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The Effect of Different Timber Harvesting Techniques on Plethadontid Salamander Populations.  

Science.gov (United States)

This investigation will explore the effect that current timber extraction techniques have on plethadontid salamander populations in ... group selection, and two-age harvest. Broad scale timber extraction can d...

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Biodiversity of Costa Rican salamanders: Implications of high levels of genetic differentiation and phylogeographic structure for species formation  

UK PubMed Central (United Kingdom)

Although salamanders are characteristic amphibians in Holarctic temperate habitats, in tropical regions they have diversified evolutionarily only in tropical America. An adaptive radiation centered...Full Text Available

2000-02-15

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Transduction noise induced by 4-hydroxy retinals in rod photoreceptors.  

UK PubMed Central (United Kingdom)

New visual pigments were formed with 4-hydroxy retinals in isolated vertebrate rod photoreceptors by exposing bleached rods from the tiger salamander, Ambystoma tigrinum, to lipid vesicles containing...Full Text Available

1990-01-01

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Mechanisms mediating the trophic effect of nerves during vertebrate limb regeneration  

Energy Technology Data Exchange (ETDEWEB)

Salamanders regenerate their appendages after amputation and nerves are required for this process. Experiments were designed to test the idea that one way nerves could affect blastema cell proliferation is by influencing the metabolism of extracellular matrix (ECM) components and to identify neurotrophic factors which promote blastema cell mitosis. Temporal and spatial differences of glycosaminoglycans (GAGs) synthesis is innervated and denervated limbs were examined. Hyaluronic acid (HA) was found to be the major GAG produced during the proliferative period and chondroitin sulfate during differentiation. Denervation reduced synthesis of both these components by half. Dorsal root ganglia and fibroblast growth factor (FGF), a brain-derived mitogen, similarly doubled GAG synthesis in cultured blastemas, the FGF-effect being primarily on HA production. Histochemical and autoradiographical results confirmed the biochemical data. Autoradiography of the limb tissue ...

1986-01-01