# 编者信息 熊荣川 明湖实验室 xiongrongchuan@126.com http://blog.sciencenet.cn/u/Bearjazz Here, we present a major new version of the molecular evolutionary software package Bayesian Evolutionary Analysis by Sampling Trees (BEAST), updated to version 1.7, and representing a signifcant software advance over that previously described (Drummond and Rambaut 2007). Alongside the primary analysis engine in BEAST, this package also includes a suite of utilities for specifying the analysis design, processing output files, and summarizing and visualizing the results. Taken together, these programs enable Bayesian inference of molecular sequences with an emphasis on time-structured evolutionary models including phylodynamic models, divergence time estimates, multiloci demographic models, gene–/species–tree inference, a range of spatial phylogeographic analyses, and discrete and continuous trait evolution. Implementing Markov chain Monte Carlo (MCMC) algorithms to perform these inferences, the package is intended and used for rigorous statistical inference and hypothesis testing of evolutionary models with joint inference of phylogeny. It is also possible to constrain portions of the phylogenetic model space to known values, including the tree topology, and perform conditional inference if required. 在这里,我们提出了 BEAST 一个重要更新版本( 1.7 版),相较先前介绍的版本( Drummond and Rambaut 2007 )它代表了一个显著的软件进步。除了 BEAST 中的主要分析核心要件外,此软件包还包括一套用于指定分析设置、处理输出文件以及汇总和可视化结果的实用程序。综合起来,这些程序使分子序列的贝叶斯推断成为可能,重点是时间结构进化模型,包括系统动力学模型、分化时间估计、多基因座种群模型、基因 / 物种树推断、空间分布范围系统地理分析,以及离散和连续的特征进化。利用马尔可夫蒙特卡罗( MCMC )算法实现这些推断,并将其应用于系统发育联合推论的进化模型的严格统计推断和假设检验。还可以将系统发育模型空间的一部分限制为已知值,包括树拓扑结构,并在需要时执行条件推断。 Drummond A J , Suchard M A , Xie D , et al. Bayesian Phylogenetics with BEAUti and the BEAST 1.7 . Molecular Biology and Evolution, 2012, 29(8):1969-1973.
吴国林 不小心,今天,我的夫人将我西式短裤放入到滚筒洗衣机中去洗,但是,没有将我的联想 U 盘取出来,于是,它与被洗了近1个小时,取衣服时,才发现了 U 盘。此 U 盘,我已使用了5年以上,为8G。我拿起吹风吹,又等于近1小时,才用。将 U 盘插入电脑, 会如何? 一切正常! 没有想到,此 U 盘 具有防水之功能! 我不知道,其他 U 盘是否能如此? 注释: 我又查寻了一下, 我这一型号的联想U盘,真的能够防水!它设计时就是防水的。 并不是所有U盘都是防水的。
现在我越来越相信所谓的垃圾DNA其实是有功能的,而最著名的“垃圾DNA”就是转座子了,所以这篇博文想把零零星星的关于转座子功能的报道整理到一起。 1 Developmental relaxation of transposable element silencing in plants: functional or byproduct?( http://www.sciencedirect.com/science/article/pii/S1369526612001136 ) 这篇文章出现一个新名词:the d evelopmental r elaxation of t ransposable element s ilencing (DRTS)。这个词的中文翻译好像有点扯,所以就不翻译了。意思大概是:在正常发育过程中转座元件表达。有什么功能呢?文章推测:One function may be the production of transposable element small RNAs.产生小RNA。小RNA是一种重要的基因表达调控因子。当然在此基础上可以合理的推测:不同的转座子会产生不同的小RNA,用来调控不同的基因表达。如果用已知的小RNA数据库和已知的转座子数据库去进行序列比对,也许能够建立小RNA和具体的转座子间的联系。 2 Epigenetic control of transposon transcription and mobility in Arabidopsis ( http://www.sciencedirect.com/science/article/pii/S1369526612001094 ) 结论:The epigenetic interplay between TE and genes thus plays a crucial role in the TE-host co-evolution.TE和基因的表观遗传学互作在转座子-宿主基因组的共同进化中扮演关键较色。换句话说:转座子通过表观遗传学机制发生作用。 本文亮点: ATE transcription is massively released in Arabidopsis epigenetic mutants and under stress conditions.在拟南芥的表观遗传学突变体和逆境条件下发生大量的TE转录(拟南芥是这样,那么水稻、玉米等估计也8 9不离10)。 B► TE transposition across generations is limited to a few TE families as revealed in Arabidopsis epigenetic mutants after inbreeding. 要理解这点得看下全文 C► TE neo-insertions can attract epigenetic marks to nearby genes thereby modifying the host gene expression.TE的插入为旁侧基因引入表观遗传学标记,从而影响基因表达。 小结1 2:1 是说TE的表达会有功能 2 是说TE的转座会有功能。共同点:影响基因表达调控。 3 Transcriptional Silencing of Transposons by Piwi and Maelstrom and Its Impact on Chromatin State and Gene Expression( http://www.sciencedirect.com/science/article/pii/S0092867412013037 ).这篇文章研究了转座子沉默的分子机制。所以人家发CELL了。进行转座子的研究可以发CELL,这对中国科学家有积极的意义。根据这篇文章的信息在动物的性腺存在一条转座沉默调控途径:The piRNA pathway。文章结论:Our work illustrates the widespread influence of transposons and the piRNA pathway on chromatin patterns and gene expression.转座子和piRNA途径广泛影响染色质结构和基因表达。由此看,转座子不但有功能,而且是非常重要的功能。问题自然就来了,植物组织中是否有类似的调控途径和相似的功能?既然有抑制的途径,那很自然地有促进途径,这个途径是什么?调控的关键节点在哪?如果能人为控制这个开关。。。?当这么重要的东西,曾今被认为是“垃圾DNA”,如果现在还固执的这么认为,那么是不是应该反问下:“我是不是垃圾?”了。在这个具体问题上,我不是垃圾。 4 Transposable Elements: An Abundant and Natural Source of Regulatory Sequences for Host Genes( http://www.annualreviews.org/doi/abs/10.1146/annurev-genet-110711-155621 )这是2012年的一篇关注转座子的重量级文章。摘要如下:The fact that transposable elements (TEs) can influence host gene expression was first recognized more than 50 years ago. However, since that time, TEs have been widely regarded as harmful genetic parasites—selfish elements that are rarely co-opted by the genome to serve a beneficial role. Here, we survey recent findings that relate to TE impact on host genes and remind the reader that TEs, in contrast to other noncoding parts of the genome, are uniquely suited to gene regulatory functions. We review recent studies that demonstrate the role of TEs in establishing and rewiring gene regulatory networks and discuss the overall ubiquity of exaptation. We suggest that although individuals within a population can be harmed by the deleterious effects of new TE insertions, the presence of TE sequences in a genome is of overall benefit to the population. 5 资源:植物重复序列数据库: http://plantrepeats.plantbiology.msu.edu/downloads.html 今日结语:今天是传说中的世界末日,为了庆祝这个黑暗而伟大的时刻的离去,特发此文,纪念这个特殊的时刻。当然这是扯蛋。除了扯蛋的东西外,这篇短文还是有干货的,当然是不是垃圾得分谁来看。用垃圾的眼光看到的自然都是垃圾。呵呵。
http://blog.csdn.net/yishengxiao/archive/2008/07/28/2723312.aspx 磨练 构建正则表达式模式的技能 通过本文的学习,您可以增加一些有用的设计实际正则表达式 (regexp) 的技能。构建正则表达式是任何管理员日常工作中的一部分。为了构造返回所需条件的成功正则表达式,需要学习以模式匹配的角度进行思考,而这种技能需要花大量的时间进行练习。 引言 UNIX 管理员每天都需要构建和使用正则表达式 (regexp) 进行文本模式匹配。大多数语言都支持正则表达式的某种实现。有的应用程序(如 EMACS)具有正则表达式搜索功能,并且您可以通过各种命令行工具使用正则表达式。无论什么应用程序,构建正确的正则表达式的关键之处在于,识别仅满足需要匹配的数据的模式,以便在输入中排除其他不必要的内容。 出于这个目的,本文将逐步介绍几种正则表达式模式构建技巧,并介绍它们如何帮助您完成各种常规任务。 使用正则表达式 (regexp) 除非特别说明,否则本文中使用的示例都是扩展可移植操作系统接口(扩展 POSIX)的正则表达式。如果通过命令行(如使用 egrep 实用工具)使用它们,您应该根据需要引用各种正则表达式。请记住,不同的正则表达式实现之间存在一些区别,您可能不得不适应所使用的特定的工具、应用程序或语言中的具体实现。 匹配整行内容 ^ 元字符匹配行首,而 $ 匹配行尾,如果将它们组合在一起(如 ^$),它们将匹配空行。(这个表达式的镜像,即 $^,是不可能匹配成功的,它将永远 都无法匹配到有效行。)这个基本的正则表达式是许多复杂正则表达式的基础,如果您还不习惯使用这个基本的正则表达式,那么您应该逐步养成使用它的习惯。使用它来构建匹配整行内容 的模式。 在用户字典文件 (/usr/dict/words) 中搜索是一个很好的基本模式。(有些版本的 UNIX 将用户字典放在 /usr/share/dict/words 中。) 例如,假设您忘记了如何拼写单词 fuchsia。其中是否包含 sh 或 cs 呢?您所知道的只是,它以 fu 开头并以 ia 结尾。 尝试使用这个模式进行搜索: $ egrep -i '^fu.*ia$' /usr/dict/words -i 标志表示在搜索过程中不区分大小写。在这个示例中,因为 fuchsia 拼写正确,所以在返回的单词中包括这个单词。 根据长度匹配行 使用大括号元字符 ({ }) 指定前面的正则表达式匹配多少次,如表 1 所示。当您将它们添加到刚才介绍的整行搜索中时,您可以指定行的长度。 表 1. 大括号元字符的含义 示例 描述 {X} 这个字符对前面的正则表达式匹配 X 次。 {X,} 这个字符对前面的正则表达式匹配 X 或更多 次。 {X,Y} 这个字符对前面的正则表达式匹配至少 X 而不超过 Y 次。 并不是所有扩展正则表达式的实现都支持大括号。此外,根据具体的实现,您可能需要先使用反斜杠对其进行转义。 您可以使用这个正则表达式得到字典中以单词长度为顺序的报告。所获得结果的数目取决于本地系统的字典文件中单词的数目,然而,它应该与清单 1 所示类似。在这个示例中,最常见的单词长度是 9 个字母,该字典中有 32,380 个匹配单词。该字典中不包括 25 个字母或更长的单词,并且最长的单词并不是您认为的 21 个字母长的 disestablishmentarian(有 81 个同样长度的单词,包括 superincomprehensible 和 phoneticohieroglyphic),这个 UNIX 字典中最长的单词有 5 个,包括 pathologicopsychological。 清单 1. 计算字典中 X 个字母的单词的个数 $ for i in `seq 1 32` { echo "There are" `egrep '^.{'$i'}$' /usr/dict/words \ | wc -l` "$i-letter words in the dictionary." } There are 52 1-letter words in the dictionary. There are 155 2-letter words in the dictionary. There are 1351 3-letter words in the dictionary. There are 5110 4-letter words in the dictionary. There are 9987 5-letter words in the dictionary. There are 17477 6-letter words in the dictionary. There are 23734 7-letter words in the dictionary. There are 29926 8-letter words in the dictionary. There are 32380 9-letter words in the dictionary. There are 30867 10-letter words in the dictionary. There are 26011 11-letter words in the dictionary. There are 20460 12-letter words in the dictionary. There are 14938 13-letter words in the dictionary. There are 9762 14-letter words in the dictionary. There are 5924 15-letter words in the dictionary. There are 3377 16-letter words in the dictionary. There are 1813 17-letter words in the dictionary. There are 842 18-letter words in the dictionary. There are 428 19-letter words in the dictionary. There are 198 20-letter words in the dictionary. There are 82 21-letter words in the dictionary. There are 41 22-letter words in the dictionary. There are 17 23-letter words in the dictionary. There are 5 24-letter words in the dictionary. There are 0 25-letter words in the dictionary. There are 0 26-letter words in the dictionary. There are 0 27-letter words in the dictionary. There are 0 28-letter words in the dictionary. There are 0 29-letter words in the dictionary. There are 0 30-letter words in the dictionary. There are 0 31-letter words in the dictionary. There are 0 32-letter words in the dictionary. $ 匹配单词 围绕字符 \ 和 \ 是非常有用的模式构造器:它们将要匹配的整个单词 括起来,这表示,它们不会匹配带括号的模式,除非该模式本身就是一个单词。单词 定义为两侧由非单词字符描述的、任意数目组成单词的字符(数字、字母和下划线字符)。非单词字符包括下面的所有字符: •行首 •空白字符 •标点符号 •行尾 •任何除字母、数字或下划线以外的字符 这些围绕字符可以节省大量的时间,但是它们常常没有被充分地利用,可能是因为并非所有的正则表达式实现都支持它们。如果您的正则表达式实现支持它们,那么您应该逐步养成使用它们的习惯。 将需要单独匹配的单词括起来,如下所示: \system\ 这个示例中的正则表达式不会匹配单词 ecosystem、systemic 或 system/70,也不会匹配模式 system 出现在行中任意位置的那些行,它将仅仅 匹配 system 作为独立的单词出现的那些行。 围绕字符与圆括号中的分组结合在一起,可以用来匹配部分 单词。 要匹配包含以 pre 开头 的单词的那些行,可以使用: \\(pre\).*\ 前面的示例将匹配包含单词 preface 和 preposterous 的行,但不会匹配 spread 或 Dupre。 匹配重复单词 这里介绍一种使用单词围绕字符匹配重复单词的快速方法,重复单词表示一个单词在空格之后再次出现。您还可以使用逆向引用,这是大多数流行的正则表达式实现中的一种递归特性,它可以匹配模式本身的某一部分。(将模式中需要引用的部分使用圆括号括起来,然后使用反斜杠加上需要进行引用的围绕字符编号来调用逆向引用:1 表示第一个圆括号分组,2 表示第二个圆括号分组,依此类推。) 要查找重复的单词,搜索在任意数目的空格之后再次出现该单词的情况,可以通过对第一个使用圆括号的部分进行逆向引用来实现: (\.*\)( )+\1 这个示例匹配缩写形式和任何类型的单词,但是它不会匹配由标点符号分隔的重复单词,如 It's been a long, long time。 要匹配所有的重复单词,包括由空格和 任意标点符号分隔的重复单词,可以使用下面的表达式: (\.*\).?( )+\1 如果需要对这些正则表达式使用 grep,则务必使用 -i 标志,以便在搜索中不区分大小写。 匹配小时 让我们再来看另外一类常见的问题:时间和日期。这里介绍了一些设计匹配正确模式的正则表达式所需要考虑的事项。 您无法搜索任何两位的数字来匹配分钟和秒,因为它们仅仅是从 0 到 59,要匹配它们,您需要使用方括号将表示十位和个位的范围括起来: •要匹配标准的 12 或 24 小时格式的小时,可以使用下面的表达式: (( ? )|( )):( )(: )? •要匹配 12 小时 AM/PM 格式、带或不带秒数的时间,甚至匹配大写或小写、不带后缀 AM 或 PM 标识符的时间,可以使用下面的表达式: ( )( ? ){1}(((:( ){1}( ){1}){1,2})|(( )?( M)|( m)))? 如果在上一个示例中没有开始的否定语句,它将匹配不带冒号的时间,这将取决于输入数据,可能会匹配中波广播电台(在美国称为调幅 AM 电台),如 1450 AM。 匹配月份 匹配 12 个月中的任何月份需要一个使用 | 操作符进行分隔的列表,但有时会使用不同的方式对日期进行缩写: •要查找完整拼写或三字母缩写的 12 个月份,可以使用下面的表达式(位于一行): Jan(uary)?|Feb(uary)?|Mar(ch)?|Apr(il)?|May|Jun(e)?|Jul(y)?| Aug(ust)?|Sep(tember)?|Oct(ober)?|Nov(ember)?|Dec(ember)? •您可以加以想象并搜索完整拼写或三字母缩写的变形,即仅当后面紧跟着一个空格或点号的情况,可以使用下面的表达式(位于一行): Jan(uary| |\.)|Feb(uary| |\.)|Mar(ch| |\.)|Apr(il| |\.)|May( |\.)|Jun(e| |\.)|Jul(y| |\ .)|Aug(ust| |\.)|Sep(tember| |\.)|Oct(ober| |\.)|Nov(ember| |\.)|Dec(ember| |\.) 请注意,在上面的这两个示例中,May 是一个特殊的例外。在所有的月份中,它是唯一的完整拼写与三字母缩写相同的月份,所以成功的匹配必须包含这两种变形中的任何一种 作为其缩写,因此像“Mayflower”这样的单词不会导致误报。 当匹配模式前面的字符不是空格或行首时,这些示例还是会失败(返回误报的结果)。这不太可能会出现在英语散文中,但是可能出现在程序源代码中,因为其中可能使用了像 NumOct 这样的变量名。 要修复这些问题,可以执行下面的操作: •使用圆括号将整个正则表达式括起来,并在它的前面加上另一个限定符,用于匹配行首或者空格字符,如下所示(位于一行): (^| )(Jan(uary| |\.)|Feb(uary| |\.)|Mar(ch| |\.)|Apr(il| |\.)| May( |\.)|Jun(e| |\.)|Jul(y| |\.)|Aug(ust| |\.)|Sep(tember| | \.)|Oct(ober| |\.)|Nov(ember| |\.)|Dec(ember| |\.)) •另一种完成这个任务的方法是,在该正则表达式的前面加上一个限定符,以匹配非文字数字的字符,如下所示(位于一行): ( )(Jan(uary| |\.)|Feb(uary| |\.)|Mar(ch| |\.)| Apr(il| |\.)|May( |\.)|Jun(e| |\.)|Jul(y| |\.)|Aug(ust| |\.)| Sep(tember| |\.)|Oct(ober| |\.)|Nov(ember| |\.)|Dec(ember| |\.)) 但是仍然存在潜在的问题,对于搜索整篇英文散文,这些示例并不可靠,因为它们可能返回错误的匹配结果,如“Janelle”或“Augury”这样的单词。要修复这个问题,您必须使用单词围绕字符将每个月份括起来。 本文开头提到,正确的正则表达式应该仅返回需要匹配的数据,以便在输入中排除其他不必要的内容。这种措词是经过仔细考虑的,因为对于构建正则表达式来说,这与上下文有关。对于有些情况,前面的示例非常适合,无需添加额外的单词围绕字符。在其他的情况下,可以对其进行相当程度的简化,例如,如果您正在搜索仅包含大写的日期数值数据的日志文件,那么只需要使用像 这样的正则表达式来匹配包含月份名称的行。 匹配日期 您可以结合一些表 1 所示的数量匹配来匹配日期。 要匹配“month, day, years”,可以使用下面的正则表达式(因为撇号字符是该正则表达式的一部分,所以必须使用双引号将它括起来,如下所示): " {3,10}\.? {1,2}, ( {4}|'? {2})" 这个正则表达式匹配 9 种不同的日期格式: 1.MONTH D, YY 2.MONTH D, 'YY 3.MONTH D, YYYY 4.MON. D, YY 5.MON. D, 'YY 6.MON. D, YYYY 7.MON D, YY 8.MON D, 'YY 9.MON D, YYYY 这个正则表达式的误报包括“Order 99, 99”,要消除这些误报,可以将这个正则表达式与用于月份的正则表达式结合起来,如上所述,以便能够仅匹配实际的月份名称。