Evaluation of a stress-inducible transgenic nematode strain for rapid aquatic toxicity testing

• Published in: Aquatic toxicology Vol. 29; no. 1; pp. 119 - 137
• Main Authors: Guven, Kemal, Duce, Jennifer A., de Pomerai, David I.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.06.1994; Elsevier Science
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Caenorhabditis elegans; Ecotoxicology, biological effects of pollution; Freshwater; Fundamental and applied biological sciences. Psychology; Heavy metals; Nematoda; Techniques; Toxicity testing; Transgenic; Transgenic; Caenorhabditis elegans; Heavy metals; Toxicity testing; Ecotoxicology; Investigation method; Test; Toxicity; Helmintha; Transgenic animal; Nemathelminthia; Water pollution; Invertebrata; Nematoda; Heavy metal
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/0166-445X(94)90052-3

A transgenic strain of the nematode Caenorhabditis elegans which carries a stress-inducible lacZ reporter gene has been evaluated in terms of its response to several environmental toxicants. Optimal sensitivity is obtained by exposing these worms to toxicants at a temperature just below that required for heat induction of the transgene. Under these circumstances, several heavy metals (Cd 2+, Zn 2+, Hg 2+, Mn 2+, Sn 2+, Ag +) cause dose-dependent transgene expression, which can be monitored as β-galactosidase enzyme activity or by in situ histochemical staining. A simple assessment procedure has been developed so that staining patterns can be compared between runs. The induced enzyme activity is localised in a single band (of apparent size 170 kD) on Western blots, as shown both by histochemical staining and immunoprobing. Endogenous heat-shock proteins ( hsp70) are optimally induced under the same assay conditions, but modest induction is also apparent under control conditions (sub-heat-shock temperatures alone). Our system requires relatively high concentrations (ppm) of metallic ions for clear-cut induction, but is apparently more sensitive to certain organic and organo-metallic compounds (lindane and tributyltin are effective at ppb levels). This system works well within strictly defined assay conditions, but some toxicants are more effective inducers than others (e.g. Cd 2+ versus Mn 2+), while some give paradoxical dose-response curves possibly due to enzyme poisoning at high toxicant concentrations (e.g. Ag +). However, similar problems are likely to be encountered with any transgenic assay system based on the heat-shock response when used to monitor environmental pollution.