Prolonged milk provisioning in a jumping spider Zhanqi Chen1, Richard T. Corlett1, Xiaoguo Jiao2, Sheng-Jie Liu3, Tristan Charles-Dominique1, Shichang Zhang2, Huan Li1, Ren Lai4, Chengbo Long4, Rui-Chang Quan1 Lactation is a mammalian attribute, and the few known nonmammal examples have distinctly different modalities. We document here milk provisioning in a jumping spider, which compares functionally and behaviorally to lactation in mammals. The spiderlings ingest nutritious milk droplets secreted from the mother’s epigastric furrow until the subadult stage. Milk is indispensable for offspring survival in the early stages and complements their foraging in later stages. Maternal care, as for some long-lived vertebrates, continues after the offspring reach maturity. Furthermore, a female-biased adult sex ratio is acquired only when the mother is present. These findings demonstrate that mammal-like milk provisioning and parental care for sexually mature offspring have also evolved in invertebrates, encouraging a reevaluation of their occurrence across the animal kingdom, especially in invertebrates. 哺乳是哺乳动物的一种属性，少数已知的非哺乳动物的例子有明显不同的模式。我们在这里记录了跳蛛的哺乳情况，并且在功能和行为上都与哺乳动物的哺乳行为类似。蜘蛛幼蛛摄取母亲生殖沟分泌的营养奶滴，直到亚成体阶段。乳汁对于后代在早期阶段的生存是必不可少的，并在后期补充它们的觅食。母性护理（亲代抚育），就像一些长寿的脊椎动物一样，在后代成熟后继续进行。此外，只有在母亲（亲本雌蛛）在场的情况下，才能获得偏向雌性的成蛛性别比。这些发现表明，无脊椎动物也进化了类似哺乳动物的母乳供应和父母对性成熟后代的照顾，鼓励重新评估它们在整个动物界的出现情况，特别是在无脊椎动物中。 Parental food provisioning is often indispensable to an offspring’s growth, development, and survival and subsequently affects litter size, sex ratio, and offspring body size. Foods provided by parents can be classified into three forms: direct food sources, regurgitation feedings, and specialized food sources. Specialized foods include mammalian milk, as well as trophic eggs in amphibians and invertebrates, epidermal mucus in fish, and milk in cockroaches and pigeons. However, these other foods are very different from mammalian milk in both duration of provisioning and degree of parent-offspring interaction. Parental food provisioning often stops when offspring acquire foraging ability, and provisioning for nutritionally independent offspring has mainly been reported from longer-lived vertebrates. Extended food provisioning frequently co-occurs with prolonged parental care, enhancing offspring fitness by providing assistance in foraging, teaching skills of foraging and competition, or influencing the morphology and behaviors of offspring. In extreme cases, parental care is extended to sexually mature offspring, but this has only been recorded in long-lived social vertebrates. Prolonged care increases offspring fitness by enabling them to allocate more time for learning foraging and social skills, antipredator behaviors, and defense against nest parasites and for selecting mates. 父母的食物供应对于后代的生长、发育和生存通常是不可或缺的，并随后影响产仔数、性别比例和后代的体型。父母提供的食物可以分为三种形式：直接食物来源、反流喂养和特殊食物来源。专门的食物包括哺乳动物的牛奶，以及两栖动物和无脊椎动物的营养卵，鱼的表皮粘液，蟑螂和鸽子的牛奶。