Fig. 1

The zygotic ERK1/2 is essential for preimplantation development. A, B Heatmap and boxplot revealed dynamic expression of MAPKs during early embryo development. C H3K9me2 deposition in zygotes treated with inhibitors of different MAPKs pathways at PN4–5 (10 hpf). DNA is stained using Hoechst33342 (blue). Scale bars, 20 µm. D Quantification is represented as the mean of H3K9me2 signal intensity in pronuclei after background subtraction (left axis) or a ratio between parental pronuclei signals (pat./mat., right axis). Each data point represents an independent zygote. Number of zygotes analysed for each group: control n = 22; iMEK1/2 + ip38 n = 27; iERK1/2 (100 μM GDC-0994) n = 19. E Time scheme of zygote collection and embryo recovery. F Representative bright-field images of blastocysts recovered from the control (left), the 50 μM (middle), and 100 μM (right) GDC-0994-treated group. Black asterisks indicate examples with normal morphology; black arrows denote the abnormal embryos with the reduced cavity. Scale bars, 100 µm. G Percentage of abnormal embryos after ERK1/2 inhibition. From three independent experiments (total number of embryos analysed: 2-cell embryos, n = 205 for Control, n = 193 for 50 μM GDC-0994 treatment, n = 209 for 100 μM GDC-0994 treatment; 4-cell embryos, n = 198 for Control, n = 176 for 50 μM GDC-0994 treatment, n = 176 for 100 μM GDC-0994 treatment; blastocysts, n = 172 for Control, n = 134 for 50 μM GDC-0994 treatment, n = 97 for 100 μM GDC-0994 treatment). H Upregulation of Oct4, Nanog, Sox2, and Klf4 in GDC-0994 treatment blastocysts as revealed by quantitative PCR. P values are indicated. Error bars indicate SD. ♀, maternal pronucleus; ♂, paternal pronucleus. PB, polar body