《Nature》目录要览：2009-10-22出版
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《Nature》目录要览：2009-10-22出版
封面故事：联合国气候变化会议专题
Cover caption
现在离哥本哈根联合国气候变化会议的召开只有45天时间了，本期Nature杂志集中发表关于最热门气候话题的最新消息和评论，其中包括“不丹新闻特写”（1042页）、“秘鲁新闻特写”（1048页）、以及两篇“Opinions”文章（一篇关于印度，在1054页，另一篇关于中国，在1055页；是关于这两个国家在哥本哈根会议上 的谈判立场的）。第1056页发表篇幅为2页的一篇“Opinion”文章，作者为“京都议定书”前主席，内容涉及哥本哈根会议对良好谈判领导者的需求、这样的领导者需要掌握的技能、以及从目前的现状来看我们是否具有这样的领导者等。
DNA损伤与疾病防治（DNA damage and disease）
The DNA-damage response in human biology and disease
细胞DNA是很多有毒药物的一个活靶子，从电离辐射到环境中很多化学药物都包括在内。以它们为目标的还包括生理过程中所出现的错误。失控的、受损的DNA会引起疾病和威胁基因库。人体已形成了检测DNA损伤和调控其修复的几个系统。Stephen Jackson 和 Jiri Bartek对关于DNA损伤在分子层面上处理方式的最新研究工作进行了综述，并且还介绍了有关DNA损伤响应的知识怎样为疾病防治提供新途径。（Review p. 1071）
X染色体在物种形成中的作用（X chromosomes in speciation）
A role for a neo-sex chromosome in stickleback speciation
在日本一个三刺鱼种群（但并不是第二个与之密切相关、分享同一生境的物种）中一个新形成的性染色体系统的发现提供了这样的证据：性染色体变化在引起生殖隔离和物种形成中所起作用可能要比以前所认为的更大。基因定位研究显示，新形成的X染色体包含雄性求偶行为基因，而先祖X染色体既包含行为隔离基因，又包含杂交种雄性不育基因。这些特征在该物种与在太平洋中发现的先祖形式之间构成一个有效的生殖障碍。（Article p. 1079）
能沿ssDNA随机行走的SSB蛋白（SSB takes a walk）
SSB protein diffusion on single-stranded DNA stimulates RecA filament formation
涉及DNA的很多交易都产生一个单链中间体，它受ssDNA结合蛋白（SSB蛋白）保护而不会被降解。在保护DNA的同时，这种蛋白需要允许DNA快速接触其他蛋白，如聚合酶或修复因子，以便随后进行DNA处理。允许SSB与ssDNA保持牢固结合、同时允许DNA接触其他蛋白的一个机制，已在对大肠杆菌的这种蛋白所进行的一项单分子荧光共振能量转移研究中被发现。这种SSB是一个四聚物，将ssDNA包裹在其外围。令人吃惊的是，它能通过沿ssDNA进行随机行走来迁移，以便使其能够重新定位，尽管它仍保持紧紧结合的状态。这种扩散性质似乎具有生理意义，例如，它能帮助由DNA链交换蛋白RecA所形成的细丝的3ʹ端进行延伸。（Article p. 1092; News & Views）
一个新的土星环被发现（Saturn’s giant surprise）
Saturn's largest ring
土星的主环系统是人们所熟悉的，但它只是整个故事的一部分。太阳系的大多数环都在只相当于它们所属行星半径几倍的范围内，在这个距离处，引力加速会阻止卫星的形成。土星暗淡的E环是个例外，它由向外延伸约10个土星半径的尘埃层构成。在这个距离之外，斯皮策天文望远镜对土星最远卫星“土卫十”的观测结果还显示了一个巨大的、以前人们不知道的土星环，向外延伸的距离至少是土星半径的128到207倍。这个环的垂直厚度为土星半径的40倍，与“土卫十”沿其轨道的上下运动相一致，而且这个环还可能是由从“土卫十”喷出的物质组成的。构成该环的这些颗粒似乎遍布从主环到行星之间空间的边缘的整个土星系统。（Letter p. 1098; News & Views）
高分辨率的“受激发射显微镜”（Super-resolution microscopy）
Imaging chromophores with undetectable fluorescence by stimulated emission microscopy
要在衍射极限之外成像（比如说为了观测细胞中的微小结构），研究人员迄今为止必需依赖于用荧光发色团对成像目标进行标记，或依赖于不利用荧光、但灵敏度也要差得多的其他显微镜技术。现在，来自哈佛大学化学与化学生物学系的一个小组开发出了另外一种技术，被称为“受激发射显微镜”，它结合了以前用在其他多光子显微镜中的实验技术。该方法的灵敏度在包括无标记微管成像和用一个“chromogenic reporter”来监测lacZ基因表达的应用中得到展示。该方法的灵敏度比吸收方法高几个数量级，不受样品中其他发色团的干扰，而且适用于三维切片观测。重要的是，所有分子都是“受激发射显微镜”的潜在观测目标，所以它可用来对不发荧光的物质进行成像观测，如血红蛋白，这些物质以前用超高分辨率的显微镜无法观测。（Letter p. 1105; News & Views）
南极冰层形成与大气中CO2浓度变化的关系（Ice cap fits CO2 reduction）
Atmospheric carbon dioxide through the Eocene–Oligocene climate transition
在距今大约3400万年前的始新世-渐新世过渡时期，地球进入了一个全球变冷阶段，一个覆盖整个大陆的冰盖迅速形成，同时海平面下降。人们普遍接受的观点是，CO2水平下降是气候从温室状态向我们目前所处的冰室状态的这种转变中的一个重要因素，但人们对CO2与南极冰层形成之间的精确关系并不完全了解。Paul Pearson及其同事，利用从坦桑尼亚最近发现的一个地质剖面的保存极为完好的碳酸盐微化石中获取的硼同位素，来估计在始新世-渐新世过渡时期之前、之中和之后的大气CO2水平。他们发现，CO2浓度曾下降到了被认为会造成冰层形成的水平之下，但随后在再次下降之前又有较大反弹。这些结果证实了CO2在冰层形成中所起的中心作用，也凸显了冰层对CO2浓度变化的非线性响应。（Letter p. 1110; News & Views）
早期类人猿的进化及分类（Aping the anthropoids）
Convergent evolution of anthropoid-like adaptations in Eocene adapiform primates
