Date of Award
Spring 1994
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Biological Sciences
First Advisor
Kumaran, Krishna A.
Second Advisor
Bergtrom, Gerald
Third Advisor
Courtright, James B.
Abstract
To study the regulation of sex-specific gene expression during oogenesis, a vitellogenic ovariole cDNA library was constructed and differentially screened with ovary and male pharate pupal total cDNAs. Six classes of ovary specific clones were isolated. Clones, F11, F20 and N23 represent 1.1, 2.0 and 2.3 kb ovary specific transcripts. In situ hybridization and developmental Northern analysis showed that F11 and F20 transcripts are limited to vitellogenic follicle cells. N23 transcripts are present in the pre-vitellogenic and vitellogenic nurse cells, and they persist in choriogenic follicles and early embryos suggesting that N23 may represent a maternal message. The 0.95 kb and 1.6 kb cDNAs of F11 and F20, bear a single open reading frame and code for peptides of 286 and 504 amino acids, respectively. The 952 bp F11 cDNA, appears to contain the entire coding region including a translation initiation codon (4-6), a stop codon (862-864) and the poly A+ signal sequence (935-941). The deduced amino acids 18 to 28, of the F11 matched Galleria YP4 yolk polypeptide N-terminal amino acid sequence. The deduced amino acid sequence of F20 shows overall identity of 42% to B. mori egg specific protein (ESP) and has a lipid binding domain (aa 271 to 281) found in mammalian lipases, B. mori ESP (aa 322-332) and Drosophila yolk proteins (YP1- aa 248-257). F20 has also a serine rich domain that can be phosphorylated and four potential N-glycosylation sites. These observations suggest that F20 may represent the follicle specific yolk polypeptide-YP2 gene. Genomic Southern and PCR analyses suggest that yp4 is a single copy gene without introns while F20 probably has introns and belongs to a small gene family. F20 and YP4 are not expressed following in vitro culture but are expressed in ovaries transplanted into male larval hosts, suggesting that the developmental expression of the follicle specific yolk protein genes may depend on the interaction of the ovary with other pharate adult tissues.