Figure 6.

Despite a failure to complete S phase, embryos homozygous for dup mutations progress into mitosis. All embryos were labeled with antibodies to phosphorylated histone H3. (A,C,E) Wild-type embryos; (B,D,F) dup^a1/dup^a1. (A) Wild-type stage 10 embryo, notice PH3 labeling in discrete domains in the epidermis. (B) In this dup mutant stage 10 embryo PH3 is present throughout the epidermis. (C) Enlargement of A. (D) Enlargement of B. (E) Wild-type stage 12 embryo, with PH3 only detectable in the mitotically proliferating central nervous system and peripheral nervous system. (F) Stage 12 dup⁻ mutant embryo in which PH3 is still detectable in the epidermis.