The cloned sheep made from the same batch of genetic material as Dolly, the first ever clone of an adult animal, are alive and well, aging as normal as any other sheep even though Dolly died earlier than scientists expected.
A new study led by Kevin Sinclair, a developmental biologist at the University of Nottingham, analyzed 13 cloned sheep, four even being the sister clones of Dolly. The clones recently reached their ninth birthday, which according to Sinclair would make them 70 in sheep years. The study concluded that cloned animals do not age any faster or have any other abnormalities than any regular old sheep. The results were published in the journal Nature Communications on July 26.
The purpose of the study was to determine if the technology used to create the cloned sheep was safe, as it can be used to develop treatments for various medical conditions. The results manage to calm any worries scientists might have had regarding the overall lifespan and health of cloned animals.
Some doubts were raised regarding the procedure when Dolly died relatively young, after six and a half years because of a pulmonary virus. Sinclair attributed her death to just bad luck but she also was affected by a joint disease in her knees called osteoarthritis, and the tips of her chromosomes were short. These were signs many scientists interpreted as a faster aging process than conventional sheep.
The main concern about cloning an adult animal was that the body of the clone might have been set to an older clock from the start.
“If you’re going to create these animals, they should be normal in every respect. They should be just as healthy as any other animal that’s conceived naturally. If that is not the case, then it raises serious ethical and welfare concerns about creating these animals in the first place,” Sinclair said.
The research team evaluated the clone’s blood pressure, metabolism, heart function, muscles and joints, and any signs of premature aging overall. They had a slight sign of arthritis but nothing unusual for any sheep at that age.
The scientists didn’t measure the size of the animal’s chromosome tips to compare them to Dolly’s. That test would have to wait until the sheep are euthanized after reaching ten years of life, in order to take cell samples from various organs and do a detailed postmortem analysis of their bodies.
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