The indicative value of the hsp70 stress response as a marker for metal effects in Oniscus asellus (Isopoda) field populations: variability between populations from metal-polluted and uncontaminated sites

Adult isopods (Oniscus asellus) from two woodland sites near Heidelberg, Germany, (1) a pristine control site and (2) a site near a disused opencast mine contaminated with cadmium, lead and zinc, were exposed to various concentrations of cadmium or lead or combinations of these for three weeks under laboratory conditions. Furthermore, in a long-term semi-field mesocosm study, isopods from the control site were exposed for up to three months either to cadmium-enriched litter substrate or to heavy metal contaminated leaf litter material from the former mine. Additional isopods were sampled directly from the field at the control site and two different sites close to the miner In each experiment, the hsp70 levels of the isopods were investigated individually by means or a standardized Western-blotting technique using monoclonal antibodies against the 70 kDa stress protein (hsp70). The studies revealed differences in the hsp70 response between the population of O. asellus living close to the mine and the population from the uncontaminated site: the latter group was characterized by a more prominent stress response to heavy metal treatment than the mine-resident population. Individuals from the control population did not acquire a physiological metal acclimatization in the mesocosm studies even after three months of exposure but resembled laboratory-exposed specimens in regards to the induction of hsp70, This observation may lead to the assumption that metal tolerance has been selected in the mine-site isopod population and, therefore, laboratory-based biomarker studies may be limited in their predicative potency in respect to long-term contaminated areas. (C) 1997 Elsevier Science B.V.