《Nature》目录要览：2010-07-22出版

封面故事：气候变化对动物种群的影响
Coupled dynamics of body mass and population growth in response to environmental change
气候变化影响植物和动物生命中定期发生的事件，如发芽、迁徙和冬眠以及种群动态和形态变化。同时对所有这些相互作用的因素进行监测是困难的，但对一种冬眠型哺乳动物（美国科罗拉多州Upper East River Valley一个亚高山环境中的一种黄腹土拨鼠种群）所做的一项长期生命史研究，提供了适合于完成这项任务的数据。1976–2008年间的气候变化使这些土拨鼠过早从冬眠中苏醒过来，延长了它们的生长季，所以它们现在要比其开始冬眠时重一些。与此同时，体型较大个体的适应性也增加了，导致种群规模迅速增大。正如Marcel Visser在配发的News & Views文章中所解释的那样，气候变化生态学中的主要挑战是预测未来气候变化对于种群的影响。关于土拨鼠的这项研究工作提供了实现这一目的所需的数据。本期封面所示为冬天在落基山脉拍摄的黄腹土拨鼠照片。（Letter p. 482; News & Views）（Mary Plage/ Photolibrary）


可以降血糖的新药物（Novel antidiabetics）
Anti-diabetic drugs inhibit obesity-linked phosphorylation of PPARγ by Cdk5
“噻唑烷二酮”类降糖药物如“罗西格列酮”和“匹格列酮”已知通过核受体PPARγ发挥作用，但它们胰岛素敏化效应之机制的某些方面仍然是个谜。现在，Choi等人报告，PPARγ 被Cdk5的磷酸化与小鼠由高脂肪饮食所诱导的肥胖有关。几种可以降血糖的PPARγ配体直接抑制Cdk5 对 PPARγ的这种作用，从而支持一种更为正常的非糖尿病型基因表达模式。另外，“罗西格列酮”对人体中这种PPARγ磷酸化的抑制也与其降糖效应密切相关。这一不同寻常的药理机制为肥胖症/糖尿病发病机理中的Cdk5-PPARγ联系、为这些疾病中以及代谢综合症（即多种疾病的综合，它们会增加心血管疾病和糖尿病的发病风险）中PPARγ配体的治疗作用提出了一个新模型。（Article p. 451; News & Views）


决定动作开始和停止时机的神经机制（Knowing when to stop）
Start/stop signals emerge in nigrostriatal circuits during sequence learning
当执行一个行为时，动作序列的适当起动和终止至关重要；这个过程在帕金森氏症和亨廷顿症等“黑质纹状体”疾病中不能正常进行。人们对主管一个固定行为模式的学习和执行的神经机制还不是很了解，但Xin Jin 和Rui Costa揭示了在任务训练过程中基底神经节回路中所出现的起动/停止神经激发模式。小鼠能够学会按自己确定的进度非常精确地执行固定数量的一组重复性动作——它们要完成的任务是压杠杆，完成之后可以获得蔗糖作为奖励。利用这一任务，Jin和Costa发现，“黑质纹状体”回路中很多神经元能够选择性地对每组被执行的动作发出自我抑制或自我终止的信号。这些回路的基因改动破坏起动/停止的执行，影响小鼠的表现。这一发现为特定神经活动和任务学习之间的因果关系提供了证据。（Letter p. 457; News & Views）


高红移处的氢21厘米整合辐射图（Seeing the dark）
An intensity map of hydrogen 21-cm emission at redshift z ≈ 0.8
为了研究宇宙暗物质（为解释宇宙膨胀速度不断增加而假设存在的力）过去的效应，天文学家需要对极端宇宙距离处的结构有更多了解。21厘米的中性氢射电辐射线被看作是适用于这一目的的一个潜在的有用工具。此前，21厘米辐射只在星系中红移值为z = 0.24的地方被检测到。超过这个点的话，星系就太暗，无法被单独检测，但却有可能测量来自“宇宙网”（cosmic web）中很多未解来源的整合辐射。利用位于美国西弗吉尼亚的名为“Green Bank Telescope”的望远镜，研究人员绘制出了在红移值为0.53到1.12处的氢21厘米辐射的一个三维强度图。将来自DEEP2“光学星系红移巡天”项目所发现的大约1万个星系周围的H I辐射数据添加到该项研究所获得的这个数据集中，可以提供一幅21厘米整合辐射图，其统计显著性为4σ。（Letter p. 463; News & Views）


