纤毛类原生动物中宿主-共生体系统的研究

Studies on the Host-Symbiont System in Ciliates

目前已经在 10 0多种纤毛虫中观察到细菌、藻类和其他微生物等共生体。对纤毛虫中宿主 -共生体系统的研究表明 ,双小核草履虫中卡巴粒的遗传为细胞质遗传理论提供了例证 ;含细菌共生体的许多厌氧纤毛虫无线粒体 ,共生体对宿主代谢有重要作用 ;尾草履虫 -钝状全孢螺菌共生作用中 ,共生菌感染形式的 39kDa、15kDa周质蛋白可分别与IF 3 1、IF 3 2两种单抗反应 ,其共生体早期感染过程中两种抗原的量发生显著变化 ,并且共生体生殖形式选择性地合成 6 3kDa蛋白质 ,该蛋白质可能是与共生作用有联系的关键分子 ;绿草履虫 -小球藻共生系统中 ,共生藻中存在葡糖胺硬性壁是其与草履虫发生共生关系的基本条件 ,其中 ,共生藻参与宿主代谢 ,与宿主形成相互受益的专一性关系 ,并且藻类共生体的作用可能影响了宿主草履虫基因组有关结构 ,改变了其基因表达。作者推测 ,探索共生体对宿主基因结构及其表达产物的影响可能是对纤毛虫中共生作用研究的主要趋势 ,这对于深入了解真核细胞中宿主 -共生体双方的相互作用、物质交流在分子水平上的调控机理、细胞结构与功能的关系等细胞生命活动规律是有意义的。

To date, bacterial,algal and other microbial symbionts have been found in more than 100 species of ciliates. The study of the host-symbiont system in ciliates shows that: ( 1 ) The inheritance of kappa particles in the cytoplasm of Paramecium aurelia is a classic example of the cytoplasmic inheritance theory. (2) Bacterial symbionts in some anerobic ciliates that lack mitochondria play the major role in the host's metabolism. (3) In the P. Caudatum-Holospora obtusa system, 39- and 15-kDa periplasmic pro teins of the infectious H. Obtusa reacted with IF-3-1 and IF-3-2 monoclonal antibodies respectively. The amounts of both antigens were reduced during the early infection process. The reproductive H. Obtusa se lectively synthesized a 63-kDa protein, which may function as a key molecules in the various symbiotic systems. (4) In the P. Bursaria-Chlorella system, the precondition of the symbiosis may be the glu osamine composition that exists in the rigid wall of the algae. The symbiotic algae takes part in the host' s metabolism, and the specific association between the symbiont and host is mutually beneficial. Some ge nomic structures in P. Bursaria may be influenced by the function of the Chlorella,so that the host' s gene expression may change. A general trend in the research of symbiosis in ciliates is further exploration of the influence of the symbiont on the gene structure and gene expression of the host. The expected results will contribute to a better understanding of the regulatory mechanisms controlling the interaction,the exchange of substances between the host and symbiont at a molecular level, and the pattern of life processes surrounding the relationship between cellular structures and functions in eukaryocytes.