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8 calves cloned from 1 adult cow



Japan researchers report 8 calves cloned from 1 adult cow
December 9, 1998
Copyright  1998 The Associated Press

WASHINGTON -- Japanese researchers reported they cloned eight genetically
identical calves from cells removed from just one adult cow.

In a study to be published this week in the journal Science, researchers
from three Japanese institutions report that the calves were cloned with
techniques similar to those used to clone the famed Scottish sheep known as
Dolly.

The Japanese said they transferred the nuclei from cells removed from a
single adult animal into cow eggs from which the nuclei had been removed.
The eggs and the transferred cell nuclei fused and grew into blastocysts,
an early embryonic stage that resembles a ball of cells.

Ten blastocysts were placed into five unrelated cows, all of which became
pregnant. Eight calves were born from the 10 blastocysts, but four of the
eight animals died shortly after birth from what the researchers called
"environmental factors."

Each of the surviving calves is a genetic duplicate of the cow from which
the cells were removed, the researchers.  Cloning cows in this manner, the
scientists said, gives an important economic benefit because it could, in
effect, duplicate cows that are "proven to be ideal milk and meat
producers."

Japanese researchers reported last month that they had cloned at least 15
calves using the Dolly technique. Japan imports much of its beef and
agricultural researchers have been aggressively studying cloning techniques
as a way of improving the meat and milk production.

Dolly was the first mammal in history to be cloned from an adult cell.
Researchers announced last year that the Finn Dorset sheep was cloned from
using the nucleus taken from a cell that had been removed from the udder of
an adult sheep.

American researchers have since cloned calves using cells taken from unborn
cows. Laboratory mice also have been cloned using the Dolly technique.  In
the new Japanese work, the researchers used two different types of cells
removed from the reproductive tract of a single Japanese beef cow. Both
types of cells carried the same genetic pattern as the donor adult cow, and
all of the cloned calves retained this same pattern, proving that they were
true clones, the researchers said.

However, the Japanese researchers said they have achieved a higher degree
of efficiency than earlier Scottish and American's creators had hundreds of
failures and some American researchers reported a success rate of only
about 12 percent.

By PAUL RECER, AP Science Writer

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