《Nature》目录要览：2009-08-13出版
时间：2009-08-14 阅读： 我要评论:
《Nature》目录要览：2009-08-13出版
封面故事： 柏拉图多面体和阿基米德多面体的最紧密堆积
Dense packings of the Platonic and Archimedean solids
基于致密颗粒堆积几何知识的模型，可帮助解释很多体系的结构，包括液体、玻璃、晶
体、颗粒和生物体系。这一领域以前的研究工作大部分集中在球状颗粒上，但即使对这
种理想化的形状，这个问题仍然极为困难——Kepler关于球体最紧密堆积的猜想直到
2005年才得到证明。人们对18个经典几何形状——柏拉图多面体和阿基米德多面体（如
本期封面所示）——的最紧密排列知之甚少，虽然它们自古希腊时代以来就为人们所知
了。现在，Salvatore Torquato 和 Yang Jiao报告了5种柏拉图多面体（四面体、立方
体、八面体、十二面体和二十面体）和13种阿基米德多面体的已知最紧密排列。这些多
面体的对称性在决定它们基本堆积排列中非常关键，具有中心对称性的柏拉图多面体和
阿基米德多面体的最紧密堆积被猜想由它们相应的最紧密（布拉菲）晶格堆积给出。
（Letter p. 876; News & Views）
干细胞中的染色质开放性（Open chromatin in stem cells）
Chd1 regulates open chromatin and pluripotency of embryonic stem cells
在从扁形虫到哺乳动物在内的很多干细胞中，染色质大部分没有异染色质，所以对转录
调控因子来说它们是完全开放的。现在，对小鼠胚胎细胞中的新颖调控因子所做的一项
RNA干涉筛选工作表明，染色质重构因子Chd1是维持染色质开放性和胚胎细胞多能性所
必需的，也是体细胞重新编程为多能细胞所必需的。这是关于染色质开放性及多能性之
间存在一个因果关系的直接证据。Chd1在生殖细胞和成年干细胞中都高度表达，因而我
们看到这样一个可能性：染色质开放性与干细胞分化潜力之间的关系是一个普遍现象。
（Article p. 863; News & Views）
Ia-类超新星爆炸物理学及辐射传输的模拟研究（Supernovae worth the candle）
The diversity of type Ia supernovae from broken symmetries
Ia-类超新星的光曲线近乎一致，这使得它们成为测量宇宙膨胀的很好的标准光源，但
必须进行观测校正（其物理原理尚不知道），才能解释更亮的超新星有更宽的光曲线这
样一个事实。Kasen等人报告了对Ia-类超新星爆炸物理学及辐射传输的多维模拟研究，
其结果显示，球形对称的破坏在决定宽度-亮度关系和所观测到的散射中都是一个关键
因子。宽度-亮度关系的斜率和标准化对碳和氧之外的元素的痕量丰度有一个弱的依赖
性。若不校正这一效应，将有可能导致对遥远超新星距离的估计系统性地过高达2%。这
项工作朝着两个方向迈出了一步：一是解释Ia-类超新星事件的性质；二是解释它们之
所以适合作为“宇宙探测器”的物理原因。（Letter p. 869）
“土卫六”上赤道附近云的形成（Stormy weather on Titan）
Storms in the tropics of Titan
关于“土卫六”的最新观测结果推翻了人们以前所达成的共识：大的对流云无法在“土
卫六”赤道附近形成。“土卫六”是太阳系中除地球之外惟一具有能够形成云和雨的一
种可凝固物质（在“土卫六”上为甲烷，在地球上为水）的地方。人们以前曾在潮湿的
高纬度地区观察到甲烷云和湖，但热带地区一直以来几乎没有对流云。来自美国国家航
空航天局红外望远镜及北双子座望远镜（这两个望远镜都在夏威夷的莫纳克亚山上）的
有关“土卫六”的新图片显示了一个大的云体系，由热带纬度地区的明亮的、瞬时的对
流层云构成。云活动的最初的一个脉冲产生了行星波，它们在“土卫六”上几年来一直
没有云的其他纬度地区造成了云的形成。（Letter p. 873）
大西洋海盆历史上的飓风活动（Tropical cyclones in context）
Atlantic hurricanes and climate over the past 1,500 years
对过去1500年整个大西洋海盆范围内飓风发生情况所做的一次新的重建研究显示，虽然
目前飓风活动异常强，但在公元1000年左右的中世纪变暖期一样强、甚至更强。该项重
建工作是根据两种独立的方法进行的：关于登陆飓风的综合性区域沉积物证据和关于由
过去气候变化的代用指标重建驱动的大西洋热带气旋活动的一个统计模型。（Letter
p. 880; News & Views）
冰川和气候对山系高度的影响（How high the mountains）
Glacial effects limiting mountain height
“冰锯”侵蚀机制是人们提出的一个假设，用来解释山系的总高度可被冰川化程度影响
这样的观测结果。现在，对冰川侵蚀在全球尺度上限制山脉地貌中所起作用所做的一项
系统分析显示，对很多高的山系来说，山脉最大高度的变化与由气候控制的雪线高度的
梯度密切相关。数值模拟显示，由冰川滑动所造成的雪线之上的侵蚀性地貌破坏与由侵
蚀性加载所造成的相应的均衡性景观隆起相结合，可解释关于山脉最大高度的观测结
果，只需要将高程向仅低于雪线的一个海拔窗口提升就行了。该模型表明，山系高度的
差别一般所反映的是局部气候的变化，而不是构造力的变化。（Letter p. 884）
早期进行体内受精的盾皮鱼（Early internal fertilization）
Pelvic claspers confirm chondrichthyan-like internal fertilization in
arthrodires
盾皮鱼是一大类原始有甲鱼类。虽然完全灭绝，但它们神秘的解剖体系有可能含有关于
有颌类脊椎动物、包括我们人类自己演化历史的线索。一个新的化石发现，澄清了关于
Incisoscutum的生殖机制的问题。Incisoscutum作为节颈鱼家族（一个大而重要的盾皮
鱼类别）的一个成员尤为研究人员所感兴趣。研究人员最近发现了一只成年
