State Key Laboratory of Freshwater Ecology and Biotechnology and Key Laboratory of Aquaculture Diseases Control, Ministry of Agriculture, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 10049, China.
State Key Laboratory of Freshwater Ecology and Biotechnology and Key Laboratory of Aquaculture Diseases Control, Ministry of Agriculture, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao 266109, China; Laboratory of Parasitology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi 1677-1, Japan.
J Invertebr Pathol. 2021 Jun;182:107578. doi: 10.1016/j.jip.2021.107578. Epub 2021 Mar 19.
We reported a new microsporidium Janacekia tainanus n. sp. from the adipose tissue of the midge Kiefferulus tainanus Kieffer, 1912 collected from a eutrophic pond in Daye city, Hubei Province, China. Infected chironomid larvae with hypertrophied adipose tissue exhibited porcelain-white. All developmental stages possessed large nuclei. The earliest stages observed were diplokaryotic meronts which were in direct contact with the host adipocyte cytoplasm. Diplokaryotic meronts developed into sporonts with the deposition of electron-dense coagulum on their surface. Multinucleate sporogonial plasmodia developed into uninucleate sporoblasts by the rosette-like division. Mature spores were oval and monokaryotic, measuring 6.14 ± 0.27 (5.65-6.67) µm long and 3.71 ± 0.12 (3.43-3.98) µm wide. Bipartite polaroplast consisted of a narrow anterior lamella and a wide posterior lamella. Isofilar polar filaments coiled 13-17 turns and arranged in one row. The exospore was thin and of no stratification, but remarkably covered with tubular secretions. The electron-lucent endospore was thick and measured 145-352 nm wide. Phylogenetic analysis based on the obtained SSU rDNA sequence indicated that the present species clustered closely with Jirovecia sinensis, a species with rod-shaped mature spores isolated from the coelomocytes of Branchiura sowerbyi. Consistent with the previous result, the monophyletic clade of Jirovecia-Bacillidium-Janacekia was sister to Pseudonosema clade and then collectively nested within Clade V of Class Aquasporidia sensu Vossbrinck and Debrunner-Vossbrinck (2005). The novel species did not form an independent monophyletic lineage with the congener, Janacekia debaisieuxi. Based on the morphological characters and ultrastructural features, as well as SSU rDNA-inferred phylogenetic relationships, a new species in the genus Janacekia, Janacekia tainanus n. sp. was designated. This is the first report of aquatic arthropod-infecting microsporidia in China.
我们报道了一种来自中国湖北省大冶市富营养化池塘中的米象科昆虫 Kiefferulus tainanus Kieffer，1912 的脂肪组织中的一种新的微孢子虫 Janacekia tainanus n. sp。受感染的摇蚊幼虫的脂肪组织呈乳白色。所有发育阶段都有大核。观察到的最早阶段是与宿主脂肪细胞质直接接触的二倍体裂殖体。二倍体裂殖体发育成表面有电子致密凝结物的孢子母细胞。多核孢子原质体通过玫瑰花结状分裂发育成单核孢子母细胞。成熟的孢子呈椭圆形和单核，长 6.14±0.27（5.65-6.67）μm，宽 3.71±0.12（3.43-3.98）μm。二分体极质体由一个窄的前叶和一个宽的后叶组成。等丝极丝卷曲 13-17 圈，排列成一行。外孢子薄且无分层，但明显覆盖有管状分泌物。电子透明的内孢子较厚，宽 145-352nm。基于获得的 SSU rDNA 序列的系统发育分析表明，本种与中华棘球绦虫（Jirovecia sinensis）密切聚类，后者是从 Branchiura sowerbyi 的体腔细胞中分离出来的一种具有杆状成熟孢子的物种。与先前的结果一致，Jirovecia-Bacillidium-Janacekia 的单系分支与 Pseudonosema 分支并列，然后共同嵌套在 Vossbrinck 和 Debrunner-Vossbrinck（2005）定义的 Class Aquasporidia 类的第五分支中。该新种与同属种 Janacekia debaisieuxi 没有形成独立的单系谱系。基于形态特征和超微结构特征以及 SSU rDNA 推断的系统发育关系，我们指定了 Janacekia 属中的一个新种，即 Janacekia tainanus n. sp。这是中国水生节肢动物感染微孢子虫的首次报道。
