假设你能看到人体内所有的基因,你应该会感到震惊。他们中只有1%是人类。另外99%属于细菌、酵母、病毒和微小的原生动物。这些微生物被称为微生物群,它覆盖着你的全身内外。 可以说,潮湿温暖的肠道环境是地球上最拥挤的空间之一。它容纳了大约上千种不同的微生物物种,其所含基因远超过我们的人类基因。 肠道微生物与我们相依相伴 神奇的是,这些微生物及其基因会影响我们的爱情生活,帮助我们像应用程序一样挑选相配的伴侣。取决于你的微生物群状态,这可能是好事,也可能是坏事。 人类可能需要花费数千年的时间才能改变基因,但是微生物可以在20分钟左右的时间内产生新一代的基因泵送的同胞细胞。然后微生物围绕着我们发展进化圈,古老的防御体系,我们的身体要不断为这些变化的微生物创造环境。 因此,在原始时代的某个时候,我们募集了有益的细菌来保护我们免受致病菌的侵害。在潮湿和温暖的环境中,微生物通过抵抗病原体来保护我们,这种关系使我们在充满病原体的世界中成长 。 这种共生有多重要?所有的动物都不遗余力地将选定的微生物传给它们的孩子,例如小马会去吃马妈妈的便便,因为它需要摄取母亲粪便中的微生物。 在人类中,产道为早期微生物的形成提供了的途径。母乳中含有的细菌会进一步建立婴儿的初始肠道微生物群。母乳甚至含有专门为喂养这些微生物而生产的益生元。 然而,我们的肠道微生物(统称为微生物群)也有自己的需求-并且他们知道如何满足。 微生物是情绪和行为操纵器 令人惊讶的是,微生物可以产生人类神经递质,包括多巴胺和5-羟色胺,这是目前抗抑郁药物最流行的两个目标。微生物也会产生激素和脂肪酸,所有这些都是有效的情绪操纵器。 再加上细菌毒素和微生物,对他们的宿主有着强大的控制能力。你是不是认为自己有意识地决定爱吃甜食?不,很可能你的微生物才是真正的甜食渴望者,并且你的欲望已经被塑造成可以满足它们的欲望。 事实是,肠道微生物并不是我们的“朋友”,它们是我们共同用餐的伙伴,但随时都可以帮助我们。 它们都有自己的食欲:酵母渴望糖;拟杆菌属(Bacteroidetes)会喜欢脂肪;普雷沃特菌属则比较喜欢碳水化合物;双歧杆菌是纤维爱好者。 它们都有自己的方法来讨好自己喜欢的,使用两种基本技术的变化来影响我们的食物选择 。 如果我们不给它们想要的东西,微生物就会产生毒素,使我们感到不舒服,因为他们知道如何使我们痛苦。 微生物通过改变我们的味蕾,增加阿片和大麻素受体以及产生神经递质(如多巴胺和5-羟色胺)来增加我们对食物的渴望。也是因此他们也知道如何使我们快乐 。 如果微生物能够指导我们的行为,那么他们还能做什么?从微生物的角度考虑,为了扩大其领土,它们可能会驱使我们更多地社交。从微生物的角度来看,有什么比亲吻,握手或拥抱更好的传播途径呢? 从果蝇开始的研究 以色列2010年的一项研究将一批果蝇分成了两组。他们给一组喂以糖蜜为食的饮食,另一组为淀粉。每组都建立了合适的微生物群,经过精心调整以消化各自的饮食。 然后,他们在交配室中把这四个混合在一起(每组取一对)。一个交配室实际上只是一个很小的塑料碗,上面有透明的盖子,这样研究人员就可以算出性行为。 具有相同微生物群的果蝇更有交配意向 尽管所有果蝇之间都可以完全通行,但他们还是希望与具有相同微生物群的果蝇交配 。 从几十代来看,果蝇一直生活在自己的群体中,基本上是两个独立的物种。那么有人问,怎么知道这是由于微生物引起的,而不仅仅是呼吸中有糖蜜的气味?答案很简单:当研究人员给果蝇使用抗生素杀死其微生物群时,他们的偏好就消失了。 细菌不会产生性信息素,但会调节其信息素 首席科学家 尤金·罗森伯格(Eugene Rosenberg)说:“共生细菌可通过改变性信息素(sex pheromones,在哺乳类动物中通过唾液,汗液和尿液释放)水平来影响果蝇交配偏好。细菌不会产生性信息素,但会调节其信息素。” 信息素是一种神秘的化学物质,可以起性吸引剂的作用。昆虫会嗅到其中的单个分子而飞走数英里。它显示了微生物群对于交配选择的重要性。 研究从果蝇走向人类 罗森伯格在后续论文中提到,蝇类并不是唯一被微生物操纵配偶选择的动物:“细菌对人类和其他动物的嗅觉有影响,而嗅觉是选择性伴侣的重要输入。” 可以这样理解,你的细菌将皮肤油脂转化为属于你自己的脂肪酸混合物,从而决定了你的气味。这是你的“特定味道”。 罗森伯格及其小组进一步推测,婴儿的抗生素治疗可能会影响这种情况,并可能导致菌群的流失和产生不同的气味 。 早期使用抗生素会影响未来的爱情生活?这种猜测令人担忧,但罗森伯格认为,通过谨慎地在抗生素使用后重新繁殖微生物群,这种情况可能会逆转。 微生物和激素 从客观上看,性有时让人满头大汗,但我们还是设法克服了这一点。细菌也可能通过操纵我们的激素发挥作用。 就像动物一样,微生物利用激素彼此交流 。这些化学物质可以帮助我们改善性生活。例如催产素,参与保持身体健康,也和快速愈合有关,但它也在社会关系中发挥作用。催产素是“荷尔蒙激素”,它可以帮助我们忽略性的不便,得以繁衍后代。 这对微生物来说,也是一个巨大的胜利,因为性可以帮助它们找到新的人类领土。接吻可以使它们的生活更美好:亲密接吻每秒可在参与者之间转移800万细菌 。 摄入益生菌如罗伊氏乳杆菌可提高体内催产素的水平 。看到这,你是不是想赶紧去买益生菌补充剂了?别急,高纤维食物也可以提高自己的罗伊氏乳杆菌水平。 嗅出灵魂伴侣 伴侣的选择还受微生物自身免疫系统的影响。主要的组织相容性复合体(MHC)由免疫蛋白组成,这些免疫蛋白为我们每个人提供了独特的气味特征。MHC蛋白是通过与微生物接触而产生的,代表了与病原体战斗的浓缩版本。 从理论上讲,我们无意识地选择了拥有完全不同的MHC的伴侣。这意味着将补充我们自身,有效地使我们对病原体的抵抗力加倍。 当你选择一个具有兼容的MHC特性的伴侣时,它们会让你闻起来很友好。如果你有孩子,他们就会在健康的微生物群上有一个良好的开端。 已婚夫妇如何影响彼此的身体健康 已婚或同居伴侣可以在很大程度上影响彼此的压力水平,情绪和健康行为方式。这意味着配偶不快乐或不健康,或敌对婚姻会让你更不健康。 当然另一方面,你的伴侣可以起到积极的作用,让你更活跃,减轻体重或减少饮酒,从而有可能改善您的身体健康。 一个最近的评论文章俄亥俄州立大学的Janice Kiecolt-Glaser及其同事的研究表明,婚姻互动,配偶情绪和生活方式习惯对健康的影响可能是通过肠道来介导的 。 最近,研究人员已更加意识到人体中,肠道是与大脑,免疫系统和心血管系统(通过迷走神经)进行通讯的中心枢纽。 研究表明,抑郁,饮食,睡眠,压力和敌对的婚姻相互作用会减少肠细菌的生物多样性,或使肠屏障更具渗透性,并更有可能使炎性因子渗入血液(称为“渗漏性肠”)。 肠道菌群多样性较低或肠道泄漏较多,会增加您对慢性炎症,肥胖症和糖尿病或心脏病等慢性疾病的抵抗力。因此,与伴侣生活在一起可能会以更多的你想象不到的方式影响肠道和整体健康 。 在一起生活为什么会影响这些因素?事实证明,身体互动,触摸,亲吻和性行为促进了微生物群的共享。肠道菌群与心血管疾病或糖尿病的许多危险因素有关,包括葡萄糖代谢,体重指数,腰围和高密度脂蛋白。 共享的压力源,情绪和健康习惯 促进已婚夫妇健康风险相似性的另一个因素是,他们可能共享共同的压力源,或者受到彼此情绪和压力水平的影响。无论是面对共同的压力源(例如经济压力或生病的孩子),还是伴侣将工作压力带回家,压力都具有传染性。 婚姻中的冲突,压力或敌意也可能影响您的情绪并增加皮质醇水平。伴侣也容易受到彼此健康或不健康行为和睡眠方式的影响。 研究表明: 拥有沮丧的伴侣会使你患抑郁的风险加倍。 不幸福的夫妻比幸福的夫妻更难消除负面情绪和压力。 伴侣有慢性睡眠问题的人有的炎症水平更高。如果你的伴侣在晚上醒着,可能会打扰你的睡眠。 肠道菌群,肠道渗漏和慢性炎症 一个健康的肠道具有多种细菌或病毒,它们分布均匀,没有一个物种能占主导地位。研究表明,菌群多样性低的人比菌群多样性高的人更容易发生慢性炎症。一些研究表明,饮食习惯也会影响微生物群的多样性。 与西方饮食相比,传统西方饮食富含红肉,精制糖和饱和脂肪,而微生物多样性较低,而地中海饮食则更多地依赖植物和健康脂肪。高饱和脂肪饮食还可以增加肠道的通透性,使毒素和炎性物质更有可能渗入您的血液中。 从婚姻敌意到全身性炎症的途径 一项研究表明,对婚姻的看法更加敌对的夫妇减少了肠道微生物的多样性,并增加了不健康的饮食习惯。在这项研究中,研究人员通过对脂多糖结合蛋白(LBP)进行评估,对婚姻状况进行了录像和编码,并测量了微生物的多样性。具有更多敌对性的夫妻的LBP较高,这又与C-反应蛋白(炎症的标志物)的水平较高有关。 因此,这项研究显示了通过减少肠道生物多样性,从婚姻敌意到全身性炎症的途径。此外,较敌对的夫妇的饮食中饱和脂肪含量较高,这可能会影响肠道微生物并增加炎症 。 配偶比兄弟姐妹具有更相似的微生物群 一项美国的研究,针对威斯康星州人群的研究,对配偶(N=94)和兄弟姐妹对(N=83)的分析进一步表明,配偶比兄弟姐妹具有更相似的微生物群和更多共同的细菌类群,在兄弟姐妹和不相关配偶之间没有观察到差异。即使考虑到饮食因素,这些差异仍然存在。 结果表明,人与人之间的互动,特别是持续的密切婚姻关系,会影响肠道菌群。已婚个体所拥有的微生物群落相对于独居者具有更大的多样性和丰富性,具有亲密关系的夫妻具有最大的菌群多样性,鉴于数十年来的研究记录了婚姻对健康的益处,这点值得注意 。 可以看到,具有亲密关系的夫妻其菌群多样性更高,而且存在显著差异。 夫妻之间的肠道菌群相似度也超过兄弟姐妹和不相关人群。 虽然饮食通常与胃肠道微生物群相关,但亲密关系表明人类互动和共同行为的影响较少得到理解。紧靠和频繁的身体接触与促进相似个人之间直接微生物共享灵长类动物中微生物的相似性是相关的。 在这项研究中,亲密关系可能代表了在一起度过的时间,身体情感以及其他可能导致微生物共享的人类互动的总和。事实上,有证据表明唾液微生物群影响肠道微生物群,而唾液微生物群可能受接吻的影响。 高质量婚姻可能有助于微生物 通过进一步分析共享的菌发现,有趣的是,这些潜在共享的OTU中的大多数都来自严格厌氧的分类单元,这表明在宿主之间的富氧环境中持续存在可能不是密切人际关系的传播限制因素。 我们进一步发现,不仅已婚夫妇具有更多相似的肠道菌群,而且已婚个体所拥有的微生物群落相对于独居者更具多样性和丰富性。亲密的婚姻关系比兄弟姐妹之间共享的遗传因素和早期生活环境影响更大。 这一发现之所以有趣,部分是因为它与大量证据相吻合,证明了高质量婚姻与发病率和死亡率之间的牢固联系。未来可能会试图弄清将密切关系与微生物成分联系起来的机制。例如,尽管我们没有发现证据表明饮食共享是造成这些发现的主要原因,但我们无法测试精确的身体接触和亲密关系频率作为替代性解释机制。 菌群预测家庭关系 通过评估共有菌群来预测区分家庭和夫妻配偶,预测家庭模型的整体性能较差,但这些预测似乎仍依赖于网络结构,因为在肠道和口腔样本中,某些家庭内部的所有关系都得到了准确的预测。 值得注意的是,模型表明,近25%的配偶非常容易以高置信度进行预测。为什么某些夫妻比其他夫妻更容易预测,这可能反映出共同的敏感性,特定行为或婚姻关系的相对重要性 。 改善伴侣关系 1. 共同努力,让生活更健康 当你和伴侣同时工作以减轻体重,多睡,多运动,少喝酒时,更有可能互助成长。看到伴侣变得更健康可以激励你去做同样的事情。 2. 更加富有同情心和相互尊重,而不是敌对地进行沟通 记住,你们是站在同一边的。请注意,对话如果朝消极方向进行,请稍作休息。尝试降低防御力,保持耐心,减少批评。 3. 如果你的伴侣在工作,家庭或育儿方面有压力,请尝试提供帮助并给予支持 最终,压力较小的配偶对你们俩来说都意味着更好的健康。如果尽管您尝试帮助您的伴侣仍然感到压力,则应集中精力分散自己,锻炼,冥想或进行愉快的活动,以减轻压力。 4. 另外,请确保了解您的肠道菌群和拥有良好的菌群 这样可以帮助你拥有美丽的皮肤,光亮的头发,毕竟健康的人自带魅力。 要调整您的微生物群,以下简单步骤供参考: 1. 多吃富含纤维的蔬菜,包括芦笋,朝鲜蓟,西兰花和韭菜。纤维可以喂养有益的微生物,从而阻止病原体。 2. 多吃含有抗氧化剂的深色水果,例如樱桃和蓝莓,可帮助您应对炎性病原体。 3. 尝试酸奶和益生菌益生元等含有微生物的发酵食品。 4. 偶尔吃一点鱼;它具有抗炎的omega-3油。 5. 做些运动,对微生物群有很好的效果。 6. 了解和重视肠道菌群检测 有了健康的微生物群,你会处于健康状态,并选择了与微生物相容的伴侣,它们可能会比任何约会应用程序更能帮助你找到良好合适的伴侣。 欢迎关注:谷禾健康 ——让你和你的家人更健康 参考文献 1. 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Sharon, Gil, Daniel Segal, Ilana Zilber-Rosenberg, and Eugene Rosenberg. “Symbiotic Bacteria Are Responsible for Diet-Induced Mating Preference in Drosophila Melanogaster, Providing Support for the Hologenome Concept of Evolution.” Gut Microbes 2, no. 3 (June 2011): 190–92. 7. Stabb, Eric V. “Could Positive Feedback Enable Bacterial Pheromone Signaling To Coordinate Behaviors in Response to Heterogeneous Environmental Cues?” MBio 9, no. 3 (July 5, 2018): e00098-18. 8. Kort, Remco, Martien P. M. Caspers, Astrid van de Graaf, Wim van Egmond, Bart J. F. Keijser, and Guus Roeselers. “Shaping the Oral Microbiota through Intimate Kissing.” In Microbiome, 2014. 9. Varian, Bernard J., Theofilos Poutahidis, Brett T. DiBenedictis, Tatiana Levkovich, Yassin Ibrahim, Eliska Didyk, Lana Shikhman, et al. “Microbial Lysate Upregulates Host Oxytocin.” Brain, Behavior, and Immunity 61 (March 2017): 36–49. 10. Kiecolt-Glaser JK, Gouin JP, Hantsoo LV (2010). Close relationships, inflammation, and health. Neuroscience and Biobehavioral Reviews. Close relationships, inflammation, and health.Neuroscience and Biobehavioral Reviews. 35, 33-38. PMC2891342 11. Melanie Greenberg Ph.D. How Married Couples Influence Each Other’s Physical Health. psychologytoday. 2019.10 12. Dill-McFarlandKA,TangZZ,KemisJH,etal.Closesocialrelationshipscorrelatewithhumangutmicrobiotacomposition.SciRep.2019;9(1):703.Published2019Jan24.doi:10.1038/s41598-018-37298-9 13.BritoIL,GurryT,ZhaoS,etal.Transmissionofhuman-associatedmicrobiotaalongfamilyandsocialnetworks.NatMicrobiol.2019;4(6):964-971.doi:10.1038/s41564-019-0409-6 本文转自谷禾健康
万事万物皆有缘起,2019年的因缘际会使我了解到了真菌的奇妙,遂将其当作一种美妙的追求和学术偏好。 就如一位将军对于军队的重要性,亦如蜂后对于蜂群的重要性,亦如船长对于一艘船的重要性,重要的东西不一定要多,不一定要稠密,但仍然是核心,仍然是一个众望所归的亮点。 真菌在人类肠道中极其少,可以说微乎其微,因此,很多人甚至认为它不存在长久定植的情况,其它人则认为他们只有致病性。本着对权威的不屑,以及对于地球千万年来进化的敬畏,本人与Wahlqvist教授随即突发奇想,经历半年的讨论,提出 'regulobiosis' 猜想,即真菌才是人体生态中至关重要的王者,他们调控、稳定着我们的细菌,我们的病毒,我们的整个人体微生态,直至我们人体本身的健康;同时,他们又对我们的饮食和环境及其敏感,他们也为全球变暖大环境下人类的可持续生存提供了无限可能。 相信基于mycobiome的regulobiosis系统会在不久的将来展现光芒。 Reference: Ju-Sheng Zheng, Mark L Wahlqvist. Regulobiosis: a regulatory and food system-sensitive role for fungal symbionts in human evolution and ecobiology. Asia Pacific Journal of Clinical Nutrition 2019; http://doi: 10.6133/apjcn.201912/PP.0007 原文链接: http://www.apjcn.org/pdf/321921203.html?t=2
在生态系统中,排放含有重金属的制革废水是当今社会面临的最重要的环境和健康挑战之一。 重金属无法进行生物降解,且对微生物具有毒性作用,仅有少数微生物对重金属的抗性和解毒作用。 因此,针对被排放到环境中的无机金属(铬、汞、镉和铅),人类社会需要更多地开发新式、高效、环保以及紧急的生物修复法,从而保护整个生态系统。 近期,Hindawi的开放获取期刊 Journal of Toxicology 发表了一篇 高被引文章 :Toxicity and Bioremediation of Heavy Metals Contaminated Ecosystem from Tannery Wastewater: A Review 。 该文对微生物的生物修复能力做出了重要的评估,特别是在环境保护方面。此外,本文还探讨了利用细菌、真菌、生物膜、藻类、基因工程微生物(genetically engineered microbes)和固定化微生物(immobilized microbial cell)细胞去除重金属生物吸附的能力。在污染微生物的重金属方面所取得的最新突破推动了生物修复技术的进步,使其有望成为传统技术的替代方案。 Figure 1: Mechanisms of heavy metal uptake by microorganisms 在移除重金属方面,生物膜的使用已经显现出了协同效应。作为可持续的环境技术,生物膜有望在不久的将来实现重金属去除的高效化。 点击查看阅读原文 由查尔斯沃思集团(Charlesworth Group)统筹翻译。
晕了,绞尽脑汁也想象不出来表面粗糙度与atomic level有何关系,不过 atomic还有“极微的、微小的、微粒的”意思 。 请问有没有哪位老师知道下面红色字体是什么意思? 如果译成““从原子尺度上来看(矿物)表面粗糙度,(矿物表面上)存在(生长)台阶、扭折、空位等缺陷”,是否正确? 敬请赐教!谢谢! In order to have a proper understanding of mineral surfaces, interfaces, and interfacial processes, we need to address a number of questions. These include: whether and how a pristine mineral surface (growth or cleavage) differs from a simple truncation of the bulk crystal structure in the arrangement of its atoms; the roughness of the surface down to atomic level and the presence of steps, kinks, vacancies and other defects ; the chemical composition of the fresh surface, before and after interaction with air, aqueous fluid, organic species or microbe, and the nature of the actual interface between mineral and fluid, organic or microbe.
Nature—— 微生物感染和 TLR4信号通路激活可能引起脑海绵状血管畸形 Abstract 1.CCM formation is stimulated by GNB infection and intravenous LPS injection. 2.CCM lesion formation requires endothelial TLR4/CD14 signalling. 3.Increased TLR4 or CD14 expression is associated with higher lesion number in familial CCM patients. 4.CCMs fail to form in most germ-free mice. 5.CCM susceptibility is associated with increased levels of Gram-negative Bacteroidetes s24-7.
这两天,中新网西安新闻报道了当地环卫部门公布了“以克论净”的城市道路标准,有网友表示:“大街都扫这么干净,我的小窝都不好意思住了!”;“街道搞这么干净,这不是难为环卫工人吗?”据了解,除西安外,山东、河北、重庆等地也出台过相关规定。然而,这样的严格的卫生活动可能并不会对人民的健康有多大促进作用,还可能起反作用! 科学研究表明,太干净了,反而不利于健康!不让接触土,人民不答应。 农场里的“脏孩子”免疫力更强 哮喘通常始于婴儿时期,有研究显示那些在生活在北欧,在传统农场环境下长大的孩子对哮喘和过敏有天然抵抗力。而在城市中长大的孩子,家中比较干净,一尘不染的环境导致其中尘埃里的细菌较少,尘埃中的LPS含量与这些孩子哮喘发病风险密切相关。这可能是由于农场环境比较脏,土壤,尘埃中含有的大量微生物,其中的细菌脂多糖(LPS)可能帮助这些孩子提高了天然抵抗力。 吃奶猪接触土壤,肠道菌群早成熟,免疫力更好 不光人接触土壤少了,现在养殖的猪也更难接触到土壤了。它们几乎终生都生活在围栏里,有些一生都没接触过土壤。 猪的本性就是爱玩土,玩泥,接触不到了身体自然不健康,必须用大量的抗生素来抗病。最近的研究显示,在猪的哺乳期给它们提供接触表层土的机会,模拟自然状态下早期菌群暴露的过程,在产后第4天到哺乳期结束持续让它们接触土壤环境。结果发现,在接触土壤的仔猪体内,与饮食转换(从母乳到植物为主的饮食)相关的肠道菌群的能够更快的成熟,这些猪可以更快的适应食物转换过程,出现肠道疾病的比例也低。普氏菌属和厚壁菌门的许多成员在饮食转换过程中能够快速显著富集。 人类是不是也这样呢?养过娃的人都碰到过食物转换过程中出现的孩子便秘腹泻的情况。是不是可以在出生后多让孩子接触土壤,让他们肚子里的菌快速发育成熟,从而快速适应环境。我估计实行起来非常困难,现在的孩子太“金贵”了,家长恨不得把孩子的环境都变成无菌的,孩子吃的用的都得消毒,让他们接触土,想都别想! 生活中城市中的人,丢失了大量共生微生物 在城市化及工业化进程中,人类的生活环境大幅提高,生活质量也好了,然而,相关的疾病也增加了。有研究调查了不同地理区域(欧洲、北美、亚洲、大洋洲)人群的的肠道菌群构成,其中包含13个发达国家(工业化社会)和2个传统的狩猎国家(农业社会前,坦桑尼亚和秘鲁)。结果发现,发达国家的人的肠道菌群多样性比狩猎国家的人要少很多,丢失了很多独特的菌。自从人类从农业社会迈入工业社会,人类丢失了大量的肠道共生菌群,并且一些菌的功能也发生了巨大变化,可能这些菌和整体功能的丢失对人类健康产生了显著影响。 环境越干净越好吗? 俗话说“不干不净,吃了没病”,是有道理的。现在的研究发现,环境微生物对人的免疫系统发育和平衡至关重要。“卫生假说”认为,太干净的环境,缺乏微生物的刺激,导致儿童免疫系统发育障碍,过敏,哮喘等都与“太干净”有关。随着城市化进程加快,环境越来越干净,土地越来越少,水泥路,柏油路越来越多,人们正在远离尘土,远离微生物。与之相伴的是,我们发生感染的比例越来越高,过敏症,哮喘,以及多种炎症性疾病,甚至焦虑,抑郁等精神类疾病的发病率也在持续增加,这一切可能都跟我们生活的环境太干净有关。 不要剥夺人民接触微生物的权利 由于微生物对维持人体健康至关重要,我们的人民,特别是生活在城市的人需要更多的接触微生物,接触土壤。ZF的初衷是好的,但是这种近乎苛刻的卫生标准实际上正在 剥夺人民接触微生物的权利。为了感官的卫生干净,牺牲自己或者后代的健康,长远来看未必是好事。 留点机会给人民接触土壤吧!路上的土也是土啊! 一起来看看,究竟要多干净? 西安碑林区柏树林街道环卫所所长兰有刚25日在接受中新网记者采访时表示,在城市道路设施完好的情况下,只要认真清扫,该辖区道路基本都能达到“以克论净”这一标准。西安市道路清扫保洁等级划分为:重点区域(每平方米灰尘分别不超过5克)、一级(10克)、二级(15克)、三级道路(20克),道路清扫保洁质量应达到“道牙无尘,路无杂物,设施整洁,路见本色”的质量标准。考核也不马虎,真带着电子秤,按克称重。为了公正,操作时还会选三个不同点收集尘土称重,取中间值来判断该路段是否达标。 来看看考核人员的认真程度吧。小刷子都用上了。 62岁的环卫工王观海负责的是三级道路,但要保持合格还是会每天至少要扫四五遍,从清早4点起来差不多要干到下午6点。检查结果与她每月的绩效工资挂钩,如果三次不达标则就会罚款。 参考资料: Holt P G, Sly P D. Environmental Microbial Exposure and Protection against Asthma. . New England Journal of Medicine, 2015, 373(26):2576-2578. Nguyen V, Tsai T C, Maxwell C, et al. Early exposure to agricultural soil accelerates the maturation of the early-life pig gut microbiota . Anaerobe, 2017. Mancabelli L, Milani C, Lugli G A, et al. Meta-analysis of the human gut microbiome from urbanized and pre-agricultural populations. . Environmental Microbiology, 2017, 19.
在人体的体表和体内分布有大量的微生物,主要分布在消化道、呼吸道、皮肤、生殖道、眼睛等和外界相通的器官。其中,人们对生殖道和子宫中的微生物了解较少。人类的繁衍依赖于这个系统,从受精卵到胎儿都会受到其中的微生物的影响。 子宫内膜中有什么菌? 近期的一篇文章 采用 宏基因组样品的分析技术, 对 子宫中的微生物进行了 分析,不仅发现人体生殖道并非是过去认为的那样是无菌的,并且鉴定出了正常及异常的阴道与子宫内膜菌群。 研究发现,子宫内膜液中含有多达191个OTU的微生物,以乳杆菌为主( 90%是乳杆菌属),其它的为非乳杆菌属的细菌。子宫内膜中非乳酸杆菌会随着 怀孕,生产 等显着减少相关。结果表明子宫内膜微生物群处于高度稳定,并受外环境影响。 胎盘里也有多种微生物,组成与口腔接近 2012年, 美国休斯顿贝勒医学院妇产科学系 Kjersti Aagaard教授发现孕妇阴道内的微生物组成与未怀孕女性阴道内微生物组成有比较明显的区别。同时,这种微生物组成又与胎儿粪便中的成分有很大的不同。 她们还发现 胎盘中竟然也存在微生物 。胎盘的微生物组成与产道微生物不同,与口腔最为接近。估计胎盘微生物的数量在数千到十万级。 产道和子宫中的微生物可能影响生育 阴道和子宫中的微生物群可能会对生育产生影响,在从受精卵发育成胎儿到出生的过程中,微生物会通过其代谢产物或直接参与发育过程。虽然,我们对其中的机制并不清楚,目前的研究已经发现这些部位的微生物组成的变化与这些部位的病理改变会影响受精过程,影响生殖。 这些发现为生殖过程增添了一个新颖的微生物学维度。到目前为止,人们对人体生殖道菌群的了解还十分有限,更好地理解生殖道菌群失调对生育健康宝宝至关重要。 参考资料: 1,Franasiak J M, Scott R T. Endometrial microbiome . Current Opinion in Obstetrics Gynecology, 2017. 2,Moreno I, Codoñer F M, Vilella F, et al. Evidence that the endometrial microbiota has an effect on implantation success or failure . American Journal of Obstetrics Gynecology, 2016, 215(6):684. 3,Pelzer E, Gomez-Arango L F, Barrett H L, et al. Maternal health and the placental microbiome . 2016. 4,Cao B, Stout M J, Lee I, et al. Placental Microbiome and Its Role in Preterm Birth. . Neoreviews, 2014, 15(12):e537-e545. 5,Prince A L, Ma J, Kannan P S, et al. The Placental Microbiome is Altered Among Subjects with Spontaneous Preterm Birth with and without Chorioamnionitis. . American Journal of Obstetrics Gynecology, 2016, 214(5):627.e1–627.e16. 6,Ayala S, Freeman L. The Placental Microbiome: A New Site for Policing Women's Bodies . Ijfab International Journal of Feminist Approaches to Bioethics, 2016, 9. 扫一扫,关注本公众号! 肠菌与健康 microbiota health 带你了解肠道菌群与健康的奥秘!
