オオクチバス幼生の離乳期における肝臓遺伝子と腸内マイクロバイオームの共変調

Co-modulation of Liver Genes and Intestinal Microbiome of Largemouth Bass Larvae () During Weaning.

• Liulan Zhao
• Kuo He
• Jie Luo
• Junlong Sun
• Lei Liao
• Xiaohong Tang
• Qiao Liu
• Song Yang

抄録

近年、中国ではスズキの養殖が盛んに行われるようになったが、幼魚の離乳期の生存率が低いことがネックとなっており、産業の発展を阻害してきた。オオクチバスの幼魚の離乳期における肝臓代謝と腸内細菌叢の変化を理解することは、より良い離乳戦略を設計し、生存率を向上させるのに役立つ。本研究では、肝臓mRNAと腸内細菌叢16S rRNA遺伝子をハイスループットシーケンシングを用いて、離乳前、離乳中、離乳後（孵化後15日、30日、45日目、全長（cm）はそれぞれ2.21±0.12、3.45±0.21、5.29±0.33）の各段階で解析した。トランスクリプトームの結果、発現が増加した遺伝子は離乳前段階ではアミノ酸代謝に関連していたが、離乳後段階では脂肪酸代謝に関連していることが明らかになった。腸内細菌叢においても同様の現象が見られ、離乳前期には支配的な微生物であったプロテオバクテリア（相対的存在率56.32％）が離乳後期には徐々にファーミキュートス（相対的存在率62.81％）に取って代わられていた。また、腸内の3大消化酵素（トリプシン、リパーゼ、アミラーゼ）は離乳中期に有意に減少し（<0.05）、肝臓の免疫経路に重要な遺伝子についても同様の結果が得られた。以上の結果から、オオクチバスの離乳期には肝臓代謝や腸内微生物群集が変化することが明らかになり、離乳期の餌源の変化に対する魚の適応についての理解が深まった。

In recent years, largemouth bass have become one of the most commonly aquacultured species in China, however, its low survival rate during larval weaning has always been a bottleneck that has restricted industrial development. Understanding the changes in liver metabolism and intestinal microflora during the weaning of largemouth bass larvae can help to design better weaning strategies and improve survival. In this study, liver mRNA and intestinal microflora 16S rRNA genes were analyzed using high-throughput sequencing at the pre, mid, and post weaning stages [15, 30, 45 days post hatching; total length (cm) were 2.21 ± 0.12, 3.45 ± 0.21, 5.29 ± 0.33, respectively]. The transcriptome results revealed that the genes with increased expression were related to amino acid metabolism in the pre-weaning stage, but they were related to fatty acid metabolism in the post-weaning stage. A similar phenomenon was observed in the intestinal microflora where the dominant microbe Proteobacteria (relative abundance 56.32%) in the pre-weaning stage was gradually replaced by Firmicutes (relative abundance 62.81%) by the post-weaning stage. In addition, the three most important digestive enzymes (trypsin, lipase, and amylase) in the intestine were significantly decreased during the mid-weaning stage ( < 0.05), which was also true for some genes crucial to immune pathways in the liver. Overall, these findings showed that weaning in largemouth bass can cause changes in liver metabolism and intestinal microbial communities, which has improved our understanding of fish adaptation to changes in food sources during weaning.

Copyright © 2020 Zhao, He, Luo, Sun, Liao, Tang, Liu and Yang.