16 June 2006 Vol 312, Issue 5780, Pages 1608-1677
新的鸟类化石暗示鸟的水生起源
来自中国的新发现的并保存完好的玉门甘肃鸟(Gansus yumenensis)的化石支持现代鸟的祖先是水鸟的想法。这些1.1亿年前的三维的、大部分没有压碎的甘肃鸟骨骼相当完整，它的碳化了的羽毛和足部的蹼提示，这种鸟也许像现代的潜鸟或鸊鷉一样潜水觅食，虽然可能效率不如现代鸟的高，尤海鲁和同事说。甘肃鸟是包括现代鸟和其化石祖先的鸟类中最古老的成员，新化石的发现也许能为现代鸟是如何以及什么时候开始统领天空。
报告：A Nearly Modern Amphibious Bird from the Early Cretaceous of Northwestern China, Hai-lu You, et al.
肝脏与脂肪间的信号通路
日本研究人员发现了一个在肝脏与末梢脂肪组织之间传递信号的神经元通路，帮助调节身体的能量平衡。大脑和其它组织之间有两个通讯系统，最终帮助控制胃口以及脂肪代谢。一个系统涉及血液中循环的分子，另一个涉及神经系统。Kenji Uno和同事研究了小鼠肝脏中的PPARg受体的作用，该受体过去被认为与肥胖症有关。他们发现这个蛋白参与一个涉及调节能量开销、系统胰岛素敏感性、葡萄糖代谢、以及肝脏和的末梢脂肪之间的脂肪分布的通路。该通路也许能帮助保护动物不受由于过多脂肪贮存而导致的代谢混乱的影响。
报告：Neuronal Pathway from the Liver Modulates Energy Expenditure and Systemic Insulin Sensitivity, Kenji Uno, et al.
远古的胚胎发育
中国研究人员报告说，一些最早的动物用了与某些现代动物类似的发育战略。一个细胞的核一旦在细胞分裂中劈开，统称为“胞质”的细胞成分也必须分开。包括软体动物和蜗牛的某些动物的早期胚胎中，充满胞质的被称为极叶的结构从正在分裂的细胞的一端凸起。最终它们被掐断，分别到两个分裂出来的细胞中。这个过程最终帮助产生具有特定功能的细胞。陈钧远和同事在年代为晚前寒武纪(距今约5.8亿年)的岩石中发现了许多看似极叶胚胎的化石样品。这些发现意味着这个发育战略的起源很早，几乎是在最早的动物出现时。
报告：Phosphatized Polar Lobe-Forming Embryos from the Precambrian of Southwest China, Jun-Yuan Chen, et al.
发炎增加脊髓中的疼痛感
炎症和创伤能增加一个人对疼痛的敏感性，部分地因为发炎能改变脊髓如何处理疼痛感。Hiroshi Ikeda和奥地利的同事 现在发现了脊髓中的一个疼痛“放大器”，它能被模仿炎症的低水平和无规律的疼痛输入启动。这种无规律的疼痛输入能提高脊髓中感觉疼痛的神经元的钙离子水平，导致长时程增强(LTP)或突触强度的增强，这也许会改变这些神经元与疼痛通路下一步的其它脊髓神经元的最初关键突触。研究人员说，突触的变化放大了疼痛信号，潜在地增加了一个人对疼痛的敏感性。
报告：Synaptic Amplifier of Inflammatory Pain in the Spinal Dorsal Horn, Hiroshi Ikeda, et al.
确定塔克拉玛干沙漠的年代
对来自中国西北部塔克拉玛干沙漠下风口的一个1626米厚的岩石序列的分析表明，塔克拉玛干至少有500万年的历史。塔克拉玛干是世界上第二大的沙丘沙漠（仅次于阿拉伯半岛的"空域"沙漠）。孙继敏和刘东生分析的岩层序列含有能跟踪沙漠随时间形成的风化黄土。他们说，全球气候事件，比如560万年到530万年前的大洋循环改变引起的变冷以及青藏高原上升引起的大气循环变化，使塔克拉玛干沙漠得以形成。
简报：The Age of the Taklimakan Desert, Jimin Sun and Tungsheng Liu
在基因组时代研究自然选择
正如查尔斯·达尔文和阿尔弗雷德·华莱士首先明确有力地表述的，正选择是有益的特征在种群中的出现随时间变得更频繁的原理。构成其基础的基因在人类进化中经历了正选择，它们能够为形成人类这个物种的事件以及至今仍在困扰我们的疾病提供深刻的了解。直到不久以前，唯一可行的确定人类中正自然选择例子的方法是分析每个可能的候选基因。在本期这篇综述中，Pardis Sabeti和同事描述了基因组范围的序列以及多态性数据如何为寻找在人类进化种经历了正选择的基因提供了全新的方法。
综述：Positive Natural Selection in the Human Lineage, P. C. Sabeti, et al.
