bluuebunny/crossref_metadata_2025 huggingface dataset:
Angiotensin II-Induced Calcium Mobilization in Oocytes by Signal Transfer Through Gap Junctions
Authors: Sandberg Kathryn , Bor Marta , Ji Hong , Markwick Alison , Millan Monica A. , Catt Kevin J
Published: October 2006

Angiotensin II (AII) stimulates rapid increases in the concentration of cytosolic calcium in follicular oocytes from
Xenopus laevis
. This calcium response was not present in denuded oocytes, indicating that it is mediated by AII receptors on the adherent follicular cells. The endogenous AII receptors differed in their binding properties from mammalian AII receptors expressed on the oocyte surface after injection of rat adrenal messenger RNA. Also, the calcium responses to activation of the amphibian AII receptor, but not the expressed mammalian AII receptor, were blocked reversibly by octanol and intracellular acidification, treatments that inhibit cell coupling through gap junctions. In addition, AII increased the rate of progesterone-induced maturation. Thus, an AII-induced calcium-mobilizing signal is transferred from follicle cells to the oocyte through gap junctions and may play a physiological role in oocyte maturation.
Three-Dimensional Structure of Cellobiohydrolase II from
Trichoderma reesei
Authors: Rouvinen J. , Bergfors T. , Teeri T. , Knowles J. K. , Jones T. A.
Published: October 2006

The enzymatic degradation of cellulose is an important process, both ecologically and commercially. The three-dimensional structure of a cellulase, the enzymatic core of CBHII from the fungus
Trichoderma reesei
reveals an α-β protein with a fold similar to but different from the widely occurring barrel topology first observed in triose phosphate isomerase. The active site of CBHII is located at the carboxyl-terminal end of a parallel β barrel, in an enclosed tunnel through which the cellulose threads. Two aspartic acid residues, located in the center of the tunnel are the probable catalytic residues.
Deep-Sea Hydrocarbon Seep Communities: Evidence for Energy and Nutritional Carbon Sources
Authors: Brooks James M. , Kennicutt M. C. , Fisher C. R. , Macko S. A. , Cole K. , Childress J. J. , Bidigare R. R. , Vetter R. D.
Published: October 2006

Mussels, clams, and tube worms collected in the vicinity of hydrocarbon seeps on the Louisiana slope contain mostly "dead" carbon, indicating that dietary carbon is largely derived from seeping oil and gas. Enzyme assays, elemental sulfur analysis, and carbon dioxide fixation studies demonstrate that vestimentiferan tube worms and three clam species contain intracellular, autotrophic sulfur bacterial symbionts. Carbon isotopic ratios of 246 individual animal tissues were used to differentiate heterotrophic (δ
13
C = -14 to -20 per mil), sulfur-based (δ
13
C = -30 to -42 per mil), and methane-based (δ
13
C = <-40 per mil) energy sources. Mussels with symbiotic methanotrophic bacteria reflect the carbon isotopic composition of the methane source. Isotopically light nitrogen and sulfur confirm the chemoautotrophic nature of the seep animals. Sulfur-based chemosynthetic animals contain isotopically light sulfur, whereas methane-based symbiotic mussels more closely reflect the heavier oceanic sulfate pool. The nitrogen requirement of some seep animals may be supported by nitrogen-fixing bacteria. Some grazing neogastropods have isotopic values characteristic of chemosynthetic animals, suggesting the transfer of carbon into the background deep-sea fauna.
Quantitative Three-Dimensional Optical Tomographic Imaging of Supersonic Flows
Authors: Faris Gregory W. , Byer Robert L.
Published: October 2006

Three-dimensional imaging of the density of nitrogen in a supersonic expansion from a nozzle by means of beam-deflection optical tomography is described. With a very simple apparatus, images could be obtained with high absolute accuracy, high spatial resolution, and wide dynamic range.
Structural Transitions Upon Ligand Binding in a Cooperative Dimeric Hemoglobin
Authors: Royer William E. , Hendrickson Wayne A. , Chiancone Emilia
Published: October 2006

Comparison of the 2.4 angstrom resolution crystal structures of dimeric clam hemoglobin in the deoxygenated and carbon-monoxide liganded states shows how radically different the structural basis for cooperative oxygen binding is from that operative in mammalian hemoglobins. Heme groups are in direct communication across a novel subunit interface formed by the E and F helices. The conformational changes at this interface that accompany ligand binding are more dramatic at a tertiary level but more subtle at a quaternary level than those in mammalian hemoglobins. These findings suggest a cooperative mechanism that links ligation at one subunit with potentiation of affinity at the second subunit.
Anthopleurine: A Sea Anemone Alarm Pheromone
Authors: Howe Nathan R. , Sheikh Younus M.
Published: October 2006

The sea anemone
Anthopleura elegantissima
responds with characteristic contraction to a pheromone released by wounded conspecifics. The alarm pheromone was isolated by ion-exchange chromatography and identified by chemical and spectroscopic methods as the quaternary ammonium ion (3-carboxy-2,3-dihydroxy-
N
,
N
,
N
-trimethyl)-1-propanaminium. Median effective concentration of the crystalline pheromone is 3.5 × 10
-10
mole per liter of seawater.
The Vibrational Spectroscopy and Dynamics of Weakly Bound Neutral Complexes
Authors: Miller R. E.
Published: October 2006

