Functional analysis of ribosomes from eukaryotes possessing prokaryotic robosomes.

长期以来，人们一直认为原核和真核核糖体在功能和结构上存在离散差异。这些事实影响了真核生物是两种原核细胞融合的结果的概念。近年来，有报道称，一些寄生原囊藻也具有沉降系数与原核生物相似的核糖体。本研究以家蚕微孢子虫（Microsporidia Nosema bombycis）为材料，制备了沉降系数为70 S的核糖体组分和可溶性酶组分，并与大鼠肝和大肠杆菌的核糖体组分进行了比较，在ATP再生系统中，利用ATP酶的催化作用，对家蚕微孢子虫的核糖体组分和可溶性酶组分进行了分析，并与大肠杆菌的核糖体组分进行了比较。来自大肠杆菌和大鼠肝脏的核糖体依赖于外源添加的聚（U）而被活性地标记苯丙氨酸。然而，来自家蚕的核糖体几乎不掺入，如果有的话，改变细胞破碎或细胞分级分离的方法不能提高系统的活性。我们现在得出结论，材料，i。例如，家蚕休眠孢子不适合作为生物活性核糖体的来源，在本研究中，我们从家蚕基因组中克隆了包括HSP 70基因在内的一些基因。序列分析表明，在生物进化过程中，没有线粒体的bycis二次丢失了线粒体。N.bom

It has long been believed that there are discrete differences between prokaryotic and eukaryotic ribosomes in both function and structure. These facts have influenced on the concept that eukaryotes emerged as a result of fusion of two kinds of prokaryotic cells. Recently, it has been reported that some parasitic procysts possessed ribosomes with sedimentation coefficient similar to prokaryotic ribosomes. This project aimed to elucidate the origin of eukaryote by analyzing the function of the prokaryotic ribosomes from the eukaryotes.Ribosomal fraction and other soluble enzyme fractions were prepared from microsporidia Nosema bombycis whose ribosome has a sedimentation coefficient of 70S.Ribosomes from rat liver and Escherichia coli were also prepared for comparison.With ATP regeneration system, ribosomes from E.coli and rat liver were actively incorporatelabeled phenylalanine depending exogenously added poly(U).Ribosomes from N.bombycis, however, incorporated little, if any, labeled amino acids in any of the system examined.Alteration of cell disrupting or cell fractionation methods failed to improve the activity of the system. We now conclude that the material, i. e., dormant spores of N.bombycis, is not suitable for the source of biologically active ribosomes.During the course of this study, we cloned some genes including HSP7O gene from N.bombycis genome. The sequence analysis revealed that N.bom bycis which does not have mito-chondria lost mitochondria secondarily during the evolution of the organism.