随着人们生活方式的改变,现代 高度精制 饮食中营养质量和包含的天然膳食纤维浓度在我们的食物中逐渐降低。特别是在西方和中国的一些富裕地区,最普遍的食物之一是精制谷物做的 面包 ,并且已经成为 肠道菌群膳食纤维的重要来源。 人体胃肠道微生物作为重要的人体生态系统,对人体健康密切相关,特别是对免疫系统的调节,包括有效保护人体免受病原体感染,减少发生炎症和自身免疫性疾病风险。研究表明,遗传特征,环境和饮食是影响肠道微生物组成的主要因素。其中,最重要因素之一是饮食,尽管我们对大量营养物质的个体效应仍不清楚。 工业面包,好吃,好看又好卖 面包的发酵过程会对最终面包中的纤维含量以及碳水化合物和蛋白质的复杂性有重要的影响。传统上,天然发酵是不受控制的 微生物发酵过程,现在这种天然发酵过程已被完全控制的快速发酵的工业化加工所替代,这种工业面包的发酵过程也仅需要最多2个小时。此外,工业面包通常是新鲜冷冻的,以便更好的储存和运输,并在销售点进一步烘烤。 近年来,随着更健康和注重生态的生活方式的出现,自制面包开始使用高品质的面粉,包括未精制小麦 (全麦) 或多种类面粉。 基本上,工业面包对应于面包店中最常见的面包类型。这种面包是为了适用大批量工业生产,满足保质期,口感和产品稳定性的需求。这种面包中还会添加一下面包改良剂,已达到好吃,好看,好卖的目的。 工业面包对肠道菌群不利,引发全身性炎症 最近,有研究 比较了工业化生产的面包(精制面粉,2h发酵)和家庭自制面包(粗粮,24h发酵)对肠道微生物和全身性炎症的影响。发现 与工业面包相比,家庭自制面包可增加部分有益菌数量,增加肠道菌群多样性,减少肥胖相关的内毒素血症,调节肠道稳态;而工业化面包使菌群多样性降低,增加拟杆菌门数量,引发全身性炎症。 研究中,他们将10只雌性8周龄雄性小鼠在单独笼中饲养,收集初始的基础粪便样品。“工业”和“celta”的两种面包是由Novapan S.L. (西班牙萨拉戈萨)生产的,两者的主要特征如下图所示。然后,将标准食品与工业面包粉以1:1的比例混合,自由饲喂动物21天。在这段时间结束时,收集第二个粪便样品,称为工业面包样品。然后仅用标准饲料再饲喂7天,然后在21天内给动物饲喂与celta面包粉混合的标准食物。最后的粪便样品被命名为Celta面包样品。另外,在第0天(基础),第21天(工业)和第49天(celta)收集血样,检测促炎因子浓度。 家庭自制面包增加肠道菌群多样性 通过检测粪便中肠道微生物的组成,研究发现,与工业面包相比,家庭自制面包可增加部分有益菌数量,增加肠道菌群多样性。在门水平上,可以看到自制面包可以明显增加Verrucomicrobia菌的比例,降低拟杆菌门的比例。 在属水平上,可以看到自制面包可以明显增加Akkernansia菌和Mucispirillum菌以及Prevotella菌等的比例,Akkernansia菌被认为是潜在的具有保护作用的肠道菌。此外,自制面包可以明显降低拟杆菌,Parabacteroides等菌的比例。 肠道微生物群的改变可能影响肠道免疫稳态,导致产生促炎环境。 工业面包促进炎症指标 通过检测血液中炎症相关因子,发现工业面包可以显著增加炎症相关因子的数量,促进炎症的发生。特别是炎症相关因子,如IL-6,IL-2,IL-5, IL-13等,在工业面包处理后明显增加。 因此,食用越多的工业化面包可能越容易引发全身性炎症。 面包原料和制作工艺是主要影响 面粉有差异: 对于工业面包,面粉是经典的面包专用面粉,可以承受工厂加工过程中的机械应力,其谷蛋白含量略低,为9.1%,但其麦醇溶蛋白含量更多。工业面包小麦面粉有一个谷蛋白/麦醇溶蛋白比例为31-69%。 而Celta面包,使用的小麦面粉是高劲面粉,麸质含量为10.4%,而Celta麦面包面粉谷蛋白/麦醇溶蛋白比例为50-50%。实际上,在发酵过程中,微生物会对谷氨酸蛋白具有水解作用,在24小时内为降解率为15%。当然,Celta面包的原料也比较贵,其5欧元/公斤的价格是成本为2欧元/公斤的工业面包的2.5倍。 参与发酵的微生物有差异: 在工业生产面团中使用的酵母是一种酿酒酵母109CFU / ml。 而在家庭自制Celta面包中,发酵过程由酸面起子(面肥)发酵的,里面包含多种微生物,包括109CFU / ml的酵母菌(酿酒酵母,巴斯德毕赤酵母和假丝酵母) 和109CFU / ml的 乳酸菌 (Lactobacillus paralimentarum,Pediococcus parvulus,Lactobacillus brevis和Leuconostoc citreum) 。 没错,传统的面起子里含有大量的益生菌!并且正是由于这些乳酸菌产生的乳酸使面团变酸。正因此,传统的发酵需要加碱中和乳酸,而用酵母发酵就不用。 发酵过程不一样: Celta面包属于传统面包的“慢烘焙”系列,具有延长的发酵时间和复杂的面粉和发酵菌。 工业面包只有2h的发酵),而家庭自制面包需要24h发酵,总制作时间达到26h,制作时间可达工业面包的13倍。 人类到底需要什么样的食物? 面包是很多国家,很多人每天消费的传统食品,其对人体健康的有益作用与其成分和制造过程有关。 面包的成分和制作过程除了对肠道微生物群变化及其对我们健康的长期影响之外,还可以影响全身炎症,这必须引起人们的重视,也值得我们反思,我们人类到底需要什么样的食物。从这篇文章中,我们可以发现食材多样化,优质化,加工方式传统化,对肠道微生物友好的食物可能更利于健康。 重要的一点,便宜没好食,好食不便宜! 参考文献: 1,Arias M, Cobo M, Jaime-Sánchez P, et al. Gut microbiota and systemic inflammation changes after bread consumption: The ingredients and the processing influence . Journal of Functional Foods, 2017, 32:98-105. 2,Chassaing, B., Koren, O., Goodrich, J. K., Poole, A. C., Srinivasan, S., Ley, R. E., Gewirtz, A. T. (2015). Dietary emulsifiers impact the mouse gut microbiota promoting colitis and metabolic syndrome. Nature, 519(7541), 92–96. 3,Conlon, M. A., Bird, A. R. (2014). The impact of diet and lifestyle on gut microbiota and human health. Nutrients, 7(1), 17–44. 4,Costabile, A., Santarelli, S., Claus, S. P., Sanderson, J., Hudspith, B. N., Brostoff, J., Gibson, G. R. (2014). Effect of breadmaking process on in vitro gut microbiota parameters in irritable bowel syndrome. PLoS One, 9(10), e111225.
对于很多药物学研究,前期研究都是在小鼠身上进行的,从小鼠身上获得的结果并不能直接推测在人体也有类似的结果。因此,很多动物实验做完后还必须做人体实验才能进一步确定效果。很多时候,小鼠体内的研究结果与人体实验的结果并不一致。 实验室小鼠太干净,缺少了微生物 最近的研究表明,之所以在实验室小鼠获得的结果不能在人体上获得重复,可能是因为小鼠生活的环境过于干净,这些小鼠从未受任何感染,也就是所谓无特异病原(SPF)级别的小鼠。 SPF小鼠与自然界中的小鼠最主要的区别是它们拥有不同的微生物学特征,自然界中的小鼠微生物种类和数量要多,这些微生物可能会干扰免疫系统。 近年来的研究已经表明,微生物大量分布于人体体表和体内,其数量超过人体自身细胞,编码的基因数量是人体自身细胞的几百倍。这些微生物影响人体健康的方方面面,微生物对人类的免疫和代谢、生殖和发育、大脑和神经发育、心理和行为、疾病和健康都有影响。 缺少的微生物影响免疫系统 对于自然界的小鼠们来说,它们的免疫系统一直曝露在各种病原体之下。人类自身免疫系统也会受微生物影响,如果我们贸然将从SPF无菌小鼠研究中得出结论应用于人类,我们可能会犯很大错误,人类不可能生存于无菌环境中。 如果实验室里的小鼠从来没有被小鼠巨细胞病毒(野生小鼠非常常见)感染过,那么它们的免疫反应就比较弱,当面对其它致命细菌的感染时就容易生病。这些小鼠中常见的病原体很可能是小鼠体内微生物环境的组成部分,会影响小鼠的健康状态。 给实验室小鼠补充微生物? 既然实验室的小鼠缺乏微生物,有人建议了,那就让实验室小鼠与更多的微生物接触呗。实际上,可以考虑让实验室小鼠和宠物店鼠共同生存一段时间,会使它们身体上获得不同的微生物。但是,无论如何,小鼠身上的微生物与自然界的也是存在差异的,与人类的微生物也不一样,因此,实验室的研究还必须经过人体实验才能说明问题。 参考文献: 1,Tao L, Reese T A. Making Mouse Models That Reflect Human Immune Responses . Trends in Immunology, 2017, 38:págs. 181-193. DOI: 10.1016/j.it.2016.12.007 2,Kelly Gouveia Jane L. Hurst,Optimising reliability of mouse performance in behavioural testing: the major role of non-aversive handling, Scientific Reports 7, Article number: 44999 (2017)。doi:10.1038/srep44999
人体微生物相关研究突发猛进,原来都被人民看作不利人体健康的细菌们居然大量分布于人体体表和体内,其数量超过人体自身细胞,编码的基因数量是人体自身细胞的几百倍。近年来的研究显示,母乳中存在多种细菌,母乳相关菌群是在婴儿肠道中定殖的第一批细菌,对婴儿的健康有长期及短期的影响。 乳汁中含有近千种细菌,每毫升达百万个 人们原来认为无菌的乳汁中,居然也有近千种细菌。来自西班牙的科学家报道了一组有意思的研究,母乳中含有超过700种细菌,这些细菌首先进入婴儿体内,帮助他们建立肠道共生菌系统,增强免疫力,维护宝宝健康。母乳除了给婴儿提供营养,还提供了多种细菌,特别是葡萄球菌属、链球菌属及假单胞菌属。母乳中菌群来源包括母亲的胃肠道菌群,及哺乳期间乳房的细菌暴露。研究人员采用高通量DNA测序技术研究了初乳和后续的乳汁,发现在初乳中含有较多的Weissella, Leuconostoc, Staphylococcus, Streptococcus和Lactococcus,之后的乳汁,一个月和六个月后则出现口腔中特有细菌,如Veillonella, Leptotrichia和Prevotella等。母乳中的细菌数量可达 百万个每毫升。 中国妈妈的乳汁中都含有什么菌? 有研究专门调查了中国城市中生活的哺乳期母亲的母乳菌群组成,发现无论用标准非无菌取样,还是无菌取样,链球菌Streptococcus和葡萄球菌Staphylococcus都是优势物种,其中在标准取样方法中,不动杆菌是优势属。但是,用标准方法取样的母乳中细菌数量更多。实验中还发现,双歧杆菌和乳酸杆菌只在很少的样本中丰度比较低。 不同国家母乳中含的细菌有差异 母乳中的细菌收到地理位置影响,有研究对比了来自欧洲、非洲及亚洲的4个不同国家,在哺乳期开始1个月后的母乳样本,发现顺产母亲的母乳菌群中,西班牙母亲的拟杆菌含量最高,而中国母亲的放线菌含量最高。多元不饱和脂肪酸在不同国家的母乳中不同,n-6多元不饱和脂肪酸在中国母亲中含量最高。此外,还发现,单一不饱和脂肪酸与变形菌门负相关,与乳酸杆菌相关。说明,不同地方的人的母乳菌群及脂质的组成不同。 母乳中的细菌是人体共生菌,不必担心 母乳中有细菌,即使数量很多也不用担心。这些菌是与人体共生的,母乳中的细菌数量与免疫细胞的数量不相关,说明母乳细菌并不被免疫系统视为感染源,它们是共生关系。 母乳菌群组成可能受到遗传因素、母亲健康及营养状况、分娩方式、哺乳期以及地理位置等很多因素的影响。母乳中含有的大量微生物对婴儿健康十分重要。但是,目前还不清楚母乳菌群的具体影响因素。 妈妈越重,刨腹产,母乳中细菌越少 有研究还发现一个有意思的现象,体重超重的妈妈或者分娩后增重较多的妈妈乳汁中含有的细菌种类越少。另外,分娩方式也会对乳汁中细菌有影响,剖腹产的妈妈乳汁中的细菌种类要比顺产的妈妈乳汁中细菌要少。因此,保持好的体型,尽量选择顺产,母乳中就会有更多的有益菌能够传递给孩子。 “人造母乳”的希望 母乳相关菌群是在婴儿肠道中定殖的第一批细菌,对婴儿的健康有长期及短期的影响。婴儿体内的细菌能够帮助他们消化母乳,还能帮助他们建立免疫系统。科学家对这些细菌的进一步研究,能够帮助我们建立更接近母乳的配方奶,为那些不能得到母乳喂养的孩子提供最好的营养建议。 参考文献: Fitzstevens J L, Smith K C, Hagadorn J I, et al. Systematic Review of the Human Milk Microbiota . Nutrition in Clinical Practice Official Publication of the American Society for Parenteral Enteral Nutrition, 2016. Mcguire M K, Mcguire M A. Got bacteria? The astounding, yet not-so-surprising, microbiome of human milk . Current Opinion in Biotechnology, 2017, 44:63-68. Sakwinska O, Moine D, Delley M, et al. Microbiota in Breast Milk of Chinese Lactating Mothers . Plos One, 2016, 11(8):e0160856. Alba B A, Collado M C, Alex M. Relationship between Milk Microbiota, Bacterial Load, Macronutrients, and Human Cells during Lactation: . Frontiers in Microbiology, 2016, 7(e57782). R. Cabrera-Rubio, M. C. Collado, K. Laitinen, S. Salminen, E. Isolauri, A. Mira. The human milk microbiome changes over lactation and is shaped by maternal weight and mode of delivery. American Journal of Clinical Nutrition, 2012; 96 (3): 544 DOI: 10.3945/ajcn.112.037382
Global pattern of plant utilization across different organisms: Does plant apparency or plant phylogeny matter? 跨生物类群的全球植物利用格局:植物显见度或植物谱系是否重要? - Dai - 2017 - Ecology and Evolution - Wiley Online Library http://onlinelibrary.wiley.com/doi/10.1002/ece3.2882/full Abstract The present study is the first to consider human and nonhuman consumers together to reveal several general patterns of plant utilization. We provide evidence that at a global scale, plant apparency and phylogenetic isolation can be important predictors of plant utilization and consumer diversity. Using the number of species or genera or the distribution area of each plant family as the island “area” and the minimum phylogenetic distance to common plant families as the island “distance”, we fitted presence–area relationships and presence–distance relationships with a binomial GLM (generalized linear model) with a logit link. The presence–absence of consumers among each plant family strongly depended on plant apparency (family size and distribution area); the diversity of consumers increased with plant apparency but decreased with phylogenetic isolation. When consumers extended their host breadth, unapparent plants became more likely to be used. Common uses occurred more often on common plants and their relatives, showing higher host phylogenetic clustering than uncommon uses. On the contrary, highly specialized uses might be related to the rarity of plant chemicals and were therefore very species-specific. In summary, our results provide a global illustration of plant–consumer combinations and reveal several general patterns of plant utilization across humans, insects and microbes. First, plant apparency and plant phylogenetic isolation generally govern plant utilization value, with uncommon and isolated plants suffering fewer parasites. Second, extension of the breadth of utilized hosts helps explain the presence of consumers on unapparent plants. Finally, the phylogenetic clustering structure of host plants is different between common uses and uncommon uses. The strength of such consistent plant utilization patterns across a diverse set of usage types suggests that the persistence and accumulation of consumer diversity and use value for plant species are determined by similar ecological and evolutionary processes. Dai X , Zhang W , Xu J , Duffy KJ , Guo Q . Global pattern of plant utilization across different organisms: Does plant apparency or plant phylogeny matter? Ecol Evol . 2017 ; 7 : 2535 – 2545 . https://doi.org/10.1002/ece3.2882
虽然,目前人体微生物相关的研究主要时围绕肠道和肠道微生物进行的,实际上,除了肠道,人体其它部位的微生物以及微生物对身体其它部位的影响也有许多有意思的研究。除了肠道,其它空间和地方的微生物组有什么作用? 孩子的免疫力受妈妈微生物影响--Andrew Macpherson教授 Andrew J. Macpherson是瑞士Born大学医院的消化科主任和医学教授。他的实验室主要兴趣在粘膜免疫在宿主与微生物的共生关系的影响。 Andrew J. Macpherson教授介绍了母体微生物对出生后婴儿早期免疫发育的促进(Early Postnatal Immune Development Driven by the Maternal Microbiota)相关研究。孩子的免疫力是受妈妈肠道微生物组成的影响的。妈妈的微生物产生的代谢产物通过母体影响到孩子的免疫。 人体不同部位的微生物组成不同--Lars Engstrand Lars Engstrand是瑞典卡罗林斯卡学院微生物,肿瘤和细胞生物学课题组教授,他们主要关注人体肠道微生物组,幽门螺杆菌感染与胃肠道疾病的发展。他们运用流行病学和微生物学,来研究免疫和遗传方面的慢性疾病,目的是搞清楚微生物在胃肠道中的致病机制和如何有效的进行初级预防。他们主要以宿主,微生物和环境因素的角度,运用流行病学研究和临床和基础的微生物科学,包括分子生物学和基因组学进行研究。还参与了一些正在进行的前瞻性研究,包括炎症性肠病、小儿肠道菌群定植力的建立初期等。 Lars Engstrand分享了他对身体多个部位的微生物进行的研究-为什么以及如何?(Studies of the Microbiome at Multiple Body Sites – Why and How?)。人体不同微生物的组成还是有差别的,但是不同人的同一部位的微生物组成还是接近的,肠道微生物还是身体不同部位中微生物最多的。这些微生物处在不断变化的过程中。 肠道微生物是如何影响大脑的?菌肠脑轴--Jane Foster Jane Foster实验室(http://www.jfosterlab.com/)位于加拿大麦克马斯特大学,她主要关注免疫系统,肠道菌群对大脑功能和行为的影响。使用的分子,行为,解剖和免疫学的方法,并且与临床合作,研究炎症和肠-脑在精神疾病中的作用。 Jane Foster教授介绍了超越胃肠道:肠-脑通路(Beyond GI: Gut-Brain Access)。肠脑轴是肠道与大脑沟通的通道,她俩直接的沟通是双向的,头脑影响肠脑,肠脑也影响大脑。她们之间的沟通包括5个途径。神经系统,激素系统,细胞免疫系统,代谢系统和神经递质途径。 肠道微生物影响大脑的研究最早是在无菌鼠里发现的,肠道完全无菌的小鼠表现出了心理和行为异常,同时她们的大脑结构也发生了改变。任何影响肠道微生物的因素都可能通过菌肠脑轴影响大脑。用益生菌改变肠道微生物有望用于心理疾病的治疗和预防。 运动和肌肉对肠道菌群有影响?--Jorge Ruas Jorge Ruas是瑞典卡罗林斯卡学院生理学与药理学系,分子生理学,分子和细胞运动生理学研究组组长,副教授。博士研究期间,他研究了细胞的氧含量如何调节基因的表达。后专注于控制骨骼肌生理学的转录网络的研究。 Jorge Ruas为大家分享了肠道菌群,骨骼肌和胰岛素抵抗(Beyond the Gut Microbiome: Skeletal Muscle and Insulin Resistance)的报告。实际上,肌肉里的代谢过程还与心理有关系。色氨酸的代谢过程异常可能引起抑郁。色氨酸经过肝脏代谢产生犬尿氨酸,犬尿氨酸透过血脑屏障可能引起抑郁,而肌肉细胞会消耗犬尿氨酸产生犬尿酸,而犬尿酸不会引起抑郁。也就是说运动可以缓解抑郁是通过肌肉消耗色氨酸代谢产物引起的。 扫一扫,关注本公众号! 肠菌与健康 microbiota health 带你了解肠道菌群与健康的奥秘!
11月 9日,第六届国际人体微生态大会(IHMC 2016)在美国休斯顿召开。有来自全球近二十个国家,四百多人参与了会议。多位行业顶级专家分享了各自的最新研究结果,让我们一起来看看,微生物基因组学在医学研究方面的进展。 肠道菌群影响感染性疾病 来自浙江大学的 李兰娟院士 作了长达40多分钟的开场报告,信息量非常大。 李兰娟是中国工程院院士,浙江大学医学部教授、博士生导师,浙江大学附属第一医院主任医师、传染病诊治国家重点实验室主任、国家重点学科带头人。秦楠博士和李兰娟院士曾共同在《Nature》杂志上发表了一篇关于肝硬化和肠道微生物关系的文章。 在本次开场的报告上,李院士的报告题为:肠道菌群:一种新的靶向治疗传染病的领域(Gut Microbiota: A New Territory of Therapeutic Targeting for Infectious Disease)。报告中涉及李院士在感染领域和微生物领域的研究成果,包括肠道微生物与肝脏疾病,艰难梭菌感染以及HIV病毒感染等方面的研究成果。报告中提到了最新发现的,舌头上的微生物组成在肝硬化患者中具有明显的特征。此外,她还提到了用益生菌对上述一些疾病具有一定的改善作用。 肠道微生物研究仍有许多问题需要解决---Dusko Ehrlich教授 Dusko Ehrlich教授是法国农学国家研究院(INRA)的研究人员,也是欧洲MetaHIT计划的主要实施和参与者。 在本次会议上,Dusko Ehrlich教授介绍了微生物研究面临的挑战(Challenges in Microbiome Research)。主要包括:标准化的流程仍欠缺,正常人的参考基因集需要多个地方的数据整合,临床数据和组学数据的整合,药物对肠道微生物检测结果的影响,个体的微生物的不稳定性以及微生物的恢复方法等都面临巨大挑战。 HMP项目都有哪些成果和新进展?--Owen White教授 Owen R. White是位于巴尔的摩的马里兰大学医学院流行病学和公共卫生部门的教授,也是基因组科学研究院生物信息学系主任(IGS)。这个部门的领导机构为人类微生物组计划的中央数据存储库或协调数据分析中心(简称HMP DACC)。 Owen R. White个性十足,不仅留着黑白色的胡子,左耳朵上还带着一个大耳环。在本次大会上,他分享了人体微生物组项目(HMP)的前景和走向未来的一步(Perspectives from the Human Microbiome Project and a Step Toward the Future)的报告。在这个报告中,他回顾了HMP项目的历史,以及HMP项目取得的成就。该项目用元基因组测序的方法检测了2280个样本,包括17个身体部位,3个采样时间点,还包括美国休斯顿和波士顿这两个城市。 此次的研究结果更新很多算法,注释结果有所提到,还提到了正在进行的基于多组学的人体微生物研究(iHMP)。 人体微生物研究的方向在哪里?--George Weinstock教授 George Weinstock教授是The Jackson Laboratory 的成员,关注微生物和传染病的研究,对新一代测序(NGS)技术和利用微生物宏基因组学进行传染病研究作了大量工作。开发了很多计算工具来管理基因组大数据。 在这次会议上,George Weinstock教授作了题为人类微生物组的进化研究和接下来三天的概述(Evolving Studies of the Human Microbiome and an Overview of the Next Three Days)的报告。在报告开始前,他先用几张片子介绍了一下美国大学的结果,他表示对“川普”当选表示惊讶。 在报告中,他还对比了美国的HMP和欧洲的MetaHIT的差异。HMP侧重人体健康微生物组的检测,包括多个身体部位,不同人的微生物组成。MetaHIT则侧重肠道疾病,样本只有粪便,并且提出了“肠型”的概念。 在最后,他还提出了自己对人体微生物组研究的未来方向的看法。他认为将来的研究会越来越多的依赖计算机,云计算等技术。检测方法也不仅限于测序,基因芯片,流氏细胞仪和质谱分析等。 关注微信公众号! 肠菌与健康 microbiota health 带你了解肠道菌群与健康的奥秘!
微美,唯美! 2016-09-06 ASM 微生物研究所 微生物研究所 微生物研究所 微信号 tkwsws 功能介绍 浙江省微生物研究所,直属于浙江省科技厅,是一家集技术研发、技术服务、成果转化为一体的研究型技术服务机构。 本文素材源自美国微生物学会(ASM)网站,详情可点击文末“阅读原文” 编辑整理:小静 今年6月美国微生物学会(ASM)举办了第二届微生物培养皿艺术大赛,精选出的图片不禁让人感叹原来培养皿也可以做出如此精美的画作,来欣赏下吧。 第一名 “第一次的竞速”(The First Race) 来自Md Zohorul Islam of University of Copenhagen 这幅画描绘的就是受精的过程了,虽然看起来似乎有点抽象…… 这里选用了一种特殊的选择性培养基,红色的菌落是金黄色葡萄球菌(Staphylococcus aureus,说好的金黄色呢?这里应该是因为培养基加了选择性显色的成分),绿色的是木糖葡萄球菌(Staphylococcus xylosus),黄色来自谷氨酸棒状杆菌(Corynebacterium glutamicum,它可以用来生产味精),白色的是猪葡萄球菌(Staphylococcushyicus)。 第二名 “这不是一杯啤酒”(This is not a beer!) 来自:MariarosaiaMarinaro from Rome 虽然看起来图案很简单但这个创意很有趣。这里用到的是过氧化氢酶阳性的MRSA(耐甲氧西林的金黄色葡萄球菌)。细菌的菌落画出了酒杯的图案,啤酒泡沫则是过氧化氢酶分解双氧水的结果,在局部产生了氧气泡泡。 第三名 Twelve Years of Yuck, 来自:Elena Gart and Laura Bryan from Texas AM University 这个是在一组培养皿上描绘了一系列近些年来爆发的病原微生物,构思巧妙,结合实际,组成了一部病原编年史了。 另外本届大赛还有经大众投票选出的创意作品:“细菌狼”, 来自:Baris Halac and Sevgin Canof Istanbul University 各位有没有被这些脑洞大开的创意加巧妙的设计所折服呢,其实在2015年下半年ASM举办的第一届大赛也产生过很多精美的作品,且看: 蝶恋花 梵高的星夜 水母 花非花 手掌 极简主义 抽象主义 想象 丰收季 人物肖像 纽约曼哈顿 神经元 还有一些其它作品: “黑暗面”(The Dark Side), 来自:Jeremy Weiszand Stephanie Beyer of Linfield College in McMinnville, Oregon 樱花树下的粉色火烈鸟 (AlexanderFlamingo Under a Cherry Tree) 来自:Tatsuya Akiyama and Rhonda Craver of Montana State University 怎么样,有没有想立马冲进实验室自己来创作一幅的冲动?如果你有什么创意的作品的话,欢迎通过后台发送给我们分享哦。 Visit the Agar Art Gallery during ASM Microbe 2016 in Boston (Boston Convention Exhibition Center, Level 2, Southeast Lobby) Washington, DC – June 8, 2016 – Following the success of the American Society for Microbiology’s vastly popular Agar Art contest last year, the winners of ASM’s second Agar Art contest have been announced. The contest drew widespread public interest last fall for its stunning and innovative submissions of artwork created using only microbes on agar plates. This year’s contest, enticing more entrants with the theme “plate a little culture,” has attracted even more inventive works of both art and science. “My passion for learning about microbes inspired me to participate in the contest. I am inspired by the advancement of fast-moving science and technology, and I wanted to reveal how diverse the microbial world is. We have come to realize that how delicate and diverse the relationship between microbes and hosts,” said 1st place winner Md. Zohorul Islam, DVM, University of Copenhagen, Denmark. In this artwork, The First Race , Islam used four bacteria as paint and a selective agar medium as canvas. The red colored paint was Staphylococcus aureus, which is an opportunistic pathogen in both humans and animals. The green color was Staphylococcus xylosus , a commensal organism in human skin, and the white was Staphylococcus hyicus , an animal pathogen responsible for grassy pig disease. The yellow colored organism was Corynebacterium glutamicum , a non-pathogenic but industrially important bacterium. “The entries for this year's agar art contest showed a really amazing level of creativity and artistry. It's particularly impressive to me because the scientist-artists were working on such a small surface - a standard petri dish is just over 3 inches across - with pigments that want to keep growing and not stay put. I particularly admired the entries where the artists incorporated the specific types of bacteria they used into the theme of the artwork to make it more meaningful,” said one of the contest’s judges, Michele Banks , Watercolor and Collage Artist. The second place winner, This is not a beer! , took inspiration from the scientist and philosopher Alfred Korzybski (“The map is not the territory it represents,” 1931) and from the surrealist painter René Magritte who drew a pipe with the caption ‘Ceci n’est pas une pipe.’ “The work presented here stems from a simple catalase reaction; nonetheless it expands Korzybski’s and Magritte’s work to the bacterial world,” said the creator of the piece Mariarosaria Marinaro, Ph.D., Istituto Superiore di Sanita, Rome, Italy. “It also represents our attempt to reach a synthesis between Science and Abstraction, Metalanguage and Microbiology,” she said. In this piece of agar artwork, the catalase-positive MRSA was used to evoke a beer through its image. Staphylococci possess an enzyme, called catalase, which converts hydrogen peroxide into water and oxygen. In particular, the MRSA isolated in Marinaro’s lab was grown on agar and then treated with hydrogen peroxide to produce foam (i.e., oxygen production). The entrants in this year’s ASM Agar Art Contest have combined canvases of agar with a colorful microbial palette to produce stunning depictions of the world around us. From a simple snowflake to our complex gut microbiome, these artists creatively use bacteria to paint and sculpt amazing and unforgettable creations that make you smile in recognition, or exclaim in appreciation, said another judge of the contest Vincent Racaniello, Ph.D., Higgins Professor, Department of Microbiology Immunology Columbia University. Third place went Elena Gart, DVM, MS, Laura Bryan, DVM, and their group from Texas AM University for their submission Twelve Years of Yuck , an image of a twelve-year calendar which represents significant human outbreaks that occurred from 2005-2016. The People’s Choice award went to Bacterial Shadow of Wolf , created by Baris Halac, DVM and Sevgin Can of the Veterinary Faculty at Istanbul University. Popular artwork from both years’ contests will be on display in an art gallery at the ASM Microbe meeting on June 16th in Boston. More artwork from this year’s contest can be viewed on the Facebook album and on microbeworld.org/art .
