Circular RNAs (circRNAs) play key roles in several biological processes in animals and their regulatory mechanism in body color formation or pigmentation in fish remains unclear. Here, circRNAs from black and red individuals of Plectropomus leopardus were identified to clarify the mechanism of circRNAs and the competing endogenous RNA (ceRNA) network (circRNA-microRNA (miRNA)-messenger RNA (mRNA)) in body color formation. We detected a total of 1,424 novel circRNAs. Expression analysis of circRNAs in black vs. red P. leopardus revealed 24 differentially expressed circRNAs (DECs), and 11 and 13 of these DECs were up-regulated and down-regulated in red individuals relative to black individuals, respectively (P<0.05 and |log2 Fold Change (FC)|>1). We identified a total of 19 significant miRNA-circRNA-mRNA ceRNA networks through the analysis of DECs, differentially expressed miRNAs (DEMs) and differentially expressed genes (DEGs). Pathway enrichment analyses of the DEGs involved in the ceRNA network revealed that they were mainly involved in melanin metabolism and immune response. Our findings showed the possibility of the regulatory functions of circRNAs and the corresponding ceRNA network in the body color formation process and will aid the breeding selection process of P. leopardus.

中文翻译：

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不同体色豹珊瑚石斑鱼 (Plectropomus leopardus) 的 circRNA 的鉴定和表征

环状 RNA (circRNA) 在动物的几个生物过程中起着关键作用，它们在鱼类体色形成或色素沉着中的调节机制仍不清楚。在这里，来自黑色和红色个体的 circRNA豹蛱蝶确定了circRNA和竞争性内源性RNA（ceRNA）网络（circRNA-microRNA（miRNA）-信使RNA（mRNA））在体色形成中的机制。我们共检测到 1,424 个新的 circRNA。黑色与红色 circRNA 的表达分析P. leopardus揭示了 24 个差异表达的 circRNAs (DECs)，其中 11 个和 13 个 DECs 在红色个体中相对于黑人个体分别上调和下调（P<0.05 和 |log2个折叠变化(FC)|＞1)。通过对 DEC、差异表达 miRNA (DEM) 和差异表达基因 (DEG) 的分析，我们总共鉴定了 19 个重要的 miRNA-circRNA-mRNA ceRNA 网络。对 ceRNA 网络中涉及的 DEG 的通路富集分析表明，它们主要参与黑色素代谢和免疫反应。我们的研究结果显示了 circRNA 和相应的 ceRNA 网络在体色形成过程中的调节功能的可能性，并将有助于育种选择过程P. leopardus.