【作者】 王正君；

【导师】 倪兵； 顾福康；

【作者基本信息】 华东师范大学 ， 动物学， 2010， 硕士

【摘要】 目前,以皮层纤毛器为主要结构成分研究纤毛虫皮层细胞骨架的形态和形态发生,已经成为细胞生物学领域探索真核细胞结构的遗传及细胞调控的热点；以纤毛虫细胞质中的一些特殊胞器为观察对象显示其特殊的生物学功能,也成为揭示真核细胞结构与功能多样性的重要内容。三缘双轴虫(Diaxonella trimarginata)是一类细胞结构特殊的腹毛目纤毛虫,其皮层细胞质除具有其他纤毛虫中常见的细胞器外,还具有色素颗粒及射出胞器等结构。对三缘双轴虫的研究尚局限于光镜水平,并且其系统分类地位也一直备受争议。本文以腹毛目纤毛虫三缘双轴虫为研究材料,应用扫描电镜技术对无性生殖时期皮层纤毛器的形态及形态发生过程进行了系统的观察,得到了一些细节特征,并取得了新的结果；应用透射电镜技术揭示三缘双轴虫细胞皮层微管胞器及细胞质的超微结构特征。本文旨在从细胞皮层超微结构、细胞骨架体系以及细胞质超微结构等不同方面对三缘双轴虫进行多方位的探索,现将结果报告如下：1皮层纤毛器的形态与形态发生扫描电镜显示,在口围带、波动膜以及相应皮层区域形成小膜侧向纤毛结构及独特的口盖结构,额棘毛具有典型的全列虫科模式,腹棘毛以棘毛对的形式组成“zig-zag”中腹棘毛列；横棘毛10-13根,前面5根与后面5-8根以“√”方式排布；左缘棘毛3-4列,偶见5列,从右至左依次变短,其中有1列左缘棘毛绕到背部与背触毛相邻排列。右缘棘毛恒为1列,左右缘棘毛在尾部不交汇；背触毛3列,偶见4列,纵贯全身。背触毛单元由一个长纤毛的毛基体构成。形态发生时前仔虫口围带在老口围带内侧形成,最终老口被完全取代,后仔虫口围带原基在中腹棘毛列左侧开始形成,经过发育、分化、成熟最终形成后仔虫的新口围带。左缘棘毛原基在最右侧的老左缘棘毛列中开始发生,逐步分化成3列原基,最终完全取代老左缘棘毛。纤毛器形态发生过程中出现了部分老纤毛器结构退化、瓦解,为新纤毛器的定位提供物质贡献的现象。上述结果从超微结构水平显示了三缘双轴虫皮层纤毛器的形态及形态发生特征,为深入了解三缘双轴虫的细胞发育提供了新的资料,对进一步探索细胞分化及纤毛模式的形成机制是很有必要的。2细胞皮层骨架及细胞质的超微结构观察扫描电镜技术揭示了三缘双轴虫的形貌特点,包括皮层纤毛器的形态及形态发生特征。但是对三缘双轴虫内部超微结构的了解甚少,因此应用透射电镜技术对三缘双轴虫进行内部超微结构的探索对于构建皮层细胞骨架的三维图形、丰富形态学相关资料都有很重要的意义。透射电镜显示,三缘双轴虫的表膜下存在由单根微管间接排列组成的微管加固层以及与表膜近乎平行排列的纤维束,推测其可能有加固表膜的作用；在细胞质的食物泡一侧有长条状的微管骨架结构,可能与微管的合成相关；三缘双轴虫中与微管骨架相邻的位置有细菌状结构物质存在,极有可能属于细菌共生体的一种,与三缘双轴虫共同构成互惠共生体系；皮层细胞质中的食物泡及粘液泡周围常常分布着丰富的线粒体结构,这可能与粘液泡发射过程以及食物泡消化过程中需要消耗大量的能量有关；细胞核为两型性,大核通常具有一至多个核仁,其中有的大核具有环状核仁,小核无核仁；染色质呈均一性分布于大核中,排列较疏松,染色质之间相互聚集形成高电子致密度的团块状结构,有的染色质与核内膜紧密相连,小核中的染色质具有均一的电子致密度,均匀分布于核内。在口区,每个口围带小膜均由3列纤毛组成,其中2列近长,1列较短,相邻口围带小膜之间有膜泡样的膈结构将其隔开,此特征与扫描电镜观察的结果相吻合。表膜下的围棘纤维篮由纤维环所包被,围棘纤维篮容纳部分纤毛杆以及毛基体,其超微结构在横切面上差异不大,围棘纤维篮的周围维管束以及基体下维管束有利于保持细胞骨架的稳定性；背触毛单元在透射电镜下显示出裸毛基体结构,而此结构在扫描电镜下并未观察到。上述结果进一步丰富了三缘双轴虫的细胞学资料,为构建三缘双轴虫的三维图形提供了相关数据。更多还原

