[Production of porcine blastocysts expressed EGFP by handmade cloning]

Production of transgenic animals via somatic cell nuclear transfer (SCNT) has been widely used worldwide. However, the application of SCNT is impeded by overall high costs and low efficiency. Here, we reported a modification of the existing technology in order to overcome some of the disadvantages associated with SCNT. Firstly, a marker gene, enhanced green fluorescent gene (EGFP), was transfected into pig fetal fibroblast cells, and was subsequently screened by fluorescent expression to ensure donor cells expressing EGFP. Porcine embryos expressing EGFP were then produced by a method called handmade cloning (HMC), a simplified method for micromanipulation. To demonstrate the concept, we collected a total of 378 fresh swine oocytes, from which 266 with the nucleus removed, obtained a total of 127 viable recombinant oocytes after fusion with EGFP-expressing cells. In vitro incubation of the 127 recombinant oocytes for approximately 144 hours resulted in successful generation of 65 viable embryos, with an average success rate of 52.1±8.3%. Compared with the traditional SCNT, the method of HMC is not only easy to operate, but also increases the rate of recombinant embryo significantly. Furthermore, the modified method no longer relies on expensive instrument like micromanipulator, facilitating the industrialization of transgenic animal production.