Comparative Transcriptome Analysis in the Hepatopancreas Tissue of Pacific White Shrimp Litopenaeus vannamei Fed Different Lipid Sources at Low Salinity

RNA-seq was used to compare the transcriptomic response of hepatopancreas in juvenile Litopenaeus vannamei fed three diets with different lipid sources, including beef tallow (BT), fish oil (FO), and an equal combination of soybean oil + BT + linseed oil (SBL) for 8 weeks at 3 practical salinity unit (psu). A total of 9622 isogenes were annotated in 316 KEGG pathways and 39, 42 and 32 pathways significantly changed in the paired comparisons of FO vs SBL, BT vs SBL, or FO vs BT, respectively. The pathways of glycerolipid metabolism, linoleic acid metabolism, arachidonic acid metabolism, glycerophospholipid metabolism, fatty acid biosynthesis, fatty acid elongation, fatty acid degradation, and biosynthesis of unsaturated fatty acid were significantly changed in all paired comparisons between dietary lipid sources, and the pathways of glycerolipid metabolism, linoleic acid metabolism, arachidonic acid metabolism and glycerophospholipid metabolism significantly changed in the FO vs SBL and BT vs SBL comparisons. These pathways are associated with energy metabolism and cell membrane structure. The results indicate that lipids sources affect the adaptation of L. vannamei to low salinity by providing extra energy or specific fatty acids to change gill membrane structure and control iron balance. The results of this study lay a foundation for further understanding lipid or fatty acid metabolism in L. vannamei at low salinity.

本研究采用RNA测序（RNA-seq）技术，对比了在3实用盐度单位（practical salinity unit, psu）环境下饲养8周的凡纳滨对虾（Litopenaeus vannamei）幼体肝胰腺的转录组应答，其饲喂的三种饲料分别使用了不同脂质源：牛油（beef tallow, BT）、鱼油（fish oil, FO），以及豆油+牛油+亚麻籽油等比例混合组（soybean oil + BT + linseed oil, SBL）。最终共有9622个同源基因被注释到316条KEGG通路中；在FO与SBL、BT与SBL、FO与BT三组配对比较中，分别有39、42、32条通路发生显著变化。甘油酯代谢、亚油酸代谢、花生四烯酸代谢、甘油磷脂代谢、脂肪酸生物合成、脂肪酸延长、脂肪酸降解及不饱和脂肪酸生物合成通路，在所有饲料脂质源的配对比较中均出现显著改变；而甘油酯代谢、亚油酸代谢、花生四烯酸代谢及甘油磷脂代谢通路，在FO与SBL、BT与SBL的配对比较中同样发生显著变化。上述通路均与能量代谢及细胞膜结构密切相关。研究结果表明，脂质来源可通过提供额外能量或特定脂肪酸以改变鳃膜结构、调控离子平衡，从而影响凡纳滨对虾对低盐环境的适应性。本研究结果为进一步解析低盐环境下凡纳滨对虾的脂质及脂肪酸代谢机制奠定了基础。