Plcz1 mRNA can activate oocytes fertilized with Plcz1 mutant spermatozoa. (a) RT–PCR analysis of testicular RNA. Actb; actin beta. (b) Immunoblot of sperm proteins. Full–length blots are presented in Supplementary Figure 5a and e. (c) The percentages of oocytes with specified numbers of PN 12 h after IVF with Plcz1 point mutant mice. (d) Ratio of GEM-GECO fluorescence of oocytes after ICSI (upper) or 2 ng/µl mouse Plcz1 mRNA injection following ICSI (lower). Images of oocytes 8 h after ICSI or mRNA injection are shown. Nuclei/PN were visualized with H2B-mCherry (red). Scale bar = 20 μm. (e) Representative host mother and pups from ICSI-rescued embryos.