Incisoscutum ritcchiei雌性个体的一个保存完好的化石，它含有胚胎，这是体内受精
的证据。而新发现的化石是该物种的一个雄性个体，长有阴茎一样的交脚器，与化石褶
齿鱼（一类未披甲的盾皮鱼）和鲨鱼中所见的相似。（Letter p. 888）
酵母的同性交配（Same-sex mating in yeasts）
Homothallic and heterothallic mating in the opportunistic pathogen Candida
albicans
病原体酵母“白念珠菌”过去曾被认为是严格无性生殖的，但现在人们知道，这种生物
有一个秘密交配循环。交配通常涉及a-细胞类型和alpha-细胞类型的融合，与相关酵母
“酿酒酵母”中所见的类似。现在，另外一种新颖的有性生殖模式已在“白念珠菌”中
被发现：在特定情况下，即在没有为一种分泌出的蛋白酶编码的BAR1基因存在的情况
下，高效同性交配可在a-型细胞之间进行。“白念珠菌”的同性交配与相关真菌病原体
“新型隐球菌”的同性交配之间的相似性提出一个可能性：这种类型的“同宗配合”也
许可帮助这些物种在哺乳动物宿主体内更加具有适应性。（Letter p. 890; News &
Views）
肿瘤抑制因子的功能获得性突变（Gain-of-function oncogenes）
Gain-of-function of mutated C-CBL tumour suppressor in myeloid neoplasms
正常人类细胞含有来自双亲中每一方的全套染色体，但在某些癌症中，部分特定染色体
的两个版本都来自同一亲代——该现象被称为“获得性单亲二体”。对来自从患有髓样
肿瘤的患者取来的超过200份骨髓样本的基因组DNA所做研究，发现11号染色体的一部分
的两个版本都遗传自单亲的发生率较高，该部分含有肿瘤抑制因子C-CBL的一个功能获
得性突变，它使成纤维细胞发生癌变，使造血干细胞对细胞因子刺激更敏感。这些数据
支持这样一个观点：c-Cbl是一个肿瘤抑制基因，癌症中所发生的突变能够以功能获得
性方式发挥作用，正如以前对肿瘤抑制基因p53所发现的那样。（Letter p. 904; News
& Views）
Lin28在原始生殖细胞发育中的作用（Reproductive cell formation）
A role for Lin28 in primordial germ-cell development and germ-cell
malignancy
对30个候选基因所做的一个RNA干涉筛选，识别出Lin28（let-7 microRNA处理的一个负
调控因子）为原始生殖细胞发育（这是发育中的胚胎内所发生的一个过程，它选择注定
要产生精子和卵子的细胞）的一个潜在关键调控因子。另外，Lin28水平在原发性人类
生殖细胞肿瘤中升高，说明它也许也与生殖细胞恶性肿瘤有关。（Letter p. 909）
MRE11在端粒上的两个作用（MRN and the telomere: a complex tale）
Multiple roles for MRE11 at uncapped telomeres
线性真核染色体的末端由被称为端粒的序列所覆盖。虽然这些地方是一次DNA双链断裂
（这种断裂是一种病灶，必须予以修复，才能维持基因组的完整性）的一半，但端粒通
常并不激发DNA损伤修复通道。端粒维护过程中一个主要角色是MRN复合物，它由三个蛋
白（MRE11、RAD50 和NBS1）组成。现在，用要么使整个MRN复合物失去活性、要么仅仅
使MRE1的核酸酶失去活性的等位基因对小鼠所做的一项研究表明，MRE11在端粒上有两
个作用。它通过促进一个悬垂的DNA端的形成来保护新合成的端粒端不受修复因子影
响；而当端粒不能正常发挥功能时，它使这种悬垂结构降级，以促进融合修复。
（Letter p. 914）
----------------------
NEWS AND VIEWS
----------------------
Mathematical physics: A tight squeeze pp801-802
How can identical particles be crammed together as densely as possible?
A combination of theory and computer simulations shows how the answer
to this intricate problem depends on the shape of the particles.
Henry Cohn
doi:10.1038/460801a
http://www.nature.com/nature/journal/v460/n7257/full/460801a.html
Stem cells: Escaping fates with open states pp802-803
The ability of embryonic stem cells to give rise to any cell type relies
on a remodelling protein that maintains open chromatin. But the chromatin
landscape of these cells may be more complex than previously thought.
Robert J. Sims III and Danny Reinberg
doi:10.1038/460802a
http://www.nature.com/nature/journal/v460/n7257/full/460802a.html
Ecology: Elementary factors pp803-804
The identification of a general connection between biogeochemistry and
the structure of food webs would constitute a considerable advance in
understanding ecosystems. Ecologists are on the case.
