rnh mutations of Escherichia coli inactivating RNase H activity allow the initiation of rounds of DNA replication in the absence of protein synthesis (stable DNA replication). However, levels of RNase H did not change during or after the induction of stable DNA replication in rnh+ strains by incubation with nalidixic acid or UV irradiation.

DNA Replication↗

PubMed1980

Fate of plasmids containing Mu DNA: chromosome association and mobilization.

The fluorescent dye, diamidinophenylindole-dihydrochloride (DAPI) can be added to CsCl gradients to enhance the density resolution of DNA species, independent of their topological configurations. When Proteus mirabilis and Escherichia coli strains carrying an RP4::Mucts plasmid were examined with the use of such a technique, it was found that after thermal induction of the prophage essentially al of the plasmid DNA became associated with the chromosome. This quantitative association is detergent-RNase- and pronase-resistant and dependent on the expression of Mu genes. The association is temporally, and probably functionally, correlated with the onset of Mu DNA replication. Genetic studies with F'::mini Mu plasmids indicate that some of the association results in stable Hfr formation, and does not require the product of Mu gene B.

Amidines↗

PubMed1971

Bacteriophage P2: interaction with phage lambda and with recombination-deficient bacteria.

Explore the source record for details and available documents.

Bacterial Proteins↗

PubMed1970

Bacteriophage lambda; abortive infection of bacteria lysogenic for phage P2.

The efficiency of plating of wild-type lambda on a host lysogenic for P2 is less than 10(-6), and only a small number of infected cells produce progeny phage. Lambda can adsorb and inject its DNA normally in such cells; the DNA can circularize and is not nicked or degraded, but replication is severely impaired. Mutants of P2, which as prophages no longer interfere with lambda, have been isolated and found to be recessive to wild type, implying that P2 prophage codes for a diffusible product involved in lambda interference. The P2 gene product responsible for preventing lambda growth also kills recombination-deficient bacteria of the recB and recC classes under conditions where P2 does not normally kill the host. Mutants of lambda that are resistant to interference are recessive to wild-type lambda. Thus lambda actively participates in its own interference. The lambda-mutants that are resistant to interference are unable to synthesize at least two nonessential proteins. In addition, they are unable to grow on recombination-deficient bacteria of the recA class, but they can grow on recA recB double mutants.

Carbon Isotopes↗

PubMedDate not supplied

Transferable drug resistance in Pseudomonas patients with premature rupture of membranes in Ile-Ife, Nigeria.

Pseudomonas aeruginosa was cultured in eight patients with premature rupture of membranes in a Maternity Unit of the University of Ife Teaching Hospital Complex within a period of 48 h. Three of the strains were found to harbour R-factor DNA conferring high-level resistance to benzylpenicillin, streptomycin, chloramphenicol and tetracycline, while two strains are able to transfer this drug resistance en bloc to drug-sensitive Escherichia coli. The significance of this in the light of a continuing study of drug resistant bacteria in Ile-Ife is discussed.

Chloramphenicol↗