Giemsa C-banding of Rhoeo (Commelinaceae)

Pettenati, Mark J.

doi:10.1007/bf00056117

Cited by 9 publications

(2 citation statements)

References 31 publications

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“…It has large and non-uniform chromosomes, making it a favourable model organism for chromosome research [7]. The basic features of its karyotype, including chromosome morphology [3,7,8], and the distribution of heterochromatin [9][10][11], NORs and 5S rRNA genes [3,[12][13] have already been well characterized, and a FISH-based system for the identification of each chromosome arm has been developed [3]. The model proposed for chromosome rearrangements in R. spathacea favours breakpoints within or near prominent blocks of centromeric heterochromatin, based on the absence of interstitial heterochromatin and the overall length similarities of the chromosome arms seen conjoining during diakinesis [3].…”

Section: Introductionmentioning

confidence: 99%

Ribosomal DNA, tri- and bi-partite pericentromeres in the permanent translocation heterozygote Rhoeo spathacea

Golczyk

Hasterok

Szklarczyk

2010

Cellular and Molecular Biology Letters

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High-and low-stringency FISH and base-specific fluorescence were performed on the permanent translocation heterozygote Rhoeo spathacea (2n = 12).Our results indicate that 45S rDNA arrays, rDNA-related sequences and other GC-rich DNA fraction(s) are located within the pericentromeric regions of all twelve chromosomes, usually colocalizing with the chromomycin A 3 -positive bands. Homogenization of the pericentromeric regions appears to result from the concerted spread of GC-rich sequences, with differential amplification likely. We found new 5S rDNA patterns, which suggest a variability in the breakpoints and in the consequent chromosome reorganizations. It was found that the large 5S rDNA locus residing on each of the 8E and 9E arms consisted of two smaller loci. On each of the two chromosome arms 3b and 4b, in addition to the major subtelomeric 5S rDNA locus, a new minor locus was found interstitially about 40% along the arm length. The arrangement of cytotogenetic landmarks and chromosome arm measurements are discussed with regard to genome repatterning in Rhoeo.

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Section: Introductionmentioning

confidence: 99%

Ribosomal DNA, tri- and bi-partite pericentromeres in the permanent translocation heterozygote Rhoeo spathacea

Golczyk

Hasterok

Szklarczyk

2010

Cellular and Molecular Biology Letters

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“…1M-P). The translocation breakpoints usually tend to occur close or within heterochromatin (SCHUBERT 2007), which in both Rhoeo varieties is accumulated around centromeres (NATARAJAN and NATARA-JAN 1972;PETTENATI 1987;GOLCZYK et al 2005GOLCZYK et al , 2010. The suggested transfer of rDNA from subtelomeric to centromeric area in Rhoeo (see Introduction), could have predisposed centromeres for fi ssion as introducing instability into these regions in the past (GOLCZYK at al.…”

Section: Resultsmentioning

confidence: 99%

Cytogenetics of the permanent translocation heterozygoteRhoeo spathaceavar.variegata. Implications for complex chromosome rearrangements inRhoeo

Golczyk

2011

Caryologia

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The chromosomal morphology, arrangement of AT-and GC-rich chromatin, 5S and 45S rDNA, NORs, and centromere behaviour during somatic interphase and during meiotic prophase I were studied for the fi rst time in the variegated ring-forming Rhoeo variety-R. spathacea var. variegata. Fluorescence in situ hybridization (FISH) together with differential base-specifi c fl uorescence revealed the existence of the highly conserved karyotype in Rhoeo. It was shown that the two existing ring-forming varieties-R. spathacea variegata and R. discolor (common Rhoeo variety) share essentially the same arrangement of the studied cytogenetic landmarks within the chromosomal arms, together with the spread of the GC-rich DNA sequences (including rDNA) across all the twelve pericentromeres. They both also exhibit the same profound trend for centromere clustering in soma-and germ-line. The obtained results together with the existing literature served as a basis to summarize the cytogenetic knowledge on the karyotype structure in Rhoeo. A series of argumentations pointing to the whole-arm translocations (WATs) as the rearrangements leading to meiotic catenation in Rhoeo was presented. A possible role of ancient inversions in the evolution of the PTH system in Rhoeo was discussed.

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Spectrum of chromosomal configurations in pollen mother cells ofRhoeo spathacea(Swartz) Stearn

Kumar

Nagpal²,

Arun

2011

Caryologia

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-Rhoeo spathacea is unusual in that its twelve chromosomes are involved in complex translocations that results in atypical meiosis with all chromosomes frequently joined end-to-end into a single ring. The detailed meiotic studies, for the fi rst time, revealed that alignment of chromosomes into a ring and / or a chain begins at very early prophase I. However, the cells at diakinesis and metaphase I do not exclusively have a ring or a chain of 12 chromosomes. Instead, they carry a range of chain confi gurations formed due to slipping of the chiasmata off the pairing segments in complex structures. While in 57.61% cells, at diakinesis, a ring or a chain was observed, in the rest 2-7 chain confi gurations existed. Similarly, at metaphase I a ring of 12 chromosomes was observed in 33.87% cells whereas in 66.13 % cells 2-9 chain confi gurations existed. The various groups of chromosomes in cells at diakinesis generally did not show any specifi c orientation pattern. However, in 17.31% cells a disjunctional arrangement of chromosomes was observed. At metaphase I also while in 82.26% cells chromosomes showed more or less non disjunctional orientations, in 17.74% cells regular arrangement of chromosomes was observed. Owing to non-disjunctional arrangement of chromosomes at metaphase I, the anaphase I distribution of chromosomes was erratic in 44.18% cells. Three to nine chromosomes were seen at two poles in 33.06% cells whereas in 11.11% cells 1-8 lagging chromosomes existed. Regular distribution of 6:6 was seen in 55.82% cells. The Pollen sterility recorded was very high i.e. 81.24% using cotton blue staining procedure. It is suggested that a wide range of chromosome confi gurations, hitherto unidentifi ed, might exist in Rhoeo spathacea which awaits to be discovered.

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Giemsa C-banding of Rhoeo (Commelinaceae)

Cited by 9 publications

References 31 publications

Ribosomal DNA, tri- and bi-partite pericentromeres in the permanent translocation heterozygote Rhoeo spathacea

Ribosomal DNA, tri- and bi-partite pericentromeres in the permanent translocation heterozygote Rhoeo spathacea

Cytogenetics of the permanent translocation heterozygoteRhoeo spathaceavar.variegata. Implications for complex chromosome rearrangements inRhoeo

Spectrum of chromosomal configurations in pollen mother cells ofRhoeo spathacea(Swartz) Stearn

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