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Nature Contents 31 August 2006 (Vol. 442 pp960-1076)
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[自然要览] （选自英国Nature杂志，2006年8月31日出版） 封面故事：“绿色”的误区 Controls on tropical Pacific Ocean productivity revealed through nutrient stress diagnostics 现场铁富集实验的结果使我们关于初级海洋生产力的养分限制的知识发生了革命 性变化，但只是在几十公里的尺度上。现在，利用从卫星海洋彩色测量工作中得 到的浮游植物生物量和生长率数据，可以在全球尺度上对海洋生产力进行监测。 一项新的研究工作将对养分压力的生理响应的认识与范围达数千平方公里的野外 数据结合起来，来确定热带太平洋中限制浮游植物生长的因素，其结果要比以前 所能做到的更准确。该发现表明，浮游植物的“绿色”并不总能准确反映初级生 产力，高表面养分和极低的铁含量使得浮游植物去合成与迅速生长无关的独特的 色素蛋白复合物。因此，以前基于卫星的调查结果可能过高估计了热带太平洋的 生产力。（Letter p.1025） 肥大细胞在组织移植排斥性中的作用（Mast cells and graft rejection） Mast cells are essential intermediaries in regulatory T-cell tolerance 肥大细胞是免疫系统的重要构成部分，是过敏和哮喘等过敏反应中的响应成分。 最近的研究工作表明，它们在先天和后天免疫中还起免疫调控细胞的作用，而且 令人吃惊的是，基因表达分析还表明，它们与对组织移植的耐受性有关系。现 在，用小鼠所做的研究证实，肥大细胞是免疫抑制中的主要细胞类别，在依赖于 调控T-细胞的周围抑制中需要它们。这还意味着白介素-9（IL-9）在被激发的T- 细胞和肥大细胞的补充之间扮演一个联系的角色，并且使得IL-9、肥大细胞和我 们所感兴趣的它们的基因产物成为防止对移植器官产生排斥性的药物的作用目 标。（Article p. 997; N&V） 蛋白质在细胞中的定位（Right place, right time） Karyopherin-mediated import of integral inner nuclear membrane proteins 蛋白质要完成它们在细胞中的任务，它们必须处在细胞中正确的腔室内。这种定 位通常是通过蛋白质中离散的信号序列实现的，这些序列可将它们引导到正确的 位置。这些信号序列中有很多已经被分析透彻，但那些将一种蛋白质引导到内核 膜上的信号序列却是一个引人注目的例外。一项新的研究工作表明，完整内核膜 蛋白质的定位涉及到的信号序列与将可溶性蛋白质定位到细胞核中的信号序列相 似。这个结果是令人吃惊的，它开启了对完整的一组内核膜蛋白质进行研究的大 门，这些蛋白质在基因调控中扮演一个角色，并且与各种不同的人类疾病有联 系。（Article p.1003; N&V） 关于GRB/XRF 060218的一组研究结果（Bursting with energy） The association of GRB 060218 with a supernova and the evolution of the shock wave 长伽马射线暴（GRB）与超新星之间的一个联系已经被确定，但在较弱与较软的 X-射线和超新星之间是否存在一个类似的关系却不清楚。GRB/XRF 060218是由 Swift卫星在今年2月份发现的，它可能为天文学家提供二者之间缺失的线索。在 关于这一新颖天体的四篇论文的第一篇中，Campana等人报告，他们发现了一次 爆发的X-射线特征，这可能是一颗超新星正在形成的证据。Pian等人报告了对与 GRB/XRF 060218相关的一种Ic型超新星2006aj的光学观测结果。Soderberg等人 报告了无线电和X-射线观测结果，其结果表明，XRF 060218的能量比宇宙GRB小 100倍，但其所属类型比宇宙GRB要常见10倍。Mazzali等人对SN 2006aj的光谱和 光学曲线进行了模拟，发现它与其他GRB-超新星相比爆炸能量要小得多，喷发的 物质也要少得多，说明它是由一颗质量只有太阳20倍的恒星产生的，之后留下的 是一颗中子星，而不是一个黑洞。（Letters pp. 1008, 1011, 1014, 1018; N&V） 检测NMR的新方法（Making NMR of light） Optical detection of liquid-state NMR 核磁共振（NMR）被用于很多场合，从NMR成像到蛋白结构研究等等。这些应用涉 及对由与原子核相关的微型磁体所产生的磁场的测量。NMR信号通常较弱，需要 利用复杂的手段将关于所测样品的有用信息梳理出来。现在，普林斯顿大学的研 究人员发现，只要让一束光穿过所测样品、再测量光偏振的转动，就可以检测到 NMR。这种新的检测方法将使得研究人员有可能用拍快照的方式来捕捉核磁，研 究一个复杂化学物质中的哪些原子与其颜色和其他光学性质有关。（Letter p.1021; N&V） 海洋中山脊下面地质构造的成像研究（A good spread） Discovery of a magma chamber and faults beneath a Mid-Atlantic Ridge hydrothermal field 来自最近对Lucky Strike火山所做的地震反射调查的数据，以及由法国船只RV l’Atalante对大西洋中热液喷孔场所做的考察研究，为我们首次提供了一个缓 慢展开的山脊下面的一个轴向岩浆室的清晰的地震波图像。从该图像上可以看 出，断层向下穿透，到达这个岩浆室，这种构造以前从未获得过图像。这些发现 为了解与在缓慢展开的山脊上的地壳形成相关的火山过程和构造过程之间的相互 作用提供了线索。Lucky Strike火山位于Mid-Atlantic山脊的Lucky Strike段的 中心，目前正在以每年大约22毫米的速度展开。（Letter p.1029） 脊椎动物中鳍的发育（Fin tuning） Evidence that mechanisms of fin development evolved in the midline of early vertebrates 脊椎动物成对出现的四肢的起源，一直是人们感兴趣的话题。最近对从中国早寒 武纪地层中发现的若干化石所做的研究表明，鳍骨架的主要部分首先是在中线上 组装的，后来才出现在成对的鳍中。对鲨鱼和七鳃鳗的胚胎发育所做的一项研究 表明，鲨鱼的中鳍是从一个连续的鳍褶发育来的，这个鳍褶主要来自中胚层；七 鳃鳗（没有成对四肢的原始脊椎动物）有一个类似的中鳍发育模式。另外，基因 Tbx18（该基因确定成对四肢前面的极限）的表达也能确定中鳍往外长的边界。 将这些结果综合在一起，我们可以看到，它们为认为成对附肢通过调控中鳍发育 程序来演化的古生物学假说提供了支持。