A growing number of binary and tertiary van der Waals and hydrogen-bonded complexes are being studied by means of near-infrared laser spectroscopy. Studies of this type have generated a wealth of detailed structural and dynamical information that provides exacting tests of the corresponding theoretical methods. An additional incentive for the investigation of such clusters arises from the fact that they may be considered as intermediates between the gas and condensed phases of matter. As a result, these systems represent a fertile meeting ground for researchers from both fields and can often be studied with a variety of methods.
Superconducting and Magnetic Behavior in La
2-x
Na
x
CuO
4
Authors: Subramanian M. A. , Gopalakrishnan J. , Torardi C. C. , Askew T. R. , Flippen R. B. , Sleight A. W. , Lin J. J. , Poon S. J.
Published: October 2006

New phases of the type La

2-
x

A

x

1+
CuO

4-
y

have been prepared where A
1+
is sodium or potassium. The sodium phases are superconducting for
x
values from 0.2 to 0.5 at temperatures up to about 40 K. In addition, there are unusual magnetic properties below about 10 K that may be indicative of spin glass behavior. Phases of the type La

2-
x

K

x

CuO

4-
y

could only be prepared with
x
values up to about 0.1, and these phases are not superconducting above 4.2 K.
North Carolina Climate Changes Reconstructed from Tree Rings: A.D. 372 to 1985
Authors: Stahle D. W. , Cleaveland M. K. , Hehr J. G.
Published: October 2006

Millennium-old bald cypress trees (
Taxodium distichum
[(L.) Rich.] have been used to develop a 1614-year reconstruction of the June Palmer drought severity index for North Carolina. This proxy paleoclimatic record indicates that the growing season climate of North Carolina has undergone many changes between significantly different regimes of drought and wetness that persist for approximately 30 years. Alternating wet and dry regimes were particularly well developed during the Medieval Warm Epoch (A.D. 1000 to 1300). The record June droughts in 1985 and 1986 and the preceding three decades of much wetter than average conditions both appear to have been rare climatic events, equaled only five times each since A.D. 372.
Tyrosine Kinase Activity and Transformation Potency of
bcr-abl
Oncogene Products
Authors: Lugo Tracy G. , Pendergast Ann-Marie , Muller Alexander J. , Witte Owen N.
Published: October 2006

Oncogenic activation of the proto-oncogene c-
abl
in human leukemias occurs as a result of the addition of exons from the gene
bcr
and truncation of the first
abl
exon. Analysis of tyrosine kinase activity and quantitative measurement of transformation potency in a single-step assay indicate that variation in
bcr
exon contribution results in a functional difference between p210

bcr-abl

and p185

bcr-abl

proteins. Thus, foreign upstream sequences are important in the deregulation of the kinase activity of the
abl
product, and the extent of deregulation correlates with the pathological effects of the
bcr-abl
proteins.
Numerical Evidence That the Motion of Pluto Is Chaotic
Authors: Sussman Gerald Jay , Wisdom Jack
Published: October 2006

The Digital Orrery has been used to perform an integration of the motion of the outer planets for 845 million years. This integration indicates that the long-term motion of the planet Pluto is chaotic. Nearby trajectories diverge exponentially with an
e
-folding time of only about 20 million years.
Direct Measurement of O
2
-Depleted Microzones in Marine
Oscillatoria
: Relation to N
2
Fixation
Authors: Paerl Hans W. , Bebout Brad M.
Published: October 2006

Among the nitrogen (N
2
)-fixing cyanobacteria, the filamentous, nonheterocystous marine
Oscillatoria
spp. (
Trichodesmium
) appears enigmatic; it exhibits N
2
fixation in the presence of oxygenic photosynthesis without structural protection of the N
2-
fixing apparatus (nitrogenase) from potential inhibition by molecular oxygen (O
2
). Characteristically, N
2
fixation is largely confined to aggregates (bundles) of filaments. Previous work has suggested that spatial partitioning of photosynthesis and of N
2
fixation occurs in the bundles as a means of allowing both processes to occur contemporaneously. The probing of freshly sampled bundles with O
2
microelectrodes directly confirmed such partitioning by showing the presence of O
2-
depleted (reduced) microzones in photosynthetically active, N
2-
fixing bundles. Bundle size was directly related to both the development of internal reduced microzones and cellular N
2
fixation rates. By enhancing microzone formation, bundles optimize N
2
fixation as a means of supporting
Oscillatoria
spp. blooms in surficial, nitrogen-depleted tropical and subtropical waters.
Climatic Changes of the Last 18,000 Years: Observations and Model Simulations
Authors:   COHMAP Members
Published: October 2006

Changes in solar radiation arising from changes in the orientation of the earth's axis had pronounced effects on tropical monsoons and mid-latitude climates as well as on ice-sheet configuration during the last 18,000 years. COHMAP (Cooperative Holocene Mapping Project) has assembled a global array of well-dated paleoclimatic data and used general-circulation models to identify and evaluate causes and mechanisms of climatic change. For the northern tropics, particularly in Africa and Asia, data and model results show that the orbitally induced increase in solar radiation in summer 12,000 to 6,000 years ago enhanced the thermal contrast between land and sea and thus produced strong summer monsoons, which raised lake levels in regions that are arid today. In middle to high latitudes the climatic response to both the insolation changes and to the retreating ice sheets led to readjustments in the vegetation in both the Northern and Southern hemispheres. Model results show that the large North American ice sheet split the westerly jet stream into northern and southern branches over North America. An increase in storms associated with the southern branch helps explain high lake levels and increased woodlands in the southwestern United States during full-glacial conditions. Comparisons of paleoclimatic data with the model simulations are important because models provide a theoretical framework for evaluating mechanisms of climatic change, and such comparisons help to evaluate the potential of general circulation models for predicting future climates.
Bulk Superconductivity at 122 K in T1(Ba,Ca)
2
Ca
3
Cu
4
O
10.5+δ
with Four Consecutive Copper Layers
Authors: Haldar P. , Chen K. , Maheswaran B. , Roig-Janicki A. , Jaggi N. K. , Markiewicz R. S. , Giessen B. C.
Published: October 2006

