WETLAND OCCUPANCY OF POND-BREEDING AMPHIBIANS IN YOSEMITE NATIONAL PARK, USA

We estimated wetland occupancy and population trends for three species of pond-breeding anurans in Yosemite National Park from 2007 – 2011. We used a double survey technique in which two observers independently surveyed each site on the same day. Double surveys allowed us to calculate detectability for the three most common anurans within the park: Rana sierrae, Anaxyrus canorus, and Pseudacris regilla. Annual estimates of detectability were generally high; mean detectability ranged from 73.7% + 0.6 (SE) for any life history stage of A. canorus to 86.7% + 0.7 for sites with P. regilla reproduction (eggs or larvae present). Detectability was most variable for Anaxyrus canorus, which ranged from 45.9% to 99.7%. The probability of occupancy for R. sierrae was highest in larger, low-elevation wetlands that lacked fish. Anaxyrus canorus were more common in shallow high-elevation ponds; their occurrence was minimally impacted by the presence of fish. Finally, occurrence of P. regilla was largely unrelated to wetland size and elevation, but like R. sierrae, they were less likely to occupy sites with fish. Occupancy showed no trend over the five years of our study for R. sierrae or A. canorus when considering either sites with any life stage or only sites with reproduction. However, P. regilla showed a modest downward trend for sites with any life stage and sites with reproduction. Our results for R. sierrae run counter to expectations given recent concern about the decline of this species, while our findings for P. regilla raise concerns for this widespread and generally common species

Habitat Use by Different Size Classes of Bowhead Whales in the Central Beaufort Sea during Late Summer and Autumn

The frequency distributions of bowhead whale (Balaena mysticetus) size classes were studied as functions of year, location, water depth, and date. Whales were classified by size and status as calves, small subadults (non-calves < 10 m); large subadults (10–13 m); and adults (> 13 m). Adults include mothers with calves, which were also counted separately. During mid-August to early October of 1982, 1984–86, and 1998–2000, calibrated vertical photography was used to obtain known-scale images of 901 different whales in waters up to 200 m deep between Flaxman and Herschel islands (146? to 139? W) in the central Beaufort Sea. Age composition of the whales photographed over all years of our study was calves 6.2%, small subadults 31.4%, large subadults 33.3%, and adults 29.1%. We found proportionally more subadults and fewer adults than are estimated to be in the overall population, and this result was found both before and after making allowance for reduced effort to obtain photographs early and late in the migration period. Thus parts of the central Beaufort Sea up to 200 m deep appear to be more heavily used by subadult bowheads than by adults in most years. Significant interannual variation existed in length-frequency distributions of whales among years, geographic subdivisions of the study area, water depth categories, and time periods. This variation was due to variable use of the study area by each size class in different years, differences in the water depths used by different size classes, and different migration timing by each size class. In all years, small subadult whales were the dominant group in shallow (< 20 m) nearshore habitats, and the size of the whales increased with increasing water depth. Timing of movements into and through the study area were also related to size class: small subadults arrived first in late August and departed in late September, and adults arrived last in late September. Mothers and calves arrived in early September and were common until at least early October.La répartition des fréquences de la baleine boréale (Balaena mysticetus) en fonction des classes de dimensions a été étudiée à la lumière de critères tels que l’année, l’emplacement, la profondeur de l’eau et la date. Les baleines étaient classées d’après leurs dimensions et leur état, comme suit : baleineaux, petites baleines immatures (non-baleineaux < 10 m); grosses baleines immatures (10–13 m); et baleines adultes (> 13 m). Les adultes comprenaient les mères avec leurs baleineaux, qui étaient aussi comptés séparément. De la mi-août au début octobre 1982, 1984 à 1986 et 1998 à 2000, nous nous sommes servi de photographies verticales calibrées pour obtenir des images d’échelle connue de 901 baleines différentes dans des eaux pouvant atteindre une profondeur de 200 m entre les îles Flaxman et Herschel (146? à 139?O), dans le centre de la mer de Beaufort. La composition par âge des baleines photographiées au cours de toutes les années visées par l’étude s’établissait comme suit : 6,2 % de baleineaux, 31,4 % de petites baleines immatures, 33,3 % de grosses baleines immatures et 29,1 % de baleines adultes. De manière proportionnelle, nous avons repéré plus de baleines immatures et moins de baleines adultes comparativement aux estimations de telles baleines au sein de la population générale, résultat qui a été trouvé tant avant qu’après avoir tenu compte de l’effort réduit pour obtenir des photographies vers le début et vers la fin de la période de migration. Par conséquent, certaines parties du centre de la mer de Beaufort où l’eau atteint une profondeur allant jusqu’à 200 m semblent plus utilisées par les baleines boréales immatures que par les baleines adultes pendant la plupart des années. Par ailleurs, il existait une variation interannuelle importante sur le plan de la répartition des fréquences de longueur des baleines en fonction des années, des subdivisions géographiques de la région à l’étude, des catégories de profondeur de l’eau et des périodes. Cette variation était attribuable à l’utilisation variable de la région visée par l’étude par chaque classe de dimension au cours des différentes années, aux différences de profondeur de l’eau utilisée par les différentes classes de dimension ainsi qu’aux périodes de migration différentes de chaque classe de dimension. Dans le cas de toutes les années, les petites baleines immatures dominaient les habitats peu profonds (< 20 m) en zone côtière, et la taille des baleines augmentait en fonction de la profondeur de l’eau. Le moment des déplacements vers la région à l’étude et dans celle-ci dépendait également de la classe de dimension : les petites baleines immatures arrivaient en premier, vers la fin août et repartaient vers la fin septembre, tandis que les baleines adultes arrivaient en dernier, vers la fin septembre. Les mères et leurs baleineaux arrivaient au début septembre et y restaient au moins jusqu’au début octobre