另外,更改数值范围以避免错误的匹配,并且通过使逗号成为可选项,重复了 18 种可能的格式。 这将得到一个很长的正则表达式。尝试下面的表达式: "( )(Jan(uary| |\.)|Feb(uary| |\.)|Mar(ch| |\.)| Apr(il| |\.)|May( |\.)|Jun(e| |\.)|Jul(y| |\.)|Aug(ust| |\.)| Sep(tember| |\.)|Oct(ober| |\.)|Nov(ember| |\.)| Dec(ember| |\.)) ? {1}(,)? ( {4}|'? {2})" 同样,根据您的需要仔细设计正则表达式。匹配模式通常比较容易,这是因为它存在于特定输入的上下文中,而不是因为它可能独立于数据集而存在。后代人将会发现,前面那个很长的正则表达式中仍然存在 Y10K 错误,因为它能匹配的最大可能的年份为 9999。 匹配整数 正如您在前几个示例中看到的,使用方括号中的范围可以很好地匹配数值。 要匹配任意长度的整数,可以在数值范围后面加上 +;要包括负值,可以在它的前面加上可选的负号(连字号)匹配: -? + 前面的例子可以匹配 0,因为 0 是指定范围中可选的字符。 对于数值匹配,使用圆括号将某些部分括起来也非常有效。要匹配任意的十进制数值,可以使用包含小数点加上一个或多个数值的可选围绕字符,以此对前面的正则表达式进行扩展: -? +(\. +)? 可以使用方括号指定十进制数值的小数位数。例如,要匹配小数位数为 5 或更多小数位数的正数值,可以使用下面的表达式: +\.( ){5,} 更多实际的匹配 范围加上使用括号括起来的元字符,在查找符合任何特定格式的数值时非常有用。将前面介绍的一些技术结合起来,可以构建匹配各种数据的正则表达式: •要匹配美国的电话号码,可以使用: ((\( {2}\))?\ ?| {2}(?:\-?|\ ?)) {2} ? {4} 这个正则表达式可以匹配美国 15 种格式的电话号码: 1.(NPA) PRE-SUFF 2.(NPA) PRE SUFF 3.(NPA) PRESUFF 4.(NPA)PRE-SUFF 5.(NPA)PRE SUFF 6.(NPA)PRESUFF 7.NPA PRE-SUFF 8.NPA PRE SUFF 9.NPA PRESUFF 10.NPAPRE-SUFF 11.NPAPRE SUFF 12.NPAPRESUFF 13.PRE-SUFF 14.PRE SUFF 15.PRESUFF 它还可以匹配美国免费 WATS 号码,尽管 1-800 的“1-”前缀或其他的免费号码不是匹配的一部分,但它本身可以匹配 10 位的数值。对于以 1 或 1+ 开头的美国号码和任意数目的空格,也完全一样,长途电话拨号前缀本身无法匹配,但是只要它后面跟着实际的号码,这个正则表达式就能够将其找出来。 •要匹配两或三位域的电子邮件地址,可以尝试下面的表达式: \ +\@ +?\. {2,3} •要匹配如今所有流行的 URL,可以使用下面的正则表达式: (((http(s)?|ftp|telnet|news)://|mailto:) ]+) 这个表达式可以正常运行,但是匹配 URL 并不像您想象的那么简单。匹配任何可能的 URL 的正则表达式,如 RFC 1738 中的定义,发表在“Regexp for URLs”(请参见参考资料部分)一文中,它非常巨大并且看起来令人生畏。现在应该将它合并为一个 类(如果有用于处理类似数据种类的各种新的类,如 ,那就好了)。 结束语 本文涉及到一些用于编写正则表达式的模式构建技术,以及如何使用它们来完成管理员时常碰到的特定类型数据匹配的工作。在此过程中,向您介绍了大量有价值的实际正则表达式,您可以将它们添加到自己的管理工具库中。 本文来自CSDN博客,转载请标明出处: http://blog.csdn.net/yishengxiao/archive/2008/07/28/2723312.aspx
DNA 离开染色体会怎么样? 几乎细胞内的所有类型的分子都具有信号调节作用。蛋白就不用多说了,胰岛素是激素的典型代表,细胞内的各类蛋白激酶是信号传导最重要的成员,属于蛋白质。各种细胞因子和转录因子是蛋白质和肽,更不要说众多神经肽。脂质的信号也许多,这方面是前列腺素为典型代表的炎症介质。小分子以几种气体为典型,一氧化碳、一氧化氮和硫化氢为代表。各类离子、各类自由基或活性氧。最近发现小 RNA 在细胞内强大的信号作用。物理化学信号,光线、声音、空间位置和震动、摩擦、温度、压迫等等,信号的类型太多了,甚至可以说,存在于细胞内外环境的所有信息都有可能参与细胞功能的调节,都可能属于信号。 染色体中的 DNA 是负责基因信息储存的,是一种具有高度特定职能的信息分子。沃森克里克因为提出 DNA 是遗传物质和双螺旋结构而获得诺贝尔医学生理学奖。 DNA 可以说是家喻户晓的明星分子了。 上述背景下,我思考的问题是,既然细胞内所有的分子都可以是信号分子,小 RNA 是重要的信号分子,那么小 DNA 是否也是一种信号分子。什么时候有小 DNA ?我不清楚正常细胞内会不会出现小 DNA 。但在被病毒感染的细胞内肯定可以出现 DNA 。这种 DNA 是否具有信号作用,肯定可以有。有一些人,例如一些自身免疫性疾病患者身体内, DNA 是可以作为一种抗原被免疫细胞识别,这显然就是一种信号现象,被免疫细胞识别意味着可以被其他细胞识别,被识别就是被信号。在组织细胞受到伤害的时候,细胞核内释放出自身的 DNA 片断,这些小片断会不会对自身或其他细胞产生信号影响,会不会成为身体的致病因子。组蛋白可以作为一种促进炎症发生的因素,那么 DNA 片断也有可能具备类似的性质。我认为这种可能是非常大的,甚至也许是非常重要的。 如果能证明这个现象,应该可以发表在 CNS 上没有问题。简单的方法是将一些细胞的 DNA 进行纯化和切割,然后注射到动物身体内,看是否能产生一些影响。如果有,那么就可以确定这种影响的细节,也就可以确定这种现象。
动物的运动通常是复杂和没有规律的。肌肉在动物运动中的关键作用困扰了科学家超过 300 年之久。虽然如此,新兴的技术和方法一直在影响着这个领域。例如,声纳微测量法和超声技术为在体条件下量化肌肉长度变化提供了重要支持。随着计算工具的发展,机器人技术和肌骨模型取得重大进展,这使得我们可以模拟在现实状态下的肌腱动力学,从而增进我们对于运动相关的肌肉功能的了解。尤其在过去的十年内,技术突飞猛进,肌肉功能相关的研究不断深入。另外,目前研究焦点集中的肌肉功能与复杂运动行为相关,而非相对简单和稳定的运动状态相关。 5 月 27 日出版的英国皇家学会哲学会刊 B (Philosophical Transactions B),作为“产生和控制运动的肌肉功能集成”专题,探讨与不同运动行为相关的肌肉功能,这些运动包括游、跳、跑、飞等。行走和奔跑的研究与人体运动和体育的临床方面密切相关。这一专题的研究包含从人到昆虫不同物种,另外,还有几篇论文关注于复杂行为下神经肌肉控制和调节的最新进展。最后,这些研究与生物力学建模和动力假肢的最新进展相关。本专题有望为将来的神经肌肉力学和运动领域研究工作提供基础。 http://rstb.royalsocietypublishing.org/content/366/1570.toc Richard L. Lieberand Samuel R. Ward Skeletal muscle design to meet functional demands Skeletal muscles are length- and velocity-sensitive force producers, constructed of a vast array of sarcomeres. Muscles come in a variety of sizes and shapes to accomplish a wide variety of tasks. How does muscle design match task performance? In this review, we outline muscle's basic properties and strategies that are used to produce movement. Several examples are provided, primarily for human muscles, in which skeletal muscle architecture and moment arms are tailored to a particular performance requirement. In addition, the concept that muscles may have a preferred sarcomere length operating range is also introduced. Taken together, the case is made that muscles can be fine-tuned to perform specific tasks that require actuators with a wide range of properties. Timothy E. Highamand Andrew A. Biewener Functional and architectural complexity within and between muscles: regional variation and intermuscular force transmission Over the past 30 years, studies of single muscles have revealed complex patterns of regional variation in muscle architecture, activation, strain and force. In addition, muscles are often functionally integrated with other muscles in parallel or in series. Understanding the extent of this complexity and the interactions between muscles will profoundly influence how we think of muscles in relation to organismal function, and will allow us to address questions regarding the functional benefits (or lack thereof) and dynamics of this complexity under in vivo conditions. This paper has two main objectives. First, we present a cohesive and integrative review of regional variation in function within muscles, and discuss the functional ramifications that can stem from this variation. This involves splitting regional variation into passive and active components. Second, we assess the functional integration of muscles between different limb segments by presenting new data involving in vivo measurements of activation and strain from the medial gastrocnemius, iliotibialis cranialis and iliotibialis lateralis pars preacetabularis of the helmeted guinea fowl ( Numida meleagris ) during level running on a motorized treadmill. Future research directions for both of these objectives are presented. Thomas J. Roberts, Emily M. Abbott, and Emanuel Azizi The weak link: do muscle properties determine locomotor performance in frogs? Muscles power movement, yet the conceptual link between muscle performance and locomotor performance is poorly developed. Frog jumping provides an ideal system to probe the relationship between muscle capacity and locomotor performance, because a jump is a single discrete event and mechanical power output is a critical determinant of jump distance. We tested the hypothesis that interspecific variation in jump performance could be explained by variability in available muscle power. We used force plate ergometry to measure power produced during jumping in Cuban tree frogs ( Osteopilus septentrionalis ), leopard frogs ( Rana pipiens ) and cane toads ( Bufo marinus ). We also measured peak isotonic power output in isolated plantaris muscles for each species. As expected, jump performance varied widely. Osteopilus septentrionalis developed peak power outputs of 1047.0 ± 119.7 W kg −1 hindlimb muscle mass, about five times that of B. marinus (198.5 ± 54.5 W kg −1 ). Values for R. pipiens were intermediate (543.9 ± 96.2 W kg −1 ). These differences in jump power were not matched by differences in available muscle power, which were 312.7 ± 28.9, 321.8 ± 48.5 and 262.8 ± 23.2 W kg −1 muscle mass for O. septentrionalis , R. pipiens and B. marinus , respectively. The lack of correlation between available muscle power and jump power suggests that non-muscular mechanisms (e.g. elastic energy storage) can obscure the link between muscle mechanical performance and locomotor performance. Andrew A. Biewener Muscle function in avian flight: achieving power and control Flapping flight places strenuous requirements on the physiological performance of an animal. Bird flight muscles, particularly at smaller body sizes, generally contract at high frequencies and do substantial work in order to produce the aerodynamic power needed to support the animal's weight in the air and to overcome drag. This is in contrast to terrestrial locomotion, which offers mechanisms for minimizing energy losses associated with body movement combined with elastic energy savings to reduce the skeletal muscles' work requirements. Muscles also produce substantial power during swimming, but this is mainly to overcome body drag rather than to support the animal's weight. Here, I review the function and architecture of key flight muscles related to how these muscles contribute to producing the power required for flapping flight, how the muscles are recruited to control wing motion and how they are used in manoeuvring. An emergent property of the primary flight muscles, consistent with their need to produce considerable work by moving the wings through large excursions during each wing stroke, is that the pectoralis and supracoracoideus muscles shorten over a large fraction of their resting fibre length (33–42%). Both muscles are activated while being lengthened or undergoing nearly isometric force development, enhancing the work they perform during subsequent shortening. Two smaller muscles, the triceps and biceps, operate over a smaller range of contractile strains (12–23%), reflecting their role in controlling wing shape through elbow flexion and extension. Remarkably, pigeons adjust their wing stroke plane mainly via changes in whole-body pitch during take-off and landing, relative to level flight, allowing their wing muscles to operate with little change in activation timing, strain magnitude and pattern. Douglas A. Symeand Robert E. Shadwick Red muscle function in stiff-bodied swimmers: there and almost back again Fishes with internalized and endothermic red muscles (i.e. tunas and lamnid sharks) are known for a stiff-bodied form of undulatory swimming, based on unique muscle–tendon architecture that limits lateral undulation to the tail region even though the red muscle is shifted anteriorly. A strong convergence between lamnid sharks and tunas in these features suggests that thunniform swimming might be evolutionarily tied to this specialization of red muscle, but recent observations on the common thresher shark ( Alopias vulpinus ) do not support this view. Here, we review the fundamental features of the locomotor systems in lamnids and tunas, and present data on in vivo muscle function and swimming mechanics in thresher sharks. These results suggest that the presence of endothermic and internalized red muscles alone in a fish does not predict or constrain the swimming mode to be thunniform and, indeed, that the benefits of this type of muscle may vary greatly as a consequence of body size. Maarten F. Bobbertand L. J. Richard Casius Spring-like leg behaviour, musculoskeletal mechanics and control in maximum and submaximum height human hopping The purpose of this study was to understand how humans regulate their ‘leg stiffness’ in hopping, and to determine whether this regulation is intended to minimize energy expenditure. ‘Leg stiffness’ is the slope of the relationship between ground reaction force and displacement of the centre of mass (CM). Variations in leg stiffness were achieved in six subjects by having them hop at maximum and submaximum heights at a frequency of 1.7 Hz. Kinematics, ground reaction forces and electromyograms were measured. Leg stiffness decreased with hopping height, from 350 N m −1 kg −1 at 26 cm to 150 N m −1 kg −1 at 14 cm. Subjects reduced hopping height primarily by reducing the amplitude of muscle activation. Experimental results were reproduced with a model of the musculoskeletal system comprising four body segments and nine Hill-type muscles, with muscle stimulation STIM( t ) as only input. Correspondence between simulated hops and experimental hops was poor when STIM( t ) was optimized to minimize mechanical energy expenditure, but good when an objective function was used that penalized jerk of CM motion, suggesting that hopping subjects are not minimizing energy