25 August 2006 Vol 313, Issue 5790, Pages 1016-1145 Contents早期哺乳动物的牙齿特征
来自俄罗斯一考古点的单个牙齿化石提示，一个所有哺乳动物都有的牙齿特征在1.3亿年前的早白垩纪就已经进化出来。哺乳动物上臼齿的尖部与对应的下臼齿的凹部相配，很像研杵与研钵的匹配。这个特有结构给予哺乳动物压碎和研磨食物的能力，同时也使它们能用牙撕裂和切断食物。这个结构的研钵部分已被发现在过去找到的其他早期哺乳动物牙化石上存在，现在Alexey Lopatin和Alexander Averianov描述了新的上臼齿有的重要的研杵部分。在本期这篇简报中，研究人员讨论了这一新发现可能如何改变人们对早期哺乳动物进化的认识。
报告：An Aegialodontid Upper Molar and the Evolution of Mammal Dentition, Alexey V. Lopatin and Alexander O. Averianov
叶子化石虫咬痕迹记录灭绝事件后的进化
研究人员报告说，在一次大规模的物种灭绝发生后，有些植物和吃植物的昆虫的多样性也许不是相互依赖的。正如R. L. Kitching在一篇相关的研究评述中指出的，过去的研究曾提出，吃植物的昆虫的多样性也许与它们能吃到植物的多样性有直接关系。但是这项Peter Wilf和同事做的新研究使这个问题变得更复杂。文章作者研究了6500万年前白垩纪末期灭绝事件的几百万年后的几千个被虫子咬过的叶子化石。许多食植物的虫子对叶子有特有的损坏，从而在叶子化石上留下了它们的标志，使研究人员得以同时分析史前昆虫与植物的多样性。文章作者报告说，在大多数情况下，灭绝事件后植物和昆虫的多样性都相对较低，但是有两个重要的特例，表现出植物和昆虫的相对高的多样性。这使研究人员们得出结论，在有一段时间中在某些地点，植物看起来是在不被昆虫食用的情况下进化的，在另一些地方，尽管没有植物的多样性，昆虫也得以进化。
报告：Decoupled Plant and Insect Diversity After the End-Cretaceous Extinction, Peter Wilf, Conrad C. Labandeira, Kirk R. Johnson, and Beth Ellis
研究评述：Crafting the Pieces of the Diversity Jigsaw Puzzle, R. L. Kitching
"化学伴随物质"类药物能治小鼠的糖尿病
研究人员报告说，某些帮助细胞完成新合成的蛋白的最后修饰的药物能保护小鼠不环2型糖尿病。如果这些药物在人体中同样工作，它们也许能为治疗人类的2型糖尿病提供新线索。过去的研究发现，肥胖症激发细胞的内质网(ER)的应激，该网在蛋白质折叠和运输上有作用。而ER应激转过来打乱身体的胰岛素信号系统。Umut Ozcan 和同事研究了一类名为"化学伴随物质"的、使ER功能正常化的药物，在2型糖尿病的小鼠模式中是否有治疗作用。在遗传肥胖和患糖尿病的小鼠中，该药物治疗了血糖过高症，恢复了对胰岛素的敏感性，研究人员报告说。他们注意到这些药物在其他临床试验中已被证明是安全的。
报告：Chemical Chaperones Reduce ER Stress and Restore Glucose Homeostasis in a Mouse Model of Type 2 Diabetes, Umut Ozcan, et al.
