《Nature》目录要览（2009年7月30日出版）
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《Nature》目录要览（2009年7月30日出版）
封面故事： 生物对海洋混合的贡献
A viscosity-enhanced mechanism for biogenic ocean mixing
物理学家查尔斯*达尔文爵士是进化论创始人查尔斯*达尔文的孙子，他的一项被人遗忘
的贡献解决了关于海洋混合的一个长期争论。他在1953年提出，游泳的动物也许对海洋
中水的混合有相当大贡献。今天，关于海洋中由生物造成的海水混合的争论集中在对动
物尾流扰动与海洋扰动的对比上。“达尔文式”混合是不同的，它是当在一种流体中运
动的一个固态物体使其周围的一部分流体运动起来、并沿该物体传播时发生的。Kakani
Katija 和 John Dabiri利用对在一个偏僻海岛湖泊中游动的水母所做的现场测定、并
结合一个新的理论模型发现，活生物通过这一机制对海洋混合的贡献是相当大的，与风
和潮的贡献在同一数量级。（Letter p. 624; News & Views）本期封面所示为对诱导
产生的流体漂流所做的染色测定，引起这种漂流的是帕劳群岛水母湖中的一种名叫“硝
水母”的水母。照片提供：Kakani Katija。
沉默调节蛋白生物学研究方面的最新进展（That sirtuin something）
Recent progress in the biology and physiology of sirtuins
用酵母所做研究发现，要通过限制热量来延长寿命必需有Sir2。这是一种蛋白质，最初
是在一项筛选基因沉默因子的工作中被分离出来的，其全称为“沉默信息调节因子
-2”，“Sir”是“沉默信息调节因子”三个英文单词的首字母缩写。自从这一发现以
来，人们对被通称为“沉默调节蛋白”(sirtuins)的一组蛋白一直饶有兴趣。在本期
Nature上，Toren Finkel, Chu-Xia Deng 和Raul Mostoslavsky对沉默调节蛋白生物学
研究方面的最新进展做了综述。这些NAD依赖型酶被发现与一系列有关细胞命运的决
定、与维持基因组稳定性和调控总体能量代谢有关。越来越多的证据还表明，沉默调节
蛋白与包括从糖尿病到癌症在内的若干疾病状态的病情发展有关。这些发现，再加上最
近在小分子沉默调节蛋白活化因子合理化设计方面所取得的进展，使我们看到这样一个
可能性：我们有可能找到针对许多与年龄相关的疾病的新疗法以及延缓哺乳动物衰老的
潜在药理策略。（Review p. 587）
P2X4 和ASIC1的结构被确定（P2X4 and ASIC1 at the gate）
Crystal structure of the ATP-gated P2X4 ion channel in the closed state /
Pore architecture and ion sites in acid-sensing ion channels and P2X
receptors
P2X受体是ATP门控的非选择性阳离子通道，与伤害性感受和炎症反应有关，过去人们并
不知道其结构。现在，Kawate等人介绍了斑马鱼P2X4受体在一种关闭状态下的晶体结
构。这种三聚结构揭示了配体结合、阳离子进入和通道门控的一些分子基础。另一篇相
关的论文介绍了鸡的酸感应离子通道-1（ASIC1）在一种脱敏状态下的结构。同P2X受体
一样，ASICs也是三聚体，但它们属于一个完全不同的离子通道家族。ASIC1的结构显示
了离子渗透和脱敏的可能机制，而ASIC 和 P2X结构的对比则表明，这些具有截然不同
功能的通道所采用的机制却相似。（Articles pp. 592, 599; News & Views）
关于矮球状星系形成的一个新理论（Galaxies stripped for action）
Resonant stripping as the origin of dwarf spheroidal galaxies
关于矮球状星系形成的一个新理论表明，矮球状星系可能是由矮盘状星系与较大矮星系
的遭遇形成的。矮球状星系是附近宇宙中由暗物质支配的低亮度星系，它们的起源是关
于星系形成方式的长期未解之谜之一。以前的模型仅适用于靠近一个像银河系和仙女座
这样的巨型星系运行的矮球状星系，这些模型因在“本星系群”外围矮星的存在而未被
当成普适理论。在新的模型模拟中，小星系群中矮星系之间的遭遇引发了一个被称为
“resonant stripping”的过程，该过程在它们被像银河系这样的体系吸积之前将其转
变成了矮球状星系。 在这一框架内，矮球状星系应能够成对地或以小群组的方式形成
和互动，留下可以探测得到的长长的星流和星尾。（Letter p. 605）
关于土星转动周期的一个新数值（Saturn’s rotation）
Saturn's rotation period from its atmospheric planetary-wave configuration
土星的整体转动周期预计在过去几十年间并没有发生我们可以觉察到的变化，所以能够
反映其转动周期的一个好的参数也应当保持得相当稳定。从“卡西尼”探测器获得的最
新结果，对测量土星内部转动（即测量磁层中某些特征的转动周期）的传统方法提出了
疑问，因为它们测出的周期比“旅行者”探测器28年前测出的10小时39分24秒的数值长
大约7分钟。Read等人在本期Nature上报告了关于土星转动周期的一个新数值，即10小
