Thraustochytrium caudivorum--一种香港牡蛎新型原生生物寄生虫  

Thraustochytrium caudivorum-a new protozoan parasite in Crassostrea hongkongensis

作　　者：刘坤娜 毛帆[1] 张翔宇 林玥 张扬[1] 喻子牛[1] LIU Kunna;MAO Fan;ZHANG Xiangyu;LIN Yue;ZHANG Yang;YU Ziniu(CAS Key Laboratory of Tropical Marine Bio-resources and Ecology,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院南海海洋研究所中国科学院热带海洋生物资源与生态重点实验室,广东广州510301 [2]中国科学院大学,北京100049

出　　处：《海洋通报》2021年第1期53-61,共9页Marine Science Bulletin

基　　金：国家自然科学基金(31572640,31572661)。

摘　　要：破囊壶菌(Thraustochytrids)是一类具有分解作用的海洋异养原生生物。研究表明破囊壶菌可对软体动物、海洋扁虫类造成消耗性疾病。本研究从发病的牡蛎鳃组织中分离出一种未在牡蛎中记录过的破囊壶菌寄生虫,经形态学及分子生物学分析后,鉴定为一种破囊壶菌寄生虫Thraustochytriu caudivorum。利用倒置显微镜和激光共聚焦超高分辨系统观察到T.caudivorum的生活史可分为游动孢子、营养细胞、孢子囊和变形虫四个阶段。游动孢子沉降成营养细胞,营养细胞再通过二分裂或形成孢子囊的方式释放不动的和可游动的孢子。破囊壶菌的形态大小变化迥异,本研究利用流式细胞仪和共聚焦系统探究了不同盐度对细胞大小的影响。结果表明,随盐度增大,体积小的细胞占比增多;在盐度为15 ppt时,细胞增殖缓慢,体积变大;而在盐度为20和25 ppt时,细胞体积变小,增殖速率加快。25 ppt盐度条件下,游动孢子数目最多。本研究首次从香港牡蛎鳃组织中分离出T.caudivorum寄生虫,并确立了其与破囊壶菌其他属之间的系统发育关系。Thraustochytrids,as an important marine decomposer,is a kind of marine heterotrophic protists.Previous studies have shown that some members of thethraustochytrids may cause severe wasting diseases in mollusks and flatworms.A potential new parasite was isolated from pathogenetic oysters'gill tissue.After identified by morphological and molecular biological methods,it was found as Thraustochytrium caudivorum.Additionally,four stages of T.caudivorum life history,zoospores,vegetative cells,the sporangia and the amoeboid stage were observed by optics inverted microscope and laser scanning confocal microscopy.Zoospores settled on the substrate and formed vegetative cells.The vegetative cells underwent binary fission or developed to sporangium for releases of the immobile and mobile zoospores.As the cell size of T.caudivorum varied greatly,the effects of different salinities on cell size using flow cytometry and con-focal microscopy were also investigated.The results show that the proportion of small cells increased in a salinity-dependent manner.At the salinity of 15 ppt,the proliferation rate was slow with a large cell in size,while cell size got smaller and the proliferation rate was accelerated at the salinity of 20 and 25 ppt.At the salinity of 25 ppt,the maximum number of zoospores was found.This is the first detailed observation and analysis of T.caudivorum parasite isolated from the tissues of HongKong oysters and the relationship between the isolated T.caudivorum and other genera of Thraustochytrids has been established.

关 键 词：破囊壶菌 Thraustochytrium caudivorum 牡蛎鳃组织 寄生虫 

分 类 号：P735[天文地球—海洋生物学] Q18[天文地球—海洋科学]