Volume 440 Number 7086 pp845-968 封面故事：味觉差异的奥秘
是否能够尝到苦味是是否能够发现食物中毒素的关键。苯硫脲（PTC）是一种不同寻常的化学物质，其特殊性在于它要么味道非常苦，要么几乎没有味道，这主要取决于一个人的遗传情况。在1939年发表在Nature杂志上的一篇经典论文中，R. A. Foster、E. B. Ford 和J. S. Huxley指出，黑猩猩对PTC也有不同的敏感度，这被认为是反映了人类与黑猩猩之间共有的一个古老的遗传多态性，是由自然选择维持下来的。现在，由于主管人类PTC敏感度的TAS2R38位点已经被识别出来，Wooding等人便对人类与黑猩猩在这个问题上的相似性重新做了比较。TAS2R38也与黑猩猩的PTC敏感度有关，但令人吃惊的是，造成这一多态性的突变在两个物种身上是不同的。在原始人类的演化过程中，“无味觉”等位基因似乎至少独立演化过两次。由D. J. Cox拍摄的封面照片是2003年3月在美国田纳西州查塔努加动物园里拍摄的，照片上的黑猩猩正在尽可能多地收集水果。
现代地震学的发端——弹性反弹理论
1906年4月18日发生的洛杉矶大地震改变了地质学领域。这是第一个记录在电影胶片上的大型自然灾害，它所产生的大量科学数据为现代地震学奠定了基础。现代地震学是从Henry Fielding Reid的弹性反弹理论开始的，该理论首次满意地解释了地震周期。Naomi Lubick对该理论做了介绍。
比“露西”更早的“南方古猿”
人类被普遍认为是由“南方古猿”这个属的动物演化来的，但这个属的起源却笼罩在一层迷雾中。在埃塞俄比亚一处名为Middle Awash的研究区域一个以前未曾取样分析的时间段中新发现的化石，为这个研究课题增添了重要信息。它们是“南方古猿湖畔种” （Australopithecus anamensis）已知最早的成员，是在肯尼亚Turkana盆地之外发现的第一批此类化石。这些动物生活在一个林地环境中，它们的化石反映了“南方古猿湖畔种”会是怎样由更原始的地猿（Ardipithecus）演化来的，并且“南方古猿湖畔种”还可能是被俗称为“露西”的“南方古猿阿法种” （Australopithecus afarensis）的祖先。
关于“织女星”的新老问题
“织女星”是北半球可以看到的第二颗最亮的恒星，被天文学家用作一个确定其他恒星亮度的标准。对该恒星在其整个光谱范围内的光强度我们都已精确了解，其亮度也与能量输出联系了起来。但是，根据这种比较得出的结论一直存在问题，于是就有人提出，“织女星”从极地方向看是一个失真的、迅速转动的恒星。现在， Peterson等人报告说，“织女星”的确在迅速转动，从地球上来看也几乎是极地朝向我们的。这个观点解决了早先的一些问题，但又为“织女星”的年龄增添了不确定性，并且提出这样一个可能性：该恒星的尘埃环有可能比我们所想的古老得多。
量子世界中的“牛顿摆”
“牛顿摆”是一种流行的教具和益智玩具，它反映了一维体系中动量的守恒。现在，研究人员在一种一维玻色气体中也生成了这样一个量子世界中的“牛顿摆”。在量子“牛顿摆”中，由超冷铷原子构成的一维阵列互相碰撞数千次，彼此之间又反弹开来或通过彼此进行传播，而不会有明显的阻尼。该体系有可能在力传感装置和原子干涉仪中找到用途。
一种新型有机光源
随着节约能源受到各国政府的高度重视，寻找经济光源的工作便成为一个热门研究领域。本期Nature报告的一项进展可能是这一领域所迈出的重要一步。该研究工作为制造颜色稳定的有机发光装置确定了一个新的架构，这类装置能够产生适用于固体发光的白光。该技术的新颖之处是使用了荧光和磷光掺杂材料，它们可以优化电荷的俘获，内部量子效率有可能达到100%。这种类型的技术有可能使有机发光装置（OLED）的发光效率远远高于白炽发光装置。即便现在还处在发展过程的早期，这种新光源在类似亮度下的发光效率也要比今天的白炽光源高出近75%。
甲烷的厌氧氧化反应
虽然存在很多猜测，但尚未发现能够用硝酸盐作为惟一电子受体来在厌氧条件下氧化甲烷的微生物。现在，研究人员已经在实验室里的一个微生物群落中演示了这一反应，该微生物群落有两个成员，一个是一种生长缓慢的细菌，该类型的细菌以前没有培养过；另一个是一种古生物。两种生物典型的核酸标记物都存在于全世界的淡水样品中，说明该反应在生物甲烷和氮循环中是一个重要环节。该反应还有可能被用来抑制与集约型农业生产有关的甲烷生成量的增加。
土壤氮对未来气候的影响
大气中CO2浓度的未来趋势以及未来气候的发展趋势，都将部分取决于陆地生态系统积累来自人类活动的CO2排放的程度。对草地进行的一项为期6年的野外研究发现，因CO2浓度升高所造成的生物质的增加在周围环境中氮供应的影响下随着时间的推移将下降，但不是在氮富集的影响下，说明不同土壤中氮含量的自然变化和氮沉降速度的变化都有可能影响植物生物质积累对CO2浓度升高所产生的响应。氮在很多被管理的和未管理的土壤中都是一个限制因素，所以土壤氮可能是影响全球对CO2浓度升高的响应情况的一个重要限制因素。