（Letter p.1033） 上皮细胞层的几何形状 The emergence of geometric order in proliferating metazoan epithelia 在所有多细胞真核生物中，上皮细胞层类似不规则的多边形，以六边形的细胞为 主。这种基本模式到底是怎么形成的？对此，研究人员仍然不是很清楚，尽管人 们通常假设，细胞按照最佳堆积的物理学原理排列成蜂窝状。研究人员将对正在 增殖的上皮细胞进行延时显微研究的方法与克隆分析和数学模拟的方法结合起 来，来驳斥这一假设。后生动物默认的多边形结构并不是随机的，也不是最小堆 积的产物，而是细胞分裂过程的一个直接的数学结果。细胞分裂内在地将上皮层 限制成一种特定的平衡分布状态，该状态由四边形至九边形的细胞组成。这种结 构见于包括果蝇、刺胞动物（Hydra）和青蛙（Xenopus）在内的各种不同的生物 的简单上皮中。（Letter p.1038） 多巴胺在人体中的精确作用（Dopamine by choice） Dopamine-dependent prediction errors underpin reward-seeking behaviour in humans 大脑信使物质多巴胺传统上被称为“快乐分子”，它与我们对食物和性的欲望有 关，也与药物和赌博上瘾有关。多巴胺在人体中的精确功能仍然不很清楚，相关 理论几乎完全依靠动物实验。Pessiglione等人在一项研究工作中，让健康的人 类志愿者在服用干扰多巴胺信号的药物后赌钱，然后利用脑成像技术对他们进行 扫描。服用提高多巴胺水平的药物的志愿者与服用抑制多巴胺水平的药物的志愿 者相比，赌博的水平更高了。当多巴胺水平被药物增强、或被药物降低时，扫描 结果显示，与奖励有关的学习和相关的纹状体活动都受到了调控，从而证实了多 巴胺在整合奖励信息、供未来决策参考中所起的关键作用。（Letter p.1042） 植物能够“记住”所受挫折（leafy legacy） Transgeneration memory of stress in plants 对植物来说，即使不舒服，它们也不能跑掉，比如说光线太强或太弱、温度太高 或太低时。相反，它们通过各种不同的生理反应来应对压力，从而表现出不同程 度的耐受性。令人吃惊的是，当拟南芥植物面对压力（如紫外线或可模仿某种病 原体进攻的一种化学物质）时，我们不仅能在经过处理的植物中检测到所发生的 变化，而且还能在它们没有经过处理的几代后代中检测到所发生的变化。植物能 “记住”压力，它们可能利用的是一种我们尚不知道的独立于DNA的外成机制。 这一发现让我们想到了关于获得性状的染色体遗传的拉马克思想（该思想已经被 认为不足为信），但也仅仅是想到而已。（Letter p.1046） 图片故事：活唾液腺组织中多线性染色体的三维、实时观测（Have you seen the movie?） Dynamics of heat shock factor association with native gene loci in living cells 果蝇幼虫的唾液腺含有巨型多线性染色体，其典型的带状结构在光学显微镜下清 晰可见。这些染色体通常是通过将细胞核打破、然后将染色体在二维方向上展开 来观察的。但是现在，利用双质子激光扫描显微镜，就可以在活唾液腺组织中对 它们进行三维、实时观测研究了。上图为多线核的一个三维重建图，其中DNA被 染成红色，用GFP标记的转录因子HSF为绿色（上面为heat stroke 之前；下面为 heat stroke之后）。该方法显示了DNA和一个典型转录因子之间相互作用的动 态，正如该论文“补充信息”中一部生动影片所反映的那样。（Letter p.1050） 细菌鞭毛马达的首个完整结构（cracking the whip） In situ structure of the complete Treponema primitia flagellar motor 一种细菌鞭毛马达的首个完整结构，让我们看到了这种精粹的大分子纳米机器的 运动姿势。该结构是通过对完好的Treponema primitia细胞进行电子冷断层扫描 的办法获得的，它显示，在鞭毛的定子部分有16-倍的对称性，与转子（C-环） 之间有多个连接，并且还有一个新颖的P-环一样的结构。（Letter p.1062） |
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木虫 (正式写手)
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---------------------- NEWS AND VIEWS ---------------------- Immunology: Protection and privilege The immune system not only attacks microbes, but also regulates itself to avoid harming vital organs. Cells notorious for their involvement in allergy turn out to be vital to this protective function. Herman Waldmann 10.1038/nature05165 http://www.nature.com/nature/jou ... ll/nature05165.html Cosmology: Unique, or not unique? That is the question. The search for a single theory of everything is as old as science itself, and is now the beat of quantum cosmologists. But some basic tenets that inform the quest are being challenged. Martin Bojowald 10.1038/442988a http://www.nature.com/nature/journal/v442/n7106/full/442988a.html 50 & 100 Years ago 10.1038/442989a http://www.nature.com/nature/journal/v442/n7106/full/442989a.html Spectroscopy: Shifting light with spin NMR spectroscopy has changed enormously over the years, but signal detection has stayed the same since the technique was invented. The latest thinking literally shines a new light on things. Warren S. Warren 10.1038/442990a http://www.nature.com/nature/journal/v442/n7106/full/442990a.html Cell biology: Taking a turn into the nucleus