Biomaterial Database

Terminal heterochromatin and alternative telomeric sequences in Allium cepa. 1998

U Pich, and I Schubert

Institut für Pflanzengenetik und Kulturpflanzenforschung, Gatersleben, Germany.

The chromosome termini of the onion (Allium cepa) apparently lack Arabidopsis-type telomeric repeats. The terminal Giemsa bands of A. cepa chromosomes contain a 375-bp satellite and (short arm of chromosome 8)/ or (short arm of chromosome 6) rDNA repeats. By means of fluorescence in situ hybridization (FISH) on metaphase chromosomes and on DNA fibres with probes specific for Ty1-copia retroelements and a En/Spm-transposable element-like sequence, respectively, it was demonstrated that the former are rarely and the latter frequently associated with satellite repeats within the terminal heterochromatin. Polymerase chain reaction of polyC-tailed nuclear DNA with anchor primers and single satellite-specific primers yielded amplification products that, after cloning and sequencing, revealed satellite sequences. This supports the idea that satellite repeats represent one class of terminal sequences in A. cepa.

UI	MeSH Term	Description	Entries
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D012091	Repetitive Sequences, Nucleic Acid	Sequences of DNA or RNA that occur in multiple copies. There are several types: INTERSPERSED REPETITIVE SEQUENCES are copies of transposable elements (DNA TRANSPOSABLE ELEMENTS or RETROELEMENTS) dispersed throughout the genome. TERMINAL REPEAT SEQUENCES flank both ends of another sequence, for example, the long terminal repeats (LTRs) on RETROVIRUSES. Variations may be direct repeats, those occurring in the same direction, or inverted repeats, those opposite to each other in direction. TANDEM REPEAT SEQUENCES are copies which lie adjacent to each other, direct or inverted (INVERTED REPEAT SEQUENCES).	DNA Repetitious Region,Direct Repeat,Genes, Selfish,Nucleic Acid Repetitive Sequences,Repetitive Region,Selfish DNA,Selfish Genes,DNA, Selfish,Repetitious Region, DNA,Repetitive Sequence,DNA Repetitious Regions,DNAs, Selfish,Direct Repeats,Gene, Selfish,Repeat, Direct,Repeats, Direct,Repetitious Regions, DNA,Repetitive Regions,Repetitive Sequences,Selfish DNAs,Selfish Gene
D006570	Heterochromatin	The portion of chromosome material that remains condensed and is transcriptionally inactive during INTERPHASE.	Heterochromatins
D000490	Allium	A genus of the plant family Amaryllidaceae. Many produce pungent, often bacteriostatic and physiologically active compounds and are used as VEGETABLES; CONDIMENTS; and medicament, the latter in traditional medicine.	Alliaceae
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D015139	Blotting, Southern	A method (first developed by E.M. Southern) for detection of DNA that has been electrophoretically separated and immobilized by blotting on nitrocellulose or other type of paper or nylon membrane followed by hybridization with labeled NUCLEIC ACID PROBES.	Southern Blotting,Blot, Southern,Southern Blot
D015342	DNA Probes	Species- or subspecies-specific DNA (including COMPLEMENTARY DNA; conserved genes, whole chromosomes, or whole genomes) used in hybridization studies in order to identify microorganisms, to measure DNA-DNA homologies, to group subspecies, etc. The DNA probe hybridizes with a specific mRNA, if present. Conventional techniques used for testing for the hybridization product include dot blot assays, Southern blot assays, and DNA:RNA hybrid-specific antibody tests. Conventional labels for the DNA probe include the radioisotope labels 32P and 125I and the chemical label biotin. The use of DNA probes provides a specific, sensitive, rapid, and inexpensive replacement for cell culture techniques for diagnosing infections.	Chromosomal Probes,DNA Hybridization Probe,DNA Probe,Gene Probes, DNA,Conserved Gene Probes,DNA Hybridization Probes,Whole Chromosomal Probes,Whole Genomic DNA Probes,Chromosomal Probes, Whole,DNA Gene Probes,Gene Probes, Conserved,Hybridization Probe, DNA,Hybridization Probes, DNA,Probe, DNA,Probe, DNA Hybridization,Probes, Chromosomal,Probes, Conserved Gene,Probes, DNA,Probes, DNA Gene,Probes, DNA Hybridization,Probes, Whole Chromosomal
D016133	Polymerase Chain Reaction	In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.	Anchored PCR,Inverse PCR,Nested PCR,PCR,Anchored Polymerase Chain Reaction,Inverse Polymerase Chain Reaction,Nested Polymerase Chain Reaction,PCR, Anchored,PCR, Inverse,PCR, Nested,Polymerase Chain Reactions,Reaction, Polymerase Chain,Reactions, Polymerase Chain
D016615	Telomere	A terminal section of a chromosome which has a specialized structure and which is involved in chromosomal replication and stability. Its length is believed to be a few hundred base pairs.	Telomeres
D017404	In Situ Hybridization, Fluorescence	A type of IN SITU HYBRIDIZATION in which target sequences are stained with fluorescent dye so their location and size can be determined using fluorescence microscopy. This staining is sufficiently distinct that the hybridization signal can be seen both in metaphase spreads and in interphase nuclei.	FISH Technique,Fluorescent in Situ Hybridization,Hybridization in Situ, Fluorescence,FISH Technic,Hybridization in Situ, Fluorescent,In Situ Hybridization, Fluorescent,FISH Technics,FISH Techniques,Technic, FISH,Technics, FISH,Technique, FISH,Techniques, FISH