PARENT SESSION
PLATFORM SESSION 18. REPRODUCTIVE TECHNOLOGIES

Tuesday, August 3, 2004
4:30 PM–6:30 PM
Buchanan A204
Chair: Esmail Behboodi Co-Chair: Ali Honarmooz

(574) ANALYSIS OF TELOMERE LENGTH AND TELOMERASE ACTIVITY IN CLONED PIGS.

Jeon, Hyun Yong ¹, Hyun, Sang Hwan ¹, Lee, Gab Sang ¹, Kim, Hye Soo ¹, Kim, Sue ¹, Jeung, Yeon Woo ¹, Kang, Sung Keun ^{1, 2}, Lee, Byeong Chun ^{1, 2}, Han, Jae Yong ³, Ahn, Curie ^{3, 4}, Hwang, Woo Suk ^{1, 2, 3}, ¹ College of Veterinary Medicine, Seoul, Korea² The Xenotransplantation Research Center, Seoul, Korea³ School of Agricultural Biotechnology, Seoul, Korea⁴ College of Medicine, Seoul, Korea

ABSTRACT- Production of cloned and transgenic pigs by somatic cell nuclear transfer (SCNT) has tremendous value for developing critical biotechnology such as xenotransplantation. However, the viability of porcine SCNT embryos and piglets is extremely low. Inefficiency in production of cloned piglets is likely due to epigenetic reprogramming errors after somatic cell nuclear transfer (SCNT). In this study, to investigate whether nuclear reprogramming is complete in cloned or transgenic cloned piglets (reconstructed with fetal fibroblasts), we measured telomere length and telomerase activity. Mean telomere length was decreased in normal pigs with biological aging, but was elongated in cloned (mean length = 25.2 kb) or transgenic cloned piglets (mean length = 24.8 kb) compared to nuclear donor cells (mean length = 22.8 kb) or age-matched normal piglets (mean length = 21.8 kb). Significant telomerase activity was observed in nuclear donor cells, normal adult and new-born pigs compared to heat-inactivated HEK-293 cell extract. A similar pattern of telomerase activity was observed in bovine tissues; however, telomerase activity in bovine tissues was relatively lower than in porcine tissues, suggesting that porcine ear cells have higher endogenous telomerase activity compared to bovine ear cells and other somatic cells reported. No differences in telomerase activity were observed between (transgenic) cloned piglets and nuclear donor cells or age-matched normal piglets. However, increased telomerase activity was observed in porcine SCNT blastocysts compared to nuclear donor cells and in vitro fertilization-derived blastocysts, suggesting that the elongation of telomere lengths observed in (transgenic) cloned piglets could be due to the presence of higher telomerase activity in SCNT blastocysts. In addition, no increases in telomere length and telomerase activity were observed in clone cattle compared to nuclear donor cells. In conclusion, we demonstrated that elongation of telomere length in cloned piglets and higher telomerase activity in SCNT blastocysts. This study was supported by grants the Biogreen 21-1000520030100000 and the Advanced Backbone IT Technology Development (IMT2000-C1-1)

KEY WORDS: telomere length , cloned piglets , somatic cell nuclear transfer (SCNT), telomerase activity