Characterisation of sperm piRNAs and their correlation with semen quality traits in swine

Piwi-interacting RNAs (piRNAs) are a class of non-coding RNAs which main reported function consists on the silencing of transposable elements and genome stability in mammalian germline. In this study we have identified piRNAs in porcine sperm, using male germline and zygote datasets from human, mice, cow and swine, and evaluated the relation between their abundances and sperm quality traits. Our analysis identified 283,382 piRNAs, 1,355 of which correlated to at least one semen quality trait. Indeed, genome analysis of the correlated piRNAs evidenced that 57% of these were less than 50kb apart and were significantly enriched near Long Interspersed Nuclear Elements (LINEs). Moreover, some of the significant piRNAs mapped within or close to genes relevant for fertility or spermatogenesis such as CSNK1G2 and PSMF1 .