Nucleolus Organising Chromosomes in &lt;i&gt;Brassica&lt;/i&gt; and Their Bearing on the Phylogeny of the Genus

Kamala, T.

doi:10.1508/cytologia.41.615

Cited by 7 publications

(2 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, it can be concluded that two pairs of chromosomes are involved in the formation of nucleoli in B. afboglabra. This is in agreement with the observation of two bivalents associated with nucleoli at meiosis in B. oleracea (ROBBELEN 1960;KAMALA 1976). The possible prevalence of heteromorphism regarding the number of copies of rRNA genes (Fig.…”

Section: Silver-stained Nors and Nucleolisupporting

confidence: 92%

“…Bailey is a form of B. oleracea L. (genome: CC, 2n = 18), cultivated as an important vegetable crop in south China. It has been reported that two pairs of chromosomes are associated with nucleoli at pachytene of male meiosis in B. oleracea (ROBBELEN 1960;KAMALA 1976). However, mitotic analyses have revealed only one pair of chromosomes exhibiting secondary constrictions and satellites in B. alboglabra (WANG et al 1989; and in other forms of B. oleracea (SIKKA 1940;WANG et al 1989;OLIN-FATIH and HENEEN 1992).…”

Section: Brassica Alboglabramentioning

confidence: 99%

See 1 more Smart Citation

Ribosomal RNA Gene Loci and Their Nucleolar Activity in Brassica alboglabra Bailey

Cheng

Heneen

Pedersen³

2004

Hereditas

View full text Add to dashboard Cite

Fluorescence in situ hybridization (FISH) and silver staining techniques were used to reveal the number, chromosomal sites and nucleolar activity of ribosomal RNA (rRNA) gene loci in Brassica alboglabra Bailey (genome: CC, 2n = 18). Two major and two minor rRNA gene loci were disclosed using FISH. The two major rRNA gene loci were located on the secondary constrictions of the satellited chromosome pair 9, the two minor rRNA gene loci, on the terminal region of the short arms of the non‐satellited chromosome pair 8. Two silver‐stained nucleolus organizer regions (Ag‐NORs) were detected on the secondary constrictions of chromosome pair 9. Two major nucleoli were recorded in telophase nuclei. In interphase nuclei, two micronucleoli were observed in addition to the two major nuceoli. Thus, it is suggested that the satellited chromosome pair 9 with Ag‐NORs contains major active rRNA gene loci leading to the formation of major nucleoli, while the non‐satellited chromosome pair 8 without detectable Ag‐NORs carries minor active rRNA gene loci responsible for the formation of micronucleoli.

show abstract

Section: Silver-stained Nors and Nucleolisupporting

confidence: 92%

Section: Brassica Alboglabramentioning

confidence: 99%

Ribosomal RNA Gene Loci and Their Nucleolar Activity in Brassica alboglabra Bailey

Cheng

Heneen

Pedersen³

2004

Hereditas

View full text Add to dashboard Cite

show abstract

Brassicaand Its Close Allies: Cytogenetics and Evolution

Prakash

Bhat

Quirós

et al. 2009

Plant Breeding Reviews

107

View full text Add to dashboard Cite

Nucleolar organizing chromosomes ofRicinus

Paris

Shifriss

Jelenković

1980

Theoret. Appl. Genetics

View full text Add to dashboard Cite

Pachytene chromosome morphology was compared in nine races ofRicinus communis L. (2n = 20), using pollen mother cells (PMCs) and light microscopy. Of the ten bivalents, only the two possessing nucleolar organizing regions (NORs), chromosomes 2 and 7, exhibit structural variations among the races. The NORs are located in the short arms of these two chromosomes. Most of the observed structural variations affect these short arms, which are similar morphologically and consist largely of heterochromatic segments. The PMCs contain a single nucleolus and this is associated with the NOR of each of the two chromosomes at a particular frequency in each race. In eight races, a nucleolar constriction (NC) is present in either chromosome 2 or chromosome 7. In these races, the nucleolus is associated with the chromosome possessing an NC at a frequency of 100% and with the chromosome lacking an NC at a frequency ranging between 5.6 and 100%, depending upon the race. No microscopically visible NC is present in the ninth race. In this race, the nucleolus is associated with both chromosomes 2 and 7 at a frequency of 100%. The association of the nucleolus with a chromosome possessing an NC is at the NC and with a chromosome lacking an NC is at the terminal heterochromatic segment of the short arm. Several interpretations are offered to account for the variations in frequency of association between the nucleolus and each of the nucleolar organizing chromosomes. It is suggested that the two non-linked NORs have evolved through some intragenomic changes rather than polyploidy, that this species is highly intolerant to structural variations other than those occurring in or near the NORs, and that structural variations in the nucleolar organizing chromosomes are not associated with racial variations in plant phenotype.

show abstract

Nucleolus Organising Chromosomes in <i>Brassica</i> and Their Bearing on the Phylogeny of the Genus

Cited by 7 publications

References 7 publications

Ribosomal RNA Gene Loci and Their Nucleolar Activity in Brassica alboglabra Bailey

Ribosomal RNA Gene Loci and Their Nucleolar Activity in Brassica alboglabra Bailey

Brassicaand Its Close Allies: Cytogenetics and Evolution

Nucleolar organizing chromosomes ofRicinus

Contact Info

Product

Resources

About