编者按 : 肠道菌群与人类的行为、情绪有着奇妙的关联。科学家正在考虑通过改变肠道微生物来直接治疗部分心理疾病。未来人们或许可以通过吃某种益生菌从而来改善情绪,这些听上去是不是都很奇妙?尽管有许多未解之谜仍需解答,但科学家已经在通过肠道菌群调控大脑之路上迈开步伐。 编译 | 华梦艺 责编 | 叶水送 ● ● ● 上世纪70年代美国盛行这句谚语“You are what you eat”(你的身体由你的食物决定),随着近些年来人们对健康生活理念的关注,这句话也越来越多地被重提起。这句话翻译过来,大概就是你的饮食结构决定你的性格。不过,我们今天的主题并不是讨论各个地区的美食与文化,也不是讨论如何健康地吃喝,而是从另一个方面去解读这句话——“You are what kind of bacterial you have“(你体内的细菌决定了你的性格)。 这句话是有出处的,实际上来源于《美国国家科学院院刊》(PNAS)2015年发表的一篇新闻特稿——“细菌影响大脑”(Microbes on the mind),文章的主角就是“肠道内的菌群军团”。 用“军团”这样的词语来定义我们肠道菌群,绝不是危言耸听。定居在肠道中的菌群数量惊人,它们是人体自身细胞总数的10倍多,而这些菌群编码的基因数也远超人体基因总数。这些体积微小的细菌,几乎占据了胃肠道表面粘膜的每一寸“领土”。研究显示,胃以及其内容物中所含有的微生物细胞约为1000个/克,盘区折叠的小肠中的微生物高达每克 10 3 - 10 7 个细胞的水平,而产生和储存粪便的结肠则俨然是这些微生物生活的“乐园”,这里的微生物数量高达 10 12 个/克。难怪有人戏称,我们=10%的人体细胞+90%的细菌,更有人认为,也许这些菌群才是人身体真正的主宰。尽管这些都是玩笑,近期一系列的研究发现:肠道菌群与人类的行为情绪有着奇妙的关联。 曲径通幽——肠道菌群与大脑有着奇妙的关联 2014年,美国神经科学学会围绕“大脑-微生物组关系”主题,召开了一次史无前例的研讨会。美国国立精神卫生研究所(NIHM)拨款100万美元用以资助这一研究项目,而美国海军研究局则计划在2016年9月之前,将此项研究资金增加至330万美元。有了经费的支持,相关研究者们都“鼓足干劲、力争上游”,形式一片大好。不过在大家真正接受“体内微生物影响大脑”这个“前卫”的观点之前,先驱者们的探索之路并没有现在这样顺利。 2013年,加拿大麦克玛斯特大学精神病和运动神经学系简·福斯特(Jane Foster)教授在《Neuroastroenterology and Motility》杂志上发表了一篇肠道微生物相关的文章。关于这篇文章,Foster教授是这样描述的,“迄今为止,这是在我所有发表的文章中,经历最为曲折的一篇。”这篇名为《无菌小鼠表现出焦虑行为的减轻症状与中枢神经中化学物质改变的关系研究》文章,从2011年接收到正式发表,花了整整两年时间,期间也是争议不断,受到很多审稿人的质疑。对大部分中规中矩的神经学以及微生物学研究者来说,肠道微生物直接影响大脑的推断,实在令他们难以接受。 不过,好在科学家们通常都随时准备拥抱惊世骇俗的科学新发现。在这之后,关于“肠内菌群影响大脑”的研究,大部分论文发表都比较顺利。“时代一直在进步,”福斯特教授表示。目前她的大部分文章在经过严格审查后,一般只需4至6个月就能顺利刊发。 越来越多的科学探索者寻找到了“菌群-大脑”关系网络的蛛丝马迹,各种各样的研究结果都暗示着细菌以及它们的附属产物可能对大脑有着不可忽视的影响。“肠道微生物影响我们身体代谢这个观点对于很多人来说,直觉上都是可以接受的。”美国人肠道菌群工程(American Gut Project)的创始人罗伯·奈特(Rob Knight)这样认为。不同于大部分实验抽样调查的原则,该项目接收所有志愿者提供的信息。参与的志愿者需如实填写饮食、健康和抗生素使用情况的调查表,并使用实验室提供的试剂盒挑取口腔、面部以及排泄物中的微生物。当他们将这些邮寄到实验室后,会得到一份关于体内微生物的报告,一个属于他们自己的“二维码”,用来存储和读取自身的微生物信息。 肠道菌群怎样对大脑“发号施令” 大部分对肠道微生物-脑的研究受到2004年日本九州大学Nobuyuki Sudo等人研究的启发。他们发现,在无菌状态下出生以及成长的小鼠面对压力时通常会更敏感。 研究人员将无菌小鼠和正常小鼠暂时性放置于同一个封闭空间中一段时间后,检测两组小鼠血浆中应激激素水平发现,面对暂时的压力,和人类相似,两组小鼠血浆中的应激激素-促肾上腺皮质激素和皮质酮水平都有显著提升。不过相比于正常的小鼠,无菌小鼠体内应激激素水平升高将近两倍。 从出生就一直生活在无菌环境中的小鼠,是研究细菌对大脑影响的理想模型。图片来自Caroline Westwater 这些有趣的实验引起了广泛的关注。一些研究结果表明,无菌小鼠大脑皮质以及海马区的神经生长因子(BDNF)低于正常小鼠的水平,其他相关的神经化学系统在无菌小鼠中似乎也受到一些影响,但这些系统究竟发生了怎样的变化,研究者还不能给出一致的结论。这些零碎却有力的实验结果,已经让大脑与肠道菌群连接的通路依稀可见,然而行为学实验结果却成了这条轮廓初现道路上的新障碍。 尽管在之前的应激实验中,无菌小鼠体内的应激激素水平显著高于正常小鼠,但在行为学实验中,这些小鼠却表现的更加“气定神闲”,它们似乎更喜欢待在暴露的场所。这对天性谨慎胆小的小鼠来说,算是“无菌小鼠不怕虎”。 为了更好地理解肠道菌群这个“庞大的军团”究竟如何给远在“千里之外”的大脑“发号施令”,研究者通过细菌转染实验人为地改变了肠道菌群的组成。在众多的相关实验中,麦克马斯特大学的约翰·克莱恩(John Cryan)研究团队通过给肠道菌群军团 “大换血”,让几只胆小羞怯的小鼠成功转型为骁勇善战的“冒险家”,例如将生性胆大的NIH Swiss型小鼠的肠道细菌移植到天生纠结犹豫的BALB/c型小鼠体内,三个星期后,BALB/c型小鼠摇身一变成了果断骁勇的“骑士”。更有趣的是,当NIH Swiss型小鼠移植了胆小的BALB/c型小鼠细菌后,前者居然花了比平时三倍多的时间才谨慎地从实验台上走下来。 除了将不同菌群转染至小鼠,研究者们还进行了一种更“偷懒”的方法:直接给小鼠喂食不同种类的菌株,这样“简单粗暴”的实验方法很快有了收获:喂食长双歧杆菌以及短双歧杆菌的小鼠面对焦虑时,应激反应强度均会出现不同程度的降低。当然这两种细菌对小鼠性情进行了不同的改造:短双歧杆菌让小鼠变得更加勇敢,而长双歧杆菌则让小鼠在面对压力时,体温不至于变化过快。 为什么科学家们要如此大费周章去解开细菌、行为以及生化过程改变之间的种种谜团? 其中一个重要的动机应该是科学家想通过改变体内微生物从而直接治疗部分心理疾病。当然,相关的体内微生物学研究已经有一些发现:微生物对于和压力与焦虑相关的神经回路的影响可能集中在一些关键的发育阶段。巧合的是,在干预治疗部分心理健康疾病时,也有几个非常关键的时期。例如,自闭症的发生很有可能源于大脑早期发育过程中的一些尚未解决的问题,而精神分裂症的发生(至少一部分)是由青少年以及成年早期脑部成熟过程中的缺陷引起。如果体内微生物确实被证明在大脑发育的敏感阶段扮演了重要的角色,那么微生物未来作为治疗心理健康疾病靶点的可能性也将大大提升。 事实上,已有证据证明细菌可能影响早期脑部回路及功能。研究者们发现,在无菌小鼠中转入相应的肠道细菌可改变一些异常的行为,但这种处理只有在10周龄前才能起作用。Sudo等人的研究发现,无菌小鼠体内过高的应激激素也可以被小鼠6周龄时转入的细菌逆转,但同样的处理,对14周龄的小鼠就已失效了。这些结果在提示我们,体内菌群的存在或缺失对塑造与焦虑压力相关的神经回路起到非常关键的作用。然而,一旦这些回路在无菌小鼠体内以错误的方式建立,即使后期再使用相关细菌进行干预恐怕也是无力回天。 当然,小鼠宝宝和我们人类一样,大部分肠内菌群来自于分娩时母亲阴道中的微生物。因此,我们不难想到,孕期母亲体内的菌群结构会影响到后代脑部发育等过程。宾夕法尼亚大学的神经生物学家特蕾丝·贝尔(Tracy Bale)通过研究发现,当小鼠在怀孕早期承担较大压力时,它们阴道中的乳酸杆菌数量会有所降低,所产下幼鼠的肠道中的菌群也会表现出相同的变化,而这些鼠宝宝的大脑中,一些和神经发育相关的氨基酸也会“减少供应”。 想要好情绪,得先填饱你的胃 除了Bale团队的实验,加州理工学院的Sarkis Mazmanian团队的实验也有不小的收获。他们给一群有类似人类抑郁症症状的小鼠喂食一种人类肠道特殊的菌株:脆弱拟杆菌,饲养一段时间后发现它们肠漏气状况(部分患有自闭症的人也会有此症状)有所好转,同时一些明显的焦虑行为(如不断的重复性行为)也会减轻。不过,加州理工学院的马兹马尼扬(Sarkis Mazmanian)也表示“谁知道这些小鼠是不是真的有自闭症呢,也许我们只是被表面现象欺骗了。” 其实,即使弄清楚小鼠是不是真的有自闭症,我们还需要解决一个更加关键的问题——这些从小鼠实验中得到的数据,要用到人类身上还有千里之遥。不过,科学家们的辛勤工作也获得了一些诱人的成果。在一项实验中,55名志愿者在连续服用瑞士乳杆菌和长双歧杆菌混合的益生菌一个月后,相对于只服用安慰剂的志愿者来说,他们的沮丧、愤怒以及不友好的情绪都有所降低。 看到这样的结果,如笔者这样脾气不够温和的吃货简直坐立不安——也许可以通过吃吃吃来让自己变得温柔些。不过,严谨的科学家立刻告诉你我——先别急着去吃益生菌啦,也许这只是由于益生菌的过渡宣传引起的安慰剂效应。而且他们还告诉我们一个更残忍的现实,目前很难有证据去证明现有的益生菌对身体健康有显而易见的好处。“大部分的细菌实际上对于我们的行为举止都没有积极作用,不过这并不代表它们对我们有害,只是没啥作用罢了。”爱尔兰科克大学的克莱恩教授表示,“想要知道哪些益生菌是如何发挥功效的,我们必须要弄清楚这些细菌会产生什么物质以及它们细胞壁的成分。” 事实上,要想弄明白体内的细菌究竟是如何“遥控”大脑,我们仍需要克服很多困难。不过,这样研究有积跬步至千里之感,仅仅解决这些问题中的一小部分,都足以让我们在“肠-脑”研究之路上迈出一大步。 参考文献: 1.Shen, H. H. (2015). News feature: microbes on the mind.. Proceedings of the National Academy of Sciences of the United States of America, 112(30), 9143-5. 2.Foster, J. A., Neufeld, M. V. (2013). Gut–brain axis: how the microbiome influences anxiety and depression. Trends in Neurosciences, 36(5), 305–312. 3.Felix, S., Fredrik, B. (2013). The gut microbiota--masters of host development and physiology.. Nature Reviews Microbiology, 11(4), 227-238. 您也可以现在测测自己的 肠脑健康状况 哟,提前 了解自己的肠脑健康状况,预防帕金森 的发生吧。点击如下链接,或扫描下方二维码: https://www.wenjuan.com/s/FFFRN3/
沿北冰洋大洋中脊(ArcticMid-Ocean Ridge)的沉积物中发现了一组新的古菌(archaea),一种新的生命形式可能有助于解决困惑现代生物界最持久的一个谜团。 地球上的生物皆可以被分成原核生物和真核生物两大类,前者结构简单,后者常更加复杂。这两类生物细胞间存在差别的显著,对于如何通过进化实现两者间的跨越这一问题,生物学家一直迷惑未解。这类被命名为Lokiarchaeota的新微生物,就可能构成搭建两者间桥梁的作用。 原核生物包括所有细菌和古菌(archaea),它们都是单细胞物种,最初将古菌也归为细菌,后来将其单独分列了出来。真核生物除了一些单细胞生命形式外,更多是多细胞生物,包括动物,植物和真菌等。 原核生物和真核生物这两类生命形式间差距巨大,真核细胞拥有被脂外层包裹的细胞结构,细胞核中含细胞的遗传物质;另一个重要的结构是线粒体,多数真核细胞中都存在这种细胞器,它是细胞的电厂,负责供应能量。根据广泛接受的理论,线粒体原来是细菌,逐渐掺入真核细胞中,可能是一种互惠(mutualbenefit)共存的形式。 来自瑞典乌普萨拉大学(UppsalaUniversity)的Thijs Ettema说:古菌与真核细胞是姐妹,她们拥有共同的祖先,这已经是20年来的流行模式。一些年前,在进化树上真核生物的起源归到了古菌支上,更详细一些的话,附属于一个叫做TACK古菌的组。 Lokiarchaeota就归属于TACK组,且是与真核关系最接近的原核生物类。据Ettema的研究,在大约20亿年前,Lokiarchaeota与真核生物拥有共同的祖先。这一祖先拥有一个基因的“起始套件”(starterkit),拥有这一特性容其不断增加细胞的复杂性,进化形成今天缤纷的真核生物界。 Lokiarchaeota拥有部分编码仅在真核细胞中才出现的蛋白的基因,如支撑细胞形状和细胞运动的骨架蛋白基因。研究人员在黄石生态系统的热泉中寻找其它的Loki样(Loki-like)微生物,Lokiarchaeota中发现的这些与真核生物相同的基因并不证明它们就具有类似的功能。他们需要更多这类生物细胞,通过实验弄清楚这些基因在Lokiarchaeota中执行的功能。 “在海洋沉积物中获取这类样品并不容易,如此艰苦的环境下营养尤其匮乏,所以这些沉积物中细胞量尤其低。有些人预测在这种环境下的细胞可能要10年才分裂增殖一次,因此无法在实验室通过培养获取所需的细胞用量。” 研究人员正在其它地方寻找Loki样物种,包括在美国黄石的热泉中,和在新西兰。Ettema说他们甚至可能找到与真核生物之间拥有更近亲缘关系的Loki样物种。他们正努力重建这类物种的基因组序列,并发现复杂生命如何起源相关的其它的更多科学问题。 真核细胞进化的一个关键问题是线粒体的获取。Lokiarchaeota与其它的原核生物一样,也没有线粒体。因此,细胞何时与“能量工厂“的祖先发生了融合还是一个悬而未决的问题。 ThijsEttema说:“获得线粒体才意味者事件的起始开始,我们在Loki中发现的这些基因给提供了一些提示”,真核生物中一个十分重要的基因是肌动蛋白(actin)。 肌动蛋白具有多种功能,其中一个就是吞噬(phagocytosis),有了这种能力细胞才能吃掉其它细胞。ThijsEttema说他们在Loki中也找到了编码肌动蛋白的一些基因。虽然他们现在还不清楚它们在Loki中的功能,但是可以推断出Loki与真核生物共同的祖先也拥有这类基因。 http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14447.html Complex archaea that bridge the gap betweenprokaryotes and eukaryotes The origin of the eukaryotic cell remains oneof the most contentious puzzles in modern biology. Recent studies have providedsupport for the emergence of the eukaryotic host cell from within the archaealdomain of life, but the identity and nature of the putative archaeal ancestorremain a subject of debate. Here we describe the discovery of ‘Lokiarchaeota’,a novel candidate archaeal phylum, which forms a monophyletic group witheukaryotes in phylogenomic analyses, and whose genomes encode an expanded repertoireof eukaryotic signature proteins that are suggestive of sophisticated membraneremodelling capabilities. Our results provide strong support for hypotheses inwhich the eukaryotic host evolved from a bona fide archaeon, and demonstratethat many components that underpin eukaryote-specific features were alreadypresent in that ancestor. This provided the host with a rich genomic‘starter-kit’ to support the increase in the cellular and genomic complexitythat is characteristic of eukaryotes. 群晓科苑 Qbioscience.com
植物微生物的“好”与“坏” 文:秦有才(博士研究生) 上 一期介绍了植物和微生物之间的“房东”与“房客”关系,那现在给大家再深入一点介绍它们之间的相互作用关系。 我 们知道流行性感冒是由流感病毒引起的疾病,那类似的,植物的病害是不是也是由病原菌引起的呢?嗯,是的,植物病原菌( plant pathogen )的过量生长会引起植物的病害发生。 植 物病原菌可以从植物叶面和根部入侵宿主植物 ,它们还能够躲在植物种子里面。当条件适合时,这些病原菌会大量生长,从而导致植物病害的发生,严重时甚至会导致植物的死亡。这些病原菌并不是固定在某处上不动的,它们会随着空气的流动而到处溜达,寻找“猎物”并伺机占领之。 图片来自文献 (Hirano and Upper2000) (略有修改) 植 物病原菌会导致植物的不正常生长或者死亡,这必然会影响其它的微生物的生长环境,那其它的微生物就不乐意了。所以,就有一些微生物与植物联合起来,保护它们的“家园”,我们称这类微生物为植物生防有益菌( plant beneficial microorganisms )。这类有益菌不仅能够产生抑制病原菌生长的物质( pathogen inhibitory compound ),还能够诱导植物的抗病性( induce resistance , IR )。在植物受到病原菌的入侵时,植物开始召集这类有益菌,与有益菌相互联合来对抗病原菌。 图片来自文献 (Roeland, Corene et al. 2012) 除 了这两大类微生物外,还存在着很大一部分的共生微生物。它们对植物或者病原菌不产生直接的影响,属于那种看戏不嫌热闹的家伙。当然了,并不说它们完全不起作用。这类微生物通过代谢产物或营养物质消化等来影响其他共生微生物的生长,这些共生微生物之间复杂的相互作用会形成多种多样的环境,而这可能会间接地影响植物或者病原菌。 这 样看来,微生物虽然是小小的生物,可是它们的世界也很复杂热闹着呢。 扩展阅读 Hirano, S. S.and C. D. Upper (2000). Bacteria in the leaf ecosytem with emphasis on Pseudomonas syringae -a pathogen, icenucleus, and epiphyte. Microbiol Mol Biol Rev 64 (3): 624-653. Roeland, L. B.,M. J. P. Corene and A. H. M. B. Peter (2012). The rhizosphere microbiome and plant health. Trends Plant Sci 17 (8): 478-486. ——————————————————— 欢迎关注“月宫一号”微信公众号,由 北京航空航天大学生物与医学工程学院 环境生物学与生命保障技术研究所 月宫一号 刘红教授科研团队 中国生物医学工程学会-全国空间基地生命保障首席科学传播专家团队 创建并维护。 带您了解载人深空探测生命保障系统科普知识和最新研究动向。 如有帮助请点赞~
为了长久的存在,走向太空是人类文明的必由之路。走向太空的最初步骤就是到达太阳系的其他行星,报告我们的近邻——火星。火星是环境和地球最为相近的太阳系行星,但仍然不适合(至少就目前而言)生命(至少是普通生命)存在。如果有一天人类要到火星开辟新的生存空间,那么探索和改造火星环境就是必须进行的活动。 到目前为止并没有在火星上明确发现生命或生命迹象。但这并不能表明,如果把生命放到火星上,这些生命是否能存活并繁衍。探索这个问题的一个可能思路如下: 找地球上和火星环境类似的地方-提取此地的微生物-实验室模拟火星环境,放入这些微生物,看存活率、适应性、以及对环境的改变-如果不能成活,看修改什么实验条件能成活(水?温度?改造微生物基因)-找到改造火星的微生物及操作方法 目前科学家已经完成了这些步骤的一半——在模拟的火星环境下研究了一种细菌Acidithiobacillus ferrooxidans的存活率和存活时间(Bauermeister et al 2014)。研究显示七日成活率接近50%。当然,这些实验距离最终目标还很远,现在还不清楚这种细菌能否在模拟的火星环境中繁衍、进化,至于改正火星环境,那就差得更远。但是,毕竟这是第一步,已经很不错了。 参考文献 Anja Bauermeister, Petra Rettberg, Hans-Curt Flemming 2014, Planetary and Space Science, 98, 205
就在前几天(2014.4.28),Andrew T. Crombie和J.Colin Murrel在Nature 上发表题为: Trace-gas metabolic versatility of the facultative methanotroph Methylocella silvestris (兼性甲烷菌的示踪气体代谢多样性)的文章。美国之音(VOA)和路透社(Reuters)分别给予题为 Microbes could help clean up oil spills 和 Natural gas-gobbling bacteria may help combat oil leaks 的相关跟进报道。 看到这则报道,瞬间让我想到这对于国内瓦斯灾害防治大有裨益。如果以后真能够实现工业化应用,对于煤矿瓦斯防治,天然气利用过程中的气体泄露,石油泄漏,和减少大气中碳排放将具有革命性的影响。但对于“生物技术”的使用还是要慎之又慎,生物技术对于环境的影响,必须要经过科学的判断和评估才好。 题目:Trace-gas metabolic versatility of the facultative methanotroph Methylocella silvestris 作者:Andrew T. Crombie J.Colin Murrel 摘要: The climate active gas methane is generated both by biological processes and by thermogenic decomposition of fossil organic material, which forms methane and short chain alkanes, principally ethane, propane and butane1, 2. In addition to natural sources, environments are exposed to anthropogenic inputs of all these gases from oil and gas extraction and distribution. The gases provide carbon and/or energy for a diverse range of microorganisms that can metabolize them in both anoxic3 and oxic zones. Aerobic methanotrophs, which can assimilate methane, have been considered to be entirely distinct from utilizers of shortchain alkanes, and studies of environments exposed to mixtures of methane and multicarbon alkanes have assumed that disparate groups of microorganisms are responsible for the metabolism of these gases. Here we describe the mechanism by which a single bacterial strain, Methylocella silvestris, can use methane or propane as a carbon and energy source, documenting a methanotroph that can utilize a shortchain alkane as an alternative to methane. Furthermore, during growth on a mixture of these gases, efficient consumption of both gases occurred at the same time. Two soluble diiron centre monooxygenase (SDIMO) gene clusters were identified and were found to be differentially expressed during bacterial growth on these gases, although both were required for efficient propaneutilization. This report of a methanotroph expressing an additional SDIMO that seems to be uniquely involved in shortchain alkane metabolism suggests that such metabolic flexibility may be important in many environments where methane and short-chain alkanes co-occur.
PNAS上的最近发的题为Chemical-biogeographic survey of secondary metabolism in soil (土壤中次生代谢的化学生物地理学调查,全文链接以及摘要和重要性见文后),是由Sean F. Brady实验组发表,他们组在从土壤宏基因组文库(metagenomic library)中发现新天然产物领域处于国际领先地位。 在这篇文章中,他们用生物合成为基础的基因型鉴定方法,比较了美国西南和东北不同生境中96份土壤微生物群系的次生代谢产物生物合成基因的丰富度和多样性。通过特异性的扩增两大重要微生物天然产物生物合成酶:非核糖体多肽合成酶(NRPS)的保守的A 结构域和聚酮合酶(PKS)的保守的KS结构域片段,然后测序扩增子(amplicon)序列分析,来评价不同土壤生境中次生代谢产物生物合成的多样性(这个方法跟读文献3中的类似)。一般来说, 干旱土壤的微生物群系产生了最大的生物合成多样性,而来自微咸水区和松树林的土壤表现出了最小的多样性 。这或许会给我们些启示:到干旱的地方比如沙漠去采样,来获得或分离到更多产生天然产物的微生物? 同时,通讯作者Brady的博士期间的导师Jon Clardy和Pierre Stallforth发表了评论文章Atlas for drug discovery。 他们提出了两个有意思的insights: 1) bacteria in similar environments produce, or at least have amplicons that suggest they would produce, similar small molecules. 相似生境的细菌可能产生相似的小分子化合物。土壤环境的多样性,尤其是pH值,是的环境选择的最重要因子。相似的土壤环境中产生的相似的细菌坑内产生相似的化合物(环境决定论?!)。2)干旱土壤相对森林 土壤具有个更大的生物合成潜力是令人费解的。Waksman开启了抗生素的黄金时代从而获得了诺贝尔奖,他发现的来之放线菌的抗生素尤其是链霉素是从新泽西的沼泽地理分离到的。可能的原因是,干旱土壤具有更多的未培养的微生物? Chemical-biogeographic survey of secondary metabolism in soil 摘要及全文链接: http://www.pnas.org/content/early/2014/02/13/1318021111.abstract?sid=6c128702-28e8-44da-a3fb-4183944cf75f Atlas for drug discovery by Pierre Stallforth and Jon Clardy 全文链接: http://www.pnas.org/content/early/2014/02/19/1400516111.full.pdf+html?sid=b11831cb-f40f-4a3a-8e19-9d97d01f9fa7
声明:本文转自果壳网,原文链接 http://www.guokr.com/article/436743/ 你是你自己么?拿这个问题去问别人,估计被问的到的人都会一愣,然后答道“我当然是我自己啦!”。的确,在大多数时候,人总是被视作一个独立、统一、完全的个体。然而,生物学和医学研究却发现,其实人体并非是一个统一的整体,在人体内部,还有一些与人体在生物学上截然不同,而又有紧密联系的生物群体。这个生物群体,是由大量微生物共同组成的。其中最重要也是最有名的,就是肠道菌群。 图片来自:http://www.nature.com/nature/journal/v444/n7122/images/4441009a-f1.2.jpg。 身体内的另一个自己 在微生物学诞生后不久,人们就发现,在动物的消化道中存在有不少微生物。例如在牛、羊、兔等食草动物的胃或盲肠中,就存在大量以细菌为主的微生物群体。由于食草动物摄入的植食性饲料中,纤维素、半纤维素等多糖难以依靠动物体自身分泌的酶液消化,而微生物群体中包含的纤维素消化菌、半纤维素消化菌等可以较好的将多糖转化为低聚糖和寡糖,从而促进对这些营养物质的吸收。 随着医学的发展,人们也注意到,在人类的肠道,尤其是结肠(也就是平常所说的大肠)中,也存在着大量微生物。这些以细菌为主的微生物种类极多,数量极大。据推测,一个正常成人体内,肠道内的细菌总重量可达1-1.5千克,包含的细菌数量则可以达到10 14 个 。而一个成年人自身的细胞数量为10 13 个,也就是说,居住在我们肠道内的细菌数量,是人体细胞总数的10倍!我们每天排出的粪便中,干重量的50%以上是由这些细菌及其“尸体”构成的。因此有人风趣的说,从数量上来看,我们人类并不应该被称为人类,而应被称作细菌。如此庞大的细菌群体驻扎在肠道内,构成了一个极为复杂的集体。这个集体,就被称作肠道菌群。(想欣赏人体内细菌的艺术照,请看: 我们=10%人+90%细菌 。) 肠道菌群并非是生来就有的,它们实际上是“外来户”。在母体子宫内,胎儿所处的是一个几乎无菌的环境,因此胎儿肠道内也是无菌的。当胎儿出生之后的几天内,细菌通过分娩时阴道物质摄入、哺乳时的口腔摄入以及空气吸入等途径进入新生儿体内,并在肠道内定植,形成新生儿最初的肠道菌群。随着婴儿的成长,肠道菌群的种类结构逐渐趋于稳定,最终形成成熟的肠道菌群。这些微小的生物的群体就这样不知不觉的定居到人体之内,悄无声息的与主人相随一生。 复杂但组织严密的群体 肠道内如此之多的细菌,并非杂乱无序的驻扎在肠道内。相反,对于一个正常人体来说,肠道菌群具有一定的组成结构。据估计,人体肠道菌群可包括500-1000种细菌,不过种类虽多,但各种细菌的数量差别却很悬殊:占细菌总数数量99%以上的细菌是由其中30-40种细菌构成的,其他多种细菌则只占到很小的比例 。目前,已经鉴定出的细菌类群有百余个,包括拟杆菌、双歧杆菌、乳酸杆菌、芽孢杆菌、肠球菌、肠杆菌等。这些细菌根据其在肠道内不同的生理功能被分为三大类:共生菌、条件致病菌和病原菌。 所谓共生菌,故名思议,它和我们人体是互利共生的关系。简单的说,就是人体为细菌的生活提供生存场所和营养,而这些细菌则为人体产生有益的物质和保护人类健康。前面说到的双歧杆菌、乳酸菌、拟杆菌等,就是共生菌的典型例子。共生菌一般都是专性厌氧菌,从数量上说,它们占据了肠道菌群所有细菌数量的99%以上,是肠道菌群的主体 。 条件致病菌在肠道菌群内数量较少。它们从功能上来说是肠道内的“看客”。在正常条件下,由于大量共生菌的存在,这些“看客”并不容易繁殖开来造成危害。但若在一定条件下任由它们繁殖,那么就会对机体产生不良印象。肠道菌群中,常见的条件致病菌大多是肠球菌、肠杆菌等。 肠道内的还有那么一小撮分子,它们在一般不常驻在肠道内。但是若不慎摄入,则有可能在肠道内大量繁殖,然后兴风作浪,导致疾病。这些就是致病菌。在致病菌的名单中,一些名字可以说臭名昭著,例如引起食物中毒的沙门氏菌、导致腹泻的致病性大肠杆菌等。 从上面可见,正是由于共生菌占据了肠道菌群的主导地位,因此才能抑制条件致病菌不至于变为致病菌,并防止致病菌的侵扰。对于人体来说,维持肠道菌群处于正常的平衡之中,是保证机体健康的重要一环。若菌群结构发生异常,则可能带来很多潜在的健康问题。 肠道菌群——尚未被认识的器官 早期研究中,肠道微生物更多的被认为是和消化、营养作用联系在一起的。在动物实验中,无菌小鼠需要多摄取30%的碳水化合物,才能和正常有菌小鼠的体重相当 。对人类来说,植物中的纤维素和半纤维素类多糖是无法消化的,而肠道菌群中的拟杆菌等细菌则具有一系列多糖消化的酶,来分解这些多糖,从而为人类提供能量。除此之外,肠道菌群通过发酵还能产生短链脂肪酸和维生素K供人体吸收,同时一些金属离子,如钙、镁、铁等,也可通过肠道菌群被重新吸收 。 然而随着研究的深入,人们逐渐发现,肠道菌群不只在消化过程发挥作用,它和人体健康有着极为密切的联系。 首先,肠道菌群的存在能通过自身屏蔽和影响机体免疫系统,阻止病原菌入侵人体。肠道内壁,是人体和外界环境接触面积最大的地区(是的,你没有看错,肠管内的空腔严格来说是“体外”环境)。肠道菌群附着在肠道内壁表面的粘膜层之上,构成了一层由细菌构成的屏障。就如同前文所说,肠道菌群通过其中占主导作用的共生菌的活动,抑制致病菌的生长,同时阻止致病透过这层屏障进入人体 。在进行被动防御的同时,肠道菌群可以刺激机体在肠道形成更多的淋巴器官,并增加免疫球蛋白在血浆和肠粘膜中的水平,使得免疫系统处于一种适度的活跃状态,以此对入侵体内的病原菌保持有效的免疫作用。而肠道菌群的失调,则可造成免疫系统的过度活跃,从而产生自体免疫疾病 。 其次,肠道菌群对肠道自身具有调节和营养作用。有报道显示,肠道菌群的存在,尤其是其产生的短链脂肪酸的营养作用,可以使得肠道上皮细胞的生长更为活跃。相比于无菌肠道,具有正常肠道菌群的肠粘膜绒毛下侧会产生更多的可分泌粘液和酶的组织——隐窝,同时肠粘膜细胞更替更为迅速。此外,肠道菌群还可调控肠粘膜上皮细胞的分化 。这意味着,具有正常的肠道菌群可以使得肠粘膜更快的修复其破损。 再次,近期的多项研究表明,肠道菌群和人体的代谢疾病具有重要关系。肠道菌群失衡可能是造成肥胖、糖尿病等多种多种代谢异常的重要原因之一。造成代谢异常的主要原因,是失衡的肠道菌群产生的脂多糖等内毒素进入人体,被免疫细胞识别后产生多种炎症因子,使得机体进入低度炎症状态,从而产生代谢异常。例如,若长期进食高脂、高糖食物,可造成肠道菌群中条件致病菌比例增加,而共生菌比例下降,从而使得食物中摄取的能量更容易转化为脂肪累积于皮下,造成肥胖 。此外,低度炎症还能促使机体对胰岛素相应程度下降,造成胰岛素抵抗,进而发展为糖尿病。 最后,肠道菌群与健康还有其他更多元的关系。比如,肠道菌群产生的类胡萝卜素类物质可一定程度上降低动脉粥样硬化和中风的风险 。正常肠道菌群可通过对淋巴细胞的影响,调节机体对过敏原的反应,从而影响过敏疾病的产生 。更令人惊奇的是,还有证据显示,肠道菌群的结构变化甚至可以影响机体的行为模式 。 从以上各方面可以看出,肠道菌群,这个陪伴我们一生的生物构造,其功能更像是一个影响到机体各个方面的“器官”,这个器官的正常与否,对人体的健康程度有着重要影响,而我们对它的了解才刚刚起步。毫不夸张的说, 肠道菌群,是我们体内一个尚未被认识的器官 ,而对它结构和功能的研究,对治疗疾病和开发新的治疗方式具有重要的意义。 肠道菌群的未来:益生菌、益生元和宏基因组学 由于肠道菌群的主体是共生菌,因此肠道菌群失衡的主要表现为共生菌比例的下降。自然而然的人们想到可以通过直接补充共生菌,或通过补充促进共生菌生长的物质,来达到调节肠道菌群的目的。目前,人们最常作为共生菌补充的是乳酸杆菌和双歧杆菌,同时也有少量链球菌等。在我们的生活中经常听到的名词“益生菌”,主要指的就是这几类细菌。通过适当的方式适度的补充这些益生菌,可以一定程度上达到调节肠道菌群组成、进而改善健康状况。 与“益生菌”这一概念相仿,最近一个新的名词“益生元”(prebiotic)被大家所熟悉。所谓益生元,较为公认的概念是指能够不被消化而完整进入肠道菌群环境、可被共生菌利用而增加共生菌数量和活力、并利于人体健康的物质。目前,公认的“益生元”物质包括低聚半乳糖和菊糖 。一些证据也表明低聚果糖可能也是潜在的“益生元”之一,因为摄入一定果糖可增加人类肠道菌群中双歧杆菌的比例 。不过值得注意的是,“益生元”是一个概念,而不是一个具体的产品。市场上很多打着“益生元”名义的产品,更多的是借用这个概念宣传其保健作用。这些产品所含成分可能对肠道菌群有良性影响,但严格来说并非真正符合“益生元”的定义。 由于肠道菌群具有如此多样和重要的功能,因此大批科研人员开始致力于对肠道菌群进行更深入的研究。微生物的传统研究手段是利用体外培养和分离培养,分析单独菌株或菌群的生理功能。但是很多种类的肠道菌群只能在人体内生存而不能被体外培养,因此传统手段对肠道菌群如此复杂的结构显得捉襟见肘。不过,随着测序技术的进步,人们可以对整个肠道菌群作为一个整体,对它所包含的所有基因进行分析。这个基因的大集合,就被称作宏基因组。根据研究,这个基因组所包含的基因多达数百万,是人类基因组的100倍之多,其中包含多个与物质代谢、免疫、信号相关的基因群体 。通过对肠道菌群宏基因组的研究,有助于进一步挖掘肠道菌群功能,更深层次的探究肠道菌群和人体健康的关系。 关于肠道菌群保健的一些Tips: 抗生素的使用可对肠道菌群产生严重影响,很容易造成菌群失调。因此使用抗生素一定需要按照医嘱使用,切勿滥用和过量使用。 高脂、高糖的饮食习惯会导致共生菌比例下降,从而造成肠道菌群失调。因此一定要注意合理饮食。 在使用标注有“益生菌”、“益生元”等信息的产品时,要注意看清其成分和预期的保健功能,并合理、适度使用。对于相关药品,应咨询医师后服用。 更多健康讨论,请加入 健康朝九晚五小组 。 参考资料: 1、Commensal host-bacterial relationships in the gut 2、Gut flora in health and disease 3、A dynamic partnership: celebrating our gut flora 4、Dietary intake, energy metabolism, and excretory losses of adult male germfree Wistar rats. 5、Effects of two fermentable carbohydrates (inulin and resistant starch) and their combination on calcium and magnesium balance in rats. 6、The ecology of the human intestine and its consequences for overgrowth by pathogens such as Clostridium difficile 7、Sex Differences in the Gut Microbiome Drive Hormone-Dependent Regulation of Autoimmunity. 8、Differential cell kinetics in the ileum and colon of germfree rats 9、An opportunistic pathogen isolated from the gut of an obese human causes obesity in germfree mice 10、Symptomatic atherosclerosis is associated with an altered gut metagenome 11、The Inhibitory Receptor PD-1 Regulates IgA Selection and Bacterial Composition in the Gut 12、The Intestinal Microbiota Determines Mouse Behavior and Brain BDNF Levels. 13、Prebiotics: The Concept Revisited 14、Short-chain fructo-oligosaccharide administration dose-dependently increases fecal bifidobacteria in healthy humans 15、An ecological and evolutionary perspective on human-microbe mutualism and disease 本文版权属于果壳网( guokr.com ),转载请注明出处。商业使用请 联系果壳
The 6 th Environmental Microbiology Lecture byProfessor Victor de Lorenzo Victor de Lorenzo 教授 在 西班牙国立生物技术中心(CentroNacional de Biotecnología )主持分子环境微生物学实验室(Molecular EnvironmentalMicrobiology Laboratory ),这个实验室主要研究细菌是如何感知和处理环境信号,以及如何将这些知识应用于生物技术,同时还致力于发展研究细菌的分子工具。 2013 年10 月28 日,Victor de Lorenzo 教授在伦敦进行了此次演讲,当天有许多精英学者参加, Wiley 十分荣幸能与应用微生物学学会(TheSociety for Applied Microbiology )一起,为大家呈上教授的全程演讲视频 。 演讲简介: 环境微生物是生物界中供酶活动的最大的“水库”, 但是这些大量的无主宝藏还有待开发。我们需要新的概念性和材料性工具,还要掌握基本的生物过程(如新陈代谢)。以下是几个重要的方面:优化有限数量的基因和生物化学过程并配以相应的生物技术、标准化DNA 结构物理装配方法、开发用于发展和维护植入物稳定的基因工具、调整工程属性以适应宿主的基因和生物化学特性。 视频地址(免费观看): http://www.yada-yada.co.uk/Blackwell/SFAM2013/SfAM2013.html 以下是Victor de Lorenzo 教授曾撰写的一些文章,欢迎阅读: The TOL network of Pseudomonas putida mt-2 processes multiple environmental inputs into a narrow response space Rafael Silva-Rocha, Víctor de Lorenzo The IHF regulon of exponentially growing Pseudomonas putida cells Rafael Silva-Rocha, Max Chavarría, Roelco J. Kleijn, Uwe Sauer, Víctor de Lorenzo Cra regulates the cross-talk between the two branches of the phosphoenolpyruvate : phosphotransferase system of Pseudomonas putida Max Chavarría, Tobias Fuhrer, Uwe Sauer, Katharina Pflüger-Grau, Víctor de Lorenzo Random and cyclical deletion of large DNA segments in the genome of Pseudomonas putida Audrey Leprince, Víctor de Lorenzo, Petra Völler, Mark W. J. van Passel, Vitor A. P. Martins dos Santos
