Quantitative evaluation of 5099 yeast mRNAs with and without I-tailing. (A) Strongly correlated abundance measurements for >5000 yeast mRNAs using either standard poly(A)+ capture or I-tailing by Cid1 and capture with the oligoC adapter. (B) Estimation of median tail lengths by Nanopolish of poly(A)+ mRNAs using direct capture of poly(A)+ with the standard oligo(dT) adapter (black, 30–50 nt) or after tailing and capture with the oligoC adapter (blue, 60–80 nt). (C) Inferred length of I-tail added as a function of mRNA abundance. For each of 4965 poly(A)+ mRNAs, the estimated median poly(A) tail length was subtracted from the estimated median poly(A)poly(I) tail length and plotted versus abundance. Across a wide range of expression levels, Nanopolish estimates the added inosine polymer to be ∼27 nt. The version of Nanopolish used here has only been trained to distinguish and measure poly(A) tails (see text).
