Butterflies have a unique sex determination system called "complementary sex determination," where the sex of an individual is determined by the interaction of two genes, master doublesex (mds) and doublesex (dsx).
In their study, published in the journal Nature Genetics, researchers from the University of Cambridge used genetic mapping and functional studies to identify the genomic elements that regulate mds expression. They found that the sex determination locus in butterflies is located in a specific region of the Z chromosome, which is one of the two sex chromosomes in butterflies.
The researchers identified a male-specific enhancer in the Z chromosome that drives the expression of mds, which in turn triggers the development of male structures. This enhancer contains several binding sites for the transcription factor Deadpan (Dpn), which is essential for male sex development in butterflies.
The study also revealed that the female-specific splicing of dsx is controlled by a sequence polymorphism located in the 5' untranslated region of the dsx gene. This polymorphism creates a splicing site that is specific to females, resulting in the production of female-specific transcripts of dsx.
These findings provide a detailed understanding of the genetic mechanism of sex determination in butterflies and uncover the evolutionary link between sex chromosomes and sex determination genes in different insect groups.
