(UK/JP)Cloned animals meet early deaths

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http://www.newscientist.com/news/news.jsp?id=ns99991903

 

Cloned animals meet early deaths

 

19:00 10 February 02

Philip Cohen

 

Cloned animals may indeed die young suggests the first

direct study of their lifespan, carried out by

Japanese researchers on mice.

 

Cloning involves removing the nucleus from an egg and

replacing it with the nucleus of a donor cell. Many of

these " nuclear transfer " embryos never develop or

miscarry. Even after birth some clones die. But many

cloning scientists argue that the few survivors can be

perfectly normal.

 

Atsuo Ogura of the National Institute of Infectious

Diseases in Tokyo says his team's work suggests that

some effects of cloning are not apparent in the days,

weeks or even years after birth. " It is very probable

that, at least for some populations of clones, some

unpredictable defects will appear in the long run, " he

says.

 

The debate over the health of clones and how they age

has swung one way and then the other. In November

2001, US biotech company Advanced Cell Technology

reported the cloning of two dozen apparently healthy

cloned cows. But in January, the first mammal cloned

from an adult cell, Dolly the sheep, was reported to

have prematurely developed arthritis.

 

Rudolf Jaenisch, a mouse cloner at Massachusetts

Institute of Technology in Boston says the new work

" shows that to look at animals at one point in time

and say they are healthy and normal is really wishful

thinking. "

 

Immune system defect

 

Ogura's team cloned 12 male mice and these were

compared with seven males from natural matings and six

others produced using in vitro fertilisation. The

clones appeared active and healthy, gained weight

normally and matched the control animals in 14 of 16

physiological measurements.

 

But the first cloned animal died after only 311 days

and, by day 800, 10 (83 per cent) of the animals were

dead. In contrast, only three (23 per cent) of the

controls died during the same period.

 

The dead clones showed high rates of pneumonia, liver

disease, cancer and a lower level of antibody

production, suggesting they had an immune system

defect. Ogura's team is now trying to pinpoint the

precise cause of death and repeat the experiment with

more animals.

 

ACT's Tony Perry points out that it remains unclear if

clones from other species such as cows or pigs die

early. And even if clones in general do prove to have

a shortened lifespan, he does not think that

undermines data from ACT and others that clones can be

healthy.

 

All the researchers agree that the work should be an

additional warning to would-be human cloners.

 

Journal reference: Nature Genetics (DOI:

10.1038/ng841)

 

 

 

 

 

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