be230cLecture6

He went on to argue that somakc cells on the other

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Unformatted text preview: ulated the germ plasm theory. Germ plasm theory states that all heritable informaKon is retained within the germ cell lineage, which rise to gametes. Weismann postulated that germ cells are not influenced by the development or life experience of somaKc cells. He went on to argue that somaKc cells, on the other hand, undergo a diluKon of heritable informaKon so that different cells retain different geneKc material. These views encapsulated the debate of whether or not somaKc nuclei lacked the full complement of heritable material of germ cells. Historical Origins of Nuclear Reprogramming •  Wilhelm Roux’s hot needle experiments of 1882 ­1887. Half ­ embryos of the frog arose aaer killing 1 or 2 blastomeres of a 2 to 4 ­cell embryo. •  Roux argued that individual blastomeres self ­differenKate, and that individual nuclei indeed loose the ability to regulate during development. Historical Origins of Nuclear Reprogramming •  Hans Driesch separated blastomeres of sea urchins and found they individually gave rise to complete organisms, 1892. •  Hans Spemann, 1928, did his now famous hair noose experiment. Spemann wrapped a noose around the egg and carefully Kghtened it around the middle, forcing the dark nucleus into just one half of the cell. Following several divisions of the embryo, Spemann carefully loosened the loop of hair. Aaer a few minutes, a nucleus from the embryo slipped into the clear part of the egg, and the noose was Kghtened again. Over Kme, this nucleus directed development of an enKre embryo. This was the first example of nuclear transfer, and led Spemann to propose, in 1938, a “fantasKcal experiment” of microsurgical nuclear transfer of a somaKc nucleus from adult Kssue into an enucleated egg. 2 4/18/13 Historical Origins of Nucl...
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This document was uploaded on 04/09/2014.

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