Fig. 4

Circular RNAs are induced during development. a Genome-wide distributions of z scores for linear and circular junctions in our heart and lung data show significant skewing of z scores in circular junctions towards positive values corresponding to circular RNA induction. b Quantitative RT-PCR confirms greater induction of circular RNA in several organs; heart and lung are shown here (intestine and stomach in Additional file 14). Plotted values are ΔΔCt = ΔCt(Age 20 weeks) – ΔCt(Age 10 weeks), where ΔCt = Ct(ACTB) – Ct(target); error-bars are standard error of the mean of technical replicates. Positive ΔΔCt indicates increased expression later in development, and is log2 scale. c A similar trend is seen in the ENCODE data: 14 out of 20 tissues, including heart and lung, have a majority of genes with increasing circular:linear expression compared with decreasing circular:linear expression (genes called with p < 0.05). Net # genes with circle fraction increasing is defined as Number of genes with circle fraction increasing from early to late timepoint – Number of genes with circle fraction decreasing. Tissues not labeled in the figure contained in the 0–500 bar are spinal cord, thyroid, metanephros, liver, umbilical cord, occipital lobe, cerebellum, diencephalon, uterus (all with data only available from ENCODE)