bluuebunny/crossref_metadata_2025 huggingface dataset:
Dogfight Erupts Over Animal Studies in the Serengeti
Authors: Morell Virginia
Published: October 2006

The last wild dogs being studied in Tanzania's Serengeti National Park have died, and some researchers point their fingers at scientists studying the animals, arguing that handling—with radio collars and darts—so stressed the dogs that they succumbed to rabies infections. Wildlife biologists vigorously dispute the scientific basis of this hypothesis in a current publication and say the charges have hampered a variety of wildlife studies.
Designer Cytokines: Targeting Actions to Cells of Choice
Authors: Economides Aris N. , Ravetch Jeffrey V. , Yancopoulos George D. , Stahl Neil
Published: October 2006

Some growth factors are therapeutically useful partly because restricted expression of their receptors limits their action to particular cell types. However, no unique stimulatory factor is known for many clinically relevant cell types, such as CD34
+
hematopoietic stem cells. Here, soluble α receptor (Rα) components for interleukin-6 (IL-6) and ciliary neurotrophic factor (CNTF) were targeted in an active form to cells expressing surface markers such as CD34 or CD45, thereby rendering those cells responsive to IL-6 or CNTF. The targeting of Rα components may provide the means to create "designer" cytokines that activate a desired cell type expressing a specific cell surface marker.
Cytotoxic T Lymphocyte Lysis Inhibited by Viable HIV Mutants
Authors: Meier Ute-Christiane , Klenerman Paul , Griffin Philip , James William , Köppe Britta , Larder Brendan , McMichael Andrew , Phillips Rodney
Published: October 2006

Immune evasion by the human immunodeficiency virus (HIV) is unexplained but may involve the mutation of viral antigens. When cytotoxic T lymphocytes engaged CD4-positive cells that were acutely infected with HIV bearing natural variant epitopes in reverse transcriptase, substantial inhibition of specific antiviral lysis was observed. Mutant viruses capable of these transactive effects could facilitate the persistence of a broad range of HIV variants in the face of an active and specific immune response.
Panel Urges New Approach to Inquiries
Authors: Kaiser Jocelyn
Published: October 2006

A commission looking at the operations of the federal Office of Research Integrity has recommended that it stick to investigating allegations of misconduct and leave others with the job of determining guilt and meting out punishment. The outside panel has also proposed a new way to define scientific misconduct.
Pressure on Budget Triggers Review of Antarctic Program
Authors: Mervis Jeffrey
Published: October 2006

Can the United States still afford the world's largest scientific program in Antarctica? And does it serve U.S. interests? Congress wants answers from the Clinton Administration before next year's round of budget negotiations.
Found: A Star Too Small to Shine
Authors: Glanz James
Published: October 2006

When a star forms with a mass of less than about 80 Jupiters, its nuclear furnaces shouldn't ignite at all or should quickly flicker out. But reports of these brown dwarfs, which give off only a faint red glow as they collapse under gravity, have been controversial. Now the detection of methane—a gas that could never survive in a full-fledged star—in a brown dwarf candidate confirms that it is the real thing.
Venus Reconsidered
Authors: Kaula William M.
Published: October 2006

The Magellan imagery shows that Venus has a crater abundance equivalent to a surface age of 300 million to 500 million years and a crater distribution close to random. Hence, the tectonics of Venus must be quiescent compared to those of Earth in the last few 100 million years. The main debate is whether the decline in tectonic activity on Venus is closer to monotonic or episodic, with enhanced tectonism and volcanism yet to come. The former hypothesis implies that most radioactive heat sources have been differentiated upward; the latter, that they have remained at depth. The low level of activity in the last few 100 million years inferred from imagery favors the monotonic hypothesis; some chemical evidence, particularly the low abundance of radiogenic argon, favors the episodic. A problem for both hypotheses is the rapid decline of thermal and tectonic activity some 300 million to 500 million years ago. The nature of the convective instabilities that caused the decline, and their propagation, are unclear.
Coactivator and Promoter-Selective Properties of RNA Polymerase I TAFs
Authors: Beckmann Holger , Chen Jin-Long , O'Brien Thomas , Tjian Robert
Published: October 2006

Human ribosomal RNA synthesis by RNA polymerase I requires the activator UBF and the promoter selectivity factor SL1, which consists of the TATA binding protein (TBP) and three associated subunits, TAF
I
110, TAF
I
63, and TAF
I
48. Here it is shown that both TAF
I
110 and TAF
I
63 contact the promoter, whereas TAF
I
48 serves as a target for interaction with UBF and is required to form a transcriptionally active SL1 complex responsive to UBF in vitro. TAF
I
48 also alters the ability of TBP to interact with TATA box elements, and the resulting complex fails to support transcription by RNA polymerase II. Thus, TAF
I
48 may function both as a target to mediate UBF activation and as a class-specific promoter selectivity factor.
Elusive HIV-Suppressor Factors Found
Authors: Balter Michael
Published: October 2006

Rome—A team of U.S. and Italian researchers led by Robert Gallo and Paolo Lusso appear to have solved a longstanding mystery in AIDS research. They have identified three previously known immune system molecules that suppress the replication of the AIDS virus, HIV. Researchers had been trying to identify these so-called suppressor factors since they were first postulated by AIDS researcher Jay Levy 6 years ago.
Science
will be publishing a paper describing this finding in the 15 December issue. The news embargo on the research was lifted a week early to coincide with publication by Nature of a letter by Reinhard Kurth and colleagues, announcing the discovery of a different factor that may also play a role in HIV suppression
It's Official: First Glimmer of Greenhouse Warming Seen
Authors: Kerr Richard A.
Published: October 2006

