Maternal inheritance of mitochondria : Molecular mechanisms for preferential digestion of male mtDNA

线粒体包含它们自己的基因组，其在有性真核生物的不同分类群中通过单亲或母系传递，包括高等植物、苔藓、蕨类植物、藻类、真菌和动物，包括人类。众所周知，线粒体在许多物种中是严格母系遗传的。用4 '，6-diamidino-2-phenylindole（DAPI）对同花受精的多头绒泡菌（Physarumpolycephalum）的合子进行染色，发现在核融合后约1 h，一半线粒体类核（含mtDNA区域）的荧光同时减少，变成小斑点。再过30分钟后，荧光完全消失，而其他类核和所有线粒体鞘保持不变。单个受精卵细胞的PCR分析证实，缺失仅限于来自一个亲本的mtDNA。交配后60 h，空线粒体鞘逐渐消失。多配接类型 ...更多信息 在绒泡菌属中发生。在16个菌株与matA 1、matA 2、matA 11、matA 12、matA 15或matA 16的所有可能的杂交中检测mtDNA的传递模式。在39个60个十字架，严格的单亲遗传证实按照多等位基因matA的相对性层次。我们证实了扁石莼和宽叶蝇子草对来自一个亲本的mtDNA具有主动的、选择性的消化作用，这种主动的、选择性的消化作用可能是mtDNA单亲遗传的一种分子机制。我们通过DNA酶谱分析和非变性聚丙烯酰胺凝胶电泳（native-PAGE）和SDS-PAGE鉴定了两种新的核酸酶。一种是依赖于Ca^2+的高分子量核酸酶复合物（约670 kDa），另一种是依赖于Mn^2+的高分子量核酸酶复合物（440-670 kDa）;后者的活性在SDS-PAGE上以依赖于Mn^2+的13 kDa DNA酶条带检测。所有的线粒体分离出的myxamoeetrium有mt-类核，而一半的线粒体分离出的合子在12小时后混合失去了mt-类核。在两种菌株混合后至少8小时，检测分离的线粒体中Mn^<2+>依赖性核酸酶的活性。Mn^<2+>依赖的DNase活性的时间和位置与mtDNA的选择性消化相匹配。少

Mitochondria contain their own genomes, which are transmitted either uniparentally or maternally in diverse taxa of sexual eukaryotes, including higher plants, mosses, ferns, algae, fungi, and animals, including humans. Mitochondria are known to be inherited strictly maternally in many species. However, the molecular mechanism underlying uniparental inheritance remains unclear.When zygotes of the isogamous protest Physarum polycephalum were stained with 4',6-diamidino-2-phenylindole (DAPI), fluorescence from half of the total mitochondrial nucleoids (mtDNA-containing areas) decreased simultaneously to small spots about 1 h after nuclear fusion. The fluorescence disappeared completely after another 30 min, while the other nucleoids and all of the mitochondrial sheaths remained unchanged. PCR analysis of single zygote cells confirmed that the loss was limited to the mtDNA from one parent. The vacant mitochondrial sheaths were gradually eliminated by 60 h after mating. Multiple mating typ … More es occur in Physarum. Transmission patterns of mtDNA were examined in all possible crosses between 16 strains with matA1, matA2, matA11, matA12, matA15 or matA16. In 39 of 60 crosses, strict uniparental inheritance was confirmed in accordance with a hierarchy of relative sexuality of multiallelic matA. We have confirmed that active, selective digestion of mtDNA from one parent in Ulva compressa and Silene latifolia.The active, selective digestion of mtDNA from one parent is a possible molecular mechanism for the uniparental inheritance of mtDNA. We identified two novel nucleases using DNA zymography with native-PAGE and SDS-PAGE. One is a Ca^<2+>-dependent, high-molecular-weight nuclease complex (about 670 kDa), and the other is a Mn^<2+>-dependent, high-molecular-weight nuclease complex (440-670 kDa) ; the activity of the latter was detected as a Mn^<2+>-dependent, 13-kDa DNase band on SDS-PAGE. All mitochondria isolated from myxamoebae had mt-nucleoids, whereas half of the mitochondria isolated from the zygotes at 12 h after mixing had lost the mt-nucleoids. The activity of the Mn^<2+>-dependent nuclease in the isolated mitochondria was detected at least 8 h after mixing of two strains. The timing and localization of the Mn^<2+>-dependent DNase activity matched the selective digestion of mtDNA. Less