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Recent studies have suggested that pheromone-degrading enzymes belonging to the carboxylesterase family could play a role in the dynamics of the olfactory response to acetate sex pheromones in insects. Bioinformatic analyses of a male antennal expressed sequence tag library allowed the identification of 19 putative esterase genes expressed in the antennae of the moth Spodoptera littoralis. Phylogenetic analysis revealed that these genes belong to different insect esterase clades, defined by their putative cellular localization and substrate preferences. Interestingly, two of the 19 genes appeared to be antennal specific, suggesting a specific role in olfactory processing. This high esterase diversity suggested that the antennae are the location for intense esterase-based metabolism, against potentially a large range of exogenous and endogenous molecules. [ABSTRACT FROM AUTHOR]

Abstract: Signal inactivation is a crucial step in the dynamic of olfactory process and involves various Odorant-Degrading Enzymes. In the silkworm Bombyx mori, one of the best models for studying olfaction in insects, the involvement of an antennal-specific aldehyde oxidase in the degradation of the sex pheromone component bombykal has been demonstrated over the three past decades by biochemical studies. However, the corresponding enzyme has never been characterized at the molecular level. Bioinformatic screening of B. mori genome and molecular approaches have been used to isolate several candidate sequences of aldehyde oxidases. Two interesting antennal-expressed genes have been further characterized and their putative functions are discussed in regard to their respective expression pattern and to our knowledge on aldehyde oxidase properties. Interestingly, one gene appeared as specifically expressed in the antennae of B. mori and associated in males with the bombykal-sensitive sensilla, strongly suggesting that it could encode for the previously biochemically characterized enzyme. [Copyright &y& Elsevier]

Abstract: Signal termination is a crucial step in the dynamic of the olfactory process. It involves different classes of odorant-degrading enzymes. Whereas aldehyde oxidase enzymatic activities have been demonstrated in insect antennae by previous biochemical studies, the corresponding enzymes have never been characterized at the molecular level. In the cabbage armyworm Mamestra brassicae, we isolated for the first time an aldehyde oxidase partial cDNA specifically expressed in chemosensory organs, with the strongest expression in antennae of both sexes. In these organs, expression was restricted to the olfactory sensilla. Our results suggest that the corresponding enzyme could degrade aldehyde odorant compounds, such as pheromones or plant’s volatiles. [Copyright &y& Elsevier]