2007年10月11日Nature中文摘要
时间:2007-10-26 10:33 来源:科学时报 作者:admin 点击:次
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封面故事：语言的发展变化 Quantifying the evolutionary dynamics of language / Frequency of word-use predicts rates of lexical evolution throughout Indo-European history 随着语言的演化，便出现了语法规则，不符合语法规则的用法便会逐渐消亡。 Lieberman等人根据英语1200年的使用情况计算了一种语言变得比较规则的发展 速度。在160个不规则动词中，70个在上个千年里变成规则动词了。如果一个不 规则动词比另一个不规则动词罕见100倍，那么它规则化的速度要比后者快10 倍。某种规则的出现（比如说给一个动词之后加“ed”来表示过去式）宣告了例 外词形的消亡。本期封面图片说明这样一个观点：动词大小相应于使用频率，所 以大的动词保持在最前面，而下一个将要消失的不规则动词是“wed”。在另一 项研究中，Pagel等人分析了词义是怎样发展变化的。在整个印欧语系中，像 “tail”或“bird”这样的单词发展变化非常快，并且可以由很多不相关的单词 来表述；而另一些单词，如数字“two”，则由整个语系中词义非常相近的词形 来表达。来自超过80种现代语言的数据表明，一个单词使用越多，其变化就越 小。（Letters pp. 713, 717; News & Views p. 665; www.nature.com/podcast）封面图片：JONATHAN SARAGOSTI 复制基因之间的任务分配（A parting of the ways） Gene duplication and the adaptive evolution of a classic genetic switch 基因复制早就被认定为新基因和功能的一个来源，但大多数复制的基因没有新功 能；它们只是将先祖基因的任务再分配。现在，研究人员对一例任务分配进行了 详细分析。在酿酒酵母中，半乳糖利用通道包括两个非常相似的基因，编码一种 共诱导因子（GAL3）和一种酶（GAL1）。二者是从一个双功能先祖基因传下来 的，后者仍然见于其他酵母。两个原始基因之间可能的冲突已经解决，主要是由 调控序列中所发生的一系列自适应变化来解决的。这种逐渐的退化花了近1亿年 才完成，到GAL3完全失去半乳糖激酶活性才结束。GAL1 和 GAL3集成进了一个更 复杂的、也可能更优化的基因通道中。（Article p. 677; News & Views） 微RNA与癌细胞转移有关（MicroRNA and metastasis） Tumour invasion and metastasis initiated by microRNA-10b in breast cancer 一种正常作用之一可能是帮助细胞从胚胎的一部分向另一部分运动的微RNA，被 发现在侵略性人类乳腺癌中高度表达，调控乳腺癌细胞的迁移、入侵和转移。微 RNA（自然出现的单链RNA分子，参与基因调控）以前曾被发现能引起癌症，但这 是首次关于它与癌细胞转移有关的报告。微RNA的功能目标似乎是HoxD10基因， 它是参与引导胚胎发育的Hox基因家族的一个成员。（Article p. 682; News & Views） 由“卡西尼”获得的“土卫二”图片的分析结果（The road to Damascus） Association of the jets of Enceladus with the warmest regions on its south-polar fractures 2005年7月14日“卡西尼”飞船掠过“土卫二”时，显示了由土星这颗冰质卫星 南极附近发出的水蒸气和冰形成的喷射流。这个地区异常得温暖，最高温度与该 卫星表面上四个“虎纹状”表面裂缝相关，它们分别被很有色彩地命名为亚历山 大、开罗、巴格达和大马士革。现在，Joseph Spitale 和Carolyn Porco采用三 角测量方法对“卡西尼”获得的图像进行了测量，以获得关于最显著的喷射流的 来源的准确信息。他们发现，这些喷射流是从虎纹裂缝发出的，最强的来源位于 巴格达和大马士革。（Letter p. 695） 测量激光辐射振幅和相位的方法（A measured approach） Phase-resolved measurements of stimulated emission in a laser 激光辐射通常是用确定频率和强度的探测器来测量的，但并不收集关于辐射相的 信息。通过测量辐射相，将有可能深入了解激光操作背后的光学放大及衰减的动 态过程。现在，Kroll等人开发出一种测量来自被称为“量子级联激光器”的激 光辐射的振幅及相位的方法，这种激光器在太赫兹范围内工作。该方法也可被延 伸到其他类型的激光器，可用来研究导致光损失的效应，这是提高激光表现的有 用信息。（Letter p. 698; News & Views） 第四种形式的铁性（Ferrotoroidicity goes fourth） Observation of ferrotoroidic domains 铁性材料（即铁磁性材料、铁电性材料和铁弹性材料）的特性，是分别基于磁 化、电极化和弹性形变的“形成畴”（forming domains）的特性。这种特性使 得这些材料在技术上非常重要，比如在数据存储中用作铁电记忆装置或用作写在 硬盘上的铁磁畴。研究人员根据磁性蜗旋的有序排列（或称作toroidization） 又提出了第四种形式的铁性，名叫ferrotoroidicity。现在，这种形式的铁性的 先决条件之一已经被观测到，它以方向相反的ferrotoroidic畴的形式存在。 ferrotoroidic畴过去曾在磷酸锂钴上通过光学手段观测到，与独立的反铁磁畴 共存。Ferrotoroidic状态与其他铁性状态不同之处是，在时间和空间逆转时其 行为是不对称的。这种不对称性有可能导致对未来应用来说让人欣喜的可能性。 （Letter p. 702; News & Views） 地表比湿增加主要由人为影响造成（Getting steamed up） Attribution of observed surface humidity changes to human influence 大气湿度对降水的分布及最大强度、对热带气旋的潜在强度、对地表水文和人的 热应激等都有很大影响。研究人员曾经观测到地球表面的比湿（给定体积的空气 中水蒸气与空气之比）显著增加，但这些变化是由于自然影响还是人为影响却不 清楚。现在，利用一组关于地表比湿观测结果的新数据，以及一个耦合的气候模 型的输出结果，Willett等人发现，全球平均表面比湿在20世纪最后几个十年显 著增加，这种增加主要是由人为影响造成的。（Letter p. 710） 不良炎症反应的抑制（Adrenergic inflammation） Phagocyte-derived catecholamines enhance acute inflammatory injury 关于细胞吞噬性血细胞（巨噬细胞和嗜中性细胞）是茶酚胺（去甲肾上腺素和肾 上腺素）一个重要来源、能引起急性炎症反应增强的发现有点出人意料。身体对 于创伤或感染的炎症反应是为了保护身体，将其恢复到受伤前的状态，但过度的 炎症反应会严重伤害组织和器官。用急性肺损伤大鼠和小鼠模型所做的实验表 明，吞噬细胞几乎可以充当肾上腺素能系统的第三个组成部分，连接脑中的肾上 腺髓质和突触神经元。这些发现提出这样一个可能性：人们不想要的炎症反应 （如在动脉硬化、急性心肌梗塞和急性肺损伤等状况中所看到的）在人体中也许 可通过肾上腺素能受体阻断来得到抑制。（Letter p. 721） 神经传输物质的转运（Neurotransmitter transport） Mechanism of chloride interaction with neurotransmitter:sodium symporters 最近，一篇具有里程碑意义的论文报告了LeuT的晶体结构。LeuT是依赖于Na+/Cl –的神经传输物质转运蛋白在细菌中的一种同源结构。在这种同源结构中，转运 蛋白与两个钠离子和一个基质分子结合在一起。在这一家族的真正的神经传输物 质转运蛋白中，氯化物是与钠和神经传输物质共同转运的。Zomot等人将关于 LeuT以及来自一个完全不同的家族的一种氯化物转运蛋白的结构和机制知识应用 于哺乳动物“神经传输物质/钠转运体”（NSS）转运蛋白，包括GAT-1在内。他 们发现，被转运的氯化物离子的作用是中和钠离子所携带的正电荷，并将氯化物 结合点的可能位置确定在与其中一个钠离子相邻的地方。由于这些转运蛋白在神 经传输调控中的作用，由于它们充当Prozac (fluoxetine)等药物的作用点，因 此它们的机制是人们特别感兴趣的。（Letter p. 726） 否定RNA疗法还为时过早（RNAi therapy back on track） Effective RNAi-mediated gene silencing without interruption of the endogenous microRNA pathway Nature杂志去年发表的一篇论文似乎断定由RNA干涉调控的沉寂作用来进行基因 治疗的前景不妙。该论文表明，大剂量的短发夹RNA会阻断小鼠的微RNA通道，造 成致命后果。现在，一项新的研究表明，否定RNA疗法还为时过早。一种不同类 型的抑制性RNA——小干涉RNA（siRNAs）——可以给实验鼠施用，而不产生毒 性。