Josep Pen~uelas and Jordi Sardans
doi:10.1038/460803a
http://www.nature.com/nature/journal/v460/n7257/full/460803a.html
Cancer: More than kin and less than kind pp804-807
A gene that is found to be mutated in a type of blood cancer exhibits
properties of both a growth-suppressing tumour suppressor and a
growth-promoting oncogene.
Kevin Shannon and Mignon Loh
doi:10.1038/460804a
http://www.nature.com/nature/journal/v460/n7257/full/460804a.html
Chemical biology: Protein picker p805
Andrew Mitchinson
doi:10.1038/460805a
http://www.nature.com/nature/journal/v460/n7257/full/460805a.html
50 & 100 years ago p807
doi:10.1038/460807b
http://www.nature.com/nature/journal/v460/n7257/full/460807b.html
Microbial genetics: Love the one you're with pp807-808
Candida albicans is notorious as an opportunistic microbe that causes
thrush and serious systemic disease. For geneticists, however, it offers
continuing revelations into the wondrously varied sex lives of fungi.
Joseph Heitman
doi:10.1038/460807a
http://www.nature.com/nature/journal/v460/n7257/full/460807a.html
----------------------
NEWS AND VIEWS Q&A
----------------------
Technology: Hydrogen-fuelled vehicles pp809-811
Hydrogen is hailed as a non-polluting synthetic fuel that could replace
oil, especially for transport applications. The technology to make this
a reality ― particularly hydrogen-storage materials ― has been a long
time coming, but the first commercial vehicles might now be only a few years
away.
Louis Schlapbach
doi:10.1038/460809a
http://www.nature.com/nature/journal/v460/n7257/full/460809a.html
----------------------
INSIGHT
----------------------
EDITORIAL
Metalloproteins p813
Joshua Finkelstein
doi:10.1038/460813a
http://www.nature.com/nature/journal/v460/n7257/full/460813a.html
REVIEW ARTICLE
Structure--function relationships of anaerobic gas-processing
metalloenzymes pp814-822
Juan C. Fontecilla-Camps et al.
doi:10.1038/nature08299
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08299.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08299.html
Metalloproteins and metal sensing pp823-830
Kevin J. Waldron, Julian C. Rutherford, Dianne Ford and Nigel J. Robinson
doi:10.1038/nature08300
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08300.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08300.html
Function and biogenesis of iron--sulphur proteins pp831-838
Roland Lill
doi:10.1038/nature08301
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08301.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08301.html
Molybdenum cofactors, enzymes and pathways pp839-847
Gu"nter Schwarz, Ralf R. Mendel and Markus W. Ribbe
doi:10.1038/nature08302
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08302.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08302.html
Mechanistic considerations of halogenating enzymes pp848-854
Alison Butler and Moriah Sandy
doi:10.1038/nature08303
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08303.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08303.html
Design of functional metalloproteins pp855-862
Yi Lu, Natasha Yeung, Nathan Sieracki and Nicholas M. Marshall
doi:10.1038/nature08304
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08304.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08304.html
----------------------
ARTICLE
----------------------
Chd1 regulates open chromatin and pluripotency of embryonic stem
cells pp863-868
A hallmark of stem cells is an open chromatin largely devoid of
heterochromatin,
but which molecules are required to maintain it is unknown, as well as
whether
an open chromatin is necessary for the differentiation potential of stem
cells.
Here, the chromatin remodelling factor Chd1 is shown to be required to
maintain
the open chromatin state of pluripotent mouse embryonic stem cells and to be
essential for the pluripotency of these cells.
Alexandre Gaspar-Maia et al.
doi:10.1038/nature08212
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08212.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08212.html
----------------------
LETTERS
----------------------
The diversity of type Ia supernovae from broken symmetries pp869-872
The near uniformity of the light curves of type Ia supernovae makes them
good
'standard candles' for measuring cosmic expansion, but a correction must be
applied to account for the fact that the brighter ones have broader light
curves. Here, multi-dimensional modelling of the explosion physics and
radioactive transfer reveals that failing to correct for an effect on the
slope and normalization of the width-luminosity relation could lead to
systematic overestimates of up to 2% of the distance to remote supernovae.
D. Kasen, F. K. Ro"pke and S. E. Woosley
doi:10.1038/nature08256
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08256.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08256.html
Storms in the tropics of Titan pp873-875
The presence of small-scale channels and dry riverbeds at latitudes thought
incapable of supporting convection on Saturn's moon Titan has therefore been
suggested to be due to mechanisms unrelated to precipitation. Here, however,
the presence of bright, transient, tropospheric clouds in tropical latitudes
is reported. It is thought that convective pulses at one latitude can
trigger
short-term convection at other latitudes, resulting in methane rain.
E. L. Schaller, H. G. Roe, T. Schneider and M. E. Brown
doi:10.1038/nature08193
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08193.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08193.html
Dense packings of the Platonic and Archimedean solids pp876-879
Kepler's conjecture gives the densest possible packing for spherical
particles
but, until now, there has not been an analogous system for determining dense
polyhedral packings. Using a variety of multiparticle initial configurations
it has now been possible to determine the densest known packings for the
Platonic
solids and to conjecture that those of Platonic and Archimedean solids with
central symmetry are given by their corresponding densest lattice packings.
