Superkiller yeast strain contains additional species of double-stranded RNA

A superkiller yeast strain, T158C, was found to contain four new species of ds RNA designated P3, P4, P5, and P6. The new components were found to have molecular weights of 880,000 daltons, 620,000 daltons, 500,000 daltons, and 330,000 daltons, respectively. The new species were shown to be double-stranded RNA by their resistance to pancreatic RNAse (E.C.3.1.4.22) in high salt and their sensitivity in low salt. Curing of the killer character by growth at high temperature resulted in the loss of P3–6 as well as M ds RNA. Since T158C is a superkiller, these new molecules may play an important role in the expression of the killer character.