Dopamine-stimulated dephosphorylation of connexin 36 mediates AII amacrine cell uncoupling.

Gap junction proteins form the substrate for electrical coupling between neurons. These electrical synapses are widespread in the CNS and serve a variety of important functions. In the retina, connexin 36 (Cx36) gap junctions couple AII amacrine cells and are a requisite component of the high-sensitivity rod photoreceptor pathway. AII amacrine cell coupling strength is dynamically regulated by background light intensity, and uncoupling is thought to be mediated by dopamine signaling via D(1)-like receptors. One proposed mechanism for this uncoupling involves dopamine-stimulated phosphorylation of Cx36 at regulatory sites, mediated by protein kinase A. Here we provide evidence against this hypothesis and demonstrate a direct relationship between Cx36 phosphorylation and AII amacrine cell coupling strength. Dopamine receptor-driven uncoupling of the AII network results from protein kinase A activation of protein phosphatase 2A and subsequent dephosphorylation of Cx36. Protein phosphatase 1 activity negatively regulates this pathway. We also find that Cx36 gap junctions can exist in widely different phosphorylation states within a single neuron, implying that coupling is controlled at the level of individual gap junctions by locally assembled signaling complexes. This kind of synapse-by-synapse plasticity allows for precise control of neuronal coupling, as well as cell-type-specific responses dependent on the identity of the signaling complexes assembled

A High Efficiency PSOFC/ATS-Gas Turbine Power System

A study is described in which the conceptual design of a hybrid power system integrating a pressurized Siemens Westinghouse solid oxide fuel cell generator and the Mercury{trademark} 50 gas turbine was developed. The Mercury{trademark} 50 was designed by Solar Turbines as part of the US. Department of Energy Advanced Turbine Systems program. The focus of the study was to develop the hybrid power system concept that principally would exhibit an attractively-low cost of electricity (COE). The inherently-high efficiency of the hybrid cycle contributes directly to achieving this objective, and by employing the efficient, power-intensive Mercury{trademark} 50, with its relatively-low installed cost, the higher-cost SOFC generator can be optimally sized such that the minimum-COE objective is achieved. The system cycle is described, major system components are specified, the system installed cost and COE are estimated, and the physical arrangement of the major system components is discussed. Estimates of system power output, efficiency, and emissions at the system design point are also presented. In addition, two bottoming cycle options are described, and estimates of their effects on overall-system performance, cost, and COE are provided

Cow-Calf Response to Stocking Rates and Grazing Systems on Native Range

Studies of grazing management for cow-calf operations on native range have been conducted on the Texas Experimental Ranch since 1960. Three stocking rates and three grazing systems were evaluated. Calf production was greater from the deferred-rotation grazing systems than from continuous grazing at the same stocking rate. Heavier stocking rates reduced calf production per animal unit slightly, but production per acre increased significantly. The net returns per animal unit were greatest from the Merrill system, stocked at a moderate rate, and the net returns per acre were greatest from heavy continuous stocking. The optimum stocking rate for this range appeared to be between 40 and 50 animal units per section and it was profitable to use the Merrill grazing system./Se llevó a cabo un estudio en el rancho experimental de Texas cerca de Throckmorton, Texas, E.U.A., comprendiendo un período de diez años. Los tratamientos fueron: pastoreo todo el año a tres diferentes cargas de animales: pesado (12.8 acres por vaca), moderado (20.8 acres por vaca), ligero (28.4 acres por vaca) y dos diferentes sistemas de pastoreo con rotación a la carga moderada. La producción de becerras por vaca fué mas alta para los sistemas de pastoreo con rotación que para el pastoreo por todo el año a la misma carga moderada. La producción por vaca fué menor en el tratamiento de pastoreo todo el año a la carga pesada pero la producción por acre fué mayor que en todos los otros tratamientos. También el ingreso neto por acre. El ingreso neto por vaca fué mayor en el cuarto potrero rotación llamado Sistema de Merrill. El coeficiente de agostadero óptimo fué entre 12.5 y 15 acres por unidad animal.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Influence of Rootplowing and Seeding on Composition and Forage Production of Native Grasses

