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5-Animals: First clone from male cells



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TITLE:  First clone from male cells
SOURCE: Wired Magazine, by Kristen Philipkoski
DATE:   June 7, 1999

----------------- archive: http://www.gene.ch/ ------------------


First Clone from Male Cells

Move over, Dolly. Researchers have broken another barrier in
genetic research by successfully engineering the first clone
using cells from a male mammal. Teruhiko Wakayama and Ryuzo
Yanagimachi, who began cloning mice a year ago at the University
of Hawaii at Manoa, used somatic (nonreproductive) cells from the
tails of mice, showing that male as well as female clones could
be produced from a variety of cells. Researchers say the cloning
could give hope to endangered species since fertility and sex are
not factors. Previous cloning research has focused on cells
related to female reproduction. "Use of the tail cells indicates
that it is possible to clone either sex, and probably from almost
any kind of somatic cell, as long as one figures out a way to
cause the cell to regress to a primitive state and capitulate
gene effects," said Robert Foote, professor of animal physiology
at Cornell University.

Other than the nature of the cells, the technique used was
similar to the one that produced Dolly the sheep. Like Dolly,
previous mice clones produced at the University of Hawaii have
been female. Male mammals have been cloned -- bull clones were
developed in Japan -- but they were also derived from female
reproductive cells. Since mice are frequently used as models for
testing treatments of human disease, this type of cloning could
make it possible to produce certain gene mutations in mice to be
used in research for illnesses such as cancer or Alzheimer's
disease.

To create the male mouse, the scientists extracted a donor-cell
nucleus from a male mouse tail and injected it into the egg of a
separate female. The egg is first enucleated (all genetic
information is removed). The researchers activate a cell-division
process, and the developing embryos are then transplanted into a
foster mother. The researchers chose the tail because it is dense
with cells. The tail also heals quickly, usually without
infection, and is easy to obtain. Of 274 transplanted embryos,
only three of the males reached full term. Two of those died
within an hour after birth due to respiratory failure. Since
there was such a small number of surviving embryos, the
researchers could not conclude whether the deaths were due to the
cloning process or other reasons.

The research holds further significance since the cloned male
developed normally and mated successfully, producing two healthy
litters, Foote said. "Not only could you clone the first
generation, [but] they showed that they were capable of
reproduction, producing progeny that were the same as the
original clones," Foote said. "Carrying through several
generations has not been done [in other animals] because of the
time span it takes to do that." So far, the cloned mouse has
produced three generations. "Once you've done that three times,
it's pretty likely you'll do it a fourth and fifth, too," Foote
said. "It's very exciting, but there's so much to be learned that
it makes one realize that we're still in a state of infancy in
relation to what's out there."




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