Current development of a long term test with yeast strain MP1

While we are exposed to low doses of environmental carcinogens over a period of many years, in mutagenicity tests only the results of mostly single high doses will be detected. There exists no mutagenicity test system showing the results of chronic treatment in low doses. To alter this situation a long term test with yeast strain MP1, suitable for simultaneous detection of mutation, nonreciprocal recombination due to gene conversion, and reciprocal recombination has been developed. Principle of the method is the permanent and exactly calibrated supply of fresh media and removal of exhausted media allowing yeast cells to grow permanently for months. First experiments have shown that it is possible to detect the effect of carcinogens (TEM,2,4-DNFB) in concentrations being at least one to two orders of magnitude lower than in short term tests. Furthermore it was possible to get clear positive results with Caprolactam, a substance which gives only weak effects in some short term tests