然而，这些其他食物在供应时间和亲子互动程度上都与哺乳动物的牛奶有很大的不同。父母的食物供应通常在后代获得觅食能力时停止，而对营养独立的后代的供应主要来自较长寿的脊椎动物。长时间的食物供应经常伴随着长时间的父母照料，通过提供觅食帮助来增强后代的健康，传授觅食和竞争的技能，或者影响后代的形态和行为。在极端情况下，父母的照顾延伸到性成熟的后代，但这只在长寿的群居脊椎动物中有记录。长时间的照料使后代能够分配更多的时间来学习觅食和社交技能、反捕食者行为、防御巢穴寄生虫和选择配偶，从而提高了后代的健康水平。 Toxeus magnus (Araneae: Salticidae) is a jumping spider that mimics ants. The breeding nest is composed of either several large individuals (fig. S1), with two or more adults, or one adult female and several juveniles. This is a puzzling observation for a species assumed to be noncolonial and suggests that T. magnus might provide either prolonged maternal care or delayed dispersal. We thus questioned (i) whether T. magnus evolved long-lasting maternal care; (ii) if it has, whether the mother provides food for the offspring; (iii) what benefits could be gained from maternal care; and (iv) how long the mother provides an effective maternal care. 大蚁蛛 ( 蜘蛛目：跳蛛科 ) 是一种模仿蚂蚁的跳蛛。繁殖巢由几个较大的个体组成 ( 图 2) 。 S1) ，有两个或两个以上的成蛛，或一只成年雌性和几只幼蛛。对于一个被认为是非殖民地（ noncolonial 非社会性的）的物种来说，这是一个令人费解的观察结果，并表明 T. magnus 可能提供长期的母体护理或延迟的分散。因此，我们质疑 (I) T. magnus 进化出了持久的产妇护理（亲代抚育）； (Ii) 如果有，母蛛是否为后代提供食物； (Iii) 母蛛护理可以获得什么好处；以及 (Iv) 母蛛提供有效亲代抚育的时间有多长。 We first assessed how offspring developed and behaved under maternal care in laboratory conditions. No spiderlings were observed leaving the nest for foraging until they were 20.9 ± 1.2 days (N = 207 , N nest = 19; SEM) old, and the mother was never seen to bring food back to the nest during this period, but offspring body lengths increased continuously (from 0.9 mm at hatching to 3.5 mm at 20 days,N= 187). Closer observations revealed that the mother provided a seemingly nutritive fluid, hereafter called milk, to the offspring. During the first week, she deposited milk droplets, excreted from her epigastric furrow, on the nest’s internal surface. In response, spiderlings came and sucked the droplets (Fig. 1B). After the first week, milk deposition stopped and the offspring sucked directly from the mother’s epigastric furrow (Fig. 1C and movies S1 and S2). Although spiderlings sometimes left the nest to forage from about 20 days, milk sucking continued until they reached the subadult stage at 37.5 ± 1.3 days (N = 1 6 7 ) ( Figs. 1 C ) , with body length of 5.26 ± 0.06 mm (around 80% of adult body length). From 40 days, milk feeding stopped, but spiderlings still used the nest at night after reaching sexual maturity within the next 20 days. Adulthood was reached at 52.2 ± 0.6 days with a body length of 6.57 ± 0.06 mm (N = 145) (Fig. 1D and fig. S2). Milk provisioning in T. magnus involves a specialized organ over an extended period, differing markedly from cockroaches, which deposit nourishing substances to the brood sac of developing embryos. In these aspects, T. magnus milk provisioning is more similar to mammalian lactation. 我们首先在实验室条件下评估了后代在母体照料下的发育和行为。