Tissue culture cells of a Rous virus-induced rat tumor undergo syncytium formation when placed in contact with mouse embryo cell cultures infected with murine leukemia viruses. This phenomenon can be used as a cytopathic end point for isolating and titrating these viruses in tissue culture. The principle should be applicable to detection of leukemia viruses of other species.

A mixed culture, WoAct, growing on acetone, consisted of two dominant morphotypes: a rod-shaped acetone-fermenting bacterium producing acetate, and an acetate-utilizing Methanosaeta species. Dense cell suspensions, largely free of the aceticlastic methanogen and supplemented with bromoethanesulfonate, were able to degrade acetone and grow in small volumes in membrane-separated culture devices i...