Transcriptional Differences between Diapausing and Non-Diapausing D. montana Females Reared under the Same Photoperiod and Temperature

Abstract

BackgroundA wide range of insects living at higher latitudes enter diapause at the end of the warm season, which increases their chances of survival through harsh winter conditions. In this study we used RNA sequencing to identify genes involved in adult reproductive diapause in a northern fly species, Drosophila montana. Both diapausing and non-diapausing flies were reared under a critical day length and temperature, where about half of the emerging females enter diapause enabling us to eliminate the effects of varying environmental conditions on gene expression patterns of the two types of female flies.ResultsRNA sequencing revealed large differences between gene expression patterns of diapausing and non-diapausing females, especially in genes involved with metabolism, fatty acid biosynthesis, and metal and nucleotide binding. Differently expressed genes included several gene groups, including myosin, actin and cytochromeP450 genes, which have been previously associated with diapause. This study also identified new candidate genes, including some involved in cuticular hydrocarbon synthesis or regulation (desat1 and desat2), and acyl-CoA Δ11-desaturase activity (CG9747), and few odorant-binding protein genes (e.g. Obp44A). Also, several transposable elements (TEs) showed differential expression between the two female groups motivating future research on their roles in diapause.ConclusionsOur results demonstrate that the adult reproductive diapause in D. montana involves changes in the expression level of a variety of genes involved in key processes (e.g. metabolism and fatty acid biosynthesis) which help diapausing females to cope with overwintering. This is consistent with the view that diapause is a complex adaptive phenotype where not only sexual maturation is arrested, but also changes in adult physiology are required in order to survive over the winter.

Photoperiod-dependent expression of MicroRNA in Drosophila

“…Obp56g, Obp99a, Obp99b, Obp83g and Obp49a). Similar genes have been previously associated with diapause in D. montana (Kankare et al 2016). Obp99b is repressed by JH, which is produced by the CA (Yamamoto et al 2013) and was found to be up-regulated in diapause .…”

“…Finally, biological functions, such as 'acid biosynthetic', 'acyl-CoA metabolism', 'oxido-reduction', that we identified here were associated with diapause in previous studies in other Drosophila species (Salminen et al 2015;Kankare et al 2016). Table 1.…”

Distinct physiological, biochemical and morphometric adjustments in the malaria vectorsAnopheles gambiaeandAn. coluzziias means to survive to dry season conditions in Burkina Faso

“…The three compounds melt at high temperatures, but n-nonacosane has a higher melting point (62-66°C) than that of n-tetracosane (48-54°C). Insect literature suggests that diapausing species over-express long-chain hydrocarbons (Benoit, 2010;Kankare et al, 2016) because they improve cuticle impermeability and help in avoiding desiccation (Chung and Carroll, 2015;Gibbs, 2011). Thus, the increased amount of longer hydrocarbon chains in A. coluzzii females collected from temporary breeding sites (n-nonacosane) could support the 'strong' aestivation strategy suggested for these mosquitoes during the dry season.…”

Comparative transcriptomics support evolutionary convergence of diapause responses across Insecta

“…In the present study, D. melanogaster and D. montana have highly similar expression profiles for adult reproductive diapause, which is consistent with a single evolutionary origin. However, some of this similarity is probably driven simply by the comparison being between a fly with and without developed ovaries (Zhao et al ., ; Kankare et al ., ). Goto et al .…”