Portal de Periódicos da CAPES

THE RELATIVELY HIGH FREQUENCY OF WHOLE-BODY MUTATIONS COMPARED WITH FRACTIONALS INDUCED BY X-RAYS IN DROSOPHILA SPERM

1961; Oxford University Press; Volume: 46; Issue: 2 Linguagem: Inglês

10.1093/genetics/46.2.203

1943-2631

Edgar Altenburg, Luolin S Browning,

Plant Genetic and Mutation Studies

Among the visible mutations of postmeiotic origin in the sperm cells of Drosophila treated with x rays, 93% appeared to be whole-body, the remaining 7% being fractionals. Among the mutations detected in a chemically treated series and those of postmeiotic spontaneous origin, the percentage of fractionals was relatively high. The high proportion of whole-body mutations in the x-ray- treated series could be accounted for on the theory of Muller, Carlson, and Schalet that radiation may break the bends of both bases of a nucleotide pair, thereby allowing their rotational substitution with resultant whole-body mutation. In all three series, the mutant tissue of the fractionals as a rule seemed to involve half of the body, so far as could be determined upon external examination of the fractionals. This half-body amount of mutant tissue indicates that these fractionals arise not as delayed effects followed by errors in replication at the first or later divisions of the fertilized egg (events which would lead to one-fourth or less mutant tissue), but rather that the fractionals in question arise as permanent changes in an already existing DNA molecule, these observations thus supporting the recent conclusions of Muller and his coworkers as to the usual naturemore » of the mutational event. However, some of the mutants may possibly have been one-fourth mosaics. If they were, they would indicate that mutations might sometimes be due to an error in the replication of the gene. (auth)« less