X-Message-Number: 24146
From: "Basie" <>
Subject: Recloning
Date: Mon, 24 May 2004 20:29:52 -0400

'Serial cloning' works
24/05/2004 11:23  - (SA)

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San Francisco - A clone of a cloned prized bull thrives today on a Japanese
farm, living proof that "serial cloning" can successfully create life beyond
mice.

The second generation cloning that created the black bull named Kamitakafuku
took place in 2000, but wasn't announced until Sunday because researchers
wanted to ensure the bull matured and was healthy. The only other mammal
known to have been cloned from a clone are mice.

"We have proven that recloning can be done in higher species," said
University of Connecticut researcher Xiangzhong "Jerry" Yang, one of three
authors of the study. The results appeared online on Sunday in the journal
Nature Biotechnology.

The experiment has little practical effect: recloning - and even cloning -
is far too inefficient to clone even the most prized bull for profit.

Yang and his colleagues "fused" 358 eggs to yield the single bull. Attempts
to create a third clone generation failed after 248 "fused" eggs were used.

Still, cloning experts such as Jose Cibelli at Michigan State University
said Yang's experiments offered evidence that a key mechanism, called
telomeres, thought to influence the ageing process is rewound in the cloned
offspring.

Cibelli and others speculated that the difficulty Yang and his colleagues
had in recloning a single bull may magnify the genetic programming errors
that many believe explain why so many cloned animals of all types die early,
either as foetuses or newborns.

To clone, researchers replace the genetic material in an egg with the DNA
from the animal to be cloned. With a little jolt of electricity and other
laboratory manoeuvres, the egg is tricked into believing it's fertilised and
grows into an exact genetic copy of the donor.

While cloning researchers are becoming much more proficient with their
craft, many problems still persist.

It can still take hundreds of cloned eggs to yield a single offspring and
many are born obese and with other health problems.

Researchers attempting to clone clones beyond the mouse have failed until
Yang published his work.

Yang hopes his recloning work will help him uncover key genes responsible
for the reprogramming errors.

Edited by Ilse Arendse

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