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Fig. 2. Barhl2-depleted embryos exhibit defects in p2 alar plate patterning. Gene expression profiles of forebrain markers in Barhl2 morphants (MObarhl2) are shown at st. 27, st. 32 and st. 37 as indicated. Both the control (CT) and the injected (INJ) sides of a representative neural tube are shown, anterior left, dorsal up, allowing direct comparison of expression territories. n: number of embryos analyzed. The scale bar stands for 0.4 mm. In Barhl2-depleted embryos (A) the p3–p2 limit, marked by the caudal limit of the dorsal prethalamic marker fezf2 (n=24), or (B) arx2 (n=24) is established properly. The p2-like cells in MObarhl2-injected embryos are present and, at least in part, specified as shown by (C) the expression of the p2 basal plate marker nkx2.1 (n=16), (D) that of otx2 (n=24) and (E) tcf4 (n=20). However, the p2 alar plate is misspecified: (F) the domain in which pax6 is expressed spreads ventrally inside the mid-diencephalic furrow (n=20); In the rostral p2 (G) irx3 expression remains unchanged compared to the CT side (n=24); Conversely (G) irx3 expression is expanded in the caudal p2 of barhl2-depleted embryos (n=24), and expression levels of both caudal p2 markers (H) irx1 (n=24) and (I) irx2 (n=36) were down-regulated upon depletion of Barhl2 activity. (J) At st. 37 the progression of shh inside the p2 alar plate is inhibited (n=16). |
