Cloning of Obese (ob) Gene of Swine and the Difference of ob Gene Expression at Different Ages

Genome RNA was extracted from adipose of pig (Duroc×Landrace×Taihu) and obese (ob) gene mRNA was amplified using RT-PCR. A DNA fragment about 504 bp in length was obtained and the PCR product was cloned into pGEM-T vector. The ob gene was isolated and sequenced from the positive clones screened. Sequence analysis suggested that this fragment was partial sequence of ob cDNA and coded 167 amino acid residues, which constituted the major part of leptin mature protein. The gene homology of fragment obtained in this study compared with that of reported ob cDNA sequence in adipocytes of porcine was 99.41%, and amino acid homology is 98.94%. Based on the ob gene clone, an optimal semi-quantitative RT-PCR method was successfully constructed. Using β-actin as inner control, the difference of ob gene expression at different ages of swine was researched, which was increased in suckling stages, and the level rising to a peak by 28 days of age and then declining.