肝脏微RNA的活性仍然不受siRNAs影响，尽管小鼠和仓鼠肝脏细胞中的目标 基因80%被沉寂。（Letter p. 745） ---------------------- NEWS AND VIEWS ---------------------- Linguistics: An invisible hand pp665 - 667 Quantitative relationships between how frequently a word is used and how rapidly it changes over time raise intriguing questions about the way individual behaviours determine large-scale linguistic and cultural change. W. Tecumseh Fitch doi:10.1038/449665a http://www.nature.com/nature/journal/v449/n7163/full/449665a.html Organic chemistry: Zippier synthesis in water pp667 - 669 Complex toxin molecules are the ultimate challenge for organic chemists ― even successful syntheses often involve an impractical number of steps. A biologically inspired reaction might simplify things. Masayuki Inoue doi:10.1038/449667a http://www.nature.com/nature/journal/v449/n7163/full/449667a.html Laser physics: A phase it's going through pp669 - 670 When we observe laser light, we typically measure its intensity, and so wave amplitude. The phase, which encodes further details of the laser's internal workings, was obscure ― but fresh light is being shed on it. David S. Citrin doi:10.1038/449669a http://www.nature.com/nature/journal/v449/n7163/full/449669a.html Cancer: Micromanagement of metastasis pp671 - 673 Although they were discovered only in the early 1990s, many regulatory functions of microRNAs ― naturally occurring short RNA sequences ― have already been reported. The latest news is that they mediate cancer spread. Patricia S. Steeg doi:10.1038/449671a http://www.nature.com/nature/journal/v449/n7163/full/449671a.html Evolutionary genetics: Making the most of redundancy pp673 - 674 Single genes, chromosomal regions and even entire genomes can undergo duplication. What good can come of these extra copies? Evolution seems to use several tricks to take advantage of the situation. Edward J. Louis doi:10.1038/449673a http://www.nature.com/nature/journal/v449/n7163/full/449673a.html Solid-state physics: Response with a twist pp674 - 675 The behaviour of ferromagnetic and ferroelectric materials in a magnetic or electric field makes them easy to spot. But for their more recently discovered counterpart, ferrotoroidic materials, things become complex. Karin M. Rabe doi:10.1038/449674a http://www.nature.com/nature/journal/v449/n7163/full/449674a.html ---------------------- ARTICLES ---------------------- Gene duplication and the adaptive evolution of a classic genetic switch pp677 - 681 With the increasing availability of genomic sequences, it is possible to ask questions about evolution by examining closely related species and genes. This paper shows that the well-studied GAL3 and GAL1 genes in yeast evolved from one ancestral gene, via movement of transcriptional regulatory sites after a gene duplication event. Chris Todd Hittinger and Sean B. Carroll doi:10.1038/nature06151 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06151.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06151.html Tumour invasion and metastasis initiated by microRNA-10b in breast cancer pp682 - 688 miR-10b is highly expressed in aggressive human breast cancers and mediates breast cancer cell migration, invasion and metastasis. miR-10b is transcriptionally activated by Twist and exerts its effects by regulating the target genes HOXD10 and RHOC. Li Ma, Julie Teruya-Feldstein and Robert A. Weinberg doi:10.1038/nature06174 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06174.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06174.html A histone H3 lysine 27 demethylase regulates animal posterior development pp689 - 694 Two JmjC-domain-contain ing enzymes are shown to catalyse demethylation of histone H3K27me3, a histone modification mediated by polycomb proteins and associated with stem cell maintenance and differentiation. Fei Lan et al. doi:10.1038/nature06192 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06192.