用STED显微镜观测联会囊
STED（受激发射损耗）显微镜是一种新型光学显微镜技术，它能克服限制传统荧光显微镜分辨率的衍射障碍。这种显微镜能够观测联会囊大小（40纳米）的结构。现在STED显微镜首次被用来分辨哺乳动物中枢神经系统中单次联会中的各个联会囊。对神经传输物质的释放至关重要的联合囊循环已被深入研究了30多年，但仍有一个大问题没有回答：它们的构成成分是在胞质膜上扩散，还是仍然聚集在一起？STED显微镜的观测结果显示，至少一个主要成分，即 synaptotagmin-1，在胞外分泌之后仍然聚集在一起，是被整体循环的。
一种利用转基因酵母生产青蒿素衍生物的方法
具有抗药性的疟疾寄生虫广泛存在，因此由疟疾所导致的死亡人数近年来明显增加。从中药材青蒿中分离出的青蒿素，是惟一能够高效杀死疟疾寄生虫的药物。由于需求量大，只能从植物中来提取的青蒿素已经供不应求。现在，Ro等人报告说，他们利用基因工程方法培育出了携带一个青蒿基因的酵母，这种酵母能产生该药物的前体物质青蒿素酸。青蒿素酸可通过化学方法进行改造，变成活性青蒿素衍生物。关于这一方法的效率还需要做进一步研究，但它却有可能缓解该药物的短缺，降低生产成本。
一种奇异的母爱形式
研究人员在一群神秘的热带脊椎动物中发现了一种特别不寻常的母爱形式。在卵生的两栖动物Boulengerula taitanus的种群中，幼子用专门的牙齿来剥掉并吃下其母亲变性的皮肤外层，从而确保在自己的生命中有一个良好的开端。这种奇异的行为可以被看作是演化上的一个环节，它为相关胎生两栖动物在输卵管内壁上哺育胎儿铺平了道路。该论文“补充信息”中的影片看起来的确是血淋淋的。
ContentsEditorials
The constant gardeners p845
While pottering away in a garden near you, botanists are playing an increasingly sophisticated role in studying plant diversity. They should continue to broaden their scientific reach.
doi:10.1038/440845a
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More than the money p845
Technology-transfer offices are learning from their mistakes. So should the academics that they serve.
doi:10.1038/440845b
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Neglected neighbour p846
Venus Express will go some way towards correcting a strange disparity.
doi:10.1038/440846a
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Research Highlights
Research highlights p848
doi:10.1038/440848a
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News
Bird-flu experts question advice on eating poultry p850
How safe are chicken and eggs?
Declan Butler
doi:10.1038/440850a
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Patients warned about unproven spinal surgery p850
Critics attack Chinese treatment despite anecdotal successes.
David Cyranoski
doi:10.1038/440850b
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Sidelines p852
doi:10.1038/440852a
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Malaria breakthrough raises spectre of drug resistance p852
Yeast engineered to produce potent drug.
