Masters Theses

Date of Award

12-1991

Degree Type

Thesis

Degree Name

Master of Science

Major

Life Sciences

Major Professor

Ranjan Ganguly

Committee Members

Beth Mullin, Daniel Roberts

Abstract

This study describes the molecular characterization of a genomic clone 549, which was isolated from Drosophila melanogaster based on its greater hybridization with RNA isolated from the head of the adult fly but not with that isolated from the body. The head of the fly is composed mostly of neural tissues, i.e. the brain and the large compound eye. Thus, the possibility that the clone 549 contained a gene(s) which is expressed predominantly within the nervous system of the fly was considered very high. The present study demonstrates that:

1. The clone 549 contains a single copy gene which produces 2.9, 1.9, and 1.0 kb RNAs;

2. While the 2.9 kb RNA is head-specific, the 1.0 kb RNA is predominantly expressed in the ovary. On the other hand, the 1.9 kb RNA is expressed in all tissues and at all stages of development and shows peak expression during late embryogenesis. These results suggest that the expression of these RNAs is under tissue-specific and developmental regulation;

3. These RNAs are predominantly expressed in the nervous system of the fly, but also appear to be expressed at lower levels in other tissues.

4. A 1.3 kb cDNA complementary to clone 549 and all three RNA species encodes a protein similar to the 14-3-3 proteins of mammals, which have been shown to be involved in the regulation of tyrosine hydroxylase and tryptophan hydroxylase activity. These are the key enzymes regulating the biosynthesis of biogenic monoamine neurotransmitters, such as dopamine and serotonin, in the brain. The deduced amino acid sequence of the Drosophila protein is 72-78% identical and 84-88% similar to previously sequenced bovine 14-3-3 protein isoforms. The Drosophila protein also possesses a nearly identical calculated isoelectric point and molecular weight as the bovine 14-3-3 proteins. Based on the above observation, the polypeptide encoded by the 1.3 kb 549 cDNA has been named Drosophila 14-3-3, or D14-3-3. Accordingly, the gene present within clone 549 has been named the D14-3-3 gene. In future studies, the mechanism(s) by which the three RNAs are produced from the D14-3-3 locus and the function of D14-3-3 protein in Drosophila should be resolved.

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