bluuebunny/crossref_metadata_2025 huggingface dataset:
HTLV-III/LAV-Neutralizing Antibodies to an
E. coli
-Produced Fragment of the Virus Envelope
Authors: Putney Scott D. , Matthews Thomas J. , Robey W. Gerard , Lynn Debra L. , Robert-Guroff Marjorie , Mueller W. Thomas , Langlois Alphonse J. , Ghrayeb John , Petteway Stephen R. , Weinhold Kent J. , Fischinger Peter J. , Wong-Staal Flossie , Gallo Robert C. , Bolognesi Dani P.
Published: October 2006

Immunization with either an
Escherichia coli
recombinant segment of the human T-cell lymphotropic virus (HTLV-III/LAV) envelope protein (gp120) or with deglycosylated gp120 envelope protein produced antibodies that neutralize HTLV-III/LAV infection in vitro. Virus neutralization titers of these antisera were equivalent to those obtained with purified native gp120 as immunogen. This localizes at least one class of neutralizing epitopes to the carboxyl-terminal half of the molecule. In addition, native gp120 prevented HTLV-III/LAV—mediated cell fusion, whereas the recombinant gp120 fragment did not. This shows that although glycosylation is not required for induction of neutralizing antibodies, it may be important for interaction with CD4, the virus receptor. A segment of the HTLV-III/LAV envelope produced in
E. coli
may be an important ingredient of a vaccine for acquired immune deficiency syndrome.
Identification of an α Subunit of Dihydropyridine-Sensitive Brain Calcium Channels
Authors: Takahashi Masami , Catterall William A.
Published: October 2006

Voltage-sensitive calcium channels in different tissues have diverse functional properties. Polyclonal antibodies (PAC-2) against the α subunits of purified rabbit skeletal muscle calcium channels immunoprecipitated calcium channels labeled with the dihydropyridine PN200-110 from both skeletal muscle and brain. The immunoreactivity of PAC-2 with the skeletal muscle channel was greater than that with the brain calcium channel and was absorbed only partially by prior treatment with the brain channel. PAC-2 specifically recognized a large peptide in synaptic plasma membranes of rabbit brain with an apparent molecular size of 169,000 daltons. This protein resembles an α subunit of the skeletal muscle calcium channel in apparent molecular weight, antigenic properties, and electrophoretic behavior after reduction of disulfide bonds. Thus, the dihydropyridine-sensitive calcium channel of rabbit brain has an α subunit that is homologous, but not identical, to those of the skeletal muscle calcium channel. The different functional properties of these two calcium channels may result from minor variations in structurally similar components.
Single-Channel and Genetic Analyses Reveal Two Distinct A-Type Potassium Channels in
Drosophila
Authors: Solc Charles K. , Zagotta William N. , Aldrich Richard W.
Published: October 2006

Whole-cell and single-channel voltage-clamp techniques were used to identify and characterize the channels underlying the fast transient potassium current (A current) in cultured myotubes and neurons of
Drosophila
. The myotube (A
1
) and neuronal (A
2
) channels are distinct, differing in conductance, voltage dependence, and gating kinetics. The myotube currents have a faster and more voltage-dependent macroscopic inactivation rate, a larger steady-state component, and a less negative steady-state inactivation curve than the neuronal currents. The myotube channels have a conductance of 12 to 16 picosiemens, whereas the neuronal channels have a conductance of 5 to 8 picosiemens. In addition, the myotube channel is affected by
Shaker
mutations, whereas the neuronal channel is not. Together, these data suggest that the two channels are separate molecular structures, the expression of which is controlled, at least in part, by different genes.
Neptune Cloud Structure at Visible Wavelengths
Authors: Hammel H. B.
Published: October 2006

Digital images of Neptune showing cloud structure at visible wavelengths were obtained in July 1988. A discrete bright feature was detected both at 6190 Å (a weak methane absorption band in the visible) and at 8900 Å (a stronger methane band in the near infrared). The images also revealed that Neptune's southern pole was bright relative to planetary mid-latitudes at 6190 Å but not 8900 Å. The implications of these findings for atmospheric rotation and structure are discussed. The detection of discrete features at visible wavelengths is of special importance to the upcoming Voyager encounter with Neptune: the wide-angle camera has a 6190 Å filter similar to that used for these observations.
Smectic Liquid Crystal Monolayers on Graphite Observed by Scanning Tunneling Microscopy
Authors: Smith D. P. E. , Hörber H. , Gerber Ch. , Binnig G.
Published: October 2006

By means of scanning tunneling microscopy, it is observed that molecules of the form
n
-alkylcyanobiphenyl, where
n
= 8 to 12, form two-dimensional crystalline domains when adsorbed onto graphite. The layer spacings measured by tunneling microscopy are 20% larger than those measured previously on bulk material by x-ray diffraction. The structure of the adsorbed molecules is quite different from that of the bulk.
X-ray Diffraction to 302 Gigapascals: High-Pressure Crystal Structure of Cesium Iodide
Authors: Mao H. K. , Hemley R. J. , Chen L. C. , Shu J. F. , Finger L. W. , Wu Y.
Published: October 2006

X-ray diffraction measurements have been carried out on cesium iodide (CsI) to 302 gigapascals with a platinum pressure standard. The results indicate that above 200 gigapascals CsI at 300 K has a hexagonal close-packed crystal structure with the ideal
c
/
a
ratio of 1.63 ± 0.01. The crystal structure and pressure-volume relations converge at high pressure with those of solid xenon, which is isoelectronic with CsI. The results indicate a significant loss of ionic bonding in the hexagonal close-packed metallic phase of CsI at ultrahigh pressure.
Chemical Cartography: Finding the Keys to the Kinetic Labyrinth
Authors: Flynn George W.
Published: October 2006

