bluuebunny/crossref_metadata_2025 huggingface dataset:
Retinal Degeneration in Mice Lacking the γ Subunit of the Rod cGMP Phosphodiesterase
Authors: Tsang Stephen H. , Gouras Peter , Yamashita Clyde K. , Kjeldbye Hild , Fisher John , Farber Debora B. , Goff Stephen P.
Published: October 2006

The retinal cyclic guanosine 3′,5′-monophosphate (cGMP) phosphodiesterase (PDE) is a key regulator of phototransduction in the vertebrate visual system. PDE consists of a catalytic core of α and β subunits associated with two inhibitory γ subunits. A gene-targeting approach was used to disrupt the mouse PDEγ gene. This mutation resulted in a rapid retinal degeneration resembling human retinitis pigmentosa. In homozygous mutant mice, reduced rather than increased PDE activity was apparent; the PDEαβ dimer was formed but lacked hydrolytic activity. Thus, the inhibitory γ subunit appears to be necessary for integrity of the photoreceptors and expression of PDE activity in vivo.
Worm Genes Imply a Master Clock
Authors: Pennisi Elizabeth
Published: October 2006

New research reported in this issue of
Science
(
p. 1010
) reveals a set of genes, the clk genes, that when mutated can make a worm live life in slow motion, swimming and eating more slowly than usual. And these experimental worms also live longer; worms with combinations of mutations lived five times as long as normal, the greatest increase in life-span ever seen in any organism. Researchers hope the new work will yield clues to aging in more complex organisms as well.
A New Theory of Turbulence Causes a Stir Among Experts
Authors: Cipra Barry
Published: October 2006

Two mathematicians are claiming that a basic formula of turbulence is flawed. The formula, known as the logarithmic law of the wall, describes how the velocity of a turbulent fluid slows in a thin layer near a surface, and it provides a convenient rule of thumb for the design of aircraft, pipelines, and other structures that operate in a fluid environment. The new analysis finds that the assumptions underlying the law of the wall are flawed, and it is off by as much as 65%. While the effect is too small to be a safety concern, the claim is roiling the field of turbulence. Computers/Math
Chemokines Take Center Stage in Inflammatory Ills
Authors: Gura Trisha
Published: October 2006

The proteins known as chemokines achieved public fame late last year, as a result of work suggesting that they might help protect against AIDS. But the proteins have a much wider role than that. As magnets for white blood cells, they play a key role in in flammatory responses and thus in the body's defenses against a wide array of invading pathogens. What's more, chemokine effects can also backfire, and contribute to a wide range of inflammatory diseases, such as rheumatoid arthritis, asthma, and adult res piratory distress syndrome, a major killer characterized by fluid buildup in the lungs. As a result, the chemokines have become major targets of efforts to develop new anti-inflammatory therapies, and recent work is already producing some promising results.
Stratospheric Control of Climate
Authors: Robock Alan
Published: October 2006

Firm evidence for a connection between variations in solar radiation and climate has been elusive. In his Perspective, Robock discusses the results of Haigh, who reports in this same issue (
p. 981
) new computer simulations of solar-climate interaction. The computer model produces a realistic tropospheric response to solar variation, in part because the simulation takes into account the stratospheric changes in ozone caused by the sun, which in turn influence the troposphere.
The Impact of Solar Variability on Climate
Authors: Haigh Joanna D.
Published: October 2006

A general circulation model that simulated changes in solar irradiance and stratospheric ozone was used to investigate the response of the atmosphere to the 11-year solar activity cycle. At solar maximum, a warming of the summer stratosphere was found to strengthen easterly winds, which penetrated into the equatorial upper troposphere, causing poleward shifts in the positions of the subtropical westerly jets, broadening of the tropical Hadley circulations, and poleward shifts of the storm tracks. These effects are similar to, although generally smaller in magnitude than, those observed in nature. A simulation in which only solar irradiance was changed showed a much weaker response.
Universality Classes of Optimal Channel Networks
Authors: Maritan Amos , Colaiori Francesca , Flammini Alessandro , Cieplak Marek , Banavar Jayanth R.
Published: October 2006

Energy minimization of both homogeneous and heterogeneous river networks shows that, over a range of parameter values, there are only three distinct universality classes. The exponents for all three classes of behavior are calculated.
Lead and Helium Isotope Evidence from Oceanic Basalts for a Common Deep Source of Mantle Plumes
Authors: Hanan B. B. , Graham D. W.
Published: October 2006

Linear arrays in lead isotope space for mid-ocean ridge basalts (MORBs) converge on a single end-member component that has intermediate lead, strontium, and neodymium isotope ratios compared with the total database for oceanic island basalts (OIBs) and MORBs. The MORB data are consistent with the presence of a common mantle source region for OIBs that is sampled by mantle plumes.
3
He/
4
He ratios for MORBs show both positive and negative correlation with the
206
Pb/
204
Pb ratios, depending on the MORB suite. These data suggest that the common mantle source is located in the transition zone region. This region contains recycled, oceanic crustal protoliths that incorporated some continental lead before their subduction during the past 300 to 2000 million years.
Spread of Synaptic Depression Mediated by Presynaptic Cytoplasmic Signaling
Authors: Cash Sydney , Zucker Robert S. , Poo Mu-ming
Published: October 2006

