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Nature Contents 16 November 2006 (pp243-400)
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[自然要览] （选自英国Nature杂志，2006年11月16日出版） 封面故事：穴居人基因组可望两年内完成初步测序 Analysis of one million base pairs of Neanderthal DNA 穴居人（尼安德特人）的特征是在距今大约40万年前的时候出现在欧洲和西亚的 人类化石记录中的，消失时间是在距今大约3万年前左右。穴居人是我们已灭绝 的关系最近的近亲，所以随着DNA技术的进步，识别现代人特有的基因变化的目 标离我们更近了。现在，研究人员识别出一块距今3.8万年的穴居人骨头，其保 存质量很高，足以能从中提取出100万个以上的碱基对。该骨头最初是1980年在 克罗地亚的Vindija洞穴中发现的（其照片刊登在本期封面上）。通过将它的DNA 组成与黑猩猩和人的基因组进行对比，研究人员发现，穴居人和人类祖先（像人 但不像猿）具有一个小而有效的种群规模。这项研究工作中所采用的技术使得科 学家有可能在两年内完成对穴居人基因组的初步测序。Article p. 330; News & Views p. 275; www.nature.com/podcast）封面照片：Johannes Krause/454 Life Sciences 植物免疫系统中一些未解之谜（Plants up the anti） The plant immune system 详细了解植物的免疫系统，对于农业和害虫控制具有重要意义。植物由于没有哺 乳动物的移动防卫细胞和适应性免疫反应，因此依靠每个细胞的先天免疫力以及 从感染点在植物内各处发送的信号来进行免疫。Jonathan Jones 和 Jeffrey Dangl对当前关于植物防卫体系的模型进行了评述，发现了一些尚未得到回答的 问题，其中包括用来遏制病原体生长的机制。（Review Article p. 323） 白藜芦醇的减肥作用是有条件的（Let them eat cake） Resveratrol improves health and survival of mice on a high-calorie diet 当“白藜芦醇(Resveratrol)能提高食用高热量食物的小鼠的健康水平和存活 率”的文章在网上发表后，那些怕胖的人们似乎看到了希望，认为以后想吃什么 就可以吃什么，不用担心发胖，而且还能永葆青春。而这篇论文实质上是说，以 人类可以做到的剂量口服白藜芦醇（当然不是从红酒中摄取，因为要达到所需剂 量每天需要喝几百瓶红酒，这样将会产生副作用），可以在小鼠身上重现食用低 热量食物所产生的生理效应，并使健康水平和存活率总体上有所提高。详情请看 本期所发表的这篇论文。（Article p. 337; News and Views） 用Taylor-Couette实验进行天体物理研究（The power behind the stars） Hydrodynamic turbulence cannot transport angular momentum effectively in astrophysical disks 利用引力能量来为类星体提供动力或形成恒星和行星的增长盘，是宇宙中已知效 率最高的能源之一。例如，一个黑洞周围的一个增长盘能以高达40%的效率将净 质量能转化为辐射能。这种转化的性质仍然比较神秘。Taylor-Couette实验（转 动的柱体之间的流体流）一直是关于非线性流体力学和涡流转变的研究工作的中 心内容，但基本上是用在流动体系中，与天体物理无关。在将一种实验室中的实 验用到天体物理学中的一个少见的实例中，一种Taylor-Couette仪器被用来模拟 天体物理条件下一种转动的流体中所涉及的力。实验结果排除了纯粹的水力扰 动，因此支持磁转动不稳定性作为造成扰动的可能原因的观点。（Letter p. 343; News and Views） 石墨薄片纳米材料可能有半金属行为（Half metals: nanoribbon development） Half-metallic graphene nanoribbons 科学家已经预测到了被称为“半金属”的让人好奇的材料的存在：仅仅对于一半 的自有电子（即那些在特定自旋方向上的电子）来说它们才是金属，而对于另一 半电子（自旋方向相反），它们是绝缘材料。虽然关于半金属行为有一些实验证 据，但科学家仍在努力寻找这种材料，它们有可能在自旋电子应用中有实际用 途。Son等人利用“第一原理”计算预测，纳米尺度的带状Graphene（一种石墨 薄片材料）会有半金属行为。当将均匀电场施加到这种纳米带上时（其“之”字 形的边缘附着在电压接触点上），这种性质就会出现。这项工作有可能为探索基 于Graphene的“纳米自旋电子材料”（nanospintronics）开辟一条道路。 （Letter p. 347） PTCDA材料的扫描隧道显微镜实验（Currents at large） Free-electron-like dispersion in an organic monolayer film on a metal substrate 当一个电流流过一种分子材料时，电子要么在分子之间缓慢跳动，要么在整个材 料中快速移动。后一个机制只有当电流中所涉及电子状态是分散的、允许电子大 规模地离开其位置时才有可能。现在，在沉积在一个银基质上的一种“原型有机 半导体”（PTCDA）材料上所做的扫描隧道显微镜实验，使研究人员首次在一个 分子薄层中观测到了广泛的扩散和电子移位。所观测到的扩散要比这种有机材料 本身预计可能发生的扩散强很多。这说明，通过设计有机分子和它们的金属基质 之间的分子间耦合，有可能实现电子运动性的大力增强，这种增强是电子应用中 经常所期望的。（Letter p. 350） 影响深海生态系统营养供应的另一因素（Flushing submarine canyon） Flushing submarine canyons 海底峡谷（深入到大陆坡中的陡峭峡谷）会像漏斗一样将水流和沉积物从海水较 浅的沿海地区转移到深海中。人们认为，这些水流大多是因为（泥沙）未能沉积 或河流洪水引起的。从法国马赛沿海附近的狮子湾（Gulf of Lions）所获得的 新的观测结果表明，它们也是由“致密的大陆架水流瀑布作用”诱发的，这是一 种比较常见的水流类型，即温度低、密度大的水从大陆架流走。这意味着，沉积 物和有机质向深海的输送可能要比我们以前所认为的更多。由未来气候变化引起 的“致密的大陆架瀑布水”数量的任何变化，对于深海生态系统的营养供应以及 深海的碳存储都可能会产生重要影响。（Letter p. 354） 地震最大强度的预测（Earthquakes: the endgame） Predicting the endpoints of earthquake ruptures 一次地震一旦发生，就会出现这么一些问题：它将在哪里结束？地震的强度会有 多大？对22次历史上的走滑地震（第一次是1857年发生在加州圣安德烈斯断层的 地震，最后一次是2002年发生在阿拉斯加德纳里的一次地震）的表面断裂痕迹图 所做的分析表明，断裂终点经常与断层阶或活跃断层痕迹终点是一致的，而且一 个长度超多3、4公里的断层阶会将一次地震断裂有效终至在其轨迹中。这些发现 对于地震威胁分析的意义在于，它们能够大致预测已知活跃断层上未来地震的强 度最大能有多大。（Letter p. 358; News and Views） 遏制生物入侵的可能办法（A moth in the country） Allee effects and pulsed invasion by the gypsy moth 欧亚舞毒蛾（gypsy moth）自1869年偶然进入美国后在整个美国的扩散，是人们 最为熟悉的、最有戏剧性的关于生物入侵的例子之一。