Cytogenetic and complementation analyses of recessive lethal mutations induced in theXchromosome ofDrosophilaby three alkylating agents

Abstract

SUMMARYSalivary-gland chromosomes of 54 methyl methanesulphonate- and 50 triethylene melamine-inducedX-chromosome recessive lethals inDrosophila melanogasterwere analysed. Two of the lethals induced by the mono-functional agent and 11 of those induced by the polyfunctional agent were found to be associated with detectable aberrations. A complementation analysis was also done on 82 ethyl methanesulphonate- and 34 triethylene melamine-induced recessive lethals in thezeste-whiteregion of theXchromosome. The EMS-induced lethals were found to represent lesions affecting only single cistrons. Each of the 14 cistrons in the region known to mutate to a lethal state was represented by mutant alleles, but in widely different frequencies. Seven of the TEM-induced lethals were associated with deletions, only one of which had both breakpoints within the mapped region. Twenty-six of the 27 mutations in which only single cistrons were affected were mapped to 7 of the 14 known loci. One TEM- and two EMS-induced mutations were alleles representing a previously undetected locus in thezeste-whiteregion.