Date of Award
Master of Arts (MA)
Dr. Bruce Chase
The intersex gene (2-60.5) lies at the terminus of the regulatory pathway that determines sex-type in Drosophila. Its product functions with the female-specific product of doublesex, another gene in the self-determination regulatory pathway, to regulate female-specific differentiation. However, the mechanism of this regulation has not been clearly demonstrated. Using a temperature-sensitive allele at intersex to eliminate its function at time points both during development and in the adult stage, the mode by which intersex regulates female determination was addressed. When chromosomal females bearing a temperature-sensitive intersex allele are raised at a permissive temperature, they develop as phenotypic females. Animals raised at a restrictive temperature also develop as normal females. In contrast, animals kept at a restrictive temperature past the mid-pupal stage, or animals raised at a permissive temperature and then shifted to a restrictive temperature before the mid-pupal stage develop as sterile females. Therefore, the fertility to be retained, intersex function must be present at least until the mid-pupal stage. To determine if the function of intersex is also required in the adult to maintain the female differentiated state, as well as to address its mode of action, intersex function was eliminated in the adult female. To this end, diplo-X females bearing a temperature-sensitive intersex allele were place at a restrictive temperature as adults and used to analyze whether intersex exerts transcriptional control over the female-specific expression of the yolk protein gene, yp1. Even after placing animals bearing the temperature-sensitive allele at a restrictive temperature for up to twenty days, yp1 transcription persisted at levels equivalent to sibling controls having normal intersex function. These data suggest that intersex does not function to positively regulate female-specific gene expression, but does not rule out that intersex functions to repress male-type gene expression in females.
Risley, Robert Russel, "The mode of action of intersex in terminal sexual differentiation in Drosophila." (1993). Student Work. 3344.