To improve the developmental potential of bovine somatic cell nuclear transfer (SCNT) embryos, this study compared the developmental rates to blastocyst stage in the SCNT embryos using donor fibroblasts treated with 5-azacytidine (5AC) and S-adenosylhomocysteine (SAH) at different concentrations. Their reprogramming efficiency level was investigated with level of telomerase activity. Donor fibroblasts isolated from adult ear skin of a cow were exposed to 5AC and SAH at different concentrations during 2 passages. After nuclear transfer into enucleated recipient oocytes, the cleavage and developmental rates were significantly (p<0.05) decreased in the SCNT embryos using 5AC-treated fibroblasts (5AC-SCNT embryos), compared with those of non-treated control (control-SCNT embryos) and SAH-treated fibroblasts (SAH-SCNT embryos). The developmental rates to blastocyst stage tended to be slightly increased in the SAH-SCNT embryos at each of the concentrations, and especially, the developmental rates in the SCNT embryos using 1.0 mM SAH-treated fibroblasts were significantly (p<0.05) higher than that of control SCNT embryos. The mean numbers of total and ICM cell in blastocysts were also significantly (p<0.05) decreased in the 5AC-SCNT embryos, compared with those of other SCNT blastocysts. Further, the level of telomerase activity was also significantly (p< 0.05) decreased in the 5AC-SCNT embryos than those of control and SAH-SCNT embryos. Whereas, a significantly (p<0.05) up-regulated telomerase activity was observed in SAH-SCNT embryos, compare with that of control-SCNT embryos. In conclusion, SCNT embryos using hypomethylated donor cells with SAH, not 5AC, may improve the developmental potential and reprogramming efficiency.

INTRODUCTION
 MATERIALS AND METHODS
  1. Media and Chemicals
  2. Treatments of Donor Cells
  3. Preparation of Recipient Cytoplasts
  4. Nuclear Transfer and Oocyte Activation
  5. In vitro Culture of SCNT Embryos
  6. Relative-Quantitative Telomerase Repeat Amplification Protocol(RQ-TRAP)
  7. Statistical Analysis
 RESULTS
  1. Developmental Potential of SCNT Embryos
  2. Relative Telomerase Activity of SCNT Embryos
 DISCUSSION
 REFERENCES

• Byeong-Gyun Jeon(Dept. of Biology Education, College of Education, Gyeongsang National University, Jinju 660-701, Korea, Research Institute of Education, Gyeongsang National University, Jinju 660-701, Korea) Correspondence
• Gie-Joon Jeong(Dept. of Biology Education, College of Education, Gyeongsang National University, Jinju 660-701, Korea)
• Gyu-Jin Rho(OBS/Theriogenology and Biotechnology, College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Korea)