El-Dien Abdel Hakim S, Abdel-Gaber Rewaida A
Department of Zoology, Faculty of Science, Cairo University, Cairo 12613, Egypt.
J Egypt Soc Parasitol. 2009 Aug;39(2):665-78.
The parasitic ciliate Ichthyophthirius multifiliis (Ich) is one of the most important protozoan pathogens of freshwater fish worldwide. Examination of 4 species of Tilapia from the River Nile recorded highest rate infection in Oreochromis niloticus, followed by Oreochromis aureus, Sarotherodon galilaeus and Tilapia zilli. By electron microscopy, apoptotic cells collected from Tilapia species infected with "Ich" showed an aggregation on the apical and basal parts of the ciliated and non-ciliated endothelial lining the gill epithelium. Ultrastructural analysis showed that the chromatin in the liver of Ich-infected O. niloticus was highly condensed and massed at the center of the nucleus. UItrastructural analysis of "Ich" infected O. aureus showed that the nuclear membrane of hepatocytes was also shrunken. In S. galilaeus, chromatin was highly condensed, fragmented and massed at the nuclear center, occasionally forming crescent-shaped masses. Ultrastructural of O. niloticus spleen showed that the macrophage number was comparatively high as compared to control. In O. aureus, damaged splenic cell number did not change, and phagocytic capacity of macrophages was not very high. In Ich-infected S. galilaeus, a marked decrease in splenic cells number was seen. Analysis of DNA by agarose gel electrophoresis on gill, liver and spleen cells showed a ladder of DNA fragments in multiple of 180bp in length, pointing to an internucleosomal DNA cleavage.
寄生性纤毛虫多子小瓜虫（Ich）是全球淡水鱼最重要的原生动物病原体之一。对尼罗河的4种罗非鱼进行检查发现，尼罗罗非鱼的感染率最高，其次是奥利亚罗非鱼、加利利罗非鱼和齐氏罗非鱼。通过电子显微镜观察，从感染“Ich”的罗非鱼物种中收集的凋亡细胞在鳃上皮纤毛和非纤毛内皮的顶端和基部聚集。超微结构分析表明，感染Ich的尼罗罗非鱼肝中的染色质高度浓缩并聚集在细胞核中心。对感染“Ich”的奥利亚罗非鱼的超微结构分析表明，肝细胞的核膜也收缩了。在加利利罗非鱼中，染色质高度浓缩、碎片化并聚集在核中心，偶尔形成新月形团块。尼罗罗非鱼脾脏的超微结构显示，与对照组相比，巨噬细胞数量相对较高。在奥利亚罗非鱼中，受损脾细胞数量没有变化，巨噬细胞的吞噬能力不是很高。在感染Ich的加利利罗非鱼中，脾细胞数量明显减少。对鳃、肝和脾细胞进行琼脂糖凝胶电泳分析DNA，显示出长度为180bp倍数的DNA片段梯状条带，表明存在核小体间DNA裂解。