Very high resolution lasers allow spectroscopic pictures to be taken following a collision between two molecular reactants. The features of these "pictures" are the electronic, vibrational, rotational, and translational motions of the atomic particles, which relate the quantum states of the reactants to the quantum states of the products. Such state-to-state kinetic information can be used to test the shape and nature of the interaction potential that controls the collision process. The potential itself is akin to a map of the terrain through mountains and valleys where elevation is a measure of energy instead of height. Accurate mapping of this potential surface leads to an understanding of the forces which control rates and mechanisms of chemical reactions. The application of four different advanced laser techniques to the study of collisions between "hot" hydrogen (H) atoms and carbon dioxide (CO
2
) molecules has provided a wealth of information about both reactive and nonreactive collisions for this system. The availability of data for rotationally, vibrationally, and translationally inelastic excitation of CO
2
by H atoms, when compared with data for reactive events producing OH + CO, provides insights into the dynamics of collisions between H and CO
2
, and illustrates the future promise of these powerful techniques for elucidating features of potential energy surfaces.
Effect of Antisense c-
raf
-1 on Tumorigenicity and Radiation Sensitivity of a Human Squamous Carcinoma
Authors: Kasid U. , Pfeifer A. , Brennan T. , Beckett M. , Weichselbaum R. R. , Dritschilo A. , Mark G. E.
Published: October 2006

Antisense RNA-mediated inhibition of gene expression was used to investigate the biological function of the c-
raf
-1 gene in a radiation-resistant human squamous carcinoma cell line, SQ-20B. S1 nuclease protection assays revealed that transfection of full-length
raf
complementary DNA in the antisense orientation (AS) leads to a specific reduction (greater than tenfold) of steady-state levels of the endogenous c-
raf
-1 sense (S) transcript in SQ-20B cells. In nude mice, the malignant potential of SQ-20B cells transfected with
raf
(S) was significantly increased relative to that of SQ-20B cells transfected with
raf
(AS). SQ-20B cells containing transfected
raf
(S) maintained a radiation-resistant phenotype as compared to those cells harboring the AS version, which appeared to have enhanced radiation sensitivity. These data indicate that the reduced expression of endogenous c-
raf
-1 is sufficient to modulate the tumorigenicity and the radiation-resistant phenotype of SQ-20B cells, thus implicating c-
raf
-1 in a pathway important to the genesis of this type of cancer.
The Rotation Period of Saturn's Polar Hexagon
Authors: Godfrey D. A.
Published: October 2006

The rotation rates of the interiors of the outer planets are normally derived from their periodic radio emissions. However, recent observations of both Jupiter and Saturn have revealed surface features with periods close to those derived for the interiors. In the study reported here, this process is carried one stage further, with the derivation of a rotation rate for the spot associated with Saturn's polar hexagon, which is simultaneously within and more accurate than the Saturnian radio period.
Critical Behavior in the Hydrogen Insulator-Metal Transition
Authors: Hemley R. J. , Mao H. K.
Published: October 2006

The vibrational Raman spectrum of solid hydrogen has been measured from 77 to 295 K in the vicinity of the recently observed insulator-metal transition and low-temperature phase transition at 150 gigapascals (1.5 megabars). The measurements provide evidence for a critical point in the pressure-temperature phase boundary of the low-temperature transition. The result suggests that below the critical temperature the insulator-metal transition changes from continuous to discontinuous, consistent with the general criteria originally proposed by Mott for metallization by band-gap closure. The effect of temperature on hydrogen metallization closely resembles that of the lower pressure insulator-metal transitions in doped V
2
O
3
alloys.
Cluster Assembly of Interfaces: Nanoscale Engineering
Authors: Weaver J. H. , Waddill G. D.
Published: October 2006

Overlayer structures can be formed on surfaces by the deposition of clusters containing hundreds or thousands of atoms. Cluster assembly alters the reaction pathway at the surface so that novel structures with unique chemical and physical properties can be stabilized. This article discusses the process of cluster assembly. Cluster-assembled interfaces are compared to those obtained by conventional techniques, and examples are given for metal-semiconductor and semiconductor-high temperature superconductor systems.
Tests of Time-Reversal Invariance in Atoms, Molecules, and the Neutron
Authors: Hunter L. R.
Published: October 2006

Sensitive experiments have been developed that search for electric dipole moments of atoms, molecules, and the neutron. These experiments play an important role in deciding which of the myriad theoretical models correctly describes violations of the principle of time-reversal invariance.
Astrophysical Jets
Authors: De Young David S.
Published: October 2006

Astrophysical jets are linear structures associated with stars and galaxies which span about seven orders of magnitude in size; the largest jets emanating from galaxies are about 100 times the size of our galaxy and are the largest single objects in the universe. Jets associated with stars are composed of ionized gas moving away from the star with velocities of a few hundred kilometers per second. Extragalactic jets are composed of relativistic particles, magnetic field, and probably additional amounts of cooler ionized plasma either originally ejected in the jet or entrained by it out of the surrounding gaseous medium. The initial outflow velocity for extragalactic jets may be relativistic, and average outflow speeds of several thousand kilometers per second are likely. The energy flux carried by extragalactic jets may be in excess of 10
46
ergs per second, depending upon the nature of the jet. A definition of jet properties, deduced from their interaction with the ambient medium, can place essential constraints on models for the central power source in the parent galaxy or quasi-stellar object where they originate.
Partial Melting of the Aliende (CV3) Meteorite: Implications for Origins of Basaltic Meteorites
Authors: Jurewicz A. J. G. , Mittlefehldt D. W. , Jones J. H.
Published: October 2006

