Molecular Thermal Telemetry of Free-Ranging Adult Drosophila melanogaster

• Published in: Oecologia 2000-01, Vol.123 (4), p.460-465
• Main Authors: Feder, Martin E., Roberts, Stephen P., Anna C. Bordelon
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Autoecology; b-galactosidase; Biological and medical sciences; Drosophila; Drosophila melanogaster; Ecological genetics; Ecophysiology; Evolution; Fundamental and applied biological sciences. Psychology; Heat; Heat shock proteins; Heat tolerance; Microhabitats; Protozoa. Invertebrata; Shock heating; Sunlight; Thermal stress
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s004420000334

The expression of two temperature-sensitive reporter genes, hsp70 and an hsp70-LacZ fusion, in freeranging adult Drosophila melanogaster indicates that natural thermal stress experienced by such small and mobile insects may be either infrequent or not severe. Levels of the heat-shock protein Hsp70, the major inducible Hsp of Drosophila, were similar in most wild Drosophila captured after warm days to levels previously reported for unstressed flies in the laboratory. In a transgenic strain transformed with an hsp70-LacZ fusion (i.e., the structural gene encoding bacterial β-galactosidase under control of a heat shock promoter), exposure to temperatures ≥32°C in the laboratory typically resulted in β-galactosidase activities exceeding 140$\text{mOD}_{450}\ \text{h}^{-1}\ \mu \text{g}^{-1}$soluble protein. Flies caged in sun frequently had β-galactosidase activities in excess of this level, whereas flies caged in shade and flies released and recaptured on cool days did not. Most flies (>80%) released on warm, sunny days had low β-galactosidase activities upon recapture. Although the balance of recaptured flies had elevated β-galactosidase activities on these days, their β-galactosidase activities were