In a report approved last week in Madrid, the Intergovernmental Panel on Climate Change recognized a new scientific consensus that global climate is showing clear signs of greenhouse warming. The key to detecting a human influence on climate was recognizing the cooling effect of the haze that hangs over industrialized regions. By moderating the warming from greenhouse gases and changing its geographic pattern, the haze had obscured greenhouse warming's signature until now. The scientific consensus, however, seems unlikely to quiet the policy debate about controls on greenhouse gases.
Polar Regions Give Cold Shoulder to Theories
Authors: Normile Dennis
Published: October 2006

Tsukuba, Japan—Climate models have predicted that the first effects of global warming might show up in the polar regions, but researchers are having a hard time coming up with solid evidence.
Cell Division: How DNA Replication Originates
Authors: Marx Jean
Published: October 2006

As the cells of higher organisms prepare to divide, they face a tremendous logistic problem: How to copy all of their DNA once—and only once—and at exactly the right time in the cell cycle. Now, in work done mainly in yeast, researchers are finding that this exquisite control of DNA replication is achieved by a complex of proteins interacting with specific short DNA sequences. They've also identified several of the proteins that form the complex, and begun to show how they tie into the machinery of the cell cycle. Work with mammals and other higher eukaryotes is less advanced, but early results suggest that these species use similar proteins for controlling DNA replication.
Quantum Computers, Factoring, and Decoherence
Authors: Chuang I. L. , Laflamme R. , Shor P. W. , Zurek W. H.
Published: October 2006

It is known that quantum computers can dramatically speed up the task of finding factors of large numbers, a problem of practical significance for cryptographic applications. Factors of an
L
-digit number can be found in ∼
L
2
time [compared to ∼exp(
L
1/3
) time] by a quantum computer, which simultaneously follows all paths corresponding to distinct classical inputs, obtaining the solution from the coherent quantum interference of the alternatives. Here it is shown how the decoherence process degrades the interference pattern that emerges from the quantum factoring algorithm. For a quantum computer performing logical operations, an exponential decay of quantum coherence is inevitable. However, even in the presence of exponential decoherence, quantum computation can be useful as long as a sufficiently low decoherence rate can be achieved to allow meaningful results to be extracted from the calculation.
AFM Fabrication of Sub-10-Nanometer Metal-Oxide Devices with in Situ Control of Electrical Properties
Authors: Snow E. S. , Campbell P. M.
Published: October 2006

Metal wires and metal-oxide-metal junctions were fabricated by anodic oxidation with the conducting tip of an atomic force microscope (AFM). The width of the wires and resistance of the junctions were controlled by real-time, in situ measurement of the device resistance during fabrication. Because the properties of nanometer-scale devices are very sensitive to size variations, such measurements provide a more accurate method of controlling device properties than by controlling geometry alone. In this way, structures with critical dimensions of less than 10 nanometers were fabricated with precisely tailored electrical properties.
Can Nuclear Waste Keep Yucca Mountain Dry—and Safe?
Authors: Roush Wade
Published: October 2006

Scientists don't wonder whether nuclear waste will leach out of its containers at the proposed Yucca Mountain repository in Nevada, but when. Researchers have recently proposed a new twist on an old idea: using the waste's own heat to boil corrosive moisture out of the mountain rock and keep the containers dry. By placing storage tunnels more widely apart than has previously been suggested and making some other storage changes, the scientists suggest the tunnels might stay dry for 1 million years. But skeptics point to a few leaks in the current models behind this plan.
Supernova Maser Emission
Authors: Fukui Yasuo
Published: October 2006

Maser emission—the microwave equivalent of laser light—has been observed in interstellar molecules since 1965. Similar maser radiation should be expected from supernova shock waves, but this has been harder to observe. In his Perspective, Fukui discusses images presented in this issue by Yusef-Zadeh
et al
. (
p. 1801
) of maser emission from a supernova near the center of our galaxy. Such observations should permit a better understanding of radiative processes in gas under extreme conditions.
Mechanisms of Gene Activation
Authors: Buratowski Stephen
Published: October 2006

S. Buratowski discusses two papers in this issue of
Science
(Sauer
et al
., pp.
1783
and
1825
) that show that the basal transcription factor complex TFIID is a target of transcriptional activators.
Evidence for Developmentally Programmed Transdifferentiation in Mouse Esophageal Muscle
Authors: Patapoutian Ardem , Wold Barbara J. , Wagner Roger A.
Published: October 2006

Transdifferentiation is a relatively rare phenomenon in which cells of one differentiated type and function switch to a second discrete identity. In vertebrate embryos, smooth muscle and skeletal muscle are distinct tissues that arise from separate compartments of the mesoderm. The musculature of the mouse esophagus was found to undergo a conversion from smooth muscle in the fetus to skeletal muscle during early postnatal development. The switch from smooth to skeletal muscle features the transitory appearance of individual cells expressing a mixed phenotype, which suggests that this conversion is a result of programmed transdifferentiation.
Governing Body Clamps Down On Its New Chief Executive
Authors: Lawler Andrew
Published: October 2006