S. Torquato and Y. Jiao
doi:10.1038/nature08239
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08239.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08239.html
Atlantic hurricanes and climate over the past 1,500 years pp880-883
Tropical cyclone activity in the Atlantic, as measured by annual storm
counts,
reached unusually high levels over the past decade. This recent activity is
now
placed in a longer-term context by comparing two independent estimates of
hurricane activity over the past 1,500 years; there is evidence of a peak in
Atlantic tropical cyclone activity during medieval times (around AD 1000)
that
rivals or exceeds recent levels of activity.
Michael E. Mann, Jonathan D. Woodruff, Jeffrey P. Donnelly and Zhihua Zhang
doi:10.1038/nature08219
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08219.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08219.html
Glacial effects limiting mountain height pp884-887
There are indications that the general height of mountain ranges is directly
influenced by the extent of glaciation through an efficient denudation
mechanism
known as the glacial buzzsaw. Here, a global analysis of topography shows
that
variations in maximum mountain height correlate closely with
climate-controlled
gradients in snowline altitude rather than with tectonic activity. Further,
the
use of a numerical model self-consistently produces the hypsometric
signature
of the glacial buzzsaw.
D. L. Egholm, S. B. Nielsen, V. K. Pedersen and J.-E. Lesemann
doi:10.1038/nature08263
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08263.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08263.html
Pelvic claspers confirm chondrichthyan-like internal fertilization in
arthrodires
pp888-889
The placoderms are a large group of primitive armoured fishes, which,
although
now extinct, could shed light on the evolution of jawed vertebrates. Recent
fossil finds have been discovered with embryos, illustrating that
fertilization
was internal, but direct evidence for this was missing. Here, the discovery
of
a completely ossified pelvic clasper in a male Incisoscutum ritchiei
confirms
internal fertilization in arthrodires, a large and important placoderm
group.
Per Ahlberg, Kate Trinajstic, Zerina Johanson and John Long
doi:10.1038/nature08176
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08176.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08176.html
Homothallic and heterothallic mating in the opportunistic pathogen Candida
albicans pp890-893
Until recently, the human pathogenic yeast Candida albicans was thought to
be
strictly asexual, existing only as an obligate diploid. However, here it is
shown that under specific conditions [mdash] in the absence of the secreted
protease Bar1 - efficient same-sex mating can take place.
Kevin Alby, Dana Schaefer and Richard J. Bennett
doi:10.1038/nature08252
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08252.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08252.html
Programming cells by multiplex genome engineering and accelerated evolution
pp894-898
Genomic diversity is difficult to generate in the laboratory in an efficient
way. Here, multiplex automated genome engineering (MAGE) is described for
large-scale programming and evolution of cells. It is an automated and
efficient approach that expedites the design and evolution of organisms
with new and improved properties.
Harris H. Wang et al.
doi:10.1038/nature08187
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08187.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08187.html
Intrinsic light response of retinal horizontal cells of
teleosts pp899-903
It has recently become apparent that rods and cones are not the only
photoreceptors in mammals. A third class, known as intrinsically
photosensitive retinal ganglion cells, use the photopigment melanopsin
and mediate non-image-forming visual functions such as circadian
photoentrainment. In teleost fish, a subset of horizontal cells is now
shown to be photosensitive; the photopigment responsible for this seems to
be melanopsin.
Ning Cheng, Takashi Tsunenari and King-Wai Yau
doi:10.1038/nature08175
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08175.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08175.html
Gain-of-function of mutated C-CBL tumour suppressor in myeloid neoplasms
pp904-908
Acquired uniparental disomy (aUPD), a common feature of cancer genomes,
is associated with gain-of-function mutations of proto-oncogenes as well
as with loss-of-function mutations of tumour suppressor genes. Here,
gain-of-function mutations of the C-CBL tumour suppressor are shown to
be tightly associated with aUPD of the 11q arm in certain myeloid neoplasms.
Masashi Sanada et al.
doi:10.1038/nature08240
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08240.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08240.html
A role for Lin28 in primordial germ-cell development and germ-cell
malignancy
pp909-913
In order to investigate the earliest molecular mechanisms of germ cell
specification, mouse embryonic stem cells were differentiated into putative
primordial germ cells (PGCs) in vitro. The use of inhibitory RNAs to then
screen candidate genes for effects on the development of these cells
demonstrates a genetic pathway for PGC specification involving Lin28, a
negative regulator of let-7 microRNA processing.
Jason A. West et al.
doi:10.1038/nature08210
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08210.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08210.html
Multiple roles for MRE11 at uncapped telomeres pp914-918
The ends of linear eukaryotic chromosomes are capped by sequences known as
telomeres. Although telomeres are essentially one half of a DNA
double-strand
break, which is a pathogenic lesion that must be repaired, telomeres do not
normally activate DNA damage repair pathways. Here, the three-member MRN
complex is shown to serve two roles at the telomere: it protects newly
synthesized telomeric ends from repair factors and it promotes a type of
fusion repair when the telomere is not functioning properly.
Yibin Deng, Xiaolan Guo, David O. Ferguson and Sandy Chang
doi:10.1038/nature08196
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08196.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08196.html
----------------------
FUTURES
----------------------
Bombs away! p924
Happy landings.