学习加强了神经元的连接
两项研究也许为我们的大脑通过名为"长时程增强(LTP)"的过程存贮记忆提供了最终的实验证据。LTP指大脑皮层中连接神经元的"突触"强度的持续增加，LTP是30多年前发现的，吸引了众多科学家对其作为学习和记忆机制的研究，但是一直没有人能直接揭示LTP的确是由学习导致的。一篇相关的研究评述简单描述了LTP假说的两个关键的预测：大脑的海马区域中的学习应该带来LTP，而且在学习一个任务后抑制LTP应该将这个任务的记忆消除。Jonathan Whitlock和同事现在为第一个预测提供了证据。他们让大鼠在学习避免进入一个隔间，大鼠在隔间曾受到轻度电击，研究纪录了大鼠学习之前与之后的海马电活动。他们在记录电极的一部分中观察到了LTP。在另一项研究中，Eva Pastalkova和同事用一个消除突触增强的名位ZIP的肽来检验第二个预测。他们首先训练大鼠在一个旋转的平台上避免一个受电击的区域，但是在给动物注射ZIP后，它们不再避免这个电击区域。
研究文章：Learning Induces Long-Term Potentiation in the Hippocampus, Jonathan R. Whitlock, Arnold J. Heynen, Marshall G. Shuler, and Mark F. Bear
报告：Storage of Spatial Information by the Maintenance Mechanism of LTP, Eva Pastalkova, et al.
DNA损坏哨兵与p53蛋白的关系
研究人员搞清楚了DNA损坏哨兵ATM（该蛋白在共济失调毛细血管扩张症患者身上有突变）与无处不有的肿瘤抑制蛋白p53之间的关系，搞清楚这两者间的关系也许能帮助解释为什么为什么患共济失调毛细血管扩张症的人患癌症的风险增加。David Dornan和同事显示，ATM对p53的作用是通过一个叫COP1的酶实现的。在通常情况下，COP1降解p53, 降低活跃的肿瘤抑制因子的数量。但是，当ATM检测到DNA损坏后，它改变COP1酶的作用，使该酶不再降解p53，而转变为降解自身。研究人员发现，如果这个混合中没有COP1，p53会响应DNA的损坏从而增多。
报告：ATM Engages Autodegradation of the E3 Ubiquitin Ligase COP1 After DNA Damage, David Dornan, et al.
本期专题部分：淡水资源
世界上近五分之一的人口没有安全的饮用水，超过三分之一的人口面临的卫生条件不令人满意。每年有超过150万的儿童死于腹泻，这些数据给本期的全球淡水问题提供了一些背景，淡水在发达国家经常被当成理所当然的东西。来自日本、瑞士、以色列、和美国的一组综述和研究评述，加上几篇特别新闻报道，介绍了世界各地致力于获得和维持淡水资源的科学和工程的努力。
专题介绍：A Thirsty World, Jake Yeston, Robert Coontz, Jesse Smith, and Caroline Ash
Special IssueFreshwater Resources
A Thirsty World
Jake Yeston, Robert Coontz, Jesse Smith, and Caroline Ash
Science 25 August 2006: 1067.
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News
Running Out of Water--and Time
John Bohannon
Science 25 August 2006: 1085-1087.
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Desalination Freshens Up
Robert F. Service
Science 25 August 2006: 1088-1090.
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Perspectives
Waterborne Infectious Diseases—Could They Be Consigned to History?
Alan Fenwick
Science 25 August 2006: 1077-1081.
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Seeking Sustainability: Israel's Evolving Water Management Strategy
Alon Tal
Science 25 August 2006: 1081-1084.
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Reviews
Global Hydrological Cycles and World Water Resources
Taikan Oki and Shinjiro Kanae
Science 25 August 2006: 1068-1072.
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The Challenge of Micropollutants in Aquatic Systems
René P. Schwarzenbach, Beate I. Escher, Kathrin Fenner, Thomas B. Hofstetter, C. Annette Johnson, Urs von Gunten, and Bernhard Wehrli
Science 25 August 2006: 1072-1077.
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This Week in Science
Editor summaries of this week's papers.
Science 25 August 2006: 1016.
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Editorial:
What's a Wetland, Anyhow?
Donald Kennedy and Brooks Hanson
Science 25 August 2006: 1019.
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Editors' Choice
Highlights of the recent literature.
Science 25 August 2006: 1020.
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NetWatch
Best of the Web in science.
Science 25 August 2006: 1023.
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NEW PRODUCTS
Science 25 August 2006: 1145.
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News of the Week
AVIAN INFLUENZA: Pushed by an Outsider, Scientists Call for Global Plan to Share Flu Data
Martin Enserink
Science 25 August 2006: 1026.