这样的入侵是对世界生态 系统稳定性的一大威胁。Johnson等人以舞毒蛾入侵为模型，发现Allee效应（低 密度时种群数量增长速度降低的效应）与生境不均衡性的组合足以引起所观测到 的周期性的入侵事件。这意味着，应当有可能通过抑制林场边界处种群周期的峰 值来减缓舞毒蛾和其他物种的入侵。（Letter p. 361） 控制视觉稳定性的一个可能机制（Wandering eyes） Influence of the thalamus on spatial visual processing in frontal cortex 当我们在看一个场景时，我们的眼睛从一个位置向另一个位置移动，而我们对该 场景的感觉却仍然是稳定的。Marc Sommer 和 Robert Wurtz 报告了一种有可能 控制这种感知稳定性的机制。该机制涉及一个大脑回路，它将关于眼睛快速移动 的信息通过丘脑从中脑传递给额叶皮质，在此，神经细胞改变它们的接受场，来 预期它们的效应。（Letter p. 374） H5N1病毒的Haemagglutin上的两处突变（Pandemic potential） Haemagglutinin mutations responsible for the binding of H5N1 influenza A viruses to human-type receptors 在亚洲、欧洲和非洲流行的H5N1禽流感病毒不能与人类细胞受体结合的事实，帮 助防止了该病毒引起一场这种疾病的人类变种的全球大流行。现在，对从被感染 的少数人（来自越南和泰国）身上分离出的H5N1病毒所做的一项研究工作，在结 合受体的病毒Haemagglutin的第182号位置和第192号位置发现了两处突变，这两 处突变使其与人类和禽类受体都能结合。这些突变也许可用作分子标记，来评估 H5N1野外分离种的流行潜力。（Letter p. 378） 蛋白相互作用的核磁共振观测研究（Close encounters） Visualization of transient encounter complexes in protein–protein association 大量生物过程中涉及蛋白-蛋白相互作用，尽管X-射线晶体学方法和核磁共振光 谱方法可用来研究一种复合物中的两个（或更多）蛋白，但难以确定这两个蛋白 在形成该最终复合物之前是怎样相互作用的。现在，研究人员利用核磁共振光谱 方法，对细菌磷酸转移酶体系（enzyme I的N-端区域和phosphocarrier蛋白 HPr）中的第一种二元复合物的瞬态的、非特定结合的复合分子组合体进行了直 接观测，所取得的一项重要发现是，这些被称为“encounter complexes”的复 合物的分布与蛋白表面上的静电电势相关联。（Letter p. 383; News and Views） mRNA动态的首次实验观测（Getting the message） Structural basis for messenger RNA movement on the ribosome 转位是核糖体功能的最重要特征之一，而此前，一直没有发现这个过程中关于 mRNA运动的结构信息。现在，Yusupova等人描述了当从初始状态转变为后初始状 态时在一个3'-5'方向上的mRNA转动和运动。这是对mRNA动态的首次实验观测， 它对了解转位机制将具有广泛的意义。（Letter p. 391） |
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ningkeqing
木虫 (正式写手)
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---------------------- NEWS AND VIEWS ---------------------- Evolutionary biology: Ancient genomics is born The reality of a complete Neanderthal genome draws near, as two papers report the sequencing of large amounts of Neanderthal DNA. The results will help to answer some central questions on human evolution. David M. Lambert and Craig D. Millar 10.1038/444275a http://www.nature.com/nature/journal/v444/n7117/full/444275a.html Seismology: Greatness thrust upon them The latest research seems to imply that all earthquakes are born equal. But combining that insight with earlier, seemingly contradictory, work could help us to tell which tremors grow to become more equal than others. James F. Dolan 10.1038/444276a http://www.nature.com/nature/journal/v444/n7117/full/444276a.html 50 & 100 Years Ago 10.1038/444277a http://www.nature.com/nature/journal/v444/n7117/full/444277a.html Cell biology: Brief encounters bolster contacts Molecules often work together in complexes to carry out their functions in the cell. But how do they get together in such a dynamic environment? A structural study follows proteins as they meet their partners. Tom L. Blundell and Juan Fernandez-Recio 10.1038/nature05306 http://www.nature.com/nature/jou ... ll/nature05306.html Medicine: Grapes versus gluttony A compound found in red grapes called resveratrol improves the health and lifespan of mice on a high-calorie diet. This is potentially good news for overweight humans. Does it bode well for the rest of us too? Matt Kaeberlein and Peter S. Rabinovitch 10.1038/nature05308 http://www.nature.com/nature/jou ... ll/nature05308.html Fluid dynamics: Spinning discs in the lab What causes gas to be drawn in towards black holes, rather than remain in