Paul Di Filippo
doi:10.1038/460924a
http://www.nature.com/nature/journal/v460/n7257/full/460924a.html
Dense packings of the Platonic and Archimedean solids
基于致密颗粒堆积几何知识的模型，可帮助解释很多体系的结构，包括液体、玻璃、晶
体、颗粒和生物体系。这一领域以前的研究工作大部分集中在球状颗粒上，但即使对这
种理想化的形状，这个问题仍然极为困难——Kepler关于球体最紧密堆积的猜想直到
2005年才得到证明。人们对18个经典几何形状——柏拉图多面体和阿基米德多面体（如
本期封面所示）——的最紧密排列知之甚少，虽然它们自古希腊时代以来就为人们所知
了。现在，Salvatore Torquato 和 Yang Jiao报告了5种柏拉图多面体（四面体、立方
体、八面体、十二面体和二十面体）和13种阿基米德多面体的已知最紧密排列。这些多
面体的对称性在决定它们基本堆积排列中非常关键，具有中心对称性的柏拉图多面体和
阿基米德多面体的最紧密堆积被猜想由它们相应的最紧密（布拉菲）晶格堆积给出。
（Letter p. 876; News & Views）
干细胞中的染色质开放性（Open chromatin in stem cells）
Chd1 regulates open chromatin and pluripotency of embryonic stem cells
在从扁形虫到哺乳动物在内的很多干细胞中，染色质大部分没有异染色质，所以对转录
调控因子来说它们是完全开放的。现在，对小鼠胚胎细胞中的新颖调控因子所做的一项
RNA干涉筛选工作表明，染色质重构因子Chd1是维持染色质开放性和胚胎细胞多能性所
必需的，也是体细胞重新编程为多能细胞所必需的。这是关于染色质开放性及多能性之
间存在一个因果关系的直接证据。Chd1在生殖细胞和成年干细胞中都高度表达，因而我
们看到这样一个可能性：染色质开放性与干细胞分化潜力之间的关系是一个普遍现象。
（Article p. 863; News & Views）
Ia-类超新星爆炸物理学及辐射传输的模拟研究（Supernovae worth the candle）
The diversity of type Ia supernovae from broken symmetries
Ia-类超新星的光曲线近乎一致，这使得它们成为测量宇宙膨胀的很好的标准光源，但
必须进行观测校正（其物理原理尚不知道），才能解释更亮的超新星有更宽的光曲线这
样一个事实。Kasen等人报告了对Ia-类超新星爆炸物理学及辐射传输的多维模拟研究，
其结果显示，球形对称的破坏在决定宽度-亮度关系和所观测到的散射中都是一个关键
因子。宽度-亮度关系的斜率和标准化对碳和氧之外的元素的痕量丰度有一个弱的依赖
性。若不校正这一效应，将有可能导致对遥远超新星距离的估计系统性地过高达2%。这
项工作朝着两个方向迈出了一步：一是解释Ia-类超新星事件的性质；二是解释它们之
所以适合作为“宇宙探测器”的物理原因。（Letter p. 869）
“土卫六”上赤道附近云的形成（Stormy weather on Titan）
Storms in the tropics of Titan
关于“土卫六”的最新观测结果推翻了人们以前所达成的共识：大的对流云无法在“土
卫六”赤道附近形成。“土卫六”是太阳系中除地球之外惟一具有能够形成云和雨的一
种可凝固物质（在“土卫六”上为甲烷，在地球上为水）的地方。人们以前曾在潮湿的
高纬度地区观察到甲烷云和湖，但热带地区一直以来几乎没有对流云。来自美国国家航
空航天局红外望远镜及北双子座望远镜（这两个望远镜都在夏威夷的莫纳克亚山上）的
有关“土卫六”的新图片显示了一个大的云体系，由热带纬度地区的明亮的、瞬时的对
流层云构成。云活动的最初的一个脉冲产生了行星波，它们在“土卫六”上几年来一直
没有云的其他纬度地区造成了云的形成。（Letter p. 873）
大西洋海盆历史上的飓风活动（Tropical cyclones in context）
Atlantic hurricanes and climate over the past 1,500 years
对过去1500年整个大西洋海盆范围内飓风发生情况所做的一次新的重建研究显示，虽然
目前飓风活动异常强，但在公元1000年左右的中世纪变暖期一样强、甚至更强。该项重
建工作是根据两种独立的方法进行的：关于登陆飓风的综合性区域沉积物证据和关于由
过去气候变化的代用指标重建驱动的大西洋热带气旋活动的一个统计模型。（Letter
p. 880; News & Views）
冰川和气候对山系高度的影响（How high the mountains）
Glacial effects limiting mountain height
“冰锯”侵蚀机制是人们提出的一个假设，用来解释山系的总高度可被冰川化程度影响
这样的观测结果。现在，对冰川侵蚀在全球尺度上限制山脉地貌中所起作用所做的一项
系统分析显示，对很多高的山系来说，山脉最大高度的变化与由气候控制的雪线高度的
梯度密切相关。数值模拟显示，由冰川滑动所造成的雪线之上的侵蚀性地貌破坏与由侵
蚀性加载所造成的相应的均衡性景观隆起相结合，可解释关于山脉最大高度的观测结
果，只需要将高程向仅低于雪线的一个海拔窗口提升就行了。该模型表明，山系高度的
差别一般所反映的是局部气候的变化，而不是构造力的变化。（Letter p. 884）
早期进行体内受精的盾皮鱼（Early internal fertilization）
Pelvic claspers confirm chondrichthyan-like internal fertilization in
arthrodires
盾皮鱼是一大类原始有甲鱼类。虽然完全灭绝，但它们神秘的解剖体系有可能含有关于
有颌类脊椎动物、包括我们人类自己演化历史的线索。一个新的化石发现，澄清了关于
Incisoscutum的生殖机制的问题。Incisoscutum作为节颈鱼家族（一个大而重要的盾皮
鱼类别）的一个成员尤为研究人员所感兴趣。研究人员最近发现了一只成年