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MATHEMATICS: Perelman Declines Math's Top Prize; Three Others Honored in Madrid
Dana Mackenzie
Science 25 August 2006: 1027-1028.
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MATHEMATICS: Okounkov, Tao, and Werner Capture Fields Medals, 'Math's Nobels'
Dana Mackenzie
Science 25 August 2006: 1027.
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PALEOANTHROPOLOGY: Skeptics Seek to Slay the 'Hobbit,' Calling Flores Skeleton a Modern Human
Elizabeth Culotta
Science 25 August 2006: 1028-1029.
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ARCHAEOLOGY: After 2 Millennia on Ice, a Nomad Resurfaces
Andrew Curry
Science 25 August 2006: 1029.
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INFECTIOUS DISEASE: At International AIDS Conference, Big Names Emphasize Big Gaps
Jon Cohen
Science 25 August 2006: 1030-1031.
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STEM CELLS: Scientists Derive Line From Single Embryo Cell
Gretchen Vogel
Science 25 August 2006: 1031.
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SPACE SCIENCE: NASA Chief Blasts Science Advisers, Widening Split With Researchers
Andrew Lawler
Science 25 August 2006: 1032.
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CHEMISTRY: New in Nanotech: Self-Folding Delivery Boxes
Robert F. Service
Science 25 August 2006: 1032-1033.
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ASTRONOMY: Satellite's X-ray Vision Clinches the Case for Dark Matter
Tom Siegfried
Science 25 August 2006: 1033.
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ScienceScope
Science 25 August 2006: 1029.
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Random Samples
Science 25 August 2006: 1025.
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Newsmakers
Science 25 August 2006: 1041.
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News Focus
HYDROENGINEERING: Going Against the Flow
Richard Stone and Hawk Jia
Science 25 August 2006: 1034-1037.
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HYDROENGINEERING: Controversial Rivers Project Aims to Turn India's Fierce Monsoon Into a Friend
Pallava Bagla
Science 25 August 2006: 1036-1037.
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HURRICANE KATRINA: One Year After, New Orleans Researchers Struggle to Rebuild
Jocelyn Kaiser
Science 25 August 2006: 1038-1039.
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METEOROLOGY: Sharpening Up Models for a Better View of the Atmosphere
Richard A. Kerr
Science 25 August 2006: 1040.
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Letters
This Week's Letters
Science 25 August 2006: 1043.
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Preserving the Jarawa's Future
Stephen Corry
Science 25 August 2006: 1043.
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Ice Sheets and Sea Level
Johannes Oerlemans, Dorthe Dahl-Jensen, Valérie Masson-Delmotte;, Jonathan T. Overpeck, Bette L. Otto-Bliesner, Gifford H. Miller, Richard B. Alley, Daniel R. Muhs, and Shawn J. Marshall
Science 25 August 2006: 1043-1045.
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Corrections and Clarifications
Science 25 August 2006: 1045.
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Books et al.
WATER RESOURCES: For Our Thirsty World, Efficiency or Else
Sandra L. Postel
Science 25 August 2006: 1046-1047.
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PHILOSOPHY OF SCIENCE: Science Undermined by Our Limited Imagination?
Tim Lewens
Science 25 August 2006: 1047-1048.
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Browsings
Science 25 August 2006: 1047.
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Books Received
Science 25 August 2006: 1048.
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Education Forum
INQUIRY LEARNING: Teaching and Assessing Knowledge Integration in Science
Marcia C. Linn, Hee-Sun Lee, Robert Tinker, Freda Husic, and Jennifer L. Chiu
Science 25 August 2006: 1049-1050.
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Perspectives
ECOLOGY: Are Global Conservation Efforts Successful?
Ana S. L. Rodrigues
Science 25 August 2006: 1051-1052.
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IMMUNOLOGY: Unraveling Gut Inflammation
Warren Strober
Science 25 August 2006: 1052-1054.
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ASTRONOMY: Growing Apart in Lock Step
Jack J. Lissauer
Science 25 August 2006: 1054-1055.
