细鳞鲑对密度胁迫的代谢响应机制研究

Brachymystax lenok is a rare endangered fish endemic to cold freshwater habitats in China, and controlled culture is an important way to protect and utilize this species. However, some problems, such as low growth rate and high morbidity in intensive culture has hindered the industrialization and commercialization of this species. Stocking density used in commercial fish production have been highlighted as an area of particular welfare concern, and chronic stress caused by stocking density may be an important reason for the low survival rate of Brachymystax lenok. Perhaps the most noticeable response to stress in fishes is a modification in metabolism since the nature of metabolites and, in particular, the changes of them carries rich information in the metabolism level as well as in the gene expression and protein functioning. However, fish will acclimate to long-term stress, the classical indicators of stress will return to normal, and due to the unidimensional nature of classical methods for quantifying stress in fish, there is a risk that common indicators of stress do not represent the whole set of organismal responses that are elicited in stressed states. In our research, the effects of stocking density on the stress reponses of juvenile Brachymystax lenok will be studied by metabonomics using NMR and GC/MS. The differences of metabolites in plasma and liver between control groups and treated groups will be compared in order to analyse metabolites spectrum characteristics, discover novel biomarkers and find effects of stocking density stress on metabolic characteristics and regulating avenues in Brachymystax lenok by biological analysis. Metabolic response mechanism to stocking density stress of Brachymystax lenok will be discussed by metabonomics integrating RNA-seq and Real-time PCR from metabolic whole. The research results will enrich basal biology theory in Salmonidae fish, and also can guild the standardizing culture of Brachymystax lenok, so our research has great significance in theory and application.

细鳞鲑是我国珍稀濒危的土著鲑科鱼类，开展人工驯化养殖是保护和利用其资源的重要手段。但集约化养殖中生长缓慢、病害高发的问题，严重制约了细鳞鲑养殖业的发展。养殖密度是鱼类福利研究中一个倍受关注的内容，密度表现出的慢性胁迫可能是细鳞鲑生存能力降低的重要诱因。代谢的改变是鱼类应对胁迫的主要表现，代谢物的变化蕴含着丰富的生物信息。然而，由于慢性胁迫作用时间较长，常规指标多不敏感且传统技术手段无法从代谢整体的角度进行研究。本项目采用核磁共振和气质联用的代谢组学技术手段，分析细鳞鲑幼鱼血浆和肝脏代谢物的高分辨图谱，鉴定差异性代谢物，通过生物解析探讨密度胁迫对细鳞鲑幼鱼代谢特征和调控途径的影响，同时应用RNA-seq测序技术和Real-time PCR从基因表达水平进行验证，进而阐明密度胁迫对细鳞鲑代谢的影响及作用机制。研究结果有助于丰富鱼类应激生物学的基础理论，同时也可为细鳞鲑标准化养殖提供依据。

细鳞鲑是我国珍稀濒危的土著鲑科鱼类，开展人工驯化养殖是保护和利用其资源的重要手段。但在细鳞鲑集约化养殖过程中，存在着生长缓慢、病害高发的问题，严重制约了细鳞鲑养殖业的发展。养殖密度是影响鱼类生长、健康和福利的重要因素。本项目综合运用代谢组学、转录组学和常规生化分析相结合的技术手段，比较研究了养殖密度对不同规格细鳞鲑生长和代谢的影响，探讨了密度影响细鳞鲑代谢的作用机制。研究结果表明: 小规格细鳞鲑的生长性能受到养殖密度的显著影响。基于NMR和GC-MS的代谢组学分析显示，密度影响了小规格细鳞鲑血浆和肝脏的代谢物组成，造成了能量代谢、氨基酸代谢、胆碱代谢和脂类代谢的改变。养殖密度没有影响不同阶段中规格细鳞鲑的生长性能、成活和饲料利用。大规格细鳞鲑的研究显示，养殖密度没有对大规格细鳞鲑的成活率产生显著影响，而仅对第三阶段细鳞鲑的生长性能产生了显著影响。基于NMR的代谢组学和多变量分析表明，养殖密度没有对中规格和大规格细鳞鲑肝脏和血浆的小分子代谢物变化产生明显的影响。基于肝脏转录组的分析显示养殖密度影响了中规格细鳞鲑代谢和免疫相关通路上的部分基因的表达。综合上述的研究结果表明，细鳞鲑随着规格的增大，对高密度表现出更强的适应能力。这一发现对于细鳞鲑集约化养殖中不同生长阶段养殖密度的精准管理具有重要的指导意义。

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