Molecular and General Genetics MGG

, Volume 126, Issue 4, pp 325–335 | Cite as

Fertility functions of resistance factors

Mutants of an F-like R factor which do not repress the F factor but remain self-repressed
  • Ibrahim A. -K. Al-Sowaygh
  • William T. Drabble


Three mutations (fin-1, fin-3 and fin-4) of the F-like R factor R381 have been recognised in the HfrC strain of Escherichia coli K12. The mutant R factors do not repress F-functions (sensitivity to male-specific phages and chromosome transfer) in the Hfr strain to the same extent as R381 fin+. However, unlike the derepressed R factors described previously, the mutant R factors neither confer sensitivity to male-specific phages on F- strains nor show a high rate of conjugational transfer. Dominance tests in heterodiploid strains with repressor-negative mutants of either R381 or R66 (F-like) indicate that fin-1, fin-3 and fin-4 produce repressors of R. It is concluded that the three mutations result in the production of altered repressors which are active on R but not on F.


Escherichia Coli Fertility Function Resistance Factor Conjugational Transfer Dominance Test 
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Copyright information

© Springer-Verlag 1973

Authors and Affiliations

  • Ibrahim A. -K. Al-Sowaygh
    • 1
    • 2
  • William T. Drabble
    • 1
  1. 1.Department of Physiology and BiochemistryThe University of SouthamptonSouthamptonUnited Kingdom
  2. 2.Faculty of PharmacyRiyad UniversitySaudi Arabia

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