Postsynaptic activity may modulate presynaptic functions by transsynaptic retrograde signals. At developing neuromuscular synapses in
Xenopus
nerve-muscle cultures, a brief increase in the cytosolic calcium ion (Ca
2+
) concentration in postsynaptic myocytes induced persistent depression of presynaptic transmitter secretion. This depression spread to distant synapses formed by the same neuron. Clearance of extracellular fluid did not prevent the spread of depression, and depression could not be induced by increasing the Ca
2+
concentration in a nearby myocyte not in contact with the presynaptic neuron. Thus, the spread of depression is mediated by signaling in the presynaptic cytoplasm, rather than by a retrograde factor in the extracellular space.
Ancient Sea-Level Swings Confirmed
Authors: Kerr Richard A.
Published: October 2006

For 20 years, Exxon researchers have touted geologic benchmarks measured on the continental margins as evidence of changes in global sea level. But academic geologists have been skeptical, for much of the supporting data was proprietary. New data from ocean cores suggest that the Exxon geologists were right after all, but the mechanism behind the most ancient sea-level swings remains a mystery.
Mammal Diversity Takes a 20-Million-Year Leap Backwards
Authors: Peterson Kim
Published: October 2006

Elephants would seem hard animals to miss, but tracking them back in time hasn't been easy. Paleontologists have followed the fossil trail of elephants and their kin—the ungulates, which include whales and deer and are one of the largest orders of mammals—back to the Cretaceous-Tertiary (K-T) boundary, when the dinosaurs went extinct 65 million years ago. There researchers ran out of fossils. But on (
page 1150
) of this issue, researchers report that some fossil teeth and jaws—recovered over the past decade from a windswept desert in the southwestern former Soviet Union by a now-deceased Russian paleontologist—look enough like ungulate teeth to push their ancestry back another 20 million years. And because these 85-million-year-old “zhelestids,” as the rat-sized ungulate forebears are called, were found in Asia, it opens up the possibility that ungulates first appeared there.
The Cerebellum: A Neuronal Learning Machine?
Authors: Raymond Jennifer L. , Lisberger Stephen G. , Mauk Michael D.
Published: October 2006

Comparison of two seemingly quite different behaviors yields a surprisingly consistent picture of the role of the cerebellum in motor learning. Behavioral and physiological data about classical conditioning of the eyelid response and motor learning in the vestibulo-ocular reflex suggest that (i) plasticity is distributed between the cerebellar cortex and the deep cerebellar nuclei; (ii) the cerebellar cortex plays a special role in learning the timing of movement; and (iii) the cerebellar cortex guides learning in the deep nuclei, which may allow learning to be transferred from the cortex to the deep nuclei. Because many of the similarities in the data from the two systems typify general features of cerebellar organization, the cerebellar mechanisms of learning in these two systems may represent principles that apply to many motor systems.
Fossil Evidence for a Late Cretaceous Origin of “Hoofed” Mammals
Authors: Archibald J. David
Published: October 2006

Seventeen of eighteen orders of living placental mammals are not known before 65 million years ago. The monophyly of each order is well established, but interrelations have been less certain. A superordinal grouping of up to seven extant orders plus a variety of extinct orders, all included within Ungulata (“hoofed” mammals), can be linked to Late Cretaceous mammals from the 85-million-year-old Bissekty Formation, Uzbekistan (and, less certainly, North America and Europe), thus pushing the origin of this major clade back by 20 million years. Ungulatomorphs are not closely related to primates, rodents, or rabbits.
Bacteria as Mediators of Copper Sulfide Enrichment During Weathering
Authors: Sillitoe Richard H. , Folk Robert L. , Saric Nicolás
Published: October 2006

Supergene chalcocite enrichment during weathering is an economically vital natural process that may lead to severalfold increases in the copper content of sulfide deposits. A scanning electron microscope study of chalcocite (Cu
2
S) from major enriched copper deposits in northern Chile revealed myriad bacterioform bodies in original growth positions near replacement interfaces with remnant hypogene sulfide grains. These minute (0.03 to 0.2 micrometers) chalcocite bodies are interpreted as fossilized and metallized nannobacteria that promoted the fixation of mobilized copper ions. Bacterial activity may thus be a fundamental factor in supergene enrichment of copper deposits.
TAB1: An Activator of the TAK1 MAPKKK in TGF-β Signal Transduction
Authors: Shibuya Hiroshi , Yamaguchi Kyoko , Shirakabe Kyoko , Tonegawa Akane , Gotoh Yukiko , Ueno Naoto , Irie Kenji , Nishida Eisuke , Matsumoto Kunihiro
Published: October 2006

Transforming growth factor-β (TGF-β) regulates many aspects of cellular function. A member of the mitogen-activated protein kinase kinase kinase (MAPKKK) family, TAK1, was previously identified as a mediator in the signaling pathway of TGF-β superfamily members. The yeast two-hybrid system has now revealed two human proteins, termed TAB1 and TAB2 (for TAK1 binding protein), that interact with TAK1. TAB1 and TAK1 were co-immunoprecipitated from mammalian cells. Overproduction of TAB1 enhanced activity of the plasminogen activator inhibitor 1 gene promoter, which is regulated by TGF-β, and increased the kinase activity of TAK1. TAB1 may function as an activator of the TAK1 MAPKKK in TGF-β signal transduction.
Requirement for Cholinergic Synaptic Transmission in the Propagation of Spontaneous Retinal Waves
Authors: Feller Marla B. , Wellis David P. , Stellwagen David , Werblin Frank S. , Shatz Carla J.
Published: October 2006