The observed increase of superconducting transition temperature (
T
c
) with the number of copper oxide planes continues in the four-[CuO
2
]
-2
layer (single TI layer) oxide superconductor, which has been prepared with > 80% purity and was magnetically aligned for crystallographic identification. A master scaling curve is proposed, which ties together the
T
c
's of virtually all known Bi and Tl oxide superconductors, and shows that the Tl(Bi) layers play an essential role in the superconductivity.
The Structure and Symmetry of Crystalline Solid Solutions: A General Revision
Authors: Vaida M. , Shimon L. J. W. , Weisinger-Lewin Y. , Frolow F. , Lahav M. , Leiserowitz L. , McMullan R. K.
Published: October 2006

Mixed single crystals composed of host and guest organic molecules of similar structures and shapes are shown to comprise sectors with different host-guest distributions and to have symmetries lower than that of the host crystal. These properties are determined by the structure of the guest and the surface structures of the crystal faces through which the guest molecules are occluded. This general concept is illustrated by studies of three mixed crystal systems, (
E
)-cinnamamide—(
E
)-2-thienylacrylamide, (
E
)-cinnamamide—(
E
)-3-thienylacrylamide, and (
S
)-asparagine—(
S
)-aspartic acid, with x-ray and neutron diffraction and solid-state photochemistry.
AAAS Presidential Lecture: Voices from the Pipeline
Authors: Widnall Sheila E.
Published: October 2006

The number of white males of college age, who have been the dominant participants in the fields of science and engineering, is predicted to drop significantly in the future. Rapid increases in the participation of women offer some hope of filling anticipated vacancies in the ranks of scientifically trained personnel, although this rapid growth has reached a plateau in many fields. Most studies show that women enter graduate school at about the same rate as men; the dropoff in women's participation occurs sometime before the attainment of the Ph.D. Recent surveys of graduate students indicate that men and women respond differently to the pressures of graduate school and often have a different image of themselves and of their advisers' perceptions of them as graduate students. Some clues from these results may show how the environment can be made more supportive for all students, and for women and minority students in particular.
Induction of AIDS-Like Disease in Macaque Monkeys with T-Cell Tropic Retrovirus STLV-III
Authors: Letvin N. L. , Daniel M. D. , Sehgal P. K. , Desrosiers R. C. , Hunt R. D. , Waldron L. M. , MacKey J. J. , Schmidt D. K. , Chalifoux L. V. , King N. W.
Published: October 2006

The T-cell tropic retrovirus of macaque monkeys STLV-III has morphologic, growth, and antigenic properties indicating that it is related to HTLV-III/LAV, the etiologic agent of the acquired immune deficiency syndrome (AIDS) in humans. Four of six rhesus monkeys died within 160 days of STLV-III inoculation with a wasting syndrome, opportunistic infections, a primary retroviral encephalitis, and immunologic abnormalities including a decrease in T4
+
peripheral blood lymphocytes. These data show that an immunodeficiency syndrome can be produced experimentally in a nonhuman primate by an agent from the HTLV-III/LAV group of retroviruses. The STLV-III-macaque system will thus provide a useful model for the study of antiviral agents and vaccine development for human AIDS.
Long-Term Cultures of HTLV-III—Infected T Cells: a Model of Cytopathology of T-Cell Depletion in AIDS
Authors: Zagury D. , Bernard J. , Leonard R. , Cheynier R. , Feldman M. , Sarin P. S. , Gallo R. C.
Published: October 2006

Long-term cultures were established of HTLV-III-infected T4 cells from patients with the acquired immune deficiency syndrome (AIDS) and of T4 cells from normal donors after infection of the cells in vitro. By initially reducing the number of cells per milliliter of culture medium it was possible to grow the infected cells for 50 to 60 days. As with uninfected T cells, immunologic activation of the HTLV-III-infected cells with phytohemagglutinin led to patterns of gene expression typical of T-cell differentiation, such as production of interleukin-2 and expression of interleukin-2 receptors, but in the infected cells immunologic activation also led to expression of HTLV-III, which was followed by cell death. The results revealed a cytopathogenic mechanism that may account for T4 cell depletion in AIDS patients and suggest how repeated antigenic stimulation by infectious agents, such as malaria in Africa, or by allogeneic blood or semen, may be important determinants of the latency period in AIDS.
In Situ Northern Mid-Latitude Observations of ClO, O
3
, and BrO in the Wintertime Lower Stratosphere
Authors: Brune W. H. , Toohey D. W. , Anderson J. G. , Starr W. L. , Vedder J. F. , Danielsen E. F.
Published: October 2006

In order to test photochemical theories linking chlorofluorocarbon derivatives to ozone (O
3
) depletion at high latitudes in the springtime, several related atmospheric species, including O
3
, chlorine monoxide (ClO), and bromine monoxide (BrO) were measured in the lower stratosphere with instruments mounted on the NASA ER-2 aircraft on 13 February 1988. The flight path from Moffett Field, California (37°N, 121°W), to Great Slave Lake, Canada (61°N, 115°W), extended to the center of the polar jet associated with but outside of the Arctic vortex, in which the abundance of O
3
was twice its mid-latitude value, whereas BrO levels were 5 parts per trillion by volume (pptv) between 18 and 21 kilometers, and 2.4 pptv below that altitude. The ClO mixing ratio was as much as 65 pptv at 60°N latitude at an altitude of 20 kilometers, and was enhanced over mid-latitude values by a factor of 3 to 5 at altitudes above 18 kilometers and by as much as a factor of 40 at altitudes below 17 kilometers. Levels of ClO and O
3
were highly correlated on all measured distance scales, and both showed an abrupt change in character at 54°N latitude. The enhancement of ClO abundance north of 54°N was most likely caused by low nitrogen dioxide levels in the flight path.
The Further Evolution of Cooperation
Authors: Axelrod Robert , Dion Douglas
Published: October 2006