Effects of rootplowing, with or without seeding, on forage production and composition of native grasses were determined on a deep upland range site. Percent composition of stoloniferous species, particularly buffalograss, was reduced initially and after 6 growing seasons by the rootplowing treatments. Frequency counts indicated a reduction of Texas wintergrass on rootplowed plots (seeded and nonseeded) compared to an undisturbed, native check area. This reduction the first growing season was attributed to the competitive effect of sorghum almum introduced in the seeding mixture. Unsuccessful establishment of other seeded grasses (sideoats grama and switchgrass) appeared to be related to poor seedbed preparation, competition from sorghum almum plants, and below normal rainfall immediately after seeding. Rootplowing decreased grass production. After 6 growing seasons, significantly less forage per acre was produced on rootplowed-seeded plots than on nonrootplowed plots. Differences in forage production were related to plant composition and density. /// El estudio fué empezado en el año de 1964 en el rancho experimental de Texas en el Municipio de Throckmorton; el diseño incluyó testigo; y se pasó arado para desenraizar sin la siembra y se pasó arado para desenraizar con la siembra. Después de 6 años los dos tratamientos disminuyeron la producción de forraje y composición de zacates deseables. El zacate sorghum almum (Sorghum almum) apareció en la siembra. El arado desenraizador controló el mezquite (Prosopis glandulosa var. glandulosa).This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Effect of Range Condition and Utilization on Nutritive Intake of Sheep on Summer Ranges

Total protein, ash, lignin, and other carbohydrates were somewhat higher in forage from poor ranges while ether extract, cellulose, and gross energy were slightly higher in forage from good ranges. The digestibilities of cellulose, other carbohydrates, and gross energy in forage from both good and poor ranges decreased with heavier utilization.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Cow-Calf Response to Stocking Rates, Grazing Systems, and Winter Supplementation at the Texas Experimental Ranch

Cow-calf performance from 1960 through 1978 was contrasted between three grazing treatments at the Texas Experimental Ranch. Grazing treatments were yearlong continuous stocked at annual rates averaging 5.1 and 7.6 ha/cow and a 4-pasture, 3-herd deferred rotation system stocked at an annual rate averaging 7.2 ha/cow. Averaged across three weighing periods, cows in the deferred rotation treatment averaged 447 kg while weight of cows in the heavily and moderately stocked continuous treatments averaged 427 and 438 kg, respectively. Calf weaning weights averaged 204, 212, and 217 kg for the heavy continuous, moderate continuous, and Merrill rotation treatments, respectively. Production-/cow averaged 182, 189, and 202 kg while production/ha averaged 35.9, 25.2, and 27.8 kg, respectively, for the heavy continuous, moderate continuous, and deferred rotation treatments. Cows fed winter supplement were significantly heavier in early spring and summer than nonsupplemented cows with no significant differences in weights by late summer. Supplemented cows weaned calves averaging 214 kg as compared to 208 kg for calves weaned from nonsupplemented cows. Winter supplementation significantly increased production in the heavily stocked treatment but not in either of the moderately stocked treatments. Numerous statistically significant interactions accompanied the significant main effects, and the biological significance of each was examined.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Range Site and Grazing System Influence Regrowth after Spraying Honey Mesquite

Honey mesquite (Prosopis glandulosa Torr. var. glandulosa) regrowth on the Texas Experimental Ranch in the Rolling Plains of northwest Texas was evaluated 8 years after aerial spraying with 2,4,5-T. Regrowth on rocky hill, rolling hill, and deep upland range sites was measured under two systems of grazing management: heavily stocked (4.86 ha/AU), continuous grazing; and, moderately stocked (6.48 ha/AU), deferred-rotation grazing. Canopy cover, density, and topgrowth production of honey mesquite regrowth were significantly greater under moderate, deferred-rotation grazing than under heavy, continuous grazing of the deep upland site. Honey mesquite density, canopy cover, and topgrowth production did not differ between grazing systems on the rocky hill site. Regrowth on the rolling hill site was usually intermediate between the rocky hill and deep upland sites. Honey mesquite plant density, topgrowth production, canopy cover, and rate of new stem initiation were greater under moderately stocked, deferred-rotation than heavily stocked, continuous grazing. Averaged across grazing systems, regrowth, regardless of variable evaluated, was greatest on the deep upland site.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Livestock Production and Economic Returns from Grazing Treatments on the Texas Experimental Ranch.

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