| 2006年10月12日 Nature中英文摘要 | | 点击： 作者： 来源： 时间： 2006-11-11 本站论坛 |
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Volume 443 Number 7112 pp605-722 (12 October 2006)
October 12, 2006
封面故事：埃塞俄比亚的狼
埃塞俄比亚狼Canis simensis是一种专门的食肉动物，只见于埃塞俄比亚7个孤立的山坳中，以啮齿动物为食。它们过着群居生活，有复杂的社会组织。1992年和2003年曾经爆发过狂犬病，使Bale山区这种狼的种群数量大大减少，现存个体少于500只。在当地进行的、作为“埃塞俄比亚狼保护计划”（）组成部分的研究工作，其内容包括采用接种免疫的办法来保护狼群，该策略有可能成为其他保护项目的一个重要模式。该策略的目的是，仅利用覆盖面较低的接种免疫方法来控制通过各分种群之间的生境走廊进行的疾病传播。该方法可降低狂犬病的爆发程度，并且应能明显增加种群的长期存活机会。（Letter p. 692）封面摄影：Martin Harvey（）
October 12, 2006
两个Bcl-2家族成员的新作用
Bcl-2家族成员是怎样调控细胞程序死亡（细胞凋亡）的是一个受到深入研究的课题。Karbowski等人发现，两个Bcl-2家族成员在健康细胞中有一个新的、未曾料到的作用。Bax 和 Bak在正常细胞中是线粒体向伸长的细管中融合所必需的。这一发现对了解Bax 和 Bak在细胞凋亡过程中所起作用有参考意义，在该过程中，它们与线粒体融合调控因子Mfn2 和 Drp1处在同一位置。
October 12, 2006
真菌独有伸长因子eEF3的晶体结构
核糖体含有三个与tRNA结合的点。A点接待前来的、酰化的tRNA；P点含有生长的氨基酸肽链要附着在其上的tRNA；去酰化的tRNA在与核糖体分离前处在E点上。对真菌来说，需要第三个伸长因子eEF3来帮助E点tRNA的释放，并允许tRNA 在A点的结合。这个现象是真菌独有的。由于eEF3是真菌独有的，它被认为是杀菌剂的一个绝好的攻击目标。Andersen等人已经确定了酵母eEF3单独存在时和在核糖体上时的晶体结构，并且分别获得了它们的冷电子显微重建结果。该成果为了解eEF3的功能提供了线索，并且为基于结构的抗菌药物的设计提供了一个出发点。
October 12, 2006
“土卫六”上为什么没有乙烷海洋？
在“卡西尼-惠更斯”探测器造访之前，行星科学家曾期望会在土星的卫星“土卫六”上找到一个由液体乙烷构成的巨大的海洋。由于在太阳系的整个生命期间都暴露于太阳紫外线下，所以“土卫六”应该能从甲烷的分解产生数量足够多的乙烷，从而形成一个范围大至整个卫星、深度达1公里的海洋。但事实上并未发现海洋，只在“土卫六”南极发现一个乙烷云和几个湖泊。Donald Hunten对“土卫六”上缺少液体乙烷这一神秘现象的解释是，乙烷在“土卫六”上丰富的烟雾颗粒上发生了冷凝，而不是在低温下冷凝成了液滴。由烟雾和甲烷构成的这种尘埃状组合（或称为smust），可能会在“土卫六”表面上形成几公里厚的沉积层。
October 12, 2006
早期宇宙的演化不存在真正的相变
粒子物理学的标准模型预测，有两个相变与早期宇宙的演化有关。第一个是量子色动力学转变，涉及将夸克结合成质子和中子的强力。尽管科学家在理论上做出了巨大的努力，这种相变的性质仍然不清楚。现在，Aoki等人报告了在演算上难度很大的计算结果，这些结果表明，不存在真正的相变；相反，实际发生的是一个分析过渡（analytic crossover），涉及快速、连续的温度变化，而不是突变。这意味着，我们将难以从天文观测结果找到关于相变的实验证据。
October 12, 2006
有氧光合作用与大气中氧含量
地球上大气氧水平首次显著增加（被称为Great Oxidation）被认为发生在有氧光合作用出现之后至少3亿年，但关于这一时间延迟的原因仍然不确定。Goldblatt等人利用一个关于全球氧化-还原体系的新的概念模型发现，在有氧光合作用出现之后，大气氧水平有可能保持在一个较低的或较高的稳定状态。Great Oxidation可能是由一个较小的环境变化诱发的这些状态之间的一个转变。该模型表明，单独有氧光合作用一个因素不足以造成一个氧含量丰富的大气层。所以，在没有其他因素的情况下，地球的大气层也许只含有几个ppm的氧，不到我们今天所习惯的大气氧含量的21%。同样，我们可以比较有把握地认为，有氧光合作用是有可能在大气中氧含量较低的行星上出现的。