Axelrod's model of the evolution of cooperation was based on the iterated Prisoner's Dilemma. Empirical work following this approach has helped establish the prevalence of cooperation based on reciprocity. Theoretical work has led to a deeper understanding of the role of other factors in the evolution of cooperation: the number of players, the range of possible choices, variation in the payoff structure, noise, the shadow of the future, population dynamics, and population structure.
Design of Sequence-Specific DNA-Binding Molecules
Authors: Dervan Peter B.
Published: October 2006

Base sequence information can be stored in the local structure of right-handed double-helical DNA (B-DNA). The question arises as to whether a set of rules for the three-dimensional readout of the B-DNA helix can be developed. This would allow the design of synthetic molecules that bind DNA of any specific sequence and site size. There are four stages of development for each new synthetic sequence-specific DNA-binding molecule: design, synthesis, testing for sequence specificity, and reevaluation of the design. This approach has produced bis(distamycin)fumaramide, a synthetic, crescent-shaped oligopeptide that binds nine contiguous adenine-thymine base pairs in the minor groove of double-helical DNA.
Cordierite-Spinel Troctolite, a New Magnesium-Rich Lithology from the Lunar Highlands
Authors: Marvin Ursula B. , Carey J. William , Lindstrom Marilyn M.
Published: October 2006

A clast of spinel troctolite containing 8 percent cordierite (Mg
2
Al
4
Si
5
O
18
) has been identified among the constituents of Apollo 15 regolith breccia 15295. The cordierite and associated anorthite, forsteritic olivine, and pleonaste spinel represent a new, Mg-rich lunar highlands lithology that formed by metamorphism of an igneous spinel cumulate. The cordierite-forsterite pair in the assemblage is stable at a maximum pressure of 2.5 kilobars, equivalent to a depth of 50 kilometers, or 10 kilometers above the lunar crust-mantle boundary. The occurrence of the clast indicates that spinel cumulates are a more important constituent of the lower lunar crust than has been recognized. The rarity of cordierite-spinel troctolite among lunar rock samples suggests that it is excavated only by large impact events, such as the one that formed the adjacent Imbrium Basin.
A G Protein Couples Serotonin and GABA
B
Receptors to the Same Channels in Hippocampus
Authors: Andrade R. , Malenka R. C. , Nicoll R. A.
Published: October 2006

Both serotonin and the selective γ-aminobutyric acid
B
(GABA
B
) agonist, baclofen, increase potassium (K
+
) conductance in hippocampal pyramidal cells. Although these agonists act on separate receptors, the potassium currents evoked by the agonists are not additive, indicating that the two receptors share the same potassium channels. Experiments with hydrolysis-resistant guanosine triphosphate (GTP) and guanosine diphosphate analogs and pertussis toxin indicate that the opening of the potassium channels by serotonin and GABA
B
receptors involves a pertussis toxin-sensitive GTP-binding (G) protein, which may directly couple the two receptors to the potassium channel.
Global Sea Level Rise and the Greenhouse Effect: Might They Be Connected?
Authors: Peltier W. R. , Tushingham A. M.
Published: October 2006

Secular sea level trends extracted from tide gauge records of appropriately long duration demonstrate that global sea level may be rising at a rate in excess of 1 millimeter per year. However, because global coverage of the oceans by the tide gauge network is highly nonuniform and the tide gauge data reveal considerable spatial variability, there has been a well-founded reluctance to interpret the observed secular sea level rise as representing a signal of global scale that might be related to the greenhouse effect. When the tide gauge data are filtered so as to remove the contribution of ongoing glacial isostatic adjustment to the local sea level trend at each location, then the individual tide gauge records reveal sharply reduced geographic scatter and suggest that there is a globally coherent signal of strength 2.4 ± 0.90 millimeters per year that is active in the system. This signal could constitute an indication of global climate warming.
Sequence of a Probable Potassium Channel Component Encoded at
Shaker
Locus of
Drosophila
Authors: Tempel Bruce L. , Papazian Diane M. , Schwarz Thomas L. , Jan Yuh Nung , Jan Lily Yeh
Published: October 2006

Potassium currents are crucial for the repolarization of electrically excitable membranes, a role that makes potassium channels a target for physiological modifications that alter synaptic efficacy. The
Shaker
locus of
Drosophila
is thought to encode a K
+
channel. The sequence of two complementary DNA clones from the
Shaker
locus is reported here. The sequence predicts an integral membrane protein of 70,200 daltons containing seven potential membrane-spanning sequences. In addition, the predicted protein is homologous to the vertebrate sodium channel in a region previously proposed to be involved in the voltage-dependent activation of the Na
+
channel. These results support the hypothesis that
Shaker
encodes a structural component of a voltage-dependent K
+
channel and suggest a conserved mechanism for voltage activation.
After Insulin Binds
Authors: Rosen Ora M.
Published: October 2006

