Biomaterial Database

Isolation and characterisation of a transcribing polynucleosomal chromatin fraction. 1983

T Wurtz, and S Fakan

A method is described for preparation of a fraction of chromatin enriched in transcribing regions from nuclei of mouse GR cells. This fraction, released by mild staphylococcal nuclease digestion of isolated nuclei, contains 2 to 10% of the DNA as polynucleosomal chromatin together with 50-70% of pulse-labelled RNA and about 90% of all template-engaged RNA polymerase B molecules, titrated with (3H)-alpha-amanitin. Hybridisation of DNA from this chromatin fraction to total nuclear RNA in excess shows that it is enriched in frequently-transcribed DNA sequences. A modification of the Miller technique, allowing the spreading of the active chromatin fraction for electron microscopy, has been developed. Examination of the spreads reveals that this chromatin fraction contains 20-100 nucleosome-long polynucleosomal chains bearing lateral RNP fibrils interpreted as nascent transcripts. The average length of the DNA fragments in the fraction is greater than that of average transcribed regions, suggesting that the transcribed regions are linked to flanking segments whose chromatin conformation probably contributes to the selective release of transcribing chromatin.

UI	MeSH Term	Description	Entries
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D009693	Nucleic Acid Hybridization	Widely used technique which exploits the ability of complementary sequences in single-stranded DNAs or RNAs to pair with each other to form a double helix. Hybridization can take place between two complimentary DNA sequences, between a single-stranded DNA and a complementary RNA, or between two RNA sequences. The technique is used to detect and isolate specific sequences, measure homology, or define other characteristics of one or both strands. (Kendrew, Encyclopedia of Molecular Biology, 1994, p503)	Genomic Hybridization,Acid Hybridization, Nucleic,Acid Hybridizations, Nucleic,Genomic Hybridizations,Hybridization, Genomic,Hybridization, Nucleic Acid,Hybridizations, Genomic,Hybridizations, Nucleic Acid,Nucleic Acid Hybridizations
D009695	Nucleic Acid Renaturation	The reformation of all, or part of, the native conformation of a nucleic acid molecule after the molecule has undergone denaturation.	Acid Renaturation, Nucleic,Acid Renaturations, Nucleic,Nucleic Acid Renaturations,Renaturation, Nucleic Acid,Renaturations, Nucleic Acid
D009707	Nucleosomes	The repeating structural units of chromatin, each consisting of approximately 200 base pairs of DNA wound around a protein core. This core is composed of the histones H2A, H2B, H3, and H4.	Dinucleosomes,Polynucleosomes,Dinucleosome,Nucleosome,Polynucleosome
D002458	Cell Fractionation	Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.	Cell Fractionations,Fractionation, Cell,Fractionations, Cell
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D002843	Chromatin	The material of CHROMOSOMES. It is a complex of DNA; HISTONES; and nonhistone proteins (CHROMOSOMAL PROTEINS, NON-HISTONE) found within the nucleus of a cell.	Chromatins
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
D012319	RNA Polymerase II	A DNA-dependent RNA polymerase present in bacterial, plant, and animal cells. It functions in the nucleoplasmic structure and transcribes DNA into RNA. It has different requirements for cations and salt than RNA polymerase I and is strongly inhibited by alpha-amanitin. EC 2.7.7.6.	DNA-Dependent RNA Polymerase II,RNA Pol II,RNA Polymerase B,DNA Dependent RNA Polymerase II
D014158	Transcription, Genetic	The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.	Genetic Transcription