Institute for Experimental Pathology, University of Iceland, Keldur v/ Vesturlandsveg, 112, Reykjavik, Iceland.
Parasit Vectors. 2013 Mar 1;6:51. doi: 10.1186/1756-3305-6-51.
Approximately 40 species of Sphaeromyxa have been described, all of which are coelozoic parasites from gall bladders of marine fish. They are unique amongst the myxosporeans as they have polar filaments that are flat and folded instead of being tubular and spirally wound. This unusual feature was used as a subordinal character to erect the suborder Sphaeromyxina, which contains one family, the Sphaeromyxidae, and a single genus Sphaeromyxa.
In the present study, we examine eelpout from the genus Lycodes from Iceland for the presence of myxosporean parasites in the gall bladder and perform morphological and DNA studies.
A novel myxosporean, Sphaeromyxa lycodi n. sp., was identified in the gall bladders of five of the six species of Lycodes examined, with a prevalence ranging from 29 - 100%. The coelozoic plasmodia are large, polysporous and contain disporic pansporoblasts and mature spores which are arcuate. The pyriform polar capsules encase long and irregularly folded ribbon-like polar filaments. Each spore valve has two distinct ends and an almost 180° twist along the relatively indistinct suture line. The single sporoplasm is granular with two nuclei. Sphaeromyxa lycodi is phylogenetically related to other arcuate sphaeromyxids and is reproducibly placed with all known sphaeromyxids and forms part of a robustly supported clade of numerous myxosporean genera which infect the hepatic biliary systems of a wide range of hosts.
Sphaeromyxa lycodi is a common gall bladder myxosporean in eelpout of the genus Lycodes from Northern Iceland. It has characteristics typical of the genus and develops arcuate spores. Molecular phylogenetic analyses confirm that sphaeromyxids form a monophyletic group, subdivided into straight and arcuate spore forms, within the hepatic biliary clade that infect a wide range of freshwater associated animals. The ancestral spore form for the hepatic biliary clade was probably a Chloromyxum morphotype; however, sphaeromyxids have more recently evolved from an ancestor with a spindle-shaped Myxidium spore form. We recommend that the suborder Sphaeromyxina is suppressed; however, we retain the family Sphaeromyxidae and place it in the suborder Variisporina.
已描述了约 40 种 Sphaeromyxa，它们都是海洋鱼类胆囊中的内寄生性寄生虫。它们在粘孢子动物中是独一无二的，因为它们的极丝是扁平且折叠的，而不是管状且螺旋缠绕的。这个不寻常的特征被用作建立包含一个科，即 Sphaeromyxidae 和一个属 Sphaeromyxa 的 Sphaeromyxina 亚目的亚目特征。
在本研究中，我们检查了来自冰岛的 Lycodes 属的胡瓜鱼是否存在胆囊中的粘孢子虫寄生虫，并进行了形态学和 DNA 研究。
在检查的六种 Lycodes 物种中的五种中，发现了一种新的粘孢子虫，即 Lycodi n. sp. Sphaeromyxa，其流行率为 29-100%。内生的质体很大，多孢子且含有二分裂的胞质体和成熟的孢子，这些孢子是弓形的。梨形极囊包含长而不规则折叠的带状极丝。每个孢子瓣有两个明显的末端，并且在相对不明显的缝合线上有近 180°的扭曲。单个孢子质是颗粒状的，有两个核。Sphaeromyxa lycodi 在系统发育上与其他弓形的粘孢子虫有关，并且与所有已知的粘孢子虫一起重复出现，并形成感染广泛宿主的肝胆管系统的许多粘孢子虫属的一个稳健支持的分支的一部分。
Lycodes 属的胡瓜鱼中的 Sphaeromyxa lycodi 是一种常见的胆囊粘孢子虫。它具有该属的典型特征，并且发育弓形孢子。分子系统发育分析证实，粘孢子虫形成一个单系群，分为直孢子和弓形孢子形式，在感染广泛的淡水相关动物的肝胆管分支中。肝胆管分支的祖先孢子形式可能是 Chloromyxum 形态型；然而，粘孢子虫最近从具有纺锤形 Myxidium 孢子形式的祖先中进化而来。我们建议抑制 Sphaeromyxina 亚目；然而，我们保留了 Sphaeromyxidae 科，并将其置于 Variisporina 亚目中。
