- Volume 37, Issue 1, 1977

Physicochemical properties of a virulent Lactobacillus phage, J1, and its DNA were studied. Phage J1 was shown to consist of a hexagonal head 55 nm in diameter and a flexible, non-contractile tail 290 nm in length and 10 nm in width. The buoyant density of the phage in CsCl was measured as 1.49 g/ml. It was found that J1 DNA was a linear duplex molecule with cohesive ends and had a contour length of 12.2 µm. The single strands were intact for the length of the molecule. The melting temperature, Tm, and the buoyant density of J1 DNA correspond to a G + C content of 48% and 45%, respectively.

The mol. wt. of the three double-stranded RNA (ds-RNA) components of Aspergillus foetidus virus S have been re-determined by using polyacrylamide gel electrophoresis (a) of native ds-RNA with ds-RNA standards and (b) of denatured ds-RNA with single-stranded RNA standards. Good agreement between the two methods and confirmation that the relationship between log mol. wt. and electrophoretic mobility of ds-RNA is not linear were obtained. The new mol. wt. values (4.0 to 4.2 × 106; 2.5 to 2.7 × 106 and 0.26 to 0.28 × 106, respectively) are significantly higher than those determined previously by linear extrapolation from reovirus ds-RNA standards.

Human diploid fibroblast cultures induced to make interferon by the combination of polyriboinosinic acid-polyribocytidylic acid, cycloheximide and actinomycin D degenerate thereafter, owing to the irreversible nature of the inhibition induced by actinomycin D. However, cultures superinduced with the DNA-dependent RNA synthesis inhibitor 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB) survive, owing to the reversible nature of the inhibition induced by DRB, and can again be superinduced on several occasions.