【Abstract】 At present, studies on the morphology and morphogenesis of the ciliate cortical cytoskeleton have already been the hot issue in exploring the eukaryotic genetic and cell regulation in the field of the cell biology. The observation of some special organelles in the cytoplasm to show the unique biological functions of the ciliate have also been the main topic of revealing the diversity of the eukaryotic structure and functions. Diaxonella trimarginata has the special cell structure, including the common organelles like the other ciliates and the special organelles like the pigment and the extrusome. The methods nowadays are mainly confined to the light microscopy level, at the same time, some related taxonomic problems are on the air all the time. In my research, Scanning Electron Microscopy(SEM) was used to systematically observe the cortex ciliature morphology and morphogenesis of hypotrichous ciliate Diaxonella trimarginata during the asexual reproduction. Meantime, Transmission Electron Microscopy(TEM) was used to reveal the morphologic characteristics of cortical mircrotubular organelles and the cytoplasmic ultrastructure. The research was mainly studied from three aspects:cortical ultrastructure, cytoskeleton systems and cytoplasmic ultrastructure. The results are as follows:1 The morphology and morphogenesis of cortex ciliatures(SEM)The results of the research investigated by SEM show that lateral membranellar cilia(LMC) and unique buccal seal exist at the area of AZM, paroral membrane(PM) and relative cortex. Diaxonella trimarginata is assigned to Holostichidae because it has three frontal cirri and the midventral complex is composed of cirral pairs.10-13 transverse cirri arranged in J-shape pattern. There are 3-4 left marginal rows which shorten incrementally from right to left and 1 right marginal row, one of the left ones lies beside the dorsal kinety. Usually 3 dorsal kineties extend entire length of cell and the unit of the dorsal kinety is composed of one cilia kinetosome. During the process of morphogenesis, the oral primordium of the proter is generated on the inner margin of the old AZM, the old AZM is finally resorbed completely. The formation of the oral primordium of the opisthe commences from the left field of the midventral pairs, with the process of proliferation and differentiation, the oral primordium is finally developed into new AZM of opisthe. Left marginal cirri primordium originates in the rightmost parental left marginal row, forming the 3 streak-like anlagen later and finally the newly structure replaced the parental rows. During the morphogenesis of ciliature, the old cilia experienced the process of gradual degeneration and at the same time provide the necessary nutrition for the new structure. In a word, the results above show the morphology and morphogenesis characteristics on cortex ciliature of Diaxonella trimarginata from the ultrastructure level, and also provide new references for a better understanding of the cell development as well as the formation mechanism of the cirri mode and the cell differentiation.2 The ultrastructure of the cortical cytoskeleton and cytoplasm(TEM)Morphology and morphogenesis characteristics of the cortex ciliature are usually revealed by SEM. However, There are few records on the ultrastructure of Diaxonella trimarginata. Therefore, it is quite necessary to do some research on the ultrastructure of Diaxonella trimarginata. The results are as follows:(1) There are micro tubule layers and fiber bundles underneath the cell pellicle.(2) Some kinds of microtubule cytoskeleton structure lies beside food vacuole.(3) Near to the microtubule cytoskeleton structure exist a bacteria-like structure.(4) There are plenty of mitochondrion surrounding food vacuole and mucocyst.(5) The nuclear apparatus is consisted of macronuclei and micronuclei. There are usually at least one nucleoli in the macronuclei, some macronuclei have circle nucleoli, all the micronuclei have no nucleoli. The chromation distributed evenly in the macronuclei, some chromation connected tightly with the inner nuclear membrane. The chromation in the micronuclei distributed as evenly as that in the macronuclei. (6) Among the adroal zone of membranelles, each membranelle consists of 3 rows cirri, membranellar bolster lies between the neighboring membranelles. This is also observed by SEM. (7) Each kind of cirri has a specific shape at its base, some basal bodies and some cirri are incorporated into the fibrillar cirral basket, the ultrastructural characteristic of them in transverse section is almost the same, many microtubules bundles around the fibrillar cirral basket play a very important role in keeping the stability of the cytoskeleton. (8) The unit of the dorsal kinety is composed of the cilia kinetosome and the naked kinetosome, the latter one can’t be observed in the SEM specimen.The results above not only enrich the cytological references, but provide corresponding data for the construction of the three-dimensional graphics.更多还原