Two biochemically and genetically different forms of L dsRNA of Saccharomyces cerevisiae exist: One form, L2, is correlated.

Nucleic acid extracted from killer strains of Saccharomyces cerevisiae and run on agarose gels under sub-optimal conditions for M dsRNA yielded two species of L dsRNA (L1 and L2) which migrated at slightly different rates. L2 dsRNA was shown to be dependent upon MAK3, MAK10 and PES1 but not MAK1 nuclear genes for its maintenance. L1 was shown to be independent of all of these genes.[HOK] a non-Mendelian genetic element which enables a replication-defective M genome, [KIL-sd1], to be maintained in a SKl (+) host (Wickner and Toh-e 1982) was found to be present in an M-o derivative of the strain K7 which possesses L2 but not L1. Curing of L2 at elevated temperatures resulted in a co-curing of [HOK] and it is therefore concluded that either L2 is equivalent to or else it encodes [HOK].