bluuebunny/crossref_metadata_2025 huggingface dataset:
Global Analysis of Protein Activities Using Proteome Chips
Authors: Zhu Heng , Bilgin Metin , Bangham Rhonda , Hall David , Casamayor Antonio , Bertone Paul , Lan Ning , Jansen Ronald , Bidlingmaier Scott , Houfek Thomas , Mitchell Tom , Miller Perry , Dean Ralph A. , Gerstein Mark , Snyder Michael
Published: July 2002

To facilitate studies of the yeast proteome, we cloned 5800 open reading frames and overexpressed and purified their corresponding proteins. The proteins were printed onto slides at high spatial density to form a yeast proteome microarray and screened for their ability to interact with proteins and phospholipids. We identified many new calmodulin- and phospholipid-interacting proteins; a common potential binding motif was identified for many of the calmodulin-binding proteins. Thus, microarrays of an entire eukaryotic proteome can be prepared and screened for diverse biochemical activities. The microarrays can also be used to screen protein-drug interactions and to detect posttranslational modifications.
Resolving the Structure of Ionized Helium in the Intergalactic Medium with the Far Ultraviolet Spectroscopic Explorer
Authors: Kriss G. A. , Shull J. M. , Oegerle W. , Zheng W. , Davidsen A. F. , Songaila A. , Tumlinson J. , Cowie L. L. , Deharveng J.-M. , Friedman S. D. , Giroux M. L. , Green R. F. , Hutchings J. B. , Jenkins E. B. , Kruk J. W. , Moos H. W. , Morton D. C. , Sembach K. R. , Tripp T. M.
Published: July 2002

The neutral hydrogen (H
i
) and ionized helium (He
ii
) absorption in the spectra of quasars are unique probes of structure in the early universe. We present Far-Ultraviolet Spectroscopic Explorer observations of the line of sight to the quasar HE2347-4342 in the 1000 to 1187 angstrom band at a resolving power of 15,000. We resolve the He
ii
Lyman α (Lyα) absorption as a discrete forest of absorption lines in the redshift range 2.3 to 2.7. About 50 percent of these features have H
i
counterparts with column densities
N

H
i

> 10
12.3
per square centimeter that account for most of the observed opacity in He
ii
Lyα. The He
ii
to H
i
column density ratio ranges from 1 to >1000, with an average of ∼80. Ratios of <100 are consistent with photoionization of the absorbing gas by a hard ionizing spectrum resulting from the integrated light of quasars, but ratios of >100 in many locations indicate additional contributions from starburst galaxies or heavily filtered quasar radiation. The presence of He
ii
Lyα absorbers with no H
i
counterparts indicates that structure is present even in low-density regions, consistent with theoretical predictions of structure formation through gravitational instability.
Self-Assembly and Mineralization of Peptide-Amphiphile Nanofibers
Authors: Hartgerink Jeffrey D. , Beniash Elia , Stupp Samuel I.
Published: July 2002

We have used the pH-induced self-assembly of a peptide-amphiphile to make a nanostructured fibrous scaffold reminiscent of extracellular matrix. The design of this peptide-amphiphile allows the nanofibers to be reversibly cross-linked to enhance or decrease their structural integrity. After cross-linking, the fibers are able to direct mineralization of hydroxyapatite to form a composite material in which the crystallographic
c
axes of hydroxyapatite are aligned with the long axes of the fibers. This alignment is the same as that observed between collagen fibrils and hydroxyapatite crystals in bone.
A Cortical Area Selective for Visual Processing of the Human Body
Authors: Downing Paul E. , Jiang Yuhong , Shuman Miles , Kanwisher Nancy
Published: July 2002

Despite extensive evidence for regions of human visual cortex that respond selectively to faces, few studies have considered the cortical representation of the appearance of the rest of the human body. We present a series of functional magnetic resonance imaging (fMRI) studies revealing substantial evidence for a distinct cortical region in humans that responds selectively to images of the human body, as compared with a wide range of control stimuli. This region was found in the lateral occipitotemporal cortex in all subjects tested and apparently reflects a specialized neural system for the visual perception of the human body.
Mammalian TOR: A Homeostatic ATP Sensor
Authors: Dennis Patrick B. , Jaeschke Anja , Saitoh Masao , Fowler Brian , Kozma Sara C. , Thomas George
Published: July 2002

The bacterial macrolide rapamycin is an efficacious anticancer agent against solid tumors. In a hypoxic environment, the increase in mass of solid tumors is dependent on the recruitment of mitogens and nutrients. When nutrient concentrations change, particularly those of essential amino acids, the mammalian Target of Rapamycin (mTOR) functions in regulatory pathways that control ribosome biogenesis and cell growth. In bacteria, ribosome biogenesis is independently regulated by amino acids and adenosine triphosphate (ATP). Here we demonstrate that the mTOR pathway is influenced by the intracellular concentration of ATP, independent of the abundance of amino acids, and that mTOR itself is an ATP sensor.
Constraints on Melt Movement Beneath the East Pacific Rise From
230
Th-
238
U Disequilibrium
Authors: Zou Haibo , Zindler Alan , Niu Yaoling
Published: July 2002

We report
230
Th-
238
U disequilibrium data on mid-ocean ridge basalts recovered 5 to 40 kilometers off the ridge axis near 9°30′N of the East Pacific Rise. These data indicate near-symmetrical eruptions of normal mid-ocean ridge basalts (NMORBs) and incompatible element–enriched mid-ocean ridge basalts (EMORBs) as far as 20 kilometers off axis. Our results suggest large-scale subsurface lateral transport of NMORB melt at 19 to 21 centimeters per year and also provide constraints on the petrogenesis of EMORBs of off-axis origin.
Enzyme Dynamics During Catalysis
Authors: Eisenmesser Elan Zohar , Bosco Daryl A. , Akke Mikael , Kern Dorothee
Published: July 2002

