Zic2a and zic2b promote chromatophore development. Zic2 morphant embryos stained by ISH for mitfa and gch2 at 24 hpf. (A,B) Zic2a knockdown causes a mild reduction of cranial melanophore progenitors, marked by mitfa expression (21/35, 3 exp.). (C) Zic2b knockdown dramatically reduces mitfa expression in the trunk (24/27, 3 exp.). (D) Knockdown of both Zic2 proteins reduces melanophores in both cranial and trunk regions (22/29, 3 exp.) and causes NC aggregation in the cranial region (12/24, 3 exp.). (E,F) Zic2a knockdown reduces xanthophore precursors, marked by gch2 expression, in the cranial region (13/20, 3 exp.) and trunk region (16/22, 3 exp.). (G) Zic2b knockdown reduces trunk xanthophores (27/28, 3 exp.). (H) Double Zic2 knockdown decreases gch2 at both cranial and trunk axial levels (17/20 affected, 3 exp.). (I,J) Gch2-expressing cells migrating on the midbrain are wild-type in zic2a morphants (3/3, 1 exp.). (K,L) Large aggregates of migrating NC cells are observed after Zic2b knockdown (1/3, 1 exp.; asterisks in C,G,K) and double Zic2 knockdown (2/3, 1 exp.; asterisk in 7L). (A–H) are lateral views with anterior to the left, with insets showing dorsal views of the same embryos. (I–J) are transverse sections through the midbrain.
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