直到 20.9±1.2 日龄 (N=207 ， Nnest=19 ； SEM) 才观察到蜘蛛幼体离开巢穴觅食，在此期间没有看到母蜘蛛将食物带回巢，但子代的体长不断增加 ( 从孵化时的 0.9 mm 增加到 20 日龄的 3.5 mm ， N=187) 。更仔细的观察显示，母亲给后代提供了一种看似有营养的液体，以下称为牛奶。在第一周，她把从她的上腹生殖沟里排出的奶滴放在巢穴的内表面。作为回应，幼蛛过来吸吮蛛奶 ( 图 1B) 。第一周后，乳汁沉积停止，后代直接从母亲的上腹沟中吸吮 ( 图 1C 和电影 S1 和 S2) 。虽然蜘蛛幼蛛有时从 20d 左右离开巢去觅食，但吸奶一直持续到 37.5±1.3d (N=1.67)( 图 1C) ，体长为 5.26± 0.06 mm( 约占成蛛体长的 80%) 。从 40 天开始，喂奶停止，但蜘蛛幼蛛在接下来的 20 天内达到性成熟后，仍然在晚上使用这个巢穴。成年时间为 52.2±0.6 天，体长为 6.57±0.06 mm(N=145) 。 (S2) 。在很长一段时间内， T. magnus 的乳汁供应涉及一个专门的器官，这与蟑螂有明显的不同，蟑螂将营养物质储存到发育中的胚胎的孵化囊中。在这些方面， T. magnus 的供乳更类似于哺乳动物的泌乳。 Observations under the microscope showed droplets leaking from the mother’s epigastric furrow where the spiderlings sucked milk (Fig. 2, A and B). Spider milk total sugar content was 2.0 mg/ml, total fat 5.3 mg/ml, and total protein 123.9 mg/ml, with the protein content around four times that of cow’s milk. We suggest this milk might have evolved from trophic eggs, unviable eggs functioning as a food for newly emerged offspring. The epigastric furrow is the egg-laying opening of spiders, and trophic eggs have evolved in diverse invertebrate taxa, including spiders. Trophic eggs are usually a one-time investment, but mothers may also supply progressive trophic eggs, as in the burrower bug Adomerus triguttulus . However, progressive provisioning usually stops after hatching, whereas spider milk is supplied continuously from hatching to subadult. 显微镜下的观察显示，蜘蛛幼蛛吸奶的地方，雌蛛的生殖沟漏出了水滴 ( 图 2 ， A 和 B) 。蜘蛛乳的总糖含量为 2.0 mg/ml ，总脂肪含量为 5.3 mg/ml ，总蛋白含量为 123.9 mg/ml ，蛋白质含量约为牛乳的 4 倍。我们认为这种牛奶可能是从营养卵进化而来的，营养卵是一种不能存活的卵，可以作为新出现的后代的食物。上腹沟是蜘蛛产卵的开口，营养卵在包括蜘蛛在内的各种无脊椎动物类群中进化。营养卵通常是一次性的投资，但母亲也可能提供渐进式的营养蛋，就像穴居虫 Admerus triuttulus 一样。然而，渐进式供应通常在幼蛛孵化后停止，而蜘蛛奶从孵化到亚成蛛是持续供应的。 The mother continued nest maintenance throughout, carrying out spiderlings’ exuviae and repairing nest damage. When receiving both maternal care and milk, 76% of the hatched offspring survived to adulthood. We also recorded a highly female-biased adult sex ratio: 84.14% (122/145). Although the mother apparently treated all juveniles the same, only daughters were allowed to return to the breeding nest after sexual maturity. Adult sons were attacked if they tried to return. This may reduce inbreeding depression, which is considered to be a major selective agent for the evolution of mating systems. 这位母亲从头到尾都在继续维护巢穴，为蜘蛛幼蛛进行蜕皮，并修复巢穴的损坏。当同时接受母婴护理和母乳喂养时， 76% 的孵化后代存活到成年。我们还记录了高度偏向雌性的成熟性别比： 84.14%(122/145) 。尽管母亲显然对所有的幼代一视同仁，但只有女儿在性成熟后才被允许回到繁殖巢中。如果成年的儿子试图返回，他们就会受到攻击。这可能会减少近亲交配抑制，而近交抑制被认为是交配系统进化的主要选择因素。 When we blocked the mother’s epigastric furrow immediately with correction fluid after hatchling emergence, the hatchlings stopped development and died 10.4 ± 0.5 days later (Fig. 3A and fig. S3), showing their complete dependence on the milk supply. A separate experiment showed that correction fluid did not affect spiderlings’ survivorship (fig. S6). We then tested why parental care and milk provisioning were continued after 20 days when the spiderlings were able