最近对始新世原始灵长类Darwinius（或称“Ida”）的介绍引起了一阵骚动，因为有人称它是一个曾经“缺失的环节”，接近包括人类在内的类人猿（高等灵长类）的祖先。古生物学家对此有所担心，因为很少有人认为Darwinius所属的已灭绝的类别（即adapoids）接近类人猿。现在，Erik Seiffert及其同事介绍了一个在埃及新发现的距今已有3700万年的adapoid（被命名为Afradapis）的颌骨和牙齿。虽然详细的系统发生分析表明，这一新形式（同Darwinius一样）与类人猿只是有远亲关系，但它的确有几个能够说明趋同进化的特征。可能的情况是，Darwinius 和Afradapis都是一个类别中的成员，这个类别在始新世中期趋同进化出一些与类人猿相似的适应性特征，但它们在始新世晚期和渐新世早期最终被真正的类人猿取代了。（Letter p. 1118）
失眠影响记忆力的机制（Lost sleep, found memories）
Sleep deprivation impairs cAMP signalling in the hippocampus
众所周知睡眠剥夺会产生认知后果，包括学习和记忆缺陷等，但睡眠剥夺影响大脑功能的机制仍不清楚。新的实验工作发现环AMP通道是睡眠剥夺的一个功能目标，具体来说就是海马体中基于cAMP/PKA的弹性的受损。利用磷酸二酯酶抑制因子来拯救cAMP信号作用还可拯救有缺陷的记忆，说明增强cAMP/PKA信号作用是应对睡眠丧失所产生的认知效应的一个可能的治疗方法。（Letter p. 1122）
部分失聪伴随听觉过敏的机制（A pathway for traumatic sound）
The postsynaptic function of type II cochlear afferents
听觉部分丧失同时会伴随听觉过敏，即对较大的、甚或中等程度的声音灵敏度增强。这是有点儿矛盾的现象，其机制尚不清楚，而这种现象的确是由声音造成的痛苦，就像创伤性声音对听觉正常的人所造成的痛苦一样。现在，在分离出的大鼠耳蜗中用千兆欧姆封接光纤内记录及燃料标记方法所做实验，确定长期很神秘的II型耳蜗传入神经元为指示创伤性声音的一个潜在通道。这些神经元从耳蜗外毛细胞接收突触输入，并以与体细胞C-纤维相似的方式被ATP激发（ATP已知在组织损伤期间会被释放出来）。在音量很高的创伤性声音下，毛细胞活动与所释放的ATP相结合，可能会为这些在解剖学上比较独特的II型耳蜗传入神经元提供充分“刺激”。（ Letter p. 1126）
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NEWS AND VIEWS
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Chemical physics: Molecular conformations fielded pp1063-1064
Studies of molecular dynamics can be foiled by the presence of stereoisomers -
molecules that have the same bond sequence arranged in different geometries.
This problem has now been deflected.
Albert Stolow
doi:10.1038/4611063a
http://www.nature.com/nature/journal/v461/n7267/full/4611063a.html
Solar System: Saturn's colossal ring pp1064-1065
A hitherto undetected disk of debris around Saturn is the largest ever found
to be orbiting a planet. This ring may hold the key to one of the most
enigmatic landscapes in the Solar System.
Matthew S. Tiscareno and Matthew M. Hedman
doi:10.1038/4611064a
http://www.nature.com/nature/journal/v461/n7267/full/4611064a.html
Climate change: Early survival of Antarctic ice pp1065-1066
Analyses of boron isotopes in ancient marine carbonate sediments provide an
enlightening perspective on the links between carbon dioxide and ice-cap
cover at a climatically momentous time in Earth's history.
Damien Lemarchand
doi:10.1038/4611065a
http://www.nature.com/nature/journal/v461/n7267/full/4611065a.html
Ecology: Kelp in postglacial time p1066
Tim Lincoln
doi:10.1038/4611066a
http://www.nature.com/nature/journal/v461/n7267/full/4611066a.html
Molecular biology: Slip sliding on DNA pp1067-1068
Dedicated binding proteins stabilize single-stranded DNA, protecting it from
breakage and distortion. Once thought to form inert complexes with DNA, such
proteins are now shown to be remarkably mobile.
Nicholas P. George and James L. Keck
doi:10.1038/4611067a
http://www.nature.com/nature/journal/v461/n7267/full/4611067a.html
50 & 100 years ago p1068
doi:10.1038/4611068b
http://www.nature.com/nature/journal/v461/n7267/full/4611068b.html
Biochemistry: Enzyme's black box cracked open pp1068-1069
Polyketide synthase enzymes make compounds from molecules that synthetic
chemists can't easily control. The basis of the enzymes' ability to use
such unstable precursors has been laid bare.