Harold Liebowitz was elected president of the academy as a write-in candidate on a platform of change. But less than 3 months into his 6-year term, the academy's oversight board decided it didn't like what it was seeing and passed a set of resolutions curbing his powers.
Science Chair Walker Calls It Quits
Authors: Lawler Andrew
Published: October 2006

Representative Robert Walker (R-PA), the first-year chair of the House Science Committee, has decided to go out while he's still on top. Last week he announced he will not seek re-election in November 1996
A New Guide to the Human Genome
Authors: Marx Jean
Published: October 2006

Researchers looking to accomplish the ultimate goal of the Human Genome Project—the complete sequencing of all 3 billion bases in the genome—now have a major new tool to help them. In an article also appearing in this issue (
p. 1945
), Eric Lander's team at the Whitehead Institute for Biomedical Research describes a detailed new physical map of the human genome. Not only is its coverage more complete than that of previous maps, but the landmarks used, which are called sequence-tagged sites, make it more versatile and easier to use. While not yet as detailed as sequencers want, it opens the door to genomewide sequencing.
Monsoon Shrinks with Aerosol Models
Authors: Mudur Ganapati
Published: October 2006

New Delhi, India—Global climate models based on rising carbon dioxide levels predicted wetter monsoons in south Asia. But new models that incorporate an increase in the aerosol haze from pollution in south Asia reverse that prediction for parts of India and China, predicting a decrease in rainfall that could hurt agriculture.
Dendrimers Display Liquid Crystal Talents
Authors: Bradley David
Published: October 2006

Chemists report they've made the first nonspherical dendrimers—densely branched polymers that are usually in the shape of a ball. The new ones are shaped like rods, however, and that asymmetry may allow them to serve as liquid crystals (LCs): the hybrid molecules that flicker between solid and liquid states to form watch and computer displays. It's taken powerful electric fields to make polymers flicker like LCs in the past; the dendrimers flicker much more readily.
Ages of the Oldest Clusters and the Age of the Universe
Authors: van den Bergh Sidney
Published: October 2006

The Hubble parameter is a measure of the size-scale and age of the universe, and its value has been a topic of intense debate. In his Perspective, van den Bergh reviews recent results obtained from observations of galaxy clusters and comments on the sources of the differing values.
An STS-Based Map of the Human Genome
Authors: Hudson Thomas J. , Stein Lincoln D. , Gerety Sebastian S. , Ma Junli , Castle Andrew B. , Silva James , Slonim Donna K. , Baptista Rafael , Kruglyak Leonid , Xu Shu-Hua , Hu Xintong , Colbert Angela M. E. , Rosenberg Carl , Reeve-Daly Mary Pat , Rozen Steve , Hui Lester , Wu Xiaoyun , Vestergaard Christina , Wilson Kimberly M. , Bae Jane S. , Maitra Shanak , Ganiatsas Soula , Evans Cheryl A. , DeAngelis Margaret M. , Ingalls Kimberly A. , Nahf Robert W. , Horton Lloyd T. , Anderson Michele Oskin , Collymore Alville J. , Ye Wenjuan , Kouyoumjian Vardouhie , Zemsteva Irena S. , Tam James , Devine Richard , Courtney Dorothy F. , Renaud Michelle Turner , Nguyen Huy , O'Connor Tara J. , Fizames Cécile , Fauré Sabine , Gyapay Gabor , Dib Colette , Morissette Jean , Orlin James B. , Birren Bruce W. , Goodman Nathan , Weissenbach Jean , Hawkins Trevor L. , Foote Simon , Page David C. , Lander Eric S.
Published: October 2006

A physical map has been constructed of the human genome containing 15,086 sequence-tagged sites (STSs), with an average spacing of 199 kilobases. The project involved assembly of a radiation hybrid map of the human genome containing 6193 loci and incorporated a genetic linkage map of the human genome containing 5264 loci. This information was combined with the results of STS-content screening of 10,850 loci against a yeast artificial chromosome library to produce an integrated map, anchored by the radiation hybrid and genetic maps. The map provides radiation hybrid coverage of 99 percent and physical coverage of 94 percent of the human genome. The map also represents an early step in an international project to generate a transcript map of the human genome, with more than 3235 expressed sequences localized. The STSs in the map provide a scaffold for initiating large-scale sequencing of the human genome.
Role of Langmuir Circulation in the Deepening of the Ocean Surface Mixed Layer
Authors: Li Ming , Zahariev Konstantin , Garrett Chris
Published: October 2006

Helical motions, known as Langmuir circulation, are a key physical process in the upper ocean but have not yet been incorporated into ocean models. Here, surface mixed layer deepening by Langmuir circulation was added to that due to convection or velocity shear; Langmuir circulation is more important than shear if the velocity difference across the mixed-layer base is less than about 1 percent of the wind speed. In an upper ocean data set, evidence was found for the deepening of the mixed layer by both mechanisms. Thus, Langmuir circulation influences upper ocean diurnal and seasonal changes in stratification.
Med Schools Receive Hughes Windfall
Authors: Kaiser Jocelyn
Published: October 2006

The Howard Hughes Medical Institute is providing grants worth a total of $80 million to 30 U.S. medical schools to shore up their capacity for doing biomedical research. Medical schools have been hit by shrinking federal grants and limits on health insurance coverage, while Hughes's $8 billion endowment has benefited from the stock market boom of 1995. The grants will channel some of that windfall into making sure that medical schools remain at the cutting edge of research.
Pacific Basin Gathering in Hawaii Fills With Chemists
Authors: Service Robert F.
Published: October 2006

