Researchers have transferred a chromosome from a rat frozen for over a year into mouse cells, resulting in living chimeric mice. The work could aid studies of extinct species and support conservation efforts.
Teruhiko Wakayama at Yamanashi University in Japan led the team that extracted a chromosome from a genetically modified rat whose blood cells had been deep-frozen for more than a year. The chromosome was injected into mouse embryos, producing animals in which some cells contain the extra rat chromosome and fluoresce green under ultraviolet light. The technique relies on nuclear transfer followed by chromosome extraction and injection into a second egg. So far it has succeeded only with rat chromosome 9, and attempts to make mice in which every cell carries the added chromosome have not yet succeeded. Wakayama’s group has obtained frozen elephant tissue from a zoo and plans to test the method on elephant cells next. The researchers are also in discussions about applying it to chromosomes from a 28,000-year-old mammoth named Yuka. The approach could allow gene activity from extinct animals to be studied in living cells, which the team says may benefit both basic research and efforts to revive species such as the Hawaiian poʻouli bird.
