12 MORE JAPANESE COWS IMPREGNATED WITH CLONE EMBRYOS

January 21, 1998

TOKYO (YOMIURI) -- Researchers at the National Institute of Animal Industry, which is affiliated with the Ministry of Agriculture, Forestry and Fisheries, announced Tuesday that they had succeeded in impregnateing 12 cows with embryos cloned using somatic, or nonreproductive, cells.

The embryos were produced with the same technology used in Britain to create the sheep named Dolly, which was the first mammal to be cloned using cells from an adult.

Of the 12 cows, 10 are between 40 and days pregnant, while the other two miscarried. If successful, a cloned calf will be born in early August, the researchers said.

The Ibaragi Prefecture-based institute impregnated the cows in cooperation with a Kagoshima prefectural institute for the improvement of beef cattle.

Researchers of the two institutes took several hundred somatic cells from a calf fetus and two bulls and cultivated them. The nuclei of the cultivated cells were removed and placed in unfertilized egg cells, resulting in about 90 embryos.

The embryos were then implanted into the wombs of 42 cows -- one or two embryos in each womb -- from October to December last year.

Twelve cows subsequently became pregnant, and two of them later miscarried, as the chances of miscarriage are high for embryos grown from the nuclei of somatic cells.

The most risky period for the embryo would be around the 70th to 90th day of gestation, after which the chance of a successful birth would rise to 50 percent, a researcher at the national institute said.

If the procedure results in birth of live calves, the institute may one day be able to mass produce superior cattle that are genetically identical, a senior researcher of the institute said.

Cow-cloning experiments using somatic cells are under way in the United States and Europe. Some cows have reportedly become pregnant through the technqiue, but no births have yet been reported.

An animal industry institute in Oita Prefecture, meanwhile, also said Tuesday that it had four cows successfully impregnated with embryos cloned from somatic cells. The institute said they were now up to two months pregnant. It began cow- cloning experiments last summer, using the technique used to clone Dolly.