Selection of triparental somatic hybrids between mouse and Chinese hamster cell lines

Triparental crosses were carried out between Chinese hamster and mouse cell lines, by using combinations of recessive and dominant markers. Evidence is provided that triparental somatic hybrids arose at relatively high frequencies in triselective media, after fusing with polyethylene glycol mixtures of three cell types carrying the appropriate resistance markers. The Karyotypes of these hybrids were consistent with their triparental origin. Since triparental chromosome complements were observed also in some of the cells selected for two markers only, the possibility is discussed that nuclear multiplicities higher than two in fused cells may favor, rather than hinder, viable hybrid formation.