123 research outputs found
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Sheep as a silvicultural tool in coastal Douglas-fir forest
The International Hill Land Symposium was held at Oregon State University in April 1983.A study was conducted during 1981 and 1982 to evaluate the feasibility of using herded sheep as a silvicultural tool to suppress brush in Douglas-fir plantations of Oregon's coastal mountains. Effects of sheep grazing on vegetation were studied by comparing plants grown on grazed with those on ungrazed portions of five clearcut plantations.
Parameters monitored included sheep live weight gains, utilization of vegetation by sheep, soil moisture, and growth of Douglas-fir trees.
Browsing of Douglas-fir trees by sheep was most intense in the spring, then declined to low levels by July. Douglas-fir trees apparently
benefited from the grazing treatment. Diameter increase of trees
growing in grazed plantations was 7 to 14 percent greater than that of ungrazed controls. Height of trees of the end of the year was not
affected by grazing. Grazing did reduce, however, the amount of brush present on the study clearcuts compared to ungrazed control areas. At the end of the 1982 growing season, current year growth of browse
plants on ungrazed areas was 18 percent to 186 percent less than that in ungrazed areas. Regrowth of herbaceous plants, however, was stimulated by grazing. Soil moisture values for spring-grazed plantations were lower in the upper 60 cm of soil, but higher below 60 cm depth
when compared to control areas
Water in Cavity−Ligand Recognition
We use explicit solvent molecular dynamics simulations to estimate free energy, enthalpy, and entropy changes along the cavity-ligand association coordinate for a set of seven model systems with varying physicochemical properties. Owing to the simplicity of the considered systems we can directly investigate the role of water thermodynamics in molecular recognition. A broad range of thermodynamic signatures is found in which water (rather than cavity or ligand) enthalpic or entropic contributions appear to drive cavity-ligand binding or rejection. The unprecedented, nanoscale picture of hydration thermodynamics can help the interpretation and design of protein-ligand binding experiments. Our study opens appealing perspectives to tackle the challenge of solvent entropy estimation in complex systems and for improving molecular simulation models
Analysis of Male Pheromones That Accelerate Female Reproductive Organ Development
Male odors can influence a female's reproductive physiology. In the mouse, the odor of male urine results in an early onset of female puberty. Several volatile and protein pheromones have previously been reported to each account for this bioactivity. Here we bioassay inbred BALB/cJ females to study pheromone-accelerated uterine growth, a developmental hallmark of puberty. We evaluate the response of wild-type and mutant mice lacking a specialized sensory transduction channel, TrpC2, and find TrpC2 function to be necessary for pheromone-mediated uterine growth. We analyze the relative effectiveness of pheromones previously identified to accelerate puberty through direct bioassay and find none to significantly accelerate uterine growth in BALB/cJ females. Complementary to this analysis, we have devised a strategy of partial purification of the uterine growth bioactivity from male urine and applied it to purify bioactivity from three different laboratory strains. The biochemical characteristics of the active fraction of all three strains are inconsistent with that of previously known pheromones. When directly analyzed, we are unable to detect previously known pheromones in urine fractions that generate uterine growth. Our analysis indicates that pheromones emitted by males to advance female puberty remain to be identified
Bone Marrow Transplantation Results in Human Donor Blood Cells Acquiring and Displaying Mouse Recipient Class I MHC and CD45 Antigens on Their Surface
Background: Mouse models of human disease are invaluable for determining the differentiation ability and functional capacity of stem cells. The best example is bone marrow transplants for studies of hematopoietic stem cells. For organ studies, the interpretation of the data can be difficult as transdifferentiation, cell fusion or surface antigen transfer (trogocytosis) can be misinterpreted as differentiation. These events have not been investigated in hematopoietic stem cell transplant models. Methodology/Principal Findings: In this study we investigated fusion and trogocytosis involving blood cells during bone marrow transplantation using a xenograft model. We report that using a standard SCID repopulating assay almost 100 % of the human donor cells appear as hybrid blood cells containing both mouse and human surface antigens. Conclusion/Significance: Hybrid cells are not the result of cell-cell fusion events but appear to be due to efficient surface antigen transfer, a process referred to as trogocytosis. Antigen transfer appears to be non-random and includes all donor cells regardless of sub-type. We also demonstrate that irradiation preconditioning enhances the frequency of hybrid cell
Management practices for control of ragwort species
The ragwort species common or tansy ragwort (Jacobaea vulgaris, formerly Senecio jacobaea), marsh ragwort (S. aquaticus), Oxford ragwort (S. squalidus) and hoary ragwort (S. erucifolius) are native in Europe, but invaded North America, Australia and New Zealand as weeds. The abundance of ragwort species is increasing in west-and central Europe. Ragwort species contain different groups of secondary plant compounds defending them against generalist herbivores, contributing to their success as weeds. They are mainly known for containing pyrrolizidine alkaloids, which are toxic to grazing cattle and other livestock causing considerable losses to agricultural revenue. Consequently, control of ragwort is obligatory by law in the UK, Ireland and Australia. Commonly used management practices to control ragwort include mechanical removal, grazing, pasture management, biological control and chemical control. In this review the biology of ragwort species is shortly described and the different management practices are discussed
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A Simple Disc Meter for Measurement of Pasture Height and Forage Bulk
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
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