World's Most Famous Sheep

Dolly The Sheep

           Dolly was a female domestic Finnish Dorset and the first mammal to be cloned from an adult somatic (non-reproductive) cell through the process of nuclear transfer. Although Dolly was the world's most famous clone, many other animals had been cloned before her. She lived for 6 years, while the normal lifespan of a sheep is 11-12 years. 

Dolly and her firstborn, Bonnie

Timeline of Dolly

5 July 1996: Dolly was born to three mothers in Roslin Institute

22 February 1997: News of Dolly the Sheep's existence was made known to the public

April 1998: She gave birth to her first lamb, Bonnie. The next year, she gave birth to Sally and Rosie, both twins. And the year after, she gave birth to triplets Lucy, Darcy and Cotton.

Autumn 2001: Dolly was confirmed to suffer from arthritis.

14 February 2003: Dolly was diagnosed with progressive lung disease (sheep pulmonary  adenomatosis, a virus-induced lung tumour which sheep kept indoors are prone to have) and severe arthritis and was euthanised.

How Dolly was born

         Nuclear transfer

        Dolly was cloned from an adult cell, rather than an embryo. Cloning from an adult cell is more complex than the other processes. Dolly was the only lamb born out of the 277 attempts. 

The steps taken for the cloning of Dolly the sheep:

1. Cell is taken from the udder of a Finn-Dorset ewe, placed in a nutritional solution and isolated. The nucleus of this cell containing all the genetic material of the Finnish Dorset ewe is removed from the cell with a very small needle and a suction device.
2. An unfertilised egg cell is taken from a Scottish Blackface ewe. The nucleus of the egg cell is taken out using a very small needle and a suction device. 
3. The nucleus of the cell from the Finn-Dorset ewe is inserted in the nucleus-free egg cell.
4. The cells are given an electric shock and the egg cell starts to divide.
5. The egg is then implanted into a surrogate mother, also a Blackface ewe where the egg cell continues to develop into an embryo.
6. Dolly is born a few months later as a Finn-Dorset ewe, as her DNA was originally taken from a Finn-Dorset ewe.

Cloning Process

Why Dolly was cloned and how is it important?

        Dolly was cloned for the research of producing medicines in milk of farm animals at the Roslin Institute. The researchers are able to transfer human genes that produce useful proteins into the farm animals, such as sheep and cows so that they can produce milk with properties or factors to treat illnesses. 

        The cloning of Dolly has also led to the cloning of other larger mammals like horses and bulls and the development of cloning. Cloning if successful might be able help preserve endangered species and might even be able to bring extinct animals back to life! 

  References:

http://www.roslin.ed.ac.uk/public-interest/dolly-the-sheep/a-life-of-dolly/

http://en.wikipedia.org/wiki/Dolly_(sheep)

http://www.animalresearch.info/en/medical-advances/151/cloning-dolly-the-sheep/

http://www.iptv.org/exploremore/ge/what/clone.cfm

  Images:

http://bootstrike.com/Genetics/Cloning/dolly_the_sheep.php

http://www.roslin.ed.ac.uk/public-interest/dolly-the-sheep/a-life-of-dolly/