Isolation of homozygous mutants after induced self-fertilization in Tetrahymena.
Genomic exclusion, an unusual cytogenetic sequence during mating in Tetrahymena pyriformis, results in the production of homozygous germinal nuclei by the diploidization of haploid nuclei following meiosis. A method is presented for selecting cells that have made new somatic nuclei from these homozygous germinal nuclei, a step necessary for phenotypic expression of new mutations; this variation of the normal set of events is termed short-circuit genomic exclusion. The utility of thisapproach for obtaining induced mutations is demonstrated by the isolation and analysis of a strain homozygous for a recessive mutation conferring resistance to 2-fluoroadenosine. Occurring in about 5% of the unmutagenized pairs in specific crosses, short-circuit genomic exclusion should be of general use for the isolation of dominant or recessive induced mutations in this protozoan.
D002467:Cell Nucleus / Q000502:physiology; D003433:Crosses, Genetic; D004352:Drug Resistance, Microbial; D005838:Genotype; D008540:Meiosis; D008938:Mitosis; D008954:Models, Biological; D009154:Mutation; D010641:Phenotype; D012098:Reproduction; D013769:Tetrahymena pyriformis / Q000302:isolation & purification* / Q000502:physiology / Q000648:ultrastructure