Transcriptome analyses of potential regulators of pre- and post-ovulatory follicles in the pigeon (Columba livia)

To identify the dominant genes controlling follicular maturation, ovulation and regression for pigeon, we used RNA-seq to explore the gene expression profiles of pre- and post-ovulatory follicles of pigeon. We obtained total of 4.73 million (96% of the raw data) high-quality clean reads, which could be aligned with 20 282 genes. Gene expression profile analysis identified 1461 differentially expressed genes (DEGs) between the pre- (P4) and post-ovulatory follicles (P5). Of these, 843 genes were upregulated, and 618 genes were down-regulated. Furthermore, many DEGs were significantly enriched in some pathways closely related to follicle maturation, ovulation and regression, such as ECM-receptor interaction, vascular smooth muscle contraction, progesterone-mediated oocyte maturation, phagosome. Importantly, the DGEs in ECM-receptor interaction pathway included COL1A1, COL1A2, COL4A1, COL4A2, ITGA11, ITGB3 and SDC3, in the progesterone-mediated oocyte maturation pathway involved CDK1, CDC25A, CCNB3, CDC20 and Plk1, and in the vascular smooth muscle contraction covered CALD1, KCNMA1, KCNMB1, CACNA1, ACTA2, MYH10, MYL3, MYL6, MYL9, closely related to promoting follicular maturation and ovulation in preovulatory follicles. Moreover, it seems that the lysosomal cathepsin family has a decisive role in the regression of early stage of post-ovulatory follicle. Taken together, these data enrich the research of molecular mechanisms of pigeon follicular activities at the transcriptional level and provide novel insight of breeding-related physiology for birds.