MANNOSE OR XYLOSE BASED POSITIVE SELECTION

摘要

The present invention provides a method for identifying or selecting from a population of eukaryotic cells cultivated on or in a medium containing at least one compound, cells which have a metabolic advantage as a result of having being transformed, wherein: (i) the cells are transformed with a nucleotide sequence or a co-introduced nucleotide sequence one of which comprises a region which: (a) encodes a protein which is involved in the metabolism of the compound, and/or (b) regulates the activity of the protein; and (ii) the compound is mannose or xylose or a derivative or a precursor of these, or a substrate of the protein, or is capable of being metabolized by the transformed cells into such a substrate, with the proviso that the compound is not mannos when the proteine is mannose 6 phosphate isomerase. The invention also includes a method according to the preceding paragraph wherein the compounds are are not so limited with the proviso that an agent which reduces the toxicity to the cells of the compound is added to the medium. It is preferred that where a toxicity-reducing agent has been added to the culture medium, the compound is mannose and the nucleotide or co-introduced nucleotide sequence encodes mannose-6-phosphate isomerase.