Isolation of temperature sensitive mammalian cells by selective detachment

Temperature sensitive cells have been isclated from Syrian and Chinese hamster cells using a method based on selective detachment from a glass substrate. The Syrian hamster isolates occurred at a high frequency (about 1 in 103) and reverted rapidly; polyoma virus transformation conferred on cells the ability to grow, perhaps abnormally, in agar suspension. A slightly modified isolation technique was applied to Chinese hamster cultures and resulted in the isolation of at least one mutant (from a starting population of 5 × 108 cells) with a spontaneous reversion rate of less than one in 6 × 107. Treatment of the mutant with ethyl methane sulphonate induced reversion. It was concluded that selective detachment provided a useful method for the isolation of conditional lethal mutants of mammalian cells.