Gene expression profile analysis of Drosophila melanogaster selected for resistance to environmental stressors.

Here, we report a detailed analysis of changes in gene expression in Drosophila melanogaster selected for ecologically relevant environmental stress resistance traits. We analysed females from seven replicated selection regimes and one control regime using whole genome gene expression arrays. When compared with gene expression profiles of control lines, we were able to detect consistent selection responses at the transcript level in each specific selection regime and also found a group of differentially expressed genes that were changed among all selected lines. Replicated selection lines showed similar changes in gene expression (compared with controls) and thus showed that 10 generations of artificial selection give a clear signal with respect to the resulting gene expression profile. The changes in gene expression in lines selected for increased longevity, desiccation and starvation resistance, respectively, showed high similarities. Cold resistance-selected lines showed little differentiation from controls. Different methods of heat selection (heat survival, heat knock down and constant 30 degrees C) showed little similarity verifying that different mechanisms are involved in high temperature adaptation. For most individual selection regimes, and in the comparison of all selected lines and controls, the gene expression changes were exclusively in one direction, although the different selection regimes varied in the direction of response. The responses to selection restricted to individual selection regimes can be interpreted as stress specific, whereas the response shared among all selected lines can be considered as a general stress response. Here, we identified genes belonging to both types of responses to selection for stress resistance.