血红素-HO通路在亚硝酸盐胁迫导致的罗非鱼链球菌易感性的机制研究

随着水产养殖集约化与规模化的发展，如何解除因高密度养殖带来的鱼类病害频发的困境已成为养殖业所面临的重大需求之一。亚硝酸盐胁迫如何导致罗非鱼链球菌易感性的发生？基于这个科学问题，课题组在前期研究发现，高亚硝酸盐会导致罗非鱼体内产生高铁血红蛋白，与无乳链球菌共处理，会导致罗非鱼的肝脏变白、脂肪富集和严重的炎症反应。我们推测：罗非鱼在亚硝酸盐胁迫下，机体的抗氧化应激系统血红素- HO通路可能被激活，进而导致代谢稳态失衡和免疫力降低，使罗非鱼产生链球菌易感性。因此，本课题将系统开展亚硝酸盐胁迫对罗非鱼链球菌的易感性及免疫调控机制的研究，并首次在鱼类中开展靶向血红素-HO通路的miRNA研究，此研究将填补该领域的空白，为阐明亚硝酸盐胁迫下罗非鱼产生链球菌敏感性的机制提供新的思路，也为罗非鱼链球菌病防治提供新的理论基础。研究成果将促进水产生物环境生物学的发展，助推新时期水产养殖业的绿色发展。

In aquaculture, the aquatic environment directly affects the growth and health of aquatic animals. With the intensive and large-scale development of aquaculture, how to deal with the nitrite stress to fish from high concentration of nitrite in aquaculture water has become a major demand of China's aquaculture industry in the new period. How does nitrite stress lead to the development of tilapia streptococcus susceptibility? In previous studies, we have found that high nitrite can lead to the production of methemoglobin in tilapia, moreover, when co-treated with streptococcus agalactiae, can lead to the whitening of tilapia liver, fat accumulation and severe inflammation. We hypothesize that under nitrite stress, heme - HO pathway which is the body's antioxidant stress system may be activated, and induce imbalance of metabolic homeostasis and decrease of immunity, and finally lead to streptococcal susceptibility in tilapia. Hence, in the present proposal, we will try to study systematically how the nitrite stress induce the streptococcal susceptibility in tilapia as well as its relative immune regulation mechanism. For the first time in fish, we will focus on the microRNA targeted heme - HO pathways to reveal the mechanism under the heme - HO pathways inducing streptococcal susceptibility. We believe that the results will fill the blank in the field of the role of heme - HO pathways in fish, and give us a novel insight to understand how nitrite stress induce streptococcal susceptibility in fish. The data also provide new theoretical basis for tilapia streptococcus disease prevention and control. The research results will promote the development of environmental biology of aquatic organisms and promote the green development of aquaculture industry in the new era.