bluuebunny/crossref_metadata_2025 huggingface dataset:
Electronics and the Dim Future of the University
Authors: Noam E. M.
Published: October 2006

The growth of electronic media and communication has provided new tools for academics, but also poses several fundamental challenges to the future of universities as centers of research and higher education. One result of the rapid increase in the production and dissemination of information is that the advantage of physical proximity of researchers in universities is diminished. The strength of the university of the future may lie less in pure centers of information and more in college as a community.
Fast Ferroelectric Liquid-Crystal Electrooptics
Authors: Walba David
Published: October 2006

Present and future information technology requires ever faster data transmission rates, but conventional circuitry has serious limitations. In his Perspective, Walba describes a new generation of electrooptical devices based on liquid crystals. These ‘spatial light modulators’ can be integrated with silicon circuits to offer compact, ultrafast optical processing of data.
Unity in Transposition Reactions
Authors: Craig Nancy L.
Published: October 2006

Cells and viruses use transposition reactions under several circumstances to move pieces of DNA around the genome. N. Craig argues that all of these events occur by similar breakage and joining reactions and that transposition proteins are quite similar structurally, in spite of a lack of substantial sequence homology.
A Class of Cobalt Oxide Magnetoresistance Materials Discovered with Combinatorial Synthesis
Authors: Briceño Gabriel , Chang Hauyee , Sun Xiaodong , Schultz Peter G. , Xiang X. -D.
Published: October 2006

The recent development of methods for generating libraries of solid-state compounds has made it possible to apply combinatorial approaches to the discovery of materials. A library of 128 members containing different compositions and stoichiometries of Ln
x
M
y
CoO
δ
, where Ln = Y or La and M = Pb, Ca, Sr, or Ba, was synthesized by a combination of thin-film deposition and physical masking techniques. Large magnetoresistance has been found in La
x
(Ba,Sr,Ca)
y
-CoO
δ
samples, whereas Y-based samples exhibit much smaller magnetoresistive effects. The magnetoresistance of the Co-containing compounds increases as the size of the alkaline earth ion increases, in sharp contrast to Mn-containing compounds, in which the magnetoresistance effect increases as the size of the alkaline earth ion decreases.
Molluscan Diversity in the Late Neogene of Florida: Evidence for a Two-Staged Mass Extinction
Authors: Petuch Edward J.
Published: October 2006

Analyses of recent data show that Floridian molluscan diversity declined markedly during the Pliocene-Pleistocene mass extinction. This decline in diversity was seen at all trophic levels, indicating a complete collapse of the ecosystem. These findings contradict the notion that there was a species diversity stasis throughout the Pliocene-Pleistocene and that the diversity of Pliocene Florida was equivalent to that of Recent Florida. The mass extinction was a two-staged, sequential event. A similar two-staged mass extinction occurred in the Miocene, indicating that two ecological catastrophes in quick geological succession may have produced this mass extinction as well.
Requirement for Generation of H
2
O
2
for Platelet-Derived Growth Factor Signal Transduction
Authors: Sundaresan Maitrayee , Yu Zu-Xi , Ferrans Victor J. , Irani Kaikobad , Finkel Toren
Published: October 2006

Stimulation of rat vascular smooth muscle cells (VSMCs) by platelet-derived growth factor (PDGF) transiently increased the intracellular concentration of hydrogen peroxide (H
2
O
2
). This increase could be blunted by increasing the intracellular concentration of the scavenging enzyme catalase or by the chemical antioxidant
N
-acetylcysteine. The response of VSMCs to PDGF, which includes tyrosine phosphorylation, mitogen-activated protein kinase stimulation, DNA synthesis, and chemotaxis, was inhibited when the growth factor-stimulated rise in H
2
O
2
concentration was blocked. These results suggest that H
2
O
2
may act as a signal-transducing molecule, and they suggest a potential mechanism for the cardioprotective effects of antioxidants.
Speech Recognition with Primarily Temporal Cues
Authors: Shannon Robert V. , Zeng Fan-Gang , Kamath Vivek , Wygonski John , Ekelid Michael
Published: October 2006

Nearly perfect speech recognition was observed under conditions of greatly reduced spectral information. Temporal envelopes of speech were extracted from broad frequency bands and were used to modulate noises of the same bandwidths. This manipulation preserved temporal envelope cues in each band but restricted the listener to severely degraded information on the distribution of spectral energy. The identification of consonants, vowels, and words in simple sentences improved markedly as the number of bands increased; high speech recognition performance was obtained with only three bands of modulated noise. Thus, the presentation of a dynamic temporal pattern in only a few broad spectral regions is sufficient for the recognition of speech.
Increased Cortical Representation of the Fingers of the Left Hand in String Players
Authors: Elbert Thomas , Pantev Christo , Wienbruch Christian , Rockstroh Brigitte , Taub Edward
Published: October 2006

Magnetic source imaging revealed that the cortical representation of the digits of the left hand of string players was larger than that in controls. The effect was smallest for the left thumb, and no such differences were observed for the representations of the right hand digits. The amount of cortical reorganization in the representation of the fingering digits was correlated with the age at which the person had begun to play. These results suggest that the representation of different parts of the body in the primary somatosensory cortex of humans depends on use and changes to conform to the current needs and experiences of the individual.
Entering the Postgenome Era
Authors: Nowak Rachel
Published: October 2006

