783 research outputs found

    Annual Production of Creek Chub and Southern Redbelly Dace in a Small Woodland Stream

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    Author Institution: Illinois Natural History Survey Laboratory and Department of Biology, Lakehead UniversityThe annual production of the creek chub, Semotilus atromaculatus, and southern redbelly dace, Phoxinus erytbrogaster, was measured in a small headwater stream in southeastern Ohio. Creek chub annual production was 13.60 g • m~2 per yr, and P/B was 1.16. Dace annual production was 2.77 g • m~2 and P/B was 1.82. Even though the stream was acidic (pH 6.3) and infertile, fish production compared favorably with that of small alkaline streams. Considerable production within allochthonous food chains probably overrides the effects of low in-stream fertility

    Movements of the Creek Chub in a Small Ohio Stream

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    Author Institution: Illinois Natural Survey Laboratory ; Lake Head UniversityCreek chub movements were monitored in a small stream in the spring and summer of 1972 to determine the magnitude of seasonal changes in distribution. A large percentage of the adult chubs moved upstream between late April and mid-May, but distances traveled by individuals were generally less than 300 m. Immature chubs moved upstream throughout the spring and summer, the catch being predominantly 2 and 3 year old fish in May and early June, and 1 and 2 year old fish in late June and July. Upstream movement of all but young-of-the-year chubs greatly exceeded downstream movement. Some young-of-the-year fish drifted downstream passively. Large population shifts, associated with the exodus of fish from 2 beaver ponds, had implications for estimation of population size, mortality and other population parameters

    Hsp27 anti-sense oligonucleotides sensitize the microtubular cytoskeleton of Chinese hamster ovary cells grown at low pH to 42 degrees C-induced reorganization

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    Chinese hamster ovary (CHO) cells maintained in vitro at pH 6.7 were used to model cells in the acidic environment of tumours. CHO cells grown at pH 6.7 develop thermotolerance during 42 degrees C heating at pH 6.7 and their cytoskeletal systems are resistant to 42 degrees C-induced perinuclear collapse. Hsp27 levels are elevated in cells grown at pH 6.7 and are further induced during 42 degrees C heating, while Hsp70 levels remain low or undetectable, suggesting that Hsp27 is responsible for some of the novel characteristics of these cells. An anti-sense oligonucleotide strategy was used to test the importance of Hsp27 by lowering heat-induced levels of the protein. The response of the microtubular cytoskeleton to heat was used as an endpoint to assess the effectiveness of the anti-sense strategy. Treatment with anti-sense oligonucleotides prevented the heat-induced increase of Hsp27 levels measured immediately following heat. Treatment with anti-sense oligonucleotides also sensitized the cytoskeleton of cells grown at low pH to heat-induced perinuclear collapse. However, cytoskeletal collapse was not evident in cells grown at pH 6.7 and treated with 4-nt mismatch oligonucleotides or in control cells maintained and heated at pH 6.7. The cytoskeleton collapsed around the nucleus in cells cultured and heated at pH 7.3. These results confirm that over-expression of Hsp27 confers heat protection to the microtubular cytoskeleton in CHO cells grown at low pH

    Structural and optical quality of GaN grown on Sc2O3/Y2O3/Si(111)

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    Thick (∼900 nm) GaN layers were grown by molecular beam epitaxy on cost-effective Sc2O3/Y2O3/Si(111) substrates and characterized by x-ray diffraction and photoluminescence. Samples grown in Ga-rich condition show superior structural and optical quality with reduced density of cubic GaN inclusions within the hexagonal matrix and a relatively strong photoluminescence emission at 3.45 eV at 10 K. Cubic inclusions are formed in the initial growth stage and their concentration is reduced with increasing film thickness and after rapid thermal annealing

    New mutations at the imprinted Gnas cluster show gene dosage effects of Gsα in postnatal growth and implicate XLαs in bone and fat metabolism, but not in suckling

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    The imprinted Gnas cluster is involved in obesity, energy metabolism, feeding behavior, and viability. Relative contribution of paternally expressed proteins XLαs, XLN1, and ALEX or a double dose of maternally expressed Gsα to phenotype has not been established. In this study, we have generated two new mutants (Ex1A-T-CON and Ex1A-T) at the Gnas cluster. Paternal inheritance of Ex1A-T-CON leads to loss of imprinting of Gsα, resulting in preweaning growth retardation followed by catch-up growth. Paternal inheritance of Ex1A-T leads to loss of imprinting of Gsα and loss of expression of XLαs and XLN1. These mice have severe preweaning growth retardation and incomplete catch-up growth. They are fully viable probably because suckling is unimpaired, unlike mutants in which the expression of all the known paternally expressed Gnasxl proteins (XLαs, XLN1 and ALEX) is compromised. We suggest that loss of ALEX is most likely responsible for the suckling defects previously observed. In adults, paternal inheritance of Ex1A-T results in an increased metabolic rate and reductions in fat mass, leptin, and bone mineral density attributable to loss of XLαs. This is, to our knowledge, the first report describing a role for XLαs in bone metabolism. We propose that XLαs is involved in the regulation of bone and adipocyte metabolism

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    Learning to Reach after Learning to Look: a Study of Autonomy in Learning Sensorimotor Transformations

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    Light Microsopy Module, International Space Station Premier Automated Microscope

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    The Light Microscopy Module (LMM) was launched to the International Space Station (ISS) in 2009 and began science operations in 2010. It continues to support Physical and Biological scientific research on ISS. During 2015, if all goes as planned, five experiments will be completed: [1] Advanced Colloids Experiments with a manual sample base -3 (ACE-M-3), [2] the Advanced Colloids Experiment with a Heated Base -1 (ACE-H-1), [3] (ACE-H-2), [4] the Advanced Plant Experiment -03 (APEX-03), and [5] the Microchannel Diffusion Experiment (MDE). Preliminary results, along with an overview of present and future LMM capabilities will be presented; this includes details on the planned data imaging processing and storage system, along with the confocal upgrade to the core microscope. [1] New York University: Paul Chaikin, Andrew Hollingsworth, and Stefano Sacanna, [2] University of Pennsylvania: Arjun Yodh and Matthew Gratale, [3] a consortium of universities from the State of Kentucky working through the Experimental Program to Stimulate Competitive Research (EPSCoR): Stuart Williams, Gerold Willing, Hemali Rathnayake, et al., [4] from the University of Florida and CASIS: Anna-Lisa Paul and Rob Ferl, and [5] from the Methodist Hospital Research Institute from CASIS: Alessandro Grattoni and Giancarlo Canavese
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