Natural variation in Drosophila melanogaster diapause due to the insulin-regulated PI3-kinase

Abstract

This study links natural variation in a Drosophila melanogaster overwintering strategy, diapause, to the insulin-regulated phosphatidylinositol 3-kinase (PI3-kinase) gene, Dp110. Variation in diapause, a reproductive arrest, was associated with Dp110 by using Dp110 deletions and genomic rescue fragments in transgenic flies. Deletions of Dp110 increased the proportion of individuals in diapause, whereas expression of Dp110 in the nervous system, but not including the visual system, decreased it. The roles of phosphatidylinositol 3-kinase for both diapause in D. melanogaster and dauer formation in Caenorhabditis elegans suggest a conserved role for this kinase in both reproductive and developmental arrests in response to environmental stresses.evolutionary genetics

Population dependent effects of photoperiod on diapause related physiological traits in an invasive beetle (Leptinotarsa decemlineata)

“…It should be stressed that many parts of the regulatory machinery are still very vaguely known, and inter-species variation is large. For instance, the cellular JH receptor still remains unknown and the link between JH titer and Insulin signaling has only been investigated in a handful of studies (Tatar et al 2001, Williams et al 2006, Sim and Denlinger 2008. Therefore many steps are to be taken as hypothetical.…”

Insulin signaling is involved in the regulation of worker division of labor in honey bee colonies

“…In this view, the combination of high insulin synthesis and high insulin sensitivity maintains, or perhaps causes, a shift from high to low adiposity during behavioral maturation (and in response to experimental nutritional manipulations). Similar reasoning has been used to explain relationships between nutrient-sensing pathways and variation in nutrient stores in the contexts of mammalian torpor (50,51) and insect diapause (52).…”

Dissecting the genetics of longevity inDrosophila melanogaster

“…65,91,112,113 Two natural Dp110 alleles which differentially affect diapause have been sequenced, though there is an absence of pronounced polymorphism between them: of 20 polymorphisms detected, none affect the amino acid sequence nor levels of RNA. 68 However, a single nucleotide polymorphism at cpo shows strong control over the ability of D. melanogaster to enter diapause. 66 The SNP shows a significant cline in frequency across latitude in the eastern U.S., suggesting a functional response to heterogeneous selection pressure.…”

“…[22][23][24]39,42 Gene expression assays clock, 67 and the insulin-regulated phosphatidylinositol 3-kinase (PI3-kinase) gene Dp110. 68 Diapause in the house mosquito Culex pipiens is also regulated by Dp110, 69 and the homolog of Dp110 in C. elegans, age-1, is well established as a gene that affects aging and dauer formation in worms. 70 This suggests that insect diapause and the dauer phenotype in C. elegans may be in part regulated by homologous pathways, 71 and while direct mutational and functional tests of diapause genes on longevity phenotype are lacking, such analyses have the potential to confirm tim, cpo and Dp110 as aging genes in Drosophila.…”

“…68 In D. melanogaster, diapause produces a significant extension in lifespan and is associated with genetic variance for longevity, fecundity, development time, lipid content and stress tolerance. 65,91,112,113 Two natural Dp110 alleles which differentially affect diapause have been sequenced, though there is an absence of pronounced polymorphism between them: of 20 polymorphisms detected, none affect the amino acid sequence nor levels of RNA.…”