| 2006年06月29日 Nature中英文摘要 | | 点击： 作者： 来源： 时间： 2006-11-12 本站论坛 |
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Volume 441 Number 7097 pp1027-1194 28 June 2006
封面故事：血液或骨髓细胞能形成卵细胞的结论受到质疑
几十年来，生物学家相信，雌性哺乳动物出生时其卵巢中就储存了可供一生使用的卵细胞。这一教条最近受到来自哈佛大学同一实验室的两项研究工作的挑战。其中的一项研究表明，雌性的性腺在整个成年期内都保持再生卵细胞的能力，另一项研究的结果更令人吃惊，它表明，卵细胞可由来自血液或骨髓的细胞形成。后一项研究引起人们很多注意，人们关注的焦点是，该结果说明有可能恢复进行化疗或过早绝经的妇女的生育能力。所以，当一篇对这些结论中的一些内容表示怀疑的论文6月14日在Nature杂志网上发表后，再次引起人们对该话题进行激烈讨论。该论文来自哈佛大学另一小组，现在以印刷形式出现。这篇论文描述了两只小鼠的循环系统发生合并的实验。没有证据表明骨髓细胞或任何其他循环细胞能形成成熟卵细胞。就算通过血液进入卵巢的细胞，其表现出的也是正常血液白细胞的性质。
中子星的“软”、“硬”状态方程
中子星EXO 0748–676作为一个低质量的X-射线双星体系是不寻常的，其不寻常之处在于，红移的氧和铁光谱线存在于由其表面发射出的光中。中子星中的物质极其致密，其所处状态与早期宇宙或地球上的实验体系中的状态很不相同，天文观测是探索这些物质的惟一方式。来自EXO 0748–676的多种信号为我们提供了进行这种研究的依据。来自RXTE、EXOSAT 和 XMM-Newton卫星的数据被用来计算该恒星的质量和半径，所获得的结果排除了中子星的所有“软”状态方程。在一个给定的温度和密度下的一个“软”状态方程所给出的压力要低于一个“硬”方程所给出的压力。如果EXO 0748–676是典型的中子星的话，那么奇异的凝聚态物质和不受约束的夸克可从中子星的中心排除。而相对比较传统的状态方程将可适用于它，它就相当于一个由中子和质子构成的体系。
“BKT转变”在二维环境中被首次直接观测到
一个二维环境中的物理现象与我们在三维世界中所观察到的物理现象是很不相同的。如果维数减少，热波动会破坏一个体系的空间秩序，多数相变（如产生铁磁现象的相变等）将不会发生。但一种特定类型的相变（涉及到旋涡的配对）的确存在于二维环境中。30年前由Berezinskii、Kosterlitz 和 Thouless 首次预测的“BKT转变”，现在已首次在一个由超冷铷原子构成的一种平面气体中被直接观测到。
多孔锗材料已经问世
“多孔”硅在15年前首次问世后被誉为微电子行业的一种激动人心的新材料。它的一系列性能与晶体硅的性能形成互补。现在，微电子行业中另一种重要元素锗也受到人们的密切关注。在本期Nature上，两个小组报告了用一种被称为表面活性剂模板的方法来合成具有有序微孔的锗的研究工作：一个小组获得的是立方形的，另一个小组获得的是六边形的。最初的研究表明，同多孔硅一样，这些材料也具有与其大体积形式不同的性能。
大规模板块变形的速度
在构造板块在大陆下相遇的地方，这些板块会在数百、数千公里宽的范围内发生变形。驱动这种大尺度扩散型大陆变形的作用力仍然是一个谜。美国西部内华达山脉和落基山脉之间盆地和山脉区是发生这种大规模变形的一个地区，1996年以来，科学家利用一个基于GPS的网络对其进行了仔细观测。最新数据表明，与以前的理解相反的是，变形速度一直在短的时间尺度（1年）上发生变化。
地震能增强地壳渗透性
由地震所造成的振动除了对人、建筑物和景观有明显影响外，还能改变地壳的渗透性。渗透性之所以重要，是因为它控制流体在地下的运动，而对此我们却很少进行长期连续测定。南加州20年时间中（在此期间曾发生7次地震）一项关于水井水位的记录表明，地震使渗透性有明显提高：在其中的两口井中，渗透性最多提高了3倍。所获得数据对水文监测、水库工程和地震物理具有潜在的深远意义。例如，所观测到的渗透性提高3倍的结果便暗示了一种主动提高油气田渗透性的方法。
保护生境和物种多样性有利于生态系统稳定
研究人员在一个由以海草为食的甲壳动物构成的实验性集合群落(metacommunity)中，对物种迁移（包括内迁和外迁）等扩散过程对一个生态系统环境退化的影响进行了研究。该实验所涉及的是一个通过物理手段分隔开来、但却通过扩散联系在一起的植物和动物群落，而不是通常的封闭系统。该研究所获得的一些发现是惊人的。例如，如果允许食草者在它们所吃的一片片海草中运动，并选择要吃哪片海草，那么生物多样性对生态系统生产力的影响就会降低。但总的结论是，保护生境和物种的多样性，可以使生态系统随着时间的推移保持稳定。
蛋白体调控神经元中联会作用的过程
蛋白体在细胞代谢中的重要性，因2004年关于“泛素-蛋白体”系统的研究工作获得诺贝尔奖而得到承认。现在，用延时拍摄方法拍摄的非凡影像，让我们有机会一瞥蛋白体在其重要角色之一（即作为神经元中联会作用的调控因子）中正在发挥作用的情况。值得注意的是，蛋白体在去极化后向树状脊中运动，并被束缚在那里。单个联会蛋白的运动以前曾经被观测到过，但观测到一个主要细胞生物机器向脊中运动、去改变突触却是新发现，并且可能是反直觉的。这里，蛋白体的作用似乎是让突触中的蛋白在原地发生特定的降解，而不是在远处进行例行的垃圾处理。
与帕金森氏症有关的两个基因
PINK1基因最近被发现与常染色体隐性青少年帕金森氏症有关。两个研究小组对果蝇中相应的基因进行了研究，发现它在活体中局限于线粒体中，对线粒体的功能非常重要。它还在遗传上与parkin基因发生相互作用，后者是与家族性帕金森氏症有关的另一个基因，为一种E3泛素连接酶编码。果蝇的pink1-parkin通道应能为研究神经退化的分子机制、为可能的治疗方案筛选药物提供一个强大的工具。
