TEMPERATURE-SENSITIVE MUTATIONS IN DROSOPHILA MELANOGASTER.: II. FREQUENCY AMONG SECOND CHROMOSOME RECESSIVE LETHALS INDUCED BY ETHYL METHANESULFONATE

Abstract
Recessive lethals and semilethal mutations induced in chromosome 2 were screened for temperature-sensitivity. Mutants which die 29[degree]C but survive at 17[degree]C were recovered. Temperature-sensitive (ts) lethals were defined as mutants which give non-survivors at 29[degree]C and at least 20% at 17[degree]C and ts semi-lethals as those which give less than 5% survival at 29[degree]C and at least 50% at 17[degree]C. At 0.005M EMS, 37.5% of the treated chromosomes were lethal or semilethal from which it is estimated that 10.9% of all EMS-induced lethals are ts. This class of conditional lethals promises to be a useful tool in genetic studies.