Recessive Lethal Mutations and the Maintenance of Duplication-Bearing Strains of Dictyostelium discoideum |
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| Authors: | Dennis L Welker and Keith L Williams |
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| Affiliation: | Max-Planck-Institut für Biochemie, 8033 Martinsried bei München, Federal Republic of Germany, Department of Biology, Utah State University, Logan, Utah 84322-5500;Max-Planck-Institut für Biochemie, 8033 Martinsried bei München, Federal Republic of Germany, School of Biological Sciences, Macquarie University, North Ryde, N.S.W., Australia 2113 |
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| 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. |
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