RESUMEN
Strains of Salmonella typhimurium which contain a duplication of approximately 30% of the genome may be obtained by a simple selective procedure. These strains are highly unstable, losing the duplication when grown on non-selective medium. In this paper we report that treatment of merodiploid bacteria with mutagenic agents stimulates the rate at which haploid segregants are obtained from merodiploid strains. The mutagens which have been tested for this effect are X-rays, ultraviolet light (UV), ethyl methanesulfonate (EMS), and the azaacridine half-mustard ICR-372.
Asunto(s)
Diploidia , Salmonella typhimurium/genética , Compuestos Aza/farmacología , Cromosomas Bacterianos/efectos de los fármacos , Cromosomas Bacterianos/efectos de la radiación , Replicación del ADN/efectos de los fármacos , Replicación del ADN/efectos de la radiación , Diploidia/efectos de los fármacos , Diploidia/efectos de la radiación , Metanosulfonato de Etilo/farmacología , Mutágenos , Rayos Ultravioleta , Rayos XRESUMEN
All the hepatocarcinogens administered to rats markedly increased the mitotic rate in the liver. Except for alpha-benzene hexachloride and nitrosobutylurea, the nonhepatocarcinogens did not appreciably increase the mitotic rate. Cytogenetic analyses on the ploidy rate and chromosome abnormalities evidence qualitative differnces among mitotic liver cells in animals treated with hepatocarcinogens and chromosome changes in liver cells observed after the administration of hepatocarcinogenic substances may have some relation to an essential process in hepatocarcinogenesis.