Chromosomal characteristics of ribosomal DNA in two extant species of North American mudminnows Umbra pygmaea and U. limi (Euteleostei: Umbridae)
Language English Country Switzerland Media print
Document type Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.
PubMed
12698003
DOI
10.1159/000069800
PII: 69800
Knihovny.cz E-resources
- MeSH
- Silver Staining MeSH
- Chromosomes * ultrastructure MeSH
- In Situ Hybridization, Fluorescence MeSH
- Karyotyping MeSH
- Chromosome Mapping MeSH
- Nucleolus Organizer Region MeSH
- Chromosome Banding MeSH
- DNA, Ribosomal genetics MeSH
- Umbridae classification genetics MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Geographicals
- North America MeSH
- Names of Substances
- DNA, Ribosomal MeSH
The locations and chromosomal characteristics of ribosomal DNA (rDNA) sites in the karyotypes of two extant North American species of mudminnows, Umbra pygmaea and U. limi (2n = 22, NF = 44), were analyzed sequentially by conventional Giemsa staining, Ag staining, CMA(3) fluorescence and fluorescence in situ hybridization (FISH). The nucleolar organizer regions (NORs) were located in the fourth chromosomal pair in both species (pericentromeric region in U. pygmaea and subtelomeric in U. LIMI). These sites were strongly CMA(3)-positive suggesting that the rDNA sites in these species are associated with GC-rich DNA. FISH with a rDNA probe gave consistently positive signals in the same regions detected by Ag-staining and CMA(3)-fluorescence. However, both species also had additional CMA(3)-positive/Ag-negative heterochromatic blocks at pericentrometric regions of several chromosomal pairs (three in U. pygmaea and five in U. limi). FISH revealed additional rDNA clusters in both species. It is hypothesized that a paracentric inversion of the chromosome arm carrying the NORs might be one of the rearrangements differentiating the karyotypes of two North American species. The presence of additional rDNA sites is indicative of more complex rearrangements. The pericentromeric NOR phenotype of Umbra pygmaea is similar to that seen in U. krameri and in the distantly related genus Esox.
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