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2007年11月1日Nature中文摘要
 BIOX.CN  来源：生命经纬    2007年11月01日
封面故事： 对神经细胞进行染色的新方法
Transgenic strategies for combinatorial expression of fluorescent
proteins in the nervous system
一个多世纪以前，Ramón Y Cajal利用高尔基神经细胞染色打开了现代神经生物
学的大门：通过对少量神经细胞进行染色，以前看不见的轴突和树突在其通过周
围组织时就可以被看到。但高尔基染色只能以一种颜色标记少量细胞。现在，来
自哈佛大学的一个小组开发出一种方法，该方法能够使一个脑回中的很多不同细
胞同时被看到。这种被称为“Brainbow”的方法可用不同颜色对数百个神经细胞
各自染色，从而生成一个详细的神经回路图。该技术不仅能推动在正常或病态脑
中的测绘工作，而且还有可能应用到其他复杂细胞群中，如免疫系统中。本期封
面所示为用“Brainbow”方法染色的小鼠海马体的一部分。齿状回（下部）的多
颜色神经细胞在拱形的CA1区域的细胞下面，而大脑皮质的神经细胞可以看到在
上面闪动。（Article p. 56; www.nature.com/podcast）


科学知识与公共政策（PARTIALITY, SCIENCE AND POLICY）
Technologies of humility
虽然社会和政策制定者要求越来越多的科学证据，但Sheila Jassanoff希望大家
不要忽略科学知识的偏颇性，并且认为需要通过有约束的方法来适应这种无法解
决的不确定性。（Essay p. 33）


听觉系统的早期发育（First steps towards hearing）
The origin of spontaneous activity in the developing auditory system
在内耳能够探听到声音之前，发育中的听觉系统中就出现了电活动，这种自然的
活动是听觉神经细胞成熟所必需的，也是在大脑中建立听觉通道所必需的。这一
效应背后的机制已经在对大鼠耳蜗所做的一系列实验中被发现。K?lliker器官
（发育中的耳蜗内的一个短暂的上皮结构）中的支持细胞会自然释放ATP，激发
内耳毛细胞和听觉神经纤维。这种活动在听觉开始时停止，以使声音的探听不受
妨碍。这一通道的再激发有可能对“周围性耳鸣”（peripheral tinnitus）中
独立于感官的活性有贡献。（Article p. 50; News & Views）


对蛔虫神经回路的研究（Circuit training）
Dissecting a circuit for olfactory behaviour in Caenorhabditis elegans
蛔虫Caenorhabditis elegans的神经系统只有302个具有已知突触连接的神经细
胞，然而它却执行很多与更复杂的生物相似的功能。这使得它非常适合让神经科
学家来研究神经回路是怎样组织的。Chalasani等人对决定这种蛔虫一种觅食行
为的神经回路进行了解剖研究。该回路允许探测气味的神经元激发或抑制下游的
中间神经元（interneuron），它们控制一致的爬行和转身行为。将遗传学和钙
成像技术结合起来，可以对信息从环境中通过传感神经元向控制趋化性和觅食的
中间神经元的流动进行跟踪。这一神经回路与哺乳动物视网膜中用来探测光的神
经回路具有非常惊人的同源性，这是关于信息处理的保留策略或融合策略的一个
明显例子。（Article p. 63; News & Views）。


支持关于吸积盘的两个理论的观测证据（What goes round）
Circular polarimetry reveals helical magnetic fields in the young
stellar object HH 135–136 / The rotating wind of the quasar PG
1700+518
两个小组在本期Nature上发表了观测证据，它们支持关于相似天体物理问题的相
关理论，这些理论人们长期以来都认为是正确的，但却没有得到确认。这些理论
所涉及的问题是：来自吸积盘的角动量的消耗。当星际气体云在引力影响下坍缩
时恒星就会形成。当这些云开始坍缩时，由于角动量的守恒，任何转动都将被放
大，就像一个滑冰者旋转一样。如果不阻止，这种转动的速度将会太快，使得恒
星形成无法发生，理论工作者提出，年轻恒星会通过由磁场诱导的物质外流而损
失转动能量。现在有了观测结果来支持这一理论：Chrysostomou等人利用圆形偏
振测量法发现，在年轻恒星HH135-136的外流物中存在螺旋形磁场。（Letter p.
71）认为活动星系核外流源于来自一个超大黑洞周围的一个转动的吸积盘的盘风
的观点是有理论依据的。实践证明，这一观点的确认比较困难。现在，Young等
人利用光谱偏振测量断层扫描方法确定，类星体风事实上是在转动的。类星体PG
1700+158产生的风以大约每秒4,000公里的速度在旋转，几乎是从吸积盘上垂直
升起的。（Letter p. 74）


