封面故事:胶带纸竟能成为 X-射线源 Correlation between nanosecond X-ray flashes and stick–slip friction in peeling tape 摩擦发光是一种光学现象,当两个接触的表面之间有相对运动时有时可以看到。在日常 生活中,将两块糖放在一起摩擦时可能会发光;将很多种胶带纸从一个表面上撕下时也 可能会发光。加州大学洛杉矶分校的物理学家在试图对胶带纸摩擦发光现象进行定性的 研究中获得了意想不到的结果。他们发现,在真空中剥离胶带纸所释放的能量会进入X- 射线的范畴,而且其强度大到足以能被用作X-射线照相。本期封面照片所示为一个人手 指的X-射线图像,是通过将剥离胶带纸(试验中用的是市场上可以买到的“Scotch”牌 胶带纸)的操作作为X-射线源拍摄的。X-射线图像是叠加到实验背景的图像上的。这里 的能量集中过程向理论工作者提出了一个有趣的挑战,因为这里所涉及的能量极限及闪 光宽度超过了当前理论的预测。(Letter p. 1089)
与成胶质细胞瘤有关的新基因(Glioblastoma: advances in genomics and a lab model) Comprehensive genomic characterization defines human glioblastoma genes and core pathways / p53 and Pten control neural and glioma stem/progenitor cell renewal and differentiation 《癌症基因组图集》(Cancer Genome Atlas)是一个旨在为与癌症相关的突变编目的 大型基因组学项目,该项目目前已经开始产生结果。成胶质细胞瘤(最常见的脑癌)是 该项目的第一个目标,其最初的结果9月4日首先在网上发布,现在出现在了印刷版的 Nature上。新发现的与成胶质细胞瘤有关的基因包括一些肿瘤抑制因子(NF1、RB1、 ATM和 APC)和几个酪氨酸激酶基因。(Article p. 1061)成胶质细胞瘤极为难以治 疗,因此开发一个可能的模型系统具有潜在重要性。Zheng等人报告,缺少肿瘤抑制因 子p53 和 PTEN的小鼠会患与人类成胶质细胞瘤相似的肿瘤,同时Myc蛋白水平提高。除 了为验证相关疗法提供一个潜在系统外,这一发现也说明c-Myc是一个可能的药物作用 目标。(Letter p. 1129)
与肺癌相关的基因突变(Mutations involved in lung cancer) Somatic mutations affect key pathways in lung adenocarcinoma 在另一项大规模基因组研究中,研究人员在188个原发肿瘤样品中对与肺癌(癌症致死 的最常见原因)相关的突变进行了分析。他们对超过600个与肺腺癌 (adenocarcinoma)有已知或潜在联系的基因进行了测序,其中26个基因以高频率发生 突变,表明它们在致癌过程中发挥直接作用。(Article p. 1069)
星系结构实际上比理论预测简单(Galactic structure: a simple answer) Galaxies appear simpler than expected 猛一看,星系看起来非常复杂:每个星系都含有数十亿恒星,它们受很多因素影响, 包括引力、旋转和辐射。星系形成的层级理论(目前很流行)认为,它们是通过冷暗物 质的很多次合并从较小的碎片形成的,某一个具体星系的性质由六个独立参数决定。现 在,对200个不同星系所做的一项调查表明,事情实际上要比理论上所说的简单,星系 结构只由一个参数控制。不过,到底是那个参数尚不清楚。星系的这种组织水平是与层 级星系形成理论及冷暗物质宇宙学预测结果相矛盾的。(Letter p. 1082; News & Views)
量子系统中信息的忠实传输(Moving memories) Solid-state quantum memory using the 31P nuclear spin 信息在两个进行处理和记忆工作的实体之间的传递对于量子计算非常关键,也非常成问 题。在经典系统中,信息传输可包括一个复制步骤(在这个步骤中错误可被发现和纠 正),但在量子系统中,复制从根本上来讲是被排除在外的。Morton等人介绍了一个技 术,该技术有可能解决这个问题:信息在电子-自旋处理元素和基于一个核自旋的记忆 元素之间的相干存储和读出。这个系统利用的是一个硅-28晶体中的磷-31自旋供体。核 自旋起一个记忆元素的作用,它可将电子的完整状态忠实存储超过一秒时间,然后以大 约90%的效率将其传送回电子自旋。(Letter p. 1085)
一种铂“oxo络合物”的合成(Catalytic oxidation: a platinum standard) Evidence for a terminal Pt(iv)-oxo complex exhibiting diverse reactivity 很多重要生物和化学过程,包括光催化水氧化成分子氧的过程(人们对其感兴趣是因为 它是人工光合作用的一个途径)和金属表面上双氧的激发,被认为涉及“过渡金属末端 oxo络合物”。Poverenov等人现在报告了基于有潜在有用特点的氧化剂的一种铂(络合 物)的合成。它是一种d6 Pt(IV) “末端oxo络合物”,该络合物不是由一个接受电子 的配体框架稳定的,因而既表现出作为一种分子间和分子内氧供体的活性,又表现出一 种亲电子分子的活性。它还能够进行水活反应,产生一种“末端dihydroxo络合物”, 这个结果对于了解水氧化反应和其他催化反应的机制也许有参考价值。(Letter p. 1093; News & Views)
地球上出现光合作用的最早时间被修正(The advent of photosynthesis: postponing the event) Reassessing the first appearance of eukaryotes and cyanobacteria 关于地球上能够生成氧气的光合作用,被人们广泛接受的最古老的证据来自从澳大利亚 Pilbara Craton距今27亿年前的页岩中提取出的烃类生物标记,它们被认为是真核生物 及光合作用蓝藻的证据。这么早的时间引起了一些争议,因为在能够产生氧的蓝藻在地 球上最早出现的这个时间与大约3亿年后引起大气中氧含量增加的“大氧化事件” (great oxidation event)有一个很长的时间延迟。由Rasmussen等人所做的新的研究 工作表明,有机生物标记不是太古代的,一定是在晚些时候、在距今大约22亿年前之后 进入岩石的。因此,真核生物及蓝藻出现在地球上的最早的、明确无误的化石证据分别 应该被纠正为在距今17.8亿–16.8亿年前和21.5亿年前。(Letter p. 1101; News & Views)
