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Nature Contents 15 June 2006 (Vol. 441 pp785-906)
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自然要览] （选自英国Nature杂志，2006年6月15日出版） 封面故事：飞机“凝结尾迹”对气候的影响 The importance of the diurnal and annual cycle of air traffic for contrail radiative forcing 由高速飞行的飞机所产生的“凝结尾迹”（contrails）对地球的能量平衡有一个效 应，这个效应与高空薄冰云对地球能量平衡所产生的效应相似。它们会将从地球及其大 气层向外传播的长波辐射束缚住，并反射入射的太阳辐射。平均来说，长波效应占优 势，净效应是气温变暖。该效应与由其他排放引起的效应相比是小的，但随着航空流量 的增加，了解该现象也是很重要的。对英格兰东南上空所做的一项研究表明，该效应关 键取决于“凝结尾迹”什么时候形成。夜间飞行占由“凝结尾迹”诱导产生的变暖的近 80%，即便只有1/4的飞行发生在夜间。“凝结尾迹”的辐射性质和它们寿命很短的特点 意味着，由航空运输的这个方面所造成的气候影响，有可能通过对航班时间重新进行精 心编排减小到最低程度。（Letter p. 864） 地球形成之初的谜团（To the centre of the Earth） 对新形成的恒星所做的观测表明，太阳的行星体系是从一个平坦的气体和尘埃盘开始形 成的，这个气体和尘埃盘快速（在大约10万年内）累积形成直径约10公里的小型行星。 然后，在一个持续时间大约为3000万至4000万年的过程中，由这些小型行星累积形成了 地球。Wood等人在本期Nature上发表了一篇综述文章，其内容是关于以下两个问题的最 近的一些研究工作的：一是上面所说的累积增长过程的性质是什么，二是地球何以形成 了一个富含铁的熔融核、而其中的低原子数元素含量高于形成地球的小型行星构造单 元。（Review Article p. 825） 木星大小的行星周围只可能形成火星或月球大小的卫星（How massive the moon） Accretion of the Earth and segregation of its core 太阳系中位置靠外的巨型行星每个都有多个卫星，每个巨型行星的卫星体系的质量总和 与该行星的质量之比都差不多——这些巨型行星的质量是它们全部卫星质量总和的10万 倍。现在，已经找到了对这种一致性的一个可能的解释。在对一个通过积累氢气和石- 冰固体而正在生长的巨型行星所做的数值模拟中，该行星的卫星体系的质量所占比例通 过两个过程之间的一个平衡被调控为1：10万，这两个过程分别是：新物质向这些卫星 的流入和由气体诱导的轨道衰减造成的物质损失。这个结果对于研究太阳系外的行星是 有意义的：科学家曾认为，木星大小的行星周围的地球大小的卫星也许适合人类生存， 但新的发现是，那种地方只可能形成火星或月球大小的卫星，所以该观点需要修正。 （Article p. 834） 单细胞层次上的蛋白组学研究（Single-cell proteomics） Single-cell proteomic analysis of S. cerevisiae reveals the architecture of biological noise 一个活细胞产生数以千计的不同蛋白，调控这些蛋白的含量是细胞生物功能的关键。每 种蛋白都只能以很少的数量产生，所以要对它们分别进行测定在技术上是困难的。但研 究人员采用了一种新的策略，他们利用高通过量的流式细胞计量方法和荧光标记方法， 来以单细胞分辨率对酵母中25000种以上的蛋白的含量进行监测。利用DNA微阵列方法也 可以观察一个细胞对环境变化的反应，而该方法是从另一个角度来研究同一个问题。分 析结果表明，不同蛋白的“噪音”水平部分取决于它们的功能。从事至关重要的“家务 工作”的蛋白在不同细胞之间往往是统一的，但参与环境响应的蛋白则在不同细胞之间 是不同的。影响噪音水平的其他因素包括一个蛋白在细胞内的位置及控制其产生的机 制。（Article p. 840） HIV-1表面上的蛋白刺（AIDS virus structure） Distribution and three-dimensional structure of AIDS virus envelope spikes 利用“冷电子显微镜断层扫描”方法所做的观测，以前所未有的详细程度显示了艾滋病 病毒HIV-1表面上的蛋白刺。这些蛋白刺可让该病毒非常有效地与人体免疫细胞结合和 融合。每个病毒体在每个粒子上平均有14个刺，其中的一些刺是聚集在一起的，这个特 点与病毒组装、感染及中和机制都有关系。有一个出乎意料的发现：过去人们假设这种 蛋白刺的柄由三个紧紧束缚在一起的杆组成，刺的头在最上边。而事实上它的柄是分成 三条腿的，其形状就像一个三角架，这样可以使其与病毒膜的接触达到最大。 （Article p. 847; News and Views） 稳定的超冷原子对（An unlikely union） Repulsively bound atom pairs in an optical lattice 在物理学中，物体之间彼此吸引、通过降低它们的能量而形成稳定的结合态是常见现 象。但稳定的复合物即便有排斥性相互作用也能存在是有条件的。本期Nature报告了这 样一个奇特的结合态的生成。它由一个光晶格中的一对超冷铷原子组成。这对铷原子之 所以是稳定的，是因为处在一个有强排斥相互作用的光晶格的一个给定点上的两个铷原 子无法衰变，因为它们无法将其势能转变成动能，这个现象可由关于超冷量子气体结构 的Bose–Hubbard模型的约束条件来解释。（Letter p. 853; News and Views） 一种新形态的二氧化碳（Beyond dry ice） Amorphous silica-like carbon dioxide 高压改变凝聚态物质中原子间和分子间的相互作用，可深层次改变材料的物理和化学性 质。这一现象在被称为“a-carbonia”的一种新发现的二氧化碳形态中得到了戏剧般地 演示。这种非分子无定形二氧化碳是固体形态的分子二氧化碳的一种高压改变形态。它 是一种玻璃质材料，与无定形硅石(SiO2)和锗石（GeO2）相似。该发现有可能在轻元素 固体化学中开辟新的研究领域。（Letter p. 857; News and Views） 杂交在物种形成中所起的重要作用（Two into three will go） Speciation by hybridization in Heliconius butterflies 物种形成一般被认为是由于一个品系分裂成了两个，但最近的研究表明，杂交（两个祖 先种类通过杂交而不发生染色体数量变化形成第三个物种的现象）对于推动物种起源的 作用比我们过去所意识到的要重要的多。