Comparative analysis of known mi RNA s across platyhelminths

Micro RNA s (mi RNA s) are a subtype of small regulatory RNA s that are involved in numerous biological processes through small RNA ‐induced silencing networks. In an attempt to explore the phylogeny of mi RNA s across five platyhelminths, we integrated annotated mi RNA s and their full genomes. We identified conserved mi RNA clusters and, in particular, miR‐71/2 was conserved from planarian to parasitic flatworms and was expanded in free‐living S chmidtea mediterranea . Analysis of 22 mi RNA loci provided compelling evidence that most known mi RNA s are conserved across platyhelminths. Meanwhile, we also observed alterations of known protein‐coding genes flanking mi RNA (s), such as transcriptional direction conversion and locus relocation, in around ~ 41% of 22 known mi RNA loci. Compared with E chinococcus multilocularis , the majority of these events occurred in evolution‐distant H ymenolepis microstoma , S chistosoma japonicum or/and S . mediterranea . These results imply rearrangement events occurred near the known mi RNA loci.