Frozen cells with lysis buffer were  mechanically lysed using liquid nitrogen-chilled 50 mL canisters for six cycles of 3 min at 15 Hz using a Retsch MM301 mixer mill Lysates were treated with RNase I and pelleted through a 24% sucrose cushion to isolate ribosomes, crosslinks were reversed, and protected RNA fragments were isolated using acid phenol chloroform. Gel-purified RNA was treated with PNK and ligated to a pre-adenylated adapter (CTGTAGGCACCATCAATNNNNNNNNNN) using T4 RNA ligase 2, K227Q, truncated. Superscript III was used for reverse transcription and circ ligase for circularization. Illumina adapters were introduced by 10-14 cycles of PCR.