Figure 3. Expression analysis of miRNA lacZ reporter.

(A) LacZ reporter expression in E11.5 embryos. Embryos for miR-30b/30d, miR-30e, miR-130a, miR-296/298, miR-301a, and miR-339 displayed lacZ expression ubiquitously, whereas embryos for miR-210, miR-146a, mir-688, miR-497/195, and miR-654/376b exhibited no expression. The central nervous system was positive for miR-7a-2, miR-135b, and miR-325. Embryos for miR-141/200c showed staining only in the nostrils, as shown with arrows. Posterior trunk staining was detected for miR-196a-1. Although both expressed in pharyngeal arches and limb buds, expression patterns of miR-130b/301b and miR-205 were distinct. In addition, miR-130b/301b embryos displayed forebrain staining. (B) lacZ reporter expression in E18.5 embryos and adult. Brains of E18.5 embryos for miR-7a-2, miR-135b, and miR-325 displayed broad lacZ expression, whereas miR-688 exhibited very restricted expression domain in the dorsal cortex and ventral mid-brain (for each miRNA, top and bottom panels correspond to dorsal and ventral view respectively). Expression of miR-135b was also found in the inner ears (semicircular canals, vestibule and cochlea), while miR-325 expression was found in the visual sensory system (eyes, optic tracts, and lateral geniculate nucleus). The spinal cord staining was detected for miR-325. The CNS expression pattern of miR-7a-2 was maintained in adults as shown in the vibratome-sectioned brain. Expression of miR-141/200c was found in the airways of the respiratory tract, including in the nasal cavity, trachea, bronchi, and bronchioles, as well as in olfactory bulbs in the brain. Expression of miR-497/195 was found both in the airways and the air sacs of the lungs. Kidneys of miR-196a-1 displayed a striking lacZ staining pattern. For miR-654/376b, the frontal portion of the ribcage (corresponding to cartilage at this developmental stage) stained positive in E18.5 embryos.