Genet]icists can now identify about half the estimated 100,000 genes in the human genome, but they don't have a clue about what most of them actually do. Now, two new techniques described in this issue of
Science
could transform research on gene function. They offer two different ways of detecting the expression of hundreds or thousands of genes at a time, thereby allowing researchers to determine which genes are turned on in particular tissues, and at what levels. And that provides a quick way of assessing how gene expression patterns change during development, disease, and other physiological conditions.
Physicist Wins Nobel Peace Prize
Authors: Marshall Eliot
Published: October 2006

British physicist Joseph Rotblat, the only researcher to quit the Manhattan Project on principle, has been awarded the Nobel Peace Prize for his 50-year crusade for nuclear disarmament. Rotblat founded the Pugwash Conferences on Science and World Affairs, a scientists' organization that helped pave the way for several arms-control treaties. The Pugwash group shared the prize.
Did Galaxies Like Our Own Start Life in Chains?
Authors: Appenzeller Tim
Published: October 2006

New observations by the Hubble Space Telescope and the Keck Telescope may have spotted ancestors of present-day spiral galaxies, some 10 billion light-years from Earth. The faint galaxies, which looklike strings of beads, could fill a gap in the early history of galactic evolution, but the evidence is not yet complete.
Transfer of Genes to Humans: Early Lessons and Obstacles to Success
Authors: Crystal Ronald G.
Published: October 2006

Enough information has been gained from clinical trials to allow the conclusion that human gene transfer is feasible, can evoke biologic responses that are relevant to human disease, and can provide important insights into human biology. Adverse events have been uncommon and have been related to the gene delivery strategies, not to the genetic material being transferred. Human gene transfer still faces significant hurdles before it becomes an established therapeutic strategy. However, its accomplishments to date are impressive, and the logic of the potential usefulness of this clinical paradigm continues to be compelling.
The Nematode
Caenorhabditis elegans
and Its Genome
Authors: Hodgkin Jonathan , Plasterk Ronald H. A. , Waterston Robert H.
Published: October 2006

Over the past two decades, the small soil nematode
Caenorhabditis elegans
has become established as a major model system for the study of a great variety of problems in biology and medicine. One of its most significant advantages is its simplicity, both in anatomy and in genomic organization. The entire haploid genetic content amounts to 100 million base pairs of DNA, about 1/30 the size of the human value. As a result,
C. elegans
has also provided a pilot system for the construction of physical maps of larger animal and plant genomes, and subsequently for the complete sequencing of those genomes. By mid-1995, approximately one-fifth of the complete DNA sequence of this animal had been determined.
Caenorhabditis elegans
provides a test bed not only for the development and application of mapping and sequencing technologies, but also for the interpretation and use of complete sequence information. This article reviews the progress so far toward a realizable goal-the total description of the genome of a simple animal.
Superplasticity in Earth's Lower Mantle: Evidence from Seismic Anisotropy and Rock Physics
Authors: Karato Shun-ichiro , Zhang Shuqing , Wenk Hans-Rudolf
Published: October 2006

In contrast to the upper mantle, the lower mantle of the Earth is elastically nearly isotropic, although its dominant constituent mineral [(Mg,Fe)SiO
3
perovskite] is highly anisotropic. On the basis of high-temperature experiments on fabric development in an analog CaTiO
3
perovskite and the elastic constants of MgSiO
3
perovskite, the seismic anisotropy was calculated for the lower mantle. The results show that absence of anisotropy is strong evidence for deformation by superplasticity. In this case, no significant transient creep is expected in the lower mantle and the viscosity of the lower mantle is sensitive to grain size; hence, a reduction in grain size will result in rheological weakening.
Center for the Mind Pleases the Senses
Authors: Cohen Jon
Published: October 2006

La Jolla, California—A neuroscience center with a difference opened last week in southern California. An independent institute headed by Nobel Prize-winner Gerald Edelman, it aims to provide young researchers ample funds to pursue their research for up to 4 years in a setting that encourages interaction.
Metal-Carbon Bonds in Nature
Authors: Kovacs Julie A. , Shoner Steven C. , Ellison Jeffrey J.
Published: October 2006

In contrast to most metabolic processes, but similar to some industrial catalysts, vitamin B
12
contains a cobalt-active species and is sometimes referred to as “nature's organometallic catalyst.” Kovacs
et al
. provide background and commentary to accompany the research report by Kumar
et al
. (
p. 628
) describing a second organometallic intermediate in biology—an active nickel species that serves as a precursor to acetic acid through its reaction with carbon monoxide and acetyl-CoA synthase.
Calcium Sparks in Vascular Smooth Muscle—Relaxation Regulators
Authors: Fay Frederic S.
Published: October 2006

Calcium “sparks” are small, intense bursts of calcium that occur in cells from cardiac muscle, skeletal muscle, and, as shown in a paper in this issue of
Science
by Nelson
et al
. (
p. 633
), smooth muscle. As discussed by F. Fay, these sparks are of particular interest because in smooth muscle they have a unique and unexpected function: They control vasodilation in small arteries of the brain.
Limits to Relief
Authors: Schmidt Kevin M. , Montgomery David R.
Published: October 2006

Comparison of slope profiles in areas exhibiting widespread bedrock landsliding with the use of a model for the maximum size of stable hillslopes established that mountain-scale material strength can limit topographic relief. Conventional laboratory values for intact rock greatly exceeded integrative rock strength properties that were back-calculated from the upper limit to hillslope relief and gradient in the northern Cascade Range and Santa Cruz Mountains. Back-calculated strength values, however, were indistinguishable from those obtained through field and conventional laboratory measurements on the weakest members of each rock formation, as well as on glacial sediments along the Cascade front. These results contrast with the conventional assumption that relief is incision-limited and indicate that the relief of mountain ranges can reflect landscape-scale material strength, as well as the interaction of tectonic and climatic processes.
Localization of Protein Implicated in Establishment of Cell Type to Sites of Asymmetric Division
Authors: Arigoni Fabrizio , Pogliano Kit , Webb Chris D. , Stragier Patrick , Losick Richard
Published: October 2006