本文精选了 3 月份中国作者发表在 Wiley 优秀生命科学期刊上的 23 篇文章,其中 Stem Cells 1 篇、 Ecology Letters 1 篇、 Global Change Biology 5 篇、 Journal of Pineal Research 2 篇、 Molecular Ecology 2 篇、 New Phytologist 4 篇、 Pigment Cell Melanoma Research 1 篇、 Plant Cell and Environment 3 篇、 Plant Journal 4 篇。 -------------------------------------------------------------------------------------------- 其他学科: Wiley化学材料学优秀期刊(A) Wiley化学材料学优秀期刊(B) Wiley医学类优秀期刊 -------------------------------------------------------------------------------------------- 一、 Stem Cells Transforming Growth Factor β1 Signal is Crucial for Dedifferentiation of Cancer Cells to Cancer Stem Cells in Osteosarcoma 作者: Haixia Zhang( 中山大学 ), Haotong Wu( 中山大学 ), Junheng Zheng( 中山大学 ), Pei Yu( 中山大学 ), Lixiao Xu( 中山大学 ), Pan Jiang( 中山大学 ), Jin Gao(James Cook University), Hua Wang( 中山大学 ), Yan Zhang( 中山大学 ) -------------------------------------------------------------------------------------------- 二、 Ecology Letters Suppression of terpenoid synthesis in plants by a virus promotes its mutualism with vectors 作者: Jun-Bo Luan ( 浙江大学 ), Dan-Mei Yao( 浙江大学 ), Tong Zhang( 浙江大学 ), Linda L. Walling(University of California, Riverside), Mei Yang( 浙江大学 ), Yu-Jun Wang( 浙江大学 ), Shu-Sheng Liu( 浙江大学 ) -------------------------------------------------------------------------------------------- 三、 Global Change Biology Environmental changes impacting Echinococcus transmission: research to support predictive surveillance and control 作者: Jo-An M. Atkinson(University of Queensland), Darren J. Gray(University of Queensland), Archie C.A. Clements(University of Queensland), Tamsin S. Barnes(University of Queensland), Donald P. McManus(Queensland Institute of Medical Research), Yu R. Yang( 宁夏医科大学 ) -------------------------------------------------------------------------------------------- Modern maize hybrids in Northeast China exhibit increased yield potential and resource use efficiency despite adverse climate change 作者: Xiaochao Chen( 中国农业大学 ), Fanjun Chen( 中国农业大学 ), Yanling Chen( 中国农业大学 ), Qiang Gao( 吉林农业大学 ), Xiaoli Yang( 中国农业大学 ), Lixing Yuan( 中国农业大学 ), Fusuo Zhang( 中国农业大学 ), Guohua Mi( 中国农业大学 ) -------------------------------------------------------------------------------------------- Changes in satellite-derived spring vegetation green-up date and its linkage to climate in China from 1982 to 2010: a multimethod analysis 作者: Nan Cong( 北京大学 ), Tao Wang(CEA CNRS UVSQ), Huijuan Nan( 北京大学 ), Yuecun Ma( 北京大学 ), Xuhui Wang( 北京大学 ), Ranga B. Myneni(Boston University), Shilong Piao( 北京大学 ) -------------------------------------------------------------------------------------------- Consistent shifts in spring vegetation green-up date across temperate biomes in China, 1982–2006 作者: Xiuchen Wu, Hongyan Liu( 北京大学 ) -------------------------------------------------------------------------------------------- Spatial patterns and climate drivers of carbon fluxes in terrestrial ecosystems of China 作者: Gui-Rui Yu( 中国科学院地理科学与资源研究所 ), Xian-Jin Zhu( 中国科学院地理科学与资源研究所 ), Yu-Ling Fu( 中国科学院地理科学与资源研究所 ), Hong-Lin He( 中国科学院地理科学与资源研究所 ), Qiu-Feng Wang( 中国科学院地理科学与资源研究所 ), Xue-Fa Wen( 中国科学院地理科学与资源研究所 ), Xuan-Ran Li( 中国科学院地理科学与资源研究所 ), Lei-Ming Zhang( 中国科学院地理科学与资源研究所 ), Li Zhang( 中国科学院地理科学与资源研究所 ), Wen Su( 中国科学院地理科学与资源研究所 ), Sheng-Gong Li( 中国科学院地理科学与资源研究所 ), Xiao-Min Sun( 中国科学院地理科学与资源研究所 ), Yi-Ping Zhang( 中国科学院西双版纳热带植物园 ), Jun-Hui Zhang( 中科院沈阳应用生态研究所 ), Jun-Hua Yan( 中国科学院华南植物园 ), Hui-Min Wang( 中国科学院地理科学与资源研究所 ), Guang-Sheng Zhou( 中国科学院植物所 ), Bing-Rui Jia( 中国科学院植物所 ), Wen-Hua Xiang( 中南林业科技大学 ), Ying-Nian Li( 中国科学院西北高原生物研究所 ), Liang Zhao( 中国科学院西北高原生物研究所 ), Yan-Fen Wang( 中国科学院大学 ), Pei-Li Shi( 中国科学院地理科学与资源研究所 ), Shi-Ping Chen( 中国科学院植物所 ), Xiao-Ping Xin( 中国农业科学院 ), Feng-Hua Zhao( 中国科学院地理科学与资源研究所 ), Yu-Ying Wang( 中国科学院遗传与发育生物学研究所 ), Cheng-Li Tong( 中国科学院亚热带农业生态研究所 ) -------------------------------------------------------------------------------------------- 四、 Journal of Pineal Research Melatonin treatment improves adipose-derived mesenchymal stem cell therapy for acute lung ischemia–reperfusion injury 作者: Hon-Kan Yip(Chang Gung University), Yi-Chih Chang( 厦门长庚纪念医院 ), Christopher Glenn Wallace(University Hospital of South Manchester), Li-Teh Chang(Meiho University), Tzu-Hsien Tsai(Chang Gung University), Yung-Lung Chen(Chang Gung University), Hsueh-Wen Chang(National Sun Yat-Sen University), Steve Leu(Chang Gung University), Yen-Yi Zhen(Chang Gung University), Ching-Yen Tsai(Academia Sinica), Kuo-Ho Yeh(Chang Gung University), Cheuk-Kwan Sun(Academia Sinica), Chia-Hung Yen(National Pingtung University of Science and Technology) -------------------------------------------------------------------------------------------- Melatonin influences proliferation and differentiation of rat dental papilla cells in vitro and dentine formation in vivo by altering mitochondrial activity 作者: Jie Liu, Hongyu Zhou, Wenguo Fan, Weiguo Dong, Shenli Fu, Hongwen He, Fang Huang( 中山大学 ) -------------------------------------------------------------------------------------------- 五、 Molecular Ecology High diversity and widespread occurrence of mitotic spore mats in ectomycorrhizal Pezizales 作者: R. A. Healy(University of Minnesota), M. E. Smith(University of Florida), G. M. Bonito(Duke University), D. H. Pfister(Harvard University), Z. -W. Ge( 中国科学院昆明植物研究所 ), G. G. Guevara(Instituto Tecnológico de Cd. Victoria), G. Williams(Duke University), K. Stafford(Duke University), L. Kumar(University of Minnesota), T. Lee(University of Minnesota), C. Hobart(University of Sheffield), J. Trappe(Oregon State University), R. Vilgalys(Duke University), D. J. McLaughlin(University of Minnesota) -------------------------------------------------------------------------------------------- Impact of climate changes from Middle Miocene onwards on evolutionary diversification in Eurasia: Insights from the mesobuthid scorpions 作者: Cheng-Min Shi, Ya-Jie Ji, Lin Liu, Lei Wang, De-Xing Zhang ( 中科院动物所 ) -------------------------------------------------------------------------------------------- 六、 New Phytologist Epigenetic modification contributes to the expression divergence of three TaEXPA1 homoeologs in hexaploid wheat (Triticum aestivum) 作者: Zhaorong Hu, Zongfu Han, Na Song, Lingling Chai, Yingyin Yao, Huiru Peng, Zhongfu Ni, Qixin Sun( 中国农业大学 ) -------------------------------------------------------------------------------------------- SlNAC1, a stress-related transcription factor, is fine-tuned on both the transcriptional and the post-translational level 作者: Weizao Huang( 四川省农业科学院 ), Min Miao( 四川大学 ), Joanna Kud(University of Idaho), Xiangli Niu( 合肥工业大学 ), Bo Ouyang( 杭州农业大学 ), Junhong Zhang( 杭州农业大学 ), Zhibiao Ye( 杭州农业大学 ), Joseph C. Kuhl(University of Idaho), Yongsheng Liu( 四川省农业科学院 ), Fangming Xiao(University of Idaho) -------------------------------------------------------------------------------------------- Molecular evolution and expression divergence of the Populus polygalacturonase supergene family shed light on the evolution of increasingly complex organs in plants 作者: Zhi-Ling Yang( 中科院植物所 ), Hai-Jing Liu( 中科院植物所 ), Xiao-Ru Wang(Ume University), Qing-Yin Zeng( 中科院植物所 ) -------------------------------------------------------------------------------------------- Jasmonate and ethylene signaling mediate whitefly-induced interference with indirect plant defense in Arabidopsis thaliana 作者: Peng-Jun Zhang( 浙江省农业科学院 ), Colette Broekgaarden(Wageningen University and Research Centre), Si-Jun Zheng(Wageningen University), Tjeerd A. L. Snoeren(Wageningen University), Joop J. A. van Loon(Wageningen University), Rieta Gols(Wageningen University), Marcel Dicke(Wageningen University) -------------------------------------------------------------------------------------------- 七、 Pigment Cell Melanoma Research Hermansky–Pudlak syndrome: pigmentary and non-pigmentary defects and their pathogenesis 作者: Ai-Hua Wei( 首都医科大学附属北京同仁医院 ), Wei Li( 中国科学院遗传与发育生物学研究所 ) -------------------------------------------------------------------------------------------- 八、 Plant, Cell Environment Chloroplast ultrastructure regeneration with protection of photosystem II is responsible for the functional ‘stay-green’ trait in wheat 作者: P. G. LUO( 四川农业大学 ), K. J. DENG( 电子科技大学 ), X. Y. HU( 四川农业大学 ), L. Q. LI( 四川农业大学 ), X. LI( 四川农业大学 ), J. B. CHEN( 四川农业大学 ), H. Y. ZHANG( 四川农业大学 ), Z. X. TANG( 四川农业大学 ), Y. ZHANG( 电子科技大学 ), Q. X. SUN( 中国农业大学 ), F. Q. TAN( 四川农业大学 ), Z. L. REN( 四川农业大学 ) -------------------------------------------------------------------------------------------- A novel protein kinase involved in Na+ exclusion revealed from positional cloning 作者: S. J. ROY(Australian Centre for Plant Functional Genomics and the University of Adelaide), W. HUANG(Australian Centre for Plant Functional Genomics and the University of Adelaide), X. J. WANG( 兰州大学 ), A. EVRARD(Australian Centre for Plant Functional Genomics and the University of Adelaide), S. M. SCHMCKEL(Australian Centre for Plant Functional Genomics and the University of Adelaide), Z. U. ZAFAR(Australian Centre for Plant Functional Genomics and the University of Adelaide), M. TESTER(Australian Centre for Plant Functional Genomics and the University of Adelaide) -------------------------------------------------------------------------------------------- OsARF16, a transcription factor, is required for auxin and phosphate starvation response in rice (Oryza sativa L.) 作者: CHENJIA SHEN( 浙江大学 ), SUIKANG WANG( 浙江大学 ), SAINA ZHANG( 浙江大学 ), YANXIA XU( 浙江大学 ), QIAN QIAN( 中国农业科学院 ), YANHUA QI( 浙江大学 ), DE AN JIANG( 浙江大学 ) -------------------------------------------------------------------------------------------- 九、 The Plant Journal Gene family evolution in green plants with emphasis on the origination and evolution of Arabidopsis thaliana genes 作者: Ya-Long Guo( 中科院植物所 ) -------------------------------------------------------------------------------------------- Wheat centromeric retrotransposons: the new ones take a major role in centromeric structure 作者: Baochun Li( 中国农业科学院 ), Frédéric Choulet(Genetic Diversity and Ecophysiology of Cereals), Yanfang Heng( 中国农业科学院 ), Weiwei Hao( 中国农业科学院 ), Etienne Paux(Genetic Diversity and Ecophysiology of Cereals), Zhao Liu( 中国农业科学院 ), Wei Yue( 中国农业科学院 ), Weiwei Jin( 中国农业大学 ), Catherine Feuillet(Genetic Diversity and Ecophysiology of Cereals), Xueyong Zhang( 中国农业科学院 ) -------------------------------------------------------------------------------------------- Oryza sativa actin-interacting protein 1 is required for rice growth by promoting actin turnover 作者: Meng Shi( 中科院植物所 ), Yurong Xie( 中科院植物所 ), Yiyan Zheng( 中科院植物所 ), Junmin Wang( 浙江省农业科学院 ), Yi Su( 湖南农业大学 ), Qiuying Yang( 中科院植物所 ), Shanjin Huang( 中科院植物所 ) -------------------------------------------------------------------------------------------- C2-mediated decrease in DNA methylation, accumulation of siRNAs, and increase in expression for genes involved in defense pathways in plants infected with beet severe curly top virus 作者: Li-Ping Yang1, Yuan-Yuan Fang( 中科院微生物研究所 ), Chun-Peng An( 中科院微生物研究所 ), Li Dong( 中科院微生物研究所 ), Zhong-Hui Zhang( 中国科学院遗传与发育生物学研究所 ), Hao Chen( 中国科学院遗传与发育生物学研究所 ), Qi Xie( 中国科学院遗传与发育生物学研究所 ), Hui-Shan Guo( 中科院微生物研究所 ) --------------------------------------------------------------------------------------------
卵磷脂phosphatidylcholine,复合维生素Vitamins,左旋肉碱L-carnitine都是常见的保健品。常被用于营养强化和保健,预防多种疾病。然而,现在的研究发现它们并非始终对人体有保健作用,在某些肠道微生物的作用下,它们可能毒害我们的身体。 卵磷脂有助于降低血脂,保护心脏和大脑,滋润皮肤延缓衰老等。卵磷脂在食物中含量丰富。蛋黄中较多,其次牛奶、动物的脑、骨髓、心脏、肺脏、肝脏、肾脏以及大豆和酵母中都含有卵磷脂。 维生素是人生长、代谢、发育过程中不可或缺的一类微量有机物质。在天然食物中含量较少,有些维生素,如B族维生素则是由肠道共生的细菌合成的。 左旋肉碱是一种能够促使脂肪分解转化为能量的类氨基酸,被用作减肥营养补充剂。红色肉类(牛、羊肉,猪肉等)是左旋肉碱的主要来源。由于它不是一种必须的营养成分,因此仅用于减肥等特殊目的。 肠道细菌能够代谢胆碱和卵磷脂生成三甲胺(trimethylamine,TMA)进而被代谢成三甲胺N-氧化物(trimethylamine-N-oxide(TMAO)。TMAO可不是个好东西,它能够促进动脉硬化的发生。而左旋肉碱其实是一种TMA,在肠道微生物的代谢作用下也会生产TMAO。所以,大量食用肉食者会摄入较多的TMA,在肠道微生物作用下产生更多的TMAO,肉食者毫无疑问的患心脑血管疾病的风险更高。 发表在《自然》上的两项研究分别证明了上述结论。美国克利夫兰医学中心的研究发现,普通食物中的卵磷脂在肠道微生物作用下会增加患心血管疾病(cardiovascular disease,CVD)的风险。食物卵磷脂的三种代谢产物(胆碱(B族维生素的复合物),氧化三甲胺(TMAO)和甜菜碱(胆碱代谢物))在血液中的水平对心血管病有很强的预示作用。这几种代谢物水平越高,患心血管疾病的风险也越高。研究发现,也许通过检测血液中的氧化三甲胺就可以知道谁更容易患心血管病。此外,胆碱作为B族维生素的复合物被肠道微生物代谢后也会产生TMAO,因此,补充复合维生素也有可能在补充维生素的同时增加血液中TMAO的含量,提高患心血管病的风险。 此外,美国俄亥俄州克利夫兰医学中心的研究人员还发现,长期给小鼠喂食左旋肉碱可以改变小鼠肠道内细菌组成,导致血液中TMAO升高,动脉硬化发生率显著升高;如果用抗生素抑制肠道细菌,则不会出现动脉硬化。与严格素食主义者或普通素食主义者相比,杂食者血液中含有更多的TMAO,由于肉食者与素食者在其肠道中具有完全不同的细菌类型,因此,这种变化可能依赖于杂食性人肠道内特殊的细菌类型。含肉饮食很可能刺激了能够将左旋肉碱变为TMAO的细菌的生长。流行病学调查发现,血浆中左旋肉碱和心血管病发病率以及心血管严重后果(中风、心肌梗塞和死亡)之间没有显著相关,但如果结合TMAO,它们之间就存在显著的相关。因此,肠道细菌可能是导致食用红肉诱导动脉硬化的原因。 保健品并不是我们想象的那么美好,与我们共生的细菌会将“美味”变成“毒药”!维生素和卵磷脂在日常食物中含量丰富,而B族微生素可以由我们肠道中的细菌自行产生,完全没有必要再补充它们。而左旋肉碱并不是必须营养物质,且本质上并不对人体有多少益处,用于减肥也并不一定有多少作用,相反还可能有很多坏处,还是不吃的好。保健品不是药物,其作用机理非常不清楚,搞不好以为吃了营养品,实则“毒药”下肚,害了自己。建议大家丰富自己的饮食,形成良好的饮食和生活习惯,多吃新鲜水果蔬菜,远离红肉,最重要的是不盲目的服用各种保健品。 善待我们的肠道细菌,注意饮食习惯,除了照顾自己的味蕾还要适当的考虑与我们共生的细菌,为她们提供菌需要的美味(某些碳水化合物和低聚糖等),而不是人类需要的美味。 参考文献: 1, Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease 2, Intestinal microbiota metabolism of L -carnitine, a nutrient in red meat, promotes atherosclerosis
PNAS:肠道微生物群信号可能调控血压 一项研究发现,通过对两个主要的短链脂肪酸(SCFAs)受体——嗅觉受体78 (Olfr78)和Gpr41起作用,肠道微生物群产生的短链脂肪酸(SCFAs)可能在调控血压方面起到作用。 Jennifer L. Pluznick及其同事发现,Olfr78在肾脏中表达,并且会响应短链脂肪酸(SCFAs),特别是响应丙酸盐,而介导肾素分泌。当给小鼠提供丙酸盐的时候,它们的血压会出现幅度大而迅速的基于剂量依赖的下降,而敲除了Olfr78 的小鼠对这种效应特别敏感,这提示Olfr78的正常功能是提高血压并对抗短链脂肪酸(SCFAs)的低血压效应。相比之下,缺乏Gpr41基因的小鼠对丙酸盐没有低血压响应,而这个剂量导致了野生类型的小鼠的强烈低血压响应,这提示Gpr41参与到了对丙酸盐做出响应降低血压。通过给予抗生素而减少Olfr78被敲除小鼠的肠道微生物群生物质导致了它们的血压增加,这提示肠道微生物群制造的丙酸盐通过Olfr78受体调控血压。 这组作者提出,研究肠道微生物群和肾脏-心血管系统的串扰可能有助于更好地理解和治疗高血压。
让中医成为科学 关于中医是不是科学的问题,一直争论不休。 按照科学的定义,理论体系和可验证性是一门科学成立的两个必要条件。理论体系必须符合辩证法和逻辑论,且与其它科学学科相互联系和兼容。可验证性实际是要求在相应实验体系的基础上,能够对实验结果或者理论结果进行检验、重复、证伪和测量。从某种意义上来说,后者比前者更为重要。 中医中药源远流长,它体现东方的文化和我们祖先的智慧。然而它进不了现代医学科学的殿堂,归因于它目前不完全具备上述两个必要条件。 中医可粗分为三个领域:经络、正骨和中药。据悉,用现代科学方法研究经络已取得重大进展。中医正骨的科学性也不难建立。所以,关于中医是否科学的问题,主要集中在中医中药领域。让中医中药成为一门科学的第一步是让它具备上述两个必要条件。 一门新学科的建立,一般是在大量实验的基础上加以归纳和整理,建立相应的规律和理论。中医中药实际上是一门经验医学。几千年来,它一直以阴阳五行为理论依据,以望闻问切为检测方法,无法得到可测量、可重复、可验证的医学数据,也无法进行统计学意义上的现代临床医学试验。因此采用这种方式建立新学科是行不通的。另一种建立新学科的方式是先提出一套新的理论,再设计各种实验去验证和完善它。 本文提出将“改变和调节人体的微生物菌群种类和结构”作为中医中药的理论依据。 目前正在进行的人类微生物组计划是继人类基因组计划之后的国际性重大研究项目。随着研究的进展,将为上述中医中药理论提供越来越多的理论支持、实验数据和检验方法。 对于日常生活中的健康问题,中医都采用热、寒、虚、实来分析和解释。利用新的中医中药理论,也可以解释和理解这些问题,更重要的是它能提供实验检验的方向和方法,将来可以验证它。 例如:在相同的环境条件下,由于温度降低,人会感冒,产生咽炎,中医解释是受凉了,有寒。由于吃热辣的东西太多,也产生咽炎,中医解释是上火了,有热。但寒和热致病的物理机制究竟是什么,至今无法给出科学的解释,更无法给出相应的测量方法和定量的数据。然而,几千年祖祖辈辈都这么说,大家也就接受了这种解释。 我们尝试用新的中医中药理论来解释上述现象: 健康人的咽喉部位具有的微生物菌群种类和结构,我们不妨用 A 处的 A 种微生物, B 处的 B 种微生物来简单表示。现代科学实验已经证明,许多微生物对温度及其敏感。第一种情况,由于温度下降, A 种微生物迁移到了 B 处,与 B 种微生物发生了冲突,产生了咽炎,这种咽炎往往带痰,那是 A 、 B 两种微生物冲突产生的分泌物。第二种情况,由于热辣环境,使 A 种微生物死亡或减少,正常的菌群结构被破坏,因此产生了咽炎,这种咽炎往往不带痰。 西医治疗第一种情况产生的咽炎是将 B 处的 A 种微生物杀死,因此炎症消失,治疗效果快而且明显。但如果 A 处的 A 种微生物没有恢复,正常的菌群结构没有建立,实际上就会变成第二种情况。因此,西药治疗后,人并不舒服,往往处于亚健康状态。 中医治疗第二种情况产生的咽炎(如果中药采用正确),是在 A 处重建 A 种微生物,使咽喉部位恢复正常的微生物菌群种类和结构,使咽炎得到根治。然而,由于不能有效地将 B 处的 A 种微生物去除,对于第一种情况产生的咽炎,中医中药的疗效不佳。 因此,对于带有炎症的急性病,使用西药治疗比较好。而病后的调理采用中药比较好。这实际上已是大家公认的治病方法。 从这个纯粹思辨的案例我们可以看到,新的中医中药理论可以合理地、自洽地解释传统中医所解释的病症。更重要的是,新的中医中药理论还给出了致病的物理机制,从而指导研究者去发明新的(或借鉴现有的)检验方法去验证这种机制的正确性,去进行中医中药与微生物菌群种类和结构的关系的研究,去探讨人体微生物菌群种类和结构的测量、调整和重建的方法。当上述这些工作取得进展并初步构成研究体系的时候,让中医中药成为科学的任务也就完成了。 关于如何初步构成中医中药的科学研究体系,将在下一篇博文中论述。 老石头 2013.1.31. 广州
Nature:新方法研究微生物与宿主相互作用的相关基因日期:2012-11-06 来源:互联网 作者:Snail 点击:201次 摘要: 来自CD和UC领域的研究者们一起分享了原始数据以及新收集的遗传信息,以探索一组累及全球数百万人的疾病的生物学性质。该项研究集中于两种疾病,统称为炎性肠病(IBD),结果提示IBD风险和参与其他免疫相关疾病及免疫系统对病原体产生应答的基因之间存在基本联系。该研究结果于10月31日在线发表在《Nature》杂志上。 克罗恩病(CD)和溃疡性结肠炎(UC)是胃肠道的炎性疾病,已困扰了科学界数十年。10年前,研究者意识到基因和环境可导致这些疾病,但对这些疾病如何发生以及发生的确切原因知之甚少。为了缩小这些疾病涉及的关键途径的范围,需要数千例患者的样本、数百万个数据点以及许多机构的医师和科学家们的贡献。 来自CD和UC领域的研究者们一起分享了原始数据以及新收集的遗传信息,以探索一组累及全球数百万人的疾病的生物学性质。该项研究集中于两种疾病,统称为炎性肠病(IBD),结果提示IBD风险和参与其他免疫相关疾病及免疫系统对病原体产生应答的基因之间存在基本联系。该研究结果于10月31日在线发表在《 Nature 》杂志上。 “这项研究标志着我们首次从全世界这么多研究中获得并综合了原始数据,我们还首次联合分析了克罗恩病和溃疡性结肠炎。” Mark Daly(该研究的高级作者之一,布罗德研究所高级准会员及其医学和人口遗传学项目的共同负责人)说。 “通过这项研究,我们能够同时评价这两种疾病的证据,并发现了与这两种疾病相关的大部分遗传危险因素。” “我们对IBD的了解有了模式上的转变。这次的基因发现过程提供了开始识别治疗新靶点以及更好的诊断方法,而且从长远来看,还为患者的个体化治疗提供了机会。” Ramnik Xavier(MGH胃肠病科主任和炎性肠病研究中心负责人)说。“我们现在已经有了可以开始了解导致克罗恩病和溃疡性结肠炎的途径的必要材料,我们还有了一个框架,可以更好地了解它们可能不是两种不同疾病而是很多不同疾病的聚集。” 克罗恩病(CD)和溃疡性结肠炎(UC)有很多共同点:两者均可导致很多相同的胃肠道症状,两者都以机体免疫系统对无害细胞或细菌产生不正确的应答为特征。在过去10年中,研究者进行了全基因组关联分析,筛查数千例CD或UC患者的基因组,并将它们与无这两种疾病的患者的基因组进行比较,以寻找有意义的遗传差异。这项新研究不仅汇总了既往分析的原始数据,还添加了另外40000份有或没有其中一种IBD者的遗传信息。 “如果我们想获得更多关于克罗恩病和溃疡性结肠炎之间差异的线索,并分析这些差异或了解它们的共性,我们必须分享我们所有的遗传数据。” Stephan Ripke(布罗德研究所和MGH的研究者)说。与Luke Jostins密切合作,汇总并分析了许多不同机构的研究者收集的遗传信息。 这项新研究识别出了IBD的71种额外遗传关联,其中很多既往已被发现参与了其他免疫相关疾病,包括强直性脊柱炎和银屑病。这项新研究还表明,IBD易感性基因与免疫系统对分枝杆菌感染(包括结核病和麻风)的应答相关的基因之间明显重叠。研究者观察到了CD的免疫应答与在结核病中所见的免疫应答之间存在相似性,并假设CD可能是某些存在于消化道并且可引发相似反应的无害微生物异常应答所致。 除了收集既往研究的原始数据,这项研究还利用了一种相对较新的方法(称为免疫芯片),通过这种方法从既往被发现与自身免疫及炎性疾病相关的基因组的20000万个位点取样。 “作为一个研究领域,我们设计了这种测定方法,以免疫介导的各种疾病涉及的基因为靶点。”Daly说。“这是我们首批用免疫芯片的研究之一,这些研究还将得到很多关于IBD和免疫疾病的结果。” 在布罗德研究所,研究者们已经在研究既往UC和CD研究识别出的一些途径,其中包括自噬,这是一种感染细胞吞噬自身以对抗微生物的过程。 “这项研究给了我们额外的研究线索。”Xavier说。“它给了我们进行高质量转化研究的机会,使我们能够识别出IBD涉及的核心途径和更好地了解这些基因如何相互作用及如何与环境相互作用,并阐明了导致疾病的新途径。” 原文摘要: Host–microbe interactions have shaped the genetic architecture of inflammatory bowel disease Luke Jostins, Stephan Ripke, Rinse K. Weersma, Richard H. Duerr, Dermot P. McGovern, Ken Y. Hui, James C. Lee, L. Philip Schumm, Yashoda Sharma, Carl A. Anderson, Jonah Essers, Mitja Mitrovic, Kaida Ning, Isabelle Cleynen, Emilie Theatre, Sarah L. Spain, Soumya Raychaudhuri, Philippe Goyette, Zhi Wei, Clara Abraham, Jean-Paul Achkar, Tariq Ahmad, Leila Amininejad, et al. Crohn’s disease and ulcerative colitis, the two common forms of inflammatory bowel disease (IBD), affect over 2.5 million people of European ancestry, with rising prevalence in other populations. Genome-wide association studies and subsequent meta-analyses of these two diseases as separate phenotypes have implicated previously unsuspected mechanisms, such as autophagy, in their pathogenesis and showed that some IBD loci are shared with other inflammatory diseases5. Here we expand on the knowledge of relevant pathways by undertaking a meta-analysis of Crohn’s disease and ulcerative colitis genome-wide association scans, followed by extensive validation of significant findings, with a combined total of more than 75,000 cases and controls. We identify 71 new associations, for a total of 163 IBD loci, that meet genome-wide significance thresholds. Most loci contribute to both phenotypes, and both directional (consistently favouring one allele over the course of human history) and balancing (favouring the retention of both alleles within populations) selection effects are evident. Many IBD loci are also implicated in other immune-mediated disorders, most notably with ankylosing spondylitis and psoriasis. We also observe considerable overlap between susceptibility loci for IBD and mycobacterial infection. Gene co-expression network analysis emphasizes this relationship, with pathways shared between host responses to mycobacteria and those predisposing to IBD.