Contents
This Week in Science
Editor summaries of this week's papers.
Science 16 June 2006: 1569.
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Editorial:
A Welcome New Look
Donald Kennedy
Science 16 June 2006: 1573.
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Editors' Choice
Highlights of the recent literature.
Science 16 June 2006: 1574.
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NetWatch
Best of the Web in science.
Science 16 June 2006: 1577.
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NEW PRODUCTS
Science 16 June 2006: 1677.
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News of the Week
ENVIRONMENTAL SCIENCE: Climate Sensors Dropped From U.S. Weather Satellite Package
Jeffrey Mervis
Science 16 June 2006: 1580.
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INFECTIOUS DISEASE: Polio Experts Strive to Understand a Puzzling Outbreak
Leslie Roberts
Science 16 June 2006: 1581.
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REPRODUCTION: Bone Marrow Fails to Produce Oocytes
Gretchen Vogel
Science 16 June 2006: 1583.
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GENETICS: U.S. Hospital Launches Large Biobank of Children's DNA
Jocelyn Kaiser
Science 16 June 2006: 1584-1585.
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STEM CELL RESEARCH: Harvard Cloners Get OK to Proceed With Caution
Constance Holden
Science 16 June 2006: 1584.
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U.S. 2007 BUDGET: NIH Gets Off to a Slow Start
Jocelyn Kaiser
Science 16 June 2006: 1585.
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AGRICULTURE: A Kinder, Gentler Jeremy Rifkin Endorses Biotech, or Does He?
Erik Stokstad
Science 16 June 2006: 1586-1587.
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PALEONTOLOGY: Fossil Embryos Hint at Early Start for Complex Development
Katherine Unger
Science 16 June 2006: 1587.
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ScienceScope
Science 16 June 2006: 1583.
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Random Samples
Science 16 June 2006: 1579.
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Newsmakers
Science 16 June 2006: 1595.
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News Focus
PLANETARY SCIENCE: In Search of the Red Planet's Sweet Spot
Richard A. Kerr
Science 16 June 2006: 1588-1590.
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ORNITHOLOGY: Vulture Research Soars as the Scavengers' Numbers Decline
Robert Koenig
Science 16 June 2006: 1591-1592.
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MATERIALS SCIENCE: Inorganic Electronics Begin to Flex Their Muscle
Robert F. Service
Science 16 June 2006: 1593-1594.
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Letters
This Week's Letters
Science 16 June 2006: 1597.
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Veterinary Virologists Share Avian Flu Data
Ilaria Capua, Ian Brown, Michael Johnson, Dennis Senne, and David Swayne
Science 16 June 2006: 1597.
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Investigating a Second Thymus in Mice
J. F. A. P. Miller; and H.-R. Rodewald
Science 16 June 2006: 1597-1598.
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BDNF in Anxiety and Depression
Allan V. Kalueff, Damira F. Avgustinovich, Natalia N. Kudryavtseva, Dennis L. Murphy;, Olivier Berton, Vaishnav Krishnan, and Eric J. Nestler
Science 16 June 2006: 1598-1599.
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Stardust Mission Results: Hot in Cold
Kurt Liffman
Science 16 June 2006: 1599.
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Show Me the Dog
Fritz Kleinhans
Science 16 June 2006: 1600.
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Corrections and Clarifications
Science 16 June 2006: 1600.
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Books et al.
BIOGRAPHY: Best and Brightest of His Generation
Ellis L. Yochelson
Science 16 June 2006: 1601.
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Books Received
Science 16 June 2006: 1601.
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Policy Forum
SCIENCE COMMUNITY: Scientific Diasporas
Béatrice Séguin, Peter A. Singer, and Abdallah S. Daar
Science 16 June 2006: 1602-1603.
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Perspectives
NEUROSCIENCE: Neurons Find Strength Through Synchrony in the Brain
Jose-Manuel Alonso
Science 16 June 2006: 1604-1605.
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GEOCHEMISTRY: Enhanced: The Pathway of Carbon in Nature
John M. Hayes
Science 16 June 2006: 1605-1606.
