长江中下游水生微孢子虫多样性与系统发育研究

The Microsporidia are ubiquitous, spore-forming, obligate intracellular protistan parasites which infect host groups of all major animal taxa in environments. This group of parasite is well known as important pathogenic agents of sericulture, apiculture, aquaculture, livestock and human being (especially immunodeficient patients) and biological agent of high efficiency against agricultural pests. However, the previous vast field of research into Microsporidia has focused on terrestrial hosts and species responsible for zoonosis，few attentions were made on the aquatic animals, especially in China. During the past decades, the very important ecological role of microsporidians in aquatic ecosystem by manipulating the sex, physiology and behavior of host of all trophic levels has posed wide research interest among ecologists. Although almost half of the known microsporidian genera were reported to infect aquatic hosts, the biodiversity of aquatic microsporidian was definitely thought to be underestimated. Given wide occurrence of zoonosis caused by microsporidians and their capacity of infecting all animal taxa, ubiquitous microsporidian in aquatic habitats were thought to be the infectious resources. Additionally, the recent frequent outbreak of microsporidiosis of aquatic economic crustaceans (including shrimp, crayfish, lobster and crab) and fish are calling more attention on aquatic microsporidians. Insights into the biodiversity of aquatic microsporidians are the basis to understand the transmission pathways and further develop the feasible preventative strategies. So, the present project will focus on the biodiversity of microsporidian of aquatic animals of all trophic levels in three different watershed of Middle and Lower reaches of Yangtze River. Integration of the current widely accepted criteria for microsporidian taxonomy, including morphological features of all developing stages, ecological characteristic and molecular data and eDNA analysis methods will be applied to explore the diversity and identify them to species level. Furthermore, all obtained sequence data will be used to uncover the phylogenetic relationships of all taxa within Aquasporidia. The present project will fill in the blank of microsporidians of aquatic invertebrates in China, get more insight into the species biodiversity, promote to explore the ecological role of aquatic microsporidians in the aquatic ecosystem and help to develop practical control strategies against zoonosis of waterborne microsporidians and increasing occurred microsporidiosis of aquatic culutred animals in China.

微孢子虫是一类范在的、成孢子、专性细胞内寄生原生动物，寄主范围涉及几乎所有动物类群，既是养蚕业、养蜂业、水产业、家畜、人（尤其是免疫缺陷病患者）的重要病原，也是农业害虫的高效生物制剂。但以往主要关注于陆生微孢子虫，而对水生微孢子虫研究十分匮乏，在我国尤甚。近年来，水生微孢子虫通过操纵不同营养级的宿主性别、生理及行为等方式进而影响水生态系统健康引起了广泛关注。 人畜共患微孢子虫病的流行也让人们意识到水体泛在的微孢子虫可能是其传播源头。此外，近年来经济水生动物微孢子虫病频发，给渔业生产造成了严重的经济损失。本项目拟以长江中下游三种不同水生生境为对象，采用现代微孢子虫分类研究方法与eDNA技术对其生境内各营养级水生动物微孢子虫的多样性开展系统调查研究，获得各物种的形态、生态与分子特征，同时结合现有物种数据探讨水生微孢子虫纲内各阶元的系统发育关系及各分类衍征进化历史。

本项目综合利用微孢子虫传统分类学手段与现代eDNA技术，对长江中下游三种不同水生生境与多种海洋鱼类寄生微孢子虫多样性开展了较广泛调查，主要结果如下：1）海水鱼类寄生微孢子虫Loma属物种存在紧密的亲缘关系，分布于地中海、红海、阿拉伯湾及我国东南海的鲈形目鱼类寄生的多种Loma虫，可能为同一物种，该种对我国养殖黄鳍鲷、黄姑鱼及石斑鱼构成了一定危害；2）首次报道我一例核内及胞内同时寄生的石斑鱼肠道上皮细胞寄生微孢子虫，石斑鱼肠胞虫（Enterospora epinephelus n. sp.），其是当前海南、广东石斑鱼苗种表粗及池塘养殖的主要危害之一，造成了严重经济损失；3）在多种鲤科鱼类肝脏与性腺中发现一微孢子虫新属新种，命名为Pseudokabatana alburnus n. gen. n. sp., 系统发育关系分析发现其与多种小型甲壳类寄生微孢子虫有较近亲缘关系，推测其可能为多宿主泛寄生，行营养传播；4）发现寄生羽摇蚊幼虫微孢子虫4种，其中Neoperezia semenovaiae我国新纪录种，3新种，命名为毛跗亚氏孢虫 Janacekia tainanus n. sp., 羽状微孢子虫（Microsporidium plumose n. sp.）和摇蚊吉荣微虫（Jirovecia chironomi n. sp.）；寄生苏氏尾鳃蚓微孢子虫5种，2种为吉荣微属（Jirovecia）新种，即中华吉荣微虫（J. sinensis n. sp.）和尾鳃吉荣微虫（J. branchial n. sp.），2种杆孢虫属（Bacillidium）新种，即中华杆孢虫（B. sinensis n. sp.）和尾鳃杆孢虫（B. branchial n. sp.），1种与已报道的种属均明显不同，建立一新属新种，即蔡甸寡孢虫（Oligospora caidianensis n. gen. n. sp.）；发现并鉴定了浮游枝角类、桡足类及累枝虫等寄生微孢子虫9种，虾类寄生微孢子虫2种，其中9新种已被鉴定，其余种类尚在鉴定中；5）eDNA及形态鉴定分析发现，所调查水域微孢子虫多样性不如预期的丰富，且感染多成聚集分布，几种主要人源微孢子虫在所调查水域分布有限。本项目较大程度的弥补了我国在小型水生动物微孢子虫多样性研究的空白，获得的数据对构建合理微孢子虫分类系统有较好的促进作用。