title: Fine-scale analysis of X chromosome inactivation in the male germ line of Drosophila melanogaster.
abstract: Inactivation of the X chromosome in the male germ line has been suggested to contribute to the excess of gene movement off the X chromosome and the paucity of X-linked male-biased genes that have been observed in Drosophila species. Recent experimental work has demonstrated the transcriptional inactivation of the X chromosome during spermatogenesis, but it is not known if some regions of the X escape inactivation. To test this, we analyzed the expression of 112 precisely-mapped, testis-specific reporter gene insertions along the X chromosome. All of the reporter gene insertions showed low levels of expression that were significantly less than those of autosomal insertions, suggesting that the X chromosome is globally inactivated in the male germ line. There was no evidence for regions of the X chromosome escaping inactivation, including cytological region 19, which appears to be a hot spot for newly evolved, testis-expressed genes.
authors.affiliation: Department of Biology II, University of Munich (LMU), Munich, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Kemkemer
authors.forename: Winfried
authors.initials: W
authors.lastname: Hense
authors.forename: John
authors.initials: J
authors.lastname: Parsch
mesh_terms: D000818:Animals; D015536:Down-Regulation; D004331:Drosophila melanogaster / Q000235:genetics*; D057075:Enzyme Assays; D005260:Female; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D008297:Male; D013091:Spermatogenesis / Q000235:genetics; D013094:Spermatozoa / Q000378:metabolism*; D049951:X Chromosome Inactivation; D001616:beta-Galactosidase / Q000096:biosynthesis
chemical_list: D001616:beta-Galactosidase