Stress-protein response in tributyltin-exposed clams.

Abstract

The heat-shock proteins (HSPs) or stress proteins are a family of diverse proteins containing both constitutive and stress-induced members (Hightower, 1991). Under normal conditions, these proteins are involved in the transport, folding and assembly of newly synthesised proteins; under adverse environmental situations, their synthesis increases and they act to repair and protect cellular proteins and to minimise protein aggregation (Cheng et al. 1989; Chiang et al. 1989; Martin et al. 1992; Kim et al. 1993). The most abundant and best studied groups are the 70 kDa (HSP70) stress protein family and the 60 kDa (HSP60) family. Both of them are known to be induced in response to a wide variety of physical and chemical stressors, including UV light, salinity, temperature, anoxia, but also oxidizing agents, heavy metals, and organic xenobiotics (Sanders, 1990). Thus, over the past decade, an increasing number of studies have explored the possibility of using HSPs as biomarkers of adverse effects at the cellular level and some authors have proposed that the induction and subsequent accumulation of HSPs may be useful in environmental monitoring (Sanders, 1990; Sanders and Martin, 1993). The use of HSPs as biomarkers has been assessed in laboratory and field experiments, and their induction by metals and other environmental contaminants or physical parameters has been demonstrated in molluscs (Hightower, 1993; Roberts et al. 1997).