> Good-bye to Dolly the cloned Sheep
to Dolly the Cloned Sheep
Dolly's life was ended at the age of 6 (about half the
life expectancy of her breed) when a veterinarian confirmed
she had a progressive lung disease. Dolly was born in
Edinburgh Scotland on July 5th, 1996. As the first mammal
cloned by nuclear transfer Dolly instantly created a
heated debate on the need and the ethics of cloning
mammals and specifically, humans.
Animals with human genes could be used to produce hormones
or other biological products to treat human diseases.
Production methods for these protien based treatments
(such as G-CSF) are very expensive and drive up the
cost of healthcare. The only thing I can't figure out
is how they would get the protein to be expressed specifically
in the milk. They could also be given human genetic
diseases and used to test new treatments. This one is
obviously more for monkeys than for sheep... Genetically
altered animals might also produce organs that could
be transplanted into humans with less chance of rejection
than now exists. There is an active area to do this
work with primates and pigs which could be used to grown
relatively antigen free organs for transplant.
did they come up with the name?
Dolly was cloned from the udder cell of a 6-year-old
adult sheep. As you may have guessed, Dolly was named
after Dolly Parton, the curvaceous country-and-Western
Dolly did produce offspring, so if there was a genetic
component to her early death the progeny will be studied
to see if the detrimental effects are passed on. She
first gave birth to Bonnie in April 1998 and then to
three more lambs (which they didn't name) in 1999. In
January of 2002 her condition caused concern when she
was diagnosed with a form of arthritis.
Telomeres of Dolly were shorter
Dolly yielded new information about the cloning process
and how it can affect the clone and could add data to
the idea that telomere length is connected to growing
older. The researchers reported that Dolly's telomeres
were 20 percent shorter than those of sheep who are
not clones. The cells were taken from a six year old
sheep and Dolly lived six years. 6+6=12 (the normal
life span of a sheep). Is this a coincidence? Probably
to early to tell at this point but the health problems
Dolly had at this young age (arthritis and progressive
lung disease) would be extremely rare in a middle-aged
sheep. Dolly's offspring have been reported to have
normal length telomeres.
Timeline of Cloning...
- The first clone to be created is from a tadpole.
Robert Briggs and Thomas King used cells from a tadpole
embryo to create identical tadpoles.
- Transgenic mice are produced by Rudolf Jaenisch
of the Salk Institute. The process involves the injection
of human DNA into newly fertilized mouse eggs to produce
mice that carry human genes. The offspring of the mice
also contain these human genes. Different human diseases
can be studied by creating mice with the appropriate
- The world's first test-tube baby is conceived through
in-vitro fertilization. Using the husband’s sperm, British
doctors fertilize an egg in a petri dish and then implant
the embryo in the uterus of the healthy woman (so she
will be 25 years old this year...)
- Sheep and cows are cloned from embryonic cells.
- Dolly the sheep, the world’s first mammal cloned from
a cell of an adult animal, was born in 1996, but her
existence isn’t revealed to the world until February
24, 1997. Polly, the first sheep to contain a human
gene was born during the same year.
- An explosion in cloning based research occured when
scientists at the University of Hawaii cloned more than
50 mice, several independent teams produced cloned cows.
Some of these techniques reached the level or 80% efficiency.
The original efficiency of Dolly's cloning batch was
1 in 300.
- Oregon researchers reveal the existence of Tetra the
cloned monkey. The company that produced Dolly announced
a litter of five cloned pigs. The aim of this research
effort is to produce pigs that can serve as a source
of organ transplants for humans.
- U.S. fertility specialist Panayiotis Zavos and a team
of international scientists announced that couples had
volunteered for an experiment to create cloned children.
The team said it was poised to help infertile couples
bear clones as early as 2003.
- Texas A&M researchers announced that they had cloned
a domestic cat. The calico-and-white female was dubbed
"cc," for "CopyCat". The advance marks another step
toward the routine cloning of household pets. Researchers
call the company founded around the technology Genetic
Savings and Clone. And I always thought they would call
the company RePet like in that Arnold Schwarzenegger
movie (The 6th Day).