A Mutation in the R Body-Coding Sequence Destroys Expression of the Killer Trait in <i>P. tetraurelia</i>

Abstract

This report describes a mutant strain of Caedibacter taeniospiralis 169 that does not produce refractile (R) bodies or kill sensitive paramecia, but still renders its host resistant to killing by wild-type strains of Caedibacter taeniospiralis. The mutation is due to insertion of a 7.5-kilobase, transposon-like element into the R body-coding region of the plasmid pKAP169. The results provide strong evidence that R body synthesis is required for expression of the killer trait.