Ramilo A, Abollo E, Villalba A, Carballal M J
Centro de Investigacións Mariñas, Consellería do Mar da Xunta de Galicia, Vilanova de Arousa, Spain.
Centro Tecnológico del Mar - Fundación CETMAR, Vigo, Spain.
J Fish Dis. 2018 Jan;41(1):41-48. doi: 10.1111/jfd.12668. Epub 2017 Jul 14.
The cockle Cerastoderma edule fishery has traditionally been the most important shellfish species in terms of biomass in Galicia (NW Spain). In the course of a survey of the histopathological conditions affecting this species in the Ria of Arousa, a haplosporidan parasite that had not been observed in Galicia was detected in one of the most productive cockle beds of Galicia. Uni- and binucleate cells and multinucleate plasmodia were observed in the connective tissue mainly in the digestive area, gills and gonad. The parasite showed low prevalence, and it was not associated with abnormal cockle mortality. Molecular identification showed that this parasite was closely related to the haplosporidan Minchinia mercenariae that had been reported infecting hard clams Mercenaria mercenaria from the Atlantic coast of the United States. The molecular characterization of its SSU rDNA region allowed obtaining a fragment of 1,796 bp showing 98% homology with M. mercenariae parasite. Phylogenetic analysis supported this identification as this parasite was clustered in the same clade as M. mercenariae from the United States and other M. mercenariae-like sequences from the UK, with bootstrap value of 99%. The occurrence of M. mercenariae-like parasites infecting molluscs outside the United States is confirmed.
鸟蛤渔业在加利西亚（西班牙西北部）一直是按生物量计算最重要的贝类物种。在对阿罗萨河口影响该物种的组织病理学状况进行调查的过程中，在加利西亚最丰产的鸟蛤养殖场之一发现了一种在加利西亚未曾见过的单孢子虫寄生虫。在结缔组织中，主要在消化区、鳃和性腺中观察到单核和双核细胞以及多核的疟原虫。该寄生虫的感染率较低，且与鸟蛤的异常死亡无关。分子鉴定表明，这种寄生虫与已报道感染美国大西洋沿岸硬壳蛤的单孢子虫Minchinia mercenariae密切相关。对其小亚基核糖体DNA（SSU rDNA）区域的分子特征分析得到了一个1796 bp的片段，与M. mercenariae寄生虫显示出98%的同源性。系统发育分析支持了这一鉴定结果，因为这种寄生虫与来自美国的M. mercenariae以及来自英国的其他类似M. mercenariae的序列聚集在同一进化枝中，自展值为99%。证实了在美国以外感染软体动物的类似M. mercenariae寄生虫的存在。