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06192.html ---------------------- LETTERS ---------------------- Association of the jets of Enceladus with the warmest regions on its south-polar fractures pp695 - 697 Jets of material have been seen emanating from the south-polar terrain of Saturn's satellite Enceladus. Observations have shown that region is anomalously warm, with the hottest measured temperatures coinciding with four 'tiger stripe' fractures. Cassini images are used to triangulate the source locations for the most prominent jets, and find that the jets emanate from the four tiger stripes. Joseph N. Spitale and Carolyn C. Porco doi:10.1038/nature06217 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06217.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06217.html Phase-resolved measurements of stimulated emission in a laser pp698 - 701 Laser radiation is usually measured with intensity detectors that determine frequency and intensity, but throw away information about the phase of the radiation. But a scheme has been developed to measure amplitude as well as phase of laser radiation from so-called quantum cascade lasers, which operate in the terahertz regime. Josef Kroll et al. doi:10.1038/nature06208 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06208.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06208.html Observation of ferrotoroidic domains pp702 - 705 There are currently three types of ferroic materials that are widely known; ferromagnets, ferroelectricity, and ferroelastic materials. A fourth form of ferroic order, ferrotoroidicity, has been postulated. To confirm that a material is a ferrotorodic, corresponding ferrotoroidic domains need to be observed. Spatially resolved measurements with a nonlinear optical imaging method on LiCoPO4 were carried out, and observed ferrotoroidic domains that coexist with independent antiferromagnetic domains. Bas B. Van Aken, Jean-Pierre Rivera, Hans Schmid and Manfred Fiebig doi:10.1038/nature06139 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06139.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06139.html Isotopic evidence for Mesoarchaean anoxia and changing atmospheric sulphur chemistry pp706 - 709 The observation of non-mass-dependent sulphur isotope ratios in sedimentary rocks more than a??2.4 billion years old and the disappearance of this signal in younger sediments is taken as evidence for the transition from an anoxic to oxic atmosphere around 2.4 Gyr ago. But now, the preservation of a non mass-dependent signal that differs from that of preceding and following periods in the Archean is demonstrated. The findings support the original idea of an anoxic early atmosphere before 2.4 Gyr ago, and at the same time identifies variability within the isotope record that suggests changes in pre-2.4 Gya atmospheric pathways for non-mass-dependent chemistry and in the ultraviolet transparency of an evolving early atmosphere. James Farquhar et al. doi:10.1038/nature06202 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06202.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06202.html Attribution of observed surface humidity changes to human influence pp710 - 712 A new dataset of surface specific humidity observations is used, along with output from a coupled climate model, to identify a significant increase in global mean surface specific humidity over the late twentieth century that is mainly attributable to human influence, indicating that human-induced climate change has already had a significant influence on this important climate variable. Katharine M. Willett, Nathan P. Gillett, Philip D. Jones and Peter W. Thorne doi:10.1038/nature06207 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06207.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06207.html Quantifying the evolutionary dynamics of language pp713 - 716 During language evolution, rules emerge and exceptions decline. A quantitative study measures the rate at which a human language becomes more regular over time. Specifically, the regularization of English verbs over the last 1200 years was studied, and it was found that half-life of a verb scales as the square root of its frequency, meaning that irregular verbs that are 100 times as rare regularize ten times faster. Erez Lieberman et al. doi:10.1038/nature06137 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06137.