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2007年9月20日Nature中文摘要
 BIOX.CN  来源：生命经纬    2007年09月20日
封面故事：鸡ASIC1的高分辨率晶体结构
Structure of acid-sensing ion channel 1 at 1.9 ? resolution and low pH
酸感应离子通道（ASIC）是质子激活的受体，它们存在于很多人体组织和器官
中，在中枢和周围神经系统中尤其丰富。在小鼠实验中，研究人员发现它们与痛
觉有关，也与条件性恐惧学习行为有关。它们是一个超级受体家族的成员，这个
家族的受体参与从体内钠平衡到机械感觉在内的广泛的生物过程。不过此前，研
究人员还不知道这一重要类别蛋白的结构。现在，来自Eric Gouaux实验室的一
篇论文报告了在封闭状态下鸡ASIC1的高分辨率晶体结构。它是一个三聚体，与
目前所研究过的任何其他通道都不同。它的大型细胞外部分（封面图片的上半部
分，图上的横条代表细胞膜）多空腔和突起，含有一对涉及质子探测的酸性残
基。（Article p. 316; News & Views）


氩-40作为行星排气过程示踪物质的价值受到质疑（Argon-40 to spare?）
40Ar retention in the terrestrial planets
稀有气体被广泛用作地球和其他陆地行星的地幔排气过程的示踪物质，但新的研
究工作对这种做法提出了质疑。具体来讲，研究人员认为，氩-40在大气中的丰
度，代表着在熔岩上升到地表和气体溶出后通过地幔中发生的部分熔融现象随时
间变化从地球内部所损失的气体总量。关于氩在上层地幔的橄榄石和斜方辉石中
的可溶性的新数据显示了这种情景设想所存在的两个主要困难：第一，关于在地
幔熔融过程中所有稀有气体在行为上都是不相容元素的默认假设被这样一个发现
所推翻：氩与陆地行星主要相的相容性似乎要比我们所认为的更大；第二，氩在
这些相中的扩散较慢。这个结果向人们普遍接受的一个观点提出了挑战，该观点
认为，上层地幔几乎将氩-40排尽了；同时该结果也使得氩-40作为行星排气过程
一种监测物质的价值产生了疑问。（Article p. 299; News & Views）


Dmanisi原始人的比较研究（Headed for Europe）
Postcranial evidence from early Homo from Dmanisi, Georgia
来自格鲁吉亚共和国Dmanisi的原始人类经常被认为与“直立人”相似，也被认
为很可能是非洲以外人类家族中已知最早的成员。这个结论到目前为止都是来自
头骨。颅后材料（与一个头骨相关的一个未成年个体的部分骨架以及另外三个成
年个体的身体构成部分）的首次呈现表明，Dmanisi原始人比“直立人”甚至还
要更原始，与“能人”（Homo habilis）相似。在为该论文配发的News & Views
文章中，Daniel Lieberman将这些新发现与来自肯尼亚Turkana湖的发现（刊登
在8月9日的Nature杂志封面上）进行了对比。Lieberman说，从二者之间的相似
性所得出的最初判断是，它们属于同一种。（Article p. 305; News & Views）


基于芯片的微波光子源（On-chip quantum optics）
Generating single microwave photons in a circuit
微波在传统通信技术中从长距离广播到电脑芯片内的短距离信号等方面都已经得
到了利用。但是，它们还有可能被用在量子计算机中，用于远距离量子位
（qubits）之间的通信。现在，研究人员已经研制出单一微波光子的一种高效的
基于芯片的按需光源，它所具有的特点使其适合用于在一个超导量子位电路中来
处理量子信息。这是关于描绘在一个“飞行量子位”（flying qubit）上的一个
超导量子位的首次报告；所谓“飞行量子位”，是指量子信息的一个移动位，它
是量子计算的“DiVincenzo”准则之一。（Letter p. 328）


