Gene expression, inositol metabolism and cold acclimation in Drosophila.

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The ability to cope with changing seasonal conditions is a key adaptive trait for many insects and limits their geographic distribution. However, what genetic and physiological processes govern cold tolerance? An increase in cold tolerance has a strong genetic basis involving the production of cryo-protective compounds. Although the evolution of cold tolerance per se is unlikely to be independent across different insect groups, the compounds used to increase cold tolerance often differ between species, probably evolving during shifts in climate or as species alter their geographic ranges. Recently we found that inositol synthesis, under the influence of the gene inos, is up-regulated during cold acclimation by species of the cold-adapted Drosophila virilis group. Knocking down inos expression produces cold-sensitive lethality in the normally cold tolerant species D. montana. We do not know if this use of inositol metabolism is an innovation of virilis group species, or if other independently cold-adapted species also use this mechanism. We propose a comparative study of the genetic and metabolomic changes occurring during cold acclimation in a range of Drosophila species, to answer this question and to elucidate potential alternative mechanisms of cold acclimation. We will develop genetic manipulation techniques to examine the effects of manipulating the expression of inos (and potentially other candidate genes) in non-model cold tolerant and intolerant species; can we genetically engineer cold sensitive species to make them more cold tolerant? Our work will provide new insights into the evolution of a key ecological trait, cold tolerance, and also provide a detailed methodology for the study of gene function in non-model species of Drosophila.