In a move that bears more than a passing similarity to Woody Allen's movie "Sleeper," where scientists try to clone a dead dictator from his nose, researchers at <<>> and <<>> have cloned a mouse from its olfactory neurons.
It's the first time that post-mitotic cells, highly specialized cells that no longer divide, have been used to produce a clone.
The study was the result of a collaboration between the labs of Dr. Richard Axel, University Professor of Biochemistry & Molecular Biophysics and Pathology in the Center for Neurobiology and Behavior, and Dr. Rudolf Jaenisch of the <<>> at MIT, who realized two different questions about development could be answered by one cloning experiment. Their results were published in the March 4 issue of Nature.
During cloning, the nucleus from an adult cell is placed into an egg cell whose nucleus has been removed. The egg is able to erase any changes to the adult cell's chromosomes, returning the chromosomes to a nascent state needed before the clone can develop.
Until now, researchers could only make clones from skin or other cells that can divide. The failures with post-mitotic cells led people to believe that nondividing cells have irreversible changes in their chromosomes that cannot be erased by the egg. Irreversible changes may be caused by additions to chromosomes that can't be removed or DNA rearrangements that remove or scramble parts of chromosomes.
The new experiments show those beliefs were mistaken. By successfully cloning mice from nondividing cells, the researchers demonstrated that any changes to chromosomes in highly specialized, post-mitotic cells are reversible or do not interfere with development of a live mouse.
The finding will now allow researchers to focus on how the egg reprograms the genetic material during cloning, Dr. Jaenisch says. Insights from those studies could be applied to the study of cancer cells, which also reprogram genetic material to turn mature cells into undifferentiated ones.