Narelle Towie
doi:10.1038/440852b
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Two telescopes join hunt for ET p853
Optical astronomers scan the sky for signs of life.
Tony Reichhardt
doi:10.1038/440853a
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Can super-antibody drugs be tamed? p855
As it becomes clear that the London clinical trial disaster was indeed the fault of the drug itself, Michael Hopkin looks at what went wrong, and whether there is any future for 'superagonist' antibody therapies.
doi:10.1038/440855a
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Japan revises its military plans for space p857
Government wants better spy satellites.
Ichiko Fuyuno
doi:10.1038/440857a
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News in brief p858
doi:10.1038/440858a
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News Features
Plant science: Gardens in full bloom p860
In a world of declining biodiversity, botanical gardens are coming into their own — both as storehouses of rare plants and skills, and increasingly as centres of molecular research. Emma Marris reports.
doi:10.1038/440860a
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Seismology: Breaking new ground p864
In 1906, a great earthquake destroyed San Francisco, and galvanized US seismologists. Naomi Lubick looks back at the event that changed the country's geological scene.
doi:10.1038/440864a
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Business
University challenge p867
Cambridge is revamping its approach to technology transfer — but will it work? Colin Macilwain reports.
doi:10.1038/440867a
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Correspondence
Industry: policing the 'dark side' of ecology p868
David Allsop
doi:10.1038/440868a
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Industry: speak up to stop its pressure on academia p868
Ralf Buckley
doi:10.1038/440868b
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Risks of a high-protein diet outweigh the benefits p868
Rosemary Stanton and Tim Crowe
doi:10.1038/440868c
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Local people may be the best allies in conservation p868
Douglas Sheil and Manuel Boissière
doi:10.1038/440868d
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Books and Arts
Real concerns, false gods p869
Invoking a wrathful biosphere won't help us deal with the problems of climate change.
Tyler Volk reviews The Revenge of Gaia: Why the Earth is Fighting Back — And How We Can Still Save Humanity by James Lovelock
doi:10.1038/440869a
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Climbing Mount Schiehallion p870
Patricia Fara reviews Weighing the World: The Quest to Measure the Earth by Edwin Danson
doi:10.1038/440870a
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Thirsty work p871
doi:10.1038/440871a
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Weird, sexy and mind-blowing p871
Jim Al-Khalili reviews The Quantum Zoo: A Tourist's Guide to the Never-Ending Universe by Marcus Chown
doi:10.1038/440871b
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Science in culture: Eggs and exegesis p872
Putting the 'history' back into natural history.
Martin Kemp
doi:10.1038/440872a
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News and Views
Astrophysics: A whirling dervish p873
Vega is a fundamental reference star for astronomers. But it seems that our perceptions of it have been misconceived — rather than spinning slowly, the star is a rapid rotator seen pole-on.
Richard Gray
doi:10.1038/440873a
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Ageing: Chromatin unbound p874
Sir2 proteins slow ageing in yeast by locking chromatin — the DNA and proteins in chromosomes — into a stable, silent state. Inactivating a Sir2 family protein in mice causes premature ageing and genome instability.
Jan Vijg and Yousin Suh
doi:10.1038/440874a
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Conservation biology: Roads and genetic connectivity p875
The Ventura Freeway slices through wildlife habitat near Los Angeles. A case study shows how large highways such as this can seriously impede genetic exchange in large vertebrates.
Jared L. Strasburg
doi:10.1038/440875a
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Chemistry: A nose for sarin p876
Andrew Mitchinson
doi:10.1038/440876a
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Quantum physics: Equilibrium on hold p877
Startlingly, two atomic clouds confined to one dimension can be made to pass through each other repeatedly without ever coming to rest. Such non-equilibrium phenomena are fundamental, but experimentally elusive.
Henk T. C. Stoof
doi:10.1038/440877a
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Biogeochemistry: Methane and microbes p878
Microorganisms can carry out a wonderful range of chemical transformations. The anaerobic oxidation of methane seemed not to be among them. But it is — both with sulphate, and now it turns out, with nitrate.
