【作者】 柳伟君；

【导师】 顾福康；

【作者基本信息】 华东师范大学 ， 动物学， 2009， 硕士

【摘要】 在腹毛目纤毛虫的分类学研究中,与细胞颜色有关的皮层色素颗粒已经引起了研究者的重视,将其作为形态学依据之一进行描述。但是,除了对腹毛目纤毛虫Trichototaxis songi取得了部分结果外,对于细胞颜色相联系的颗粒为什么长期保持下去,它在细胞皮层的定位、遗传及其在细胞生命活动过程中的作用关系尚未进行深入的探索。作者应用微分干涉相差显微术和扫描、透射电镜显微术,对腹毛目纤毛虫伪红色双轴虫(Diaxonella pseudorubra)观察,显示其细胞内含有大、小两种皮层色素颗粒,细胞质具有粘液泡类胞器。一、伪红色双轴虫的色素颗粒(1)在微分干涉相差显微镜下显示:细胞体呈红色或淡红色,细胞皮层存在红色色素颗粒和无色颗粒两种皮层颗粒。其中:在腹皮层右缘棘毛与中腹棘毛之间,中腹棘毛与左缘棘毛之间,以及两列左缘棘毛之间,大部分色素颗粒成线性松散的列;在背皮层,色素颗粒分布较不规则,颗粒的排布似与背触毛列无明显联系。高倍镜观察显示:其皮层色素颗粒为圆球形,可分为大、小两种:一种较大的颗粒直径大约0.5μm,另一种较小的颗粒直径大约0.2μm。也经常观察到几个或多个颗粒紧密排挤在一起形成念珠状的形态,这可能是颗粒连续分裂形成的图形(2)在透射电镜下显示:皮层颗粒呈低电子密度、圆球状,大部分以相互分离的形态聚集在较致密的细胞质内,或以串珠样排列在较致密的细胞质内。也观察到颗粒进行分裂的现象,其中:在大颗粒中心形成一个较高电子密度的分隔,把一个颗粒分割成两个部分,最终产生两个颗粒;或是在大颗粒经连续分裂产生小颗粒,形成如出芽样的图像。据结果认为,该纤毛虫的两种皮层色素颗粒可能有共同的起源,其颗粒呈现不同的大小可能与颗粒分裂的结果有关,可以肯定所述颗粒是与纤毛虫细胞颜色遗传有关的细胞器,但其功能尚需进一步的研究二、伪红色双轴虫粘液泡射出胞器(1)结构及定位成熟的粘液泡近圆球形,外围一层平滑的或呈波浪形的膜,内含晶状物质。粘液泡发生过程中,最初于细胞质深部致密的胞质内凹形成小泡,包围低密度的物质,形成早期的粘液泡,随着泡内物质电子密度逐渐变高,产生高电子密度的晶状物,发育为成熟的粘液泡。粘液泡成熟时晶状物质的分布密度发生变化,形成头端、体部和尾端三部分。成熟的粘液泡自头端以“阿米巴”样向表膜运动,前端膜与表膜融合,泡向表膜外发射泡内物质。(2)与其他纤毛虫粘液泡的区别特征伪红色双轴虫细胞质中存在粘液泡发射胞器,泡位于细胞质深部,成熟时可区分为头端、体部及尾端,泡内含有的晶状物及其胞器发射的形态等与大尾柱虫(Urostyla grandis)的同种胞器有相似之处,但与低等的纤毛虫四膜虫(Tetrahymena)等的粘液泡稳定存在于纤毛列及两表膜泡之间的情况不一样。而伪红色双轴虫的粘液泡在发射前,泡成波浪形,以“阿米巴”样运动到表膜,射出其泡内物质的过程,这一现象在大尾柱虫中则未观察到;联系扫描电镜显示在纤毛虫细胞皮层表面有时也存在一些圆球形颗粒状突起或与颗粒大小相似的凹陷的情况,在大尾柱虫扫描电镜的结果中也发现了这种情况,这很可能与胞器射出泡内物质后相应位置表膜未立即修复留下的射出痕迹有关。(3)可能的功能据伪红色双轴虫粘液泡发射、排出泡内物质后细胞表膜存在空洞的现象推测,粘液泡排出内容物后其膜结构已与表膜结构融合为一体,成为表膜的一部分,据结果认为伪红色双轴虫粘液泡的形成和排出过程对促进细胞内膜物质的流动和更新及表膜的更新具有物质贡献,同时也是一个加强细胞内物质新陈代谢的过程。小结与结论本文的工作为腹毛目纤毛虫细胞皮层色素颗粒与射出胞器的研究提供了较详细的形态学资料,所得结果对进一步阐明纤毛虫细胞结构的分化及其细胞结构与功能的关系,深入探讨纤毛目生命活动中胞器的发生、皮层结构的变化及细胞调控机理等具有学术意义。更多还原