Asymmetric division in
Bacillus subtilis
generates progeny cells with dissimilar fates. SpoIIE, a membrane protein required for the establishment of cell type, was shown to localize near sites of potential polar division. SpoIIE initially localizes in a bipolar pattern, coalescing at marks in the cell envelope at which asymmetric division can take place. Then, during division, SpoIIE becomes restricted to the polar septum and is lost from the distal pole. Thus, when division is complete, SpoIIE sits at the boundary between the progeny from which it dictates cell fate by the activation of a cell-specific transcription factor.
Activation of Cell-Specific Transcription by a Serine Phosphatase at the Site of Asymmetric Division
Authors: Duncan Leonard , Alper Scott , Arigoni Fabrizio , Losick Richard , Stragier Patrick
Published: October 2006

Cell fate is determined by cell-specific activation of transcription factor σ
F
after asymmetric division during sporulation by
Bacillus subtilis
. The activity of σ
F
is governed by SpoIIAA, SpoIIAB, and SpoIIE, a membrane protein localized at the polar septum. SpoIIAB binds to and inhibits σ
F
, and SpoIIAA inhibits SpoIIAB, which prevents SpoIIAB from binding to σ
F
. SpoIIAB is also a serine kinase that inactivates SpoIIAA. Here, it is demonstrated that SpoIIE dephosphorylates SpoIIAA-P and overcomes SpoIIAB-mediated inhibition of σ
F
. The finding that SpoIIE is a serine phosphatase links asymmetric division to the pathway governing cell-specific gene transcription.
India Proposes Private Universities
Authors: Bagla Pallava
Published: October 2006

New Delhi—The Indian government wants legislative approval of a plan that would allow the first private universities in the country. The proposal responds to complaints from industry and students that undergraduates aren't being properly trained for high-tech jobs.
Greenhouse Report Foresees Growing Global Stress
Authors: Kerr Richard A.
Published: October 2006

A panel of scientists convened by the United Nations has issued a grim picture of the greenhouse world: Global warming could affect everything from ocean fisheries to human health, mostly for the worse. But the good news, the panel said in a major report, is that these effects could be forestalled with surprisingly little cost.
Researchers Build Novel Laser By Putting a Lock on Atoms
Authors: Taubes Gary
Published: October 2006

A golden rule of laser technology is that a majority of the atoms in the lasing medium must be in the excited, light-emitting state. But two teams of physicists have managed to break this rule: They have obtained light from just a few excited atoms by preventing the others from absorbing photons. The trick was to use a second laser to alter the atomic energy levels, creating two different paths by which the atoms could absorb the light. The paths competed, and absorption was stymied. See sidebar (p. 738).
The Brain's Visual World: Representation of Visual Targets in Cerebral Cortex
Authors: Maunsell John H. R.
Published: October 2006

Microelectrode recordings from behaving monkeys have shown that neuronal responses in the visual cerebral cortex can depend greatly on which aspect of the scene is the target of the animal's attention. Accumulating evidence suggests that while the early stages of the visual pathway provide a faithful representation of the retinal image, later stages of processing in the visual cortex hold representations that emphasize the viewer's current interest. By filtering out irrelevant signals and adding information about objects whose presence is remembered or inferred, the cortex creates an edited representation of the visual world that is dynamically modified to suit the immediate goals of the viewer.
Photoluminescence from Porous Silicon by Infrared Multiphoton Excitation
Authors: Chin R. P. , Shen Y. R. , Petrova-Koch V.
Published: October 2006

Visible photoluminescence from porous silicon induced by infrared multiphoton excitation was observed at room temperature. Luminescence resulted from carrier excitations in the surface region of the sample. With the pump in the mid-infrared, excitation was effective only when the pump frequency was near resonance with the stretch vibrations of the surface species, SiH
x
. For each visible photon emitted, at least seven or eight infrared photons were absorbed. The excitation is believed to occur via pumping up a vibrational ladder, followed by conversion to electronic excitation. The process is similar to infrared multiphoton excitation of polyatomic molecules.
Carbon Dioxide Uptake by an Undisturbed Tropical Rain Forest in Southwest Amazonia, 1992 to 1993
Authors: Grace John , Lloyd Jon , McIntyre John , Miranda Antonio C. , Meir Patrick , Miranda Heloisa S. , Nobre Carlos , Moncrieff John , Massheder Jon , Malhi Yadvinder , Wright Ivan , Gash John
Published: October 2006

Measurements of carbon dioxide flux over undisturbed tropical rain forest in Brazil for 55 days in the wet and dry seasons of 1992 to 1993 show that this ecosystem is a net absorber of carbon dioxide. Photosynthetic gains of carbon dioxide exceeded respiratory losses irrespective of the season. These gains cannot be attributed to measurement error, nor to loss of carbon dioxide by drainage of cold air at night. A process-based model, fitted to the data, enabled estimation of the carbon absorbed by the ecosystem over the year as 8.5 ± 2.0 moles per square meter per year.
Dynamic Contribution to Hemispheric Mean Temperature Trends
Authors: Wallace John M. , Zhang Yuan , Renwick James A.
Published: October 2006

