Expression of thermal tolerance genes in two Drosophila species with different acclimation capacities

Research output: Contribution to journalArticle

Abstract

Heat tolerance increases at higher acclimation temperatures in D. melanogaster, but not in D. subobscura. The two species represent separate lineages of the subgenus Sophophora of Drosophila with contrasting tropical African and temperate Palearctic evolutionary histories. D. melanogaster has five copies of the inducible hsp70 gene distributed in two clusters, named A (with two copies) and B (three copies), while D. subobscura has only two copies arranged similarly to cluster A of D. melanogaster. The hsp70s of the two species also differ in their cis-regulatory regions, with D. melanogaster exhibiting features of a faster and more productive promoter. We predicted that the interspecific variation in acclimation capacity of heat tolerance is explained by evolved variation in expression of the major group of heat shock proteins. To test this prediction, we compared basal levels of gene expression at different developmental temperatures within each of the two species. Furthermore, we explored the heat hardening dynamics by measuring the induction of gene expression during a ramping assay. The prediction of a stronger heat shock protein response in D. melanogaster as compared to D. subobscura was confirmed for both long-term acclimation and short-term hardening. For D. melanogaster the upregulation with temperature ramping ranged from less than two fold (hsp26) to 2500 fold (hsp70A) increase. In all cases induction in D. melanogaster exceeded that of D. subobscura homologs. These differences correlate with structural differences in the regulatory regions of hsp70, and might explain differences in acclimation capacity among species. Finally, in D. melanogaster we found an indication of an inverse relationship between basal and induced levels of hsp70A and hsp83 expression, suggesting a divergent role for thermal adaptation of these genes at benign and stressful temperatures, respectively. Summary statement. Drosophila melanogaster and D. subobscura differ in heat shock protein expression levels, likely mediated by evolved differences in promoter regions. This corroborates differences in acclimation capacities between the two species.

Details

Authors
  • Jesper Givskov Sørensen
  • Marta Puig Giribets
  • Rosa Tarrío
  • Francisco Rodríguez-Trelles
  • Mads Fristrup Schou
  • Volker Loeschcke
Organisations
External organisations
  • Aarhus University
  • Autonomous University of Barcelona
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Genetics

Keywords

  • Drosophila melanogaster, Drosophila subobscura, Gene expression, Heat tolerance, Hsp, Plasticity
Original languageEnglish
Pages (from-to)200-207
Number of pages8
JournalJournal of Thermal Biology
Volume84
Publication statusPublished - 2019 Aug
Publication categoryResearch
Peer-reviewedYes