Rudolf K. Thauer and Seigo Shima
doi:10.1038/440878a
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Biological imaging: The diffraction barrier broken p879
The conventional optical limitations of fluorescence microscopy have been defied, to achieve nanoscale resolution of individual vesicle organelles at the junctions of neuronal cells.
Garth J. Simpson
doi:10.1038/440879a
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Behavioural ecology: Grasshoppers don't play possum p880
When about to be eaten by frogs, certain grasshoppers assume a static, unwieldy pose that means they cannot be swallowed. Similar behaviours, interpreted as feigning death, may also be open to alternative explanations.
Graeme Ruxton
doi:10.1038/440880a
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Brief Communications
Evolution: A catfish that can strike its prey on land p881
This denizen of tropical swamps may shed light on how ancient fish were able to survive out of water.
Sam Van Wassenbergh, Anthony Herrel, Dominique Adriaens, Frank Huysentruyt, Stijn Devaere and Peter Aerts
doi:10.1038/440881a
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Brief Communications Arising
Taxonomy: Sus bucculentus revisited pE7
Judith H. Robins, Howard A. Ross, Melinda S. Allen and Elizabeth Matisoo-Smith
doi:10.1038/nature04770
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Articles
Asa Issie, Aramis and the origin of Australopithecus p883
Tim D. White, Giday WoldeGabriel, Berhane Asfaw, Stan Ambrose, Yonas Beyene, Raymond L. Bernor, Jean-Renaud Boisserie, Brian Currie, Henry Gilbert, Yohannes Haile-Selassie, William K. Hart, Leslea J. Hlusko, F. Clark Howell, Reiko T. Kono, Thomas Lehmann, Antoine Louchart, C. Owen Lovejoy, Paul R. Renne, Haruo Saegusa, Elisabeth S. Vrba, Hank Wesselman and Gen Suwa
doi:10.1038/nature04629
Abstract | Full Text | PDF (670K) | Supplementary information
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Chemokines enhance immunity by guiding naive CD8+ T cells to sites of CD4+ T cell–dendritic cell interaction p890
Flora Castellino, Alex Y. Huang, Grégoire Altan-Bonnet, Sabine Stoll, Clemens Scheinecker and Ronald N. Germain
doi:10.1038/nature04651
Abstract | Full Text | PDF (520K) | Supplementary information
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Letters
Vega is a rapidly rotating star p896
D. M. Peterson, C. A. Hummel, T. A. Pauls, J. T. Armstrong, J. A. Benson, G. C. Gilbreath, R. B. Hindsley, D. J. Hutter, K. J. Johnston, D. Mozurkewich and H. R. Schmitt
doi:10.1038/nature04661
First paragraph | Full Text | PDF (245K) | Supplementary information
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A quantum Newton's cradle p900
Toshiya Kinoshita, Trevor Wenger and David S. Weiss
doi:10.1038/nature04693
First paragraph | Full Text | PDF (575K) | Supplementary information
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Parametric oscillation in vertical triple microcavities p904
C. Diederichs, J. Tignon, G. Dasbach, C. Ciuti, A. Lemaître, J. Bloch, Ph. Roussignol and C. Delalande
doi:10.1038/nature04602
First paragraph | Full Text | PDF (700K) | Supplementary information
Management of singlet and triplet excitons for efficient white organic light-emitting devices p908
Yiru Sun, Noel C. Giebink, Hiroshi Kanno, Biwu Ma, Mark E. Thompson and Stephen R. Forrest
doi:10.1038/nature04645
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Deep origin and hot melting of an Archaean orogenic peridotite massif in Norway p913
Dirk Spengler, Herman L. M. van Roermund, Martyn R. Drury, Luisa Ottolini, Paul R. D. Mason and Gareth R. Davies
doi:10.1038/nature04644
First paragraph | Full Text | PDF (696K) | Supplementary information
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A microbial consortium couples anaerobic methane oxidation to denitrification p918
Ashna A. Raghoebarsing, Arjan Pol, Katinka T. van de Pas-Schoonen, Alfons J. P. Smolders, Katharina F. Ettwig, W. Irene C. Rijpstra, Stefan Schouten, Jaap S. Sinninghe Damsté, Huub J. M. Op den Camp, Mike S. M. Jetten and Marc Strous
doi:10.1038/nature04617