Eucrites and angrites are distinct types of basaltic meteorites whose origins are poorly known. Experiments in which samples of the Allende (CV3) carbonaceous chondrite were partially melted indicate that partial melts can resemble either eucrites or angrites, depending only on the oxygen fugacity (ƒ

O
2

). Melts are eucritic if the ƒ

O
2

is below that of the iron-wüstite buffer or angritic if above the ƒ

O
2

of that buffer. With changing pressure, the graphite-oxygen redox reaction can produce oxygen fugacities that are above or below those of the iron-wüstite buffer. Therefore, a single, homogeneous, carbonaceous planetoid >110 kilometers in radius could produce melts of drastically different composition, depending on the depth of melting.
The Potential for Ozone Depletion in the Arctic Polar Stratosphere
Authors: Brune W. H. , Anderson J. G. , Toohey D. W. , Fahey D. W. , Kawa S. R. , Jones R. L. , McKenna D. S. , Poole L. R.
Published: October 2006

The nature of the Arctic polar stratosphere is observed to be similar in many respects to that of the Antarctic polar stratosphere, where an ozone hole has been identified. Most of the available chlorine (HCl and ClONO
2
) was converted by reactions on polar stratospheric clouds to reactive ClO and Cl
2
O
2
throughout the Arctic polar vortex before midwinter. Reactive nitrogen was converted to HNO
3
, and some, with spatial inhomogeneity, fell out of the stratosphere. These chemical changes ensured characteristic ozone losses of 10 to 15% at altitudes inside the polar vortex where polar stratospheric clouds had occurred. These local losses can translate into 5 to 8% losses in the vertical column abundance of ozone. As the amount of stratospheric chlorine inevitably increases by 50% over the next two decades, ozone losses recognizable as an ozone hole may well appear.
Crystallinity of the Double Layer of Cadmium Arachidate Films at the Water Surface
Authors: Leveiller F. , Jacquemain D. , Lahav M. , Leiserowitz L. , Deutsch M. , Kjaer K. , Als-Nielsen J.
Published: October 2006

A crystalline counterionic layer at the interface between an electrolyte solution and a charged layer of insoluble amphiphilic molecules was observed with grazing incidence synchrotron x-ray diffraction. Uncompressed arachidic films spread over 10
-3
molar cadmium chloride solution (pH 8.8) spontaneously form crystalline clusters with coherence lengths of ∼1000 angstroms at 9°C. Ten distinct diffraction peaks were observed, seven of which were attributed to scattering only from a crystalline Cd
2+
layer and the other three to scattering primarily from the arachidate layer. The reflections from the Cd
2+
layer were indexed according to a 2 × 3 supercell of the arachidate lattice with three Cd
2+
ions per cadmium unit cell.
Dislocations and Flux Pinning inYBa
2
Cu
3
O
7-δ
Authors: Jin S. , Kammlott G. W. , Nakahara S. , Tiefel T. H. , Graebner J. E.
Published: October 2006

Bulk YBa
2
Cu
3
O
7-δ
superconductors, under certain processing conditions such as melt texturing, exhibit a very high dislocation density of 10
9
to 10
10
per square centimeter. In addition, the density of low-angle grain boundaries in such samples can be significantly increased (to less than ∼700-nanometer spacing) through a dispersion of submicrometer-sized Y
2
BaCuO
5
inclusions. These defect densities are comparable to those in high critical current thin films as revealed through scanning tunneling microscopy, and yet the critical current densities in the bulk materials (at 77 kelvin and a field of 1 tesla for example) remain at a 10
4
amperes per square centimeter level, about two orders of magnitude lower than in thin films. The results imply that these defect density levels are not significant enough to explain the difference in flux pinning strength between the thin film and bulk materials. The observation of spiral-like growth of the superconductor phase in bulk Y-Ba-Cu-O is also reported.
Hydrogen-Helium Mixtures at Megabar Pressures: Implications for Jupiter and Saturn
Authors: Klepeis J. E. , Schafer K. J. , Barbee T. W. , Ross M.
Published: October 2006

Models of Jupiter and Saturn postulate a central rock core surrounded by a fluid mixture of hydrogen and helium. These models suggest that the mixture is undergoing phase separation in Saturn but not Jupiter. State-of-the-art total energy calculations of the enthalpy of mixing for ordered alloys of hydrogen and helium confirm that at least partial phase separation has occurred in Saturn and predict that this process has also begun in Jupiter.
Physics of the Granular State
Authors: Jaeger H. M. , Nagel Sidney R.
Published: October 2006

Granular materials display a variety of behaviors that are in many ways different from those of other substances. They cannot be easily classified as either solids or liquids. This has prompted the generation of analogies between the physics found in a simple sandpile and that found in complicated microscopic systems, such as flux motion in superconductors or spin glasses. Recently, the unusual behavior of granular systems has led to a number of new theories and to a new era of experimentation on granular systems.
The Inner Core Translational Triplet and the Density Near Earth's Center
Authors: Smylie D. E.
Published: October 2006

