Sex-biased expression in heads of three Drosophila species

Investigation of sex-biased expression across species have relied on measurements from whole flies which sample the extensive expression differences found in the germline and gonads of females and males. We wanted to examine genes with sex-biased expression in a somatic tissue to analyze patterns of genes with sex-biased expression in the context of a tissue more phenotypically similar between females and males. We used a Nimblegen microarray designed for Drosophila melanogaster and two custom micoarrays designed for D. pseudoobscura and D. mojavensis to survey gene expression differences in heads of females and males. PolyA+ mRNA was isolated in quadruplicate from dissected heads of 8 day old adult females and males. Female and male mRNA were labeled with Cy3 or Cy5 dyes separately and co-hybridized to species-specific microarrays. We analyzed a total of 24 channels of data.