PubMed Health⌕ Search

Biomedical subjects

M RILEY

Publications and source records attributed to M RILEY.

6 recordsLinked to original sources
PubMed1965

ISOLATION OF MUTANTS AFFECTING TRYPTOPHANASE PRODUCTION IN ESCHERICHIA COLI.

Gartner, Theodore K. (University of California, Davis), and Monica Riley. Isolation of mutants affecting tryptophanase production in Escherichia coli. J. Bacteriol. 89:313-318. 1965.-Mutants of Escherichia coli K-12 were isolated which appear to have suffered an alteration in the regulation system governing tryptophanase synthesis. A novel selection method was used to isolate tryptophanase mutants from tryptophan synthetase deletion mutants. Mutants were obtained which exhibited the following phenotypes either singly or in combination with others: constitutivity and inducibility at 13 C (wild type is not inducible at 13 C), constitutivity and hyperinducibility at 37 C. Mutation to constitutivity at 13 C seems to require two mutational changes of the wild type. Other mutants, presumably structural gene mutations, were isolated which lack tryptophanase activity under all conditions tested.

Culture Media↗
PubMed1965

GENETIC ANALYSIS OF TRYPTOPHANASE MUTANTS OF ESCHERICHIA COLI.

Gartner, Theodore K. (University of California, Davis), and Monica Riley. Genetic analysis of tryptophanase mutants of Escherichia coli. J. Bacteriol. 89:319-325. 1965.-The tryptophanase structural gene tna, and one of the tryptophanase regulation genes, R(1)tna, are closely linked, and lie between the pyr-E and ilv genes on the Escherichia coli chromosome. The mutant form of the regulation gene, which confers the properties of inducibility at 13 C, constitutivity at 37 C, and hyperinducibility at 37 C, is dominant over the wild form of the gene. Another regulation gene, R(2)tna, confers constitutivity at 13 C and does not map at the same locus as the R(2)tna gene.

Escherichia coli↗
PubMed1962

Nutritional effects on frequencies of bacterial recombination.

Riley, Monica (University of California, Berkeley) and Arthur B. Pardee. Nutritional effects on frequencies of bacterial recombination. J. Bacteriol. 83:1332-1335. 1962.-The number of recombinant colonies obtained from mated Escherichia coli is highly dependent on the composition of the medium, both during and after mating, and of the agar medium on which the bacteria are plated. Many bacteria appear to participate in mating, but the efficiency with which they carry out subsequent events leading to recombinant colony formation depends on the physiological state of the zygotes and the challenge to which they are subjected on the selective plates. These findings are reminiscent of the factors which influence the frequency of production of mutants from irradiated bacteria, the survival of bacteria irradiated with ultraviolet light, lysogenization by bacteriophage, or transformation by deoxyribonucleic acid. As a practical measure, care must be taken to hold conditions of plating constant to obtain reproducible numbers of recombinant colonies in mating experiments. For instance, traces of nutrients in agar can greatly affect recombination frequencies.

Acridines↗