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* Address for correspondence: Alexsandra Fernandes Pereira. Laboratory of Animal Biotechnology, Federal Rural University of Semi-Arid, Av. Francisco Mota, 572, Mossoró, RN, 59625-900, Brazil. Tel: + 55 84 3317 8361. E-mail address: [email protected]
Introduction
The decrease in the biodiversity of wild mammals has been caused mainly by human activity, resulting in an increase in research aimed at the development of conservation strategies (Pereira et al., 2016). In general, several techniques to help with the conservation of wild animals are available, including the formation of biobanks (León-Quinto et al., 2009), artificial insemination (Howard et al., 2016), embryo transfer (Goeritz et al., 2012), in vitro fertilization (Herrick et al., 2010), and cloning using somatic cell nuclear transfer (SCNT, Folch et al., 2009). Because of the low availability of oocytes for SCNT, interspecific cloning using intraspecific and interspecific nuclear transfer techniques (iSCNT) has been shown to be an important tool in conservation (Wani et al., 2017).
The main argument for the application of iSCNT is the rapid decrease in the number of species. Any tool that can avoid this decrease is important. 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).
Therefore, in all applications of cloning, studies related to the improvement of iSCNT, as well as its wide use in different individuals, are important.
Overview of the iSCNT technique and its limitations
The iSCNT technique involves embryo reconstruction by fusing a nucleus of a donor cell (karyoplast) derived from a wild mammal with an enucleated oocyte (cytoplast) from a domestic mammal of a different species, family, order, or class (Do & Taylor-Robinson, 2014). The nucleus in G0/G1 is exposed to reprogramming by the oocyte, followed by the fusion and activation of the reconstructed embryo (Loi et al.