确定FPT性质的新方法（Mean first-passage times）
First-passage times in complex scale-invariant media
一个随机的步行者多长时间能到达一个给定的目标点？  这个数量（被称为“首
次穿越时间”，英文简称为FPT）因其在真实情形如紊乱媒介中的运输、神经激
发、疾病传播以及目标搜索等过程中所起作用而显得很重要。以前确定FPT性质
的方法仅限于一维几何或均匀媒介。Condamin等人建立了一种普适理论，它能允
许对复杂媒介中的平均FPT进行准确评估。该理论的预测结果被关于紊乱媒介、
碎形（fractals）、异常扩散和无尺度网络（包括一个酵母蛋白互动网络）的几
个模型的数值模拟结果所证实。（Letter p. 77, News & Views）


射频扫描隧道显微镜（STM now on radio）
Radio-frequency scanning tunnelling microscopy
扫描隧道显微镜（STM）是纳米科学中最有用的工具之一。但这一技术的一个严
重局限性是其时间分辨率。这个分辨率不是由隧道作用的基本物理决定的，而是
由传统隧道电流读出电路有限的高频响应决定的。射频STM（RF-STM）采用一种
特殊设计的射频测量电路来避免这些测量带宽限制，而且本期Nature报告的研究
工作表明，RF-STM能够将时间分辨率与最新STM相比提高100倍。该新型快速成像
仪器的实验演示表明，该技术适合三种潜在应用——快速表面形状研究、 纳米
尺度测温和纳米机械位移传感。（Letter p. 85）


火灾发生情况对森林地区碳平衡的影响（Fire tips the carbon balance）
Fire as the dominant driver of central Canadian boreal forest carbon
balance
气候、大气二氧化碳浓度和火灾频率的变化几十年来在高纬度（北半球北部）森
林中一直在发生。以前的研究工作没有将这些变化与植被竞争在大尺度上联系起
来，但一项新的研究工作利用一个计算机模型来模拟一百万平方公里的加拿大森
林中树木与苔藓之间的竞争。结果表明，在1948和2005年之间，这一地区的碳平
衡（土壤和植被获得或损失的碳的数量）在很大程度上是由火灾发生情况驱动
的，而不是由气候或二氧化碳浓度增加驱动的。二十世纪末更频繁和更大的火灾
以针叶树木为代价促进了落叶树木和苔藓的生长。较差的土壤排水条件抑制了景
观碳平衡的变化，说明气候和水文变化的增加会不成比例地影响这些地区的碳动
态。（Letter p. 89）


具有非常先进牙齿形状的动物化石（GOOD TEETH）
Convergent dental adaptations in pseudo-tribosphenic and tribosphenic
mammals
三尖齿或大臼齿似乎在哺乳动物身上演化过两次：一次是在有袋类和胎生动物的
后代身上，另一次是在其后代包括单孔类或卵生哺乳动物的一组哺乳动物身上。
来自内蒙古中侏罗纪地层的后一类的一个新标本的牙齿与其身体其余部分的原始
性质相比具有非常先进的形态。这显示了古代哺乳动物的多样性——这些化石层
还产生了一种海獭一样的会游泳的哺乳动物和一种极为古老的能滑翔的哺乳动
物。（Letter p. 93）


关于加勒比地区珊瑚礁状况的模型研究（REEFS IN PERIL）
Thresholds and the resilience of Caribbean coral reefs
加勒比地区很多珊瑚礁健康状况很差，这是因为发生了珊瑚的损失和大型海藻数
量的增加。Mumby等人通过模型研究发现，自从一种食草海胆在1983年大量死亡
以来，加勒比珊瑚礁抵抗影响的弹性普遍降低。现在，这些珊瑚礁预计对鹦鹉鱼
掠食高度敏感，但这一模型研究可帮助识别对草食性动物掠食和飓风损害的抵抗
力弹性最大的区域，并对珊瑚礁管理有重要意义。（Letter p. 98）


