Figure 2. The effect of melatonin on histone methylation at H3K4me2 of prolonged-culture oocytes. Porcine oocytes matured in vitro were continuously cultured in medium supplemented with or without 10−3 M melatonin for 24 h. (A) Representative images of fresh, prolonged-culture and prolonged-culture + Mel oocytes stained with H3K4me2 antibody. (B) Quantitative analysis of H3K4me2 fluorescence intensity. The data are presented as mean ± SEM of at least three independent experiments. PC, prolonged-culture; Mel, melatonin; Scale bar=100 μm. Data are expressed as the mean ± SEM, ****P<0.0001.