Small RNA sequencing of hypothalamic miRNAs in Sunite sheep under different photoperiod conditions
This project investigates the role of microRNAs (miRNAs) in the hypothalamic regulation of seasonal estrus in Sunite sheep (Ovis aries). The hypothalamus plays a central role in controlling reproductive processes through the hypothalamic-pituitary-gonadal (HPG) axis. To elucidate how photoperiod affects miRNA expression patterns in the hypothalamus, we performed small RNA sequencing on hypothalamic tissues collected from ovariectomized estradiol-treated ewes exposed to three different photoperiod conditions: short photoperiod (SP, 8L:16D), long photoperiod (LP, 16L:8D), and short-to-long photoperiod transition (SLP).Nine healthy 3-year-old Sunite ewes were randomly assigned to three groups (n=3 per group): SP42 (short photoperiod for 42 days), LP42 (long photoperiod for 42 days), and SLP42 (transition from short to long photoperiod, sampled at day 84). Total RNA was extracted from hypothalamic tissues and small RNA libraries were constructed using the NEB Next Ultra Directional RNA Library Prep Kit. Sequencing was performed on the Illumina HiSeq 4000 platform (150 bp paired-end).This study identified differentially expressed miRNAs (DEMs) between different photoperiod groups and constructed miRNA-mRNA co-expression networks. Key miRNAs including oar-miR-370-5p, oar-miR-10b, and oar-miR-3957-3p were identified as potential regulators of seasonal estrus. Functional enrichment analysis revealed that target genes of DEMs were significantly enriched in pathways related to reproduction, including GnRH signaling pathway, prolactin signaling pathway, and Wnt signaling pathway. These findings provide insights into the molecular mechanisms underlying photoperiod-dependent reproductive regulation in sheep.