David H. Sherman
doi:10.1038/4611068a
http://www.nature.com/nature/journal/v461/n7267/full/4611068a.html
Microscopy: Light from the dark pp1069-1070
Fluorescence microscopy is the most popular way to image biomolecules,
but it leaves many of them in the dark. Non-fluorescent, light-absorbing
molecules can now be viewed by a method that turns them into mini-lasers.
Stefan W. Hell and Eva Rittweger
doi:10.1038/4611069a
http://www.nature.com/nature/journal/v461/n7267/full/4611069a.html
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REVIEW
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The DNA-damage response in human biology and disease pp1071-1078
Stephen P. Jackson and Jiri Bartek
doi:10.1038/nature08467
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08467.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08467.html
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ARTICLES
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A role for a neo-sex chromosome in stickleback speciation pp1079-1083
Closely related species often have different sex-chromosome systems, but it
is not known whether sex-chromosome turnover contributes to the evolution of
reproductive isolation between species. Here, a neo-sex chromosome is
identified in only one member of a sympatric species pair of stickleback
fish in Japan. The newly evolved sex chromosome is found to contain genes
that contribute to speciation, suggesting that sex-chromosome turnover might
have a greater role in speciation than was previously appreciated.
Jun Kitano et al.
doi:10.1038/nature08441
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08441.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08441.html
Pten in stromal fibroblasts suppresses mammary epithelial tumours pp1084-1091
The tumour microenvironment has an important role in tumorigenesis. Here,
the genetic inactivation of Pten in stromal fibroblasts of mouse mammary
glands is shown to accelerate the initiation, progression and malignant
transformation of mammary epithelial tumours. The data presented suggest
that the Pten-Ets2 axis - Ets2 being a transcription factor activated by
the loss of Pten - is a critical stroma-specific signalling pathway that
suppresses mammary epithelial tumours.
Anthony J. Trimboli et al.
doi:10.1038/nature08486
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08486.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08486.html
SSB protein diffusion on single-stranded DNA stimulates RecA filament formation
pp1092-1097
During DNA metabolism, single-stranded DNA intermediates are often generated
that are protected from degradation by binding of ssDNA-binding (SSB) proteins.
Bacterial SSB protein forms a tetramer that wraps ssDNA using its four subunits.
Here it is shown that tetrameric SSB protein can spontaneously migrate along
ssDNA; this diffusional movement introducing a new model for the redistribution
of the SSB protein, while remaining bound to ssDNA during recombination and
repair processes.
Rahul Roy, Alexander G. Kozlov, Timothy M. Lohman and Taekjip Ha
doi:10.1038/nature08442
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08442.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08442.html
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LETTERS
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Saturn's largest ring pp1098-1100
In the Solar System, planetary rings tend to lie within a few radii of their
host body, because at these distances gravitational accelerations inhibit
satellite formation. One of the best known exceptions to this rule is Saturn's
E ring, a broad sheet of dust continuously supplied by source satellites that
fades from view at five to ten planetary radii. An enormous ring associated
with Saturn's outer moon Phoebe is now reported; it extends from at least
128 to 207 Saturn radii.
Anne J. Verbiscer, Michael F. Skrutskie and Douglas P. Hamilton
doi:10.1038/nature08515
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08515.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08515.html
Information causality as a physical principle pp1101-1104
A broad class of theories exist which share the distinguishing characteristics
of quantum mechanics but allow even stronger correlations. Here, the principle
of 'information causality' is introduced and shown to be respected by both
classical and quantum physics; however, it is violated by other models that
resemble quantum mechanics but with stronger correlations. It is suggested
that information causality may help to distinguish physical theories from
non-physical ones.
Marcin Pawlowski et al.
doi:10.1038/nature08400
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08400.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08400.html
Imaging chromophores with undetectable fluorescence by stimulated emission
microscopy pp1105-1109
Imaging beyond the diffraction limit - to resolve tiny features in cells, for
example - has had to rely on tagging the imaged substance with fluorescent
chromophores or other techniques that are much less sensitive, like absorption.
The use of stimulated emission (a property, unlike fluorescence, which all
molecules can have) is now reported; sensitivity is orders of magnitude higher
than for spontaneous emission or absorption contrast, and fluorescence is not used.
Wei Min et al.
doi:10.1038/nature08438
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08438.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08438.html
Atmospheric carbon dioxide through the Eocene--Oligocene climate transition
pp1110-1113
It is generally accepted that declining carbon dioxide (CO2) levels were an
important factor in the Eocene-Oligocene transition about 34 million years ago,
when the world shifted from a greenhouse to an icehouse climate. Here, using the
boron isotope pH proxy on carbonate microfossils from a recently discovered
geological section in Tanzania, atmospheric CO2 levels before, during and after
the climate transition are estimated.
Paul N. Pearson, Gavin L. Foster and Bridget S. Wade
doi:10.1038/nature08447
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08447.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08447.html
Trench-parallel anisotropy produced by serpentine deformation in the hydrated
mantle wedge pp1114-1117
Although seismic anisotropy in the upper mantle is generally attributed to the
crystal-preferred orientation of olivine, the strong trench-parallel anisotropy
observed in several subduction systems is difficult to explain in terms of olivine
anisotropy. Using high-pressure deformation experiments, it is now shown that the
crystal-preferred orientation of serpentine, the main hydrous mineral in the
upper mantle, can produce the strong trench-parallel seismic anisotropy observed
in such subduction systems.
