title: Genetic variation for expression of the sex determination pathway genes in Drosophila melanogaster.
abstract: Sequence polymorphisms result in phenotypic variation through the pathways of interacting genes and their products. We focused on transcript-level variation in the splicing pathway for sex determination - a model network defining downstream morphological characters that are dimorphic between males and females. Expression of Sex lethal, transformer, transformer2, doublesex, intersex and hermaphrodite was assayed with quantitative RT-PCR in 0- to 1-day-old adult males and females of 36 Drosophila melanogaster inbred lines. Abundant genetic variation in the transcript levels was found for all genes. Sex-specific splices had high concentrations in the appropriate sex. In the other sex, low but detectable concentrations were also observed. Abundances of splices strongly co-varied between sexes among genotypes, with little genetic variation strictly limited to one sex. The level of sexually dimorphic Yolk protein1 expression - an immediate downstream target of the pathway - was modelled as the target phenotype of the upstream sex determination pathway. Substantial genetic variation in this phenotype in males was explained by leaky splicing of female-specific transcripts. If higher transcript levels of the appropriate isoform of sex determination genes are beneficial in a sex, then stronger leakiness of the inappropriate transcript might be deleterious, perhaps contributing to the fitness trade-offs previously observed between the sexes.
authors.affiliation: Evolution and Ecology, University of California at Davis, CA 95616, USA.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Tarone
authors.forename: Yaseen M
authors.initials: YM
authors.lastname: Nasser
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Nuzhdin
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000235:genetics; D029721:Drosophila Proteins / Q000096:biosynthesis / Q000235:genetics; D004331:Drosophila melanogaster / Q000235:genetics*; D005260:Female; D017344:Genes, Insect; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D008297:Male; D008954:Models, Biological; D009687:Nuclear Proteins / Q000235:genetics; D011110:Polymorphism, Genetic; D012313:RNA / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012261:Ribonucleoproteins / Q000235:genetics; D012727:Sex Characteristics; D019849:Sex Determination Processes; D012737:Sex Factors; D014157:Transcription Factors / Q000235:genetics; D014819:Vitellogenins / Q000096:biosynthesis / Q000235:genetics
chemical_list: D017931:DNA Primers; D004268:DNA-Binding Proteins; C070369:DSX protein, Drosophila; D029721:Drosophila Proteins; C468125:IX protein, Drosophila; D009687:Nuclear Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C067777:Sxl protein, Drosophila; C097162:Tra protein, Drosophila; D014157:Transcription Factors; D014819:Vitellogenins; C105973:YP1 protein, Drosophila; C507971:her protein, Drosophila; C066174:tra2 protein, Drosophila; D012313:RNA