Ralph the laboratory rat and his brother are a piece of nice timing — and a breakthrough in cloning technology from France. In the past five years researchers in Britain, America and Japan have cloned sheep, pigs, cattle, a kitten, mice and even a horse, but until now, rats have proved a puzzle.
Cloning starts with DNA from a donor and an oocyte, or egg. But a rat’s egg spontaneously activates within 60 minutes of removal from the oviducts, and then aborts. Researchers in Lyon, France, report in Science today that with precise timing and careful use of drugs they have successfully transferred DNA from an adult rat cell into an egg.
The rat is an important animal for experimenters: it can answer questions about hypertension, auto-immune diseases, some cancers, two types of diabetes, and liver and kidney failure. Researchers also use them to tease out puzzles in neuroscience, and behavioural science.
One laboratory animal in four is a rat, and pharmaceutical companies would like to test promising drugs on identical genetically modified rats.
But as usual, it took a lot of attempts to produce Ralph. French and Chinese scientists working with a commercial biotech venture called genOway in Lyon made 876 embryos, and implanted 129 of them. Three male rats were born live, and one died three hours after birth.
”The two remaining pups developed normally into sexually mature animals,” the French team report. – Guardian Unlimited Â