October 12, 2006
哺乳动物的定数
哺乳动物物种在这个地球上似乎有一个定数，即存在大约250万年后就会灭绝。物种为什么具有这样一个特征的预期寿命是一个令人困惑的事情。对来自西班牙的一个非常长（2200万年）的、详细的啮齿类动物化石序列所做的研究表明，物种的出现与消失集中在所谓的“周转事件”（turnover events）中，这些事件以大约100万至240万年的固定周期发生。这些周期的持续时间和发生时间，相应于地球-太阳距离变化周期的持续时间和发生时间、以及被认为造成Milankovitch气候周期的地轴倾斜度变化周期的持续时间和发生时间。将物种灭绝周期与气候联系起来的结果，与1985年由耶鲁大学古生物学家Elisabeth Vrba提出的“周转脉冲”假说是一致的，该假说是通过假设在环境变化诱发迅速的物种灭绝和物种形成之前物种保持稳定来解释物种存活时间的。
October 12, 2006
与昆虫眼睛演化有关的基因
Kevin Moses在一篇“News and Views”文章中说，我们并不能经常看到演化是怎样发挥作用的。他所指的是，从古代苍蝇和如蜜蜂及甲虫等一些现代昆虫的复眼（在这种复眼中，感光细胞或称感杆是融合在一起、作为一个整体发挥作用的）向果蝇和家蝇眼睛中那种类型的结构（其中的感杆是分开的、独立发挥作用的，所以晶状体的每个面感觉到的是七个点的光，而不是一个点的光）的转变。Zelhof等人识别出了感杆组合体中所涉及的三个基因。其中一个名叫spacemaker的基因的丢失，可将果蝇的开放体系转变成一个封闭的或融合的感杆体系。
October 12, 2006
控制脑部血流量的另一机制
非入侵性成像技术是通过探测向活跃的神经细胞供应额外的葡萄糖和氧的血流量的增加来显示大脑中活跃部分的。此前，人们一直假设，血流量是由被称为细动脉（arteriole）的大血管周围的平滑肌的收缩来控制的。现在，研究人员发现了另一层次的血流量控制，是在细动脉的下游进行的。这种控制是由被称为“周围细胞”的小细胞施加的，它们包裹在靠近活跃神经细胞的毛细管周围。“周围细胞”是通过挤压毛细管以减少通过它们的血流量来发挥作用的，它们很可能与在脑成像技术中所探测到的信号有关，并且还可能为脑血流疾病的治疗提供一个目标。
October 12, 2006
与食欲有关的分子
食欲至少部分是在视丘下部调控的，这个部位是大脑中将神经系统和内分泌系统联系起来的区域。现在，对调控食欲的分子所进行的一次筛选工作，发现蛋白nucleobindin 2的一部分（被称为nesfatin-1）是在视丘下部生成的一种饱度分子。当将nesfatin-1注射进脑中时，大鼠的进食量就会减少，体重就会下降。当将nesfatin-1阻断时，动物就会吃得更多。因此，nesfatin-1是减肥药物的一个可能的作用目标。
October 12, 2006
Aprataxin蛋白在DNA修复中的作用
罕见的神经退化疾病“共济失调性眼球运动功能丧失症-1”是由aprataxin蛋白的突变引起的。以前的研究工作表明，aprataxin与RNA修复蛋白有关，但它在DNA修复中是直接还是间接发挥作用的却不知道。现在，用含有正常和突变aprataxin蛋白的纯化的提取物所做的实验表明，aprataxin的作用是帮助将由活性氧分子或自由基诱导的DNA中的单链缺口连接在一起。具体来说，它是将腺苷酸（adenylate）从DNA其中一端去掉，并允许其再缝合回去。这表明，“共济失调性眼球运动功能丧失症-1”中所出现的神经退化，可能是由神经细胞的DNA中未修复的损伤的逐渐积累造成的。
Contents
Editorials
A global folly p605
If not a global non-nuclear proliferation regime based on international treaties, then what?
