IDENTIFICATION AND CHARACTERIZATION OF CIRCULAR RNAS IN BLUNT SNOUT BREAM Megalobrama amblycephala

Circular RNAs (circRNAs) provide us a new perspective to study the transcriptional regulation of Megalobrama amblycephala. In order to understand the molecular structure and potential function of M. amblycephala circRNAs, a circRNA library constructed from the mixture of 10 fish tissues (brain, eyes, heart, liver, spleen, kidney, intestines, skin, muscle, gill) were sequenced, and 101958628 clean reads were obtained.

Through performing the analysis with three algorithms, find_circ, CIRI2 and CIRCexplorer, a total of 10542 circRNAs were identified (Figure 1). Of total circRNAs, 4444 (42.2%) M. amblycephala circRNAs showed their similarity with zebrafish and grass crap. 2033 circRNAs with high credibility were identified by all three algorithms. The bioinformatics analysis of those 2033 circRNAs showed that 639 (31.4%) circRNAs contained internal ribosome entry site (IRES), while 1887 (92.8%) circRNAs contained Open Reading Frame (ORF) and 581 (28.6%) circRNAs with both IRES and ORF had the potential to translate proteins (Figure 2). Mam_circ_9493, Mam_circ_2856, Mam_circ_1505, Mam_circ_922, Mam_circ_2817, Mam_circ_2818 contained multiple miRNAs binding sites, and Mam_circ_8063, Mam_circ_8064 and Mam_circ_8065 contained multiple U7 small nuclear RNA, indicating the potential of circRNAs to participate in gene regulation via small RNA.