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Nitrogen limitation constrains sustainability of ecosystem response to CO2 p922
Peter B. Reich, Sarah E. Hobbie, Tali Lee, David S. Ellsworth, Jason B. West, David Tilman, Johannes M. H. Knops, Shahid Naeem and Jared Trost
doi:10.1038/nature04486
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Parental investment by skin feeding in a caecilian amphibian p926
Alexander Kupfer, Hendrik Müller, Marta M. Antoniazzi, Carlos Jared, Hartmut Greven, Ronald A. Nussbaum and Mark Wilkinson
doi:10.1038/nature04403
First paragraph | Full Text | PDF (317K) | Supplementary information
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Independent evolution of bitter-taste sensitivity in humans and chimpanzees p930
Stephen Wooding, Bernd Bufe, Christina Grassi, Michael T. Howard, Anne C. Stone, Maribel Vazquez, Diane M. Dunn, Wolfgang Meyerhof, Robert B. Weiss and Michael J. Bamshad
doi:10.1038/nature04655
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STED microscopy reveals that synaptotagmin remains clustered after synaptic vesicle exocytosis p935
Katrin I. Willig, Silvio O. Rizzoli, Volker Westphal, Reinhard Jahn and Stefan W. Hell
doi:10.1038/nature04592
First paragraph | Full Text | PDF (357K) | Supplementary information
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Production of the antimalarial drug precursor artemisinic acid in engineered yeast p940
Dae-Kyun Ro, Eric M. Paradise, Mario Ouellet, Karl J. Fisher, Karyn L. Newman, John M. Ndungu, Kimberly A. Ho, Rachel A. Eachus, Timothy S. Ham, James Kirby, Michelle C. Y. Chang, Sydnor T. Withers, Yoichiro Shiba, Richmond Sarpong and Jay D. Keasling
doi:10.1038/nature04640
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Reactive oxygen species have a causal role in multiple forms of insulin resistance p944
Nicholas Houstis, Evan D. Rosen and Eric S. Lander
doi:10.1038/nature04634
First paragraph | Full Text | PDF (406K) | Supplementary information
IkappaB kinase-alpha is critical for interferon-alpha production induced by Toll-like receptors 7 and 9 p949
Katsuaki Hoshino, Takahiro Sugiyama, Mitsuru Matsumoto, Takashi Tanaka, Masuyoshi Saito, Hiroaki Hemmi, Osamu Ohara, Shizuo Akira and Tsuneyasu Kaisho
doi:10.1038/nature04641
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The reversibility of mitotic exit in vertebrate cells p954
Tamara A. Potapova, John R. Daum, Bradley D. Pittman, Joanna R. Hudson, Tara N. Jones, David L. Satinover, P. Todd Stukenberg and Gary J. Gorbsky
doi:10.1038/nature04652
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Toxin-induced conformational changes in a potassium channel revealed by solid-state NMR p959
Adam Lange, Karin Giller, Sönke Hornig, Marie-France Martin-Eauclaire, Olaf Pongs, Stefan Becker and Marc Baldus
doi:10.1038/nature04649
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Naturejobs
Prospect
What now for biotechnology? p963
Developing world offers opportunities for biotechnology.
Paul Smaglik
doi:10.1038/nj7086-963a
Full Text
Postdocs and Students
Mentoring mismatch p964
Is your adviser not the role model or mentor of your dreams? Then take charge of the situation and find the right people. Kendall Powell plays matchmaker. More than one mentor may be necessary for postdocs and graduate students.
Kendall Powell
doi:10.1038/nj7086-964a
Full Text | PDF (456K)
Career Views
Nikolaus Rajewsky, head of bioinformatics research, Max Delbrück Center, Berlin, Germany p966
Physicist-turned-bioinformatician heads back to Germany.
Dirk Steuerwald
doi:10.1038/nj7086-966a
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Mass uprising of women in science p966
Women scientist group benefits from some bad news.
Joanne Kamens and Karen Yee
doi:10.1038/nj7086-966b
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Selling the PhD p966
Graduate student steps outside comfort zone.
Katja Bargum
doi:10.1038/nj7086-966c
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Futures
Directed energy p968
More than just a flash in the pan.
Jeff Hecht
doi:10.1038/440968a
Full Text | PDF (332K)