Three recent advances pertinent to the mechanism of insulin action include (i) the discovery that the insulin receptor is an insulin-dependent protein tyrosine kinase, functionally related to certain growth factor receptors and oncogene-encoded proteins, (ii) the molecular cloning of the insulin proreceptor complementary DNA, and (iii) evidence that the protein tyrosine kinase activity of the receptor is essential for insulin action. Efforts are now focusing on the physiological substrates for the receptor kinase. Experience to date suggests that they will be rare proteins whose phosphorylation in intact cells may be transient. The advantages of attempting to dissect the initial biochemical pathway of insulin action include the wealth of information about the metabolic consequences of insulin action and the potential for genetic analysis in
Drosophila
and in man.
A G Protein Directly Regulates Mammalian Cardiac Calcium Channels
Authors: Yatani Atsuko , Codina Juan , Imoto Yutaka , Reeves John P. , Birnbaumer Lutz , Brown Arthur M.
Published: October 2006

A possible direct effect of guanine nucleotide binding (G) proteins on calcium channels was examined in membrane patches excised from guinea pig cardiac myocytes and bovine cardiac sarcolemmal vesicles incorporated into planar lipid bilayers. The guanosine triphosphate analog, GTPγS, prolonged the survival of excised calcium channels independently of the presence of adenosine 3′,5′-monophosphate (cAMP), adenosine triphosphate, cAMP-activated protein kinase, and the protein kinase C activator tetradecanoyl phorbol acetate. A specific G protein, activated G
s
, or its α subunit, purified from the plasma membranes of human erythrocytes, prolonged the survival of excised channels and stimulated the activity of incorporated channels. Thus, in addition to regulating calcium channels indirectly through activation of cytoplasmic kinases, G proteins can regulate calcium channels directly. Since they also directly regulate a subset of potassium channels, G proteins are now known to directly gate two classes of membrane ion channels.
The
Diageotropica
Mutant of Tomato Lacks High Specific Activity Auxin Binding Sites
Authors: Hicks Glenn R. , Rayle David L. , Lomax Terri L.
Published: October 2006

Tomato plants homozygous for the
diageotropica
(
dgt
) mutation exhibit morphological and physiological abnormalities which suggest that they are unable to respond to the plant growth hormone auxin (indole-3-acetic acid). The photoaffinity auxin analog [
3
H]5N
3
-IAA specifically labels a polypeptide doublet of 40 and 42 kilodaltons in membrane preparations from stems of the parental variety, VFN8, but not from stems of plants containing the
dgt
mutation. In roots of the mutant plants, however, labeling is indistinguishable from that in VFN8. These data suggest that the two polypeptides are part of a physiologically important auxin receptor system, which is altered in a tissue-specific manner in the mutant.
Computational Aerodynamics for Aircraft Design
Authors: Jameson Antony
Published: October 2006

This article outlines some of the principal issues in the development of numerical methods for the prediction of flows over aircraft and their use in the design process. These include the choice of an appropriate mathematical model, the design of shock-capturing algorithms, the treatment of complex geometric configurations, and shape modifications to optimize the aerodynamic performance.
Melting Inhibition and Superheating of Ice by an Antifreeze Glycopeptide
Authors: Knight C. A. , DeVries A. L.
Published: October 2006

The melting of pure ice single crystals can be inhibited by the presence of an antifreeze glycopeptide isolated from an Antarctic fish. This inhibition effect exhibits crystallographic dependence and can result in superheating of the crystal by heat conduction across the ice-solution interface. The antifreeze molecules inhibit melting in a manner more or less symmetrical to their well-known effect of inhibiting freezing. The melting effect is best expressed at concave ice interfaces, whereas the freezing effect is best expressed at convex ones. Both are restricted to orientations near (101̅0) with the particular antifreeze that was used.
The Growth of Japanese Science and Technology
Authors: Narin Francis , Frame J. Davidson
Published: October 2006

Several measures are used to delineate the remarkable growth in the Japanese technological position over the last decade. The share of U.S. patents issued to Japanese inventors has been rising at 1 percent per year. These patents are the most frequently cited patents in the U.S. system. By 1984, Japanese inventors obtained more U.S. patents than inventors in the United Kingdom, France, and West Germany combined, and the gap has been widening ever since. As measured by publications, the Japanese scientific position is more modest, with a 0.5 percent rise per year in papers and with barely average citation performance. These indicators characterize Japan as a technological powerhouse, with highly innovative technology, and an expanding but far less powerful scientific position.
Nonequilibrium Molecular Motion in a Hypersonic Shock Wave
Authors: Pham-Van-Diep G. , Erwin D. , Muntz E. P.
Published: October 2006

Molecular velocities have been measured inside a hypersonic, normal shock wave, where the gas experiences rapid changes in its macroscopic properties. As first hypothesized by Mott-Smith, but never directly observed, the molecular velocity distribution exhibits a qualitatively bimodal character that is derived from the distribution functions on either side of the shock. Quantitatively correct forms of the molecular velocity distribution function in highly nonequilibrium flows can be calculated, by means of the Direct Simulation Monte Carlo technique.
Superconducting Gap in Bi-Sr-Ca-Cu-O by High-Resolution Angle-Resolved Photoelectron Spectroscopy
Authors: Olson C. G. , Liu R. , Yang A.-B. , Lynch D. W. , Arko A. J. , List R. S. , Veal B. W. , Chang Y. C. , Jiang P. Z. , Paulikas A. P.
Published: October 2006

Detailed studies indicate a superconducting gap in the high-temperature superconductor Bi
2
Sr
2
CaCu
2
O
8
. Photoemission measurements with high energy and angle resolution isolate the behavior of a single band as it crosses the Fermi level in both the normal and superconducting states, giving support to the Fermi liquid picture. The magnitude of the gap is 24 millielectron volts.
Evidence from Sediments of Long-Term
Acanthaster planci
Predation on Corals of the Great Barrier Reef
Authors: Walbran Peter D. , Henderson Robert A. , Jull A. J. Timothy , Head M. John
Published: October 2006

