bluuebunny/crossref_metadata_2025 huggingface dataset:
Probing the Local Effects of Magnetic Impurities on Superconductivity
Authors: Yazdani Ali , Jones B. A. , Lutz C. P. , Crommie M. F. , Eigler D. M.
Published: July 2002

The local effects of isolated magnetic adatoms on the electronic properties of the surface of a superconductor were studied with a low-temperature scanning tunneling microscope. Tunneling spectra obtained near magnetic adsorbates reveal the presence of excitations within the superconductor's energy gap that can be detected over a few atomic diameters around the impurity at the surface. These excitations are locally asymmetric with respect to tunneling of electrons and holes. A model calculation based on the Bogoliubov-de Gennes equations can be used to understand the details of the local tunneling spectra.
Surprise Authorship
Authors: Levy Gerald N.
Published: July 2002

Recent letters (
6 Dec., p. 1593
;
24 Jan., p. 461
) have proposed strict rules for co-authorship of scientific publications. I wholeheartedly agree that to put one's name on a paper is an assurance to the scientific community that one has contributed to the work and that one stands behind the work reported. However, one aspect of the co-authorship problem that I have not seen discussed in this forum is that of finding one's name as a co-author on a publication of which one has no knowledge. This recently happened to a colleague and me when we found a paper in a journal listing our names as co-authors, although neither of us had ever contributed to the work, seen the manuscript, or been notified of its submission or publication.

I felt victimized by this event and by the use of my name in an inappropriate manner. Integrity and reputation are among our major assets as scientists. I agree with previous letter writers that every reputable journal should secure a written statement from each author listed on a manuscript assuring that a contribution to the work was made and accepting responsibility for the work. Such a requirement will protect both the integrity of the literature from bogus authorship and the integrity of researchers whose names may be usurped.
Reform Begins With New CNR Head
Authors: Biggin Susan
Published: July 2002

VENICE
—Last week, Italy's science minister, Luigi Berlinguer, appointed a relatively unknown academic, informatics engineer Lucio Bianco, to head the National Research Council (CNR). Just days earlier, Parliament approved a law that gives Berlinguer more authority and requires his ministry for universities and research to draw up within 1 year legislation to reform the scientific infrastructure. Berlinguer told Science his first target for reform is the CNR, to shift its emphasis toward applied research, and Bianco's appointment is part of his master plan.
Robotic Subs for Rapid-Response Science
Authors: Nadis Steve
Published: July 2002

The Haro Strait experiment tested a new method of doing oceanography in “real time” (
see related story
)—and a versatile new tool for collecting the data. Along with an array of buoys and a ship, the experiment relied on two robotic submersibles known as autonomous underwater vehicles.
Tenure Turmoil Sparks Reforms
Authors: Holden Constance
Published: July 2002

Pinched by shrinking budgets, institutions of higher education, state legislatures, and boards of regents are reevaluating the terms of tenure, which has come under fierce attack in recent years. While a few institutions have abolished their tenure systems, most are tightening it up to ensure greater accountability. On many campuses, tenure is become harder to get and--with new systems of posttenure review--a little easier to lose. And in some cases, it is being redefined as a guarantee of a teaching job and an office, but not necessarily a full salary.
Merit Review: NSF Adopts New Guidelines
Authors: Mervis Jeffrey
Published: July 2002

Scientists who review grant proposals for the National Science Foundation (NSF) soon will be asked to judge them according to just two criteria: scientific quality and impact on society. The new approach, adopted last week by the National Science Board, eliminates separate criteria relating to the applicant's track record and the effect of the project on the nation's scientific infrastructure.
Astronomy: Supernovae Offer a First Glimpse of the Universe's Fate
Authors: Goldsmith Donald
Published: July 2002

By studying Type Ia supernovae, exploding stars visible at distances so vast that they represent earlier epochs of cosmic history, astronomers are getting a look at the ultimate fate of the universe. By comparing the brightness of these beacons--an indicator of their distance--with the rate at which cosmic expansion is carrying them away, two groups of observers are now closing in on the rate at which cosmic expansion has changed over time. Early results suggest that high matter density is slowing the universe's expansion, and that the cosmos contains hundreds of times more mass than can be seen as stars and galaxies--a conclusion that may conflict with other clues suggesting a low-density universe (
see p. 36
).
The Cis-Trans Paradox of Integrase
Authors: Jayaram Makkuni
Published: July 2002

During recombination, strands of DNA break and are rejoined, producing the reshuffling of genetic information that underlies genetic diversity. Jayaram discusses the chemical mechanism underlying this process, including the controversial cis-trans paradox, as revealed by the x-ray crystallographic structure of the recombinase lambda integrase, reported in this issue by Kwon
et al.
(
p. 126
).
… or Distraction?
Authors: Vincent Jeffrey R. , Panayotou Theodore
Published: July 2002

Environmental degradation and resource depletion are not inevitably linked to consumption. The root causes of these problems are instead market and policy failures that lead consumers and producers to ignore the full social costs of their decisions. Policy-makers should focus not on capping consumption, but rather on addressing market and policy failures through economic and political liberalization and environmental policy reform.
Quantitative Trait Loci for Refractoriness of
Anopheles gambiae
to
Plasmodium cynomolgi
B
Authors: Zheng Liangbiao , Cornel Anton J. , Wang Rui , Erfle Holger , Voss Hartmut , Ansorge Wilhelm , Kafatos Fotis C. , Collins Frank H.
Published: July 2002

