Fig. 2

Effect of light on zper2 expression at the blastula and gastrula stages. Embryos were kept under continuous light or dark and sampled throughout the first 10 h of development; zper2 mRNA was detected by whole-mount ISH. Shown are representative whole-mount ISH results of 3–10-h zebrafish embryos, side view; the embryonic stage and age are indicated at the top. Before transcription activation at the MBT stage (3–4 hpf), maternal zper2 mRNA was present at high levels in all embryos regardless of the light treatment. Under continuous dark, zper2 transcripts rapidly decreased, and by 5 hpf, the signal was similar to that obtained with the sense RNA control probe. Under continuous light, the decay in zper2 mRNA was substantially slower; the signal matched that obtained with sense RNA probe at 7–8 hpf.