What best describes the outcome of the DSX protein function in female Drosophila?

The outcome of the DSX protein function in female Drosophila is best described as repressing male gene expression. DSX, or Doublesex protein, is a key factor in the sexual differentiation pathway of Drosophila. In females, the DSX protein is produced from the female-specific splice isoform of the dsx gene. This isoform functions to promote the expression of female-specific traits and inhibits the expression of male-specific traits.

The mechanism by which DSX represses male gene expression involves targeting male-promoting genes and silencing them, ensuring that female development occurs without interference from male characteristics. This selective repression is crucial for the proper sexual differentiation and development of female Drosophila, resulting in the expression of genes necessary for female anatomy and behavior, while concurrently suppressing those that would lead to male phenotypes.

Understanding DSX's role elucidates how the interplay of various proteins and genetic regulation results in the distinct sexual characteristics observed in Drosophila, marking it as a foundational concept in developmental biology and sex differentiation.