月球磷灰石与地球相似（Earth-like lunar apatite）
Lunar apatite with terrestrial volatile abundances
人们认为，月球内部相对于地球来说氢、氯和其他挥发性元素较贫乏，原因是在形成月球的碰撞过程中，气体几乎全部跑掉了。对“月球玄武岩14053”（由“阿波罗14号”的宇航员收集的一个被研究得很多的月球岩石样品）所做的新的分析表明，月幔或月壳的部分地方所含挥发性物质可能要比人们以前所认为的更丰富。来自“14053”的磷灰石矿物中氢、氯和硫的浓度与来自地球上普通火成岩中的磷灰石无法区分。对来自其他可以获得的月球岩石类型的磷灰石进行测定，将可帮助澄清这种玄武岩之与地球相似特性的普遍性及重要性。（Letter p. 466）


一种用于合成石墨烯纳米带的精密方法（Ribbon development）
Atomically precise bottom-up fabrication of graphene nanoribbons
石墨烯纳米带（单原子厚度的层状碳所形成的狭窄的直边带状结构）被预测具有引人注目的性能，这使得它们很适合未来电子应用。在这一潜力能够实现之前，还需要在化学上更为精密的合成方法。Cai等人报告了在实现这一目标的方向上所迈出的一步：他们开发出一种从下到上的合成方法，该方法能够生成具有不同拓扑和宽度的、精度达到原子级的石墨烯纳米带。该方法的过程涉及将具有能够编码所期望带状最终产物之拓扑和宽度的结构的前体单体沉积到一个金属表面上。在表面帮助下将前体耦合到线性“聚亚苯基”中，之后再发生环化脱氢作用。鉴于这种方法的多功能性和精确性，它甚至还有可能为合成具有经过微调的化学和电子性能的更不寻常的石墨烯纳米带结构提供一个路径。（Letter p470）


湖泊作为碳汇的重要作用（Lakes as carbon sinks）
Temperature-controlled organic carbon mineralization in lake sediments
内陆水沉积物是重要的、但通常却被放弃的长期碳汇，事实上，湖泊和水库中每年所埋藏的有机碳超过海洋沉积物中的埋藏量。现在，Gudasz等人发现，对处于瑞典亚北极地区的几种不同类型的湖泊来说，湖泊沉积物中的碳矿化随温度升高显著增加。如果假设未来向湖泊沉积物中的有机碳输送与今天的情况相似，那么这个过程可能会成为全球变暖的一个正反馈。（Letter p. 478）


造成信息素种类差异的一个基因（Growing apart）
Allelic variation in a fatty-acyl reductase gene causes divergence in moth sex pheromones
欧洲玉米螟已成为研究性交流的遗传学及性信号在物种形成中所起作用的一个模型体系，部分是因为它由两种性信息素组成，这两种性信息素利用醋酸盐信息素成分的不同比例的顺式异构体和反式异构体，导致强烈生殖隔离——这可能是物种形成的第一步。实践证明，雌性信息素生成及雄性行为反应的基因控制之谜难以揭开，但现在，信息素种类差异中所涉及的一个基因已被识别出来。信息素生物合成所必需的一个脂肪酰还原酶基因发生的变异，可以解释雌性信息素生成中的表现型变异，这种变异导致（信息素）种类特异性信号。这表明，单一一种酶的编码区域中取代的积累会在信息素的混合物种产生差异，这些差异之大足以导致生殖隔离。（Letter p. 486）


“发育弹性”的控制机制（Sharing the load）
Co-option of the hormone-signalling module dafachronic acid–DAF-12 in nematode evolution
一个给定物种中具有相同基因组的植物或动物却能发育成相差迥异的形式，它取决于环境条件，这个现象被称为“发育弹性”，该现象在自然界很普遍，但却很少从基因和分子角度对其进行描述。对线虫Pristionchus pacificus的一种新的捕食性特征（即嘴中额外的牙齿状结构的形成使得它们能够以真菌为食以及在种群密度过大时以其他线虫为食）所做的一项研究表明，它是由控制第四期幼虫（dauer larva）形成的同一内分泌体系调控的。（第四期幼虫状态相当于线虫的休眠期。）源自关键信号作用通道这种性状功能变化（称之为“co-options”或“exaptations”）的“弹性”可能有助于形态新颖性的形成。（Letter p. 494）


