Courtship and copulation behaviors in Drosophila melanogaster males are
regulated by sex-specific products from the gene fruitless (fru). Male-specific FRU
proteins (FRU[superscript M]) are putative transcription factors of the BTB-ZnF family that likely
act by controlling development and maintenance of the neural circuitry used during
male sexual behavior. However, which neuronal characteristics are regulated by
FRU[superscript M] is mostly unknown and how FRU[superscript M] neurons are grouped into circuits and the
role that specific neuronal circuits play in sexual behavior has not been elucidated. I
have identified a subset of FRU[superscript M] neurons that co-express the transcription factor,
Engrailed (En). After fru[superscript M]-RNAi-induced targeted removal of FRU[superscript M] proteins from
FRU[superscript M]/En neurons, males were impaired in their ability to initiate or maintain
copulation. Further, I examined two characteristics, the initial projections and
neurotransmitters used by FRU[superscript M]/En neurons. Males and females showed a difference
in the neurochemistry of FRU[superscript M]/En neurons in the thoracic ganglia; this
neurochemistry is disrupted in fru mutant males.
For one cohort of serotonergic neurons in the abdominal ganglion that were
previously shown to be dependent on FRU[superscript M] for expression of serotonin, I determined
that FRU[superscript M] works in conjunction with other sex-specific genes, TAKEOUT (TO) and
DOUBLESEX (DSX), to induce of serotonin expression in males; in females
serotonin expression is repressed by DSX and TO.
Finally, I performed a genetic screen for genes that interact with, or are
downstream targets of, fru, dsx, or dissatisfaction (dsf). I assessed fertility, copulation
success, and abdominal muscle development of EMS-mutagenized flies, resulting in
one fly line in which homozygous mutant animals had a novel muscle phenotype. By
genetic tests, the mutation was found to be allelic to string, which encodes a Cdc25-
like phosphatase.
Taken together, my research demonstrates that subsets of FRU[superscript M] neurons
function in circumscribed circuits to regulate specific portions of sexual behavior, and
that FRU[superscript M], along with other sex-specific genes, controls development of these
neurons in part by determining neurochemistry. Further, FRU[superscript M] likely directs multiple
downstream targets, in different subsets of neurons in which it is expressed, which
collectively provide correct development of neural circuits underlying courtship and
copulation behavior. / Graduation date: 2006
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28943 |
| Date | 09 June 2005 |
| Creators | Latham, Kristin Lynn |
| Contributors | Taylor, Barbara J. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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