Origin of mitochondria.
Origin of mitochondria.
复制标题
DOI：
10.1126/science.180.4085.516
复制
发表时间：
1973-05
期刊：
影响因子：
56.9
通讯作者：
T. Uzzell;C. Spolsky
中科院分区：
文献类型：
--
作者：
T. Uzzell;C. Spolsky
真核生物细胞器的起源是一个有趣的系统发育问题，这既是因为细胞器的古老性。真核生物和原核生物的分化，以及这些组织等级之间巨大的结构和功能差异。这是令人耳目一新的发现审查（1），反对广泛宣传的概念内共生起源的真核细胞器（2）。然而，我们感到，无论是支持还是反对内共生假说的人都忽视了系统学的一些原则。根据拉夫和马勒的观点，18亿年前的氧化红层之间的时间差（大气中游离O2的指示）和最古老的可能的真核生物化石（贝克斯普林斯白云岩，12亿至14亿年前）怀疑内共生假说。我们发现，在这个假设本身中，没有任何东西要求”真核生物在自由O2开始出现时获得有氧共生体。“原核生物的一般生化机会主义（见证他们目前的代谢多样性）表明，他们将迅速进化以利用这种02。然而，这些好氧原核生物是否会立即与生物化学上更受限制的原真核生物形成内共生关系，或者它们是否会立即开始进化成这样的生物体，目前还不清楚。无论是否是内共生的，真核生物都会跟随而不是先于O2释放到大气中。它们可能是在大约4 × 108年之后释放了足够的O2，这似乎与这两种假设都不矛盾。另一方面，考虑到在化石记录的早期区分小型原核生物和原核生物的困难，这两个事件可能比拉夫和马勒所指出的更接近同时发生。更重要的是，真核细胞不仅仅是具有线粒体的厌氧细胞（1，3）。如果可以证明细胞质中的有氧途径是真核生物直接从其原核生物祖先继承的原始特征，那么线粒体的内共生起源就不太可能了。原核生物和真核生物细胞质中存在的同源需氧途径（因此由核基因组编码）将由真核生物直接从需氧原核生物遗传
The origin of eukaryotic organelles is an intriguing phylogenetic question both because of the antiquity of. divergence of eukaryotes and prokaryotes and because of the enormous structural and functional differences between these grades of organization. It is refreshing to find a review (1) that opposes the widely publicized notion of the endosymbiotic origin of eukaryotic organelles (2). We feel, however, that some of the principles of systematics have been ignored by both those in favor of and against the endosymbiosis hypothesis.According to Raff and Mahler, the time lag between the 1.8-billion-year-old oxidized red beds (an indication of free O2 in the'atmosphere) and the oldest probable eukaryote fossils (Beck Springs Dolomite, 1.2 to 1.4 billion years ago) discredits the endosymbiosis hypothesis. We find nothing in the hypothesis itself that requires that" eukaryotes acquired aerobic symbionts as free O2 began to appear." The general biochemical opportunism of prokaryotes (witness their present metabolic diversity) suggests that they would quickly evolve to utilize this 02. That such aerobic prokaryotes would immediately thereafter enter into an endosymbiotic relationship with biochemically more restricted protoeukaryotes, or that they would immediately begin to evolve into such organisms, however, is not clear. Whether endosymbiotic or not, eukaryotes would follow rather than precede the release of O2 into the atmosphere. That they may have followed the release of sufficient O2 by some 4 X 108 years seems not in conflict with either hypothesis. On the other hand, given the difficulties of distinguishing small protoeukaryotes from prokaryotes in the early part of the fossil record, it is possible that the two events were more nearly simultaneous than Raff and Mahler indicate. More to the point is that eukaryotic cells are not just anaerobic cells with mitochondria (1, 3). If it can be shown that an aerobic pathway in the cytoplasm is a primitive feature of eukaryotes inherited directly from their prokaryote ancestors, then the endosymbiotic origin of mitochondria is less likely. A homologous aerobic pathway present hoth in prokaryotes and in the cytoplasm of eukaryotes (and therefore encoded by the nucl~ ar genome) would be inherited by the eukaryote directly from the aerobic prokaryotic