expenditure. Instead, we speculated, subjects are using a simple control strategy that results in smooth movements and a decrease in leg stiffness with hopping height. Edith M. Arnoldand Scott L. Delp Fibre operating lengths of human lower limb muscles during walking Muscles actuate movement by generating forces. The forces generated by muscles are highly dependent on their fibre lengths, yet it is difficult to measure the lengths over which muscle fibres operate during movement. We combined experimental measurements of joint angles and muscle activation patterns during walking with a musculoskeletal model that captures the relationships between muscle fibre lengths, joint angles and muscle activations for muscles of the lower limb. We used this musculoskeletal model to produce a simulation of muscle–tendon dynamics during walking and calculated fibre operating lengths (i.e. the length of muscle fibres relative to their optimal fibre length) for 17 lower limb muscles. Our results indicate that when musculotendon compliance is low, the muscle fibre operating length is determined predominantly by the joint angles and muscle moment arms. If musculotendon compliance is high, muscle fibre operating length is more dependent on activation level and force–length–velocity effects. We found that muscles operate on multiple limbs of the force–length curve (i.e. ascending, plateau and descending limbs) during the gait cycle, but are active within a smaller portion of their total operating range. Alan Wilsonand Glen Lichtwark The anatomical arrangement of muscle and tendon enhances limb versatility and locomotor performance The arrangement of muscles and tendons has been studied in detail by anatomists, surgeons and biomechanists for over a century, and the energetics and mechanics of muscle contraction for almost as long. Investigation of how muscles function during locomotion and the relative length change in muscle fibres and the associated elastic tendon has, however, been more challenging. In recent years, novel in vivo measurement methods such as ultrasound and sonomicrometry have contributed to our understanding of the dynamics of the muscle tendon unit during locomotion. Here, we examine both published and new data to explore how muscles are arranged to deliver the wide repertoire of locomotor function and the trade-offs between performance and economy that result. James M. Wakeling, Ollie M. Blake, Iris Wong, Manku Rana, and Sabrina S. M. Lee Movement mechanics as a determinate of muscle structure, recruitment and coordination During muscle contractions, the muscle fascicles may shorten at a rate different from the muscle-tendon unit, and the ratio of these velocities is its gearing. Appropriate gearing allows fascicles to reduce their shortening velocities and allows them to operate at effective shortening velocities across a range of movements. Gearing of the muscle fascicles within the muscle belly is the result of rotations of the fascicles and bulging of the belly. Variable gearing can also occur as a result of tendon length changes that can be caused by changes in the relative timing of muscle activity for different mechanical tasks. Recruitment patterns of slow and fast fibres are crucial for achieving optimal muscle performance, and coordination between muscles is related to whole limb performance. Poor coordination leads to inefficiencies and loss of power, and optimal coordination is required for high power outputs and high mechanical efficiencies from the limb. This paper summarizes key studies in these areas of neuromuscular mechanics and results from studies where we have tested these phenomena on a cycle ergometer are presented to highlight novel insights. The studies show how muscle structure and neural activation interact to generate smooth and effective motion of the body. Jinger S. Gottschalland T. Richard Nichols Neuromuscular strategies for the transitions between level and hill surfaces during walking Despite continual fluctuations in walking surface properties, humans and animals smoothly transition between terrains in their natural surroundings. Walking transitions have the potential to influence dynamic balance in both the anterior–posterior and medial–lateral directions, thereby increasing fall risk and decreasing mobility. The goal of the current manuscript is to provide a review of the literature that pertains to the topic of surface slope transitions between level and hill surfaces, as well as report the recent findings of two experiments that focus on the neuromuscular strategies of surface slope transitions. Our results indicate that in anticipation of a change in surface slope, neuromuscular patterns during level walking prior to a hill are significantly different from the patterns during level walking without the future change in surface. Typically, the changes in muscle activity were due to co-contraction of opposing muscle groups and these changes correspond to modifications in head pitch. In addition, further experiments revealed that the neck proprioceptors may be an initial source of feedback for upcoming surface slope transitions. Together, these results illustrate that in order to safely traverse varying surfaces, transitions strides are functionally distinct from either level walking or hill walking independently. Monica A. Daleyand Andrew A. Biewener Leg muscles that mediate stability: mechanics and control of two distal extensor muscles during obstacle negotiation in the guinea fowl Here, we used an obstacle treadmill experiment to investigate the neuromuscular control of locomotion in uneven terrain. We measured in vivo function of two distal muscles of the guinea fowl, lateral gastrocnemius (LG) and digital flexor-IV (DF), during level running, and two uneven terrains, with 5 and 7 cm obstacles. Uneven terrain required one step onto an obstacle every four to five strides. We compared both perturbed and unperturbed strides in uneven terrain to level terrain. When the bird stepped onto an obstacle, the leg became crouched, both muscles acted at longer lengths and produced greater work, and body height increased. Muscle activation increased on obstacle strides in the LG, but not the DF, suggesting a greater reflex contribution to LG. In unperturbed strides in uneven terrain, swing pre-activation of DF increased by 5 per cent compared with level terrain, suggesting feed-forward tuning of leg impedance. Across conditions, the neuromechanical factors in work output differed between the two muscles, probably due to differences in muscle–tendon architecture. LG work depended primarily on fascicle length, whereas DF work depended on both length and velocity during loading. These distal muscles appear to play a critical role in stability by rapidly sensing and responding to altered leg–ground interaction. Simon Sponberg, Andrew J. Spence, Chris H. Mullens, and Robert J. Full A single muscle's multifunctional control potential of body dynamics for postural control and running A neuromechanical approach to control requires understanding how mechanics alters the potential of neural feedback to control body dynamics. Here, we rewrite activation of individual motor units of a behaving animal to mimic the effects of neural feedback without concomitant changes in other muscles. We target a putative control muscle in the cockroach, Blaberus discoidalis (L.), and simultaneously capture limb and body dynamics through high-speed videography and a micro-accelerometer backpack. We test four neuromechanical control hypotheses. We supported the hypothesis that mechanics linearly translates neural feedback into accelerations and rotations during static postural control. However, during running, the same neural feedback produced a nonlinear acceleration control potential restricted to the vertical plane. Using this, we reject the hypothesis from previous work that this muscle acts primarily to absorb energy from the body. The conversion of the control potential is paralleled by nonlinear changes in limb kinematics, supporting the hypothesis that significant mechanical feedback filters the graded neural feedback for running control. Finally, we insert the same neural feedback signal but at different phases in the dynamics. In this context, mechanical feedback enables turning by changing the timing and direction of the accelerations produced by the graded neural feedback. Simon Sponberg, Thomas Libby, Chris H. Mullens, and Robert J. Full Shifts in a single muscle's control potential of body dynamics are determined by mechanical feedback Muscles are multi-functional structures that interface neural and mechanical systems. Muscle work depends on a large multi-dimensional space of stimulus (neural) and strain (mechanical) parameters. In our companion paper, we rewrote activation to individual muscles in intact, behaving cockroaches ( Blaberus discoidalis L.), revealing a specific muscle's potential to control body dynamics in different behaviours. Here, we use those results to provide the biologically relevant parameters for in situ work measurements. We test four hypotheses about how muscle function changes to provide mechanisms for the observed control responses. Under isometric conditions, a graded increase in muscle stress underlies its linear actuation during standing behaviours. Despite typically absorbing energy, this muscle can recruit two separate periods of positive work when controlling running. This functional change arises from mechanical feedback filtering a linear increase in neural activation into nonlinear work output. Changing activation phase again led to positive work recruitment, but at different times, consistent with the muscle's ability to also produce a turn. Changes in muscle work required considering the natural sequence of strides and separating swing and stance contributions of work. Both in vivo control potentials and in situ work loops were necessary to discover the neuromechanical coupling enabling control. Jared Markowitz, Pavitra Krishnaswamy, Michael F. Eilenberg, Ken Endo, Chris Barnhart, and Hugh Herr Speed adaptation in a powered transtibial prosthesis controlled with a neuromuscular model Control schemes for powered ankle–foot prostheses would benefit greatly from a means to make them inherently adaptive to different walking speeds. Towards this goal, one may attempt to emulate the intact human ankle, as it is capable of seamless adaptation. Human locomotion is governed by the interplay among legged dynamics, morphology and neural control including spinal reflexes. It has been suggested that reflexes contribute to the changes in ankle joint dynamics that correspond to walking at different speeds. Here, we use a data-driven muscle–tendon model that produces estimates of the activation, force, length and velocity of the major muscles spanning the ankle to derive local feedback loops that may be critical in the control of those muscles during walking. This purely reflexive approach ignores sources of non-reflexive neural drive and does not necessarily reflect the biological control scheme, yet can still closely reproduce the muscle dynamics estimated from biological data. The resulting neuromuscular model was applied to control a powered ankle–foot prosthesis and tested by an amputee walking at three speeds. The controller produced speed-adaptive behaviour; net ankle work increased with walking speed, highlighting the benefits of applying neuromuscular principles in the control of adaptive prosthetic limbs.