乐观倾向的神经基础（It’s looking good…）
Neural mechanisms mediating optimism bias
抑郁（经常以悲观倾向为特征）的神经基础已经受到了广泛研究。然而，关于乐
观的神经科学研究却是新事物。人类是非常乐观的物种，即使在没有根据的情况
下也总是期待会产生积极的结果。例如，我们期待自己比一般人寿命更长、更健
康，我们会低估自己遭遇车祸和离婚的可能性。一项将对健康的志愿者进行的脑
成像研究和行为研究结合起来的研究工作，为这一现象的神经机制提供了证据。
有趣的是，我们知道在抑郁症患者身上功能异常的大脑区域的活动也能预测乐观
倾向。（Letter p. 102）


植物和动物病原体的共同之处（Common entrance）
A translocation signal for delivery of oomycete effector proteins into
host plant cells
很多植物和动物病原体通过将毒性或效应子蛋白注射进宿主细胞中来逃避宿主免
疫系统。对真菌Phytophthora infestans（马铃薯枯萎病病原体）所做的一项研
究，在效应子蛋白中发现了一种保留下来的肽，它是效应子从被称为haustoria
的专门的感染结构向植物细胞中运动所需要的。这个序列（名叫RXLR-EER）最近
被报道说是疟疾寄生虫“镰刀形疟原虫”向人类红血球中转位所需要的。这些研
究说明，不同真核病原体可利用等价的定位信号来提供它们的效应子蛋白。
（Letter p. 115; News & Views）


组蛋白H3K9去甲基化酶与精子的生成和成熟（Fertility-linked demethylase）
Histone demethylase JHDM2A is critical for Tnp1 and Prm1 transcription
and spermatogenesis
过去科学家已经知道，组蛋白H3K9去甲基化酶JHDM2A在由雄性激素受体调控的转
录激发中扮演一个角色。现在对小鼠Jhdm2a基因的定向破坏表明，这种酶涉及精
子生成和转换核蛋白及鱼精蛋白基因的调控。这项工作表明，这种组蛋白去甲基
化酶在精子产生和成熟后期扮演一个角色，而且Jhdm2a成为尚未被完全确定性质
的不育症的一个可能的候选基因。（Letter p. 119）


----------------------
NEWS AND VIEWS
----------------------
Smell: The worm turns pp35 - 36
The worm Caenorhabditis elegans has many advantages as an experimental
organism. These have been exploited to investigate how, at a
single-neuron level, neural circuits transform sensory signals into
behaviour.
Piali Sengupta
doi:10.1038/450035a
http://www.nature.com/nature/journal/v450/n7166/full/450035a.html

Organic chemistry: Aromatics with a twist pp36 - 37
The properties of flat aromatic molecules are well known to chemists,
but some non-planar aromatics remain a mystery. A molecule that can
twist into a Moebius band on command might shed light on their
features.
Rainer Herges
doi:10.1038/450036a
http://www.nature.com/nature/journal/v450/n7166/full/450036a.html

Vision: Dynamic platforms pp37 - 39
Scaffolding proteins are so named because they function as platforms
for the assembly of molecular signalling complexes. But at least one
such protein is more than a passive bystander and has its own
signalling role.
Roger C. Hardie
doi:10.1038/450037a
http://www.nature.com/nature/journal/v450/n7166/full/450037a.html

Mathematical physics: First encounters pp40 - 41
The idea of 'random walks' pops up in areas from biochemical reaction
pathways to animals' foraging strategies. A central question ― how
likely is it that a walker is somewhere for the first time? ― now has
a simpler answer.
Michael F. Shlesinger
doi:10.1038/450040a
http://www.nature.com/nature/journal/v450/n7166/full/450040a.html

Plant pathology: Deadly special deliveries pp41 - 43
When attacking a plant, pathogens must deliver proteins into their
victim's cells. The causal agent of potato late blight uses a system
that is remarkably similar to that used by the malaria parasite in red
blood cells.
Nicholas J. Talbot
doi:10.1038/450041a
http://www.nature.com/nature/journal/v450/n7166/full/450041a.html

Hearing: A fantasia on Koelliker's organ pp43 - 44
In the silence that precedes the onset of hearing in the developing
auditory system, it seems that the cells of a transient structure
known as Koelliker's organ are capable of generating their own
'virtual' music.
Ian D. Forsythe
doi:10.1038/450043a
http://www.nature.com/nature/journal/v450/n7166/full/450043a.html

CORRESPONDENCE
Correction p44
doi:10.1038/450044a
http://www.nature.com/nature/journal/v450/n7166/full/450044a.html

