In this post we’ll get to know Dolly the sheep, who revolutionized the science of cloning and stem cell research, a little bit better.
Cloning (making exact copies of living organisms) wasn’t a new concept before 1997. However, the news of a female sheep successfully being cloned took the world by storm on February 22, 1997. Her name was Dolly, and she was the first mammal to be cloned from an adult somatic cell. But why was Dolly’s cloning so ground-breaking if cloning itself wasn’t new, and where is Dolly now?
Introducing Dolly the Sheep
Dolly was a Finnish Dorset sheep. She was born on July 5, 1986, but it took another seven months before she was publicly announced.
Her announcement was met with much controversy in the media and scientific circles.
She was named after the American country singer Dolly Parton. A laboratory assistant reportedly suggested the name after he learned that she was cloned from a mammary cell.
Dolly was not the first animal to be successfully cloned. However, she was the first to be cloned from a somatic cell. Before Dolly, animals were cloned, with varying degrees of success, from developing embryos created by the fusion of reproductive gametes (sperm and ova).On the other hand, Dolly was cloned using nuclear transfer from somatic cells taken from a sheep’s udder.
The difference between the methods is that Dolly’s cloning started with the use of somatic cells not normally involved in sexual reproduction. This meant scientists could now create a living mammal without the fusion of male and female reproductive sexual gametes. The successful cloning of Dolly was a feat of great proportions in the scientific community back then, and remains a milestone and breakthrough in science.
How was Dolly cloned?
Interestingly, Dolly the sheep had three mothers from two different sheep breeds with no male parent.
One mother contributed the DNA (somatic cell), the second provided the egg, and the third mother was the surrogate who carried her to term.
The DNA contributor was a six-year-old Finnish Dorset, but the egg provider and surrogate mothers were Scottish Blackface sheep. However, Dolly was a copy of the Finnish Dorset sheep from which her DNA was taken.
Dolly was created using a scientific method known as nuclear transfer. The nucleus from an adult cell was taken and transferred into an unfertilized egg with its nucleus removed.
Afterward, the hybrid cell was stimulated with electric shocks and grown under laboratory conditions before implantation into the surrogate sheep.
Consequently, the surrogate gave birth to an identical twin of the DNA-contributing mother. Dolly was six years younger and had a completely different personality from her mother. The nuclear transfer technique was not immediately successful in creating Dolly, and it took the scientist behind Dolly’s creation 277 tries before they eventually succeeded. Other than breaking ground in the field of cloning research, it is likewise a great illustration of how important it is to not give up until you succeed.
Who created Dolly?
Dolly was a product of research by British scientists at the Roslin Institute in Scotland. Ian Wilmot and Keith Campbell, who were embryologists and microbiologists, respectively, led the research team. Dolly’s cloning was jointly funded by the United kingdom’s Ministry of Agriculture and now defunct PPL therapeutics.
PPL therapeutics was a biotechnology company based in Edinburgh, Scotland, and part of their involvement was to sponsor the development of animal proteins for therapeutic and nutritional use. According to Ian Wilmot, “Dolly would enable us to study genetic diseases for which there is presently no cure and track down the mechanisms involved.” True to that, Dolly’s cloning paved the way for further genetic and stem cell research breakthroughs. One such advancement is the discovery of induced pluripotent stem cells (iPSC) by Japanese scientists in 2006, which can assist both diabetes and leukemia patients – amongst many other things. In other words, the success of Dolly’s cloning has generated discoveries that can help save thousands of lives.
What happened to Dolly, and where is she now?
After dolly’s cloning, she was bred with a Welsh Mountain Ram and gave birth to six lambs. Her first lamb, Bonnie, was born when Dolly was almost two years old in April 1998. Shortly afterward, she gave birth to the twins Sally and Rosie in 1999. The following year she gave birth to the triplets Lucy, Darcy, and Cotton.
In late 2001, when Dolly was four years old, she developed arthritis which her handlers treated with anti-inflammatory drugs. Yet, by 2003, Dolly’s arthritis had worsened, and she was diagnosed with a progressive lung disease.
The combination of these chronic ailments necessitated her euthanization, and Dolly was euthanized on February 14, 2003. Veterinarians performed a post-mortem exam upon Dolly’s death and discovered that she had ovine pulmonary adenocarcinoma (Jaagsietke.) Jaagsietke is caused by a retrovirus and is a very common disease in sheep. The post-mortem result was contrary to speculation in the press that she died of rapid aging. Dolly spent most of her life indoors for security reasons and lived 6 ½ years.
She was preserved by taxidermy after death and gifted to the National Museum of Scotland by the Roslin Institute. She has been on display at the museum since 2003 and remains one of its most popular exhibits.
Even though the Roslin Institute has stopped cloning animals, to this day, their official mascot remains Dolly the sheep.
Dolly was a trailblazer in mammal cloning. Using the technique devised by Keith Campbell and Ian Wilmot, scientists have cloned pigs, horses, cattle, and deer.
In 2002, Clonaid, an American organization, claimed to have successfully cloned the first human baby named Eve. However, this report has been largely unverified by the scientific community. More than a decade later, in January 2018, the first confirmed successful cloning of a primate, a macaque monkey, was reported in China.
Because of Dolly, scientists currently see the possibility of using cloning to preserve endangered animals and even to revive extinct species. Yet, Dolly’s biggest contribution to modern science wasn’t cloning but advancements in stem cell research, which has helped us understand diseases, genetic abnormalities, and regenerative medicine.
Thank you for reading this article! If you want to learn about another impressive and hoofed animal, take a look at our article about the Alpine Goat.
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