Clones. What was once an idea confined to science fiction is now a common term that even your grandmother must know about! With the recent US Food and Drug Administration (FDA) decision that cloned animals as food are no different from regular animals, you will surely be hearing about cloned animals a lot more in the future. But what exactly is a cloned animal and how are these animals made?
How are cloned animals made?
Cloning refers to the process of making an identical copy of something. There are many different types of cloning, depending on what the application is. For example, a molecular biologist, who is someone who studies the molecules of life, might use molecular cloning to make identical copies of a gene they are studying. When the cloning aims to make a genetically identical copy of an entire organism, we refer to this as animal cloning or organism cloning.
Did you know? The first cloned animal, Dolly the Sheep, was born over 10 years ago and was named after the country singer Dolly Parton!
Making a genetically identical copy of an animal is, surprisingly, a relatively easy to understand technique. The whole idea is to create a female egg that has the same genetic content as the animal being cloned. Firstly, an unfertilized egg is taken to a laboratory where its nucleus (i.e. the part of the cell which contains the DNA) is removed. This is important because the egg’s DNA is NOT the same as the DNA in the rest of the animal’s cells because the egg only has half the genetic content (in case you’re wondering, the other half of an embryo’s genetic content comes from the father’s sperm cell).
Did you know? The female egg is the largest human cell in the body and completely dwarfs the male sperm, which is the smallest human cell.
Once the nucleus is removed from the egg, it is ready to receive the nucleus of the animal you want to clone. This nucleus, which can’t come from an egg or sperm cell (remember because it has only half the genetic content!), but could come from any other cell such as a skin cell or a liver cell, is then injected into the egg. Congratulations, you’ve made an egg that has the same genetic makeup as the animal you want to clone!
With the aid of a brief electrical shock, the egg will start to divide and, once it reaches a particular size, it will be implanted into a surrogate mother. The rest is the same as how animals are normally born; the egg continues to divide and grow inside the surrogate mother until it has developed into an embryo, which then grows and develops into a fetus, followed eventually by the birth of a new animal. Except in this case, the newborn animal is a genetic copy of another animal!
When will we see cloned animals at the local supermarket?
Well, that’s a bit of a trick question, because you’re unlikely to see a cloned cow or chicken walking around in your local supermarket! As for food, such as steaks or milk, which have come from a cloned animal or their offspring, no one really knows. The recent decision by the US FDA paves the way for food from cloned animals or their offspring entering the marketplace. They have, however, encouraged the makers of these cloned animals to stick with a volunteer moratorium on their release into the food supply.
As for Canada, currently there are no cloned animals in our food supply nor have there been any decisions made by Health Canada concerning cloned animals as food. So while the technology of cloning has advanced rapidly, finding cloned animals in the food supply might take a considerably longer time.
Photo gallery of cloned animals
FDA info on cloned animals as food
John is currently a graduate student in the department of Molecular Genetics at the University of Toronto. He is frantically writing up his PhD thesis at the moment, but in his spare time he enjoys reading and playing the trombone.