----------------------
ARTICLES
----------------------
Patterns of relative species abundance in rainforests and coral
reefs pp45 - 49
Neutral theory, in which species do not interact, has been used to try
to understand the relative species abundance of tropical forests,
although its validity been questioned. A non-interacting theory with
similarities and differences to conventional neutral theory is
developed. The approach provides a unified and quantitatively accurate
description of relative species abundance data from both tropical
forests and coral reefs.
Igor Volkov, Jayanth R. Banavar, Stephen P. Hubbell and Amos Maritan
doi:10.1038/nature06197
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06197.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06197.html

The origin of spontaneous activity in the developing auditory
system pp50 - 55
Acoustic information is detected by inner hair cells in mammalian
cochlea and is transmitted to the brain via the auditory nerve. But
auditory nerve activity is evident before the cochlear machinery
develops the ability to process information. The mechanism that
underlies this effect has been uncovered in a series of experiments,
showing that supporting cells located in Koelliker's organ
spontaneously release ATP, activating inner hair cells and thus
auditory nerve fibres.
Nicolas X. Tritsch et al.
doi:10.1038/nature06233
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06233.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06233.html

Transgenic strategies for combinatorial expression of fluorescent
proteins in the nervous system pp56 - 62
A combination of genetic tricks and fancy fluorescent proteins is used
to develop the Technicolor version of Golgi staining, 'Brainbow', in
which hundreds of individual neurons are painted, each with a
distinctive hue. This technology should not only boost mapping efforts
in normal or diseased brains, but could also be applied to other
complex cell populations, such as the immune system.
Jean Livet et al.
doi:10.1038/nature06293
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06293.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06293.html

Dissecting a circuit for olfactory behaviour in Caenorhabditis
elegans pp63 - 70
A combination of genetics and calcium imaging is used to detail the
neuronal circuitry in Caenorhabditis elegans that allows odour-sensing
neurons to activate or inhibit downstream interneurons controlling
crawling and turning behaviours. The nerve cell connectivity and
molecules used by this nematode to process olfactory information shows
striking homologies with those used to sense light in mammalian retina
Sreekanth H. Chalasani et al.
doi:10.1038/nature06292
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06292.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06292.html

----------------------
LETTERS
----------------------
Circular polarimetry reveals helical magnetic fields in the young
stellar object HH 135-136 pp71 - 73
Antonio Chrysostomou, Philip W. Lucas and James H. Hough
doi:10.1038/nature06220
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06220.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06220.html

The rotating wind of the quasar PG 1700+518 pp74 - 76
Structures observed in polarized light across the broad Hα± emission
line in the quasar PG 1700+158 originate close to the accretion disk
in a wind. The wind has large rotational motions (4,000km s-1),
providing direct observational evidence that outflows from active
galactic nuclei are launched from the disks.
S. Young et al.
doi:10.1038/nature06319
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06319.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06319.html

First-passage times in complex scale-invariant media pp77 - 80
How long does it take a random walker to reach a given target point?
This quantity, known as a first passage time, is important because of
its crucial role in various situations such as spreading of diseases
or target search processes. This paper develops a general theory that
allows the accurate evaluation of the mean first passage time in
complex media. The predictions are confirmed by numerical simulations
of several representative models of disordered media, fractals,
anomalous diffusion and scale free networks.
S. Condamin et al.
doi:10.1038/nature06201
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06201.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06201.html

Abrupt onset of a second energy gap at the superconducting transition
of underdoped Bi2212 pp81 - 84
In underdoped high-TC superconducting copper oxides a pseudogap
develops well above TC. Whether the pseudogap is a distinct phenomenon
or the incoherent continuation of the superconducting gap above TC is
one of the central questions in high- TC research. A direct and
unambiguous observation of a single-particle gap tied to the
superconducting transition as function of temperature is discovered in
underdoped Bi2Sr2CaCu2O8+δ′.
W. S. Lee et al.
doi:10.1038/nature06219
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06219.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06219.html

Radio-frequency scanning tunnelling microscopy pp85 - 88
The bandwidth of the scanning tunnelling microscope has been
significantly improved by designing a radio-frequency measurement
circuit and demonstrate first experimental results for three possible
applications; fast surface topography, thermometry at the nanometre
scale and displacement sensing.
U. Kemiktarak, T. Ndukum, K. C. Schwab and K. L. Ekinci
doi:10.1038/nature06238
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06238.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06238.html

