Eki, Toshihiko et al. (2009) International Worm Meeting "A lifespan-based assay to assess the long-term toxicity of prolonged exposure to ecotoxic agents using C. elegans."

Harada, Hiroaki, Eki, Toshihiko, Morise, Hisashi, Kurauchi, Masaru

[International Worm Meeting, 2009]

Nematodes are highly abundant organisms found in soil or sedimentary habitats and the free-living nematode Caenorhabditis elegans (C. elegans) has been used as an excellent model for monitoring ecotoxicity in soil. The acute toxicities of toxic agents have been well examined with respect to several endpoints, such as mortality, for application to toxicity tests for environmental assessments. However, chronic influences of these agents on multicellular organisms still need to be determined. Here we studied long-term effects on the lifespan of a free-living nematode C. elegans resulting from prolonged exposure to heavy metals metals (CuSO4 and CdCl2), detergents (sodium dodecyl sulfate and a commercially available household detergent), a perfluoro organic compound (pentadecafluorooctanoic acid) and an organophosphate insecticide (dichlorvos) as well as short-term inhibitory effects on egg production and growth. These agents except for dichlorvos inhibited growth of hatched larvae and reproductive capacity in a concentration-dependent manner. They also effectively shortened the lifespan of the adult nematode over the same concentration range. Since toxic effects on both the growth and the lifespan were observed over similar concentration ranges, where acute toxicities in various endpoints are detected, the shortening of the lifespan can be used as a new endpoint for the assessment of various ecotoxic agents. We have also used a daf-16(mu86) mutant CF1038 strain, which has a deficient transcription factor DAF-16 regulating a variety of the genes involved in longevity and stress response, for ecotoxicity assays, however, both strains unexpectedly exhibited comparable reductions in these endpoints including lifespan by exposure to these ecotoxicants, indicating that DAF-16 does not largely contribute to tolerance to these agents. By virtue of a shorter assay period, the lifespan-based assay using the daf-16 mutant can be useful for assessing the ecotoxicity of ecotoxic chemicals. Ref. Harada et al., Ecotoxicol. Environ. Saf., 66, 378-383 (2007).