Comparative expression of selected miRs in the retina, brain, and mouse platform. Bars represent deviations from mean expression levels for each microRNA (miR) on a log2 scale in c57 retina (dark blue), c57 brain (light blue), and mouse platform (magenta). (a) Relative expression of some known retinal miRs. (b) Relative expression of miRs with novel retinal specificity. Panels a and b display data from miR microarray experiments. (c) Quantitative real-time reverse transcription polymerase chain reaction (qPCR) validation of expression of selected miRs. Note that columns are in descending order of difference between retinal and platform expression; y-axes are to different scales; and bars for miR-181a in brain and miR-204 in mouse platform are missing in panel a because of incomplete data.