养殖大菱鲆蟹栖异阿脑虫病及其防治研究

对目前我国大菱鲆养殖过程中普遍发生的一种重要疾病———盾纤毛虫病的防治进行了较为全面地研究。描述了流行病学特征、病原形态学特点及分类地位,进行了主要环境因子对病原纤毛虫生存、生长的影响以及药物对纤毛虫的体外杀灭实验,并对实验室筛选的高效、低毒药物进行了临床治疗实验。研究结果表明,大菱鲆盾纤毛虫病的病原为蟹栖异阿脑虫(MesanophryscarciniGroliere&Leglise1977),属于广温、广盐、偏酸性食腐种类。多种药物对虫体的杀灭实验表明,甲醛、双氧水和复方中草药‘盾纤虫清’对该虫有较好杀除效果。甲醛溶液在3·1×10-5浓度下,7h可以杀死盾纤虫,双氧水在6·2×10-5浓度下,30min可杀灭虫体。另外,口服中草药‘盾纤虫清’(5g/kg饵料的添加量)显示出良好的治疗效果,为实际生产中防治盾纤虫病提供了理论依据。     

养殖大菱鲆蟹栖异阿脑虫感染及其危害

从养殖大菱鲆（Scophthalmus maximus）患病鱼体中分离出一种寄生性纤毛虫，通过活体观察、碳酸银法染色和扫描电镜对其形态学进行特征分析。经鉴定，该纤毛虫为蟹栖异阿脑虫（Mesanophrys carcini Groliere ＆ Leglise，1977），隶属于寡膜纲、盾纤目、嗜污科、异阿脑虫属。患病鱼常表现为静伏池底，体色变暗，活力弱，摄食差，生长减慢，并发生急、慢性死亡。最明显的特征是病灶部位变白，略有浮肿，触摸柔软。流行病学特征显示，在大菱鲆的苗期、养成期、亲鱼培育期均可发生纤毛虫感染，幼鱼期发生率较高，发病水温14-20℃，盐度12～40。组织病理学观察分析表明，病灶组织处以盾纤虫为主要入侵微生物，常伴有细菌存在，但没有发现病毒性细胞病变和霉菌等其他寄生生物。     

Isolation,characterization and virulence of Mesanophrys sp. (Ciliophora: Orchitophryidae) in farmed swimming crab (Portunus trituberculatus) in eastern China

A disease outbreak occurred in swimming crab (Portunus trituberculatus) farmed in eastern China, with a mortality rate of more than 80%. To further investigate the characteristics and pathogenesis, we reported isolation, characterization and virulence of the causative agent of this disease from 10 sick crabs. Histopathological observation found that multiple tissues, especially haemolymph, contained lots of ciliates. The ciliate was isolated and cultured in vitro, and molecular and morphological studies were done. The results showed that SSU rDNA and LSU rDNA sequences of the ciliate were similar to Mesanophrys ciliates (>96.81%), while ITS1-5.8s-ITS2 sequence was similar to Mesanophrys pugettensis (95.37%) and identical to Orchitophrya stellarum (100%). Furthermore, the results of the morphological study confirmed that the ciliate was similar to Mesanophrys ciliates and O. stellarum cultured in supportive media, but different from O. stellarum cultured in living sperm cells of starfish (Leptasterias spp.). Also, the growth of the ciliate did not interfere with light, which was different from O. stellarum. Accordingly, the ciliate was classified as genus Mesanophrys and temporarily named as Mesanophrys sp. In addition, experimental infection confirmed that Mesanophrys sp. was the pathogen that infected farmed crabs. In summary, Mesanophrys sp. was first isolated and characterized in P. trituberculatus.