Fig. 4.

Nuclear accumulation of HIF2α in pre-implantation embryo under different oxygen concentrations. a–d Detection of HIF2α (Green) in pre-implantation embryos at 2-cell (2-cell), 4-cell (4-cell), morula (Morula), and blastocyst (Blast) stages collected from atmospheric oxygen (a), in vivo (b), oxygen gradient (c) and hypoxia (d) groups. DNA was stained with DAPI (Blue). More than 8 embryos were examined in each stage of each condition. Scale bars: 20 μm. e Quantification of fluorescence intensity for HIF2α in embryonic blastomeres (n = 30 blastomeres per developmental stage in different oxygen conditions, 3 independent experiments). Error bars indicates SEM. Statistical analysis was carried out using two-way ANOVA with Tukey's multiple comparisons test. f Hypoxic in vitro culture reduced expression of LDHA in blastocyst stage embryos. Relative expression level of LDHA was examined by quantitative real-time PCR in blastocyst stage embryos collected from atmospheric oxygen group and hypoxia group (n = 60 embryos in each group, 3 independent experiments). The mean value for blastocysts cultured in atmospheric oxygen group was set as 1, and relative values for hypoxia group samples were calculated accordingly. Error bars represented SEM. Statistical analysis was performed using two-tailed unpaired Student’s t test. ⁎p < 0.05; ⁎⁎p < 0.01; ⁎⁎⁎p < 0.001; ⁎⁎⁎⁎p < 0.0001