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06137.html Frequency of word-use predicts rates of lexical evolution throughout Indo-European history pp717 - 720 Statistical modelling techniques and concepts from biology are applied to linguistic data to show a general and law-like relationship between the frequency with which meanings are used in everyday language and their rate of evolution throughout Indo-European history: the more a word is used, the less likely it is to change over time. The findings demonstrate a fundamental aspect of language evolution that is predicted to apply to all languages. Mark Pagel, Quentin D. Atkinson and Andrew Meade doi:10.1038/nature06176 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06176.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06176.html Phagocyte-derived catecholamines enhance acute inflammatory injury pp721 - 725 Macrophages and neutrophils release catecholamines after exposure to lipopolysaccharide or immune complex stimulation, and phagocyte-derived catecholamines contribute to acute lung injury. Michael A. Flierl et al. doi:10.1038/nature06185 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06185.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06185.html Mechanism of chloride interaction with neurotransmitter:sodium symporters pp726 - 730 Neurotransmitter:sodium symporters (NSS) use energy derived from sodium gradients to power transport of their respective neurotransmitters. But, whereas most eukaryotic NSS transporters are chloride-dependent, the prokaryotic homologue LeuT is not. Structural and mechanistic knowledge of LeuT, and a chloride transporter from an entirely different family, is applied to mammalian NSS transporters and finds that transported chloride ions serve to neutralise the positive charge carried by the sodium ions. Elia Zomot et al. doi:10.1038/nature06133 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06133.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06133.html UTX and JMJD3 are histone H3K27 demethylases involved in HOX gene regulation and development pp731 - 734 Two human JmjC-domain-containing enzymes are shown to catalyse demethylation of histone H3K27me3, a histone modification mediated by polycomb proteins and associated with stem cell maintenance and differentiation Karl Agger et al. doi:10.1038/nature06145 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06145.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06145.html Structural basis for selective recognition of ESCRT-III by the AAA ATPase Vps4 pp735 - 739 In yeast, two ESCRT-III-related subunits, Vps2 and Did2 bind to Vps4. The crystal structure of Vps2 bound to Vp4 s is presented, elucidating the basis for selective recognition of the ESCRT-III complex. Takayuki Obita et al. doi:10.1038/nature06171 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06171.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06171.html ESCRT-III recognition by VPS4 ATPases pp740 - 744 The microtubule interacting and tarnsport (MIT) domain of Vps4 binds conserved residues in the CHMP1-3 class of ESCRT-III proteins. These results reveal how Vps4 recognises substrates to facilitate membrane fission events required for viral release and endosomal vesicles Melissa D. Stuchell-Brereton et al. doi:10.1038/nature06172 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06172.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06172.html Effective RNAi-mediated gene silencing without interruption of the endogenous microRNA pathway pp745 - 747 Recent work found that overexpression of short hairpin RNAs in cells could lead to mortality in mice, this was attributed to interference with the cellular machinery that makes miRNAs. This raised the issue of whether RNA interference-mediated silencing would be therapeutically possible. This paper shows that small interfering RNAs can be systemically administered and effectively suppress gene expression without compromising the activity of various liver miRNAs. Matthias John et al. doi:10.1038/nature06179 Abstract: http://www.nature.com/nature/journal/v449/n7163/abs/nature06179.html Article: http://www.nature.com/nature/journal/v449/n7163/full/nature06179.html (责任编辑：泉水) |