Incisoscutum ritcchiei雌性个体的一个保存完好的化石，它含有胚胎，这是体内受精
的证据。而新发现的化石是该物种的一个雄性个体，长有阴茎一样的交脚器，与化石褶
齿鱼（一类未披甲的盾皮鱼）和鲨鱼中所见的相似。（Letter p. 888）
酵母的同性交配（Same-sex mating in yeasts）
Homothallic and heterothallic mating in the opportunistic pathogen Candida
albicans
病原体酵母“白念珠菌”过去曾被认为是严格无性生殖的，但现在人们知道，这种生物
有一个秘密交配循环。交配通常涉及a-细胞类型和alpha-细胞类型的融合，与相关酵母
“酿酒酵母”中所见的类似。现在，另外一种新颖的有性生殖模式已在“白念珠菌”中
被发现：在特定情况下，即在没有为一种分泌出的蛋白酶编码的BAR1基因存在的情况
下，高效同性交配可在a-型细胞之间进行。“白念珠菌”的同性交配与相关真菌病原体
“新型隐球菌”的同性交配之间的相似性提出一个可能性：这种类型的“同宗配合”也
许可帮助这些物种在哺乳动物宿主体内更加具有适应性。（Letter p. 890; News &
Views）
肿瘤抑制因子的功能获得性突变（Gain-of-function oncogenes）
Gain-of-function of mutated C-CBL tumour suppressor in myeloid neoplasms
正常人类细胞含有来自双亲中每一方的全套染色体，但在某些癌症中，部分特定染色体
的两个版本都来自同一亲代——该现象被称为“获得性单亲二体”。对来自从患有髓样
肿瘤的患者取来的超过200份骨髓样本的基因组DNA所做研究，发现11号染色体的一部分
的两个版本都遗传自单亲的发生率较高，该部分含有肿瘤抑制因子C-CBL的一个功能获
得性突变，它使成纤维细胞发生癌变，使造血干细胞对细胞因子刺激更敏感。这些数据
支持这样一个观点：c-Cbl是一个肿瘤抑制基因，癌症中所发生的突变能够以功能获得
性方式发挥作用，正如以前对肿瘤抑制基因p53所发现的那样。（Letter p. 904; News
& Views）
Lin28在原始生殖细胞发育中的作用（Reproductive cell formation）
A role for Lin28 in primordial germ-cell development and germ-cell
malignancy
对30个候选基因所做的一个RNA干涉筛选，识别出Lin28（let-7 microRNA处理的一个负
调控因子）为原始生殖细胞发育（这是发育中的胚胎内所发生的一个过程，它选择注定
要产生精子和卵子的细胞）的一个潜在关键调控因子。另外，Lin28水平在原发性人类
生殖细胞肿瘤中升高，说明它也许也与生殖细胞恶性肿瘤有关。（Letter p. 909）
MRE11在端粒上的两个作用（MRN and the telomere: a complex tale）
Multiple roles for MRE11 at uncapped telomeres
线性真核染色体的末端由被称为端粒的序列所覆盖。虽然这些地方是一次DNA双链断裂
（这种断裂是一种病灶，必须予以修复，才能维持基因组的完整性）的一半，但端粒通
常并不激发DNA损伤修复通道。端粒维护过程中一个主要角色是MRN复合物，它由三个蛋
白（MRE11、RAD50 和NBS1）组成。现在，用要么使整个MRN复合物失去活性、要么仅仅
使MRE1的核酸酶失去活性的等位基因对小鼠所做的一项研究表明，MRE11在端粒上有两
个作用。它通过促进一个悬垂的DNA端的形成来保护新合成的端粒端不受修复因子影
响；而当端粒不能正常发挥功能时，它使这种悬垂结构降级，以促进融合修复。
（Letter p. 914）
----------------------
NEWS AND VIEWS
----------------------
Mathematical physics: A tight squeeze pp801-802
How can identical particles be crammed together as densely as possible?
A combination of theory and computer simulations shows how the answer
to this intricate problem depends on the shape of the particles.
Henry Cohn
doi:10.1038/460801a
http://www.nature.com/nature/journal/v460/n7257/full/460801a.html
Stem cells: Escaping fates with open states pp802-803
The ability of embryonic stem cells to give rise to any cell type relies
on a remodelling protein that maintains open chromatin. But the chromatin
landscape of these cells may be more complex than previously thought.
Robert J. Sims III and Danny Reinberg
doi:10.1038/460802a
http://www.nature.com/nature/journal/v460/n7257/full/460802a.html
Ecology: Elementary factors pp803-804
The identification of a general connection between biogeochemistry and
the structure of food webs would constitute a considerable advance in
understanding ecosystems. Ecologists are on the case.
