Biomaterial Database

Nucleolar organizing regions, 18S and 5S rDNA in Astyanax scabripinnis (Pisces, Characidae): populations distribution and functional diversity. 2000

D A Ferro, and D M Néo, and O Moreira-Filho, and L A Bertollo

Universidade Federal de São Carlos, Departamento de Genética e Evolução, SP, Brazil.

Astyanax scabripinnis specimens from four distinct populations in Brazil were studied with respect to their karyotype macrostructure, nucleolar organizer regions, and 18S and 5S rRNA genes. The four populations showed a 2n = 50 chromosomes (3 M + 11 SM + 5 ST + 6 A pairs) and 1-2 B chromosomes. No chromosomal differentiations were observed between sexes. Although a karyotypic diversity has been characterized in this fish group, the populations now analyzed presented the same macrokaryotypic pattern. Chromosome mapping of 5S rDNA showed a total of eight sites located in four distinct chromosomal pairs, with no apparent differences among populations. A comparative study on 18S rDNA locations and Ag-NORs showed some secondary NOR sites that are not usually expressed in karyotypes and a probable differential NOR activity among populations. Correlations between these data, environmental conditions and B chromosomes are discussed.

UI	MeSH Term	Description	Entries
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
D009697	Nucleolus Organizer Region	The chromosome region which is active in nucleolus formation and which functions in the synthesis of ribosomal RNA.	Nucleolar Organizer,Nucleolar Organizers,Nucleolus Organizer Regions,Organizer Region, Nucleolus,Organizer Regions, Nucleolus,Organizer, Nucleolar,Organizers, Nucleolar,Region, Nucleolus Organizer,Regions, Nucleolus Organizer
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
D005399	Fishes	A group of cold-blooded, aquatic vertebrates having gills, fins, a cartilaginous or bony endoskeleton, and elongated bodies covered with scales.
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
D012337	RNA, Ribosomal, 18S	Constituent of the 40S subunit of eukaryotic ribosomes. 18S rRNA is involved in the initiation of polypeptide synthesis in eukaryotes.	18S Ribosomal RNA,18S RRNA,RNA, 18S Ribosomal,Ribosomal RNA, 18S
D012341	RNA, Ribosomal, 5S	Constituent of the 50S subunit of prokaryotic ribosomes containing about 120 nucleotides and 34 proteins. It is also a constituent of the 60S subunit of eukaryotic ribosomes. 5S rRNA is involved in initiation of polypeptide synthesis.	5S Ribosomal RNA,5S rRNA,RNA, 5S Ribosomal,Ribosomal RNA, 5S,rRNA, 5S