Heat shock protein (hsp60, hsp70, hsp90) expression in earthworms exposed to metal stressors in the field and laboratory

An indirect immunoperoxidase staining method, exploiting three commercially -available monoclonal antibodies, was used to detect and localize stress pr oteins (hsp60, hsp70, and hsp90, respectively) in histological sections of earthworm populations (Lumbricus rubellus) exposed to metal polluted soils. The metalliferous soils differed in certain physicochemical characters, bu t were predominantly contaminated with different levels and proportions of Pb and Zn. In the four earthworm populations resident on their "own" contam inated soils, the intensity of immunostaining for hsp70 and hsp90 was: (a) elevated above the constitutive levels in control earthworms inhabiting an unpolluted calcareous soil; (b) was least intense in the tissues of the wor m population exposed to the lowest soil metal concentrations, implying that the hsps may be expressed in a dose-response fashion; (c) was especially p ronounced in the chloragocytes, the known target tissue for metal sequestra tion and detoxification. Some evidence was obtained of a nuclear distributi on of upregulated hsp70 and hsp90 in stressed chloragocytes. Finally, trans ferring earthworms from a clean soil to one of the metalliferous soils fair ly quickly resulted in the upregulation of hsp60, hsp70 and hsp90 again pre dominantly in the chloragocytes. The potential of quantifying the earthworm hsp response to stress as a screening (Tier 1)biomarker is discussed.