doi:10.1038/443605a
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Forgotten plights p605
Scientists' human-rights groups deserve stronger backing.
doi:10.1038/443605b
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Ambassador for Earth p606
Is it time for SETI to reach out to the stars?
doi:10.1038/443606a
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Top of pageResearch Highlights
Research highlights p608
doi:10.1038/443608a
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Top of pageNews
The fizzle heard around the world p610
North Korea's nuclear test raises more questions than answers. Despite the small size of the blast, Jim Giles and Geoff Brumfiel get little reassurance from the weapon watchers.
doi:10.1038/443610a
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Protests mount against Libyan trial p612
Support grows for accused medics.
Declan Butler
doi:10.1038/443612a
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Nobel prize blurs boundaries p615
"But is it chemistry?" ask chemists.
Katharine Sanderson
doi:10.1038/443615a
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Intelligent design gets political p615
Teaching creationism becomes an election issue in Michigan.
Geoff Brumfiel
doi:10.1038/443615b
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Sidelines p616
doi:10.1038/443616a
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Hard-hitting endeavour captures Ig Nobel p616
Woodpecker research flies away with alternative prize.
Steve Nadis
doi:10.1038/443616b
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News in brief p618
doi:10.1038/443618a
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Correction p619
doi:10.1038/443619a
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Top of pageBusiness
Hell on no wheels p621
The crash of a demonstration train in Germany casts a shadow on magnetic levitation technology. Ned Stafford reports.
doi:10.1038/443621a
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Top of pageNews Features
Oceanography: The real sea change p622
What can pirates' journals and centuries-old cookbooks teach modern-day ecologists? Mark Schrope meets the researchers who trawl history books for deeper insights into marine ecosystems.
doi:10.1038/443622a
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AIDS in Africa: A question of trust p626
AIDS treatment in South Africa is often a tug-of-war between clinicians and traditional healers. Natasha Bolognesi meets a woman who is uniquely qualified to heal the rift.
doi:10.1038/443626a
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Depression: Comfortably numb p629
It started life as an anaesthetic, then became a psychedelic club drug. Now researchers think ketamine could hold the key to understanding and treating depression, says Erika Check.
doi:10.1038/443629a
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Top of pageCorrespondence
Biochemistry has outgrown its traditional boundaries p632
Chris Kirk
doi:10.1038/443632a
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Videos have starring role to play in protocol sharing p632
Matias Pasquali
doi:10.1038/443632b
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Consistency tests establish empirical generalizations p632
Brian D. Haig
doi:10.1038/443632c
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Chimp comparisons won't explain human evolution p632
Robert Barton
doi:10.1038/443632d
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Science prediction rate would be good in gambling p632
Kenneth D. Pimple
doi:10.1038/443632e
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Top of pageBooks and Arts
Evolution's highest branches p633
An intriguing tour around and, especially, up the tree of life.
Matthew A. Wills reviews Creatures of Accident: The Rise of the Animal Kingdom by Wallace Arthur
doi:10.1038/443633a
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Psychoneuroindoctrinology p634
Rebecca M. Young and Evan Balaban review The Female Brain by Louann Brizendine
doi:10.1038/443634a
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A comprehensive medical history p635
Andreas-Holger Maehle reviews The Western Medical Tradition: 1800 to 2000 by W. F. Bynum, Anne Hardy, Stephen Jacyna, Christopher Lawrence and E. M. (Tilli) Tansey
doi:10.1038/443635a
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The background buzz p635
P. V. E. McClintock reviews Noise by Bart Kosko
doi:10.1038/443635b
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Science in culture: A modern megalith p636
Mariko Mori's glass sculpture responds to the death of stars.
