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Pure Appl. Chem. Vol.
73, No. 3, pp. 613-616 (2001)
Pure and Applied
Vol. 73, Issue
Molecules and macromolecules involved in chemical communication
of scarab beetles*
Walter Soares Leal
Department of Entomology, University of California,
Davis, CA 95616 USA
Abstract: Chemical communication involves the production and
release of specific chemicals (pheromones and other semiochemicals)
by the emitter, and the detection and olfactory processing of these
signals leading to appropriate behavioral responses in the receiver.
In contrast to most of the scarab species investigated to date, the
Japanese and Osaka beetles have the ability to detect the allospecific
pheromone, which plays a pivotal role in the isolation mechanism between
these two species. Each species produces a single enantiomer of japonilure
[(Z)-5-(dec1-enyl)oxacyclopentan-2-one], but they have evolved the ability
to detect both enantiomers, one as an attractant and the other as a
behavioral antagonist (stop signal). There is growing evidence in the
literature that the inordinate sensitivity and selectivity of the insect
olfactory system is achieved by a combination of various olfactory-specific
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
play a part in the selectivity of the olfactory system in scarab beetles
by "filtering" chemical signals during the early olfactory
processing (perireceptor events). Nevertheless, it is unlikely that
pheromone-binding proteins are "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 ligands.
*Lecture presented at the 22nd IUPAC International
Symposium on the Chemistry of Natural Products, São Carlos, Brazil,
3-8 September 2000. Other presentations are published in this issue,
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