Four long records from superconducting gravimeters yield evidence of the triplet of translational oscillations of the solid inner core about its central position. Calculations of core oscillation modes allow identification of the three translational resonances at periods of 3.5820 ± 0.0008, 3.7677 ± 0.0006, and 4.015 ± 0.001 hours by their rotational splitting. Each resonance is defined by approximately 20 successive spectral estimates. A new Earth model brings the computed periods into agreement with observation. It has a central density of 12.960 grams per cubic centimeter, inner core radius of 1221.1 kilometers, and a density jump at the inner core boundary of 0.407 grams per cubic centimeter.
T Cell Receptor Gene Trans-Rearrangements: Chimeric γ-δ Genes in Normal Lymphoid Tissues
Authors: Tycko Benjamin , Palmer James D. , Sklar Jeffrey
Published: October 2006

Joining of V-, D-, and J-region gene segments during DNA rearrangements within all antigen receptor genes involves recognition of the same highly conserved heptamernonamer sequences flanking each segment. In order to investigate the possibility that recognition of these conserved sequences may sometimes permit intergenic joining of segments among different antigen receptor genes, DNA of normal human lymphoid tissues was examined by polymerase chain reaction amplification for the presence of chimeric γ-δ T cell receptor gene rearrangements. These studies detected V
γ
-(D
δ
)-J
δ
and V
δ
-(D
δ
)-J
γ
rearrangements in thymus, peripheral blood, and tonsil. Analysis of thymus RNA indicated that many of these rearrangements are expressed as V
γ
-(D
δ
)-J
δ
-C
δ
and V
δ
-(D
δ
)-J
γ
-C
γ
transcripts. Most transcripts (19 of 20 complementary DNA clones studied) are appropriately spliced and show correct open translational reading frames across the V-(D)-J junctions. Thus, chimeric antigen receptor genes are generated in a subset of normal lymphoid cells, probably as a result of chromosomal translocations, and such genes may possibly contribute to increased diversity within the antigen receptor repertoire.
Physics and Device Applications of Optical Microcavities
Authors: Yokoyama H.
Published: October 2006

Optical microcavities are resonators that have at least one dimension on the order of a single optical wavelength. These structures enable one to control the optical emission properties of materials placed inside them. They can, for example, modify the spatial distribution of radiation power, change the spectral width of the emitted light, and enhance or suppress the spontaneous emission rate. In addition to being attractive for studying the fundamental physics of the interaction between materials and vacuum field fluctuations, optical microcavities hold technological promise for constructing novel kinds of light-emitting devices. One of their most dramatic potential features is thresholdless lasing. In this way and others, controlled spontaneous emission is expected to play a key role in a new generation of optical devices.
Synthesis and Electronic Transport of Single Crystal K
3
C
60
Authors: Xiang X. -D. , Hou J. G. , Briceño G. , Vareka W. A. , Mostovoy R. , Zettl A. , Crespi Vincent H. , Cohen Marvin L.
Published: October 2006

Sizable single crystals of C
60
have been synthesized and doped with potassium. Above the superconducting transition temperature

T
c

, the electrical resistivity ρ(
T
) displays a classic metal-like temperature dependence. The transition to the superconducting state at T
c
= 19.8 K is extremely sharp, with a transition width Δ
T
< 200 mK. In contrast to transport behavior of doped polycrystalline and granular thin films, no anomalous fluctuations are observed near

T
c

in single crystal specimens.
New Approaches to Nuclear Proliferation Policy
Authors: Nye Joseph S.
Published: October 2006

Nuclear proliferation is not one but a complex of problems. One relates to the collapse of the Soviet Union and its effect on the spread of nuclear weapons and knowledge. Second, Iraq's violation of its Non-Proliferation Treaty obligation has exposed certain weaknesses in the traditional regime of multilateral nonproliferation institutions and treaties. Third, Pakistan's achievement of a nuclear weapons capability in the late 1980s brings the postproliferation question to the forefront in South Asia. There is no single solution to this complex set of problems, but the beginning of wisdom is to build upon the successes of the past, add new policy procedures, and, above all, increase the priority given to the issue. Otherwise, we may be faced with the ironic outcome that the widely welcomed end of the Cold War may increase the prospect of nuclear use.
Heritable Allele-Specific Differences in Amounts of apoB and Low-Density Lipoproteins in Plasma
Authors: Gavish Dov , Brinton Eliot A. , Breslow Jan L.
Published: October 2006

Low-density lipoprotein (LDL) concentrations correlate with risk of coronary heart disease, and genetic variation affecting LDL levels influences atherosclerosis susceptibility. The principal LDL protein is apolipoprotein B (apoB); apoB is not exchangeable between lipoprotein particles and there is only one apoB per LDL particle. Plasma LDL therefore consists of two populations, one containing apoB derived from the maternal and one from the paternal apoB alleles. Products of the apob gene with high or low affinity for the MB-19 monoclonal antibody can be distinguished, and this antibody was used to identify heterozygotes with allele-specific differences in the amount of apoB in their plasma. A family study confirmed that the unequal expression phenotype was inherited in an autosomal dominant manner and was linked to the apob gene locus. Significant apoB genetic variation affecting plasma LDL levels may be more common than previously appreciated.
Manganese Flux from Continental Margin Sediments in a Transect Through the Oxygen Minimum
Authors: Johnson Kenneth S. , Berelson William M. , Coale Kenneth H. , Coley Teresa L. , Elrod Virginia A. , Fairey W. Russell , Iams Helen D. , Kilgore Tammy E. , Nowicki Jocelyn L.
Published: October 2006

