In insect olfactory receptor neurons, rapid and transient increases in inositol triphosphate (IP3) and Ca2+ are detected upon stimulation with pheromone or nonpheromonal odorants. This suggests that heterotrimeric guanine nucleotide binding proteins (G proteins) may transduce some odorant responses in insects. We obtained cDNA clones encoding three classes of G protein alpha subunits, Bm Go, Bm Gq, and Bm Gs, from the antennae of the adult male silkmoth (Bombyx mori). RT-PCR experiments showed that the mRNA of these G protein alpha subunits was also present in the various tissues of adult and larval insects. We used immunocytochemistry to localize these G protein alpha subunits in adult male and female antennae. In the adult male antennae, anti-Go antiserum stained the nerve bundles. In contrast, anti-Gq and anti-Gs antisera stained the inner and outer dendritic segments of the putative olfactory receptor neuron. The localizations of Bm Go, Bm Gq, and Bm Gs in the female antennae were the same as in the male antennae. The localizations of Bm Gq and Bm Gs suggest that each subunit mediates a subset of the odorant response.
Copyright 2005 Wiley-Liss, Inc.