library_construction_protocol: RNA was harvested using Rneasy mini kit (Qiagen). 2 ug of total RNA was used for the construction of sequencing libraries. We reverse transcribed 1 ug of total RNA with the partial P7 adapter (Illumina_4N_21T) and dNTPs with the addition of spiked-in azido-nucleotides (AzVTPs) at 5:1. We click-ligated the p5 adapter (IDT) to the 5′ end of the cDNA with CuAAC. We then amplified the cDNA for 17 cycles with Universal primer and 3′ indexing primer and purified it on a 2% agarose gel by extracting amplicon from 200-300 base pairs. We pooled the libraries and sequenced single-end, 75 base-pair reads on a Nextseq 550 (Illumina). PAC-seq as described in Routh et al, 2017.