Specification in hab mutants before and during gastrulation. In the following experiments, all hab-/+ embryos are zygotic maternal dominant (ZMD) embryos; during these stages, in situ analysis cannot distinguish between the wild-type and dominant phenotypes. Embryos were genotyped after completion of photography as outlined in the Experimental Procedures section. All embryos are dorsal views with the animal pole to the top, and arrows indicate the width of the axial expression pattern, except C, which is a side view with dorsal to the right and arrows indicate the anteroposterior extent of expression. Arrowheads indicate the edge of the blastoderm margin in mutant embryos. A: Expression of goosecoid, 40% epiboly, in wild-type and hab-/-, dorsal view. B: Expression of FoxA2/axial/forkhead 1, 75% epiboly in wild-type and hab-/-. C: Expression of gata2, 75% epiboly in wild-type and hab-/- (C). Arrows indicate the expression domain. D: sonic hedgehog, tail bud stage in wild-type and hab-/-. Note the absence of expression in the anterior neural plate of the mutant. E,F: FoxB1/mariposa/forkhead 3, 75% epiboly and tail bud stage in ZMD hab-/+ and hab-/-. E′ and F′: Arrows indicate widening of the midline in the mutants. F′: Note gaps in the midline and absence of anterior forebrain expression. G,H: no tail, 75% epiboly and tail bud stage in wild-type and hab-/-. Ectopic forerunner cell clusters are indicated by asterisks. Wild-type embryos in G are from hab-/+ mothers. I,J: spadetail, 75% epiboly and tail bud stage in wild-type, ZMD hab-/+ and hab-/-. K,L: paraxial protocadherin, 75% epiboly and tail bud stage in wild-type, ZMD hab-/+and hab-/-. Note that, in the hab-/- mutants, expression of both spadetail and paraxial protocadherin in the prechordal plate is retained longer.
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