研究人员从水稻籼稻品种93-11中克隆并鉴定了控制水稻籼粳分类的基因并将其命名为PHR1。转基因功能互补实验证明PHR1是区分水稻籼粳分类的基因。在水稻中抑制或过量表达PHR1,得到具不同抗病虫害能力的转基因水稻,表明可以利用基因工程技术调控该基因从而调节植物抗性。 Yanchun Yu,Tian Tang, Qian Qian, YonghongWang,Meixian Yan,Dali Zeng, Bin Han, Chung-IWu,Suhua Shi, and Jiayang Lia,Independent Losses of Function in a Polyphenol Oxidase in Rice: Differentiation in Grain Discoloration between Subspecies and the Role of Positive Selection under Domestication.The Plant Cell, 2008.Vol. 20: 2946–2959, Phenol reaction phenotype(PHR)表现在籼稻中,而在粳稻中缺失,籼稻和粳稻在收获时通常都是金黄色,因此籼稻经过phenol处理会变成褐色或者在储存的过程中会变身;粳稻则不会变色。并且PHR是由单个gene控制,phr1 gene是引起PHR的原因。paper中phr1 gene的clone过程如下: 1、初步定位:应用PHR-positive indica cv MH63 和PHR-negative japonica cv CJ06 构建一个非常大的作图群体,杂交得到5589个F2群体(分离比3:1;PHR-positive4203:PHR-negative 1386)。前期研究phr1定位在4号染色体,应用新的PCR-based marker S100与S115在水稻遗传图谱phr1的两端。然后应用这两个标记扫描所有的PHR-negative 植株。phr1 gene定位到S100和S115之间,遗传距离9.3cM 与8.5cM之间。 2、精细定位:获得66个phr1与S100之间的重组个体以及40个phr1与S115之间的重组个体。
信号转导子和转录激活子3(Signal Transducer and Activator of Transcription 3 ,STAT3)是一种存在于细胞浆与酪氨酸磷酸化信号通道偶联的双功能蛋白,是STATs七个家族成员之一。多种肿瘤细胞中STAT3均有异常高表达,STAT3过度激活导致细胞的异常增殖和凋亡障碍,促进肿瘤的形成、发展。STAT3信号通道可能成为肿瘤基因治疗的一个新的作用靶位。针对STAT3的阻断治疗的研究成为近年研究的热点,本文试就此作一综述。 1.STAT3简介 1.1.STAT3结构 有关于STAT3结构及各部位相应的功能有国外文献详细介绍 。其中SH2区是STATs结构中最保守的部分。通过识别已激活受体特定的SH2结构域向受体集聚;激活JAK家族;参与STATs同源或异源二聚体的形成,在信号转导中起重要功能。与二聚体形成有关的705位关键酪氨酸即位于SH2区附近 。STAT3羧基端转录激活区参与转录复合物的形成,其最大转录活性的发挥受727位丝氨酸磷酸化水平的调节 。 1.2.STAT3蛋白功能 STAT3最初是作为一种急性期反应因子被发现,由IL-6激活。STAT3在多种组织中都有表达。STAT3基因缺陷小鼠在胚胎早期即会发生死亡,STAT3缺陷的T细胞失去了IL-6诱导的增殖反应;STAT3无效的乳腺细胞周期性更新的程序化死亡明显延迟;鼠缺乏STAT3的肝实质细胞其IL-6诱导急性期反应基因的能力缺失 。表明STAT3参与了正常细胞的存活、增殖、凋亡等重要活动。 细胞因子等配体与细胞表面相应的受体结合后,诱发了受体的集聚和二聚化。缺乏内在酪氨酸激酶活性的受体如IL-6家族受体等聚集胞浆内的Janus激酶(JAK)家族成员,使其发生自身磷酸化而激活,继而磷酸化受体胞浆区的酪氨酸残基,使受体的构象发生改变,共同形成STAT3识别的SH2结构域,招募胞浆中相应的STATs成员与之结合。在JAK激酶的作用下,结合的STAT3单体705位酪氨酸发生磷酸化并通过SH2区的相互作用而形成同源或异源的二聚体。激活的二聚体接着从受体上解离并转入细胞核内,识别并结合到靶基因DNA特异的反应元件,诱导了抗凋亡基因Bcl-xL、Mcl-l和细胞周期控制基因c-Myc、cyclins D1和VEGF等基因表达 。 具有内在酪氨酸激酶(TK)活性的生长因子受体,如表皮生长因子受体(EGFR)、血小板源性生长因子受体(PDGFR)等可直接磷酸化STAT3蛋白。Src激酶和Ab1及其它如v-ras、Lck等癌蛋白等其他的TK也能直接磷酸化STAT3蛋白 。STATs成员完成特定的信号传递后,被一种未知的酪氨酸磷酸酶去磷酸化,并重新回到细胞质中 。 2.STAT3异常激活与肿瘤 正常信号转导中STATs的激活快速而短暂。STATs持续性激活与细胞的恶性转化进程密切相关 。STAT3是EGFR、IL-6/JAK、Src等多个致癌性酪氨酸激酶信号通道的汇聚的焦点,在多种肿瘤细胞和组织中都有激活,如乳腺癌、卵巢癌、头颈部鳞状细胞癌、前列腺癌、恶性黑色素瘤、多发性骨髓瘤、淋巴瘤、脑瘤、非小细胞性肺癌和各种白血病等 - 。 STAT3激活后诱导某些与细胞增殖、分化、生存、凋亡密切相关的关键基因的异常高表达,通过各种途径促进细胞增殖、恶性转化、阻碍细胞凋亡,表现出致癌的作用。组成性激活的STAT3不需要酪氨酸磷酸化而能够使成纤维细胞发生转化 。而显性负STAT3的表达则可以终止急性髓细胞性白血病以及胃肠基质细胞肿瘤的转化 。JAK2磷酸化抑制剂AG490能够抑制卵巢癌细胞中的STAT3激活,进而抑制肿瘤的生长 。前列腺癌细胞株中STAT3被激活,反义STAT3能够诱发癌细胞凋亡 。由于持续性激活的STAT3能够促使培养细胞发生恶性转化并能在裸鼠中形成肿瘤,STAT3已被认为是一种癌基因 。 3.STAT3阻断治疗及阻断机制 尽管STAT3参与正常细胞因子信号的调节,但是在越来越多的肿瘤细胞中发现STAT3的持续性高表达,而且有证据证实STAT3参与了肿瘤的形成,表明STAT3有可能成为肿瘤治疗的一个新的治疗靶位。在正常鼠成纤维细胞及人口腔角化细胞、乳腺细胞中阻断STAT3信号通道并不影响细胞生长,因此,阻断STAT3途径也许不会过多损伤正常细胞的功能 。针对STAT3信号途径各个阶段不同蛋白或核酸序列可以设计不同的方式对该途径进行阻断,从而抑制肿瘤增殖,或诱导凋亡增加,治疗肿瘤。 3.1 显性负STAT3竞争性抑制 显性负STAT3是指缺失羧基端转录活性区的STAT3突变体蛋白(STAT3β),它能够结合STAT3靶DNA反应元件,但不能促进相应基因的转录,从而与细胞中激活的STAT3竞争结合相应的反应元件,阻断STAT3的信号转导途径。 Guilian Niu在高表达STAT3的鼠黑色素瘤细胞株B16中导入含显性负STAT3的质粒载体,结果诱导了B16细胞的死亡。而在正常鼠成纤维细胞和不表达STAT3的鼠MethA瘤细胞中显性负STAT3对细胞的生长无影响。体内研究也表明显性负STAT3显著的抑制肿瘤的生长。这种抑制增值效应与肿瘤细胞的凋亡增加相关,显性负STAT3下调了抗凋亡基因Bcl-xL的表达 。在人A2058和JW黑色素瘤细胞株中,显性负STAT3也下调了Bcl-xL和Mcl-1表达,诱导细胞凋亡增加 。肿瘤细胞调亡过程中,可能有细胞旁效应的存在 。Burke WM等研究表明显性负STAT3显著的抑制了卵巢癌细胞集落形成能力 。 3.2 STAT3 decay竞争性阻断 STAT3 decoy指一段双链寡核苷酸,它与STAT3靶基因启动子反应元件中STAT3识别的特异性靶DNA序列相一致,在细胞中能够竞争性结合活化的STAT3,减少STAT3与特异性反应元件的结合,从而阻断STAT3信号途径。 Leing PL等针对c-fos启动子中STAT3反应元件,设计了15个碱基的双链STAT3 decoy,用来研究高表达STAT3的头颈部鳞状癌细胞。STAT3 decoy处理的细胞中,STAT3与放射性标记的STAT3结合元件hSIE形成hSIE-STAT3蛋白复合物的能力大大下降,而且这种能力的下降与STAT3的蛋白表达量及其磷酸化水平无关。STAT3 decoy 抑制了头颈部鳞状癌细胞的生长,但对正常口腔角化细胞却没有抑制作用。进一步研究表明STAT3 decoy下调了抗凋亡基因Bcl-xL的表达。他们认为decoy作为肿瘤分子治疗一种方法具有如下的优点:(1)作用的靶转录因子明确;(2)不需要了解靶转录因子的分子结构;(3)decoy 的合成相对比较直接。因此,STAT3 decoy可能成为高表达STAT3肿瘤的一种新的分子治疗策略 。 3.3 反义寡核苷酸阻断 反义寡核苷酸是含12-25个碱基的寡聚核苷酸,能够根据碱基配对原理结合靶mRNA,抑制特异基因的表达,进而研究特定基因生物学功能或者用于治疗相关的疾病。利用反义STAT3对前列腺癌细胞进行研究发现:STAT3转染前列腺癌细胞株DU145细胞,24小时后STAT3蛋白与DNA结合水平显著下降,总STAT3蛋白表达量大量减少,细胞有明显的生长抑制,凋亡细胞数量与对照组相比有三倍的增加 。反义STAT3处理非小细胞性肺癌细胞株A549 和H358,细胞中STAT3的DNA结合能力完全缺失,细胞发生凋亡 。表明反义STAT3可以作为针对高表达STAT3恶性肿瘤的又一分子工具。 3.4 磷酸酪氨酸肽(Phosphotyrosyl Peptides) Turkson J 等针对STAT3的SH2区设计了STAT3 SH2区结合肽,PY*LKTK,其中Y*表示磷酸化的酪氨酸。研究表明该磷酸化的短肽体外以剂量依赖的方式抑制STAT3与DNA结合能力,其同源性的三肽A*YL和PY*L也有类似作用,而非磷酸化的PYLKTK则无此能力。STAT3与短肽形成STAT3YLKTK复合物,从而减少了STAT3:STAT3二聚体激活形式。将PY*LKTK导入细胞,则抑制了细胞中STAT3的激活和转录活性。PY*LKTK也能阻断Src激酶诱导的STAT3依赖性的成纤维细胞的转化。他们的研究表明针对STAT3蛋白特殊结构设计的阻滞剂也能够阻断STAT3的信号通道。 3.5间接阻断 针对STAT3信号途径中上游酪氨酸激酶如JAK、Src、EGFR的抑制剂已经研制成功,部分已进入临床各期试验 。AG490是JAK家族激酶的选择性抑制剂。Burke WM 等利用AG490处理卵巢癌细胞株Caov3和MDAH2774,结果发现STAT3的磷酸化水平和Bcl-xL的表达水平均明显减少,STAT3与DNA特异性的结合能力也下降;细胞的增殖受到抑制,凋亡增加。同时在乳腺癌细胞株MDA-MB-468中,用AG490处理也发现相同现象。进一步对正常卵巢细胞、人皮肤成纤维细胞和正常乳腺细胞的研究表明,用AG490作用后,细胞的增殖和凋亡不受影响。AG490能够抑制何杰金氏瘤中的STAT3激活,进而抑制肿瘤的生长 。在多形性恶性胶质瘤中AG490抑制了STAT3的激活并减少了Bcl-xL, Bcl-2和Mcl-1的表达,细胞的增殖受到抑制 。因此,AG490能够显著的抑制肿瘤细胞的生长,诱导肿瘤细胞的凋亡,而对正常细胞不产生明显的毒性作用,有望成为肿瘤分子治疗的新的治疗药物。 AG490及EGFR特异性抑制剂PD158780对黑色素瘤细胞株JW和A2058中STAT3与DNA结合能力没有抑制作用,对细胞也没有明显的生长抑制作用。而另外两种能够抑制Src激酶的抑制剂PD166285 和PD180970则以剂量依赖的方式抑制了STAT3的DNA结合活性和瘤细胞的生长,并且抑制了抗凋亡基因Bcl-xL和Mcl-l的表达,增加了肿瘤细胞的凋亡。进一步研究表明在黑色素瘤细胞中STAT3的激活与Src 激酶相关,与JAK和EGFR关系不大 。因此,Src激酶抑制剂也能够用于黑色素瘤等依赖Src-STAT3途径异常激活的肿瘤治疗。 4.结语与展望 Stat 3信号通道的过度激活破坏了正常细胞的增殖、生存活动,能够诱导出某些转化细胞的特性;过表达的STAT3调节了细胞周期的调控和凋亡,表明STAT3的激活可能与致癌作用有关系,阻断STATs信号通路的也许能够预防和治疗人类肿瘤。目前针对STAT3途径的分子治疗研究已经取得了很大的进展。下一步的研究也许能找出其它STAT3调节的基因,进一步揭示STAT3在致癌中的作用,寻找阻断STAT3作用靶位治疗癌症的新的分子途径。另外,对目前各种可选择的阻断STAT3信号通道的各种方法进一步进行评价、筛选、综合,选择最优的阻断方法;将分子治疗与传统的放化疗结合进一步研究挑选出有效、低价易于实施的治疗药物和方法,也许是今后的研究方向之一。 Rho蛋白 百科名片 Rho蛋白属于小G蛋白超家族的亚家族成员,到目前为止,已发现了20多个Rho家族成员(图7—1)。根据序列的同源程度和功能,将其分为RhoA、Racl、Cdc42及缺乏GTP酶活性等四大类。 Rho belongs to the Ras super family of low molecular weight GTPases. Fifteen Rho proteins have already been characterized a n d divided into three sub-families; the first includes Rho (A, B, C), the second, Rnd 1-3 a n d the third which includes Rac 1-3, RhoG, Cdc42Hs, Rho/TTF. TC10 a n d Chp (1-2). Rho acts as a molecular switch which turns on of off various intracellular signaling pathways such as ACK, PAKs, MEKKs ROCK (3). Rho is active when bound to GTP a n d inactive when bound to GDP (4). It is also known to participate in many physiological activities including cell migration, adhesion, cytokinesis, proliferation, differentiation a n d apoptosis a n d to a greater extend cell transformation (5). Rho蛋白 Rho家族蛋白是Ras超家族中最早被克隆出来的蛋白,它们是一组相对分子质量大约为20~25kD的三磷酸鸟苷(guanosine triphosphate,GTP)结合蛋白,具有GTP酶活性,因此,习惯被称为Rho GTP酶,Rho GTP酶在细胞骨架重组调控方面起重要作用〔1〕。近年来研究发现,Rho GTP酶在多种恶性肿瘤中高表达,并和肿瘤的发生、侵袭和转移密切相关。本文主要从肿瘤细胞形态改变,细胞与胞外基质粘附以及细胞骨架重组等几个方面,对Rho GTP酶作用于肿瘤侵袭转移的分子调控机制综述如下。 1 Rho GTP酶 到目前为止,Rho GTP酶超家族已发现约20个成员,根据结构和功能不同,大致分为5个亚家族,包括:(1)Rho亚家族,包括RhoA、RhoB和RhoC,在序列上具有高度同源性,并在多种细胞中高表达,主要参与张力纤维形成和粘着斑复合体(focal adhesion complexs,FACs)组装;(2)Rac亚家族:包括Rac1、Rac2、Rac3和RhoG,促进层状伪足和胞膜皱褶形成;(3)Cdc42亚家族,包括Cdc42、TC10、TCL、Wrch1和chp/Wrch2,其中Cdc42促进丝状伪足形成:(4)Rnd亚家族:包括Rnd1、Rnd3/RhoE和Rnd2,在细胞中组成性激活表达并具有不同的组织分布,可拮抗Rho信号通路;(5)Rho BTB亚家族,包括Rho BTB1和Rho BTB2,具体功能尚不清楚。在所有Rho GTP酶超家族成员中,Cdc42、Rac1和RhoA是目前研究最多的Rho GTP酶。Rho家族各成员在氨基酸序列上有50%~55%的同源性,在靠近催化位点处都有1个能和GTP结合的功能区,与催化GTP水解密切相关。Rho GTP酶同Ras超家族的其他成员一样,羧基端通常具有共同结构域,即由半胱氨酸残基,脂族残基和其他氨基酸残基组成的末端,是翻译后修饰的位点〔2〕。Rho GTP酶的翻译后修饰与其质膜定位有关,只有经翻译后修饰的Rho GTP酶才具有活性并能与细胞膜上适宜的脂质分子结合。在异戊烯基转移酶的作用下,半胱氨酸的巯基和异戊二烯基团间共价形成硫醚键,并在内切酶的作用下水解掉末端其余3个残基,最后异戊二烯基化的半胱氨酸残基在甲基转移酶的作用下发生甲基化,完成翻译后的修饰。Rho家族蛋白同Ras超家族的所有成员一样在活性型/GTP限制型和失活型/二磷酸鸟苷(guanosine diphosphate,GDP)限制型构象之间循环。调节这个循环过程的3类重要蛋白是:(1)鸟苷酸交换因子(guaninenucleotide exchanging factors,GEFs),催化GDP的释放和GTP的结合,活化Rho GTP酶。不同的Rho GEF在结构上都具有相同的功能域,包含1个DH(Dbl homology domain)区和1个PH(pleckstrin homologyv domain)区,前者与Rho GTP酶结合并催化其构象改变,后者通过和细胞膜上特定的脂质作用使GEF在膜上定位;(2)GTP酶活化蛋白(GTPase activating protein,GAP),作为负向调节因子加速Rho GTP酶的水解,使Rho GTP酶由活性状态变为无活性状态;(3)GDP解离抑制因子(GDP dissociation inhibitor,GDI),阻止GDP从Rho GTP酶上分离,抑制Rho GTP酶活性。Rho GTP酶是细胞内多条信号转导通路的关键分子,作为分子开关在胞内信号转导中发挥桥梁作用。Rho GTP酶可参与对正常细胞增殖、分化、凋亡的调节,并与肿瘤的发生和转移密切相关。实验研究发现,在多种肿瘤中可见Rho GTP酶表达异常,改变细胞内Rho GTP酶的表达水平可以直接影响肿瘤细胞侵袭和转移的过程。 2Rho GTP酶与肿瘤的侵袭转移 肿瘤细胞在基质中的运动由4个循环往复的步骤组成,即头部伪足的形成和延伸,新粘附位点的建立,胞体的收缩以及尾部的退缩,通过不断重复的4个过程向前迁移〔3〕。对这一过程精确调节的分子机制非常复杂,涉及胞内多条信号转导通路。