The severity of the malaria pandemic in the tropics is aggravated by the ongoing spread of parasite resistance to antimalarial drugs and mosquito resistance to insecticides. A strain of
Anopheles gambiae
, normally a major vector for human malaria in Africa, can encapsulate and kill the malaria parasites within a melanin-rich capsule in the mosquito midgut. Genetic mapping revealed one major and two minor quantitative trait loci (QTLs) for this encapsulation reaction. Understanding such antiparasite mechanisms in mosquitoes may lead to new strategies for malaria control.
Vesicle-Specific Noble Gas Analyses of "Popping Rock": Implications for Primordial Noble Gases in Earth
Authors: Burnard Pete , Graham David , Turner Grenville
Published: July 2002

Gases trapped in individual vesicles in the volatile-rich basaltic glass “popping rock” were found to have the same carbon dioxide, helium-4, and argon-40 composition, but a variable
40
Ar/
36
Ar ratio (∼4000 to ≥40,000). The argon-36 is probably surface-adsorbed atmospheric argon; any mantle argon-36 trapped in the vesicles cannot be distinguished from an atmospheric contaminant. Consequently the
40
Ar/
36
Ar ratios and
3
He/
36
Ar ratios (1.45) determined are minimum estimates of the upper mantle composition. Heavy noble gas relative abundances in the mantle resemble solar noble gas abundance patterns, and a solar origin may be common to all primordial mantle noble gases.
Patterned Delivery of Immunoglobulins to Surfaces Using Microfluidic Networks
Authors: Delamarche Emmanuel , Bernard André , Schmid Heinz , Michel Bruno , Biebuyck Hans
Published: July 2002

Microfluidic networks (μFNs) were used to pattern biomolecules with high resolution on a variety of substrates (gold, glass, or polystyrene). Elastomeric μFNs localized chemical reactions between the biomolecules and the surface, requiring only microliters of reagent to cover square millimeter–sized areas. The networks were designed to ensure stability and filling of the μFN and allowed a homogeneous distribution and robust attachment of material to the substrate along the conduits in the μFN. Immunoglobulins patterned on substrates by means of μFNs remained strictly confined to areas enclosed by the network with submicron resolution and were viable for subsequent use in assays. The approach is simple and general enough to suggest a practical way to incorporate biological material on technological substrates.
Defective Excitation-Contraction Coupling in Experimental Cardiac Hypertrophy and Heart Failure
Authors: Gómez A. M. , Valdivia H. H. , Cheng H. , Lederer Miriam R. , Santana L. F. , Cannell M. B. , McCune S. A. , Altschuld R. A. , Lederer W. J.
Published: July 2002

Cardiac hypertrophy and heart failure caused by high blood pressure were studied in single myocytes taken from hypertensive rats (Dahl SS/Jr) and SH-HF rats in heart failure. Confocal microscopy and patch-clamp methods were used to examine excitation-contraction (EC) coupling, and the relation between the plasma membrane calcium current (
I
Ca
) and evoked calcium release from the sarcoplasmic reticulum (SR), which was visualized as “calcium sparks.” The ability of
I
Ca
to trigger calcium release from the SR in both hypertrophied and failing hearts was reduced. Because
I
Ca
density and SR calcium-release channels were normal, the defect appears to reside in a change in the relation between SR calcium-release channels and sarcolemmal calcium channels. β-Adrenergic stimulation largely overcame the defect in hypertrophic but not failing heart cells. Thus, the same defect in EC coupling that develops during hypertrophy may contribute to heart failure when compensatory mechanisms fail.
Structures of the Tyrosine Kinase Domain of Fibroblast Growth Factor Receptor in Complex with Inhibitors
Authors: Mohammadi Moosa , McMahon Gerald , Sun Li , Tang Cho , Hirth Peter , Yeh Brian K. , Hubbard Stevan R. , Schlessinger Joseph
Published: July 2002

A new class of protein tyrosine kinase inhibitors was identified that is based on an oxindole core (indolinones). Two compounds from this class inhibited the kinase activity of fibroblast growth factor receptor 1 (FGFR1) and showed differential specificity toward other receptor tyrosine kinases. Crystal structures of the tyrosine kinase domain of FGFR1 in complex with the two compounds were determined. The oxindole occupies the site in which the adenine of adenosine triphosphate binds, whereas the moieties that extend from the oxindole contact residues in the hinge region between the two kinase lobes. The more specific inhibitor of FGFR1 induces a conformational change in the nucleotide-binding loop. This structural information will facilitate the design of new inhibitors for use in the treatment of cancer and other diseases in which cell signaling by tyrosine kinases plays a crucial role in disease pathogenesis.
Epilepsy and Exacerbation of Brain Injury in Mice Lacking the Glutamate Transporter GLT-1
Authors: Tanaka Kohichi , Watase Kei , Manabe Toshiya , Yamada Keiko , Watanabe Masahiko , Takahashi Katsunobu , Iwama Hisayuki , Nishikawa Toru , Ichihara Nobutsune , Kikuchi Tateki , Okuyama Shigeru , Kawashima Naoya , Hori Seiji , Takimoto Misato , Wada Keiji
Published: July 2002

Extracellular levels of the excitatory neurotransmitter glutamate in the nervous system are maintained by transporters that actively remove glutamate from the extracellular space. Homozygous mice deficient in GLT-1, a widely distributed astrocytic glutamate transporter, show lethal spontaneous seizures and increased susceptibility to acute cortical injury. These effects can be attributed to elevated levels of residual glutamate in the brains of these mice.
Targets for Stabilization of Atmospheric CO
2
Authors: Azar Christian , Rodhe Henning
Published: July 2002

