【作者】 万永继；

【导师】 沈佐锐；

【作者基本信息】 中国农业大学 ， 农业昆虫与害虫防治， 2005， 博士

【摘要】 微孢子虫（Microsporidia）是一类专营细胞内寄生、无线粒体的单细胞真核生物,是昆虫、鱼类及哺乳动物的病原微生物。家蚕微粒子（Nosema bombycis Naegeli 1857）是人类最初认识的微孢子虫,由于能通过胚胎传染从母代传染危害子代而被列为检疫对象。近数年来我国蚕种生产由于微孢子虫的感染损失惨重,过去一直认为家蚕微粒子Nosema bombycis是唯一的寄生病原。本研究以四川蚕区为研究对象,对家蚕微粒子病及其病原的发生状况进行了流行病学研究,构建了时间流行曲线、病害管理模型和病原种类的地域分布,发现了其他寄生家蚕的微孢子虫的新种群,从家蚕体内分离出两种新型微孢子虫并进行了分类鉴定,即大型微孢子虫SCM₆（Nosema sp）和小型微孢子虫SCM₇（Endoreticulatus bombycis sp. nov.）。 大型微孢子虫SCM₆孢子卵园形,大小为3.91±0.25μm×2.56±0.28μm,极丝长度126±8.35μm;孢子双倍核,极丝绕核排列14～15圈,偶有16圈;发育过程具有裂殖体和孢子形成期,产孢体以二分裂形成两个孢子母细胞,然后形成成熟孢子,表现为Nosema属的发育特征;可寄生蚕体的多数组织,寄生程度以后部丝腺为重,但在中肠的寄生繁殖和孢子的形成较弱,生殖腺偶有寄生;胚传率低于家蚕微粒子Nosema bombycis 10倍以上,为1.44±0.75%,对蚕子代群体的发育无明显影响;生物学分类与家蚕微粒子Nosema bombycis同属异种,记录为Nosemasp。 小型微孢子虫SCM₇孢子卵园形,大小2.26±0.21μm×1.19±0.81μm,极丝长度39.90～60.18μm;孢子单核,极丝绕核排列7～9圈,裂殖体和孢子的发育均包被在宿主内质网膜形成的孢囊内,并在孢囊内形成许多孢子,表现为内网虫属Endoreticulatus的发育特征;只寄生中肠上皮组织,不感染生殖腺;无胚传致病性。分类检索表明该微孢子虫为一新种,鉴定记录为家蚕内网虫（Endoreticulatus bombycis sp nov）;其16S rRNA的核心序列为1230pb,与修氏内网虫Endoreticulatus schubergi有98%以上的同源性。 根据大型微孢子虫SCM₆和小型微孢子虫SCM₇弱度胚传和不胚传的特点,进一步研究制定了与家蚕微粒子Nosema bombycis不同的检验技术、母蛾的病率计算方法及合格标准,并成功地应用于疫区。据蚕种生产和检验机构反馈的应用结果,已挽回了大量的蚕种损失和巨大的经济效益。对家蚕病原性微孢子虫的新种群的研究取得了在理论和实践上的突破性进步,为国内外创新成果,解决了长期困扰我国蚕种生产的一个重大难题。 另一方面,从四川省阆中市蚕桑生态系统周围的林木害虫龙眼裳卷蛾幼虫体内发现分离到一种新的微孢子虫。孢子卵圆形（3.1±0.3μm×1.6±0.2μm）,孢子发育中呈现出八孢子囊孢和二孢子母细胞类型,为变形孢虫属的典型特征,分别形成单核孢子和双核孢子,极丝圈数分别为7～9圈和10～12圈;从宿主、大小、极丝、发育等的差异检索表明:为微孢子虫门变形孢虫属（Vairimorpha Pilly 1976）一新种,记录为裳卷蛾变形孢虫新种（Vairimorpha Ceracessp. nov.）。通过对裳卷蛾变形孢虫（Vairimorpha ceraces sp. nov.）转家蚕、鱼类的感染试验,本文研究了微孢子虫的感染生态问题。同时,对微孢子虫感染性变异机制研究的重要性进行了讨论。更多还原

