Nlrp2 is Required for Early Embryonic Development ration was used to deliver silencing RNA because it is one of the most effective ways of delivering double stranded (ds)RNA and small interfering (si)RNA into mouse oocytes and early embryos [29,30]. In addition, we constructed an expression vector for Nlrp2 and microinjected it into mouse zygotes. We report here that the maternal depletion of Nlrp2 in GV- stage oocytes and zygotes results in early developmental arrest. However, overexpression of Nlrp2 in zygotes appears to lead to normal development, but increases apoptosis in blastocyst. In addition, Nlrp2 is not required for oocyte maturation. Thus, Nlrp2 can be added to the increasing—if limited—list of mammalian maternal effect genes. Results Nlrp2 mRNA Expression Levels Nlrp2 expression was detected in mouse ovaries, but not in eleven other tissues, including male testes (Fig. 1A). Within the ovary, expression was restricted to ovarian follicles at various stages (Fig. 1B). After ovulation and fertilization, the transcripts Figure 1. Developmental expression of Nllrp2 in the mouse. (A) Quantitative reverse-transcription polymerase chain reaction (qRT–PCR) with total RNA extracted from 4-week-old mouse ovary (Ov), uterus (Ut), testis (Te), kidney (Ki), lung (Lu), heart (He), liver (Li), brain (Br), stomach (St), intestines (In), muscle (Mu), spleen (Sp) were performed. Results were normalized to the abundance in the ovary and expressed as the mean 6 SEM. (B) In situ hybridization of fixed, paraffin wax-embedded 6 mm ovary sections probed with DIG-labeled Nlrp2 oligonucleotide probes. The original magnification was 6100. (C) The relative abundance of Nlrp2 transcripts in mouse oocytes and preimplantation embryos. (D) The relative abundance of Nlrp2 transcripts in different mouse cells. doi:10.1371/journal.pone.0030344.g001 PLoS ONE | www.plosone.org 2 January 2012 | Volume 7 | Issue 1 | e30344