Josep Pen~uelas and Jordi Sardans
doi:10.1038/460803a
http://www.nature.com/nature/journal/v460/n7257/full/460803a.html
Cancer: More than kin and less than kind pp804-807
A gene that is found to be mutated in a type of blood cancer exhibits
properties of both a growth-suppressing tumour suppressor and a
growth-promoting oncogene.
Kevin Shannon and Mignon Loh
doi:10.1038/460804a
http://www.nature.com/nature/journal/v460/n7257/full/460804a.html
Chemical biology: Protein picker p805
Andrew Mitchinson
doi:10.1038/460805a
http://www.nature.com/nature/journal/v460/n7257/full/460805a.html
50 & 100 years ago p807
doi:10.1038/460807b
http://www.nature.com/nature/journal/v460/n7257/full/460807b.html
Microbial genetics: Love the one you're with pp807-808
Candida albicans is notorious as an opportunistic microbe that causes
thrush and serious systemic disease. For geneticists, however, it offers
continuing revelations into the wondrously varied sex lives of fungi.
Joseph Heitman
doi:10.1038/460807a
http://www.nature.com/nature/journal/v460/n7257/full/460807a.html
----------------------
NEWS AND VIEWS Q&A
----------------------
Technology: Hydrogen-fuelled vehicles pp809-811
Hydrogen is hailed as a non-polluting synthetic fuel that could replace
oil, especially for transport applications. The technology to make this
a reality ― particularly hydrogen-storage materials ― has been a long
time coming, but the first commercial vehicles might now be only a few years
away.
Louis Schlapbach
doi:10.1038/460809a
http://www.nature.com/nature/journal/v460/n7257/full/460809a.html
----------------------
INSIGHT
----------------------
EDITORIAL
Metalloproteins p813
Joshua Finkelstein
doi:10.1038/460813a
http://www.nature.com/nature/journal/v460/n7257/full/460813a.html
REVIEW ARTICLE
Structure--function relationships of anaerobic gas-processing
metalloenzymes pp814-822
Juan C. Fontecilla-Camps et al.
doi:10.1038/nature08299
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08299.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08299.html
Metalloproteins and metal sensing pp823-830
Kevin J. Waldron, Julian C. Rutherford, Dianne Ford and Nigel J. Robinson
doi:10.1038/nature08300
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08300.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08300.html
Function and biogenesis of iron--sulphur proteins pp831-838
Roland Lill
doi:10.1038/nature08301
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08301.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08301.html
Molybdenum cofactors, enzymes and pathways pp839-847
Gu"nter Schwarz, Ralf R. Mendel and Markus W. Ribbe
doi:10.1038/nature08302
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08302.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08302.html
Mechanistic considerations of halogenating enzymes pp848-854
Alison Butler and Moriah Sandy
doi:10.1038/nature08303
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08303.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08303.html
Design of functional metalloproteins pp855-862
Yi Lu, Natasha Yeung, Nathan Sieracki and Nicholas M. Marshall
doi:10.1038/nature08304
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08304.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08304.html
----------------------
ARTICLE
----------------------
Chd1 regulates open chromatin and pluripotency of embryonic stem
cells pp863-868
A hallmark of stem cells is an open chromatin largely devoid of
heterochromatin,
but which molecules are required to maintain it is unknown, as well as
whether
an open chromatin is necessary for the differentiation potential of stem
cells.
Here, the chromatin remodelling factor Chd1 is shown to be required to
maintain
the open chromatin state of pluripotent mouse embryonic stem cells and to be
essential for the pluripotency of these cells.
Alexandre Gaspar-Maia et al.
doi:10.1038/nature08212
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08212.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08212.html
----------------------
LETTERS
----------------------
The diversity of type Ia supernovae from broken symmetries pp869-872
The near uniformity of the light curves of type Ia supernovae makes them
good
'standard candles' for measuring cosmic expansion, but a correction must be
applied to account for the fact that the brighter ones have broader light
curves. Here, multi-dimensional modelling of the explosion physics and
radioactive transfer reveals that failing to correct for an effect on the
slope and normalization of the width-luminosity relation could lead to
systematic overestimates of up to 2% of the distance to remote supernovae.
D. Kasen, F. K. Ro"pke and S. E. Woosley
doi:10.1038/nature08256
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08256.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08256.html
Storms in the tropics of Titan pp873-875
The presence of small-scale channels and dry riverbeds at latitudes thought
incapable of supporting convection on Saturn's moon Titan has therefore been
suggested to be due to mechanisms unrelated to precipitation. Here, however,
the presence of bright, transient, tropospheric clouds in tropical latitudes
is reported. It is thought that convective pulses at one latitude can
trigger
short-term convection at other latitudes, resulting in methane rain.
E. L. Schaller, H. G. Roe, T. Schneider and M. E. Brown
doi:10.1038/nature08193
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08193.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08193.html
Dense packings of the Platonic and Archimedean solids pp876-879
Kepler's conjecture gives the densest possible packing for spherical
particles
but, until now, there has not been an analogous system for determining dense
polyhedral packings. Using a variety of multiparticle initial configurations
it has now been possible to determine the densest known packings for the
Platonic
solids and to conjecture that those of Platonic and Archimedean solids with
central symmetry are given by their corresponding densest lattice packings.