一种riboswitche的三维结构
基因通常是由响应于细胞信号的蛋白因子打开或关闭的。最近关于 riboswitches（一些信使RNA 内的调控元素）的发现证明，RNA分子还能感知重要代谢物和控制基因的存在。两项结构研究为了解riboswitch系统提供了新线索。Serganov等人利用X-射线衍射确定来自大肠杆菌的一个riboswitch的三维结构，该riboswitch结合在其目标、即一种维生素B1衍生物上。这些发现显示了RNA是如何折叠形成一个适合其目标的形状、尺寸非常精确的袋子的，也显示了抗硫胺素（pyrithiamine）是如何通过欺骗该riboswitch来发挥作用的。这个结果为我们提供了一个设计以riboswitches为作用目标的抗细菌和抗真菌的化合物的新的药物设计策略。Montange 和 Batey解决了结合在S-adenosyl methionine上的一个细菌riboswitch RNA的结构。这一RNA复杂的折叠结构显示了该配体的结合何以导致下游区域的二级结构的改变，而这种改变又会阻止进一步的转录。
Contents
Editorials
Science in the Arab world p1027
The immense challenges facing those who attempt to support research in developing countries are compounded by political turmoil in the Middle East.
doi:10.1038/4411027a
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A tale of one world p1028
Celebrating science on the solstice.
doi:10.1038/4411028a
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Action stations p1028
The time for sitting on flu data is over.
doi:10.1038/4411028b
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Research Highlights
Research highlights p1030
doi:10.1038/4411030a
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News
Academy affirms hockey-stick graph p1032
But it criticizes the way the controversial climate result was used.
Geoff Brumfiel
doi:10.1038/4411032a
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Experts comb tropics for clues to vCJD p1033
Fate of ex-cannibals suggests prion diseases can incubate for half a century.
Helen Pearson
doi:10.1038/4411033a
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Sidelines p1034
doi:10.1038/4411034a
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Hungary's science academy slammed as 'obsolete' p1034
Government and researchers complain of old-fashioned and discriminatory policies.
Quirin Schiermeier
doi:10.1038/4411034b
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Hunt for AIDS vaccine tackles genomes p1034
Systematic search for HIV immunity proposed.
Erika Check
doi:10.1038/4411034c
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Scientists become targets in Iraq p1036
Violence is common currency in Iraq, but one group is increasingly and persistently singled out — academics. Declan Butler reports on the risks run by researchers as they struggle to pursue their studies.
doi:10.1038/4411036a
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Human eggs supply 'ethical' stem cells p1038
Use of parthenogenetic lines could side step moral issues.