该现象仍然被认为是少见的，但新的事例正在 出现。最新的一例是热带蝴蝶Heliconius heurippa，科学家知道它有一个杂合的基因 组，看起来像是另外两个物种（H. cydno 和 H. melpomene）之间的一种杂交。而且， 实验表明，一个杂合的特征直接造成生殖隔离。过去，育种实验曾被用来重新生成H. heurippa的中间翅膀颜色， 并用来证明该物种鲜明的图案在生殖上将其与父辈物种隔 离开来。（Letter p. 868） 从神经生物学角度来研究好奇心（To boldly go…） Cortical substrates for exploratory decisions in humans 人类是非常好奇的，这种好奇心可帮助我们了解新环境和新的可能性。但常言说，好奇 心，惹祸根。好奇心是有风险的，是有可能让我们付出代价的。统计学家、工程师和经 济学家早就考虑到了如何平衡探索的成本与利益的问题。现在，涉及一项博弈任务和一 次fMRI脑扫描的测试表明，人类在考虑自己的意见时似乎遵从类似的原理。参试者必须 在两种欲望之间达成平衡：一种是根据积累的经验选择可能性最大的选项；另一种是选 择一个不太熟悉、但有可能有更大回报的选项。大脑中有一个参与认知控制的区域，被 称为frontopolar cortex。该区域在探索性决定过程中尤为活跃。这项研究的结果从神 经生物学角度对人类的探索行为做了解释，并且指出了行为和神经研究的一个新领域。 （Letter p. 876; News and Views） 细胞成分不断清除对于维持神经健康的重要性A tidy cell is a healthy cell） Loss of autophagy in the central nervous system causes neurodegeneration in mice/ Suppression of basal autophagy in neural cells causes neurodegenerative disease in mice 本期Nature上两篇论文表明，蛋白降解和细胞成分清除的过程在维持神经系统健康中所 起的作用可能比我们以前所想的更为重要。两个小组所做的研究都表明，抑制小鼠细胞 的自吞作用，导致神经退化和过早死亡。自吞作用（细胞成分的蛋白降解和循环）对于 一个细胞的正常生长和发育是很重要的。关于细胞成分不断清除对于维持神经健康来说 非常重要的发现，将为关于神经退化疾病的研究工作开辟新的途径。（Letters pp. 880, 885; News and Views） |
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木虫 (正式写手)
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---------------------- NEWS AND VIEWS ---------------------- Structural biology: Images from the surface of HIV Human and monkey immunodeficiency viruses are studded with ‘spikes’ that enable them to infect cells. Structural studies reveal that these spikes are tripod-like assemblies that cluster on the virus surface. Dennis R. Burton http://www.nature.com/nature/journal/v441/n7095/full/441817a.html Material science: Oxygen breaks into carbon world When oxygen atoms bind to a graphite surface, they fall into line and make bridges across carbon atoms. This is the spearhead of a chemical attack in which the atomic arrangement of solid carbon is torn apart. Pulickel M. Ajayan and Boris I. Yakobson http://www.nature.com/nature/journal/v441/n7095/full/441818a.html Neurodegeneration: Good riddance to bad rubbish Autophagy -- cellular ‘self-eating’ -- can be induced by stress, but it also acts continuously in a housekeeping role, disposing of unwanted proteins. Can it protect against neurodegenerative diseases? Daniel J. Klionsky http://www.nature.com/nature/journal/v441/n7095/full/441819a.html Quantum physics: United through repulsion Mutually repulsive atoms placed at periodic intervals in a ‘crystal of light’ can, counterintuitively, be forced into stable couplings. That theoretical prediction has just seen experimental confirmation. Leonardo Fallani and Massimo Inguscio http://www.nature.com/nature/journal/v441/n7095/full/441820a.html Biomaterials: Silk spin-off Helen Dell http://www.nature.com/nature/journal/v441/n7095/full/441821a.html Neuroeconomics: Best to go with what you know? In a changing world, how do we decide our best option? How do we settle between picking something familiar or trying out a new, possibly more rewarding, choice? Daeyeol Lee