PETM时期湿地甲烷增加的证据（A warming event）
Increased terrestrial methane cycling at the Palaeocene–Eocene
thermal maximum
大约5500万年前的一个全球变暖时期（即“古新世-始新世热极大”时期或称
PETM时期），被归因于温室气体水平的迅速上升，而甲烷水合物的分解是人们所
提出的最常见的解释。 曾有人提出，来自陆地环境的高纬度甲烷排放可能增强
了这一变暖效应，但此前一直没有直接证据证明来自湿地的甲烷流量有增加。现
在，对Cobham Lignite（最近定性的英格兰东南部的一个系列的沉积物，其时间
跨度经过了PETM时期）所做的一次地球化学分析提供了一定的证据。这些沉积物
记录了在这一温暖时期开始时hopanoids（一种细菌生物标记物）的碳同位素含
量有所下降，这与甲烷微生物数量的增加是一致的。这一结果可能是对在较温暖
和较潮湿气候条件下湿地甲烷产量增加的一个反应，这种反应有可能充当了对全
球变暖的一个正反馈机制。（Letter p. 332）


一个涉及钙调神经磷酸酶的新通道（Calcineurin in fertilization）
Calcineurin is required to release Xenopus egg extracts from meiotic M
phase / Transient activation of calcineurin is essential to initiate
embryonic development in Xenopus laevis
从受精到卵中胞质Ca2+浓度增加（多细胞生物卵激发过程中的一个至关重要的事
件）的通道已经明确确定了，但对其下游通道的研究却不是很多。 现在，两个
研究小组报告了这方面的研究。他们发现了一个新的涉及磷酸酶、钙调神经磷酸
酶的通道。由钙诱导的钙调神经磷酸酶的激发，对于Xeonopus中胚胎发育的抑制
是必不可少的，促使卵母细胞走出受精之后减数分裂的M-阶段中的细胞周期抑制
时期。然后，第二波磷酸酶活动则充当进入有丝分裂的一个通道。（Letters
pp. 336, 341; News & Views）


让干细胞具有多功能性的方法（Laying down a marker for stem cells）
Generation of functional multipotent adult stem cells from GPR125+
germline progenitors
成年干细胞是代替胚胎干细胞用于治疗目的的一个很吸引人的替代物。虽然目前
还没有从成年个体获取这种细胞、并诱导它们形成不同组织的标准方法，但能从
成年个体睾丸中产生大量干细胞的一个新体系为我们带来了希望。这个新体系利
用一种新颖的标记物，一个被称为GPR125的器官受体，存在于精原干细胞表面
上。用专门的饲养细胞（feeder cells）来支持干细胞生长，可以使曾经用来生
成精子的干细胞变成多功能细胞。这项工作还为了解成年细胞产生多功能性所需
满足的最低要求提供了重要线索。（Letter p. 346）


干细胞同先祖细胞如何区分（Stem cells go up a Notch）
Differential Notch signalling distinguishes neural stem cells from
intermediate progenitors
关于大多数干细胞体系中存在不同增殖细胞类型的观点是被广泛接受的，但人们
对这些干细胞与受限制的“先祖亚集”（progenitor subsets）细胞之间的差别
却并不是很了解。现在，在约翰霍普金斯大学从事研究工作的一个小组发现了正
在发育中的小鼠脑中两个不同细胞类群（它们是“真正的”神经干细胞，是相似
的、但功能稍差的先祖细胞）之间是怎样区分的。干细胞分步成熟，逐渐脱去
“干细胞”属性。第一步是通过决定Notch（一种在很多组织中调控干细胞的蛋
白）下游的信号如何传输来将干细胞变成“先祖细胞”。然后，两个细胞类型分
化，这里的关键因素是一种Notch信号作用蛋白（被称为CBF1）是否是具有活性
的。CBF1信号通道在血液干细胞中起相同作用，所以它可能是一个将干细胞同先
祖细胞区分开来的通用“开关”。（Letter p. 351）


