Prior to preparation of sequencing libraries, rRNA was removed by poly(A)+ selection (CD19+ B-cells, CD8+ T-cells, 500 ng) or rRNA depletion (fetal heart, 1 ug). Poly(A)+ selection was done twice by using Dynabeads Oligo(dT)25 (Life Technologies) according to the manufacturer's manual. rRNA depletion was done by using Ribo-Zero rRNA removal kit (Epicentre, Illumina) according to the manual. The treated RNA was dissolved in 20 μL water.