http://www.nature.com/nature/journal/v441/n7095/full/441822a.html Solid-state chemistry: A glass of carbon dioxide Carbon is unusual in its family of elements because it has gaseous oxides. But under high pressure, carbon dioxide forms crystalline solids and can become a glass -- so revealing the chemical family resemblance. Paul F. McMillan http://www.nature.com/nature/journal/v441/n7095/full/441823a.html Obituary: Bruce Merrifield (1921-2006) Inventor of solid-phase peptide synthesis. Stephen Kent http://www.nature.com/nature/journal/v441/n7095/full/441824a.html ---------------------- REVIEW ---------------------- Accretion of the Earth and segregation of its core The high-pressure nature of the core-forming process led to the Earth's core being richer in low atomic number elements, notably silicon and possibly oxygen, than the smaller planetesimal building blocks would indicate. Bernard J. Wood, Michael J. Walter and Jonathan Wade Abstract: http://www.nature.com/nature/jou ... bs/nature04763.html Article: http://www.nature.com/nature/jou ... ll/nature04763.html ---------------------- ARTICLES ---------------------- A common mass scaling for satellite systems of gaseous planets Modelling of satellite growth as a giant planet accumulates hydrogen gas and rock-ice solids from solar orbit finds that the mass fraction of its satellite system is ～10-4 and regulated by a balance of two competing processes. Robin M. Canup and William R. Ward Abstract: http://www.nature.com/nature/jou ... bs/nature04860.html Article: http://www.nature.com/nature/jou ... ll/nature04860.html Single-cell proteomic analysis of S. cerevisiae reveals the architecture of biological noise A strategy involving high-throughput flow cytometry to monitor protein abundance at single-cell resolution in yeast allows a different view of the cellular response to environmental changes than can be obtained with DNA microarrays. John R. S. Newman, Sina Ghaemmaghami, Jan Ihmels, David K. Breslow, Matthew Noble, Joseph L. DeRisi and Jonathan S. Weissman Abstract: http://www.nature.com/nature/jou ... bs/nature04785.html Article: http://www.nature.com/nature/jou ... ll/nature04785.html Distribution and three-dimensional structure of AIDS virus envelope spikes Ping Zhu, Jun Liu, Julian Bess, Jr, Elena Chertova, Jeffrey D. Lifson, Henry Gris?(c), Gilad A. Ofek, Kenneth A. Taylor and Kenneth H. Roux Abstract: http://www.nature.com/nature/jou ... bs/nature04817.html Article: http://www.nature.com/nature/jou ... ll/nature04817.html ---------------------- LETTERS ---------------------- Repulsively bound atom pairs in an optical lattice In a periodic potential with no dissipation, stable composite objects can exist even for repulsive interactions. The paper reports the observation of such an exotic bound state, which is comprised of a pair of ultracold rubidium atoms in an optical lattice. K. Winkler, G. Thalhammer, F. Lang, R. Grimm, J. Hecker Denschlag, A. J. Daley, A. Kantian, H. P. B?1/4chler and P. Zoller