Internal protein dynamics are intimately connected to enzymatic catalysis. However, enzyme motions linked to substrate turnover remain largely unknown. We have studied dynamics of an enzyme during catalysis at atomic resolution using nuclear magnetic resonance relaxation methods. During catalytic action of the enzyme cyclophilin A, we detect conformational fluctuations of the active site that occur on a time scale of hundreds of microseconds. The rates of conformational dynamics of the enzyme strongly correlate with the microscopic rates of substrate turnover. The present results, together with available structural data, allow a prediction of the reaction trajectory.
Earthquake Recurrence and Rupture Dynamics of Himalayan Frontal Thrust, India
Authors: Kumar Senthil , Wesnousky Steven G. , Rockwell Thomas K. , Ragona Daniel , Thakur Vikram C. , Seitz Gordon G.
Published: July 2002

The Black Mango fault is a structural discontinuity that transforms motion between two segments of the active Himalayan Frontal Thrust (HFT) in northwestern India. The Black Mango fault displays evidence of two large surface rupture earthquakes during the past 650 years, subsequent to 1294 A.D. and 1423 A.D., and possibly another rupture at about 260 A.D. Displacement during the last two earthquakes was at minimum 4.6 meters and 2.4 to 4.0 meters, respectively, and possibly larger for the 260 A.D. event. Abandoned terraces of the adjacent Markanda River record uplift due to slip on the underlying HFT of 4.8 ± 0.9 millimeters per year or greater since the mid-Holocene. The uplift rate is equivalent to rates of fault slip and crustal shortening of 9.6
−3.5
+7.0
millimeters per year and 8.4
−3.6
+7.3
millimeters per year, respectively, when it is assumed that the HFT dips 30° ± 10°.
Global Allocation Rules for Patterns of Biomass Partitioning in Seed Plants
Authors: Enquist Brian J. , Niklas Karl J.
Published: July 2002

A general allometric model has been derived to predict intraspecific and interspecific scaling relationships among seed plant leaf, stem, and root biomass. Analysis of a large compendium of standing organ biomass sampled across a broad sampling of taxa inhabiting diverse ecological habitats supports the relations predicted by the model and defines the boundary conditions for above- and below-ground biomass partitioning. These canonical biomass relations are insensitive to phyletic affiliation (conifers versus angiosperms) and variation in averaged local environmental conditions. The model thus identifies and defines the limits that have guided the diversification of seed plant biomass allocation strategies.
Role of
Escherichia coli
Curli Operons in Directing Amyloid Fiber Formation
Authors: Chapman Matthew R. , Robinson Lloyd S. , Pinkner Jerome S. , Roth Robyn , Heuser John , Hammar Mårten , Normark Staffan , Hultgren Scott J.
Published: July 2002

Amyloid is associated with debilitating human ailments including Alzheimer's and prion diseases. Biochemical, biophysical, and imaging analyses revealed that fibers produced by
Escherichia coli
called curli were amyloid. The CsgA curlin subunit, purified in the absence of the CsgB nucleator, adopted a soluble, unstructured form that upon prolonged incubation assembled into fibers that were indistinguishable from curli. In vivo, curli biogenesis was dependent on the nucleation-precipitation machinery requiring the CsgE and CsgF chaperone-like and nucleator proteins, respectively. Unlike eukaryotic amyloid formation, curli biogenesis is a productive pathway requiring a specific assembly machinery.
Efficient Near-Infrared Polymer Nanocrystal Light-Emitting Diodes
Authors: Tessler Nir , Medvedev Vlad , Kazes Miri , Kan ShiHai , Banin Uri
Published: July 2002

Conjugated polymers and indium arsenide–based nanocrystals were used to create near-infrared plastic light-emitting diodes. Emission was tunable from 1 to 1.3 micrometers—a range that effectively covers the short-wavelength telecommunications band—by means of the quantum confinement effects in the nanocrystals. The external efficiency value (photons out divided by electrons in) is ∼0.5% (that is, >1% internal) and is mainly limited by device architecture. The near-infrared emission did not overlap the charge-induced absorption bands of the polymer.
Clustered Star Formation and the Origin of Stellar Masses
Authors: Pudritz Ralph E.
Published: July 2002

Star clusters are ubiquitous in galaxies of all types and at all stages of their evolution. We also observe them to be forming in a wide variety of environments, ranging from nearby giant molecular clouds to the supergiant molecular clouds found in starburst and merging galaxies. The typical star in our galaxy and probably in others formed as a member of a star cluster, so star formation is an intrinsically clustered and not an isolated phenomenon. The greatest challenge regarding clustered star formation is to understand why stars have a mass spectrum that appears to be universal. This review examines the observations and models that have been proposed to explain these fundamental issues in stellar formation.
The Hydride Anion in an Extended Transition Metal Oxide Array: LaSrCoO
3
H
0.7
Authors: Hayward M. A. , Cussen E. J. , Claridge J. B. , Bieringer M. , Rosseinsky M. J. , Kiely C. J. , Blundell S. J. , Marshall I. M. , Pratt F. L.
Published: July 2002

We present the synthesis and structural characterization of a transition metal oxide hydride, LaSrCoO
3
H
0.7
, which adopts an unprecedented structure in which oxide chains are bridged by hydride anions to form a two-dimensional extended network. The metal centers are strongly coupled by their bonding with both oxide and hydride ligands to produce magnetic ordering at temperatures up to at least 350 kelvin. The synthetic route is sufficiently general to allow the prediction of a new class of transition metal–containing electronic and magnetic materials.
Effectiveness of Donor Natural Killer Cell Alloreactivity in Mismatched Hematopoietic Transplants
Authors: Ruggeri Loredana , Capanni Marusca , Urbani Elena , Perruccio Katia , Shlomchik Warren D. , Tosti Antonella , Posati Sabrina , Rogaia Daniela , Frassoni Francesco , Aversa Franco , Martelli Massimo F. , Velardi Andrea
Published: July 2002

