Figure 10.

Absence of maternally supplied Idh3b causes developmental arrest. Embryos shown are from mothers whose germlines were homozygous for the indicated Idh3b alleles crossed to Df(3R)Exel6188/TM6B fathers. For embryos from Idh3b⁺, Idh3b¹, and Idh3b³ homozygous germline mothers, the segmentation protein engrailed (En) is stained using Cy3-labeled anti-engrailed (red). Since embryos from Idh3b² mutant germline mothers all arrest prior to segmentation, the Idh3b² mutant embryo shown is stained instead with DAPI (blue), which stains nuclei. Most embryos from Idh3b¹ germline mothers segment, but engrailed stripes usually show spacing defects or are fused with one another (arrow). The head region (arrowhead) is almost always reduced. Embryos from Idh3b² germline mothers all arrest during cleavage, and contain nuclei of variable size. Embryos from Idh3b³ germline mothers arrest at stages ranging from cleavage to cuticle formation; almost all of those that express engrailed have grossly abnormal striping patterns, like the embryo shown here.