The flux of manganese from continental margin sediments to the ocean was measured with a free-vehicle, benthic flux chamber in a transect across the continental shelf and upper slope of the California margin. The highest fluxes were observed on the shallow continental shelf. Manganese flux decreased linearly with bottom water oxygen concentration, and the lowest fluxes occurred in the oxygen minimum zone (at a depth of 600 to 1000 meters). Although the flux of manganese from continental shelf sediments can account for the elevated concentrations observed in shallow, coastal waters, the flux from sediments that intersect the oxygen minimum cannot produce the subsurface concentration maximum of dissolved manganese that is observed in the Pacific Ocean.
No Evidence of a Circumsolar Dust Ring from Infrared Observations of the 1991 Solar Eclipse
Authors: Lamy P. , Kuhn J. R. , Lin H. , Koutchmy S. , Smartt R. N.
Published: October 2006

During the past 25 years there have been many attempts to detect a possible dust ring around the sun, with contradictory results. Before the 1991 eclipse, infrared eclipse experiments used single-element detectors to scan the corona along the ecliptic for excess surface brightness peaks. The availability of relatively large-format infrared array detectors now provides a considerable observational advantage: two-dimensional mapping of the brightness and polarization of the corona with high photometric precision. The 1991 eclipse path included the high-altitude Mauna Kea Observatory, a further advantage to measure the corona out to large angular distances from the sun. Results are reported from an experiment conducted on Mauna Kea with a HgCdTe-array detector sensitive to wavelengths between 1 and 2.5 micrometers, using broad-band J, H, and K filters. Although the sky conditions were not ideal, the H- and K-band surface brightnesses clearly show the inhomogeneous structure in the K-corona and the elliptical flattening of the F-corona, but no evidence of a circumsolar, local dust component out to 15 solar radii.
Jupiter's Magnetosphere: Plasma Description from the Ulysses Flyby
Authors: Bame Samuel J. , Barraclough Bruce L. , Feldman William C. , Gisler Galen R. , Gosling John T. , McComas David J. , Phillips John L. , Thomsen Michelle F. , Goldstein Bruce E. , Neugebauer Marcia
Published: October 2006

Plasma observations at Jupiter show that the outer regions of the Jovian magnetosphere are remarkably similar to those of Earth. Bow-shock precursor electrons and ions were detected in the upstream solar wind, as at Earth. Plasma changes across the bow shock and properties of the magnetosheath electrons were much like those at Earth, indicating that similar processes are operating. A boundary layer populated by a varying mixture of solar wind and magnetospheric plasmas was found inside the magnetopause, again as at Earth. In the middle magnetosphere, large electron density excursions were detected with a 10-hour periodicity as planetary rotation carried the tilted plasma sheet past Ulysses. Deep in the magnetosphere, Ulysses crossed a region, tentatively described as magnetically connected to the Jovian polar cap on one end and to the interplanetary magnetic field on the other. In the inner magnetosphere and Io torus, where corotation plays a dominant role, measurements could not be made because of extreme background rates from penetrating radiation belt particles.
Middle Tertiary Volcanism During Ridge-Trench Interactions in Western California
Authors: Cole Ronald B. , Basu Asish R.
Published: October 2006

Bimodal volcanism in the Santa Maria Province of west-central California occurred when segments of the East Pacific Rise interacted with a subduction zone along the California margin during the Early Miocene (about 17 million years ago). Isotopic compositions of neodymium and strontium as well as trace-element data indicate that these volcanic rocks were derived from a depleted-mantle (mid-ocean ridge basalt) source. After ridge-trench interactions, the depleted-mantle reservoir was juxtaposed beneath the continental margin and was erupted to form basalts. It also assimilated and partially melted local Jurassic-Cretaceous sedimentary and metasedimentary basement rocks to form rhyolites and dacites.
Production of Metallo-Carbohedrenes in the Solid State
Authors: Cartier S. F. , Chen Z. Y. , Walder G. J. , Sleppy C. R. , Castleman A. W.
Published: October 2006

Macroscopic quantities of the metallo-carbohedrenes Ti
8
C
12
and V
8
C
12
have been synthesized with an arc discharge technique. Mass spectroscopy of raw soot samples generated in both an alternating and direct current arc between two metal-graphite powder composite electrodes establishes that the titanium and vanadium analogs of the metallo-carbohedrenes have been produced. An estimated yield of ∼1 percent is obtained, and significantly, the products are stable in air.
Early and Late Alkali Igneous Pulses and a High-3He Plume Origin for the Deccan Flood Basalts
Authors: Basu Asish R. , Renne Paul R. , DasGupta Deb K. , Teichmann Friedrich , Poreda Robert J.
Published: October 2006

Several alkalic igneous complexes of nephelinite-carbonatite affinities occur in extensional zones around a region of high heat flow and positive gravity anomaly within the continental flood basalt (CFB) province of Deccan, India. Biotites from two of the complexes yield40Ar/39Ar dates of 68.53 ± 0.16 and 68.57 ± 0.08 million years. Biotite from a third complex, which intrudes the flood basalts, yields an40Ar/39Ar date of 64.96 ± 0.11 million years. The complexes thus represent early and late magmatism with respect to the main pulse of CFB volcanism 65 million years ago. Rocks from the older complexes show a3He/4He ratio of 14.0 times the air ratio, an initial87Sr/86Sr ratio of 0.70483, and other geochemical characteristics similar to ocean island basalts; the later alkalic pulse shows isotopic evidence of crustal contamination. The data document 3.5 million years of incubation of a primitive, high-3He mantle plume before the rapid eruption of the Deccan CFB.
Influence of Productivity on the Stability of Real and Model Ecosystems
Authors: Moore John C. , de Ruiter Peter C. , Hunt H. William
Published: October 2006

