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The First
Cloned Cat
On 14th February
2002,cloning scientists in Texas publicly
announced the world's first "Copy Cat" -
a cloned kitten named Cc. Cc (nicknamed
"Copycat" or "Identicat" by
the media) was made from a cell taken from an
adult tortoiseshell female. The nucleus of this
cell was inserted into an egg in a technique
called "nuclear transfer" - the same
technique used to make Dolly the sheep. It is
believed to be the first time a domestic cat has
been cloned; attempts to clone a dog had failed.
Mark Westhusin and his colleagues from the
College of Veterinary Medicine at Texas A&M
University fused a cell from one of the adult
cat's ovaries with an egg from which the nucleus
had been removed. Genetic material from the adult
cell was transferred into the egg. This grew into
an embryo and was implanted in a surrogate mother.
Out of 188 attempts to create embryos, 87 cloned
embryos were made and transferred into 8 surrogate
mothers. Only two resulted in pregnancies and only
one pregnancy was successful.
Cc was born by Caesarean section on December
22nd 2001. She was reported to be vigorous at
birth and appeared to be completely normal.
Despite being a clone, Cc's coat has a different
pattern from that of the donor cat because the
pattern of pigmentation in multi-colored animals
is not solely caused by the genes, but also by the
way the cat develops i.e. what genes are switched
on or off in each individual skin cell (though the
cells may be identical, some have
"black" switched on while others have
"orange" switched on).
Although the reports describe Copycat as a
tortoiseshell, the photos issued to the media very
clearly show a tabby-and-white, not a
tortoiseshell (black-and-orange) which suggests
scientists may be improving the cloning process,
but they have a great deal to learn about cats in
general! The donor is a tabby-tortie-and-white
called Rainbow.
Though this seems a
great step forwards, the failure rate is still
extremely high - only 1 out of 87 attempts
resulted in a clone - and the kitten was not born
naturally. There will also be other DNA present
because only the nucleus was transferred to the
egg - other parts of the cell (the mitochondria)
will not have come from the clone donor cell but
from the egg cell.
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