The Intergovernmental Panel on Climate Change (IPCC) has published emission trajectories for CO
2
leading to atmospheric equilibrium in the range of 350 to 1000 parts per million by volume (ppmv). This range does not, however, imply that any one concentration is the appropriate value toward which policies influencing worldwide anthropogenic emissions should aim. Scientists must join the debate, despite the difficulty of pinpointing the correct number; otherwise, action may not be taken. Analysis suggests that a value nearer to 350 ppmv should be adopted, until it can be proven that a higher value is safe.
Inducible Expression and Phosphorylation of Coactivator BOB.1/OBF.1 in T Cells
Authors: Zwilling Stefan , Dieckmann Andreas , Pfisterer Petra , Angel Peter , Wirth Thomas
Published: July 2002

BOB.1/OBF.1 is a transcriptional coactivator that is constitutively expressed in B cells and interacts with the Oct1 and Oct2 transcription factors. Upon activation of Jurkat T cells and primary murine thymocytes with phorbol esters and ionomycin, BOB.1/OBF.1 expression and transactivation function were induced. BOB.1/OBF.1 was phosphorylated at Ser
184
both in vivo and in vitro, and this modification was required for inducible activation. Mutation of Ser
184
also diminished transactivation function in B cells, suggesting that the activating phosphorylation that is inducible in T cells is constitutively present in B cells. Thus, BOB.1/OBF.1 is a transcriptional coactivator that is critically regulated by posttranslational modifications to mediate cell type–specific gene expression.
Alternative Cleavage of Alzheimer-Associated Presenilins During Apoptosis by a Caspase-3 Family Protease
Authors: Kim Tae-Wan , Pettingell Warren H. , Jung Yong-Keun , Kovacs Dora M. , Tanzi Rudolph E.
Published: July 2002

Most cases of early-onset familial Alzheimer's disease (FAD) are caused by mutations in the genes encoding the presenilin 1 (PS1) and PS2 proteins, both of which undergo regulated endoproteolytic processing. During apoptosis, PS1 and PS2 were shown to be cleaved at sites distal to their normal cleavage sites by a caspase-3 family protease. In cells expressing PS2 containing the asparagine-141 FAD mutant, the ratio of alternative to normal PS2 cleavage fragments was increased relative to wild-type PS2-expressing cells, suggesting a potential role for apoptosis-associated cleavage of presenilins in the pathogenesis of Alzheimer's disease.
Analysis of a Chemical Plant Defense Mechanism in Grasses
Authors: Frey Monika , Chomet Paul , Glawischnig Erich , Stettner Cornelia , Grün Sebastian , Winklmair Albert , Eisenreich Wolfgang , Bacher Adelbert , Meeley Robert B. , Briggs Steven P. , Simcox Kevin , Gierl Alfons
Published: July 2002

In the Gramineae, the cyclic hydroxamic acids 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) and 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) form part of the defense against insects and microbial pathogens. Five genes,
Bx1
through
Bx5
, are required for DIBOA biosynthesis in maize. The functions of these five genes, clustered on chromosome 4, were demonstrated in vitro.
Bx1
encodes a tryptophan synthase α homolog that catalyzes the formation of indole for the production of secondary metabolites rather than tryptophan, thereby defining the branch point from primary to secondary metabolism.
Bx2
through
Bx5
encode cytochrome P450–dependent monooxygenases that catalyze four consecutive hydroxylations and one ring expansion to form the highly oxidized DIBOA.
Room-Temperature Spin Memory in Two-Dimensional Electron Gases
Authors: Kikkawa J. M. , Smorchkova I. P. , Samarth N. , Awschalom D. D.
Published: July 2002

Time-resolved Kerr reflectivity of two-dimensional electron gases in II-VI semiconductors provides a direct measure of electron spin precession and relaxation over a temperature range from 4 to 300 kelvin. The introduction of
n
-type dopants increases the electronic spin lifetimes several orders of magnitude relative to insulating counterparts, a trend that is also observed in doped bulk semiconductors. Because the electronic spin polarization in these systems survives for nanoseconds, far longer than the electron-hole recombination lifetime, this technique reveals thousands of spin precession cycles of 15 gigahertz per tesla within an electron gas. Remarkably, these spin beats are only weakly temperature dependent and persist to room temperature.
Conditional Mutator Phenotypes in hMSH2-Deficient Tumor Cell Lines
Authors: Richards Burt , Zhang Hong , Phear Geraldine , Meuth Mark
Published: July 2002

Two human tumor cell lines that are deficient in the mismatch repair protein hMSH2 show little or no increase in mutation rate relative to that of a mismatch repair–proficient cell line when the cells are maintained in culture conditions allowing rapid growth. However, mutations accumulate at a high rate in these cells when they are maintained at high density. Thus the mutator phenotype of some mismatch repair–deficient cell lines is conditional and strongly depends on growth conditions. These observations have implications for tumor development because they suggest that mutations may accumulate in tumor cells when growth is limited.
Galactic Reflections
Authors: Cowley Anne
Published: July 2002

Bright Galaxies, Dark Matters.
VERA RUBIN. AIP Press (Springer-Verlag), New York, 1996. xvi, 236 pp., illus., + plates. $29.95 or £22.95. ISBN 1-56396-231-4. Masters of Modern Physics.
Cysteine and Glutathione Secretion in Response to Protein Disulfide Bond Formation in the ER
Authors: Carelli Stephana , Ceriotti Aldo , Cabibbo Andrea , Fassina Giorgio , Ruvo Menotti , Sitia Roberto
Published: July 2002

