Abstract:

The purpose of this study is to screen candidate genes associated with muscle growth in Dexin mutton type fine-wool sheep at different developmental stages using RNA-Seq technology, preliminarily elucidate the molecular mechanisms underlying differential development of the longissimus dorsi muscle, and provide a theoretical foundation for muscle growth research in this breed. Male Dexin mutton type fine-wool sheep at 3, 6, and 12 months of age, raised under identical conditions, were utilized as research subjects. Carcass traits of the longissimus dorsi muscle were analyzed and compared. Transcriptomic sequencing was performed on the longissimus dorsi muscle using the Illumina NovaSeq platform for mRNA sequencing and analysis to identify candidate genes influencing muscle growth. RNA-Seq analysis identified 2468 differentially expressed genes (DEGs) across the three age groups. Among these, 30 DEGs were commonly expressed in all three groups, while 468, 458, and 544 DEGs were specifically expressed in the 3-month, 6-month, and 12-month groups, respectively. Gene Ontology (GO) functional annotation revealed significant enrichment of DEGs in 2997 GO terms (P<0.05). Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis demonstrated DEG involvement in 93 pathways, including growth-related pathways such as: JAK-STAT signaling pathway, PI3K-Akt signaling pathway, MAPK signaling pathway, Cytokine-cytokine receptor interaction, and FoxO signaling pathway. Subsequent screening prioritized two key candidate genes (IGF2 and MYL4). The candidate genes IGF2 and MYL4 provide critical molecular insights into muscle growth and development, establishing a theoretical basis for subsequent research on muscle regulation in Dexin mutton type fine-wool sheep.

Key words: Dexin mutton type fine-wool sheep, candidate genes, muscle tissue, transcriptome, functional analysis