Friday, 29 July 2016

Dolly just had some bad luck

Twenty years ago, scientists managed to clone a mammal for the first time; Dolly. The problem was, Dolly died only six years later, from what scientists thought were side-effects of cloning. Kevin Sinclair has discovered that this wasn’t the case.

Cloning some sheep
But how do you actually clone a mammal, or to be more specific, a sheep? To create Dolly the sheep, scientists did the following. First, they took a few cells from an adult sheep. Through some complicated processes, they managed to change those cells into stem cells. This is very important, because stem cells can evolve into all types of cells. Whilst they can become skin cells, liver cells or bone cells, the cells the scientists took from the adult sheep could only stay what they already were; udder cells in this case. Not wanting a sheep entirely made out of udder, you would need to start with a stem cell. But, since the stem cells were made from cells from the adult sheep, Dolly had the exact same genes as that adult sheep and therefore looked exactly the same. 

Poor Dolly
Stem cells also seem to have a downside. When you take the cell from a four-year-old sheep, the stem cells will also be four years old. Because of this, the new sheep will already be four years old when it is born. Because of this, the sheep will age much faster and die at a young age, like Dolly did. She died when she was six years old, while sheep can normally live for fifteen to twenty years. But now, Kevin Sinclair and his team have discovered that Dolly didn’t die of old age caused by cloning.

But they’re all right!
The method they used to find this out was actually quite simple. They made four more clones from the same stem cells Dolly was made from. This way, these four sheep were clones of the original adult sheep, but also of Dolly. They did this about eight years ago, so now the sheep are eight years old. Unlike Dolly, they didn’t die of old age early, defying the expectations of the scientists. There doesn’t seem to be anything wrong with them. The scientists checked the sheep’s blood pressure, their joints and bones and other things. They didn’t seem to find anything that indicated that the sheep were aging faster than normal (not cloned) sheep. This means that Dolly probably didn’t die because she was cloned, but because of other reasons.

What went wrong?
But why did Dolly die? Scientists aren’t completely sure yet, but they have theories. It may be possible that something went wrong with Dolly when she was still in her mother’s womb, which caused Dolly to age really fast, but this new research has proven that this doesn’t need to happen when you clone a sheep. This means that cloning is much safer than we thought and this discovery has cleared the way for further research about cloning. 

Click here to read more about biology.


No comments:

Post a Comment

Great that you want to comment! Please write something relevant and non-offending.