T cells that accompany allogeneic hematopoietic grafts for treating leukemia enhance engraftment and mediate the graft-versus-leukemia effect. Unfortunately, alloreactive T cells also cause graft-versus-host disease (GVHD). T cell depletion prevents GVHD but increases the risk of graft rejection and leukemic relapse. In human transplants, we show that donor-versus-recipient natural killer (NK)–cell alloreactivity could eliminate leukemia relapse and graft rejection and protect patients against GVHD. In mice, the pretransplant infusion of alloreactive NK cells obviated the need for high-intensity conditioning and reduced GVHD. NK cell alloreactivity may thus provide a powerful tool for enhancing the efficacy and safety of allogeneic hematopoietic transplantation.
Experimental Quantum Cloning of Single Photons
Authors: Lamas-Linares Antı́a , Simon Christoph , Howell John C. , Bouwmeester Dik
Published: July 2002

Although perfect copying of unknown quantum systems is forbidden by the laws of quantum mechanics, approximate cloning is possible. A natural way of realizing quantum cloning of photons is by stimulated emission. In this context, the fundamental quantum limit to the quality of the clones is imposed by the unavoidable presence of spontaneous emission. In our experiment, a single input photon stimulates the emission of additional photons from a source on the basis of parametric down-conversion. This leads to the production of quantum clones with near-optimal fidelity. We also demonstrate universality of the copying procedure by showing that the same fidelity is achieved for arbitrary input states.
Mantophasmatodea: A New Insect Order with Extant Members in the Afrotropics
Authors: Klass Klaus-D. , Zompro Oliver , Kristensen Niels P. , Adis Joachim
Published: July 2002

A new insect order, Mantophasmatodea, is described on the basis of museum specimens of a new genus with two species:
Mantophasma zephyra
gen. et sp. nov. (one female from Namibia) and
M. subsolana
sp. nov. (one male from Tanzania). This is the first time since 1914 that a newly described extant insect taxon has proved unplaceable within a recognized order. Mantophasmatodeans are apterous carnivores. Their closest phylogenetic relationships may be to Grylloblattodea (ice-crawlers) and/or Phasmatodea (stick insects), but the morphological evidence is ambiguous.
Raptophasma
Zompro from Baltic amber is assigned to the Mantophasmatodea, revealing a wider previous range for the lineage.
Genetic Dissection of Transcriptional Regulation in Budding Yeast
Authors: Brem Rachel B. , Yvert Gaël , Clinton Rebecca , Kruglyak Leonid
Published: July 2002

To begin to understand the genetic architecture of natural variation in gene expression, we carried out genetic linkage analysis of genomewide expression patterns in a cross between a laboratory strain and a wild strain of
Saccharomyces cerevisiae
. Over 1500 genes were differentially expressed between the parent strains. Expression levels of 570 genes were linked to one or more different loci, with most expression levels showing complex inheritance patterns. The loci detected by linkage fell largely into two categories: cis-acting modulators of single genes and trans-acting modulators of many genes. We found eight such trans-acting loci, each affecting the expression of a group of 7 to 94 genes of related function.
Ferroelectric Bi
3.25
La
0.75
Ti
3
O
12
Films of Uniform
a
-Axis Orientation on Silicon Substrates
Authors: Lee Ho Nyung , Hesse Dietrich , Zakharov Nikolai , Gösele Ulrich
Published: July 2002

The use of bismuth-layered perovskite films for planar-type nonvolatile ferroelectric random-access memories requires films with spontaneous polarization normal to the plane of growth. Epitaxially twinned
a
axis–oriented La-substituted Bi
4
Ti
3
O
12
(BLT) thin films whose spontaneous polarization is entirely along the film normal were grown by pulsed laser deposition on yttria-stabilized zirconia-buffered Si(100) substrates using SrRuO
3
as bottom electrodes. Even though the (118) orientation competes with the (100) orientation, epitaxial films with almost pure (100) orientation were grown using very thin, strained SrRuO
3
electrode layers and kinetic growth conditions, including high growth rates and high oxygen background pressures to facilitate oxygen incorporation into the growing film. Films with the
a
-axis orientation and having their polarization entirely along the direction normal to the film plane can achieve a remanent polarization of 32 microcoulombs per square centimeter.
Reverse Engineering of Biological Complexity
Authors: Csete Marie E. , Doyle John C.
Published: July 2002

Advanced technologies and biology have extremely different physical implementations, but they are far more alike in systems-level organization than is widely appreciated. Convergent evolution in both domains produces modular architectures that are composed of elaborate hierarchies of protocols and layers of feedback regulation, are driven by demand for robustness to uncertain environments, and use often imprecise components. This complexity may be largely hidden in idealized laboratory settings and in normal operation, becoming conspicuous only when contributing to rare cascading failures. These puzzling and paradoxical features are neither accidental nor artificial, but derive from a deep and necessary interplay between complexity and robustness, modularity, feedback, and fragility. This review describes insights from engineering theory and practice that can shed some light on biological complexity.
Coda Wave Interferometry for Estimating Nonlinear Behavior in Seismic Velocity
Authors: Snieder Roel , Grêt Alexandre , Douma Huub , Scales John
Published: July 2002