时34分13秒±20秒，该结果是通过分析潜在的大气涡度（atmospheric vorticity）得
出的。这一改变了的参照系与存在一个交替式喷射模式的假设是一致的，说明土星上的
风要比以前所认为的更像木星上的风。（Letter p. 608; News & Views）
一个能够预测颗粒堆积特点的统计模型（Going with the grain）
A 'granocentric' model for random packing of jammed emulsions
颗粒随机堆积的性质是物理学和数学上的一个基础性的古老问题，它有很多不同的实际
用途，如从多孔岩石中采油、粮食储存、以及从粉末来制造药片等。迄今为止，对于与
晶体排序相似的颗粒，尚没有一个已知的简单机制。来自纽约大学软物质研究中心的一
个小组，对多分散乳滴的堆积进行了测定，发现整体堆积结构的复杂性可以用“颗粒中
心论”观点来理解。一个根据两个简单局部参数（一个颗粒周围可获得的空间及其与相
邻颗粒的接触比）建立起来的统计模型，成功预测出了堆积的局部和整体特点，包括它
们的连接性和密度。（Letter p. 611）
全球变暖大大加快泥炭地中的碳排放（Carbon released from peat）
Carbon respiration from subsurface peat accelerated by climate warming in
the subarctic
由全球变暖所诱导的、通过增强世纪到千年时间的泥炭沉积物的呼吸作用而发生的二氧
化碳排放速度的加快，可能会对我们的气候形成一个强有力的正反馈。但碳在泥炭地、
尤其是在泥炭地深处的长期温度敏感度仍然不确定。现在，一项涉及对亚北极泥炭地人
工变暖的长期（8年以上）实验表明，变暖大约1°C，会刺激生态系统呼吸速度加快50%
以上，这种加快的大部分来自永久冻土之上接近活性层底部的长期存在的顽固性碳。这
些发现表明，气候变暖对泥炭地中地下碳库呼吸作用的加快程度要比以前人们所认为的
大得多，有可能将《京都议定书》对整个欧盟所确定的温室气体减排目标的大部分抵消
掉。（Letter p. 616）
早衰蛋白控制神经传输物质的释放（Presenilins control neurotransmitter
release）
Presenilins are essential for regulating neurotransmitter release
早衰蛋白基因在遗传上已被与家族性阿尔茨海默氏症联系起来，但它们在什么地方发挥
作用、它们在神经元中做什么却不清楚。Zhang等人通过小鼠模型发现，早衰蛋白在突
触前腔中发挥作用，控制依赖于活性的神经传输物质的释放，这是一个对于神经计算、
学习和记忆来说必不可少的过程。这些发现表明，突触前功能丧失也许是神经退化性疾
病中导致痴呆的一个早期原因。（Letter p. 632）
具有抗菌活性的巨噬细胞（Antibacterial macrophages）
Macrophage elastase kills bacteria within murine macrophages
我们对很多基质金属蛋白酶（MMPs）（一个广泛的锌依赖型肽链内切酶家族）的正常生
理作用仍然很不了解。现在，基质金属蛋白酶-12（MMP-12，亦称为巨噬细胞弹性蛋白
酶）被发现具有针对革兰氏阳性和革兰氏阴性细菌的直接抗菌活性。MMP-12的这种功能
与该分子的羧基端区域、而不是其催化点有关。而且令人吃惊的是，MMP-12在细胞内也
具有抗菌活性，因为其MMPs主要是在细胞外空间中具有活性。这项工作还表明，巨噬细
胞在急性细菌感染最早阶段扮演一个角色，人们更为熟悉的是，这些阶段被认为是嗜中
性细胞发挥作用的范畴。（Letter p. 637）
X-染色体失活过程的触发（X chromosome inactivation）
Evidence of Xist RNA-independent initiation of mouse imprinted X-chromosome
inactivation
雌性哺乳动物携带两个版本的X-染色体，而雄性则携带一个X-染色和一个Y-染色体，为
了抵消双剂量同一基因可能产生的毒性，X-染色体上的大多数基因都被沉默。这一X-染
色体失活（XCI）过程，长期以来被假设是由RNA基因Xist的表达、具体来说是由该基因
在失活X-染色体上的版本的表达触发的。现在，用小鼠胚胎（研究人员用基因工程方法
使这些小鼠在其未来失活的X-染色体上含有一个有缺陷的Xist基因）所做的新的研究工
作显示，实际情况更为复杂。事实上，在留下印迹的XCI过程中，父系X-染色体的沉默
可在没有父系Xist的情况下被启动。如果仍旧没有Xist，X-染色体最终会再活化，说明
它的作用也许是使沉默长期保持稳定。（Letter p. 647）
----------------------
NEWS AND VIEWS
----------------------
Optics: All smoke and metamaterials pp579-580
An illusion device, placed near but not enclosing an object of arbitrary
shape, manipulates and transforms light scattered off the object so as to
give it the appearance of a completely different object.
