Ultraviolet-induced mutations to asparagine independence in Jensen sarcoma cells in vitro

UV-irradiation induces an exponential increase in the frequency of mutation from asparagine requirement to asparagine non-requirement in Jensen sarcoma cells grown in vitro. The corrected mutation frequency increases from the spontaneous rate of 5.1·10^?6 per cell to 1248·10^?6 per cell with a dose of 180 erg/mm² of 254 nm UV A substantial increase was oberved even without correction for survivors, and no significant difference was observed in the UV sensitivity of asparagine-requiring and non-requiring Jensen clones. When Jensen cells were plated at low densities in a feeder layer of LMTK-cells inactivated by HAT medium, an increase in the cloning ability of the former was observed as compared to appropriate controls without the feeder layer, but the increase was constant over all doses of UV tested. Revertants are stable and possess measurable asparagine synthetase.It is concluded that UV is an extremely effective mutagen in this system.