Small RNA-Seq analysis of miRNA isoform (isomiR) expression in single porcine Day 10 blastocysts and analysis of effects of maternal estradiol-17-beta feeding from day of ovulation until Day 10 of pregnancy. Small RNA-Seq analysis of miRNA isoform (isomiR) expression in single porcine Day 10 blastocysts and analysis of effects of maternal estradiol-17-beta feeding from day of ovulation until Day 10 of pregnancy

Small RNA sequencing of 36 porcine embryo samples collected on Day 10 of pregnancy detected miRNA sequences mapping to known and predicted porcine miRNAs, and novel miRNAs highly conserved in human and cattle. A set of highly abundant miRNAs was identified as well as a large number of rarely expressed miRNAs. Due to the high number of generated sequence reads, it was possible to detect a large number of different miRNA isoforms (isomiRs). Potentially embryo-specific miRNAs were identified by comparing the data with small RNA-Seq data sets from porcine endometrium and a search in databases for miRNA tissue expression. The identification of 140 novel miRNAs in addition to 173 known porcine miRNAs (miRBase21) showed the benefit of our small RNA analysis pipeline. This benefit has a big impact for poorly annotated species such as the pig where it is possible to annotate many additional miRNAs based on the knowledge from related species. Furthermore, we integrated our pipeline into a Galaxy workflow using standard Galaxy tools which guaranties high reproducibility and flexibility for new/upcoming datasets/studies. Using ortholog species information increases the total number of annotated miRNAs while mapping to other non-coding RNAs decreased the chances of falsely annotated miRNAs. Galaxy workflows can be published, shared, downloaded, and optimized to adapt to other species or modify analysis parameters, such as tools specifically developed for a given research project/problem, so that a broad audience can use it.