人体微生物基因组图谱将为疾病诊疗寻找新途径 6 月 13 日美国研究人员申明已绘制出第一幅寄居于健康人体的微生物的全面基因图谱,这一成果来自于一项旨在更好地了解在从消化到感染等过程中起着关键作用的细菌和其他微生物的研究,是由美国国家健康研究院( National Institutes of Health )资助、耗时五年、耗资 1.73 亿美元的“人体微生物工程”( Human Microbiome Project )的成果之一,它将为医生诊断疾病和治疗病患开启了新的可能性。 这些研究成果发表在《自然》和《公共科学图书馆》等刊物,是基于对美国 242 名健康志愿者的口腔、鼻腔、皮肤、肠道和阴道等位置的样本的研究得出的。在人类基因组计划( Human Genome Project )中绘制 DNA 图谱的高级 DNA 测序机对这些样本进行了分析。 人类基因组计划确认了约有 22,000 个人类基因,而该项目在人体微生物──生活在人体内部或表面的微生物──中发现了超过 800 万个基因,并识别出了 10,000 多种微生物。 为何开展人类微生物组研究? 基因与环境相互作用决定人体健康,目前大量的研究都集中在分析人的基因组成与疾病易感性和药物敏感性的关系上。但是在人体内发挥作用、影响我们生老病死的不仅有人的基因,还有大量的共生微生物的基因。 人体内有两个基因组,一个是从父母那里遗传来的人基因组,编码大约 2.5 万个基因;另一个则是出生以后才进入人体的数万亿共生微生物──实际上,它们的数量超过了人体细胞,二者之比为 10 : 1 。特别是肠道内的多达 1000 多 种的共生微生物,其遗传信息的总和叫“微生物组”,也可称为“元基因组”,它们所编码的基因有 100 万个以上。两个基因组相互协调、和谐一致,保证了人体 的健康。因此,在研究基因与人体健康关系时,一定不能忽略共生微生物基因的研究。 人类微生物组是如何影响人体健康的? 通过下面几个最新科学研究进展的例子,可以来说明肠道微生物组与人体健康的关系。 1 )英国帝国理工大学教授尼科尔森的研究组 2006 年在《自然》杂志报道,通过对给药前大鼠的尿液代谢物进行全谱测定,可以把同一个遗传品系的大鼠分成两个类型,在给予高剂量的同一种药物后,一种类型表现出肝中毒的症状,另一种则安然无恙。研究发现,能够把遗传特性高度相似的个体区别开的尿液代谢物主要是肠道菌群产生的,未出现肝中毒症状的大鼠肠道里存在着可以把药物解毒的细菌,这些细菌保护了宿主。由此可见,肠道微生物组的基因组成与个体对药物的敏 感性有密切关系。最近,他们又在《自然》杂志报道,通过对中国、美国、日本和英国等 4 个国家 17 个不同地区的 4630 名志愿者尿液代谢组学分析,发现高血 压与肠道菌群的组成具有密切的关系。 2 )美国华盛顿大学戈登小组 2006 年在《自然》杂志报道,肥胖小鼠的肠道菌群可以把人体不能消化的植物纤维,转变成短链脂肪酸供人体吸收利用,增加人体从食 物中获得热量的能力。细菌还可以直接调节人体脂肪代谢途径的基因表达活性,减少脂肪酸的氧化,增加甘油三酯从源头上的合成。研究人员认为,肠道菌群产生的 某种因子,很有可能是启动机体肥胖所必需的。 3 )英国里丁大学吉布森小组 2007 年在《糖尿病》杂志报道,高脂食物显著减少双歧杆菌等保护肠道屏障的细菌,致使产生内毒素的细菌明显增加,导致进入血液的 内毒素增加,引起低度的慢性炎症,最后导致胰岛素抵抗等一系列代谢紊乱疾病。这一研究是通过动物模型进行的,在人体上是什么情况还需要研究。研究人体共生 微生物的基因,为阐明代谢性疾病等多种慢性病的病因提供了一种创新性的思维和方法,并为有效预防和治疗这些疾病带来了新的希望。 为诊断和治疗疾病寻找新途径 圣路易斯( St. Louis )华盛顿大学医学院( Washington University School of Medicine )的小儿消化与营养科主任菲利普•塔尔( Phillip Tarr )是这项涉及 80 家机构、约 200 名研究人员的项目的带头人之一,他说,“这实际上是生物学的一个新领域。”这幅新基因图谱将支持对一些起因综合了遗传因素与人体细菌群落变化的疾病的研究。 旧金山加利福尼亚大学( University of California )的生物学家迈克尔•费施巴赫( Michael Fischbach )称,“这项研究可能将导致对克罗恩氏病 的新疗法、对糖尿病和代谢疾病的新疗法,以及对其他疾病,例如湿疹的新疗法。”他未参与该项目。费施巴赫博士提醒,相关新药上市之前“还需要很长一段时间”,因为仍有许多问题需要解决──不仅是基因与细菌之间的相互作用,还有细菌在不同人体之间的巨大差异。研究人员称,从人类历史开始之时,微生物就寄居在人体之中。美国国家人类基因组研究所( National Human Genome Research Institute )主任埃里克•格林( Eric Green )称,“多数时候我们与它们和谐共处。”它们在消化和其他对人类生存十分重要的过程中起着关键作用。 但有时,这种有益关系会瓦解,进而导致疾病。格林博士称,“我们需要更好地了解正常微生物是什么样,以及什么情况下它会发生改变,进而引发或影响疾病。”该项目的研究人员之一、得克萨斯贝勒医学院儿童微生物中心( Texas Children's Microbiome Center at Baylor College of Medicine )主任詹姆斯•韦尔萨罗维克( James Versalovic )说,“这给出了健康人的基因与微生物参考组。”根据计划,研究人员将对儿童、老年人、来自非洲和南美洲等洲的人以及病人身上的微生物进行类似分析,以探明微生物在维持健康或引发疾病中所扮演的角色。 来源:生物探索
与人类完美共生的微生物 胃肠的粘膜表面具有复杂的微环境,许多无害的微生物寄居于此。然而病原微生物也企图破坏粘膜的表面,打开入侵人体的大门。这些病原微生物要么直接侵入粘膜,要么分泌毒素破坏之。肠表皮的细胞也进化出一套防御机制,如一些非经典免疫细胞表达 MHC I , II 参与对病原微生物的免疫识别,还有的细胞在膜上表达 Toll-like 受体,使之能检测到病菌的存在,且引发免疫反应。 已知这些防御机制怎样分清敌我呢 ?Science 上 intimin 提出了一个观点,无非致病的沙门氏菌不会引起肠表皮合成炎症因子,他们发现此细菌抑制了 IkB 的降解, IkB 是一个重要转录因子 NF - kB 的抑制剂,正是此效应诱导了细菌对肠表皮细胞的耐受。 肠道内的微生物与生物体具有良好的共生关系,两者互惠互利。有益微生物与有害微生物的特征区分并不明显,一般来说,病原微生物会有一些附着装置,如 (type III translocation proteins) ,致病 E.coli 结合在人体肠表皮细胞上的 intimin 蛋白上, intimin 的工作是第一例报道有益微生物怎样避免表皮细胞的炎症反应的。 越来越多的证据表明 NF - kB 是肠炎症免疫反应的重要因子, IkB 与 NF - kB 结合时定位在核外,当 IkB 被 IkBa,b 磷酸化后,引起泛素化及降解,然后 NF - kB 得以入核行使转录因子功能。已知许多病原微生物可以激活 NF - kB 。 随着研究的深入,我们对在这个充满敌意的世界上与自己完美共生的一些微生物的了解日益加深。 A bug's life. Nonpathogenic Salmonella bacteria interfere with NF-kB activation in gut epithelial cells. The transcription factor NF-kB is activated by binding of bacterial products such as lipopolysaccharide to the surface of gut epithelial cells. Commensal bacteria that normally inhabit the gut such as nonpathogenic Salmonella have devised schemes to interfere with NF-kB activation and hence with the expression of genes involved in the inflammatory response. Nonpathogenic Salmonella block ubiquitination (UBQ) and degradation of IkB, an inhibitor that binds to and sequesters NF-kB in the cytoplasm. When IkB is degraded, NF-kB is released and moves to the nucleus where it switches on target genes involved in inflammation. This strategy may explain the virtual absence of inflammation in the gut mucosa despite its constant exposure to a variety of indigenous bacteria. 相关文章: Prokaryotic Regulation of Epithelial Responses by Inhibition of IB- Ubiquitination. Andrew S. Neish, Andrew T. Gewirtz, Hui Zeng, Andrew N. Young, Michael E. Hobert, Vinit Karmali, Anjali S. Rao, and James L. Madara Science 2000 289: 1560-1563. (in Reports) R. Medzhitov, P. Preston-Hurlburt, C. A. Janeway Jr., Nature 388, 394 (1997) . E. Cario et al., J. Immunol. 164, 966 (2000) . A. S. Neish et al., Science 289, 1560 (2000). L. Bry, P. G. Falk, T. Midtvedt, J. I. Gordon, Science 273, 1380 (1996). L. M. Higgins et al., Science 285, 588 (1999). M. Karin and Y. Ben-Neriah, Annu. Rev. Immunol. 18, 621 (2000) . K. Orth et al., Science 285, 1920 (1999). B. J. Rembacken et al., Lancet 354, 635 (1999) . P. Gionchetti et al., Gastroenterology 119, 305 (2000)
Mantel test 是对两个矩阵相关关系的检验,由 Nathan Mantel 在1976年提出。之所以抛开相关系数发展这样一种方法,是因为相关系数只能处理两列数据之间的相关性,而在面对两个矩阵之间的相关性时就束手无策。Mantel检验专治这种不服。 这种方法多用于生态学上,不同的样本case对应不同的变量,而不同的变量可以分属不同的类别,对case有不同角度的刻画。如基于不同植物种类数量可以建立样本间的两两距离矩阵,只需套用距离计算公式即可;不同样本的微生物clone序列,通过Unifrac方法也可以计算得到样本间距离矩阵;不同位置,两两间距离也可以用距离表示。所得到这些矩阵,如果希望验证两类描述间有没有相关关系,就非常有用了。比如我希望检验微生物群落是否和植被群落有对应关系,就可以将微生物Unifrac矩阵对植物的比如Bray-Curtis距离矩阵做个相关分析,由得到的结果得出自己的推论。这种方法的好处在于,不管你是什么数据,只要能计算有距离属性的值,都可以转化为距离矩阵进行分析。本人《空间方法在微生物生态学中的应用》(好像是生态学报2010年2月)一文中已有提及,在此延伸到实际应用。 Mantel test,顾名思义,是一种检验。既然是检验就得有原假设,它的原假设是两个矩阵见没有相关关系。检验过程如下:两个矩阵都对应展开,变量两列,计算相关系数(理论上什么相关系数都可以计算,但常用pearson相关系数),然后其中一列或两列同时置换,再计算一个值,permutation 成千上万次,看实际的r值在所得r值分布中的位置,如果跟随机置换得到的结果站队较近,则不大相关,如果远远比随机由此得到显著性。 如图,得到的值在这个区域,说明跟随机出现的数值比较接近,因此 $z.stat 6.009877 $p 0.519 这里使用的是z统计量,不是r,使用的ape包里的 mantel.test() 函数。 The function calculates a Z-statistic for the Mantel test, equal to the sum of the pairwise product of the lower triangles of the permuted matrices, for each permutation of rows and columns. It compares the permuted distribution with the Z-statistic observed for the actual data. 然后用vegan算,用r统计量,得到差不多的结果,也是不显著。 mantel(q1,q2) Mantel statistic based on Pearson's product-moment correlation Call: mantel(xdis = q1, ydis = q2) Mantel statistic r: 0.169 Significance: 0.279 Empirical upper confidence limits of r: 90% 95% 97.5% 99% 0.351 0.425 0.516 0.597 Based on 999 permutations 但是不同相关方法会对结果造成很大的影响, mantel(veg.dist, env.dist) Mantel statistic based on Pearson's product-moment correlation Call: mantel(xdis = veg.dist, ydis = env.dist) Mantel statistic r: 0.3047 Significance: 0.001 Empirical upper confidence limits of r: 90% 95% 97.5% 99% 0.113 0.150 0.174 0.215 Based on 999 permutations mantel(veg.dist, env.dist, method="spear") Mantel statistic based on Spearman's rank correlation rho Call: mantel(xdis = veg.dist, ydis = env.dist, method = "spear") Mantel statistic r: 0.2838 Significance: 0.001 Empirical upper confidence limits of r: 90% 95% 97.5% 99% 0.126 0.160 0.187 0.223 Based on 999 permutations 此处我的理解是:这说明对矩阵也需要检验其分布假设,不符合分布假设的条件下用spearman秩相关更靠谱。偏mantel相关函数包括三个变量(矩阵),即控制第三个矩阵影响下前两个矩阵的相关性。 进一步关于Mantel correlogram。这种方法基于上述相关系数,不过其中一个矩阵换成了设计好的不同距离矩阵,分析相关性,得到不同距离下某多元变量组与之相关性的结果。 mite.correlog = mantel.correlog(mite.hel.D, XY=mite.xy, nperm=999) mite.correlog Mantel Correlogram Analysis Call: mantel.correlog(D.eco = mite.hel.D, XY = mite.xy, nperm = 999) class.index n.dist Mantel.cor Pr(Mantel) Pr(corrected) D.cl.1 0.514182 358.000000 0.135713 0.001 0.001 *** D.cl.2 1.242546 650.000000 0.118174 0.001 0.002 ** D.cl.3 1.970910 796.000000 0.037820 0.052 0.052 . D.cl.4 2.699274 696.000000 -0.098605 0.001 0.004 ** D.cl.5 3.427638 500.000000 -0.112682 0.001 0.005 ** D.cl.6 4.156002 468.000000 -0.107603 0.001 0.006 ** D.cl.7 4.884366 364.000000 -0.022264 0.134 0.134 D.cl.8 5.612730 326.000000 NA NA NA D.cl.9 6.341094 260.000000 NA NA NA D.cl.10 7.069458 184.000000 NA NA NA D.cl.11 7.797822 130.000000 NA NA NA D.cl.12 8.526186 66.000000 NA NA NA D.cl.13 9.254550 32.000000 NA NA NA --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 A table with the distance classes as rows and the class indices, number of distances per class, Mantel statistics (computed using Pearson's r, Spearman's r, or Kendall's tau), and p-values as columns. A positive Mantel statistic indicates positive spatial correlation. An additional column with p-values corrected for multiple testing is added unless mult="none". 这种方法多用于空间分析中,用于表征不同尺度下某多元变量的变化趋势。我还没有见过用到dna数据上的,可以考虑写个东西。 基本就这些吧,见到有新鲜应用再讨论。
能遏制细菌生长的天然产物 美国科学家揭秘亥姆霍兹感染中心所发现天然药物的作用机制 2012年8月3日 电子显微镜下的Sorangium cellulosum细菌图。 S. Cellulosum属于粘细菌,从中可以提取包括Ripostatin在内的多种天然产物。 一支国际研究团队在著名《科学》杂志上发表文章,阐释一类天然产物抑制细菌生长的机理。亥姆霍兹感染研究中心(HZI)发现的这种产物可以阻断细菌细胞中的RNA聚合酶,后者负责读取遗传信息。科研人员通过超级敏感的分析手段证明,这种有效成分对酶的攻击是在不同的作用点上,不同于迄今的各种抗生素,因此可以开发全新的抗菌药物。 Myxopyronin、Corallopyronin和Ripostatin都源自于粘细菌。这种土壤微生物可以产出一系列具有生物活性的化合物。有些具有抗癌作用,比如同样由HZI发现的埃博霉素已经是上市抗癌药物。而另一类化合物如Myxopyronin、Corallopyronin和Ripostatin则可以杀灭其他细菌。 HZI科研人员在多年前就发现,这些活性成份可以抑制细菌RNA聚合酶。他们如今与美国新泽西州罗格斯大学的伙伴一起澄清了作用机制。酶的外形有个类似于蟹钳的结构。为了能绑定细菌DNA,这个钳首先需要张开,尔后在读码过程中咬合关闭。而Myxopyronin、Corallopyronin和Ripostatin可以阻止酶钳的重新张开,致使RNA聚合酶被卡住,无法读出进一步的基因。 借助高度敏感的“smFRET”(单分子荧光共振能量转移)标记法,美国合作伙伴理查德·埃布赖特(Richard Ebright)和阿里班.查克拉伯蒂(Anirban Chakraborty)成功地测量出在不同读码阶段两个“分子剪刀”的开口距离大小,进而验证了该化合物的作用机制。 HZI“微生物有效成分”科研组的罗尔夫·詹森(Rolf Jansen)博士说:“值得关注的是看到我们发现的物质其作用机制跟所有其他已知抗生素全然不同,这有助于对已经耐其他抗生素的病原体开发全新药物。”他的同事赫伯特.伊希克(Herbert Irschik)补充说,目前这些物质还不当作药物来用:“它们在培养皿中表现出很好抗菌效果。但要体内见到同样效果并保证病人可以耐受,必须做进一步的开发。我们至今仍不能肯定药物开发的路还有多漫长。”这有待于看研究人员未来的科研结果。 “这项科研结果提示我们,粘细菌与其他天然产物中还有多大潜力”,HZI“微生物天然产物”部的负责人罗尔夫·米勒(Rolf Müller)教授说。 “许多药物、尤其是对治传染病的药物自于自然界。我们确信我们会在未来几年继续发现一些具有很好苗头的化合物。” HZI“微生物有效成份”科研组的研究重点是从粘细菌中查找并提取有可能开发成为抗菌药物的各种物质。 原始出版物: Opening and Closing of the Bacterial RNA Polymerase Clamp Anirban Chakraborty, Dongye Wang, Yon W. Ebright, You Korlann, Ekaterine Kortkhonjia, Taiho Kim, Saikat Chowdhury, Sivaramesh Wigneshweraraj, Herbert Irschik, Rolf Jansen, B. Tracy Nixon, Jennifer Knight, Shimon Weiss, and Richard H. Ebright Science 3 August 2012: 591-595 参考:2008年基于一篇CELL文章的生物谷的相关博文 http://bbs.bioon.net/bbs/home.php?mod=spaceuid=504722do=blogid=1638
亥姆霍兹环境研究中心UFZ寻求饮用水污染微生物快速检测合作伙伴 (也算是技术转移与合作的一种方式) 德国亥姆霍兹环境研究中心UFZ的Thomas Mascow博士所在科研团队新近发表了关于一种基于微生物发热计量用于快速检验饮用水污染的技术路线。因为德国乃至欧洲已经有基于其他化学原理的成熟技术,德方希望在中国或其他新兴经济体国家找到技术合作伙伴,以探讨共同开发完善工艺并找到市场应用的空间。 Mascow博士提出对合作方的希望: 从过去的原理性测试的经验来看,我们比较希望与具有较强环境生物学背景的优秀科研团队合作。 对合作伙伴的主要期望是: 有足够的从事水质中微生物分析的研究条件和相关经验;关注饮用水、矿泉水、食品用水以及医药行业的用水安全,包括在工业或家庭的污水排放外之外的所有涉及需要监控微原微生物污染的各种水体。 - 合作伙伴应拥有生物安全实验室和接触致病菌的权限,能够在分子生物学水平对细菌族群进行分类甄别 - 指纹图谱技术(针对不同的进化标记基因(16S rRNA的目标)的T-RFLP) - RTQ-PCR技术 - 定量分析细菌的手段(如荧光原位杂交 FISH技术 ) - 合作中或者可能会用上基于质谱分析的相关设备 - 非常重要的考虑还包括科研实力之外的社会资源,包括与产业用户及上级监管部门有充分的沟通交流,以方便接下来根据实际情况共同做实际现场测试和联合产品开发。 欢迎有良好微生物工业应用基础或重点从事饮用水污染检测相关单位跟亥姆霍兹北京代表处进行联系。 亥姆霍兹北京代表处地址: 北京朝阳区东三环北路8号 亮马河大厦2-1723 邮编 100004 联系人:刘彤 电话: 65907865; 传真:65907867 邮箱: info@helmholtz.cn 一种新式的基于微生物热量计量的饮用水污染快速检测法.pdf Rapid analysis of bacterial contamination of tap water using isothermal calorimetry Thomas Maskow∗, Katrin Wolf, Wolfgang Kunze, Sabine Enders, Hauke Harms Calorimetry was applied to monitor bacterial contamination in tap water. The method allowed faster contaminant detection than conventional methods. Theoretical considerations show that calorimetry is superior to colony detection. Quantification of the contaminant was also possible with the new method. Heat signals were characteristic for the combination of strain, medium and conditions.
2011年12月28日发表在《 PLoS ONE 》上的论文表明蚊子咬不咬你可能由你皮肤共生微生物决定。这个研究很有意思,他们找了20-64岁之间的成年男性,实验前禁止饮酒,吃蒜,洋葱等辛辣食物,禁止用香味物质沐浴。给他们穿经过杀菌消毒过的尼龙袜子。采集左脚上的气味物质让蚊子闻,记录对它们的吸引力,之后采集被试左脚底板皮肤上的菌样进行16sRNA分析。研究发现皮肤上面的菌表现高丰度,低多样性的个体更吸引蚊子。高吸引性个体中葡萄球菌Staphylococcus含量是低吸引性个体的2.62倍,而在低吸引性个体身上假单胞菌Pseudomonas的含量是高吸引性个体的3.11倍。贪食菌属Variovoraxspp.和假单胞菌属Pseudomonasspp.与低吸引性群体显著相关。纤毛菌属Leptotrichiaspp.,Delftiaspp.和放线菌Gp3属ActinobacteriaGp3spp.与高吸引性群体显著相关。 只是这个试验有些缺陷,他们用的是脚上皮肤的菌,而且只是给被试穿尼龙袜子但是并没有规定穿什么鞋,鞋可能会影响菌,运动鞋不透气,易出汗,肯定非常臭。出汗多了菌数量应该就多,可能太臭了,氨,硫化氢,吲哚等物质抑制了一些菌的生长导致菌的数量多,但是菌的丰度,也就是菌的种类变少了,因此更加吸引蚊子,所以我推测可能脚越臭越吸引蚊子!这一结果与我们日常生活经验就比较一致了,记得小时候,夏天上床睡觉前妈妈都让洗脚,说这样蚊子不咬,另外去水沟里或泥坑里玩过之后也更招蚊子。 这个结果也算是对“卫生假说”的一个扩展,身体上菌的种类多了,丰富了,身体才能更健康,甚至连蚊子都不咬了,也就很少得疟疾。 如果这一结论是真的的话,将来可以从补充皮肤细菌种类角度开发驱蚊产品,如开发提高皮肤细菌多样性的菌的食物或增殖剂,或者直接喷上与人体皮肤共生的多种细菌。 参考文献: http://dx.doi.org/10.1371/journal.pone.0028991 Composition of Human Skin Microbiota Affects Attractiveness to Malaria Mosquitoes Niels O. Verhulst, Yu Tong Qiu, Hans Beijleveld, Chris Maliepaard, Dan Knights, Stefan Schulz, Donna Berg-Lyons, Christian L. Lauber, Willem Verduijn, Geert W. Haasnoot, Roland Mumm, Harro J. Bouwmeester, Frans H. J. Claas, Marcel Dicke, Joop J. A. van Loon, Willem Takken, Rob Knight, Renate C. Smallegange The African malaria mosquito Anopheles gambiae sensu stricto continues to play an important role in malaria transmission, which is aggravated by its high degree of anthropophily, making it among the foremost vectors of this disease. In the current study we set out to unravel the strong association between this mosquito species and human beings, as it is determined by odorant cues derived from the human skin. Microbial communities on the skin play key roles in the production of human body odour. We demonstrate that the composition of the skin microbiota affects the degree of attractiveness of human beings to this mosquito species. Bacterial plate counts and 16S rRNA sequencing revealed that individuals that are highly attractive to An. gambiae s.s. have a significantly higher abundance, but lower diversity of bacteria on their skin than individuals that are poorly attractive. Bacterial genera that are correlated with the relative degree of attractiveness to mosquitoes were identified. The discovery of the connection between skin microbial populations and attractiveness to mosquitoes may lead to the development of new mosquito attractants and personalized methods for protection against vectors of malaria and other infectious diseases.
原文链接: http://blog.sciencenet.cn/home.php?mod=spaceuid=236900do=blogid=549521 全文如下: 已有大量研究表明自闭症可能与肠道菌群紊乱有关。也有报道给自闭症儿童服用某些益生菌能够减去自闭症症状甚至治愈。自闭症儿童常出现胃肠道失调,可能肠道微生物组成也相应发生变化。这些报道提示我们自闭症与肠道健康状况密切相关。 最近的一项来自美国哥伦比亚大学的研究表明,超过一半的伴有胃肠功能肠癌的自闭症儿童肠道中发现了一种肠道微生物-萨特菌( Sutterella )。他们通过回肠和盲肠活体组织取样检测共生微生物多样性,对伴有胃肠功能肠癌的自闭症儿童和仅患有胃肠功能障碍的正常儿童对比发现,发现在一些自闭症儿童肠道中检测到了产碱菌科 Alcaligenaceae 的某些成员,而对照组中没有发现。而这些产碱菌属水平的升高是由于萨特菌( Sutterella )的水平较高。通过对 Sutterella 的16S rRNA 基因序列分析发现,在23个伴有胃肠功能肠癌的自闭症儿童中的12个个体中都发现了萨特菌( Sutterella ),而在9个对照组完全没有发现萨特菌( Sutterella )的存在。进一步的系统发育分析表明,在检测的12个个体中的11个阳性个体中,其肠道萨特菌( Sutterella )中有两类菌占绝大多数,他们分别是华德萨特菌 Sutterella wadsworthensis 和 Sutterella stercoricanis 。 此外,他们首次报道了一种萨特菌特异PCR( Sutterella -specific PCR),用于从生物或环境样品中对萨特菌( Sutterella )进行检测、定量以及基因型分析。 自闭症影响着世界上大约1%的人群,对肠道微生物的研究,尤其是共生微生物的研究将有助于我们了解肠道微生物与自闭症的关系。 有需要探讨益生菌的请加我QQ:99593398,我熟悉 Culturelle Probiotic 。 附原文摘要: Application of Novel PCR-Based Methods for Detection, Quantitation,and Phylogenetic Characterization of Sutterella Species in Intestinal Biopsy Samples from Children with Autism and Gastrointestinal Disturbances Brent L. Williams, Mady Hornig, Tanmay Parekh, and W. Ian Lipkin Center for Infection and Immunity, Mailman School of Public Health, Columbia University, New York, New York, USA ABSTRACT Gastrointestinal disturbances are commonly reported in children with autism and may be associated with compositional changes in intestinal bacteria. In a previous report, we surveyed intestinal microbiota in ileal and cecal biopsy samples from children with autism and gastrointestinal dysfunction (AUT-GI) and children with only gastrointestinal dysfunction (Control-GI). Our results demonstrated the presence of members of the family Alcaligenaceae in some AUT-GI children, while no Control-GI children had Alcaligenaceae sequences. Here we demonstrate that increased levels of Alcaligenaceae in intestinal biopsy samples from AUT-GI children result from the presence of high levels of members of the genus Sutterella.We also report the first Sutterella-specific PCR assays for detecting, quantitating, and genotyping Sutterella species in biological and environmental samples. Sutterella 16S rRNA gene sequences were found in 12 of 23 AUT-GI children but in none of 9 Control-GI children. Phylogenetic analysis revealed a predominance of either Sutterella wadsworthensis or Sutterella stercoricanis in 11 of the individual Sutterella-positive AUT-GI patients; in one AUT-GI patient, Sutterella sequences were obtained that could not be given a species-level classification based on the 16S rRNA gene sequences of known Sutterella isolates. Western immunoblots revealed plasma IgG or IgM antibody reactivity to Sutterella wadsworthensis antigens in 11 AUT-GI patients, 8 of whom were also PCR positive, indicating the presence of an immune response to Sutterella in some children. IMPORTANCE Autism spectrum disorders affect ~1% of the population. Many children with autism have gastrointestinal (GI) disturbances that can complicate clinical management and contribute to behavioral problems. Understanding the molecular and microbial underpinnings of these GI issues is of paramount importance for elucidating pathogenesis, rendering diagnosis, and administering informed treatment. Here we describe an association between high levels of intestinal, mucoepithelial-associated Sutterella species and GI disturbances in children with autism. These findings elevate this little-recognized bacterium to the forefront by demonstrating that Sutterella is a major component of the microbiota in over half of children with autism and gastrointestinal dysfunction (AUT-GI) and is absent in children with only gastrointestinal dysfunction (Control-GI) evaluated in this study. Furthermore, these findings bring into question the role Sutterella plays in the human microbiota in health and disease. With the Sutterella-specific molecular assays described here, some of these questions can begin to be addressed.
已有大量研究表明自闭症可能与肠道菌群紊乱有关。也有报道给自闭症儿童服用某些益生菌能够减去自闭症症状甚至治愈。自闭症儿童常出现胃肠道失调,可能肠道微生物组成也相应发生变化。这些报道提示我们自闭症与肠道健康状况密切相关。 最近的一项来自美国哥伦比亚大学的研究表明,超过一半的伴有胃肠功能肠癌的自闭症儿童肠道中发现了一种肠道微生物-萨特菌( Sutterella )。他们通过回肠和盲肠活体组织取样检测共生微生物多样性,对伴有胃肠功能肠癌的自闭症儿童和仅患有胃肠功能障碍的正常儿童对比发现,发现在一些自闭症儿童肠道中检测到了产碱菌科 Alcaligenaceae 的某些成员,而对照组中没有发现。而这些产碱菌属水平的升高是由于萨特菌( Sutterella )的水平较高。通过对 Sutterella 的16S rRNA 基因序列分析发现,在23个伴有胃肠功能肠癌的自闭症儿童中的12个个体中都发现了萨特菌( Sutterella ),而在9个对照组完全没有发现萨特菌( Sutterella )的存在。进一步的系统发育分析表明,在检测的12个个体中的11个阳性个体中,其肠道萨特菌( Sutterella )中有两类菌占绝大多数,他们分别是华德萨特菌 Sutterella wadsworthensis 和 Sutterella stercoricanis 。 此外,他们首次报道了一种萨特菌特异PCR( Sutterella -specific PCR),用于从生物或环境样品中对萨特菌( Sutterella )进行检测、定量以及基因型分析。 自闭症影响着世界上大约1%的人群,对肠道微生物的研究,尤其是共生微生物的研究将有助于我们了解肠道微生物与自闭症的关系。 附原文摘要: Application of Novel PCR-Based Methods for Detection, Quantitation,and Phylogenetic Characterization of Sutterella Species in Intestinal Biopsy Samples from Children with Autism and Gastrointestinal Disturbances Brent L. Williams, Mady Hornig, Tanmay Parekh, and W. Ian Lipkin Center for Infection and Immunity, Mailman School of Public Health, Columbia University, New York, New York, USA ABSTRACT Gastrointestinal disturbances are commonly reported in children with autism and may be associated with compositional changes in intestinal bacteria. In a previous report, we surveyed intestinal microbiota in ileal and cecal biopsy samples from children with autism and gastrointestinal dysfunction (AUT-GI) and children with only gastrointestinal dysfunction (Control-GI). Our results demonstrated the presence of members of the family Alcaligenaceae in some AUT-GI children, while no Control-GI children had Alcaligenaceae sequences. Here we demonstrate that increased levels of Alcaligenaceae in intestinal biopsy samples from AUT-GI children result from the presence of high levels of members of the genus Sutterella.We also report the first Sutterella-specific PCR assays for detecting, quantitating, and genotyping Sutterella species in biological and environmental samples. Sutterella 16S rRNA gene sequences were found in 12 of 23 AUT-GI children but in none of 9 Control-GI children. Phylogenetic analysis revealed a predominance of either Sutterella wadsworthensis or Sutterella stercoricanis in 11 of the individual Sutterella-positive AUT-GI patients; in one AUT-GI patient, Sutterella sequences were obtained that could not be given a species-level classification based on the 16S rRNA gene sequences of known Sutterella isolates. Western immunoblots revealed plasma IgG or IgM antibody reactivity to Sutterella wadsworthensis antigens in 11 AUT-GI patients, 8 of whom were also PCR positive, indicating the presence of an immune response to Sutterella in some children. IMPORTANCE Autism spectrum disorders affect ~1% of the population. Many children with autism have gastrointestinal (GI) disturbances that can complicate clinical management and contribute to behavioral problems. Understanding the molecular and microbial underpinnings of these GI issues is of paramount importance for elucidating pathogenesis, rendering diagnosis, and administering informed treatment. Here we describe an association between high levels of intestinal, mucoepithelial-associated Sutterella species and GI disturbances in children with autism. These findings elevate this little-recognized bacterium to the forefront by demonstrating that Sutterella is a major component of the microbiota in over half of children with autism and gastrointestinal dysfunction (AUT-GI) and is absent in children with only gastrointestinal dysfunction (Control-GI) evaluated in this study. Furthermore, these findings bring into question the role Sutterella plays in the human microbiota in health and disease. With the Sutterella-specific molecular assays described here, some of these questions can begin to be addressed. 原文链接: MBio. 2012 Jan 10;3(1). pii: e00261-11. doi: 10.1128/mBio.00261-11 http://mbio.asm.org/content/3/1/e00261-11.long 谢谢牛登科老师提供链接!