Integrin αvβ8是TGFβ的一个关键激发因子（Balancing the immune
forces）
Loss of integrin  v 8 on dendritic cells causes autoimmunity and
colitis in mice
在免疫响应的有益激发与免疫系统对正常组织的不失当攻击之间保持平衡，需要
多种抑制和平衡作用。Cytokine TGFβ (transforming growth factor-β)在这
样一种通道中是一个主要因子，充当适应性免疫的一个负调控因子，但一直不清
楚是什么激发TGFβ的，也不清楚哪些免疫细胞是其作用的关键。现在，
Integrin αvβ8被发现是TGFβ的一个关键激发因子；组织树状细胞上这种
Integrin的失去会激发TGFβ，后者又会诱导调控性T-细胞。在缺少这种通道
时，小鼠会出现自免疫，其结肠会发生严重炎症，类似于人类的溃疡性结肠炎。
（Letter p. 361）


胰岛素调控肝葡萄糖生产的一个通道（TORC2 and diabetes）
Insulin modulates gluconeogenesis by inhibition of the coactivator
TORC2
本期Nature 介绍了胰岛素调控肝葡萄糖生产的一个以前没有被发现的通道。在
哺乳动物体内，葡萄糖水平通过胰腺激素对肝脏的糖生成作用的效应而被维持在
一个很窄的范围内。这个新通道通过促进磷酸化和CREB共激发因子TORC2依赖于
泛素的降解来帮助胰岛素抑制糖生成基因的表达。这个信号作用通道涉及激酶
SIK2和E3连接酶COP1。这些发现表明，TORC2和SIK2在II-型糖尿病中是潜在的治
疗目标。（Letter p. 366）



----------------------
NEWS AND VIEWS
----------------------
Computing: The wireless epidemic pp287 - 288
As wireless communication technologies spread, so the potential for
viruses to exploit them grows. Biological models of virus transmission
will assume new relevance for assessing the emerging threat.
Jon Kleinberg
doi:10.1038/449287a
http://www.nature.com/nature/journal/v449/n7160/full/449287a.html

Ageing: From stem to stern pp288 - 291
Immortality is the stuff of myth and legend, but lifespan extension is
the subject of serious scientific inquiry. Exploring the causes and
effects of ageing in stem cells should aid this quest.
Anne Brunet and Thomas A. Rando
doi:10.1038/449288a
http://www.nature.com/nature/journal/v449/n7160/full/449288a.html

Palaeoanthropology: Homing in on early Homo pp291 - 292
Newly described fossils from Georgia in Eurasia and from Kenya shed
more light on the earliest members of the genus Homo. These finds
indicate that there was considerable variability in their size and
shape.
Daniel E. Lieberman
doi:10.1038/449291a
http://www.nature.com/nature/journal/v449/n7160/full/449291a.html

Catalysis: Raising the gold standard pp292 - 293
Gold is the current star of metal catalysis, but most gold catalysts
cannot control which mirror-image version of a molecule forms during a
reaction. The answer lies with the positive catalyst's negative
counter-ion.
A. Stephen K. Hashmi
doi:10.1038/449292a
http://www.nature.com/nature/journal/v449/n7160/full/449292a.html

Structural biology: Unexpected opening pp293 - 294
Cell membranes contain channels that open to allow ions into cells.
The structure of a sodium ion channel helps explain how it opens in
response to protons, and settles a long-standing debate about its
composition.
Cecilia M. Canessa
doi:10.1038/449293a
http://www.nature.com/nature/journal/v449/n7160/full/449293a.html

Geochemistry: Earth holds its breath pp294 - 296
Some inert-gas isotopes in Earth's atmosphere can only have come from
deep inside the planet. We thought we knew how much gas Earth gives
up, and how it does it ― but a challenge has emerged to the
prevailing model.
Chris J. Ballentine
doi:10.1038/449294a
http://www.nature.com/nature/journal/v449/n7160/full/449294a.html

Condensed-matter physics: Relaxation after a tight squeeze pp296
- 297
Are the rules that determine relaxation to equilibrium the same in the
classical and quantum worlds? Recent experiments supported the idea
that they are ― but an investigation with ultracold atoms now
contradicts that.
Ehud Altman and Eugene Demler
doi:10.1038/449296a
http://www.nature.com/nature/journal/v449/n7160/full/449296a.html

