Control of female pheromones in Drosophila melanogaster by homeotic genes. C. Wicker-Thomas , J.M. Jallon. Universit Paris-Sud, UMR 8620,IBAIC, Orsay , France.

   The cuticle of Drosophila melanogaster is covered with a layer of lipids including long-chain saturated and unsaturated hydrocarbons. The main mature male hydrocarbons are monoenes (7-tricosene and 7-pentacosene) whereas female hydrocarbons are dienes (7,11-heptacosadiene, 7,11-HD and 7,11-nonacosadiene, 7,11-ND). These unsaturated hydrocarbons act as contact pheromones. To precise the role of the different parts of the body in pheromone production, we have analyzed the cuticular hydrocarbons of flies mutant for different homeotic genes of the Antp and Bithorax complexes (ANT-C and BX-C). In males there was no sigificant influence of these complexes on the hydrocarbon pattern. In females these complexes had large and opposite effects on unsaturated hydrocarbons, with no change of the saturated hydrocarbons. two ANT-C alleles caused an enhancement of diene production, with a diminution of monoenes, due to a higher conversion of monoenes to dienes. The possible existence of an activating factor originating from the prothorax on pheromone synthesis is suggested. Most BX-C mutations resulted in a more or less decrease in dienes and increase in monoenes while their sum remained constant. The effect was the highest in Mcpand iab6females. The abdomen seems therefore to have a crucial role in the production or control of pheromones; abdominal segments four to seven had the main effects, with a most dramatic effect for segments four and five.