| 2005年02月17日 Nature中文摘要 | 点击： 作者： 来源： 时间： 2006-11-11 本站论坛
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|  | Volume 433 Number 7027 pp669-784
封面故事：土星的极光
本期封面所示为“哈伯太空望远镜”在2004年1月24、26和28日拍摄的土星及其极光的图像。可见光图像与土星南极地区的紫外线图像结合在了一起。这些图像是在“卡西尼”飞船飞临土星执行测量太阳风任务期间以及执行土星千米无线电波测量任务期间获得的。这些结果发布在本期发表的三篇论文中。1月28日土星极光的强烈变亮与太阳风的一次大幅度波动是相应的。土星的极光与地球和木星上所看到的极光在形状和形式上都是不同的，它们对太阳风的反应也是不同的。土星最强烈的无线电发射似乎与其极光密切相关。（Letters, pp. 717, 720, 722; News and Views）
太阳能飞船将发射
定于下月发射的Cosmos 1是为检验宇宙飞船可以只由阳光驱动这一思想而用真实尺寸的飞船所做的第一次尝试。一旦脱离地球大气层，一个面积为600平方米的用聚酯材料做成的帆将从构成太阳风的气体和带电粒子流中收集能量。Cosmos 1的轨道速度的微小增加将足以演示这一原理。以这种形式的推动获得巨大加速是不可能的，但3年后，一个以太阳能为动力的探测器将能以每小时16万公里的速度飞行，其速度之快足以在不到5年内到达冥王星。
关于超重元素的最新研究
原子序数为110及以上的超重元素的实验合成向理论物理学提出了一个新挑战。尽管它们中大多数很可能在宇宙中实际上不存在（这是由于它们的寿命非常短），但就在它们所存在的极短时间内，数量非常大的粒子可被集中起来，形成一个核。理论必须能够解释这样一个事实：尽管质子之间存在巨大静电排斥，但第116号和118号元素的确存在，虽说存在时间很短。本期的Review Article对关于原子序数高达128的超重元素的最新理论做了综述。
鸣鸟是怎样学习唱歌的
这是一个需要几台iPod电脑（“苹果”电脑的一种牌子）来存储声音的项目。Derégnacourt等人对一种鸣鸟的声音发育的全过程进行了研究，该研究涉及到对每只鸟的100万以上的音节进行分析。同人学习说话一样，鸣鸟也有一个敏感期（对斑胸草雀来说即在孵化出后的30-90天），在此期间，它们学习声音效果极佳。该实验涉及到连续记录由一群斑胸草雀唱出的每首歌，显示出睡眠对幼鸟学习唱歌有强烈共鸣效果。唱歌表现在早晨比较差，而经过一上午集中唱歌后得到恢复。这种共鸣的作用似乎是很大的，因为每天共鸣表现比较强烈的鸟最后的模仿效果也比较好。这些鸟可能在睡眠过程中还在温习所学的歌曲，从而有机会不断练习和修正以前学会的运动技能。
基于硅的连续波激光器
在1月20日一期的Nature杂志上，英特尔公司的研究人员报告了在光电子领域所取得的一项值得注意的进展。他们在单一芯片上制成了一个全硅激光器，使作为现代微电子学基础材料的硅用在光应用中真正有了希望。现在，英特尔的研究实验室报告，他们首次实验演示了存在于单一芯片上的一个硅波导腔中的一个连续波激光器。这是朝着制造基于硅的低成本集成光电子电路的方向迈出的重要一步，这种光电子电路在通信和计算应用中将会有用武之地。
“现代智人”的起源时间被再次远推
35年前，由Richard Leakey及其同事在Nature杂志上发表的论文描述了来自埃塞俄比亚南部Kibish构造的化石，他们认为这些化石是“现代智人”（Homo sapiens）的化石。这些化石是“人类非洲起源说”的重要依据，据信其时间约在13万年前。最近来自Herto(也在埃塞俄比亚)的发现将最早的现代人的出现时间远推到距今约16万年前。但现在，对Kibish沉积层所做的重新评估表明，它们要比所想的久远得多，从而将这些人类遗骨出现的时间远推到距今19.5万年前。
气候变化所引起的动物种群数量的同步变化
