Use of Natural and Artificial Chromosome Vectors for Animal Transgenesis

The ability to use hCFs as vectors for introducing large stretches of human DNA into mice was first demonstrated in 1997 (1 ). Transferred hCFs were stably maintained as an extra chromosome in the somatic cells of mice, and the human genes included in them were expressed under proper tissue-specific regulation. In some cases they could be transmitted through the germline, resulting in the establishment of novel mouse strains (trans -chromosomic [Tc] mice) containing a heritable hCF (1 ,2 ). Thus, such an approach using chromosome vectors for animal transgenesis has been thought to be useful for overcoming size constraints of cloned transgenes in conventional techniques and facilitate functional studies of human genome in the postsequencing era.