在多条信号级连反应通路中,Rho GTP酶尤其是RhoA、Rac1和Cdc42是关键的调控因子,主要参与对细胞形态改变,细胞与基质粘附及细胞骨架重组的调控,调节肿瘤细胞的侵袭转移过程〔4〕。 21 细胞形态改变 伪足形成和细胞形态改变是侵袭转移的起始步骤。Rac可诱导质膜突起形成片状样的层状伪足,而Cdc42诱导指头样突起的丝状伪足形成。在高侵袭和转移性的肿瘤细胞,还可见一种侵袭伪足形成,由于与细胞外基质降解密切相关,可能成为主要的伪足结构〔5〕。层状伪足与周围基质形成粘附连接,产生细胞向前运动的锚着位点;丝状伪足有助于细胞对周围环境的适应及确定细胞迁移的方向。WiskottAldrich综合征蛋白家族(WiskottAldrich syndrome protein,WASP)是调节细胞迁移的关键分子,包括神经组织来源WASP(neural WiskottAldrich syndrome protein,NWASP),WASP家族富含脯氨酸同源蛋白1(WASP family verprolinhomologous protein1,WAVE1),WASP家族富含脯氨酸同源蛋白2(WASP familyverprolinhomologous protein2,WAVE2)等成员,也是Rac和Cdc42下游的重要效应子,在肿瘤细胞中高表达,Rac和Cdc42通过活化WASP家族成员诱导伪足形成和基质降解〔6〕。Lorenz等〔7〕首次使用荧光共振能量传感器区分活性状态和失活状态的NWASP构象,并模拟内源性NWASP功能发现,NWASP在迁移的肿瘤细胞头部层状伪足形成中起重要作用。细胞迁移头部高度动态性伪足结构的形成依赖肌动蛋白单体聚合和肌动蛋白纤维的延长,WASP家族不同成员通过不同的结构域与Rac和Cdc42结合而活化,而肌动蛋白相关2/3复合体(actinrelated 2/3 complexs,Arp2/3 complexs)和肌动蛋白单体通过分别结合于活化的WASP家族羧基端共同的结构域,直接调控肌动蛋白单体聚合〔8〕。Arp2/3复合体是肌动蛋白组装的核心,可将肌动蛋白单体从头合成组装为肌动蛋白丝,进而促进丝状伪足和层状伪足的形成〔9〕。Arp2/3复合体与WASP的结合是调控肌动蛋白聚合的重要因素,两者在多种肿瘤细胞中共表达,对115例肺腺癌组织切片免疫组化染色发现,78例(678%)共表达Arp2/3和WAVE2,并与病人临床生存时间负相关;多变量回归分析揭示,Arp2/3和WAVE2的共表达是肿瘤复发的独立危险因素〔10〕。并且NWASP和Arp2/3复合体也是高侵袭和转移性肿瘤细胞侵袭伪足形成的主要调节子,并可能成为肿瘤治疗的重要靶位〔11〕。肌动蛋白单体的聚合和伪足形成还依赖另一种关键调节子cofilin,cofilin可使肌动蛋白单体从肌动蛋白丝的顶端解离,诱导肌动蛋白丝从头部折断,产生新的末端。Rac和Cdc42可通过活化共同的底物p21激活激酶(p21activated kinase,PAK),分别激活LIM(3种同源异型结构域蛋白lin11、isl1和mec3)激酶1(LIM kinase1,LIMK1)和LIM激酶2(LIM kinase2,LIMK2),磷酸化cofilin使其失活而抑制肌动蛋白的解聚,稳定肌动蛋白细胞骨架。 22 细胞基质粘附 伪足形成启动细胞迁移的过程,但细胞持续的迁移需依赖细胞伪足与细胞外基质(extracellular matrix,ECM)的稳定粘附,提供细胞向前迁移的牵引支点。迁移的细胞头部与ECM的粘附和尾部与ECM的去粘附的不断交替使得细胞向前迁移,Rho GTP酶对这一过程发挥精确的调节。细胞表面的整合素受体与ECM中特异的配体结合,通过整合素聚集成簇而形成FACs,而整合素受体的胞内区与桩蛋白(paxillin),纽蛋白(vinculin)和踝蛋白(talin)等多种肌动蛋白结合蛋白相互作用形成分子桥,并与细胞骨架相连,提供细胞迁移的锚着位点。活化的Rac可诱导肌动蛋白的聚合和层状伪足的形成,同时也能诱导新的FACs的形成,而FACs的形成又能反过来活化Rac,这一正反馈的失控可增加肿瘤细胞的侵袭能力〔11〕。Jung〔12〕发现,活化的Rac1和Cdc42,可通过激活PAKl磷酸化下游的粘着斑激酶(focal adhesion kinase,FAK),活化的FAK作为分子支架招募胞浆中桩蛋白,纽蛋白和踝蛋白等至FACs,促进FACs的形成。p65激活激酶还可通过LIMK间接调节cofilin的活性,cofilin在活性型和失活型间的循环可调节肌动蛋白亚单位从肌动蛋白丝末端的解离和聚合,并对促进肌动蛋白纤维组装时踏车(treadmilling)现象的发生非常必要〔3〕。肿瘤细胞侵袭和转移与ECM的降解密切相关,Rho GTP酶可直接或间接调节下游效应子促进ECM的降解。对人乳腺癌细胞株MDAMB435的研究发现,Rac1和Cdc42可通过间接活化LIMKl上调丝氨酸蛋白酶尿激酶型纤溶酶原激活剂(urokinase type plasminogen activator,uPA)系统,增加uPA启动子活性,诱导uPA和uPA受体mRNA和蛋白表达及uPA的分泌,降解ECM胶原等成分,有助于细胞的侵袭转移〔13〕。 23 细胞骨架重组 侵袭和转移的肿瘤细胞的持续运动需依靠张力纤维收缩和肌动蛋白丝的延长提供动力,Rho GTP酶可通过调节细胞骨架的重组,为细胞迁移提供动力。张力纤维是真核细胞中一种稳定的、平行排列的微丝结构,由肌动蛋白、肌球蛋白、原肌球蛋白等组成,肌动肌球蛋白相对运动产生的收缩力是细胞迁移动力的主要来源。Rho及其下游的Rho相关卷曲螺旋形成蛋白激酶(Rho associated coiledcoil forming protein kinase,ROCK)可提升肌球蛋白轻链(myosin light chain,MLC)的磷酸化水平,增加肌动-肌球蛋白的收缩力促使细胞在ECM中的迁移。ROCK是Rho下游的重要效应分子,包括Rho激酶和p160ROCK 2个成员。活化的ROCK通过2条通路提升MLC的磷酸化水平,一方面ROCK磷酸化其底物肌球蛋白轻链磷酸酶(myosin light chain phosphatase,MLCP)的肌球蛋白结合亚单位(myosinbinding subunit,MBS)而抑制MLCP的磷酸酶活性,减少MLC磷酸基团的水解;另一方面,ROCK可直接磷酸化MLC,增加MLC的磷酸化水平,从而增加与肌动蛋白丝交联产生的收缩力。抑制Rho/Rock通路能抑制肿瘤细胞张力纤维的收缩和细胞侵袭,显性激活(dominant active)的p160ROCK的质粒转染的人卵巢癌细胞具有更强的侵袭和迁移能力,而用p160ROCK的反义寡核苷酸处理的癌细胞侵袭和迁移能力可显著减弱〔4〕。Rho还可作用于下游另一重要效应分子mDia(Mammalian Diaphanousrelated protein)蛋白,活化的mDia蛋白可将肌动蛋白单体参入到肌动蛋白丝的末端,并阻止成帽蛋白的结合,诱导肌动蛋白丝的延长,有助于细胞迁移〔15〕。 3 Rho GTP酶在肿瘤侵袭转移诊断和治疗中的意义 由于Rho GTP酶在许多恶性肿瘤中高表达,因此,Rho GTP酶可能成为肿瘤转移的临床诊断指标。对53例胃癌病人和7名胃肿瘤细胞株的Rho超家族7名主要成员RhoA、RhoB、RhoC、Rac1、Rac2、Rac3和Cdc42mRNA表达水平的检测发现,RhoA、Rac1和Cdc42在胃癌组织切片中的平均表达水平显著高于癌旁组织切片,RhoA的表达水平与肿瘤分期显著正相关并和组织分化程度负相关,RhoA和Rac1在7种胃肿瘤细胞株中的mRNA表达水平,总蛋白量及活性都显著高于正常胃粘膜上皮细胞株〔16〕。RhoC在许多恶性肿瘤中高表达,特别是在转移性肿瘤中表达异常增高〔17〕。在原发胃癌细胞中RhoC的表达显著高于正常胃上皮细胞,在有淋巴结转移的原发胃癌中RhoC的表达显著高于没有淋巴结转移的原发癌,在有多个淋巴结转移的原发胃癌中RhoC的表达也显著高于较少淋巴结转移的胃癌细胞,穿过浆膜的胃癌细胞比在胃壁中的胃癌细胞具有更高的RhoC表达,表明RhoC的过表达与肿瘤细胞的高度浸润相关,提示RhoC可作为胃癌病人临床预后的重要指标。鉴于Rho GTP酶与肿瘤转移的相关性,使其可能成为转移性肿瘤临床转移及预后分析的重要指标。由于Rho GTP酶与肿瘤侵袭转移密切相关,Rho GTP酶及其下游靶分子可能成为抑制肿瘤转移的重要靶位。特异性的ROCK抑制剂Wf536可在体内抑制小鼠Lewis肺癌转移及肿瘤细胞诱导的新生毛细血管生成,并在体外抑制肿瘤细胞在基质胶上的侵袭和迁移〔18〕。由于Rho GTP酶翻译后羧基端的修饰对于其正确的膜定位和活化非常重要,因此多种异戊烯基转移酶抑制剂如Zarnestra,Sarasar,L778等〔2〕,通过阻断Rho GTP酶C端翻译后修饰位点的蛋白质法呢基化,已被证实在肿瘤治疗中有较好疗效,而且针对某一种Rho GTP酶(如RhoA、RhoB、Rac1或Cdc42)的特异性异戊烯基转移酶抑制剂将具有更好的临床治疗效果〔19〕。由于针对Rho GTP酶进行的肿瘤治疗能够减少传统抗癌药物的副作用,因此,Rho GTP酶已成为肿瘤药物开发的新靶位,对于肿瘤的临床治疗将具有良好的应用前景。
始终牢记目的性 —— 通往 B 点 说服就是从 A 点到 B , 要从对听众有什么好处( What ’ s IN It For You? )开始 说服:把听众从他们在你开始讲演时所持的立场( A 点)带到你的目标( B 点)上去。而这一动态的转移过程就是说服。 我们的目标就是 —— 从 A 点到 B 点 。 就是 从引领或管理( Lead or manage ) —— 有效管理 (Effective Management) 有效的进行内容管理和创造性的思维 考察一下把听众从 A 点带到 B 点上去面临着什么样的挑战吧。 例如 : 说服性演讲目标 1 影响听众信念,促使听众行动 2 持有立场,设法使听众接受、支持 3 寻找理由、论据,支持自己的观点 A 点是听众的出发点,具有强大的稳定性,在这个点上,听众: 缺少信息 —— 对你及业务知之甚少。 充满疑虑 —— 怀疑并准备质疑你所说的一切。 充满抵触 —— 处在一个与你目标对立的位置上,并想保持它。 要点:要达到 B 点,你必须使缺少信息的听众在你的讲演中开始“理解”;使充满疑虑的听众开始“信任”;使充满抵触的听众开始“行动”。 事实上,“理解”、“信任”、“行动” 并不是三个各不相关的目标。毕竟,你的听众只有首先“ 理解”你的故事并“相信”故事所转达的信息,才能以你所希望的方式“行动”。 你必须学会讲“故事”,讲对你有什么好处 … 方法: —— 以终为始( Starting with the Objects in Sight ) —— 为听众着想( Audience Advocacy ) —— 把注意力从性能( features )转移到好处( banefits )上来 —— 了解听众的需要 为了克服 MEGO 症 ( “五宗罪” ) 我们除了 把握 Less is more 原则 不断地问 WIIFY 即:把注意力从性能转移到好处上来 以终为始 并且可以通过“讲故事”的有效方式来推销自己的观点 同时必须 在讲演准备前充分 “了解听众的需要” 在讲演中不断赢得听众赞同,不断将听众带领到一个高潮,另一个高潮。 让他们欲罢不能。
记得几年前,我在接受新浪网的专访时,曾就包皮环切的问题做了一期访谈。其中对包皮的功能做了简单的介绍(访谈内容详见 http://www.dxyer.cn/andrologist/article/i30527.htm )。近来又有不少患者在门诊向我咨询这个话题,看来大家对于包皮的关注度还是很高的,因此觉得有必要对这个问题专门列个题目详细谈谈,于是就有了下面这篇博文: 包皮是上帝赠给灵长类,尤其人类最特殊而且珍贵的礼物,此礼物据信已在灵长类身体上保留了一亿年以上,既没有退化也没有进化。足见其功能与结构的确历经了千锤百炼,却始终屹立不摇。然而,在某些种族或宗教的文化里,为了顺应他们的社会传承或宗教仪式,在孩提时期或在行成人礼时,却将这个珍贵的礼物切掉作为祭品了。这个上帝的礼物就是包皮!当代,大多数医师尽管承认包皮是经过千万年进化史而被完整保留下来的东西,属于阴茎上的正常结构,但却仍认为包皮容易藏污纳菌、滋生感染,而且分泌的包皮垢易助长子宫颈癌的发生,所以他们多数建议尽早割除包皮。 果真像上面所讲的,包皮一无是处吗?或者因为只能当作某种仪式的图腾,而在功能簿上不能占有一席之地吗?又或者说它仅仅是人类进化史中尚未来得及彻底消亡的无用结构吗? 其实不然!因为到目前为止,它仍不是人体可有可无的痕迹器官(一为阑尾,一为第三臼齿),足见它必然具有一定的功能,只是我们以前把它给忽略了。因此,我想有必要为包皮作一些医学上的平反昭雪才对。 以下我们列举包皮的17项功能,并依其重要性按次序进行排列。 A:性生活 一、 增加性愉悦。系带处的感觉特别敏锐。 二、 在性交或自慰时,包皮内外板皮肤处于滑动状态,有着令人舒服的滚动感(rolling bearing)。 三、 因包皮内外板自身有滑动,减轻了对阴道壁的摩擦力,可避免性交疼痛。 四、 富裕的包皮可刺激伴侣生殖器,获得畅快。 五、 勃起时,提供因阴茎伸长所需的皮肤,避免束缚感。 六、 包皮可以储存费洛蒙(pheromone),且在性唤起时释出,充分调动伴侣的情欲。 七、 包皮可储存自然的润滑液(射精前液),在性兴奋时释出,性生活时起到润滑作用。 八、 性唤起时使龟头成为视觉刺激焦点。 九、 为精液提供一个暂时的容器,以减少在阴道壁上的耗损。 B:保护 十、 保护龟头,避免龟头皮肤过度角质化,保持松软湿润。 十一、保护薄皮的龟头(thin-skinned glans),使其免于受伤。 十二、保护龟头的神经,避免勃起功能受损。 十三、在孩童时,保护尿道口,免于污染或尿道感染。 十四、包皮分泌物中本来就有抗菌的成分,其中比较明确的就有溶菌酶,可发挥杀灭抑制病菌的作用。 十五、保护无色素的龟头,以免晒伤。 十六、保护血流供应本就不足的龟头,以免冻伤。(还记得Sir Ranulph Fiennes跨越北极区时龟头被冻伤的事情吗?) C:其它 十七、提供皮肤,供重建矫形手术使用。(如尿道下裂,眼睑烧伤) 由上述可知,包皮在人类是一种特殊的性感组织(erogenous tissue),如果千古名言饮食男女,人之大欲存焉?是对的话,那保留包皮势必有如羽化而登仙的效果。因此,在性功能研究逐渐成为热门学科之时,我们是否也应该还给包皮一个应有的地位,不要动不动就找理由把包皮给割了! 何况男性接受割包皮后,也常常丧失了珍贵的系带及其它功能,且疤痕处也可能形成神经瘤(Neuroma)。所以,除非万不得已,拙见认为应把包皮环切术的手术指证设定的更严格点,只有在内科治疗无效时,才可考虑。而当要行包皮环切术时,也须带着包皮美容的观念,尽量保留球状感觉接受体,Dartos肌肉、包皮粘膜等,并尽量避免龟头暴露,以免局部皮肤过度角化。 在众多的医学观点里,如澳州小儿外科学会、加拿大小儿医学会及小儿泌尿教科书中,都认为新生儿的龟头及包皮粘膜是一个复杂的融合体,还未发育成熟,更应谨慎是否行包皮环切术;在青少年期,最好也能清楚的告知男孩本人,最好等他们能明白割包皮的利弊得失后才可施行。碰到一些影响到小孩健康的包皮疾病,非开不行时,也须尽量保存包皮的结构及功能。如果医疗质量够高,所有切割下来的包皮都应该送病理检查,确定包皮环切术的适应症是不是抓对了! 当然不只医师要了解包皮的角色及功能,孩子的父母或成年患者本人也须提升对包皮的认知,唯有双管齐下,才能让无辜的包皮遭遇明镜本非台,何事惹尘埃之叹! 【附】包皮环切前后阴茎疲软和勃起状态比较 In order to appreciate the sexual functions of the foreskin, refer to Figures 15, which clarify what the foreskin is and how it works. Figures1 and2 show the difference between a circumcised and an uncircumcised penis in the relaxed or flaccid state. Note that the foreskin serves to cover the glans or head of the penis. Figure3 shows this diagrammatically. Figure 4 shows the circumcised penis in the erect state. The shaft skin is taut. Figure5 shows the uncircumcised penis before, during, and after erection. Note that the inner foreskin layer becomes exposed and the entire foreskin moves to loosely cover the penile shaft. Fig.1 包皮环切后处于疲软状态的的阴茎(Circumcised Penis in the Relaxed State) Fig.2 尚未环切的处于疲软状态的阴茎(Uncircumcised Penis in the Relaxed State) Fig3 包皮内板和外板的关系(Inner and Outer Foreskin Layers) Fig.4 环切后处于勃起状态的阴茎(Erectile Process in the Circumcised Penis) Fig.5 未环切阴茎的勃起过程(Erectile Process in the Uncircumcised Penis)
Endnote自从x2版本实现了可以直接找到全文的功能,很受大家欢迎,但也很多人反馈为什么很多全文明明有权限看却不能够找到全文? Endnote 找全文可以通过以下途径实现 : ISI web of knowledge和全文数据库做的链接(ISI上面的数据是文摘, 全文 字样是因为和全文数据库做了链接,可以直接通过链接到全文数据库下载全文) endnote web服务 DOI Pubmed的linkout链接 open url 因此最大化endnote找全文功能请: 关注是否有使用权限的全文数据库都和ISI做了链接 注册endnote web可以增加找全文的可能性 关注DOI号是否在DOI这个字段下,如果不在想办法归位 不要关闭IE的cookie保存 ps. 以前都在鸿波网开设博客,最近鸿波上不去了,转战到此,希望有老朋友惠顾!