John Pendry
doi:10.1038/460579a
http://www.nature.com/nature/journal/v460/n7255/full/460579a.html
Structural biology: Trimeric ion-channel design pp580-581
Cavernous chambers, intricate passages, a gate with a curious lock the
structure of an ATP-activated ion channel reveals its architecture. And
this intriguing interior design is found in another type of ion channel too.
Shai D. Silberberg and Kenton J. Swartz
doi:10.1038/460580a
http://www.nature.com/nature/journal/v460/n7255/full/460580a.html
Oceanography: A fishy mix pp581-582
Ocean life is in almost constant motion, and such activity must surely
stir things up. Innovative investigations into this concept of 'biogenic
mixing' show a role for jellyfish and their brethren.
William K. Dewar
doi:10.1038/460581a
http://www.nature.com/nature/journal/v460/n7255/full/460581a.html
Planetary science: Windy clues to Saturn's spin pp582-583
Saturn's rotation period has been a mystery. An estimate based on its
meteorology comes with implications for our understanding of the planet's
atmospheric jet streams and interior structure.
Adam P. Showman
doi:10.1038/460582a
http://www.nature.com/nature/journal/v460/n7255/full/460582a.html
Earth science: Trickle-down geodynamics pp583-584
Analysis of the platinum-group elements in a particular type of ancient
volcanic rock provides clues about Earth's early history as well as a
fresh approach to understanding mantle dynamics.
Nicholas Arndt
doi:10.1038/460583a
http://www.nature.com/nature/journal/v460/n7255/full/460583a.html
Developmental biology: Skeletal muscle comes of age pp584-585
A regulatory protein thought to be crucial for maintaining the muscle
stem-cell pool throughout life is shown to be dispensable in the adult.
Muscle biologists are left wondering what fundamental things apply as
time goes by.
Terry Partridge
doi:10.1038/460584a
http://www.nature.com/nature/journal/v460/n7255/full/460584a.html
Supramolecular chemistry: Phosphorus caged pp585-586
Violent criminals are imprisoned to keep them under control. Similarly,
incarceration in a molecular jail stops white phosphorus from bursting
into flames [mdash] but on release, it regains its fiery character.
Kenneth N. Raymond
doi:10.1038/460585a
http://www.nature.com/nature/journal/v460/n7255/full/460585a.html
----------------------
REVIEW
----------------------
Recent progress in the biology and physiology of sirtuins pp587-591
Toren Finkel, Chu-Xia Deng and Raul Mostoslavsky
doi:10.1038/nature08197
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08197.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08197.html
----------------------
ARTICLES
----------------------
Crystal structure of the ATP-gated P2X4 ion channel in the closed
state pp592-598
P2X receptors are ATP-gated cation channels that are implicated in diverse
physiological processes, from synaptic transmission to inflammation to the
sensing of taste and pain. The crystal structure of the zebrafish P2X4
channel is now solved in its closed state, revealing some of the molecular
underpinnings of ligand-binding, cation entry and channel gating.
Toshimitsu Kawate, Jennifer Carlisle Michel, William T. Birdsong and Eric
Gouaux
doi:10.1038/nature08198
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08198.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08198.html
Pore architecture and ion sites in acid-sensing ion channels and P2X
receptors pp599-604
Like P2X receptors, acid-sensing ion channels are trimeric in structure;
however, they belong to an entirely different family. Here, the structure
of an acid-sensing ion channel is presented and compared to the structure
of P2X4, suggesting that these functionally distinct channels use similar
mechanistic principles.
Eric B. Gonzales, Toshimitsu Kawate and Eric Gouaux
doi:10.1038/nature08218
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08218.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08218.html
----------------------
LETTERS
----------------------
Resonant stripping as the origin of dwarf spheroidal galaxies pp605-607
The origin of dwarf spheroidal galaxies is one of the outstanding puzzles
of how galaxies form. Previous theories require that they orbit near giant
galaxies like the Milky Way, but some dwarfs have been observed in the
outskirts of the Local Group. Here, simulations of encounters between dwarf
disk galaxies and somewhat larger dwarfs yield results that may account for
some of the observed properties of dwarf spheroidals in the Local Group.
Elena D'Onghia, Gurtina Besla, Thomas J. Cox and Lars Hernquist
doi:10.1038/nature08215
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08215.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08215.html
Saturn/'s rotation period from its atmospheric planetary-wave configuration
pp608-610
The rotation period of a gas giant's magnetic field (the System III
reference frame) is commonly used to infer its bulk rotation, but this
approach cannot be used for Saturn because its dipole magnetic field is not
tilted relative to its rotation axis. Consequently, the surrogate measure
of long-wavelength radiation is used to fix the System III rotation period.
The period as recently measured by the Cassini spacecraft is up to 7 minutes
longer than the value measured 28 years ago by Voyager. Here, a
determination
of Saturn's rotation period is reported, based on an analysis of potential
vorticity.
P. L. Read, T. E. Dowling and G. Schubert
doi:10.1038/nature08194
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08194.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08194.html
A /`granocentric/' model for random packing of jammed emulsions pp611-615
A simple underlying mechanism for the random assembly of granular particles,
analogous to crystalline ordering, remains unknown. Here however,
three-dimensional measurements of packings of polydisperse emulsion droplets
are used to build a statistical model where the complexity of the global
packing can be understood in terms of two simple, local parameters the
available space around a particle and the ratio of contacts to neighbours.
