Fig. 8

Expression of sncRNA sub-groups per K-means clusters. CAP (caput), COR (corpus), CAU (cauda) epididymis, and ejaculated sperm (SPZ). a The proportion of expression attributable to each tsRNA isotype was computed per cluster, showing that some clusters tend to gather the expression of specific sncRNA sub-groups. For instance, Glycine isoacceptors account for a large proportion of expression within clusters 5, 8, and 9 (58%, 56%, and 70%, respectively), while glutamine and valine isoacceptors account for about 54% of expression within cluster 11 and 6, respectively. b Regarding tsRNAs, 5'-tRHs account for a large proportion of expression within clusters 2, 4, 5, and 6 (52%, 80%, 86%, and 54%, respectively), while tRF5s account for 66% of clusters 8 and 11 expression. Likewise, i-tRFs account for 50% and 82% of expression within clusters 10 and 12, respectively. c Specific patterns were also observed for rRNAs. For instance, 16S account for most of the expression within cluster 8 (64%) as well as 10–12 (55%), while 28S accounts for more than 70% of expression within clusters 1, 3, and 9. d A diversity of nucleotide composition was also observed according to K-means clusters. U1 piRNAs account for more than 80% of expression within clusters 1–4, peaking at PAR. In contrast, expression within clusters peaking at COR, CAU, and SPZ was dominated by non-U1 piRNAs. No gross enrichment for an A residue was observed at position 10, except for clusters 6 and 7 peaking at COR. e piRNAs perfectly matching mtDNA account for 18% and 55% of piRNA expression within cluster 6 and cluster 10, respectively. Mitochondrial features associated with these piRNAs were mainly coding sequences (CDS, clusters 6 and 7), 16S rRNA (cluster 11), and tRNA-Gly (cluster 12)