July 5: Dolly Sheep, the first cloned animal in the world was born

Today July 5 is the 20th anniversary of Dolly's sheep, the first mammal cloned in the world (July 5, 1996 - July 5, 2016). Dolly was created by Ian Wilmut and colleagues at the Roslin Institute (Edinburgh, Scotland), obtained from the Finnish Dorset sheep.

Dolly is the first cloned animal created from mature vegetative cells using a nuclear transfer method. The creation of Dolly has shown that a cell is taken from special body parts that can reproduce a complete body. More specifically, this indicates that somatic cells that have differentiated and matured from the animal body under certain conditions can be transformed into unspecified pluripotent forms and then can develop into parts of the animal's body. The name Dolly is derived from the fact that it was created from the breast of a female sheep, so it was named after Dolly Parton , the famous country music singer with huge breasts.

Singer Dolly Parton

Dolly is the result of a long-term research of the Roslin Institute under the auspices of the British Government. The creation of Dolly uses somatic cell nuclear transfer technology , in which the nucleus from an adult cell (taken from a lamb, the Dorset Finland - the Finnish Dorset) is transferred to an unfertilized oocyte ( ie developing egg cells - taken from a lamb like Blackface). The hybrid cells were then stimulated to be divided by electric shock and developed into a blastocyst and then transplanted into the womb of a third sheep. After being born, Dolly was exactly the same as the Finnish Dorset mother in both form and character.

In previous years, the team succeeded in cloning sheep from embryonic cells . However, that was not a breakthrough when there were a series of organisms created from embryonic tissue since 1958 with frog species Xenopus laevis. Dolly Sheep is the first cloned creature made from an adult animal cell. However, the replication process has very low performance: from 277 eggs, only 29 embryos are formed, of which only 3 are born and only Dolly survives. The creation of Dolly has been marked as an important step in the development of modern biology.

After death, Dolly's corpse was stuffed and displayed at the National Museum of Scotland

Dolly lived to the end of her life at Roslin Institute. She gave birth three times to a lamb lamb Welsh Mountain (named David) and had a total of six children: first born with a child named Bonnie in 1998, then twins in 1999 and triplets. in 2000. In the autumn of 2001, at the age of five, Dolly suffered from arthritis and became difficult to walk, but was later treated with successful anti-inflammatory drugs.

On February 14, 2003, Dolly was given a pain-free injection (a smooth death) in order to get rid of severe lung disease. Usually a sheep like Finn Dorset like Dolly has a lifespan of 12 to 15 years, but Dolly can only live up to 7 years old. A previous test showed that it had a lung cancer called Jaagsiekte , a common disease in sheep caused by Retrovirus JSRV virus . The scientists at Roslin said that they did not think there was a link between illness and Dolly's clone, and other sheep in the herd died of the same disease. And lung diseases are especially dangerous for domestic pets, just like the case Dolly was raised inside the Institute for security reasons.

However, some believe that Dolly's cause of death is that it was born with the genome of a 6-year-old sheep, equivalent to the age of the Finn Dorset sheep when used for cloning. The basis of this idea is to discover that Dolly's telomere is very short, which is considered as a result of aging .