. Cell heredity. Cytogenetics. RECOMBINATION IN VIRUSES AND BACTERIA 127 phaneless strain will not transduce tryptophaneless bacteria of the same strain which are, of course, mutant at the same site. To succeed, the phages must be grown on tryptophane-synthesizing bacteria, or at least on bacteria that have the wild-type allele of the locus that is mutant in the recipient strain. A suspension of sensitive bacteria infected by transducing phages may simultaneously be transduced and undergo lyso- genic conversion. But the two processes may also occur independently in the same suspension; some ba
. Cell heredity. Cytogenetics. RECOMBINATION IN VIRUSES AND BACTERIA 127 phaneless strain will not transduce tryptophaneless bacteria of the same strain which are, of course, mutant at the same site. To succeed, the phages must be grown on tryptophane-synthesizing bacteria, or at least on bacteria that have the wild-type allele of the locus that is mutant in the recipient strain. A suspension of sensitive bacteria infected by transducing phages may simultaneously be transduced and undergo lyso- genic conversion. But the two processes may also occur independently in the same suspension; some bacteria may be lysogenized and not trans- ducedâ they are converted. Others may be transduced and not con- verted. In this case the infection is initiated and the contents of the phage coat are injected but, for some reason, the phage DNA aborts and neither enters the productive cycle nor becomes reduced to pro- phage. Only the bacterial DNA is incorporated and assumes a function. Sometimes a phage may even carry from cell to cell the prophage of "- "^ Phages were grown on mef^ gal"^ xyl"^ str-r- bacteria â¢-Za^ Recipient bacteria are "met ~ gal ~ xyl ~ str-s v_/. Glucose Galactose methionine Xylose methionine Glucose methionine streptomycin met â *â gal ~ xyl ~ str-s met ~ gal ~ xyl * str-s met ~ gal '*' xyl ~ str-s m£t ~ gal ~ xyl ~ str-r FIGURE Transduction of one character at a time in Salmonella typhimurium (after Zinder and Lederberg, 1952, J. Bacf., 65:679).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Sager, Ruth; Ryan, Francis J. (Francis Joseph), 1916-. New York, Wiley
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