In coda wave interferometry, one records multiply scattered waves at a limited number of receivers to infer changes in the medium over time. With this technique, we have determined the nonlinear dependence of the seismic velocity in granite on temperature and the associated acoustic emissions. This technique can be used in warning mode, to detect the presence of temporal changes in the medium, or in diagnostic mode, where the temporal change in the medium is quantified.
Ablation of Insulin-Producing Neurons in Flies: Growth and Diabetic Phenotypes
Authors: Rulifson Eric J. , Kim Seung K. , Nusse Roel
Published: July 2002

In the fruit fly
Drosophila
, four insulin genes are coexpressed in small clusters of cells [insulin-producing cells (IPCs)] in the brain. Here, we show that ablation of these IPCs causes developmental delay, growth retardation, and elevated carbohydrate levels in larval hemolymph. All of the defects were reversed by ectopic expression of a
Drosophila
insulin transgene. On the basis of these functional data and the observation that IPCs release insulin into the circulatory system, we conclude that brain IPCs are the main systemic supply of insulin during larval growth. We propose that IPCs and pancreatic islet β cells are functionally analogous and may have evolved from a common ancestral insulin-producing neuron. Interestingly, the phenotype of flies lacking IPCs includes certain features of diabetes mellitus.
Toward Self-Organization and Complex Matter
Authors: Lehn Jean-Marie
Published: July 2002

Beyond molecular chemistry based on the covalent bond, supramolecular chemistry aims at developing highly complex chemical systems from components interacting through noncovalent intermolecular forces. Over the past quarter century, supramolecular chemistry has grown into a major field and has fueled numerous developments at the interfaces with biology and physics. Some of the conceptual advances and future challenges are profiled here.
A Heat-Sensitive TRP Channel Expressed in Keratinocytes
Authors: Peier Andrea M. , Reeve Alison J. , Andersson David A. , Moqrich Aziz , Earley Taryn J. , Hergarden Anne C. , Story Gina M. , Colley Sian , Hogenesch John B. , McIntyre Peter , Bevan Stuart , Patapoutian Ardem
Published: July 2002

Mechanical and thermal cues stimulate a specialized group of sensory neurons that terminate in the skin. Three members of the transient receptor potential (TRP) family of channels are expressed in subsets of these neurons and are activated at distinct physiological temperatures. Here, we describe the cloning and characterization of a novel thermosensitive TRP channel. TRPV3 has a unique threshold: It is activated at innocuous (warm) temperatures and shows an increased response at noxious temperatures. TRPV3 is specifically expressed in keratinocytes; hence, skin cells are capable of detecting heat via molecules similar to those in heat-sensing neurons.
An Adenovirus Mutant That Replicates Selectively in p53- Deficient Human Tumor Cells
Authors: Bischoff James R. , Kirn David H. , Williams Angelica , Heise Carla , Horn Sharon , Muna Mike , Ng Lelia , Nye Julie A. , Sampson-Johannes Adam , Fattaey Ali , McCormick Frank
Published: July 2002

The human adenovirus
E1B
gene encodes a 55-kilodalton protein that inactivates the cellular tumor suppressor protein p53. Here it is shown that a mutant adenovirus that does not express this viral protein can replicate in and lyse p53-deficient human tumor cells but not cells with functional p53. Ectopic expression of the 55-kilodalton EIB protein in the latter cells rendered them sensitive to infection with the mutant virus. Injection of the mutant virus into p53-deficient human cervical carcinomas grown in nude mice caused a significant reduction in tumor size and caused complete regression of 60 percent of the tumors. These data raise the possibility that mutant adenoviruses can be used to treat certain human tumors.
Electron Beams and Ion Composition Measured at Io and in Its Torus
Authors: Williams D. J. , Mauk B. H. , McEntire R. E. , Roelof E. C. , Armstrong T. P. , Wilken B. , Roederer J. G. , Krimigis S. M. , Fritz T. A. , Lanzerotti L. J.
Published: July 2002

Intense, magnetic field-aligned, bidirectional, energetic (>15 kiloelectron volts) electron beams were discovered by the Galileo energetic particles detector during the flyby of Io. These beams can carry sufficient energy flux into Jupiter's atmosphere to produce a visible aurora at the footprint of the magnetic flux tube connecting Io to Jupiter. Composition measurements through the torus showed that the spatial distributions of protons, oxygen, and sulfur are different, with sulfur being the dominant energetic (>∼10 kiloelectron volts per nucleon) ion at closest approach.
Sudden and Gradual Molluscan Extinctions in the Latest Cretaceous of Western European Tethys
Authors: Marshall Charles R. , Ward Peter D.
Published: July 2002

Incompleteness of the fossil record has confounded attempts to establish the role of the end-Cretaceous bolide impact in the Late Cretaceous mass extinctions. Statistical analysis of latest Cretaceous outer-shelf macrofossils from western European Tethys reveals (i) a major extinction at or near the Cretaceous-Tertiary (K-T) boundary, probably caused by the impact, (ii) either a faunal abundance change or an extinction of up to nine ammonite species associated with a regression event shortly before the boundary, (iii) gradual extinction of most inoceramid bivalves well before the K-T boundary, and (iv) background extinction of approximately six ammonites throughout the latest Cretaceous.
Functions of Ceramide in Coordinating Cellular Responses to Stress
Authors: Hannun Yusuf A.
Published: July 2002

