The Roslin Institute

Public Interest: Dolly the Sheep

The Importance of Dolly

Why was Dolly Important?

The birth of Dolly overturned the assumption among scientists that the whole process of differentiation was irreversible.

We all start life as a single cell, the fertilised egg. The cell divides and multiplies and by the time we are born, there are maybe 200 different cell types, each containing the same DNA, the same 30,000 or so genes, but each has differentiated into a particular role. That role is determined by the proportion of active genes within the cell that determines whether the cell is for example a liver cell or a nerve cell. A presumption among cell biologists was that this was a one way process of progressive and permanent change. What Dolly demonstrated was that it is possible to take a differentiated cell and essentially turn its clock back; to reactivate all its silent genes and make the cell behave as though it was a recently fertilised egg.

Dolly was also important because she captured the public imagination. A clone, a copy has been a very discernible strand within science fiction. The idea that there might be and exact copy of oneself somewhere around is a theme that has been pursued in science fiction and the prospect that it might be possible to clone a human being excited a lot of speculation and interest.

What is the longterm significance of Dolly?

At the moment that's difficult to say. The practical applications of cloning, of copying livestock seem relatively limited. The likelihood is that the longer lasting benefit will be in the change in perception about biology.

Our understanding now is that the cells in our bodies are a lot more plastic than we previously thought and it may be that as we understand more about repair processes, for various organs and tissues, we might find that this understanding informs research that is able to augment the bodies normal repair mechanisms. It may well prove to be an important factor in stem cell research and allow the derivation of stem cells from tissues other than early human embryos. This would alleviate the reservations that many people have about the use of human embryos for research or therapeutic purposes.