a1 National Institute of Genetics, Mishima, Shizuoka-ken, Japan
The frequency of cotransduction of motC and H1 in Salmonella has been investigated, using four Salmonella serotypes and many serotypic recombinants as donors and S. typhimurium motC mutant as recipient. The frequency varied with the four serotypes from 7% to 52%. It is suggested that the difference in frequency arises from not only differences in genetic homology between the chromosome of the recipient and the fragment from the donor, but also from differences in genetic composition of the chromosome fragments carried by the phage. The frequency of serotypic recombinants selected for motC+ and H1 gene of the donor is generally higher than with recombinants selected for flaK+ and H1. The difference in genetic homology between S. typhimurium and other species is more marked in the region between H1 aud flaK than between motC and H1.
(Received January 24 1969)