From 17 to 22 December, chemists from around the Pacific Rim converged on Honolulu, Hawaii, for an assembly held every 6 years: the International Chemical Congress of Pacific Basin Societies. The researchers heard reports of many advances, including the invention of square molecules with twists and plants engineered to make insect-killing viruses.
Selector Genes, Polymorphisms, and Evolution
Authors: Tautz Diethard
Published: October 2006

Evolution has been thought to act on small changes in the characteristics of organisms coded by genes called realizator genes. D. Tautz explains how a new result in this issue of
Science
by Gibson and Hogness (
p. 200
) shows that this may not always be true. A small phenotypic variation in
Drosophila
(sensitivity to ether), apparent only under environmental stress, turns out to be coded by a polymorphism in a selector gene,
Ultrabithorax
, a member of a class of genes that specifies whole body parts and anatomical regions.
AMS Adds Realism to Chemical Risk Assessment
Authors: Weisman Jonathan
Published: October 2006

To judge the biological risk of trace compounds, researchers traditionally give huge doses to a rat—a procedure of questionable relevance to human beings exposed to normal doses. Accelerator mass spectrometry (AMS), a technique borrowed from archaeology that can detect trace amounts of an isotope, is opening a view of the biological activity of smaller doses. The idea is to tag the suspect compound with carbon-14, feed a “normal” dose to a rat, and use AMS to track down the telltale isotope in the rat's tissues.
New U.K. Committee Draws Fire
Authors: Williams Nigel
Published: October 2006

London—Last week the British government announced what it believes to be a world first: a new commission to advise it on genetic testing. But the announcement instantly prompted a storm of protest from the House of Commons' science and technology committee, the body that originally suggested the new commission, which argued that the commission's purview—which omits issues such as insurance, patenting, and public education—is too narrow.
Closing In On Superconductivity
Authors: Clery Daniel
Published: October 2006

For nearly a decade, two camps have been battling to explain how complex new crystals can conduct electricity at high temperatures without resistance. Now one camp says an elegant new result reported on
page.329
—favoring behavior in superconducting electrons known as “d-wave”—knocks many opposing ideas out of the running for good.
Choreographing the Bacterial Cell Cycle
Authors: Roush Wade
Published: October 2006

In the careful dance of a bacterial cell's life, particular movements, such as cell division or the development of particular cell structures, occur only after previous steps are completed. But scientists haven't been able to find a master choreographer—until now. In an aquatic bacterium, researchers report finding a gene whose product coordinates the formation of a propellerlike flagellum with several other critical events, including DNA replication.
Newly Learned Auditory Responses Mediated by NMDA Receptors in the Owl Inferior Colliculus
Authors: Feldman Daniel E. , Brainard Michael S. , Knudsen Eric I.
Published: October 2006

Alignment of auditory and visual receptive fields in the optic tectum of the barn owl (
Tyto alba
) is maintained through experience-dependent modification of auditory responses in the external nucleus of the inferior colliculus (ICX), which provides auditory input to the tectum. Newly learned tectal auditory responses, induced by altered visual experience, were found to be pharmacologically distinct from normal responses expressed at the same tectal sites.
N
-methyl-D-aspartate (NMDA) receptor antagonists administered systemically or applied locally in the ICX reduced learned responses more than normal responses. This differential blockade was not observed with non-NMDA or broad-spectrum antagonists. Thus, NMDA receptors preferentially mediate the expression of novel neuronal responses induced by experience during development.
Seeking Out Strange New Worlds
Authors: Goldsmith Donald
Published: October 2006

Now that astronomers searching for planets around other stars have detected Jupiter-sized objects, another goal beckons: finding planets more like Earth. NASA Administrator Daniel Goldin is an enthusiast, and a panel of leading astronomers has just endorsed a “road map” for the search. Ultimately, it would require placing an array of infrared telescopes in an orbit beyond Mars.
Hearing Highlights Hopes, Realities
Authors: Mervis Jeffrey
Published: October 2006

A 4-hour hearing by three House subcommittees featured rare bipartisan agreement on the need for the federal government to do more to promote oceanographic research—even if there's no new money to spend.
Galileo Hits a Strange Spot on Jupiter
Authors: Kerr Richard A.
Published: October 2006

Planetary scientists hoped that the free-flying probe released into Jupiter's atmosphere by the spacecraft Galileo would return results they could use to help understand the formation of the gas giant and of the whole solar system. But thanks to a piece of bad luck, the probe came down in an uncharacteristically hot, dry, and cloudless spot—essentially a Jovian Sahara—dashing those hopes at least for now. Still, the data are offering new insights into Jupiter's weather, possibly helping resolve a debate about the origins of the planet's strong winds.
Will a Computer Checkmate a Chess Champion at Last?
Authors: Cipra Barry
Published: October 2006

In a series of games in Philadelphia beginning on 10 February, chess master Gary Kasparov will go face-to-interface with Deep Blue, a computer chess program developed at IBM. Some experts think that for the first time, a computer has a chance of beating a human champion. Building on the latest techniques, Deep Blue's strategy is not to outsmart its opponent but to outsearch him, by looking many moves ahead and ferreting out what looks like the best line of play. Computers/Math
Crystal and Molecular Structures of Hexamethyltungsten and Hexamethylrhenium
Authors: Pfennig Valerie , Seppelt Konrad
Published: October 2006

