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Biomedical subjects

B Rolfe

Publications and source records attributed to B Rolfe.

33 records · Page 2Linked to original sources
PubMed1972

Pleiotropic properties and genetic organization of the tolA,B locus of Escherichia coli K-12.

Colicin-tolerant mutants of Escherichia coli K-12, which map near gal at 17 min (tolA, B mutants), have been isolated and characterized. These mutants exhibited a very broad spectrum of phenotypic changes consistent with the interpretation that they are cell surface mutants. In addition to being colicintolerant and sensitive to deoxycholate and ethylenediaminetetraacetic acid, tolA, B mutants are sensitive to vancomycin, bacitracin, and dodecyl sulfate. The tolA, B mutants from most strains also formed mucoid colonies at 30 C on nutrient agar plates and had a greatly increased plating efficiency for lysisdefective S mutants of bacteriophage lambda. Complementation analysis showed that the four phenotypic groups of tol mutants that map near gal fall into three complementation groups: tolP, tolA, and tolB. Recombination analysis by three-factor crosses established the order of the three groups as tolP-tolA-tolB-gal. Because of the wide variety of phenotypic changes that accompanies mutation to colicin tolerance, revertants were isolated to test whether single or multiple mutations were involved. The reversion analysis, as well as other genetic criteria, confirmed that only single mutations were involved, suggesting that these pleiotropic changes are a consequence of a single change in the E. coli cell surface.

Bacitracin↗
PubMed1968

Genetic and biochemical analysis of the biotin loci of Escherichia coli K-12.

Some 60 biotin auxotrophs of Escherichia coli K-12 were isolated and classified into four groups according to their cross-feeding patterns, excertion products, and their ability to show a growth response to various biotin vitamers. Since all the mutants could be transduced with lambdadbio phages known to carry the entire bioA locus, it was concluded that all of the mutation sites were located in this locus. It was also possible to derive a gene order for the different mutant groups on the basis of transduction studies with various lambdadbio phages that carry portions of the bioA locus. A possible biochemical pathway for the biosynthesis of biotin in E. coli K-12 is discussed.

Biological Assay↗
PubMed1966

Alterations in host specificity of bacterial deoxyribonucleic acid after an increase in growth temperature of Pseudomonas aeruginosa.

Rolfe, B. (University of Melbourne, Victoria, Australia), and B. W. Holloway. Alterations in host specificity of bacterial deoxyribonucleic acid after an increase in growth temperature of Pseudomonas aeruginosa. J. Bacteriol. 92:43-48. 1966.-Increased recombination frequency is found with some crosses of Pseudomonas aeruginosa if the FP(-) parent is grown at 43 C prior to mating. This occurs where there is a difference in host specificity between the FP(-) and FP(+) parents, as is found in strains 1 and 2. Differences in recovery of unlinked markers are found in such crosses, and the results can be explained in terms of an alteration of the restriction and modification mechanisms by growth at the higher temperature, similar to that previously shown to occur with host-modified bacteriophage. As with that system, persistence of the temperature effect occurs for a number of generations after the strains are returned for growth at 37 C.

Chromosomes↗