Highly correlated neural activity in the form of spontaneous waves of action potentials is present in the developing retina weeks before vision. Optical imaging revealed that these waves consist of spatially restricted domains of activity that form a mosaic pattern over the entire retinal ganglion cell layer. Whole-cell recordings indicate that wave generation requires synaptic activation of neuronal nicotinic acetylcholine receptors on ganglion cells. The only cholinergic cells in these immature retinas are a uniformly distributed, bistratified population of amacrine cells, as assessed by antibodies to choline acetyltransferase. The results indicate that the major source of synaptic input to retinal ganglion cells is a system of cholinergic amacrine cells, whose activity is required for wave propagation in the developing retina.
U.K. Labs: A Year of Uncertainty
Authors: Williams Nigel
Published: October 2006

London—Most of Britain's government laboratories have been living on the edge for thepast year, while the Conservative government considers whether to close or merge them, turn them over to the private sector, or keep them in public ownership. Forty establishments that employ a total of about 20,000 staff members and spend $1.2 billion a year are being subjected to top-to-bottom reviews. Last week, the government announced its intentions for the first dozen of these labs. It said it intends to privatize most of them, but itcalled for further studies to explore how they can be transferred to the private sector.
NIH Panel Urges Overhaul of the Rating System for Grants
Authors: Marshall Eliot
Published: October 2006

Choosing winners from among the 30,000 biomedical scientists who seek federal grants each year is a delicate task, especially when more than three-quarters of grant proposals now get rejected. But tinkering with the peer-review process by which the National Institutes of Health (NIH) picks these winners is an even more delicate proposition. An internal NIH panel has, however, just issued a set of recommendations that could result in a fundamental change in the way peer-review panels weigh scientific merit. Their recommendations are available
on-line
.
Academy Fights to Maintain Research in the "Wild East"
Authors: Stone Richard
Published: October 2006

Vladivostok, Russia—In July, 30 Russian, American, and Japanese scientists are scheduled to set sail from here on a Russian research vessel to study the biodiversity of the Kuril Islands off Japan's northern tip. This important expedition is the latest example of the trans-Pacific alliances that have been forged since Russia opened up its far Eastern coast to the outside world. But it is also a symbol of a different kind: It is the only expedition the Far Eastern Branch of the Russian Academy of Sciences can afford this year, and as
Science
went to press, it was scrambling to pay a dock fee that would allow the ship—the
Professor Bogorov
—to leave harbor.
Combinatorial Chemistry Hits the Drug Market
Authors: Service Robert F.
Published: October 2006

Combinatorial chemistry is a hot field that's only getting hotter. It burst on the scene in the early 1990s as a way to simultaneously create and then test thousands of related compounds for various kinds of activity, potentially fast-forwarding the process of drug discovery. The method was originally built around large molecules, but they make poor drugs. Now chemists have optimized the complex synthetic reactions needed to make small molecules, the basis for most drugs, and they have discovered ways to make them compatible with the polymer beads that many combinatorial molecules are built upon. “People on our project are getting calls from headhunters everyday,” says one project leader.
Upgrade to Improve Arecibo's Vision
Authors: Glanz James
Published: October 2006

Astronomers are completing work on a $26 million upgrade that will sharpen the eyesight of the combination radio telescope and radar facility at Arecibo, Puerto Rico, that is run by Cornell University for the National Science Foundation. The project will give researchers the chance to use the observatory, already the world's most powerful of its type, to search for superfast radio pulsars and to extend their understanding of the nature of the whirling gases in galaxies of the early universe and the chemistry of the cloudy birthplaces of stars within the Milky Way.
Thermoelectrics Run Hot and Cold
Authors: Tritt Terry M.
Published: October 2006

Some materials exhibit thermoelectricity, a phenomenon not only useful for heating and cooling applications but also for power generation. In his Perspective, Tritt describes results reported by Sales
et al
. (
p. 1325
) on a class of thermoelectrics called skutterudites. These compounds are promising higher performance in applications such as deep space probes, new generation automobiles, and temperature stabilization.
A Molecular Paramagnetic Superconductor
Authors: Cassoux Patrick
Published: October 2006

One previously reliable rule of thumb has been that magnetism and superconductivity cannot coexist peacefully. In his Perspective, Cassoux discusses a new organic superconductor that contains magnetic ions, which was synthesized by Kurmoo
et al
. and recently reported in the
Journal of the American Chemical Society
. As a result, previous notions about the interplay of magnetism and superconductivity will need rethinking.
Perspectives in Helioseismology
Authors: Gough D. O. , Leibacher J. W. , Scherrer P. H. , Toomre J.
Published: October 2006

Helioseismology is probing the interior structure and dynamics of the sun with ever-increasing precision, providing a well-calibrated laboratory in which physical processes can be studied under conditions that are unattainable on Earth. Nearly 10 million resonant modes of oscillation are observable in the solar atmosphere, and their frequencies need to be known with great accuracy in order to gauge the sun's interior. The advent of nearly continuous imaged observations from the complementary ground-based Global Oscillation Network Group (GONG) observatories and the space-based Solar and Heliospheric Observatory instruments augurs a new era of discovery. The flow of early results from GONG resolves some issues and raises a number of theoretical questions whose answers are required for understanding how a seemingly ordinary star actually operates.
The Global Oscillation Network Group (GONG) Project
Authors: Harvey J. W. , Hill F. , Hubbard R. P. , Kennedy J. R. , Leibacher J. W. , Pintar J. A. , Gilman P. A. , Noyes R. W. , Title A. M. , Toomre J. , Ulrich R. K. , Bhatnagar A. , Kennewell J. A. , Marquette W. , Patrón J. , Saá O. , Yasukawa E.
Published: October 2006

