Zebrafish mpo expression incloche and retsina mutant embryos.

In situ hybridization using a digoxigenin-labeled RNA probe against zebrafish mpo (purple) and αE1 (red). Expression of mpo in wild-type (A,C,E) and clochemutant embryos (B,D,F). Cloche mutants (bloodless) at 1 dpf (B), 2 dpf (D), and 4 dpf (F) lack mpo staining except for rare cells in the posterior blood island (B,D,F; black arrowhead). Wild-type siblings at 1 dpf (A), 2 dpf (C), and 4 dpf (E); note purple-stained cells expressing mpo. Expression ofαE1 and mpo in wild-type (G) andretsina mutant (H) embryos at 4 dpf. Retsinamutant at 4 dpf (H) with normal mpo expression (purple-stained cells) but low expression of αE1(red-stained cells) relative to a wild-type sibling (G). Lateral views, dorsal upward and anterior to the left.