The lengths of food chains within ecosystems have been thought to be limited either by the productivity of the ecosystem or by the resilience of that ecosystem after perturbation. Models based on ecological energetics that follow the form of Lotka-Volterra equations and equations that include material (detritus) recycling show that productivity and resilience are inextricably interrelated. The models were initialized with data from 5- to 10-year studies of actual soil food webs. Estimates indicate that most ecological production worldwide is from ecosystems that are themselves sufficiently productive to recover from minor perturbations.
Chlorine Chemistry on Polar Stratospheric Cloud Particles in the Arctic Winter
Authors: Webster C. R. , May R. D. , Toohey D. W. , Avallone L. M. , Anderson J. G. , Newman P. , Lait L. , Schoeberl M. R. , Elkins J. W. , Chan K. R.
Published: October 2006

Simultaneous in situ measurements of hydrochloric acid (HCl) and chlorine monoxide (ClO) in the Arctic winter vortex showed large HCl losses, of up to 1 part per billion by volume (ppbv), which were correlated with high ClO levels of up to 1.4 ppbv. Air parcel trajectory analysis identified that this conversion of inorganic chlorine occurred at air temperatures of less than 196 ± 4 kelvin. High ClO was always accompanied by loss of HCl mixing ratios equal to 1/2(ClO + 2Cl
2
O
2
). These data indicate that the heterogeneous reaction HCl + ClONO
2
→ Cl
2
+ HNO
3
on particles of polar stratospheric clouds establishes the chlorine partitioning, which, contrary to earlier notions, begins with an excess of ClONO
2
, not HCl.
Real-Time Observation of the Vibration of a Single Adsorbed Molecule
Authors: Watanabe Fumiya , McClelland Gary M. , Heinzelmann Harry
Published: October 2006

The newly developed femtosecond field emission camera was used to observe the time dependence of field emission through a single copper phthalocyanine molecule adsorbed on a tungsten tip. In many of the individual 212-picosecond-long recordings, the field emission was found to oscillate with a frequency between 5 × 10
10
and 20 × 10
10
hertz. The oscillations, which were not observed from a bare tip, are believed to arise from the vibration of a single molecule with respect to the surface. Numerical simulations confirmed the statistical significance of the data.
Biological Diversity, Soils, and Economics
Authors: Huston Michael
Published: October 2006

Terrestrial biological diversity is supported by solar energy captured by plants growing in soil. This soil-based plant productivity also provides the foundation for human societies through production of food and renewable forms of energy. Variations in plant productivity, resulting from differences in inherent soil fertility, variations in climate and weather, and differences in chemical inputs and agricultural practices, produce patterns of biological diversity that are associated with the agricultural component of economic productivity. Ecological processes lead to a generally negative relation between the diversity of plant species and potential agricultural productivity at both local and global scales. One implication of this negative relation is that preservation of areas of high plant biodiversity does not require the sacrifice of productive agricultural lands.
Disruption of the YeastN-Myristoyl Transferase Gene Causes Recessive Lethality
Authors: Duronio Robert J. , Towler Dwight A. , Heuckeroth Robert O. , Gordon Jeffrey I.
Published: October 2006

The structural gene forN-myristoyl transferase (NMT1) has been cloned from the budding yeastSaccharomyces cerevisiae. The gene encodes a polypeptide of 455 amino acids (Mr= 52,837) that has no identifiable significant primary sequence homology with any protein in currently available databases. Overexpression of NMT activity was achieved by means of the yeast episomal plasmid YEp24 without obvious effects on growth kinetics, cell morphology, or acylprotein metabolic labeling patterns. Insertional mutagenesis of theNMT1locus on yeast chromosome XII caused recessive lethality, indicating that this protein acyltransferase activity is necessary for vegetative cell growth.
Genetic Engineering of Bacteria from Managed and Natural Habitats
Authors: Lindow S. E. , Panopoulos N. J. , McFarland B. L.
Published: October 2006

The genetic modification of bacteria from natural and managed habitats will impact on the management of agricultural and environmental settings. Potential applications include crop production and protection, degradation or sequestration of environmental pollutants, extraction of metals from ores, industrial fermentations, and productions of enzymes, diagnostics, and chemicals. Applications of this technology will ultimately include the release of beneficial agents in the environment. If safely deployed, genetically modified bacteria should be able to provide significant benefits in the management of environmental systems and in the development of new environmental control processes.
Taxonomic Differences in the Scaling of Brain on Body Weight Among Mammals
Authors: Pagel Mark D. , Harvey Paul H.
Published: October 2006

Theories for the evolution of brain weight in mammals suggest that closely related species have diverged largely as a result of selection for differences in body weight, but that differences among more distantly related species have arisen due to greater net directional selection on brain weight. This pattern of changing selection causes brain weight to evolve more slowly than body weight among closely related species, such as those in the same genus, than among more distantly related species, such as those from different families or orders; a phenomenon known as the "taxon-level effect." Thus, brain weight differs more for a given difference in body weight as the species compared are more distantly related. An alternative explanation for the taxon-level effect is proposed. Distantly related species are more likely to inhabit different ecological conditions than are more closely related species. Where the taxon-level effect occurs, brain weight appears to have evolved in response to the demands of these different ecological conditions. As a consequence, brain weight differs more among distantly related species, for any given difference in body weight, than among closely related species. This effect, rather than a progressive pattern of changing selection pressures, may account for the taxon-level effect in mammals.
Light Adaptation in Cat Retinal Rods
Authors: Tamura T. , Nakatani K. , Yau K.-W.
Published: October 2006

