Cystine-independent Thermoresistant Mutants of Poliovirus.

vegetative cell, and the more slowly moving component proved to be the heat-resistant spore catalase. The two catalase-anticatalase arcs crossed each other, showing that the enzymes were antigenically distinct. Figure 1 shows a diagrammatic representation of the results of an analysis of sporulating-cell extract by use of the antigen trench method of Osserman (J. Immunol. 84:93, 1960). An earlier attempt to study the immunological specificity of B. cereus spore catalase (Sadoff, p. 180. In H. 0. Halvorson [ed.] Spores II, Burgess Publishing Co., Minneapolis, 1961) by immunodiffusion failed to demonstrate catalase activity in the antigen-antibody complex. Sadoff did, however, demonstrate the formation of heat-resistant catalase in the early stages of spore-formation in B. cereus, and presented evidence indicating that the heat-resistant and heat-sensitive catalases are quite distinct enzymes. To this finding, we would now add their lack of antigenic relationship as evidence for the existence of two structurally different molecular forms of catalase in sporulating cells of B. cereus.