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ningkeqing

木虫 (正式写手)

[交流] Nature Contents 25 May 2006 (Vol. 441 pp.383-548)

[自然要览]

(选自英国Nature杂志,2006年5月25日出版)


封面故事:抑制癌变干细胞而保护造血干细胞的药物
Pten dependence distinguishes haematopoietic stem cells from
leukaemia-initiating cells/ PTEN maintains haematopoietic stem cells and
acts in lineage choice and leukaemia prevention
能引发和维持癌症的干细胞非常像正常细胞,以至于难以设计专门针对癌症的药物来。
这是一个严重的问题,因为举例来说,在白血病治疗期间受损的血液干细胞能造成造血
机能丧失,甚至导致患者死亡。现在,对肿瘤抑制因子PTEN(在白血病和其他癌症中经
常是没有活性的)所做的一项研究,发现了正常干细胞与癌变干细胞在自我更新上的一
大差别。PTEN正常情况下抑制磷脂酰肌醇-3-OH激酶信号通道,限制细胞增殖和存活。
在没有PTEN时,白血病干细胞能够增殖,但正常干细胞被耗尽。这说明,能够模仿PTEN
的药物也许能够抑制白血病,而不会伤害血液干细胞。事实上,在缺失Pten的小鼠身
上,雷帕霉素(Rapamycin)能杀死白血病干细胞,但却能保护血液干细胞的功能。另
一项研究证实了PTEN在调控血液干细胞中所起的作用。(Article p.475; Letter
p.518; News and Views)本期封面图片为在组织培养中由一个缺失Pten的造血干细胞
形成的一组血液细胞。


GRB在银河系中比较少见(Not in our back yard)
Long  -ray bursts and core-collapse supernovae have different environments
在其死亡的阵痛中,巨型恒星经常产生超新星,偶尔还会产生持续时间很长的伽马射线
暴(GRB)。这说明,GRB和超新星应能在类似环境中找到,但以“哈勃太空望远镜”
1000小时以上的观测结果为依据所做的研究表明,这种期待是错误的。大多数持续时间
很长的GRB存在于很小的、暗淡的、不规则的星系中。超新星在螺旋星系和不规则星系
之间似乎是等分的。GRB集中在它们主星系中最亮的部分,在那里超新星在其整个主星
系中都出现。该发现一个让人高兴的结论是,GRB在银河系中相对较少见,如果它们在
我们附近爆炸的话会在地球上造成灾难。(Article p. 463)


动物也有副突变现象(Paramutation in mice)
RNA-mediated non-mendelian inheritance of an epigenetic change in the mouse
副突变(Paramutation)首次于上个世纪50年代在玉米中被发现,后在其他植物和真菌
中被发现,它是一种不符合法则的遗传形式。大多数情况下,孟德尔的遗传定律(该定
律认为基因对中的等位基因独立遗传)都是对的。但副突变是具有同一位点的两个等位
基因之间的相互作用,它导致其中一个等位基因发生一个可遗传的变化。现在,这种类
型的非孟德尔遗传已在一种动物中被发现。在对小鼠的Kit基因进行研究的过程中,研
究人员发现,在与无效突变体杂交之后,野生型表现型没有得到充分表达。Kit+/Kit+
基因型事实上是按预料中的频率生成的,但由于副突变,它们中大多数仍然有白点突变
体表现型。这种外成(独立于DNA的)遗传的机制涉及配子与合子之间的RNA转移。RNA
是这方面的一个关键成分,它参与了植物的各种不同类型的外成遗传,作为遗传信息的
存储地点,或作为起调控作用的“微RNA”(microRNA)。(Article p. 469; News
and Views)


研究磁现象的新技术——EMCD(EM with a twist)
Detection of magnetic circular dichroism using a transmission electron
microscope
目前已经是一种功能强大的研究仪器的电子显微镜,随着“磁园二色性”(MCD)被发
现能够用传统透射电子显微镜探测到,它的功能还可能变得更强大。如果在施加一个磁
场的情况下左、右圆偏振光的吸收有所不同,材料就会显示“磁园二色性”。利用同步
加速器X-射线光子产生的这种效应的应用,是研究磁现象的一个强大工具。名为EMCD
(energy loss magnetic chiral dichroism)的新技术利用X-射线吸收与无弹性电子
散射之间的相似性来实现昂贵的同步加速器通常才具有的TEM功能。EMCD在包括自旋电
子学和纳米磁学在内的很多领域都可能有用。(Letter p. 486)


