Zebrafish TUNEL assayZebrafish embryos were collected at 54–60 hpf and fixed with 4% PFA. After methanol dehydration, rehydration, proteinase K digestion and acetone treatment, the embryos were permeabilized in incubating buffer (0.1% Triton X-100, 0.1% sodium citrate in PBS) for 30 min at RT. Then TUNEL staining was performed using the In Situ Cell Death Detection Kit TMR red (Roche) as the manufacturer’s instruction. After that, the embryos were incubated with mouse anti-GFP antibody (Abmart, M20004, 1:500) followed by incubation of Alexa-Fluor 488-conjugated secondary antibody.