DNA-repair Deficient Strains Chlamydomonas reinhardtii as Good Tools for Environmental Toxicology

The aim of the present study was to compare stress response of Chlamydomonas reinhardtii strains with different DNA repair capability to zeocin in order to develop a set of endpoints for the revealing of very low levels of xenobiotics. Four C. reinhardtii genotypes – 137C (wild type); CW15 (cell-wallless); UVS-10 (recombination-repair deficient); UVS-14 (mismatch-repair deficient) and different endpoints were applied – micro-colonies survival assay, malondialdehyde (MDA) and intracellular H2O2 quantities, carotenoids content, double-strand DNA breaks (DSBs) induction. Based on the cell survival, strains could be arranged as follows: WT > CW > UVS10 ∼ UVS14. The strongest oxidative stress, measured as the highest MDA and H2O2 contents, was evaluated for UVS-14 genotype. The highest quantity of DSBs induced was measured after zeocin treatment with low doses (2–10 μg/ml) for UVS-10 genotype (P < 0.01). Based on the data reported, a short-term bioassay based on C. reinhardtii with DNA repair-deficient genotypes is proposed to be successfully used in genotoxicity screening of low doses xenobiotics – micro-colonies assay on both strains (UVS-10 and UVS-14); measurement of the kinetics of MDA and H2O2 content on strain UVS-14, and primary induced DSBs levels on strain UVS-10.