Lehrstuhl für Allgemeine Botanik, Ruhr-Universität, Postfach 102148, D-4630, Bochum 1, Federal Republic of Germany.
Curr Genet. 1981 May;3(2):151-6. doi: 10.1007/BF00365719.
As previously reported, a ccc DNA with a contour length of 0.75 µm and molecular weight of 2.4 kb (termed plasmid-like, p1DNA) 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 (3)H-labelled plDNA and mtDNA cleaved by restriction 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.
如前所述，一种具有 0.75 µm 轮廓长度和 2.4 kb 分子量的 ccc DNA（称为质粒样，p1DNA）是真菌 Podospora anserina 衰老的原因。以下实验证明了其在 mtDNA 中的假定位置是正确的：1. mtDNA 的限制分析导致幼年期（95 kb）和衰老期（30 kb）mtDNA 的分子量不同。详细限制图谱的构建清楚地表明，衰老 mtDNA 仅包含其幼年期 mtDNA 的一部分。2. （3）H 标记的 plDNA 与 mtDNA 之间的杂交实验（Southern 印迹）用限制酶切割，幼年期 mtDNA 与 plDNA 同源。3. plDNA 整合到细菌载体中与其假定的等价物之间的精细作图实验（限制图谱的构建和异源双链实验），以及从幼年期 mtDNA 中获得的同样整合到细菌载体中的 plDNA 等价物，允许精确确定 plDNA 在幼年期 mtDNA 内的插入位点。所有这些数据都符合先前发表的模型，即衰老过程中，plDNA 从 mtDNA 中切除并变得能够自主复制和功能。