Since 1962 the crown-of-thorns starfish,
Acanthaster planci
, has caused the devastation of living coral in large tracts of the Great Barrier Reef, Australia. Some authorities view this as a modern phenomenon, resulting from ecological disturbance caused by man. Evidence from skeletal remains in sediment suggests that large
A. planci
populations have been part of the Great Barrier Reef ecosystem for at least 8000 years. Coral predation by
A. planci
is likely to have influenced the morphological fabric of the Great Barrier Reef in its post-glacial development and may also have influenced species richness of the reef biota.
Effect of Forskolin on Voltage-Gated K
+
Channels Is Independent of Adenylate Cyclase Activation
Authors: Hoshi Toshinori , Garber Sarah S. , Aldrich Richard W.
Published: October 2006

Forskolin is commonly used to stimulate adenylate cyclase in the study of modulation of ion channels and other proteins by adenosine 3′,5′-monophosphate (cAMP)-dependent second messenger systems. In addition to its action on adenylate cyclase, forskolin directly alters the gating of a single class of voltage-dependent potassium channels from a clonal pheochromocytoma (PC12) cell line. This alteration occurred in isolated cell-free patches independent of soluble cytoplasmic enzymes. The effect of forskolin was distinct from those of other agents that raise intracellular cAMP levels. The 1,9-dideoxy derivative of forskolin, which is unable to activate the cyclase, was also effective in altering the potassium channel activity. This direct action of forskolin can lead to misinterpretation of results in experiments in which forskolin is assumed to selectively activate adenylate cyclase.
Inactivation and Block of Calcium Channels by Photo-Released Ca
2+
in Dorsal Root Ganglion Neurons
Authors: Morad Martin , Davies Noel W. , Kaplan Jack H. , Lux H. Dieter
Published: October 2006

Calcium channels are inactivated by voltage and intracellular calcium. To study the kinetics and the mechanism of calcium-induced inactivation of calcium channels, a "caged" calcium compound, dimethoxy-nitrophen was used to photo-release about 50 μ
M
calcium ion within 0.2 millisecond in dorsal root ganglion neurons. When divalent cations were the charge carriers, intracellular photo-release of calcium inactivated the calcium channel with an invariant rate [time constant (τ) ≈ 7 milliseconds]. When the monovalent cation sodium was the charge carrier, photorelease of calcium inside or outside of the cell blocked the channel rapidly (τ ≈ 0.4 millisecond), but the block was greater from the external side. Thus the kinetics of calcium-induced calcium channel inactivation depends on the valency of the permeant cation. The data imply that calcium channels exist in either of two conformational states, the calcium- and sodium-permeant forms, or, alternatively, calcium-induced inactivation occurs at a site closely associated with the internal permeating site.
Ordered Interstrand and Intrastrand DNA Transfer During Reverse Transcription
Authors: Panganiban Antonito T. , Fiore Diccon
Published: October 2006

Retroviruses contain two copies of the plus stranded viral RNA genome. As a means of determining whether both of these RNA's are used in the reverse transcription reaction, cells were infected with heterozygous virus particles that varied in nucleotide sequence at two separate locations at the RNA termini. The DNA proviruses formed from a single cycle of reverse transcription were then examined. Of the 12 proviruses that were characterized, all exhibited long terminal repeats (LTR's) that would be expected to arise only if both RNA templates were used for the generation of minus strand DNA. In contrast, only a single minus strand DNA appeared to be used as template for the plus strand DNA in the generation of fully double-stranded viral DNA. These results indicate that the first strand transfer step in reverse transcription is an intermolecular event while that of the second transfer is intramolecular. Thus, retroviruses contain two functionally active RNA's, and both may be required for the generation of a single linear DNA molecule. Formation of heterozygotes during retrovirus infection would be expected to result in the efficient generation of LTR recombinants.
Structure and Function of Voltage-Sensitive Ion Channels
Authors: Catterall William A.
Published: October 2006

Voltage-sensitive ion channels mediate action potentials in electrically excitable cells and play important roles in signal transduction in other cell types. In the past several years, their protein components have been identified, isolated, and restored to functional form in the purified state. Na
+
and Ca
2+
channels consist of a principal transmembrane subunit, which forms the ion-conducting pore and is expressed with a variable number of associated subunits in different cell types. The principal subunits of voltage-sensitive Na
+
, Ca
2+
, and K
+
channels are homologous members of a gene family. Models relating the primary structures of these principal subunits to their functional properties have been proposed, and experimental results have begun to define a functional map of these proteins. Coordinated application of biochemical, biophysical, and molecular genetic methods should lead to a clear understanding of the molecular basis of electrical excitability.
Scanning Tunneling Microscopy and Nanolithography on a Conducting Oxide, Rb
0.3
MoO
3
Authors: Garfunkel E. , Rudd G. , Novak D. , Wang S. , Ebert G. , Greenblatt M. , Gustafsson T. , Garofalini S. H.
Published: October 2006

The scanning tunneling microscope has been used to image and modify the surface of a conducting oxide (Rb
0.3
MoO
3
) in ambient atmosphere. Individual octahedral MoO
6
units of the oxide can be imaged, and under certain conditions defects can be created in the surface that are stable in air. The ability to produce nanometer-sized structures on the surface of an oxide is demonstrated and discussed with reference to nanolithographic applications.
Understanding Behavior in Escalation Situations
Authors: Staw Barry M. , Ross Jerry
Published: October 2006

