A cell in which the F-factor has integrated into a specific location in the chromosome, causing it to act as a highfrequency donor of chromosomal genes in crosses with F- cells.

A male bacterial cell that has the F factor integrated into its chromosome is an Hfr (high frequency of recombination) cell. Crosses between Hfr cells and F- females produce far more recombinant progeny than do crosses between F+ males and F- females.

High-frequency recombination strain of Escherichia coli; in such strains, the F episome is integrated into the bacterial chromosome.

Housing Flows Return - ODPM monitoring of changing dwelling numbers

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