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，这些基因组在真核生物的不同分类群中单亲或母体传播，包括高等植物、苔藓、蕨类、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。然而，单亲遗传的分子机制尚不清楚。用4‘，6-二氨基-2-苯吲哚(DAPI)染色多头绒泡菌受精卵时，核融合后约1h，半数线粒体核仁(含mtDNA的区域)的荧光同时减弱为小斑点。30min后荧光完全消失，而其他核团和所有线粒体鞘均无变化。对单个受精卵细胞进行的聚合酶链式反应分析证实，这种缺失仅限于来自亲本的mtDNA。交配后60h，线粒体鞘逐渐消失。多种交配类型的…泡囊藻属的ES较多。在16个菌株与matA1、matA2、matA11、matA12、matA15或matA16的所有可能的杂交中检测了mtDNA的传播模式。在60个杂交组合中，有39个组合的严格单亲遗传符合多等位基因MATA的相对性别等级。我们已经证实，从扁穗石榴和宽叶石杉中的一个亲本中主动、选择性地消化mtDNA。从一个亲本中主动、选择性地消化mtDNA可能是mtDNA单亲遗传的分子机制。我们用DNA酶谱结合Native-PAGE和SDS-PAGE鉴定了两种新的核酸酶。一种是依赖于钙的高分子量核酸酶复合体(约670 kDa)，另一种是依赖于锰的高分子量核酸酶复合体(约440-670 kDa)，后者的活性在SDS-PAGE上显示为一条依赖于锰的13 kDa的DNA酶带。从粘阿米巴分离的线粒体全部有Mt-核，而在混合后12h从受精卵中分离的线粒体有一半丢失了Mt-核。在分离的线粒体中，两种菌株混合至少8h后，检测到依赖于Mn2的核酸酶的活性。依赖于Mn2&gt；的DNA酶活性的时间和位置与线粒体DNA的选择性消化相匹配。较少

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