Molecules and macromolecules involved in chemical communication of scarab beetles

Chemical communication involves the production and release of specific chem icals (pheromones and other semiochemicals) by the emitter. and the detecti on and olfactory processing of these signals leading to appropriate behavio ral responses in the receiver. In contrast to most of the scarab species in vestigated to date, the Japanese and Osaka beetles have the ability to dete ct the allospecific pheromone, which plays a pivotal role in the isolation mechanism between these two species. Each species produces a single enantio mer of japonilure [(Z)-5-(dec1-enyl)oxacyclopentan-2-one], but they have ev olved the ability to detect both enantiomers, one as an attractant and the other as a behavioral antagonist (stop signal). There is growing evidence i n the literature that the inordinate sensitivity and selectivity of the ins ect olfactory system is achieved by a combination of various olfactory-spec ific proteins, namely, odorant-binding proteins (OBPs), odorant receptors ( ORs), and odorant-degrading enzymes. The relationship between the pheromone structures and the primary sequences of the proteins suggest that OBPs pla y a part in the selectivity of the olfactory system in scarab beetles by "f iltering" chemical signals during the early olfactory processing (perirecep tor events). Nevertheless, it is unlikely that pheromone-binding proteins a re "chiral filters" as the Japanese and Osaka beetles each possess only one single binding protein. Upon interaction with negatively charged membranes , OBPs undergo conformational changes that may lead to the release of the l igands.