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-30UbL was generated, with constitutively active rps-30 promoter used to control the expression of RFP-RPS-30UbL fusion protein. We found RFP-RPS-30UbL 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 × 10-7 , and the detectable time could be within 2 h. Detecting the transcription and expression levels of RFP-RPS-30UbL in worms exposed to different kinds of environmental contaminants showed that the expression level of RFP-RPS-30UbL was not regulated by environmental contaminants, and the number differences of 'rod-like' structures were just due to the morphological change of RFP-RPS-30UbL 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-30UbL transgenic worm was more suitable to be cultured and used further than N2;GFP-RPS-30UbL , for expressing RPS-30UbL in wild type N2 worms shortened the lifespan and deceased the brood size. Therefore, rps-30-/- ;RFP-RPS-30UbL 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.