The miRnome of Fasciola hepatica juveniles endorses the existence of a reduced set of highly divergent micro RNAs in parasitic flatworms.

The miRnome of Fasciola hepatica juveniles endorses the existence of a reduced set of highly divergent micro RNAs in parasitic flatworms.

Fontenla S, Dell’Oca N, Smircich P, Tort JF, Siles-Lucas M.

Int J Parasitol. 2015 Sep 30. pii: S0020-7519(15)00248-9. doi:10.1016/j.ijpara.2015.06.007. [Epub ahead of print]

The liver fluke Fasciola hepatica is a foodborne zoonotic parasite affecting livestock worldwide, with increasing relevance in human health. The first developmental stage that the host meets after ingestion of the parasite is the newly excysted juvenile. The regulation of the early developmental events in newly excysted juveniles is still poorly understood. Here we investigated the putative involvement of small regulatory RNAs in the invasion process. We identified 45 different miRNAs.

Remarkably, several protostomian and metazoan conserved families were not detected, showing a drastic miRnome reduction in parasitic flatworms. Finally, the distinctive presence of tRNA-derived sequences, mostly 5′ tRNA halves of selected tRNAs in the small RNA population of newly excysted juveniles, raises the possibility that both miRNA and tRNA fragments participate in the regulation of gene expression in this parasite.