Helioseismology requires nearly continuous observations of the oscillations of the solar surface for long periods of time in order to obtain precise measurements of the sun's normal modes of oscillation. The GONG project acquires velocity images from a network of six identical instruments distributed around the world. The GONG network began full operation in October 1995. It has achieved a duty cycle of 89 percent and reduced the magnitude of spectral artifacts by a factor of 280 in power, compared with single-site observations. The instrumental noise is less than the observed solar background.
Detection of Abundant Ethane and Methane, Along with Carbon Monoxide and Water, in Comet C/1996 B2 Hyakutake: Evidence for Interstellar Origin
Authors: Mumma Michael J. , DiSanti Michael A. , Russo Neil Dello , Fomenkova Marina , Magee-Sauer Karen , Kaminski Charles D. , Xie David X.
Published: October 2006

The saturated hydrocarbons ethane (C
2
H
6
) and methane (CH
4
) along with carbon monoxide (CO) and water (H
2
O) were detected in comet C/1996 B2 Hyakutake with the use of high-resolution infrared spectroscopy at the NASA Infrared Telescope Facility on Mauna Kea, Hawaii. The inferred production rates of molecular gases from the icy, cometary nucleus (in molecules per second) are 6.4 × 10
26
for C
2
H
6
, 1.2 × 10
27
for CH
4
, 9.8 × 10
27
for CO, and 1.7 × 10
29
for H
2
O. An abundance of C
2
H
6
comparable to that of CH
4
implies that ices in C/1996 B2 Hyakutake did not originate in a thermochemically equilibrated region of the solar nebula. The abundances are consistent with a kinetically controlled production process, but production of C
2
H
6
by gas-phase ion molecule reactions in the natal cloud core is energetically forbidden. The high C
2
H
6
/CH
4
ratio is consistent with production of C
2
H
6
in icy grain mantles in the natal cloud, either by photolysis of CH
4
-rich ice or by hydrogen-addition reactions to acetylene condensed from the gas phase.
Type II Supernova Matter in a Silicon Carbide Grain from the Murchison Meteorite
Authors: Hoppe Peter , Strebel Roger , Eberhardt Peter , Amari Sachiko , Lewis Roy S.
Published: October 2006

The circumstellar silicon carbide (SiC) grain X57 from the Murchison meteorite contains large amounts of radiogenic calcium-44 (20 times its solar system abundance) and has an anomalous silicon isotopic composition, different from other circumstellar SiC grains. Its inferred initial
44
Ti/Si and
44
Ti/
48
Ti ratios are 1.6 × 10
−4
and 0.37. In addition, it contains radiogenic magnesium-26; the inferred initial
26
Al/
27
Al ratio is 0.11. The isotopic and elemental data of X57 can be explained by selective mixing of matter from different zones of a typical type II supernova of 25 solar masses during its explosion. The high
44
Ti/Si ratio requires contributions from the innermost nickel zone of the supernova to the SiC condensation site, as similarly suggested by astronomical observations.
Decline in the Tropospheric Abundance of Halogen from Halocarbons: Implications for Stratospheric Ozone Depletion
Authors: Montzka Stephen A. , Butler James H. , Myers Richard C. , Thompson Thayne M. , Swanson Thomas H. , Clarke Andrew D. , Lock Loreen T. , Elkins James W.
Published: October 2006

Analyses of air sampled from remote locations across the globe reveal that tropospheric chlorine attributable to anthropogenic halocarbons peaked near the beginning of 1994 and was decreasing at a rate of 25 ± 5 parts per trillion per year by mid-1995. Although bromine from halons was still increasing in mid-1995, the summed abundance of these halogens in the troposphere is decreasing. To assess the effect of this trend on stratospheric ozone, estimates of the future stratospheric abundance of ozone-depleting gases were made for mid-latitude and polar regions on the basis of these tropospheric measurements. These results suggest that the amount of reactive chlorine and bromine will reach a maximum in the stratosphere between 1997 and 1999 and will decline thereafter if limits outlined in the adjusted and amended Montreal Protocol on Substances That Deplete the Ozone Layer are not exceeded in future years.
Dimerization of TFIID When Not Bound to DNA
Authors: Taggart Andrew K. P. , Pugh B. Franklin
Published: October 2006

For unknown reasons, the eukaryotic transcription factor TFIID inefficiently recognizes promoters. Human TFIID was found to form highly specific homodimers that must dissociate before DNA binding. TFIID dimers formed through self-association of the TATA-binding polypeptide (TBP) subunit and could be immunoprecipitated with antibodies to TAF
II
250, the core subunit of TFIID. Chemical cross-linking experiments in HeLa cells revealed the presence of TBP dimers in vivo. These findings suggest that dimerization through TBP is the physiological state of TFIID when not bound to DNA. Thus, the inefficiency of TFIID binding to a promoter may be partly attributable to the competitive effect of dimerization.
Computation Cracks 'Semantic Barriers' Between Databases
Authors: Nadis Steve
Published: October 2006

Differences in vocabulary between fields make it difficult or impossible to search for a familiar concept in collections of data from an unfamiliar field, which is why reference librarians are invaluable. But on the Internet, where databases are proliferating and librarians are nowhere to be seen, users need another way to cross these “semantic barriers.” Now, by using a supercomputer to comb through millions of abstracts in different fields, searching for patterns of association between key terms, information scientists laid the groundwork for a system that can suggest keywords for finding known concepts in unfamiliar databases. Computers/Math
New Dynamic Duo: PET, MRI, Joined for the First Time
Authors: Service Robert F.
Published: October 2006

