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HELLO, DOLLY: FIRST CLONING OF AN ADULT MAMMAL.

Cloning involves building a living, multicellular organism from the genetic information contained in the nucleus of a single cell. Typically, this has been accomplished in plants, amphibians, and animals with embryonic cells, but until now scientists had not attempted cloning from cells of an adult mammal. Indeed, many believed that these cells were too highly differentiated to allow cloning.

However, a Scottish team transferred the nucleus of a cell from an adult white-faced sheep into an egg taken from an adult black-faced sheep, after the nucleus from that egg had been removed. The "new" egg was reimplanted in the uterus of the black-faced sheep, and ultimately a white-faced lamb (named Dolly) was born. Dolly is now seven months old and healthy. Genetic studies confirm that Dolly is indeed a clone of the white-faced sheep who donated the cell nucleus. The researchers achieved this success by inducing the white-faced sheep's cell to exit the growth phase of its cycle before they attempted the nuclear transfer.

Comment: Following this dramatic breakthrough, there will surely be attempts to clone adult livestock endowed with special qualities, such as having more lean meat or producing more milk. However, this research made headlines because it makes the question of whether adult humans can be cloned, and whether such a practice would be ethical, a reality instead of science fiction.

— AL Komaroff

Published in Journal Watch General Medicine March 14, 1997

Citation(s):

Wilmut I et al. Viable offspring derived from fetal and adult mammalian cells. Nature 1997 Feb 27 385 810-813.

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