Figure 2.
(a–d) Validation of metatranscriptomic approach in synovial fluid. Results of the analytical validation experiments using four distinct tenfold serial dilutions of the ERCC RNA spike-in control mix in RNA extracted from synovial fluid. Three replicates were performed at each dilution level with sequences classified as ERCC or non-ERCC using the k-mer based annotation tool CLARK. (a–d) The correlation between expected molecules per µL of each ERCC transcript and the average observed read counts of each unique ERCC transcript at concentrations of 1.8 × 109–8.6 × 102 molecules/µL (a), 1.8 × 108–8.6 × 101 molecules/µL (b), 1.8 × 107–8.6 molecules/µL (c), and 1.8 × 106–8.6 × 10–1 molecules/µL (d).