Nlrp2 is Required for Early Embryonic Development Figure 7. Development of parthenogenetic embryos derived from EP control, control siRNA and Nlrp2 siRNA-treated groups (20, 40 and 60 nM). (A) Parthenogenetic activation rate of electroporated oocytes. (B) Morphological appearance of parthenogenetic embryos after being cultured for 3.5 days. The original magnification was 6100. (C) Percentage of parthenogenetic embryos at different stages after being cultured for 3.5 days. doi:10.1371/journal.pone.0030344.g007 localization of Nlrp2 in the preimplantation embryo is very different, so the molecular function of Nlrp2 may be different from Dnmt1o and PGC7/Stella. Identification of proteins that interact with NLRP2 could provide insights into the roles of this maternal factor in regulating the critical stages of development from the oocyte to the preimplantation embryo. In summary, our data demonstrate that Nlrp2 is a maternal effect gene and required for early embryonic development in the mouse. The maternal depletion of Nlrp2 in zygotes by RNAi results in early embryonic arrest. Nlrp2 knockdown oocytes can progress through the metaphase of meiosis I and emit the first polar body; however, the development of parthenogenetic embryos derived from Nlrp2 knockdown oocytes mainly arrest at the 2-cell stage. In addition, overexpression of Nlrp2 in zygotes appears to permit normal development, but increases the incidence of apoptosis in blastocysts. Materials and Methods Ethics Statement The experimental procedure was approved by the Animal Care Commission of the College of Veterinary Medicine, Northwest A&F University. Adult male and female ICR strain mice were PLoS ONE | www.plosone.org 8 January 2012 | Volume 7 | Issue 1 | e30344