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题名: 几种淡水寄生纤毛虫的系统发育研究
作者: 李明
答辩日期: 2008-06-14
导师: 汪建国
授予单位: 中国科学院水生生物研究所
授予地点: 水生生物研究所
学位: 博士
关键词: 寄生纤毛虫 ; 系统发育分析 ; 18S rDNA
其他题名: Studies on the phylogeny of some freshwater parasitic ciliates
摘要: 寄生纤毛虫作为一类重要的水产病害原生动物,可专性或兼性寄生在各种水产经济动物的鳃表、皮肤、肌肉或内腔系统中,对宿主造成直接或间接的危害。随着水产养殖规模的扩大和集约化程度的提高,此类病原虫对淡、海水养殖业造成的危害日渐引起人们的重视。然而,对此类群的一些基础性的研究工作如病原分类鉴定、系统发育关系等依然十分匮乏,严重制约了后续病害防控工作的开展。本论文以我国淡水寄生纤毛虫为主要研究对象,采用形态观察和分子数据相结合的方法,研究了几种病原纤毛虫各自的系统发育关系,主要结果和结论如下: 1.从杯体虫属名的厘定、形态结构与生活史、分类依据、虫体与宿主关系等四个方面全面整理了当今国内外有关本类群的研究资料。并对洪泽地区鱼杯体虫的活体、固定染色标本形态及其超微结构进行了较为系统的观察、描述。发现杯体虫体内尤其是口区具有很多细菌和有机颗粒,证明了其营养是来自于外界水环境而并非宿主,从杯体虫食物来源的角度论证了杯体虫是一种体外共生体而非体外寄生体。另外,还观察到虫体尤其是口围唇部的表膜具有非常明显的褶皱,显示了其口区表膜极强的伸缩能力,这也是虫体在受到刺激或形成游泳体时能将整个口围盘缩进体内的原因。 2.对鲩肠袋虫运用传统的形态学研究方法及扫描电镜和透射电镜技术对鲩肠袋虫的形态结构尤其是其复杂精细的皮层系统进行了深入的研究,提出皮层是由impenetrated dimension和superimposed dimension 两大系统构成的二维模型并就鲩肠袋虫的致病机制和传染途径进行了探讨。认为水体肠袋虫的传播途径可能有别于寄生于哺乳类的种类,是由鱼体肛门感染进入寄主。 3.对多泡肠袋虫从经典形态学和现代分子生物学两方面进行了再描述,在引入淡水鱼类来源肠袋虫(多泡肠袋虫、鲩肠袋虫)18S rDNA序列的基础上构建了毛口亚纲的系统发育树。认为肠袋虫属在系统发育上是并系发生,独立于Australian clade、Entodiniomorphida和绝大多数Vestibuliferians之外;认为肠袋虫属的分类地位有待提升。 4.在大鲵肠道发现肠袋虫一新种:大鲵肠袋虫和一新纪录:中华肠袋虫。之所以将大鲵肠袋虫定为一新种,是因为:(1)它的虫体大小不同于其它任何一种两栖类肠袋虫(有尾目或无尾目);(2)其体形近乎圆形,胞口显著狭长,从前端一直延伸到体横中轴;(3)其胞口的长宽比接近8:1,这与其他任何一种肠袋虫种类都明显不同。基于这些显著的不同,并依据其独特的宿主,将其命名为大鲵肠袋虫。这是首次有关寄生于隐鳃鲵亚目两栖类的肠袋虫的报道,填补了中国大鲵体内寄生原生动物研究方面的空白。 5.在黑斑蛙、泽蛙直肠内发现肠袋虫一新种,依据发现地点命名为洪湖肠袋虫。在对洪湖肠袋虫的形态特征进行描述的同时,还测定了该新种及中华肠袋虫的18S rDNA序列,并结合鱼类来源肠袋虫和相近物种的序列信息构建了分子系统发育树。再次证实肠袋虫属在系统发育上为并系发生,并主张提升肠袋虫属的分类阶元。 6.对鲤斜管虫的形态,尤其是其皮层银线系统进行了全方位的研究。对鲤斜管虫的18S rDNA进行了全序测定,并引入钩刺斜管虫和叶咽纲其他物种的序列信息构建分子系统发育树,探讨了斜管虫属的系统发生地位并对叶咽纲纤毛虫的系统发育模式进行了初步探索。
英文摘要: As an important group of the pathogenic protozoa, the parasitic ciliates can obligately or facultatively infect the gills, skins, muscles or internal organs of various aquatic animals and do harm to the hosts in varying degrees. Many reports indicate great losses in both freshwater and marine aquaculture industry caused by parasitic ciliates. However, our knowledge to this group remains in the stage of alpha taxonomy. Little attention has been given to the phylogenetic relationships of these ciliates. In this dissertation, the phylogeny of some freshwater parasitic ciliates with both morphological and molecular markers is studied. The main results and conclusions are summarized as follows: 1. The revision of the genus name, morphology and life-cycle, determination key, relationship between Apiosoma and their hosts were reviewed respectively. The morphology and structure of A. piscicola were well described and lots of bacteria and food particles were observed within the body of the organisms, especially around the peristomial disc. This phenomenon give a strong support from the aspect of food sources to the viewpoint that Apiosoma is a kind of ectocommensals but not ectoparasites. Twelve morphometric parameters were used to describe this peritrich in detail and comparisons were made with other reports. Its synonyms, Glossatella cylindriformis Chen, 1955 and Apiosoma magna Banina, 1968 were clarified based on reliable data. A. piscicola was still considered somewhat host-specific by us, especially to cyprinids, although it shows a quite wide limit of host variability. The telotroch was also observed, and its structures were described. Besides, the difficulties of the generic taxonomy were discussed and some suggestions were given. 