Effects of the maleless mutation on X and autosomal gene expression in Drosophila melanogaster.
The mutational effect of the maleless (mle) gene in Drosophila has been reexamined. Earlier work had suggested that mle along with other male-lethal genes was responsible for hypertranscription of the X chromosome in males to bring about dosage compensation. Prompted by studies on dosage sensitive regulatory genes, we tested for effects of mlets on the phenotypes of 16 X or autosomal mutations in adult escapers of lethality. In third instar larvae, prior to the major lethal phase of mle, we examined activities of 6 X or autosomally encoded enzymes, steady state mRNA levels of 15 X-linked or autosomal genes and transcripts from two large genomic segments derived from either the X or from chromosome 2 and present in yeast artificial chromosomes. In contrast to the previously hypothesized role, we detected pronounced effects of mle on the expression of both X-linked and autosomal loci such that a large proportion of the tested genes were increased in expression, while only two X-linked loci were reduced. The most prevalent consequence was an increase of autosomal gene expression, which can explain previously observed reduced X:autosome transcription ratios. These observations suggest that if mle plays a role in the discrimination of the X and the autosomes, it may do so by modification of the effects of dosage sensitive regulatory genes.
Hiebert
J C
JC
Biological Laboratories, Harvard University, Cambridge, Massachusetts 02138.
Birchler
J A
JA
D000818:Animals; D005075:Biological Evolution; D004303:Dosage Compensation, Genetic; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000235:genetics* / Q000378:metabolism; D005127:Eye Color / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D017344:Genes, Insect; D005804:Genes, Lethal; D006720:Homozygote; D007814:Larva / Q000378:metabolism; D008297:Male; D009154:Mutation; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014921:Wings, Animal / Q000033:anatomy & histology; D014960:X Chromosome
D012333:RNA, Messenger