有望成为高性能FET的新型锗/硅纳米线(Outperforming silicon)
Ge/Si nanowire heterostructures as high-performance field-effect transistors
以半导体纳米线为基础的场效应晶体管(FET)有一天可能会取代微型电路中标准的硅
MOSFET(金属氧化物半导体场效应晶体管)。 MOSFET是用于高速切换和电脑集成电路中
的一种普及型的晶体管。一种专门设计的、具有锗外壳和硅内核的纳米线,有希望成为
一种纳米尺度的场效应晶体管:它有一个近乎完美的导电通道。现在,在半导体配置
中,这种锗/硅纳米线表现出了包括电导高和切换时间延迟短在内的性能,这些性能优
于最新硅MOSFET材料。(Letter p. 489)


海洋中水下火山喷发的直接观测(Bubbling under)
Long-term eruptive activity at a submarine arc volcano
地球火山活动的四分之三在海洋底下。我们很少知道火山在什么时候和什么地方喷发,
大多数观测结果都是间接的,是由表面船只获得的,或是在喷发之后获得的。现在,
Embley等人报告了对位于关岛东北的北马里亚纳群岛中的一个水下弧形火山的一次正在
进行中的喷发所做的直接观测和取样研究结果。遥控的潜水装置首次被用来在540米的
深度处、在一个最近被测绘出的水下火山的最高峰附近识别一个由喷发形成的热液柱。
之后,研究人员又在2004年3/4月和2005年10月对火山活动进行了监测。长期喷发活动
形成了一个不寻常的化学环境和一个也许是活的弧形和热点火山所特有的生态系统。
(Letter p. 494)


与人为善于己方便(Your cheating art)
Resource competition and social conflict in experimental populations of
yeast/ A simple rule for the evolution of cooperation on graphs and social
networks
演化,尤其是合作行为的维持,需要做一些解释。合作群体会被自私地利用共同资源的
“骗子”所葬送,大量理论预测,骗子通常会取代合作者。但对为什么欺骗并不总能大
行其道所做的一个可能的解释,来自酵母菌种之间的竞争实验。实验所用的酵母菌种既
表现为合作者,也表现为欺骗者,相互之间竞争葡萄糖,并有效地或自私地利用它。实
验结果表明,两个策略能够共存,因为两个策略都与代价和利益相联系。进行欺骗是有
代价的,在该实验中这种代价就是欺骗者所产生的后代少于对手。(Letter p. 498)
Ohtsuki等人在对由一个曲线上的点构成的有层次的“虚拟”种群的演化动态所做的一
项研究中,用图形方式显示了自然选择会支持合作。如果无私行为的利益被代价所除的
结果超过邻居的平均数量的话,合作就会受到支持。所以,即使在没有声誉效应或策略
复杂性的情况下,合作也能作为这种“社会凝聚性”的一个结果而演化和发展。
(Letter p. 502)


海蜘蛛头上已不再长脚(Talking heads)
Homology of arthropod anterior appendages revealed by Hox gene expression in
a sea spider
螃蟹、昆虫、蜘蛛和其他节肢动物提供了一个很好的事例,让我们了解演化何以能从单
一物种产生不同身体形式。它们都由一段一段的头部和躯干组成,每种都有不同附肢,
如螯、触角、翅膀和腿等。Nature杂志最近发表的一篇论文提出一个新的假设,来解释
一些明显的异常现象。该论文提出,让人好奇的节肢动物海蜘蛛甚至在第一个头部段就
有附肢,从而为我们提供了一个联系节肢动物祖先的线索。这项研究工作所依据的是神
经解剖证据,但现在,Jager等人利用分子技术所做的研究表明,同其他所有现存的节
肢动物一样,海蜘蛛也失去了在化石中所看到的第一个头部段的附肢。(Letter p.
506)