Protein folding in the endoplasmic reticulum (ER) often involves the formation of disulfide bonds. The oxidizing conditions required within this organelle were shown to be maintained through the release of small thiols, mainly cysteine and glutathione. Thiol secretion was stimulated when proteins rich in disulfide bonds were translocated into the ER, and secretion was prevented by the inhibition of protein synthesis. Endogenously generated cysteine and glutathione counteracted thiol-mediated retention in the ER and altered the extracellular redox. The secretion of thiols might link disulfide bond formation in the ER to intra- and intercellular redox signaling.
Toroidal Structure of λ-Exonuclease
Authors: Kovall Rhett , Matthews Brian W.
Published: July 2002

Structure determination at 2.4 angstrom resolution shows that λ-exonuclease consists of three subunits that form a toroid. The central channel is funnel shaped, tapering from an inner diameter of about 30 angstroms at the wider end to 15 angstroms at the narrow end. This is adequate to accommodate the DNA substrate and thus provides a structural basis for the ability of the enzyme to sequentially hydrolyze thousands of nucleotides in a highly processive manner. The results also suggest the locations of the active sites and the constraints that limit cleavage to a single strand.
A Range of Research-Based Pharmacotherapies for Addiction
Authors: O'Brien Charles P.
Published: July 2002

Modern approaches to the treatment of addiction have been influenced by several important factors. These include advances in our understanding of the nature of addiction based on longitudinal studies, and progress in elucidating the biological underpinnings of addictive behavior. In addition, changes in the system for delivery of services have begun to shape the way that addiction is treated.
Inhibition of Hyperalgesia by Ablation of Lamina I Spinal Neurons Expressing the Substance P Receptor
Authors: Mantyh Patrick W. , Rogers Scott D. , Honore Prisca , Allen Brian J. , Ghilardi Joseph R. , Li Jun , Daughters Randy S. , Lappi Douglas A. , Wiley Ronald G. , Simone Donald A.
Published: July 2002

Substance P is released in the spinal cord in response to painful stimuli, but its role in nociceptive signaling remains unclear. When a conjugate of substance P and the ribosome-inactivating protein saporin was infused into the spinal cord, it was internalized and cytotoxic to lamina I spinal cord neurons that express the substance P receptor. This treatment left responses to mild noxious stimuli unchanged, but markedly attenuated responses to highly noxious stimuli and mechanical and thermal hyperalgesia. Thus, lamina I spinal cord neurons that express the substance P receptor play a pivotal role in the transmission of highly noxious stimuli and the maintenance of hyperalgesia.
CDC20
and
CDH1
: A Family of Substrate-Specific Activators of APC-Dependent Proteolysis
Authors: Visintin Rosella , Prinz Susanne , Amon Angelika
Published: July 2002

Proteolysis mediated by the anaphase-promoting complex (APC) triggers chromosome segregation and exit from mitosis, yet its regulation is poorly understood. The conserved Cdc20 and Cdh1 proteins were identified as limiting, substrate-specific activators of APC-dependent proteolysis.
CDC20
was required for the degradation of the APC substrate Pds1 but not for that of other APC substrates, such as Clb2 and Ase1. Conversely,
cdh1Δ
mutants were impaired in the degradation of Ase1 and Clb2 but not in that of Pds1. Overexpression of either
CDC20
or
CDH1
was sufficient to induce APC-dependent proteolysis of the appropriate target in stages of the cell cycle in which substrates are normally stable.
The Spatial Dimension in Population Fluctuations
Authors: Ranta Esa , Kaitala Veijo , Lundberg Per
Published: July 2002

Theoretical research into the dynamics of coupled populations has suggested a rich ensemble of spatial structures that are created and maintained either by external disturbances or self-reinforcing interactions among the populations. Long-term data of the Canadian lynx from eight Canadian provinces display large-scale spatial synchrony in population fluctuations. The synchronous dynamics are not time-invariant, however, as pairs of populations that are initially in step may drift out of phase and back into phase. These observations are in agreement with predictions of a spatially-linked population model and support contemporary population ecology theory.
Rules of the Game
Authors: Rhodes Frank H. T.
Published: July 2002

Academic Duty.
DONALD KENNEDY. Harvard University Press, Cambridge, MA, 1997. viii, 310 pp., $29.95 or £19.95. ISBN 0-674-00222-9.
Cleavage of the BMP-4 Antagonist Chordin by Zebrafish Tolloid
Authors: Blader Patrick , Rastegar Sepand , Fischer Nadine , Strähle Uwe
Published: July 2002

Dorsoventral patterning of vertebrate and
Drosophila
embryos requires bone morphogenetic proteins (BMPs) and antagonists of BMP activity. The
Drosophila
gene
tolloid
encodes a metalloprotease similar to BMP-1 that interacts genetically with
decapentaplegic
, the
Drosophila
homolog of vertebrate BMP-2/4. Zebrafish embryos overexpressing a zebrafish homolog of
tolloid
were shown to resemble loss-of-function mutations in
chordino
, the zebrafish homolog of the
Xenopus
BMP-4 antagonist Chordin. Furthermore, Chordin was degraded by COS cells expressing Tolloid. These data suggest that Tolloid antagonizes Chordin activity by proteolytically cleaving Chordin. A conserved function for zebrafish and
Drosophila
Tolloid during embryogenesis is proposed.
Uncoupling of Immune Complex Formation and Kidney Damage in Autoimmune Glomerulonephritis
Authors: Clynes Raphael , Dumitru Calin , Ravetch Jeffrey V.
Published: July 2002

