Showing papers by "Norton D. Zinder published in 1992"
TL;DR: The work was done during the previous two years in JOSHUA LEDERBERG'S laboratory at the University of Wisconsin where I was attempting to extend his discovery of bacterial conjugation, and I reconstructed the discovery from my notes.
Abstract: F ORTY years ago we published a paper describing bacterial transduction (ZINDER and LEDERBERG 1952). The work was done during the previous two years in JOSHUA LEDERBERG'S laboratory at the University of Wisconsin where I was attempting to extend his discovery of bacterial conjugation. Since over many years one’s memory can play tricks as well as be influenced by external circumstances, I’ve reconstructed the discovery from my notes. Although they are for the most part readable, we must remember that they were written at a time when concepts such as phage, lysogeny, and even the gene were obscure. Getting started: With the discovery of the penicillin enrichment technique for isolating auxotrophic bacterial mutants (DAVIS 1948; LEDERBERG and ZINDER 1948), a number of strains of Salmonella typhimurium were marked so as to permit tests for bacterial conjugation. Marking the strains involved the isolation of two sets of nonoverlapping double mutants, most having amino acid requirements. Tests were done by mixing two cultures, plating on a minimal medium, and looking for prototrophic colonies. At that time, similarly marked mutant strains of Escherichia coli K12 would give between 1 OS6 and 1 O-’ prototrophic recombinants. It is also important to note that the E. coli data strongly suggested that the bacteria were haploid (TATUM and LEDERBERG 1947). This work really began when 22 phage-typed S. typhimurium strains arrived from LILLEENGEN in Sweden (LILLEENGEN 1948). From each of these strains large numbers of auxotrophic mutants were obtained by the penicillin enrichment procedure. Two mutagenesis protocols were used involving two UV dosages. Trying to reconstruct why I chose these dosages, my guess is that some of the strains carried UVinducible phages and were readily killed but not readily mutagenized, necessitating a larger UV dose. There are no interpretable data in this part of my notes other than that the lower dose reduced the
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