Everyday observation reveals that both individuals and organizations often become overly committed to losing courses of action; in a sense, throwing good money after bad. More than 10 years of research on this escalation problem shows that persistence is associated with at least four major classes of determinants: project, psychological, social, and organizational variables. The influence of these four sets of variables evolves over time, forming a dynamic model of behavior in escalation situations.
Covariance Mapping: A Correlation Method Applied to Multiphoton Multiple Ionization
Authors: Frasinski L. J. , Codling K. , Hatherly P. A.
Published: October 2006

In some cases there are hidden correlations in a highly fluctuating signal, but these are lost in a conventional averaging procedure. Covariance mapping allows these correlations to be revealed unambiguously. As an example of the applicability of this technique, the dynamics of fragmentation of molecules ionized by an intense picosecond laser are analyzed.
Voyager Radio Science Observations of Neptune and Triton
Authors: Tyler G. L. , Sweetnam D. N. , Anderson J. D. , Borutzki S. E. , Campbell J. K. , Eshleman V. R. , Gresh D. L. , Gurrola E. M. , Hinson D. P. , Kawashima N. , Kursinski E. R. , Levy G. S. , Lindal G. F. , Lyons J. R. , Marouf E. A. , Rosen P. A. , Simpson R. A. , Wood G. E.
Published: October 2006

The Voyager 2 encounter with the Neptune system included radio science investigations of the masses and densities of Neptune and Triton, the low-order gravitational harmonics of Neptune, the vertical structures of the atmospheres and ionospheres of Neptune and Triton, the composition of the atmosphere of Neptune, and characteristics of ring material. Demanding experimental requirements were met successfully, and study of the large store of collected data has begun. The initial search of the data revealed no detectable effects of ring material with optical depth τ ≳ 0.01. Preliminary representative results include the following: 1.0243 × 10
26
and 2.141 × 10
22
kilograms for the masses of Neptune and Triton; 1640 and 2054 kilograms per cubic meter for their respective densities; 1355 ± 7 kilometers, provisionally, for the radius of Triton; and
J
2
= 3411 ± 10(×10
-6
) and
J
4
= -26
+12
-20
(× 10
-6
) for Neptune's gravity field (
J
2
and
J
4
are harmonic coefficients of the gravity field). The equatorial and polar radii of Neptune are 24,764 ± 20 and 24,340 ± 30 kllometers, respectively, at the 10
5
-pascal (1 bar) pressure level. Neptune's atmosphere was probed to a pressure level of about 5 × 10
5
pascals, and effects of a methane cloud region and probable ammonia absorption below the cloud are evident in the data. Results for the mixing ratios of helium and ammonia are still being investigated; the methane abundance below the clouds is at least 1 percent by volume. Derived temperature-pressure profiles to 1.2 × 10
5
pascals and 78 kelvins (K) show a lapse rate corresponding to "frozen" equilibrium of the para- and ortho-hydrogen states. Neptune's ionosphere exhibits an extended topside at a temperature of 950 ± 160 K if H
+
is the dominant ion, and narrow ionization layers of the type previously seen at the other three giant planets. Triton has a dense ionosphere with a peak electron concentration of 46 × 10
9
per cubic meter at an altitude of 340 kilometers measured during occultation egress. Its topside plasma temperature is about 80 ± 16 K if N
2
+
is the principal ion. The tenuous neutral atmosphere of Triton produced distinct signatures in the occultation data; however, the accuracy of the measurements is limited by uncertainties in the frequency of the spacecraft reference oscillator. Preliminary values for the surface pressure of 1.6 ± 0.3 pascals and an equivalent isothermal temperature of 48 ± 5 K are suggested, on the assumption that molecular nitrogen dominates the atmosphere. The radio data may be showing the effects of a thermal inversion near the surface; this and other evidence imply that the Triton atmosphere is controlled by vapor-pressure equilibrium with surface ices, at a temperature of 38 K and a methane mixing ratio of about 10
-4
.
Growth of Greenland Ice Sheet: Measurement
Authors: Zwally H. Jay , Bindschadler Robert A. , Brenner Anita C. , Major Judy A. , Marsh James G.
Published: October 2006

Measurements of ice-sheet elevation change by satellite altimetry show that the Greenland surface elevation south of 72° north latitude is increasing. The vertical velocity of the surface is 0.20 ± 0.06 meters per year from measured changes in surface elevations at 5906 intersections between Geosat paths in 1985 and Seasat in 1978, and 0.28 ± 0.02 meters per year from 256,694 intersections of Geosat paths during a 548-day period of 1985 to 1986.
Infection and Replication of HIV-1 in Purified Progenitor Cells of Normal Human Bone Marrow
Authors: Folks Thomas M. , Kessler Steven W. , Orenstein Jan M. , Justement Jesse S. , Jaffe Elaine S. , Fauci Anthony S.
Published: October 2006

Myeloid progenitor cells were highly purified from normal human bone marrow by positive immunoselection with high-affinity monoclonal antibodies linked to magnetic beads and were successfully infected in vitro with the human immunodeficiency virus type 1 (HIV-1). From 99 to 100 percent pure bone marrow cells expressing the CD34 phenotypic marker were obtained. These cells were devoid of mature myeloid or T cell surface and intracellular markers as analyzed by immunohistochemical staining and flow cytometry. HIV-1 particles were detected by supernatant reverse transcriptase activity and transmission electron microscopy 40 to 60 days after infection. Viral particles were predominantly observed assembling and accumulating from within intracellular membranes, while phenotypically the cells were observed to have differentiated into CD4
+
monocytes. These studies have important implications in understanding the pathogenesis of HIV-1 as well as the possible cause of certain of the observed hematologic abnormalities in HIV-1 infection. They also indicate that the bone marrow may serve as a potentially important reservoir of HIV-1 in the body.
Polymerase Chain Reaction with Single-Sided Specificity: Analysis of T Cell Receptor δ Chain
Authors: Loh Elwyn Y. , Elliott John F. , Cwirla Steve , Lanier Lewis L. , Davis Mark M.
Published: October 2006

