Bio #2: Dolly the Sheep

Welcome to the second cache in a series of student-driven biographies about a scientist or topic instrumental to understanding DNA, Heredity, and Genetics. The second belongs to the fascinating case of the cloned sheep Dolly.

Dolly the Sheep (born July 5, 1996 and died February 14, 2003) was a female domestic sheep, and the first mammal to be successfully cloned from an adult somatic cell (non-reproductive and non-stem cell). She was cloned by a team led by Sir Ian Wilmut at the Roslin Institute (part of the University of Edinburgh in Scotland). One of the members had tried over 400 times to clone a sheep, and was unsuccessful until Dolly. f = 0 With 3 mothers (one who provided the egg, one who provided the cells, and the last who carried the cloned embryo to term), she was cloned using a lab procedure called somatic cell nuclear transfer. The process is this: the cell nucleus from an adult cell is transferred into an unfertilized oocyte (meaning developing egg cell), missing its own cell nucleus. Then, the hybrid cell is stimulated with an electric shock, causing the genetically engineered cell to form into a blastocyst (essentially a mammal embryo in an early stage of development), which is implanted in a surrogate mother.

The success of with Dolly proved that a healthy clone can be created from a cell taken from a specific part of the body (in Dolly’s case, a mammary gland). To be more specific, it proved that genes in the nucleus of a mature differentiated cell still have the capability of reverting to an embryonic totipotent state (able to change into any other cell), creating a cell capable of developing into any part of an animal.

Just days before the scientists would make their public announcement of Dolly in February 1996, the news was leaked, and became known worldwide. Dolly’s cloning received a huge amount of media attention, including a special report in Time magazine. Dolly was a significant shock to the scientific community, as many doubted this could ever be done. Yes, a frog had been cloned in the 1960’s, but mammals were seen as too complex.

This scientific breakthrough was extremely controversial. Human cloning no longer seemed far away, and people were scared of the ramifications. Many have criticized cloning Dolly as “playing god.” These concerns became more prominent in the public zeitgeist. Nobody was capable of seeing a future where cloned will help develop drugs and other therapies that cure/treat deadly human diseases. Then president Bill Clinton banned federal funding on the cloning of humans. This also meant research on embryonic stem cells for medical purposes was affected. h = 9 Later, then president George W. Bush restricted federal funding of stem cell research. This was undone later by Barack Obama when he was president.

Dolly lived her entire life at the Roslin Institute in Edinburgh, where she bred with a Welsh Mountain ram, producing 6 lambs in total. On February 14th, 2003, Dolly was euthanized due to a progressive lung disease and severe arthritis, at 6.5 years old. The average life expectancy of a Finn Dorset (her species) is 11 to 12 years. This lung disease turned out to be a form of lung cancer called ovine pulmonary adenocarcinoma, a contagious disease caused by a retrovirus (which is an RNA virus that inserts a DNA copy of their genome into their host cell in order to replicate). Some people in the press speculated that one of her reasons for an early death was that she had a genetic age of 6 years, which was the same age of the sheep she was cloned from. Her telomeres (nucleotide sequences capped on the ends of chromosomes that protect it from deterioration) were short, which is one of the fuels for this argument. The Roslin Institute stated that intensive healths screening beheld no abnormalities in Dolly that could have been a result of advanced aging.

Dolly, a clear watershed event, left a massive legacy. Successful mammal clones followed. Two examples include Injaz, a cloned female dromedary camel, and the first cloned cat CC (which stands for CopyCat). Eventually, cloning stem cells in humans became possible. This method was improved when Japanese scientist Shinya Yamanaka figured out a way to convert ordinary human cells into stem cells, which was extremely more efficient than the Dolly method. It is still a fledgeling technology that could surely help in medicine in the future.

A = Dolly’s birthday is on July __th.

B =

C =

D = One of the members of the team had attempted over _00 sheep clonings until Dolly. (subtract 4)

E = (Genetic age people suspected Dolly was born with) - 1

F =

G = (Number of lambs Dolly birthed) + 2

H =

J =

K = Dolly had _ mothers (add two)

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