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The growth and development of muscle and fat cells

by Fernyhough, Melinda.

Abstract (Summary)
by Melinda Fernyhough, Ph.D. Washington State University May 2006 Chair: Michael V. Dodson Twelve compounds commonly touted as having ergogenic properties were tested on ovine satellite cells for their ability to elicit satellite cell activity (proliferation and/or differentiation) in vitro. The compounds were tested at levels ranging from pharmocologic to physiologic. None of the compounds tested were able to induce satellite cell proliferation (P < 0.05) or differentiation (P < 0.05) under the cell culture system. Purified cultures of adipofibroblasts, derived from the dedifferentiation of bovine adipocytes, were used to evaluate their “plasticity” and redifferentiative ability in vitro. Adipofibroblasts proliferated and overgrew the culture dishes when exposed to fetal bovine serum-containing medium, but demonstrated protracted adipogenesis when exposed to horse serum-containing medium. Protracted adipogenesis was evident through the adipofibroblast accumulation of cytoplasmic vesicles that first appeared 5 d after a uniform monolayer was established and remained for up to 60 d in vitro. These vesicles demonstrated little/no lipid incorporation despite positive immunocytochemistry staining, immunoblot, and isolation of mRNA for peroxisome proliferator activated receptor ?. The cytoplasmic vesicles did not possess glycogen, and lipid uptake was not enhanced by the addition of insulin, lipid, induction iv medium, or thiazolidinedione to the serum-containing medium. Examination of the ultrastructure of cytoplasmic vesicles with transmission electron microscopy revealed a discrete structure with a monophosphate layer, and immunofluorescence demonstrated the lipiddroplet protein perilipin surrounding the vesicle. Collectively, these data suggest that mature adipocytes dedifferentiate to form proliferative-competent progeny cells, that dedifferentiated adipofibroblasts retain their adipocyte lineage characteristics and possess the ability to undergo in vitro adipogenesis without complicated induction procedures or through the use of exogenous chemicals, and that the adipofibroblasts do not experience in vitro transformation. The protracted nature of cellular conversion from adipofibroblasts to adipocytes may now be exploited in studies to determine the cellular/molecular regulation of adipogenesis or progressive regulation of lipid metabolism. v
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School:Washington State University

School Location:USA - Washington

Source Type:Master's Thesis

Keywords:satellite cells

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