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Abstract
Summary: For the mapping of HI, the structural gene for phase-1 flagellin in Salmonella, spontaneous non-flagellate HI mutants were isolated from a phase-1 stable derivative, SJ925 HI-g1g2g3t, of Salmonella abortusequi. First, mapping was carried out with the deletion mutants among them by P22 phage-mediated transduction. Mutants of flaA1 and flaL, adjoining opposite sides of HI, were also included in the mapping. As the result, HI was divided into 16 segments by 15 deletions. Mapping by recombination frequencies was then carried out using representative HI mutants. Comparison of the two maps showed that 14 consecutive segments near flaL covered about 70% of the non-flagellate HI mutational sites, although they were confined to a quarter of HI in the recombination map. The other two segments were found to occupy the remaining three quarters of HI. By use of the deletion map, the sites of three phase-1 curly and three ah1 mutations were determined. The curly mutational sites were mapped in the segment second from the flaA1 side and the ahi mutational sites in the segments near the flaL side. To ascertain approximate positions of the areas determining the phase-1 antigen specificities, their arrangement relative to a curly mutational site, curly-2, and HI-linked fla genes was examined by three-point crosses. From the results, all the antigenic specificity-determining areas examined were located between flaA1 and curly-2 in the following order: flaA1--g2-g1-g4-(g3,g5,f,m,t)-curly-2---flaL.
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