Desiccation resistance: effect of cuticular hydrocarbons and water content in Drosophila melanogaster adults

Abstract

Background.The insect cuticle covers the whole body and all appendages and has bi-directionnal selective permeability: it protects against environmental stress and pathogen infection and also helps to reduce water loss. The adult cuticle is often associated with a superficial layer of fatty acid-derived molecules such as waxes and long chain hydrocarbons that prevent rapid dehydration. The waterproofing properties of cuticular hydrocarbons (CHs) depend on their chain length and desaturation number. Drosophila CH biosynthesis involves an enzymatic pathway including several elongase and desaturase enzymes.Methods.The link between desiccation resistance and CH profile remains unclear, so we tested (1) experimentally selected desiccation-resistant lines, (2) transgenic flies with altered desaturase expression and (3) natural and laboratory-induced CH variants. We also explored the possible relationship between desiccation resistance, relative water content and fecundity in females.Results.We found that increased desiccation resistance is linked with the increased proportion of desaturated CHs, but not with their total amount. Experimentally-induced desiccation resistance and CH variation both remained stable after many generations without selection. Conversely, flies with a higher water content and a lower proportion of desaturated CHs showed reduced desiccation resistance. This was also the case in flies with defective desaturase expression in the fat body.Discussion. We conclude that rapidly acquired desiccation resistance, depending on both CH profile and water content, can remain stable without selection in a humid environment. These three phenotypes, which might be expected to show a simple relationship, turn out to have complex physiological and genetic links.PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.3501v1 | CC BY 4.0 Open Access | rec:

Tissue-specific cis-regulatory divergence implicates a fatty acid elongase necessary for inhibiting interspecies mating inDrosophila

“…Unlike previous observations that CHC changes can affect desiccation resistance (Chung et al 2014; Ferveur et al 2018), our preliminary tests of eloF’s effects on desiccation did not yield a strong effect (data not shown). These studies examined flies from widely varying ecological niches (Australian desert/jungle and France/Zimbabwe), whereas D. simulans and D. sechellia have overlapping ranges (Matute and Ayroles 2014).…”

Temperature, rainfall and wind variables underlie environmental adaptation in natural populations of Drosophila melanogaster

“…We also found other interesting genes, which have been previously reported as candidates in North America but not in Europe, such as obst ‐ F , which has been suggested to be involved in longitudinal clinality (Table 2; Campo et al, 2013). obst ‐ F is involved in the cuticle formation, which acts as a barrier between the fly and the environment protecting it from insecticides, solar radiation, and desiccation (Balabanidou et al, 2018; Behr & Hoch, 2005; Ferveur et al, 2018; Rajpurohit et al, 2018). Indeed, most of the SNPs with the highest differentiation score were located in genes that are candidate for several stress responses, such as oxidative and starvation stress response, and behavioural phenotypes (Table 2).…”

“…Daylight hours is related to the circadian rhythm, which for example is known to play a role in Drosophila behavioural adaptation to high latitudes (Helfrich‐Förster et al, 2020). Evaporation is involved in organism thermoregulation and response to desiccation stress (Ferveur et al, 2018; Rajpurohit et al, 2018; Smit et al, 2018). Finally, wind direction is involved in plant adaptation by modifying pollen flow and therefore changing the spatial genetic structure (Balkenhol et al, 2017; Gardiner et al, 2016; Wang et al, 2016) and in the case of insects, antennae and specifically the Johnston's organ, are directly involved in neuron response to wind (Fuller et al, 2014; Patella & Wilson, 2018).…”

Two fatty acid synthase genes from the integument contribute to cuticular hydrocarbon biosynthesis and cuticle permeability in Locusta migratoria

“…This in turn indicates that LmFAS1 and LmFAS3 are crucial for locusts to adapt to dry conditions by promoting the synthesis of HCs. At this point, we should note that desiccation resistance in the fruit fly D. melanogaster has also been linked to HC present in the fat body (Ferveur et al ., 2018). Hence, reduced IHC in ds LmFAS1 and ds LmFAS3 locusts may contribute to the observed desiccation sensitivity.…”