Leukocytes recovered from birds inoculated with an oncogenic strain of Marek's disease virus synthesized deoxyribonucleic acid in vitro at a rate 7.9 times that of leukocytes from normal birds or birds inoculated with the nononcogenic herpesvirus of turkeys. A close relationship was observed between the level of in vitro deoxyribonucleic acid synthesis and in vivo tumor formation.

Deoxyribonucleic acid synthesis after ultraviolet irradiation was studied in wild-type, uvrA, recB, recA recB, and recA Escherichia coli strains. Inhibition of deoxyribonucleic acid synthesis, which occurs almost immediately after exposing the cells to ultraviolet radiation, depends on the functional gene recA.

An ultraviolet radiation-sensitive derivative of Streptococcus faecalis strain JH2-2 was isolated and found to be deficient in recombination, using a plasmid-plasmid recombination system. The strain was sensitive to chemical agents which interact with deoxyribonucleic acid and also underwent deoxyribonucleic acid degradation after ultraviolet irradiation. Thus, the mutant has properties similar...

Nucleoids from Salmonella typhimurium strain LT2 consist of supercoiled deoxyribonucleic acid structures that are ribonuclease labile sedimenting at 1,700S. More than 90% of the covalently closed circular deoxyribonucleic acid of a cryptic plasmid harbored by this strain cosediments with the host's 1,700S nucleoids.

Thirty-one Kanagawa-positive and -negative Vibrio parahaemolyticus isolates from patient stools and seafood were examined for plasmid deoxyribonucleic acid content, culture characteristics, and indices of pathogenicity. No significant correlation was found between plasmid deoxyribonucleic acid contents and indices of pathogenicity for the strains tested.

The presence of supercoiled deoxyribonucleic acid in the form of a relaxation complex is described for the antibiotic resistance plasmids R64, R28K, and R6K. The properties of these relaxation complexes indicate that they consist of a covalently closed circular deoxyribonucleic acid molecule associated with an activable, single strand-specific endonuclease.

Single-strand breaks in deoxyribonucleic acid of Escherichia coli B/r cells exposed to 20 krads of gamma radiation could be rejoined by incubation of irradiated cells in growth medium. In the presence of 0.25% phenethyl alcohol, this repair was completely inhibited although deoxyribonucleic acid and protein syntheses were suppressed only partially.

A modified transformation procedure that is effective for the introduction of plasmid deoxyribonucleic acid at high frequency into Salmonella typhimurium, as well as into Escherichia coli, is described. Transformed bacteria acquire a circular deoxyribonucleic acid species having the genetic and molecular characteristics of the transforming plasmid.

A series of petite mutants of Saccharomyces cerevisiae, generated after treatment for various times with ethidium bromide, was isolated, and the mitochondrial deoxyribonucleic acid size for each member was estimated. It was found that, as the treatment time with ethidium bromide was increased, the mitochondrial deoxyribonucleic acid isolated from the petite series was increasingly reduced in size.

Deoxyribonucleic acid replication and genetic recombination were investigated after infection of Escherichia coli with ligase-deficient rII bacteriophage T4D. The major observations are: (i) deoxyribonucleic acid synthesis is discontinuous, (ii) the discontinuities are more slowly repaired than in wild-type infection, (iii) host ligase is required for viability, and (iv) genetic recombination i...