The structure of hexamethyltungsten, W(CH
3
)
6
, was determined by x-ray single-crystal diffraction at −163°C. The molecule has a strongly distorted trigonal prismatic structure with
C

3
ν

symmetry. This irregular structure is not a result of intermolecular forces, but rather represents its true molecular structure. A similar structure, which deviates less from the ideal trigonal prismatic structure, was determined for hexamethylrhenium, Re(CH
3
)
6
. Although these structures violate the simplistic models used to predict the geometry of molecules, they are at least in part explainable by the molecular orbital model.
Overview: European Universities in Transition
Authors: Clery Daniel
Published: October 2006

All across Europe, university systems are being revamped, but the forces driving these changes and the responses to them are far from uniform. Germany and France are struggling to cope with more students while funding has stagnated; the United Kingdom is broadening access to university education while stimulating more competition among institutions; the Netherlands is trying to shorten the time it takes students to graduate; and the former countries of the Soviet bloc are struggling with the legacy of communism—the separation of research and teaching, and limited finances. This special issue examines these trends in eight countries
Galactic Building Blocks Found?
Authors: Glanz James
Published: October 2006

Although astronomers have long suspected that galaxies form from the bottom up, with small structures merging into larger ones, they have not previously detected the subgalactic clumps of gas and newborn stars that serve as the building blocks. Now, perhaps, they have, although not everyone is as yet convinced.
Collisions Hint That Quarks Might Not Be Indivisible
Authors: Glanz James
Published: October 2006

Batavia, Illinois—In a year's harvest of data from the Tevatron particle accelerator at the Fermi National Accelerator Laboratory, a large collaboration of physicists has found hints that quarks may have internal structure. Because quarks are now thought to be fundamental particles, the evidence—a slight excess in the number of sideways jets of debris spurting from proton-antiproton collisions—could challenge the reigning theory of matter. But the Fermilab physicists caution that there are other, less revolutionary, ways to explain the data.
Direct Visualization of A-, P-, and E-Site Transfer RNAs in the
Escherichia coli
Ribosome
Authors: Agrawal Rajendra K. , Penczek Pawel , Grassucci Robert A. , Li Yanhong , Leith ArDean , Nierhaus Knud H. , Frank Joachim
Published: October 2006

Transfer RNA (tRNA) molecules play a crucial role in protein biosynthesis in all organisms. Their interactions with ribosomes mediate the translation of genetic messages into polypeptides. Three tRNAs bound to the
Escherichia coli
70
S
ribosome were visualized directly with cryoelectron microscopy and three-dimensional reconstruction. The detailed arrangement of A- and P-site tRNAs inferred from this study allows localization of the sites for anticodon interaction and peptide bond formation on the ribosome.
Evolving Rhythms
Authors: Morell Virginia
Published: October 2006

The circadian clock, the body's light-sensitive timekeeper, functions in a similar manner, with similar components, throughout the vertebrate lineage, indicating it arose as the lineage did, about 450 million years ago. But its components fit together in slightly different ways in different animals, pointing to a degree of plasticity and adaptability.
Researchers Nail Down Leptin Receptor
Authors: Barinaga Marcia
Published: October 2006

During the past 18 months, researchers have learned a great deal about what causes obesity, identifying first a hormone, called leptin, needed for normal weight maintenance, as well as a possible candidate for the hormone's receptor. Now three groups, one of which reports its findings on
page 994
, have confirmed that they have indeed found the right receptor by showing that it's the product of the
db
gene, which has long been thought to encode the receptor for the weight-controlling hormone. What's more, they have shown how
db
mutations might lead to an inactive product—and grossly overweight mice as a result.
New Images Wet Researchers' Appetites
Authors: Clery Daniel
Published: October 2006

Chilton, Oxfordshire—The first images from the European Space Agency's Infrared Satellite Observer (ISO) have detected signs of water vapor in a planetary nebula. It is the first signature of water vapor from outside the solar system, and its occurrence along with carbon monoxide is a surprise. This is just one of several intriguing results from the first data sent back by ISO and is raising astronomer's expectations for the rest of the mission.
Congenital Jaundice in Rats with a Mutation in a Multidrug Resistance-Associated Protein Gene
Authors: Paulusma Coen C. , Bosma Piter J. , Zaman Guido J. R. , Bakker Conny T. M. , Otter Marlies , Scheffer George L. , Scheper Rik J. , Borst Piet , Elferink Ronald P. J. Oude
Published: October 2006

The human Dubin-Johnson syndrome and its animal model, the TR
−
rat, are characterized by a chronic conjugated hyperbilirubinemia. TR
−
rats are defective in the canalicular multispecific organic anion transporter (cMOAT), which mediates hepatobiliary excretion of numerous organic anions. The complementary DNA for rat c
moat
, a homolog of the human multidrug resistance gene (h
MRP1
), was isolated and shown to be expressed in the canalicular membrane of hepatocytes. In the TR
−
rat, a single-nucleotide deletion in this gene resulted in a reduced messenger RNA level and absence of the protein. It is likely that this mutation accounts for the TR
−
phenotype.
The Whole Lactose Repressor
Authors: Matthews Kathleen S.
Published: October 2006

