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

线粒体包含自己的基因组，在不同的有性真核生物分类群中，包括高等植物、苔藓、蕨类、藻类、真菌和包括人类在内的动物，这些基因组要么是单系遗传，要么是母系遗传。众所周知，在许多物种中，线粒体是严格由母系遗传的。然而，单代遗传的分子机制尚不清楚。用4′，6-二氨基-2-苯基吲哚（4′，6-二氨基-2-苯基吲哚（DAPI））染色抗生多头绒泡菌的受精卵时，半数线粒体类核（含mtdna区域）的荧光在核聚变后约1小时同时减弱为小斑点。再过30分钟，荧光完全消失，而其他类核和所有线粒体鞘保持不变。对单个受精卵细胞的PCR分析证实，这种损失仅限于来自一个亲本的mtDNA。交配后60 h，线粒体鞘逐渐消失。多交配类型，绒泡菌较多。在与matA1、matA2、matA11、matA12、matA15或matA16的所有可能杂交中检测mtDNA的传播模式。在60个杂交组合中，有39个根据多等位基因的相对性别等级确定了严格的单代遗传。我们已经证实，从一个亲本的活性，选择性消化mtDNA的压缩和沉默叶。来自亲本的mtDNA的主动、选择性消化可能是mtDNA单亲性遗传的分子机制。我们用native-PAGE和SDS-PAGE的DNA酶谱技术鉴定了两种新的核酸酶。一种是依赖Ca^<2+>的高分子量核酸酶复合物（约670 kDa），另一种是依赖Mn^<2+>的高分子量核酸酶复合物（440-670 kDa）；在SDS-PAGE上检测到后者的活性为Mn^<2+>依赖的13 kda dna酶带。黏性阿米巴分离的线粒体均具有mt-类核，而混合12 h后从受精卵分离的线粒体中有一半失去了mt-类核。分离的线粒体中Mn^<2+>依赖性核酸酶的活性在两株菌株混合至少8 h后检测。Mn^<2+>-依赖性dna酶活性的时间和定位与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