Thermal adaptation and environmental stress: from selection experiments to gene expression studies and field releases
Friday seminar by Volker Loeschcke.
We are studying adaptation to genetic and environmental stresses and their evolutionary implications with particular emphasis on thermal adaptation and the heat shock response . To achieve our research goals, we study correlated responses in lines selected for resistance to various environmental stresses as heat, cold, starvation and desiccation . Results on the phenotypic level are related to results on the DNA level, studying gene regulation in the same stress selected lines using Affymetrix gene chips at different time points after being exposed to a heat or cold hardening treatment . To complement these expression studies and to assess the role of putative candidate genes we use knockout or mutant lines and do quantitative PCR , and we study the metabolite profile and the proteome . Further, we map quantitative trait loci (QTL) responsible for thermal stress resistance , study DNA sequence variation in candidate genes and the relation of candidate gene variation to variation in resistance traits in natural populations and selection lines . Finally, we use some of the same selection lines and lines with molecular variation for stress resistance to study fitness in the wild using release-recapture experiments in order to bridge the gap between laboratory experiments and studies of thermal adaptation in the wild . These results indicate that field fitness not always can be characterized through lab assays.
 Sørensen, J.G., Norry, F., Scannapieco, A. and Loeschcke, V. 2005. Altitudinal variation for stress resistance traits and thermal adaptation in adult Drosophila buzzatii from the New World. J. Evol. Biol. 18: 829-837. Sarup, P, Sørensen, J.G., Dimitrov, K., Barker, J.S.F. and Loeschcke, V. 2006. Variation in life history and stress related traits in Drosophila buzzatii collected along a climatic gradient in South-Eastern Australia. Heredity 96: 479-486.
 Bubliy, O. and Loeschcke, V 2005. Correlated responses to selection for stress resistance and longevity in a laboratory population of Drosophila melanogaster. J. Evol. Biol. 18: 789-803.
 Sørensen, J.G., Nielsen., M.M. and Loeschcke, V. 2007. Gene expression profiles in lines selected for stress resistance in Drosophila melanogaster. J. Evol. Biol. 20: 1624-1636. - Nielsen., M.M., Sørensen, J.G.., Kruhøffer, M., Justesen, J. and Loeschcke, V. 2006. Phototransduction genes respond to heat stress selection in Drosophila melanogaster. Cell Stress & Chaperones 11: 325-333. - Kristensen, T.N., Sørensen, P., Pedersen, K.S., Kruhøffer, M. and Loeschcke, V. 2006. Inbreeding by environment interactions effects gene expression. Genetics 173: 1329-1336.
 Nielsen, M.M., Overgaard, J., Sørensen, Holmstrup, M, Justesen, J. and Loeschcke, V. 2005. Role of HSF activation for resistance to heat, cold and high temperature knock-down. J. Ins. Phys. 51: 1320-1329.
 Malmendal, A., Overgaard, J., Sørensen, J.G., Petersen, S.O., Nielsen, N. C., Loeschcke, V. and Holmstrup, M.: Metabolic profiles of stress selected flies after acclimation in Drosophila melanogaster. Am. J. Phys. - Regul. Integr. Comp. Phys. 291: R205-R212 (2006). - Overgaard, J., Malmendal, A., Sørensen, J.G., Bundy, J., Loeschcke, V., Nielsen, N. C. and Holmstrup, M. Metabolomic profiling of rapid cold hardening and cold shock in Drosophila melanogaster. J. Ins. Phys. 53: 1218-1232 (2007).
 Norry, F.M., Dahlgaard, J. and Loeschcke, V. 2004. Quantitative trait loci affecting knock-down resistance to high temperature stress in Drosophila melanogaster. Molec. Ecol. 13: 3585-3594. - Norry, F.M., Gomez, F.H. and Loeschcke, V.: Knockdown resistance to heat stress and slow recovery from chill coma are genetically associated in a central region of chromosome 2 in Drosophila melanogaster. Mol. Ecol. 16: 3274-3284 (2007).
 Frydenberg, J., Hoffmann, A.A. and Loeschcke, V.: DNA sequence variation and latitudinal associations in hsp23, hsp26 and hsp27 from natural populations of Drosophila melanogaster. Mol. Ecol. 12: 2025-2032 (2003). Jensen, L.T., Nielsen, M.M. and Loeschcke, V.: New candidate genes for heat resistance in Drosophila are regulated by HSF. Cell Stress & Chaperones (2007), in press.
 Loeschcke, V. and Hoffmann, A.A 2007. Heat hardening benefits and costs on field fitness of Drosophila depend on environmental temperature. Amer Nat. 169: 175-183. - Kristensen, T.N., Loeschcke, V. and Hoffmann, A.A. 2007. Can artificially selected phenotypes influence a component of field fitness? Thermal selection and fly performance under thermal extremes. Proc. R. Soc Lond. B 274: 771-778. - Kristensen, T.N., Hoffmann, A.A., Overgaard, J., Sørensen, J.G., Hallas, R. and Loeschcke, V.: Costs and benefits of cold acclimation in field released Drosophila. Proc. Natl. Acad. Sci. USA 105: 216-221 (2008).