Kinetics of recombinant formation in synchronized cultures of Escherichia coli

Abstract

that the DNA transferred during conjugation is synthesized during mating under separate control in the male cell. This theory is based on the reports of K. W. Fisher (J. Gen. Microbiol. 16:120 and 16:136, 1957) that the female is not actively involved in the replication and transfer of the penetrating chromosome. From experiments of F. Bonhoeffer (Z. Vererbungslehre 98:141, 1966), it was concluded that the transfer of chromosome was not affected when deoxyribonucleic acid (DNA) synthesis was prevented in a thermosensitive mutant of an Hfr strain of Escherichia coli. However, the inhibition of DNA synthesis in the female resulted in the inhibition of recombinant formation. D. Freifelder (J. Bacteriol. 94: 396, 1967) observed that purine-requiring female strains of E. coli starved for purine formed mating pairs with the male cells, but the yield of recombinants was markedly reduced. From this, it was presumed that the mating process resulting in formation of recombinants requires some active function of the recipient cell. This function is as yet unknown, since purine starvation inhibits DNA, ribonucleic acid, and protein synthesis, and reduces all metabolic processes where adenosine triphosphate is involved. This report shows that the yield and the rate of recombinants formed by mating of synchronized female cells of E. coli depends on the position of recipient cells in the division cycle. The following strains of E. coli were used in synchronization experiments and in genetic crosses: HfrC, Met-; 242, F-Pro-Lac Strc (a

Physical Assay of Competence for Specific Mating-Pair Formation in Escherichia coli

“…It follows that each female cell has a limited time of competence to bind male cells. This may explain the observation (16,19) that the ability of recipient bacteria to produce recombinants varies considerably during their cell division cycle.…”