Molecular Cytogenetic Organization of 5S and 18S-26S rDNA Loci in White Clover (Trifolium repensL.) and Related Species

Ansari, H. A.; Ellison, Nicholas W.; Reader, S. M.; Бадаева, Е. Д.; Friebe, Bernd; Miller, Terry E.; Williams, W. M.

doi:10.1006/anbo.1998.0806

Cited by 86 publications

(115 citation statements)

References 27 publications

Supporting

Mentioning

101

Contrasting

Unclassified

Order By: Relevance

“…In theory, polyploidy results in multiplying the number of rDNA sites compared with the diploid ancestors; however, in some species the number of rDNA sites detected is different from that expected based on ploidy level (Adachi et al 1997;Ansari et al 1999;Raina and Mukai 1999). In our study, the tetraploid species, C. sp, C. spp, and C. heptadactylus have duplicated rDNA site numbers as expected compared with the diploid species.…”

Section: Discussionsupporting

confidence: 39%

Comparative chromosomal localization of 45S and 5S rDNAs and implications for genome evolution inCucumis

Zhang

Yang

et al. 2016

Genome

View full text Add to dashboard Cite

Ribosomal DNAs are useful cytogenetic markers for chromosome analysis. Studies investigating site numbers and distributions of rDNAs have provided important information for elucidating genome organization and chromosomal relationships of many species by fluorescence in situ hybridization. But relevant studies are scarce for species of the genus Cucumis, especially in wild species. In the present study, FISH was conducted to investigate the organization of 45S and 5S rDNA among 20 Cucumis accessions, including cultivars and wild accessions. Our results showed that the number of 45S rDNA sites varied from one to five pairs in different accessions, and most of these sites are located at the terminal regions of chromosomes. Interestingly, up to five pairs of 45S rDNA sites were observed in C. sativus var. sativus, the species which has the lowest chromosome number, i.e., 2n = 14. Only one pair of 5S rDNA sites was detected in all accessions, except for C. heptadactylus, C. sp, and C. spp that had two pairs of 5S rDNA sites. The distributions of 5S rDNA sites showed more variation than 45S rDNA sites. The phylogenetic analysis in this study showed that 45S and 5S rDNA have contrasting evolutionary patterns. We find that 5S rDNA has a polyploidizationrelated tendency towards the terminal location from an interstitial location but maintains a conserved site number, whereas the 45S rDNA showed a trend of increasing site number but a relatively conserved location.

show abstract

Section: Discussionsupporting

confidence: 39%

Comparative chromosomal localization of 45S and 5S rDNAs and implications for genome evolution inCucumis

Zhang

Yang

et al. 2016

Genome

View full text Add to dashboard Cite

show abstract

“…Schmid and Guttenbach (1988) obtained positive mithramycin A staining of vertebrate nucleolus organizer region (NOR) in various species except humans, the authors attributing this exception to the low repeat number (40-46 repeats per locus) of human NORs. In Maxillaria, the rDNA site heteromorphism observed in three of the four species investigated may also be caused by differences in the number of rDNA repeats in some loci, as observed in Arabidopsis (Murata et al, 1997) and Trifolium (Ansari et al, 1999).…”

Section: Discussionmentioning

confidence: 89%

Heterochromatin diversity and its co-localization with 5S and 45S rDNA sites in chromosomes of four Maxillaria species (Orchidaceae)

2006

View full text Add to dashboard Cite

We investigated four orchids of the genus Maxillaria (M. discolor, M. acicularis, M. notylioglossa and M. desvauxiana) in regard to the position of heterochromatin blocks as revealed using chromomycin A 3 (CMA) and 4'-6-diamidino-2-phenylindole (DAPI) fluorochrome staining and 5S and 45S rDNA sites using fluorescence in situ hybridization (FISH). The species showed differences in chromosome number and a diversified pattern of CMA + and DAPI + bands, including heteromorphism for CMA + bands. The 5S and 45S rDNA sites also varied in number and most of them were co-localized with CMA + bands. The relationship between 5S rDNA sites and CMA + bands was more evident in M. notylioglossa, in which the brighter CMA + bands were associated with large 5S rDNA sites. However, not all 5S and 45S rDNA sites were co-localized with CMA + bands, probably due to technical constraints. We compare these results to banding data from other species and suggest that not all blocks of tandemly repetitive sequences, such as 5S rDNA sites, can be observed as heterochromatin blocks.

show abstract

“…These genes occur as a large number of tandem repeats of single transcription units (45s rDNA). These sequences are predominantly located in the NOR of eukaryotic chromosomes (Ansari et al 1999). Moreover, the digital image analysis system allowed the assembly of a density profile 3D plot of the chromosome 1 that highlighted the fluorescence signals (Fig.…”

Section: Discussionmentioning

confidence: 99%

Classical and Molecular Cytogenetic Tools to Resolve the Bixa Karyotypes

Almeida

Carvalho

2006

CYTOLOGIA

View full text Add to dashboard Cite

SummaryThe cytogenetic studies performed in Bixa orellana have reported 2nϭ14 or 2nϭ16 chromosomes with little karyotypic information. In this context, an improved cytogenetic protocol using enzymatic maceration of meristematic cellular walls and digital image analysis was applied to B. orellana and B. arborea. In B. arborea, the high-resolution technique, Ag-NOR and C banding methods, and FISH using a probe of 45S rDNA genes, were also performed. Prometaphasic and standard C-metaphasic chromosomes presented well-defined primary and secondary constrictions facilitated the pairing of homologues and assembly of the karyogram for the 2 species. These species showed similar karyotypes with 2nϭ14 chromosomes, being composed of 5 metacentric pairs (1, 2, 3, 4 and 6) and 2 submetacentric pairs (5 and 7). The chromosome 1 is approximately 2 times as long as the others and possesses the secondary constriction adjacent to the centromere, which suggests that Robertsonian translocation between 2 smaller chromosomes may have occurred during the karyotype evolution of Bixa. Additionally, the active NOR, the NOR-adjacent heterochromatic region and 18S, 5.8S and 26S rDNA genes were identified in the secondary constriction of chromosome 1.

show abstract

Molecular Cytogenetic Organization of 5S and 18S-26S rDNA Loci in White Clover (Trifolium repensL.) and Related Species

Cited by 86 publications

References 27 publications

Comparative chromosomal localization of 45S and 5S rDNAs and implications for genome evolution inCucumis

Comparative chromosomal localization of 45S and 5S rDNAs and implications for genome evolution inCucumis

Heterochromatin diversity and its co-localization with 5S and 45S rDNA sites in chromosomes of four Maxillaria species (Orchidaceae)

Classical and Molecular Cytogenetic Tools to Resolve the Bixa Karyotypes

Contact Info

Product

Resources

About