【Abstract】 On the taxonomic studies of Hypotrich ciliates, the cortical Pigment Granule, which related to cell color, has attracted the attention of the researchers. And the distributions and shapes of these granules are always regarded as the morphological taxonomy evidence. At present, some researches about cortical pigment granule in Trichototaxis songi have been done. But a problem is why the pigment granule could inherit permanently, and the distribution, heredity and function in the cellular activities have not been discussed deeply. So in this dissertation, the cortical pigment granules and the cytoplasmic mucocyst of Hypotrichous ciliate Diaxonella pseudorubra were investigated by using differential interference contrast microscopy and TEM. And two kinds of pigment granules in the cortex and mucocysts in the cytoplasm have been observed.1 pigment granules(1) differential interference contrast microscopy showed that the cell present red or faint red colors, and there are two kinds of granules in the cortex, including red granules and colorless granules. A majority of pigment granules arrange in linear and incompact rows between RMC and MVC, MVC and LMC, 2 rows of LMC; in the dorsal cortex, the pigment granules distribute irregularly, and the distribution model of granules and dorsal kineties have no obvious correlation. High power lens showed that the pigment granules are spheroidal, which can be divided into two kinds with different size: diameter of the bigger one is 0.5μm, the smaller is 0.2μm. in addition, several granules arranged closely and formed moniliform, this probably is the graph which formed by the binary fission.( 2 ) TEM showed that the cortical granules present low electronic density and spheroidal, most of them get together or arrange in string beads in compact cytoplasm. And also the binary fission were observed, one of the manner is that a high electronic density diaphragm present in the big granule center, and separate the granule into two parts; another is that the big granule divided continuously, and produce many small granules.The results indicate that the two kinds of cortical pigment granule of Diaxonella pseudorubra might have common origin and bear relations with the heredity of ciliate color, the different size were form by different division models. And the further studies about the functions will still be needed.2 Mucocyst(1) Structure and distributionMucocysts look like an oval structure surrounded with a smooth membranous layer and containing crystal-like substances internally. In occurrence of mucocysts, some vesicles present in deep compact cytoplasm. These vesicles were surrounded by low density materials, and then become the mucocysts precursors. With the electronic density of substances increase, the precursors blossom into mature mucocysts. The distribution of the crystal-like substance changes and gradually the crystal-like substance forms three recognizable parts: head, body and tail. The matured mucocysts can move towards pellicle by means of "amebism" with their head ahead and fuse its head part plasma membrane with the pellicle. The fusion may result in an opening of mucocyst on the pellicle. Then the inclusion of mucocyst is extruded out of the organelle and finally the remaining empty mucocyst becomes part of the pellicle and can no longer be observed.(2) Characteristics different from the mucocysts found in other ciliatesIn Diaxonella pseudorubra cytoplasm, some mucocysts extrusomes present in deep compact cytoplasm. In addition, the mature mucocysts in Diaxonella pseudorubra can be divided into three parts: head, body and tail, while these morphological characteristics are similar to Urostyla grandis, but different to Tetrahymena. The mature mucocyst seemed to be undulated before extrusion. The mucocyst moved to pellicle by means of "amebism" and there the inclusion of mucocyst was extruded out. This progress is beried similarity to those observed in Urostyla grandis. In addition, the SEM showed that there are some spheroidal granular protuberances or hollows in the surface, while this phenomenon is also observed in Urostyla grandis. They must be the traces of the extrusion which have not been repaired immediately. The separate distribution of the developing mococysts of Diaxonella pseudorubra is obviously different from those ciliates such as Tetrahymena whose mucocysts are found to be located constantly in the pellicle region between ciliate lines and two alveoluses.(3) FunctionsThe appearance of some holes after mucocyst extruded suggests that mucocysts might take an important part in the physical activity in the Diaxonella pseudorubra. The extrusion process of mucocyst and the fusion of the membranous structure of mucocyst with the pellicle after extrusion indicate that mucocysts in Diaxonella pseudorubra could have some contribution to the pellicle renewal and material flow of the ciliate, and also promote the metabolism.3 conclusionsThe present study provides abundant morphological data for the investigation into extrusomes in protozoan ciliates. To sum up, the findings in this research are of significant scientific importance for the further elucidation of the specificity of cytoarchitectures and the relationship between the cytoarchitectures and their functions, the deep of the knowledge about the occurrence of organelles, the changes of cortical structure and the mechanisms of cell regulation in cellular activity of ciliates.更多还原