On the basis of land station data from the Northern Hemisphere, it was determined that roughly half of the temporal variance of monthly mean hemispheric mean anomalies in surface air temperature during the period from 1900 through 1990 were linearly related to the amplitude of a distinctive spatial pattern in which the oceans are anomalously cold and the continents are anomalously warm poleward of 40 degrees north when the hemisphere is warm. Apart from an upward trend since 1975, to which El Niño has contributed, the amplitude time series associated with this pattern resembles seasonally dependent white noise. It is argued that the variability associated with this pattern is dynamically induced and is not necessarily an integral part of the fingerprint of global warming.
Aberrant Subcellular Localization of BRCA1 in Breast Cancer
Authors: Chen Yumay , Chen Chi-Fen , Riley Daniel J. , Allred D. Craig , Chen Phang-Lang , Von Hoff Daniel , Osborne C. Kent , Lee Wen-Hwa
Published: October 2006

The
BRCA1
gene product was identified as a 220-kilodalton nuclear phosphoprotein in normal cells, including breast ductal epithelial cells, and in 18 of 20 tumor cell lines derived from tissues other than breast and ovary. In 16 of 17 breast and ovarian cancer lines and 17 of 17 samples of cells obtained from malignant effusions, however, BRCA1 localized mainly in cytoplasm. Absence of BRCA1 or aberrant subcellular location was also observed to a variable extent in histological sections of many breast cancer biopsies. These findings suggest that BRCA1 abnormalities may be involved in the pathogenesis of many breast cancers, sporadic as well as familial.
Orphanin FQ: A Neuropeptide That Activates an Opioidlike G Protein-Coupled Receptor
Authors: Reinscheid Rainer K. , Nothacker Hans-Peter , Bourson Anne , Ardati Ali , Henningsen Robert A. , Bunzow James R. , Grandy David K. , Langen Hanno , Monsma Frederick J. , Civelli Olivier
Published: October 2006

A heptadecapeptide was identified and purified from porcine brain tissue as a ligand for an orphan heterotrimeric GTP- binding protein (G protein)- coupled receptor (LC132) that is similar in sequence to opioid receptors. This peptide, orphanin FQ, has a primary structure reminiscent of that of opioid peptides. Nanomolar concentrations of orphanin FQ inhibited forskolin-stimulated adenylyl cyclase activity in cells transfected with LC132. This inhibitory activity was not affected by the addition of opioid ligands, nor did the peptide activate opioid receptors. Orphanin FQ bound to its receptor in a saturable manner and with high affinity. When injected intracerebroventricularly into mice, orphanin FQ caused a decrease in locomotor activity but did not induce analgesia in the hot-plate test. However, the peptide produced hyperalgesia in the tail-flick assay. Thus, orphanin FQ may act as a transmitter in the brain by modulating nociceptive and locomotor behavior.
Defects in B Lymphocyte Maturation and T Lymphocyte Activation in Mice Lacking Jak3
Authors: Thomis Daniel C. , Gurniak Christine B. , Tivol Elizabeth , Sharpe Arlene H. , Berg Leslie J.
Published: October 2006

Biochemical studies of signaling mediated by many cytokine and growth factor receptors have implicated members of the Jak family of tyrosine kinases in these pathways. Specifically, Jak3 has been shown to be associated with the interleukin-2 (IL-2) receptor γ chain, a component of the receptors for IL-2, IL-4, IL-7, IL-9, and IL-15. Mice lacking Jak3 showed a severe block in B cell development at the pre-B stage in the bone marrow. In contrast, although the thymuses of these mice were small, T cell maturation progressed relatively normally. In response to mitogenic signals, peripheral T cells in Jak3-deficient mice did not proliferate and secreted small amounts of IL-2. These data demonstrate that Jak3 is critical for the progression of B cell development in the bone marrow and for the functional competence of mature T cells.
Mutation of Jak3 in a Patient with SCID: Essential Role of Jak3 in Lymphoid Development
Authors: Russell Sarah M. , Tayebi Nahid , Nakajima Hiroshi , Riedy Mary C. , Roberts Joseph L. , Aman M. Javad , Migone Thi-Sau , Noguchi Masayuki , Markert M. Louise , Buckley Rebecca H. , O'Shea John J. , Leonard Warren J.
Published: October 2006

Males with X-linked severe combined immunodeficiency (XSCID) have defects in the common cytokine receptor γ chain (γ
c
) gene that encodes a shared, essential component of the receptors for interleukin-2 (IL-2), IL-4, IL-7, IL-9, and IL-15. The Janus family tyrosine kinase Jak3 is the only signaling molecule known to be associated with γ
c
, so it was hypothesized that defects in Jak3 might cause an XSCID-like phenotype. A girl with immunological features indistinguishable from those of XSCID was therefore selected for analysis. An Epstein-Barr virus (EBV)-transformed cell line derived from her lymphocytes had normal γ
c
expression but lacked Jak3 protein and had greatly diminished Jak3 messenger RNA. Sequencing revealed a different mutation on each allele: a single nucleotide insertion resulting in a frame shift and premature termination in the Jak3 JH4 domain and a nonsense mutation in the Jak3 JH2 domain. The lack of Jak3 expression correlated with impaired B cell signacrcling, as demonstrated by the inability of IL-4 to activate Stat6 in the EBV-transformed cell line from the patient. These observations indicate that the functions of γ
c
are dependent on Jak3 and that Jak3 is essential for lymphoid development and signaling.
Defective Lymphoid Development in Mice Lacking Jak3
Authors: Nosaka Tetsuya , van Deursen Jan M. A. , Tripp Ralph A. , Thierfelder William E. , Witthuhn Bruce A. , McMickle Anthony P. , Doherty Peter C. , Grosveld Gerard C. , Ihle James N.
Published: October 2006

