PARENT SESSION
REPRODUCTIVE TECHNOLOGIES

Wednesday, August 4, 2004
10:30 AM–12:30 PM
Buchanan Courtyard

(632) EFFECT OF ACTIVATION STIMULI ON mRNA EXPRESSION IN BOVINE PREIMPLATNATION EMBRYOS DERIVED FROM SOMATIC CELL NUCLEAR TRANSFER.

Kang, Sung Keun¹, Jang, Goo¹, Jeon, Hyun Yong¹, Ko, Kyung Hee¹, Bhuiyan, M.M.U.¹, Park, Hee Jung¹, Lee, Byeong Chun¹, Hwang, Woo Suk^{1, 2}, ¹ Department of Theriogenology and Biotechnology, College of Veterinary Medicine, Seoul Natioanl University, Seoul, South Korea² School of Agricultural Biotechnology, Seoul National University, Seoul, South Korea

ABSTRACT- An activation stimulus is a key factor for reprogramming of genes in somatic cell nuclear transfer (SCNT) embryos and developmental competence of SCNT embryos. The present study evaluated the effect of two activation treatments on embryo development and mRNA expression in bovine parthenogenetic and SCNT embryos. The SCNT was performed according to the established system in our laboratory (Reprod Fertil Dev. 2003 15; 179-185) using cumulus cells as nuclear donor cells. For activation, oocytes and SCNT embryos was incubated with ionomycin for 4 minutes, followed by treatment with cycloheximide (CHX) for 5 hours or 6-dimethylaminopurine (DMAP) for 4 hours. The developmental competence was observed under a microscope and the cell number and allocation in blastocysts were determined by a differential staining. The relative abundance (ratio to GAPDH mRNA) of various gene transcripts in blastocysts was measured by semiquantitive reverse transcription-polymerase chain reaction. The Bax, E-cad, IF-tau, Hsp (heat shock protein) 70, Igf2r (insulin-like growth factor 2 receptor), DNMT (DNA methyltransferase) 1, and Mash (mammalian achaete-scute homologue) 2 gene were selected. As results, developmental competence of parthenogenetic and SCNT embryos, and the number of inner cell mass and trophoblasts were not affected by different activation treatments. Higher expression of Hsp 70 mRNA was observed in CHX-treated SCNT embryos compared to those treated with CHX. The expression of E-cad mRNA was significantly higher in DMAP-treated parthenogenetic and SCNT embryos compared to those embryos treated with CHX. Lowest expression of DNMT1 and Igf2r mRNA was observed in CHX-treated parthogenetic embryos compared to other embryos. Higher expression of Mash2 mRNA was observed in DMAP-treated parthenogenetic embryos comapred to CHX-treated parthenogenetic embryos. In parthenogenetic and SCNT embryos, no significant differences were observed in the Bax and IF-tau transcripts regardless of activation protocols. Our results demonstrated that different activation stimuli induced differential expression of genes in SCNT embryos, suggesting that this may affect development of the embryos after implantation and/or during fetal growth in vivo. This study was supported by Biogreen 21-1000520030100000.

KEY WORDS: parthenogenesis, gene expression, activation, SCNT