Year

2011

Season

Fall

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

First Advisor

Dr. Judith D. Ochrietor

Second Advisor

Dr. Michael Lentz

Third Advisor

Dr. Cliff Ross

Department Chair

Dr. Courtney T. Hackney

College Dean

Dr. Barbara A. Hetrick

Abstract

Basigin gene products are cell adhesion molecules that are expressed by photoreceptor cells, Müller cells and endothelial cells of the mammalian retina. Previous studies have suggested that a lactate shuttle exists between the photoreceptor cells and the Müller cells, with Basigin being an essential component in this shuttle. Deletion of the Basigin gene in mice results in blindness with an eventual retinal degeneration. It was hypothesized that the lactate shuttle between photoreceptors and Müller cells does not form in Basigin null mice and that the blindness is attributed to faulty photoreceptor metabolism. Therefore, the purpose of this study was to determine whether the mitochondria of the Basigin null mice are metabolically active in the absence of the lactate shuttle. Mitochondrial health in the Basigin null mouse retina was assessed by a variety of assays, including ELISA analyses to measure Cytochrome c concentration and expression of autophagy-specific proteins. Mitotracker dyes were used to stain the mitochondria of Basigin null and normal retinas to determine the number of metabolically active mitochondria and the total number of mitochondria. The results showed that apoptosis and autophagy are not occurring in the Basigin null animals at a rate greater than that of the normal animals. The Mitotracker assay showed that there is a ~60% decrease in the total number of mitochondria in the null animals compared to their normal counterparts. A recalculation of the Cytochrome c assay in light of the reduced number of mitochondria in Basigin null mice revealed that apoptosis is likely occurring in these animals prior to the first signs of cytoarchitectural changes in the tissue. These results suggest that in the absence of the lactate shuttle in the Basigin null animals, the photoreceptors are unable to perform oxidative phosphorylation at the necessary rate, thus decreasing the number of mitochondria, which results in limited photoreceptor functionality, hence blindness.

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