Cytological effects of infection with T5 and some related phages.

Luria and Human (1950) reported the cytological effects on Escherichia coli, strain B, of infection with the T-phages, excepting T5. This provided a more detailed description of the effects already noted by Luria and Palmer (1946) and by Delaporte (1948) who used T4. A study of T2r and T2r+ (Murray et al., 1950) provided little additional information. The observed changes were distinct for each serological group within the T series, and the effects in each group were constant. Rita and Silvestri (1950) have given a brief report of the cytological effects of all the T phages and come to the same conclusions. However, the indefinite descriptions and the lack of time relations do not allow strict comparison with the above studies. Concerning T5 they note the disappearance of nuclear structures in the infected cell and the appearance of fine chromatin granules, but the sequence of events is not clarified. Similarly, phase contrast (Boyd, 1949) and electron microscope (Wyckoff, 1948) studies of T5 infections do not give by themselves any definite information on structural changes in the host and require integration with a cytological study. The present communication concerns T5 (Demerec and Fano, 1945) and some of its serological relatives (Adams, 1952) acting on their various restricted and common host strains. The sequence of cytological changes to be reported is distinct from those produced by other members of the T series and, as far as we know, other phage systems. There is a probability that cytological characteristics provide an additional genetic marker for the study of this group.