Published online 11 May 2006 [DOI: 10.1126/science.1128966] (in Science Express Perspectives)
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IMMUNOLOGY: Discriminating Microbe from Self Suffers a Double Toll
Christopher C. Goodnow
Science 16 June 2006: 1606-1608.
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ANTHROPOLOGY: Autonomous Cultivation Before Domestication
Ehud Weiss, Mordechai E. Kislev, and Anat Hartmann
Science 12 June 2006: 1608-1610.
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ASTRONOMY: A Key Molecular Ion in the Universe and in the Laboratory
T. R. Geballe and T. Oka
Science 16 June 2006: 1610-1612.
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CLIMATE CHANGE: Permafrost and the Global Carbon Budget
Sergey A. Zimov, Edward A. G. Schuur, and F. Stuart Chapin III
Science 16 June 2006: 1612-1613.
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Review
Positive Natural Selection in the Human Lineage
P. C. Sabeti, S. F. Schaffner, B. Fry, J. Lohmueller, P. Varilly, O. Shamovsky, A. Palma, T. S. Mikkelsen, D. Altshuler, and E. S. Lander
Science 16 June 2006: 1614-1620.
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Brevia
The Age of the Taklimakan Desert
Jimin Sun and Tungsheng Liu
Science 16 June 2006: 1621.
The appearance of windblown sediment dates the formation of the Taklimakan Desert of central Asia, the second-largest shifting-sand desert, to 5.3 million years ago.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Research Articles
Cortex Is Driven by Weak but Synchronously Active Thalamocortical Synapses
Randy M. Bruno and Bert Sakmann
Science 16 June 2006: 1622-1627.
Electrical recordings from cortical neurons in living rodents show that the numerous sensory inputs to these cells are individually weak but very effective because they act synchronously.
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Biomarker Evidence for a Major Preservation Pathway of Sedimentary Organic Carbon
Y. Hebting, P. Schaeffer, A. Behrens, P. Adam, G. Schmitt, P. Schneckenburger, S. M. Bernasconi, and P. Albrecht
Science 16 June 2006: 1627-1631.
Published online 11 May 2006 [DOI: 10.1126/science.1126372] (in Science Express Research Articles)
Laboratory and field studies show that reduced carbon is preserved in rocks and oil via inorganic reactions involving sulfur species, not bacterial processing as had been thought.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Reports
Measurement of Forces Inside a Three-Dimensional Pile of Frictionless Droplets
J. Zhou, S. Long, Q. Wang, and A. D. Dinsmore
Science 16 June 2006: 1631-1633.
Chains of about 10 droplets within droplet piles shorten and rotate as the pile is deformed, providing an explanation for organized flow in granular piles.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Bidirectional Counting of Single Electrons
Toshimasa Fujisawa, Toshiaki Hayashi, Ritsuya Tomita, and Yoshiro Hirayama
Science 16 June 2006: 1634-1636.
A device made from two coupled quantum dots can detect both the forward and reverse flow of single electrons and thus function as a sensitive ammeter.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
The Role of * Excited States in the Photodissociation of Heteroaromatic Molecules
M. N. R. Ashfold, B. Cronin, A. L. Devine, R. N. Dixon, and M. G. D. Nix
Science 16 June 2006: 1637-1640.
Three common aromatic biomolecules that absorb ultraviolet light can dissipate energy by breaking their N朒 or O朒 bonds without activating their vibrational modes.
Abstract »| Full Text »| PDF »|
A Nearly Modern Amphibious Bird from the Early Cretaceous of Northwestern China
Hai-lu You, Matthew C. Lamanna, Jerald D. Harris, Luis M. Chiappe, Jingmai O'Connor, Shu-an Ji, Jun-chang Lü, Chong-xi Yuan, Da-qing Li, Xing Zhang, Kenneth J. Lacovara, Peter Dodson, and Qiang Ji
Science 16 June 2006: 1640-1643.
A well-preserved bird from about 120 million years ago has webbed feet and other adaptations for an aquatic lifestyle and may be a predecessor of modern birds.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Phosphatized Polar Lobe-Forming Embryos from the Precambrian of Southwest China
Jun-Yuan Chen, David J. Bottjer, Eric H. Davidson, Stephen Q. Dornbos, Xiang Gao, Yong-Hua Yang, Chia-Wei Li, Gang Li, Xiu-Qiang Wang, Ding-Chang Xian, Hung-Jen Wu, Yeu-Kuang Hwu, and Paul Tafforeau
Science 16 June 2006: 1644-1646.