动物种群数量经常通过同步波动来响应于气候波动，但这种响应是气候对各个动物的直接效应还是对捕食者和食物供应的间接效应尚不清楚。对英格兰北部红松鸡种群所做的一项研究，首次识别出了英国全国种群数量达到同步的年份，显示出同步起始的时间与种群数量增加的时间巧合。数值模拟显示，松鸡种群数量的增加是与不适合某种肠胃寄生虫传播的条件相关联的，这种寄生虫能够降低松鸡的生育力。这说明，特定气候事件能导致疾病或寄生虫感染的传播，间接引起寄主种群数量的同步变化。
视网膜中的光受体和光敏细胞
哺乳动物和鱼类中内视网膜光受体的发现是近年来视觉科学领域最让人吃惊的发现之一。除了众所周知的视杆和视锥细胞外还存在的这些受体，其作用被认为是探测光照的总体水平，并与生物钟系统的日夜调节联系在一起。两项新的研究工作表明，“黑视素”（Melanopsin）是光敏的（该物质几乎全部存在于这些“神经节细胞光受体”中）。Qiu等人通过引入“黑视素”将哺乳动物肾脏细胞变成了功能性光受体，Melyan等人在神经细胞中完成了类似工作，这些发现有可能具有重要临床应用，很可能能够让科学家对大脑中的细胞进行选择性刺激，帮助在视网膜退化病变中恢复视力。（Letters, pp. 741, 745; News and Views）另一项研究进而识别出了一组以前不知道的视网膜细胞群，名为“表达黑视素的巨型神经节细胞”。它们是光敏的，但也能被视杆和视锥细胞激发，因而将灵长动物中传统的视网膜“图像形成”通道与光照探测或“非图像形成”通道合并了起来。
干细胞和源祖细胞的再生能力
年轻个体中身体组织再生较好，年老个体中身体组织再生较差。为了确定身体组织再生能力的这种下降是否是不可逆转的、是否可由循环系统中的因素来调节，Conboy等人将年幼和年老小鼠的循环系统连在一起，成为一个“异共生”对。令人吃惊的是，老化的肌肉和肝脏的再生性质因暴露于年幼小鼠的血清而变年轻了，同时还伴随着年轻的“分子标记”的恢复，其中涉及Notch信号作用（在肌肉中）和由cEBPalpha-调节的细胞周期调节（在肝脏中）。这说明，干细胞和源祖细胞即使老了也保持其大部分增殖潜力，分子信号通道调节的“年轻”模式能重新激发组织再生。
微RNA及其表达
关于微RNA（miRNA）的新的研究工作为了解人体中的组织特异性基因表达提供了线索。微RNA在植物和动物中的作用是调节基因表达。对含有miR-124（一种微RNA，优先表达在大脑中）或miR-1（存在于肌肉中）的人类细胞中表达的信使RNA（mRNA）所做的微阵列分析表明，两种微RNA会改变这些细胞中的表达情况，使其与微RNA“主”细胞中的表达一样，而不管它的最初来源是哪里。这一点是通过降低大量目标mRNA转录的水平（即所谓的“下调”）以及降低所生成的蛋白质的数量来做到的。
本期目录：
Editorial
Africa 2005 p669
The world's poorest continent is rightly at the top of the global agenda this year. But the agenda needs to be set by Africa, with the outside world in a supporting role — not the other way round.
doi: 10.1038/433669a
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Top of pageNews
Salt sellers challenge US health agency using data-quality act p671
Industry fights for access to data showing salt and blood pressure link.
Meredith Wadman
doi: 10.1038/433671a
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US extends security clearance for scholars p672
Visa-related checks to remain valid for up to four years.
