凡纳滨对虾体内β-胡萝卜素向虾青素转化的代谢途径研究及功能基因发掘

Carotenoids play a crucial nutrition and physiology roles for Pacific white shrimp. Pacific white shrimp cannot synthesise carotenoids de novo and must obtain them from their diets. However, there has been strong evidence that Pacific white shrimp can convert β-carotene into astaxanthin and deposit it in tissues. Very limited information is known for the metabolic conversion mechanisms. Hence, to gain more insights about it, this proposal is planning to focus on the “Metabolic pathway of β-carotene to astaxanthin” in Pacific white shrimp. Firstly, UPLC-ESI-QQQ-MS and multivariate data analysis methods are applied to identify and quantify the species of changed carotenoids in the pathway. Subsequently, bioinformatics means are used to mine the functional genes of key enzyme from high-throughput transcriptome basing on the metabolome data. Finally, 1-2 candidate genes for β-carotenoids hydroxylase/ketolase will be selected based on the previous findings. And further identified for their potential functions during the process of the “Metabolic pathway of β-carotene to astaxanthin” through RNA interference and other methods. The expected outcomes of current project would not only help to elucidate the metabolic conversion mechanism of carotenoids, but also provide valuable information for the nutritional requirement of carotenoids and feed development for Pacific white shrimp.

类胡萝卜素对凡纳滨对虾具有重要的营养生理作用。凡纳滨对虾自身无法合成类胡萝素，但可以将外源β-胡萝卜素转化为虾青素储存在体内的不同组织中。然而有关其体内β-胡萝卜素到虾青素转化的代谢机制所知甚少。为此，本项目首先利用代谢组学技术对其体内β-胡萝卜素到虾青素转化过程的中间代谢产物进行定性和定量研究；然后利用生物信息学综合分析转录组、代谢组和已知基因组数据库，实现对代谢转化途径中所需羟基化酶和酮基化酶功能基因的发掘；最后在目的基因克隆的基础上，通过RNA干扰和过表达等鉴定其具体功能，从而确定凡纳滨对虾体内β-胡萝卜素到虾青素转化的主要途径和参与调控的关键酶基因。预期研究结果不仅有助于阐明对虾体内类胡萝卜素的代谢转化机制，进一步了解其对类胡萝卜素的营养需求，而且为开发凡纳滨对虾集约化养殖高效优质饲料提供了理论依据。

类胡萝卜素对甲壳动物具有重要的营养生理作用。甲壳动物自身无法从头合成类胡萝卜素，但可以代谢转化外源类胡萝卜素来满足特定养殖阶段的营养需求。然而有关甲壳动物体内类胡萝卜素的代谢转化及转录调控机制所知甚少。为此，本项目首先通过摄食生长实验探究了外源类胡萝卜素水平对凡纳滨对虾生长、体色、免疫活性及生理生化指标的显著影响；并通过体内类胡萝卜素组成检测，获悉外源β-胡萝卜素和角黄素在对虾体内的代谢转化的主要代谢中间产物及路径。最后整合分析代谢组、转录组及参考基因组数据库获取关键酶基因，获悉凡纳滨对虾体内类胡萝卜素代谢转化途径。同时还围绕卤虫开展了类胡萝卜素强化等相关实验，建立了卤虫体内类胡萝卜素的代谢模型，为后续的甲壳动物体内类胡萝卜素代谢转化所需酮基化酶的挖掘打下基础。预期成果有助于深入了解工厂化养殖对虾的精准营养需求、提高外源类胡萝卜素的利用率、加强养殖健康与品质调控等方面均有重要的理论价值和现实意义。