THYMINELESS MUTATION SITE ON ESCHERICHIA COLI CHROMOSOME.

Kitsuji, Nobuo (Kanazawa University, Kanazawa, Ishikawa, Japan). Thymineless mutation site on Escherichia coli chromosome. J. Bacteriol. 87:802-808. 1964.-Kinetic studies of the recombinant formation in crosses between Escherichia coli K-12 Hfr H, Hfr C, or Hfr P10 as donor and F(-)W1177thy(-)his(-) as recipients showed that the time of appearance of thy(+)Sm(r) recombinants lay between that of xyl(+)Sm(r) and his(+)Sm(r), indicating that the thy gene lies between the xyl and his markers. Genetic analysis of recombinants of the Hfr C x W117thy(-)his(-) cross further indicated that the thy gene is located on the chromosome between the Sm marker and the his marker. In matings between seven independently isolated thymineless mutants of Hfr P10 and F(-)W1177thy(-)his(-), thy(+) recombinants of various recombination rates appeared. Thus, it was suggested that in E. coli K-12 the thy gene occupies some region between the Sm marker and the his marker on the chromosome, and that there are many thymineless mutation sites in it.