Interspecies Nuclear Transfer Embryos Reconstructed from Cat Somatic Cells and Bovine Ooplasm

Abstract

Abstract. This study was conducted to investigate the developmental capacity of domestic cat-bovine reconstructed embryos via interspecies somatic cell nuclear transfer (iSCNT) and to observe the mitochondrial DNA (mtDNA) content of the iSCNT embryos. The iSCNT embryos were generated using mixed-breed domestic cat fibroblasts as donor cells and enucleated bovine oocytes as the recipient cytoplasm. When the developmental capacities of iSCNT embryos and parthenogenic bovine embryos were compared, there was no difference (P>0.05) in the rates of cleavage and development to the 8-cell stage (86.6 vs. 84.0% and 32.2 vs. 36.2%, respectively). However, in contrast to development of parthenogenic embryos to the morula and blastocyst stages, no iSCNT embryos (0/202) developed beyond the 8-cell stage. For mtDNA analysis, iSCNT embryos at the 1-cell, 2-cell, 4-cell and 8-cell stages were randomly selected. Both cat and bovine mtDNA quantification analysis were performed using quantitative PCR. The levels of both cat and bovine mtDNA in cat-bovine iSCNT embryos varied at each stage of development. The cat mtDNA concentration in the iSCNT embryos was stable from the 1-cell to 8-cell stages. The bovine mtDNA in the iSCNT embryos at the 8-cell stage was significantly lower than that at the 4-cell stage (P<0.05). No difference in the proportions of cat mtDNA in the iSCNT embryos was found in any of the observed developmental stages (1-through 8-cell stages). In conclusion, bovine cytoplasm supports domestic cat nucleus development through the 8-cell stage. The mtDNA genotype of domestic catbovine iSCNT embryos illustrates persistence of heteroplasmy, and the reduction in mtDNA content might reflect a developmental block at the 8-cell stage. Key words: Bovine oocyte, Cat, Interspecies somatic cell nuclear transfer (iSCNT), Mitochondrial DNA analysis (J. Reprod. Dev. 54: [142][143][144][145][146][147] 2008) nterspecies somatic cell nuclear transfer (iSCNT) involves transfer of donor cell nuclei from one species to the enucleated oocytes of another species. The type of nuclear transfer allows for derivation of embryos that carry valuable genes in a surrogate ooplasm from another mammalian species. This technology was established for many reasons including production of embryos from species from which oocytes are difficult to obtain or where their collection is under restricted control. In regard to reproductive aims, iSCNT has been applied to conservation of wildlife animals including gaur [1], mouflon [2], banteng [3] and African wildcats [4]. In regard to therapeutic or biomedical aims, patientspecific embryonic cell lines have been established using iSCNT [5,6]. Furthermore, iSCNT provides an opportunity for molecular tracking of nucleocytoplasmic interaction and the transmission of two cytoplasmic populations. This methodology influences embryonic development and survival post-implantation and provides an enabling technology to explore fundamental aspects of developmental biology in mammals.The survival of wildcats in Thail...

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Cell cycle analysis and interspecies nuclear transfer of cat cells treated with chemical inhibitors

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Mitochondrial DNA transmission and confounding mitochondrial influences in cloned cattle and pigs

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