http://www.sciencenet.cn/htmlnews/2009/9/223241.shtm 神经细胞内质网功能机理揭晓 50年谜题得解 瑞士弗雷德里希米歇尔生物医学研究所9月7日发布新闻公告称,该所科学家经过多年潜心研究,终于确定神经管微观网络内质网(ER)调节神经细胞间连接强度的功能机理。这一发现解答了困扰科学家长达50年的谜题,使人类对大脑学习和记忆的认识更深入了一步。相关研究成果发表在美国《国家科学院院刊》( PNAS )网络版上。 突触可塑性,即神经细胞间连接强度可调节的特性,对学习和记忆至关重要。神经细胞上的所有突触是否都具有相同的表达长期可塑性的能力,目前并不是很清楚。突触组织会影响局部信号级联的功能,进而对单个突触的可塑性进行差异性调控。这导致了大脑中神经细胞间突触连接的两种类型:一种连接会不断地形成、增强或减弱;另一些连接会则保持稳定状态,而正是这种状态使我们能够保持某种记忆很多年。 但突触组织的功能机理是怎样的?学界对此认识一直模糊不清。 瑞士弗雷德里希米歇尔生物医学研究所的神经生物学家托马斯奥特内尔带领一小组对CA1锥形神经细胞树突棘中的内质网是如何影响突触后信号的机理进行了研究,终于阐明了这种神经管微观网络的作用:正是神经细胞树突棘中内质网的存在决定了突触连接的稳定与否。这也是自1959年爱德华乔治格雷首次描述神经管微观网络内质网以来,科学家第一次阐明该结构的功能机理。 研究表明,在神经细胞树突棘中,内质网会有目标地选择含有强壮突触的大棘。当神经细胞受到刺激时,含有内质网的棘会释放大量的钙,从而引发突触功能的变化。对这些树突棘的低频刺激,会导致突触效力被长期抑制。相反,在缺乏内质网的棘中就没有这种功能的改变。因此,在同一个神经细胞中,两种类型的突触连接能够并存,并被单独控制。 公告称,奥特内尔的研究小组将下一步目标转到脆性X染色体综合征的研究上。作为最常见的一种遗传性认知障碍,该种病症患者会出现智力下降、学习困难、注意力不集中等问题。奥特内尔指出,该病症患者的神经树突棘会出现异常。他们怀疑,是含内质网的树突棘应激产生的信号级联在患者体内遭到过度刺激,才导致某些症状的出现。 http://www.pnas.org/content/106/35/15055.abstract?sid=da377557-7ade-4062-86a8-1985fc2cfa52 Differential distribution of endoplasmic reticulum controls metabotropic signaling and plasticity at hippocampal synapses Niklaus Holbro , sa Grunditz and Thomas G. Oertner , 1 + Author Affiliations Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland Edited by Roger A. Nicoll, University of California, San Francisco, CA, and approved July 22, 2009 (received for review May 8, 2009) Abstract Synaptic plasticity is considered essential for learning and storage of new memories. Whether all synapses on a given neuron have the same ability to express long-term plasticity is not well understood. Synaptic microanatomy could affect the function of local signaling cascades and thus differentially regulate the potential for plasticity at individual synapses. Here, we investigate how the presence of endoplasmic reticulum (ER) in dendritic spines of CA1 pyramidal neurons affects postsynaptic signaling. We show that the ER is targeted selectively to large spines containing strong synapses. In ER-containing spines, we frequently observed synaptically triggered calcium release events of very large amplitudes. Low-frequency stimulation of these spines induced a permanent depression of synaptic potency that was independent of NMDA receptor activation and specific to the stimulated synapses. In contrast, no functional changes were induced in the majority of spines lacking ER. Both calcium release events and long-term depression depended on the activation of metabotropic glutamate receptors and inositol trisphosphate receptors. In summary, spine microanatomy is a reliable indicator for the presence of specific signaling cascades that govern plasticity on a micrometer scale. long-term depression metabotropic glutamate receptor metaplasticity spine apparatus dendritic spines Footnotes 1 To whom correspondence should be addressed. E-mail: thomas.oertner@fmi.ch Author contributions: N.H. and T.G.O. designed research; N.H. and .G. performed research; N.H. analyzed data; and N.H. and T.G.O. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at 信息分析平台: http://www.gopubmed.org/web/gopubmed/1?WEB0b6tqs2ai913gIgI1I00d000j10040001rl 检索策略:Endoplasmic Reticulum and Nerve Cells and Synapses and Calcium and CA1 相关文献计量分析结果: Top Countries Publications USA 4 Switzerland 1 France 1 Belgium 1 Russia 1 Germany 1 Czech Republic 1 Italy 1 Top Cities Publications Basel 1 Boston 1 North Chicago 1 Gif-sur-Yvette 1 Lawrence 1 Mons 1 Moscow 1 Bethesda 1 Homburg 1 Hradec Krlov 1 Milan 1 Top Journals Publications J Neurosci 2 Proc Natl Acad Sci U S A 1 Nature 1 Pflug Arch Eur J Phy 1 Mol Brain Res 1 J Biol Chem 1 Biofizika+ 1 Neuroscience 1 J Physiol-london 1 Eur J Neurosci 1 1 2 3 ... 13 Top Terms Publications Endoplasmic Reticulum 11 endoplasmic reticulum 11 Synapses 10 Neurons 10 Hippocampus 10 Animals 10 Calcium 9 Dendrites 6 dendrite 6 Rats 6 pyramidal neuron development 5 pyramidal neuron differentiation 5 pyramidal neuron migration 5 intracellular 5 Pyramidal Cells 5 Plastics 4 Ryanodine Receptor Calcium Release Channel 4 ryanodine-sensitive calcium-release channel activity 4 Thapsigargin 4 Ryanodine 4 1 2 3 ... 13 1 2 3 Top Authors Publications Shen J 1 Zhang C 1 Wu B 1 Beglopoulos V 1 Wines-Samuelson M 1 Zhang D 1 Dragatsis I 1 Sdhof T 1 Stutzmann G 1 Chakroborty S 1 Goussakov I 1 Miller M 1 Chameau P 1 Van de Vrede Y 1 Fossier P 1 Baux G 1 Jols M 1 Wang J 1 Kelly P 1 Mackinnon R 1 1 2 3 相关研究报道: Title: Differential distribution of endoplasmic reticulum controls metabotropic signaling and plasticity at hippocampal synapses . PMID: 19706463 Related Articles Authors: Holbro, N , Grunditz, A , Oertner, T G Journal: Proc Natl Acad Sci U S A , 2009 Abstract: Synaptic plasticity is considered essential for learning and storage of new memories. Whether all synapses on a given neuron have the same ability to express long-term plasticity is not well understood. Synaptic microanatomy could affect the function of local signaling cascades and thus differentially regulate the potential for plasticity at individual synapses . Here, we investigate how the presence of endoplasmic reticulum ( ER ) in dendritic spines of CA1 pyramidal neurons affects postsynaptic signaling. We show that the ER is targeted selectively to large spines containing strong synapses . In ER-containing spines, we frequently observed synaptically triggered calcium release events of very large amplitudes. Low-frequency stimulation of these spines induced a permanent depression of synaptic potency that was independent of NMDA receptor activation and specific to the stimulated synapses . In contrast, no functional changes were induced in the majority of spines lacking ER. Both calcium release events and long-term depression depended on the activation of metabotropic glutamate receptors and inositol trisphosphate receptors. In summary, spine microanatomy is a reliable indicator for the presence of specific signaling cascades that govern plasticity on a micrometer scale. Affiliation: Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel , Switzerland . Wikipedia: Calcium , Calcium metabolism , Dendrite , Dendritic spine , Depression , Endoplasmic Reticulum , Ergastoplasm , Glutamate receptor , Government , Inositol , Inositol metabolism , Metabotropic glutamate receptor , N-methyl-D-aspartate , N-methylaspartate , NMDA , Nerve cell , Neuron , Plastic , Receptors, glutamate , Receptors, metabotropic glutamate , Receptors, n-methyl-d-aspartate , Synapse Title: Presenilins are essential for regulating neurotransmitter release. PMID: 19641596 Related Articles Authors: Zhang, C , Wu, B , Beglopoulos, V , Wines-Samuelson, M , Zhang, D , Dragatsis, I , Sdhof, T C , Shen, J Journal: Nature , Vol. 460 (7255): 632-6 , 2009 Abstract: Mutations in the presenilin genes are the main cause of familial Alzheimer's disease. Loss of presenilin activity and/or accumulation of amyloid-beta peptides have been proposed to mediate the pathogenesis of Alzheimer's disease by impairing synaptic function. However, the precise site and nature of the synaptic dysfunction remain unknown. Here we use a genetic approach to inactivate presenilins conditionally in either presynaptic (CA3) or postsynaptic ( CA1 ) neurons of the hippocampal Schaeffer-collateral pathway. We show that long-term potentiation induced by theta-burst stimulation is decreased after presynaptic but not postsynaptic deletion of presenilins. Moreover, we found that presynaptic but not postsynaptic inactivation of presenilins alters short-term plasticity and synaptic facilitation. The probability of evoked glutamate release, measured with the open-channel NMDA ( N-methyl-D-aspartate ) receptor antagonist MK-801, is reduced by presynaptic inactivation of presenilins. Notably, depletion of endoplasmic reticulum Ca(2+) stores by thapsigargin, or blockade of Ca(2+) release from these stores by ryanodine receptor inhibitors, mimics and occludes the effects of presynaptic presenilin inactivation. Collectively, these results indicate a selective role for presenilins in the activity-dependent regulation of neurotransmitter release and long-term potentiation induction by modulation of intracellular Ca(2+) release in presynaptic terminals, and further suggest that presynaptic dysfunction might be an early pathogenic event leading to dementia and neurodegeneration in Alzheimer's disease. Affiliation: Center for Neurologic Diseases, Brigham Women's Hospital, Program in Neuroscience, Harvard Medical School, Boston , Massachusetts 02115, USA . Pubmed MeSH: Animals , Calcium , Cells, Cultured , Gene Expression Regulation , Glutamic Acid , Hippocampus , Mice , Mice, Inbred C57BL , Mice, Knockout , Mice, Transgenic Wikipedia: Alzheimer's Disease , Alzheimer disease , Axon terminal , Cistron , Dementia , Endoplasmic Reticulum , Ergastoplasm , Frontotemporal lobar degeneration , Gene , Genetic material , Long-term potentiation , Long term potentiation , Mutation , N-methyl-D-aspartate , N-methylaspartate , NMDA , Nature , Nerve cell , Neurohormones , Neuromodulator , Neuron , Neurotransmitter , Neurotransmitter agents , Pathogenicity , Peptides , Plastic , Polypeptides , Presenile dementia , Presenilin , Presynaptic terminal , Probabilities , Probability , Receptors, n-methyl-d-aspartate , RyR1 , RyR2 , RyR3 , Ryanodine , Ryanodine receptor , Ryanodine receptor calcium release channel , Semantic Dementia , Senile Dementia , Synaptic bouton , Synaptic terminal , Thapsigargin , Virulence Title: Deviant ryanodine receptor -mediated calcium release resets synaptic homeostasis in presymptomatic 3xTg-AD mice. PMID: 19641109 Related Articles Authors: Chakroborty, S , Goussakov, I , Miller, M B , Stutzmann, G E Journal: J Neurosci , Vol. 29 (30): 9458-70 , 2009 Abstract: Presenilin mutations result in exaggerated endoplasmic reticulum ( ER ) calcium release in cellular and animal models of Alzheimer's disease (AD). In this study, we examined whether dysregulated ER calcium release in young 3xTg-AD neurons alters synaptic transmission and plasticity mechanisms before the onset of histopathology and cognitive deficits. Using electrophysiological recordings and two-photon calcium imaging in young (6-8 weeks old) 3xTg-AD and non-transgenic (NonTg) hippocampal slices, we show a marked increase in ryanodine receptor ( RyR )-evoked calcium release within synapse-dense regions of CA1 pyramidal neurons . In addition, we uncovered a deviant contribution of presynaptic and postsynaptic ryanodine receptor -sensitive calcium stores to synaptic transmission and plasticity in 3xTg-AD mice that is not present in NonTg mice. As a possible underlying mechanism, the RyR2 isoform was found to be selectively increased more than fivefold in the hippocampus of 3xTg-AD mice relative to the NonTg controls. These novel findings demonstrate that 3xTg-AD CA1 neurons at presymptomatic ages operate under an aberrant, yet seemingly functional, calcium signaling and synaptic transmission system long before AD histopathology onset. These early signaling alterations may underlie the later synaptic breakdown and cognitive deficits characteristic of later stage AD. Affiliation: Department of Neuroscience, Rosalind Franklin University, The Chicago Medical School, North Chicago , Illinois 60064, USA . Pubmed MeSH: Disease Models, Animal , Humans , Mice, Transgenic , Neuronal Plasticity , Pyramidal Cells , RNA, Messenger , Receptor, Adenosine A1 , Synapses Wikipedia: Alzheimer's Disease , Alzheimer disease , Ammon's horn , Animal , Animal model , Animalia , Autoregulation , Calcium , Calcium metabolism , Cornu ammonis , Endoplasmic Reticulum , Ergastoplasm , Hippocampal formation , Hippocampus , Homeostasis , House Mouse , House mice , Isoforms , Laboratory mice , Laboratory mouse , Mice , Models, animal , Mouse , Mus , Mus domesticus , Mus musculus , Mus musculus domesticus , Mutation , Nerve cell , Neuron , Plastic , Presenile dementia , Presenilin , Protein isoforms , RyR1 , RyR2 , RyR3 , Ryanodine , Ryanodine receptor , Ryanodine receptor calcium release channel , Senile Dementia , Subiculum , Synaptic Transmission Title: Control of IsAHP in mouse hippocampus CA1 pyramidal neurons by RyR3 -mediated calcium -induced calcium release. PMID: 17562071 Related Articles Authors: Van de Vrede, Y , Fossier, P , Baux, G , Jols, M , Chameau, P Journal: Pflugers Arch , Vol. 455 (2): 297-308 , 2007 Abstract: In several neuronal preparations, the ryanodine-sensitive calcium store was reported to participate in the generation of slow afterhyperpolarization currents (IsAHP) involved in spike frequency adaptation. We show that calcium release from the ryanodine-sensitive calcium store is a major determinant of the triggering of IsAHP in mouse CA1 pyramidal neurons . Whole-cell patch clamp recordings in hippocampus slices show that the intracellular calcium stores depletion using an inhibitor of the endoplasmic reticulum Ca2+-ATPase (5 microM cyclopiazonic acid), as well as the specific blockade of ryanodine receptors (100 microM ryanodine ) both reduced the IsAHP by about 70%. Immunohistology, using an anti- RyR3 specific antibody, indicates that RyR3 expression is particularly enriched in the CA1 apical dendrites (considered as the most important site for sAHP