A set of female pheromones affects reproduction before, during and after mating in Drosophila

0022-0949 (Print) Comparative Study Journal Article Research Support, Non-U.S. Gov'tSex pheromones are chemical signals used for mate attraction and discrimination in many invertebrate species. These compounds are often complex mixtures with different components having different effects. We tested live Drosophila melanogaster mutant female flies genetically depleted for unsaturated cuticular hydrocarbons, which were then perfumed with these substances to measure their influence on various aspects of reproduction. Female pheromones of the control Cs strain enhanced female attractivity, copulation duration and tended to decrease the number of female progeny of mutant females mated with Cs males, but no dose-dependent effect was found. Cs and variant males showed different response to Cs female pheromone, suggesting a strain-specific coadaptation of female and male characters. The fact that female pheromones induced reciprocal effects on the frequency of the genes contributed by females and males suggests that these substances regulate coevolutionary processes between the sexes

Dissection génétique et moléculaire du gène desat1 impliqué dans la communication phéromonale, chez Drosophila melanogaster

Chez Drosophila melanogaster, nous avons isolé et caractérisé une mutation causée par l insertion d un transposon PGal4 dans la région 5 UTR du gène desat1. A l état homozygote, cette mutation perturbe plusieurs caractères qui sont tous liés avec la communication phéromonale et la reproduction de cet insecte. a) La production des hydrocarbures cuticulaires (HCs) comportant une ou deux doubles-liaisons est largement diminuée au profit des HCs linéaires saturés qui deviennent très abondants chez les mutants. Ces HCs insaturés, sexuellement dimorphiques chez les mâles (7-monoènes) et femelles (7,11-diènes) sauvages, permettent normalement à un mâle témoin de distinguer les sexes : ce sont des phéromones sexuelles. b) La discrimination de ces phéromones sexuelles est perturbée chez le mâle mutant. c) Les phéromones femelles exercent un rôle important sur le choix du mâle, et sur la composition de leur progéniture. d) La mutation modifie aussi plusieurs aspects de l accouplement.In Drosophila melanogaster, we found and characterized a mutation induced by a PGal4 transposon inserted in the 5'UTR region of the desat1 gene. When homozygous, this mutation affected several characters that are all related to the pheromonal communication and sexual reproduction of this insect. a) The production of cuticular hydrocarbons (CHs) with one or two double-bonds largely decreased whereas linear saturated CHs increased to become predominant in mutant flies. The predominant CHs of control flies that are sexually dimorphic (7-monoenes in males and 7,11-dienes in females) are sex pheromones because they normally allow a control male to distinguish the sexes. b) Male discrimination of these sex pheromones was altered by the mutation. c) Female's pheromones were involved in mate recognition and choice, and also influenced the sex-ratio of the offspring. Several aspects of copulation behaviour were also altered by the mutation.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

A Mutation With Major Effects on Drosophila melanogaster Sex Pheromones

Sex pheromones are intraspecific chemical signals that are crucial for mate attraction and discrimination. In Drosophila melanogaster, the predominant hydrocarbons on the cuticle of mature female and male flies are radically different and tend to stimulate or inhibit male courtship, respectively. This sexual difference depends largely upon the number of double bonds (one in males and two in females) added by desaturase enzymes. A mutation was caused by a PGal4 transposon inserted in the desat1 gene that codes for the desaturase crucial for setting these double bonds. Homozygous mutant flies produced 70–90% fewer sex pheromones than control flies, and the pheromonal difference between the sexes was almost abolished. A total of 134 excision alleles were induced by pulling out all or a part of the transposon. The pheromonal profile was generally rescued in excision alleles with a completely or largely removed transposon whereas it remained mutant in alleles with a larger piece of the transposon. Five desat1 transcripts were detected during larval-to-adult development. Their levels were precisely quantified in 24-hr-old adults, a critical period for the production of sex pheromones. Three transcripts significantly varied between control females and males; however, the predominant transcript showed no difference. In mutant flies, the predominant transcript was highly decreased with the two sexually dimorphic transcripts.These two transcripts were also absent in the sibling species D. simulans, which shows no sexually dimorphic hydrocarbons. We also induced a larval-lethal allele that lacked all transcripts and failed to complement the defective hydrocarbon phenotype of mutant alleles

Revisited Roles of Drosophila Female Pheromones

0379-864X (Print) Journal articl

The role of cuticular pheromones in courtship conditioning of Drosophila males

Courtship conditioning is an associative learning paradigm in Drosophila melanogaster, wherein male courtship behavior is modified by experience with unreceptive, previously mated females. While the training experience with mated females involves multiple sensory and behavioral interactions, we hypothesized that female cuticular hydrocarbons function as a specific chemosensory conditioned stimulus in this learning paradigm. The effects of training with mated females were determined in courtship tests with either wild-type virgin females as courtship targets, or with target flies of different genotypes that express distinct cuticular hydrocarbon (CH) profiles. Results of tests with female targets that lacked the normal CH profile, and with male targets that expressed typically female CH profiles, indicated that components of this CH profile are both necessary and sufficient cues to elicit the effects of conditioning. Results with additional targets indicated that the female-specific 7,11-dienes, which induce naive males to court, are not essential components of the conditioned stimulus. Rather, the learned response was significantly correlated with the levels of 9-pentacosene (9-P), a compound found in both males and females of many Drosophila strains and species. Adding 9-P to target flies showed that it stimulates courting males to attempt to copulate, and confirmed its role as a component of the conditioned stimulus by demonstrating dose-dependent increases in the expression of the learned response. Thus, 9-P can contribute significantly to the conditioned suppression of male courtship toward targets that express this pheromone