Emmanuelle JACOUIN-JOLY, Gemma FABRIAS-1,
M. Pilar MARCO-1, Claude WICKER-THOMAS-2, Martine MAIBECHE,
Patricia NAGNAN-LE MEILLOUR and Charles DESCOINS.
Unite de Phytopharmacie et des Mediateurs Chimiques,
INRA Route de Saint-Cyr, F-78026 Versailles Cedex, France. 1-Departamento
de Ouimica Organica Biologica, ClD-CSiC, Jordi Girona 18-26, 08034
Barcelona, Spain. 2-Universite Paris Sud, NAM, CNRS URA 1491 Mecanismes de
Communication, F-91405 Orsay Cedex, France.
(e-mail: jacquin@versailles.inra.fr)
Pheromone production in female moth is control by a neuropeptide named PBAN (Pheromone Biosynthesis Activating Neuropeptide) (1). In our laboratory, the mechanism of the regulation was intensively studied in the cabbage armyworm Mamestra brassicae (Lepidoptera: Noctuidae): immunochemical localization of neurosecretory cells of the subesophageal ganglion, mode of transport of the hormone, mode of action. ELISA (2) and Western-blotting (3) afler both SDS-PAGE and Native-PAGE were developped for these studies. We are currently setting up a purification procedure that will lead to the amino acid sequence.
Regulation of pheromone production has been studied in a variety of insect species. In most Lepidoptera, regulation by PBAN seems to be well established. Cross-activity from different families has been obtained (1), suggesting that the brain factors are very similar among different species. However, we showed using native- and SDS-western-blots that the molecular weight and the acidity of the immunoreactive peptides are different according to the family they belong to.
The presence of immunoreactive peptides in many lepidopteran species let supposed a wide distribution of PBAN-like peptides within this order and confirmed the occurence of a PBAN peptide family.
In order to test the occurence of PBAN-like peptides in other lepidopteran species and insects from other orders, we used both immunodetection techniques described above and a bioassay that consists in incubation of M. brassicae isolated abdomens with brain extracts of the considered species. Pheromotropic activity was then tested by analysing the presence of pheromone production in isolated abdomens.
Our results are exemplified with several insects from different lepidopteran families and different orders: 1) the African sugar cane borer Eldana saccharine (Lepidoptera: Pyralidae), 2) a butterfly species: Pieris brassicae (Lepidoptera Pieridae), 3) the drosophila: Drosophila melanogaster (Diptera). In all these species, a pheromonotropic activity in brain extracts of both sexes has been shown using the bioassay described above. However, we were not able to detect any PBAN immunoreactivity in Drosophila head extract.
These results suggest that the pheromonotropic activity is not always correlated with the presence of a PBAN peptide and that those peptides could be involved in functions other than regulation of pheromone production.
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