brd2 paralogs are differentially expressed in head and trunk regions of pharyngula stage embryos. Whole mount in situ hybridizations to RNA in 44–48 hour zebrafish embryos with DIG-labelled zf626 (A-F) and zf69 (G, H) cloned sequences. Dorsal (A) and lateral (B) views of whole embyros show brd2 expression abundant in all brain subdivisions and developing pharyngeal arches, and in neural retina (nr), otic vesicle (ov), pectoral fin buds (fb) and ventral trunk. Cross sections at levels indicated in A, reveal brd2 expression in: C) mesencephalon (m), diencephalon (d) and neural retina (nr); D) in cells of otic vesicle walls (ov, black arrows); E) in caudal hindbrain (hb), endoderm of prospective digestive tract (en), and pectoral fin bud (fb); F) in developing spinal cord (sc), posterior lateral line primordium (lat), pronephric duct (pn), and endodermal tissue (en), including pancreas progenitor (p) and developing gut (g). Signal in hollow of otic vesicle (white arrows in D) is an artefact due to trapped probe. Although brd2b (G dorsal, H lateral) is also expressed in head region and pectoral fin buds (fb), it is reduced in dorsal midbrain, caudal hindbrain, and ventral trunk, and absent from neural retina (nr, white arrow) and otic vesicle (ov, white arrow). Bar = 250 μm for A,B,G,H; = 100 μm for C, D (two right images); = 25 μm for D (left image).
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