Polymorphic variations in the ori sequences from the mitochondrial genomes of different wild-type yeast strains

Summary We determined the restriction maps and primary structures of two as yet poorly characterized regions of the mitochondrial genomes of different wildtype strains of Saccharomyces cerevisiae. These regions respectively comprised the ori1 sequence and the newly identified ori8 sequence. Ori1 and ori8, together with their flanking sequences, exhibit a large polymorphism, resulting from specific variations due to insertions or deletions of optional GC clusters at different locations. The mechanisms underlying such sequence rearrangements are discussed.