The Janus tyrosine kinases (Jaks) play a central role in signaling through cytokine receptors. Although Jak1, Jak2, and Tyk2 are widely expressed, Jak3 is predominantly expressed in hematopoietic cells and is known to associate only with the common γ (γ
c
) chain of the interleukin (IL)-2, IL-4, IL-7, IL-9, and IL-15 receptors. Homozygous mutant mice in which the
Jak3
gene had been disrupted were generated by gene targeting. Jak3-deficient mice had profound reductions in thymocytes and severe B cell and T cell lymphopenia similar to severe combined immunodeficiency disease (SCID), and the residual T cells and B cells were functionally deficient. Thus, Jak3 plays a critical role in γ
c
signaling and lymphoid development.
Superior Parietal Cortex Activation During Spatial Attention Shifts and Visual Feature Conjunction
Authors: Corbetta Maurizio , Shulman Gordon L. , Miezin Francis M. , Petersen Steven E.
Published: October 2006

Positron emission tomography was used to measure changes in the regional cerebral blood flow of normal people while they searched visual displays for targets defined by color, by motion, or by a conjunction of color and motion. A region in the superior parietal cortex was activated only during the conjunction task, at a location that had previously been shown to be engaged by successive shifts of spatial attention. Correspondingly, the time needed to detect a conjunction target increased with the number of items in the display, which is consistent with the use of a mechanism that successively analyzes each item in the visual field.
Rhythmic Expression of
timeless
: A Basis for Promoting Circadian Cycles in
period
Gene Autoregulation
Authors: Sehgal Amita , Rothenfluh-Hilfiker Adrian , Hunter-Ensor Melissa , Chen Yifeng , Myers Michael P. , Young Michael W.
Published: October 2006

The clock gene
timeless
(
tim
) is required for circadian rhythmicity in
Drosophila
. The accumulation of
tim
RNA followed a circadian rhythm, and the phase and period of the
tim
RNA rhythm were indistinguishable from those that have been reported for
per
. The
tim
RNA oscillations were found to be dependent on the presence of PER and TIM proteins, which demonstrates feedback control of
tim
by a mechanism previously shown to regulate
per
expression. The cyclic expression of
tim
appears to dictate the timing of PER protein accumulation and nuclear localization, suggesting that
tim
promotes circadian rhythms of
per
and
tim
transcription by restricting
per
RNA and PER protein accumulation to separate times of day.
Isolation of
timeless
by PER Protein Interaction: Defective Interaction Between
timeless
Protein and Long-Period Mutant PER
L
Authors: Gekakis Nicholas , Saez Lino , Delahaye-Brown Anne-Marie , Myers Michael P. , Sehgal Amita , Young Michael W. , Weitz Charles J.
Published: October 2006

The
period
(
per
) gene likely encodes a component of the
Drosophila
circadian clock. Circadian oscillations in the abundance of
per
messenger RNA and
per
protein (PER) are thought to arise from negative feedback control of
per
gene transcription by PER. A recently identified second clock locus,
timeless
(
tim
), apparently regulates entry of PER into the nucleus. Reported here are the cloning of complementary DNAs derived from the
tim
gene in a two-hybrid screen for PER-interacting proteins and the demonstration of a physical interaction between the
tim
protein (TIM) and PER in vitro. A restricted segment of TIM binds directly to a part of the PER dimerization domain PAS. PER
L
, a mutation that causes a temperature-sensitive lengthening of circadian period and a temperature-sensitive delay in PER nuclear entry, exhibits a temperature-sensitive defect in binding to TIM. These results suggest that the interaction between TIM and PER determines the timing of PER nuclear entry and therefore the duration of part of the circadian cycle.
Participation of the Human β-Globin Locus Control Region in Initiation of DNA Replication
Authors: Aladjem Mirit I. , Groudine Mark , Brody Linnea L. , Dieken Ellen S. , Fournier R. E. Keith , Wahl Geoffrey M. , Epner Elliot M.
Published: October 2006

The human β-globin locus control region (LCR) controls the transcription, chromatin structure, and replication timing of the entire locus. DNA replication was found to initiate in a transcription-independent manner within a region located 50 kilobases downstream of the LCR in human, mouse, and chicken cells containing the entire human β-globin locus. However, DNA replication did not initiate within a deletion mutant locus lacking the sequences that encompass the LCR. This mutant locus replicated in the 3′ to 5′ direction. Thus, interactions between distantly separated sequences can be required for replication initiation, and factors mediating this interaction appear to be conserved in evolution.
Ulysses Cracks a Cosmic Peanut
Authors: Glanz James
Published: October 2006

Chicagod—New results from the U.S.-European solar satellite, Ulysses, have indicated that the heliosphere—a region carved out of the thin gases of interstellar space by the wind of charged particles streaming from the sun—is not spherical, as physicists have generally pictured it. Instead, it is shaped more like a peanut, with its “waist” in the same plane as the solar system.
Life and Death Decisions:
ced-9
and Programmed Cell Death in
Caenorhabditis elegans
Authors: Hengartner Michael O.
Published: October 2006

In his grand prize-winning essay for the Pharmacia Biotech &
Science
Prize for Young Scientists, M. Hengartner discusses the phenomenon of programmed cell death and the gene
ced-9
from
C. elegans
, a small nematode in which the pattern of cell death during development is completely known. The
ced-9
gene seems to keep the cell death program off in cells that are scheduled to live.
Geometry of a Black Hole Collision
Authors: Matzner Richard A. , Seidel H. E. , Shapiro Stuart L. , Smarr L. , Suen W.-M. , Teukolsky Saul A. , Winicour J.
Published: October 2006

