Naldoni Juliana, Pereira Jose O L, Milanin Tiago, Adriano Edson A, da Silva Marcia R M, Maia Antonio A M
Department of Ecology and Evolutionary Biology, Federal University of São Paulo - UNIFESP. Rua Professor Arthur Riedel, 275, Jardim Eldorado, CEP, 09972-270 Diadema, SP, Brazil.
Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, São Paulo University, Avenida Duque de Caxias Norte, 225, CEP, 13635-900 Pirassununga, SP, Brazil.
Parasitol Int. 2020 Jun;76:102061. doi: 10.1016/j.parint.2020.102061. Epub 2020 Jan 22.
Two new Myxobolus species were described infecting Brycon orthotaenia from the São Francisco River, in the state of Minas Gerais, Brazil. From a total of 39 B. orthotaenia collected, two specimens (5.1%) exhibited infection of the ovary and 12 specimens (30.8%) displayed infection of the liver. The plasmodia of both Myxobolus species were white and spherical measuring around 1 mm in length. The plasmodium found in the ovary showed mature myxospores, which were oval shaped from the frontal view and measured 9.2-11.0 (9.8 ± 0.4) μm in length, 5.9-6.9 (6.5 ± 0.3) μm in width and 4.6-5 (4.9 ± 0.1) μm in diameter. The two polar capsules were the same size and measured 3.9-6.2 (4.7 ± 0.5) μm in length and 1.8-2.4 (2.1 ± 0.2) μm in width. The polar tubules had 9 coils. The plasmodium found in the liver showed mature myxospores which were ellipsoidal in shape from the frontal view and measured 10.0-11.4 (10.7 ± 0.5) μm in length, 7.3-8.6 (8.1 ± 0.4) μm in width and 5.3-7.0 (6.8 ± 0.4) μm in diameter. The two polar capsules were the same size and measured 4.2-5.4 (4.9 ± 0.3) μm in length and 1.9-2.9 (2.7 ± 0.3) μm in width. The polar tubules had 8 coils. Ultrastructural analysis revealed an asynchronous sporogenesis process, with young developmental myxospore stages more often found in the periphery of the plasmodium and mature myxospores in the centre of the plasmodium. The plasmodial wall was formed by a single membrane which was not surrounded by a layer of host tissue. A thick layer of fibrous material was found in the peripheral ectoplasm close to the plasmodial wall of the plasmodium found in the ovary. Phylogenetic analysis based on the small-subunit ribosomal DNA - ssrDNA sequences and using the closest myxozoan sequences to each one of the species studied here based on previous GenBank data and Henneguya/Myxobolus/Thelohanellus species parasitizing fish from South American, revealed that the new species are grouped in a subclade together with other Myxobolus species parasitizing bryconid hosts.
描述了两种新的粘体虫物种，它们感染了巴西米纳斯吉拉斯州圣弗朗西斯科河的直口脂鲤。在总共收集的39条直口脂鲤中，有两条标本（5.1%）表现出卵巢感染，12条标本（30.8%）表现出肝脏感染。两种粘体虫物种的孢质团均为白色球形，长度约为1毫米。在卵巢中发现的孢质团显示出成熟的粘孢子，从正面看呈椭圆形，长度为9.2 - 11.0（9.8±0.4）微米，宽度为5.9 - 6.9（6.5±0.3）微米，直径为4.6 - 5（4.9±0.1）微米。两个极囊大小相同，长度为3.9 - 6.2（4.7±0.5）微米，宽度为1.8 - 2.4（2.1±0.2）微米。极丝有9圈。在肝脏中发现的孢质团显示出成熟的粘孢子，从正面看呈椭圆形，长度为10.0 - 11.4（10.7±0.5）微米，宽度为7.3 - 8.6（8.1±0.4）微米，直径为5.3 - 7.0（6.8±0.4）微米。两个极囊大小相同，长度为4.2 - 5.4（4.9±0.3）微米，宽度为1.9 - 2.9（2.7±0.3）微米。极丝有8圈。超微结构分析揭示了一个不同步的孢子发生过程，较年轻的发育中粘孢子阶段更常出现在孢质团的外围，而成熟的粘孢子在孢质团的中心。孢质团壁由一层单一膜形成，没有被一层宿主组织包围。在卵巢中发现的孢质团的孢质团壁附近的外周外质中发现了一层厚厚的纤维物质。基于小亚基核糖体DNA - ssrDNA序列进行系统发育分析，并根据先前的GenBank数据以及寄生于南美鱼类的亨内古亚属/粘体虫属/泰勒汉内虫属物种，使用与这里研究的每个物种最接近的粘孢子虫序列，结果表明新物种与其他寄生于脂鲤科宿主的粘体虫物种一起被归为一个亚分支。
