Stage-specific expression profiling of Drosophila spermatogenesis suggests that meiotic sex chromosome inactivation drives genomic relocation of testis-expressed genes

PLoS Genet. 2009 Nov;5(11):e1000731. doi: 10.1371/journal.pgen.1000731. Epub 2009 Nov 20.

Abstract

In Drosophila, genes expressed in males tend to accumulate on autosomes and are underrepresented on the X chromosome. In particular, genes expressed in testis have been observed to frequently relocate from the X chromosome to the autosomes. The inactivation of X-linked genes during male meiosis (i.e., meiotic sex chromosome inactivation-MSCI) was first proposed to explain male sterility caused by X-autosomal translocation in Drosophila, and more recently it was suggested that MSCI might provide the conditions under which selection would favor the accumulation of testis-expressed genes on autosomes. In order to investigate the impact of MSCI on Drosophila testis-expressed genes, we performed a global gene expression analysis of the three major phases of D. melanogaster spermatogenesis: mitosis, meiosis, and post-meiosis. First, we found evidence supporting the existence of MSCI by comparing the expression levels of X- and autosome-linked genes, finding the former to be significantly reduced in meiosis. Second, we observed that the paucity of X-linked testis-expressed genes was restricted to those genes highly expressed in meiosis. Third, we found that autosomal genes relocated through retroposition from the X chromosome were more often highly expressed in meiosis in contrast to their X-linked parents. These results suggest MSCI as a general mechanism affecting the evolution of some testis-expressed genes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Drosophila melanogaster / cytology
  • Drosophila melanogaster / genetics*
  • Gene Expression Profiling
  • Gene Expression Regulation, Developmental*
  • Genes, Insect
  • Genes, X-Linked
  • Genome, Insect / genetics
  • Male
  • Meiosis / genetics*
  • Mitosis
  • Organ Specificity / genetics
  • Sex Chromosomes / genetics*
  • Spermatogenesis / genetics*
  • Testis / cytology
  • Testis / metabolism*
  • X Chromosome Inactivation / genetics*