MULTIPLE ORIGINS OF ANAEROBIC CILIATES WITH HYDROGENOSOMES WITHIN THE RADIATION OF AEROBIC CILIATES
MULTIPLE ORIGINS OF ANAEROBIC CILIATES WITH HYDROGENOSOMES WITHIN THE RADIATION OF AEROBIC CILIATES
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DOI：
10.1098/rspb.1995.0180
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发表时间：
1995-10-23
影响因子：
4.7
通讯作者：
WILLIAMS, AG
中科院分区：
文献类型：
--
作者：
EMBLEY, TM;FINLAY, BJ;WILLIAMS, AG
一些纤毛虫生活在厌氧环境中，缺乏线粒体，但拥有氢酶体：含有氢化酶并产生氢的细胞器。氢化酶体的起源有两种相互竞争的假说：（i）它们是生化修饰的线粒体;或（ii）它们来自具有氢化酶体生物化学的纤毛虫和厌氧真细菌的内共生体。系统发育分析的代表性好氧，厌氧hydrogenosomal纤毛虫使用主机核SSU rDNA序列表明至少有三个，但更有可能是四个，独立的起源hydrogenosomes。虽然这并不能反驳这两种假设，但多重趋同内共生的不可信性进一步支持了纤毛虫中的氢化酶体来自现有细胞器的观点，超微结构证据表明这是一种细胞器。我们的研究结果表明，一组主要是好氧真核生物的生理生化可塑性相当大的潜力，并提供了一个系统发育框架，以进一步完善和测试的氢酶体的起源的假设。
Some ciliates live anaerobically and lack mitochondria, but possess hydrogenosomes: organelles that contain hydrogenase and produce hydrogen. The origin of hydrogenosomes has been explained by two competing hypotheses: (i) they are biochemically modified mitochondria; or (ii) they are derived from endosymbiotic association(s) of ciliates and anaerobic eubacteria that possessed the hydrogenosome biochemistry. Phylogenetic analyses of representative aerobic, and anaerobic hydrogenosomal ciliates using host nuclear SSU rDNA sequences indicate a minimum of three, but more likely four, separate origins of hydrogenosomes. Whereas this does not refute either hypothesis, the implausibility of multiple convergent endosymbioses gives further support to the view that hydrogenosomes in ciliates derive from an existing organelle, which ultrastructural evidence suggests is the mitochondrion. Our results indicate a considerable potential for physiological-biochemical plasticity among a group of predominantly aerobic eucaryotes, and provide a phylogenetic framework to further refine and test hypotheses of the origins of the hydrogenosomal enzymes.