黄颡鱼寄生车轮虫生活史和营养需求研究

Trichodinid is one kind of protozoan, which can cause serious diseases in aquaculture animals. Trichodinid infection will lead to the deadth of aquaculture animals directly, but also cause the bacterial infection and virus infection indirectly. Therefore，the economic losses were leaded and the aquaculture development was inhibited. At present，CuSO4-FeSO4 powder is the most common drug used to deal with the Trichodinid infection. But the obvious resistance was observed with the long time using of this kind of powder in Trichodinid. Furthermore，CuSO4 is one kind of heavy metal, the continuous using has leaded to water and soil pollution. So, the high-efficiency and low-toxicity specialized drug screening is immediate urgency. The life cycle and nutrition requirement are the key points solving these troubles. Research data demonstrates that life cycle can help to understand the process of growth, development and breeding. Furthermore, the survival condition, infection model and weak stag of parasite will be uncovered, all of these lead to effective controlling measure. Our preliminary work indicated alepidote fish such as yellow catfish were more likely to be infected. In the present research, we aimed to build a trichodinid keeping and reproduction system using yellow catfish as vector. Also，trichodinid nutrition requirement will be analyzed by feeding fish mucus and bacteria. Research data will promote the building of Trichodinid in vitro culture.

车轮虫是一类对水产养殖品种具有严重危害的原生动物，车轮虫的感染除了直接导致水产动物的死亡之外，还会间接引起细菌和病毒的续发感染，造成严重的经济损失并制约着水产养殖业的发展。目前对该病原的防治主要依赖于硫酸铜-硫酸亚铁混合物，但是长期的使用已经使得车轮虫出现了较为明显的耐受性，同时由于硫酸铜属于重金属，长期的使用必将造成水环境、土壤环境的污染，因此筛选具有针对性的高效低毒药物迫在眉睫，而此工作的关键在于对车轮虫生活史及营养需求研究。研究表明通过揭示生活史不但可以了解寄生虫生长、发育和繁殖的全过程，而且可以据此明确其生存条件、感染模式及其脆弱时期，进而提出有效的防治措施。前期研究表明黄颡鱼等无鳞鱼更易感染车轮虫，本项目拟通过构建以黄颡鱼为载体的传代维持体系来研究车轮虫的生活史，进一步分析车轮虫对鱼体黏液、细菌等物质的摄食来分析该虫的营养需求，为车轮虫的离体培养提供实验数据。

一、项目的背景：. 车轮虫是一类对水产养殖品种具有严重危害的原生动物，车轮虫的感染除了直接导致水产动物的死亡之外，还会间接引起细菌和病毒的续发感染，造成严重的经济损失并制约着水产养殖业的发展。目前对该病原的防治主要依赖于硫酸铜-硫酸亚铁混合物，但是长期的使用已经使得车轮虫出现了较为明显的耐受性，同时由于硫酸铜属于重金属，长期的使用必将造成水环境、土壤环境的污染，因此筛选具有针对性的高效低毒药物迫在眉睫，而此工作的关键在于对车轮虫生活史及营养需求研究。.二、主要研究内容：. 本项目对车轮虫的生活史进行了连续观察，通过银染、甲基绿派洛宁染色等手段揭示了车轮虫生活史的各个时期特点；通过荧光标记手段研究了车轮虫对大肠杆菌的摄食情况；通过生物统计研究了鱼体感染车轮虫数量与环境因子的相关性。.三、重要结果：. 1、车轮虫繁殖以二分裂为主；2、分裂前期马蹄形大核固缩成棒状，分裂期表现为虫体正中两侧开始出现一道凹陷的裂痕将其划分为大致相等的两部分，凹陷由虫体边缘向中心逐渐加深，进入分裂末期，虫体呈“8”字形，最后断裂成一对新个体。3、车轮虫可以摄食大肠杆菌；4、黄颡鱼腮部寄生车轮虫丰度与总磷浓度、活性磷浓度、总氮浓度显著负相关；与亚硝酸盐浓度显著正相关；与温度（24.0～30．5 ℃）、氨氮浓度无显著相关性。.四、关键数据及其科学意义：. 车轮虫可以摄食大肠杆菌的这一发现为车轮虫的纯培养提供了一个选择方向。