![]() ![]() This animal is often held up as the ultimate GM horror, created so that farmers will be saved the effort of having to pluck feathers before poultry are sold to supermarkets. Thus it may be possible one day to cook omelettes that could prevent us succumbing to disease, though most scientists envisage a slightly different route in which GM egg whites are dried out before their antibodies are removed and administered separately.īut what geneticists have not developed, insists Sang, is the featherless chicken, illustrated on the right. In particular, they are working on whites in which the hen expresses antibodies that can block viruses which cause enteric – ie gut – diseases. Roslin scientists are also working on a strain that can express therapeutic proteins in the whites of eggs. In fact, the chicken turns out to be a popular target for modification. For example, if this part of the chick embryo develops into stem cells, that tells us whether other animals, including humans, have stem cells in that part of their embryos and will therefore provide us with important basic biological insights." In other words, stem-cell science can get a boost from the glowing green chicken. "You can then watch and see what organ that group of cells develops into because that tissue will have a green fluorescence. "You can take a sample of cells from a green embryo and then put them into a normal embryo," says Sang. This allows scientists to tinker with the way in which an embryo develops and so reveal processes that were previously obscured. But the technique had been pushed to its limits by scientists – until the arrival of the GM mutant. Thus the chick provides us with a key model for understanding the development of early embryos for all vertebrates, including humans. By contrast, a mammal foetus gestates inside the uterus of its mother, making it far harder for researchers to monitor physiological changes. The crucial point is that chicks are extremely useful for studying embryo development because their growth takes place inside an egg which can be kept in an incubator and studied fairly easily. "The protein itself does not affect the chicken in any way but it is a very useful tool for looking at the very early embryos," says Roslin researcher Professor Helen Sang. As we have noted, the technique involves putting jellyfish genes into the DNA of a chick so that it makes a green, fluorescent protein. Fluorescent chickens were developed by scientists at Edinburgh University's Roslin Institute, the zoological research organisation responsible for the creation of Dolly the sheep. ![]() Yet it has become the standard route for researchers. It also makes the public uncomfortable and raises the hackles of animal rights organisations. But what gives the insertion of a piece of DNA from one living being into another such an advantage for scientists? After all, inserting invertebrate genes into mammals, and vice versa, is not easy. In other words, more and more scientists are now relying on the use of GM animals, as opposed to unmodified ones, for their research. ![]()
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