Maxime Clusel, Eric I. Corwin, Alexander O. N. Siemens and Jasna Brujic
doi:10.1038/nature08158
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08158.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08158.html
Carbon respiration from subsurface peat accelerated by climate warming in
the subarctic pp616-619
The feedback between the terrestrial carbon cycle and climate is one of the
largest uncertainties in current projections of future climate, with the
long-term sensitivity of carbon in peatlands remaining unclear. The
combination of non-disturbing in situ measurements of carbon dioxide
respiration rates and isotopic composition of respired CO2 in subarctic
peatland experiments now shows that warming accelerates respiration rates
of these subsurface carbon reservoirs to a much larger extent than was
previously thought.
Ellen Dorrepaal et al.
doi:10.1038/nature08216
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08216.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08216.html
Progressive mixing of meteoritic veneer into the early Earth/'s deep mantle
pp620-623
Komatiites are ancient volcanic rocks, mostly from the Archaean era, that
formed through high degrees of partial melting of the mantle and therefore
provide reliable information on bulk mantle compositions. Here it is shown
that most early Archaean komatiites from the Barberton greenstone belt of
South Africa and the Pilbara craton of Western Australia are depleted in
platinum group elements (PGEs) relative to late Archaean and younger
komatiites, and the variations of this depletion with time suggests that
PGE-enriched cosmic material was progressively mixed into the deep mantle.
Wolfgang D. Maier et al.
doi:10.1038/nature08205
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08205.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08205.html
A viscosity-enhanced mechanism for biogenic ocean mixing pp624-626
Sir Charles Darwin, grandson of the famous evolutionary pioneer, was a
physicist who suggested that swimming animals might contribute significantly
to the mixing of water in the ocean. Here, observations of swimming
jellyfish are used to create and validate a theoretical model for the
relative contributions of Darwinian mixing and turbulent wake mixing.
The contribution of living organisms to ocean mixing is found to be
substantial [mdash] in the same order of magnitude as winds and tides.
Kakani Katija and John O. Dabiri
doi:10.1038/nature08207
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08207.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08207.html
Adult satellite cells and embryonic muscle progenitors have distinct
genetic requirements pp627-631
The myogenic determinant Pax7 is thought to have a critical role in adult
muscle stem cells (satellite cells), but a formal demonstration has been
lacking in vivo. Here it is shown that, unexpectedly, when Pax7 is
inactivated
in adult mice, mutant satellite cells are not compromised in muscle
regeneration. Multiple time points of gene inactivation reveal that Pax7
is only required up to the juvenile period, indicating an age-dependent
change in the genetic requirement for muscle stem cells.
Christoph Lepper, Simon J. Conway and Chen-Ming Fan
doi:10.1038/nature08209
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08209.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08209.html
Presenilins are essential for regulating neurotransmitter
release pp632-636
Mutations in the presenilin genes are associated with familial cases of
Alzheimer's disease, but the precise site and nature of the synaptic
dysfunction remain unknown. Using a genetic approach to selectively
inactivate presenilins in a mouse model, it has been possible to demonstrate
that they act in the presynaptic compartment to control the
activity-dependent efficacy of neurotransmitter release, a process essential
for neuronal computation, learning and memory.
Chen Zhang et al.
doi:10.1038/nature08177
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08177.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08177.html
Macrophage elastase kills bacteria within murine macrophages pp637-641
Macrophages possess several substances with which they can kill bacteria,
including reactive oxygen species, nitric oxide, and antimicrobial proteins.
Here, macrophage elastase, an enzyme implicated in several disease processes
including emphysema, is shown to have direct antimicrobial activity against
Gram-positive and Gram-negative bacteria.
A. McGarry Houghton et al.
doi:10.1038/nature08181
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08181.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08181.html
MicroRNA-mediated switching of chromatin-remodelling complexes in neural
development pp642-646
During development of the vertebrate nervous system, a switch in the subunit
composition of the BAF chromatin-remodelling complex occurs when cells lose
multipotency and begin to develop stable connections that will persist for
a lifetime. Here, the switch in BAF subunits is shown to be mediated by two
microRNAs that are selectively expressed in post-mitotic neurons.
Andrew S. Yoo, Brett T. Staahl, Lei Chen and Gerald R. Crabtree
doi:10.1038/nature08139
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08139.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08139.html
Evidence of Xist RNA-independent initiation of mouse imprinted X-chromosome
inactivation pp647-651
Female mammals undergo silencing of most genes on one of their two X
chromosomes in a process termed X-chromosome inactivation (XCI). In
placental mammals, the non-coding RNA Xist is thought to trigger XCI.
Here it is demonstrated that silencing of the paternal X chromosome (Xp)
is able to initiate in the absence of paternal Xist; Xist is, however,
required to stabilize silencing along the Xp.
