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2008年11月20日Nature中文摘要
封面故事:
Cover caption
2009年2月是达尔文诞辰200周年,他也许是近代最有影响的科学家。而2009年11月则是
历史上最有影响的著作之一《物种起源》发表150周年。在两个世纪的时间里,没有一
个科学家对科学、政治、宗教、哲学和艺术的影响能与达尔文相比。本期Nature(请看
295页的导言和281页的编者按)是纪念《物种起源》发表150周年专辑,内容包括关于
达尔文、其生活、及其科学和传奇的新闻、研究和分析。达尔文将眼睛(它是如此复
杂,似乎又毫无用处,其任何一个组成成分都只是部分形成)看作是接受自然选择的一
个障碍。今天,我们知道它是进化当中最辉煌的成就之一。本期Nature发表了一篇配有
插图的插页特写文章(p. 304)和当前的研究论文(p. 395),后者提到了达尔文所假
设的“原始眼睛”。在其后期的著作(Descent of Man ,1871)中,达尔文触及了一个
目前在演化生物学家中仍存在分歧的话题——群体选择。自然选择是否是以牺牲群体利
益的方式进行的?这种观点是否是一个历史错误?我们对这个争论及其重要性进行了报
道(News Feature)。灭绝是随着演化(进化)发生的,但它是否是永久性的?随着早
已灭绝的长毛象基因组序列的发表(pp. 387, 330),一些研究人员甚至声称长毛象将
来有一天也将会再生(News Feature p. 310)。生物学家倾向于将演化出的活生物系
统看成是精密的机器,如果其中一个部件发生故障,整个系统就会失灵。但是,正如
Tanguy Chouard所揭示的,真实世界中的情形并不是这样的(News Feature)。有很多
东西让生物学家去纪念,也有很多地方让他们去进行纪念活动:我们对全世界纪念达尔
文生平和工作的活动进行了搜索(p. 322),也对出版商相关纪念活动的书目进行了搜
索(Books & Arts p. 323)。并不是每个人都想进行庆祝活动,虽然我们所采访的科
学家大部分都想进行庆祝(Commentary p, 317),不过对过去的庆祝活动也要进行认
真研究(Essay p. 324)。本期Nature上与达尔文相关的内容以及其他仅在网上发布的
内容可通过以下网址访问:www.nature.com/darwin


Rhcg因子与氨代谢的关系(Getting rid of ammonia)
A role for Rhesus factor Rhcg in renal ammonium excretion and male fertility
关于包括Rh血型抗原(RhCE和 RhD)在内的Rhesus (Rh)因子与微生物氨运输载体在序
列上有远亲关系的出乎意料的发现意味着,这些蛋白可能有一个尚未发现的生物功能。
现在,Biver等人报告说,缺少肾Rhcg因子的小鼠氨分泌受损,应对酸压力的能力减
弱。Rhcg还是附睾流体平衡所需要的,与雄性生育能力有明显关系。这项工作与认为氨
穿过收集管道上皮的运输完全通过类脂相扩散发生的常见假设是矛盾的,并且表明,
Rhcg在肾脏和雄性生殖道内的氨处理和pH值平衡中都起一定作用。(Article p. 339;
News & Views)


成人睾丸干细胞(Adult testis stem cells)
Generation of pluripotent stem cells from adult human testis
虽然成人睾丸细胞仅限于在正常发育过程中产生生殖细胞,但来自几个方面的证据都表
明,它们在适当条件下可成为多能细胞。现在,这些条件已被发现。从来自成人睾丸的
未成熟人精子细胞开始,Conrad等人确定了可像人胚胎干细胞一样被操纵和分化的细胞
系。这些细胞可被稳定地分化成为分泌胰岛素的细胞或肌性细胞系、成骨细胞系和与神
经细胞相似的细胞系。当在皮下移植时,这些细胞会在小鼠身上形成畸胎瘤,这是它们
具有多能性的进一步证据,也反映了这些细胞在再生治疗中所具有的潜力。(Article
p. 344)


哺乳动物“霍利迪连结体”解离酶被发现(Late Holliday junction)
Identification of Holliday junction resolvases from humans and yeast
在减数分裂和同源DNA修复中,会形成一个被称为“霍利迪连结体”(Holliday
junction)的四链DNA中间体。这个结构以共价键方式连接两个DNA分子,因此必须将其
拆解,才能让染色体正确分离和复制。1991年,研究人员发现,大肠杆菌中的ruvC基因
的产物为细菌“霍利迪连结体”解离酶。不过,哺乳动物相应的酶却并不好寻找,但经
过17年之后,它们终于被发现了。人体中的这种酶是一种被称为GEN1的蛋白,酵母中的
这种酶是其直系同源蛋白,即Yen 1。二者都是结构特异性核酶的Rad2/XPG家族的成
员。(Article p. 357)


