A mutation in the R body-coding sequence destroys expression of the killer trait in P. tetraurelia

Science  02 May 1986:
Vol. 232, Issue 4750, pp. 641-643
DOI: 10.1126/science.3008334


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.