1887

Abstract

SUMMARY: The effect of irradiating donor cells, immediately before mating, upon the yield of recombinants has been investigated for male (F + Hfr) strains of , which, owing to a mutational block (uvr), are unable to excise pyrimidine photoproducts. Despite the extreme sensitivity of the strains employed, as judged by colony formation, the yield of recombinants was surprisingly little affected by u.v. In particular, using an Hfr strain it was found that, after an initial fall to about 30–40% of that given by the unirradiated control, the yield of recombinants for both early and late markers declined with increasing dose at about the same rate as for the parent strain. There was evidence of damage in the DNA transferred from irradiated males in that normal linkage of unselected markers was reduced, but the decline in linkage with increasing dose was the same for both and strains. The yield of recombinants was nearly independent of the phenotype of the parent. Thus although fertility and survival are closely correlated in the Hfr, this correlation disappears in the male. Instead the u.v. sensitivity of the processes involved in chromosome transfer appears only slightly altered in these mutants despite the considerable change in sensitivity as judged by colony-formation.

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/content/journal/micro/10.1099/00221287-59-2-185
1969-12-01
2019-12-15
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