Sundeep Kalantry et al.
doi:10.1038/nature08161
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08161.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08161.html
A viscosity-enhanced mechanism for biogenic ocean mixing
物理学家查尔斯*达尔文爵士是进化论创始人查尔斯*达尔文的孙子，他的一项被人遗忘
的贡献解决了关于海洋混合的一个长期争论。他在1953年提出，游泳的动物也许对海洋
中水的混合有相当大贡献。今天，关于海洋中由生物造成的海水混合的争论集中在对动
物尾流扰动与海洋扰动的对比上。“达尔文式”混合是不同的，它是当在一种流体中运
动的一个固态物体使其周围的一部分流体运动起来、并沿该物体传播时发生的。Kakani
Katija 和 John Dabiri利用对在一个偏僻海岛湖泊中游动的水母所做的现场测定、并
结合一个新的理论模型发现，活生物通过这一机制对海洋混合的贡献是相当大的，与风
和潮的贡献在同一数量级。（Letter p. 624; News & Views）本期封面所示为对诱导
产生的流体漂流所做的染色测定，引起这种漂流的是帕劳群岛水母湖中的一种名叫“硝
水母”的水母。照片提供：Kakani Katija。
沉默调节蛋白生物学研究方面的最新进展（That sirtuin something）
Recent progress in the biology and physiology of sirtuins
用酵母所做研究发现，要通过限制热量来延长寿命必需有Sir2。这是一种蛋白质，最初
是在一项筛选基因沉默因子的工作中被分离出来的，其全称为“沉默信息调节因子
-2”，“Sir”是“沉默信息调节因子”三个英文单词的首字母缩写。自从这一发现以
来，人们对被通称为“沉默调节蛋白”(sirtuins)的一组蛋白一直饶有兴趣。在本期
Nature上，Toren Finkel, Chu-Xia Deng 和Raul Mostoslavsky对沉默调节蛋白生物学
研究方面的最新进展做了综述。这些NAD依赖型酶被发现与一系列有关细胞命运的决
定、与维持基因组稳定性和调控总体能量代谢有关。越来越多的证据还表明，沉默调节
蛋白与包括从糖尿病到癌症在内的若干疾病状态的病情发展有关。这些发现，再加上最
近在小分子沉默调节蛋白活化因子合理化设计方面所取得的进展，使我们看到这样一个
可能性：我们有可能找到针对许多与年龄相关的疾病的新疗法以及延缓哺乳动物衰老的
潜在药理策略。（Review p. 587）
P2X4 和ASIC1的结构被确定（P2X4 and ASIC1 at the gate）
Crystal structure of the ATP-gated P2X4 ion channel in the closed state /
Pore architecture and ion sites in acid-sensing ion channels and P2X
receptors
P2X受体是ATP门控的非选择性阳离子通道，与伤害性感受和炎症反应有关，过去人们并
不知道其结构。现在，Kawate等人介绍了斑马鱼P2X4受体在一种关闭状态下的晶体结
构。这种三聚结构揭示了配体结合、阳离子进入和通道门控的一些分子基础。另一篇相
关的论文介绍了鸡的酸感应离子通道-1（ASIC1）在一种脱敏状态下的结构。同P2X受体
一样，ASICs也是三聚体，但它们属于一个完全不同的离子通道家族。ASIC1的结构显示
了离子渗透和脱敏的可能机制，而ASIC 和 P2X结构的对比则表明，这些具有截然不同
功能的通道所采用的机制却相似。（Articles pp. 592, 599; News & Views）
关于矮球状星系形成的一个新理论（Galaxies stripped for action）
Resonant stripping as the origin of dwarf spheroidal galaxies
关于矮球状星系形成的一个新理论表明，矮球状星系可能是由矮盘状星系与较大矮星系
的遭遇形成的。矮球状星系是附近宇宙中由暗物质支配的低亮度星系，它们的起源是关
于星系形成方式的长期未解之谜之一。以前的模型仅适用于靠近一个像银河系和仙女座
这样的巨型星系运行的矮球状星系，这些模型因在“本星系群”外围矮星的存在而未被
当成普适理论。在新的模型模拟中，小星系群中矮星系之间的遭遇引发了一个被称为
“resonant stripping”的过程，该过程在它们被像银河系这样的体系吸积之前将其转
变成了矮球状星系。 在这一框架内，矮球状星系应能够成对地或以小群组的方式形成
和互动，留下可以探测得到的长长的星流和星尾。（Letter p. 605）
关于土星转动周期的一个新数值（Saturn’s rotation）
Saturn's rotation period from its atmospheric planetary-wave configuration
土星的整体转动周期预计在过去几十年间并没有发生我们可以觉察到的变化，所以能够
反映其转动周期的一个好的参数也应当保持得相当稳定。从“卡西尼”探测器获得的最
新结果，对测量土星内部转动（即测量磁层中某些特征的转动周期）的传统方法提出了
疑问，因为它们测出的周期比“旅行者”探测器28年前测出的10小时39分24秒的数值长
大约7分钟。Read等人在本期Nature上报告了关于土星转动周期的一个新数值，即10小
时34分13秒±20秒，该结果是通过分析潜在的大气涡度（atmospheric vorticity）得
出的。这一改变了的参照系与存在一个交替式喷射模式的假设是一致的，说明土星上的
风要比以前所认为的更像木星上的风。（Letter p. 608; News & Views）
一个能够预测颗粒堆积特点的统计模型（Going with the grain）
