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Sex Compatibility in Escherichia coli

Genetics Society of America
Publication Date
  • Recombination
  • Genetic
  • Mutation
  • Genetics
  • Microbial
  • Escherichia Coli
  • Medicine


Reprinted from GENETICS, Vol. 37, No. 6, November, 1952, pages 720-730. PRINTEI) 1N U.S.A. SEX COMPATIBILITY IN ESCHERICHIA COIJ l JOSHUA LEDERBERG, LUIGI L. CAVALLI AND ESTHER M. LEDERBERG Department of Genetics, University of Wisconsin, Madisost, Wisconsin, and Istituto Sieroterapico Milanese “ Serajko Belfanti,” dlilano, Italia Received April 2, 1952 G ENETIC recombination in bacteria was first successfully studied in strain K-12 of Escherichiu coli (TATUM and LEDER.BERC. 1947; LEDERBERG 1951) . Since the nutritional mutants used in the crosses were derived directly from this strain under clonal propa,rration, their compatibility implied a homo- thallic or self-compatible sexual system (cf. WIIITEHOUSE 1949). The infer- ence that crossing was genetically unrestricted was supported by the absence of marked hereditary mating preferences amon 2 the segregants of a variety of crosses (LEDERBERG 1947, 1949 ; cf. LEUPOLD 1950). More recently, evi- dence has been secured for a system of sexual compatibility which was previ- ously obscured by its unique inheritance via an infective agent. METHODS AND CULTURES Experimental techniques differed slightly in Madison and Milan, but the concordance of the results obviates a detailed comparison. Crossing proce- dures, genetic symbols and the detailed pedigrees of many stocks are given elsewhere (CAVALLI 1950 ;LEDERBERG 1947 ;LEDERBERG et al. 1951). Most of the experiments have involved crosses of the original K-12, of stocks clonally related to 55-161, a double mutant requirin g biotin and methionine (B-M-), and stocks related to Y-10, a triple mutant requiring threonine, leucine, and thiamin (T-L-Th-). (Since the original isolation of 55-161 and early cross- ing experiments (TATUM 1945 ; LEDERRERC 1947) its biotin requirement appears to have been lost. The methionineless stock is, fortunately, so stable that back mutations to prototrophy are undetectable under the conditions of crossing experiments.) St

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