CYTOLOGICAL EFFECTS OF INFECTION WITH T5 AND SOME RELATED PHAGES

Abstract

Using current cytological methods, it was found that T5 and its relatives produce similar changes in the host cell during the 1st half of the latent period. The initial events were cessation of cell division; partial loss of cytoplasmic basophilia (mainly pentosenucleic acid); complete loss of stainable nuclear chromatin (mainly desoxypentose nucleic acid); and a progressive disruption of the nuclear sites. During the 2d half of the latent period (about 20 min. to lysis) synthesis of new nuclear chromatin started and progressed in the form of a finely granular core. This was true of all the phages, but some of them (the PB and Salmonella poona phages) formed spherical chromatin masses that were an additional characteristic. Studies of T5 X PB hybrids indicate that the intracellular arrangement of new chromatin is probably a hereditary phage characteristic. This may be of further aid in classification. Infections do not proceed beyond the initial (homogenous) stage if the host cells are deprived of Ca or if the host cells are infected with u.-v. inactivated phage.