Bovine somatotropin -bST- is a naturally-occurring protein hormone produced in the anterior pituitary gland of cattle and is a major regulator of milk production and growth in cows. BST is physiologically inactive in human, probably because the bovine somatotropin molecule differs from human somatotropin by about 30 percent of the amino acid sequences. Since the 1920s, administrating pituitary extracts to lactating cows was known to increase milk production. In 1980 scientists have found a new method to produce recombinant bST because of difficulty in harvesting the pituitaries and purifying sufficient quantity of bST from slaughtered cattle. This method using the cloned bST gene and express the gene by E.coli. The hormone so called recombinant bST -rbST-. Studies on rbST treated cows had extended significantly since it was produced by recombinant DNA technology in a large scale. Those studies indicated that both natural bST and recombinant bST are the same physiologically. Also it has been shown that milk production increases 40% and feed efficiency improves about 9.3% in rbST treated cows. These mentioned points cause an increase in diary products, which are cheaper, consequently a higher consume of diary products by people. In addition to milk production, rbST can be use as growth promoter in beef cattle or using in embryo transfer as inducer of embryos longevity. At present this hormone is not produced in our country and using the imported kind is not economical. As a result production of rbST is essential to being self-sufficient. To start the project at first we need extracted RNA from pituitary gland. Then with treatment of DNA polymerase enzyme making the complimentary strands of all RNAs. Afterward with help of an appropriate primers and PCR reaction, amplify the coding region of bST gene and construct a vector with this amplified segment. Finally transfer this vector to a suitable E.coli strain. Know E.coli can duplicate and protect the bST gene safely. This cloned gene can be use for constructing the expression vector for producing the rbST.

کلمات کلیدی