中国新发现恐龙化石改写恐龙-鸟类演化历史(Theropod evolution: a trick of the tail) A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers 这里是从非鸟类四足动物向鸟类过渡中的另一个篇章——一种奇特的、鸽子大小的长羽 毛的恐龙从中国的中-晚侏罗纪地层中被发现。这种生物生活的年代比始祖鸟稍早一 些,它在很多方面都像鸟,包括长有四个非常长的、丝带一样的尾羽和一个短尾。但没 有在像小盗龙那样的鸟样恐龙四肢上所看到的那种飞行羽毛的痕迹。在今天的鸟类中, 加长的尾羽通常都是起装饰作用的,这种古生物的尾羽也可能是起这种作用。这一新发 现的化石,使得从恐龙向鸟类演化的早期历史变得更复杂了。(Letter p. 1105)
有益细菌也许可用于治疗1-型糖尿病(Microbes to counter diabetes) Innate immunity and intestinal microbiota in the development of Type 1 diabetes NOD(非肥胖型糖尿病)小鼠(1-型糖尿病的一种实验模型)自免疫糖尿病的发病率随 它们饲养条件的不同而不同。尤其是,暴露于被杀死的分支杆菌和其他细菌产物的NOD 小鼠,会受到保护而不患糖尿病,说明这个过程涉及快速先天免疫反应。现在,用有先 天免疫缺陷(由Toll-样受体信号适配蛋白MyD88的缺失造成)的NOD小鼠所做实验表 明,先天免疫和肠道菌落都影响糖尿病的易患性。缺少MyD88的无菌小鼠会患严重糖尿 病,而对补充与正常人肠道细菌相似的肠道细菌的小鼠,糖尿病则会减轻。这个发现提 出一个可能性:活的、有益的细菌或细菌产物也许可用于治疗1-型糖尿病。(Letter p. 1109)
细菌感染胎儿同时需要两个入侵蛋白(Crossing the barrier) Conjugated action of two species-specific invasion proteins for fetoplacental listeriosis 李氏杆菌病和孕期的其他细菌感染会影响胎儿及母亲,但对于病原体是怎样穿过胎盘障 碍的人们却知之甚少。Disson等人利用被Listeria monocytogenes感染的两个互补动物 模型对这一过程进行了研究。他们发现,病原体向胎盘的转移同时需要两个毒性因子或 入侵蛋白,即InlA 和 InlB。所以阻断这两个通道中的一个或将其全部阻断,有可能阻 止细菌进入胎儿体内。反过来说,人们也许有可能利用这两个通道来输送穿过同一障碍 的治疗用分子。(Letter p. 1114)
一种能促进拟南芥双精细胞生成的新蛋白(Flower power) Control of plant germline proliferation by SCFFBL17 degradation of cell cycle inhibitors 双受精(Double fertilization)是一种在生物学上具有独特意义的生殖系统,被认为 是开花植物演化中的一个关键创新。与动物受精不同的是,双受精涉及一对精细胞通过 不同子细胞的选择性分裂的生成。现在,一种新的F-box蛋白,名为FBL17,被发现在拟 南芥中能促进双精细胞的生成。在雄性生殖细胞中,FBL17以KRP7为目标,后者是依赖 于细胞周期蛋白的激酶的一个抑制因子。开花植物所用的这一细胞周期调控机制在酵母 和动物细胞之间是在演化上保留下来的,这项新的研究工作说明了调控机制是怎样演化 来适应特殊环境的。(Letter p. 1134)
---------------------- NEWS AND VIEWS ---------------------- Biochemistry: Cells enforce an ion curtain pp1043-1044 Metal cofactors are an essential part of many proteins. But how is the right choice of metal made? For bacteria, one answer is to change the cellular compartment where cofactor insertion occurs. Ben C. Berks doi:10.1038/4551043a http://www.nature.com/nature/journal/v455/n7216/full/4551043a.html
Economics: Sustainable fisheries pp1044-1045 Fishermen's aims of increasing their catch seem at odds with preserving fish stocks by limiting catch. A study of more than 11,000 fisheries shows that 'individual tradable quotas' can reconcile these goals. Geoffrey Heal and Wolfram Schlenker doi:10.1038/4551044a http://www.nature.com/nature/journal/v455/n7216/full/4551044a.html