Sphingolipid metabolites participate in key events of signal transduction and cell regulation. In the sphingomyelin cycle, a number of extracellular agents and insults (such as tumor necrosis factor, Fas ligands, and chemotherapeutic agents) cause the activation of sphingomyelinases, which act on membrane sphingomyelin and release ceramide. Multiple experimental approaches suggest an important role for ceramide in regulating such diverse responses as cell cycle arrest, apoptosis, and cell senescence. In vitro, ceramide activates a serine-threonine protein phosphatase, and in cells it regulates protein phosphorylation as well as multiple downstream targets [such as interleukin converting enzyme (ICE)-like proteases, stress-activated protein kinases, and the retinoblastoma gene product] that mediate its distinct cellular effects. This spectrum of inducers of ceramide accumulation and the nature of ceramide-mediated responses suggest that ceramide is a key component of intracellular stress response pathways.
Structure of Staphylococcal α-Hemolysin, a Heptameric Transmembrane Pore
Authors: Song Langzhou , Hobaugh Michael R. , Shustak Christopher , Cheley Stephen , Bayley Hagan , Gouaux J. Eric
Published: July 2002

The structure of the
Staphylococcus aureus
α-hemolysin pore has been determined to 1.9 Å resolution. Contained within the mushroom-shaped homo-oligomeric heptamer is a solvent-filled channel, 100 Å in length, that runs along the sevenfold axis and ranges from 14 Å to 46 Å in diameter. The lytic, transmembrane domain comprises the lower half of a 14-strand antiparallel β barrel, to which each protomer contributes two β strands, each 65 Å long. The interior of the β barrel is primarily hydrophilic, and the exterior has a hydrophobic belt 28 Å wide. The structure proves the heptameric subunit stoichiometry of the α-hemolysin oligomer, shows that a glycine-rich and solvent-exposed region of a water-soluble protein can self-assemble to form a transmembrane pore of defined structure, and provides insight into the principles of membrane interaction and transport activity of β barrel pore-forming toxins.
Seeking a Simple Complex System
Authors: Aeppli G. , Chandra P.
Published: July 2002

Solids are usually shown in textbooks as perfect periodic structures, but real solids often have substantial disorder. This disorder leads to completely new and often complex behavior. In their Perspective, Aeppli and Chandra describe the search for systems that are simple enough to understand theoretically, but that still exhibit interesting complexity. Magnetic systems may fulfill this need and might lead to new systems for information storage and computation.
Yangtze Seen as Earliest Rice Site
Authors: Normile Dennis
Published: July 2002

NARA, JAPAN
—The Yangtze region could predate the more politically powerful Yellow River area to the north as both the site of the oldest civilization in China and the earliest cultivation of rice anywhere on Earth, according to preliminary findings by a team of Japanese and Chinese archaeologists. The report comes from the International Symposium on Agriculture and Civilizations, held here last month.
Vascular System Defects and Impaired Cell Chemokinesis as a Result of Gα
13
Deficiency
Authors: Offermanns Stefan , Mancino Valeria , Revel Jean-Paul , Simon Melvin I.
Published: July 2002

Heterotrimeric GTP-binding proteins (G proteins) participate in cellular signaling and regulate a variety of physiological processes. Disruption of the gene encoding the G protein subunit α
13
(Gα
13
) in mice impaired the ability of endothelial cells to develop into an organized vascular system, resulting in intrauterine death. In addition, Gα
13
(−/−) embryonic fibroblasts showed greatly impaired migratory responses to thrombin. These results demonstrate that Gα
13
participates in the regulation of cell movement in response to specific ligands, as well as in developmental angiogenesis.
Optical Computation with Negative Light Intensity with a Plastic Bacteriorhodopsin Film
Authors: Lewis Aaron , Albeck Yehuda , Lange Zvi , Benchowski Julia , Weizman Gavriel
Published: July 2002

The inability to use light intensity to represent negative values limits the potential of optical computing. The protein bacteriorhodopsin, an optically switchable bistable material, was used to represent an image as a local concentration of one of its two states. Light of one wavelength increased this concentration and represented positive intensity, whereas light of a different wavelength decreased the concentration and represented negative intensity. Optical subtraction was demonstrated by performing the mathematical operation of a difference of Gaussians. The electro-optical characteristics of bacteriorhodopsin films portend a variety of practical applications for this system.
Direct Radiative Forcing by Smoke from Biomass Burning
Authors: Hobbs Peter V. , Reid Jeffrey S. , Kotchenruther Robert A. , Ferek Ronald J. , Weiss Ray
Published: July 2002

Airborne measurements in smoke from biomass burning in Brazil have yielded optical parameters that permit an improved assessment of the effects of smoke on Earth's radiation balance. The global-mean direct radiative forcing due to smoke from biomass burning worldwide is estimated to be no more than about −0.3 watt per square meter (cooling), compared with +2.45 watts per square meter (warming) due to anthropogenic greenhouse gases. On regional scales, direct radiative forcing due to smoke can be large and might indirectly affect global climate.
Constitutive Transcriptional Activation by a β-Catenin-Tcf Complex in APC
−/−
Colon Carcinoma
Authors: Korinek Vladimir , Barker Nick , Morin Patrice J. , van Wichen Dick , de Weger Roel , Kinzler Kenneth W. , Vogelstein Bert , Clevers Hans
Published: July 2002

The adenomatous polyposis coli (APC) tumor suppressor protein binds to β-catenin, a protein recently shown to interact with Tcf and Lef transcription factors. The gene encoding hTcf-4, a Tcf family member that is expressed in colonic epithelium, was cloned and characterized. hTcf-4 transactivates transcription only when associated with β-catenin. Nuclei of APC
−/−
colon carcinoma cells were found to contain a stable β-catenin-hTcf-4 complex that was constitutively active, as measured by transcription of a
Tcf
reporter gene. Reintroduction of APC removed β-catenin from hTcf-4 and abrogated the transcriptional transactivation. Constitutive transcription of
Tcf
target genes, caused by loss of APC function, may be a crucial event in the early transformation of colonic epithelium.
UPDATE: PH Domains--A Universal Membrane Adapter
Authors: Hemmings Brian A.
Published: July 2002

