Biomaterial Database

X-chromosome activity in preimplantation mouse embryos from XX and XO mothers. 1978

M Monk, and M Harper

Embryos from XO female mice begin development with half the activity levels of an enzyme (HPRT) coded for by a gene on the X chromosome, compared with embryos from XX females. Groups of unfertilized eggs and individual embryos at the 8-cell, morula and blastocyst stages were assayed for HPRT activity. An autosomally coded enzyme (APRT) was assayed simultaneously in the same reaction mix as a control. There is a substantial increase in HPRT activity by the 8-cell stage. However, the mean activity of HPRT in embryos of XO mothers remains half that in embryos of XX mothers. This suggests a significant maternally inherited component of HPRT activity in 8-cell embryos. By the 9- to 16-cell morula stage the HPRT activities in the two groups of embryos become similar due, presumably, to a transition to embryo-coded activity; HPRT activities in individual morulae from XX mothers show a bimodal distribution consistent with the hypothesis that both X-chromosomes are active in XX embryos at this stage.

UI	MeSH Term	Description	Entries
D007041	Hypoxanthine Phosphoribosyltransferase	An enzyme that catalyzes the conversion of 5-phosphoribosyl-1-pyrophosphate and hypoxanthine, guanine, or MERCAPTOPURINE to the corresponding 5'-mononucleotides and pyrophosphate. The enzyme is important in purine biosynthesis as well as central nervous system functions. Complete lack of enzyme activity is associated with the LESCH-NYHAN SYNDROME, while partial deficiency results in overproduction of uric acid. EC 2.4.2.8.	Guanine Phosphoribosyltransferase,HPRT,Hypoxanthine-Guanine Phosphoribosyltransferase,IMP Pyrophosphorylase,HGPRT,HPRTase,Hypoxanthine Guanine Phosphoribosyltransferase,Phosphoribosyltransferase, Guanine,Phosphoribosyltransferase, Hypoxanthine,Phosphoribosyltransferase, Hypoxanthine-Guanine,Pyrophosphorylase, IMP
D007621	Karyotyping	Mapping of the KARYOTYPE of a cell.	Karyotype Analysis Methods,Analysis Method, Karyotype,Analysis Methods, Karyotype,Karyotype Analysis Method,Karyotypings,Method, Karyotype Analysis,Methods, Karyotype Analysis
D001755	Blastocyst	A post-MORULA preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. A blastocyst has two distinctive tissues. The outer layer of trophoblasts gives rise to extra-embryonic tissues. The inner cell mass gives rise to the embryonic disc and eventual embryo proper.	Embryo, Preimplantation,Blastocysts,Embryos, Preimplantation,Preimplantation Embryo,Preimplantation Embryos
D004622	Embryo, Mammalian	The entity of a developing mammal (MAMMALS), generally from the cleavage of a ZYGOTE to the end of embryonic differentiation of basic structures. For the human embryo, this represents the first two months of intrauterine development preceding the stages of the FETUS.	Embryonic Structures, Mammalian,Mammalian Embryo,Mammalian Embryo Structures,Mammalian Embryonic Structures,Embryo Structure, Mammalian,Embryo Structures, Mammalian,Embryonic Structure, Mammalian,Embryos, Mammalian,Mammalian Embryo Structure,Mammalian Embryonic Structure,Mammalian Embryos,Structure, Mammalian Embryo,Structure, Mammalian Embryonic,Structures, Mammalian Embryo,Structures, Mammalian Embryonic
D005260	Female		Females
D000228	Adenine Phosphoribosyltransferase	An enzyme catalyzing the formation of AMP from adenine and phosphoribosylpyrophosphate. It can act as a salvage enzyme for recycling of adenine into nucleic acids. EC 2.4.2.7.	AMP Pyrophosphorylase,Transphosphoribosidase,APRTase,Phosphoribosyltransferase, Adenine,Pyrophosphorylase, AMP
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012730	Sex Chromosomes	The homologous chromosomes that are dissimilar in the heterogametic sex. There are the X CHROMOSOME, the Y CHROMOSOME, and the W, Z chromosomes (in animals in which the female is the heterogametic sex (the silkworm moth Bombyx mori, for example)). In such cases the W chromosome is the female-determining and the male is ZZ. (From King & Stansfield, A Dictionary of Genetics, 4th ed)	Gonosomes,Chromosome, Sex,Chromosomes, Sex,Gonosome,Sex Chromosome
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D014960	X Chromosome	The female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in human and other male-heterogametic species.	Chromosome, X,Chromosomes, X,X Chromosomes