A 'granocentric' model for random packing of jammed emulsions
颗粒随机堆积的性质是物理学和数学上的一个基础性的古老问题，它有很多不同的实际
用途，如从多孔岩石中采油、粮食储存、以及从粉末来制造药片等。迄今为止，对于与
晶体排序相似的颗粒，尚没有一个已知的简单机制。来自纽约大学软物质研究中心的一
个小组，对多分散乳滴的堆积进行了测定，发现整体堆积结构的复杂性可以用“颗粒中
心论”观点来理解。一个根据两个简单局部参数（一个颗粒周围可获得的空间及其与相
邻颗粒的接触比）建立起来的统计模型，成功预测出了堆积的局部和整体特点，包括它
们的连接性和密度。（Letter p. 611）
全球变暖大大加快泥炭地中的碳排放（Carbon released from peat）
Carbon respiration from subsurface peat accelerated by climate warming in
the subarctic
由全球变暖所诱导的、通过增强世纪到千年时间的泥炭沉积物的呼吸作用而发生的二氧
化碳排放速度的加快，可能会对我们的气候形成一个强有力的正反馈。但碳在泥炭地、
尤其是在泥炭地深处的长期温度敏感度仍然不确定。现在，一项涉及对亚北极泥炭地人
工变暖的长期（8年以上）实验表明，变暖大约1°C，会刺激生态系统呼吸速度加快50%
以上，这种加快的大部分来自永久冻土之上接近活性层底部的长期存在的顽固性碳。这
些发现表明，气候变暖对泥炭地中地下碳库呼吸作用的加快程度要比以前人们所认为的
大得多，有可能将《京都议定书》对整个欧盟所确定的温室气体减排目标的大部分抵消
掉。（Letter p. 616）
早衰蛋白控制神经传输物质的释放（Presenilins control neurotransmitter
release）
Presenilins are essential for regulating neurotransmitter release
早衰蛋白基因在遗传上已被与家族性阿尔茨海默氏症联系起来，但它们在什么地方发挥
作用、它们在神经元中做什么却不清楚。Zhang等人通过小鼠模型发现，早衰蛋白在突
触前腔中发挥作用，控制依赖于活性的神经传输物质的释放，这是一个对于神经计算、
学习和记忆来说必不可少的过程。这些发现表明，突触前功能丧失也许是神经退化性疾
病中导致痴呆的一个早期原因。（Letter p. 632）
具有抗菌活性的巨噬细胞（Antibacterial macrophages）
Macrophage elastase kills bacteria within murine macrophages
我们对很多基质金属蛋白酶（MMPs）（一个广泛的锌依赖型肽链内切酶家族）的正常生
理作用仍然很不了解。现在，基质金属蛋白酶-12（MMP-12，亦称为巨噬细胞弹性蛋白
酶）被发现具有针对革兰氏阳性和革兰氏阴性细菌的直接抗菌活性。MMP-12的这种功能
与该分子的羧基端区域、而不是其催化点有关。而且令人吃惊的是，MMP-12在细胞内也
具有抗菌活性，因为其MMPs主要是在细胞外空间中具有活性。这项工作还表明，巨噬细
胞在急性细菌感染最早阶段扮演一个角色，人们更为熟悉的是，这些阶段被认为是嗜中
性细胞发挥作用的范畴。（Letter p. 637）
X-染色体失活过程的触发（X chromosome inactivation）
Evidence of Xist RNA-independent initiation of mouse imprinted X-chromosome
inactivation
雌性哺乳动物携带两个版本的X-染色体，而雄性则携带一个X-染色和一个Y-染色体，为
了抵消双剂量同一基因可能产生的毒性，X-染色体上的大多数基因都被沉默。这一X-染
色体失活（XCI）过程，长期以来被假设是由RNA基因Xist的表达、具体来说是由该基因
在失活X-染色体上的版本的表达触发的。现在，用小鼠胚胎（研究人员用基因工程方法
使这些小鼠在其未来失活的X-染色体上含有一个有缺陷的Xist基因）所做的新的研究工
作显示，实际情况更为复杂。事实上，在留下印迹的XCI过程中，父系X-染色体的沉默
可在没有父系Xist的情况下被启动。如果仍旧没有Xist，X-染色体最终会再活化，说明
它的作用也许是使沉默长期保持稳定。（Letter p. 647）
----------------------
NEWS AND VIEWS
----------------------
Optics: All smoke and metamaterials pp579-580
An illusion device, placed near but not enclosing an object of arbitrary
shape, manipulates and transforms light scattered off the object so as to
give it the appearance of a completely different object.
John Pendry
doi:10.1038/460579a
http://www.nature.com/nature/journal/v460/n7255/full/460579a.html
Structural biology: Trimeric ion-channel design pp580-581
Cavernous chambers, intricate passages, a gate with a curious lock the
structure of an ATP-activated ion channel reveals its architecture. And
this intriguing interior design is found in another type of ion channel too.
