特殊涡鞭毛虫——尖尾虫染色体与典型涡鞭毛虫染色体的比较研究

我们实验室与上海细胞生物学研究所的有关同志多年来在特殊涡鞭毛虫──尖尾虫（Ｏｘｙｒｒｈｉｓｍａｒｉｎａ）的细胞生物学和生物化学上作了一系列的研究,本文所报道的是这些工作中的一部分。对尖尾虫（Ｏｘｙｒｒｈｉｓｍａｒｉｎａ）的永久浓聚染色体的精细形象以及不同固定方法对其精细形象的影响作了观察,并与人肠道细菌的类核体、典型涡鞭毛虫原甲藻（Ｐｒｏｒｏｃｅｎｔｒｕｍｍｉｃａｎｓ）和鞭毛虫眼虫（Ｅｎｇｌｅｎａｓｐ．）的永久浓聚染色体作了比较。结果表明,细菌的类核体的精细形象受固定方法的影响极大。反之,不同的固定方法对于眼虫染色体的精细形象则看不出有任何显著的影响。至于典型涡鞭毛虫类的染色体,单用ＯｓＯ４或用戊二醛－ＯｓＯ４双固定法固定,都会得到典型涡鞭毛虫类染色体的横带样结构,然而单纯用戊二醛固定,却会得到大不相同的形象。在这方面尖角虫的染色体与一般的涡鞭毛虫类的染色体相距甚远,其染色体的精细形象本身也与眼虫类的染色体较为相似,而与一般涡鞭毛虫类的大不相同。本工作所得到的结果与以前我们在不同方面所得到的结果一致。研究结果全都表明,失足虫与典型涡鞭毛虫有着一系列重大的差异,实际上代表着一个介于一般鞭毛虫类与典型涡鞭毛虫类

THE COMPARATIVE STUDY ON THE CHROMOSOMES OF Oxyrrhis marina AND TYPICAL DINOFLAGELLATE PAYING SPECIAL ATTENTION TO THE SYSTEMATIC POSITION OF THIS ORGANISM

Our laboratory and Shanghai institute of Cell Biology have done a series of works on the cell biology and biochemistry of special dimoflagellate, Oxyrrhis manna for many years.The present work is one amony them.The fine features of the constantly condensed chromosomes of the special dinoflagellate Oxyrrhis manna and the effects of different fixations on the fine featrues were observed and compared with those of the nucleoid of a species of human excrement bacteria, and of the constantly condensed chromosomes of a typical dinoflagellate Prorocentrum micans and a flagellate Euglena sp..Materials were fixed with glutaraldehyde (3%, PH7.0), OsO4 (1.5%, PH7.0), and glutaraldehyde-OsO4, respectively, The bacteria were also fixed with Ryter and Kellenberger's so-called "standard method". Ultrathin sections were made and stained with uranyl salt routinedly.The fine features of the bacterial nucleoid varied greatly depending upon the fixation methodes used (Figs. 1-5). On the contrary, the features of the condensed chromosomes of Euglena sp. showed no evident changes when different fixation methods were used (Figs. 6-8). As for the condensed chromosomes of typical dinoflagellate, P. micans, both OsO4 fixation and glutaraldehyde-OsO4 fixation gave the typical banding features of dinonagllate chromosomes (Figs. 10 and if), while glutaraldehyde fixation resulted in quite different features (Fig.9). Being quite different from the condensed chromosomes of common dinonagellates, the condensed chromosomes of the special dinoflagellate, oxyrrhiS manna,showed fine .features somewhat similar to those of the Euglena chromosomes. Different fixation methods did not give evident changes on the fine features of Oxyrrhis chromosomes either(Figs. 12-14).In this respect, O. manna chromosomes were similar to the condensed chromosomes of Euglena and distinct from those of other dinoflagellates.Lots of evidences in cell biology and molecular biology, that have been accumulated, indicated that Oxyrrhis is quite different from other dinoflagellates, but similar and closer to other flagellates. Oxyrrhis chromosomes are not dissolved when DNA: is removed; Oxyrrhis DNA does not contain hydroxymethyl uracil; Oxyrrhis chromatin contains histone-related protein and nucleosome-like particles; its nucleus divides by means of a special endomitosis,which is very different from the dinomitosis of typical dinoflagellates. The present work provides the differece in a new respect.All these facts indicate that oxyrrhis represents a special group of nagelles which link the common nagellates with dinoflagellates. A new phylum, Phylum oxyrrhinea, is suggested.This idea tallies with the result of the molecular evolution study of 245 rRNAs of Oxyrrhis and venous dinoflagellates (Lenares et al., 1991).