整整三年了,我当年在西农的师弟博士都毕业啦,新来的博后也比我还年轻。我还在这里混日子,说到混日子呢,在那里都是混。读着说起来也不咋轻松的德国PhD。 自从从农药植保转到现在微生物天然产物生物合成和生物技术上,花了大约一年半的时间,在拼命的看文献,填知识的gap,从前没做过PCR,没提过质粒,没养过E.coli。一来啥也不敢干,不会干,心里怕做实验。后来慢慢越来越明白,边做实验边学习,不能啥都想好啦,学会啦,再去做实验,那样永远都没法做实验。学着尝试,学会尝试,try, try。这世界没有人知道所有的知识,预测所有的可能结果。就像他们说的,老板最喜欢的不是你做出了预料的结果,而是做出了意想不到,意料之外的结果。不要去做那些都已经很明白,一眼就能看到底的project,要选择那些解决未解决的问题,就算不能一时解决掉,做一做,总会有些结果,说不定某一天,柳暗花明又一村,踏破铁鞋无觅处。暮然回首,竟在灯火阑珊处。 最近参加了两个会议,一个是每年例行的VAAM workshop:Biology of bacteria producing natural products。在Bonn举行,主要就是关于微生物天然产物分离,活性物质的筛选方法,微生物天然产物的生物合成途径调控和组合生物合成。包括德国等欧洲国家和美国的教授和学生,主要是博士生用来练习报告的。我也作了一个报告还有一个poster。那个是真紧张啊。参见另外一篇博文。 另外一个是在西班牙由欧洲分子生物学协会和欧洲科学基金联合举办的 Synthetic biology of antibiotic production。基本上世界上合成生物学和生物合成的领域的大牛都到啦 Roy Kishony, Christina Smolke, Jörg Stelling, Nancy Keller, Russell Cox, Axel Brakhage, Jens Nielsen(没来),Tom Simpson , Joern Piel ,Peter Leadlay, Wolfgang Wohlleben, Luis Serrano ,Haruo Ikeda, Michael Fischbach, Chris Voigt 。算是开了眼界,自己也顿时觉得无限的渺小,自己的科研也是无限的渺小。然后回来就安心安心淡定淡定的做实验。 好好干活。淡定的做实验。 觉得写的真烂。欢迎批评指正。 Life is too short to waste。Do my best todesign and completethe experiments。 Bless me!
Comparison of Microbial Community Compositions of Injection and Production Well Samples in a Long-Term Water-Flooded Petroleum Reservoir Ren H, Zhang X *, Song Z, Rupert W, Gao G, Guo S, Zhao L. Comparison of Microbial Community Compositions of Injection and Production Well Samples in a Long-term Water-Flooded Petroleum Reservoir. Plos One , 2011 , 6(8): e23258. doi:10.1371/journal.pone.0023258 Abstract Water flooding plays an important role in recovering oil from depleted petroleum reservoirs. Exactly how the microbial communities of production wells are affected by microorganisms introduced with injected water has previously not been adequately studied. Using denaturing gradient gel electrophoresis (DGGE) approach and 16S rRNA gene clone library analysis, the comparison of microbial communities is carried out between one injection water and two production waters collected from a working block of the water-flooded Gudao petroleum reservoir located in the Yellow River Delta. DGGE fingerprints showed that the similarities of the bacterial communities between the injection water and production waters were lower than between the two production waters. It was also observed that the archaeal composition among these three samples showed no significant difference. Analysis of the 16S rRNA gene clone libraries showed that the dominant groups within the injection water were Betaproteobacteria, Gammaproteobacteria and Methanomicrobia, while the dominant groups in the production waters were Gammaproteobacteria and Methanobacteria. Only 2 out of 54 bacterial operational taxonomic units (OTUs) and 5 out of 17 archaeal OTUs in the injection water were detected in the production waters, indicating that most of the microorganisms introduced by the injection water may not survive to be detected in the production waters. Additionally, there were 55.6% and 82.6% unique OTUs in the two production waters respectively, suggesting that each production well has its specific microbial composition, despite both wells being flooded with the same injection water. 原文链接:http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0023258 pdf原文: Ren2011-pLOSone.pdf
A diverse bacterial community in a n anoxic quinoline-degrading bioreactor determined by using pyrosequencing and clone library analysis Zhang X , Yue S , Zhong H, Hua W, Chen R, Cao Y, and Zhao L . A diverse bacterial community in a n anoxic quinoline-degrading bioreactor determined by using pyrosequencing and clone library analysis. Applied Microbial and Biotechnology , 2011, 91:425–434. Abstract There is a concern of whether the structure and diversity of a microbial community can be effectively revealed by short-length pyrosequencing reads. In this study, we performed a microbial community analysis on a sample from a high-efficiency denitrifying quinolinedegrading bioreactor and compared the results generated by pyrosequencing with those generated by clone library technology. By both technologies, 16S rRNA gene analysis indicated that the bacteria in the sample were closely related to, for example, Proteobacteria, Actinobacteria, and Bacteroidetes. The sequences belonging to Rhodococcus were the most predominant, and Pseudomonas, Sphingomonas, Acidovorax, and Zoogloea were also abundant. Both methods revealed a similar overall bacterial community structure. However, the 622 pyrosequencing reads of the hypervariable V3 region of the 16S rRNA gene revealed much higher bacterial diversity than the 130 sequences from the full-length 16S rRNA gene clone library. The 92 operational taxonomic unit (OTUs) detected using pyrosequencing belonged to 45 families, whereas the 37 OTUs found in the clone library belonged to 25 families. Most sequences obtained from the clone library had equivalents in the pyrosequencing reads. However, 64 OTUs detected by pyrosequencing were not represented in the clone library. Our results demonstrate that pyrosequencing of the V3 region of the 16S rRNA gene is not only a powerful tool for discovering low-abundance bacterial populations but is also reliable for dissecting the bacterial community structure in a wastewater environment. 原文链接:http://www.springerlink.com/content/c763h26l28541v38/ PDF 原文下载: Zhang2011-AMB.pdf
耕种行为并非人类的专利,研究人员发现一种真核微生物也会播种并收获自己的食物——细菌。 新一期 Nature 报告说,美国赖斯大学的研究人员发现一些盘基网柄菌具有这种农业行为。盘基网柄菌是黏菌的一种,虽然名字中带个“菌”字,却并不是通常说的细菌,而是属于真核生物。它通常以单细胞形态存在,以细菌为食,但当某处的食物变得匮乏时,大量盘基网柄菌就会聚集到一起,形成黏液状的多细胞有机体,集体迁徙到别的地方。 过去人们一直认为盘基网柄菌只会这样四处“游猎”,但本次研究发现,有的盘基网柄菌在找到可作为食物的细菌后,并不将其完全吃掉,而是留下一部分作为“种子”,在集体迁徙时也带上这些“种子”,到达新地方后再进行“播种”,以收获更多细菌。研究人员在报告 中风 趣地称这些盘基网柄菌为“农民”。 领导研究的德布拉·布罗克说,盘基网柄菌有很多种,研究只发现其中一部分具有这种行为。具有这种能力的盘基网柄菌在食物稀缺环境下要比其他同类更具竞争力。( 生物谷 Bioon.com) 生物谷推荐原文出处: Nature doi:10.1038/nature09668 Primitive agriculture in a social amoeba Debra A. Brock,Tracy E. Douglas,David C. Queller Joan E. Strassmann Agriculture has been a large part of the ecological success of humans1. A handful of animals, notably the fungus-growing ants, termites and ambrosia beetles2, 3, 4, have advanced agriculture that involves dispersal and seeding of food propagules, cultivation of the crop and sustainable harvesting5. More primitive examples, which could be called husbandry because they involve fewer adaptations, include marine snails farming intertidal fungi6 and damselfish farming algae7. Recent work has shown that microorganisms are surprisingly like animals in having sophisticated behaviours such as cooperation, communication8, 9 and recognition10, 11, as well as many kinds of symbiosis12, 13, 14, 15. Here we show that the social amoeba Dictyostelium discoideum has a primitive farming symbiosis that includes dispersal and prudent harvesting of the crop. About one-third of wild-collected clones engage in husbandry of bacteria. Instead of consuming all bacteria in their patch, they stop feeding early and incorporate bacteria into their fruiting bodies. They then carry bacteria during spore dispersal and can seed a new food crop, which is a major advantage if edible bacteria are lacking at the new site. However, if they arrive at sites already containing appropriate bacteria, the costs of early feeding cessation are not compensated for, which may account for the dichotomous nature of this farming symbiosis. The striking convergent evolution between bacterial husbandry in social amoebas and fungus farming in social insects makes sense because multigenerational benefits of farming go to already established kin groups 盘基网柄菌生活在含丰富有机物的土壤中。当潮湿时,子实体接种的孢子释放单倍体细胞,这些细胞呈现阿米巴的外形和生活方式。它们生活在水膜中,吃细菌,通过二分分裂方式繁殖(营养期,vegetative phase)。只有当食物供给已经耗尽或食物暴露,有干掉的危险时,成百上千的黏菌就向周围发送信号——环腺苷酸小分子cAMP。收到信号的黏菌,也向其周围发送同样的信号。在一片互相收发的信号背景中,自发形成一个聚集中心。大量黏菌聚集后,形成一个多细胞组成的蛞蝓。口语中也称它为“蛞蝓”,科学术语称它为粘聚菌(grex)或假疟原虫(pseudoplasmodium)。蛞蝓被包在一种粘质的、非细胞片物质中,能象一个真正的蛞蝓那样移动。它迁移到一个明亮的地方变成子实体(fruitingbody),子实体由一个基板和一个支持球形新孢子聚集于顶端的茎组成。基板和茎由体细胞构成。体细胞形成由纤维素组成的壁,最后死亡。相反,其中的孢子细胞存活,它们是生殖细胞,其形成和释放都是为了执行无性繁殖的功能。 从大量黏菌以自己为中心向四面发送cAMP信号,最初形成均匀的随机背景,后来突然自发产生一个聚集中心。这是一种以自发对称破缺为特征的非平衡相变,是自组织行为的典型事例。人们对此进行过许多实验和理论研究。 在无性繁殖的生命周期中,网柄菌从单细胞状态到多细胞状态发生了一个非同寻常的转换:大量单个阿米巴集合成一个社会群体,使能适应不利的环境条件。因此,网柄菌是一种由原来独立的单细胞阿米巴形成的“部分时间是多细胞的生物体”。 网柄菌在非正常条件下也会产生奇妙的有性生殖:通过吞噬相邻的阿米巴,两个细胞融合并扩大成一个巨型细胞,这个巨型细胞被包裹在囊内,尔后经过减数分裂和有丝分裂产生新的单倍体阿米巴虫。 图示盘基网柄菌的生命周期。 近年来, 盘基网柄菌 作为异源重组糖蛋白表达载体的研究受到了学术界的重视,已经有多种具有生物活性的复杂糖蛋白成功地得到了表达。通过对表达产物的研究发现, 盘基网柄菌 具有各种翻译后加工机制,例如磷酸化、酰基化及形成GPI(糖基磷脂酰基醇)锚点等,具有类似于高等动物的糖基化修饰能力。与哺乳动物细胞表达载体相比较, 盘基网柄菌 具有培养成本低廉、细胞生长迅速及易于大规模培养的优势。 盘基网柄菌 有可能发展成为一种有重要应用前景的糖蛋白表达载体系统
科学松鼠会 发表于 2011-05-06 05:20 作者:裴唯珂 (编者注:本文为 征文009【游戏组】对决【动漫组】 的获奖来稿。) 引子 “从水生到陆生,从低等到高等,从简单到复杂”,这看起来不太有气势的排比句总能为植物们各种精巧聪明的生存策略一一注释。而站在注释背后的往往是“物竞天择,适者生存”这一早已家喻户晓的金科玉律。 的确,陆生植物存在地表的七亿年中,虽然从没遇到过大波僵尸的亲密接触,但他们的生存难题可绝对不少:寒冷,干旱,害虫,还有最头疼的微生物。可是在细菌,真菌以及病毒们一波波的袭击下,植物不仅没有灭绝,反而衍生出了庞大的植物王国,并深刻地改变了地球的面貌。 植物们能傲立地球亿万年靠是一身完美强健的免疫系统。但他们的免疫系统与我们的不同,由于植物的细胞不能运动,就没有我们身体里一套专门负责料理病原菌的白细胞,因此植物们只能采取全民皆兵的策略,全体细胞筑起一层层的防卫体系,与病原菌们演绎着一场场波澜壮阔的微观战争。 对于兵法家们来说,最经济、有效的防卫方式莫过于御敌于国门之外,同样“退避三舍”也是植物避病的首选策略。比如早熟的小麦品种由于发育较早刚好错开了病菌流行时间,对生育后期才流行的病害往往有很好的避病作用。可大多数情况下,微生物们与植物们总是进行亲密接触的,因此战争永远无法避免,建立多层次完善的防御体系是植物们生存的唯一出路。 『第一条防线』植物军团: “以防为主,防灭结合” 就像《植物大战僵尸》中,让僵尸们头疼不已的坚果和地刺一样,以高大坚固的城墙为依托的第一层屏障是每个准备攻坚战的病原菌都要面对的大难题。 在植物体表面,往往有一层含有酸类和脂肪物质的角质层或蜡质层,它们与细胞壁中的纤维素、木质素一起形成一道坚固屏障。有些植物茎的表皮和果实的果皮细胞壁中还含有鞣酸、硅酸盐和碳酸钙等无机化合物,这种加强版的细胞壁进一步巩固城防,让附着在细胞表面的病原菌们无可乘之机。 此外,细胞表面的一类蛋白质(transmembrane pattern recognition receptors,PRRs)可以识别维持细菌运动的鞭毛蛋白。在识别有病原菌附着在细胞附近后,PRRs会引发一系列细胞内的信号转导反应,启动细胞核内众多与防御相关的基因表达而引发抗病反应(1)。比如合成葡糖水解酶PEN2(2)并运输到植物细胞表面病原菌所在的位置,降解病原菌的细胞壁从而杀灭病菌。合成的PEN1蛋白也运输到这此,加速植物细胞壁的沉积,进一步加厚“城墙”以防病原菌的卷土重来(3-5)。受攻击的植物细胞还能“发狼烟”将敌情转达给周围的植物细胞。比如甜菜受褐斑病菌侵染后,侵染点四周的组织能迅速形成木栓层封锁病菌,从而使病斑较小甚至不能产生孢子。 病菌军团: “明修栈道,暗渡陈仓” 虽然植物们的第一层防卫体系看上去固若金汤,可以抵御大部分微生物的入侵,但在一些强力的病原菌眼里可谓是破绽百出。 一些彪悍的病原菌可以压制住植物守军的活动。侵染拟南芥和大麦的真菌就可以通过抑制PEN1介导的病菌侵染部位细胞壁沉积的方式,阻止植物在病毒突击位点的城墙加固工作,以利于病菌军团的攻坚活动。 更可怕的是,在真刀真枪的攻坚表面背后,病原菌还有一些影子部队可以出其不意地克敌制胜。比如一类称为假单胞菌(Pseudomonas syringae)的病原菌就称得上是玩弄敌人的高手。他们在侵染土豆的过程中可以合成一种茉莉酸的类似物并分泌出来。茉莉酸是植物广泛存在的一种激素,这种激素与抗病反应密切相关。土豆在被假单胞菌侵染后,误将假单胞菌产生的茉莉酸类似物当成是自己体内产生的茉莉酸,有如被催眠了一般抑制水杨酸介导的防御反应(6,7),并打开表皮细胞的气孔(8)。在诱骗守卫细胞撤掉守卫,大开城门后,假单胞菌们就顺着打开的气孔,长驱直入到细胞中大肆破坏。 『第二条防线』 除了上述的那些强悍的微生物可以撕破第一条防线外,昆虫的撕咬,大风狂吹导致的机械损伤,甚至是我们不经意间的踩踏都可以轻易的破坏植物们引以为豪的城防。在城门告破后,扬刀跃马的病菌大军将面对的是一支植物细胞全副武装的虎狼之师。真正的战斗才刚刚打响。 植物军团: “关门放狗,瓮中捉鳖” 摆在植物面前的关键问题是如何尽快地关闭城门,并将闯入的病原菌们一举歼灭。植物细胞内一类富含亮氨酸重复单位的受体激酶(以下简称NB-LRR),可以识别入侵病菌的毒性蛋白(以下简称Avr),并能在受侵染部位引发旺盛的呼吸作用。 旺盛的呼吸作用,可以促进植物伤口部位形成木栓层,加快伤口的愈合,并将健康组织和受害部位隔离开来。这样一种加速城墙恢复的战术,在阻止更多病原菌侵入的同时切断了城内敌军与城外敌军的联系,形成一个“关门打狗,瓮中捉鳖”的局势。 如同磁铁蘑菇可以将僵尸们的武器吸走以降低僵尸能力一样,受侵染部位的氧化酶也扮演着相似的角色。这些氧化酶异常活跃,使受侵染组织的呼吸作用加强,从而可以氧化分解病菌产生的毒素,减小病毒对细胞的损伤,起到“缴械”和“消毒”的作用(9)。 植物的呼吸作用加快以后,还可以抑制病菌的水解酶的活性。水解酶活性降低将导致病原菌分解利用植物养分的能力下降,在保护了植物“私有财产”的同时加速病菌的死亡。此釜底抽薪之计在断了病菌们粮草之后又彻底瓦解了病原菌的战斗力。 除此之外,植物还可以分泌抗菌物质,直接杀伤病菌。例如大蒜能产生有强烈杀菌作用的大蒜素,它比青霉素的杀菌能力还强100倍。抗花叶病的一些花卉植物,叶片细胞能产生类似人体干扰素的物质,这种植物干扰素能有效地阻止花卉花叶病毒的繁殖。 病菌军团: “里应外合,直捣黄龙” 面对植物『关门——缴械——断粮——围歼』步步为营的打击策略,病原菌们自然不会坐以待毙。 假单胞菌可以抑制植物体内的ARF-GEF蛋白,从而抑制植物细胞内的膜泡运输,这些膜泡负责运输巩固植物细胞壁需要的多糖以及酶类等物质(10),在膜泡运输受阻后,城墙无法修补,守军无法增兵,植物细胞“关门放狗”的战术只能化为泡影。同时还为在植物细胞外的病原菌继续突击创造条件,以形成里应外合之势。 细菌在侵入植物细胞后,体内的AvrPto和AvrPtoB蛋白释放抑制植物体内的激酶,通过阻止植物细胞体内的信号转导来抑制呼吸作用的加强,减小植物细胞缴械和断粮部队的威力,以保证病原菌的毒素不被氧化分解,水解酶不被氧化抑制(11)。 所谓“远水解不了近渴”,无论是等待援军还是恢复补给都不能立刻解决病原菌所面临的被抗菌物质迅速围歼的难题。为了取得白刃战的胜利,细菌采取了僵尸们才用的手段,将一个个有战斗力的作战单位通通“吃掉”。病原菌AvrPtoB蛋白的C末端可以折叠形成一个激活的E3连接酶,这种E3连接酶可以使植物蛋白(如合成抗菌物质的蛋白)标记上泛素并被降解,可以清除大量植物体内的反抗力量,以保证病原菌的存活(12)。 『第三条防线』 到底是植物的“关门打狗”道高一尺,还是病菌们的“里应外合”魔高一丈。除了双方的实力对比外,这场战斗的胜败还决定于战争所处的环境条件。天时地利在有些时候可以完全改变植物军团的作战能力。 根外部皮层的形成、伤口愈合以及组织木栓化等抗病反应都要求较高的温度,因此大多数土传的苗期病害在低温下发病较重。光照不足会削弱水稻对稻瘟病的抗病性,因为在这些条件下,稻株体内游离氮素的比例增高,有利于稻瘟病菌的发育。而氮肥不足则会削弱水稻对胡麻斑病和玉米对大斑病的抗病性。大气污染有时也会对寄主的抗病性产生影响,如只有在二氧化硫污染地区,松树针枯病才会严重发生。生物因素中,土壤中的某些线虫能破坏植物对根病和维管束病害(如棉花枯萎病、烟草黑胫病等)的抗性。此外,日常管理措施如修剪等农事操作也都会使某些植物的某种抗病性不同程度地增强或削弱(9)。 植物军团: “宁为玉碎,不为瓦全” 当外界条件不利于植物军团,第二条防线几近崩溃时,植物细胞不得已启用一直封印的最强兵器——自毁装置。当然植物的自毁没有毁灭菇那么暴力,而是一种外表温和,称为程序性死亡的过程。在危急时刻由植物细胞自己发动,释放水解酶水解植物细胞自身,形成死亡组织,将病原菌封闭在其中,以阻止病菌向健康的组织侵染。 在这过程中,将死的植物细胞会产生类似“遗言”的信号给整个植物的细胞,通告全体成员大敌当前,尽快加固细胞壁,提前表达抗病相关蛋白备战。这种全株获得性抗性的现象如今发展成为“植物疫苗”的理论基石,比如板栗的种植者们用弱株系的病原菌接种于树干,可使该树能抵抗该病菌的侵染。 病菌军团: “扶植傀儡,以战养战” 值得一提的是,确有一些更老谋深算的病原菌在入侵的同时阻止细胞进入程序性死亡,让细胞如中了生死符般求生不得,求死不能,只能沦为阶下囚乖乖地为病原菌提供营养。更高明的是病菌们控制住植物细胞后,阻断该细胞将战况泄露给其他植物细胞,凭借“以战养战”的策略在细胞内修养生息,迅速繁殖扩军,为下一次突袭附近毫无准备的细胞埋下伏笔。 天下大势——分久必“和” 能一口气突破三层防御的病原菌还是少之又少的。植物之所以可以抵御大部分病菌的侵害,除了靠他们现有的防御系统外,更依赖植物不断更新升级自己的防御程序。 为了更强有力地侵染植物,病原菌在不停地进化自己的包被蛋白等结构,躲避植物细胞表面受体的识别,同样病原菌的Avr效应蛋白也在不断进化躲避植物细胞内NB-LRR的识别。依靠自然选择压力,病菌还可以进化出对植物防御体系更强力的武器(13)。同样为了生存,植物细胞表面和内部受体也在不断进化以便及时准确地识别出病原菌发动免疫反应。无论是病原菌准备攻击武器还是植物细胞构建防卫系统,这种植物和微生物间的斗争就像国与国之间的战争一样劳民伤财,损人损己。 在这永不休止的军备竞赛中,一些植物和病原菌可以跳出成为宿敌的命运。比如根瘤菌就以为植物根系提供氮源养分为条件,让豆科植物敞开大门供其寄生并提供根瘤菌需要的碳源营养。在这种互惠互利的情况下,根瘤菌与豆科植物互利共生,协调进化,谱写了一代佳话。 但凡是文章,总要有个结尾。不过植物与微生物间这荡气回肠的斗争就算我不作总结,依然不减其无穷的回味。故在结尾不写结语插播广告,若列位看官喜欢看这眼皮子底下的战争故事,请您静待小弟的下件作品——《植物大战昆虫》。 参考资料: 1.Zipfel, C. et al. 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美国科罗拉多大学的微生物科学家与美国地质调查部门的科学家合作研究发现,微量的杀菌剂磺胺甲恶唑( sulfamethoxazole )会使地下水中硝酸根还原能力下降,最终导致地下水富化。美国《 CEN 》以及《 Environ. Sci. Technol. 》 的相关报道如下 Antibiotic Pollution May Increase Groundwater Nitrate Water Pollution: Compound slows growth of nitrate-reducing bacteri a Charlie Schmidt Decades after spawning a health care revolution, antibiotics are now common pollutants. Scientists' biggest concern about these emerging contaminants is that they promote the spread of resistance. But new research suggests they also harm the microbes that cleanse groundwater of dangerous compounds, particularly nitrates ( Environ. Sci. Technol. , DOI: 10.1021/es103605e ). High nitrate levels in drinking water can cause methemoglobinemia, a disease that decreases the blood's oxygen carrying capacity. Naturally-occurring bacteria in groundwater, such as Pseudomonas putida , can remove nitrates by reducing them to nitrogen gas. In Cape Cod, Mass., very high nitrate levels co-occur in groundwater with one of the most common antibiotics in the clinical arsenal: sulfamethoxazole (SMX). For nearly a decade, microbiologist Ronald Harvey and colleagues from the U.S. Geological Survey have tracked SMX and other groundwater pollutants at an aquifer that originates at the Otis Air National Guard Base, a heavily polluted site on Cape Cod. Other researchers had shown that high doses of SMX can interfere with bacterial nitrate reduction. But no one knew if a similar response might occur at environmentally-relevant concentrations. To answer that question, Harvey's team first cultured bacteria from a non-contaminated portion of the aquifer. Next, they added nitrate to the cultures at levels measured in the environment, along with SMX at doses ranging from 0.005 to 2,000 M. Bacterial growth rates dropped at all doses. At the environmentally relevant concentration of 0.005 M SMX, the amount of total nitrate that the bacteria removed from the culture fell by nearly half. "We're demonstrating a clear biological effect," Harvey says. "And we're showing that in the same bacteria that live in this particular aquifer." Harvey says that the next step would be to study the bacteria's response to SMX exposure in the aquifer itself. USGS research hydrologist Dana Kolpin , who didn't participate in this study, thinks the results suggest that SMX contamination might account at least in part for high nitrate levels in the aquifer. "We can't jump to that conclusion yet," he says. "But the data suggest that's a hypothesis worth pursuing." 下面是原文摘要: Effects of the Antimicrobial Sulfamethoxazole on Groundwater Bacterial Enrichment The effects of “trace” (environmentally relevant) concentrations of the antimicrobial agent sulfamethoxazole (SMX) on the growth, nitrate reduction activity, and bacterial composition of an enrichment culture prepared with groundwater from a pristine zone of a sandy drinking-water aquifer on Cape Cod, MA, were assessed by laboratory incubations. When the enrichments were grown under heterotrophic denitrifying conditions and exposed to SMX, noticeable differences from the control (no SMX) were observed. Exposure to SMX in concentrations as low as 0.005 μM delayed the initiation of cell growth by up to 1 day and decreased nitrate reduction potential (total amount of nitrate reduced after 19 days) by 47% ( p = 0.02). Exposure to 1 μM SMX, a concentration below those prescribed for clinical applications but higher than concentrations typically detected in aqueous environments, resulted in additional inhibitions: reduced growth rates ( p = 5 × 10−6), lower nitrate reduction rate potentials ( p = 0.01), and decreased overall representation of 16S rRNA gene sequences belonging to the genus Pseudomonas . The reduced abundance of Pseudomonas sequences in the libraries was replaced by sequences representing the genus Variovorax . Results of these growth and nitrate reduction experiments collectively suggest that subtherapeutic concentrations of SMX altered the composition of the enriched nitrate-reducing microcosms and inhibited nitrate reduction capabilities.
很有意思,为一个病原写一首歌,这个微生物曾经震动美国朝野。 Title:Cryptosporidium Septicemia, Yersinia Pestis Delusional Hyponatremia H2O poisoning without knowing Tap water infects my throat Nausea, retching, pallor bowel movements Epigastric discomfort Consume water from the sink Trying to rehydrate myself Virulent liquid maggots produce Rapid progressive condition Instant depletion of body fluids Electrolyte balance precarious Secretion of intestinal polypeptide Dilation of blood vessels Asiatic cholera secreting fluid and salt In the intestinal tract, viremia, vipoma, Water born epidemic Confusion in thought Intestinal rot, Bacterial Fate Trying to rehydrate Leading to hypovolemia... chronic renal dysfunction Massive loss of potassium, ion (K) from diarrhea and vomiting, Reaching for the stash tray Load a bowl... fire it up Trying to control nausea Internal anal hemorrhaging, bleeding sphincter and constantly wiping, Lying in pain slowly dying Wandering in disbelief Yearning at the terror inside me Cramping in unbearable I want to cry Somehow this has to end Same bacteria eats my friends Drink Pepto-Bismal to remiss Smoke a joint to progress Pale and pink... acid vomit sprays Dizziness erupts... I slip away Immune system starts to fade A fight with time Antibiotics will save my life Cryptosporidium killing inside Burning and churning, intestines writhe I am still breathing, but barely alive Parasites dying, I come back to life Cheating death, smoke another bowl Regaining hope, bless my soul The body is gaining strength No more bloody stool, I hit the bong Eating to constipate Hoping I won't defecate Water epidemic deploys town A defective filter is what was found At the water treatment plant, Intake/Outtake valves Were somehow crossed, sending untreated sewage Into the home, community infected... Cryptosporidium infecting my body, Living to tell the this purulent story Smoking some kind and feeling alive
逆向生态学求解微生物的环境适应机制 熊荣川 编译 找到基因型和表型之间的关系,从而阐明野生种群对于环境的适应性是进化生物学研究的基础。然而,这却不是一个轻松就能达到的目标,尤其是对于地球上占绝大多数的微生物物种来说。虽然,微生物在野外可以被可靠的采集到,但是要描述它们的环境适应性表型却异常的困难。本文则回避了这些困难,采用了“逆向生态学”种群基因组的研究方法,不考虑任何先验的环境适应基因假设,使用第三代测序技术,对 48 个真核微生物 Neurospora crassa 样本进行全基因组测序,并搜索单核苷酸多态性位点。通过对数据的比对和系统发育分析,我们发现两个最近分化的两个种群,一个栖息在加勒比热带海湾地区,一个栖息在 路易斯安那 亚热带 地区 。通过对两个种群染色体基因组严格分化区域的高通量扫描发现两个“基因组岛”,其上包含有温度和日照适应性基因。之后进行的温度控制生长率实验表明,路易斯安那 亚热带 地区种群有更好的低温( 10 ℃ )适应性。这一结果表明,基因组岛可能是两个种群对于平均最低温度相差 9 ℃的不同环境的适应分化的结果。引人注目的是,基因组岛上还有一个与生物节律调节相关的基因 frequency ,这暗示,两个地区相差 2.4°–10.6° 的纬度可能是另外一个导致两个种群分化的重要环境因子。 关键词:生态基因组学 基因组扫描 真菌生物钟 原文: Population genomics and local adaptation in wild isolates of a model microbial eukaryote Abstract Elucidating the connection between genotype, phenotype, and adaptation in wild populations is fundamental to the study of evolutionary biology, yet it remains an elusive goal, particularly for microscopic taxa, which comprise the majority of life. Even for microbes that can be reliably found in the wild, defining the boundaries of their populations and discovering ecologically relevant phenotypes has proved extremely difficult. Here, we have circumvented these issues in the microbial eukaryote Neurospora crassa by using a “reverse-ecology” population genomic approach that is free of a priori assumptions about candidate adaptive alleles. We performed Illumina whole-transcriptome sequencing of 48 individuals to identify single nucleotide polymorphisms. From these data, we discovered two cryptic and recently diverged populations, one in the tropical Caribbean basin and the other endemic to subtropical Louisiana. We conducted high-resolution scans for chromosomal regions of extreme divergence between these populations and found two such genomic “islands.” Through growth-rate assays, we found that the subtropical Louisiana population has a higher fitness at low temperature (10 °C) and that several of the genes within these distinct regions have functions related to the response to cold temperature. These results suggest the divergence islands may be the result of local adaptation to the 9 °C difference in average yearly minimum temperature between these two populations. Remarkably, another of the genes identified using this unbiased, whole-genome approach is the well-known circadian oscillator frequency , suggesting that the 2.4°–10.6° difference in latitude between the populations may be another important environmental parameter. ( Ellison et al., 2011 ) Keywords : ecological genomics ; genome scan ; fungi circadian clock 参考文献 Population genomics and local adaptation in wild isolates of a model microbial e.pdf Ellison Christopher E., Hall Charles, Kowbel David, Welch Juliet, Brem Rachel B., Glass N. L.,Taylor John W. (2011). "Population genomics and local adaptation in wild isolates of a model microbial eukaryote." Proceedings of the National Academy of Sciences 108 (7): 2831-2836.