The lactose repressor turns the bacterial genes for lactose metabolism on and off. This system has served as a blueprint for the study of both eukaryotic and prokaryotic gene regulation for decades. In this issue of
Science
, the crystal structure of the whole lactose repressor in a complex with DNA and its inducer is reported. In her Perspective, K. Matthews discusses the significance of this landmark event.
Crystal Structure of the Lactose Operon Repressor and Its Complexes with DNA and Inducer
Authors: Lewis Mitchell , Chang Geoffrey , Horton Nancy C. , Kercher Michele A. , Pace Helen C. , Schumacher Maria A. , Brennan Richard G. , Lu Ponzy
Published: October 2006

The
lac
operon of
Escherichia coli
is the paradigm for gene regulation. Its key component is the
lac
repressor, a product of the
lacI
gene. The three-dimensional structures of the intact
lac
repressor, the
lac
repressor bound to the gratuitous inducer isopropyl-β-D-1-thiogalactoside (IPTG) and the
lac
repressor complexed with a 21-base pair symmetric operator DNA have been determined. These three structures show the conformation of the molecule in both the induced and repressed states and provide a framework for understanding a wealth of biochemical and genetic information. The DNA sequence of the
lac
operon has three
lac
repressor recognition sites in a stretch of 500 base pairs. The crystallographic structure of the complex with DNA suggests that the tetrameric repressor functions synergistically with catabolite gene activator protein (CAP) and participates in the quaternary formation of repression loops in which one tetrameric repressor interacts simultaneously with two sites on the genomic DNA.
A Distinct G
1
Step Required to Specify the Chinese Hamster DHFR Replication Origin
Authors: Wu Jia-Rui , Gilbert David M.
Published: October 2006

Nuclei isolated from Chinese hamster ovary (CHO) cells at various times during the G
1
phase of the cell cycle were stimulated to enter S phase by incubation in
Xenopus
egg cytosol. Replication of DNA initiated within the dihydrofolate reductase (DHFR) origin locus in nuclei isolated late in G
1
, but at random sites in nuclei isolated early in G
1
. A discrete transition point occurred 3 to 4 hours after metaphase. Neither replication licensing nor nuclear assembly was sufficient for origin recognition. Thus, a distinct cell cycle-regulated event in the nucleus restricts the initiation of replication to specific sites downstream of the DHFR gene.
Blocked Ras Activation in Anergic CD4
+
T Cells
Authors: Fields Patrick E. , Gajewski Thomas F. , Fitch Frank W.
Published: October 2006

T cell anergy is a state of functional unresponsiveness characterized by the inability to produce interleukin-2 (IL-2) upon T cell receptor stimulation. The mitogen-activated protein kinases ERK-1 and ERK-2 and the guanosine triphosphate-binding protein p21
Ras
were found to remain unactivated upon stimulation of anergic murine T helper cell 1 clones. The inability to activate the Ras pathway did not result from a defect in association among Shc, Grb-2, and murine Son of Sevenless, nor from a defect in their tyrosine phosphorylation. This block in Ras activation may lead to defective transactivation at activator protein 1 sites in anergic cells and may enable T cells to shut down IL-2 production selectively during anergy.
Catalytic Role of 2′-Hydroxyl Groups Within a Group II Intron Active Site
Authors: Abramovitz Dana L. , Friedman Richard A. , Pyle Anna Marie
Published: October 2006

Domain 5 is an essential active-site component of group II intron ribozymes. The role of backbone substituents in D5 function was explored through synthesis of a series of derivatives containing deoxynucleotides at each position along the D5 strand. Kinetic screens revealed that eight 2′-hydroxyl groups were likely to be critical for activity of D5. Through two separate methods, including competitive inhibition and direct kinetic analysis, effects on binding and chemistry were distinguished. Depending on their function, important 2′-hydroxyl groups lie on opposite faces of the molecule, defining distinct loci for molecular recognition and catalysis by D5.
A Fleet Too Good to Afford?
Authors: Mervis Jeffrey
Published: October 2006

The U.S. research fleet, with three new vessels, may be the best in the world. But rising costs and tightening budgets could leave scientists high and dry. A consortium of ship operators hopes to gain business from other federal agencies that now go to sea on their own ships, while a National Research Council panel thinks there may be a better way to coordinate the nation's oceanographic assets.
Protein Motors May Drive Cells on Route to Specialization
Authors: Roush Wade
Published: October 2006

The ability of parent cells to send progeny on a new and different course underlies all complex life, and researchers are beginning to learn how this happens from yeast. Mother yeast cells are sexually ambidextrous, able to switch between two mating types. But their daughters lack this switching ability. The reason, according to recent research, may lie in a cellular railway running between mother and daughter. Moving along cytoskeletal “railway tracks,” motor proteins shuttle in an unknown regulatory factor that, working through a newly discovered protein called Ash1p, prevents mating-type switching. This pathway is now one of the most carefully mapped journeys toward cell specialization known.
Teetering on the Brink of Danger
Authors: Pennisi Elizabeth
Published: October 2006

