Scientists in Japan have found that mice cloned from somatic cells have a significantly shorter lifespan than mice conceived through natural mating (see online publication). Previous studies had shown that cloned animals tend to be obese and may have higher rates of immune dysfunction, but this is the first to link cloning with premature death.
Atsuo Ogura and colleagues at the National Institute of Infectious Diseases in Tokyo examined 12 mice cloned from immature cells in the testis. The cloned mice started to die after 311 days, with 10 of the 12 dying before 800 days. Only 1 of 7 experimental control mice died before 800 days. An examination of six of the clones revealed severe pneumonia and liver failure, which was not observed in the control mice. As antibody production in the cloned mice was significantly reduced, the authors suggest that the immune systems of the mice may be incompetent to fight off infection.
The authors used a clever control to rule out the process of replacing the cell nucleus itself as the cause of the premature death. By transferring a sperm nucleus into a recipient egg using the same technique that was used to insert the nucleus from immature testis cells in clones, the researchers effectively mimicked the cloning technique while simultaneously fertilizing the egg. Only 2 of 6 of these mice died before 800 days.
The authors caution that clone longevity may depend on many factors, including genetic background and the type of cell from which the nucleus is taken--the so-called donor cell.
Dr Atsuo Ogura
National Institute of Infectious Diseases
Tel: +81 3 5285 1111
Additional contacts for comment on paper:
Dr Davor Solter
Max-Planck Institute fur Immunbiologie
Tel: +49 761 5108 566
Drs Teruhiko Wakayama and Tony Perry
Advanced Cell Technology
Worcester, MA, USA
Tel: +1 508 756 1212
Tel: +1 617 470 7441
(C) Nature Genetics press release.
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