Wolbachia的寄生环境(A niche fit for Wolbachia)
Somatic stem cell niche tropism in Wolbachia
Wolbachia是非常成功的细胞内寄生虫。它们存在于多数节肢动物体内,也因有可能成
为控制疟疾的工具而成为新闻,它们的转基因变种有可能阻止疟原虫在蚊子中成熟。同
线粒体一样,这些细菌也是由母亲传播的。它们还在物种之间横向传播,但对其中所涉
及的细胞机制我们却知之甚少。现在Frydman等人报告,Wolbachia能跨过组织障碍到达
生殖细胞。在新发生的或遗传的感染中,它们喜欢寄居在果蝇卵巢的体干细胞中。这种
干细胞环境似乎是感染生殖细胞的细菌的一个聚居地。(Letter p. 509)


shRNA在活体中有很强毒性(Adverse reaction to shRNA)
Fatality in mice due to oversaturation of cellular microRNA/short hairpin
RNA pathways
虽然尚处在初期阶段,但RNA干涉(RNAi)已经被看作是一种用来沉寂基因的具有潜在
重要性的治疗方法。在活体中输送“短干涉RNA”(siRNA)的一种办法是,将siRNA序
列作为“短发夹”克隆进一种腺病毒载体中。当送入动物体内时,该发夹序列被表达出
来,形成一个“双链RNA”(shRNA),并被RNAi通道处理。然而,对成年小鼠肝脏中
shRNA的表达的长期效应所做的一项研究为我们敲响了警钟。该研究结果表明,很多
shRNA在小鼠中表达时是有毒的。这种经常是致命的毒性似乎是由shRNA与内生微RNA之
间为与Exportin-5结合所展开的竞争造成的。Exportin-5是一个参与将分子输送出细胞
核的因子。人们对开发基于shRNA的疗法非常感兴趣,而此前几乎没有证据表明shRNA在
活体中有很强毒性。(Letter p. 537)
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ningkeqing

木虫 (正式写手)

----------------------
NEWS AND VIEWS
----------------------
Social sciences: A New World of differences For richer, for poorer — the
countries of the Americas and those of the Caribbean present stark contrasts
in fortune. An explanation of those contrasts invokes branching chains of
cause and effect.
Shaun Miller and Jared Diamond
http://www.nature.com/nature/journal/v441/n7092/full/441411a.html

Genetics: Paramutable possibilities
A curious genetic phenomenon allows certain genetic instructions to be
passed between generations without the gene variants involved being
transmitted. Some spotty mice provide clues to how this might happen.
Paul D. Soloway
http://www.nature.com/nature/journal/v441/n7092/full/441413a.html

Nanomaterials: Display of flexibility
Treated the right way, carbon nanotubes can be moulded into large, flexible
electron-emitting sheets. The material is one half of what's needed for an
electronic display you could fold up and slip in your pocket.
Laszlo Forro
http://www.nature.com/nature/journal/v441/n7092/full/441414a.html

Immunology: Adaptable innate killers
Natural killer cells are versatile white blood cells that act in the innate
immune system. Quite how adaptable they can be in the absence of other, more
specialized, immune cells comes as a surprise.
Peter Parham
http://www.nature.com/nature/journal/v441/n7092/full/441415a.html

Meteoritics: How to make a chondrule
Chondrules, the stony, seed-like grains in meteorites, were formed when some
event melted rock in the solar nebula. The latest analyses narrow the
possible ‘when’, ‘where’ and ‘how’ of that process.
Steve Desch
http://www.nature.com/nature/journal/v441/n7092/full/441416a.html

Ecology: Paradox of the clumps
A fresh look at an established model in ecology has generated insights into
how species coexist with each other. But it has also raised a vexed
question: what constitutes the ecological identity of species?
Sean Nee and Nick Colegrave
http://www.nature.com/nature/journal/v441/n7092/full/441417a.html

Materials science: Film review
Maria Bellantone
http://www.nature.com/nature/journal/v441/n7092/full/441418a.html