Martin Kemp
doi:10.1038/443636a
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Top of pageNews and Views
Particle physics: Did the big bang boil? p637
Standard theories tell us that, at some point in the Universe's evolution, free quarks and gluons must have become bound together into the hadronic matter we see today. But was this transition abrupt or smooth?
Frank Wilczek
doi:10.1038/443637a
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Evolutionary biology: Fly eyes get the whole picture p638
The compound eyes of ancestral flies picked up only one picture point in each facet. The evolution of a means to split up the light-sensitive cells increased this number to seven, boosting the eye's resolution greatly.
Kevin Moses
doi:10.1038/nature05209
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50 & 100 years ago p639
doi:10.1038/443639a
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Physical chemistry: Seeds of phase change p641
An effective but counter-intuitive trick to obtain highly ordered protein crystals is to 'seed' particles on disordered, porous surfaces. Computer simulations provide an explanation for the success of this strategy.
Daan Frenkel
doi:10.1038/443641a
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Neuroscience: Controlled capillaries p642
The finest scale of blood flow through the brain occurs in capillaries. Suspicions that capillary flow is regulated by cells that put the squeeze on these vessels are now borne out by detailed experiments.
Brian A. MacVicar and Michael W. Salter
doi:10.1038/443642a
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Developmental biology: A change of heart p642
Helen Dell
doi:10.1038/443642b
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Earth sciences: Ups and downs of ancient oxygen p643
The latest models suggest that atmospheric oxygen could have fluctuated between high and low concentrations once photosynthesis had evolved. But does the geological evidence really support this?
James F. Kasting
doi:10.1038/443643a
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Ecology: Moving to the ideal free home p645
Pike move between two basins of a British lake to maximize their evolutionary fitness. This adaptive behaviour suggests that habitat selection is more significant in population dynamics than was thought.
Douglas W. Morris
doi:10.1038/443645a
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Cell biology: Mitochondria shape up p646
Mitochondria are central to the process of programmed cell death that kills damaged or superfluous cells. Surprisingly, components of the death machinery turn out to be essential for keeping these organelles in shape.
Barbara Conradt
doi:10.1038/443646a
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Top of pageBrief Communications
An accessory chromophore in red vision p649
The rods in salamanders' retinas can co-opt a molecule derived from chlorophyll to detect red light.
T. Isayama, D. Alexeev, C. L. Makino, I. Washington, K. Nakanishi and N. J. Turro
doi:10.1038/443649a
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Corrigendum p649
doi:10.1038/443649b
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Top of pageReview
Phosphoinositides in cell regulation and membrane dynamics p651
Gilbert Di Paolo and Pietro De Camilli
doi:10.1038/nature05185
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Top of pageArticles
Role of Bax and Bak in mitochondrial morphogenesis p658
Mariusz Karbowski, Kristi L. Norris, Megan M. Cleland, Seon-Yong Jeong and Richard J. Youle
doi:10.1038/nature05111
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Structure of eEF3 and the mechanism of transfer RNA release from the E-site p663
Christian B. F. Andersen, Thomas Becker, Michael Blau, Monika Anand, Mario Halic, Bharvi Balar, Thorsten Mielke, Thomas Boesen, Jan Skov Pedersen, Christian M. T. Spahn, Terri Goss Kinzy, Gregers R. Andersen and Roland Beckmann
doi:10.1038/nature05126
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Top of pageLetters
The sequestration of ethane on Titan in smog particles p669
D. M. Hunten
doi:10.1038/nature05157
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Observation of strong coupling between one atom and a monolithic microresonator p671
Takao Aoki, Barak Dayan, E. Wilcut, W. P. Bowen, A. S. Parkins, T. J. Kippenberg, K. J. Vahala and H. J. Kimble
