Relationship among AREScore, 3′UTR length, and mRNA expression level.

(A) For 6657 Drosophila mRNAs with a 3′UTR ≥10 nt, the log2-transformed expression levels, as measured by microarray analysis in SL2 cells under control conditions (dsGFP), were plotted against the AREScore. The red curve corresponds to non-linear lowess regression. (B) The 6657 mRNAs were grouped into 9 categories according to their AREScore: 0–0.99; 1–1.99; 2–2.99; 3–3.99; 4–5.99; 6–7.99; 8–11.99; 12–15.99; and ≥16. Average expression levels ± SE were determined for each group and plotted in the graph, the number n of mRNAs within each group is indicated. Asterisks mark statistically significant differences in comparison to the average expression level of all 6657 mRNAs, as determined by Student's T-test. (C) The 3′UTR length of all 6657 mRNAs was plotted against the AREScore. The red curve corresponds to non-linear lowess regression. (D) The log2-transformed expression levels of all 6657 mRNAs were plotted against the 3′UTR length. The red curve corresponds to non-linear lowess regression. (E) The 6657 mRNAs were grouped into 9 categories according to their 3′UTR length: 10–99; 100–199; 200–299; 300–399; 400–499; 500–999; 1000–1499; 1500–1999; and ≥2000 nt. Average expression levels ± SE were represented as in panel B. (F) For the 1781 mRNAs with a 3′UTR length between 200 and 499 nt, the log2-transformed expression levels were plotted against the 3′UTR length. The red curve corresponds to non-linear lowess regression, R to the Pearson correlation coefficient. (G), For the same 1781 mRNAs, the log2-transformed expression levels were plotted against the AREScore. (H) The same 1781 mRNAs were divided into two groups based on AREScores of 0–7.99 and ≥8. The same mRNAs were also divided into two equally large groups according to the 3′UTR length, and average expression levels ± SE were determined for each group.