Abstract: http://www.nature.com/nature/jou ... bs/nature04918.html Article: http://www.nature.com/nature/jou ... ll/nature04918.html Amorphous silica-like carbon dioxide Mario Santoro, Federico A. Gorelli, Roberto Bini, Giancarlo Ruocco, Sandro Scandolo and Wilson A. Crichton Abstract: http://www.nature.com/nature/jou ... bs/nature04879.html Article: http://www.nature.com/nature/jou ... ll/nature04879.html Control of four stereocentres in a triple cascade organocatalytic reaction Development of an asymmetric organocatalytic triple cascade able to synthesize tetra-substituted cyclohexene carbaldehydes proceeds through a Michael/Michael/aldol condensation sequence, generating four stereogenic centres with high diastereo- and complete enantiocontrol in good to moderate yields. Dieter Enders, Matthias R. M. H?1/4ttl, Christoph Grondal and Gerhard Raabe Abstract: http://www.nature.com/nature/jou ... bs/nature04820.html Article: http://www.nature.com/nature/jou ... ll/nature04820.html The importance of the diurnal and annual cycle of air traffic for contrail radiative forcing A sophisticated radiative transfer model estimates the effect of air traffic condensation trails, or contrails, on the atmosphere -- although the effect is currently small compared with that induced by other sources of human emissions, the comparably large growth rate of air traffic requires an improved understanding of the resulting impact. Nicola Stuber, Piers Forster, Gaby Radel and Keith Shine Abstract: http://www.nature.com/nature/jou ... bs/nature04877.html Article: http://www.nature.com/nature/jou ... ll/nature04877.html Speciation by hybridization in Heliconius butterflies Breeding experiments re-created the intermediate wing coloration of Heliconius heurippa from H. cydno and H. melpomene, showing that its distinctive patterning reproductively isolates it from the parent species and that a hybrid trait directly causes reproductive isolation. Jesus Mavarez, Camilo A. Salazar, Eldredge Bermingham, Christian Salcedo, Chris D. Jiggins and Mauricio Linares Abstract: http://www.nature.com/nature/jou ... bs/nature04738.html Article: http://www.nature.com/nature/jou ... ll/nature04738.html Sperm storage induces an immunity cost in ants Boris Baer, Sophie A. O. Armitage and Jacobus J. Boomsma Abstract: http://www.nature.com/nature/jou ... bs/nature04698.html Article: http://www.nature.com/nature/jou ... ll/nature04698.html Cortical substrates for exploratory decisions in humans Use of a gambling task and a functional magnetic resonance imaging (fMRI) scanner shows that human subjects' choices can be characterized by a computationally well regarded strategy for addressing the explore/exploit dilemma. Nathaniel D. Daw, John P. O'Doherty, Peter Dayan, Ben Seymour and Raymond J. Dolan Abstract: http://www.nature.com/nature/jou ... bs/nature04766.html Article: http://www.nature.com/nature/jou ... ll/nature04766.html Loss of autophagy in the central nervous system causes neurodegeneration in mice One of