to forage for themselves. We assessed the effects on survival, growth, foraging, and nest departure of (i) blocking the milk at this stage but leaving the mother in the nest to assess the effect of maternal care without milk provisioning and (ii) removing the mother from the nest to assess the combined effects of maternal care and milk provisioning. Removing the mother after 20 days significantly reduced survivorship (Fig. 3A) and body size (Fig. 3B) and increased foraging (Fig. 3C) and activities outside the nest (Fig. 3D). Blocking milk significantly reduced survivorship (Fig. 3A), but did not affect body size (Fig. 3B), and increased foraging (Fig. 3C) and activities outside the nest (Fig. 3D) compared with those receiving full maternal care and milk. Among spiderlings not receiving milk, those receiving maternal care survived significantly better (Fig. 3A), grew faster (Fig. 3B), and left the nest more rarely (Fig. 3D) than those without the mother, but both showed similar foraging frequency (Fig. 3C) (table S1 to S4). The milk-blocked spiderlings still attempted to suck milk from the mother (movie S3). These results show that from days 20 to 40, milk provisioning is not essential for spiderlings’survival, as they can compensate by foraging more, but has a positive effect on survivorship and development in lab conditions. In the field, milk provisioning, by reducing time spent outside the nest, might also reduce predation risk, as smaller offspring are more prone to predation. When spiderlings did not have milk, the higher surviorship with their mother present might be mediated by parasites. Although not quantified, parasites were observed on juveniles commonly without maternal care but rarely when the mother was present. Nest cleaning and repairing by the mother may partly explain this reduction in parasite loads. Nest parasites are common in invertebrates, and parental care usually plays a crucial role in reducing juvenile parasite infections. 幼蛛孵化后立即用涂改液堵住母体的生殖沟，孵化出的幼蛛停止发育， 10.4±0.5 天后死亡 ( 图 3A 和图 3) 。 S3) ，表现出对蛛奶供应的完全依赖。另一项单独的实验表明，涂改液不会影响蜘蛛幼蛛的存活 ( 图 S6) 。然后，我们测试了为什么在蜘蛛幼蛛能够自己觅食的 20 天后，亲代抚育和蛛奶供应仍在继续。我们评估了以下措施对生存、生长、觅食和离巢的影响： (I) 在这个阶段阻断母乳，但将雌蛛留在巢中，以评估不提供母乳的亲代抚育的效果； (Ii) 将母亲从巢中移走，以评估亲代抚育和蛛奶供应的综合效果。 20 天后移走母亲，显著降低了存活率 ( 图 3A) 和体型 ( 图 3B) ，增加了觅食 ( 图 3C) 和巢外活动 ( 图 3D) 。与接受充分的母亲关怀和母乳的相比，阻断蛛奶显著降低了幼蛛存活率 ( 图 3A) ，但不影响身体大小 ( 图 3B) ，增加了幼蛛觅食 ( 图 3C) 和巢外活动 ( 图 3D) 。在没有接受母乳的幼蛛中，那些接受亲代抚育的幼蛛存活得明显更好 ( 图 3A) ，生长更快 ( 图 3B) ，更少离开巢穴 ( 图 3D) ，但两者都显示出相似的觅食频率 ( 图 3C)( 表 S1 至 S4) 。蛛奶堵塞的蜘蛛幼蛛仍然试图从母亲那里吸奶 ( 电影 S3) 。这些结果表明，在实验室条件下，从第 20~40d ，供乳对幼蛛的存活并不是必需的，因为它们可以通过增加觅食来补偿，但对存活和发育有积极的影响。在野外，提供蛛奶，通过减少在巢外停留的时间，也可能降低捕食风险，因为较小的后代更容易被捕食。当蜘蛛幼蛛没有母乳时，它们母亲在场时的高存活率可能是由寄生虫介导的。虽然没有量化，但通常在没有母亲照料的幼蛛身上观察到寄生虫，但很少在母亲在场的情况下观察到。母亲清理和修复巢穴可能在一定程度上解释了寄生虫载量的减少。巢寄生虫在无脊椎动物中很常见，父母的照顾通常在减少幼年寄生虫感染方面起着至关重要的作用。 