Introduction Perinatal and dry periods are important physiological stages for cows to recover after calving and improve lactation performance. Exploring the expression characteristics of circRNAs as a molecular hotspot during the perinatal and dry periods of dairy cows is of great significance. Methods This study identified and compared circular RNAs (circRNAs) in the mammary tissue of three cows between the perinatal and dry periods. After analysis, we identified 10,388 circRNAs, ranging from 48 bp to 99,406 bp. Results Chromosome 1 had the most circRNAs, containing 597 circRNAs. Furthermore, 91.97% of the circRNAs belonged to sense-overlapping circRNA. CircRNAs contain different number of exons, ranging from 1 to 47 and most of the cirsRNAs harbored 1 to four exons. Compared with dry period, 132 circRNAs with significantly different expressions were identified in the perinatal period, 99 of which were upregulated and 33 downregulated. Enrichment analysis revealed the enrichment of circRNAs in the proliferation and differentiation of cells, such as regulation of chondrocyte differentiation and integral component of plasma membrane, phosphatidylinositol 3-kinase binding. The significantly enriched pathways further indicate that circRNAs play important roles in immunity and infection, such as cell adhesion molecules (CAMs), herpes simplex infection, and Kaposi’s sarcoma-associated herpesvirus infection. Discussion This study revealed the expression profile and characteristics of circRNAs in the perinatal and dry period of Holstein cows, thus providing rich information for studying circRNAs functions and mechanisms underlying perinatal and dry period diseases, suggesting a new avenue to investigate the regulatory mechanisms of dairy cow genetic breeding.
Liang et al. (Mon,) studied this question.