TEMPERATURE-SENSITIVE MUTATIONS IN Drosophila melanogaster, III. DOMINANT LETHALS AND SEMILETHALS ON CHROMOSOME 2^*,†

Abstract

Dominant temperature-sensitive lethal and semilethal (DTS-L) mutations induced by ethyl methanesulfonate have been recovered in chromosome 2 of Drosophila melanogaster. The 19 (0.39% of the chromosomes screened) characterized had greater than 65 per cent viability at 22° ± 2°C and less than 5 per cent at 29° ± 0.5°C. Fifteen of the DTS-L's map genetically as point mutants, one appears to be a synthetic lethal, and the remaining three yielded sterile females. Ten different DTS mutants had a high survival in triploid females at 29°C. Eleven DTS-L's were found to map in the same genetic region (dp-b). All behaved as recessive lethals at 22°C and failed to survive at 22°C when combined with mutants 3 and 12. Crosses of the 11 mutants in all possible pairwise combinations yielded a circular complementation map with a side branch. The effective lethal phases and temperature-sensitive periods during development were determined for 15 of the mutants.