Fig. 6

Knockdown of Lmx1b.1 and Lmx1b.2 affects cell fate in the isthmocerebellar region, but not the mesencephalon or ventral rhombomere 1 (R1). Lateral (A,B,G,H), dorsal (C-F) or dorsolateral views (I,J), with anterior leftwards. Embryos were injected with BX-MO (A,C,E,G,I) or B1B2-MO (B,D,F,H,J). pax5 expression (A,B), which marks the isthmus and cerebellum, is strongly reduced at 24 hpf in Lmx1b.1/2 knockdown embryos. Expression of otx2 (C,D) and mab21 (E,F), markers of the mesencephalon, is unaffected Lmx1b.1/2 knockdown embryos. Epha4a expression (G,H) marks several regions of the developing brain, including the ventral region of R1, and is unaffected in Lmx1b.1/2 knockdown embryos. Expression of en3 (I,J) marks both the tectum and the isthmocerebellar region. Knockdown of Lmx1b.1/2 results in a loss of en3 expression at the ventral isthmus, but normal expression is retained in the tectum and dorsal isthmus. Red arrowheads indicate the position of the MMR, black arrows indicate the ventral R1 staining of epha4a and horizontal lines indicate the ventral isthmic staining of en3.