与8-9月份相比,7月植物的对无机氮的竞争能力明显弱于土壤微生物群落;在表层土壤中,植物对无机氮的竞争能力强于微生物。 Spatio-temporal variations determine plant–microbe competition for inorganic nitrogen in an alpine meadow Journal of Ecology Xingliang Xu *, Hua Ouyang , Andreas Richter , Wolfgang Wanek , Guangmin Cao,Yakov Kuzyakov Summary 1. Plant–microbe competition for available nitrogen (N) has been suggested to be an important mechanism controlling N limitation of plants in a variety of ecosystems. However, spatio-temporal patterns of competition between plants and microbes for soil N remain unclear. 2. Short-term 15N tracer experiments were conducted during a growing season (July, August and September) in an alpine meadow on the Tibetan Plateau to unravel spatio-temporal patterns of plant–microbe competition for NH4+ and NO3−. 3. Alpine plants were poorer competitors than soil microorganisms for inorganic N in July compared with August and September. Occupation of soil volume by roots and root density (high in August and September) played a greater role in plant–microbe competition than air temperature or precipitation (high in July). 4. In topsoils (0–5cm, highest root density), alpine plants effectively competed with soil microorganisms for N and showed a preference for 15NO3−, while soil microorganisms that preferentially took up 15NH4+ out-competed plants below 5cm soil depth (lower root density). Competition between plants and soil microorganisms for inorganic N strongly depended on root density ( P 0.0001, R 2=0.93, exponential decay model). 5. Synthesis . Plant–microbe competition for inorganic N showed a clear spatio-temporal pattern in alpine meadows depending on (i) root density and therefore soil depth, (ii) inorganic N form, and (iii) different periods during the growing season. These findings have important implications for our understanding of above-ground–below-ground interactions and plant–microbial competition for available N. Source: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2745.2010.01789.x/abstract
Steven D. Allison, Matthew D. Wallenstein, Mark A. Bradford. Soil-carbon response to warming dependent on microbial physiology . Nature Geoscience , 2010; DOI: 10.1038/ngeo846 全球变暖的情况下,微生物的生理活动可能决定了土壤中向大气释放CO2的量。 多数生态系统模型都预测,随着全球温度的升高将会刺激微生物对土壤C的分解活动,从而形成一个正反馈。但是来自UC Irvine, Colorado State University and the Yale School of Forestry Environmental Studies 等单位的科学家发现随着全球温度的升高,土壤微生物在将土壤中的C转变为CO2的过程的效率将随时间的推移而降低。 以前的模型中都没有考虑到酶的活性的问题,而这些研究者的模型中考虑了酶活性在温度升高过程的变化情况。微生物产生的酶在土壤有机碳转变为CO2的过程中发挥着重要作用。
这算是创新吗?这与之前我还看到的与肠道益生菌相关的研究,根本是一回事啊。换汤不换药。 新华网伦敦11月30日电(记者 黄堃) 户外放养的猪总是比圈养和严密隔离饲养的猪看起来脏。但英国一项研究显示,这些户外放养的脏小猪实际上更健康。 英国阿伯丁大学等机构研究人员日前在《BMC生物学》( BMC Biology )期刊上报道了这一发现。他们将54只基因谱系近似的小猪平均分成3组,一组在户外放养,另一组在室内圈养,最后一组不仅在严格隔离的环境下饲养,还被定时喂食抗生素。 研究人员分别在实验初期、小猪断奶期和接近成熟期对它们进行了分析。结果发现,在户外放养的那一组小猪中,肠道里约90%的细菌都属于壁厚菌门,这类细菌的大部分都对健康有益,有助于控制大肠杆菌和沙门氏菌等致病菌;而室内圈养的小猪肠道内这种细菌只占70%,隔离饲养的小猪肠道内这种细菌仅为50%左右。 研究人员说,肠道菌群的差异甚至还引起与免疫系统相关的基因变化,在隔离饲养的小猪体内,与发炎免疫反应有关的基因表达更多;而在户外放养的小猪体内,与免疫细胞T细胞相关的基因表达更多。 研究人员认为,实验表明,看起来脏的环境反而更有利于小猪的健康和免疫系统发展。研究人员说,虽然在小猪身上得到的实验结果不能直接套用到人身上,但两者肠道内微生物的相似性,使得这一结果对人类也具有参考价值。 BMC Biology 2009, 7:79doi:10.1186/1741-7007-7-79 Environmentally-acquired bacteria influence microbial diversity and natural innate immune responses at gut surfaces Imke E Mulder* 1 , Bettina Schmidt* 1 , Christopher R Stokes2 , Marie Lewis2 , Mick Bailey2 , Rustam I Aminov1 , James I Prosser3 , Bhupinder P Gill4 , John R Pluske5 , Claus-Dieter Mayer6 , Corran C Musk1 and Denise Kelly1 1Gut Immunology Group, University of Aberdeen, Rowett Institute of Nutrition and Health, Greenburn Road, Aberdeen AB21 9SB, UK 2Veterinary Pathology, Infection Immunity, Langford House, Langford, Bristol, BS40 5DU, UK 3Institute of Biological and Environmental Sciences, University of Aberdeen, St Machar Drive, Aberdeen AB24 3UU, UK 4Agricultural and Horticultural Development Board, Winterhill House, Snowdon Drive, Milton Keynes MK6 1AX, UK 5School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, WA 6150, Australia 6Biomathematics Statistics Scotland, University of Aberdeen, Rowett Institute of Nutrition and Health, Greenburn Road, Aberdeen AB21 9SB, UK Background Early microbial colonization of the gut reduces the incidence of infectious, inflammatory and autoimmune diseases. Recent population studies reveal that childhood hygiene is a significant risk factor for development of inflammatory bowel disease, thereby reinforcing the hygiene hypothesis and the potential importance of microbial colonization during early life. The extent to which early-life environment impacts on microbial diversity of the adult gut and subsequent immune processes has not been comprehensively investigated thus far. We addressed this important question using the pig as a model to evaluate the impact of early-life environment on microbe/host gut interactions during development. Results Genetically-related piglets were housed in either indoor or outdoor environments or in experimental isolators. Analysis of over 3,000 16S rRNA sequences revealed major differences in mucosa-adherent microbial diversity in the ileum of adult pigs attributable to differences in early-life environment. Pigs housed in a natural outdoor environment showed a dominance of Firmicutes, in particular Lactobacillus, whereas animals housed in a hygienic indoor environment had reduced Lactobacillus and higher numbers of potentially pathogenic phylotypes. Our analysis revealed a strong negative correlation between the abundance of Firmicutes and pathogenic bacterial populations in the gut. These differences were exaggerated in animals housed in experimental isolators. Affymetrix microarray technology and Real-time Polymerase Chain Reaction revealed significant gut-specific gene responses also related to early-life environment. Significantly, indoor-housed pigs displayed increased expression of Type 1 interferon genes, Major Histocompatibility Complex class I and several chemokines. Gene Ontology and pathway analysis further confirmed these results. Conclusion Early-life environment significantly affects both microbial composition of the adult gut and mucosal innate immune function. We observed that a microbiota dominated by lactobacilli may function to maintain mucosal immune homeostasis and limit pathogen colonization.
引用出处: http://www.51xuewen.com/Blog/B_aShow.aspx?blog=wangleleID=9497 Marine Agar (DSMZ Medium 123) Composition per liter: Agar ..................................................................15.0g Tryptone............................................................10.0g Peptone ...............................................................5.0g Yeast extract ........................................................1.0g Synthetic seawater ............................................. 1.0L pH 7.8 0.2 at 25C Synthetic Seawater Composition per liter: NaCl ..................................................................24.0g MgCl26H2O .....................................................11.0g Na2SO4................................................................4.0g CaCl26H2O.........................................................2.0g KCl......................................................................0.7g KBr......................................................................0.1g SrCl26H2O .......................................................0.04g H3BO3 ...............................................................0.03g NaSiO39H2O...................................................5.0mg NaF...................................................................3.0mg NH4NO3 ...........................................................2.0mg Fe3PO44H2O ...................................................1.0mg Preparation of Synthetic Seawater: Add components to distilled water and bring volume to 1.0L. Mix thoroughly. Preparation of Medium: Add agar, tryptone, peptone, and yeast extract to synthetic seawater and bring volume to 1.0L. Mix thoroughly. Adjust pH to 7.8. Gently heat and bring to boiling. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure121C. Pour into sterile Petri dishes or leave in tubes. Use: For the cultivation and maintenance of Halobacillus halophilus, Halomonas spp., Vibrio harveyi,Cobetia marina, and Ruegeria atlantica. Marine Agar 2216(DSMZ Medium 604) Composition per liter: NaCl ................................................................19.45g Agar ..................................................................15.0g MgCl2..................................................................8.8g Peptone................................................................5.0g Na2SO3..............................................................3.24g CaCl2...................................................................1.8g Yeast extract ........................................................1.0g KCl....................................................................0.55g NaHCO3 ............................................................0.16g Ferric citrate........................................................0.1g KBr....................................................................0.08g SrCl2..................................................................0.03g H3BO3 ...............................................................0.02g Na2HPO4 ..........................................................8.0mg Na2SiO3............................................................4.0mg NaF...................................................................2.4mg NH4NO3 ...........................................................1.6mg pH 7.6 0.2 at 25C Source: This medium is available as a premixed powder from BD Diagnostic Systems. Preparation of Medium: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat while stirring and bring to boiling. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure121C. Pour into sterile Petri dishes or leave in tubes. Use: For the cultivation and maintenance of Hyphomonas spp., Oceanospirillum spp., Hyphomicrobium indicum, Psychroflexus gondwanensis=Flavobacterium gondwanense, Salegentibacter salegens=Flavobacterium salegens, Psychromonas antarctica, Sulfitobacter mediterraneus, Thalassomonas viridans,Vibrio spp., Marinospirillum minutulum=Oceanospirillum minutulum, Terasakiella pusilla=Oceanospirillum pusillum, Pseudoalteromonas atlantica=Alteromonas atlantica, Pseudomonas atlantica,Roseobacter spp., Erythrobacter longus, Pseudospirillum japonicum=Oceanospirillum japonicum,Marinobacter hydrocarbonoclasticus (Pseudomonas nautica), Psychrobacter spp., and Moritella japonica. For the isolation, cultivation, and maintenance of a wide variety of heterotrophic marine bacteria. Marine Agar with Biphenyl Composition per liter: NaCl ................................................................19.45g Agar ..................................................................15.0g MgCl2..................................................................8.8g Peptone ...............................................................5.0g Na2SO3..............................................................3.24g CaCl2...................................................................1.8g Yeast extract........................................................1.0g KCl....................................................................0.55g NaHCO3............................................................0.16g Ferric citrate........................................................0.1g KBr ...................................................................0.08g SrCl2..................................................................0.03g H3BO3 ...............................................................0.02g Na2HPO4..........................................................8.0mg Na2SiO3............................................................4.0mg NaF ..................................................................2.4mg NH4NO3 ...........................................................1.6mg Biphenyl...........................................................1.0mg pH 7.6 0.2 at 25C Preparation of Medium: Add components, except biphenyl, to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat and bring to boiling. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure121C. Pour into sterile Petri dishes or leave in tubes. After agar solidifies, aseptically add a few crystals of biphenyl to each plate. Use: For the cultivation and maintenance of biphenyl-utilizing marine bacteria, such as Cycloclasticus pugetii. Marine Agar with -Carrageenan Composition per 1070.0mL: Solution A.......................................................... 1.0L Solution B ..................................................... 60.0mL Solution C ..................................................... 10.0mL pH 7.2 0.2 at 25C Solution A: Composition per liter: NaCl ..................................................................25.0g Agar ..................................................................15.0g MgSO47H2O......................................................5.0g Casamino acids ...................................................2.5g Carrageenan.....................................................2.5g NaNO3.................................................................2.0g CaCl22H2O.........................................................0.2g KCl......................................................................0.1g Preparation of Solution A: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat and bring to boiling. Autoclave for 15 min at 15 psi pressure121C. Solution B: Composition per 100.0mL: Na2HPO42H2O.................................................3.56g Preparation of Solution B: Add component to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Autoclave for 15 min at 15 psi pressure121C. Solution C: Composition per 100.0mL: FeSO47H2O........................................................0.3g Preparation of Solution C: Add component to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Autoclave for 15 min at 15 psi pressure121C. Preparation of Medium: Aseptically add 60.0mL of sterile solution B and 10.0mL of sterile solution C to 1.0L of sterile solution A. Mix thoroughly. Pour into sterile Petri dishes or distribute into sterile tubes. Use: For the cultivation and maintenance of ATCC strain 43554. Marine Agar with - and -Carrageenan Composition per 1070.0mL: Solution A.......................................................... 1.0L Solution B..................................................... 60.0mL Solution C..................................................... 10.0mL pH 7.2 0.2 at 25C Solution A: Composition per liter: NaCl ..................................................................25.0g Agar ..................................................................15.0g MgSO47H2O......................................................5.0g Casamino acids ...................................................2.5g NaNO3 ................................................................2.0g -Carrageenan...................................................1.25g -Carrageenan...................................................1.25g CaCl22H2O ........................................................0.2g KCl......................................................................0.1g Preparation of Solution A: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat and bring to boiling. Autoclave for 15 min at 15 psi pressure121C. Solution B: Composition per 100.0mL: Na2HPO42H2O.................................................3.56g Preparation of Solution B: Add component to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Autoclave for 15 min at 15 psi pressure121C. Solution C: Composition per 100.0mL: FeSO47H2O........................................................0.3g Preparation of Solution C: Add component to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Autoclave for 15 min at 15 psi pressure121C. Preparation of Medium: Aseptically add 60.0mL of sterile solution B and 10.0mL of sterile solution C to 1.0L of sterile solution A. Mix thoroughly. Pour into sterile Petri dishes or distribute into sterile tubes. Use: For the cultivation and maintenance of Pseudomonas carrageenovora. Marine Agar with Naphthalene Composition per liter: NaCl ................................................................19.45g Agar ..................................................................15.0g MgCl2..................................................................8.8g Peptone ...............................................................5.0g Na2SO3..............................................................3.24g CaCl2...................................................................1.8g Yeast extract ........................................................1.0g KCl....................................................................0.55g NaHCO3 ............................................................0.16g Ferric citrate........................................................0.1g KBr....................................................................0.08g SrCl2..................................................................0.03g H3BO3 ...............................................................0.02g Na2HPO4 ..........................................................8.0mg Na2SiO3............................................................4.0mg NaF...................................................................2.4mg NH4NO3 ...........................................................1.6mg Naphthalene ........................................................1mg pH 7.6 0.2 at 25C Preparation of Medium: Add components, except naphthalene, to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat and bring to boiling. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure121C. Pour into sterile Petri dishes or leave in tubes. After agar solidifies, aseptically add a few crystals of naphthalene to each plate. Use: For the cultivation and maintenance of naphthalene-utilizing marine bacteria Marine Agar with Sulfur (ATCC Medium 1922) Composition per liter: NaCl ................................................................19.45g Sulfur ................................................................10.0g MgCl2..................................................................8.8g Peptone................................................................5.0g Na2SO3..............................................................3.24g CaCl2...................................................................1.8g Yeast extract ........................................................1.0g KCl....................................................................0.55g NaHCO3 ............................................................0.16g Ferric citrate........................................................0.1g KBr....................................................................0.08g SrCl2..................................................................0.03g H3BO3 ...............................................................0.02g Na2HPO4 ..........................................................8.0mg Na2SiO3............................................................4.0mg NaF...................................................................2.4mg NH4NO3 ...........................................................1.6mg pH 7.6 0.2 at 25C Preparation of Sulfur: Autoclave sulfur for 15 min at 0 psi pressure100C on three successive days. Preparation of Medium: Prepare anaerobically under a gas phase of 80% N2 + 10% CO2 + 10% H2. Add components, except sulfur, to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat while stirring and bring to boiling. Autoclave for 15 min at 15 psi pressure121C. Cool to 5055C. Aseptically add 10.0g of sterile sulfur. Mix thoroughly. Aseptically and anaerobically, under a gas phase of 80% N2 + 10% CO2 + 10% H2, distribute into sterile tubes. Use: For the cultivation and maintenance of Thermococcus litoralis. Marine Ameba Medium Composition per liter: Agar ..................................................................10.0g Malt extract .........................................................0.1g Yeast extract........................................................0.1g Artificial seawater.............................................. 1.0L Artificial Seawater: Composition per liter: NaCl ..................................................................27.5g MgSO4 7H2O...................................................6.78g MgCl26H2O .....................................................5.38g KCl....................................................................0.72g NaHCO3............................................................. 0.2g CaCL22H2O.......................................................1.4g Preparation of Artificial Seawater: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Preparation of Medium: Add components to artificial seawater and bring volume to 1.0L. Mix thoroughly. Gently heat and bring to boiling. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure121C. Pour into sterile Petri dishes or leave in tubes. Use: For the cultivation of Cochliopodium clarum, Heteramoeba clara, Ling***oeba leei, Paramoeba pemaquidensis, and Vannella species. Marine Broth 2216 (LMG Medium 164) Composition per liter: NaCl ................................................................19.45g MgCl2..................................................................8.8g Peptone ...............................................................5.0g Na2SO3..............................................................3.24g CaCl2...................................................................1.8g Yeast extract........................................................1.0g KCl....................................................................0.55g NaHCO3............................................................0.16g Ferric citrate........................................................0.1g KBr ...................................................................0.08g SrCl2..................................................................0.03g H3BO3 ...............................................................0.02g Na2HPO4..........................................................8.0mg Na2SiO3............................................................4.0mg NaF...................................................................2.4mg NH4NO3 ...........................................................1.6mg pH 7.6 0.2 at 25C Source: This medium is available as a premixed powder from BD Diagnostic Systems. Preparation of Medium: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat while stirring and bring to boiling. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure121C. Use: For the cultivation of Vibrio liquefaciens and for the isolation, cultivation, and maintenance of a wide variety of heterotrophic marine bacteria. Marine Broth with Biphenyl Composition per liter: NaCl ................................................................19.45g MgCl2..................................................................8.8g Peptone................................................................5.0g Na2SO3..............................................................3.24g CaCl2...................................................................1.8g Yeast extract ........................................................1.0g KCl....................................................................0.55g NaHCO3 ............................................................0.16g Ferric citrate........................................................0.1g KBr....................................................................0.08g SrCl2..................................................................0.03g H3BO3 ...............................................................0.02g Na2HPO4 ..........................................................8.0mg Na2SiO3............................................................4.0mg NaF...................................................................2.4mg NH4NO3 ...........................................................1.6mg Biphenyl ...........................................................1.0mg pH 7.6 0.2 at 25C Preparation of Medium: Add components, except biphenyl, to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure121C. Aseptically add a few crytals of biphenyl to each tube or flask. Use: For the cultivation of biphenyl-utilizing marine bacteria. Marine Broth with -Carrageenan Composition per 1070.0mL: Solution A.......................................................... 1.0L Solution B ..................................................... 60.0mL Solution C ..................................................... 10.0mL pH 7.2 0.2 at 25C Solution A: Composition per liter: NaCl ..................................................................25.0g MgSO47H2O......................................................5.0g Casamino acids ...................................................2.5g -Carrageenan .....................................................2.5g NaNO3 ................................................................2.0g CaCl22H2O ........................................................0.2g KCl......................................................................0.1g Preparation of Solution A: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat and bring to boiling. Autoclave for 15 min at 15 psi pressure121C. Solution B: Composition per 100.0mL: Na2HPO42H2O.................................................3.56g Preparation of Solution B: Add component to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Autoclave for 15 min at 15 psi pressure121C. Solution C: Composition per 100.0mL: FeSO47H2O........................................................0.3g Preparation of Solution C: Add component to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Autoclave for 15 min at 15 psi pressure121C. Preparation of Medium: Aseptically add 60.0mL of sterile solution B and 10.0mL of sterile solution C to 1.0L of sterile solution A. Mix thoroughly. Pour into sterile Petri dishes or distribute into sterile tubes. Use: For the cultivation of ATCC strain 43554. Marine Broth with - and -Carrageenan Composition per 1070.0mL: Solution A.......................................................... 1.0L Solution B..................................................... 60.0mL Solution C..................................................... 10.0mL pH 7.2 0.2 at 25C Solution A: Composition per liter: NaCl ..................................................................25.0g MgSO47H2O......................................................5.0g Casamino acids ...................................................2.5g NaNO3 ................................................................2.0g -Carrageenan...................................................1.25g -Carrageenan...................................................1.25g CaCl22H2O ........................................................0.2g KCl......................................................................0.1g Preparation of Solution A: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat and bring to boiling. Autoclave for 15 min at 15 psi pressure121C. Solution B: Composition per 100.0mL: Na2HPO42H2O.................................................3.56g Preparation of Solution B: Add component to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Autoclave for 15 min at 15 psi pressure121C. Solution C: Composition per 100.0mL: FeSO47H2O........................................................0.3g Preparation of Solution C: Add component to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Autoclave for 15 min at 15 psi pressure121C. Preparation of Medium: Aseptically add 60.0mL of sterile solution B and 10.0mL of sterile solution C to 1.0L of sterile solution A. Mix thoroughly. Distribute into sterile tubes or flasks. Use: For the cultivation and maintenance of Pseudomonas carrageenovora. Marine Broth with Naphthalene Composition per liter: NaCl ................................................................19.45g MgCl2..................................................................8.8g Peptone................................................................5.0g Na2SO3..............................................................3.24g CaCl2...................................................................1.8g Yeast extract ........................................................1.0g KCl....................................................................0.55g NaHCO3 ............................................................0.16g Ferric citrate........................................................0.1g KBr....................................................................0.08g SrCl2..................................................................0.03g H3BO3 ...............................................................0.02g Na2HPO4 ..........................................................8.0mg Na2SiO3............................................................4.0mg NaF...................................................................2.4mg NH4NO3 ...........................................................1.6mg Naphthalene ........................................................1mg pH 7.6 0.2 at 25C Preparation of Medium: Add components, except biphenyl, to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure121C. Aseptically add a few crytals of naphthalene to each tube or flask. Use: For the cultivation of naphthalene-utilizing marine bacteria. Marine Broth with Sulfur Composition per liter: NaCl ................................................................19.45g Sulfur ................................................................10.0g MgCl2..................................................................8.8g Peptone ...............................................................5.0g Na2SO3..............................................................3.24g CaCl2...................................................................1.8g Yeast extract........................................................1.0g KCl....................................................................0.55g NaHCO3............................................................0.16g Ferric citrate........................................................0.1g KBr ...................................................................0.08g SrCl2..................................................................0.03g H3BO3 ...............................................................0.02g Na2HPO4..........................................................8.0mg Na2SiO3............................................................4.0mg NaF ..................................................................2.4mg NH4NO3 ...........................................................1.6mg pH 7.6 0.2 at 25C Preparation of Sulfur: Autoclave for 15 min at 0 psi pressure100C on three successive days. Preparation of Medium: Prepare anaerobically under a gas phase of 80% N2 + 10% CO2 + 10% H2. Add components, except sulfur, to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat while stirring and bring to boiling. Autoclave for 15 min at 15 psi pressure121C. Cool to 50C. Aseptically add 10.0g of sulfur. Mix thoroughly. Aseptically and anaerobically, under a gas phase of 80% N2 + 10% CO2 + 10% H2, distribute into sterile tubes. Use: For the cultivation of Thermococcus litoralis. Marine Caulobacter Medium Composition per liter: Proteose peptone...............................................10.0g Yeast extract........................................................3.0g Artificial seawater.............................................. 1.0L pH 7.27.4 at 25C Artificial Seawater: Composition per liter: Commercially available marine aquarium salts mixture ...........................variable Preparation of Artificial Seawater: Add commercially available marine aquarium salts mixture to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Preparation of Medium: Combine components. Mix thoroughly. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure121C. Use: For the cultivation of Caulobacter halobacteroides and Caulobacter maris. Marine Chlorobiaceae Medium 2 Composition per 1051.0mL: Solution 1.................................................... 950.0mL Na2S9H2O solution...................................... 60.0mL NaHCO3 solution .......................................... 40.0mL Vitamin B12 solution ....................................... 1.0mL pH 6.8 0.2 at 25C Solution 1: Composition per 950.0mL: NaCl ..................................................................20.0g MgSO47H2O......................................................3.0g KH2PO4...............................................................1.0g NH4Cl .................................................................0.5g CaCl22H2O.......................................................0.05g Trace elements solution SL-8 ......................... 1.0mL Preparation of Solution 1: Add components to distilled/deionized water and bring volume to 950.0mL. Mix thoroughly. Autoclave for 15 min at 15 psi pressure121C. Cool to 4550C. Trace Elements Solution SL-8: Composition per liter: Disodium EDTA .................................................5.2g FeCl24H2O.........................................................1.5g CoCl26H2O ......................................................0.19g MnCl24H2O .......................................................0.1g ZnCl2.................................................................0.07g H3BO3 ...............................................................0.06g NaMoO42H2O..................................................0.04g CuCl22H2O ......................................................0.02g NiCl26H20........................................................0.02g Preparation of Trace Elements Solution SL8: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Na2S9H2O Solution: Composition per 100.0mL: Na2S9H2O..........................................................5.0g Preparation of Na2S9H2O Solution: Add Na2S9H2O to distilled/deionized water and bring volume to 100.0mL. Autoclave for 15 min at 15 psi pressure121C. Cool to 4550C. NaHCO3 Solution: Composition per 100.0mL: NaHCO3 ..............................................................5.0g Preparation of NaHCO3 Solution: Add NaHCO3 to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Filter sterilize. Vitamin B12 Solution: Composition per 100.0mL: Vitamin B12 ......................................................2.0mg Preparation of Vitamin B12 Solution: Add vitamin B12 to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Filter sterilize. Preparation of Medium: To 950.0mL of cooled, sterile solution 1, aseptically add 60.0mL of sterile Na2S9H2O solution, 40.0mL of sterile NaHCO3 solution, and 1.0mL of sterile vitamin B12 solution. Mix thoroughly. Adjust pH to 6.8 with sterile H2SO4 or Na2CO3 . Aseptically distribute into sterile 50.0mL or 100.0mL bottles with metal screw-caps and rubber seals. Completely fill bottles with medium except for a pea-sized air bubble. Use: For the isolation and cultivation of marine members of the Chlorobiaceae. Marine Chromatiaceae Medium 2 Composition per 1051.0mL: Solution 1.................................................... 950.0mL Na2S9H2O solution...................................... 60.0mL NaHCO3 solution.......................................... 40.0mL Vitamin B12 solution ....................................... 1.0mL pH 7.3 0.2 at 25C Solution 1: Composition per 950.0mL: NaCl ..................................................................20.0g MgSO47H2O......................................................3.0g KH2PO4...............................................................1.0g NH4Cl .................................................................0.5g CaCl22H2O ......................................................0.05g Trace elements solution SL-8 ......................... 1.0mL Preparation of Solution 1: Add components to distilled/deionized water and bring volume to 950.0mL. Mix thoroughly. Autoclave for 15 min at 15 psi pressure121C. Cool to 4550C. Trace Elements Solution SL-8: Composition per liter: Disodium EDTA.................................................5.2g FeCl24H2O.........................................................1.5g CoCl26H2O ......................................................0.19g MnCl24H2O .......................................................0.1g ZnCl2.................................................................0.07g H3BO3 ...............................................................0.06g NaMoO42H2O..................................................0.04g CuCl22H2O ......................................................0.02g NiCl26H20........................................................0.02g Preparation of Trace Elements Solution SL8: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Na2S9H2O Solution: Composition per 100.0mL: Na2S9H2O..........................................................5.0g Preparation of Na2S9H2O Solution: Add Na2S9H2O to distilled/deionized water and bring volume to 100.0mL. Autoclave for 15 min at 15 psi pressure121C. Cool to 4550C. NaHCO3 Solution: Composition per 100.0mL: NaHCO3 ..............................................................5.0g Preparation of NaHCO3 Solution: Add NaHCO3 to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Filter sterilize. Vitamin B12 Solution: Composition per 100.0mL: Vitamin B12 ......................................................2.0mg Preparation of Vitamin B12 Solution: Add vitamin B12 to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Filter sterilize. Preparation of Medium: To 950.0mL of cooled, sterile solution 1, aseptically add 60.0mL of sterile Na2S9H2O solution, 40.0mL of sterile NaHCO3 solution, and 1.0mL of sterile vitamin B12 solution. Mix thoroughly. Adjust pH to 7.3 with sterile H2SO4 or Na2CO3 . Aseptically distribute into sterile 50.0mL or 100.0mL bottles with metal screw-caps and rubber seals. Completely fill bottles with medium except for a pea-sized air bubble. Use: For the isolation and cultivation of marine members of the Chromatiaceae. Marine Cytophaga Agar Composition per liter: Agar ..................................................................15.0g Nutrient broth......................................................8.0g Yeast extract ........................................................5.0g Salt solution ....................................................... 1.0L Salt Solution: Composition per liter: NaCl ................................................................12.86g MgCl2................................................................2.48g KCl....................................................................0.75g CaCl2.................................................................0.56g Fe(SO4)2(NH4)2...............................................0.048g Preparation of Salt Solution: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Preparation of Medium: Add solid components to 1.0L of salt solution. Mix thoroughly. Gently heat while stirring and bring to boiling. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure 121C. Pour into sterile Petri dishes or leave in tubes. Use: For the cultivation and maintenance of Cytophaga species. Marine Cytophaga Medium Composition per liter: NaCl ..................................................................24.7g Agar ..................................................................15.0g MgSO47H2O......................................................6.3g MgCl26H2O .......................................................4.6g Tryptic digest of casein.......................................1.0g Yeast extract........................................................1.0g KCl......................................................................0.7g NaHCO3 solution .......................................... 10.0mL CaCl22H2O solution..................................... 