Growth abnormalities in Hfr Derivatives of Escherichia coli Strain c

Growth abnormalities in Hfr derivatives of Escherichia coli strain C.

From Escherichia coli strain c, made F+ by infection with the sex factor F normally carried by E. coli strain K-12, several Hfr ('high frequency of recombination ') strains were derived. Among these, four were found which exhibited a defective growth pattern on minimal media a t 37". Reversion to the F+ state was accompanied by re-establishment of normal growth habit. In the case best studied (...

Transposition derivatives of an Hfr strain of Escherichia coli K-12.

HE genome in Escherichia coli K-12 exists normally as one ring of doublestranded DNA (CAIRINS 1963). The fertility factor, F, is responsible for the ability of certain strains to act as genetic donors. F may exist as an autonomously replicating element (in Ff strains) or be integrated into and replicate with bacterial genome (in Hfr strains) (WOLLMAN, JACOB, and HAYES 1956). Multiplication of t...

Hfr Strains of Escherichia coli K-12

Since the first reports by Cavalli-Sforza (9) and Hayes (24) of strains of Escherichia coli K-12 which are conjugational donors of chromosomal markers at high frequency (Hfr strains), many other Hfr strains have been isolated and our understanding of the mechanisms involved in Hfr formation has increased considerably. All Hfr strains arise from the integration of a conjugative plasmid into the ...

Conjugational recombination in Escherichia coli: genetic analysis of recombinant formation in Hfr x F- crosses.

The formation of recombinants during conjugation between Hfr and F- strains of Escherichia coli was investigated using unselected markers to monitor integration of Hfr DNA into the circular recipient chromosome. In crosses selecting a marker located approximately 500 kb from the Hfr origin, 60-70% of the recombinants appeared to inherit the Hfr DNA in a single segment, with the proximal exchang...

F+ strains of Escherichia coli K-12 defective in Hfr formation.