DAF-16d/f寿命调控因子（DAF-16d/f longevity factor）
A new DAF-16 isoform regulates longevity
FOXO (single Forkhead Box O) 转录因子已成为细胞功能调控因子的一个主要汇聚点，包括“胰岛素/IGF1信号作用(IIS)通道”。IIS参与各种不同的生物过程，包括寿命的调控。在线虫中，FOXO转录因子DAF-16a在IIS通道中扮演一个主要角色。DAF-16a是两个同形物中的一个，调控线虫的寿命、应激反应和“多尔滞育”(dauer diapause)，但尚不清楚DAF-16在调控这些不同生物过程中是怎样实现其特异性的。现在，一个新的DAF-16同形物，即DAF-16d/f，已被识别出来，它在寿命调控中也很重要。一系列涉及基因表达操纵的实验表明，各种不同DAF-16同形物之间的组合互动的作用是，在整个生物的背景下微调由IIS调控的过程。线虫似乎是利用来自一个基因的多种同形物来微调由IIS调控的过程的，这与哺乳动物中的情况形成对比——在哺乳动物中，四个不同的FOXO基因执行重叠的和截然不同的功能。（Letter p. 498）



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NEWS AND VIEWS
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Obesity: New life for antidiabetic drugs pp443-444
Antidiabetic drugs that activate the protein PPAR[gamma] had a bright start but soon lost their appeal because of undesirable side effects. Subtle modifications may once again make them suitable for treating diabetes.
Riekelt H. Houtkooper and Johan Auwerx
doi:10.1038/466443a
http://www.nature.com/nature/journal/v466/n7305/full/466443a.html

Astrophysics: Broad-brush cosmos pp444-445
An innovative way of mapping the large-scale structure in the Universe sidesteps the need to observe millions of galaxies individually. The approach holds promise for both astrophysical and cosmological studies.
Chris L. Carilli
doi:10.1038/466444a
http://www.nature.com/nature/journal/v466/n7305/full/466444a.html

Climate change: Fatter marmots on the rise pp445-447
Demonstrations of coupled phenotypic and demographic responses to climate change are rare. But they are much needed in formulating predictions of the effects of climate change on natural populations.
Marcel E. Visser
doi:10.1038/466445a
http://www.nature.com/nature/journal/v466/n7305/full/466445a.html

Catalysis: Fluorination made easier pp447-448
By putting the pieces of a chemical puzzle into the right order, a thorny problem in catalysis has been solved. This opens the door to syntheses of molecules that contain the useful trifluoromethyl group.
Tobias Ritter
doi:10.1038/466447a
http://www.nature.com/nature/journal/v466/n7305/full/466447a.html

Conservation science: Hunting the cause of a population crash p448

Tamas Szekely and William J. Sutherland
doi:10.1038/466448a
http://www.nature.com/nature/journal/v466/n7305/full/466448a.html

Neuroscience: Brain's traffic lights p449
The organization of behaviour as sequences of actions requires proper initiation and termination of each action sequence. The neural circuit that signals instructions to start and stop is now revealed.
Paolo Calabresi and Massimiliano Di Filippo
doi:10.1038/466449a
http://www.nature.com/nature/journal/v466/n7305/full/466449a.html

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ARTICLES
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Anti-diabetic drugs inhibit obesity-linked phosphorylation of PPAR[ggr] by Cdk5 pp451-456
PPAR[gamma] ligands are used to control diabetes, but their anti-diabetic actions are puzzling. Here the authors show that phosphorylation of PPAR[gamma] by cyclin-dependent kinase 5 (Cdk5) in mice is linked to obesity induced by high-fat feeding, and that inhibition of the effect in humans by the drug rosiglitazone is closely associated with its anti-diabetic effects. Several anti-diabetic PPAR[gamma] ligands directly inhibit the effect, and thus support a more normal non-diabetic pattern of gene expression.
Jang Hyun Choi et al.
doi:10.1038/nature09291
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09291.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09291.html

Start/stop signals emerge in nigrostriatal circuits during sequence learning pp457-462
The appropriate initiation and termination of behavioural action sequences is imperative, but the neural mechanisms underlying the learning and execution of fixed behavioural patterns are poorly understood. Here the authors reveal start/stop neuronal activity in basal ganglia circuits that emerge during task training in mice. Genetically altering these circuits disrupted the activity and impaired performance, providing evidence for a causal relationship between the specific neuronal activity and task learning.
Xin Jin and Rui M. Costa
doi:10.1038/nature09263
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09263.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09263.html

