HUMAN MINICHROMOSOMES IN MOUSE EMBRYONAL STEM-CELLS

We have introduced human mini-chromosomes of 4 Mb and similar to 15 Mb in size into mouse embryonal stem cells, Although these human mini-ch romosomes are stable in hamster and chicken cells, they re-arrange or segregate aberrantly in the embryonal stem cells and are rapidly lost in the absence of selection, However, one of the mini-chromosomes re-a rranged, acquired mouse centromeric sequences and was then stably main tained for at least 60 population doublings in culture, This mini-chro mosome, which is 4 Mb in size, is a candidate for a mouse germ line ch romosome vector.