The Binary Black Hole Alliance was formed to study the collision of black holes and the resulting gravitational radiation by computationally solving Einstein's equations for general relativity. The location of the black hole surface in a head-on collision has been determined in detail and is described here. The geometrical features that emerge are presented along with an analysis and explanation in terms of the spacetime curvature inherent in the strongly gravitating black hole region. This curvature plays a direct, important, and analytically explicable role in the formation and evolution of the event horizon associated with the surfaces of the black holes.
Chemical Generation of Acoustic Waves: A Giant Photoacoustic Effect
Authors: Chen Huxiong , Diebold Gerald
Published: October 2006

An anomalous photoacoustic effect is produced when a suspension of carbon particles in water is irradiated by a high-power, pulsed laser. The photoacoustic effect has an amplitude on the order of 2000 times that produced by a dye solution with an equivalent absorption coefficient and gives a distinctly audible sound above an uncovered cell. Transient grating experiments with carbon suspensions show a doubling of the acoustic frequency corresponding to the optical fringe spacing of the grating. The effect is thought to originate in high-temperature chemical reactions between the surface carbon and the surrounding water.
Carbon Dioxide and Oxygen Isotope Anomalies in the Mesosphere and Stratosphere
Authors: Thiemens Mark H. , Jackson Teresa , Zipf Edward C. , Erdman Peter W. , van Egmond Cornel
Published: October 2006

Isotopic (δ
17
O and δ
18
O) measurements of stratospheric and mesospheric carbon dioxide (CO
2
) and oxygen (O
2
), along with trace species concentrations (N
2
O, CO, and CO
2
), were made in samples collected from a rocket-borne cryogenic whole air sampler. A large mass-independent isotopic anomaly was observed in CO
2
, which may in part derive from photochemical coupling to ozone (O
3
). The data also require an additional isotopic fractionation process, which is presently unidentified. Mesospheric O
2
isotope ratios differed from those in the troposphere and stratosphere. The cause of this isotopic variation in O
2
is presently unknown. The inability to account for these observations represents a fundamental gap in the understanding of the O
2
chemistry in the stratosphere and mesosphere.
Logic Gates Made from Polymer Transistors and Their Use in Ring Oscillators
Authors: Brown A. R. , Pomp A. , Hart C. M. , de Leeuw D. M.
Published: October 2006

Metal-insulator-semiconductor field-effect transistors have been fabricated from polymer semiconductors that can be processed from solution. The performance of these transistors is sufficient to allow the construction of simple logic gates that display voltage amplification. Successful coupling of these gates into ring oscillators demonstrates that these logic gates can switch subsequent gates and perform logic operations. The ability to perform logic operations is an essential requirement for the use of polymer-based transistors in low-cost low-end data storage applications.
Guidelines for Protein Design: The Energetics of β Sheet Side Chain Interactions
Authors: Smith Catherine K. , Regan Lynne
Published: October 2006

To determine the interaction energy between cross-strand pairs of side chains on an antiparallel β sheet, pairwise amino acid substitutions were made on the solvent-exposed face of the B1 domain of streptococcal protein G. The measured interaction energies were substantial (1.8 kilocalories per mole) and comparable to the magnitude of the β sheet propensities. The experimental results paralleled the statistical frequency with which the residue pairs are found in β sheets of known structure.
Lymphoproliferative Disorders with Early Lethality in Mice Deficient in
Ctla-4
Authors: Waterhouse Paul , Penninger Josef M. , Timms Emma , Wakeham Andrew , Shahinian Arda , Lee Kelvin P. , Thompson Craig B. , Griesser Henrik , Mak Tak W.
Published: October 2006

The role of the cell-surface molecule CTLA-4 in the regulation of T cell activation has been controversial. Here, lymph nodes and spleens of CTLA-4-deficient mice accumulated T cell blasts with up-regulated activation markers. These blast cells also infiltrated liver, heart, lung, and pancreas tissue, and amounts of serum immunoglobulin were elevated. The mice invariably became moribund by 3 to 4 weeks of age. Although CTLA-4-deficient T cells proliferated spontaneously and strongly when stimulated through the T cell receptor, they were sensitive to cell death induced by cross-linking of the Fas receptor and by gamma irradiation. Thus, CTLA-4 acts as a negative regulator of T cell activation and is vital for the control of lymphocyte homeostasis.
Genomic Structure of an Attenuated Quasi Species of HIV-1 from a Blood Transfusion Donor and Recipients
Authors: Deacon N. J. , Tsykin A. , Solomon A. , Smith K. , Ludford-Menting M. , Hooker D. J. , McPhee D. A. , Greenway A. L. , Ellett A. , Chatfield C. , Lawson V. A. , Crowe S. , Maerz A. , Sonza S. , Learmont J. , Sullivan J. S. , Cunningham A. , Dwyer D. , Dowton D. , Mills J.
Published: October 2006

A blood donor infected with human immunodeficiency virus-type 1 (HIV-1) and a cohort of six blood or blood product recipients infected from this donor remain free of HIV-1-related disease with stable and normal CD4 lymphocyte counts 10 to 14 years after infection. HIV-1 sequences from either virus isolates or patient peripheral blood mononuclear cells had similar deletions in the
nef
gene and in the region of overlap of
nef
and the U3 region of the long terminal repeat (LTR). Full-length sequencing of one isolate genome and amplification of selected HIV-1 genome regions from other cohort members revealed no other abnormalities of obvious functional significance. These data show that survival after HIV infection can be determined by the HIV genome and support the importance of
nef
or the U3 region of the LTR in determining the pathogenicity of HIV-1.
Converting
Escherichia coli
RNA Polymerase into an Enhancer-Responsive Enzyme: Role of an NH
2
-Terminal Leucine Patch in σ
54
Authors: Wang Jonathan T. , Syed Adeela , Hsieh Mingli , Gralla Jay D.
Published: October 2006