Ikuo Katayama, Ken-ichi Hirauchi, Katsuyoshi Michibayashi and Jun-ichi Ando
doi:10.1038/nature08513
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08513.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08513.html
Convergent evolution of anthropoid-like adaptations in Eocene adapiform primates
pp1118-1121
The recent description of the primitive Eocene primate Darwinius has been widely
publicized as an important 'link' in the early evolution of Anthropoidea. The
extinct group to which Darwinius belongs, the 'adapoid' primates, was not generally
thought to be close to the anthropoids. Here, the jaw and teeth of a large-bodied
adapiform from the earliest late Eocene of Egypt is described; detailed phylogenetic
analysis shows that adapiforms were only very distant relatives of anthropoids but
that they do have some features that suggest convergent evolution.
Erik R. Seiffert, Jonathan M. G. Perry, Elwyn L. Simons and Doug M. Boyer
doi:10.1038/nature08429
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08429.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08429.html
Sleep deprivation impairs cAMP signalling in the hippocampus pp1122-1125
Sleep deprivation can have adverse cognitive effects, with one of the major
consequences on the brain being memory deficits in learning models that are
dependent on the hippocampus. A molecular mechanism by which brief sleep
deprivation alters hippocampal function is now identified in mice; it involves
the impairment of cyclic-AMP- and protein-kinase-A-dependent forms of synaptic plasticity.
Christopher G. Vecsey et al.
doi:10.1038/nature08488
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08488.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08488.html
The postsynaptic function of type II cochlear afferents pp1126-1129
The mammalian cochlea is innervated predominantly by type I sensory neurons, but
also present are the far less numerous type II neurons, the function of which has
been the subject of much speculation. Studies of type II fibres now show that they
receive excitatory glutamatergic synaptic input and that they are depolarized by
exogenous ATP. These results prove that type II neurons function as cochlear
afferents, and can be modulated by ATP.
Catherine Weisz, Elisabeth Glowatzki and Paul Fuchs
doi:10.1038/nature08487
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08487.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08487.html
Unexpected consequences of a sudden and massive transposon amplification on rice
gene expression pp1130-1134
Most eukaryotic genomes harbour numerous transposable elements which contribute to
gene and genome evolution; however, how genomic integrity is maintained in the face
of high transposition is not completely understood. High-throughput sequencing of
individual rice plants is now used to assess the impact of insertion on gene
expression. The vast majority of transposable element insertions are found either
to upregulate or to have no detectable effect on gene transcription.
Ken Naito et al.
doi:10.1038/nature08479
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08479.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08479.html
A transposon-induced epigenetic change leads to sex determination in melon
pp1135-1138
During the development of flowering plants, sex determination leads to the physical
separation of male and female flowers from an originally bisexual floral meristem.
Here, in melon, the transition from male to female flowers is shown to result from
epigenetic changes in the promoter of a transcription factor, CmWIP1. The data
presented are used to propose a model for the control and development of male,
female and hermaphrodite flowers in melon.
Antoine Martin et al.
doi:10.1038/nature08498
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08498.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08498.html
Structural basis for biosynthetic programming of fungal aromatic polyketide
cyclization pp1139-1143
Regiospecific cyclizations of reactive poly-[beta]-keto intermediates are known
to lead to the structural variability of aromatic products of fungal nonreducing,
multidomain iterative polyketide synthases (NR-PKS group of IPKSs), but questions
about the process remain. The crystal structure and mutational studies of a
dissected product template monodomain from PksA, the NR-PKS that initiates the
biosynethesis of the hepatocarcinogen aflatoxin B1, are now presented.
Jason M. Crawford et al.
doi:10.1038/nature08475
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08475.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08475.html
Structural basis for translational fidelity ensured by transfer RNA lysidine
synthetase pp1144-1148
tRNAs are transcribed as precursor molecules that are then shortened, have a
short sequence added, and may then undergo modifications of certain nucleotides
to generate a different amino acid specificity. Here, tRNAIle2 lysidine synthetase
(TilS) - a bacterial enzyme that carries out a nucleotide modification - is shown
to specifically recognize and modify tRNAIle2 in its precursor form, thereby
avoiding potential translation errors.
Kotaro Nakanishi et al.
doi:10.1038/nature08474
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08474.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08474.html
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TECHNOLOGY FEATURES
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Neural circuits: Putting neurons on the map pp1149-1152
After a long lull, powerful new technologies are putting the charting of brain
circuitry back on neuroscientists' agenda. Michael Eisenstein explores the
challenge of mapping the mammalian mind.
Michael Eisenstein
doi:10.1038/4611149a
http://www.nature.com/nature/journal/v461/n7267/full/4611149a.html
Neural circuits: Whose map is it anyway? p1150
doi:10.1038/4611150a
http://www.nature.com/nature/journal/v461/n7267/full/4611150a.html
Neural circuits: Table of suppliers pp1153-1154
doi:10.1038/4611153a
http://www.nature.com/nature/journal/v461/n7267/full/4611153a.html
----------------------
FUTURES
----------------------
Tropicbird p1162
The winds of change.