generation). We show that our anti- RyR3 antibody acts as a functional RyR3 antagonist and induced a reduction in IsAHP by about 70%. The additional ryanodine application (100 micro M) did not further affect IsAHP, thus excluding RyR2 in IsAHP activation. Our results argue in favor of a specialized function of RyR3 in CA1 pyramidal cells in triggering IsAHP due to their localization in the apical dendrite. Affiliation: Laboratoire de Neurobiologie Cellulaire et Molculaire, CNRS, Avenue de la Terrasse, 91198 Gif sur Yvette , France . Pubmed MeSH: Action Potentials , Amino Acid Sequence , Animals , Calcium Channels , Electrophysiology , Neuronal Plasticity , Patch-Clamp Techniques , Protein Isoforms , Synapses Wikipedia: Ammon's horn , Antibodies , Antibody , B cell receptor , Calcium , Calcium-induced calcium release , Calcium metabolism , Constriction , Cornu ammonis , Dendrite , Endoplasmic Reticulum , Ergastoplasm , Hippocampal formation , Hippocampus , House Mouse , House mice , Immunoglobulin , Intracellular , Laboratory mice , Laboratory mouse , Localization , Mice , Mouse , Mus , Mus domesticus , Mus musculus , Mus musculus domesticus , Nerve cell , Neuron , Opsonin , Protoplasm , Pyramidal cell , RyR1 , RyR2 , RyR3 , Ryanodine , Ryanodine receptor , Ryanodine receptor calcium release channel , Subiculum Title: Postsynaptic IP3 receptor -mediated Ca2+ release modulates synaptic transmission in hippocampal neurons . PMID: 15857686 Related Articles Authors: Kelly, P T , Mackinnon, R L , Dietz, R V , Maher, B J , Wang, J Journal: Brain Res Mol Brain Res , Vol. 135 (1-2): 232-48 , 2005 Abstract: Ca(2+)-dependent mechanisms are important in regulating synaptic transmission. The results herein indicate that whole-cell perfusion of inositol 1,4,5-trisphosphate receptor (IP(3)R) agonists greatly enhanced excitatory postsynaptic current (EPSC) amplitudes in postsynaptic hippocampal CA1 neurons . IP(3)R agonist-mediated increases in synaptic transmission changed during development and paralleled age-dependent increases in hippocampal type-1 IP(3)Rs. IP(3)R agonist-mediated increases in EPSC amplitudes were inhibited by postsynaptic perfusion of inhibitors of Ca(2+)/calmodulin, PKC and Ca(2+)/calmodulin-dependent protein kinase II. Postsynaptic perfusion of inhibitors of smooth endoplasmic reticulum (SER) Ca(2+)-ATPases, which deplete intracellular Ca(2+) stores, also enhanced EPSC amplitudes. Postsynaptic perfusion of the IP(3)R agonist adenophostin ( AdA ) during subthreshold stimulation appeared to convert silent to active synapses ; synaptic transmission at these active synapses was completely blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Postsynaptic IP(3)R-mediated Ca(2+) release also produced a significant increase in spontaneous EPSC frequency. These results indicate that Ca(2+) release from intracellular stores play a key role in regulating the function of postsynaptic AMPARs. Affiliation: Department of Molecular Biosciences, University of Kansas, Lawrence , KS 66045-2106, USA . ptkelly@ku.edu Pubmed MeSH: 2-Amino-5-phosphonovalerate , Adenosine , Age Factors , Animals , Animals, Newborn , Bicuculline , Blotting, Western , Calcium , Calcium Channel Agonists , Calcium Channels , Drug Interactions , Electric Stimulation , Enzyme Inhibitors , Excitatory Amino Acid Antagonists , Excitatory Postsynaptic Potentials , GABA Antagonists , Gene Expression Regulation, Developmental , Hippocampus , Indoles , Patch-Clamp Techniques , Picrotoxin , Rats , Receptors, Cytoplasmic and Nuclear , Thapsigargin , Time Factors Wikipedia: Agranular endoplasmic reticulum , CNQX , Calmodulin kinase , Endoplasmic Reticulum , Endoplasmic reticulum, smooth , Ergastoplasm , IP3 receptor , Inositol , Inositol 1,4,5-triphosphate , Inositol 1,4,5-trisphosphate , Inositol metabolism , Inositol triphosphate receptor , Kinase , Nerve cell , Neuron , Perfusion , Phosphotransferases , Protein Kinase , Protein kinases , Proteins , Smooth endoplasmic reticulum , Synapse , Synaptic Transmission Title: Capacitative calcium entry induces hippocampal long term potentiation in the absence of presenilin-1 . PMID: 12902342 Related Articles Authors: Ris, L , Dewachter, I , Reverse, D , Godaux, E , Van Leuven, F Journal: J Biol Chem , Vol. 278 (45): 44393-9 , 2003 Abstract: Presenilins, whose mutant forms are the most common cause of early onset familial Alzheimer's disease, are involved in two very distinct processes: (i) proteolytic activity as gamma-secretase acting on amyloid precursor protein to produce amyloid peptides and (ii) storage of Ca2+ in the endoplasmic reticulum (ER). In particular, absence of presenilin-1 ( PS1 ) was claimed to potentiate capacitative calcium entry (CCE), i.e. the mechanism of replenishment of ER Ca2+ stores. However, until now, evidence in favor of the latter role has been obtained only in isolated or cultured cells and not on neurons in situ. Here, we studied the strength of the synapses between Schaffer's collaterals and CA1 neurons in hippocampal slices when they were submitted first to Ca(2+)-free medium containing thapsigargin and subsequently to normal artificial cerebrospinal fluid, a procedure known to trigger CCE. We demonstrate that Ca2+ influx via the CCE mechanism is sufficient to trigger robust long term potentiation of the synapses in hippocampal slices from transgenic mice with a postnatal, neuron-specific ablation of PS1 , but remarkably not from wild-type mice. Our data establish for the first time in neurons confined in normal neuronal networks that PS1 acts on the refilling mechanism of ER Ca2+ stores. Affiliation: Laboratory of Neuroscience, University of Mons - Hainaut , B-7000 Mons, Belgium . Pubmed MeSH: Animals , Hippocampus , Long-Term Potentiation , Membrane Proteins Wikipedia: Alpha-secretase , Alpha secretase , Alzheimer's Disease , Alzheimer disease , Amyloid , Beta-secretase , Beta secretase , Calcium , Calcium metabolism , Cells, cultured , Cerebrospinal Fluid , Endoplasmic Reticulum , Ergastoplasm , Gamma-Secretase , Gamma secretase , House Mouse , House mice , Laboratory mice , Laboratory mouse , Methods , Mice , Mouse , Mus , Mus domesticus , Mus musculus , Mus musculus domesticus , Nerve cell , Neuron , Peptides , Polypeptides , Presenile dementia , Presenilin , Procedure , Proteins , Secretase , Senile Dementia , Synapse , Thapsigargin , Transgene Title: PMID: 12723356 Related Articles Authors: Popov, V I , Medvedev, N I , Rogachevskii, V V , Ignat'ev, D A , Stewart, M G , Fesenko, E E Journal: Biofizika , Vol. 48 (2): 289-308 , 2003 Mar-Apr Abstract: The literature data and our own data on the synaptic plasticity and remodeling of synaptic organelles in the central nervous system are reviewed. Modern techniques of laser scanning confocal microscopy and serial thin sectioning for in vivo and in vitro studies of dendritic spines, including the relationship between morphological changes and the efficacy of synaptic transmission, are discussed using, in particular, a model of long-term potentiation. The organization of dendritic spines and postsynaptic densities of different categories as well as the role of filopodia in spine genesis were analyzed. It was shown that the method of serial ultrathin sections is the most effective for unbiased quantitative stereological analysis and 3D reconstructions. By using the refined method of serial ultrathin sections with subsequent three-dimensional reconstructions, the presence of giant mitochondria in hippocampal neuronal dendrites was demonstrated. It was shown that smooth endoplasmic reticulum forms a unified continuum with the outer membrane of the mitochondrial envelope within dendrites. It was suggested that this continuum provides calcium tunneling, which makes possible intracellular signal transduction during synaptic transmission. Evidence is presented indicating the presence of gap junctions ( electrical synapses ) in the synapses of mammalian brain, as well as between glial processes, and between glial cells and neurons . Our data and the data of other authors show that glial cell processes form a structural and functional glial network, which modulates the functioning of the neuronal network. The connection of dendritic spines with the glial network is shown on 3D reconstructions by analyzing the neuropil volume in CA1 hippocampal area of ground squirrels in three functional states: normothermia, provoked arousal, and hibernation when brain temperature falls below 6 degrees C. The own data of the authors are discussed indicating the formation of more than five presynaptic boutons (multiple synapses ) on both CA1 mushroom-like dendritic spines and CA3 thorny excrescences. On the basis of the analysis, new ideas of the organization and functioning of synapses were suggested. Affiliation: Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia . popvi@mail.ru Pubmed MeSH: Animals , Gerbillinae , Hibernation , Rats , Species Specificity Wikipedia: Agranular endoplasmic reticulum , Ammon's horn , Anxiety , Astrocyte , Astroglia , Calcium , Calcium metabolism , Confocal Microscopy , Confocal laser scanning microscopy , Cornu ammonis , Dendrite , Dendritic spine , Electrical synapse , Endoplasmic Reticulum , Endoplasmic reticulum, smooth , Ergastoplasm , Filopodia , Gap junction , Glia , Glial Cells , Glial cell , Hippocampal formation , Hippocampus , Lamellipodia , Laser , Lobopodia , Long-term potentiation , Long term potentiation , Maser , Membrane , Microscopy , Microscopy, confocal , Microtomy , Mitochondria , Mitochondrion , Nerve cell , Nervousness , Neuroglia , Neuron , Neuropil , Organelle , Plastic , Pseudopodia , Pseudopodium , Pulsed laser , Q-switched laser , Smooth endoplasmic reticulum , Subiculum , Synapse , Synaptic Transmission , Temperature , Ultramicrotomy , Underweight Title: Calcium /calmodulin-dependent protein kinase II clusters in adult rat hippocampal slices. PMID: 12421609 Related Articles Authors: Tao-Cheng, J H , Vinad, L , Pozzo Miller, L D , Reese, T S , Dosemeci, A Journal: Neuroscience , Vol. 115 (2): 435-40 , 2002 Abstract: We have previously reported the formation of calcium /calmodulin-dependent protein kinase II ( CaMKII ) clusters approximately 110 nm in diameter in hippocampal neurons in culture and in the intact adult brain, under conditions that simulate ischemic stress and increase (i) . These observations suggest that ischemia-like conditions that prevail during the dissection of brain tissue for the preparation of hippocampal slices could lead to the formation of CaMKII clusters. We now show by pre-embedding immuno-electron microscopy that, indeed, CaMKII clusters are present in the CA1 pyramidal neurons in hippocampal slices from adult rats fixed immediately after dissection, and that the number of CaMKII clusters increases with the delay time between decapitation and fixation. Moreover, CaMKII clusters are typically localized near the endoplasmic reticulum . When acute slices are allowed to recover in oxygenated medium for 2 h, CaMKII clusters mostly disappear, indicating that clustering is reversible. Also, the postsynaptic density, another site for CaMKII accumulation under excitatory conditions, becomes thinner upon recovery. Treatment of recovered slices with high potassium for 90 s causes the re-appearance of CaMKII clusters in nearly all CA1 pyramidal cells examined. On the other hand, when dissociated hippocampal neurons in primary culture are exposed to the same depolarizing conditions, only approximately 25% of neurons exhibit CaMKII clusters, indicating a difference in the susceptibility of the neurons in culture and in acute slices to excitatory stimuli. Altogether these observations indicate that the effect of CaMKII clustering should be considered when interpreting experimental results obtained with hippocampal slices. Affiliation: Laboratory of Neurobiology, NINDS, NIH, Building 36, Room 2A21, Bethesda , MD 20892, USA . chengs@ninds.nih.gov Pubmed MeSH: Age Factors , Animals , Cells, Cultured , Culture Media , Hippocampus , Microscopy, Electron , Organ Culture Techniques , Rats , Rats, Sprague-Dawley , Synapses Wikipedia: Adult , CaMKII , CaM KII , CaM Kinase II , Calmodulin kinase , Cluster Analysis , Cluster analyses , Clustering , Decapitation , Dioxygen , Dissection , Dissociation , Dissociative Disorders , Dissociative disorder , Endoplasmic Reticulum , Ergastoplasm , Fugue , Kinase , Microscopy , Nerve cell , Neuron , Neuroscience , Oxygen , Oxygen metabolism , Oxygenator , Phosphotransferases , Potassium , Potassium Metabolism , Protein Kinase , Protein kinases , Proteins , Pyramidal cell , Tissue Title: Release and sequestration of calcium by ryanodine-sensitive stores in rat hippocampal neurones. PMID: 9234194 Related Articles Authors: Garaschuk, O V , Yaari, Y , Konnerth, A Journal: J Physiol , Vol. 502 ( Pt 1) , 1997 Abstract: 1. The properties of ryanodine-sensitive Ca2+ stores in CA1 pyramidal cells were investigated in rat hippocampal slices by using whole-cell patch-clamp recordings combined with fura-2-based fluorometric digital imaging of cytoplasmic Ca2+ concentration ( i). 2. Brief pressure applications of caffeine onto the somata of pyramidal cells caused large transient increases in i (Ca2+ transients) of 50-600 nM above baseline. 