The enzyme PI 3-kinase seems to mediate extraordinarily diverse cellular responses to growth factors. In his Update Perspective, Hemmings offers an explanation by outlining the evidence for a common target of the phospholipid signaling molecules generated by PI 3-kinase—the pleckstrin homology (PH) domains located on at least 100 cellular proteins, which could mediate the diverse responses of cells. On p.
1927
of this issue, Klarlund
et al
. report the isolation of one of these PH domain-containing proteins, GRP1.
Diffusing-Wave Spectroscopy of Dynamics in a Three-Dimensional Granular Flow
Authors: Menon Narayanan , Durian Douglas J.
Published: July 2002

Diffusing-wave spectroscopy was used to measure the microscopic dynamics of grains in the interior of a three-dimensional flow of sand. The correlation functions show that minutely separated grains fly from collision to collision with large random velocities. On a time scale 10
3
to 10
4
times longer than the average time between collisions, the grains displayed slow, collective rearrangements, which, at the long-time limit, produced diffusive dynamics.
Bni1p, a Yeast Formin Linking Cdc42p and the Actin Cytoskeleton During Polarized Morphogenesis
Authors: Evangelista Marie , Blundell Kelly , Longtine Mark S. , Chow Clinton J. , Adames Neil , Pringle John R. , Peter Matthias , Boone Charles
Published: July 2002

The
Saccharomyces cerevisiae BNI1
gene product (Bni1p) is a member of the formin family of proteins, which participate in cell polarization, cytokinesis, and vertebrate limb formation. During mating pheromone response, bni1 mutants showed defects both in polarized morphogenesis and in reorganization of the underlying actin cytoskeleton. In two-hybrid experiments, Bni1p formed complexes with the activated form of the Rho-related guanosine triphosphatase Cdc42p, with actin, and with two actin-associated proteins, profilin and Bud6p (Aip3p). Both Bni1p and Bud6p (like Cdc42p and actin) localized to the tips of mating projections. Bni1p may function as a Cdc42p target that links the pheromone response pathway to the actin cytoskeleton.
Energy Conditions in the Epoch of Galaxy Formation
Authors: Visser Matt
Published: July 2002

The energy conditions of Einsteinian gravity (classical general relativity) do not require one to fix a specific equation of state. In a Friedmann-Robertson-Walker universe where the equation of state for the cosmological fluid is uncertain, the energy conditions provide simple, model-independent, and robust bounds on the behavior of the density and look-back time as a function of red shift. Current observations suggest that the “strong energy condition” was violated sometime between the epoch of galaxy formation and the present. This implies that no possible combination of “normal” matter is capable of fitting the observational data.
Cloud Microphysics and Climate
Authors: Baker M. B.
Published: July 2002

Recent studies have shown that global radiative and hydrological fluxes are strongly linked to microphysical processes in clouds. The sensitivity of predictions of climate variations to assumptions about the microphysical processes has led to new approaches to atmospheric measurements and to heightened interest and progress in understanding the physical chemistry, radiative properties, and kinetics of small solid and liquid aqueous particles.
The Worm Returns
Authors: Hermann Robert K.
Published: July 2002

C. elegans
II.

DONALD L. RIDDLE, THOMAS BLUMENTHAL, BARBARA J. MEYER, and JAMES R. PRIESS, Eds. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1997. xx, 1222 pp., illus. $175. ISBN 0-87969-488-2. Cold Spring Harbor Monograph 33.
Observation of Magnetic Domain Behavior in Colossal Magnetoresistive Materials With a Magnetic Force Microscope
Authors: Lu Qingyou , Chen Chun-Che , de Lozanne Alex
Published: July 2002

Magnetic domain behavior was imaged in calcium-doped lanthanum manganese trioxide films. Magnetic domains behave differently at temperatures that are well below and near the Curie temperature
T
c
. At low temperatures the domains are very stable. As temperature rises toward
T
c
, domain-domain interactions become weaker and domains become highly mobile and subject to merging and splitting, yet the domains are still traceable. The contrast (which is a measure of magnetization) and size of domains continuously reduce to zero. The temperature at which the domains disappear agrees with the
T
c
obtained by a macroscopic magnetization measurement. Sample defects such as scratches tend to attract magnetic domains.
Early Humans and Rapidly Changing Holocene Sea Levels in the Queen Charlotte Islands-Hecate Strait, British Columbia, Canada
Authors: Josenhans Heiner , Fedje Daryl , Pienitz Reinhard , Southon John
Published: July 2002

Marine cores from the continental shelf edge of British Columbia (Canada) demonstrate that sea level at the shelf edge was 153 meters below present 14,000 calendar years ago and more than 30 meters lower than the maximum eustatic low of −120 meters. Dated artifacts, including stone tools, indicate that humans occupied this region by at least 10,200 calendar years before present (B.P.). Local sea level rose rapidly (5 centimeters per year) during the period of early human occupation as a result of eustatic sea-level rise and glacio-isostatic forebulge movement. This shelf edge site was first elevated and then subsided. The exposed shelf edge was available for human occupation and may have served as a migration route during times of lowered sea levels between 13,500 and 9500
14
C years B.P.
Prion Diseases and the BSE Crisis
Authors: Prusiner Stanley B.
Published: July 2002

Bovine spongiform encephalopathy (BSE) and human Creutzfeldt-Jakob disease (CJD) are among the most notable central nervous system degenerative disorders caused by prions. CJD may present as a sporadic, genetic, or infectious illness. Prions are transmissible particles that are devoid of nucleic acid and seem to be composed exclusively of a modified protein (PrP
Sc
). The normal, cellular prion protein (PrP
C
) is converted into PrP
Sc
through a posttranslational process during which it acquires a high β-sheet content. It is thought that BSE is a result of cannibalism in which faulty industrial practices produced prion-contaminated feed for cattle. There is now considerable concern that bovine prions may have been passed to humans, resulting in a new form of CJD.
Inhibition of HIV-1 Infection by the β-Chemokine MDC
Authors: Pal Ranajit , Garzino-Demo Alfredo , Markham Phillip D. , Burns Jennifer , Brown Michelle , Gallo Robert C. , DeVico Anthony L.
Published: July 2002

