NMDA receptor losses in putamen from patients with Huntington's disease

N-Methyl-D-aspartate (NMDA), phencyclidine (PCP), and quisqualate receptor binding were compared to benzodiazepine, gamma-aminobutyric acid (GABA), and muscarinic cholinergic receptor binding in the putamen and cerebral cortex of individuals with Huntington's disease (HD). NMDA receptor binding was reduced by 93 percent in putamen from HD brains compared to binding in normal brains. Quisqualate and PCP receptor binding were reduced by 67 percent, and the binding to other receptors was reduced by 55 percent or less. Binding to these receptors in the cerebral cortex was unchanged in HD brains. The results support the hypothesis that NMDA receptor-mediated neurotoxicity plays a role in the pathophysiology of Huntington's disease.     

Thermal structure of the venus atmosphere in the middle cloud layer

Thermal structure measurements obtained by the two VEGA balloons show the Venus middle cloud layer to be generally adiabatic. Temperatures measured by the two balloons at locations roughly symmetric about the equator differed by about 6.5 kelvins at a given pressure. The VEGA-2 temperatures were about 2.5 kelvins cooler and those of VEGA-1 about 4 kelvins warmer than temperatures measured by the Pioneer Venus Large Probe at these levels. Data taken by the VEGA-2 lander as it passed through the middle cloud agreed with those of the VEGA-2 balloon. Study of individual frames of the balloon data suggests the presence of multiple discrete air masses that are internally adiabatic but lie on slightly different adiabats. These adiabats, for a given balloon, can differ in temperature by as much as 1 kelvin at a given pressure.     

The magnetic memory of Titan's ionized atmosphere

After 3 years and 31 close flybys of Titan by the Cassini Orbiter, Titan was finally observed in the shocked solar wind, outside of Saturn's magnetosphere. These observations revealed that Titan's flow-induced magnetosphere was populated by "fossil" fields originating from Saturn, to which the satellite was exposed before its excursion through the magnetopause. In addition, strong magnetic shear observed at the edge of Titan's induced magnetosphere suggests that reconnection may have been involved in the replacement of the fossil fields by the interplanetary magnetic field.     

Implications of the VEGA Balloon Results for Venus Atmospheric Dynamics

Both VEGA balloons encountered vertical winds with typical velocities of 1 to 2 meters per second. These values are consistent with those estimated from mixing length theory of thermal convection. However, small-scale temperature fluctuations for each balloon were sometimes larger than predicted. The approximate 6.5-kelvin difference in temperature consistently seen between VEGA-1 and VEGA-2 is probably due to synoptic or planetary-scale nonaxisymmetric disturbances that propagate westward with respect to the planet. There is also evidence from Doppler data for the existence of solar-fixed nonaxisymmetric motions that may be thermal tides. Surface topography may influence atmospheric motions experienced by the VEGA-2 balloon.     

Overview of VEGA Venus Balloon in Situ Meteorological Measurements

The VEGA balloons made in situ measurements of pressure, temperature, vertical wind velocity, ambient light, frequency of lightning, and cloud particle backscatter. Both balloons encountered highly variable atmospheric conditions, with periods of intense vertical winds occurring sporadically throughout their flights. Downward winds as large as 3.5 meters per second occasionally forced the balloons to descend as much as 2.5 kilometers below their equilibrium float altitudes. Large variations, in pressure, temperature, ambient light level, and cloud particle backscatter (VEGA-1 only) correlated well during these excursions, indicating that these properties were strong functions of altitude in those parts of the middle cloud layer sampled by the balloons.     

Biogeography and ecological setting of Indian Ocean hydrothermal vents

Within the endemic invertebrate faunas of hydrothermal vents, five biogeographic provinces are recognized. Invertebrates at two Indian Ocean vent fields (Kairei and Edmond) belong to a sixth province, despite ecological settings and invertebrate-bacterial symbioses similar to those of both western Pacific and Atlantic vents. Most organisms found at these Indian Ocean vent fields have evolutionary affinities with western Pacific vent faunas, but a shrimp that ecologically dominates Indian Ocean vents closely resembles its Mid-Atlantic counterpart. These findings contribute to a global assessment of the biogeography of chemosynthetic faunas and indicate that the Indian Ocean vent community follows asymmetric assembly rules biased toward Pacific evolutionary alliances.     

Yeast RNA polymerase II genes: isolation with antibody probes

Genes encoding yeast RNA polymerase II subunits were cloned. Efficient isolation of these genes was accomplished by probing a phage lambda gt11 recombinant DNA expression library with polyvalent antibodies directed against purified yeast RNA polymerase II. The identity of genes that specify the largest RNA polymerase II subunits, the 220,000- and 150,000-dalton polypeptides, was confirmed by competitive radioimmune assay. Both of these genes exist in single copy in the yeast Saccharomyces cerevisiae.     

Modeling connectivity of black bears in a desert sky island archipelago

Landscape features such as rivers, mountains, desert basins, roads, and impermeable man-made structures may influence dispersal and gene flow among populations, thereby creating spatial structure across the landscape. In the US–Mexico borderland, urbanization and construction of the border fence have the potential to increase genetic subdivision and vulnerability to isolation in large mammal populations by bisecting movement corridors that have enabled dispersal between adjacent Sky Island mountain ranges. We examined genetic variation in black bears (Ursus americanus) from three regions in central and southern Arizona, US, to assess genetic and landscape connectivity in the US–Mexico border Sky Islands. We found that the three regions grouped into two subpopulations: the east-central subpopulation comprised of individuals sampled in the central highland and high desert regions, and the border subpopulation comprised of individuals sampled in the southern Sky Islands. Occupancy for the border subpopulation of black bears was influenced by cover type and distance to water, and occupancy-based corridor models identified 14 potential corridors connecting border Sky Island habitat cores with the east-central subpopulation. Biological quality of corridors, defined as length:width ratio and proportions of suitable habitat within corridors, declined with Sky Island dispersion. Our results show that black bears in the border subpopulation are moderately isolated from the east-central subpopulation, the main population segment of black bears in Arizona, and that connectivity for border bears may be vulnerable to anthropogenic activities, such as those associated with urbanization and trans-border security.