The link between dosage compensation and sex differentiation in Drosophila melanogaster

Publisher Website
Google Scholar
Abstract
The rate of 3H-uridine incorporation into X-chromosome and autosomal RNA was measured as an indicator of relative transcription activity in larvae carrying various Sxl mutant alleles. Hyperactivity of X chromosomes was found in heteroallelic Sxl f#1/Sxlfhv#1 and homozygous Sxl f#2 female larvae. Sxl fhv#1 homozygotes, Sxl f#1/Sxl+ heterozygotes, heteroallelic Sxl f#2/Sxlf#2 as well as homozygous Sxl f#ba female larvae exhibited normal X chromosome transcription. Except for Sxl f#ba, there is a correlation between the viability of the mutants and the degree to which X-chromosome activity is elevated. Male larvae carrying the dominant male-specific lethal mutation Sxl M#1 displayed X chromosomes only half as wide as those of control larvae. However, it could not be determined whether this property is the result of a lower transcription rate or of underreplication of the mutated X chromosomes. The results demonstrate that the Sxl gene plays an important role in controlling X-chromosome activity. The relationship among the various genes known to act in sex differentiation and dosage compensation is discussed.