高能宇宙射线的来源(High-energy cosmic rays)
An excess of cosmic ray electrons at energies of 300–800 GeV
ATIC(高级稀薄电离热量计)宇宙射线天文学实验将氦气球送到南极洲上空35公里以上
的高度,每次持续时间长达15天。这些实验活动探测到了大量来自银河系的宇宙射线电
子,其能量约为300–800 GeV,这表明我们附近有一个高能电子发射源。这个发射源有
可能是一个我们没有看到的天体,该天体将那些电子加速到如此高的能量;这些电子也
可能来自“Kaluza-Klein”暗物质的湮灭。“Kaluza-Klein”暗物质是由涉及“紧致额
外维度”的宇宙理论所预测的一个奇异概念。(Letter p. 362; News & Views)


非传统超导体中产生超导性的电子成对机制(Superconductivity: unlikely pairs)
Twinning superlattices in indium phosphide nanowires
在大多数超导体中,对无电阻导电性负责的电子的成对是由固体晶格中的振动驱动的。
但是也有其他超导材料,在其中,将电子结合在一起的“胶水”被认为有一个很不相同
的起源:自旋或电荷的量子波动。现在,研究人员已在非传统超导体CeRhIn5中发现了
这种成对机制的一种异常“猛烈”的共性(自旋和电荷的不稳定性相加起来的机制)。
这些紧密耦合的波动显著扰乱电子在其正常非成对状态下的流动,但也为产生超导电子
对提供了必要的量子力学“胶水”。(Letter p. 369)


千年尺度气候变化的原因实际上可能比较简单
Glacial greenhouse-gas fluctuations controlled by ocean circulation changes
人们经常用“大西洋经向翻转环流”的突变来解释Dansgaard–Oeschger气候振荡的物
理特点。Dansgaard–Oeschger气候振荡是使上次冰期中断的一系列迅速气候波动,其
周期性与南极洲和格陵兰冰芯中记录的温室气体CO2 和 N2O的波动相关。温室气体的这
种变化曾以不同方式被归因于海洋物理过程、生物过程及陆地生物圈内变化的多样性。
Andreas Schmittner 和 Eric Galbraith介绍了用一个将冰川气候和生物地球化学周期
结合起来的耦合模型完成的模拟结果,这些结果说明,温室气体上述变化的情形实际上
比较简单。他们发现,全球海洋中营养物和溶解氧的分布的变化(由“大西洋经向翻转
环流”的变化所导致),有可能对所观察到的千年尺度变化的大部分做出解释。
(Letter p. 373; News & Views)


克隆长毛象目前仍不大可能(Palaeogenes: mammoth task)
Sequencing the nuclear genome of the extinct woolly mammoth
从在永久冻土中保存的化石和组织中分离出的古代DNA长期以来让人着迷。虽然它已断
裂成了碎片,几乎被现代微生物DNA所淹没,但其序列却能让我们有机会一瞥已灭绝的
生命形式。现在,引发个人基因组革命的同样的大型并行合成DNA测序技术,也使得古
代DNA研究领域发生了革命性变化。本期Nature发表了一种已经灭绝的动物——长毛象
近乎完整的核基因组的测序工作的第一篇报告。对长毛象基因组与非洲象基因组所做比
较表明,出人意料的是,两个基因组都可能比完全测序的胎生哺乳动物的基因组至少大
40%。(Letter p. 387; News and Views)《美国国家科学院院刊》(PNAS)上最近关
于从在冰箱中保存16年的小鼠尸体克隆出小鼠的论文,引发新闻报道说,长毛象的克隆
即将发生。这种可能性有多大?Henry Nicholls提出了这个问题,并且得出结论说,在
目前它仍是幻想。但哺乳动物的克隆也仅仅是在15年前。所以,我们要密切关注这个领
域的发展,但需要有耐心。(News Feature)