The generation of autoantibody and subsequent tissue deposition of immune complexes (IC) is thought to trigger the pathogenic consequences of systemic autoimmune disease. Modulation of the autoantibody response disrupts pathogenesis by preventing the formation of ICs; however, uncoupling IC formation from subsequent inflammatory responses seems unlikely because of the apparent complexity of the IC-triggered inflammatory cascade. However, the disruption of a single gene, which encodes the γ chain of the Fc receptor, was found to achieve this uncoupling in a spontaneous model of lupus nephritis, the New Zealand Black/New Zealand White (NZB/NZW) mouse. Gamma chain–deficient NZB/NZW mice generated and deposited IC and activated complement, but were protected from severe nephritis, thus defining another potential pathway for therapeutic intervention in autoimmune disease.
Direct Observation of Heterogeneous Chemistry in the Atmosphere
Authors: Gard Eric E. , Kleeman Michael J. , Gross Deborah S. , Hughes Lara S. , Allen Jonathan O. , Morrical Bradley D. , Fergenson David P. , Dienes Tas , E. Gälli Markus , Johnson Robert J. , Cass Glen R. , Prather Kimberly A.
Published: July 2002

The heterogeneous replacement of chloride by nitrate in individual sea-salt particles was monitored continuously over time in the troposphere with the use of aerosol time-of-flight mass spectrometry. Modeling calculations show that the observed chloride displacement process is consistent with a heterogeneous chemical reaction between sea-salt particles and gas-phase nitric acid, leading to sodium nitrate production in the particle phase accompanied by liberation of gaseous HCl from the particles. Such single-particle measurements, combined with a single-particle model, make it possible to monitor and explain heterogeneous gas/particle chemistry as it occurs in the atmosphere.
Linkage of Adhesion, Filamentous Growth, and Virulence in
Candida albicans
to a Single Gene,
INT1
Authors: Gale Cheryl A. , Bendel Catherine M. , McClellan Mark , Hauser Melinda , Becker Jeffrey M. , Berman Judith , Hostetter Margaret K.
Published: July 2002

Adhesion and the ability to form filaments are thought to contribute to the pathogenicity of
Candida albicans
, the leading cause of fungal disease in immunocompromised patients. Int1p is a
C. albicans
surface protein with limited similarity to vertebrate integrins.
INT1
expression in
Saccharomyces cerevisiae
was sufficient to direct the adhesion of this normally nonadherent yeast to human epithelial cells. Furthermore, disruption of
INT1
in
C. albicans
suppressed hyphal growth, adhesion to epithelial cells, and virulence in mice. Thus,
INT1
links adhesion, filamentous growth, and pathogenicity in
C. albicans
and Int1p may be an attractive target for the development of antifungal therapies.
Quantum Theory of Chemical Reaction Dynamics
Authors: Clary David C.
Published: July 2002

It is now possible to use rigorous quantum scattering theory to perform accurate calculations on the detailed state-to-state dynamics of chemical reactions in the gas phase. Calculations on simple reactions, such as H + D
2
→ HD + D and F + H
2
→ HF + H, compete with experiment in their accuracy. Recent advances in theory promise to extend such accurate predictions to more complicated reactions, such as OH + H
2
→ H
2
O + H, and even to reactions of molecules on solid surfaces. New experimental techniques for probing reaction transition states, such as negative-ion photodetachment spectroscopy and pump-probe femtosecond spectroscopy, are stimulating the development of new theories.
Induction of Lens Differentiation by Activation of a bZIP Transcription Factor, L-Maf
Authors: Ogino Hajime , Yasuda Kunio
Published: July 2002

After the vertebrate lens is induced from head ectoderm, lens-specific genes are expressed. Transcriptional regulation of the lens-specific αA-crystallin gene is controlled by an enhancer element, αCE2. A gene encoding an αCE2-binding protein,
L-maf
(lens-specific
maf
), was isolated.
L-maf
expression is initiated in the lens placode and is restricted to lens cells. The gene product L-Maf regulates the expression of multiple genes expressed in the lens, and ectopic expression of this transcription factor converts chick embryonic ectodermal cells and cultured cells into lens fibers. Thus, vertebrate lens induction and differentiation can be triggered by the activation of L-Maf.
A Monolithic Photovoltaic-Photoelectrochemical Device for Hydrogen Production via Water Splitting
Authors: Khaselev Oscar , Turner John A.
Published: July 2002

Direct water electrolysis was achieved with a novel, integrated, monolithic photoelectrochemical-photovoltaic design. This photoelectrochemical cell, which is voltage biased with an integrated photovoltaic device, splits water directly upon illumination; light is the only energy input. The hydrogen production efficiency of this system, based on the short-circuit current and the lower heating value of hydrogen, is 12.4 percent.
Anterior Cingulate Cortex, Error Detection, and the Online Monitoring of Performance
Authors: Carter Cameron S. , Braver Todd S. , Barch Deanna M. , Botvinick Matthew M. , Noll Douglas , Cohen Jonathan D.
Published: July 2002

An unresolved question in neuroscience and psychology is how the brain monitors performance to regulate behavior. It has been proposed that the anterior cingulate cortex (ACC), on the medial surface of the frontal lobe, contributes to performance monitoring by detecting errors. In this study, event-related functional magnetic resonance imaging was used to examine ACC function. Results confirm that this region shows activity during erroneous responses. However, activity was also observed in the same region during correct responses under conditions of increased response competition. This suggests that the ACC detects conditions under which errors are likely to occur rather than errors themselves.
Chemical Amplification: Continuous-Flow PCR on a Chip
Authors: Kopp Martin U. , Mello Andrew J. de , Manz Andreas
Published: July 2002

