| dc.description.abstract | Sex determination in Drosophila melanogaster depends on the X chromosome number. Embryos with two dose of X chromosomes develop into females while embryos with one dose of X develop into males. Four X-linked signal elements (XSEs), sisterless A (sisA), scute (sc), unpaired (upd) and runt are responsible of conveying X dose to master regulatory gene, Sex-lethal (Sxl). As a result, two dose of X can activate the female specific establishment promotor, SxlPe, and set up an autoregulatory loop that maintain the continuous production of SXL while one dose of X lead to no Sxl activity and default male development. Hence, it is of great importance to understand how XSEs regulate Sxl activity.
The mechanism of how sisA, a strong XSE, regulate SxlPe activity is not known. Predicted to be a bZip transcription factor, SisA protein is believed to heterodimerize with a dimerization partner. To find out the potential partners, I generated transgenic flies carrying tagged-sisA constructs, which allow purification of SisA and pull down of SisA and potential partners from embryonic nuclear extracts using high-affinity antibodies against the tags. However, mass spectrometry revealed no candidates of significant abundance. Possible reasons and alternative approaches are discussed in this thesis. Meanwhile, transgenic flies carrying tagged-sc constructs were generated with similar approach to search for any protein interactors apart from Da that are involved in Sc’s regulation of Sxl activity and genetic tests were performed on transgene lines carrying Zelda binding site mutations to better understand the role of Zelda in regulation of Sxl. | en |