Fertilization: Calcium's double punch pp297 - 298
Fertilization promotes a calcium surge necessary to ensure the success
of embryonic development. It seems that calcium activates apparently
opposite molecular signalling pathways to achieve that end.
Catherine Jessus and Olivier Haccard
doi:10.1038/449297a
http://www.nature.com/nature/journal/v449/n7160/full/449297a.html

----------------------
ARTICLES
----------------------
40Ar retention in the terrestrial planets pp299 - 304
It is thought that the abundance of 40Ar in the atmosphere represents
the time-integrated loss of gases from the interior through partial
melting in the mantle followed by melt ascent to the surface and gas
exsolution. But data now presented reveal two major difficulties with
this simple magmatic degassing scenario: that argon is compatible in
the major phases of the terrestrial planets and that argon diffusion
in these phases is slow at upper-mantle conditions.
E. Bruce Watson, Jay B. Thomas and Daniele J. Cherniak
doi:10.1038/nature06144
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06144.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06144.html

Postcranial evidence from early Homo from Dmanisi, Georgia pp305
- 310
The primitive hominins from Dmanisi in the Republic of Georgia are
often thought to be akin to Homo erectus and are arguably the earliest
known members of the human family outside Africa. This conclusion has
come, so far, from the presentation of postcranial material: now a
partial skeleton of an adolescent individual associated with a skull,
and remains from three adult individuals, suggest that the Dmanisi
hominids are even more primitive than that, akin to Homo habilis.
David Lordkipanidze et al.
doi:10.1038/nature06134
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06134.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06134.html

Structural insight into filament formation by mammalian septins pp311
- 315
This paper reports the first crystal and electron microscopy structure
of an individual septin and a heteromeric complex as well as linear
septin filaments. The structure reveals that the G domain, which is
conserved amongst all septins, serves as a universal building block
for formation of a polymer. This domain interacts with other septins
via conserved residues.
Minhajuddin Sirajuddin et al.
doi:10.1038/nature06052
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06052.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06052.html

Structure of acid-sensing ion channel 1 at 1.9 A resolution and low
pH pp316 - 323
Acid-sensing ion channels belong to a large family of ion channels,
the diverse functions of which range from sodium absorption to
mechanosensitivity; however, the structure of this class of proteins
is unknown. Here, the high-resolution crystal structure of chicken
ASIC1 in the closed state is reported, and of note is the trimeric
architecture and the appealing mechanism of proton-gating proposed.
Jayasankar Jasti, Hiroyasu Furukawa, Eric B. Gonzales and Eric Gouaux
doi:10.1038/nature06163
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06163.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06163.html

----------------------
LETTERS
----------------------
Non-equilibrium coherence dynamics in one-dimensional Bose
gases pp324 - 327
This paper reports a direct experimental study of the coherence
dynamics in both isolated and coupled degenerate one-dimensional (1D)
Bose gases. Completely isolated 1D Bose gases exhibit coherence decay
in excellent agreement with recent predictions. The coherence of two
coupled 1D Bose gases decays to a finite value, analogous to the phase
locking of two lasers by injection.
S. Hofferberth et al.
doi:10.1038/nature06149
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06149.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06149.html

Generating single microwave photons in a circuit pp328 - 331
An on-chip, on-demand efficient source of single microwave photons
that can be used for processing quantum information in a circuit of
superconducting qubits is demonstrated. The single photon source is an
important addition to a rapidly growing toolbox for quantum optics on
a chip.
A. A. Houck et al.
doi:10.1038/nature06126
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06126.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06126.html

Increased terrestrial methane cycling at the Palaeocene-Eocene thermal
maximum pp332 - 335
It has been suggested that high-latitude methane emissions from
terrestrial environments could have enhanced a period of global
warming about 55 million years ago. A decrease in the carbon isotope
values of hopanoids (a biomarker derived from bacteria) at the onset
of the warm period is reported, which suggests an increase in
methanotroph populations . This could reflect an increase in methane
production and release from the terrestrial biosphere, which could
have acted as a positive feedback mechanism in global warming.
Richard D. Pancost et al.
doi:10.1038/nature06012
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06012.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06012.html