It has long been an open question whether individual rod receptors in the mammalian retina show any light adaptation. The prevailing evidence so far has suggested that these cells, unlike those in lower vertebrates, adapt little if at all. The experiments on cat rods reported here, however, indicate that this is not really true. Since the cone system in the cat retina has a fairly high light threshold, the rods also need to adapt so that they do not saturate with light before the cones fully take over vision at higher light intensities. In similar experiments, adaptation was found in rods of other mammalian species, including primates.
COOH-Terminal-Modified Interleukin-3 Is Retained Intracellularly and Stimulates Autocrine Growth
Authors: Dunbar Cynthia E. , Browder Timothy M. , Abrams John S. , Nienhuis Arthur W.
Published: October 2006

Autocrine growth due to dysregulated growth factor production may have a role in the development of neoplasia. Whether autocrine growth is stimulated by growth factor secretion in an autocrine loop or by intracellular binding of the growth factor to a receptor has been unclear. The carboxyl-terminus coding sequence for murine interleukin-3 (IL-3) was extended with an oligonucleotide encoding a four-amino acid endoplasmic reticulum retention signal. IL-3-dependent hematopoietic cells became growth factor-independent when the modified IL-3 gene was introduced by retroviral gene transfer, despite lack of secretion of the modified IL-3. Hence autocrine growth can occur as a result of the intracellular action of a growth factor and this mechanism may be important in neoplastic and normal cells.
Second Conserved Domain of gp120 Is Important for HIV Infectivity and Antibody Neutralization
Authors: Ho David D. , Kaplan Joan C. , Rackauskas Indre E. , Gurney Mark E.
Published: October 2006

Rabbit antisera were raised against three overlapping synthetic peptides with sequence homology to the second conserved domain of the external envelope glycoprotein (gp120) of the human immunodeficiency virus (HIV). All of the antisera immunoprecipitated the envelope glycoprotein. In particular, an antiserum directed against amino acids 254 to 274 of
env
was efficient in neutralizing three different isolates of HIV in vitro, without affecting the binding of the virus to CD4-positive cells. Therefore, this conserved region of gp120 appears to be critical in a postbinding event during virus penetration and may represent a target for antibody neutralization of HIV. These findings may be applicable in the design of a vaccine for the acquired immunodeficiency syndrome.
Genetically Transformed Maize Plants from Protoplasts
Authors: Rhodes Carol A. , Pierce Dorothy A. , Mettler Irvin J. , Mascarenhas Desmond , Detmer Jill J.
Published: October 2006

Genetically transformed maize plants were obtained from protoplasts treated with recombinant DNA. Protoplasts that were digested from embryogenic cell suspension cultures of maize inbred A188 were combined with plasmid DNA containing a gene coding for neomycin phosphotransferase (NPT II) next to the 35
S
promoter region of cauliflower mosaic virus. A high voltage electrical pulse was applied to the protoplasts, which were then grown on filters placed over feeder layers of maize suspension cells (Black Mexican Sweet) and selected for growth in the presence of kanamycin. Selected cell lines showed NPT II activity. Plants were regenerated from transformed cell lines and grown to maturity. Southern analysis of DNA extracted from callus and plants indicated the presence of the NPT II gene.
Maternally Inherited Transposon Excision in
Drosophila simulans
Authors: Bryan Glenn J. , Hartl Daniel L.
Published: October 2006

A mutation in the
white
gene of
Drosophila mauritiana
resulting from insertion of the transposable element
mariner
exhibits genetic instability in germline and somatic cells. The instability is greatly enhanced in the presence of the trans-acting autosomal factor
Mos
, giving eye-color mosaics with pigmented sectors of tissue on an otherwise peach-colored background. The
Mos
factor, when introduced into the genome of the sibling species
Drosophila simulans
, exhibited a dramatic maternal effect on expression of the mosaic phenotype. When
D. simulans
mosaic females (heterozygous for
Mos
) were crossed with non-mosaic males, two distinct classes of mosaic offspring occurred, one resulting from a maternal effect in which the non-
Mos
offspring were nevertheless mosaic. The maternal effect was mediated by a product acting after fertilization, and was expressed to varying extents in different backcross strains.
Cellular Transcription Factors and Regulation of IL-2 Receptor Gene Expression by HTLV-I
tax
Gene Product
Authors: Ruben Steven , Poteat Harry , Tan Tse-Hua , Kawakami Kyoshi , Roeder Robert , Haseltine William , Rosen Craig A.
Published: October 2006

Expression of the interleukin-2 receptor (IL-2Rα) gene is activated by the transcriptional activator protein, Tax (previously referred to as the
tat
gene product), encoded by the human T-cell leukemia virus (HTLV-I). Multiple protein binding sites for specific DNA-protein interactions were identified over the upstream IL-2Rα transcriptional regulatory sequences. However, only one region, which includes the sequence motif GGGGAATCTCCC, was required for activation by both the
tax
gene product and mitogenic stimulation. Remarkably, this sequence also bound the nuclear factor NFκB, which is important for induction of κ-immunoglobulin gene expression. A model is presented whereby regulation of cellular gene expression by the HTLV-I
tax
gene product occurs via an indirect mechanism that may involve a post-translational modification of preexistent cellular transcription factors.
Two Anonymous DNA Segments Distinguish the Wilms' Tumor and Aniridia Loci
Authors: Davis Lisa M. , Stallard Richard , Thomas George H. , Couillin Philippe , Junien Claudine , Nowak Norma J. , Shows Thomas B.
Published: October 2006