Inorganic chemistry: Confirmation of the improbable pp1045-1047 Certain transition-metal complexes are thought to exist only fleetingly, perhaps as intermediates in reactions. So the discovery of one such complex that is stable at room temperature is provocative. Craig L. Hill doi:10.1038/4551045a http://www.nature.com/nature/journal/v455/n7216/full/4551045a.html
Apoptosis: Stabbed in the BAX pp1047-1049 Apoptotic cell death is an intricate and highly regulated process. To initiate apoptosis, the protein BIM binds to a hitherto unrecognized site on the BAX protein to trigger permeabilization of the outer mitochondrial membrane. Douglas R. Green and Jerry E. Chipuk doi:10.1038/4551047a http://www.nature.com/nature/journal/v455/n7216/full/4551047a.html
Astrophysics: How do galaxies form? pp1049-1051 A study of galaxies indicates that galaxy formation may be regulated by a single parameter. This unexpected finding shows that prevailing views on the process could need revision. Sidney van den Bergh doi:10.1038/4551049a http://www.nature.com/nature/journal/v455/n7216/full/4551049a.html
Biogeochemistry: Life before the rise of oxygen pp1051-1052 The discovery of molecular fossils in 2.7-billion-year-old rocks prompted a re-evaluation of microbial evolution, and of the advent of photosynthesis and rise of atmospheric oxygen. That discovery now comes into question. Woodward W. Fischer doi:10.1038/4551051a http://www.nature.com/nature/journal/v455/n7216/full/4551051a.html
---------------------- NEWS AND VIEWS Q&A ---------------------- Systems biology: Metabonomics pp1054-1056 Organisms often respond in complex and unpredictable ways to stimuli that cause disease or injury. By measuring and mathematically modelling changes in the levels of products of metabolism found in biological fluids and tissues, metabonomics offers fresh insight into the effects of diet, drugs and disease. Jeremy K. Nicholson and John C. Lindon doi:10.1038/4551054a http://www.nature.com/nature/journal/v455/n7216/full/4551054a.html
---------------------- FEATURE ---------------------- The mental wealth of nations pp1057-1060 Countries must learn how to capitalize on their citizens' cognitive resources if they are to prosper, both economically and socially. Early interventions will be key. John Beddington et al. doi:10.1038/4551057a http://www.nature.com/nature/journal/v455/n7216/full/4551057a.html
---------------------- Advance Online Publication ---------------------- Comprehensive genomic characterization defines human glioblastoma genes and core pathways pp1061-1068 With a comprehensive analysis of sequencing data, DNA copy number, gene expression and DNA methylation in a large number of human glioblastomas, The Cancer Genome Atlas project initiative provides a broad overview of the genes and pathways that are altered in this cancer type.