In the polymerase chain reaction (PCR), two specific oligonucleotide primers are used to amplify the sequences between them. However, this technique is not suitable for amplifying genes that encode molecules where the 5′ portion of the sequences of interest is not known, such as the T cell receptor (TCR) or immunoglobulins. Because of this limitation, a novel technique, anchored polymerase chain reaction (A-PCR), was devised that requires sequence specificity only on the 3′ end of the target fragment. It was used to analyze TCR δ chain mRNA's from human peripheral blood γδ T cells. Most of these cells had a Vδ gene segment not previously described (V
δ
3), and the δ chain junctional sequences formed a discrete subpopulation compared with those previously reported.
Cloning and Expression of a
Xenopus
Embryonic Gap Junction Protein
Authors: Ebihara L. , Beyer E. C. , Swenson K. I. , Paul D. L. , Goodenough D. A.
Published: October 2006

Gap junctions in the early amphibian embryo may play a fundamental role in the regulation of differentiation by mediating the cell-to-cell transfer of chemical signals. A complementary DNA encoding a gap junction present in
Xenopus
oocytes and early embryos has now been cloned and sequenced. This protein sequence is homologous to the well-characterized gap junction structural proteins rat connexin32 and connexin43. RNA blot analysis of total
Xenopus
oocyte RNA showed hybridization to a single 1.6-kilobase band. This messenger RNA is abundant in oocytes, decreases to levels below the sensitivity of our assay by stage 15 (18 hours), and is not detectable in RNA from a number of adult organs. To confirm that the oocyte cDNA encodes a gap junction channel, the protein was over expressed in
Xenopus
oocytes by injection of RNA synthesized in vitro. Pairs of RNA-injected oocytes formed many more time- and voltage-sensitive cell-cell channels than water-injected pairs.
Solid-State Chemistry: a Rediscovered Chemical Frontier
Authors: DiSalvo Francis J.
Published: October 2006

Chemical bonding in solids is not completely understood, mainly because of the wide variation in the chemical properties of the elements. Many difficult challenges remain in predicting the composition, structure, and the properties of new materials. Consequently, the synthesis of novel solids is as much an art as a science. Discoveries of new compounds and structure types highlight the versatility that nature has allowed with the relatively small number of elements. This article explores the long-term challenges in solid-state chemistry and then focuses on efforts at Cornell to prepare new solids.
Transmembrane Channels Based on Tartaric Acid-Gramicidin A Hybrids
Authors: Stankovic Charles J. , Heinemann Stefan H. , Delfino Jose M. , Sigworth Frederick J. , Schreiber Stuart L
Published: October 2006

The gramicidin A transmembrane channel is believed to consist of two head-to-head β helices. Computer-generated models were used to formulate the structure of new single-chain channel molecules based on the gramicidin motif. The chemical synthesis of two tartaric acid-gramicidin A hybrids and single-channel analyses of their conducting properties are reported. These studies illustrate the rational design and synthesis of long-lived channels with tunable conductance properties and provide support for current molecular models of the natural (dimeric) gramicidin channel.
Human KGF is FGF-Related with Properties of a Paracrine Effector of Epithelial Cell Growth
Authors: Finch Paul W. , Rubin Jeffrey S. , Miki Toru , Ron Dina , Aaronson Stuart A.
Published: October 2006

Keratinocyte growth factor (KGF) is a human mitogen that is specific for epithelial cells. The complementary DNA sequence of KGF demonstrates that it is a member of the fibroblast growth factor family. The KGF transcript was present in stromal cells derived from epithelial tissues. By comparison with the expression of other epithelial cell mitogens, only KGF, among known human growth factors, has the properties of a stromal mediator of epithelial cell proliferation.
Phosphorus Uptake by Pigeon Pea and Its Role in Cropping Systems of the Indian Subcontinent
Authors: Ae Noriharu , Arihara Joji , Okada Kensuke , Yoshihara Teruhiko , Johansen Chris
Published: October 2006

Pigeon pea was shown to be more efficient at utilizing iron-bound phosphorus (Fe-P) than several other crop species. This ability is attributed to root exudates, in particular piscidic acid and its
p
-O-methyl derivative, which release phosphorus from Fe-P by chelating Fe
3+
. Pigeon pea is normally intercropped with cereals under low-input conditions in the Indian subcontinent. Although pigeon pea can utilize the relatively insoluble Fe-P, intercropped cereals must rely on the more soluble calcium-bound phosphorus. This finding suggests that cultivation of pigeon pea increases total phosphorus availability in cropping systems with low available phosphorus.
Regulatory Role for GTP-Binding Proteins in Endocytosis
Authors: Mayorga Luis S. , Diaz Ruben , Stahl Philip D.
Published: October 2006

Guanosine 5′-triphosphate (GTP)-binding proteins have been implicated in the transport of newly synthesized proteins along the secretory pathway of yeast and mammalian cells. Early vesicle fusion events that follow receptor-mediated endocytosis as measured by three in vitro assays were blocked by guanosine 5′-
O
-(3-thiotriphosphate) and aluminum fluoride. The effect was specific for guanosine nucleotides and depended on the presence of cytosolic factors. Thus, GTP-binding proteins may also have a role in the transport of molecules along the endocytic pathway.