Biomaterial Database

Multiple locations of the rDNA sites in holocentric chromosomes of Rhynchospora (Cyperaceae). 1998

A L Vanzela, and A Cuadrado, and N Jouve, and M Luceño, and M Guerra

Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, SP, Brazil.

Several cytogenetic studies have shown that representatives of the family Cyperaceae have holocentric chromosomes. Despite their interesting chromosome morphology, the chromosome organization has not been studied. This paper reports on the number and distribution of 18S-5.8S-26S ribosomal RNA sites by fluorescence in situ hybridization in eight Brazilian species of Rhynchospora. The signal of the rDNA probe was always localized in the telomeric regions. A high degree of variation was observed in the number of labelled sites, ranging from 4-8 in karyotypes with 2n = 10 to 30 sites in a karyotype with 50 chromosomes. It is possible that the same mechanism involved in the multiplication of these regions in organisms with monocentric chromosomes also plays a role in the polymorphism observed in holocentric chromosomes of Rhynchospora. An interesting feature of most hybridization sites was their diffuse state observed through to early metaphase. The decondensed state probably reflects the later transcription of this region during the cell cycle.

UI	MeSH Term	Description	Entries
D007399	Interphase	The interval between two successive CELL DIVISIONS during which the CHROMOSOMES are not individually distinguishable. It is composed of the G phases (G1 PHASE; G0 PHASE; G2 PHASE) and S PHASE (when DNA replication occurs).	Interphases
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
D008677	Metaphase	The phase of cell nucleus division following PROMETAPHASE, in which the CHROMOSOMES line up across the equatorial plane of the SPINDLE APPARATUS prior to separation.
D010944	Plants	Multicellular, eukaryotic life forms of kingdom Plantae. Plants acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations. It is a non-taxonomical term most often referring to LAND PLANTS. In broad sense it includes RHODOPHYTA and GLAUCOPHYTA along with VIRIDIPLANTAE.	Plant
D002874	Chromosome Mapping	Any method used for determining the location of and relative distances between genes on a chromosome.	Gene Mapping,Linkage Mapping,Genome Mapping,Chromosome Mappings,Gene Mappings,Genome Mappings,Linkage Mappings,Mapping, Chromosome,Mapping, Gene,Mapping, Genome,Mapping, Linkage,Mappings, Chromosome,Mappings, Gene,Mappings, Genome,Mappings, Linkage
D004275	DNA, Ribosomal	DNA sequences encoding RIBOSOMAL RNA and the segments of DNA separating the individual ribosomal RNA genes, referred to as RIBOSOMAL SPACER DNA.	Ribosomal DNA,rDNA
D012335	RNA, Ribosomal	The most abundant form of RNA. Together with proteins, it forms the ribosomes, playing a structural role and also a role in ribosomal binding of mRNA and tRNAs. Individual chains are conventionally designated by their sedimentation coefficients. In eukaryotes, four large chains exist, synthesized in the nucleolus and constituting about 50% of the ribosome. (Dorland, 28th ed)	Ribosomal RNA,15S RNA,RNA, 15S
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
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
D018744	DNA, Plant	Deoxyribonucleic acid that makes up the genetic material of plants.	Plant DNA