title: Recessive lethal mutations and the maintenance of duplication-bearing strains of Dictyostelium discoideum.
abstract: Recessive lethal mutations have been isolated and used to maintain n + 1 aneuploid strains of Dictyostelium discoideum carrying a duplication of part or all of linkage group VII. The recessive lethal mutations, relA351 and relB352, arose spontaneously in diploids; no mutagenic treatment was used in the isolation of these mutations. The probable gene order on linkage group VII is: centromere, relB couA, bsgB, cobA, relA. Maintenance of aneuploids disomic for linkage group VII was made possible by complementation of a rel mutation on each linkage group VII homologue by the corresponding wild-type allele on the other linkage group VII homologue. The duplication-bearing disomic strains were slow-growing and produced faster-growing sectors on the colony edge. Haploid sectors probably arise by a combination of mitotic recombination and subsequent loss of one homologue, diploid sectors may be formed by chromosome doubling to 2n + 2, followed by chromosome loss to return to 2n, and aneuploid sectors may arise by deletion or new mutation.
mesh_terms: D000782:Aneuploidy; D002874:Chromosome Mapping; D004023:Dictyostelium / Q000235:genetics*; D005800:Genes, Fungal; D005804:Genes, Lethal; D005808:Genes, Recessive; D008040:Genetic Linkage; D005810:Multigene Family; D009154:Mutation