A micromachined chemical amplifier was successfully used to perform the polymerase chain reaction (PCR) in continuous flow at high speed. The device is analogous to an electronic amplifier and relies on the movement of sample through thermostated temperature zones on a glass microchip. Input and output of material (DNA) is continuous, and amplification is independent of input concentration. A 20-cycle PCR amplification of a 176–base pair fragment from the DNA gyrase gene of
Neisseria gonorrhoeae
was performed at various flow rates, resulting in total reaction times of 90 seconds to 18.7 minutes.
Cloned Transgenic Calves Produced from Nonquiescent Fetal Fibroblasts
Authors: Cibelli Jose B. , Stice Steve L. , Golueke Paul J. , Kane Jeff J. , Jerry Joseph , Blackwell Cathy , Ponce de León F. Abel , Robl James M.
Published: July 2002

An efficient system for genetic modification and large-scale cloning of cattle is of importance for agriculture, biotechnology, and human medicine. Here, actively dividing fetal fibroblasts were genetically modified with a marker gene, a clonal line was selected, and the cells were fused to enucleated mature oocytes. Out of 28 embryos transferred to 11 recipient cows, three healthy, identical, transgenic calves were generated. Furthermore, the life-span of near senescent fibroblasts could be extended by nuclear transfer, as indicated by population doublings in fibroblast lines derived from a 40-day-old fetal clone. With the ability to extend the life-span of these primary cultured cells, this system would be useful for inducing complex genetic modifications in cattle.
Molecular Basis for Interactions of G Protein βγ Subunits with Effectors
Authors: Ford Carolyn E. , Skiba Nikolai P. , Bae Hyunsu , Daaka Yehia , Reuveny Eitan , Shekter Lee R. , Rosal Ramon , Weng Gezhi , Yang Chii-Shen , Iyengar Ravi , Miller Richard J. , Jan Lily Y. , Lefkowitz Robert J. , Hamm Heidi E.
Published: July 2002

Both the α and βγ subunits of heterotrimeric guanine nucleotide–binding proteins (G proteins) communicate signals from receptors to effectors. Gβγ subunits can regulate a diverse array of effectors, including ion channels and enzymes. Gα subunits bound to guanine diphosphate (Gα-GDP) inhibit signal transduction through Gβγ subunits, suggesting a common interface on Gβγ subunits for Gα binding and effector interaction. The molecular basis for interaction of Gβγ with effectors was characterized by mutational analysis of Gβ residues that make contact with Gα-GDP. Analysis of the ability of these mutants to regulate the activity of calcium and potassium channels, adenylyl cyclase 2, phospholipase C-β2, and β-adrenergic receptor kinase revealed the Gβ residues required for activation of each effector and provides evidence for partially overlapping domains on Gβ for regulation of these effectors. This organization of interaction regions on Gβ for different effectors and Gα explains why subunit dissociation is crucial for signal transmission through Gβγ subunits.
Eclogitic Diamond Formation at Jwaneng: No Room for a Recycled Component
Authors: Cartigny Pierre , Harris Jeffrey W. , Javoy Marc
Published: July 2002

Eclogitic diamonds have a large range of δ
13
C values, whereas peridotitic diamonds do not. Paired δ
15
N-δ
13
C-N variations in 40 eclogitic diamonds from the Jwaneng kimberlite in Botswana show that neither the influence of recycled biogenic carbon nor the global and primordial heterogeneity of mantle carbon are likely for the origin of the large δ
13
C range; the data instead support a fractionation process. It is proposed that carbonatitic mantle melts from which diamonds crystallize undergo different evolutions before diamond precipitation, when percolating through either a peridotite or an eclogite. These different evolutions, reflecting the presence or absence of olivine, can account for their respective δ
13
C distributions.
Plasticity Induced by Shock Waves in Nonequilibrium Molecular-Dynamics Simulations
Authors: Holian Brad Lee , Lomdahl Peter S.
Published: July 2002

Nonequilibrium molecular-dynamics simulations of shock waves in three-dimensional 10-million atom face-centered cubic crystals with cross-sectional dimensions of 100 by 100 unit cells show that the system slips along all of the available {111} slip planes, in different places along the nonplanar shock front. Comparison of these simulations with earlier ones on a smaller scale not only eliminates the possibility that the observed slippage is an artifact of transverse periodic boundary conditions, but also reveals the richness of the nanostructure left behind. By introducing a piston face that is no longer perfectly flat, mimicking a line or surface inhomogeneity in the unshocked material, it is shown that for weaker shock waves (below the perfect-crystal yield strength), stacking faults can be nucleated by preexisting extended defects.
Going the Distance: A Current View of Enhancer Action
Authors: Blackwood Elizabeth M. , Kadonaga James T.
Published: July 2002

In eukaryotes, transcription of genes by RNA polymerase II yields messenger RNA intermediates from which protein products are synthesized. Transcriptional enhancers are discrete DNA elements that contain specific sequence motifs with which DNA-binding proteins interact and transmit molecular signals to genes. Here, current models regarding the role of enhancers in the regulation of transcription by RNA polymerase II are presented.
Mapping Natural Communities and Ecosystems
Authors: Suter Sherman
Published: July 2002

A Classification of North American Biotic Communities
.
By David E. Brown, Frank Reichenbacher, and Susan E. Franson
. University of Utah Press, Salt Lake City, 1998. 152 pp. Paper, $19.95. ISBN 0-87480-562-7. With 1:10,000,000 map, $34.95. ISBN 0-8748-0-568-6.

