Takano H, Mori K, Kawano S, Kuroiwa T
Department of Plant Sciences, Graduate School of Science, University of Tokyo, Hongo, Tokyo 113, Japan.
Curr Genet. 1996 Feb;29(3):257-64. doi: 10.1007/BF02221556.
A specific linear mitochondrial plasmid (mF) is genetically associated with the fusion of mitochondria in the true slime mould, Physarum polycephalum. In matings between mF+ and mF- strains, which respectively carry and do not carry the mF plasmid, mitochondrial fusion occurs in the zygote. Mitochondrial fusion induces recombination between specific sites in the mitochondrial DNA (mtDNA) and in the mF plasmid. To detect a region which is associated with the mitochondrial fusion in the mF plasmid, we isolated, by fluorescence microscopy, strains which showed defective mitochondrial fusion (delta mif-) from those which showed normal mitochondrial fusion (mif+). Analysis of the mitochondrial genomes of delta mif- strains showed only mtDNA which recombined with the mF plasmid in mitochondria. Comparison of this recombinant mtDNA in one delta mif- strain (NG 15) with that of a mif+ strain showed that a 2.2-kbp region, which included the integration site of the mF plasmid, was deleted in the delta mif- strain by recombination between the main mtDNA and the mF plasmid. In other strains, in addition to this deletion, a 6-kbp region which included both termini was deleted by recombination at six repeats of AAT sequences in the mF plasmid. Moreover, transcripts of the mF plasmid were not detected in NG15 by slot hybridization.
一种特定的线性线粒体质粒（mF）在真黏菌多头绒泡菌中与线粒体融合存在遗传关联。在分别携带和不携带mF质粒的mF⁺和mF⁻菌株之间的交配中，合子中会发生线粒体融合。线粒体融合会诱导线粒体DNA（mtDNA）和mF质粒中特定位点之间的重组。为了检测mF质粒中与线粒体融合相关的区域，我们通过荧光显微镜从表现出正常线粒体融合（mif⁺）的菌株中分离出表现出线粒体融合缺陷（δmif⁻）的菌株。对δmif⁻菌株的线粒体基因组分析表明，线粒体中仅存在与mF质粒重组的mtDNA。将一个δmif⁻菌株（NG 15）中的这种重组mtDNA与一个mif⁺菌株的进行比较，结果显示，在δmif⁻菌株中，一个包含mF质粒整合位点的2.2千碱基对区域通过主mtDNA与mF质粒之间的重组而缺失。在其他菌株中，除了这种缺失外，一个包含两端的6千碱基对区域在mF质粒中AAT序列的六个重复位点处通过重组而缺失。此外，通过狭缝杂交在NG15中未检测到mF质粒的转录本。