a stable orbit as planets do around the Sun? A laboratory result indicates that something more than just hydrodynamics must be at work. Steven A. Balbus 10.1038/444281a http://www.nature.com/nature/journal/v444/n7117/full/444281a.html Environmental chemistry: Browning the waters Levels of dissolved organic carbon in British streams and lakes have risen over the past two decades. It might be a downstream effect of decreased acid rain ― but isolating single factors is notoriously difficult. Nigel Roulet and Tim R. Moore 10.1038/444283a http://www.nature.com/nature/journal/v444/n7117/full/444283a.html ---------------------- BRIEF COMMUNICATIONS ---------------------- Upper Palaeolithic infant burials Thomas Einwogerer et al. 10.1038/444285a Abstract: http://www.nature.com/nature/journal/v444/n7117/abs/444285a. html Article: http://www.nature.com/nature/journal/v444/n7117/full/444285a. html Materials: Carbon nanotubes in an ancient Damascus sabre M. Reibold et al. 10.1038/444286a Abstract: http://www.nature.com/nature/journal/v444/n7117/abs/444286a. html Article: http://www.nature.com/nature/journal/v444/n7117/full/444286a. html BRIEF COMMUNICATIONS ARISING Earth science: Palaeo-altimetry of Tibet Peter Molnar, Gregory A. Houseman and Philip C. England 10.1038/nature05368 Abstract: http://www.nature.com/nature/jou ... bs/nature05368.html Article: http://www.nature.com/nature/jou ... ll/nature05368.html Earth science: Palaeo-altimetry of Tibet (reply) D. B. Rowley and B. S. Currie 10.1038/nature05369 Abstract: http://www.nature.com/nature/jou ... bs/nature05369.html Article: http://www.nature.com/nature/jou ... ll/nature05369.html ---------------------- INSIGHT ---------------------- INTRODUCTION Chemical sensing I-han Chou, Tanguy Chouard, John E. Spiro and Lesley Anson 10.1038/444287a http://www.nature.com/nature/journal/v444/n7117/full/444287a.html REVIEW ARTICLE The receptors and cells for mammalian taste Jayaram Chandrashekar, Mark A. Hoon, Nicholas J. P. Ryba and Charles S. Zuker 10.1038/nature05401 Abstract: http://www.nature.com/nature/jou ... bs/nature05401.html Article: http://www.nature.com/nature/jou ... ll/nature05401.html Comparative chemosensation from receptors to ecology Cornelia I. Bargmann 10.1038/nature05402 Abstract: http://www.nature.com/nature/jou ... bs/nature05402.html Article: http://www.nature.com/nature/jou ... ll/nature05402.html Insects as chemosensors of humans and crops Wynand van der Goes van Naters and John R. Carlson 10.1038/nature05403 Abstract: http://www.nature.com/nature/jou ... bs/nature05403.html Article: http://www.nature.com/nature/jou ... ll/nature05403.html Pheromonal communication in vertebrates Peter A. Brennan and Frank Zufall 10.1038/nature05404 Abstract: http://www.nature.com/nature/jou ... bs/nature05404.html Article: http://www.nature.com/nature/jou ... ll/nature05404.html Smell images and the flavour system in the human brain Gordon M. Shepherd 10.1038/nature05405 Abstract: http://www.nature.com/nature/jou ... bs/nature05405.html Article: http://www.nature.com/nature/jou ... ll/nature05405.html ---------------------- REVIEW ---------------------- The plant immune system Jonathan D. G. Jones and Jeffery L. Dangl 10.1038/nature05286 Abstract: http://www.nature.com/nature/jou ... bs/nature05286.html Article: http://www.nature.com/nature/jou ... ll/nature05286.html ---------------------- ARTICLES ---------------------- Analysis of one million base pairs of Neanderthal DNA Richard E. Green et al. 10.1038/nature05336 Abstract: http://www.nature.com/nature/jou ... bs/nature05336.html Article: http://www.nature.com/nature/jou ... ll/nature05336.html Resveratrol improves health and survival of mice on a high-calorie diet Joseph A. Baur et al. 10.1038/nature05354 Abstract: http://www.nature.com/nature/jou ... bs/nature05354.html Article: http://www.nature.com/nature/jou ... ll/nature05354.html ---------------------- LETTERS ---------------------- Hydrodynamic turbulence cannot transport angular momentum effectively in astrophysical disks A laboratory experiment demonstrates that non-magnetic quasi-keplerian flows at Reynolds numbers up to millions are essentially steady. By ruling out purely hydrodynamic turbulence, results support magnetorotational instabilities as the likely cause of turbulence. Hantao Ji, Michael Burin, Ethan Schartman and Jeremy Goodman 10.1038/nature05323 Abstract: http://www.nature.com/nature/jou ... bs/nature05323.html Article: http://www.nature.com/nature/jou ... ll/nature05323.html Half-metallic graphene nanoribbons First-principles calculations predict that half-metallic behaviour can be found in nanometre-scale ribbons of graphene, in practically realistic conditions. The property emerges when homogeneous electric fields are applied across the zigzag-shaped edges of the graphene nanoribbons, and it can be controlled by the external electric fields. Young-Woo Son, Marvin L. Cohen and Steven G. Louie 10.1038/nature05180 Abstract: http://www.nature.com/nature/jou ... bs/nature05180.html Article: http://www.nature.com/nature/jou ... ll/nature05180.html Free-electron-like dispersion in an organic monolayer film on a metal substrate R. Temirov, S. Soubatch, A. Luican and F. S. Tautz 10.1038/nature05270 Abstract: http://www.nature.com/nature/jou ... bs/nature05270.html Article: http://www.nature.com/nature/jou ... ll/nature05270.html Flushing submarine canyons Submarine canyons can be triggered by dense shelf water cascading (that is, a relatively common process in which cold, dense water flows off the continental shelf). Thus, transport of sediment and organic material to the deep ocean may be more significant than previously believed, and any changes in cascading caused by climate change may have implications for nutrient supply to deep ocean ecosystems and carbon storage in the deep ocean. Miquel Canals et al. 10.1038/nature05271 Abstract: http://www.nature.com/nature/jou ... bs/nature05271.html Article: http://www.nature.com/nature/jou ... ll/nature05271.html Predicting the endpoints of earthquake ruptures Steven G. Wesnousky 10.1038/nature05275 Abstract: http://www.nature.com/nature/jou ... bs/nature05275.html Article: http://www.nature.com/nature/jou ... ll/nature05275.html Allee effects and pulsed invasion by the gypsy moth Biological invasions are one of the greatest threats to the stability of the world's ecosystems. This paper details that the combination of Allee effects (depressed population growth at low densities) and habitat patchiness is sufficient to cause periodic invasion pulses in the biological invasion of the gypsy moth across North America. Derek M. Johnson, Andrew M. Liebhold, Patrick C. Tobin and Ottar N. Bjornstad 10.1038/nature05242 Abstract: http://www.nature.com/nature/jou ... bs/nature05242.html Article: http://www.nature.com/nature/jou ... ll/nature05242.html A protein interaction network for pluripotency of embryonic stem cells Jianlong Wang et al. 10.1038/nature05284 Abstract: http://www.nature.com/nature/jou ... bs/nature05284.html Article: http://www.nature.com/nature/jou ... ll/nature05284.html Boc is a receptor for sonic hedgehog in the guidance of commissural axons Ami Okada et al. 10.1038/nature05246 Abstract: http://www.nature.com/nature/jou ... bs/nature05246.html Article: http://www.nature.com/nature/jou ... ll/nature05246.html Influence of the thalamus on spatial visual processing in frontal cortex Marc A. Sommer and Robert H. Wurtz 10.1038/nature05279 Abstract: http://www.nature.com/nature/jou ... bs/nature05279.html Article: http://www.nature.com/nature/jou ... ll/nature05279.html Haemagglutinin mutations responsible for the binding of H5N1 influenza A viruses to human-type receptors Shinya Yamada et al. 10.1038/nature05264 Abstract: http://www.nature.com/nature/jou ... bs/nature05264.html Article: http://www.nature.com/nature/jou ... ll/nature05264.html Visualization of transient encounter complexes in protein-protein association Chun Tang, Junji Iwahara and G. Marius Clore 10.1038/nature05201 Abstract: http://www.nature.com/nature/jou ... bs/nature05201.html Article: http://www.nature.com/nature/jou ... ll/nature05201.html Bacterial chromatin organization by H-NS protein unravelled using dual DNA manipulation A new single-molecule approach is used to examine how a nucleoid-associated protein, H-NS, functions. H-NS sits between the two DNA molecules and is aligned along the helical pitch. H-NS does not act as a barrier to RNA polymerase, and its cooperative binding ensures that H-NS is dynamic enough to accommodate the movement of DNA-associated motor proteins, but stable enough to maintain DNA loops. Remus T. Dame, Maarten C. Noom and Gijs J. L. Wuite 10.1038/nature05283 Abstract: http://www.nature.com/nature/jou ... bs/nature05283.html Article: http://www.nature.com/nature/jou ... ll/nature05283.html Structural basis for messenger RNA movement on the ribosome A series of eight crystal structures shows the changes that occur in interactions between the bacterial 70S ribosome and the messenger RNA during translation initiation, post-initiation and elongation. Certain interactions are only observed when the Shine-Dalgarno sequence is present, and the exit path of the mRNA appears to change once translation shifts from initiation to elongation mode. Gulnara Yusupova et al. 10.1038/nature05281 Abstract: http://www.nature.com/nature/jou ... bs/nature05281.html Article: http://www.nature.com/nature/jou ... ll/nature05281.html ***** Nature Copyright Macmillan Publishers Ltd 2004 Registered No. 785998 England. Nature's worldwide offices: London . Munich . New Delhi . Tokyo . San Diego . San Francisco Washington . New York ***** This message has been sent to you as a member of Nature Asia's e-mail contents service. If you wish to remove your address from our list please send a blank e- mail message to naturekcontents-off@mail-list.com. If you would like further help on adding or removing your address from our list please send a blank e-mail message to naturekcontents- help@mail- list. com. You will receive a help message by return. |
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