Biological functions of circRNAs and their progress in livestock and poultry.

CircRNAs are a new member of endogenous RNAs, which characterized by a closed-loop structure without terminated 5' caps and 3' tails via covalent bonding, which are evolutionarily conserved among different species and often exhibit tissue or developmental stage-specific expression. So far, thousands of circRNAs have been discovered in eukaryotic cells. CircRNAs are more stable due to its resistance to exonuclease implying important biological functions in all kingdoms of life. They could function as miRNA sponges, interfere with splicing and bind to protein to regulate the expression of host genes and so on. In addition, emerging evidence suggests that circRNAs are closely related to a series of physiological processes in livestock and poultry. In this review, we summarized the biogenesis mechanism, major biological function and detection methods and focused on research advance of circRNAs in livestock and poultry, aiming at providing certain reference value and novel techniques for the development of new molecular genetic markers and breeding of livestock and poultry. Meanwhile, we hope this review could show significant prospect for other researches.