Jo Marchant
doi:10.1038/4411038a
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News in brief p1039
doi:10.1038/4411039a
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Correction p1039
doi:10.1038/4411039a
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News Feature
Science on the solstice p1040
Every day, all over the planet and beyond it, scientists try to make sense of the world in which they live. Here we present a composite picture of just one day — 21 June 2006, the Northern summer solstice.
doi:10.1038/4411040a
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Business
Assault on batteries p1046
Miniature fuel cells are being developed as an alternative way to power portable devices. But they're not ready yet, as Kurt Kleiner reports.
doi:10.1038/4411046a
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In brief p1047
doi:10.1038/4411047a
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Market watch p1047
Colin Macilwain
doi:10.1038/4411047b
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Correspondence
Seeing is believing as brain reveals its adaptability p1048
Oliver Sacks and Ralph M. Siegel
doi:10.1038/4411048a
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Discrete reminder about Weismann's discovery p1048
William L. Abler
doi:10.1038/4411048b
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Researchers frustrated by lack of input to NIH policy p1048
Don C. Rockey
doi:10.1038/4411048c
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Public will fear biological accidents, not just attacks p1048
Markus Schmidt
doi:10.1038/4411048d
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Correction p1048
doi:10.1038/4411048e
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Books and Arts
Faster, better, healthier p1049
An exploration of how genetics has influenced many aspects of life.
Michael A. Goldman reviews The Strongest Boy In The World: How Genetic Information Is Reshaping Our Lives by Philip R. Reilly
doi:10.1038/4411049a
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A glimpse of the early Universe p1050
Patrick Petitjean reviews Chasing Hubble's Shadows: The Search for Galaxies at the Edge of Time by Jeff Kanipe
doi:10.1038/4411050a
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A question of taste p1051
John Piggott reviews Molecular Gastronomy: Exploring the Science of Flavor by Hervé This
doi:10.1038/4411051a
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Correction p1051
doi:10.1038/4411051b
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News and Views
Quantum physics: Atomic gas in flatland p1053
The observation of Bose–Einstein condensation in an atomic gas was a seminal result. Two-dimensional gases are more complex, and an intriguing interference experiment has exposed a different superfluid transition.
Tilman Esslinger and Gianni Blatter
doi:10.1038/4411053a
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Structural biology: RNA switches function p1054
Proteins are not the only regulators of metabolite synthesis — some RNA molecules do it too. These RNAs lack chemical diversity, so how do we explain the variety of their respective substrates?
Steve Reichow and Gabriele Varani
doi:10.1038/4411054a
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Materials science: Germanium takes holey orders p1055
Soap-like molecules serve as a scaffold for remarkably well-ordered, porous germanium skeletons. The nanometre-sized features of these semiconductor frameworks confer unique optical and electronic properties.
Andreas Stein
doi:10.1038/4411055a
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Astronomy: Supernovae brought to light p1056
The existing catalogue of Galactic supernova remnants contains only a small fraction of the true number of these stellar explosions. A different observational technique is being employed to find the missing ones.
Carl Heiles
doi:10.1038/4411056a
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Neurodegenerative disease: Pink, parkin and the brain p1058
Dysfunctions in a number of cellular pathways can cause Parkinson's disease. Fruitflies with mutations in a protein called PINK1 show that there might be some unsuspected interplay between two such pathways.
Leo Pallanck and J. Timothy Greenamyre
doi:10.1038/4411058a
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Insight: Stem-cell Biology - Produced with support from:
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Insight: Stem-cell Biology
Stem-cell Biology p1059
Natalie DeWitt
doi:10.1038/4411059a
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A glossary for stem-cell biology p1060
Austin Smith
doi:10.1038/nature04954
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Nuclear reprogramming and pluripotency p1061
Konrad Hochedlinger and Rudolf Jaenisch
doi:10.1038/nature04955
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Asymmetric and symmetric stem-cell divisions in development and cancer p1068
Sean J. Morrison and Judith Kimble
doi:10.1038/nature04956
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The stem-cell niche as an entity of action p1075
David T. Scadden
doi:10.1038/nature04957
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Stem cells, ageing and the quest for immortality p1080
Thomas A. Rando
doi:10.1038/nature04958
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Generation of neuronal variability and complexity p1087
Alysson R. Muotri and Fred H. Gage
doi:10.1038/nature04959
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Stem cells for the treatment of neurological disorders p1094
Olle Lindvall and Zaal Kokaia
doi:10.1038/nature04960
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Potential of stem-cell-based therapies for heart disease p1097
Deepak Srivastava and Kathryn N. Ivey
doi:10.1038/nature04961
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Stem-cell therapies for blood diseases p1100
