水产学报2025，Vol.49Issue(12)：176-187,12.DOI:10.11964/jfc.20250515001
感染鲫鳃丝的秀山单极虫(新种)的形态与分子生物学鉴定
Morphological and molecular characterization of Thelohanellus xiushanensis n.sp.infecting the gill filament of Carassius auratus
摘要
Abstract
The exploration and understanding of myxosporean,one of the crucial stressors causing fish disease,have always been highly regarded.The present study aims to fully understand a novel myxobolid species,Thelohanellus xiushanensis n.sp.infecting the gill filaments of Carassius auratus from Chongqing,China,as well as the associated patholo-gical impacts.A multifaceted analysis at various levels and perspectives was carried out by the approach integrating morphology,molecular systematics,histopathology,com-bined host and habitat,as well as SSU rDNA data.The results indicated that its mature myxospores displayed a tapering anterior and a blunt-rounded posterior,with a drop-shape in front view and melon-seed shape in sutural view in morphology.The outer sur-face was covered with a transparent membrane sheath in valve view.The dimensions of myxospores were average(19.2±1.1)(17.1-21.0)×(10.0±0.7)(8.7-12.1)×(9.7±0.5)(9.1-10.8)μm.An elliptical polar capsule,containing four to five turns of single polar fila-ment,measures(8.0±0.6)(6.9-9.1)×(6.6±0.3)(6.1-7.1)μm.Its SSU rDNA sequence demonstrated the closest similarity(99.95%)with an actinosporean Neoactinomyxum sp.NEO-7.Histopathological results indicated that numerous myxoplasmodia of T.xiushan-ensis n.sp.were located in the tips of the gill filaments,resulting in deformation and rup-ture of partial gill filaments.Furthermore,severely infected gill lamellae exhibited hyper-plasia and fusion,accompanied by infiltration of numerous eosinophils.In addition,regenerated gill filaments were observed at the bases of partially ruptured gill filaments,indicating that the host's gill tissue has the innate capacity to shed diseased tissues and regenerate new ones.This study has proved the present species and Neoactinomyxum sp.NEO-7 belong to the same myxosporean species but corresponding to different develop-mental stage,designated as a new species.This novel species is a potential pathogen for the host,which should not be ignored.This study not only enriches myxobolid biod-iversity and demonstrates a potentially pathogenic agent,but also provides a valid dia-gnosis for the gill myxoboliosis caused by the present pathogen in aquaculture.关键词
鲫/秀山单极虫新种/形态学/系统发育/SSU rDNAKey words
Carassius auratus/Thelohanellus xiushanensisn.sp./morphology/phylogeny/SSU rDNA分类
农业科技引用本文复制引用
张金叶,王苗苗,王悦如,刘红艳,张艺雯,赵元莙..感染鲫鳃丝的秀山单极虫(新种)的形态与分子生物学鉴定[J].水产学报,2025,49(12):176-187,12.基金项目
国家自然科学基金(31970409) （31970409）
重庆市科技局重点项目(cstc2021jcyj-msxmX0731) National Natural Science Foundation of China(31970409) （cstc2021jcyj-msxmX0731）
Projects of Chongqing Science and Technology Commission(cstc2021jcyj-msxmX0731) （cstc2021jcyj-msxmX0731）