Magnetic resonance imaging (MRI) excels at providing high-resolution anatomical maps, while positron emission tomography (PET) can better gauge the actual function of tissues. But never have the twain met in one machine: The powerful magnetic fields generated by MRI wreak havoc with the electronic detectors of PET scanners. That's made it hard on researchers studying the effects of drugs on particular tissues, for example. Now, however, things finally seem to be coming together. A team of researchers have created a small PET prototype that's able to distance its vital electronics from MRI's high magnetic fields, thanks to fiber optic lines and highly sensitive detectors based on a crystalline material never before used in PET. This week, at the Society of Nuclear Medicine meeting in Denver, the team demonstrated their results: the first-ever simultaneous PET and MRI images.
To See a World in 80 Kilograms of Rock
Authors: Treiman Allan
Published: October 2006

Out of the thousands of meteorites that have fallen to earth, 12 are known to have come from Mars. In his Perspective, Treiman discusses our current understanding of these martian specimens, in particular, recent results presented at the 27th Lunar and Planetary Science Conference held in March.
Environmental Estrogens: Can Two "Alrights" Make a Wrong?
Authors: Simons Stoney S.
Published: October 2006

In a report in this week's issue of
Science
, Arnold
et al
. (
p. 1489
) show that pesticides that are individually innocuous have effects like the female hormone estrogen when they are mixed together. In his Perspective, Simons outlines several mechanisms by which this synergy may be ocurring in the cell.
Long-Range (Casimir) Interactions
Authors: Spruch Larry
Published: October 2006

Normally, nonrelativistic electromagnetic theory with two-particle Coulombic interactions adequately determines the interaction potential of systems A and B if the systems are composed of particles with characteristic velocities much less than the speed of light. If, however, the time it takes light to travel between A and B exceeds a characteristic oscillation period of A or B, the way in which the potential function depends on the separation of the systems can be altered. Called the Casimir effect, it has only recently been confirmed, and it arises in physics, chemistry, and biology. It is the clearest physical manifestation of the fact that, even in a vacuum, electromagnetic fields cannot all vanish.
Amorphization of Serpentine at High Pressure and High Temperature
Authors: Irifune Tetsuo , Kuroda Koji , Funamori Nobumasa , Uchida Takeyuki , Yagi Takehiko , Inoue Toru , Miyajima Nobuyoshi
Published: October 2006

Pressure-induced amorphization of serpentine was observed at temperatures of 200° to 300°C and pressures of 14 to 27 gigapascals with a combination of a multianvil apparatus and synchrotron radiation. High-pressure phases then crystallized rapidly when the temperature was increased to 400°C. These results suggest that amorphization of serpentine is an unlikely mechanism for generating deep-focus earthquakes, as the temperatures of subducting slabs are significantly higher than those of the rapid crystallization regime.
Blockage by Adenovirus E4orf6 of Transcriptional Activation by the p53 Tumor Suppressor
Authors: Dobner Thomas , Horikoshi Nobuo , Rubenwolf Susanne , Shenk Thomas
Published: October 2006

The adenovirus E4orf6 protein is shown here to interact with the cellular tumor suppressor protein p53 and to block p53-mediated transcriptional activation. The adenovirus protein inhibited the ability of p53 to bind to human TAF
II
31, a component of transcription factor IID (TFIID). Earlier work demonstrated that the interaction of p53 with TAF
II
31 involves a sequence near the NH
2
-terminus of p53, whereas the E4orf6-p53 interaction occurs within amino acids 318 to 360 of p53. Thus, the E4orf6 protein interacts at a site on p53 distinct from the domain that binds to TAF
II
31 but nevertheless inhibits the p53-TAF
II
31 interaction.
Evidence That Spt6p Controls Chromatin Structure by a Direct Interaction with Histones
Authors: Bortvin Alex , Winston Fred
Published: October 2006

Genetic analysis has implicated
SPT6
, an essential gene of
Saccharomyces cerevisiae
, in the control of chromatin structure. Mutations in
SPT6
and particular mutations in histone genes are able to overcome transcriptional defects in strains lacking the Snf/Swi protein complex. Here it is shown that an
spt6
mutation causes changes in chromatin structure in vivo. In addition, both in vivo and in vitro experiments provide evidence that Spt6p interacts directly with histones and primarily with histone H3. Consistent with these findings, Spt6p is capable of nucleosome assembly in vitro.
Infection and AIDS in Adult Macaques After Nontraumatic Oral Exposure to Cell-Free SIV
Authors: Baba Timothy W. , Trichel Anita M. , An Li , Liska Vladimir , Martin Louis N. , Murphey-Corb Michael , Ruprecht Ruth M.
Published: October 2006

Unprotected receptive anal intercourse is a well-recognized risk factor for infection with human immunodeficiency virus-type 1 (HIV-1). Isolated human case reports have implicated HIV-1 transmission by oral-genital exposure. Adult macaques exposed nontraumatically to cell-free simian immunodeficiency virus (SIV) through the oral route became infected and developed acquired immunodeficiency syndrome (AIDS). The minimal virus dose needed to achieve systemic infection after oral exposure was 6000 times lower than the minimal dose required to achieve systemic infection after rectal exposure. Thus, unprotected receptive oral intercourse, even in the absence of mucosal lesions, should be added to the list of risk behaviors for HIV-1 transmission.
Principles of Chaperone-Assisted Protein Folding: Differences Between in Vitro and in Vivo Mechanisms
Authors: Frydman Judith , Hartl F. Ulrich
Published: October 2006

