Isolation of Temperature-Sensitive Mutants

This chapter describes isolation and characterization of mutants that are defective in biochemical, cellular, or developmental processes provide a powerful tool in the analysis of the regulation of these processes at the molecular and cellular levels. A special group is the conditional mutants—usually, temperature sensitive. Temperature-sensitive (ts), mainly heat-sensitive, mutants have been isolated in various organisms and also in cultured cell lines. Such mutants have been proven very useful in physiological studies of mammalian cells grown in culture. As a result, all those ts mutants that lose viability rapidly when they become arrested at the high temperature are lost. To recover all potential ts mutants, any selection step that involves exposure of cells to the restrictive temperature is avoided. Screening of conditional mutants by replica plating is a well-known procedure in microorganisms. However, applying similar techniques for mammalian cells is much harder because of technical problems.