BAX activation is initiated at a novel interaction site pp1076-1081 A structural analysis of the apoptosis-inducing protein BAX in complex with a peptide derived from its activator BIM reveals an unforeseen interaction site that does not involve the classic hydrophobic groove reported for inhibitors of apoptosis. This identification of BAX's activation site provides mechanistic insights into a cell's demise. Evripidis Gavathiotis et al. doi:10.1038/nature07396 Abstract: http://www.nature.com/nature/journal/v455/n7216/abs/nature07396.html?lang=en Article: http://www.nature.com/nature/journal/v455/n7216/full/nature07396.html
Galaxies appear simpler than expected pp1082-1084 This paper reports that a sample of galaxies (first detected from neutral hydrogen emission) shows five independent correlations amongst six independent observables. This implies that the structure of such galaxies must be controlled by a single parameter, which cannot yet be identified. Such a degree of organization is at odds with hierarchical galaxy formation. M. J. Disney et al. doi:10.1038/nature07366 Abstract: http://www.nature.com/nature/journal/v455/n7216/abs/nature07366.html?lang=en Article: http://www.nature.com/nature/journal/v455/n7216/full/nature07366.html
Solid-state quantum memory using the 31P nuclear spin pp1085-1088 The transfer of information between processing entities and memory is crucial for quantum computation; it is challenging because the process must remain coherent at all times to preserve the quantum nature of the information. This paper demonstrates coherent storage and readout of information between electron-spin processing elements and memory elements based on a nuclear spin. John J. L. Morton et al. doi:10.1038/nature07295 Abstract: http://www.nature.com/nature/journal/v455/n7216/abs/nature07295.html?lang=en Article: http://www.nature.com/nature/journal/v455/n7216/full/nature07295.html
Correlation between nanosecond X-ray flashes and stick-slip friction in peeling tape pp1089-1092 Relative motion between two contacting surfaces can produce visible light, a process known as triboluminescence. Scientists now fully characterize the energy emissions from peeling sticky tape in a vacuum and show the generation of X-rays with sufficient intensity that they were used for X-ray imaging. Carlos G. Camara, Juan V. Escobar, Jonathan R. Hird and Seth J. Putterman doi:10.1038/nature07378 Abstract: http://www.nature.com/nature/journal/v455/n7216/abs/nature07378.html?lang=en Article: http://www.nature.com/nature/journal/v455/n7216/full/nature07378.html
Evidence for a terminal Pt(iv)-oxo complex exhibiting diverse reactivity pp1093-1096 Terminal oxo complexes of transition metals are important in biological and chemical processes, for example, the catalytic oxidation of organic molecules and the activation of dioxygen on metal surfaces are thought to involve oxo complexes. This paper explored the reactivity of a d6 Pt(IV) complex, a dn (n > 5) terminal oxo complex that is not stabilized by an electron withdrawing ligand framework. The complex exhibits reactivity as an inter- and intra-molecular oxygen donor and as an electrophile. Elena Poverenov et al. doi:10.1038/nature07356 Abstract: http://www.nature.com/nature/journal/v455/n7216/abs/nature07356.html?lang=en Article: http://www.nature.com/nature/journal/v455/n7216/full/nature07356.html
Fault-induced seismic anisotropy by hydration in subducting oceanic plates pp1097-1100 It is shown that the amount and geometry of seismic anisotropy measured in the forearc regions of subduction zones strongly depend on the preferred orientation of hydrated faults in the subducting oceanic plate. The anisotropy originates from the crystallographic preferred orientation of highly anisotropic hydrous minerals formed along steeply dipping faults and from the larger-scale vertical layering consisting of dry and hydrated crust-mantle sections, the spacing of which is several times smaller than teleseismic wavelengths. Manuele Faccenda, Luigi Burlini, Taras V. Gerya and David Mainprice doi:10.1038/nature07376 Abstract: http://www.nature.com/nature/journal/v455/n7216/abs/nature07376.html?lang=en Article: http://www.nature.com/nature/journal/v455/n7216/full/nature07376.html