VMAT2-Deficient Mice Display Nigral and Extranigral Pathology and Motor and Nonmotor Symptoms of Parkinson's Disease

Dopamine is transported into synaptic vesicles by the vesicular monoamine transporter (VMAT2; SLC18A2). Disruption of dopamine storage has been hypothesized to damage the dopamine neurons that are lost in Parkinson's disease. By disrupting vesicular storage of dopamine and other monoamines, we have created a progressive mouse model of PD that exhibits catecholamine neuron loss in the substantia nigra pars compacta and locus coeruleus and motor and nonmotor symptoms. With a 95% reduction in VMAT2 expression, VMAT2-deficient animals have decreased motor function, progressive deficits in olfactory discrimination, shorter latency to behavioral signs of sleep, delayed gastric emptying, anxiety-like behaviors at younger ages, and a progressive depressive-like phenotype. Pathologically, the VMAT2-deficient mice display progressive neurodegeneration in the substantia nigra (SNpc), locus coeruleus (LC), and dorsal raphe (DR) coupled with α-synuclein accumulation. Taken together, these studies demonstrate that reduced vesicular storage of monoamines and the resulting disruption of the cytosolic environment may play a role in the pathogenesis of parkinsonian symptoms and neurodegeneration. The multisystem nature of the VMAT2-deficient mice may be useful in developing therapeutic strategies that go beyond the dopamine system

COMPLEMENT-DEPENDENT RELEASE OF IMMUNE COMPLEXES FROM THE LYMPHOCYTE MEMBRANE

Soluble antigen-antibody-complement complexes bound to mouse B lymphocytes are rapidly released from the cell membrane in the presence of normal serum from several mammalian species. The release is not the result of antigen-antibody dissociation or extensive degradation of the complexes. However, the released complexes have been altered because they will no longer bind to fresh lymphocytes. The release is not the result of lymphocyte damage mediated by complement. It is complement-dependent, and is generated either preferentially or exclusively via the alternate pathway, since it occurs in C4-deficient serum, is Mg++ but not Ca++ dependent, and requires C3 proactivator. C3 inactivator is not involved. The release activity of the serum, once generated, is unstable at 37°C. The release of complexes from the lymphocyte membrane by serum provides a convenient assay for the functioning of the alternate pathway in the mouse and in other species

Individual Cas Phosphorylation Sites Are Dispensable for Processive Phosphorylation by Src and Anchorage-independent Cell Growth

Cas is a multidomain signaling protein that resides in focal adhesions. Cas possesses a large central substrate domain containing 15 repeats of the sequence YXXP, which are phosphorylated by Src. The phosphorylation sites are essential for the roles of Cas in cell migration and in regulation of the actin cytoskeleton. We showed previously that Src catalyzes the multisite phosphorylation of Cas via a processive mechanism. In this study, we created mutant forms of Cas to identify the determinants for processive phosphorylation. Mutants containing single or multiple YXXP mutations were phosphorylated processively by Src, suggesting that individual sites are dispensable. The results also suggest that there is no defined order to the Cas phosphorylation events. We also studied the effects of these mutations by reintroducing Cas into Cas-deficient fibroblasts. Mutants lacking some or all YXXP sites augment the ability of Src to promote anchorage-independent growth. On the other hand, deletion of YXXP sites compromises the ability of Cas to promote tumor cell migration