Ecoregions
The Ecosystem Geography of the Oceans and Continents.
By Robert G. Bailey
. Springer, New York, 1998. 186 pp. $79.95. ISBN 0-387-98305-8. Paper, $39.95. ISBN 0-387-98311-2.
Uncoupling of Nonreceptor Tyrosine Kinases from PLC-γ1 in an SLP-76-Deficient T Cell
Authors: Yablonski Deborah , Kuhne Michelle R. , Kadlecek Theresa , Weiss Arthur
Published: July 2002

Activation of nonreceptor protein tyrosine kinases (PTKs) is essential for T cell receptor (TCR) responsiveness; however, the function of individual PTK substrates is often uncertain. A mutant T cell line was isolated that lacked expression of SLP-76 (SH2 domain–containing leukocyte protein of 76 kilodaltons), a hematopoietically expressed adaptor protein and PTK substrate. SLP-76 was not required for TCR-induced tyrosine phosphorylation of most proteins, but was required for optimal tyrosine phosphorylation and activation of phospholipase C-γ1 (PLC-γ1), as well as Ras pathway activation. TCR-inducible gene expression was dependent on SLP-76. Thus, coupling of TCR-regulated PTKs to downstream signaling pathways requires SLP-76.
Still Stimulating After All These Years
Authors: Pinker Steven
Published: July 2002

The Expression of the Emotions in Man and Animals
.
Charles Darwin
. Third edition, with Introduction, Afterword and Commentaries.
Paul Ekman
. Oxford University Press, New York, and HarperCollins, London, 1998. 509 pp. $30, ISBN 0-19-511271-7. £16.99, ISBN 0-00-255866-1.
Rotation of a Single Molecule Within a Supramolecular Bearing
Authors: Gimzewski J. K. , Joachim C. , Schlittler R. R. , Langlais V. , Tang H. , Johannsen I.
Published: July 2002

Experimental visualization and verification of a single-molecule rotor operating within a supramolecular bearing is reported. Using a scanning tunneling microscope, single molecules were observed to exist in one of two spatially defined states laterally separated by 0.26 nanometers. One was identified as a rotating state and the other as an immobilized state. Calculations of the energy barrier for rotation of these two states show that it is below the thermal energy at room temperature for the rotating state and above it for the immobilized state.
Reconstitution of Peptide Bond Formation with
Escherichia coli
23
S
Ribosomal RNA Domains
Authors: Nitta Itaru , Kamada Yoshie , Noda Hiroe , Ueda Takuya , Watanabe Kimitsuna
Published: July 2002

It was recently demonstrated that peptide bond formation can occur using an
Escherichia coli
naked 23
S
ribosomal RNA without any of the ribosomal proteins. Here, the six domains of the 23
S
ribosomal RNA were individually synthesized and shown to be capable, when complexed together, of stimulating the reaction. Omission and addition experiments indicated that the activity could be reconstituted solely by domain V at a concentration 10 times higher than that of the intact 23
S
ribosomal RNA, whereas domain VI could enhance the activity in
trans
. These findings suggest that fragments of an RNA molecule have the ability to associate into a functional whole.
Fluxes of Fast and Epithermal Neutrons from Lunar Prospector: Evidence for Water Ice at the Lunar Poles
Authors: Feldman W. C. , Maurice S. , Binder A. B. , Barraclough B. L. , Elphic R. C. , Lawrence D. J.
Published: July 2002

Maps of epithermal- and fast-neutron fluxes measured by Lunar Prospector were used to search for deposits enriched in hydrogen at both lunar poles. Depressions in epithermal fluxes were observed close to permanently shaded areas at both poles. The peak depression at the North Pole is 4.6 percent below the average epithermal flux intensity at lower latitudes, and that at the South Pole is 3.0 percent below the low-latitude average. No measurable depression in fast neutrons is seen at either pole. These data are consistent with deposits of hydrogen in the form of water ice that are covered by as much as 40 centimeters of desiccated regolith within permanently shaded craters near both poles.
Segregation of Transcription and Replication Sites Into Higher Order Domains
Authors: Wei Xiangyun , Samarabandu Jagath , Devdhar Rakendu S. , Siegel Alan J. , Acharya Raj , Berezney Ronald
Published: July 2002

Microscopy shows that individual sites of DNA replication and transcription of mammalian nuclei segregate into sets of roughly 22 and 16 higher order domains, respectively. Each domain set displayed a distinct network-like appearance, including regions of individual domains and interdigitation of domains between the two networks. These data support a dynamic mosaic model for the higher order arrangement of genomic function inside the cell nuclei.
Disruption of a Neuropeptide Gene,
flp-1
, Causes Multiple Behavioral Defects in
Caenorhabditis elegans
Authors: Nelson Laura S. , Rosoff Marc L. , Li Chris
Published: July 2002

Neuropeptides serve as important signaling molecules in the nervous system. The FMRFamide (Phe-Met-Arg-Phe-amide)–related neuropeptide gene family in the nematode
Caenorhabditis elegans
is composed of at least 18 genes that may encode 53 distinct FMRFamide-related peptides. Disruption of one of these genes,
flp-1
, causes numerous behavioral defects, including uncoordination, hyperactivity, and insensitivity to high osmolarity. Conversely, overexpression of
flp-1
results in the reciprocal phenotypes. On the basis of epistasis analysis,
flp-1
gene products appear to signal upstream of a G protein–coupled second messenger system. These results demonstrate that varying the levels of FLP-1 neuropeptides can profoundly affect behavior and that members of this large neuropeptide gene family are not functionally redundant in
C. elegans
.
A Skeptic's Sense of Wonder
Authors: Richardson W. Mark
Published: July 2002

Skeptics and True Believers
The Exhilarating Connection Between Science and Religion. Chet Raymo. Walker, New York, 1998. 300 pp. $23. ISBN 0-8027-1338-6.

