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R C Miller

Publications and source records attributed to R C Miller.

At least 343 records · Page 19Linked to original sources
PubMed1970

Molecular Recombination in T4 Bacteriophage Deoxyribonucleic Acid: III. Formation of Long Single Strands During Recombination.

Evidence was presented to support the hypothesis that long single strands appearing at late times (15 min after infection) are produced as a result of recombination and not as a continuous elongation during the replication process. The production of long strands does not depend on the multiplicity of infection, and the first long strands appear at the time when 20 to 50 phage equivalent units of deoxyribonucleic (DNA) are synthesized, and not earlier. The addition of chloramphenicol at 5 min, which prevents molecular recombination but allows replication of DNA, prevents the formation of long, single strands. Chloramphenicol added between 8 and 10 min after infection, a time at which molecular recombination is fully expressed and covalent repair of recombinant molecules is allowed, does not prevent formation of long single strands. Cutting of single-strand DNA with a limited amount of endonuclease I allows confirmation that the fast-sedimenting characteristic of intracellular denatured DNA is caused primarily by the length of the strands, and not by the formation of aggregates. The computer simulation of two recombination models indicates the feasibility of random breakage and rejoining of molecules in generating long concatenates.

Journal Article↗
PubMed1970

Early intracellular events in the replication of bacteriophage T4 deoxyribonucleic acid. V. Further studies on the T4 protein-deoxyribonucleic acid complex.

Soon after infection parental deoxyribonucleic acid (DNA) enters a structure sedimenting fast to the bottom of a sucrose gradient. The addition of chloramphenicol (CM) prevents formation of this structure, whereas treatment with Pronase releases DNA which sediments thereafter with the speed characteristic of phenol-extracted replicative DNA. It is assumed therefore that the structure responsible for fast sedimentation of replicative DNA is a newly synthesized protein. Those fast-sedimenting complexes contain preferentially the replicative form of parental DNA; this was proven by density labeling experiments. Progeny DNA labeled with (3)H-thymidine added after infection can also be detected preferentially in this fast-sedimenting moiety. The association of the DNA with the complexing protein is of a colinear or quasi-colinear type. This was proven by introducing double-strand scissions into DNA embedded in the replicative complex; double-strand scissions do not liberate DNA from the fast-sedimenting complex. Despite the apparent intimate relation between protein and DNA, DNA residing in complexes is fully sensitive to the action of nucleases. Shortly prior to the appearance of the fast-sedimenting complex, parental DNA displays still another characteristic: at about 3 min after infection, it sediments faster than reference, but sizeably slower than the complex which appears at roughly 4 to 5 min after infection. The transition between these two fast-sedimenting types of moieties is not continuous. This fast-sedimenting intermediate, which appears at 3 min after infection, cannot be inhibited by the addition of CM either at the moment or prior to infection. Fast-sedimenting intermediate can be destroyed by sodium dodecyl sulfate, Pronase, or phenol extraction. The progeny DNA labeled with (3)H-thymidine between 3 and 3.5 min after infection can be recovered in fast-sedimenting intermediate. The contribution of newly synthesized progeny DNA is so small that it cannot be detected as a shift of the parental density in a density labeling experiment. Small fragments of progeny DNA recovered in fast-sedimenting intermediate are not covalentlv attached to parental molecules and represent both strands of T4 DNA.

Centrifugation, Density Gradient↗
PubMed1970

Early intracellular events in the replication of bacteriophage T4 deoxyribonucleic acid. VI. Newly synthesized proteins in the T4 protein-deoxyribonucleic acid complex.

Shortly after infection of Escherichia coli B with T4 phage, the phage deoxyribonucleic acid (DNA) can be isolated as a fast-sedimenting, proteinaceous complex. Formation of the complex is inhibited by the addition of chloramphenicol between 3 and 4 min after infection, suggesting that phage-coded proteins are necessary to form the complex and may contribute to its structure. To determine whether the phage DNA is associated with a random collection of proteins after infection or whether the complex contained a specific set of proteins, total protein from phage-infected cell lysates was compared to complex protein isolated from similar lysates by gel acrylamide electrophoresis. The proteins obtained from complexes exhibited a distinctly different pattern of separation, indicating that the complex contained a specific set of those proteins newly synthesized after infection. The proteins of the complex appear to be associated directly with the DNA rather than with some other component which could impart the characteristic of fast sedimentation to the complex. Fast-sedimenting complexes were isolated from a (3)H-leucine-labeled cell lysate. Part of this material was treated with pancreatic deoxyribonuclease. Deoxyribonuclease-treated and untreated complexes were resedimented in sucrose gradients. Virtually all the untreated complex remained fast-sedimenting, whereas most of the (3)H-leucine label of the deoxyribonuclease-treated material was located toward the top of the gradient. These data suggest a direct association of DNA and protein in the complex.

Acrylates↗
PubMed1970

Incorporation of deoxyribonucleic acid precursors by T4 deoxyribonucleic acid-protein complexes retained on glass fiber filters.

Bacteriophage T4 deoxyribonucleic acid (DNA)-protein complexes were retained preferentially on glass fiber filters. DNA polymerase activity in the complex was detected through the incorporation of (3)H-labeled DNA precursors. The primer-product DNA hybridized with both phage and Escherichia coli DNA. Density labeling experiments showed that about 30% of incorporated (3)H-deoxyadenosine triphosphate was found in DNA which hybridized with phage DNA; this DNA was found to be covalently attached to the primer DNA.

Centrifugation, Density Gradient↗