视觉注意力调控机制在脑中的精确位置(Francis Crick in the spotlight)
Guarding the gateway to cortex with attention in visual thalamus
注意力转移的显著影响,可由“注意力不集中多动症”儿童的行为得到很好演示。人们
认为,注意力效应出现在丘脑中,但对视觉系统而言,事实证明,要确定传感处理最早
阶段的精确发生位置很困难。现在,McAlonan等人用猕猴所做实验表明,空间注意力调
控发生在“外侧膝状核”中,(使其上发生抑制性连接的)相反效应发生在相邻丘脑网
状核中。这种相互活动可能是产生瞬间注意力的一个机制,从而证实了由Francis
Crick在近25年前提出的一个观点,当时他的兴趣正从DNA转向神经科学。他假设,注意
力的方向是由脑中的一个小核指引的,这个小核正是丘脑网状核。(Letter p. 391)


眼睛的演化及其光传感机制(An eye for evolution)
Mechanism of phototaxis in marine zooplankton
使海洋浮游植物群落依光照条件在海水表层及深层之间转移的微小无脊椎动物幼虫,可
通过双细胞眼点来探测光强度,与达尔文所假设的作为哺乳动物眼睛进化起源的“原始
眼睛”(protoeyes)相似。科学家对来自眼点的传感信息被翻译成运动的机制并不是
很了解。Jékely等人研究了海洋蠕虫岩虫(Platynereis dumerilii)的幼虫,他们发
现,眼点受到的光照,导致相邻纤毛通过胆碱能信号作用产生的节拍发生一个变化。计
算机模型证实了趋光性所受到的这些局部效应的意义,并且预测,如果该生物采取一个
螺旋形游动模式的话,其导航精确度将会提高。光传感与纤毛运动器以这种方式所进行
的直接耦合,有可能是“原始眼睛”的一个功能,是动物眼睛演化过程中的一个重要里
程碑。(Letter p. 395; Author page)本期Nature上还有一篇插页文章也是关于眼睛
演化的。(News Feature p. 304)


----------------------
NEWS AND VIEWS
----------------------
Astrophysics: A message from the dark side pp329-330
Both astrophysicists and particle physicists are in on the hunt
for the elusive dark matter that is thought to pervade the Universe.
A high-altitude balloon-borne experiment offers the latest hints
as to what it could be.
Yousaf M. Butt
doi:10.1038/456329a
http://www.nature.com/nature/journal/v456/n7220/full/456329a.html

DNA sequencing: Mammoth genomics pp330-331
Reconstruction of most of the genome sequence of the woolly mammoth
illustrates how such investigations will pave the way for a deeper
understanding of the biology and evolution of extinct species.
Michael Hofreiter
doi:10.1038/456330a
http://www.nature.com/nature/journal/v456/n7220/full/456330a.html

Palaeoclimate: Greenhouse-gas fingerprints pp331-333
Short episodes of warming and cooling occurred throughout the last
glaciation. An innovative modelling study indicates that ocean-
circulation changes produced much of the causative variation in
greenhouse gases.
Thomas F. Stocker and Adrian Schilt
doi:10.1038/456331a
http://www.nature.com/nature/journal/v456/n7220/full/456331a.html

Cell biology: Nuclear order out of chaos pp333-334
How cells build their internal structures remains one of the
central mysteries in cell biology. If the cell nucleus is anything
to go by, stochastic assembly and self-organization seem to be key.
Tom Misteli
doi:10.1038/456333a
http://www.nature.com/nature/journal/v456/n7220/full/456333a.html

Nanotechnology: Squaring up with polymers pp334-336
Squares may be unfashionable, but for electronic circuitry no other
shape will do. A method for making square arrays of polymeric
nanoparticles could herald the next generation of miniature silicon chips.
Anthony J. Ryan
doi:10.1038/456334a
http://www.nature.com/nature/journal/v456/n7220/full/456334a.html

Cell biology: Why little swimmers take turns p334
Tim Lincoln
doi:10.1038/456334b
http://www.nature.com/nature/journal/v456/n7220/full/456334b.html

Physiology: Courier service for ammonia pp336-337
Physiological studies in mice demonstrate a surprising role for a
kidney protein related to the rhesus factor of red blood cells.
Similar research would aid further annotation of mammalian genomes.
Mark A. Knepper
doi:10.1038/456336a
http://www.nature.com/nature/journal/v456/n7220/full/456336a.html

Structural biology: Enzyme knocked for a loop pp337-338
Protein-digesting enzymes are kept on a tight leash to stop them
from wantonly attacking targets. Two crystal structures show how
an inhibitory protein domain gags one such enzyme without being chewed up
itself.
Ronald L. Mellgren
doi:10.1038/456337a
http://www.nature.com/nature/journal/v456/n7220/full/456337a.html