3. The Ca2+ transients evoked by caffeine at -60 mV were not associated with an inward current, persisted after blocking voltage-activated Ca2+ currents and were completely blocked by bath-applied ryanodine. Similar transients were also evoked at +60 mV. Thus, these transients reflect Ca2+ release from intracellular ryanodine-sensitive Ca2+ stores. 4. The Ca2+ transients evoked by closely spaced caffeine pulses rapidly decreased in amplitude, indicating progressive depletion of the Ca2+ stores. The amplitude of the Ca2+ transients recovered spontaneously with an exponential time constant of 59 s. Recovery was accelerated by depolarization-induced elevations in i and blocked by cyclopiazonic acid (CPA) and thapsigargin, indicating that store refilling is mediated by endoplasmic reticulum Ca(2+)-ATPases. 5. Even without prior store depletion the caffeine-induced Ca2+ transients disappeared after 6 min exposure to CPA, suggesting that ryanodine-sensitive Ca2+ stores are maintained at rest by continuous Ca2+ sequestration. 6. Caffeine-depleted Ca2+ stores did not refill in Ca(2+)-free saline, suggesting that the refilling of the stores depends upon Ca2+ influx through a 'capacitative-like' transmembrane influx pathway operating at resting membrane potential. The refilling of the stores was also blocked by Ni2 + and gallopamil (D600). 7. Elevations of basal i produced by bath-applied KCl markedly potentiated (up to 6-fold) the caffeine-induced Ca2+ transients. The degree of potentiation was positively related to the increase in basal i. The Ca2+ transients remained potentiated up to 9 min after reversing the KCl-induced i increase. Thus, the ryanodine-sensitive Ca2+ stores can 'overcharge' when challenged with an increase in i and slowly discharge excess Ca2+ after basal i returns to its resting level. 8. Pressure applications of caffeine onto pyramidal cell dendrites evoked local Ca2+ transients similar to those separately evoked in the respective somata. Thus, dendritic ryanodine-sensitive Ca2+ stores are also loaded at rest and can function as independent compartments. 9. In conclusion, the ryanodine-sensitive Ca2+ stores in hippocampal pyramidal neurones contain a releasable pool of Ca2+ that is maintained by a Ca2+ entry pathway active at subthreshold membrane potentials. Ca2+ entry through voltage-gated Ca2+ channels transiently overcharges the stores. Thus, by acting as powerful buffers at rest and as regulated sources during activity, Ca2+ stores may control the waveform of physiological Ca2+ signals in CA1 hippocampal pyramidal neurones. Affiliation: I Physiologisches Institut, Universitt des Saarlandes, Homburg , Germany . Pubmed MeSH: Animals , Calcium Channels , Calmodulin-Binding Proteins , Central Nervous System Stimulants , Enzyme Inhibitors , Hippocampus , Indoles , Muscle Proteins , Potassium , Rats , Rats, Wistar , Ryanodine Receptor Calcium Release Channel , Synapses Wikipedia: 1,3,7-trimethylxanthine , Acceleration , Caffeine , Calcium , Calcium metabolism , Cytoplasm , D600 , Dendrite , Endoplasmic Reticulum , Ergastoplasm , Membrane , Membrane potential , Nerve cell , Neuron , Patch-clamp technique , Pressure , Protoplasm , Pulse , Pyramidal cell , Resting membrane potential , Resting potential , Ryanodine , Salinity , Thapsigargin , Transmembrane potential , Transmembrane potential difference , Vivarin Title: Three-dimensional organization of smooth endoplasmic reticulum in hippocampal CA1 dendrites and dendritic spines of the immature and mature rat. PMID: 8987748 Related Articles Authors: Spacek, J , Harris, K M Journal: J Neurosci , Vol. 17 (1): 190-203 , 1997 Abstract: Recent studies have shown high levels of calcium in activated dendritic spines, where the smooth endoplasmic reticulum (SER) is likely to be important for regulating calcium . Here, the dimensions and organization of the SER in hippocampal spines and dendrites were measured through serial electron microscopy and three-dimensional analysis. SER of some form was found in 58% of the immature spines and in 48% of the adult spines. Less than 50% of the small spines at either age contained SER, suggesting that other mechanisms, such as cytoplasmic buffers, regulate ion fluxes within their small volumes. In contrast, 80% of the large mushroom spines of the adult had a spine apparatus, an organelle containing stacks of SER and dense-staining plates. Reconstructed SER occupied 0.001-0.022 microm3, which was only 2-3.5% of the total spine volume; however, the convoluted SER membranes had surface areas of 0.12-2.19 microm2, which were 12 to 40% of the spine surface area. Coated vesicles and multivesicular bodies occurred in some spines, suggesting local endocytotic activity. Smooth vesicles and tubules of SER were found in continuity with the spine plasma membrane and margins of the postsynaptic density (PSD), respectively, suggesting a role for the SER in the addition and recycling of spine membranes and synapses . The amount of SER in the parent dendrites was proportional to the number of spines and synapses originating along their lengths. These measurements support the hypothesis that the SER regulates the ionic and structural milieu of some, but not all, hippocampal dendritic spines. Affiliation: Department of Pathology, Charles University Medical Faculty Hospital, CZ-500 05 Hradec Kralove , Czech Republic . Pubmed MeSH: Aging , Animals , Endocytosis , Exocytosis , Hippocampus , Humans , Rats , Rats, Inbred Strains Wikipedia: Adult , Agranular endoplasmic reticulum , Calcium , Calcium metabolism , Cell Membrane , Cell membranes , Cytoplasm , Cytoplasmic membrane , Dendrite , Dendritic spine , Electron , Electron Microscopy , Electronic , Endoplasmic Reticulum , Endoplasmic reticulum, smooth , Ergastoplasm , Ions , Membrane , Microscopy , Microscopy, electron , Negatron , Parent , Plasma membrane , Positron , Protoplasm , Smooth endoplasmic reticulum , Step-parent , Stepparent , Synapse Page 1 2 Title: Cytosolic Ca2+ binding proteins during rat brain ageing: loss of calbindin and calretinin in the hippocampus, with no change in the cerebellum. PMID: 8000572 Related Articles Authors: Villa, A , Podini, P , Panzeri, M C , Racchetti, G , Meldolesi, J Journal: Eur J Neurosci , Vol. 6 (9): 1491-9 , 1994 Abstract: The expression of two cytosolic, high affinity Ca(2+)-binding proteins, calbindin-28 and calretinin, has been investigated in the cerebellum and hippocampus of young and old rats (from 12 days to 30 months) by combining immunofluorescence and Western blotting. Three markers, calreticulin (the major Ca2+ binding protein within the lumen of the endoplasmic reticulum ), MAP-2 (a microtubule binding protein concentrated in neuronal dendrites ) and synaptophysin (an integral protein of synaptic vesicles), were studied in parallel. In the cerebellar cortex a rise from 12 to 60 days was observed with calbindin-28 and, especially, calretinin, concentrated in the Purkinje and granule neurons , respectively. The level of expression of the two proteins subsequently remained high and the distribution was unchanged, even in the cerebellum of old animals. A completely different pattern was observed in the hippocampus. Here calretinin, present especially in fibres and interneurons, was abundant in the young, decreased in the adult and reached low values in the old rats. Calbindin-28 accumulated during growth, especially in a subpopulation of CA1 pyramidal cells and in the mossy fibres of CA3, then declined, although irregularly, during ageing. These changes of the two proteins were more marked in the dorsal and central parts than in the ventral part of the hippocampus. In the same brain areas the levels of expression of the three additional markers and their distribution within neurons and synapses were unchanged by ageing.(ABSTRACT TRUNCATED AT 250 WORDS) Affiliation: Department of Pharmacology, CNR Cytopharmacology, Milan , Italy . Pubmed MeSH: Aging , Brain , Calcium-Binding Protein, Vitamin D-Dependent , Calcium-Binding Proteins , Immunohistochemistry , Rats , Rats, Sprague-Dawley Wikipedia: Adult , Ammon's horn , Animal , Animalia , Binding protein , Blotting, western , Calreticulin , Carrier proteins , Cellular senescence , Cerebellar cortex , Cerebellum , Cornu ammonis , Cytosol , Dendrite , Endoplasmic Reticulum , Ergastoplasm , Fluorescent antibody technique , Hippocampal formation , Hippocampus , Immunofluorescence , Interneuron , Microtubule , Nerve cell , Neuron , Proteins , Pyramidal cell , Subiculum , Synapse , Synaptic vesicle , Synaptophysin , Western Blot , Western blotting Page 1 2 对100篇相关文献的计量分析结果: Top Countries Publications USA 53 United Kingdom 8 Japan 7 Germany 7 Canada 7 France 4 Sweden 3 Italy 2 New Zealand 2 Spain 2 Netherlands 1 Switzerland 1 Taiwan 1 China 1 Argentina 1 1 2 3 4 Top Cities Publications New York 6 Boston 6 Bethesda 5 Montreal 4 Valhalla 3 London 3 Birmingham, USA 3 Aurora 2 Yamagata 2 New Haven 2 San Francisco 2 Paris 2 Dallas 2 Albuquerque 2 Gothenburg 2 Madrid 2 Oxford 2 Utrecht 1 Munich 1 Milan 1 1 2 3 4 1 2 Top Journals Publications J Neurosci 37 J Neurophysiol 9 Neuron 6 Eur J Neurosci 5 J Physiol-london 5 Neuroscience 3 Hippocampus 3 Nature 2 Prog Neurobiol 2 Proc Natl Acad Sci U S A 2 P Natl Acad Sci Usa 2 J Physiol 2 Mol Cell Neurosci 2 Learn Memory 2 Eur J Cell Biol 1 Neuropharmacology 1 Crit Rev Neurobiol 1 Cell 1 Neurosci Lett 1 Can J Physiol Pharm 1 1 2 1 2 3 ... 17 Top Authors Publications Lacaille J 6 McBain C 3 Topolnik L 3 Congar P 3 Horne E 3 Svoboda K 3 Sabatini B 3 Pelkey K 2 Gomez L 2 Dell'Acqua M 2 Matsumoto M 2 Fujii S 2 Kato H 2 Konnerth A 2 Stanton P 2 Crepel F 2 Siegelbaum S 2 Fine A 2 Emptage N 2 Otani S 2 1 2 3 ... 17 研究主题分布: 1 2 3 ... 52 Top Terms Publications Animals 98 Synapses 87 Plastics 79 Neurons 70 Rats 70 Hippocampus 69 Dendrites 63 dendrite 62 Glutamates 55 Synaptic Transmission 52 Calcium 52 N-Methylaspartate 51 Receptors, Glutamate 48 Pyramidal Cells 47 N-methyl-D-aspartate selective glutamate receptor activity 47 Depression 46 Receptors, N-Methyl-D-Aspartate 46 Neuronal Plasticity 46 Dendritic Spines 45 Long-Term Potentiation 44 1 2 3 ... 52 Top Terms Publications long-term synaptic potentiation 42 dendritic spine membrane 42 dendritic spine 41 Excitatory Postsynaptic Potentials 40 Patch-Clamp Techniques 35 Receptors, Metabotropic Glutamate 35 Electric Stimulation 34 pyramidal neuron development 31 pyramidal neuron differentiation 30 pyramidal neuron migration 30 receptor activity 30 synaptic transmission 30 Rats, Sprague-Dawley 30 signal transduction 29 long term synaptic depression 28 Receptors, AMPA 27 alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid selective glutamate receptor complex 27 alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid 27 Proteins 26 Excitatory Amino Acid Antagonists 26 1 2 3 4 ... 52 Top Terms Publications Action Potentials 25 hippocampus development 25 Calcium Signaling 24 nmda receptor 24 intracellular 23 ampa 22 Long-Term Synaptic Depression 22 learning 19 Mice 19 Membranes 17 membrane 17 Signal Transduction 17 Phosphotransferases 16 synapse 16 Cells, Cultured 16 positive regulation of synaptic plasticity 15 Rats, Wistar 15 Protein Kinases 14 Calcium Channels 14 learning or memory 13 1 2 3 4 5 ... 52 Top Years Publications 2006 13 2007 12 2005 11 2009 10 2008 9 2004 6 2001 6 2002 6 2000 6 1999 5 2003 3 1992 3 1996 3 1998 3 1988 1 1997 1 1993 1 1995 1 Top Terms Publications postsynaptic density 13 glutamate receptor activity 13 Organ Culture Techniques 13 mglur 13 regulation of excitatory postsynaptic membrane potential 12 Interneurons 12 regulation of action potential in neuron 12 regulation of action potential 12 positive regulation of action potential 12 negative regulation of action potential 12 Microscopy 12 Inositol 1,4,5-Trisphosphate Receptors 11 PLC activating metabotropic glutamate receptor activity 11 Membrane Potentials 11 Inositol 10 Calcium Channels, L-Type 10 Glutamic Acid 10 Time Factors 10 metabotropic glutamate receptor 10 regulation of synaptic plasticity 9 1 2 3 4 5 6 ... 52 Top Terms Publications Glycine 9 Fluorescence 9 positive regulation of dendrite morphogenesis 9 Neural Inhibition 9 Probability 9 Inositol 1,4,5-Trisphosphate 8 nmdar 8 Humans 8 ionotropic glutamate receptor activity 8 Electrophysiology 8 Actins 7 protein serine/threonine kinase activity 7 pka 7 actin 7 Mice, Knockout 7 nr2b 7 Ryanodine 7 Endoplasmic Reticulum 7 Green Fluorescent Proteins 7 endoplasmic reticulum 7 1 2 3 4 5 6 7 ... 52 Top Terms Publications extracellular region 7 Transfection 7 Receptors, Neurotransmitter 7 Adult 7 Calcium-Calmodulin-Dependent Protein Kinase Type 2 7 6-Cyano-7-nitroquinoxaline-2,3-dione 7 positive regulation of synaptic transmission 7 Presynaptic Terminals 7 glutamate receptor 7 Electrons 7 Electronics 7 Axons 7 axon 7 Mossy Fibers, Hippocampal 6 Cyclic AMP-Dependent Protein Kinases 6 ionotropic glutamate receptor complex 6 ionotropic glutamate receptor binding 6 regulation of neuronal synaptic plasticity 6 Carrier Proteins 6 negative regulation of synaptic plasticity 6 1 2 3 ... 5 6 7 8 ... 52 Top Years Publications 2009 3 2003 2 1997 2 2007 1 2005 1 2002 1 1994 1