Calcineurin is required to release Xenopus egg extracts from meiotic M
phase pp336 - 340
One of two papers that identify a new pathway by which calcium
triggers oocyte fertilization. Previous work has shown a critical role
for the calcium-regulated kinase CaMKII. But new work from the Ohsumi
and Hunt laboratories shows that, in parallel, calcium-mediated
transient activation of a phosphatase, calcineurin, is needed to
release oocytes from a cell cycle arrest after fertilization. The Hunt
group also identifies a second wave of phosphatase activity that acts
in mitosis.
Satoru Mochida and Tim Hunt
doi:10.1038/nature06121
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06121.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06121.html

Transient activation of calcineurin is essential to initiate embryonic
development in Xenopus laevis pp341 - 345
One of two papers that identify a new pathway by which calcium
triggers oocyte fertilization. Previous work has shown a critical role
for the calcium-regulated kinase CaMKII. But new work from the Ohsumi
and Hunt laboratories shows that in parallel, calcium-mediated
transient activation of a phosphatase, calcineurin, is needed to
release oocytes from a cell cycle arrest after fertilization.
Tomoko Nishiyama, Norio Yoshizaki, Takeo Kishimoto and Keita Ohsumi
doi:10.1038/nature06136
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06136.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06136.html

Generation of functional multipotent adult stem cells from GPR125+
germline progenitors pp346 - 350
Adult stem cells are an ethically attractive alternative to embryonic
stem cells for obtaining tissues for therapeutic purposes. However, no
standardized methods exist to obtain such cells reliably from adults,
and then convert them into different tissues. However, a system has
been developed to generate large numbers of stem cells from the adult
testicle, based on the presence of a novel marker (GPR125),
specifically on the stem cell surface.
Marco Seandel et al.
doi:10.1038/nature06129
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06129.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06129.html

Differential Notch signalling distinguishes neural stem cells from
intermediate progenitors pp351 - 355
Two populations of cells from the telencephalic ventricular zone of
the developing brain, the neural stem cells and neuroblasts, display
differences in Notch signalling and could be sorted prospectively on
the basis of this heterogeneity.
Ken-ichi Mizutani et al.
doi:10.1038/nature06090
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06090.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06090.html

ZEITLUPE is a circadian photoreceptor stabilized by GIGANTEA in blue
light pp356 - 360
In Aradopsis, rhythmic expression of the F-box protein, ZEITLUPE
(ZTL), is necessary to sustain a normal circadian period, but the
mechanism of this oscillation is unknown. GIGANTEA (GI), a protein
previously implicated in the circadian clock, but with unknown
molecular function, is essential to establish and sustain oscillations
of ZTL by direct protein-protein interactions. Furthermore, this
stabilization is modulated by light through the N-terminal
flavin-binding LIGHT, OXYGEN OR VOLTAGE (LOV) domain of ZTL.
Woe-Yeon Kim et al.
doi:10.1038/nature06132
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06132.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06132.html

Loss of integrin αvβ8 on dendritic cells causes autoimmunity and
colitis in mice pp361 - 365
It is shown that mice deficient for β8 integrin develop colitis, and
that β8 needs to be expressed by dendritic cells rather than T cells
for colitis to develop. In addition, a decrease of T cells in the gut
but not adjacent lymph nodes in diseased animals is shown. It is
concluded that αVβ8-mediated integrin activation of dendritic cells
is essential for prevention of colitis-inducing immune dysfunction.
Mark A. Travis et al.
doi:10.1038/nature06110
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06110.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06110.html

Insulin modulates gluconeogenesis by inhibition of the coactivator
TORC2 pp366 - 369
Insulin inhibits expression of gluconeogenic genes by promoting the
phosphorylation and ubiquitin-dependent degradation of the CREB
coactivator TORC2. The signalling pathway involves the kinase SIK2 and
the E3 ligase COP1.
Renaud Dentin et al.
doi:10.1038/nature06128
Abstract:
http://www.nature.com/nature/journal/v449/n7160/abs/nature06128.html
Article:
http://www.nature.com/nature/journal/v449/n7160/full/nature06128.html
 
    
 


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