Reassessing the first appearance of eukaryotes and cyanobacteria pp1101-1104 The oldest widely accepted evidence for oxygenic photosynthesis comes from hydrocarbon biomarkers extracted from 2.7-billion-year-old shales in the Pilbara Craton, Australia, thought to be evidence of eukaryotes and photosynthetic cyanobacteria. But evidence now shows that the organic biomarkers were not indigenous to the rocks containing them, and must have entered the rocks after [sim]2.2 Gyr ago. The earliest unambiguous fossil evidence for eukaryotes and cyanobacteria thus reverts to 1.78-1.68 and 2.15 Gyr, respectively. Birger Rasmussen, Ian R. Fletcher, Jochen J. Brocks and Matt R. Kilburn doi:10.1038/nature07381 Abstract: http://www.nature.com/nature/journal/v455/n7216/abs/nature07381.html?lang=en Article: http://www.nature.com/nature/journal/v455/n7216/full/nature07381.html
A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers pp1105-1108 This paper presents another chapter in the earliest history of birds, with the discovery of a feathered dinosaur from the Mid to Late Jurassic of China. Living a little earlier than the famous fossil bird Archaeopteryx,
Innate immunity and intestinal microbiota in the development of Type 1 diabetes pp1109-1113 The effect of deficiency of MyD88 on the generation of type 1 diabetes (T1D) has been investigated through the generation of congenic strains in the non-obese diabetic (NOD) mouse model. It is found that in specific pathogen-free conditions, MyD88-deficiency attenuates T1D, indicating that the interaction of intestinal microbes with the innate immune system is a critical factor in modifying susceptibility to type 1 diabetes. Li Wen et al. doi:10.1038/nature07336 Abstract: http://www.nature.com/nature/journal/v455/n7216/abs/nature07336.html?lang=en Article: http://www.nature.com/nature/journal/v455/n7216/full/nature07336.html
p53 and Pten control neural and glioma stem/progenitor cell renewal and differentiation pp1129-1133 In a mouse model, it is found that the loss of the tumour suppressors p53 and Pten leads to the development of tumours resembling human primary glioblastomas, and both p53 and PTEN are frequently lost in the human cancer. Loss of these tumour suppressors impairs the differentiation of neural stem cells, due to upregulation of Myc by the concerted action of p53 and PTEN loss. Hongwu Zheng et al. doi:10.1038/nature07443 Abstract: http://www.nature.com/nature/journal/v455/n7216/abs/nature07443.html?lang=en Article: http://www.nature.com/nature/journal/v455/n7216/full/nature07443.html
Control of plant germline proliferation by SCFFBL17 degradation of cell cycle inhibitors pp1134-1137 A newly discovered F-box protein of Arabidopsis thaliana that promotes twin sperm cell production is identified. The protein, FBL17, targets KRP7, an Arabidopsis inhibitor of CDKA1, for proteasome-dependent degradation, allowing germ cell division and twin sperm cell production. Hyo Jung Kim et al. doi:10.1038/nature07289 Abstract: http://www.nature.com/nature/journal/v455/n7216/abs/nature07289.html?lang=en Article: http://www.nature.com/nature/journal/v455/n7216/full/nature07289.html
Protein-folding location can regulate manganese-binding versus copper- or zinc-binding pp1138-1142 This study identifies the most abundant Cu2+- and Mn2+-containing proteins in the periplasm of a cyanobacterium and determines that the cellular compartment in which each of those proteins fold is responsible for the insertion of the correct metal ion into the metalloprotein. Steve Tottey et al. doi:10.1038/nature07340 Abstract: http://www.nature.com/nature/journal/v455/n7216/abs/nature07340.html?lang=en Article: http://www.nature.com/nature/journal/v455/n7216/full/nature07340.html