Claudio Bordignon
doi:10.1038/nature04962
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Articles
Genetic evidence for complex speciation of humans and chimpanzees p1103
Nick Patterson, Daniel J. Richter, Sante Gnerre, Eric S. Lander and David Reich
doi:10.1038/nature04789
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Ovulated oocytes in adult mice derive from non-circulating germ cells p1109
Kevin Eggan, Sara Jurga, Roger Gosden, Irene M. Min and Amy J. Wagers
doi:10.1038/nature04929
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Letters
Soft equations of state for neutron-star matter ruled out by EXO 0748 - 676 p1115
F. Özel
doi:10.1038/nature04858
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Berezinskii–Kosterlitz–Thouless crossover in a trapped atomic gas p1118
Zoran Hadzibabic, Peter Krüger, Marc Cheneau, Baptiste Battelier and Jean Dalibard
doi:10.1038/nature04851
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Mesostructured germanium with cubic pore symmetry p1122
Gerasimos S. Armatas and Mercouri G. Kanatzidis
doi:10.1038/nature04833
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Hexagonal nanoporous germanium through surfactant-driven self-assembly of Zintl clusters p1126
Dong Sun, Andrew E. Riley, Ashley J. Cadby, Erik K. Richman, Scott D. Korlann and Sarah H. Tolbert
doi:10.1038/nature04891
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Subcontinental-scale crustal velocity changes along the Pacific–North America plate boundary p1131
J. L. Davis, B. P. Wernicke, S. Bisnath, N. A. Niemi and P. Elósegui
doi:10.1038/nature04781
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Seismic waves increase permeability p1135
Jean E. Elkhoury, Emily E. Brodsky and Duncan C. Agnew
doi:10.1038/nature04798
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Diversity and dispersal interactively affect predictability of ecosystem function p1139
Kristin E. France and J. Emmett Duffy
doi:10.1038/nature04729
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Activity-dependent dynamics and sequestration of proteasomes in dendritic spines p1144
Baris Bingol and Erin M. Schuman
doi:10.1038/nature04769
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Nodulation independent of rhizobia induced by a calcium-activated kinase lacking autoinhibition p1149
Cynthia Gleason, Shubho Chaudhuri, Tianbao Yang, Alfonso Muñoz, B. W. Poovaiah and Giles E. D. Oldroyd
doi:10.1038/nature04812
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Deregulation of a Ca2+/calmodulin-dependent kinase leads to spontaneous nodule development p1153
Leïla Tirichine, Haruko Imaizumi-Anraku, Satoko Yoshida, Yasuhiro Murakami, Lene H. Madsen, Hiroki Miwa, Tomomi Nakagawa, Niels Sandal, Anita S. Albrektsen, Masayoshi Kawaguchi, Allan Downie, Shusei Sato, Satoshi Tabata, Hiroshi Kouchi, Martin Parniske, Shinji Kawasaki and Jens Stougaard
doi:10.1038/nature04862
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Mitochondrial dysfunction in Drosophila PINK1 mutants is complemented by parkin p1157
Jeehye Park, Sung Bae Lee, Sungkyu Lee, Yongsung Kim, Saera Song, Sunhong Kim, Eunkyung Bae, Jaeseob Kim, Minho Shong, Jin-Man Kim and Jongkyeong Chung
doi:10.1038/nature04788
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Drosophila pink1 is required for mitochondrial function and interacts genetically with parkin p1162
Ira E. Clark, Mark W. Dodson, Changan Jiang, Joseph H. Cao, Jun R. Huh, Jae Hong Seol, Soon Ji Yoo, Bruce A. Hay and Ming Guo
doi:10.1038/nature04779
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Structural basis for gene regulation by a thiamine pyrophosphate-sensing riboswitch p1167
Alexander Serganov, Anna Polonskaia, Anh Tuân Phan, Ronald R. Breaker and Dinshaw J. Patel
doi:10.1038/nature04740
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Structure of the S-adenosylmethionine riboswitch regulatory mRNA element p1172
Rebecca K. Montange and Robert T. Batey
doi:10.1038/nature04819
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Retraction: Induction of DNA methylation and gene silencing by short interfering RNAs in human cells p1176
Hiroaki Kawasaki and Kazunari Taira
doi:10.1038/nature04952
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Technology Features
Cell sorting: Divide and conquer p1179
A key element of performing good cell-biology experiments is starting with exactly the right cells. Michael Eisenstein takes a look at the technologies that can make this possible.
Michael Eisenstein
doi:10.1038/4411179a
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Cell sorting: The gentle touch p1179
doi:10.1038/4411179b
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Cell sorting: Playing the field p1181
doi:10.1038/4411181a
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Cell sorting: The guiding light p1183
doi:10.1038/4411183a
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Naturejobs
Prospect
Prospect p1191
Research assessment threatens to reshuffle UK funding.
Paul Smaglik
doi:10.1038/nj7097-1191a
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Careers and Recruitment
Gary Borisy, director and chief executive, Marine Biological Laboratory, Woods Hole, Massachusetts p1192
Gary Borisy takes the helm at the Marine Biological Laboratory.
Virginia Gewin
doi:10.1038/nj7097-1192a
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Networks work p1192
Networking can pay off for PhD students.
Denis Bilotta
doi:10.1038/nj7097-1192b
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Goooaaalll! A PhD! p1192
Thesis excitement rivals the World Cup.
Milan de Vries
doi:10.1038/nj7097-1192c
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Futures
Finding a happy medium p1194
Be careful what you think out loud...
John Gilbey
doi:10.1038/4411194a
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