Shai D. Silberberg and Kenton J. Swartz
doi:10.1038/460580a
http://www.nature.com/nature/journal/v460/n7255/full/460580a.html
Oceanography: A fishy mix pp581-582
Ocean life is in almost constant motion, and such activity must surely
stir things up. Innovative investigations into this concept of 'biogenic
mixing' show a role for jellyfish and their brethren.
William K. Dewar
doi:10.1038/460581a
http://www.nature.com/nature/journal/v460/n7255/full/460581a.html
Planetary science: Windy clues to Saturn's spin pp582-583
Saturn's rotation period has been a mystery. An estimate based on its
meteorology comes with implications for our understanding of the planet's
atmospheric jet streams and interior structure.
Adam P. Showman
doi:10.1038/460582a
http://www.nature.com/nature/journal/v460/n7255/full/460582a.html
Earth science: Trickle-down geodynamics pp583-584
Analysis of the platinum-group elements in a particular type of ancient
volcanic rock provides clues about Earth's early history as well as a
fresh approach to understanding mantle dynamics.
Nicholas Arndt
doi:10.1038/460583a
http://www.nature.com/nature/journal/v460/n7255/full/460583a.html
Developmental biology: Skeletal muscle comes of age pp584-585
A regulatory protein thought to be crucial for maintaining the muscle
stem-cell pool throughout life is shown to be dispensable in the adult.
Muscle biologists are left wondering what fundamental things apply as
time goes by.
Terry Partridge
doi:10.1038/460584a
http://www.nature.com/nature/journal/v460/n7255/full/460584a.html
Supramolecular chemistry: Phosphorus caged pp585-586
Violent criminals are imprisoned to keep them under control. Similarly,
incarceration in a molecular jail stops white phosphorus from bursting
into flames [mdash] but on release, it regains its fiery character.
Kenneth N. Raymond
doi:10.1038/460585a
http://www.nature.com/nature/journal/v460/n7255/full/460585a.html
----------------------
REVIEW
----------------------
Recent progress in the biology and physiology of sirtuins pp587-591
Toren Finkel, Chu-Xia Deng and Raul Mostoslavsky
doi:10.1038/nature08197
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08197.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08197.html
----------------------
ARTICLES
----------------------
Crystal structure of the ATP-gated P2X4 ion channel in the closed
state pp592-598
P2X receptors are ATP-gated cation channels that are implicated in diverse
physiological processes, from synaptic transmission to inflammation to the
sensing of taste and pain. The crystal structure of the zebrafish P2X4
channel is now solved in its closed state, revealing some of the molecular
underpinnings of ligand-binding, cation entry and channel gating.
Toshimitsu Kawate, Jennifer Carlisle Michel, William T. Birdsong and Eric
Gouaux
doi:10.1038/nature08198
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08198.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08198.html
Pore architecture and ion sites in acid-sensing ion channels and P2X
receptors pp599-604
Like P2X receptors, acid-sensing ion channels are trimeric in structure;
however, they belong to an entirely different family. Here, the structure
of an acid-sensing ion channel is presented and compared to the structure
of P2X4, suggesting that these functionally distinct channels use similar
mechanistic principles.
Eric B. Gonzales, Toshimitsu Kawate and Eric Gouaux
doi:10.1038/nature08218
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08218.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08218.html
----------------------
LETTERS
----------------------
Resonant stripping as the origin of dwarf spheroidal galaxies pp605-607
The origin of dwarf spheroidal galaxies is one of the outstanding puzzles
of how galaxies form. Previous theories require that they orbit near giant
galaxies like the Milky Way, but some dwarfs have been observed in the
outskirts of the Local Group. Here, simulations of encounters between dwarf
disk galaxies and somewhat larger dwarfs yield results that may account for
some of the observed properties of dwarf spheroidals in the Local Group.
Elena D'Onghia, Gurtina Besla, Thomas J. Cox and Lars Hernquist
doi:10.1038/nature08215
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08215.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08215.html
Saturn/'s rotation period from its atmospheric planetary-wave configuration
pp608-610
The rotation period of a gas giant's magnetic field (the System III
reference frame) is commonly used to infer its bulk rotation, but this
approach cannot be used for Saturn because its dipole magnetic field is not
tilted relative to its rotation axis. Consequently, the surrogate measure
of long-wavelength radiation is used to fix the System III rotation period.
The period as recently measured by the Cassini spacecraft is up to 7 minutes
longer than the value measured 28 years ago by Voyager. Here, a
determination
of Saturn's rotation period is reported, based on an analysis of potential
vorticity.
P. L. Read, T. E. Dowling and G. Schubert
doi:10.1038/nature08194
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08194.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08194.html
A /`granocentric/' model for random packing of jammed emulsions pp611-615
A simple underlying mechanism for the random assembly of granular particles,
analogous to crystalline ordering, remains unknown. Here however,
three-dimensional measurements of packings of polydisperse emulsion droplets
are used to build a statistical model where the complexity of the global
packing can be understood in terms of two simple, local parameters the
available space around a particle and the ratio of contacts to neighbours.
