The Production of Inactive Phage P 22 Particles Following Induction ’ VANCE

Using an in vitro system for tail attachment, it is demonstrated that following ultraviolet (UV) induction of Salmonella typhimurium LT2 (P22) most of the particles formed lack a functional tail. This effect is found at all temperatures studied, but is more pronounced at temperatures of 37” and above. Similar results are described for thermal and spontaneous induction. Tailless particles are found following infection only at temperatures of 42” and above. Temperature pulse experiments on UV-induced lysogens suggest that late in the growth cycle tail synthesis is inhibited by high temperature. There is also an earlier temperature-sensitive step, which probably causes the production of inactive heads at 40”.