two papers showing that loss of autophagy in the central nervous system of mice causes the accumulation of protein aggregates in inclusion bodies, neurodegeneration and premature death of the mice. This demonstrates that continuous clearance of cellular components is essential for proper housekeeping and vital to keep the neurons in tiptop shape. Masaaki Komatsu, Satoshi Waguri, Tomoki Chiba, Shigeo Murata, Jun-ichi Iwata, Isei Tanida, Takashi Ueno, Masato Koike, Yasuo Uchiyama, Eiki Kominami and Keiji Tanaka Abstract: http://www.nature.com/nature/jou ... bs/nature04723.html Article: http://www.nature.com/nature/jou ... ll/nature04723.html Suppression of basal autophagy in neural cells causes neurodegenerative disease in mice One of two papers showing that loss of autophagy in the central nervous system of mice causes the accumulation of protein aggregates in inclusion bodies, neurodegeneration and premature death of the mice. This demonstrates that continuous clearance of cellular components is essential for proper housekeeping and vital to keep the neurons in tiptop shape. Taichi Hara, Kenji Nakamura, Makoto Matsui, Akitsugu Yamamoto, Yohko Nakahara, Rika Suzuki-Migishima, Minesuke Yokoyama, Kenji Mishima, Ichiro Saito, Hideyuki Okano and Noboru Mizushima Abstract: http://www.nature.com/nature/jou ... bs/nature04724.html Article: http://www.nature.com/nature/jou ... ll/nature04724.html Interleukin-2 signals during priming are required for secondary expansion of CD8+ memory T cells Matthew A. Williams, Aaron J. Tyznik and Michael J. Bevan Abstract: http://www.nature.com/nature/jou ... bs/nature04790.html Article: http://www.nature.com/nature/jou ... ll/nature04790.html Signal peptide peptidase is required for dislocation from the endoplasmic reticulum As well as cleaving hydrophobic stretches of amino acids in the plane of the cell membrane, the protease signal peptide peptidase plays a role in the disposal of unwanted glycoproteins from the endoplasmic reticulum -- indicating that these proteases may be important for general membrane protein quality control. Joana Loureiro, Brendan N. Lilley, Eric Spooner, Vanessa Noriega, Domenico Tortorella and Hidde L. Ploegh Abstract: http://www.nature.com/nature/jou ... bs/nature04830.html Article: http://www.nature.com/nature/jou ... ll/nature04830.html CRD-BP mediates stabilization of βTrCP1 and c-myc mRNA in response to β -catenin signalling β-catenin stabilizes the mRNA encoding the F-box protein βTrCP1, and the RNA-binding protein CRD-BP (coding region determinant-binding protein) is identified as a previously unknown target of β-catenin/Tcf transcription factor. Felicite K. Noubissi, Irina Elcheva, Neehar Bhatia, Abbas Shakoori, Andrei Ougolkov, Jianghuai Liu, Toshinari Minamoto, Jeff Ross, Serge Y. Fuchs and Vladimir S. Spiegelman Abstract: http://www.nature.com/nature/jou ... bs/nature04839.html Article: http://www.nature.com/nature/jou ... ll/nature04839.html |
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