Search PubMed⌕ Search

Biomedical subjects

R B Inman

Publications and source records attributed to R B Inman.

At least 73 records · Page 4Linked to original sources
PubMed1979

Influence of A-T content on the fractionation of DNA restriction fragments by RPC-5 column chromatography.

The properties of the fractionated Hae III fragments of pRZ2 DNA (Patient, R.K., Hardies, S.C., and Wells, R.D. (1979) J. Biol. Chem. 254, 5542-5547) were studied in an effort to determine why several of the fragments bind more tightly to RPC-5 than expected on the basis of their length. The purified fragments were analyzed for their nucleotide composition by direct determination of their constituent mononucleotides and by analytical CsCl and Cs2SO4 density gradient analyses. A-T-rich fragments elute at higher salt concentrations than fragments of equivalent size which are not A-T-rich. In addition, denaturation mapping studies by electron microscopy indicate that an A-T-rich run within an otherwise G-C-rich fragment can give rise to delayed elution. At least one other factor influences the separation of DNA restriction fragments by RPC-5 chromatography. Some of the fragments in this digest which elute later than predicted from their size either contain known genetic regulatory sites or bind regulatory proteins.

Adenine↗
PubMed1978

Restriction enzyme cleavage of DNA resulting from gently lysed Escherichia coli.

When E. coli or lambda infected E. coli are gently lysed the DNA is released as a very fast sedimenting species that is presumably bound to membrane material. If this complex is now subjected to restriction enzyme cleavage, only a minor fraction of the fast sedimenting DNA remains and this is found, after purification, to be enriched for branched molecules.

Cell Membrane↗
PubMed1975

Physical mapping of bacteriophage P2 mutations and their relation to the genetic map.

Three new deletion mutants and an insertion mutant of E. coli bacteriophage P2, del2, vir79, del4 and sig5, were mapped by the electron microscope heteroduplex method. The deletions were found to cover 45.5-51.6%, 75.6-76.7% and 92.3-99.3% respectively of P2 DNA while sig5 represented a 3.7% insertion at 78.6% from the left end. The region covering 75.9-76.7% of P2 DNA is also deleted in the two previously characterized immunity insensitive variants of P2, vir22 and Hy dis. This region may identify the portion of the genome responsible for immunity. The physical and genetic maps of P2 were previously found to be colinear with respect to the two mutations vir22 and vir37. This relationship is confirmed by the position of del2.

Bacteriophage P2↗
PubMed1975

Visualization of a novel junction in bacteriophage lambda DNA.

At early times after infection of a recA derivative of Escherichia coli with lambdab221c126red270a42 phage, a low but significant proportion of intracellular lambda molecules show a novel junction. These junctions are also present, although in reduced numbers, in a lysate obtained at late times after infection of a recA+ host with lambdacIIcIII phage. Fine structure and denaturation mapping analyses showed that these junctions occur at homologous positions and that they are compatible with the occurrence of a cross-strand exchange between lambda DNA duplexes similar to the type proposed in most molecular models for genetic recombination. However, the results are also consistent with the structures expected if a replicating growing point undergoes branch migration.

Coliphages↗
PubMed1974

Tandem duplication in bacteriophage P2: electron microscopic mapping.

The physical position of vir37, a new immunity-insensitive mutant of Escherichia coli bacteriophage P2, was mapped by the electron microscopic heteroduplex method. In P2 vir37, a segment equivalent to 2.8% of P2 DNA is added. The addition was characterized as a tandem duplication of the segment occurring between 77.2 and 80.0% from the left end of P2 DNA (the right half of P2 DNA is arbitrarily defined, from denaturation map studies, as the half richer in A + T). The point of addition of the duplicated segment (the "novel-joint") was, thus, 80.0% from the left end of P2 DNA. On the basis of previous studies on P2 vir22, it was tentatively concluded that the physical and genetic maps of P2 are colinear. This conclusion is now further supported by physical and genetic data on P2 vir37.

Chromosome Mapping↗