title: Rat mitochondrial DNA polymorphism: sequence analysis of a hypervariable site for insertions/deletions.
abstract: Three closely related variants of rat (Rattus norvegicus) mtDNA have been shown to differ in the number of T residues found in a run of Ts (light strand) which spans the junction between the tRNACys and tRNATyr genes. The number of Ts in the repeat varies from 6 to 8 in these DNAs. Another, less closely related, R. norvegicus variant has a run of 5 Ts at this site and in the related species, Rattus rattus, a run of 4 Ts is found. In R. norvegicus mtDNA runs of 5 As and 5 Gs are found just to the 3' side of the variable T repeat, and it is suggested that the three runs of repeated nucleotides may stabilize heteroduplexes which result from strand slippage and which give rise to the insertions and/or deletions. Among 17 mtDNA clones derived from an individual with the 8T repeat, one clone was found which possessed a 9T repeat. This variant may represent an additional DNA type originally present within the individual.
mesh_terms: D000818:Animals; D001483:Base Sequence; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004251:DNA Transposable Elements; D004272:DNA, Mitochondrial / Q000235:genetics*; D014644:Genetic Variation; D007668:Kidney / Q000032:analysis; D008928:Mitochondria / Q000032:analysis; D008930:Mitochondria, Liver / Q000032:analysis; D011110:Polymorphism, Genetic; D051381:Rats; D013045:Species Specificity
chemical_list: D004251:DNA Transposable Elements; D004272:DNA, Mitochondrial; D004262:DNA Restriction Enzymes