CD8
+
T lymphocytes from individuals infected with human immunodeficiency virus–type 1 (HIV-1) secrete a soluble activity that suppresses infection by HIV-1. A protein associated with this activity was purified from the culture supernatant of an immortalized CD8
+
T cell clone and identified as the β-chemokine macrophage-derived chemokine (MDC). MDC suppressed infection of CD8
+
cell–depleted peripheral blood mononuclear cells by primary non–syncytium-inducing and syncytium-inducing isolates of HIV-1 and the T cell line–adapted isolate HIV-1
IIIB
. MDC was expressed in activated, but not resting, peripheral blood mononuclear cells and binds a receptor on activated primary T cells. These observations indicate that β-chemokines are responsible for a major proportion of HIV-1–specific suppressor activity produced by primary T cells.
Adiabatic Electron Transfer: Comparison of Modified Theory with Experiment
Authors: Nelsen Stephen F. , Ismagilov Rustem F. , Trieber Dwight A.
Published: July 2002

The radical cations of properly designed bishydrazines allow comparison of observed and calculated electron transfer rate constants. These compounds have rate constants small enough to be measured by dynamic electron spin resonance spectroscopy and show charge transfer bands corresponding to vertical excitation from the energy well for the charge occurring upon one hydrazine unit to that for the electron-transferred species. Analysis of the data for all six compounds studied indicates that the shape of the adiabatic surface on which electron transfer occurs can be obtained from the charge transfer band accurately enough to successfully predict the electron transfer rate constant and that explicit tunneling corrections are not required for these compounds.
Mechanism for the Green Glow of the Upper Ionosphere
Authors: Guberman Steven L.
Published: July 2002

The generation of the green line of atomic oxygen by dissociative recombination of O
2
+
occurs by the capture of an electron into a repulsive state of O
2
followed by dissociation along another state of a different electronic symmetry. The two states are coupled together by mixed symmetry Rydberg states. Quantum chemical calculations give a rate coefficient at room temperature of (0.39
−0.19
+0.31
) × 10
−8
cubic centimeters per second. The quantum yield of excited oxygen is within the range deduced from ground, rocket, and satellite observations. The rate coefficients and yields are needed in models of the optical emission, chemistry, and energy balance of planetary ionospheres.
Independent and Additive Effects of Central POMC and Leptin Pathways on Murine Obesity
Authors: Boston Bruce A. , Blaydon Kathryn M. , Varnerin Jeffrey , Cone Roger D.
Published: July 2002

The
lethal yellow
(

A
Y
/a

) mouse has a defect in proopiomelanocortin (POMC) signaling in the brain that leads to obesity, and is resistant to the anorexigenic effects of the hormone leptin. It has been proposed that the weight-reducing effects of leptin are thus transmitted primarily by way of POMC neurons. However, the central effects of defective POMC signaling, and the absence of leptin, on weight gain in double-mutant
lethal yellow
(

A
Y
/a

) leptin-deficient (

lep
ob
/lep

ob

) mice were shown to be independent and additive. Furthermore, deletion of the leptin gene restored leptin sensitivity to

A
Y
/a

mice. This result implies that in the

A
Y
/a

mouse, obesity is independent of leptin action, and resistance to leptin results from desensitization of leptin signaling.
Radar Detection of the Nucleus and Coma of Comet Hyakutake (C/1996 B2)
Authors: Harmon J. K. , Ostro S. J. , Benner L. A. M. , Rosema K. D. , Jurgens R. F. , Winkler R. , Yeomans D. K. , Choate D. , Cormier R. , Giorgini J. D. , Mitchell D. L. , Chodas P. W. , Rose R. , Kelley D. , Slade M. A. , Thomas M. L.
Published: July 2002

Radar observations of comet Hyakutake (C/1996 B2) made at the Goldstone Deep Space Communications Complex in California have detected echoes from the nucleus and from large grains in the inner coma. The nucleus of this bright comet was estimated to be only 2 to 3 kilometers in diameter. Models of the coma echo indicate backscatter from porous, centimeter-size grains ejected anisotropically at velocities of tens of meters per second. The radar observations suggest that a comet's activity may be a poor indicator of its size and provide evidence that large grains constitute an important component of the mass loss from a typical active comet.
Coupling of South American and African Plate Motion and Plate Deformation
Authors: Silver Paul G. , M. Russo Raymond , Lithgow-Bertelloni Carolina
Published: July 2002

Although the African Plate's northeastward absolute motion slowed abruptly 30 million years ago, the South Atlantic's spreading velocity has remained roughly constant over the past 80 million years, thus requiring a simultaneous westward acceleration of the South American Plate. This plate velocity correlation occurs because the two plates are coupled to general mantle circulation. The deceleration of the African Plate, due to its collision with the Eurasian Plate, diverts mantle flow westward, increasing the net basal driving torque and westward velocity of the South American Plate. One result of South America's higher plate velocity is the increased cordilleran activity along its western edge, beginning at about 30 million years ago.
Evidence for New Sources of NO

X

in the Lower Atmosphere
Authors: Zipf Edward C. , Prasad Sheo S.
Published: July 2002

