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R W Hedges

Publications and source records attributed to R W Hedges.

At least 73 records · Page 4Linked to original sources
PubMed1975

Origin of the TEM-beta-lactamase gene found on plasmids.

A sequence of deoxyribonucleic acid of 2.7 times 10-6 to 3.3 times 10-6 daltons which includes the TEM beta-lactamase gene is present on the small plasmid RSF 1030 (R-Amp). This same sequence is present on plasmid derivatives that have received a translocation of deoxyribonucleic acid specifying the TEM beta-lactamase and is also present on naturally occurring plasmids of the F1, F11, N, X, O, I, C, and W incompatibility groups that do not specify ampicillin resistance or specify O-type beta-lactamases.

Ampicillin↗
PubMed1974

Molecular specificities of R factor-determined beta-lactamases: correlation with plasmid compatibility.

Beta (beta)-lactamases determined by 29 ampicillin resistance plasmids could be divided into two types. One, TEM-type, was very uniform with respect to substrate specificity but heterogeneous in absolute levels of beta-lactamase activity. The TEM-type beta-lactamase was determined by R factors of compatibility groups FII, Ialpha, Iepsilon, N, C, A, T, W, P, L, and X, and by prophage phi Amp. The other type, characterized by the ability to hydrolyze oxacillin, was less common, showed lower absolute levels of activity, and was heterogeneous as regards substrate specificities. Oxacillin-hydrolyzing beta-lactamases were determined by R factors of compatibility groups FI, Ialpha, N, C, and O.

Ampicillin↗
PubMed1972

Host specificities of RNA phages.

Host ranges of members of four groups of male-specific RNA coliphages were determined by plating on hosts carrying various derepressed plasmids. An RNA phage originally isolated on Pseudomonas aeruginosa failed to form plaques on any of the strains of Escherichia coli.

Coliphages↗