10.0mL pH 7.2 0.2 at 25C NaHCO3 Solution: Composition per 10.0mL: NaHCO3..............................................................0.2g Preparation of NaHCO3 Solution: Add NaHCO3 to distilled/deionized water and bring volume to 10.0mL. Mix thoroughly. Autoclave for 15 min at 15 psi pressure121C. CaCl22H2O Solution: Composition per 10.0mL: CaCl22H2O ........................................................1.2g Preparation of CaCl22H2O Solution: Add CaCl22H2O to distilled/deionized water and bring volume to 10.0mL. Mix thoroughly. Autoclave for 15 min at 15 psi pressure121C. Preparation of Medium: Add components, except NaHCO3 solution and CaCl22H2O solution, to distilled/deionized water and bring volume to 980.0mL. Mix thoroughly. Gently heat and bring to boiling. Autoclave for 15 min at 15 psi pressure 121C. Cool to 5055C. Aseptically add 10.0mL of sterile NaHCO3 solution and 10.0mL of sterile CaCl22H2O solution. Mix thoroughly. Pour into sterile Petri dishes or distribute into sterile tubes. Use: For the cultivation of Cytophaga species, Flexibacter species, Microscilla species, and Saprospira grandis. Marine Cytophaga Medium A Composition per liter: Agar ..................................................................15.0g Pancreatic digest of casein..................................2.0g Beef extract .........................................................0.5g Yeast extract........................................................0.5g Sodium acetate....................................................0.2g Seawater...................................................... 700.0mL pH 7.2 0.2 at 25C Preparation of Medium: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat and bring to boiling. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure121C. Pour into sterile Petri dishes or leave in tubes. Use: For the cultivation of Flexibacter maritimus. Marine Cytophaga Medium B Composition per liter: Agar ..................................................................15.0g Pancreatic digest of casein..................................2.0g Beef extract .........................................................0.5g Yeast extract ........................................................0.5g Sodium acetate....................................................0.2g Seawater...................................................... 500.0mL pH 7.2 0.2 at 25C Preparation of Medium: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat and bring to boiling. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure121C. Pour into sterile Petri dishes or leave in tubes. Use: For the cultivation of Vibrio ordalii. Marine Cytophaga Medium C Composition per liter: Agar ..................................................................15.0g Pancreatic digest of casein..................................2.0g Beef extract .........................................................0.5g Yeast extract ........................................................0.5g Sodium acetate....................................................0.2g pH 7.2 0.2 at 25C Preparation of Medium: Add components to seawater and bring volume to 1.0L. Mix thoroughly. Gently heat and bring to boiling. Distribute into tubes or flasks. Autoclave for 15 min at 15 psi pressure 121C. Pour into sterile Petri dishes or leave in tubes. Use: For the cultivation of Cytophaga agarovorans, Cytophaga fermentans, and Cytophaga salmonicolor. Marine Desulfovibrio Medium Composition per liter: Solution A................................................... 980.0mL Solution B ..................................................... 10.0mL Solution C ..................................................... 10.0mL pH 7.8 0.2 at 25C Solution A: Composition per 980.0mL: NaCl ..................................................................25.0g DL-Sodium lactate...............................................2.0g MgSO47H2O......................................................2.0g Na2SO4................................................................1.0g NH4Cl .................................................................1.0g Yeast extract........................................................1.0g K2HPO4...............................................................0.5g CaCl22H2O ........................................................0.1g Resazurin .........................................................1.0mg Preparation of Solution A: Add components to distilled/deionized water and bring volume to 980.0mL. Mix thoroughly. Gently heat and bring to boiling. Continue boiling for 3-4 min. Allow to cool to room temperature while gassing under 100% N2. Solution B: Composition per 10.0mL: FeSO47H2O........................................................0.5g Preparation of Solution B: Add FeSO47H2O to distilled/deionized water and bring volume to 10.0mL. Mix thoroughly. Solution C: Composition per 10.0mL: Ascorbic acid ......................................................0.1g Sodium thioglycolate ..........................................0.1g Preparation of Solution C: Add components to distilled/deionized water and bring volume to 10.0mL. Mix thoroughly. Preparation of Medium: To 980.0mL of cooled solution A, anaerobically add 10.0mL of solution B and 10.0mL of solution C. Mix thoroughly. Adjust pH to 7.8 with NaOH. Distribute into tubes or flasks. During distribution, swirl the medium to keep the precipitate in suspension. Autoclave for 15 min at 15 psi pressure121C. Use: For the cultivation and maintenance of Desulfovibrio desulfuricans, Desulfovibrio salexigens, and Desulfovibrio vulgaris. Marine Flagellate Medium Composition per 15.0mL: Rice grains ..........................................................2.0g Seawater........................................................ 15.0mL Preparation of Medium: Autoclave rice grains for 15 min at 15 psi pressure121C. Add 2.0g of sterile rice grains to 15.0mL of filter-sterilized seawater. Aseptically distribute into T-25 tissue culture flasks. Use: For the cultivation of Acanthoecopsis unguiculata, Amastigomonas species, Bicosoeca vacillans, Bodo designis, Bodo variabilis, Caecitellus parvulus, Choanoeca perplexa, Codosiga gracilis, Diaphanoeca grandis, Entosiphon species, Goniomonas species, Procryptobia species, Pseudobodo tremulans, Rhynchomonas nasuta, Salpingoeca urceolata, Stephanoeca diplocostata, and Stephanopogon apogon. Marine Flagellate Medium with B-Vitamins Composition per liter: Seawater...................................................... 990.0mL Vitamin solution............................................ 10.0mL Vitamin Solution: Composition per 100.0mL: ThiamineHCl ...................................................0.15g Calcium D-(+)-pantothenate..............................0.05g Nicotinamide.....................................................0.05g PyridoxalHCl ...................................................0.05g Riboflavin .........................................................0.05g Folic acid.........................................................0.025g PyridoxamineHCl ..........................................0.025g Biotin .............................................................12.5mg Preparation of Vitamin Solution: Add components to distilled/deionized water and bring volume to 100.0mL. Mix thoroughly. Filter sterilize. Preparation of Medium: Allow natural seawater to age for 2 months. Filter sterilize. Aseptically add 100.0mL of sterile vitamin solution. Mix thoroughly. Aseptically distribute into sterile tubes or flasks. Use: For the cultivation of Oikomonas species. Marine Glucose Trypticase Yeast Extract Agar (MGTY Agar) Composition per liter: Agar ....................................................................8.0g Glucose ...............................................................2.0g Pancreatic digest of casein..................................1.0g Yeast extract ........................................................1.0g L-CysteineHClH2O............................................0.5g Seawater...................................................... 750.0mL Tris-HCl buffer (5.0 mM, pH 7.5) ................ 50.0mL Resazurin (0.1% solution)............................... 1.0mL pH 7.5 0.2 at 25C Preparation of Medium: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat while stirring and bring to boiling. Distribute into tubes or flasks under 97% N2 + 3% H2. Cap with rubber stoppers and place tubes in a press. Autoclave for 15 min at 15 psi pressure121C with fast exhaust. Use: For the cultivation and maintenance of Spirochaeta isovalerica. Marine Glucose Trypticase Yeast Extract Broth (MGTY Broth) Composition per liter: Glucose ...............................................................2.0g Pancreatic digest of casein..................................1.0g Yeast extract........................................................1.0g L-CysteineHClH2O............................................0.5g Seawater...................................................... 750.0mL Tris-HCl buffer (5.0 mM, pH 7.5) ................ 50.0mL Resazurin (0.1% solution) .............................. 1.0mL pH 7.5 0.2 at 25C Preparation of Medium: Add components to distilled/deionized water and bring volume to 1.0L. Mix thoroughly. Gently heat while stirring and bring to boiling. Distribute into tubes or flasks under 97% N2 + 3% H2. Cap with rubber stoppers and place tubes in a press. Autoclave for 15 min at 15 psi pressure121C with fast exhaust. Use: For the cultivation and maintenance of Spirochaeta isovalerica. Marine Methanogenium Alcohol Medium Composition per 1003.0mL: NaCl ..................................................................21.0g MgCl26H2O .......................................................3.0g NaCl ....................................................................1.0g KCl......................................................................0.5g MgCl26H2O .......................................................0.5g NH4Cl .................................................................0.4g Sodium acetate3H2O..........................................0.4g KH2PO4...............................................................0.2g CaCl22H2O ........................................................0.1g NaHCO3 solution.......................................... 60.0mL 2-Propanol....................................................... 5.0mL Na2S9H2O solution........................................ 3.0mL Cyanocobalamin solution ............................... 1.0mL Selenite-molybdate-tungstate solution............ 1.0mL Thiamine solution ........................................... 1.0mL Trace elements solution .................................. 1.0mL
小红猪小分队 发表于2008-01-7 星期一 10:27 分类: 医学 , 小红猪翻译小分队 , 生物 | | by Jerome Groopman August 11, 2008 Doctors fear that dangerous bacteria may become entrenched in hospitals. In August, 2000, Dr. Roger Wetherbee, an infectious-disease expert at New York Universitys Tisch Hospital, received a disturbing call from the hospitals microbiology laboratory. At the time, Wetherbee was in charge of handling outbreaks of dangerous microbes in the hospital, and the laboratory had isolated a bacterium called Klebsiella pneumoniae from a patient in an intensive-care unit. It was literally resistant to every meaningful antibiotic that we had, Wetherbee recalled recently. The microbe was sensitive only to a drug called colistin, which had been developed decades earlier and largely abandoned as a systemic treatment, because it can severely damage the kidneys. So we had this report, and I looked at it and said to myself, My God, this is an organism that basically we cant treat. Klebsiella is in a class of bacteria called gram-negative, based on its failure to pick up the dye in a Grams stain test. (Gram-positive organisms, which include Streptococcus and Staphylococcus , have a different cellular structure.) It inhabits both humans and animals and can survive in water and on inanimate objects. We can carry it on our skin and in our noses and throats, but it is most often found in our stool, and fecal contamination on the hands of caregivers is the most frequent source of infection among patients. Healthy people can harbor Klebsiella to no detrimental effect; those with debilitating conditions, like liver disease or severe diabetes, or those recovering from major surgery, are most likely to fall ill. The bacterium is oval in shape, resembling a TicTac, and has a thick, sugar-filled outer coat, which makes it difficult for white blood cells to engulf and destroy it. Fimbriafine, hairlike extensions that enable Klebsiella to adhere to the lining of the throat, trachea, and bronchiproject from the bacterias surface; the attached microbes can travel deep into our lungs, where they destroy the delicate alveoli, the air sacs that allow us to obtain oxygen. The resulting hemorrhage produces a blood-filled sputum, nicknamed currant jelly. Klebsiella can also attach to the urinary tract and infect the kidneys. When the bacteria enter the bloodstream, they release a fatty substance known as an endotoxin, which injures the lining of the blood vessels and can cause fatal shock. Tisch Hospital has four intensive-care units, all in the east wing on the fifteenth floor, and at the time of the outbreak there were thirty-two intensive-care beds. The I.C.U.s were built in 1961, and although the equipment had been modernized over the years, the units had otherwise remained relatively unchanged: the beds were close to each other, with I.V. pumps and respirators between them, and doctors and nursing staff were shared among the various I.C.U.s. This was an ideal environment for a highly infectious bacterium. It was the first major outbreak of this multidrug-resistant strain of Klebsiella in the United States, and Wetherbee was concerned that the bacterium had become so well adapted in the I.C.U. that it could not be killed with the usual ammonia and phenol disinfectants. Only bleach seemed able to destroy it. Wetherbee and his team instructed doctors, nurses, and custodial staff to perform meticulous hand washing, and had them wear gowns and gloves when attending to infected patients. He instituted strict protocols to insure that gloves were changed and hands vigorously disinfected after handling the tubing on each patients ventilator. Spray bottles with bleach solutions were installed in the I.C.U.s, and surfaces and equipment were cleaned several times a day. Nevertheless, in the ensuing months Klebsiella infected more than a dozen patients. In late autumn of 2000, in addition to pneumonia patients began contracting urinary-tract and bloodstream infections from Klebsiella . The latter are often lethal, since once Klebsiella infects the bloodstream it can spread to every organ in the body. Wetherbee reviewed procedures in the I.C.U. again and discovered that the Foley catheters, used to drain urine from the bladder, had become a common source of contamination; when emptying the urine bags, staff members inadvertently splashed infected urine onto their gloves and onto nearby machinery. They were very effectively moving the organism from one bed to the next, Wetherbee said. He ordered all the I.C.U.s to be decontaminated; the patients were temporarily moved out, supplies discarded, curtains changed, and each room was cleaned from floor to ceiling with a bleach solution. Even so, of the thirty-four patients with infections that year, nearly half died. The outbreak subsided in October, 2003, after even more stringent procedures for decontamination and hygiene were instituted: patients kept in isolation, and staff and visitors required to wear gloves, masks, and gowns at all times. My basic premise, Wetherbee said, is that you take a capable microrganism like Klebsiella and you put it through the gruelling test of being exposed to a broad spectrum of antibiotics and it will eventually defeat your efforts, as this one did. Although Tisch Hospital has not had another outbreak, the bacteria appeared soon after at several hospitals in Brooklyn and one in Queens. When I spoke to infectious-disease experts this spring, I was told that the resistant Klebsiella had also appeared at Mt. Sinai Medical Center, in Manhattan, and in hospitals in New Jersey, Pennsylvania, Cleveland, and St. Louis. Of the so-called superbugsthose bacteria that have developed immunity to a wide number of antibioticsthe methicillin-resistant Staphylococcus aureus , or MRSA , is the most well known. Dr. Robert Moellering, a professor at Harvard Medical School, a past president of the Infectious Diseases Society of America, and a leading expert on antibiotic resistance, pointed out that MRSA , like Klebsiella , originally occurred in I.C.U.s, especially among patients who had undergone major surgery. Until about ten years ago, Moellering told me, virtually all cases of MRSA were either in hospitals or nursing homes. In the hospital setting, they cause wound infections after surgery, pneumonias, and bloodstream infections from indwelling catheters. But they can cause a variety of other infections, all the way to bacterial meningitis. The first deaths from MRSA in community settings, reported at the end of the nineteen-nineties, were among children in North Dakota and Minnesota. And then it started showing up in men who have sex with men, Moellering said. Soon, it began to be spread in prisons among the prisoners. Now we see it in a whole bunch of other populations. An outbreak among the St. Louis Rams football team, passed on through shared equipment, particularly affected the teams linemen; artificial turf, which causes skin abrasions that are prone to infection, exacerbated the problem. Other outbreaks were reported among insular religious groups in rural New York; Hurricane Katrina evacuees; and illegal tattoo recipients. And now its basically everybody, Moellering said. The deadly toxin produced by the strain of MRSA found in U.S. communities, Panton-Valentine leukocidin, is thought to destroy the membranes of white blood cells, damaging the bodys primary defense against the microbe. In 2006, the Centers for Disease Control and Prevention recorded some nineteen thousand deaths and a hundred and five thousand infections from MRSA . Unlike resistant forms of Klebsiella and other gram-negative bacteria, however, MRSA can be treated. There are about a dozen new antibiotics coming on the market in the next couple of years, Moellering noted. But there are no good drugs coming along for these gram-negatives. Klebsiella and similarly classified bacteria, including Acinetobacter , Enterobacter , and Pseudomonas , have an extra cellular envelope that MRSA lacks, and that hampers the entry of large molecules like antibiotic drugs. The Klebsiella that caused particular trouble in New York are spreading out, Moellering told me. They have very high mortality rates. They are sort of the doomsday-scenario bugs. In 1968, Moellering travelled to Malaita, in the Solomon Islands. I was really interested to see whether we could find an antibiotic-resistant population of bacteria in a place that had never seen antibiotics, Moellering said. The natives practiced head-hunting and cannibalism, and were isolated as much by conflict as by the islands dense jungle. Moellering identified microbes there that were resistant to the antibiotics streptomycin and tetracycline, which were then in use in the West but had never been introduced clinically on Malaita. Later studies found resistant bacteria in many other isolated indigenous human populations, as well as in natural reservoirs like aquifers. Before the development of antibiotics, the threat of infection was urgent: until 1936, pneumonia was the No. 1 cause of death in the United States, and amputation was sometimes the only cure for infected wounds. The introduction of sulfa drugs, in the nineteen-thirties, and penicillin, in the nineteen-forties, suddenly made many bacterial infections curable. As a result, doctors prescribed the drugs widelyoften for sore throats, sinus congestion, and coughs that were due not to bacteria but to viruses. In response, bacteria quickly developed resistance to the most common antibiotics. The public assumed that the pharmaceutical industry and researchers in academic hospitals would continue to identify effective new treatments, and for many years they did. In the nineteen-eighties, a class of drugs called carbapenems was developed to combat gram-negative organisms like Klebsiella , Pseudomonas , and Acinetobacter . They were, at the time, thought to be drugs of last resort, because they had activity against a whole variety of multiply-resistant gram-negative bacteria that were already floating around, Moellering said. Many hospitals put the drugs on reserve, but an apparent cure-all was too tempting for some physicians, and the tight stewardship slowly broke down. Inevitably, mutant, resistant microbes flourished, and even the carbapenems effectiveness waned. Now microbes are appearing far outside their environmental niches. Acinetobacter thrives in warm, humid climates, like Honduras, as well as in parts of Iraq, and is normally found in soil. An article published in the military magazine Proceedings in February reported that more than two hundred and fifty patients at U.S. military hospitals were infected with a highly resistant strain of Acinetobacter between 2003 and 2005, with seven deaths as of June, 2006, linked to Acinetobacter -related complications. In 2004, about thirty per cent of all patients returning from Iraq and Afghanistan tested positive for the bacteria. Its a big problem, and its contaminated the evacuation facilities in Germany and a lot of the V.A. hospitals in the United States where these soldiers have been brought, Moellering said. Patients evacuated to Stockholm from Thailand after the 2004 tsunami were often infected with resistant gram-negative microbes, including a strain of Acinetobacter that was resistant even to colistin, the antibiotic used, to variable effect, in the outbreak at Tisch Hospital. The practice of clinical tourism, in which patients travel long distances for more advanced or more affordable medical centers, may introduce resistant microbes into hospitals where they had not existed before. Meanwhile, antibiotic use in agricultural industries has grown rapidly. Seventy per cent of the antibiotics administered in America end up in agriculture, Michael Pollan, a professor of journalism at Berkeley and the author of In Defense of Food: An Eaters Manifesto, told me. The drugs are not used to cure sick animals but to prevent them from getting sick, because we crowd them together under filthy circumstances. These are perfect environments for disease. And we also have found, for reasons that I dont think we entirely understand, that administering low levels of antibiotics to animals speeds their growth. The theory is that by killing intestinal bacteria the competition for energy is reduced, so that the animal absorbs more energy from the food and therefore grows faster. The Food and Drug Administration, which is often criticized for its lack of attention to the risks of widespread use of antibiotics, offers recommended, non-binding guidelines for these drugs but has rarely withdrawn approval for their application. A spokesman for the Center for Veterinary Medicine at the F.D.A. told me that the center believes that prudent drug-use principles are essential to the control of antimicrobial resistance. A study by David L. Smith, Jonathan Dushoff, and J. Glenn Morris, published by PLoS Medicine , from the Public Library of Science, in 2005, noted that the transmission of resistant bacteria from animal to human populations is difficult to measure, but that antibiotics and antibiotic-resistant bacteria ( ARB ) are found in the air and soil around farms, in surface and ground water, in wild-animal populations, and on retail meat and poultry. ARB are carried into the kitchen on contaminated meat and poultry, where other foods are cross-contaminated because of common unsafe handling practices. The researchers developed a mathematical model that suggested that the impact of the transmission of these bacteria from agriculture may be more significant than that of hospital transmissions. The problem is that we have created the perfect environment in which to breed superbugs that are antibiotic-resistant, Pollan told me. Weve created a petri dish in our factory farms for the evolution of dangerous pathogens. Ten years ago, the Institute of Medicine of the National Academy of Sciences, in Washington, D.C., assessed the economic impact of resistant microbes in the United States at up to five billion dollars, and experts now believe the figure to be much higher. In July, 2004, the Infectious Diseases Society of America released a white paper, Bad Bugs, No Drugs: As Antibiotic Discovery Stagnates . . . A Public Health Crisis Brews, citing 2002 C.D.C. data showing that, of that years estimated ninety thousand deaths annually in U.S. hospitals owing to bacterial infection, more than seventy per cent had been caused by organisms that were resistant to at least one of the drugs commonly used to treat them. Drawing on these data, collected mostly from hospitals in large urban areas which are affiliated with medical schools, the Centers for Disease Control and Prevention found more than a hundred thousand cases of gram-negative antibiotic-resistant bacteria. No precise numbers for all infections, including those outside hospitals, have been calculated, but the C.D.C. also reported that, among gram-negative hospital-acquired infections, about twenty per cent were resistant to state-of-the-art drugs. In April, I visited Dr. Stuart Levy, at Tufts University School of Medicine. Levy is a researcher-physician who has made key discoveries about how bacteria become resistant to antibiotics. In addition to the natural cell envelope of Klebsiella , Levy outlined three primary changes in bacteria that make them resistant to antibiotics. Each change involves either a mutation in the bacteriums own DNA or the importation of mutated DNA from another. (Bacteria can exchange DNA in the form of plasmids, molecules that are shared by the microbes and allow them to survive inhibitory antibiotics.) First, the bacteria may acquire an enzyme that can either act like a pair of scissors, cutting the drug into an inactive form, or modify the drugs chemical structure, so that it is rendered impotent. Thirty years ago, Levy discovered a second change: pumps inside the bacteria that could spit out the antibiotic once it had passed through the cell wall. His first reports were met with profound skepticism, but now, Levy told me, most people would say that efflux is the most common form of bacterial resistance to antibiotics. The third change involves mutations that alter the inner contents of the microbe, so that the antibiotic can no longer inactivate its target. Global studies have shown how quickly these bacteria can develop and spread. This has been a problem in Mediterranean Europe that started about ten years ago, Dr. Christian Giske told me. Giske is a clinical microbiologist at Karolinska University Hospital, in Stockholm, who, with researchers in Israel and Denmark, recently reported on the worldwide spread of resistant gram-negative bacteria. He continued, It started to get really serious during the last five or six years and has become really dramatic in Greece. A decade ago, only a few microbes in Southern Europe had multidrug resistance; now some fifty to sixty per cent of hospital-acquired infections are resistant. Giske and his colleagues found that infection with a resistant strain of Pseudomonas increased, twofold to fivefold, a patients risk of dying, and increased about twofold the patients hospital stay. Like other experts in the field, Giskes team was concerned about the lack of new antibiotics being developed to combat gram-negative bacteria. There are now a growing number of reports of cases of infections caused by gram-negative organisms for which no adequate therapeutic options exist, Giske and his colleagues wrote. This return to the preantibiotic era has become a reality in many parts of the world. 文章分段,下边算第二篇译文原文 Doctors and researchers fear that these bacteria may become entrenched in hospitals, threatening any patient who has significant health issues. Anytime you hear about some kid getting snatched, you want to find something in that story that will convince you that that family is different from yours, Dr. Louis Rice, an expert in antibiotic resistance at Louis Stokes Cleveland VA Medical Center, told me. But the problem is that any of us could be an I.C.U. patient tomorrow. Its not easy to convey this to people if its not immediately a threat. You dont want to think about it. But its actually anybody who goes into a hospital. This is scary stuff. Rice mentioned that he had a mild sinusitis and was hoping it would not need to be treated, because taking an antibiotic could change the balance of microbes in his body and make it easier for him to contract a pathogenic organism while doing his rounds at the hospital. Genetic elements in the bacteria that promote resistance may also move into other, more easily contracted bugs. Moellering pointed out that, while Klebsiella seems best adapted to hospital settings, and poses the greatest risk to patients, other gram-negative bacteriaspecifically E. coli , which is a frequent cause of urinary-tract infection in otherwise healthy peoplehave recently picked up the genes from Klebsiella which promote resistance to antibiotics. In the past, large pharmaceutical companies were the primary sources of antibiotic research. But many of these companies have abandoned the field. Eli Lilly and Company developed the first cephalosporins, Moellering told me, referring to familiar drugs like Keflex. They developed a huge number of important anti-microbial agents. They had incredible chemistry and incredible research facilities, and, unfortunately, they have completely pulled out of it now. After Squibb merged with Bristol-Myers, they closed their antibacterial program, he said, as did Abbott, which developed key agents in the past treatment of gram-negative bacteria. A recent assessment of progress in the field, from U.C.L.A., concluded, FDA approval of new antibacterial agents decreased by 56 per cent over the past 20 years (1998-2002 vs. 1983-1987), noting that, in the researchers projection of future development only six of the five hundred and six drugs currently being developed were new antibacterial agents. Drug companies are looking for blockbuster therapies that must be taken daily for decades, drugs like Lipitor, for high cholesterol, or Zyprexa, for psychiatric disorders, used by millions of people and generating many billions of dollars each year. Antibiotics are used to treat infections, and are therefore prescribed only for days or weeks. (The exception is the use of antibiotics in livestock, which is both a profit-driver and a potential cause of antibiotic resistance.) Antibiotics are the only class of drugs where all the experts, as soon as you introduce them clinically, we go out and tell everyone to try to hold it in reserve, Rice pointed out. If there is a new cardiology drug, every cardiologist out there is saying that everyone deserves to be on it. In February, Rice wrote an editorial in the Journal of Infectious Diseases criticizing the lack of support from the National Institutes of Health; without this support, he wrote, the big picture did not receive the attention it deserved. Rice acknowledges that there are competing agendas. As loud as my voice might be, there are louder voices screaming AIDS , he told me. And there are congressmen screaming bioterrorism. Rice came up with the acronym ESKAPE bacteria Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanni, Pseudomonas aeruginosa, and the Entero-bacter speciesas a way of communicating the threat these microbes pose, and the Infectious Diseases Society is lobbying Congress to pass the Strategies to Address Antimicrobial Resistance Act, which would earmark funding for research on ESKAPE microbes and also set up clinical trials on how to limit infection and antibiotic resistance. Rice has also proposed studies to determine the most effective useat what dosage, and for how longof antibiotics for common infections like bronchitis and sinusitis. Dr. Anthony Fauci is the director of the National Institute of Allergy and Infectious Diseases, which chairs the federal interagency working group on microbial resistance. Fauci told me that the government is acutely aware of the severity of the problem. He pointed out that the N.I.H. recently issued a call for proposals to study optimal use of antibiotics for common bacterial infections. It has also funded so-called coperative agreements, including one on Klebsiella , to facilitate public-private partnerships where the basic research from the institute or from university laboratories can be combined with development by a pharmaceutical or a biotech company. Even so, the total funding for studying the resistance of ESKAPE microbes is about thirty-five million dollars, a fraction of the two hundred million dollars provided by the NIAID for research on antimicrobial resistance, most of which goes to malaria, t.b., and H.I.V. The difficulty that we are faced with is that our budget has been flat for the last five years, Fauci told me. In real dollars, weve lost almost fifteen per cent purchasing power, because of an inflation index of about three per cent for biomedical research and development. Since September 11, 2001, significant funding has been directed toward the study of anthrax and other microbes, like the one that causes plague, which could be used as bioweapons. Although there is little concern that Klebsiella or Acinetobacter might be weaponized, the basic science of their mutation and resistance could be useful in helping us to understand these threats. Fauci hopes to make the case that funds for biodefense should be used to study the ESKAPE bugs, but, for now, he is quick to point out the challenge posed by a lack of resources. The problem is, it is extremely difficult to do a prospective controlled trial, because when people come into the hospital they immediately get started on some treatment, which ruins the period of study, he said, referring to research into the treatment of common infections. The culture of American medicine makes a study like that more difficult to execute. These types of studieson how often, and for how long, antibiotics should be prescribedare much easier to conduct in countries where medicine is largely socialized and prescriptions are tightly regulated. Recently, researchers in Israel, where most citizens receive their care through such a system, showed that refraining from empirically prescribing antibiotics during the summer months resulted in a sharp decline in ear infections caused by antibiotic-resistant microbes. (In the United States, a 1998 study estimated that fifty-five per cent of all antibiotics prescribed for respiratory infections in outpatients22.6 million prescriptionswere unnecessary.) In Sweden, the government closely monitors all infections, and has the power to intervene as needed. Our infection-control people have a lot of authority, Giske said. This is power from the legislation. Once a resistant microbe is identified, stringent protocols are put in place, with dramatic results. Fewer than two per cent of the staphylococci in Sweden are MRSA , compared with sixty per cent in the United States. Of course, its only around ten million people, so its possible to intervene because everything is smaller, Giske said, adding, Maybe Swedes are more used to this type of intervention and regulation. Stuart Levys laboratory occupies the eighth floor of a renovated building on Harrison Avenue in Bostons Chinatown, across the street from Tufts Medical Center. As I passed from his office into the corridor, I detected the acrid smell of agar, which is used to grow bacteria. That day, a laboratory technician was testing specimens taken from the eyes of people with bacterial conjunctivitis who had been given an antibiotic eye drop containing fluoroquinolone. Levy was comparing the bacteria from the infected eyes with those in the noses, cheeks, and throats of the same patients. His technician held up a petri dish with a cranberry-colored agar base. The patients specimen was growing bacteria that were susceptible to the antibiotic; the drug had created a large oval clear zone on the plate which resembled the halo around the moon. The study investigates whether an antibiotic applied to the eye would affect bacteria in the nose and mouth as well, which might indicate that what seems to be an innocuous and limited treatment may profoundly change a wider area of the body and foster resistant microbes. Levy has also received funding from the N.I.H. to study Yersinia pestis , the microbe that causes plague; the Department of Agriculture has sponsored his study of Pseudomonas fluorescens , a soil-based bacterium that has the potential to protect plants from microbial infection. He plans to develop it as a biocontrol agent, so that farmers can be weaned off the potent antibiotics and chemicals they use to treat their fields. We need to treat biology with biology, not chemistry, he said. In other studies, Levy and his team are looking at ways to render bacteria nondestructive and noninvasive, so that they might enter the body without harmful effects. This makes it necessary to identify virulence factorswhich parts of the bacteria cause damage to our tissues. Levys laboratory is targeting a protein in gram-negative organisms called MAR , which appears to act as a master switch, turning on both virulence genes and genes that mediate resistance, like the efflux pump. In collaboration with a startup company called Paratek, of which Levy is a co-founder, his laboratory is screening novel compounds in the hope of finding a drug that blocks MAR . Frederick Ausubel, a bacterial geneticist at the Massachusetts General Hospital, in Boston, is searching for drugs to combat bacterial virulence, using tiny animals like worms, which have intestinal cells that are similar to those in humans, and which are susceptible to lethal microbial infection. The worm that Ausubel is studying, Caenorhabditis elegans , is one and a half millimetres in length. You are probably going to have to screen millions of compounds and you cant screen millions of infected mice, Ausubel said. So our approach was to find an alternative host that could be infected with human pathogens which was small enough and cheap enough to be used in drug screens. Whats remarkable is that many common human pathogens, including Staphylococcus and Pseudomonas , will cause intestinal infection and kill the worms. So now you can look for a compound that cures it, that prevents the pathogen from killing the host. Ausubel first screened some six thousand compounds by hand and found eight, none of them traditional antibiotics, that may protect the worms. He is also attempting, among other potential solutions, to find a compound that would block what is called quorum sensing, in which bacteria release small molecules to communicate with one another and signal when a critical mass is present. Once this quorum is reached, the bacteria turn on their virulence genes. Bacteria dont want to alert their host that they are there by immediately producing virulence factors which the host would recognize, triggering the immune system, Ausubel explained. When they reach a certain quorum, there are too many of them for the host to do anything about it. Bonnie Bassler, a molecular biologist at Princeton University, has recently shown that it is through quorum sensing that cholera bacteria are able to accumulate in the intestines and release toxins that can be fatal; Pseudomonas is also known to switch on its virulence genes in response to signals from quorum sensing. Moellering is enthusiastic but cautious about this avenue of research. Its a great idea, but so far nobody has been able to make it work for human infections, he told me. With certain types of staphylococci , Moellering said, mutations have occurred spontaneously in nature that cut down on a number of virulence factors . . . but they still cause serious infections. Im not sure that we have a way yet to use what we know about virulence factors to develop effective antimicrobial agents. And we almost certainly will have to use these agents in combination with antibiotics. No one, Moellering said, has developed a way to disarm bacteria sufficiently to allow the human body to naturally and consistently defend against them. I asked him what we should do to combat these new superbugs. Nobody has the answer right now, he said. The fact of the matter is that we have found all the easy targets for drug development. He went on, So the only other thing we can do is continue to work on antibiotic stewardship. Meanwhile, new resistant bacteria, Moellering asserted, arent going to go away. We can temper things, we might be able to slow the rate of emergence of resistance, but its unlikely that we will ever be able to conquer it. 标签: 微生物 , 翻译