THE ROLE OF THE UVRA GENE IN THE SCREENING OF GENOTOXINS IN THE SOS CHROMOTEST
Chen Zhongfu Feng Xiao Sheng Zujia (Institute of Genetics, Fudan University, Shanghai)
45 different chemicals, including carcinogens, antitumor agents, base analogues, metabolite inhibitors, food additives and waste water, were screened for their genotoxicity using the SOS chromotest. Escherichia coli uvr A~- strain PQ37 and uvr A~+ strain GC4415 were used to elucidate the role of the uvrA gene in the SOS chromotest. Generally, uvrA~-strain PQ37 is very sensitive in the SOS chromotest while with strain GC4415 we failed to detect the genotoxicity of nitrocaphane, acridine yellow and a series of analogues of daunomycin. It has been observed that for some chemicals, such as mitomycin C, nalidixic acid, methotrexat, the SOS inducibility of strain PQ37 is instead lower than the strain GC4415. It has been known that the ability of certain chemicals to induce SOS response depends partly on uvrA~+ gene product. It is thereforere preferable to use unrA~+ strain and uvrA~- strain together in the SOS chromotest for screening genotoxins as we did here.