EXPERIMENTAL BIAS IN THE EVALUATION OF THE CELLULAR TRANSIENT EXPRESSION IN DNA COTRANSFECTION EXPERIMENTS

beta-Galactosidase (beta-gal) expressing vectors are commonly used to standardize the transfection efficiency in transient expression experi ments. In the Chinese hamster ovary (CHO) cell Line, we transfected be ta-gal expressing vectors in combination with different plasmid DNAs, We reported here that the presence of specific DNAs led to statistical ly significant variations in the beta-gal expression level. Therefore, the measure of beta-gal activity is not necessarily an accurate metho d to monitor transfection efficiency, and its use to normalize the exp ression from reporter genes could be questionable.