Dolly deathIn 2003, Dolly, the world-famous firstcloned sheep, was put down, at age about 6½years. She had been suffering from a progressive lung disease. Dolly, a Finn Dorset sheep, wasborn at the Roslin Institute, Edinburgh, Scotland on 5 Jul 1996. This accomplishment, the first mammal cloned from an adult cell was announced on 23 Feb 1997. Using microscopic needles, scientists had replaced the nucleus of an egg cell with the nucleus from a parent cell (an udder cell, in Dolly's case). The resulting embryo was implanted into the womb of a third, surrogate sheep. Somehow, the egg cell reprogrammed the donated DNA contained within its new nucleus. Normal life expectancy of a Finn Dorset sheep is about 11 to 12 years. Dolly's early death, like her birth, raised new controversy about the wisdom of cloning.« |
