Absence of metazoan-like auxiliary elements in protists. (A) Comparison of the UGUA versus its shuffled versions 20–50 nt upstream of the cleavage site in human versus protists. Each data point represents the total number of either UGUA tetramers (red) or its shuffled versions (gray) and the bar shows the mean count value for all compared combinations. We observed human-like enrichment only in N. gruberi. Statistical analysis is presented in Supplemental Figure S2. (B) Enrichment of GU and U-rich elements calculated in the region 40 nt downstream from the cleavage site in comparison to the region 40 nt upstream to the cleavage site. Each point on the box and whisker plot represents the log2 ratio from downstream versus upstream quantity of one of the CUGCCU, CUGGGG, CUGUGU, GUCUGU, GUGUCU, GUGUGU, UGUCUC, UGUCUG, UGUGUG, UGUUUU, UUAUUU, UUUCUU, UUUUUU sequences. Statistical significance was calculated in comparison to human enrichment using a one-sided Wilcoxon rank sum test.