The association of Wilms' tumor with aniridia (the
WAGR
complex) in children with 11p13 chromosomal abnormalities has been established, but the paucity of molecular probes in 11p13 has hampered identification of the responsible genes. Two new anonymous DNA segments have been identified that map to the
WAGR
region of 11p13. Both DNA probes identify a cytologically undetectable deletion associated with a balanced chromosome translocation inherited by a patient with familial aniridia, but not Wilms' tumor. The same two DNA segments are also included in the distal p13-p14.1 deletion of another patient, who has aniridia, Wilms' tumor, and hypogonadism, but they are not included in the p12-p13 deletion of a third patient, who does not have aniridia but has had a Wilms' tumor. The discovery of this aniridia deletion and these two DNA segments that physically separate the Wilms' tumor and aniridia loci should facilitate identification of the genes in the
WAGR
locus, beginning with the aniridia gene.
Arginine Vasopressin as a Thyrotropin-Releasing Hormone
Authors: Lumpkin Michael D. , Samson Willis K. , McCann Samuel M.
Published: October 2006

Although hypothyroidism (with concomitant increased levels of thyroid-stimulating hormone) has been associated with elevated plasma vasopressin, the role that vasopressin plays in controlling thyroid-stimulating hormone secretion from the adenohypophysis is not understood. In two in vitro pituitary cell systems, vasopressin caused a specific and dose-related release of thyroid-stimulating hormone from cells that was equal in potency to that elicited by thyrotropin-releasing hormone, the primary acknowledged regulator of thyroid-stimulating hormone release. When injected into the hypothalamus, however, vasopressin specifically inhibited the release of thyroid-stimulating hormone. Thus, vasopressin may exert differential regulatory effects on thyroid-stimulating hormone secretion in the hypothalamus and pituitary gland.
Homeo Domain of the Yeast Repressor α2 Is a Sequence-Specific DNA-Binding Domain But Is Not Sufficient for Repression
Authors: Hall Michael N. , Johnson Alexander D.
Published: October 2006

The α2 protein, the product of the
MAT
α2 gene, is a regulator of cell type in the yeast
Saccharomyces cerevisiae
. It represses transcription of a group of cell type-specific genes by binding to an operator located upstream of each target gene. Fifteen in-frame deletions within the coding region of the
MAT
α2 gene were constructed. The deletion alleles were examined for phenotypes conferred in vivo, and the encoded mutant proteins were assayed for ability to bind specifically to the operator in vitro. This analysis has revealed that the sequence-specific DNA-binding domain of α2 is located within a region of 68 amino acids. This region of α2 has significant homology with the homeo domain, a conserved sequence found in the products of several
Drosophila
homeotic and segmentation genes. In addition, there is a class of mutant α2 proteins that binds tightly and specifically to the operator in vitro, but fails to repress transcription in vivo.
A Chemically Synthesized
Antennapedia
Homeo Domain Binds to a Specific DNA Sequence
Authors: Mihara Hisakazu , Kaiser Emil Thomas
Published: October 2006

A peptide 60 residues in length that corresponds to the homeo domain of
Antennapedia
(
Antp
), a protein governing development in
Drosophila
, was synthesized by segment condensation with protected peptide segments prepared on an oxime resin. A footprinting assay showed that the homeo domain binds specifically to a TAA repeat DNA sequence in the
Antp
gene. Thus the
Antp
homeo domain has a sequence-specific DNA binding property. The circular dichroism spectra of the homeo domain peptide showed the presence of a significant amount of α-helical structure in aqueous solution and in 50 percent trifluoroethanol. The α helicity measured in water appears to depend on the peptide concentration, which suggests that the peptide aggregates. These results support the hypothesis that the homeo domain binds to DNA through a helix-turn-helix motif.
Protein Structure Determination in Solution by Nuclear Magnetic Resonance Spectroscopy
Authors: Wüthrich Kurt
Published: October 2006

Knowledge of three-dimensional protein structures is one of the foundations of protein design and protein engineering. Nuclear magnetic resonance spectroscopy was recently introduced as a second method for protein structure determination, in addition to the well-established diffraction techniques with protein single crystals. This new approach enables one to carry out detailed structural studies of proteins in solution and other noncrystalline states, which may be similar or identical to the physiological environment, and promises new insights into the dynamics of protein molecules and the protein-folding problem.
Histamine is an Intracellular Messenger Mediating Platelet Aggregation
Authors: Saxena Satya P. , Brandes Lorne J. , Becker Allan B. , Simons Keith J. , LaBella Frank S. , Gerrard Jon M.
Published: October 2006

Inhibition of human platelet aggregation byN,N-diethyl-2-[4-(phenylmethyl)phenoxy]ethanamine-HCl (DPPE), a novel antagonist of histamine binding, suggested that histamine might serve a critical role in cell function. Phorbol-12-myristate-13-acetate (PMA) or collagen was found to increase platelet histamine content in parallel with promotion of aggregation. Inhibitors of histidine decarboxylase (HDC) suppressed both aggregation and the elevation of histamine content, whereas DPPE inhibited aggregation only. In saponin-permeabilized platelets, added histamine reversed the inhibition by DPPE or HDC inhibitors on aggregation induced by PMA or collagen. The results indicate a role for histamine as an intracellular messenger, which in platelets promotes aggregation.