Cloned dog takes a bow-wow
2005-08-03 19:30
Paris - South Korean scientists announced on Wednesday they had carried out the first successful cloning of a dog, creating a duplicate of a three-year-old Afghan hound by using the same technique that gave the world Dolly the Sheep.
The copycat canine, born on April 24, has been named Snuppy, for Seoul National University Puppy, they reported in Nature, the British weekly science journal.
Snuppy, with black, tan and white fur, is genetically identical to his father, according to DNA tests.
He joins sheep, mice, cows, goats, pigs, rabbits, cats, a mule, a horse, rats and a rare wild ox called a gaur in the list of animals that have been cloned since Dolly, the first mammal to be created from an adult cell, was born in Scotland in July 1996.
The technique, called somatic cell nuclear transfer, entails taking an egg and removing the nucleus that contains the DNA programme for life.
The nucleus is then replaced by the nucleus of an adult cell taken from the animal which is to be cloned.
Electricity
The reconstructed egg is then treated with chemicals or a jolt of electricity to make it divide.
It then continues to grow in a dish filled with nurturing chemicals, until it becomes a cluster of cells big enough to transplanted into the uterus of a surrogate mother.
Dogs have been among the trickiest of animals to clone, mainly because of the difficulty of acquiring eggs that are in a state of maturity.
In contrast to other mammal species, dogs ovulate when their eggs are immature. The eggs go to a special duct to mature for two or three days.
The South Korean team, led by Woo Suk Hwang of the university's College of Veterinary Medicine, solved the problem by gently flushing out the oviduct to harvest the mature eggs.
The donor nucleus for Snuppy came from the ear skin of a male Afghan hound, while the surrogate mother was a yellow Labrador retriever, which gave birth to the puppy and raised it.
Success rate very low
The team say their achievement is a step forward for conservationists who want to preserve rare species, and for canine specialists who want to know how genes affect the behavioural traits of various dog breeds.
But they admit that the success rate of the cloning is still very low.
A total of 1 095 embryos were transferred into 123 recipients. Just three of these embryos resulted in pregnancies, and only two of these pregnancies resulted in live births.
Cloned animals are notorious for having short lives or falling prey to sickness, and this - along with moral
reasons - is why scientists sternly warn against attempts to clone human beings.