The remodeling of the central nervous system (CNS) during metamorphosis in
Drosophila melanogaster is a prime model system in which to study the genetic control
of the sexual dimorphisms in the abdominal ganglion of the CNS. I have been using a
P[tau-lacZ] enhancer trap line, 4.078, to label a segmentally repeated subset of abdominal
motorneurons in order to assess the function of the sex determination hierarchy in
controlling sex-specific development of the adult nervous system. In both the male and
female larva there are 8 sets of these labeled abdominal motorneurons but only six sets in
males and five sets in females survive in the adult. When this P[tau-lacZ] reporter
construct is placed into a doublesex (dsx) mutant background, all 8 sets of these labeled
abdominal motorneurons survive in both male and female adults. These results strongly
suggest that dsx plays a role in the sex-specific survival of larval neurons that have
functions in the adult.
During the construction of mutant strains containing the sex determining genes
transformer (tra) and transformer-2 (tra2), a genetic interactor was discovered in the
P[tau-lacZ] 4.078 line. Female flies heterozygous for either tra or tra-2 alleles and the
P[tau-lacZ] 4.078 developed with masculinized external and internal sex-specific
structures. The external sex-specific structures, such as the genitalia, and ventral muscles
are dependent on dsx gene function and a dorsal sex-specific muscle is dependent on
fruitless (fru) gene function. From standard genetic crosses, I have characterized and
demonstrated that the genetic interaction is linked to the P-element insertion site, which
maps to the 85-87 region on the right arm of the third chromosome. By genetic analysis,
this new genetic interactor appears to interfere with the tra and tra2 regulated female specific
functions of both dsx and fru, potentially by reducing the female-specific splicing
of the primary transcripts of the genes dsx and fru. To test the possibility that this newly
described genetic interactor was allelic to a known gene, B52, that maps to the same region of the chromosome and alters dsx splicing, complementation tests were conducted which showed that the P[tau-lacZ] is not allelic B52. Additional phenotypes were observed in the crosses that first detected the interaction, suggesting that this newly described locus may affect other gene functions as well. Among the phenotypes observed were XX intersexes, male-female gynandromorphs (XX//XO mosaics), and non-disjunction events evident as XO males and XXY females. This new locus may represent a new member of the family of genes that influence regulated splicing events. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33315 |
| Date | 24 July 1998 |
| Creators | Larsen, DeLaine D. |
| Contributors | Taylor, Barbara J. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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