Stem cells: Good, bad and reformable
The ability of stem cells to continuously supply vast numbers of cells is
magnificent, but it can be devastating if it runs amok, as in some tumours.
So what makes a normal stem cell turn bad, and can it be redeemed?
Viktor Janzen and David T. Scadden
http://www.nature.com/nature/journal/v441/n7092/full/441418b.html

----------------------
BRIEF COMMUNICATIONS
----------------------
Ecology: Avoidance of disease by social lobsters These gregarious animals
shun lobsters that carry a lethal virus, even when they still seem to be
healthy.
Donald C. Behringer, Mark J. Butler and Jeffrey D. Shields
Abstract: http://www.nature.com/nature/journal/v441/n7092/abs/441421a.html
Article: http://www.nature.com/nature/journal/v441/n7092/full/441421a.html

BRIEF COMMUNICATIONS ARISING
Correspondence patterns: Mechanisms and models of human dynamics Alex
Kentsis
Abstract:
http://www.nature.com/nature/jou ... bs/nature04901.html
Article:
http://www.nature.com/nature/jou ... ll/nature04901.html

Correspondence patterns: Mechanisms and models of human dynamics (Reply) J.
G. Oliveira and A.-L. Barabasi
Abstract:
http://www.nature.com/nature/jou ... bs/nature04902.html
Article:
http://www.nature.com/nature/jou ... ll/nature04902.html

----------------------
INSIGHT
----------------------
INTRODUCTION
Signalling in cancer
Alex Eccleston and Ritu Dhand
http://www.nature.com/nature/journal/v441/n7092/full/441423a.html

REVIEW ARTICLE
Ras, PI(3)K and mTOR signalling controls tumour cell growth Reuben J. Shaw
and Lewis C. Cantley
Abstract:
http://www.nature.com/nature/jou ... bs/nature04869.html
Article:
http://www.nature.com/nature/jou ... ll/nature04869.html

Nuclear factor-κB in cancer development and progression Michael Karin
Abstract:
http://www.nature.com/nature/jou ... bs/nature04870.html
Article:
http://www.nature.com/nature/jou ... ll/nature04870.html

Hypoxia signalling in cancer and approaches to enforce tumour regression
Jacques Pouyssegur, Frederic Dayan and Nathalie M. Mazure
Abstract:
http://www.nature.com/nature/jou ... bs/nature04871.html
Article:
http://www.nature.com/nature/jou ... ll/nature04871.html

New signals from the invasive front
Gerhard Christofori
Abstract:
http://www.nature.com/nature/jou ... bs/nature04872.html
Article:
http://www.nature.com/nature/jou ... ll/nature04872.html

REVIEW ARTICLE
Validating cancer drug targets
John D. Benson, Ying-Nan P. Chen, Susan A. Cornell-Kennon, Marion Dorsch,
Sunkyu Kim, Magdalena Leszczyniecka, William R. Sellers and Christoph
Lengauer
Abstract:
http://www.nature.com/nature/jou ... bs/nature04873.html
Article:
http://www.nature.com/nature/jou ... ll/nature04873.html

REVIEW ARTICLE
Mechanisms of drug inhibition of signalling molecules Judith S.
Sebolt-Leopold and Jessie M. English
Abstract:
http://www.nature.com/nature/jou ... bs/nature04874.html
Article:
http://www.nature.com/nature/jou ... ll/nature04874.html

----------------------
ARTICLES
----------------------
Long γ-ray bursts and core-collapse supernovae have different environments
γ-ray bursts are more concentrated in the very brightest regions of their
host galaxies than are supernovae -- in addition, the host galaxies of the
γ-ray bursts are significantly fainter and more irregular than the hosts of
the supernovae.
A. S. Fruchter et al.
Abstract:
http://www.nature.com/nature/jou ... bs/nature04787.html
Article:
http://www.nature.com/nature/jou ... ll/nature04787.html

RNA-mediated non-mendelian inheritance of an epigenetic change in the mouse
Minoo Rassoulzadegan, Valérie Grandjean, Pierre Gounon, Stéphane Vincent,
Isabelle Gillot and Fran?ois Cuzin
Abstract:
http://www.nature.com/nature/jou ... bs/nature04674.html
Article:
http://www.nature.com/nature/jou ... ll/nature04674.html