Removing the mother at day 20 reduced the percentage of spiderlings reaching maturity and reduced their adult body size (by 12%), whereas blocking milk did not change their adult survivorship or body size (MB20: 6.64 ± 0.07 mm) compared with the control (Fig. 4, A and D). Most notably, removing the mother greatly affected the adult sex ratio (female/total: MC = 0.84, MR20 = 0.50), whereas blocking milk did not (MB20 = 0.87) (Fig. 4C). Further analysis showed that the reduction of offspring body size after mother removal is not caused by a sex ratio change coupled with intersexual differences (table S6). No treatment impacted the timing of developmental stages (MR20: 52.5 ± 0.78 days, MB20: 50.5 ± 0.82 days, MC: 52.3 ± 0.60 days) (Fig. 4B and table S5). Thus, milk provisioning after 20 days does not affect adult survivorship, body size, sex ratio, and development time, but the mother’s presence plays a key role in assuring high adult survival and normal body size. This may reflect the parasite defense discussed above. The mother’s presence is also required for achieving the female-biased sex ratio of adult offspring. Sex role divergence theory suggests that the reproductive value of a population is heavily determined by the sex that invests more in parental care. In T. magnus , the mother invests much more than the male invests, predicting a female-biased sex ratio to be optimal for reproductive success with a polygamous mating system. Unequal adult sex ratios could be passively induced, as with the selective mortality with respect to sex in the bark beetle Dendroctonus ponderosae , or maternally induced, as in the spider Oedothorax gibbosus , but the mechanisms remain largely unclear. 20 日龄去掉母体降低了蜘蛛幼蛛的成熟率 ，并缩小了它们的成年体型 ( 减少 12%) 。与对照组相比，阻断乳汁并没有改变它们的成蛛存活率 或身体大小 (MB20 ： 6.64±0.07 mm) 与对照组比较 ( 图 4 ， A 和 D) 。最值得注意的是，去掉母亲极大地影响了子代成年时性比 ( 雌性 / 总： MC=0.84 ， MR20=0.50) ，而阻断蛛奶没有影响 (MB20=0.87)( 图 4C) 。进一步的分析表明，移走母亲后后代的体型变小不是由性别比例的改变加上两性之间的差异引起的 ( 表 S6) 。不处理影响发育阶段的时间 (MR20 ： 52.5±0.78 天， MB20 ： 50.5±0.82 天， MC ： 52.3±0.60 天 )( 图 4B 和表 S5) 。因此， 20 天后的母乳供应不会影响成蛛的存活率、体型、性别比例和发育时间，但母亲的在场对确保成体的高存活率和正常的体型起着关键作用。这可能反映了上面讨论的寄生虫防御。要实现成年后代中偏向雌性的性别比例，母亲的在场也是必需的。性别角色分化理论表明，人口的生育价值在很大程度上取决于亲代的投入。在 T.Magnu s 中，雌蛛的投资远远超过雄蛛的投资，预测在一夫多妻制的交配系统中，雌性偏向的性别比例将是生殖成功的最佳选择。不平等的成虫性别比可以被被动地诱导，比如松毛虫的性别选择性死亡，或者母性诱导的不平等，比如蜘蛛 Oedothorax gibbosus ，但其机制仍然很不清楚。 In mammals, lactation is likely an adaptation mitigating an uncertain access to food resource as a juvenile and compensating for low probabilities for future reproduction. More generally, food provisioning helps promote offspring fitness by reducing risks linked to self-feeding. In nonmammals, we suggest that the most important ecological conditions favoring the evolution of lactation might be predation risk and uncertain food access. As a response, the mother’s physiology, behavior, and cognition might have changed to adapt to providing milk and prolonged maternal care as in mammals. Extended parental care could have evolved in invertebrates as a response to complex and