Absence of nucleolus formation in raccoon dog-porcine interspecies somatic cell nuclear transfer embryos results in embryonic developmental failure

Abstract

Interspecies somatic cell nuclear transfer (iSCNT) can be a solution for preservation of endangered species that have limited oocytes. It has been reported that blastocyst production by iSCNT is successful even if the genetic distances between donors and recipients are large. In particular, domestic pig oocytes can support the development of canine to porcine iSCNT embryos. Therefore, we examined whether porcine oocytes may be suitable recipient oocytes for Korean raccoon dog iSCNT. We investigated the effects of trichostatin A (TSA) treatment on iSCNT embryo developmental patterns and nucleolus formation. Enucleated porcine oocytes were fused with raccoon dog fibroblasts by electrofusion and cleavage, and blastocyst development and nucleolus formation were evaluated. To our knowledge, this study is the first in which raccoon dog iSCNT was performed using porcine oocytes; we found that 68.5% of 158 iSCNT embryos had the ability to cleave. However, these iSCNT embryos did not develop past the 4-cell stage. Treatment with TSA did not affect iSCNT embryonic development; moreover, the nuclei failed to form nucleoli at 48 and 72 h post-activation (hpa). In contrast, pig SCNT embryos of the control group showed 18.8% and 87.9% nucleolus formation at 48 and 72 hpa, respectively. Our results demonstrated that porcine cytoplasts efficiently supported the development of raccoon dog iSCNT embryos to the 4-cell stage, the stage of porcine embryonic genome activation (EGA); however, these embryos failed to reach the blastocyst stage and showed defects in nucleolus formation.

Resurrecting biodiversity: advanced assisted reproductive technologies and biobanking

“…Many of these problems occur early on in embryonic development and result from incomplete reprogramming of the donor cell nuclei and the subsequent developmental failure of the cloned embryos (Zuo et al, 2014). Choice of oocyte donor species to ensure compatibility with the somatic cell donor is also likely to be an important factor (Jeon et al, 2016). It is particularly important to take the low success rates of reproductive cloning into consideration in the context of endangered species, where the production of viable offspring is the top priority.…”

“…Many of these problems occur early on in embryonic development and result from incomplete reprogramming of the donor cell nuclei and the subsequent developmental failure of the cloned embryos ( Zuo et al 2014 ). Choice of oocyte donor species to ensure compatibility with the somatic cell donor is also likely to be an important factor ( Jeon et al 2016 ).…”

Knockdown of YY1 Inhibits XIST Expression and Enhances Cloned Pig Embryo Development

“…The technique of cloning, also known as somatic cell nuclear transfer (SCNT), is used to propagate superior livestock [ 1 , 2 ], preserve endangered animals [ 3 , 4 , 5 , 6 ], generate cloned human embryos for isolation of therapeutic embryonic stem cells [ 7 , 8 , 9 , 10 ], and produce multi-purpose genetically engineered animals [ 11 , 12 , 13 ]. Thus, cloning is a powerful tool that has wide applications in animal production, life science, and biomedicine.…”

Effects of small‐molecule compounds on fibroblast properties in golden snub‐nosed monkey (Rhinopithecus roxellana)

“…However, it has been reported the efficiency with iSCNT is not as ideal as that with somatic cell nuclear transfer (SCNT) in such research. 17 Thus, it is necessary to understand iSCNT mechanisms through different research models further. On the other hand, even though the isolation of ESCs from iSCNT blastocysts has been successfully performed in the embryos derived from human nuclei and rabbit oocytes 18 -an example of potential applications to the wild animals' conservation.…”