Pten dependence distinguishes haematopoietic stem cells from
leukaemia-initiating cells The tumour suppressor PTEN is required for
maintenance of haematopoietic stem cells, but not leukaemia-initiating cells
-- this specific effect is mediated by the mTOR pathway and mitigated by
rapamycin.
?mer H. Yilmaz, Riccardo Valdez, Brian K. Theisen, Wei Guo, David O.
Ferguson, Hong Wu and Sean J. Morrison
Abstract:
http://www.nature.com/nature/jou ... bs/nature04703.html
Article:
http://www.nature.com/nature/jou ... ll/nature04703.html
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ningkeqing

木虫 (正式写手)

----------------------
LETTERS
----------------------
Chondrule formation in particle-rich nebular regions at least hundreds of
kilometres across A model in which molten chondrules come to equilibrium
with the gas that was evaporated from other chondrules explains why
chondrules are depleted in volatile elements, but surprisingly show little
evidence for the associated loss of lighter isotopes one would expect.
Jeffrey N. Cuzzi and Conel M. O'D. Alexander
Abstract:
http://www.nature.com/nature/jou ... bs/nature04834.html
Article:
http://www.nature.com/nature/jou ... ll/nature04834.html

Detection of magnetic circular dichroism using a transmission electron
microscope Comparison of measurements of electron energy-loss magnetic
chiral dichroism with X-ray magnetic circular dichroism spectra obtained
from the same specimen, together with theoretical calculations, show that
chiral atomic transitions in a specimen are accessible with inelastic
electron scattering under particular scattering conditions.
P. Schattschneider, S. Rubino, C. Hebert, J. Rusz, J. Kunes, P. Novák, E.
Carlino, M. Fabrizioli, G. Panaccione and G. Rossi
Abstract:
http://www.nature.com/nature/jou ... bs/nature04778.html
Article:
http://www.nature.com/nature/jou ... ll/nature04778.html

Ge/Si nanowire heterostructures as high-performance field-effect transistors
In a transistor configuration, a new germanium/silicon nanowire has
characteristics such as conductance, on-current and switching time delay
that are better than those of state-of-the-art silicon
metal-oxide-semiconductor field-effect transitors.
Jie Xiang, Wei Lu, Yongjie Hu, Yue Wu, Hao Yan and Charles M. Lieber
Abstract:
http://www.nature.com/nature/jou ... bs/nature04796.html
Article:
http://www.nature.com/nature/jou ... ll/nature04796.html

Long-term eruptive activity at a submarine arc volcano Direct observations
and sampling of an active eruption at a submarine arc volcano determines
that long-term eruptive activity has produced an unusual chemical
environment and an ecosystem perhaps distinctive of active arc and hotspot
volcanoes.
Robert W. Embley, William W. Chadwick, Jr, Edward T. Baker, David A.
Butterfield, Joseph A. Resing, Cornel E.J. de Ronde, Verena Tunnicliffe,
John E. Lupton, S. Kim Juniper, Kenneth H. Rubin, Robert J. Stern, Geoffrey
T. Lebon, Ko-ichi Nakamura, Susan G. Merle, James R. Hein, Douglas A. Wiens
and Yoshihiko Tamura
Abstract:
http://www.nature.com/nature/jou ... bs/nature04762.html
Article:
http://www.nature.com/nature/jou ... ll/nature04762.html

Resource competition and social conflict in experimental populations of
yeast Yeast strains that behave as cooperators and cheaters when competing
for a common resource can stably coexist, because both strategies are
associated with costs and benefits.
R. Craig MacLean and Ivana Gudelj
Abstract:
http://www.nature.com/nature/jou ... bs/nature04624.html
Article:
http://www.nature.com/nature/jou ... ll/nature04624.html

A simple rule for the evolution of cooperation on graphs and social networks
Natural selection generally favours cooperation if the benefit of the
altruistic act divided by the cost exceeds the average number of neighbours,
indicating that cooperation can evolve as a consequence of /`social
viscosity/', even in the absence of reputation effects or strategic
complexity.
Hisashi Ohtsuki, Christoph Hauert, Erez Lieberman and Martin A. Nowak
Abstract:
http://www.nature.com/nature/jou ... bs/nature04605.html
Article:
http://www.nature.com/nature/jou ... ll/nature04605.html

