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Mature specimens of the isopod Oniscus asellus were maintained on soil and leaf litter to which was added different concentrations of either benzo[a]pyren (B[a]P), 2,2',5,5'-tetrachlorobiphenyl (PCB52), gamma-hexachlorocyclohexane (gamma-HCH), or pentachlorophenol (PCP) for a maximum of 14 days. Time-dependent investigation of the body level of the 70 kD stress protein group (hsp70) in the isopods revealed a significant but transient induction of the hsp70 response after about 24 h of exposure to PCB52 or B[a]P. Despite continuous exposure, the hsp70 level decreased subsequently and ended up close to or below the control level independent of the concentration of PCB52 or B[a]P in the substrate. All applied PCP or gamma-HCH concentrations also resulted in an initial peak of hsp70 response after 24 h of exposure and a second peak after several days of exposure, as well as an elevated hsp70 level throughout the period of exposure. Although acute stress conditions posed by all four organic chemicals were monitored by stress protein induction, hsp70 can act as a biomarker of chronic exposure and effect for PCP and gamma-HCH only.

Abstract During investigations on the induction of the 70 kD stress protein family (hsp70, stress-70) in Julus scandinavius following exposure to different biohazards, the colour of the supernatant of the homogenate was closely correlated to the hsp70 level. Hsp70 has recently been shown to be a suitable biomarker for sublethal toxicity in soil animals. Control millipedes typically exhibited red or red-orange supernatants whilst the supernatant of starved or toxin-exposed diplopods was orange, orange-yellow, or even bright yellow. Based on these observations, a quantitative colour test was established which was found to be able to indicate the degree of stress situations caused by exposure to heavy metals (cadmium, zinc), organic pollutants (lindane, PCB 52), or by food deprivation in laboratory tests. It is suggested that this is caused by a breakdown of the red-orange bilirubins into orange-yellow urobilins.