Wiik-Nielsen J, Mo T A, Kolstad H, Mohammad S N, Hytterød S, Powell M D
Norwegian Veterinary Institute, Oslo, Norway.
Imaging Centre, Norwegian University of Life Sciences, Ås, Norway.
J Fish Dis. 2016 Sep;39(9):1113-23. doi: 10.1111/jfd.12444. Epub 2016 Jan 18.
Amoebic gill disease (AGD) caused by the ectoparasite Paramoeba perurans affects several cultured marine fish species worldwide. In this study, the morphology and ultrastructure of P. perurans in vitro and in vivo was investigated using scanning and transmission electron microscopy (SEM and TEM, respectively). Amoebae cultures contained several different morphologies ranging from a distinct rounded cell structure and polymorphic cells with pseudopodia of different lengths and shapes. SEM studies of the gills of AGD-affected Atlantic salmon, Salmo salar L., revealed the presence of enlarged swellings in affected gill filaments and fusion of adjacent lamellae. Spherical amoebae appeared to embed within the epithelium, and subsequently leave hemispherical indentations with visible fenestrations in the basolateral surface following their departure. These fenestrated structures corresponded to the presence of pseudopodia which could be seen by TEM to penetrate into the epithelium. The membrane-membrane interface contained an amorphous and slightly fibrous matrix. This suggests the existence of cellular glycocalyces and a role for extracellular products in mediating pathological changes in amoebic gill disease.
由体外寄生虫秘鲁嗜阿米巴（Paramoeba perurans）引起的阿米巴鳃病（AGD）影响着全球多种养殖海水鱼类。在本研究中，分别使用扫描电子显微镜和透射电子显微镜（SEM和TEM）对秘鲁嗜阿米巴在体外和体内的形态及超微结构进行了研究。阿米巴培养物包含几种不同形态，从独特的圆形细胞结构到具有不同长度和形状伪足的多形细胞。对受AGD影响的大西洋鲑（Salmo salar L.）鳃的SEM研究显示，受影响的鳃丝出现肿大，相邻鳃小片融合。球形阿米巴似乎嵌入上皮细胞内，随后离开时在基底外侧表面留下带有可见小孔的半球形凹痕。这些有孔结构与伪足的存在相对应，通过TEM可以看到伪足穿透上皮细胞。膜 - 膜界面含有无定形且略带纤维状的基质。这表明存在细胞糖萼，并且细胞外产物在介导阿米巴鳃病的病理变化中发挥作用。