Molecular chaperones in the eukaryotic cytosol were shown to interact differently with chemically denatured proteins and their newly translated counterparts. During refolding from denaturant, actin partitioned freely between 70-kilodalton heat shock protein, the bulk cytosol, and the chaperonin TCP1-ring complex. In contrast, during cell-free translation, the chaperones were recruited to the elongating polypeptide and protected it from exposure to the bulk cytosol during folding. Posttranslational cycling between chaperone-bound and free states was observed with subunits of oligomeric proteins and with aberrant polypeptides; this cycling allowed the subunits to assemble and the aberrant polypeptides to be degraded. Thus, folding, oligomerization, and degradation are linked hierarchically to ensure the correct fate of newly synthesized polypeptides.
Small Labs Make Big Targets
Authors: Peterson Kim
Published: October 2006

The Department of Energy's (DOE's) nine multipurpose labs are getting most of the political attention, but it's the 17 smaller, more focused, and less well-known labs that are more likely to get swamped by the changes washing over the department. Especially vulnerable are eight single-purpose facilities with specific missions. While some labs are looking for private-sector owners, others are hoping that powerful friends in Washington will save the day.
Ariane Failure Casts Shadow Over ESA's Science Program
Authors: Hellemans Alexander
Published: October 2006

Brussels—Ariane 5, Europe's latest space launcher, exploded on 4 June, 37 seconds into its first flight. It was carrying an important science payload: a quartet of satellites called Cluster designed to map Earth's magnetosphere. While a board of inquiry is trying to pinpoint the cause—the leading candidate is a software problem—space physicists are trying to figure out a way to resurrect the Cluster project. One satellite could probably be put together quickly, mostly from spare parts, but it will be hard to find the money to duplicate the mission.
IVF Project Stirs Debate Over How to Preserve Pandas
Authors: Zhou Meiyue
Published: October 2006

Beijing—The giant panda has become a symbol of international efforts to protect endangered species. But the so-called “living fossil” also stands at the center of a long-running scientific debate about the appropriate use of technology in China, home to all of the world's approximately 1000 wild pandas as well as nearly 100 living in 29 zoos and research centers. A new project to produce the world's first giant panda conceived by in vitro fertilization (IVF) has pitted advocates of captive breeding techniques against those who favor greater efforts to improve conditions in the wild. That dispute extends into the central government, where officials from the ministry responsible for zoos and captive breeding vie for limited resources with officials from another ministry that oversees wildlife preservation and conservation.
Civil War Leaves Once-Proud Georgian Science in Tatters
Authors: Stone Richard
Published: October 2006

Tbilisi, Georgia—Shortly after declaring independence from the Soviet Union in 1991, the southern republic of Georgia was plunged into almost 2 years of civil war. Although the conflict is now restricted to the breakaway republic of Abkhazia in northwestern Georgia, this country of 5 million people is exhausted—its gross national product is $350 per person, on a par with Mozambique. And not surprisingly, Georgian science, which once boasted a strong math community and a productive suite of optical telescopes, is in crisis. Researchers and government officials are warning that without fundamental reforms, it will be hard to maintain even the best groups.
Gene Linked to Commonest Cancer
Authors: Pennisi Elizabeth
Published: October 2006

Although most skin cancers are triggered by exposure to the sun, some people are genetically predisposed to develop them. People with the rare hereditary condition known as Gorlin's or basal cell nevus syndrome, for example, develop basal cell carcinoma as well as certain developmental abnormalities. Now, two teams of researchers, one of which reports its results on
page 1668
, have identified the gene at fault, and it turns out to be the human version of
patched
, a gene first identified as a component of a key developmental pathway in the fruit fly. Researchers hope that what is already known about
patched
will give them a clearer picture of how the basal cell carcinoma develops, and possibly lead to new, nonsurgical treatments for the skin cancer. In addition, a second paper (
p. 1621
) further clarifies the operation of the pathway to which
patched
belongs
Did Neandertals Lose an Evolutionary "Arms" Race?
Authors: Gibbons Ann
Published: October 2006

It has been called “The Mystery of Mount Carmel,” a riddle embodied in the ancient humans who lived in caves around this Israeli mountain 40,000 to 100,000 years ago. Neandertals and early modern humans were in these caves at about the same time; they hunted the same prey and used similar tools. But only the moderns survived—and the reason why is the mystery, for their behavior seemed so similar. Now differences are beginning to emerge from the bones. Researchers have found that Neandertals' upper arm bones record more vigorous use, perhaps because they were less efficient at processing food. And their hip bones indicate that Neandertals were more active as children, possibly because they had to follow along with the adults as the group hunted and foraged; early modern society, in contrast, might have been organized differently, allowing youngsters to stay safely in camp with baby-sitters. Both differences might have given the early moderns an evolutionary edge.
Polar Clouds and Sulfate Aerosols
Authors: Tolbert Margaret A.
Published: October 2006

Polar stratospheric clouds are known to play an important role in ozone destruction over the north and south poles. One puzzle is how the clouds can continuously form throughout the winter. In her Perspective, Tolbert describes results by Koop and Carslaw (
p. 1638
) that reveal a new pathway for cloud regeneration.
Bacteria Also Vote
Authors: Kaiser Dale
Published: October 2006

