Evaluation for Hsp70 as a biomarker of effect of pollutants on the earthworm Lumbricus terrestris

Abstract

Induction of heat shock proteins (Hsps) is often associated with a cellular response to a harmful stress or to adverse life conditions. The main aims of the present study were (1) to assess if stress-induced Hsp70 could be used to monitor exposure of the earthworm species Lumbricus terrestris to various soil pollutants, (2) to assess the specificity of pollutants in their tissue targeting and in Hsp70 induction, and (3) to evaluate if dose-response relationships could be established and if the stress-response observed was specific. The midgut/intestinal tissues of L. terrestris are shown to express an inducible member of the Hsp70 family after heat shock treatment in vitro and exposures to different soil toxicants in vivo (re: artificial soil). Short-term (24-72 hours) and long-term (14-16 days) exposures to the chemical standards chloroacetamide and pentachlorophenol and to heavy metals (Pb++, Cd++, Cu++, and Hg++) also affected the earthworms, and Hsp70 was induced in their midgut/intestinal tissues. After a 3-day exposure to heavy metals, the level of Hsp70 induction in the midgut/intestinal tissues appears to correlate well with the reported in vivo and in vitro toxicity data. Comparatively, in proximal and midbody wall muscle tissues of animals exposed to the heavy metals, a decrease in expression of Hsp70 was sometimes detected. Thus Hsp analysis by Western blot in L. terrestris tissues and particularly in the midgut/intestine proved to be a suitable and sensitive assay for adverse effects in earthworms and showed a good level of reproducibility despite some individual variations. The use of pristine/nonexposed animals transposed into contaminated environments as in the present study should therefore be of high ecological relevance. Induction of Hsp70 in earthworms should represent not only a good wide-spectrum biomarker of exposure but also a biomarker of effect since known toxicants altered gene expression in tissues of these animals, as contrasted with a simple accumulation of Hsp. Hence, the detection of Hsp70 in earthworms can constitute an early-warning marker for the presence of potentially deleterious agents in soils, with L. terrestris in particular and earthworms in general acting as potential sentinel animal species.

Identification of a novel inducible cytosolic Hsp70 gene in Chinese shrimp Fenneropenaeus chinensis and comparison of its expression with the cognate Hsc70 under different stresses

“…FcHsp70 can be induced by copper exposure at transcription level in Chinese shrimp F. chinensis. It has been reported that Hsp70 could be responsive to a wide spectrum of heavy metal pollutants such as Pb, Hg, Ag, Co, or Ni at either the protein or the mRNA levels (Murata et al 1999;Nadeau et al 2001). Studies in aquatic invertebrates have shown that heat shock proteins contribute significantly to both organism adaptation to the environments and to survival under acute environmental stresses (Sanders 1993).…”

Heat shock response: hsp70 in environmental monitoring

“…A few studies in recent years have correlated the expression of hsp70 with known toxicological endpoints [51][52][53]. The efficiency of hsp70 expression as biomarker of environmental pollution has been advocated by many researchers [36,51,[54][55][56][57][58][59]. Recently a number of studies have been made to include more and more environmental pollutants to validate the above hypothesis.…”

“…Potentially, combinations of heavy metals can induce such distinctive patterns of Hsp expression in soil nematodes that these patterns can become diagnostic fingerprints for specific toxicants in soil [62]. Additional examples of Hsp70 expression in environmental monitoring concern rotifers [63], fish [59,[64][65][66][67], mollusks [39,40,[68][69][70][71][72], algae [73], and earthworm [57].…”

“…Yoshimi et al [74] showed that Chironomous yoshimatsui larvae could express Hsp70 upon exposure to low concentrations of insecticides and proposed that Hsp70 expression could be used as a sensitive indicator for assessing environmental burden of insecticides. Bierkens et al [73] in green algae and Nadeau et al [57] in earthworm (L. terrestris) have shown that Hsp70 could be used as a very sensitive biomarker for different classes of environmental pollutants. In soil invertebrates Oniscus asellus (isopoda) exposed to Pb ++ , Hsp70 induction could be detected as early as 1 h after treatment [42].…”

An intron-containing, heat-inducible stress-70 gene in the millipede Tachypodoiulus niger (Julidae, Diplopoda)

“…The significance of hsps within the cellular stress response and their ability to integrate overall adverse effects on protein integrity also make them informative biomarkers for tracking environmental pollution (Sanders 1990;De Pomerai 1996;Kammenga et al 2000;Nadeau et al 2001). Among the numerous classes of stress proteins, the stress-70 (hsp70) family is in this respect far best investigated.…”