Mutagene und inaktivierende Wirkung salpetriger Säure auf freie Partikel des Phagen T2

Abstract

T2 phages are inactivated by in vitro treatment with nitrous acid at pH 4.5. The inactivation follows first order kinetics with respect to the time of treatment. During the treatment a significant rise in plaque type mutants m, tu and r was observed. A detailed analysis of the r mutants revealed a linear increase with respect to the log of inactivation and the time of treatment. For a survival rate of 10^-4, 3% of the surviving particles give rise to r plaques. Approximately 30% of the plaques are mottled, the others are non-mottled. Nonmottled r mutants remain stable in subsequent passages. The mottled mutants segregate to yield about 50% stable r^- and 50% stable r and 0.05 to 0.1% mottlers. Control experiments demonstrate that inactivation and mutation are due to the action of nitrous acid and not to effects produced by the salt concentration or the pH of the incubation mixture. An increase of mutants by positive selection in the course of inactivation was experimentally excluded.