A whole transcriptomal linkage analysis of gene co-regulation in insecticide resistant house flies, Musca domestica

To gain valuable insights into the gene interaction and complex regulation involved in the development of insecticide resistance, the first reference transcriptome from the adult house fly was generated and a whole transcriptome analysis was conducted for the multiple insecticide resistant strain ALHF (wild-type) and two insecticide susceptible strains: aabys (with morphological recessive markers) and CS (wild type) of house flies, Musca domestica. A total of 1316 genes were identified as being co-up-regulated in ALHF in comparison to both aabys and CS. The majority of these up-regulated genes fell within the SCOP categories of metabolism, general, intra-cellular processes, and regulation, and covered three key SCOP detailed function categories: redox detailed function category in metabolism, signal transduction and kinases/phosphatases in regulation, and proteases in intra-cellular processes. The redox detailed function group contained supergene families for detoxification, including multiple cytochrome P450s, glutathione S-transferases, and esterases. The signal transduction and kinases/phosphatases detailed function groups contained gene families including 7 transmembrane receptors (rhodopsin-like GPCR family), adenylate and guanylate cyclases, protein kinases and phosphates. The proteases detailed function group contained genes with digestive, catalytic, and proteinase activities. Genetic linkage analysis with house fly lines comparing different autosomal combinations from ALHF revealed that the up-regulation of gene expression in the three key SCOP detailed function categories occurred mainly through the co-regulation of factors among multiple autosomes, especially between autosomes 2 and 5, suggesting that signaling transduction cascades controlled by GPCRs, protein kinase/phosphates and proteases may be involved in the regulation of resistance P450 gene expression.