Mouse cloned from frozen tissue

A research team from the Institute of Physical and Chemical Science has succeeded in cloning a mouse using tissue from one that was frozen for 16 years.

The newborn mouse is believed to be the first animal in the world to be cloned from frozen animal tissue.

The team's work could potentially lead to the cloning of extinct animals such as mammoths, but likely will also prove controversial in terms of bioethics.

The research data appeared in Tuesday's issue of the journal Proceedings of the National Academy of Sciences.

Previously, it had not been possible to clone animals from frozen tissue and all cloned animals have so far been produced from living cells.

However, the research team developed a technology to extract the nucleus of a cell by grinding it softly in a special culture. Nuclei from brain and blood cells were taken from the mouse. The nuclei were then inserted into an ovum taken from a healthy mouse. Four mice were born as a result of growing cells derived from embryonic stem cells grown from the ovum and implanting the nuclei of these cells into the eggs of a surrogate mouse.