2. Redescription of Balantidium ctenopharyngodoni Chen, 1955 collected from the hindgut of grass carp from Honghu Lake were well presented at both light and electron microscopic levels. Some revisions were done: the vestibulum is fairly symmetrical, with compactly arranged cilia rather than assembled membrane bordering on the left vestibular side; four contractile vacuoles actually exist in the latter body. Its fine structure was described in detail with an emphasis on its somatic cortex and vestibulum. A pattern of a two dimensional system that constitutes the elaborate cortex architecture was firstly put forward. Besides, the cysts of B. ctenopharyngodoni were observed, and its possible infection routes were also discussed. 3. The unique body shape of Balantidium polyvacuolum Li, 1963-highly arched dorsal side and flattened ventral surface as well as its remarkable concave platelet present in the centroventral were well described. Two types of vestibulum shape were observed, which may suggest the existence of two subspecies or genotype species of these balantidia. The 18S rDNA of B. polyvacuolum and B. ctenopharyngodoni were sequenced herein and phylogenetic analysis of the subclass Trichostomatia was conducted. The result indicated that the subclass Trichostomatia is monophyletic while the oder Vestibuliferida and Balantidium spp. showed their paraphyly. As to the phylogenetic position, the genus Balantidium should be recognized as a higher taxon. 4. Two ciliated protozoa, Balantidium sinensis Nie, 1935 and Balantidium andianusis n. sp., were isolated from the feces of a wild Chinese giant salamander (Andrias davidianus) captured from the mountainous area of Shiyan, Hubei Province, Central China in October 2006. The occurrence of B. sinensis in A. davidianus should be a new record because the type specimens were first discovered and named by Nie in 1935 from Rana nigromaculata and R. plancyi. B. andianusis n. sp. was considered to be a new species based on its unique morphological characteristics, especially the high length/width ratio of the vestibulum (8:1). Comparisons were also made among Balantidium species that were found from urodele amphibians. To our knowledge, it is the first report of Balantidium species inhabiting Cryptobranchoidea amphibians. 5. A new parasitic ciliate, Balantidium honghuensis n. sp., was discovered in the hindgut of R. nigromaculata and R. limnocharis and named after the type locality, Honghu Lake. Its morphology was well described and its 18S rDNA as well as that of B. sinenesis was also sequenced. The result of phylogenetic analysis indicated once more that the genus Balantidium is paraphyly and its phylogenetic position should be lifted to a higher taxon. 6. The morphology, especially the siliverline system of Chilodonella cyprini Moroff, 1902 was described at both light and scanning electron microscopic levels. Phylogenetic analysis was conducted by using 18S rDNA sequences, which contains C. cyprini, C. uncinata, T. stein and other 22 sequences of the class Phyllopharyngea. The result showed that the former three species fell in a single clade and nested within the order Chlamydodontida.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ihb.ac.cn/handle/342005/12398
Appears in Collections:中科院水生所知识产出(2009年前)_学位论文

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Recommended Citation:
几种淡水寄生纤毛虫的系统发育研究.李明[d].中国科学院水生生物研究所,2008.20-25
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