Credit: MRC Clinical Sciences Centre
The use of cells from two different species allows the team to distinguish events as the human X chromosome is reprogrammed, and some genes are turned on. Left panel show cells with both a human (red) and a mouse (green) nucleus, before these nuclei fuse. At this point, one human X chromosome is active (bright red dot). Then the second human X chromosome becomes reprogrammed (middle panel, two red dots). Finally, the nuclei of the two cells fuse (right panel) to form a hybrid cell with two active X chromosomes.