Transformation Of SCT Gene Into Lettuce Using Agrobacterium Tumefaciens

Osteoporosis (OP) is a common disease harmful for people's health. With the occurrence frequency rising up, OP is being a most severe killer for human beings.Calcitonin is a 32-peptide hormone secreted by C cells in hypothyroid. In 1985, it was allowed to cure OP by FDA. Calcitonin can depress the cell multiplication and prevent the massive osteolysis by integrating with the osteoclasts surface receptors. It has been confirmed that calcitonin has a curative effect for OP. At present, the production of calcitonin has troubles on resources, costs and safety. Plant bioreactor is a hopeful meaning to resolve these problems.In this study, transgenic lettuce was used as bioreactor to express salmon calcitonin (sCT), which has more activation. The aim of the study is to prevent or cure OP by eating lettuce expressing calcitonin. An artificial msCT gene encoding sCT was designed and synthesized according to plant code bias. To improve the absorbing efficiency, pil gene (encoding fimbriae protein) was cloned from strain C83912 and linked with 5' end of msCT to produce a fuse gene pil-sCT. For the safety of transgenic food, a plant expression vector p35S-2300-twin T-DNAs:: pil-sCT::noster was constructed and introduced into Agrobaterium timefaciens EHA105. The sCT gene was transformed into lettuce mediated by A. tumefaciens and 169 kanamycin resistant strains were isolated. PCR analysis of this generation revealed that 35 of 169 were positive, and the ratio was 20.7%. PCR analysis of 358 Tl strains from 4 strains (9, 19, 37, and 50) showed 263 positive and 95 negative, which was consistent with the Mendel Separation Law (3:1). Further researches on the measurement of msCT in transformed plants and animal tests are going on. This study explored the expression of heterogonous medical protein in plant, and built a basic technical platform for further research.