Genome-wide identification of circular RNAs in adult Schistosoma japonicum.

Circular RNAs (circRNAs) are a class of novel, widespread, covalently closed RNAs that have played an essential role in animal gene regulation. To systematically explore circRNAs in the blood fluke Schistosoma japonicum, we performed RNA sequencing and bioinformatics analysis, and found that hundreds of circRNAs showed gender-associated expression. Among these identified circRNAs, more than 77.54% and 74.73% were putatively derived from the exon region of the genome and some circRNAs showed gender-associated expressions. The functional prediction of circRNAs (circ_003826 and circ_004690) showed potential binding sites and possibly acted as the sponge to regulate microRNAs (miRNAs) sja-miR-1, sja-miR-133 and sja-miR-3504. Altogether, these findings demonstrated that S. japonicum also contains circRNAs, which may have potential regulatory roles during schistosome development.