Abstract: The disclosure relates to genetic engineering, and more particularly to a CHO cell line, its construction and a recombinant protein expression system using the CHO cell line. Regardless of the presence screening pressure, the recombinant protein expression system constructed by the 60th passage of the recombinant APRT gene-deficient CHO cell line is much higher than the normal recombinant CHO cell in the expression retention of the target protein EGFP. In the absence of G418 screening pressure, the expression level of the recombinant vitronectin in the recombinant protein expression system constructed by the 30th passage of the recombinant APRT gene-deficient CHO cell is significantly higher than the expression level of the corresponding target protein in the normal recombinant CHO cells.

Abstract: The invention relates to genetic engineering, and more particularly to a Dnmt3b gene-deficient CHO cell line, a preparation method and an application thereof and a recombinant protein expression system using the same. The invention adopts a CRISPR/Cas9 gene editing technique to knock out the Dnmt3b gene from the CHO cells to produce the Dnmt3b gene-deficient CHO cell line, which can significantly improve the expression level and stability of the target gene in CHO cells, overcoming the defects existing in the current CHO cell expression system, such as low expression level and stability. It has been demonstrated that using the CHO line provided herein to express a recombinant adalimumab can significantly increase the expression level of the recombinant adalimumab, indicating that the CHO cell line can be widely used to enhance the expression of target proteins.

Abstract: This disclosure relates to the conversion of methane to hydrocarbon of greater molecular weight, including aromatic hydrocarbon such as xylenes, to materials and equipment useful in such conversion, and to the use of such conversion for, e.g., natural gas upgrading.