A report by Moré
et al
. (
p. 1655
) describes the biosynthesis of an autoinducer from
Agrobacterium tumefaciens
, a molecule that signals bacterial density of a culture (a quorum sensor). The Perspective by Kaiser reviews what is known about autoinducers from a number of microorganisms and speculates about their identity as predecessors of hormone-hormone receptor systems of eukaryotes.
High-Resolution Molecular Spectroscopy of van der Waals Clusters in Liquid Helium Droplets
Authors: Hartmann Matthias , Miller Roger E. , Toennies J. Peter , Vilesov Andrej F.
Published: October 2006

Small van der Waals clusters of sulfur hexafluoride (SF
6
) and mixed SF
6
-rare gas clusters were prepared inside large droplets of helium-4, with each droplet consisting of about 4000 helium atoms. A diode laser was used to measure the high-resolution infrared spectra of these clusters in the vicinity of the ν
3
vibrational mode. In all cases rotational structure was observed, indicating that the embedded species rotate nearly freely, although they had been cooled to a temperature of 0.37 kelvin. The results indicate that helium droplets are probably superfluid and thereby provide a uniquely cold yet gentle matrix for high-resolution spectroscopy.
Direct pH Measurement of NaCl-Bearing Fluid with an in Situ Sensor at 400°C and 40 Megapascals
Authors: Ding Kang , Seyfried William E.
Published: October 2006

The pH of concentrated NaCl-HCl fluids (0.57 mole of NaCl per kilogram of water) has been measured at supercritical conditions of water with a yttria-stabilized zirconia sensor in a titanium flow reactor. At 400°C and 40 megapascals, the in situ pH of the fluids, ranging from 3.3 to 6.2, differs greatly from its original value of 1.9 to 7.6 at ambient conditions. The measurements agree well with theoretical predictions, showing strong associations of HCl° and NaOH° complexes in high-temperature fluids. The pH sensor provides a powerful tool to investigate unambiguously the distribution of species in aqueous fluids at elevated temperatures and pressures.
Melting of H
2
SO
4
⋅4H
2
O Particles upon Cooling: Implications for Polar Stratospheric Clouds
Authors: Koop Thomas , Carslaw Kenneth S.
Published: October 2006

Polar stratospheric clouds (PSCs) are important for the chemical activation of chlorine compounds and subsequent ozone depletion. Solid PSCs can form on sulfuric acid tetrahydrate (SAT) (H
2
SO
4
⋅4H
2
O) nuclei, but recent laboratory experiments have shown that PSC nucleation on SAT is strongly hindered. A PSC formation mechanism is proposed in which SAT particles melt upon cooling in the presence of HNO
3
to form liquid HNO
3
-H
2
SO
4
-H
2
O droplets 2 to 3 kelvin above the ice frost point. This mechanism offers a PSC formation temperature that is defined by the ambient conditions and sets a temperature limit below which PSCs should form.
A Quasi-Monoclonal Mouse
Authors: Cascalho Marilia , Ma Audrey , Lee Steven , Masat Linda , Wabl Matthias
Published: October 2006

As a model for studying the generation of antibody diversity, a gene-targeted mouse was produced that is hemizygous for a rearranged V(D)J segment at the immunoglobulin (Ig) heavy chain locus, the other allele being nonfunctional. The mouse also has no functional kappa light chain allele. The heavy chain, when paired with any lambda light chain, is specific for the hapten (4-hydroxy-3-nitrophenyl) acetyl (NP). The primary repertoire of this quasi-monoclonal mouse is monospecific, but somatic hypermutation and secondary rearrangements change the specificity of 20 percent of the antigen receptors on B cells. The serum concentrations of the Ig isotypes are similar to those in nontransgenic littermates, but less than half of the serum IgM binds to NP, and none of the other isotypes do. Thus, neither network interactions nor random activation of a small fraction of the B cell population can account for serum Ig concentrations.
Enzymatic Synthesis of a Quorum-Sensing Autoinducer Through Use of Defined Substrates
Authors: Moré Margret I. , Finger L. David , Stryker Joel L. , Fuqua Clay , Eberhard Anatol , Winans Stephen C.
Published: October 2006

Many bacteria, including several pathogens of plants and humans, use a pheromone called an autoinducer to regulate gene expression in a cell density-dependent manner.
Agrobacterium
autoinducer [AAI,
N
-(3-oxo-octanoyl)-L-homoserine lactone] of
A. tumefaciens
is synthesized by the TraI protein, which is encoded by the tumor-inducing plasmid. Purified hexahistidinyl-TraI (H
6
-TraI) used
S
-adenosylmethionine to make the homoserine lactone moiety of AAI, but did not use related compounds. H
6
-TraI used 3-oxo-octanoyl-acyl carrier protein to make the 3-oxo-octanoyl moiety of AAI, but did not use 3-oxo-octanoyl-coenzyme A. These results demonstrate the enzymatic synthesis of an autoinducer through the use of purified substrates.
Activation of Gal4p by Galactose-Dependent Interaction of Galactokinase and Gal80p
Authors: Zenke F. T. , Engels R. , Vollenbroich V. , Meyer J. , Hollenberg C. P. , Breunig K. D.
Published: October 2006

Yeast galactokinase (Gal1p) is an enzyme and a regulator of transcription. In addition to phosphorylating galactose, Gal1p activates Gal4p, the activator of
GAL
genes, but the mechanism of this regulation has been unclear. Here, biochemical and genetic evidence is presented to show that Gal1p activates Gal4p by direct interaction with the Gal4p inhibitor Gal80p. Interaction requires galactose, adenosine triphosphate, and the regulatory function of Gal1p. These data indicate that Gal1p-Gal80p complex formation results in the inactivation of Gal80p, thereby transmitting the galactose signal to Gal4p.
Optical Imaging of Functional Organization in the Monkey Inferotemporal Cortex
Authors: Wang Gang , Tanaka Keiji , Tanifuji Manabu
Published: October 2006