K V
doi:10.1038/4611162a
http://www.nature.com/nature/journal/v461/n7267/full/4611162a.html
Cover caption
现在离哥本哈根联合国气候变化会议的召开只有45天时间了，本期Nature杂志集中发表关于最热门气候话题的最新消息和评论，其中包括“不丹新闻特写”（1042页）、“秘鲁新闻特写”（1048页）、以及两篇“Opinions”文章（一篇关于印度，在1054页，另一篇关于中国，在1055页；是关于这两个国家在哥本哈根会议上 的谈判立场的）。第1056页发表篇幅为2页的一篇“Opinion”文章，作者为“京都议定书”前主席，内容涉及哥本哈根会议对良好谈判领导者的需求、这样的领导者需要掌握的技能、以及从目前的现状来看我们是否具有这样的领导者等。
DNA损伤与疾病防治（DNA damage and disease）
The DNA-damage response in human biology and disease
细胞DNA是很多有毒药物的一个活靶子，从电离辐射到环境中很多化学药物都包括在内。以它们为目标的还包括生理过程中所出现的错误。失控的、受损的DNA会引起疾病和威胁基因库。人体已形成了检测DNA损伤和调控其修复的几个系统。Stephen Jackson 和 Jiri Bartek对关于DNA损伤在分子层面上处理方式的最新研究工作进行了综述，并且还介绍了有关DNA损伤响应的知识怎样为疾病防治提供新途径。（Review p. 1071）
X染色体在物种形成中的作用（X chromosomes in speciation）
A role for a neo-sex chromosome in stickleback speciation
在日本一个三刺鱼种群（但并不是第二个与之密切相关、分享同一生境的物种）中一个新形成的性染色体系统的发现提供了这样的证据：性染色体变化在引起生殖隔离和物种形成中所起作用可能要比以前所认为的更大。基因定位研究显示，新形成的X染色体包含雄性求偶行为基因，而先祖X染色体既包含行为隔离基因，又包含杂交种雄性不育基因。这些特征在该物种与在太平洋中发现的先祖形式之间构成一个有效的生殖障碍。（Article p. 1079）
能沿ssDNA随机行走的SSB蛋白（SSB takes a walk）
SSB protein diffusion on single-stranded DNA stimulates RecA filament formation
涉及DNA的很多交易都产生一个单链中间体，它受ssDNA结合蛋白（SSB蛋白）保护而不会被降解。在保护DNA的同时，这种蛋白需要允许DNA快速接触其他蛋白，如聚合酶或修复因子，以便随后进行DNA处理。允许SSB与ssDNA保持牢固结合、同时允许DNA接触其他蛋白的一个机制，已在对大肠杆菌的这种蛋白所进行的一项单分子荧光共振能量转移研究中被发现。这种SSB是一个四聚物，将ssDNA包裹在其外围。令人吃惊的是，它能通过沿ssDNA进行随机行走来迁移，以便使其能够重新定位，尽管它仍保持紧紧结合的状态。这种扩散性质似乎具有生理意义，例如，它能帮助由DNA链交换蛋白RecA所形成的细丝的3ʹ端进行延伸。（Article p. 1092; News & Views）
一个新的土星环被发现（Saturn’s giant surprise）
Saturn's largest ring
土星的主环系统是人们所熟悉的，但它只是整个故事的一部分。太阳系的大多数环都在只相当于它们所属行星半径几倍的范围内，在这个距离处，引力加速会阻止卫星的形成。土星暗淡的E环是个例外，它由向外延伸约10个土星半径的尘埃层构成。在这个距离之外，斯皮策天文望远镜对土星最远卫星“土卫十”的观测结果还显示了一个巨大的、以前人们不知道的土星环，向外延伸的距离至少是土星半径的128到207倍。这个环的垂直厚度为土星半径的40倍，与“土卫十”沿其轨道的上下运动相一致，而且这个环还可能是由从“土卫十”喷出的物质组成的。构成该环的这些颗粒似乎遍布从主环到行星之间空间的边缘的整个土星系统。（Letter p. 1098; News & Views）
高分辨率的“受激发射显微镜”（Super-resolution microscopy）
Imaging chromophores with undetectable fluorescence by stimulated emission microscopy
要在衍射极限之外成像（比如说为了观测细胞中的微小结构），研究人员迄今为止必需依赖于用荧光发色团对成像目标进行标记，或依赖于不利用荧光、但灵敏度也要差得多的其他显微镜技术。现在，来自哈佛大学化学与化学生物学系的一个小组开发出了另外一种技术，被称为“受激发射显微镜”，它结合了以前用在其他多光子显微镜中的实验技术。该方法的灵敏度在包括无标记微管成像和用一个“chromogenic reporter”来监测lacZ基因表达的应用中得到展示。该方法的灵敏度比吸收方法高几个数量级，不受样品中其他发色团的干扰，而且适用于三维切片观测。重要的是，所有分子都是“受激发射显微镜”的潜在观测目标，所以它可用来对不发荧光的物质进行成像观测，如血红蛋白，这些物质以前用超高分辨率的显微镜无法观测。（Letter p. 1105; News & Views）
南极冰层形成与大气中CO2浓度变化的关系（Ice cap fits CO2 reduction）
Atmospheric carbon dioxide through the Eocene–Oligocene climate transition
在距今大约3400万年前的始新世-渐新世过渡时期，地球进入了一个全球变冷阶段，一个覆盖整个大陆的冰盖迅速形成，同时海平面下降。人们普遍接受的观点是，CO2水平下降是气候从温室状态向我们目前所处的冰室状态的这种转变中的一个重要因素，但人们对CO2与南极冰层形成之间的精确关系并不完全了解。Paul Pearson及其同事，利用从坦桑尼亚最近发现的一个地质剖面的保存极为完好的碳酸盐微化石中获取的硼同位素，来估计在始新世-渐新世过渡时期之前、之中和之后的大气CO2水平。他们发现，CO2浓度曾下降到了被认为会造成冰层形成的水平之下，但随后在再次下降之前又有较大反弹。这些结果证实了CO2在冰层形成中所起的中心作用，也凸显了冰层对CO2浓度变化的非线性响应。（Letter p. 1110; News & Views）
早期类人猿的进化及分类（Aping the anthropoids）
Convergent evolution of anthropoid-like adaptations in Eocene adapiform primates
最近对始新世原始灵长类Darwinius（或称“Ida”）的介绍引起了一阵骚动，因为有人称它是一个曾经“缺失的环节”，接近包括人类在内的类人猿（高等灵长类）的祖先。古生物学家对此有所担心，因为很少有人认为Darwinius所属的已灭绝的类别（即adapoids）接近类人猿。现在，Erik Seiffert及其同事介绍了一个在埃及新发现的距今已有3700万年的adapoid（被命名为Afradapis）的颌骨和牙齿。虽然详细的系统发生分析表明，这一新形式（同Darwinius一样）与类人猿只是有远亲关系，但它的确有几个能够说明趋同进化的特征。可能的情况是，Darwinius 和Afradapis都是一个类别中的成员，这个类别在始新世中期趋同进化出一些与类人猿相似的适应性特征，但它们在始新世晚期和渐新世早期最终被真正的类人猿取代了。（Letter p. 1118）