Homology of arthropod anterior appendages revealed by Hox gene expression in
a sea spider Muriel Jager, Jerome Murienne, Céline Clabaut, Jean Deutsch,
Hervé Le Guyader and Micha?l Manuel
Abstract:
http://www.nature.com/nature/jou ... bs/nature04591.html
Article:
http://www.nature.com/nature/jou ... ll/nature04591.html

Somatic stem cell niche tropism in Wolbachia Wolbachia migrate through
several tissues and reach the germ line of their arthropod hosts through the
somatic stem cell niche during horizontal transmission. In addition, a high
abundance of bacteria in this niche suggests that this location may also
contribute to efficient vertical transmission.
Horacio M. Frydman, Jennifer M. Li, Drew N. Robson and Eric Wieschaus
Abstract:
http://www.nature.com/nature/jou ... bs/nature04756.html
Article:
http://www.nature.com/nature/jou ... ll/nature04756.html

S-Nitrosylated protein-disulphide isomerase links protein misfolding to
neurodegeneration Takashi Uehara, Tomohiro Nakamura, Dongdong Yao,
Zhong-Qing Shi, Zezong Gu, Yuliang Ma, Eliezer Masliah, Yasuyuki Nomura and
Stuart A. Lipton
Abstract:
http://www.nature.com/nature/jou ... bs/nature04782.html
Article:
http://www.nature.com/nature/jou ... ll/nature04782.html

PTEN maintains haematopoietic stem cells and acts in lineage choice and
leukaemia prevention Jiwang Zhang, Justin C. Grindley, Tong Yin, Sachintha
Jayasinghe, Xi C. He, Jason T. Ross, Jeffrey S. Haug, Dawn Rupp, Kimberly S.
Porter-Westpfahl, Leanne M. Wiedemann, Hong Wu and Linheng Li
Abstract:
http://www.nature.com/nature/jou ... bs/nature04747.html
Article:
http://www.nature.com/nature/jou ... ll/nature04747.html

Identification of a tumour suppressor network opposing nuclear Akt function
Lloyd C. Trotman, Andrea Alimonti, Pier Paolo Scaglioni, Jason A. Koutcher,
Carlos Cordon-Cardo and Pier Paolo Pandolfi
Abstract:
http://www.nature.com/nature/jou ... bs/nature04809.html
Article:
http://www.nature.com/nature/jou ... ll/nature04809.html

GTP-dependent twisting of dynamin implicates constriction and tension in
membrane fission Dynamic light microscopy imaging of dynamin-coated lipid
tubules revealed a GTP hydrolysis-dependent twisting activity -- the
constricting activity produced by this twisting led to fission only when
coupled to the longitudinal tension of the tubules.
Aurélien Roux, Katherine Uyhazi, Adam Frost and Pietro De Camilli
Abstract:
http://www.nature.com/nature/jou ... bs/nature04718.html
Article:
http://www.nature.com/nature/jou ... ll/nature04718.html

Rec8 phosphorylation and recombination promote the step-wise loss of
cohesins in meiosis Gloria A. Brar, Brendan M. Kiburz, Yi Zhang, Ji-Eun Kim,
Forest White and Angelika Amon
Abstract:
http://www.nature.com/nature/jou ... bs/nature04794.html
Article:
http://www.nature.com/nature/jou ... ll/nature04794.html

Fatality in mice due to oversaturation of cellular microRNA/short hairpin
RNA pathways Many short hairpin RNAs (shRNAs) are toxic when expressed in
mice -- this is traced to possible competition between the shRNAs and
endogenous microRNAs for binding to exportin-5, a factor involved in
transporting molecules out of the nucleus.
Dirk Grimm, Konrad L. Streetz, Catherine L. Jopling, Theresa A. Storm, Kusum
Pandey, Corrine R. Davis, Patricia Marion, Felix Salazar and Mark A. Kay
Abstract:
http://www.nature.com/nature/jou ... bs/nature04791.html
Article:
http://www.nature.com/nature/jou ... ll/nature04791.html
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