Lack of effects of ooplasm transfer on early development of interspecies somatic cell nuclear transfer bison embryos

Abstract

BackgroundSuccessful development of iSCNT (interspecies somatic cell nuclear transfer) embryos depends on complex interactions between ooplasmic and nuclear components, which can be compromised by genetic divergence. Transfer of ooplasm matching the genetic background of the somatic cell in iSCNT embryos is a valuable tool to study the degree of incompatibilities between nuclear and ooplasmic components. This study investigated the effects of ooplasm transfer (OT) on cattle (Bos taurus) and plains bison (Bison bison bison) embryos produced by iSCNT and supplemented with or without ooplasm from cattle or plains bison oocytes.ResultsEmbryos in all groups were analysed for developmental competence that included cleavage rates, ATP content, and expression of nuclear- and mitochondrial- encoded genes at 8–16 cell stage. Interestingly, no significant differences were observed in embryo development, ATP content, and expression of nuclear respiratory factor 2 (NRF2), mitochondrial transcription factor A (TFAM) and mitochondrial subunit 2 of cytochrome c oxidase (mt-COX2) among groups. Thus, although OT did not result in any detrimental effects on the reconstructed embryos due to invasive manipulation, significant benefits of OT were not observed up to the 8–16 cell stage.ConclusionsThis study showed that a viable technique for OT + SCNT is possible, however, further understanding of the effects of OT on blastocyst development is necessary.

Additional mitochondrial DNA influences the interactions between the nuclear and mitochondrial genomes in a bovine embryo model of nuclear transfer

“…However, when mtDNA was added to porcine oocytes with sufficient mtDNA, there were no additional benefits 11 . Whilst it has been also reported that the transfer of donor ooplasm containing mtDNA was neither detrimental or beneficial to embryos up to the 8–16 cell stage 60 , donor mtDNA can modify the germline as it is detectable in the offspring’s oocytes 22 . Nevertheless, donor mtDNA appears to decrease in foetal tissues suggesting a skewed bias towards the germline 22 .…”

Does supplementation with mitochondria improve oocyte competence? A systematic review

“…The majority of the experimental studies (14 out of 24) were conducted in animals with good quality oocytes. The effects of mitochondrial transfer were evaluated by comparing IVF/ICSI (intracytoplasmic sperm injection) vs mitochondrial supplementation in combination with ICSI (mICSI) or by comparing somatic cell nuclear transfer (SCNT) in animals of the same species (Lee et al 2017, Srirattana & St John 2018, Xu et al 2019) or involving different species (iSCNT) (Sansinena et al 2011, Hua et al 2012, Takeda et al 2012, Gonzalez-Grajales et al 2016, with or without mitochondrial transfer. Mitochondrial transfer was also compared in the context of parthenogenetic development in bovine species (Takeda et al 2005).…”

Potential role of intraspecific and interspecific cloning in the conservation of wild mammals

“…After the transfer of the nucleus into the enucleated oocyte, the cytoplast–karyoplast complex is subjected to an electric pulse that not only induces the fusion of the somatic cell nucleus with the enucleated oocyte to form a new complex, but also promotes the release of intracellular calcium that initiates cellular activation (Pereira & Freitas, 2009). In general, the successful development of a reconstructed embryo depends on the complex interactions between the cytoplast and the nuclear structure during embryonic development; failures in this interaction can cause problems during early cleavage and embryonic development (González-Grajales et al , 2016).…”

“…iSCNT preserves and even expands genetic variability when somatic cells of different individuals representative of the original biodiversity of a population are collected for its use (Loi et al , 2001). In addition, interest in cloning has increased not only for the conservation of endangered species, but also for the multiplication of reproducers with better genetic characteristics (Saini et al , 2015), basic research on cell epigenetic status (Saragusty et al , 2016), embryonic development (González-Grajales et al , 2016), and the production of induced pluripotent cells (Sukparangsi et al , 2018).…”