Transgenic RFP-RPS-30UbL strain of the nematode Caenorhabditis elegans as a biomonitor for environmental pollutants

Environmental pollutants are recognized as one of the major concerns for public health. The free-living nematode Caenorhabditis elegans are widely used to evaluate the toxicity of environmental contaminants in biomonitoring researches. In the present study, a new transgenic strain, rps-30(-/-);RFP-RPS-30(UbL) was generated, with constitutively active rps-30 promoter used to control the expression of RFP-RPS-30(UbL) fusion protein. We found RFP-RPS-30(UbL) would accumulate to form 'rod-like' structures, when worms were exposed to environmental contaminants, including Cd, Hg, Pb, As, Paraquat and Dichlorvos. The number of the 'rod-like' structures was induced by environmental contaminants in a concentration- and time-dependent manner. The 'rod-like' structure formation could be detectable in response to the concentration of each contaminant as low as 24-h LC50 x 10(-7), and the detectable time could be within 2 h. Detecting the transcription and expression levels of RFP-RPS-30(UbL) in worms exposed to different kinds of environmental contaminants showed that the expression level of RFP-RPS-30(UbL) was not regulated by environmental contaminants, and the number differences of 'rod-like' structures were just due to the morphological change of RFP-RPS-30(UbL) from dispersion to accumulation induced by environmental contaminants. In addition, this transgenic strain was developed in rps-30(-/-) homozygous worm, which was a longevity strain. Detection of lifespan and brood size showed that rps-30(-/-);RFP-RPS-30(UbL) transgenic worm was more suitable to be cultured and used further than N2;GFP-RPS-30(UbL), for expressing RPS-30(UbL) in wild type N2 worms shortened the lifespan and deceased the brood size. Therefore, rps-30(-/-);RFP-RPS-30(UbL) transgenic worm might play a potential role in versatile environmental biomonitoring, with the advantage of not only the convenient and quick fluorescence-based reporter assay, but also the quantificational evaluation of the toxicities of environmental contaminants using 'rod-like' structures with high sensitivity, off-limited the expression level of the reporter protein.

Automated summary

The study found that certain environmental pollutants induce the accumulation of a specific protein in nematodes, forming "rod-like" structures that can be used to evaluate the toxicity of environmental contaminants. By generating transgenic nematodes, this monitoring method can be implemented more conveniently.