Pheromones, genes & transcriptomes. A molecular analysis of moth sex pheromone production

Sammanfattning: Female moths emit sex pheromones to lure a mate. In this thesis I examined the transcriptomes of female moth pheromone glands in order to identify genes encoding proteins involved in pheromone production. Two cDNA-libraries were constructed from Agrotis segetum (Noctuidae) pheromone glands and the remaining body tissue, respectively. The libraries were sampled and sequenced. A total of 707 unigenes was identified. One third of the unigenes were exclusively found in the gland library. Transcripts more abundantly found in the pheromone gland and with a putative function in pheromone biosynthesis, included homologs of the following genes: a ?11-desaturase, a G-protein subunit, a chemosensory protein and a juvenile hormone binding protein. The unigene set identified in A. segetum was used to construct a cDNA microarray. Differential gene expression in the A. segetum pheromone gland versus the remaining body tissue was studied by comparative hybridization of RNA-derived cDNA targets from the two tissues. Of the gene reporters, 65% were differentially expressed in the pheromone gland compared to the body tissue, with approximately half of these reporters expressed at higher levels in the respective tissue. The highest gene expression levels in the pheromone gland were detected for a ?11-desaturase homolog and an antennal binding protein homolog. The up-regulation of several chemosensory proteins and proteins involved in juvenile hormone interactions in the pheromone glands is also reported. Agrotis ipsilon is closely related to A. segetum. The two species have different pheromone blends but some pheromone components are in common. A cross-species hybridization experiment was performed between A. ipsilon and A. segetum pheromone glands on the microarray platform derived from A. segetum. We identified transcriptional differences in the two species that could account for the differences in pheromone blends. Candidates for the pheromone differences included two different reductases that were expressed more highly in the respective species. Desaturase-encoding transcripts of the primitive moth Lampronia capitella (Incurvariodea, Prodoxidae) were characterized and functionally expressed in yeast. A ?11-desaturase, that arose from a gene duplication event, is present and most likely responsible for the conjugated diene pheromone of L. capitella. The presence of an active ?11-desaturase in the pheromone gland of this primitive species implies that the gene duplication took place before the split of the ditrysian