The protein σ
54
associates with
Escherichia coli
core RNA polymerase to form a holoenzyme that binds promoters but is inactive in the absence of enhancer activation. Here, mutants of σ
54
enabled polymerases to transcribe without enhancer protein and adenosine triphosphate. The mutations are in leucines within the NH
2
-terminal glutamine-rich domain of σ
54
. Multiple leucine substitutions mimicked the effect of enhancer protein, which suggests that the enhancer protein functions to disrupt a leucine patch. The results indicate that σ
54
acts both as an inhibitor of polymerase activity and as a receptor that interacts with enhancer protein to overcome this inhibition, and that these two activities jointly confer enhancer responsiveness.
Transition in Specification of Embryonic Metazoan DNA Replication Origins
Authors: Hyrien Olivier , Maric Chrystelle , Méchali Marcel
Published: October 2006

In early
Xenopus
embryos, in which ribosomal RNA genes (rDNA) are not transcribed, rDNA replication initiates and terminates at 9- to 12-kilobase pair intervals, with no detectable dependence on specific DNA sequences. Resumption of ribosomal RNA (rRNA) synthesis at late blastula and early gastrula is accompanied by a specific repression of replication initiation within transcription units; the frequency of initiation within intergenic spacers remains as high as in early blastula. These results demonstrate that for rRNA genes, circumscribed zones of replication initiation emerge in intergenic DNA during the time in metazoan development when the chromatin is remodeled to allow gene transcription.
African Origins: West Side Story
Authors: Morell Virginia
Published: October 2006

Some of the first steps towards humanity, researchers used to think, were taken in East Africa, because that's where the earliest bipedal australopithecines were found. But a new australopithecine found in Central Africa indicates our ancestors' range was far wider than anyone had thought.
New Drug Shows Promise in Monkeys
Authors: Cohen Jon
Published: October 2006

In experiments reported in this issue (p.
p. 1197
), a new AIDS drug called PMPA protected monkeys from being infected by SIV, the simian counterpart of the AIDS virus. Preliminary results presented at a meeting last week also indicate that the drug slows the onset of symptoms when it is given after SIV infection is established
Science Policy: The Long March to Topnotch Science
Authors: Mervis Jeffrey
Published: October 2006

Shanghai—Research in China is being transformed by the growing use of competitive grants, international collaborations, young scientists returning with a splash as older scientists retire quietly, the growth of high-tech enterprises, and the promise of new cutting-edge facilities. But can the bureaucracy and the nation's penchant for secrecy accommodate such sweeping changes?
Reading the Tea Leaves in a List of Major Priorities
Authors: Mervis Jeffrey
Published: October 2006

Beijing—The Chinese Academy of Sciences has proposed several new big-science facilities, including a 2.5-GeV synchrotron radiation facility and a 4-meter telescope with advanced optics. Proponents of each project are now jockeying for support among scientists and public officials at all levels of government.
Astronomers Hang Out Help-Wanted Sign
Authors: Mervis Jeffrey
Published: October 2006

Chinese astronomers hope that international cooperation will help them to launch two ambitious projects—an orbiting optical telescope to study the sun, and a radio telescope with an unprecedented collecting area of 1 square kilometer. Both projects are attracting interest from researchers in the United States, Europe, and Japan.
The Course of Reform at the Chinese Academy of Sciences
Authors: Zhou Guangzhao
Published: October 2006

The author discusses recent reforms in the Chinese Academy of Sciences, the leading institution in China fostering research. Major challenges include reduction of permanent staff while increasing visiting staff, and the balance between basic and applied research.
The Emerging Art of Solid-State Synthesis
Authors: Parkinson Bruce
Published: October 2006

Solid-state chemists are exploring new routes to synthesizing useful compounds, including self-assembly, by which complex structures form spontaneously from simpler ones. Parkinson provides background and comment on a research report by Noh
et al
. in this issue (
p. 1181
) that describes a method of depositing reactants on a substrate at low temperature; once the starting materials are in place, the temperature is increased, allowing the reaction to proceed.
Gas-Phase Multiply Charged Anions
Authors: Scheller Markus K. , Compton Robert N. , Cederbaum Lorenz S.
Published: October 2006

Singly charged negative ions in the gas phase have attracted considerable experimental and theoretical attention over the past decades. However, the existence of free doubly or multiply charged negative ions, in particular those of small systems, has remained a curiosity and a matter of some controversy. Recent experimental and quantum mechanical studies show that multiply charged negative ions of small molecules and clusters can exist as isolated entities.
Partitioning of Tungsten and Molybdenum Between Metallic Liquid and Silicate Melt
Authors: Walter Michael J. , Thibault Yves
Published: October 2006

The "excess" of siderophile elements in Earth's mantle is a long-standing problem in understanding the evolution of Earth. Determination of the partitioning behavior of tungsten and molybdenum between liquid metal and silicate melt at high pressure and temperature shows that partition coefficients (
D
metal/silicate
) vary by two orders of magnitude depending on whether metal segregated from a basaltic or peridotitic melt. This compositional dependence is likely a response to changes in the degree of polymerization of the silicate melt caused by compositional variations of the network-modifying cations Mg
2+
and Fe
2+
. Silicate melt compositional effects on partition coefficients for siderophile elements are potentially more important than the effects of high pressure and temperature.
Fas Ligand-Induced Apoptosis as a Mechanism of Immune Privilege
Authors: Griffith Thomas S. , Brunner Thomas , Fletcher Sharon M. , Green Douglas R. , Ferguson Thomas A.
Published: October 2006

