Figure 3

Common element expression. Medial is to the right and dorsal is towards the top. A) E17.5 coronal bulb showing the typical punctate pattern observed with any one of 17 cDNA probes containing the common element. A) Signal is observed in the nascent EPL/GL, mitral, and granule layers. Weaker expression is observed in both the nascent EPL/GL and mitral layers along the VM surface (white box) as compared to the rest of the bulb (e.g. black box). B) Higher magnification of the black boxed area shown in (A). Note strong nuclear expression in nascent EPL/GL (arrowheads). C) Higher magnification of the white boxed area shown in (A). Note fewer cells and weaker staining as compared with (B). This is not due to a reduced number of cells in this area, as a significant number of nascent EPL/GL cells can be seen to be present that are unstained. D) Expression pattern using the 134 bp common element as probe. E) Expression pattern using a dig-labeled LNA-oligo corresponding to miR-706. (D) and (E) are qualitatively similar to (A). F) Expression pattern using an LNA oligo for miR-138. The pattern is distinct from miR-706, with no punctate expression. Scale bar = 100 μm for A; 50 μm for C, D; 75 μm for D, E, F. G) The common element is contained within an intron or 3' untranslated region. Only a portion of the 134 bp conserved sequence is shown. Sequence contained within the element matches that of miR-709 at 17/19 positions (mismatches indicated by "+"). For miR-706, a subset of the cDNAs matched the sequence perfectly, with others matching at 21/22 or 20/22 positions. The most commonly observed mismatched nucleotide occurred at the 3' end (indicated by a "+"). H) The remainder of the element corresponds to sequence upstream of the presumed pri-miRNA (shown as dashed lines and filled circles) of miR-706.