FEDER, M.E.; EVGEN’EV, M.B.; ZATSEPINA, O.; GARBUZ, D.; Univ. Chicago; EIMB, Moscow; EIMB, Moscow; EIMB, Moscow: Interspecific Genetics of Thermotolerance and the Heat-Shock Response in the virilis Group of Drosophila

In studies of thermotolerance, large differences among higher taxa and small differences within a species are normally separate realms of investigation, with genetic experimentation currently feasible for only the latter. In the virilis group of Drosophila, however, species can be interbred to yield viable and partially fertile hybrids. Our research groups together have examined several species which replace one another along a latitutidinal gradient of temperature. The high-latitude species have lower thermotolerance. Hybrids are intermediate in thermotolerance. Reciprocal matings yield similar outcomes, consistent with an autosomal basis. Two species chosen for detailed study, D. virilis [low latitude] and D. lummei [high latitude], differ correspondingly in levels of heat-shock proteins. In situ hybridization to and the cloning and sequencing of the hsp68 and hsp70 genes reveal both inter- and intra-specific variation in hsp70 gene copy number due to both tandem duplication and pseudogenization. Extension of this analysis to multiple species pairs should permit a well-replicated analysis of the molecular basis of variation in thermotolerance among and within species. Supported by Russian Grants for Basic Science 0304-48-918 and 0204-49121, NSF grants IBN99-86158 and IBN03-16627.