Magnetohydrodynamics dynamical relaxation of coronal magnetic fields. I. Parallel untwisted magnetic fields in 2D

Context. For the last thirty years, most of the studies on the relaxation of stressed magnetic fields in the solar environment have onlyconsidered the Lorentz force, neglecting plasma contributions, and therefore, limiting every equilibrium to that of a force-free field. Aims. Here we begin a study of the non-resistive evolution of finite beta plasmas and their relaxation to magnetohydrostatic states, where magnetic forces are balanced by plasma-pressure gradients, by using a simple 2D scenario involving a hydromagnetic disturbance to a uniform magnetic field. The final equilibrium state is predicted as a function of the initial disturbances, with aims to demonstrate what happens to the plasma during the relaxation process and to see what effects it has on the final equilibrium state. Methods. A set of numerical experiments are run using a full MHD code, with the relaxation driven by magnetoacoustic waves damped by viscous effects. The numerical results are compared with analytical calculations made within the linear regime, in which the whole process must remain adiabatic. Particular attention is paid to the thermodynamic behaviour of the plasma during the relaxation. Results. The analytical predictions for the final non force-free equilibrium depend only on the initial perturbations and the total pressure of the system. It is found that these predictions hold surprisingly well even for amplitudes of the perturbation far outside the linear regime. Conclusions. Including the effects of a finite plasma beta in relaxation experiments leads to significant differences from the force-free case

Wavelength and Temperature-Dependent Apparent Quantum Yields for Photochemical Formation of Hydrogen Peroxide in Seawater

Wavelength and temperature-dependent apparent quantum yields (AQYs) were determined for the photochemical production of hydrogen peroxide using seawater obtained from coastal and oligotrophic stations in Antarctica, the Pacific Ocean at Station ALOHA, the Gulf of Mexico, and at several sites along the East Coast of the United States. For all samples, AQYs decreased exponentially with increasing wavelength at 25 °C, ranging from 4.6 × 10−4 to 10.4 × 10−4 at 290 nm to 0.17 × 10−4 to 0.97 × 10−4 at 400 nm. AQYs for different seawater samples were remarkably similar irrespective of expected differences in the composition and concentrations of metals and dissolved organic matter (DOM) and in prior light exposure histories; wavelength-dependent AQYs for individual seawater samples differed by less than a factor of two relative to respective mean AQYs. Temperature-dependent AQYs increased between 0 and 35 °C on average by a factor of 1.8 per 10 °C, consistent with a thermal reaction (e.g., superoxide dismutation) controlling H2O2 photochemical production rates in seawater. Taken together, these results suggest that the observed poleward decrease in H2O2photochemical production rates is mainly due to corresponding poleward decreases in irradiance and temperature and not spatial variations in the composition and concentrations of DOM or metals. Hydrogen peroxide photoproduction AQYs and production rates were not constant and not independent of the photon exposure as has been implicitly assumed in many published studies. Therefore, care should be taken when comparing and interpreting published H2O2AQY or photochemical production rate results. Modeled depth-integrated H2O2 photochemical production rates were in excellent agreement with measured rates obtained from in situ free-floating drifter experiments conducted during a Gulf of Maine cruise, with differences (ca. 10%) well within measurement and modeling uncertainties. Results from this study provide a comprehensive data set of wavelength and temperature-dependent AQYs to model and remotely sense hydrogen peroxide photochemical production rates globally

Investigation of Hygro-Thermal Aging on Carbon/Epoxy Materials for Jet Engine Fan Sections

This poster summarizes 2 years of aging on E862 epoxy and E862 epoxy with triaxial braided T700s carbon fiber composite. Several test methods were used to characterize chemical, physical, and mechanical properties of both the resin and composite materials. The aging cycle that was used included varying temperature and humidity exposure. The goal was to evaluate the environmental effects on a potential jet engine fan section material. Some changes were noted in the resin which resulted in increased brittleness, though this did not significantly affect the tensile and impact test results. A potential decrease in compression strength requires additional investigation