失眠影响记忆力的机制（Lost sleep, found memories）
Sleep deprivation impairs cAMP signalling in the hippocampus
众所周知睡眠剥夺会产生认知后果，包括学习和记忆缺陷等，但睡眠剥夺影响大脑功能的机制仍不清楚。新的实验工作发现环AMP通道是睡眠剥夺的一个功能目标，具体来说就是海马体中基于cAMP/PKA的弹性的受损。利用磷酸二酯酶抑制因子来拯救cAMP信号作用还可拯救有缺陷的记忆，说明增强cAMP/PKA信号作用是应对睡眠丧失所产生的认知效应的一个可能的治疗方法。（Letter p. 1122）
部分失聪伴随听觉过敏的机制（A pathway for traumatic sound）
The postsynaptic function of type II cochlear afferents
听觉部分丧失同时会伴随听觉过敏，即对较大的、甚或中等程度的声音灵敏度增强。这是有点儿矛盾的现象，其机制尚不清楚，而这种现象的确是由声音造成的痛苦，就像创伤性声音对听觉正常的人所造成的痛苦一样。现在，在分离出的大鼠耳蜗中用千兆欧姆封接光纤内记录及燃料标记方法所做实验，确定长期很神秘的II型耳蜗传入神经元为指示创伤性声音的一个潜在通道。这些神经元从耳蜗外毛细胞接收突触输入，并以与体细胞C-纤维相似的方式被ATP激发（ATP已知在组织损伤期间会被释放出来）。在音量很高的创伤性声音下，毛细胞活动与所释放的ATP相结合，可能会为这些在解剖学上比较独特的II型耳蜗传入神经元提供充分“刺激”。（ Letter p. 1126）
----------------------
NEWS AND VIEWS
----------------------
Chemical physics: Molecular conformations fielded pp1063-1064
Studies of molecular dynamics can be foiled by the presence of stereoisomers -
molecules that have the same bond sequence arranged in different geometries.
This problem has now been deflected.
Albert Stolow
doi:10.1038/4611063a
http://www.nature.com/nature/journal/v461/n7267/full/4611063a.html
Solar System: Saturn's colossal ring pp1064-1065
A hitherto undetected disk of debris around Saturn is the largest ever found
to be orbiting a planet. This ring may hold the key to one of the most
enigmatic landscapes in the Solar System.
Matthew S. Tiscareno and Matthew M. Hedman
doi:10.1038/4611064a
http://www.nature.com/nature/journal/v461/n7267/full/4611064a.html
Climate change: Early survival of Antarctic ice pp1065-1066
Analyses of boron isotopes in ancient marine carbonate sediments provide an
enlightening perspective on the links between carbon dioxide and ice-cap
cover at a climatically momentous time in Earth's history.
Damien Lemarchand
doi:10.1038/4611065a
http://www.nature.com/nature/journal/v461/n7267/full/4611065a.html
Ecology: Kelp in postglacial time p1066
Tim Lincoln
doi:10.1038/4611066a
http://www.nature.com/nature/journal/v461/n7267/full/4611066a.html
Molecular biology: Slip sliding on DNA pp1067-1068
Dedicated binding proteins stabilize single-stranded DNA, protecting it from
breakage and distortion. Once thought to form inert complexes with DNA, such
proteins are now shown to be remarkably mobile.
Nicholas P. George and James L. Keck
doi:10.1038/4611067a
http://www.nature.com/nature/journal/v461/n7267/full/4611067a.html
50 & 100 years ago p1068
doi:10.1038/4611068b
http://www.nature.com/nature/journal/v461/n7267/full/4611068b.html
Biochemistry: Enzyme's black box cracked open pp1068-1069
Polyketide synthase enzymes make compounds from molecules that synthetic
chemists can't easily control. The basis of the enzymes' ability to use
such unstable precursors has been laid bare.
David H. Sherman
doi:10.1038/4611068a
http://www.nature.com/nature/journal/v461/n7267/full/4611068a.html
Microscopy: Light from the dark pp1069-1070
Fluorescence microscopy is the most popular way to image biomolecules,
but it leaves many of them in the dark. Non-fluorescent, light-absorbing
molecules can now be viewed by a method that turns them into mini-lasers.
