Lu Kang-Le, Ji Zhong-Li, Rahimnejad Samad, Zhang Chun-Xiao, Wang Ling, Song Kai
Xiamen Key Laboratory for Feed Quality Testing and Safety Evaluation, Fisheries College, Jimei University, Xiamen 361021, China.
Xiamen Key Laboratory for Feed Quality Testing and Safety Evaluation, Fisheries College, Jimei University, Xiamen 361021, China.
Comp Biochem Physiol Part D Genomics Proteomics. 2017 Dec;24:51-59. doi: 10.1016/j.cbd.2017.08.001. Epub 2017 Aug 9.
Fish farming seriously influences the aquatic environment because most dietary phosphorus (P) is excreted in the effluent. To increase the P utilization in fish, molecular techniques should be explored given the remarkable development of these techniques. Thus, to identify the candidate genes related to P utilization and molecular alterations following administration of a P-deficient diet in seabass Lateolabrax japonicus, we assessed the de novo pituitary, gill, intestine, liver, kidney, scales and vertebra transcriptomes, and we compared the expression of hepatic genes with three diets varying in P and Ca levels: diet I (0.4% P, 0.3% Ca), diet II (0.8% P, 0.3% Ca), and diet III (0.8% P, 3% Ca). In total, we identified 99,392 unigenes, and 37,086 (37.31%) unigenes were annotated. The results showed that 48 unigenes were significantly (P<0.05) up-regulated, while 55 genes were significantly down-regulated in the liver of group I compared with group II. Offering the P-sufficient and high Ca diet, diet III significantly up-regulated 24 unigenes and down-regulated 46 genes in the liver. There were significant differences in the regulation of 8 unigenes (3 up-regulated and 5 down-regulated) between groups II and III. Gene ontology (GO) functional enrichment and KEGG pathway analysis of differently expressed genes were performed for each pair of groups. The GO analysis showed that a large number of biological processes were significantly altered between P-deficient and P-sufficient treatments (I vs II and I vs III). Comparing group I and group II, seven KEGG terms were enriched significantly: glycine, serine and threonine metabolism, one carbon pool by folate, arginine and proline metabolism, the biosynthesis of unsaturated fatty acids, fatty acid elongation, drug metabolism-cytochrome P450, and fatty acid metabolism. There was no significantly enriched KEGG pathway between groups II and III. In conclusion, our study revealed that a P-deficient diet could increase catabolism and decrease anabolism of protein, as highlighted by low protein efficiency in fish fed the P-deficient diet. Furthermore, P-deficiency could motivate the biosynthesis of fatty acids. However, the dietary Ca level had no significant effect on the growth and expression of hepatic genes in L. japonicus.
养鱼业严重影响水生环境，因为大部分饲料中的磷（P）会随废水排出。鉴于分子技术的显著发展，应探索利用这些技术来提高鱼类对磷的利用率。因此，为了鉴定与鲈鱼（Lateolabrax japonicus）磷利用相关的候选基因以及缺磷日粮投喂后分子水平的变化，我们评估了垂体、鳃、肠道、肝脏、肾脏、鳞片和椎骨的从头转录组，并比较了投喂磷和钙水平不同的三种日粮（日粮I：0.4% P，0.3% Ca；日粮II：0.8% P，0.3% Ca；日粮III：0.8% P，3% Ca）后肝脏基因的表达情况。我们总共鉴定出99,392个单基因，其中37,086个（37.31%）单基因得到注释。结果表明，与II组相比，I组肝脏中有48个单基因显著上调（P<0.05），55个基因显著下调。投喂磷充足且钙含量高的日粮III后，肝脏中有24个单基因显著上调，46个基因显著下调。II组和III组之间有8个单基因（3个上调，5个下调）的调控存在显著差异。对每两组之间差异表达基因进行基因本体（GO）功能富集和KEGG通路分析。GO分析表明，缺磷和磷充足处理（I组与II组以及I组与III组）之间大量生物学过程发生显著改变。比较I组和II组，有7个KEGG条目显著富集：甘氨酸、丝氨酸和苏氨酸代谢、叶酸一碳池、精氨酸和脯氨酸代谢、不饱和脂肪酸生物合成、脂肪酸延长、药物代谢-细胞色素P450以及脂肪酸代谢。II组和III组之间没有显著富集的KEGG通路。总之，我们的研究表明，缺磷日粮会增加蛋白质的分解代谢并降低合成代谢，这在投喂缺磷日粮的鱼类较低的蛋白质效率中得到体现。此外，缺磷会促进脂肪酸的生物合成。然而，日粮钙水平对鲈鱼肝脏生长和基因表达没有显著影响。