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LETTERS
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An intensity map of hydrogen 21-cm emission at redshift z[thinsp][ap][thinsp]0.8 pp463-465
Hitherto, 21-cm emission has been detected in galaxies only to redshift 0.24, although it is possible to measure the aggregate emission from many more distant, unresolved sources in the 'cosmic web'. Here the authors report a three-dimensional 21-cm intensity field at redshift 0.53-1.12. They co-add neutral-hydrogen emission from the volumes surrounding about 10,000 galaxies to detect the aggregate 21-cm glow at a significance of approximately four standard deviations.
Tzu-Ching Chang, Ue-Li Pen, Kevin Bandura and Jeffrey B. Peterson
doi:10.1038/nature09187
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09187.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09187.html

Lunar apatite with terrestrial volatile abundances pp466-469
These authors report the concentrations of hydrogen, chlorine and sulphur in the mineral apatite from a lunar basalt, and show that the concentrations are indistinguishable from apatites in common terrestrial igneous rocks. They conclude that both metamorphic and igneous models of apatite formation suggest a volatile inventory for at least some lunar materials that is similar to comparable materials within the Earth.
Jeremy W. Boyce et al.
doi:10.1038/nature09274
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09274.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09274.html

Atomically precise bottom-up fabrication of graphene nanoribbons pp470-473
Graphene nanoribbons (GNRs) have structure-dependent electronic properties that make them attractive for the fabrication of nanoscale electronic devices, but exploiting this potential has been hindered by the lack of precise production methods. Here the authors demonstrate how to reliably produce different GNRs, using precursor monomers that encode the structure of the targeted nanoribbon and are converted into GNRs by means of surface-assisted coupling.
Jinming Cai et al.
doi:10.1038/nature09211
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09211.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09211.html

Binary nanocrystal superlattice membranes self-assembled at the liquid-air interface pp474-477
The spontaneous assembly of two different types of nanoparticle into ordered superlattices offers a route to designing materials with precisely controlled properties, but available synthesis strategies have many practical limitations. These authors report a fabrication process which overcomes these limitations. They generate large-scale (square-millimetre) binary superlattice structures at a liquid-air interface, allowing the material to be free standing or transferred to any substrate ready for fabrication into useful devices.
Angang Dong et al.
doi:10.1038/nature09188
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09188.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09188.html

Temperature-controlled organic carbon mineralization in lake sediments pp478-481
The annual burial of organic carbon in lakes and reservoirs exceeds that of ocean sediments, but inland waters are components of the global carbon cycle that receive only limited attention. Here the authors find that the mineralization of organic carbon in lake sediments exhibits a strong positive relationship with temperature, suggesting that warmer water temperatures lead to more mineralization and less organic carbon burial.
Cristian Gudasz et al.
doi:10.1038/nature09186
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09186.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09186.html

Coupled dynamics of body mass and population growth in response to environmental change pp482-485
Climate change can affect the phenology, population dynamics and morphology of species, but it is difficult to study all these factors and their interactions at once. Using long-term data for individual yellow-bellied marmots, these authors show that climate change has increased the length of the marmot growing season, leading to a gradual increase in individual size. It has simultaneously increased the fitness of large individuals, leading to a rapid increase in population size.
Arpat Ozgul et al.
doi:10.1038/nature09210
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09210.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09210.html

Allelic variation in a fatty-acyl reductase gene causes divergence in moth sex pheromones pp486-489
The European corn borer consists of two sex pheromone races, leading to strong reproductive isolation which could represent a first step in speciation. Female sex pheromone production and male behavioural response are under the control of different genes, but the identity of these genes is unknown. These authors show that allelic variation in a gene essential for pheromone biosynthesis accounts for the phenotypic variation in female pheromone production, leading to race-specific signals.
Jean-Marc Lassance et al.
doi:10.1038/nature09058
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09058.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09058.html

Phenotypic robustness conferred by apparently redundant transcriptional enhancers pp490-493
Transcriptional enhancers are segments of regulatory DNA located some distance from the coding region of a gene, and several of them may sometimes serve apparently redundant functions. These authors demonstrate in Drosophila that such 'redundant' enhancers, by contributing higher overall levels of transcription, ensure robustness of phenotypes against both genetic and environmental perturbations, for example mutations in other genes or temperature changes that would otherwise lead to aberrant development.
Nicolas Frankel et al.
doi:10.1038/nature09158
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09158.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09158.html

