UNTIL now, all the animals cloned from adult cells and described in the
scientific literature have been females. That鈥檚 why Fibrio, a mouse created from
a cell from the tail of an adult male mouse, is cloning鈥檚 latest celebrity.
Fibrio, born last October, is unveiled to the world in this month鈥檚 issue of
Nature Genetics (vol 22, p 127). Teruhiko Wakayama and Ryuzo
Yanagimachi at the University of Hawaii in Honolulu, who cloned female mice last year
(鈥淭he year in news鈥�, 19 December, 1998, p 28),
took cells called fibroblasts from the tips of the tails of 10-week-old golden-brown male mice.
They injected nuclei from these cells into eggs which had been stripped of their
own chromosomes. The eggs came from females with black coats.
A third of the 700 embryos survived to be implanted, but most then failed to
establish pregnancies. Of the three pups eventually delivered by caesarean
section, two stopped breathing immediately. The lone survivor had a golden-brown
coat just like his 鈥減arent鈥�.
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Although Fibrio is the first male cloned from an adult to be described in a
scientific paper, he may not be the first one created. At a conferance in Hawaii
in February, two Japanese groups claimed to have cloned bulls, and one team
leader, Chikara Kubota of the Cattle Breeding and Development Laboratory in
Kagoshima, told 快猫短视频 that four clones made from skin cells of
a single bull were born last August.
Experts say the main reason males haven鈥檛 been cloned before is that many of
the companies backing the work are interested in cloning female animals that
could be genetically engineered to produce useful proteins in their milk.
鈥淭here鈥檚 no reason to believe that male cloning is harder,鈥� says Eric
Overstr枚m of Tufts University in North Grafton, Massachusetts, who helped a
company called Genzyme Transgenics clone female goats engineered to make an
anticoagulant
(This Week, 1 May, p 5).