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Letters to Nature

Nature 234, 222-223 (26 November 1971) | doi:10.1038/234222a0

Compatibility Groups among fi- R Factors

NAOMI DATTA & R. W. HEDGES

  1. Department of Bacteriology, Royal Postgraduate Medical School, DuCane Road, London W12
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TRANSMISSIBLE R factors in bacteria are divisible into two main classes, fi+ (fertility inhibition +) and fi-, according to their effect on F mediated conjugation1. fi+ R factors determine F-like pili2. Some fi- R factors determine pili similar to those specified by col I (I-type pili)3 which can be recognized as receptors for I-specific phages like If1 (ref. 4). Although heterogeneity among fi- R factors has already been indicated5–8, it is sometimes assumed that all fi- R factors have I pili9,10.