For 5 decades, immunologists have thought that during embryonic development and early life, the immune system learns to distinguish “self” antigens, which are found on the body's own tissues, from “nonself” antigens, such as invading pathogens. This idea sprang partly from experiments in which Peter Medawar showed that fetal mice can become tolerant to transplanted tissues from immunologically different donors, presumably because the neonates' immune systems accept them as self, just as they accept the animals' own tissues. But three papers in this issue have undermined the experimental basis of the self-nonself theory by showing that immunity can be induced in newborn mice under the right conditions. And conversely, tolerance can be induced in adults. The new work may not only have clinical implications, such as effective vaccines for infants or better success rates for organ transplantation, but it also opens the door to a new theory of how the immune system is activated: Instead of distinguishing self from nonself, it may spring into action when an antigen is associated with harm—the danger theory, its proponents call it.
Shock Forges Piece of Jovian Interior
Authors: Kerr Richard A.
Published: October 2006

The impact of a high-speed projectile at Lawrence Livermore National Laboratory has forged a material never seen before on Earth: a silvery, electrically conducting metallic form of hydrogen. Metallic hydrogen was already thought to make up most of the interiors of the giant planets Jupiter and Saturn, but the Livermore result shows that it forms at lower pressures—closer to each planet's surface—than was thought. That could help explain Jupiter's outsized magnetic field and its powerful winds.
Researchers Find the Reset Button for the Fruit Fly Clock
Authors: Barinaga Marcia
Published: October 2006

One of the more puzzling observations concerning the circadian clock of the fruit fly concerns how it can be reset by light. If the light comes on early at night, it sets the clock back, but if it comes on late it pushes the clock forward. Now four independent groups, two of which describe their work in this issue, have solved the puzzle. They've found that a recently discovered clock protein called TIM (for timeless) is the key. TIM and its partner PER (for period) control the clock by cycling up and down, reaching peak concentrations at night. Light destroys TIM, and when this happens early in the evening when TIM and PER are still being made, it just delays the clock. But later at night, when TIM and PER levels are falling anyway, it accelerates this effect, advancing the clock.
AT-AC Introns—An ATtACk on Dogma
Authors: Mount Stephen M.
Published: October 2006

Messenger RNAs are initially made as long precursor molecules from which final, transcribable mRNAs are assembled. A specialized organelle, the spliceosome, contains small RNAs with pairs of dinucleotides that can pick out complementary pairs of nucleotides at the ends of the introns that are to be spliced together. It has been assumed that these pairs were always GU-AG (or GT-AG in the DNA), but in findings described in this week's issue of
Science
(
p. 1716
) and the current issue of
Cell
(vol. 84, p. 801) a minor class of intron is shown to be flanked by AU-AC (or AT-AC in the DNA). In his Perspective, Mount explains how these maverick introns were discovered and why their existence is so surprising.
Hydrogen—The First Metallic Element
Authors: Hensel Friedrich , Edwards Peter P.
Published: October 2006

Theoretical studies have long predicted that hydrogen will become a metal when subjected to intense pressure, but experimental studies have provided only indirect glimpses of this possibility. In their Perspective, Hensel and Edwards describe results from Lawrence Livermore National Laboratory in which the crucial quantity—electrical conductivity—has been measured as a shock wave passes through liquid hydrogen. As discussed in a news story by Kerr (
p. 1667
), the results have important implications for Jupiter, a planet consisting of hydrogen and helium under high pressure.
Requirement of U12 snRNA for in Vivo Splicing of a Minor Class of Eukaryotic Nuclear Pre-mRNA Introns
Authors: Hall Stephen L. , Padgett Richard A.
Published: October 2006

A conserved sequence element in a minor class of eukaryotic pre-messenger RNA (pre-mRNA) introns was previously proposed to base pair with a complementary sequence in the U12 small nuclear RNA (snRNA) in a manner analogous to the pairing of U2 snRNA with the branch site sequence of the major class of introns. Here, mutations generated in this conserved sequence element block the splicing of a member of this minor intron class in vivo. This block was relieved by coexpression of a U12 snRNA containing compensatory mutations that restore the proposed base pairing interaction. These results show that this minor class of pre-mRNA introns is a distinct class existing alongside the major class of introns in animal genomes, and these results also establish an in vivo function for U12 snRNA.
A Slippery Slope for Science
Authors: Lawler Andrew
Published: October 2006

Last week the White House submitted a 1997 budget request that would add $1 billion to overall spending on civilian R&D. But buried in the fine print of the documents are projections that billions of dollars will be squeezed from many science and technology programs in the next several years, as the government inches toward a balanced budget.
Cash-Starved Researchers to Undergo Trial by Peer Review
Authors: Stone Richard
Published: October 2006

Kiev, Ukraine—Every research group in Ukraine will be subjected to peer review by committees of foreign and Ukrainian scientists. The effort, unprecedented in its scope, is an attempt to channel the country's limited research funds only to the best groups. But it is causing some concern that the reviews will be biased against applied research, which was favored in the Soviet era.
Maintaining Diversity in Science
Authors: Culotta Elizabeth
Published: October 2006

The scientific world has often seemed a bit cool toward women and minorities, but today a constellation of factors ranging from budget cuts to court rulings conspire to create a frigid climate for programs designed to promote diversity in the scientific work force. In this issue, we explore how current political and economic trends may threaten recent advances made by women and underrepresented minorities in the scientific work force, including African Americans, Hispanics, and American Indians.)
☆

Tight budgets are expected to hit women and minorities hardest, in part because diversity programs may be left out in the cold, as reported by
Ann Gibbons
. But even if budgets were ample, such efforts face major legal challenges from recent rulings on affirmative action. Berkeley-based reporter
Marcia Barinaga
untangles the legal threads and their implications for scientists.