Co-option of the hormone-signalling module dafachronic acid-DAF-12 in nematode evolution pp494-497
Plants or animals with identical genomes in a given species can develop into wildly differing forms, depending on environmental conditions, a phenomenon that is widespread in nature yet rarely described in genetic and molecular terms. These authors show that the formation of additional teeth-like structures in the mouth of the nematode Pristionchus pacificus in response to overcrowding is mediated by the same endocrine system that controls dauer larva formation.
Gilberto Bento, Akira Ogawa and Ralf J. Sommer
doi:10.1038/nature09164
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09164.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09164.html

A new DAF-16 isoform regulates longevity pp498-502
The insulin/IGF-1 signalling (IIS) pathway is involved in various biological processes, including regulation of longevity. In the worm Caenorhabditis elegans, the transcription factor DAF-16a, one of two isoforms, has a major role in this pathway, regulating longevity, stress response and dauer diapause. These authors describe a new isoform, DAF-16d/f, which is also important in the regulation of lifespan. The DAF-16 isoforms functionally cooperate to fine-tune IIS-mediated processes in the context of a whole organism.
Eun-Soo Kwon, Sri Devi Narasimhan, Kelvin Yen and Heidi A. Tissenbaum
doi:10.1038/nature09184
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09184.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09184.html

Histone H4K20/H3K9 demethylase PHF8 regulates zebrafish brain and craniofacial development pp503-507
PHF8 is a JmjC domain-containing protein, the gene for which has been linked to X-linked mental retardation (XLMR). These authors demonstrate PHF8 to be a histone demethylase with activity against H4K20me1. It has a role in regulating gene expression as well as in neuronal cell survival and craniofacial development in zebrafish. The results suggest there may be a link between histone methylation dynamics and XLMR.
Hank H. Qi et al.
doi:10.1038/nature09261
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09261.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09261.html

PHF8 mediates histone H4 lysine 20 demethylation events involved in cell cycle progression pp508-512
These authors show that the JmjC domain-containing protein PHF8 has histone demethylase activity against H4K20me1 and is linked to two distinct events during cell cycle progression. PHF8 is recruited to the promoters of genes involved in the G1-S phase transition, where it removes H4K20me1 and contributes to gene activation, whereas dissociation of PHF8 from chromatin in prophase allows H4K20me1 to accumulate during mitosis.
Wen Liu et al.
doi:10.1038/nature09272
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09272.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09272.html

LRRC26 auxiliary protein allows BK channel activation at resting voltage without calcium pp513-516
Here the authors show that in non-excitable LNCaP prostate cancer cells, the large-conductance, voltage- and calcium-activated potassium (BK) channel can be activated at negative voltages without rises in intracellular Ca2+ concentration, by interacting with an auxiliary protein, the leucine-rich repeat containing protein 26. This auxiliary protein modulates BK channel gating by enhancing the allosteric coupling between voltage-sensor activation and the channel's closed-open transition.
Jiusheng Yan and Richard W. Aldrich
doi:10.1038/nature09162
Abstract: http://www.nature.com/nature/journal/v466/n7305/abs/nature09162.html
Article: http://www.nature.com/nature/journal/v466/n7305/full/nature09162.html

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FUTURES
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Little Dutch boy p522
A delicate balancing act.
Jeff Crook
doi:10.1038/466522a
http://www.nature.com/nature/journal/v466/n7305/full/466522a.html

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Advance Online Publication
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18 July 2010
Regulation of myeloid leukaemia by the cell-fate determinant Musashi
Takahiro Ito et al.
doi:10.1038/nature09171
Abstract: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature09171.html
Article: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature09171.html

Cross-species genomics matches driver mutations and cell compartments to model ependymoma
Robert A. Johnson et al.
doi:10.1038/nature09173
Abstract: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature09173.html
Article: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature09173.html

Microbial metalloproteomes are largely uncharacterized
Aleksandar Cvetkovic et al.
doi:10.1038/nature09265
Abstract: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature09265.html
Article: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature09265.html

Role of Tet proteins in 5mC to 5hmC conversion, ES-cell self-renewal and inner cell mass specification
Shinsuke Ito et al.
doi:10.1038/nature09303
Abstract: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature09303.html
Article: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature09303.html

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