The eye is a privileged site that cannot tolerate destructive inflammatory responses. Inflammatory cells entering the anterior chamber of the eye in response to viral infection underwent apoptosis that was dependent on Fas (CD95)-Fas ligand (FasL) and produced no tissue damage. In contrast, viral infection in
gld
mice, which lack functional FasL, resulted in an inflammation and invasion of ocular tissue without apoptosis. Fas-positive but not Fas-negative tumor cells were killed by apoptosis when placed within isolated anterior segments of the eyes of normal but not FasL-negative mice. FasL messenger RNA and protein were detectable in the eye. Thus, Fas-FasL interactions appear to be an important mechanism for the maintenance of immune privilege.
Negative Xylem Pressures in Plants: A Test of the Balancing Pressure Technique
Authors: Holbrook N. Michele , Burns Michael J. , Field Christopher B.
Published: October 2006

Xylem tension was experimentally imposed by centrifugal force to assess the stability of negative pressures within the xylem and the estimation of those pressures with a pressure chamber. Balancing pressure measurements of leaves attached to a spinning branch at the axis of rotation closely agreed with tensions calculated from the rotational velocity. This agreement demonstrates that the xylem is capable of sustaining large negative pressures and directly validates the balancing pressure technique.
Inhibitors of HIV Nucleocapsid Protein Zinc Fingers as Candidates for the Treatment of AIDS
Authors: Rice William G. , Supko Jeffrey G. , Malspeis Louis , Buckheit Robert W. , Clanton David , Bu Ming , Graham Lisa , Schaeffer Catherine A. , Turpin Jim A. , Domagala John , Gogliotti Rocco , Bader John P. , Halliday Susan M. , Coren Lori , Sowder Raymond C. , Arthur Larry O. , Henderson Louis E.
Published: October 2006

Strategies for the treatment of human immunodeficiency virus-type 1 (HIV-1) infection must contend with the obstacle of drug resistance. HIV-1 nucleocapsid protein zinc fingers are prime antiviral targets because they are mutationally intolerant and are required both for acute infection and virion assembly. Nontoxic disulfide-substituted benzamides were identified that attack the zinc fingers, inactivate cell-free virions, inhibit acute and chronic infections, and exhibit broad antiretroviral activity. The compounds were highly synergistic with other antiviral agents, and resistant mutants have not been detected. Zinc finger-reactive compounds may offer an anti-HIV strategy that restricts drug-resistance development.
Pheromone Response in Yeast: Association of Bem1p with Proteins of the MAP Kinase Cascade and Actin
Authors: Leeuw Thomas , Fourest-Lieuvin Anne , Wu Cunle , Chenevert Janet , Clark Karen , Whiteway Malcolm , Thomas David Y. , Leberer Ekkehard
Published: October 2006

Haploid cells of the yeast
Saccharomyces cerevisiae
respond to mating pheromones with polarized growth toward the mating partner. This morphological response requires the function of the cell polarity establishment protein Bem1p. Immunochemical and two-hybrid protein interaction assays revealed that Bem1p interacts with two components of the pheromone-responsive mitogen-activated protein (MAP) kinase cascade, Ste20p and Ste5p, as well as with actin. Mutants of Bem1p that are associated with defective pheromone-induced polarized morphogenesis interacted with Ste5p and actin but not with Ste20p. Thus, the association of Bem1p with Ste20p and Ste5p may contribute to the conveyance of spatial information that regulates polarized rearrangement of the actin cytoskeleton during yeast mating.
Ligand-Induced Autoregulation of IFN-γ Receptor β Chain Expression in T Helper Cell Subsets
Authors: Bach Erika A. , Szabo Susanne J. , Dighe Anand S. , Ashkenazi Avi , Aguet Michel , Murphy Kenneth M. , Schreiber Robert D.
Published: October 2006

Interferon γ (IFN-γ) responsiveness in certain cells depends on the state of cellular differentiation or activation. Here an in vitro developmental system was used to show that IFN-γ produced during generation of the CD4
+
T helper cell type 1 (T
H
1) subset extinguishes expression of the IFN-γ receptor β subunit, resulting in T
H
1 cells that are unresponsive to IFN-γ. This β chain loss also occurred in IFN-γ-treated T
H
2 cells and thus represents a specific response of CD4
+
T cells to IFN-γ rather than a T
H
1-specific differentiation event. These results define a mechanism of cellular desensitization where a cytokine down-regulates expression of a receptor subunit required primarily for signaling and not ligand binding.
Antarctic Research Ship Narrowly Saved
Authors: Allakhverdov Andrey
Published: October 2006

Moscow—A research vessel has been impounded by a German shipyard awaiting payment of repair bills. The Russian finance ministry came through with a payment just before the ship was to be put on the auction block, but the delay may force a temporary shutdown of Russia's Vostok station near the South Pole.
Semiconductors Open a New Niche for Plasma Researchers
Authors: Glanz James
Published: October 2006

Louisville, Kentucky—Now that Congress has cut a third from the Department of Energy's fusion program—long the primary employer of plasma physicists—job prospects for researchers in the field look grim. But salvation may come from the computer industry. Plasma etching is crucial to the production of dense, high-performance microcircuits, and plasma physicists are in increasing demand to refine the process.