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 Heidelber g, Germany, (1) a pristine control site and (2) a site near a disused opencast mine contaminated with cadmium, lead and zinc, were exposed t o various concentrations of cadmium or lead or combinations of these f or three weeks under laboratory conditions. Furthermore, in a long-ter m semi-field mesocosm study, isopods from the control site were expose d for up to three months either to cadmium-enriched litter substrate o r to heavy metal contaminated leaf litter material from the former min e. Additional isopods were sampled directly from the field at the cont rol site and two different sites close to the miner In each experiment , the hsp70 levels of the isopods were investigated individually by me ans or a standardized Western-blotting technique using monoclonal anti bodies against the 70 kDa stress protein (hsp70). The studies revealed differences in the hsp70 response between the population of O. asellu s living close to the mine and the population from the uncontaminated site: the latter group was characterized by a more prominent stress re sponse to heavy metal treatment than the mine-resident population. Ind ividuals from the control population did not acquire a physiological m etal acclimatization in the mesocosm studies even after three months o f exposure but resembled laboratory-exposed specimens in regards to th e 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 t heir predicative potency in respect to long-term contaminated areas. ( C) 1997 Elsevier Science B.V.