Geoff Brumfiel
doi: 10.1038/433672a
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Nuclear-physics research falls foul of budget cuts p672
Physics spending to drop 4% in Bush administration proposal.
Jessica Ebert
doi: 10.1038/433672b
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Online access offers fresh scope for bug identification p673
Remote-control microscope to ease work in taxonomy.
Jim Giles
doi: 10.1038/433673a
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Europe's research still lacks competitive edge, says panel p673
Five-year assessment of Framework funding comes to sober conclusion.
Quirin Schiermeier
doi: 10.1038/433673b
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Scientists urged to end feud with White House p674
Former science adviser says now is the time for a fresh start.
Geoff Brumfiel
doi: 10.1038/433674a
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Sanctions agreed over teenager's gene-therapy death p674
Out-of-court settlement ends five-year investigation into trial.
Erika Check
doi: 10.1038/433674b
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India's nuclear debate hots up after tsunami floods reactor p675
Fast-breeder prototype open to fresh debate after 26 December disaster.
K. S. Jayaraman
doi: 10.1038/433675a
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Global geoscience suffers as UNESCO curtails funding p675
Star of UN Earth sciences programme faces serious cuts.
Quirin Schiermeier
doi: 10.1038/433675b
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news in brief p676
doi: 10.1038/433676a
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Top of pageNews Features
Space technology: Setting sail for history p678
A small budget and big dreams make for a heady mix. But solar-sail pioneer Lou Friedman is ready for anything as spacecraft Cosmos 1 prepares to take on the Sun and the space agencies. Tony Reichhardt reports.
doi: 10.1038/433678a
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Cell biology: Hopping fences p680
Just how proteins jostle around in the fatty membrane that surrounds every living cell has been a source of debate for decades. Now one researcher is using an ultra-high-speed camera to watch this dance in unprecedented detail — but that hasn't stopped the arguments. Alison Abbott investigates.
doi: 10.1038/433680a
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Top of pageCorrespondence
No political will to seek innovative contraception p683
Focus instead on other reproductive issues, which may make birth-control superfluous.
Carl Djerassi
doi: 10.1038/433683a
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Emissions control needs atmospheric verification p683
Euan Nisbet
doi: 10.1038/433683b
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Top of pageBooks and Arts
In search of weighty matters p685
A hard look at the 45-year quest to detect gravitational radiation.
Virginia Trimble reviews Gravity's Shadow: The Search for Gravitational Waves by Harry Collins
doi: 10.1038/433685a
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Watson's way with words p686
Lewis Wolpert reviews The Writing Life of James D. Watson by Errol C. Friedberg
doi: 10.1038/433686a
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Science in culture p687
The Queen Anne churches in east London were precisely aligned on an east?west axis.
Heike Langenberg reviews
doi: 10.1038/433687a
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The rise of the professional p688
John Waller reviews The Victorian Scientist: The Growth of a Profession by Jack Meadows
doi: 10.1038/433688a
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Top of pagePhysics detective
Schr?dinger's mousetrap p689
Part 5: Refracted glory.
Remco Zegers
doi: 10.1038/433689a
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Top of pageNews and Views
Optoelectronics: Silicon shines on p691
Researchers are getting better at making silicon do what it really does not like to do — emit light. A silicon laser is now demonstrated that has promising features for future practical applications.
Jerome Faist
doi: 10.1038/433691a
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Cell biology: Divide and conquer p692
The discovery that cell death in nematode worms induces fragmentation of mitochondria reveals a new parallel to the death process in mammals, and may shed light on why mitochondria divide in death.
Michael Hengartner
doi: 10.1038/433692a
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Surface chemistry: Oiled acrobatics p693
Magdalena Helmer
doi: 10.1038/433693a
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Evolutionary biology: The power of natural selection p694
Adaptation by natural selection is the centrepiece of biology. Yet evolutionary biologists may be deluding themselves if they think they have a good handle on the typical strength of selection in nature.