【Abstract】 Microsporidia are lacking mitochondriate unicellular eukaryotes and all obligate intracellular parasites and infecting a wide range of vertebrate and invertebrate hosts such as insects and fishes and mammals. Microsporidum which was first discovered is Nosema bombycis Naegeli 1857 from the silkworm and it was established for quarantine objective because of transovarial transmission and pathogenetic to filial generation. My study first established its epidemic curve, control model and area distriating of pathogeny kinds. Before Nosema bombycis was considered only microsporidia pathogen of the silkworm but in my study new several kinds of microsporidia was found and isolated two species microsporidia from the silkworm in Sichuan China, the big spore SCM6(Nosema sp) and small spore SCM7(Endoreticulatus bombycis sp nov).SCM6(Nosema sp) fresh spores were oval in shape and 3.91±0.25 X 2.56±0.28μm in size. The mean polar filament length was 126 ± 8.23 μ m . Ultrastructural studies showed that the spore binucleate and the polar filament normally arranged in 14 or 15 coils and occasionally in 16 coils. The cycle of life include merogony and sporogony stages and the sporont a fusiform diplokayotic cell and change to spore and there shows Nosema Genus characteristic. The microsporidum can parasitic to many tissues of the silkworm and highly invaded into silk-glands, but merogony and sporogony were low in mid-gut and occasionally invaded into reproduction gonad. SCM6(Nosema sp) transovarial transmission rate only were 1.44±0.75% and lower 10 times than Nosema bombycis, No pathogenicity to the silkworms progeny. It is a new pathogenetic microsporidum in the silkworm and belongs to Genus Nosema in taxonomy and is recorded as Nosema sp.SCM7(Endoreticulatus bombycis sp nov) spores were ovoidal, 2.26 ± 0.21X1.19± 0.81 μm . The polar filament length was 39.90-60.18μm .The electroscope studies revealed that the spore uninucleate and the polar filament in single coil with 7~9 turns. All development stage is enveloped by parasitophorous vacuole from a double membrane of host endoplasmic reticulum and producing many spores and the developmental features were similar to Genus Endoreticulatus. The isolate only infects the midgut epithelial cell of the silkworm but no invade to reproduction gonad and no transovarial transmission to pathogenetic to progeny. The isolate was new species of microsporidum by taxonomy searching and is recorded Endoreticulatus bombycis sp nov. SCM7(Endoreticulatus bombycis sp nov) small subunit(16S) ribosomal RNA gene partial sequence has 1230pb and it have over 98% similarity to Endoreticulatus.schuerg.Because SCM6(Nosema sp) transovarial transmission rate only were 1.44±0.75% and SCM7 no transovarial transmission, the study lay down the inspection technique distinguishing from Nosema bombycis and counting method of the moth infecting rate andqualified rules of the silkworm eggs to the SCM6 and SCM7 , and the technique is applied to disease area . According to application report of the inspection organization, it retrieved how much loss of the silkworm eggs and tremendous economic result. The study took theoretical and practical breakthrough and is innovation production in home and international, and solved a great problem of the silkworm eggs production in China.Another, a previously undescribed microsporidum is isolated from the Cerace stipatana (Walker) in October 2000, in Langzhong, Sichuan province, China. We describe this microsporidium as a new species of Vairimorpha, and name it as Vairimorpha ceraces sp.nov. According to taxonomy system (Sprague 1992), it belongs to Phylum Microspora, Class Dihalophasea, Order meiodihalophasea, and Family Burenellidae. Type Host: Cerace stipatana Walker (Lepidoptera,Tortricoidea).Site of Infection: Infection to midgut epithelial and muscle cells, fat body, derma cell.Type Locality: LangZhong, Sichuan province(32 °N,105 °E),China. Prevalence of infection: Seventy-five of three hundred larvae, Cerace stipatana examined were infected (25%). Diagnosis: spore is ova更多还原