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Knock-down of nr4a2a and nr4a2b reveals different requirements for formation of DA neurons in pretectum, preoptic area and retina. Morphant embryos were analyzed for th expression by WISH at 72hpf. Embryos injected with control morpholino showed normal formation of CA groups, including DA neurons in the pretectum (A, arrow), the preoptic region (A, arrowhead) and in the retina (C, arrow). The injection of MOnr4a2, which targets both nr4a2 genes, leads to a strong reduction of DA neurons in the pretectum (B, arrow), in the preoptic region (C) and in the retina (D). The same phenotype is observed upon injection of a morpholino targeting only nr4a2a (MOnr4a2a) (E-F). However, the same DA groups are unaffected by injection of a morpholino targeting nr4a2b (MOnr4a2b) (I-L). Knock-down of nr4a2b leads only to a mild reduction of th expressing DA amacrine cells (L, arrow), as compared to controls (K, arrows). Scale bar: 100 μm.
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