Andrew P. Hendry
doi: 10.1038/433694a
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Planetary science: Saturn's mixed magnetosphere p695
When interplanetary shock waves hit the Cassini spacecraft and then Saturn in January 2004, it presented a unique opportunity to study the planet's magnetosphere and to compare it with that of Earth.
Fran Bagenal
doi: 10.1038/433695a
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100 and 50 years ago p695
doi: 10.1038/433695b
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Neurodegeneration: Cellular defences destroyed p696
A lack of blood flow can kill nerve cells, by causing a massive influx of calcium ions. But what's happened to the cellular mechanisms for coping with excess calcium?
Dennis W. Choi
doi: 10.1038/433696a
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Neurobiology: Bright blue times p698
The discovery of light-sensitive neurons that can adjust our body clocks prompted a search for their light-detecting molecule. We now know the identity of this pigment — and that these cells do more than was thought.
Russell G. Foster
doi: 10.1038/433698a
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Obituary: Ernst Mayr (1904?2005) p700
Jared Diamond
doi: 10.1038/nature03435
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research highlights p702
doi: 10.1038/433702a
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Top of pageBrief Communications
Insect behaviour: Migratory bands give crickets protection p703
Predators are not so lucky in picking out a flightless insect from a marching mass.
Gregory A. Sword, Patrick D. Lorch and Darryl T. Gwynne
doi: 10.1038/433703a
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Chemical communication: Butterfly anti-aphrodisiac lures parasitic wasps p704
Nina E. Fatouros, Martinus E. Huigens, Joop J. A. van Loon, Marcel Dicke and Monika Hilker
doi: 10.1038/433704a
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Top of pageReview Article
Shape coexistence and triaxiality in the superheavy nuclei p705
S. wiok, P.-H. Heenen and W. Nazarewicz
doi: 10.1038/nature03336
Abstract | Full Text | PDF (442K)
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Top of pageArticle
How sleep affects the developmental learning of bird song p710
Sébastien Derégnaucourt, Partha P. Mitra, Olga Fehér, Carolyn Pytte and Ofer Tchernichovski
doi: 10.1038/nature03275
Abstract | Full Text | PDF (1,656K) | Supplementary information
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Top of pageLetters to Nature
Morphological differences between Saturn's ultraviolet aurorae and those of Earth and Jupiter p717
J. T. Clarke, J.-C. Gérard, D. Grodent, S. Wannawichian, J. Gustin, J. Connerney, F. Crary, M. Dougherty, W. Kurth, S. W. H. Cowley, E. J. Bunce, T. Hill and J. Kim
doi: 10.1038/nature03331
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Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae p720
F. J. Crary, J. T. Clarke, M. K. Dougherty, P. G. Hanlon, K. C. Hansen, J. T. Steinberg, B. L. Barraclough, A. J. Coates, J.-C. Gérard, D. Grodent, W. S. Kurth, D. G. Mitchell, A. M. Rymer and D. T. Young
doi: 10.1038/nature03333
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An Earth-like correspondence between Saturn's auroral features and radio emission p722
W. S. Kurth, D. A. Gurnett, J. T. Clarke, P. Zarka, M. D. Desch, M. L. Kaiser, B. Cecconi, A. Lecacheux, W. M. Farrell, P. Galopeau, J.-C. Gérard, D. Grodent, R. Prangé, M. K. Dougherty and F. J. Crary
doi: 10.1038/nature03334
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A continuous-wave Raman silicon laser p725
Haisheng Rong, Richard Jones, Ansheng Liu, Oded Cohen, Dani Hak, Alexander Fang and Mario Paniccia
doi: 10.1038/nature03346
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See also: Editor's summary | News and Views by Faist
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Biological control of terrestrial silica cycling and export fluxes to watersheds p728
Louis A. Derry, Andrew C. Kurtz, Karen Ziegler and Oliver A. Chadwick
doi: 10.1038/nature03299
