title: Sexual Dimorphism of Body Size Is Controlled by Dosage of theX-Chromosomal GeneMycand by the Sex-Determining GenetrainDrosophila.
abstract: Drosophilafemales are larger than males. In this article, we describe howX-chromosome dosage drives sexual dimorphism of body size through two means: first, through unbalanced expression of a keyX-linked growth-regulating gene, and second, through female-specific activation of the sex-determination pathway.X-chromosome dosage determines phenotypic sex by regulating the genes of the sex-determining pathway. In the presence of two sets ofX-chromosome signal elements (XSEs),Sex-lethal(Sxl) is activated in female (XX) but not male (XY) animals. Sxl activatestransformer(tra), a gene that encodes a splicing factor essential for female-specific development. It has previously been shown that null mutations in thetragene result in only a partial reduction of body size ofXXanimals, which shows that other factors must contribute to size determination. We tested whetherXdosage directly affects animal size by analyzing males with duplications ofX-chromosomal segments. Upon tiling across theXchromosome, we found four duplications that increase male size by >9%. Within these, we identified several genes that promote growth as a result of duplication. Only one of these,Myc, was found not to be dosage compensated. Together, our results indicate that bothMycdosage andtraexpression play crucial roles in determining sex-specific size inDrosophilalarvae and adult tissue. SinceMycalso acts as an XSE that contributes totraactivation in early development, a double dose ofMycin females serves at least twice in development to promote sexual size dimorphism.
authors.affiliation: Institute of Molecular Life Sciences, University of Zurich, 8057, Switzerland kristina.mathews@uzh.ch.
authors.forename: Kristina Wehr
authors.identifier: 0000-0002-3655-1088
authors.initials: KW
authors.lastname: Mathews
authors.affiliation: Institute of Molecular Life Sciences, University of Zurich, 8057, Switzerland.
authors.forename: Margrith
authors.initials: M
authors.lastname: Cavegn
authors.affiliation: Institute of Molecular Life Sciences, University of Zurich, 8057, Switzerland.
authors.forename: Monica
authors.initials: M
authors.lastname: Zwicky
mesh_terms: D000818:Animals; D049628:Body Size / Q000235:genetics*; D059006:Chromosomes, Insect / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004303:Dosage Compensation, Genetic; D004330:Drosophila / Q000235:genetics* / Q000254:growth & development; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D020440:Gene Duplication; D008297:Male; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012727:Sex Characteristics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014960:X Chromosome / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C102284:Myc protein, Drosophila; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; C067777:Sxl protein, Drosophila; C097162:Tra protein, Drosophila; D014157:Transcription Factors
keywords: Drosophila melanogaster; Myc; dosage compensation; sexual dimorphism; tra