Fossilized embryos dating to 580 million years ago reveal polar lobes, implying that this specialization of early cell division emerged in some of the earliest animals.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Element Partitioning: The Role of Melt Structure and Composition
M. W. Schmidt, J. A. D. Connolly, D. Günther, and M. Bogaerts
Science 16 June 2006: 1646-1650.
Experiments in a giant centrifuge housing a high pressure—high temperature press reveal how the composition of melts in the earth affects trace-element partitioning.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
p53 Regulates Mitochondrial Respiration
Satoaki Matoba, Ju-Gyeong Kang, Willmar D. Patino, Andrew Wragg, Manfred Boehm, Oksana Gavrilova, Paula J. Hurley, Fred Bunz, and Paul M. Hwang
Science 16 June 2006: 1650-1653.
Published online 25 May 2006 [DOI: 10.1126/science.1126863] (in Science Express Reports)
Cancer cells can survive in low-oxygen conditions because a defect in a common tumor suppressor inhibits mitochondrial respiration, allowing glycolysis to take place.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
The Xist RNA Gene Evolved in Eutherians by Pseudogenization of a Protein-Coding Gene
Laurent Duret, Corinne Chureau, Sylvie Samain, Jean Weissenbach, and Philip Avner
Science 16 June 2006: 1653-1655.
A noncoding RNA that silences extra copies of sex chromosomes evolved from a gene that lost its protein-coding function after the eutherian-marsupial divergence.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Neuronal Pathway from the Liver Modulates Energy Expenditure and Systemic Insulin Sensitivity
Kenji Uno, Hideki Katagiri, Tetsuya Yamada, Yasushi Ishigaki, Takehide Ogihara, Junta Imai, Yutaka Hasegawa, Junhong Gao, Keizo Kaneko, Hiroko Iwasaki, Hisamitsu Ishihara, Hironobu Sasano, Kouichi Inukai, Hiroyuki Mizuguchi, Tomoichiro Asano, Masakazu Shiota, Masamitsu Nakazato, and Yoshitomo Oka
Science 16 June 2006: 1656-1659.
A neuronal pathway that exchanges metabolic signals between liver and peripheral fat helps to coordinate energy balance in mammals.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Synaptic Amplifier of Inflammatory Pain in the Spinal Dorsal Horn
Hiroshi Ikeda, Johanna Stark, Harald Fischer, Matthias Wagner, Ruth Drdla, Tino Jäger, and Jürgen Sandkühler
Science 16 June 2006: 1659-1662.
Chronic inflammatory pain results from long-term potentiation at spinal cord synapses, which can be triggered by irregular, low-frequency input such as occurs after an injury.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Food-Caching Western Scrub-Jays Keep Track of Who Was Watching When
Joanna M. Dally, Nathan J. Emery, and Nicola S. Clayton
Science 16 June 2006: 1662-1665.
Published online 18 May 2006 [DOI: 10.1126/science.1126539] (in Science Express Reports)
Western scrub-jays remember which birds watched them hide food and use this knowledge to minimize the risk that one of these observers might pilfer their caches.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Regulation of B Cell Tolerance by the Lupus Susceptibility Gene Ly108
Kirthi Raman Kumar, Liunan Li, Mei Yan, Madhavi Bhaskarabhatla, Angela B. Mobley, Charles Nguyen, Jill M. Mooney, John D. Schatzle, Edward K. Wakeland, and Chandra Mohan
Science 16 June 2006: 1665-1669.
Mice with a genetic variant of a protein that helps eliminate cells making self-reactive antibodies are more likely to suffer from an autoimmune disease.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Autoreactive B Cell Responses to RNA-Related Antigens Due to TLR7 Gene Duplication
Prapaporn Pisitkun, Jonathan A. Deane, Michael J. Difilippantonio, Tatyana Tarasenko, Anne B. Satterthwaite, and Silvia Bolland
Science 16 June 2006: 1669-1672.
Published online 18 May 2006 [DOI: 10.1126/science.1124978] (in Science Express Reports)
Genetic duplication of an innate immune receptor on the Y chromosome makes male mice more susceptible to the development of a lupus-like autoimmune disorder.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Extrafollicular Activation of Lymph Node B Cells by Antigen-Bearing Dendritic Cells
Hai Qi, Jackson G. Egen, Alex Y. C. Huang, and Ronald N. Germain
Science 16 June 2006: 1672-1676.
Images of living tissue show that antibody-producing cells moving from the blood to the lymph node are unexpectedly activated by specialized antigen - presenting cells.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
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