Expression of the mammalian X chromosome before and after fertilization.
The activity of hypoxanthine-guanine phosphoribosyltransferase in unfertilized mouse ova and in mouse embryos at the two-cell stage is proportional to the number of X chromosomes present during oogenesis. This indicates that the enzyme is X-linked in the mouse and that inactivation of the X chromosome does not occur during oogenesis. However, the genetic dosage effect of the X chromosomes is not present after the increase in hypoxanthine-guanine phosphoribosyltransferase activity in the late morula and the blastocyst stages. These results indicate that the X-linked enzyme lacuts is expressed sometimne after fertilization but before the morula stage.
D000619:Aminohydrolases / Q000032:analysis; D000818:Animals; D004622:Embryo, Mammalian / Q000201:enzymology*; D005260:Female; D005306:Fertilization; D005796:Genes; D008040:Genetic Linkage; D005865:Gestational Age; D006147:Guanine; D007042:Hypoxanthines; D007621:Karyotyping; D051379:Mice; D010063:Ovum / Q000201:enzymology*; D010430:Pentosyltransferases / Q000032:analysis*; D011247:Pregnancy; D012730:Sex Chromosomes
D007042:Hypoxanthines; D006147:Guanine; D010430:Pentosyltransferases; D000619:Aminohydrolases