harsh living environments that require offspring skills (e.g., hunting, predator defense) to be fully developed before complete independence. Another aspect to investigate is whether lactation and extended parental care are accompanied by a reduction in offspring number because of milk production and parental care costs. Lastly, we anticipate that the discoveries presented in this study will encourage a reevaluation of the evolution of lactation and its occurrence across the animal kingdom. 在哺乳动物中，哺乳很可能是一种适应，缓解了青少年时期获取食物资源的不确定性，并补偿了未来繁殖的低可能性。更广泛地说，食物供应通过降低与自我捕食相关的风险，有助于促进后代的健康。在非哺乳动物中，我们认为最重要的有利于哺乳期进化的生态条件可能是捕食风险和不确定的食物获取。作为回应，母亲的生理、行为和认知可能发生了变化，以适应提供蛛奶和长时间的产妇护理，就像哺乳动物一样。在无脊椎动物中，延长父母照顾可能是对复杂而恶劣的生活环境的一种反应，这些环境需要后代技能 ( 例如，狩猎、捕食者防御 ) 在完全独立之前得到充分发展。另一个要调查的方面是，哺乳和延长父母照料是否会因为产奶和蛛亲代抚育费用而伴随着后代数量的减少。最后，我们预计，这项研究中提出的发现将鼓励重新评估泌乳的进化及其在整个动物界的发生。
美国 CDC在2012 年《 Breast-feeding Rates in US Continue to Rise 》的报告中表明美国妇女哺乳率上升的数据 http://www.medscape.com/viewarticle/768631 。 同时还有一份全美国各州的情况 http://www.cdc.gov/breastfeeding/pdf/2012BreastfeedingReportCard.pdf
哺乳动物在哺乳期的高摄食行为与瘦素有关 哺乳动物最大的特点之一自然是哺乳了。可哺乳是哺乳动物非常耗能的一个过程，哺乳期也是消耗能量很多的一个时期。这样一般的雌性小型哺乳动物（如鼠类）在哺乳期经常是增加能量摄入，吃得多。还有一个特点是在哺乳高峰期母体会消耗体内储存的脂肪，这个时候母体的体内脂肪含量是最低的。母体在这个时期将身体脂肪含量降到很低的水平有什么生理意义呢？这方面的生理功能现在还不是很清楚。有一种说法是母体在哺乳期动用身体的脂肪存积主要是由于母体的能量消耗过多，能量摄入不足以补偿哺乳活动所消耗的能量。但是通过计算就可以发现，动物从消耗的脂肪中所获取的能量在整个能量平衡中占的份额是微不足道的。那么，母体在哺乳期身体脂肪含量降低的生理功能是什么呢？一个科学假说认为：哺乳动物身体脂肪含量降低会导致一些脂肪激素的降低（如瘦素），而低瘦素水平在哺乳期具有刺激过量摄食的作用。 我们以内蒙古典型草原区的一种季节性繁殖的啮齿动物布氏田鼠为研究对象，利用微渗透泵技术在野生啮齿动物布氏田鼠哺乳期的最后 7 天，通过施加外源瘦素以确定瘦素在哺乳高峰期的生理功能。布氏田鼠是草食性动物，储存食物越冬，不具有冬眠的习性，穴居，聚群生活。我们研究组对布氏田鼠的生理生态学特征和适应环境的生理机理已有多年的研究，有很好的研究积累，包括哺乳期能量消耗的测定等等。 研究结果发现，施加外源瘦素可以明显降低哺乳布氏田鼠的体重和摄食量，瘦素的这种生理效应与施加的瘦素剂量相关。由于母体体内脂肪含量降低导致的体内循环的瘦素水平也降低（瘦素主要是由白色脂肪细胞分泌的），通过将哺乳的田鼠与非繁殖的田鼠个体进行比较可知，哺乳田鼠 16% 的能量过度摄入是由于瘦素水平所导致的。哺乳期瘦素水平降低，可以通过（部分）刺激控制中枢下丘脑的增食类的神经肽（如 NPY 和 AgRP ）和厌食类的神经肽（如 POMC ）的变化，从而调节哺乳期田鼠母体的高摄食行为。瘦素的这种生理效应还可以通过施加外源瘦素而发生逆转。 在本研究中我们采用双标记水（ H3, O18 ）的方法，对哺乳田鼠在自由活动状态下的能量消耗进行了测定，并计算了母体的泌乳量（通过将母体的摄入能量与消耗的能量进行比较，就可以获得泌乳量）。我们的结果发现，外源瘦素处理并没有影响哺乳布氏田鼠的每日能量消耗、母体的泌乳量或幼崽的生长速率，但却导致非颤抖性产热组织（褐色脂肪组织 , BAT ）中线粒体内膜上解偶联蛋白 UCP1 表达的增加 （一般在哺乳期，动物 BAT 中 UCP1 的含量是降低的）。非颤抖下产热（ nongshivering thermogenesis, NST ）就是动物没有通过肌肉收缩而产生热量的一种方式，这主要是在褐色脂肪组织（ BAT ）内产生（ BAT 与白色脂肪组织结构和功能都不同）， BAT 内产生热量的分子基础是解偶联蛋白 1 (uncoupling protein 1, UCP1) 。这个发现表明在哺乳高峰期动物身体脂肪含量降低和瘦素水平降低可能还具有其他的生理功能，如引起 BAT 产热的变化等。这些结果发表在《美国生理学杂志》 (American Journal of Physiology) 上。 本项工作是我们研究组崔建国博士的博士论文的部分内容。本研究是我们研究组与英国阿伯丁大学合作完成的， JR Speakman 实验室提供了微渗透泵和测定动物能量消耗用的双标记水 (DLW) ，并协助完成血样的测试和分析工作。本研究受到国家基金委和科技部的基金资助，受到基金委国际合作项目的资助。 Cui JG, Tang GB, Wang DH, Speakman JR. 2011 Effects of leptin infusion during peak lactation on food intake, body composition, litter growth, and maternal neuroendocrine status in female Brandt’s voles ( Lasiopodomys brandtii ). Am J Physiol Regul Integr Comp Physiol 300: R447–R459. First published December 1, 2010; doi:10.1152/ajpregu.00121.2010 . 论文的PDF文本： CuiJG-AJP2011.pdf
标签: 哺乳
