魁蚶(Scapharca broughtonii)也称“赤贝”，属软体动物门(Mollusca)、瓣鳃纲(Lamellibranchia)、蚶目(Arcoida)、蚶科(Arcidae)、毛蚶属(Scapharca)，是一种高蛋白、低脂肪食品。其个大质厚、肉嫩味鲜，自古就被视为珍品，又因含有多种营养的保健功能和独特的风味更受人们青睐。但近年来，随着人们生活水平的提高，对野生贝类资源需求量越来越大，多年无节制的采捕和日益严重的海洋污染，致使贝类的养殖产量和面积日趋减少，魁蚶的种质资源也受到严重威胁[1-2]。随着蚶类养殖业的发展，蚶类养殖在构筑现代海洋产业体系、推动贝类传统产业高端化发展、集约高效利用海洋资源、增强海洋经济可持续发展方面起重要的拉动和示范作用。因此，魁蚶滩涂养殖发展迅猛起来，其养殖面积和产量不断扩大，魁蚶已成为我国海洋养殖贝类的主要品种。然而，高密度养殖水体易滋生大量病原菌，其中致病性鳗弧菌(Vibrio anguillarum)引起的水产动物疾病较为严重，且在世界范围流行[3-4]。因此，魁蚶养殖业的健康可持续发展亟需选育出抗逆抗病能力强的魁蚶品种。
Response of lysozyme activity to Vibrio anguillarum infection in different tissues of Scapharca broughtonii
- Received Date: 2018-12-11
- Accepted Date: 2019-04-25
- Available Online: 2019-10-01
Abstract: The changes in the marine environment and overfishing have caused imbalances in the ecological environment, making the various diseases of shellfish increasingly prominent, and the diseases caused by pathogenic Vibrio have become more common. In this context, the number of wild resources of Scapharca broughtonii has been sharply reduced, and its breeding industry is in urgent need of improved germplasm. In order to effectively prevent the damage of bacteria and other pathogenic microorganisms on S. broughtonii, we observed the response process of the lysozyme activity in different tissues of S. broughtonii infected by Vibrio anguillarum, and explored the immune function of the lysozyme in the body of S. broughtonii. In this experiment, 20-month-old S. broughtonii. individuals were infected by injecting live bacteria, and 16 individuals were randomly selected. And 1 mL (about 1×109) V. anguillarum suspension was injected into the axe of each individual as the infection group. 16 randomly selected individuals were not injected with V. anguillarum as the control group. The two groups were cultivated in clean seawater for 4、12、24 and 48 h. Each group randomly selected 4 S. broughtonii individuals who were dissected the blood, mantle, gill, axe foot, hepatopancrea and adductor muscle tissues. The concentration of lysozyme was determined by ELISA kit. The results showed that for the invasion of V. anguillarum, the lysozyme content in the blood of the S. broughtonii rapidly increased from the normal low value and maintained a high level, indicating that the blood is one of the main immune tissues of the S. broughtonii body defense pathogen.In the case of no infection, the S. broughtonii mantle always maintained a high lysozyme concentration to prevent the interference of the external water environment. The concentration of lysozyme in infected gills and axe foot are significantly higher than the normal values after the injection about 24 hours, indicating that the mantle, gills and axe foot were the first barrier as the S. broughtonii body to contact with the outside world can also respond to the invasion of pathogenic bacteria, but the response was delayed compared with the blood. The lysozyme content of hepatopancrea and adductor muscle did not change significantly. And it was speculated that hepatopancrea and adductor muscle were not important immune tissues or organs of S. broughtonii. The results of this study can provide relevant parameters for the study of disease resistance and immune mechanism of S. broughtonii.