Fig. 9

Fig. 9 5-Azacytidine treatment of zebrafish embryos causes loss of no tail in the notochord and eng2 expression in muscle pioneer cells. (A) In 19-h wild-type zebrafish embryos, no tail is expressed in continuous pattern in cells of the differentiated notochord (n) and the caudal mesoderm of the tail bud (tb). (B. C) no tail expression in 24-h 5-azaC-treated embryos is discontinuous ranging from (B) short gaps of absent expression along the body axis or (C) nearly complete loss of expressing cells. Expression of no tail in the tailbud mesoderm is normal in 5-azaC-treated embryos. (D) Wild-type embryos express eng2 in the muscle pioneer cells (mp) located at the horizontal septum of developing somites and in cells at the mid/hindbrain boundary (mh). (E, F) 5-AzaC-treated embryos show loss of expression of eng2 in the muscle pioneers cells, but maintains normal eng2 expression in the mid/hindbrain boundary. (G, H), Transverse sections of double-labeled embryos with antisense probes for no tail and eng2. (G) Controls. The muscle pioneer cells are indicated by an arrow. (H) 5-AzaC-treated embryos. No expression of eng2 in the muscle pioneer cells was observed despite the presence of no tail-expressing notochord cells (n). Scale bar: A–F, 220 μm; G and H, 95 μm.