Preimplantation death of xenomitochondrial mouse embryo harbouring bovine mitochondria

Abstract

Mitochondria, cellular organelles playing essential roles in eukaryotic cell metabolism, are thought to have evolved from bacteria. The organization of mtDNA is remarkably uniform across species, reflecting its vital and conserved role in oxidative phosphorylation (OXPHOS). Our objectives were to evaluate the compatibility of xenogeneic mitochondria in the development of preimplantation embryos in mammals. Mouse embryos harbouring bovine mitochondria (mtB-M embryos) were prepared by the cell-fusion technique employing the haemagglutinating virus of Japan (HVJ). The mtB-M embryos showed developmental delay at embryonic days (E) 3.5 after insemination. Furthermore, none of the mtB-M embryos could implant into the maternal uterus after embryo transfer, whereas control mouse embryos into which mitochondria from another mouse had been transferred developed as well as did non-manipulated embryos. When we performed quantitative PCR (qPCR) of mouse and bovine ND5, we found that the mtB-M embryos contained 8.3% of bovine mitochondria at the blastocyst stage. Thus, contamination with mitochondria from another species induces embryonic lethality prior to implantation into the maternal uterus. The heteroplasmic state of these xenogeneic mitochondria could have detrimental effects on preimplantation development, leading to preservation of species-specific mitochondrial integrity in mammals.

Trophectoderm regeneration to support full-term development in the inner cell mass isolated from bovine blastocyst

“…Mouse and bovine preimplantation embryos for analyses in this study were produced using in vitro fertilization (IVF), as described in our previous studies (30,55). In mice, female ICR or BDF1 (C57BL/6N ϫ DBA/2N) mice were superovulated by injections of 5 IU PMSG (ASKA Pharmaceutical Co., Ltd., Tokyo, Japan) and 5 IU equine chorionic gonadotropin (ASKA Pharmaceutical Co., Ltd.), administered 48 h apart.…”

Overgrowth of mice generated from postovulatory‐aged oocyte spindles

“…20,24 Briefly, the zona pellucida (ZP) around the first polar body of each 0 h-oocyte was cut using a glass knife in M2 medium supplemented with 7.5 µg/mL cytochalasin B (Sigma-Aldrich) and 0.1 µg/mL colcemid (Wako Pure Chemical Industries, Ltd, Osaka, Japan). 20,24 Briefly, the zona pellucida (ZP) around the first polar body of each 0 h-oocyte was cut using a glass knife in M2 medium supplemented with 7.5 µg/mL cytochalasin B (Sigma-Aldrich) and 0.1 µg/mL colcemid (Wako Pure Chemical Industries, Ltd, Osaka, Japan).…”

“…OST was performed as previously described with a slight modification. 20,24 Briefly, the zona pellucida (ZP) around the first polar body of each 0 h-oocyte was cut using a glass knife in M2 medium supplemented with 7.5 µg/mL cytochalasin B (Sigma-Aldrich) and 0.1 µg/mL colcemid (Wako Pure Chemical Industries, Ltd, Osaka, Japan). Following the removal of the polar body, the spindle, including a small amount of cytoplasm, from 12 h-and 24 h-oocytes was fused with enucleated 0 h-oocytes using inactivated Sendai virus (hemagglutinating virus of Japan; Ishihara Sangyo Kaishya, Ltd).…”