50 & 100 years ago p337
doi:10.1038/456337b
http://www.nature.com/nature/journal/v456/n7220/full/456337b.html

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Advance Online Publication
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A role for Rhesus factor Rhcg in renal ammonium excretion and male
fertility pp339-343
It is shown that mice lacking the renal Rhcg factor have impaired
ammonium excretion, thereby refuting the long-standing notion that
rapid transepithelial transport of non-ionic ammonia occurs solely
by lipid phase diffusion. In addition, it is shown that Rhcg is
required for epididymal fluid homeostasis with clear consequences for male
fertility.
Sophie Biver et al.
doi:10.1038/nature07518
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07518.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07518.html

Generation of pluripotent stem cells from adult human testis pp344-349
It is now established that pluripotent adult germline stem cells (haGSCs)
are derived from spermatogonial cells of adult human testis and proposed
that it may be possible to derive haGSCs from testicular biopsies to
generate cells for individual cell-based therapy.
Sabine Conrad et al.
doi:10.1038/nature07404
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07404.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07404.html

Identification of Holliday junction resolvases from humans and
yeast pp357-361
A four-stranded DNA intermediate, known as a Holliday junction, is formed
during meiosis and DNA repair. This structure covalently links two DNA
molecules. The product of the RuvC gene in Escherichia coli was shown
to be the bacterial Holliday junction resolvase. The mammalian enzyme
has remained refractory to identification until now, where GEN1 is
identified as the human resolvase.
Stephen C. Y. Ip et al.
doi:10.1038/nature07470
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07470.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07470.html

An excess of cosmic ray electrons at energies of
300-800[thinsp]GeV pp362-365
This paper reports an excess of galactic cosmic-ray electrons at energies
of [sim]300-800 GeV, which indicates a nearby source of energetic
electrons. Such a source could be an unseen astrophysical object that
accelerates electrons to those energies, or the electrons could arise
from the annihilation of dark matter.
J. Chang et al.
doi:10.1038/nature07477
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07477.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07477.html

Isotropic quantum scattering and unconventional
superconductivity pp366-368
In most superconductors, the pairing-up of electrons responsible for
resistance-less conduction is driven by vibrations of the solid's
crystal lattice. But other materials exist in which the attractive
interaction responsible for binding electrons is believed to have a
very different origin: quantum fluctuations of spin or charge. This
paper identifies an unusually 'violent' generalization of such pairing
mechanisms, in which these spin and charge instabilities combine forces.
T. Park et al.
doi:10.1038/nature07431
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07431.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07431.html

Glacial greenhouse-gas fluctuations controlled by ocean circulation
changes pp373-376
This paper presents simulations with a coupled model of glacial climate
and biogeochemical cycles, forced only with changes in the Atlantic
meridional overturning circulation. It is found that variations in
atmospheric carbon dioxide levels on millennial time scales are dominated
by slow changes in the deep ocean inventory of biologically-sequestered
carbon and are correlated to Antarctic temperature and Southern Ocean
stratification. The results suggest that ocean circulation changes were
the primary mechanism that drove glacial fluctuations in carbon dioxide
and nitrous oxide fluctuations on millennial time scales.
Andreas Schmittner and Eric D. Galbraith
doi:10.1038/nature07531
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07531.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07531.html

Long-period earthquakes and co-eruptive dome inflation seen with particle
image velocimetry pp377-381
This study presents optical geodetic observations to constrain the sources
responsible for long-period volcanic earthquakes, which are coincident
with frequent explosive eruptions at Santiaguito Volcano, Guatemala.
It is found that acceleration in deformation of the volcanic dome,
extracted from the high-resolution optical image processing, is
coincident with recorded long-period seismic sources. On the basis
of these observations, abrupt mass shift of solidified domes, conduit
magma or magma pads seem to be part of the mechanism responsible for
generating long-period earthquakes at silicic volcanic systems.
Jeffrey B. Johnson et al.
doi:10.1038/nature07429
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07429.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07429.html

Acoel development indicates the independent evolution of the bilaterian
mouth and anus pp382-386
Most bilaterian animals have a through gut and it is commonly believed
that in the transition from radial to bilaterial symmetry, both openings
evolved simultaneously by the partial, lateral closure of a slit-like
blastopore. This idea is called into question by work on acoel flatworms,
primitive bilaterians that have a mouth but no anus. In studies of the
acoel Convolutriloba longifissura, molecular markers are used to show
that the acoel's mouth does indeed correspond with a mouth, and that
molecular markers characteristic of the hind end of the gut cluster
around the (blind) end of the body, in a posterior domain associated
with a gonopore.
Andreas Hejnol and Mark Q. Martindale
doi:10.1038/nature07309
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07309.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07309.html

