The present study compared the developmental potential, telomerase activity and transcript levels of X-linked genes (ANT3, HPRT, MeCP2, RPS4X, XIAP, XIST and ZFX) in the bovine somatic cell nuclear transfer (SCNT) embryos derived from different age and cell cycle of female donor nucleus. In experiment 1, the fusion rate, cleavage rate to 2-cell stage, developmental rate to blastocyst stage, and the mean number of total and ICM cells was slightly increased in embryos cloned with fetal fibroblasts compared to those with adult fibroblasts, but there was no significantly (p<0.05) differences. Telomerase activity was also similar in blastocysts cloned with fetal and adult fibroblasts. Up-regulated RPS4X and down-regulated MeCP2, XIAP, and XIST transcript level were observed in blastocysts cloned with adult fibroblasts, compared to those with fetal fibroblasts. In experiment 2, the fusion rate, cleavage rate to 2-cell stage, developmental rate to blastocyst stage, and the mean number of total and ICM cells was significantly (p<0.05) increased in embryos cloned with fetal fibroblasts at early G1 phase of the cell cycle, compared to those of fetal fibroblasts at late G1 phase. DNMT1 transcript was observed to significantly (p<0.05) increased in the fetal fibroblasts at 3 hrs after trypsin treatment of confluent culture. Further, level of telomerase activity and transcribed X-linked genes was also significantly (p<0.05) higher in the early G1 SCNT blastocysts than those of late G1. The results imply that fetal fibroblasts at early G1 phase induces the enhanced developmental potential and up-regulated telomerase activity and X-linked gene, but aberrant transcript pattern of X-linked genes may be displayed in the SCNT embryos.

ABSTRACT   INTRODUCTION   MATERIALS AND METHODS    Media and Chemicals    Preparation of Donor Cells    Nuclear Transfer and Oocyte Activation    In Vitro Culture of Embryos    Absolutely Quantitative Analysis of Transcripts by Real Time RT-PCR    Relative-Quantitative Telomerase Repeat Amplification Protocol (RQ-TRAP)    Experimental Design    Statistical Analysis   RESULTS    Developmental Potential of SCNT Embryos    Relative Telomerase Activity (RTA) of SCNT Embryos    Transcript Levels of DNMT1 in the Fibroblasts    Transcript Levels of X-linked Genes of SCNT Embryos   DISCUSSION   ACKNOWLEDGEMENTS   REFERENCES

• Byeong-Gyun Jeon(OBS/Theriogenology and Biotechnology, College of Veterinary Medicine, Gyeongsang National University, Institute of Animal Medicine, Gyeongsang National University)
• Gyu-Jin Rho(OBS/Theriogenology and Biotechnology, College of Veterinary Medicine, Gyeongsang National University, Research Institute of Life Science, Gyeongsang National University) Corresponding author