The use of stress proteins as a biomarker of sub-lethal toxicity: induction of heat shock protein 70 by 2-isobutyl piperidine and transition metals at sub-lethal concentrations.

The stress response is a highly conserved reaction to various physical, chemical and biological stimuli. The ubiquity of the response occurring across taxonomic classes has identified heat shock proteins as potential biomarkers. In this study using the neutral red assay, silver stained one-dimensional SDS-PAGE, Western blotting and ELISA, the use of heat shock proteins as biomarkers of sub-lethal toxicity was examined. Hsp70 was induced in the mouse connective tissue cell line (L929) at sub-lethal concentrations for three transition metals (cadmium, mercury and copper) and for 2-isobutyl piperidine, a novel compound whose chemical structure is similar to a toxin found in the Colorado potato beetle (Leptinotarsa decemlineata). Hsp70 induction was found to increase in a dose-dependent fashion. Expression of other potentially interfering proteins was found to decrease with increasing toxin concentration. The induction of hsp70 at sub-lethal concentrations by the transition metals and 2-isobutyl piperidine demonstrates the potential of hsp70 as a biomarker of sub-lethal toxicity.