Biomaterial Database

Differential order of replication of Xenopus laevis 5S RNA genes. 1986

D R Guinta, and L J Korn

In Xenopus laevis there are two multigene families of 5S RNA genes: the oocyte-type 5S RNA genes which are expressed only in oocytes and the somatic-type 5S RNA genes which are expressed throughout development. The Xenopus 5S RNA replication-expression model of Gottesfeld and Bloomer (Cell 28:781-791, 1982) and Wormington et al. (Cold Spring Harbor Symp. Quant. Biol. 47:879-884, 1983) predicts that the somatic-type 5S RNA genes replicate earlier in the cell cycle than do the oocyte-type genes. Hence, the somatic-type 5S RNA genes have a competitive advantage in binding the transcription factor TFIIIA in somatic cells and are thereby expressed to the exclusion of the oocyte-type genes. To test the replication-expression model, we determined the order of replication of the oocyte- and somatic-type 5S RNA genes. Xenopus cells were labeled with bromodeoxyuridine, stained for DNA content, and then sorted into fractions of S phase by using a fluorescence-activated cell sorter. The newly replicated DNA containing bromodeoxyuridine was separated from the lighter, unreplicated DNA by equilibrium centrifugation and was hybridized with DNA probes specific for the oocyte- and somatic-type 5S RNA genes. In this way we found that the somatic-type 5S RNA genes replicate early in S phase, whereas the oocyte-type 5S RNA genes replicate late in S phase, demonstrating a key aspect of the replication-expression model.

UI	MeSH Term	Description	Entries
D009865	Oocytes	Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).	Ovocytes,Oocyte,Ovocyte
D002453	Cell Cycle	The complex series of phenomena, occurring between the end of one CELL DIVISION and the end of the next, by which cellular material is duplicated and then divided between two daughter cells. The cell cycle includes INTERPHASE, which includes G0 PHASE; G1 PHASE; S PHASE; and G2 PHASE, and CELL DIVISION PHASE.	Cell Division Cycle,Cell Cycles,Cell Division Cycles,Cycle, Cell,Cycle, Cell Division,Cycles, Cell,Cycles, Cell Division,Division Cycle, Cell,Division Cycles, Cell
D002469	Cell Separation	Techniques for separating distinct populations of cells.	Cell Isolation,Cell Segregation,Isolation, Cell,Cell Isolations,Cell Segregations,Cell Separations,Isolations, Cell,Segregation, Cell,Segregations, Cell,Separation, Cell,Separations, Cell
D004261	DNA Replication	The process by which a DNA molecule is duplicated.	Autonomous Replication,Replication, Autonomous,Autonomous Replications,DNA Replications,Replication, DNA,Replications, Autonomous,Replications, DNA
D005786	Gene Expression Regulation	Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.	Gene Action Regulation,Regulation of Gene Expression,Expression Regulation, Gene,Regulation, Gene Action,Regulation, Gene Expression
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
D012313	RNA	A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)	RNA, Non-Polyadenylated,Ribonucleic Acid,Gene Products, RNA,Non-Polyadenylated RNA,Acid, Ribonucleic,Non Polyadenylated RNA,RNA Gene Products,RNA, Non Polyadenylated
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D014982	Xenopus laevis	The commonest and widest ranging species of the clawed "frog" (Xenopus) in Africa. This species is used extensively in research. There is now a significant population in California derived from escaped laboratory animals.	Platanna,X. laevis,Platannas,X. laevi