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Pressure sensitivity of olivine slip systems and seismic anisotropy of Earth's upper mantle p731
David Mainprice, Andréa Tommasi, Hélène Couvy, Patrick Cordier and Daniel J. Frost
doi: 10.1038/nature03266
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Stratigraphic placement and age of modern humans from Kibish, Ethiopia p733
Ian McDougall, Francis H. Brown and John G. Fleagle
doi: 10.1038/nature03258
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Parasites and climate synchronize red grouse populations p737
Isabella M. Cattadori, Daniel T. Haydon and Peter J. Hudson
doi: 10.1038/nature03276
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Addition of human melanopsin renders mammalian cells photoresponsive p741
Z. Melyan, E. E. Tarttelin, J. Bellingham, R. J. Lucas and M. W. Hankins
doi: 10.1038/nature03344
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Induction of photosensitivity by heterologous expression of melanopsin p745
Xudong Qiu, Tida Kumbalasiri, Stephanie M. Carlson, Kwoon Y. Wong, Vanitha Krishna, Ignacio Provencio and David M. Berson
doi: 10.1038/nature03345
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Melanopsin-expressing ganglion cells in primate retina signal colour and irradiance and project to the LGN p749
Dennis M. Dacey, Hsi-Wen Liao, Beth B. Peterson, Farrel R. Robinson, Vivianne C. Smith, Joel Pokorny, King-Wai Yau and Paul D. Gamlin
doi: 10.1038/nature03387
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DRP-1-mediated mitochondrial fragmentation during EGL-1-induced cell death in C. elegans p754
Ravi Jagasia, Phillip Grote, Benedikt Westermann and Barbara Conradt
doi: 10.1038/nature03316
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Rejuvenation of aged progenitor cells by exposure to a young systemic environment p760
Irina M. Conboy, Michael J. Conboy, Amy J. Wagers, Eric R. Girma, Irving L. Weissman and Thomas A. Rando
doi: 10.1038/nature03260
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Mitf cooperates with Rb1 and activates p21Cip1 expression to regulate cell cycle progression p764
Suzanne Carreira, Jane Goodall, Isil Aksan, S. Anna La Rocca, Marie-Dominique Galibert, Laurence Denat, Lionel Larue and Colin R. Goding
doi: 10.1038/nature03269
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Microarray analysis shows that some microRNAs downregulate large numbers of target mRNAs p769
Lee P. Lim, Nelson C. Lau, Philip Garrett-Engele, Andrew Grimson, Janell M. Schelter, John Castle, David P. Bartel, Peter S. Linsley and Jason M. Johnson
doi: 10.1038/nature03315
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Highly coupled ATP synthesis by F1-ATPase single molecules p773
Yannick Rondelez, Guillaume Tresset, Takako Nakashima, Yasuyuki Kato-Yamada, Hiroyuki Fujita, Shoji Takeuchi and Hiroyuki Noji
doi: 10.1038/nature03277
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corrigendum: Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution p777
International Chicken Genome Sequencing Consortium
doi: 10.1038/nature03394
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Top of pageNaturejobs
Prospects
Cultivating black gold p779
Paul Smaglik
doi: 10.1038/nj7027-779a
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Postdocs
Baby blues p780
Are women being held back by an 'innate difference': their ability to give birth? With better academic policies, motherhood and scientific excellence would not seem mutually exclusive, says Virginia Gewin.
Virginia Gewin
doi: 10.1038/nj7027-780a
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Career View
Graduate Journal: A painful transition p782
Jason Underwood
doi: 10.1038/nj7027-782a
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Scientists & Societies p782
Marika Willerroider
doi: 10.1038/nj7027-782b
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Movers p782
doi: 10.1038/nj7027-782c
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Top of pageFutures
Undead again p784
How sweet the taste of freedom.
Ken MacLeod
doi: 10.1038/433784a
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