ABSTRACT
@#Finding stable expression sites on the chromosomes of Chinese hamster ovary (CHO) cells is an effective method to solve the problem of unstable expression of CHO cells in long-term culture. Our group used lentiviral transfection to integrate the tracer gene (Zsgreen1) into the chromosome of CHO cells and found multiple potential stable expression sites. This study verified the ability of one of the sites located in the 148052-148157 bp region on chromosome NW_003614241.1 to stably express exogenous proteins.The expression of Zsgreen1 gene was first observed, and CRISPR/Cas9 technology was then used to integrate the enhanced green fluorescent protein (EGFP) gene into this site. Three strains of EGFP gene integrated cells were obtained. After 60 generations of suspension culture, the fluorescence intensity of the cells had no significant changes, which proved that this site can stably express the EGFP gene. The same method was used to construct recombinant CHO cell lines expressing the human serum albumin (HSA) gene, and was verified by Western blot that this site could express and secrete HSA. It shows that the above-mentioned sites can be integrated and can stably express exogenous proteins.
ABSTRACT
A double antibody sandwich ELISA for quantitative analysis of recombinant fusion protein IL-2-HSA was constructed using a polyclonal antibody to human IL-2 for capture and a monoclonal antibody to HSA with HRP-labeled conjugate for detection.The optimal concentration of the first coating antibody and detection antibody were 2 μg/mL and 0.5 μg/mL,respectively.Regression equation of the linear calibration curve was:y = 0.442 9 x-1.143 3 with a correlation coefficient of 0.996 6,and the linear detection ranged from 39.06 ng/mL to 1 250 ng/mL.Recovery from the supernatant of fermentation broth was 98.13% to 102.94%.The specificity assay indicated that it had little cross-reactions with IL-2 and HSA.The soundness analysis suggested that fermentation broth,mouse serum and dilution had no influence on the method.The present method can be used in the studies on fermentation,purification and clinical diagnosis.
ABSTRACT
Objective: To investigate the effect of 1,3-diacylglycerol(DAG) on reducing blood lipid and obesity. Methods: Fifty SD rats were divided into five groups: triacylglycerol (TAG) low-fat diet, TAG high-fat diet, DAG high-dose , medium-dose and low-dose diet. The rats were fed for 6 w, and body weight was recorded every week. At the end of the experiment, the ratio of visceral fat to body weight was calculated, and blood lipid was analyzed. Results: The body weight of rats in TAG high-fat group was significantly higher than that in TAG low-fat group from the 2nd week (P