Fig. 6. The mao mutation diminishes an early sign of programmed cell death – DNA fragmentation. (A) Mao mutant (bottom) and sibling (top) 36 hpf embryos were co-processed for HuA immunocytochemistry (left) and TUNEL (middle; see Materials and Methods). In the merged images (right), fewer TUNEL-positive RB cells are present in the mao mutant versus the sibling embryo. Scale bar:10 µm. (B) Cell counts of TUNEL-positive RB neurons indicate that there are significantly fewer TUNEL-positive RB neurons in 36 hpf mao mutants compared with siblings (P<0.05; n=4 and n=3, mutants and siblings, respectively).