Date of Award

2003

Level of Access

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Animal Sciences

Advisor

Charles Wallace

Second Committee Member

James Weber

Third Committee Member

Carol Kim

Abstract

Bovine placental lactogen (bPL) is a hormone produced by the fetal portion of the placenta during gestation. Although there is little known about the structure and function of the protein, it is thought to play a role in the growth of the fetus and in mammary growth and differentiation. Attempts have been made to heighten the understanding of bPL through the use of recombinant DNA technology. Thus far, researchers have been able to produce the recombinant molecule in bacteria cells. Bacteria, however, are incapable of carrying out some of the post-translational modifications characteristic of mammalian proteins. For example, unlike native bPL, recombinant bPL is non-glycosylated. Other examples of post-translational modifications include disulfide bond formation and correct folding of the proetin. The aim of this study, therefore, was to clone the bPL cDNA into a mammalian expression vector, amplify the recombinant molecule in E. coli cells, and transfect the rbPL into mouse fibroblast cells. The idea behind this research was that the mouse cells would be able to produce the bPL complete with the post-tanslational modifications seen in the native protein. Attempts were made to transfect the pcDNA3.1-bPL into mouse L929 cells. Media was collected post-transfection and awwayed (Wallace, 1993) for the presence of pBL. An average concentration of 1 ng/mL bPL was measured. It was also noted that the transfected cells, as compared to control non-transfected cells, grew at a slower rate. Initially, it was suspected that the L929 cells were infected with mycoplasma. Transfection of a new batch of mouse cells showed improved growth rate, but did not produce a higher transfection efficiency. Studies with ovine placental lactogen have shown that the 5' flanking sequence of the PL gene is important in the production of the protein. In this study, the 5' flanking region of the bPL gene was removed during the making of the recombinant bPL molecule. It is therefore hypothesized that the 5' flanking sequence of the bPL gene is important to the production of the protein due to the low transfection efficiency observed.

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