Table1_Identification and Functional Prediction of Circular RNAs Related to Growth Traits and Skeletal Muscle Development in Duroc pigs.DOCX

Porcine skeletal muscle is a highly heterogeneous tissue type, and the Longissimus Dorsi muscle (LDM), as the most economical and physiologically metabolized skeletal muscle in pigs, has always been the focus of research and improvement in pig molecular breeding. Circular RNA, as an important new member of regulatory non-coding RNA after microRNA, has become a frontier hot spot in life science research. This study aims to explore candidate circRNAs related to growth, meat quality, and skeletal muscle development among Duroc pigs with different average daily gain (ADG). Eight pigs were selected and divided into two groups: H group (high-ADG) and L group (low-ADG), followed by RNA-Seq analysis to identify circRNAs. The results showed that backfat at 6-7 rib (BF) and Intramuscular fat (IMF) content in the H group was significantly lower than L group, but ribeye area (REA) in the H group was higher than in the L group. In RNA-seq, 296 Differentially expressed (DE) circRNAs (157 upregulated and 139 downregulated) were identified and exons flanking long introns are easier to circularize to produce circRNAs. Most of the DE circRNAs were enriched in Quantitative trait locus (QTL) regions related to meat quality and growth traits. In addition, a gene can produce one or more circRNA transcripts. It was also found that the source genes of DE circRNAs were enriched in MAPK, FoXO, mTOR, PI3K-Akt, and Wnt signaling pathways. The results showed that different ADG, carcass, and meat quality traits among half-sibling Duroc pigs with the same diet may be due to the DE circRNAs related to skeletal muscle growth and development.

猪骨骼肌是一种高度异质性的组织类型，而背最长肌（Longissimus Dorsi Muscle, LDM）作为猪中经济价值与生理代谢特性最为突出的骨骼肌，一直是猪分子育种研究与改良的重点对象。
环状RNA（Circular RNA, circRNA）作为继微小RNA（microRNA）之后的一类重要新型调控非编码RNA，已成为生命科学研究的前沿热点。本研究旨在探究不同日增重（average daily gain, ADG）的杜洛克猪中与生长、肉质及骨骼肌发育相关的候选环状RNA。
本研究选取8头杜洛克猪，分为高日增重组（H组，高ADG组）与低日增重组（L组，低ADG组），随后通过RNA测序（RNA-Seq）分析鉴定环状RNA。
结果显示，H组的6-7肋背膘厚（BF）与肌内脂肪（IMF）含量均显著低于L组，但其眼肌面积（REA）显著高于L组。
通过RNA-seq分析，共鉴定出296个差异表达环状RNA（DE circRNAs），其中157个上调表达、139个下调表达；侧翼带有长内含子的外显子更易发生环化并产生环状RNA。大部分差异表达环状RNA富集于与肉质及生长性状相关的数量性状基因座（Quantitative trait locus, QTL）区域。
此外，单个基因可产生一种或多种环状RNA转录本。研究还发现，差异表达环状RNA的宿主基因显著富集于MAPK、FoXO、mTOR、PI3K-Akt及Wnt信号通路。
研究结果表明，在饲喂相同日粮的半同胞杜洛克猪中，个体间日增重、屠宰及肉质性状的差异，可能与调控骨骼肌生长发育的差异表达环状RNA密切相关。