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Biology of Reproduction, Vol 1, 11-20, Copyright © 1969 by Society for the Study of Reproduction
1 Department of Molecular, Cellular and Developmental Biology, University of Colorado,
Boulder, Colorado 80302 Embryo culture and radioautographic techniques were used to detect incorporation of
precursors of DNA, RNA and proteins by blastocysts of mammals with and without a
delayed implantation. These experiments reveal the absence of labeled thymine incorporation by diapausing blastocysts from mink, fur seal, and lactating rat, although thymine
is incorporated by nondiapausing rabbit and rat blastocysts. There is little or no incorporation of labeled uracil by blastocysts from those animals which have a relatively
long and obligate diapause; but significant levels of uracil incorporation are present in
the blastocysts from lactating rats, which have a shorter and facultative delay. Conversely, nondiapausing blastocysts of rat and rabbit have high levels of nucleic acid
synthesis, as judged by incorporation of the labeled precursors. Incorporation of amino acids was shown to be present in mink, armadillo, and fur
seal blastocysts and, contrary to earlier findings of others, also in diapausing rodent
blastocysts. It is postulated that a uterine fluid component which may regulate (inhibit?)
protein synthesis is washed out or diluted subsequent to removal of the blastocysts from
the uterus, resulting in protein synthesis in vitro. This hypothesis is supported by the
observation that diapausing rat blastocysts require twice as long as the nondiapausing
ones to show incorporation of labeled methionine in vitro. The results reported here also support the hypothesis that "masked" mRNA may exist
in the preimplantation mammal embryo.
This article has been cited by other articles:
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J. A. Desmarais, V. Bordignon, F. L. Lopes, L. C. Smith, and B. D. Murphy The Escape of the Mink Embryo from Obligate Diapause Biol Reprod, March 1, 2004; 70(3): 662 - 670. [Abstract] [Full Text] [PDF] |
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