Interrupted mating.

Wollman and Jacob (Nobel 1965) incubated mixtures of hfr bacteria and antibiotic-resistant F- strains with several marker genes, and placed them in a blender at various times to interrupt the conjugating process.

The cells are grown on antibiotic media so that only recipient cells were recovered.

Genetic recombination showed a linear progression with time. thr and leu are always transferred and are used in the initial screen for recombinants.

After about 10 minutes, recombination of the genes started to be detected , in the order aziR, tonS, lac+, and gal+.

This oriented transfer of genes can be used to construct a conjugation map.