Effect of Different Type of Mitochondrial DNA on Preimplantation Embryonic Development in the Mouse

Abstract

To examine the effect of mitochondrial DNA (mtDNA) on the developmental ability of mouse embryos, we investigated using the mice from standard and the mtDNA-congenic strain carrying different type of mtDNA under the same nuclear genetic background. When the 2-cell embryos (day 2 after hCG injection) derived from standard strain C57BL/6 (B6) carrying Mus musculus domesticus type mtDNA and from mtDNA-congenic strain C57BL/6.mt^SPR (B6-mt^SPR) carrying Mus spretus type mtDNA were used to compare the developmental ability in vitro, the percentage of embryos developed to blastocyst of B6-mt^SPR strain (34.7%) showed significantly lower than that of B6 strain (93.8%) at day 6 after hCG injection. The results from reciprocal cross mating between B6 and B6-mt^SPR to examine the effect of paternal mtDNA indicated that F1 embryos from B6-mt^SPR females (38.7%) also exhibited lower developmental ability to blastocysts than those from B6 females (86.7%). When B6 and B6-mt^SPR embryos were cultured in the low oxygen (5% O₂) condition, development of B6-mt^SPR embryos (96.7%) to the blastocyst stage was greatly improved to the level comparable to that of B6 embryos (97.4%). These results suggest that developmental ability of the embryos may be influenced by the type of maternally derived mtDNA through mitochondria respiratory pathway, but a possible involvement of incompativility among nuclear and mitochondrial genome and cytoplasmic factors on preimplantation development still remains to be resolved.