Fire as the dominant driver of central Canadian boreal forest carbon
balance pp89 - 92
A process model with three competing vascular and nonvascular
vegetation types is used to examine the effects of climate, carbon
dioxide concentrations and fire disturbance on a large area of
Canadian boreal forest. It finds that the carbon balance of the region
was driven by changes in fire disturbance from 1948 to 2005.
Ben Bond-Lamberty, Scott D. Peckham, Douglas E. Ahl and Stith T. Gower
doi:10.1038/nature06272
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06272.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06272.html

Convergent dental adaptations in pseudo-tribosphenic and tribosphenic
mammals pp93 - 97
A 'pseudotribosphenic' mammal from the Middle Jurassic whose teeth
have a very advanced morphology for mammals of such an early date
compared with the primitive nature of the rest of its body, is
described. The find confirms the previously unexpected diversity of
the most ancient mammals, as the same fossil beds (in Inner Mongolia)
had previously revealed remains of a beaver-like swimming mammal.
Zhe-Xi Luo, Qiang Ji and Chong-Xi Yuan
doi:10.1038/nature06221
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06221.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06221.html

Thresholds and the resilience of Caribbean coral reefs pp98 - 101
Use of a model has shown that the mass mortality of a grazing urchin
in 1983 has made Caribbean reefs susceptible a general loss of
resilience. The reefs are now highly sensitive to parrotfish
exploitation, with important consequences for reef management.
Peter J. Mumby, Alan Hastings and Helen J. Edwards
doi:10.1038/nature06252
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06252.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06252.html

Neural mechanisms mediating optimism bias pp102 - 105
Optimism for the future is a ubiquitous human trait. In an fMRI study,
Phelps and colleagues link this tendency to activity in amygdala and
rostral anterior cingulate -- brain areas whose function may be
disrupted in depression. Activation in these areas is higher when
subjects imagine positive rather than negative future events, and
activity levels also correlate with individual personality tendencies
towards optimism.
Tali Sharot, Alison M. Riccardi, Candace M. Raio and Elizabeth A.
Phelps
doi:10.1038/nature06280
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06280.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06280.html

PYY modulation of cortical and hypothalamic brain areas predicts
feeding behaviour in humans pp106 - 109
Functional magnetic resonance imaging is used to examine brain areas
whose activity correlates with subsequent feeding behaviour under
different satiety states evoked by intravenous peptide YY3-36 (PYY),
administration. Under high PYY conditions, (mimicking the fed state)
changes in orbitofrontal cortex activation better predicted subsequent
feeding, whereas in low PYY conditions, hypothalamic activation
predicted food intake.
Rachel L. Batterham et al.
doi:10.1038/nature06212
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06212.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06212.html

Subcapsular sinus macrophages in lymph nodes clear lymph-borne viruses
and present them to antiviral B cells pp110 - 114
Lymph nodes help clear infecting pathogens and prevent their
dissemination. In the case of lymph-borne virus, this involves a
particular subpopulation of macrophages that is shown to capture the
viral particles and present them to B cells, leading to B cell
activation.
Tobias Junt et al.
doi:10.1038/nature06287
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06287.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06287.html

A translocation signal for delivery of oomycete effector proteins into
host plant cells pp115 - 118
A conserved peptide motif, RXLR-EER present in effector proteins from
the oomycete Phytophthora infestans (the cause of the Irish Potato
famine) is required for movement of effectors from specialized
infection structures called haustoria into plant cells. This sequence
has recently been reported to be required for the translocation of the
malarial parasite Plasmodium falciparum into human erythrocytes.
Stephen C. Whisson et al.
doi:10.1038/nature06203
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06203.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06203.html

Histone demethylase JHDM2A is critical for Tnp1 and Prm1 transcription
and spermatogenesis pp119 - 123
Targeted disruption of the gene for the histone H3K9 demethylase
JHDM2A in mouse uncovers a role for the enzyme in spermatogenesis and
regulation of transition nuclear protein and protamine genes.
Yuki Okada et al.
doi:10.1038/nature06236
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06236.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06236.html

Probing the chemistry of thioredoxin catalysis with force pp124
- 127
Thioredoxins catalyze disulphide bond reduction in all living
organisms. Single-molecule force-clamp spectroscopy has revealed that
there are two alternative forms of the catalytic reaction: the first
requires a reorientation of the disulphide bond in the substrate and
the second involves an elongation of the disulphide bond in the
substrate.
Arun P. Wiita et al.
doi:10.1038/nature06231
Abstract:
http://www.nature.com/nature/journal/v450/n7166/abs/nature06231.html
Article:
http://www.nature.com/nature/journal/v450/n7166/full/nature06231.html
 
    
 


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