Stefan W. Hell and Eva Rittweger
doi:10.1038/4611069a
http://www.nature.com/nature/journal/v461/n7267/full/4611069a.html
----------------------
REVIEW
----------------------
The DNA-damage response in human biology and disease pp1071-1078
Stephen P. Jackson and Jiri Bartek
doi:10.1038/nature08467
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08467.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08467.html
----------------------
ARTICLES
----------------------
A role for a neo-sex chromosome in stickleback speciation pp1079-1083
Closely related species often have different sex-chromosome systems, but it
is not known whether sex-chromosome turnover contributes to the evolution of
reproductive isolation between species. Here, a neo-sex chromosome is
identified in only one member of a sympatric species pair of stickleback
fish in Japan. The newly evolved sex chromosome is found to contain genes
that contribute to speciation, suggesting that sex-chromosome turnover might
have a greater role in speciation than was previously appreciated.
Jun Kitano et al.
doi:10.1038/nature08441
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08441.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08441.html
Pten in stromal fibroblasts suppresses mammary epithelial tumours pp1084-1091
The tumour microenvironment has an important role in tumorigenesis. Here,
the genetic inactivation of Pten in stromal fibroblasts of mouse mammary
glands is shown to accelerate the initiation, progression and malignant
transformation of mammary epithelial tumours. The data presented suggest
that the Pten-Ets2 axis - Ets2 being a transcription factor activated by
the loss of Pten - is a critical stroma-specific signalling pathway that
suppresses mammary epithelial tumours.
Anthony J. Trimboli et al.
doi:10.1038/nature08486
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08486.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08486.html
SSB protein diffusion on single-stranded DNA stimulates RecA filament formation
pp1092-1097
During DNA metabolism, single-stranded DNA intermediates are often generated
that are protected from degradation by binding of ssDNA-binding (SSB) proteins.
Bacterial SSB protein forms a tetramer that wraps ssDNA using its four subunits.
Here it is shown that tetrameric SSB protein can spontaneously migrate along
ssDNA; this diffusional movement introducing a new model for the redistribution
of the SSB protein, while remaining bound to ssDNA during recombination and
repair processes.
Rahul Roy, Alexander G. Kozlov, Timothy M. Lohman and Taekjip Ha
doi:10.1038/nature08442
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08442.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08442.html
----------------------
LETTERS
----------------------
Saturn's largest ring pp1098-1100
In the Solar System, planetary rings tend to lie within a few radii of their
host body, because at these distances gravitational accelerations inhibit
satellite formation. One of the best known exceptions to this rule is Saturn's
E ring, a broad sheet of dust continuously supplied by source satellites that
fades from view at five to ten planetary radii. An enormous ring associated
with Saturn's outer moon Phoebe is now reported; it extends from at least
128 to 207 Saturn radii.
Anne J. Verbiscer, Michael F. Skrutskie and Douglas P. Hamilton
doi:10.1038/nature08515
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08515.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08515.html
Information causality as a physical principle pp1101-1104
A broad class of theories exist which share the distinguishing characteristics
of quantum mechanics but allow even stronger correlations. Here, the principle
of 'information causality' is introduced and shown to be respected by both
classical and quantum physics; however, it is violated by other models that
resemble quantum mechanics but with stronger correlations. It is suggested
that information causality may help to distinguish physical theories from
non-physical ones.
Marcin Pawlowski et al.
doi:10.1038/nature08400
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08400.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08400.html
Imaging chromophores with undetectable fluorescence by stimulated emission
microscopy pp1105-1109
Imaging beyond the diffraction limit - to resolve tiny features in cells, for
example - has had to rely on tagging the imaged substance with fluorescent
chromophores or other techniques that are much less sensitive, like absorption.
The use of stimulated emission (a property, unlike fluorescence, which all
molecules can have) is now reported; sensitivity is orders of magnitude higher
than for spontaneous emission or absorption contrast, and fluorescence is not used.
Wei Min et al.
doi:10.1038/nature08438
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08438.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08438.html
Atmospheric carbon dioxide through the Eocene--Oligocene climate transition
pp1110-1113
It is generally accepted that declining carbon dioxide (CO2) levels were an
important factor in the Eocene-Oligocene transition about 34 million years ago,
when the world shifted from a greenhouse to an icehouse climate. Here, using the
boron isotope pH proxy on carbonate microfossils from a recently discovered
geological section in Tanzania, atmospheric CO2 levels before, during and after
the climate transition are estimated.
Paul N. Pearson, Gavin L. Foster and Bridget S. Wade
doi:10.1038/nature08447
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08447.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08447.html
Trench-parallel anisotropy produced by serpentine deformation in the hydrated
mantle wedge pp1114-1117
Although seismic anisotropy in the upper mantle is generally attributed to the
crystal-preferred orientation of olivine, the strong trench-parallel anisotropy
observed in several subduction systems is difficult to explain in terms of olivine
anisotropy. Using high-pressure deformation experiments, it is now shown that the
crystal-preferred orientation of serpentine, the main hydrous mineral in the
upper mantle, can produce the strong trench-parallel seismic anisotropy observed
in such subduction systems.
