Department of Aquatic Animal Medicine and Management, Faculty of Veterinary Medicine, Assiut University, Assiut, 71526, Egypt.
Fish Health and Diseases Department, Faculty of Fish and Fisheries Technology, Aswan University, Aswan, 81528, Egypt.
BMC Vet Res. 2022 Aug 31;18(1):330. doi: 10.1186/s12917-022-03405-2.
Prevalence, morphology, and molecular characteristics of isopodiosis in the European seabass, Dicentrarchus labrax, in Egypt were assessed using light and electron microscopy and polymerase chain reaction targeting the mitochondrial COI (cytochrome oxidase c) gene.
Adult parasites were found mainly in the branchial cavity between gill arches and to a lesser extent in the buccal cavity. They were morphologically identified as the Cymothoidae Livoneca redmanii Leach, 1818 (Crustacea: Isopoda). Obviously, a 23% prevalence rate of isopods was reported in D. labrax from Egyptian Mediterranean waters. Destructive and degenerative necrotic alterations with complete sloughing of gill lamellae of the infested fish were observed. DNA sequencing of the mitochondrial COI gene confirmed the identification of the parasite which was deposited in the GenBank under accession numbers MW600099, MZ208984, and MZ208985. Furthermore, the phylogenetic analysis demonstrated that parasites emerged from a monophyletic clade closely affiliated with L. redmanii and were clearly distinguished from other isopod genospecies.
The present investigation addresses L. redmanii infestation in D. labrax in Egypt and affirmed morphological properties via the scanning electron microscopy (SEM) and molecular characteristics of this isopod species. The drastic effects of this parasite on the infected fish were proven both clinically and histopathologically.
本研究采用光镜和电子显微镜以及针对线粒体 COI（细胞色素氧化酶 c）基因的聚合酶链式反应，评估了埃及欧洲鲈鱼（Dicentrarchus labrax）中等足目寄生虫的流行率、形态和分子特征。
成年寄生虫主要在鳃弓之间的鳃腔中发现，在口腔中也有少量存在。它们被形态学鉴定为尾海鞘科 Livoneca redmanii Leach, 1818（甲壳纲：等足目）。显然，在埃及地中海水域的 D. labrax 中报告了 23%的等足目寄生虫流行率。受感染鱼类的鳃片出现明显的破坏性和退行性坏死改变，完全脱落。线粒体 COI 基因的 DNA 测序证实了寄生虫的鉴定，该序列已在 GenBank 中以 MW600099、MZ208984 和 MZ208985 登录号进行了保存。此外，系统发育分析表明，寄生虫来自与 L. redmanii 密切相关的单系分支，并且与其他等足目种明显区分开来。
本研究调查了埃及 D. labrax 中 L. redmanii 的感染情况，并通过扫描电子显微镜（SEM）证实了这种等足目寄生虫的形态特征，以及该物种的分子特征。这种寄生虫对感染鱼类的严重影响在临床和组织病理学上都得到了证明。
