Stilwell Justin M, Petty B Denise, Camus Alvin C, Woodyard Ethan T, Griffin Matt J, Rosser Thomas G
Department of Pathology, University of Georgia, Athens, GA, 30602, USA.
North Florida Aquatic Veterinary Services, Ft. White, FL, 32038, USA.
Syst Parasitol. 2020 Jun;97(3):305-314. doi: 10.1007/s11230-020-09911-x. Epub 2020 Apr 6.
A previously undescribed Myxobolus sp. was isolated from the cranial nerves and ganglia of the spotfin hatchetfish Thoracocharax stellatus (Kner) that exhibited neurologic signs following importation from Colombia. Associated plasmodia formed space-occupying masses within nerves, compressing neuronal cell bodies and causing axonal degeneration. Myxospores from these fish were morphologically and molecularly distinct from other myxobolids infecting the central nervous system of characins. In valvular view, spores are pyriform with a rounded posterior and tapering anterior aspect. Myxospore bodies are 17.0-19.4 (mean 18.4) µm long and 8.2-9.3 (mean 8.8) µm wide. Polar capsules are asymmetrical and pyriform with a neck-like projection at the apical end. The small polar capsule measures 4.3-5.9 × 2.2-3.1 (mean 5.0 × 2.6) µm, while the large polar capsule measures 9.1-10.7 × 4.9-6.3 (mean 9.9 × 5.4) µm wide. The sequence generated for the small subunit rRNA (18S) gene did not directly match any sequences available on GenBank, but demonstrated 92% nucleotide similarity to Myxobolus axelrodi Camus, Dill, Rosser, Pote & Griffin, 2017 infecting Paracheirodon axelrodi (Schultz). This study provides the first morphological, histological and molecular characterisation of Myxobolus stellatus n. sp. from the spotfin hatchetfish.
从星斑胸斧鱼（Thoracocharax stellatus，克纳）的脑神经和神经节中分离出一种先前未描述过的黏液孢子虫属（Myxobolus sp.），该鱼从哥伦比亚进口后出现了神经症状。相关的孢囊在神经内形成占位性肿块，压迫神经元细胞体并导致轴突变性。这些鱼的黏液孢子在形态和分子特征上与感染脂鲤科鱼类中枢神经系统的其他黏液孢子虫不同。在瓣膜视图中，孢子呈梨形，后部圆形，前部逐渐变细。黏液孢子体长17.0 - 19.4（平均18.4）μm，宽8.2 - 9.3（平均8.8）μm。极囊不对称，呈梨形，顶端有类似颈部的突出物。小极囊尺寸为4.3 - 5.9×2.2 - 3.1（平均5.0×2.6）μm，而大极囊尺寸为9.1 - 10.7×4.9 - 6.3（平均9.9×5.4）μm宽。为小亚基rRNA（18S）基因生成的序列与GenBank上的任何可用序列均不直接匹配，但与2017年感染阿氏魮脂鲤（Paracheirodon axelrodi，舒尔茨）的阿克塞尔罗德黏液孢子虫（Myxobolus axelrodi，卡穆斯、迪尔、罗瑟、波特和格里芬）有92%的核苷酸相似性。本研究首次对星斑胸斧鱼的星斑黏液孢子虫（Myxobolus stellatus n. sp.）进行了形态学、组织学和分子特征描述。
