Lepidoptera's pheromonal communication, so sensitive and specific, constitutes a model of choice to study the molecular basis of olfactory reception. The strong specificity of this system is thought to be ensured in the antennae by the intervention of a diversity of genes implicated in the olfactory chemoreception. The silkworm, Bombyx mori, is a particularly interesting species for studying olfaction in insects: male's response to the pheromone is well known, this species is amenable to genetic manipulations and genomic sequences are available on the Internet. In my PhD work, I have identified and characterized at the molecular level a diversity of olfactory genes by bioinformatic analysis of the genome and molecular biology tools. The expression patterns of these genes have been established in order to check for a possible chemosensory function. Some of them (BmPBP2, BmPBP3, BmAOX2) could encode proteins specifically involved in pheromonal reception whereas others (BmAOX1, BmSNMP2) could also act in the reception of less specific molecules. By their combinatorial and sequential actions in signal recognition, these proteins from different families would ensure specific recognition across the different steps of peripheral olfactory reception. I have also participated in the development of a new in vivo functional analysis tool in B. mori, based on the expression of OR by transgenesis. This system has been tested with a male-specific pheromone receptor, BmOR1. Females from transgenic lines strongly expressed the receptor in their antennae, but were unable to respond to the pheromonal compound (Bol) during electrophysiological recordings. Future use of a new promotor, more specific to olfactory neurons, pOR2, could allow the development of the first stable in vivo functional analysis tool in a lepidoptera.