Maxime Clusel, Eric I. Corwin, Alexander O. N. Siemens and Jasna Brujic
doi:10.1038/nature08158
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08158.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08158.html
Carbon respiration from subsurface peat accelerated by climate warming in
the subarctic pp616-619
The feedback between the terrestrial carbon cycle and climate is one of the
largest uncertainties in current projections of future climate, with the
long-term sensitivity of carbon in peatlands remaining unclear. The
combination of non-disturbing in situ measurements of carbon dioxide
respiration rates and isotopic composition of respired CO2 in subarctic
peatland experiments now shows that warming accelerates respiration rates
of these subsurface carbon reservoirs to a much larger extent than was
previously thought.
Ellen Dorrepaal et al.
doi:10.1038/nature08216
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08216.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08216.html
Progressive mixing of meteoritic veneer into the early Earth/'s deep mantle
pp620-623
Komatiites are ancient volcanic rocks, mostly from the Archaean era, that
formed through high degrees of partial melting of the mantle and therefore
provide reliable information on bulk mantle compositions. Here it is shown
that most early Archaean komatiites from the Barberton greenstone belt of
South Africa and the Pilbara craton of Western Australia are depleted in
platinum group elements (PGEs) relative to late Archaean and younger
komatiites, and the variations of this depletion with time suggests that
PGE-enriched cosmic material was progressively mixed into the deep mantle.
Wolfgang D. Maier et al.
doi:10.1038/nature08205
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08205.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08205.html
A viscosity-enhanced mechanism for biogenic ocean mixing pp624-626
Sir Charles Darwin, grandson of the famous evolutionary pioneer, was a
physicist who suggested that swimming animals might contribute significantly
to the mixing of water in the ocean. Here, observations of swimming
jellyfish are used to create and validate a theoretical model for the
relative contributions of Darwinian mixing and turbulent wake mixing.
The contribution of living organisms to ocean mixing is found to be
substantial [mdash] in the same order of magnitude as winds and tides.
Kakani Katija and John O. Dabiri
doi:10.1038/nature08207
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08207.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08207.html
Adult satellite cells and embryonic muscle progenitors have distinct
genetic requirements pp627-631
The myogenic determinant Pax7 is thought to have a critical role in adult
muscle stem cells (satellite cells), but a formal demonstration has been
lacking in vivo. Here it is shown that, unexpectedly, when Pax7 is
inactivated
in adult mice, mutant satellite cells are not compromised in muscle
regeneration. Multiple time points of gene inactivation reveal that Pax7
is only required up to the juvenile period, indicating an age-dependent
change in the genetic requirement for muscle stem cells.
Christoph Lepper, Simon J. Conway and Chen-Ming Fan
doi:10.1038/nature08209
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08209.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08209.html
Presenilins are essential for regulating neurotransmitter
release pp632-636
Mutations in the presenilin genes are associated with familial cases of
Alzheimer's disease, but the precise site and nature of the synaptic
dysfunction remain unknown. Using a genetic approach to selectively
inactivate presenilins in a mouse model, it has been possible to demonstrate
that they act in the presynaptic compartment to control the
activity-dependent efficacy of neurotransmitter release, a process essential
for neuronal computation, learning and memory.
Chen Zhang et al.
doi:10.1038/nature08177
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08177.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08177.html
Macrophage elastase kills bacteria within murine macrophages pp637-641
Macrophages possess several substances with which they can kill bacteria,
including reactive oxygen species, nitric oxide, and antimicrobial proteins.
Here, macrophage elastase, an enzyme implicated in several disease processes
including emphysema, is shown to have direct antimicrobial activity against
Gram-positive and Gram-negative bacteria.
A. McGarry Houghton et al.
doi:10.1038/nature08181
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08181.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08181.html
MicroRNA-mediated switching of chromatin-remodelling complexes in neural
development pp642-646
During development of the vertebrate nervous system, a switch in the subunit
composition of the BAF chromatin-remodelling complex occurs when cells lose
multipotency and begin to develop stable connections that will persist for
a lifetime. Here, the switch in BAF subunits is shown to be mediated by two
microRNAs that are selectively expressed in post-mitotic neurons.
Andrew S. Yoo, Brett T. Staahl, Lei Chen and Gerald R. Crabtree
doi:10.1038/nature08139
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08139.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08139.html
Evidence of Xist RNA-independent initiation of mouse imprinted X-chromosome
inactivation pp647-651
Female mammals undergo silencing of most genes on one of their two X
chromosomes in a process termed X-chromosome inactivation (XCI). In
placental mammals, the non-coding RNA Xist is thought to trigger XCI.
Here it is demonstrated that silencing of the paternal X chromosome (Xp)
is able to initiate in the absence of paternal Xist; Xist is, however,
required to stabilize silencing along the Xp.
Sundeep Kalantry et al.
doi:10.1038/nature08161
Abstract:
http://www.nature.com/nature/journal/v460/n7255/abs/nature08161.html
Article:
http://www.nature.com/nature/journal/v460/n7255/full/nature08161.html
环境科学之家（http://www.eschina.org.cn/）
| 《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 |
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