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Abstract
Five fla mutations of Salmonella typhimurium lt2 have been mapped by transduction. They were isolated from five motile (fla +) strains each with a different form of antigen-i, caused by mutation of H1, the structural gene for phase-1 flagellin. H1 was cotransduced (frequency 0·1 to 0·5) with each of the fla mutations. Three-point crosses using a serological selection technique indicate the following order: fla-50—fla-58—fla-55-H1. The position of fla-52 was not discovered. If the fla complementation groups correspond to the fla genes their order is flaB—flaD—flaA—H1.
Of the five H1 mutations four (M5, M20, M11, M12) appear to be very closely linked. The fifth (M6) is outside this cluster. Transductants with functionally and antigenically normal antigen-i were obtained, at a very low frequency, in crosses between i-curly and fla strains: they are attributed to crossing over within H1 between the ‘curly’ mutation and the mutations causing alteration in serological character. Some earlier conclusions (Joys & Stocker, 1963) as to gene order, especially within H1, now seem unjustified.
- Accepted:
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