Gene expression, inositol metabolism and cold acclimation in Drosophila.

应对季节条件变化的能力是许多昆虫的一个关键适应特征，并限制了它们的地理分布。然而，是什么遗传和生理过程决定了耐冷性？耐寒性的提高有很强的遗传基础，包括产生低温保护化合物。虽然耐冷性本身的进化不太可能在不同的昆虫群体中独立存在，但用于提高耐寒性的化合物在不同物种之间往往不同，可能是随着气候的变化或物种改变其地理范围而进化的。最近我们发现，在冷驯化过程中，在inos基因的影响下，冷适应果蝇种群的肌醇合成被上调。在通常耐寒的物种蒙大拿州，下调inos的表达会产生对冷敏感的致命性。我们不知道这种肌醇代谢的使用是否是男性群体物种的创新，或者是否其他独立适应冷的物种也使用这种机制。我们建议对一系列果蝇在冷驯化过程中发生的遗传和代谢变化进行比较研究，以回答这个问题并阐明冷驯化的潜在替代机制。我们将开发基因操纵技术，以检验在非模式耐寒和不耐冷物种中操纵iNOS(以及潜在的其他候选基因)表达的效果；我们能否通过基因工程使寒冷敏感物种更耐寒？我们的工作将为耐寒这一关键生态性状的进化提供新的见解，并为研究非模式物种果蝇的基因功能提供详细的方法学。

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.