MULTIPLE DELETIONS IN MITOCHONDRIAL-DNA ARE PRESENT IN SENESCENT MOUSE-BRAIN

We report for the first time that multiple deletions occur during agei ng of mice brain mitochondrial DNA (mtDNA). Deletions were detected by electrophoresis after amplification using the nested Polymerase Chain Reaction (N-PCR) method. Three mutant mtDNAs with 3726-, 3867- and 42 36-bp deletions were directly detected by were undetectable in young b rain mice. Each deletion was sequenced : containing the junction fragm ent three different repeats of 13, 14 and 15 bp These results support the hypothesis that direct repeats are an initiating factor ageing-ass ociated accumulation of deletion. (C) 1994 Academic Press, Inc.