Hepatic transcriptome analysis and identification of differentially expressed genes response to dietary oxidized fish oil in loach <i>Misgurnus anguillicaudatus</i>

RNA sequencing and short-read assembly were utilized to produce a transcriptome of livers from loaches (Misgurnus anguillicaudatus) fed with three different diets respectively containing fresh fish oil (FO group), medium oxidized fish oil (MO group) and high oxidized fish oil (HO group). A total of 60,663 unigenes were obtained in this study, with mean length 848.74 bp. 50,814, 49,584 and 49,814 unigenes were respectively obtained from FO, MO and HO groups. There were 2,343 differentially expressed genes between FO and MO, with 855 down- and 1,488 up-regulated genes in the MO group. 2,813 genes were differentially expressed between FO and HO, including 1,256 down- and 1,552 up-regulated genes in the HO group. 2,075 differentially expressed genes were found in the comparison of MO and HO, including 1,074 up- and 1,001 down-regulated genes in the MO group. Some differentially expressed genes, such as fatty acid transport protein (fatp), fatty acid binding protein (fabp), apolipoprotein (apo), peroxisome proliferator activated receptor-gamma (ppar-γ), acetyl-CoA synthetase (acs) and arachidonate 5-lipoxygenase (alox5), were involved in lipid metabolism, suggesting these genes in the loach were responsive to dietary oxidized fish oil. Results of transcriptome profilings here were validated using quantitative real time PCR in fourteen randomly selected unigenes. The present study provides insights into hepatic transcriptome profile of the loach, which is a valuable resource for studies of loach genomics. More importantly, this study identifies some important genes responsible for dietary oxidized fish oil, which will benefit researches of lipid metabolism in fish.本研究采用RNA测序结合短读长组装技术，对分别饲喂三种不同日粮的泥鳅（Misgurnus anguillicaudatus）肝脏进行转录组构建，三种日粮分别添加新鲜鱼油（FO组）、中度氧化鱼油（MO组）与重度氧化鱼油（HO组）。本研究共获得60663条非冗余基因（unigenes），平均长度为848.74 bp；FO、MO、HO三组分别获得50814、49584、49814条非冗余基因。FO组与MO组间共鉴定到2343个差异表达基因，其中MO组中有855个基因表达下调、1488个基因表达上调。FO组与HO组间共鉴定到2813个差异表达基因，其中HO组中有1256个基因表达下调、1552个基因表达上调。MO组与HO组间共鉴定到2075个差异表达基因，其中MO组中有1074个基因表达上调、1001个基因表达下调。部分差异表达基因参与脂质代谢过程，例如脂肪酸转运蛋白（fatty acid transport protein, fatp）、脂肪酸结合蛋白（fatty acid binding protein, fabp）、载脂蛋白（apolipoprotein, apo）、过氧化物酶体增殖物激活受体γ（peroxisome proliferator activated receptor-gamma, ppar-γ）、乙酰辅酶A合成酶（acetyl-CoA synthetase, acs）以及花生四烯酸5-脂氧合酶（arachidonate 5-lipoxygenase, alox5），提示泥鳅体内这些基因可响应日粮中氧化鱼油的刺激。本研究通过实时荧光定量PCR（quantitative real time PCR）对随机选取的14条非冗余基因进行验证，证实了转录组测序分析结果的可靠性。本研究解析了泥鳅肝脏的转录组特征，为泥鳅基因组学相关研究提供了宝贵的数据资源。更为重要的是，本研究筛选出一批响应日粮氧化鱼油的关键基因，可为鱼类脂质代谢相关研究提供理论参考。