During normal early embryonic development in mammals, the global pattern of genomic DNA methylation undergoes marked changes. The level of methylation is high in male and female gametes. Thus, we cloned the cDNA of the porcine DNA methyltransferase 1 (Dnmt1) gene to promote the efficiency of the generation of porcine clones. In this study, porcine Dnmt1 cDNA was sequenced, and Dnmt1 mRNA expression was detected by reverse transcription-polymerase reaction (RT-PCR) in porcine tissues during embryonic development. The porcine Dnmt1 cDNA sequence showed more homology with that of bovine than human, mouse, and rat. The complete sequence of porcine Dnmt1 cDNA was 4,774-bp long and consisted of an open reading frame encoding a protein of 1611 amino acids. The amino acid sequence of porcine DNMT1 showed significant homology with those of bovine (91%), human (88%), rat (76%), and mouse (75%) Dnmt1. The expression of porcine Dnmt1 mRNA was detected during porcine embryogenesis. The mRNA was detected at stages of porcine preimplantation development (1-cell, 2-cell, 4-cell, 8-cell, morula, and blastocyst stages). It was also abundantly expressed in tissues (lung, ovary, kidney and somatic cells). Further investigations are necessary to understand the complex links between methyltransferase 1 and the transcriptional activity in cloned porcine tissues.

ABSTRACT   INTRODUCTION   MATERIALS AND METHODS    Cloning of Porcine Dnmt1 cDNA    5'- and 3'-RACE System    In Vivo Derived Porcine Embryos    RT-PCR of Tissues and Embryos    Real Time PCR   RESULTS    Cloning of Procine Dnmt1 cDNA    Dnmt1 mRNA Expression in Preimplantation PorcineEmbryos and Tissues   DISCUSSION   REFERENCES

• Yu-Youn Lee(Animal Biotechnology, Graduate School of Bio. & Information Technology, Institute of Genetic Engineering, Hankyong National University)
• Hye-Young Kang(Animal Biotechnology, Graduate School of Bio. & Information Technology, Institute of Genetic Engineering, Hankyong National University)
• Kwan-Sik Min(Animal Biotechnology, Graduate School of Bio. & Information Technology, Institute of Genetic Engineering, Hankyong National University) Corresponding author