Plasmid-like DNA is part of mitochondrial DNA inPodospora anserina

✍ Scribed by Ulrich Kück; Ulf Stahl; Karl Esser

• Publisher: Springer-Verlag
• Year: 1981
• Tongue: English
• Weight: 704 KB
• Volume: 3
• Category: Article
• ISSN: 0172-8083
• DOI: 10.1007/bf00365719

✦ Synopsis

As previously reported, a ccc DNA with a contour length of 0.75/~m and molecular weight of 2.4 kb (termed plasmid-like, plDNA) is the causative agent of senescence in the fungus Podospora anserina. Its postulated location in mtDNA was proved correct by the following experiments: 1. Restriction analysis of mtDNA resulted in different molecular weights for both, juvenile (95 kb) and senescent (30 kb) mtDNA. The construction of a detailed restriction map made evident the fact that senescent mtDNA comprises only a part of its juvenile counterpart.

2. Hybridization experiments (Southern blots) between

3H-labelled plDNA and mtDNA cleaved by restriction enzymes have shown that only certain parts of the juvenile mtDNA are homologous to plDNA. 3. Fine mapping experiments (construction of restriction maps and heteroduplex experiments) between plDNA integrated into a bacterial vector and its postulated equivalent, derived from juvenile mtDNA and also integrated into a bacterial vector, allowed a precise determination of the site of plDNA insertion within the juvenile mtDNA. All of these data fit into a previously published model in which, during aging, plDNA is excised from mtDNA and becomes autonomous for replication and function.