Biology subjects

Farine, J.-P.

Publications and source records attributed to Farine, J.-P..

3 recordsLinked to original sources

bioRxiv2022

Age and experience affect the biosynthesis and emission of a Drosophila pheromone

The most studied pheromone in Drosophila melanogaster, cis-Vaccenyl Acetate (cVA), is synthesized in the male ejaculatory bulb and transferred to the female during copulation. Combined with other chemicals cVA can modulate fly aggregation, courtship, mating and fighting. It is not detected on the cuticle of isolated males and is only released by males involved in social or sexual interaction. We explored the mechanisms underlying both cVA biosynthesis and emission in males of two wild types and a pheromonal mutant line. The effects of ageing, adult social interaction, and maternally-transmitted cVa and microbes -- both associated with the egg chorion-- on cVA biosynthesis and emission were measured. While ageing and genotype changed both biosynthesis and emission in similar ways, early developmental exposure to maternally-transmitted cVA and microbes strongly decreased cVA emission but not the biosynthesis of this molecule. This indicates that the release -- but not the biosynthesis -- of this sex pheromone strongly depends on early developmental context. The mechanism by which the preimaginal effects occur is unknown, but reinforces the significance of development in determining adult physiology and behaviour. Summary statementWe show how the biosynthesis and release of a key Drosophila pheromone is affected by ageing, by early exposure to this pheromone and to microbes, and by social context.

animal behavior and cognition↗

bioRxiv2019

Dysfunction of Torr causes a Harlequin-type ichthyosis-like phenotype in Drosophila melanogaster

Prevention of desiccation is a constant challenge for terrestrial organisms. Land insects have an extracellular coat, the cuticle, that plays a major role in protection against exaggerated water loss. Here, we report that the ABC transporter Torr - a human ABCA12 paralog - contributes to the waterproof barrier function of the cuticle in the fruit fly Drosophila melanogaster. We show that the reduction or elimination of Torr function provokes rapid desiccation. Torr is also involved in defining the inward barrier against xenobiotics penetration. Consistently, the amounts of cuticular hydrocarbons that are involved in cuticle impermeability decrease markedly when Torr activity is reduced. GFP-tagged Torr localises to membrane nano-protrusions within the cuticle, likely pore canals. This suggests that Torr is mediating the transport of cuticular hydrocarbons (CHC) through the pore canals to the cuticle surface. The envelope, which is the outermost cuticle layer constituting the main barrier, is unaffected in torr mutant larvae. This contrasts with the function of Snu, another ABC transporter needed for the construction of the cuticular inward and outward barriers, that nevertheless is implicated in CHC deposition. Hence, Torr and Snu have overlapping and independent roles to establish cuticular resistance against transpiration and xenobiotic penetration. The torr deficient phenotype parallels the phenotype of Harlequin ichthyosis caused by mutations in the human abca12 gene. Thus, it seems that the cellular and molecular mechanisms of lipid barrier assembly in the skin are conserved in vertebrates in invertebrates.\n\nAuthor SummaryAs in humans, lipids on the surface of the skin of insects protect the organism against excessive water loss and penetration of potentially harmful substances. During evolution, a greasy surface was indeed an essential trait for adaptation to life outside a watery environment. Here, we show that the membrane-gate transporter Torr is needed for the deposition of barrier lipids on the skin surface in the fruit fly Drosophila melanogaster through extracellular nano-tubes, called pore canals. In principle, the involvement of Torr parallels the scenario in humans, where the membrane-gate transporter ABCA12 is implicated in the construction of the lipid-based stratum corneum of the skin. In both cases, mutations in the genes coding for the respective transporter cause rapid water-loss and are lethal soon after birth. We conclude that the interaction between the organism and the environment obviously implies an analogous mechanism of barrier formation and function in vertebrates and invertebrates.

cell biology↗

bioRxiv2019

Experimental introgression to evaluate the impact of sex specific traits on Drosophila melanogaster incipient speciation

Sex specific traits are involved in speciation but it is difficult to determine whether their variation initiates or reinforces sexual isolation. In some insects, speciation depends of the rapid change of expression in desaturase genes coding for sex pheromones. Two closely related desaturase genes are involved in Drosophila melanogaster pheromonal communication: desat1 affects both the production and the reception of sex pheromones while desat2 is involved in their production in flies of Zimbabwe populations. There is a strong asymmetric sexual isolation between Zimbabwe populations and all other \"Cosmopolitan\" populations: Zimbabwe females rarely copulate with Cosmopolitan males whereas Zimbabwe males readily copulate with all females. All populations express desat1 but only Zimbabwe strains show high desat2 expression. To evaluate the impact of sex pheromones, female receptivity and desat expression on the incipient speciation process between Zimbabwe and Cosmopolitan populations, we introgressed the Zimbabwe genome into a Cosmopolitan genome labelled with the white mutation, using a multi-generation procedure. The association between these sex-specific traits was determined during the procedure. The production of pheromones was largely dissociated between the sexes. The copulation frequency (but not latency) was highly correlated with the female--but not with the male--principal pheromones. We finally obtained two stable white lines showing Zimbabwe-like sex pheromones, copulation discrimination and desat expression. Our study indicates that the variation of sex pheromones and of mating discrimination depend of distinct--yet overlapping--sets of genes in each sex suggesting that their cumulated effects participate to reinforce the speciation process.

evolutionary biology↗