How soluble proteins get into the cell nucleus is known in great detail, but how membrane proteins make it into the inner nuclear membrane has long been an enigma. The two processes in fact turn out to be related. Ulrike Kutay and Petra Muhlhausser 10.1038/nature05173 http://www.nature.com/nature/jou ... ll/nature05173.html Astrophysics: Shock breakout caught on camera What exactly is the relationship between bursts of cosmic γ-rays and the stellar explosions known as supernovae? Intimate, it seems: highly magnetic neutron stars might even have spawned both. Timothy R. Young 10.1038/442992a http://www.nature.com/nature/journal/v442/n7106/full/442992a.html Nanoscience: Small talk Is rebranding research as 'nanoscience' just jumping on the bandwagon? A recent conference in Basel proves that the name does at least attract researchers from different disciplines to mingle for mutual inspiration. Liesbeth Venema 10.1038/442994a http://www.nature.com/nature/journal/v442/n7106/full/442994a.html Parasitology: Peculiar lipid production Joshua M. Finkelstein 10.1038/442995a http://www.nature.com/nature/journal/v442/n7106/full/442995a.html Obituary: Setsuro Ebashi (1922-2006) Physiologist who uncovered the regulatory role of calcium in cells. Makoto Endo 10.1038/442996a http://www.nature.com/nature/journal/v442/n7106/full/442996a.html ---------------------- ARTICLES ---------------------- Mast cells are essential intermediaries in regulatory T-cell tolerance Li-Fan Lu et al. 10.1038/nature05010 Abstract: http://www.nature.com/nature/jou ... bs/nature05010.html Article: http://www.nature.com/nature/jou ... ll/nature05010.html Karyopherin-mediated import of integral inner nuclear membrane proteins Sequences responsible for targeting integral membrane proteins to the inner nuclear membrane (INM) resemble classical nuclear localization signals. Recognition of these signals by the import receptor karyopherin-alpha promotes nuclear import; targeting of INM proteins is dependent on the Ran GTPase system and specific nuclear pore complex proteins. Megan C. King, C. Patrick Lusk and Gunter Blobel 10.1038/nature05075 Abstract: http://www.nature.com/nature/jou ... bs/nature05075.html Article: http://www.nature.com/nature/jou ... ll/nature05075.html ---------------------- LETTERS ---------------------- The association of GRB 060218 with a supernova and the evolution of the shock wave Observations of the close gamma-ray burst GRB 060218 and its connection to supernova SN 2006aj reveal the break-out of a shock wave driven by a mildly relativistic shell into the dense wind surrounding the GRB progenitor. These observation catch a supernova in the act of exploding. S. Campana et al. 10.1038/nature04892 Abstract: http://www.nature.com/nature/jou ... bs/nature04892.html Article: http://www.nature.com/nature/jou ... ll/nature04892.html An optical supernova associated with the X-ray flash XRF 060218 A report of the optical discovery and follow-up observations of the type Ic supernova SN 2006aj associated with X-ray flash XRF 060218. SN 2006aj was intrinsically less luminous than the gamma-ray burst (GRB)-supernovae connection, but more luminous than many supernovae not accompanied by a GRB. E. Pian et al. 10.1038/nature05082 Abstract: http://www.nature.com/nature/jou ... bs/nature05082.html Article: http://www.nature.com/nature/jou ... ll/nature05082.html Relativistic ejecta from X-ray flash XRF 060218 and the rate of cosmic explosions Radio and X-ray observations of X-ray flash XRF 060218, which is associated with supernova SN 2006aj, show that this event is 100 times less energetic but ten times more common than cosmological gamma-ray bursts (GRBs). The production of relativistic ejecta seems to be the key physical distinction between GRBs/XRFs and ordinary supernovae. A. M. Soderberg et al. 10.1038/nature05087 Abstract: http://www.nature.com/nature/jou ... bs/nature05087.html Article: http://www.nature.com/nature/jou ... ll/nature05087.html A neutron-star-driven X-ray flash associated with supernova SN 2006aj Modelling the spectra and light curve of supernova SN 2006aj shows that it had a much smaller explosion energy and ejected much less mass than other gamma-ray burst-supernovae, suggesting that it was produced by a star whose initial mass was only ～20 solar masses, and which left behind a neutron star, rather than a black hole. Paolo A. Mazzali et al. 10.1038/nature05081 Abstract: http://www.nature.com/nature/jou ... bs/nature05081.html Article: http://www.nature.com/nature/jou ... ll/nature05081.html Optical detection of liquid-state NMR I. M. Savukov, S.-K. Lee and M. V. Romalis 10.1038/nature05088 Abstract: http://www.nature.com/nature/jou ... bs/nature05088.html Article: http://www.nature.com/nature/jou ... ll/nature05088.html Controls on tropical Pacific Ocean productivity revealed through nutrient stress diagnostics The nutrients that limit phytoplankton growth also influence fluorescence. The nature of these relationships in the tropical Pacific are now established, allowing fluorescence measurements to determine the factors that limit phytoplankton growth in this region more accurately, and on a larger spatial scale, than has been possible previously. Michael J. Behrenfeld et al. 10.1038/nature05083 Abstract: http://www.nature.com/nature/jou ... bs/nature05083.html Article: http://www.nature.com/nature/jou ... ll/nature05083.html Discovery of a magma chamber and faults beneath a Mid-Atlantic Ridge hydrothermal field Satish C. Singh et al. 10.1038/nature05105 Abstract: http://www.nature.com/nature/jou ... bs/nature05105.html Article: http://www.nature.com/nature/jou ... ll/nature05105.html Evidence that mechanisms of fin development evolved in the midline of early vertebrates The median fins of sharks develop from a continuous finfold derived mainly from paraxial mesoderm. Expression of Tbx18, which specifies the anterior limit of the paired forelimbs, also delineates the boundaries of median fin outgrowth. Lampreys, primitive vertebrates that lack paired limbs, have a median fin that shares a similar pattern of development with sharks. Renata Freitas, GuangJun Zhang and Martin J. Cohn 10.1038/nature04984 Abstract: http://www.nature.com/nature/jou ... bs/nature04984.html Article: http://www.nature.com/nature/jou ... ll/nature04984.html The emergence of geometric order in proliferating metazoan epithelia Matthew C. Gibson, Ankit B. Patel, Radhika Nagpal and Norbert Perrimon 10.1038/nature05014 Abstract: http://www.nature.com/nature/jou ... bs/nature05014.html Article: http://www.nature.com/nature/jou ... ll/nature05014.html Dopamine-dependent prediction errors underpin reward-seeking behaviour in humans An fMRI study of healthy human volunteers finds that when dopamine levels are either enhanced or reduced by drugs, both reward-related learning and associated striatal activity are modulated, confirming the critical role of dopamine in integrating reward information for future decisions. Mathias Pessiglione et al. 10.1038/nature05051 Abstract: http://www.nature.com/nature/jou ... bs/nature05051.html Article: http://www.nature.com/nature/jou ... ll/nature05051.html Transgeneration memory of stress in plants Plants exposed to environmental stresses such as ultraviolet light exhibit increased recombination between homologous chromosomes. Here, the progeny of plants that were exposed to an environmental stress also exhibited increased levels of genetic recombination, even though the progeny were not actually exposed to the stress. Jean Molinier, Gerhard Ries, Cyril Zipfel and Barbara Hohn 10.1038/nature05022 Abstract: http://www.nature.com/nature/jou ... bs/nature05022.html Article: http://www.nature.com/nature/jou ... ll/nature05022.html Dynamics of heat shock factor association with native gene loci in living cells Jie Yao, Katherine M. Munson, Watt W. Webb and John T. Lis 10.1038/nature05025 Abstract: http://www.nature.com/nature/jou ... bs/nature05025.html Article: http://www.nature.com/nature/jou ... ll/nature05025.html Proteolytic turnover of the Gal4 transcription factor is not required for function in vivo Kip Nalley, Stephen Albert Johnston and Thomas Kodadek 10.1038/nature05067 Abstract: http://www.nature.com/nature/jou ... bs/nature05067.html Article: http://www.nature.com/nature/jou ... ll/nature05067.html Nutrient regulates Tor1 nuclear localization and association with rDNA promoter Yeast Tor1 is dynamically distributed in the cytoplasm and nucleus, and its association with the rDNA promoter is important for 35S rRNA synthesis and cell growth. Hong Li et al. 10.1038/nature05020 Abstract: http://www.nature.com/nature/jou ... bs/nature05020.html Article: http://www.nature.com/nature/jou ... ll/nature05020.html In situ structure of the complete Treponema primitia flagellar motor The structure (at ～7-nm resolution) of a complete flagellar motor obtained in situ by electron cryotomography of intact Treponema primitia cells is presented. The stator's 16-fold symmetry and its multiple connections to the rotor, C ring and a novel P-ring-like structure are described. Gavin E. Murphy, Jared R. Leadbetter and Grant J. Jensen 10.1038/nature05015 Abstract: http://www.nature.com/nature/jou ... bs/nature05015.html Article: http://www.nature.com/nature/jou ... ll/nature05015.html |
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