Fig. 1.

GRAND-SLAM overview. After a period of labeling with 4-thiouridine (4sU), RNA is extracted from cells, treated with IAA and sequenced. Shown is a theoretical timecourse of the abundances of new and old RNA for a gene g. IAA converts incorporated 4sU into cytosine analogs with an overall rate p_c (including the incorporation rate, conversion rate and error rate), and uridines are sequenced as cytosine with an error rate p_e. Based on the observed mismatches from T to C, the proportion of new to old RNA of gene g, π_g, can be estimated using Bayesian inference. Estimates of π_g can be transformed into estimates of the gene’s RNA half-life or relative abundance measures