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ECOLOGY: Crafting the Pieces of the Diversity Jigsaw Puzzle
R. L. Kitching
Science 25 August 2006: 1055-1057.
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PHYSICS: Surface Transfer Doping of Semiconductors
Jürgen Ristein
Science 25 August 2006: 1057-1058.
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NEUROSCIENCE: Enhanced: ZAP and ZIP, a Story to Forget
Tim V. P. Bliss, Graham L. Collingridge, and Serge Laroche
Science 25 August 2006: 1058-1059.
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Association Affairs
AAAS News and Notes
Science 25 August 2006: 1060.
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Review
Trajectory Shifts in the Arctic and Subarctic Freshwater Cycle
Bruce J. Peterson, James McClelland, Ruth Curry, Robert M. Holmes, John E. Walsh, and Knut Aagaard
Science 25 August 2006: 1061-1066.
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Brevia
An Aegialodontid Upper Molar and the Evolution of Mammal Dentition
Alexey V. Lopatin and Alexander O. Averianov
Science 25 August 2006: 1092.
An early mammal found in Russia shows that a distinctive dental pattern of marsupials and placental animals had evolved by 130 million years ago.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Research Article
Learning Induces Long-Term Potentiation in the Hippocampus
Jonathan R. Whitlock, Arnold J. Heynen, Marshall G. Shuler, and Mark F. Bear
Science 25 August 2006: 1093-1097.
Rapid learning in rats strengthens synapses in the hippocampus of the brain, confirming that synaptic long-term potentiation underlies learning in vivo.
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Reports
Superfluidity of Grain Boundaries and Supersolid Behavior
S. Sasaki, R. Ishiguro, F. Caupin, H. J. Maris, and S. Balibar
Science 25 August 2006: 1098-1100.
Published online 27 July 2006 [DOI: 10.1126/science.1130879] (in Science Express Reports)
Experiments show that superfluid flow along grain boundaries in solid 4He may explain its supersolid behavior.
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Detection, Stimulation, and Inhibition of Neuronal Signals with High-Density Nanowire Transistor Arrays
Fernando Patolsky, Brian P. Timko, Guihua Yu, Ying Fang, Andrew B. Greytak, Gengfeng Zheng, and Charles M. Lieber
Science 25 August 2006: 1100-1104.
With an array of silicon nanowire field-effect transistors, the activity at up to 50 locations along an axon of a cortical rat neuron can be recorded and modified.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Discrete Sandwich Compounds of Monolayer Palladium Sheets
Tetsuro Murahashi, Mayu Fujimoto, Masa-aki Oka, Yasuhiro Hashimoto, Tomohito Uemura, Yasuki Tatsumi, Yoshihide Nakao, Atsushi Ikeda, Shigeyoshi Sakaki, and Hideo Kurosawa
Science 25 August 2006: 1104-1107.
A compound containing three or five metal atoms, instead of the usual one, between two hydrocarbon layers challenges the boundary between discrete molecules and layered solids.
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Forced Resonant Migration of Pluto's Outer Satellites by Charon
William R. Ward and Robin M. Canup
Science 25 August 2006: 1107-1109.
Published online 6 July 2006 [DOI: 10.1126/science.1127293] (in Science Express Reports)
The orbits of Pluto抯 two small moons can be explained if they corotated with the larger moon, Charon, following an impact in which the three moons were created.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Ice Record of 13C for Atmospheric CH4 Across the Younger Dryas-Preboreal Transition
Hinrich Schaefer, Michael J. Whiticar, Edward J. Brook, Vasilii V. Petrenko, Dominic F. Ferretti, and Jeffrey P. Severinghaus
Science 25 August 2006: 1109-1112.
Carbon isotopes in ice methane did not vary near the end of the last deglaciation when atmospheric methane levels rose, implying that clathrates were not the methane source.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Decoupled Plant and Insect Diversity After the End-Cretaceous Extinction
Peter Wilf, Conrad C. Labandeira, Kirk R. Johnson, and Beth Ellis
Science 25 August 2006: 1112-1115.