Sequencing the nuclear genome of the extinct woolly mammoth pp387-390
This is the first report of the sequencing of the nearly complete
nuclear genome of an extinct animal, the woolly mammoth. 4.1 billion
bases of high quality sequence from several mammoth species are reported,
including 3.3 billion bases from the woolly mammoth. Nuclear-genome
sequencing of extinct species and its comparison with the extant
relatives (in this case African elephant) provide insights into
elephantid evolution and population differences.
Webb Miller et al.
doi:10.1038/nature07446
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07446.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07446.html

Guarding the gateway to cortex with attention in visual
thalamus pp391-394
It was thought that attentional effects arise in the thalamus but for
the visual system, evidence at the single cell level has been rare.
This paper demonstrates spatial attentional modulation in primate
lateral geniculate nucleus as well as opposing effects in the adjacent
thalamic reticular nucleus, which makes inhibitory connections onto it.
Kerry McAlonan, James Cavanaugh and Robert H. Wurtz
doi:10.1038/nature07382
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07382.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07382.html

Mechanism of phototaxis in marine zooplankton pp395-399
Marine zooplankton phototactic swimming involves light sensation by the
eyespots to direct movement, yet the mechanisms underlying the transduction
of this sensory information into locomotion are not well understood. It
is shown that eyespot illumination leads to a change in the beating of
adjacent cilia through cholinergic signalling. Computer models confirmed
the significance of these local effects on phototaxis and predicted
increased navigational precision if the organism adopted a helical
swimming pattern.
Gaspar Jekely et al.
doi:10.1038/nature07590
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07590.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07590.html

The zinc-finger protein Zelda is a key activator of the early zygotic
genome in Drosophila pp400-403
The earliest events of embryogenesis are controlled by maternal gene
products in the oocyte, but at some point after fertilization the zygotic
genome becomes activated. Many of the early transcribed genes in Drosophila
share a cis-regulatory heptamer motif. This paper reports that the
zinc-finger protein, Zelda, binds specifically to these sites, and is
capable of activating transcription in transient transfection assays.
Hsiao-Lan Liang et al.
doi:10.1038/nature07388
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07388.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07388.html

Concerted multi-pronged attack by calpastatin to occlude the catalytic
cleft of heterodimeric calpains pp404-408
The 3.0 A structure of Ca2+-bound m-calpain in complex with the first
calpastatin repeat is solved, revealing the mechanism of the exclusive
specificity. The structure highlights the complexity of calpain activation
by Ca2+, illustrating key residues in a peripheral domain that serve to
stabilize the protease core after Ca2+-binding.
Tudor Moldoveanu, Kalle Gehring and Douglas R. Green
doi:10.1038/nature07353
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07353.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07353.html

Calcium-bound structure of calpain and its mechanism of inhibition by
calpastatin pp409-412
The 2.4 A structure of the Ca2+-bound calpain 2 heterodimer bound to one
of the four inhibitory domains of calpastatin. Calpastatin seems to inhibit
calpain by occupying both the primed and unprimed sides of the active site
cleft. This crystal structure also reveals the conformational changes
that calpain undergoes upon binding calcium, which include opening of
the active site cleft and movement of the domains relative to each
other to produce a more compact enzyme.
Rachel A. Hanna, Robert L. Campbell and Peter L. Davies
doi:10.1038/nature07451
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07451.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07451.html

The ion pathway through the opened Na+,K+-ATPase pump pp413-416
P-type ATPases are molecular machines that use energy derived from ATP
hydrolysis to pump ions across membranes. Recent work on the Na+, K+ ATPase
has identified a pathway for ions from the extracellular side of the protein

to its ion binding sites. This paper employs the marine toxin palytoxin
to 'hold open' the gates of the pump, allowing direct measurements of
ion flow and defines the entire route for ions from one side of the membrane
to the other.
Ayako Takeuchi, Nicolas Reyes, Pablo Artigas and David C. Gadsby
doi:10.1038/nature07350
Abstract:
http://www.nature.com/nature/journal/v456/n7220/abs/nature07350.html?lang=en
Article:
http://www.nature.com/nature/journal/v456/n7220/full/nature07350.html
 
    
 


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