Chet Raymo, a science writer and professor of astronomy and physics, wishes to bridge the gap between the scientific and spiritual communities with a scientifically enlightened new religious consciousness. The reviewer found "no positive claims of a religious sort ... but many scientific experiences of wonder and awe, many breathtaking observations that lead to apprehensions of mystery."
Harnessing the Biosynthetic Code: Combinations, Permutations, and Mutations
Authors: Cane David E. , Walsh Christopher T. , Khosla Chaitan
Published: July 2002

Polyketides and non-ribosomal peptides are two large families of complex natural products that are built from simple carboxylic acid or amino acid monomers, respectively, and that have important medicinal or agrochemical properties. Despite the substantial differences between these two classes of natural products, each is synthesized biologically under the control of exceptionally large, multifunctional proteins termed polyketide synthases (PKSs) and non-ribosomal peptide synthetases (NRPSs) that contain repeated, coordinated groups of active sites called modules, in which each module is responsible for catalysis of one complete cycle of polyketide or polypeptide chain elongation and associated functional group modifications. It has recently become possible to use molecular genetic methodology to alter the number, content, and order of such modules and, in so doing, to alter rationally the structure of the resultant products. This review considers the promise and challenges inherent in the combinatorial manipulation of PKS and NRPS structure in order to generate entirely “unnatural” products.
Alterations of the
PPP2R1B
Gene in Human Lung and Colon Cancer
Authors: Wang Steven Siqing , Esplin Edward D. , Li Jia Ling , Huang Liying , Gazdar Adi , Minna John , Evans Glen A.
Published: July 2002

The
PPP2R1B
gene, which encodes the β isoform of the A subunit of the serine/threonine protein phosphatase 2A (PP2A), was identified as a putative human tumor suppressor gene. Sequencing of the
PPP2R1B
gene, located on human chromosome 11q22-24, revealed somatic alterations in 15% (5 out of 33) of primary lung tumors, 6% (4 out of 70) of lung tumor–derived cell lines, and 15% (2 out of 13) of primary colon tumors. One deletion mutation generated a truncated PP2A-Aβ protein that was unable to bind to the catalytic subunit of the PP2A holoenzyme. The
PP2R1B
gene product may suppress tumor development through its role in cell cycle regulation and cellular growth control.
A Modest Maker of Modern Physics
Authors: Arnold Lorna
Published: July 2002

The Neutron and the Bomb
A Biography of Sir James Chadwick. Andrew Brown. Oxford University Press, New York, 1997. 402 pp. $35. ISBN 0-19-853992-4.

Brown, an English radiation oncologist, provides the first biography of the physicist who discovered the neutron, helped write the "Maud" report that led the British and Americans to pursue nuclear weapons, and was the chief British scientist on the Manhattan Project.
Controlling Factors for the Brittle-to-Ductile Transition in Tungsten Single Crystals
Authors: Gumbsch Peter , Riedle Joachim , Hartmaier Alexander , Fischmeister Hellmut F.
Published: July 2002

Materials performance in structural applications is often restricted by a transition from ductile response to brittle fracture with decreasing temperature. This transition is currently viewed as being controlled either by dislocation mobility or by the nucleation of dislocations. Fracture experiments on tungsten single crystals reported here provide evidence for the importance of dislocation nucleation for the fracture toughness in the semibrittle regime. However, it is shown that the transition itself, in general, is controlled by dislocation mobility rather than by nucleation.
A Receptor/Cytoskeletal Movement Triggered by Costimulation During T Cell Activation
Authors: Wülfing Christoph , Davis Mark M.
Published: July 2002

During T cell activation, the engagement of costimulatory molecules is often crucial to the development of an effective immune response, but the mechanism by which this is achieved is not known. Here, it is shown that beads attached to the surface of a T cell translocate toward the interface shortly after the start of T cell activation. This movement appears to depend on myosin motor proteins and requires the engagement of the major costimulatory receptor pairs, B7-CD28 and ICAM-1–LFA-1. This suggests that the engagement of costimulatory receptors triggers an active accumulation of molecules at the interface of the T cell and the antigen-presenting cell, which then increases the overall amplitude and duration of T cell signaling.
Going to Extremes in America
Authors: Bowler Peter J.
Published: July 2002

Darwinism Comes to America
. Ronald L. Numbers. Harvard University Press, Cambridge, MA, 1998. 222 pp. $39.95. ISBN 0-674-19311-3. Paper, $18.95. ISBN 0-674-19312-1.

This study of the reaction to Darwinism in the United States dispels many myths about the origin, development, and distribution of creationism. The reviewer notes Number's sophisticated analysis of the 19th-century debates and suggests that paying less attention to the 20th-century clashes between modern Darwinists and Fundamentalists might provide interesting perspectives on moderates who sought to reconcile modern science and traditional faith.
Isotopic Evidence for the Diet of an Early Hominid,
Australopithecus africanus
Authors: Sponheimer Matt , Lee-Thorp Julia A.
Published: July 2002

Current consensus holds that the 3-million-year-old hominid
Australopithecus africanus
subsisted on fruits and leaves, much as the modern chimpanzee does. Stable carbon isotope analysis of
A. africanus
from Makapansgat Limeworks, South Africa, demonstrates that this early hominid ate not only fruits and leaves but also large quantities of carbon-13–enriched foods such as grasses and sedges or animals that ate these plants, or both. The results suggest that early hominids regularly exploited relatively open environments such as woodlands or grasslands for food. They may also suggest that hominids consumed high-quality animal foods before the development of stone tools and the origin of the genus
Homo
.
Entrancing Influences
Authors: Gauld Alan
Published: July 2002

Mesmerized
Powers of Mind in Victorian Britain. Alison Winter. University of Chicago Press, Chicago, 1998. 478 pp. $30.00, £23.95. ISBN 0-226-90219-6.

The development of scientific and medical authority and the understanding of mental functioning are among the many issues of the history of science and social history that Winter explores while discussing the rise and fall of mesmerism in England.