Understanding the behavior of transgenes introduced into oocyte or embryos is essential for evaluating the methodologies for transgenic animal production. To date, many studies have reported the production of transgenic pig embryos with, however, low efficiency in environment of blastocyst production. The aim of present study was to determine the expression and duration of transgene transferred by intracytoplasmic sperm injection-mediated gene transfer (ICSI-MGT). Embryos obtained from the ICSI-MGT procedure were analysed for the expression of GFP and then for the transmission of the transgene. Briefly, fresh spermatozoa were bound to exogenous DNA after treatment by Triton X-100 and Lipofectin. When ICSI-MGT was performed using sperm heads with tails removed, the yield of blastocyst (25.3%), treated with Lipofectin (18.8%) and Triton X-100 (19.2%) were observed. Treatments of Lipofectin or Triton X-100 did not further improve the rates of blastocysts. Moreover, the apoptosis rates of embryos were obtained from the control and LIpofectin groups (8.7%, 9.7%, respectively), but were significantly higher in the Triton X-100 group (13.0%). Our results demonstrated that ICSI-MGT caused minimal damage to oocytes that could develop to full term. Moreover, the embryos derived by ICSI-MGT have shown prolonged exogenous DNA expression during preimplantation stage in vivo. However, more efforts will be required to improve the procedures of both sperm treatments cause of high frequency of mosaicisms.

Production of transgenic animals for studying specific gene has been limited due to a low efficiency, lack of skilled researchers and the need for expensive equipment. Currently, the boar spermatozoa as a vector to deliver exogenous DNA into the oocyte were used to improve the efficiency of transfection rate. In this study, we revealed that the optimal conditions for DNA uptake in spermatozoa by liposome were to 90 min of incubation, 17'C, 10' spermatozoa, 4 ng/ml of exogenous DNA and 0.5% (v/v) liposome, without damage to fertility. In addition, the developmental rate to the blastocyst stage of embryo in control group was significantly higher than those embryos with exogenous DNA and liposome, whereas there were no significant differences in embryo development between the liposome and type of DNA. The transfection rates of embryo using treated spermatozoa with both liposome and circular DNA were higher than those using linear DNA. These findings raise the possibility thattreated spermatozoa with liposome/DNA complexes could be used in in vitro fertilization, and the exogenous DNA transferred into the oocytes. Taken together, we demonstrated that liposome a vector for the uptake of exogenous DNA in boar spermatozoa could improve the efficiency of sperm-mediated gene transfer in creating transgenic pig and the other domestic transgenic animals.

Sperm-mediated gene transfer (SMGT) can be used to transfer exogenous DNA into the oocyte at fertilization. The main objective of this study was to assess efficiency of transferring mitochondrial DNA (mtDNA) fragment into boar spermatozoa in either presence or absence of liposome and quality of transfected spermatozoa. The mtDNA of chicken liver was isolated and purified by phenol and alkaline lysis extraction, and it was inserted to plasmid. The genome of transfected spermatozoa treated with DNase Ⅰ was purified by alkaline lysis, and then amplified by the PCR analysis. After electrophoresis, DNA quantitation of each well was calculated by comparison of the band intensity with standard. As a result, exogenous DNA was composed of mtDNA fragment (1.2 kb) and plasmid (2.7 kb). On the other hand, efficiency of transfection by liposome (9.0±0.34 ng/l) in SMGT was higher than that by DNA solution (6.9±0.53 ng/l). However, there was no significant difference. Transfering exogenous DNA into spermatozoa was completed within 90 min of incubation. In another experiment, there were significant (p<0.05) differences between transfected spermatozoa using both DNA solution and DNA/liposome complexes with untreated spermatozoa for viability (70.8±1.80 and 68.0±2.16% vs. 83.3±1.69%, respectively) and motility (78.7±1.59 and 79.3±2.14% vs. 86.7±1.59%, respectively). This study indicates that exogenous mtDNA can be efficiently transferred into boar spermatozoa regardless of the presence of liposome, and transfected spermatozoa can also use insemination and in vitro fertilization to generate transgenic pig.