Cincinnati--In the March 1 issue of Nature Medicine,
Randall R. Sakai, PhD, associate professor, psychiatry, and associates
at University of Cincinnati (UC) College of Medicine, report details of
the first documented research to prove that cloned animals suffer from
obesity. After the news that Dolly the sheep has arthritis and that
cloned mice may have a reduced life-span, Nature Medicine reports on a further abnormality produced by cloning: cloned mice are also prone to adult-onset obesity.
Sakai and colleagues at the UC College of Medicine Obesity Research
Center studied mice created by the technique of somatic cell transfer
to produce cloned mice -- that is, the nucleus of an adult cell was
placed into a donor egg that had the original nucleus removed. The mice
studied at UC were cloned at the University of Hawaii, Institute for
Biogenesis Research, John A. Burns School of Medicine, by the same
internationally known reproductive biology research team led by Ryuzo
Yanagimachi, PhD, that cloned the first mouse. The cloned mice became
heavier than controls after 10 weeks of age. The scientists measured
various parameters of obesity and found that the clones were not simply
larger than controls, but also displayed the characteristics of obesity
-- increased body fat, increased levels of leptin (a hormone produced
by fat cells), and raised levels of insulin in the blood. Importantly,
the offspring of these mice were not obese, meaning that the
abnormality was not passed on through the germline.
who contributed to Sakai's research included David A. D'Alessio, MD,
associate professor, internal medicine/endocrinology; Randy J. Seeley,
PhD, associate professor, psychiatry; Stephen C. Woods, PhD, professor,
psychiatry; and Kellie L.K. Tamashiro, Jennifer Lachey, and Matthew
Wortman, students in the Graduate Program in Neuroscience.
Wilmut, PhD, a key member of the team that generated the first clone,
Dolly the sheep, writes an accompanying News & Views article in the
March 1 Nature Medicine,
discussing the work. He asks whether any cloned animals are normal, and
writes that detailed observations of clones "...are important before
large-scale use of the technology in medicine..." can take place.