Identification of reproduction-related genes in the hypothalamus of sheep (Ovis aries) using the nanopore full-length transcriptome sequencing technology

The hypothalamus is the coordination center of the sheep (Ovis aries) endocrine system and plays an important role in the reproductive processes of sheep. However, the specific mechanism by which the hypothalamus affects sheep reproductive performance remains unclear. In this study, the hypothalamus tissues of high-reproduction small-tailed Han sheep and low-reproduction Wadi sheep were collected, and full-length transcriptome sequencing by Oxford Nanopore Technologies (ONT) was performed to explore the key functional genes associated with sheep fecundity. The differentially expressed genes (DEGs) were screened and enriched using DESeq2 software through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Approximately 41.75 million clean reads were obtained from the hypothalamus tissues of high- and low-reproduction sheep, after quality control, 32,194,872 high-quality full-length sequences and 2,114 DEGs were obtained, including 1,247 upregulated genes and 867 downregulated genes (P adjust < 0.05, |log2FC|>1). Some DEGs were enriched in oocyte meiosis, progesterone-mediated oocyte maturation, estrogen signaling pathway, GnRH signaling pathway and other development-related signaling pathways. The constructed protein-protein interaction (PPI) networks identified the reproduction-related genes, such as GSK3B, PPP2R1B, and PPP2CB. The results of this study will enrich and supplement the genomic information available for small-tailed Han sheep and Wadi sheep, as well as expand the understanding of the molecular mechanisms underlying the regulation of animal reproduction by the hypothalamus, and they also provided reference data for further investigations on the mechanism of high reproduction in sheep.