Lewis Honors College Capstone Collection

Year of Publication



Arts and Sciences



Degree Name

B.S. in Biology

First Capstone/Thesis Advisor

Dr. Rebecca Kellum


The master switch of the sexual differentiation and dosage compensation pathway in Drosophila is the sex lethal gene, Sxl. The early promoter, SxlPe, is activated in females, resulting in female-specific splicing of later transcripts (notably the late Sxl transcript SxlPm), while inactive in males. Chromatin immunoprecipitation (ChIP) assays have previously shown association of two conventionally heterochromatin-localized proteins, HOAP and HP1, at SxlPe, and in situ hybridization as well as RT-PCR assays have confirmed a repressive role for HOAP and both repressive and activating roles for HP1. The mechanism for the activity shift of HP1 is currently unknown. Deletions in the region of Rapgap1 yielded a similar phenotype to that of HP1 mutants, suggesting a potential role in the regulation of its activity. Attempted PCR characterization of the deletion spans in the studied mutant strains, Rapgap122 and Rapgap147, was unclear, leading to the redesign of chosen oligonucleotide primer pairs and protocol. Future analyses will include genetic crosses between Rapgap1 and HP1 mutants and RT-PCR assays to observe Rapgap1 interactions with HP1 and Sxl.