[Cloning and optimizing prokaryotic induced expression conditions of prolactin in White Goose]

The mature segment gene of prolactin (PRL) in White Goose was amplified from pituitary by RT-PCR and then cloned into the pMD18-T vector. Sequencing analysis showed that the cDNA has a length of 690 bp including the termination codon and encodes a protein composed of 230 amino acids, which differs from the published PRL cDNA sequence. There is a homology of 99.57% in base and 99.56% in amino acids with that of Wanxi White Goose, respectively. A prokaryotic expression vector, pET-32a(+), was used to construct the recombinant plasmid pET-32a(+)-PRL to produce protein. Having been induced by IPTGthe host cell carrying the recombinant plasmid expressed the recombinant PRL. The optimal condition for expression is 1 mmol/L IPTG at 37. Based on this condition, the expression rose to the highest level by 4 h of induction, accounting for 28.96% of the total bacterial protein.