Laboratory studies show that the reaction of short-lived O
2
(B
3
Σ
u
) molecules (lifetime ∼10 picoseconds) with N
2
and the photodissociation of the N
2
:O
2
dimer produce NO

x

in the stratosphere at a rate comparable to the oxidation of N
2
O by O(
1
D
). This finding implies the existence of unidentified NO

X

sinks in the stratosphere. The NO
2
observed in this experiment is isotopically heavy with a large
15
N/
14
N enhancement. However, photodissociation of this NO
2
unexpectedly produced NO molecules with a low
15
N/
14
N ratio. The diurnal odd-nitrogen cycle in the stratosphere will be marked by a complex isotope signature that will be imprinted on the halogen and HO

X

catalytic cycles.
Kinesin and Dynein Superfamily Proteins and the Mechanism of Organelle Transport
Authors: Hirokawa Nobutaka
Published: July 2002

Cells transport and sort proteins and lipids, after their synthesis, to various destinations at appropriate velocities in membranous organelles and protein complexes. Intracellular transport is thus fundamental to cellular morphogenesis and functioning. Microtubules serve as a rail on which motor proteins, such as kinesin and dynein superfamily proteins, convey their cargoes. This review focuses on the molecular mechanism of organelle transport in cells and describes kinesin and dynein superfamily proteins.
Precambrian Sponges with Cellular Structures
Authors: Li Chia-Wei , Chen Jun-Yuan , Hua Tzu-En
Published: July 2002

Sponge remains have been identified in the Early Vendian Doushantuo phosphate deposit in central Guizhou (South China), which has an age of ∼580 million years ago. Their skeletons consist of siliceous, monaxonal spicules. All are referred to as the Porifera, class Demospongiae. Preserved soft tissues include the epidermis, porocytes, amoebocytes, sclerocytes, and spongocoel. Among thousands of metazoan embryos is a parenchymella-type of sponge larvae having a shoe-shaped morphology and dense peripheral flagella. The presence of possible amphiblastula larva suggests that the calcareous sponges may have an extended history in the Late Precambrian. The fauna indicates that animals lived 40 to 50 million years before the Cambrian Explosion.
Atmospheric Radiocarbon Calibration to 45,000 yr B.P.: Late Glacial Fluctuations and Cosmogenic Isotope Production
Authors: Kitagawa H. , van der Plicht J.
Published: July 2002

More than 250 carbon-14 accelerator mass spectrometry dates of terrestrial macrofossils from annually laminated sediments from Lake Suigetsu (Japan) provide a first atmospheric calibration for almost the total range of the radiocarbon method (45,000 years before the present). The results confirm the (recently revised) floating German pine chronology and are consistent with data from European and marine varved sediments, and combined uranium-thorium and carbon-14 dating of corals up to the Last Glacial Maximum. The data during the Glacial show large fluctuations in the atmospheric carbon-14 content, related to changes in global environment and in cosmogenic isotope production.
Modulation of Diversity by Grazing and Mowing in Native Tallgrass Prairie
Authors: Collins Scott L. , Knapp Alan K. , Briggs John M. , Blair John M. , Steinauer Ernest M.
Published: July 2002

Species diversity has declined in ecosystems worldwide as a result of habitat fragmentation, eutrophication, and land-use change. If such decline is to be halted ecological mechanisms that restore or maintain biodiversity are needed. Two long-term field experiments were performed in native grassland to assess the effects of fire, nitrogen addition, and grazing or mowing on plant species diversity. In one experiment, richness declined on burned and fertilized treatments, whereas mowing maintained diversity under these conditions. In the second experiment, loss of species diversity due to frequent burning was reversed by bison, a keystone herbivore in North American grasslands. Thus, mowing or the reestablishment of grazing in anthropogenically stressed grasslands enhanced biodiversity.
Correction of Deafness in
shaker-2
Mice by an Unconventional Myosin in a BAC Transgene
Authors: Probst Frank J. , Fridell Robert A. , Raphael Yehoash , Saunders Thomas L. , Wang Aihui , Liang Yong , Morell Robert J. , Touchman Jeffrey W. , Lyons Robert H. , Noben-Trauth Konrad , Friedman Thomas B. , Camper Sally A.
Published: July 2002

The
shaker-2
mouse mutation, the homolog of human
DFNB3
, causes deafness and circling behavior. A bacterial artificial chromosome (BAC) transgene from the
shaker-2
critical region corrected the vestibular defects, deafness, and inner ear morphology of
shaker-2
mice. An unconventional myosin gene,
Myo15
, was discovered by DNA sequencing of this BAC.
Shaker-2
mice were found to have an amino acid substitution at a highly conserved position within the motor domain of this myosin. Auditory hair cells of
shaker-2
mice have very short stereocilia and a long actin-containing protrusion extending from their basal end. This histopathology suggests that
Myo15
is necessary for actin organization in the hair cells of the cochlea.
Association of Unconventional Myosin
MYO15
Mutations with Human Nonsyndromic Deafness
DFNB3
Authors: Wang Aihui , Liang Yong , Fridell Robert A. , Probst Frank J. , Wilcox Edward R. , Touchman Jeffrey W. , Morton Cynthia C. , Morell Robert J. , Noben-Trauth Konrad , Camper Sally A. , Friedman Thomas B.
Published: July 2002

DFNB3
, a locus for nonsyndromic sensorineural recessive deafness, maps to a 3-centimorgan interval on human chromosome 17p11.2, a region that shows conserved synteny with mouse
shaker-2
. A human unconventional myosin gene,
MYO15
, was identified by combining functional and positional cloning approaches in searching for
shaker-2
and
DFNB3
.
MYO15
has at least 50 exons spanning 36 kilobases. Sequence analyses of these exons in affected individuals from three unrelated
DFNB3
families revealed two missense mutations and one nonsense mutation that cosegregated with congenital recessive deafness.