S. Torquato and Y. Jiao
doi:10.1038/nature08239
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08239.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08239.html
Atlantic hurricanes and climate over the past 1,500 years pp880-883
Tropical cyclone activity in the Atlantic, as measured by annual storm
counts,
reached unusually high levels over the past decade. This recent activity is
now
placed in a longer-term context by comparing two independent estimates of
hurricane activity over the past 1,500 years; there is evidence of a peak in
Atlantic tropical cyclone activity during medieval times (around AD 1000)
that
rivals or exceeds recent levels of activity.
Michael E. Mann, Jonathan D. Woodruff, Jeffrey P. Donnelly and Zhihua Zhang
doi:10.1038/nature08219
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08219.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08219.html
Glacial effects limiting mountain height pp884-887
There are indications that the general height of mountain ranges is directly
influenced by the extent of glaciation through an efficient denudation
mechanism
known as the glacial buzzsaw. Here, a global analysis of topography shows
that
variations in maximum mountain height correlate closely with
climate-controlled
gradients in snowline altitude rather than with tectonic activity. Further,
the
use of a numerical model self-consistently produces the hypsometric
signature
of the glacial buzzsaw.
D. L. Egholm, S. B. Nielsen, V. K. Pedersen and J.-E. Lesemann
doi:10.1038/nature08263
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08263.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08263.html
Pelvic claspers confirm chondrichthyan-like internal fertilization in
arthrodires
pp888-889
The placoderms are a large group of primitive armoured fishes, which,
although
now extinct, could shed light on the evolution of jawed vertebrates. Recent
fossil finds have been discovered with embryos, illustrating that
fertilization
was internal, but direct evidence for this was missing. Here, the discovery
of
a completely ossified pelvic clasper in a male Incisoscutum ritchiei
confirms
internal fertilization in arthrodires, a large and important placoderm
group.
Per Ahlberg, Kate Trinajstic, Zerina Johanson and John Long
doi:10.1038/nature08176
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08176.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08176.html
Homothallic and heterothallic mating in the opportunistic pathogen Candida
albicans pp890-893
Until recently, the human pathogenic yeast Candida albicans was thought to
be
strictly asexual, existing only as an obligate diploid. However, here it is
shown that under specific conditions [mdash] in the absence of the secreted
protease Bar1 - efficient same-sex mating can take place.
Kevin Alby, Dana Schaefer and Richard J. Bennett
doi:10.1038/nature08252
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08252.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08252.html
Programming cells by multiplex genome engineering and accelerated evolution
pp894-898
Genomic diversity is difficult to generate in the laboratory in an efficient
way. Here, multiplex automated genome engineering (MAGE) is described for
large-scale programming and evolution of cells. It is an automated and
efficient approach that expedites the design and evolution of organisms
with new and improved properties.
Harris H. Wang et al.
doi:10.1038/nature08187
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08187.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08187.html
Intrinsic light response of retinal horizontal cells of
teleosts pp899-903
It has recently become apparent that rods and cones are not the only
photoreceptors in mammals. A third class, known as intrinsically
photosensitive retinal ganglion cells, use the photopigment melanopsin
and mediate non-image-forming visual functions such as circadian
photoentrainment. In teleost fish, a subset of horizontal cells is now
shown to be photosensitive; the photopigment responsible for this seems to
be melanopsin.
Ning Cheng, Takashi Tsunenari and King-Wai Yau
doi:10.1038/nature08175
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08175.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08175.html
Gain-of-function of mutated C-CBL tumour suppressor in myeloid neoplasms
pp904-908
Acquired uniparental disomy (aUPD), a common feature of cancer genomes,
is associated with gain-of-function mutations of proto-oncogenes as well
as with loss-of-function mutations of tumour suppressor genes. Here,
gain-of-function mutations of the C-CBL tumour suppressor are shown to
be tightly associated with aUPD of the 11q arm in certain myeloid neoplasms.
Masashi Sanada et al.
doi:10.1038/nature08240
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08240.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08240.html
A role for Lin28 in primordial germ-cell development and germ-cell
malignancy
pp909-913
In order to investigate the earliest molecular mechanisms of germ cell
specification, mouse embryonic stem cells were differentiated into putative
primordial germ cells (PGCs) in vitro. The use of inhibitory RNAs to then
screen candidate genes for effects on the development of these cells
demonstrates a genetic pathway for PGC specification involving Lin28, a
negative regulator of let-7 microRNA processing.
Jason A. West et al.
doi:10.1038/nature08210
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08210.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08210.html
Multiple roles for MRE11 at uncapped telomeres pp914-918
The ends of linear eukaryotic chromosomes are capped by sequences known as
telomeres. Although telomeres are essentially one half of a DNA
double-strand
break, which is a pathogenic lesion that must be repaired, telomeres do not
normally activate DNA damage repair pathways. Here, the three-member MRN
complex is shown to serve two roles at the telomere: it protects newly
synthesized telomeric ends from repair factors and it promotes a type of
fusion repair when the telomere is not functioning properly.
Yibin Deng, Xiaolan Guo, David O. Ferguson and Sandy Chang
doi:10.1038/nature08196
Abstract:
http://www.nature.com/nature/journal/v460/n7257/abs/nature08196.html
Article:
http://www.nature.com/nature/journal/v460/n7257/full/nature08196.html
----------------------
FUTURES
----------------------
Bombs away! p924
Happy landings.
Paul Di Filippo
doi:10.1038/460924a
http://www.nature.com/nature/journal/v460/n7257/full/460924a.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 |
| 《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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