METHOD OF MODIFYING CHROMOSOME

摘要

It is intended to provide a widely usable method of modifying chromosome without resorting to any specific enzyme or sequence and a method of identifying a gene that is essentially required in cell proliferation. First, a selection marker gene (B) allowing negative selection is integrated into the upstream or downstream of a target DNA region (X) and then the selection marker gene (B) and the target DNA region (X) are sandwiched between duplicated sequences. It is preferable that a DNA fragment having a sequence (A') (which is a sequence being substantially the same as a specific sequence (A) located in the downstream of the target DNA region) and the selection marker gene (B) as described above is constructed and then this DNA fragment is integrated into the upstream of the target DNA region (X). Next, homologous recombination and negative selection are conducted so that the target DNA region (X) can be easily removed from the chromosome. In the case where the chromosome contains no target DNA region (X) after the above-described treatment, it can be understood that the target DNA region (X) contains no gene that is essentially required in cell proliferation under the culture condition.