Despite technological advances, two major problems continue to plague the field of animal cloning: few clones survive to term and those that do are grotesquely large. The root of these problems has remained a mystery until now.

But a new study led by the Whitehead Institute traces their origin to two separate sources, reporting that while poor survival rate is influenced by the genetic background of the donor cell, the gross overgrowth of clones results from the actual procedure of cloning.

The findings will add to the crucial body of knowledge needed to improve cloning efficiency and to understand why so few clones survive to term and become healthy adults.

These findings , from Rudolf Jaenischs lab at the Whitehead Institute of Biomedical Research, were reported on the web May 1, 2001 in the Proceedings of the National Academies of Science.

"These results are important because they identify two distinct problems that we researchers need to focus on as we work on solving the problems plaguing cloning technology. Now researchers can treat as two separate issues factors in the cloning procedure that cause enlarged animals and the factors in the genetic makeup of donor cells that influence clone survival," says Kevin Eggan, first author on the paper and a graduate student in the Jaenisch lab.

Cloning has captured the attention of biologists because of its potential benefitsthe creation of cells and tissues to replace diseased ones, recovery of extinct species, creation of animal models mimicking human diseases, and generation of herds of superior agricultural animals. The cloning procedure involves removing the nucleus, or the genetic command center, of an egg and replacing it with the nucleus of an adult cell. The egg resets the developmental clock of the adult cell back to its embryonic state and gives rise to a new organism that is genetically identical to the d
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Contact: Nadia Halim
halim@wi.mit.edu
617-258-9183
Whitehead Institute for Biomedical Research
9-May-2001