Ikuo Katayama, Ken-ichi Hirauchi, Katsuyoshi Michibayashi and Jun-ichi Ando
doi:10.1038/nature08513
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08513.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08513.html
Convergent evolution of anthropoid-like adaptations in Eocene adapiform primates
pp1118-1121
The recent description of the primitive Eocene primate Darwinius has been widely
publicized as an important 'link' in the early evolution of Anthropoidea. The
extinct group to which Darwinius belongs, the 'adapoid' primates, was not generally
thought to be close to the anthropoids. Here, the jaw and teeth of a large-bodied
adapiform from the earliest late Eocene of Egypt is described; detailed phylogenetic
analysis shows that adapiforms were only very distant relatives of anthropoids but
that they do have some features that suggest convergent evolution.
Erik R. Seiffert, Jonathan M. G. Perry, Elwyn L. Simons and Doug M. Boyer
doi:10.1038/nature08429
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08429.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08429.html
Sleep deprivation impairs cAMP signalling in the hippocampus pp1122-1125
Sleep deprivation can have adverse cognitive effects, with one of the major
consequences on the brain being memory deficits in learning models that are
dependent on the hippocampus. A molecular mechanism by which brief sleep
deprivation alters hippocampal function is now identified in mice; it involves
the impairment of cyclic-AMP- and protein-kinase-A-dependent forms of synaptic plasticity.
Christopher G. Vecsey et al.
doi:10.1038/nature08488
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08488.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08488.html
The postsynaptic function of type II cochlear afferents pp1126-1129
The mammalian cochlea is innervated predominantly by type I sensory neurons, but
also present are the far less numerous type II neurons, the function of which has
been the subject of much speculation. Studies of type II fibres now show that they
receive excitatory glutamatergic synaptic input and that they are depolarized by
exogenous ATP. These results prove that type II neurons function as cochlear
afferents, and can be modulated by ATP.
Catherine Weisz, Elisabeth Glowatzki and Paul Fuchs
doi:10.1038/nature08487
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08487.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08487.html
Unexpected consequences of a sudden and massive transposon amplification on rice
gene expression pp1130-1134
Most eukaryotic genomes harbour numerous transposable elements which contribute to
gene and genome evolution; however, how genomic integrity is maintained in the face
of high transposition is not completely understood. High-throughput sequencing of
individual rice plants is now used to assess the impact of insertion on gene
expression. The vast majority of transposable element insertions are found either
to upregulate or to have no detectable effect on gene transcription.
Ken Naito et al.
doi:10.1038/nature08479
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08479.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08479.html
A transposon-induced epigenetic change leads to sex determination in melon
pp1135-1138
During the development of flowering plants, sex determination leads to the physical
separation of male and female flowers from an originally bisexual floral meristem.
Here, in melon, the transition from male to female flowers is shown to result from
epigenetic changes in the promoter of a transcription factor, CmWIP1. The data
presented are used to propose a model for the control and development of male,
female and hermaphrodite flowers in melon.
Antoine Martin et al.
doi:10.1038/nature08498
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08498.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08498.html
Structural basis for biosynthetic programming of fungal aromatic polyketide
cyclization pp1139-1143
Regiospecific cyclizations of reactive poly-[beta]-keto intermediates are known
to lead to the structural variability of aromatic products of fungal nonreducing,
multidomain iterative polyketide synthases (NR-PKS group of IPKSs), but questions
about the process remain. The crystal structure and mutational studies of a
dissected product template monodomain from PksA, the NR-PKS that initiates the
biosynethesis of the hepatocarcinogen aflatoxin B1, are now presented.
Jason M. Crawford et al.
doi:10.1038/nature08475
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08475.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08475.html
Structural basis for translational fidelity ensured by transfer RNA lysidine
synthetase pp1144-1148
tRNAs are transcribed as precursor molecules that are then shortened, have a
short sequence added, and may then undergo modifications of certain nucleotides
to generate a different amino acid specificity. Here, tRNAIle2 lysidine synthetase
(TilS) - a bacterial enzyme that carries out a nucleotide modification - is shown
to specifically recognize and modify tRNAIle2 in its precursor form, thereby
avoiding potential translation errors.
Kotaro Nakanishi et al.
doi:10.1038/nature08474
Abstract: http://www.nature.com/nature/journal/v461/n7267/abs/nature08474.html
Article: http://www.nature.com/nature/journal/v461/n7267/full/nature08474.html
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TECHNOLOGY FEATURES
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Neural circuits: Putting neurons on the map pp1149-1152
After a long lull, powerful new technologies are putting the charting of brain
circuitry back on neuroscientists' agenda. Michael Eisenstein explores the
challenge of mapping the mammalian mind.
Michael Eisenstein
doi:10.1038/4611149a
http://www.nature.com/nature/journal/v461/n7267/full/4611149a.html
Neural circuits: Whose map is it anyway? p1150
doi:10.1038/4611150a
http://www.nature.com/nature/journal/v461/n7267/full/4611150a.html
Neural circuits: Table of suppliers pp1153-1154
doi:10.1038/4611153a
http://www.nature.com/nature/journal/v461/n7267/full/4611153a.html
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FUTURES
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Tropicbird p1162
The winds of change.
K V
doi:10.1038/4611162a
http://www.nature.com/nature/journal/v461/n7267/full/4611162a.html
| 《Nature》目录要览 — 2011-04-28出版 |
| 《Nature》目录要览：2011-01-20出版 |
| 《Nature》目录要览：2010-12-23出版 |
| 《Nature》目录要览：2010-12-16出版 |
| 《Nature》目录要览：2010-12-09出版 |
| 《Nature》目录要览：2010-12-02出版 |
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