To investigate the functional organization of object recognition, the technique of optical imaging was applied to the primate inferotemporal cortex, which is thought to be essential for object recognition. The features critical for the activation of single cells were first determined in unit recordings with electrodes. In the subsequent optical imaging, presentation of the critical features activated patchy regions around 0.5 millimeters in diameter, covering the site of the electrode penetration at which the critical feature had been determined. Because signals in optical imaging reflect average neuronal activities in the regions, the result directly indicates the regional clustering of cells responding to similar features.
Human Homolog of

patched

, a Candidate Gene for the Basal Cell Nevus Syndrome
Authors: Johnson Ronald L. , Rothman Alana L. , Xie Jingwu , Goodrich Lisa V. , Bare John W. , Bonifas Jeannette M. , Quinn Anthony G. , Myers Richard M. , Cox David R. , Epstein Ervin H. , Scott Matthew P.
Published: October 2006

The basal cell nevus syndrome (BCNS) is characterized by developmental abnormalities and by the postnatal occurrence of cancers, especially basal cell carcinomas (BCCs), the most common human cancer. Heritable mutations in BCNS patients and a somatic mutation in a sporadic BCC were identified in a human homolog of the
Drosophila patched (ptc)
gene. The
ptc
gene encodes a transmembrane protein that in
Drosophila
acts in opposition to the Hedgehog signaling protein, controlling cell fates, patterning, and growth in numerous tissues. The human
PTC
gene appears to be crucial for proper embryonic development and for tumor suppression.
Hot Property: Biologists Who Compute
Authors: Marshall Eliot
Published: October 2006

Drug companies, hoping to mine biological databases for information that will lead to new products, are buying up experts in genetics and computer science. Competition for people skilled in bioinformatics is so intense that salary offers are being driven sky-high and there is concern that the universities—few of which are training students in the field—are rapidly being depleted of the best researchers.
From Genes to Genome Biology
Authors: Pennisi Elizabeth
Published: October 2006

The reams of data pouring in from genome projects render traditional gene-by-gene methods of analysis too slow for impatient geneticists. So researchers are designing a new generation of genome-probing techniques—ranging from laboratory screens to computer programs—to handle whole batches of genes simultaneously. Such industrial-strength approaches allow researchers to rapidly learn what genes actually do, and to ask new questions about entire genomes. Potential applications range from cancer research to DNA forensics.
Form Follows Function When Plants Harvest Light
Authors: Moffat Anne Simon
Published: October 2006

Recent structural studies, including one reported in this issue (
p. 1788
), have been clarifying how photosynthetic organisms, ranging from bacteria to single-celled algae to higher plants, harvest the light they need. They show that the organisms' light-harvesting centers are carefully tailored to each species' ecological niche.
Room-Temperature Blue Gallium Nitride Laser Diode
Authors: Fasol G.
Published: October 2006

In December 1995, a researcher at a medium-sized company in Japan announced the development of a long-sought device—a laser diode operating at room temperature that emits blue light. In his Perspective, Fasol describes the development of this device, which may have major applications in optical data storage and computer displays, and the corporate culture that fostered its creation.
Receptor Tails Unlock Developmental Checkpoints for B Lymphocytes
Authors: Roth Patricia E. , DeFranco Anthony L.
Published: October 2006

Two reports, one previously published in
Science
(Gong and Nussenzweig, 19 April,
p. 411
) and one in this week's issue (Torres
et al
.,
p. 1804
), report the surprising phenotypes of genetically engineered (knockout) mice missing the Ig-alpha and Ig-beta accessory proteins of the B cell antigen receptor. DeFranco and Roth discuss in their Perspective how the characteristics of these mice reveal two new checkpoints in the developmental pathway of the B cell.
Remapping the Brain
Authors: Freund Hans-Joachim
Published: October 2006

A report by Nudo
et al
. (
p. 1791
) show that after a stroke (simulated in a monkey), training the animal with certain tasks can limit the subsequent dysfunctional reorganization of the brain. These tasks engage the body part that is mapped at the injured site. In his Perspective, Freund discusses the implications of these results for rehabilitation.
Quantifying Transport Between the Tropical and Mid-Latitude Lower Stratosphere
Authors: Volk C. M. , Elkins J. W. , Fahey D. W. , Salawitch R. J. , Dutton G. S. , Gilligan J. M. , Proffitt M. H. , Loewenstein M. , Podolske J. R. , Minschwaner K. , Margitan J. J. , Chan K. R.
Published: October 2006

Airborne in situ observations of molecules with a wide range of lifetimes (methane, nitrous oxide, reactive nitrogen, ozone, chlorinated halocarbons, and halon-1211), used in a tropical tracer model, show that mid-latitude air is entrained into the tropical lower stratosphere within about 13.5 months; transport is faster in the reverse direction. Because exchange with the tropics is slower than global photochemical models generally assume, ozone at mid-latitudes appears to be more sensitive to elevated levels of industrial chlorine than is currently predicted. Nevertheless, about 45 percent of air in the tropical ascent region at 21 kilometers is of mid-latitude origin, implying that emissions from supersonic aircraft could reach the middle stratosphere.