doi:10.1038/nature05147
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The order of the quantum chromodynamics transition predicted by the standard model of particle physics p675
Y. Aoki, G. Endrdi, Z. Fodor, S. D. Katz and K. K. Szabó
doi:10.1038/nature05120
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Origin of the dielectric dead layer in nanoscale capacitors p679
Massimiliano Stengel and Nicola A. Spaldin
doi:10.1038/nature05148
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Bistability of atmospheric oxygen and the Great Oxidation p683
Colin Goldblatt, Timothy M. Lenton and Andrew J. Watson
doi:10.1038/nature05169
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Long-period astronomical forcing of mammal turnover p687
Jan A. van Dam, Hayfaa Abdul Aziz, M. Ángeles Álvarez Sierra, Frederik J. Hilgen, Lars W. van den Hoek Ostende, Lucas J. Lourens, Pierre Mein, Albert J. van der Meulen and Pablo Pelaez-Campomanes
doi:10.1038/nature05163
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Low-coverage vaccination strategies for the conservation of endangered species p692
D. T. Haydon, D. A. Randall, L. Matthews, D. L. Knobel, L. A. Tallents, M. B. Gravenor, S. D. Williams, J. P. Pollinger, S. Cleaveland, M. E. J. Woolhouse, C. Sillero-Zubiri, J. Marino, D. W. Macdonald and M. K. Laurenson
doi:10.1038/nature05177
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Transforming the architecture of compound eyes p696
Andrew C. Zelhof, Robert W. Hardy, Ann Becker and Charles S. Zuker
doi:10.1038/nature05128
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Bidirectional control of CNS capillary diameter by pericytes p700
Claire M. Peppiatt, Clare Howarth, Peter Mobbs and David Attwell
doi:10.1038/nature05193
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Fast neurotransmitter release triggered by Ca influx through AMPA-type glutamate receptors p705
Andrés E. Chávez, Joshua H. Singer and Jeffrey S. Diamond
doi:10.1038/nature05123
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Identification of nesfatin-1 as a satiety molecule in the hypothalamus p709
Shinsuke Oh-I, Hiroyuki Shimizu, Tetsurou Satoh, Shuichi Okada, Sachika Adachi, Kinji Inoue, Hiroshi Eguchi, Masanori Yamamoto, Toshihiro Imaki, Koushi Hashimoto, Takafumi Tsuchiya, Tsuyoshi Monden, Kazuhiko Horiguchi, Masanobu Yamada and Masatomo Mori
doi:10.1038/nature05162
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The neurodegenerative disease protein aprataxin resolves abortive DNA ligation intermediates p713
Ivan Ahel, Ulrich Rass, Sherif F. El-Khamisy, Sachin Katyal, Paula M. Clements, Peter J. McKinnon, Keith W. Caldecott and Stephen C. West
doi:10.1038/nature05164
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Top of pageAddendum
Sustainability of three apple production systems p717
John P. Reganold, Jerry D. Glover, Preston K. Andrews and Herbert R. Hinman
doi:10.1038/nature05188
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Top of pageCorrigendum
Structure of the E. coli protein-conducting channel bound to a translating ribosome p718
Kakoli Mitra, Christiane Schaffitzel, Tanvir Shaikh, Florence Tama, Simon Jenni, Charles L. Brooks, Nenad Ban and Joachim Frank
doi:10.1038/nature05086
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Top of pageNaturejobs
Prospect
Prospects p719
Adaptability can trump planning in career considerations.
Paul Smaglik
doi:10.1038/nj7112-719a
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Career Views
King Holmes, director, Department of Global Health, University of Washington, Seattle p720
New public health challenges for King Holmes at the University of Washington.
Virginia Gewin
doi:10.1038/nj7112-720a
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More than one route to PhD success p720
Two researchers offer their take on how to succeed as a PhD student.
Sarah Bekessy and Brendan Wintle
doi:10.1038/nj7112-720b
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Lab life or love life? p720
Sometimes dedication in the lab leaves little time for personal relationships.
Mhairi Dupré
doi:10.1038/nj7112-720c
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Top of pageFutures
Picasso's cat p722
The editor's wavefunction collapses.
Ron Collins
doi:10.1038/443722a
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