After the end-Cretaceous extinction, plants diversified without many insects in some places, whereas elsewhere insect herbivores diversified despite few plant species.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Why Are There So Many Species of Herbivorous Insects in Tropical Rainforests?
Vojtech Novotny, Pavel Drozd, Scott E. Miller, Miroslav Kulfan, Milan Janda, Yves Basset, and George D. Weiblen
Science 25 August 2006: 1115-1118.
Published online 13 July 2006 [DOI: 10.1126/science.1129237] (in Science Express Reports)
The number of insect species in tropical and temperate forests is determined by the diversity of tree species.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Brassinosteroids Regulate Dissociation of BKI1, a Negative Regulator of BRI1 Signaling, from the Plasma Membrane
Xuelu Wang and Joanne Chory
Science 25 August 2006: 1118-1122.
Published online 20 July 2006 [DOI: 10.1126/science.1127593] (in Science Express Reports)
A steroid hormone signaling pathway in plants is activated when an inhibitor is displaced from the cell membrane.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
ATM Engages Autodegradation of the E3 Ubiquitin Ligase COP1 After DNA Damage
David Dornan, Harumi Shimizu, Angie Mah, Tanay Dudhela, Michael Eby, Karen O'Rourke, Somasekar Seshagiri, and Vishva M. Dixit
Science 25 August 2006: 1122-1126.
After a cell experiences DNA damage, the enzyme that normally tags a tumor suppressor for degradation is inhibited, allowing accumulation of the tumor suppressor.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Symbiotic Bacteria Direct Expression of an Intestinal Bactericidal Lectin
Heather L. Cash, Cecilia V. Whitham, Cassie L. Behrendt, and Lora V. Hooper
Science 25 August 2006: 1126-1130.
The cells that line the intestine secrete a small molecule that binds to resident bacteria through a peptidylglycan interaction and kills them.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Individual Cell Migration Serves as the Driving Force for Optic Vesicle Evagination
Martina Rembold, Felix Loosli, Richard J. Adams, and Joachim Wittbrodt
Science 25 August 2006: 1130-1134.
High-resolution imaging of cells in living fish shows that migrating cells form the eye by acting individually rather than collectively.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Argonaute Slicing Is Required for Heterochromatic Silencing and Spreading
Danielle V. Irvine, Mikel Zaratiegui, Niraj H. Tolia, Derek B. Goto, Daniel H. Chitwood, Matthew W. Vaughn, Leemor Joshua-Tor, and Robert A. Martienssen
Science 25 August 2006: 1134-1137.
In RNA interference, genes are silenced through base-pairing of small interfering RNAs with RNA, presumably transcribed from the silenced region.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Chemical Chaperones Reduce ER Stress and Restore Glucose Homeostasis in a Mouse Model of Type 2 Diabetes
Umut Özcan, Erkan Yilmaz, Lale Özcan, Masato Furuhashi, Eric Vaillancourt, Ross O. Smith, Cem Z. Görgün, and Gökhan S. Hotamisligil
Science 25 August 2006: 1137-1140.
Small-molecule drugs that help to fold and process proteins correct type 2 diabetes in a mouse model, providing a new lead for the treatment of human diabetes.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Storage of Spatial Information by the Maintenance Mechanism of LTP
Eva Pastalkova, Peter Serrano, Deana Pinkhasova, Emma Wallace, André Antonio Fenton, and Todd Charlton Sacktor
Science 25 August 2006: 1141-1144.
Maintenance of spatial memories in the rat brain can be reversed by inhibition of long-term synaptic potentiation in the rat brain.
Abstract »| Full Text »| PDF »| Supporting Online Material »|
Technical Comments
Comment on "Cell Type Regulates Selective Segregation of Mouse Chromosome 7 DNA Strands in Mitosis"
James E. Haber
Science 25 August 2006: 1045.
Abstract »| Full Text »| PDF »|
Response to Comment on "Cell Type Regulates Selective Segregation of Mouse Chromosome 7 DNA Strands in Mitosis"
Amar J. S. Klar and Athanasios Armakolas
Science 25 August 2006: 1045.
Abstract »| Full Text »| PDF »|
