In Drosophila, what is the role of the transformer (Tra) gene?
Promotes male development
Promotes female development
Determines the number of X chromosomes
Determines the number of autosomes
The Transformer (Tra) gene in Drosophila is responsible for promoting female development. It is involved in the regulation of sexual differentiation by controlling the splicing of the doublesex (dsx) pre-mRNA transcript. In females, the Tra protein is present, and it interacts with other proteins to promote the splicing of dsx into a female-specific isoform. This isoform then directs the development of female-specific structures and traits.
In contrast, in males, the absence of functional Tra protein results in the alternative splicing of dsx into a male-specific isoform. This male-specific isoform of dsx directs the development of male-specific structures and traits. Therefore, the presence or absence of functional Tra protein is critical in determining the sexual development and differentiation of Drosophila flies.
Option 2 is the correct answer.