Cytonucleoproteins in cleaving eggs of <i>Xenopus lœvis</i>

Abstract

ABSTRACT The cytoplasm of unfertilized eggs of Xenopus laevis induces DNA synthesis in a high proportion of adult and embryonic nuclei introduced into it (Graham, Arms &amp; Gurdon, 1966). This induction of DNA synthesis is not due merely to the fact that the egg cytoplasm supplies precursors of DNA synthesis which might be absent from the nuclei, since adult liver nuclei, at least, of those nuclei which are induced to synthesize DNA after their injection into eggs, do not do so if incubated in vitro with DNA precursors (Arms, 1968). One of the ways in which the cytoplasm of unfertilized eggs might induce DNA synthesis is by supplying other molecules, such as various enzymes, to the introduced nuclei.