Such trends play out in different ways in different disciplines, and we zero in on two fields at opposite ends of the diversity spectrum. In computer science, diversity has actually dropped recently, and
Virginia Morell
explores subtle cultural factors that may help explain why. In contrast, the social sciences are the most diverse in science. But as reported by
Constance Holden
, the overall parity masks a gender split among fields. And ironically, some fear that the influx of women may coincide with lower prestige for the field.

Throughout the section, top-ranked women and minorities offer advice on how to succeed in today's competitive environment; we also present the latest
diversity data
. And Science's Next Wave presents an on-line
forum
on maintaining diversity.

Despite the frosty atmosphere, women and some minorities are still making strides. Stay tuned for updates on how current trends affect their progress.

☆
Asian-Americans, although they face some obstacles common to other minorities, are not underrepresented in science and so are not a focus of this issue. See Science, 12 November 1993,
p. 1117
, and 13 November 1992,
p. 1224
, for articles devoted to Asian-Americans.
An Immune Boost to the War on Cancer
Authors: Williams Nigel
Published: October 2006

As immunologists learn more and more about the molecular workings of the immune system, they are beginning to apply that knowledge in hopes of developing a new generation of vaccines, as well as treatments for a wide range of diseases. Recent efforts aimed at devising new immunotherapies for cancer show the promise, as well as the potential pitfalls, of these efforts. On the one hand, researchers have found that several strategies have produced encouraging results in animals. Among them: genetically engineering tumor cells to boost their ability to generate an anti-tumor immune response and using specific tumor antigens to do the same. But on the other, they know they have their work cut out for them because years of experience have shown that promising animal results often don't translate into success in humans.

Science invites all immunologists to air their opinions on what the realistic prospects are for these immunotherapies and when they are likely to happen. You can respond in a questionnaire. We will collate the responses received for a month after publication and post the results in late May.
Population Dynamics of Immune Responses to Persistent Viruses
Authors: Nowak Martin A. , Bangham Charles R. M.
Published: October 2006

Mathematical models, which are based on a firm understanding of biological interactions, can provide nonintuitive insights into the dynamics of host responses to infectious agents and can suggest new avenues for experimentation. Here, a simple mathematical approach is developed to explore the relation between antiviral immune responses, virus load, and virus diversity. The model results are compared to data on cytotoxic T cell responses and viral diversity in infections with the human T cell leukemia virus (HTLV-1) and the human immunodeficiency virus (HIV-1).
Comet Hyakutake Blazes in X-rays
Authors: Glanz James
Published: October 2006

When a team of astronomers pointed the x-ray satellite ROSAT at Comet Hyakutake 2 weeks ago, they expected to see a faint smudge of x-rays at best. Instead, they picked up an x-ray glow 100 times brighter than even the most optimistic predictions. Now the challenge is to figure out its source: whether solar radiation is causing elements evaporating from the comet to fluoresce, or whether the x-rays come from a shock wave, formed as the sun's wind of charged particles collides with the comet.
Acid Rain's Dirty Business: Stealing Minerals From Soil
Authors: Kaiser Jocelyn
Published: October 2006

Even though the United States, Canada, and European countries have cut the sulfur pollution that leads to acid rain, forests, lakes, and streams haven't bounced back as quickly as expected. On page
244
, a group of researchers reports confirming the reason: The acid has wrought profound changes in the soil. Three decades of data on rain and stream-water chemistry in a New Hampshire forest show that the acid has stripped away the soil's base mineral ions, which buffer, or neutralize, acids and are essential to plant growth. Given the rate at which these ions are still being depleted, it could be decades before the acid-ravaged ecosystems become healthy again.
Imaging and Time-Resolved Spectroscopy of Single Molecules at an Interface
Authors: Macklin J. J. , Trautman J. K. , Harris T. D. , Brus L. E.
Published: October 2006

Far-field microscopy was used to noninvasively measure the room-temperature optical properties of single dye molecules located on a polymer-air interface. Shifts in the fluorescence spectrum, due to perturbation by the locally varying molecular environment, and the orientation of the transition dipole moment were correlated to variation in the excited-state lifetime. The lifetime dependence on spectral shift is argued to result from the frequency dependence of the spontaneous emission rate; the lifetime dependence on dipole orientation was found to be a consequence of the electromagnetic boundary conditions on the fluorescent radiation at the polymer-air interface.
Accurate Processing of a Eukaryotic Precursor Ribosomal RNA by Ribonuclease MRP in Vitro
Authors: Lygerou Zoi , Allmang Christine , Tollervey David , Séraphin Bertrand
Published: October 2006

Very few of the enzymes required for eukaryotic precursor ribosomal RNA (pre-rRNA) processing have been identified. Ribonuclease (RNase) MRP was characterized as a nuclease that cleaves mitochondrial replication primers, but it is predominantly nucleolar. Previous genetic evidence revealed that this ribonucleoprotein is required, directly or indirectly, for cleavage of the yeast pre-rRNA in vivo at site A
3
. Here, an in vitro processing system that accurately reproduces this cleavage is described. Biochemical purification and the use of extracts depleted of the MRP RNA demonstrate that endonucleolytic cleavage of the pre-rRNA is directly mediated by RNase MRP. This establishes a role for RNase MRP in the nucleolus.