Detection of environmental mutagens using the FACIM assay

A genetically engineered diploid yeast strain named yJC 2, was specifically developed for environmental mutagen detection and characterization of induced mutations. This strain contains one copy of the human TP53 tumour suppressor gene coding sequence which is used as a molecular target for mutagens and two copies of the ADE2 reporter gene allowing accurate measurement of the TP53 transcriptional activity. The strain sensitivity to mutagens was evaluated by exposing cells to UVC, 4-nitroquinoline (NQO) or to an organic extract of sediment from the Seine estuary. For all studied mutagens, a significant and dose-dependent increase of mutant frequency was observed. The present assay named FACIM II (Functional Analysis of Chemical-Induced TP53 Mutations) is more convenient than the FACIM I and more inducible than the SOS Chromotest to detect direct-acting mutagens in the environment.