Constitutive heterochromatin DNA polymorphisms in diploid <i>Medicago sativa</i> ssp. <i>falcata</i>

Bauchan, Gary R.; Hossain, M. A.

doi:10.1139/g99-038

Cited by 12 publications

(17 citation statements)

References 9 publications

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“…Although C‐banding patterns often show a high degree of polymorphism in cross‐pollinated species (Gill, 1981; Endo and Gill, 1984; Bauchan and Hossain, 1999), all the observed bands were quite consistent in plants of PI 440215 studied here except for the telomeric band on the short arm of chromosome II. This band was absent in 10 of the 17 plants of the accession.…”

Section: Resultssupporting

confidence: 52%

Karyotype and C‐Banding Patterns of Mitotic Chromosomes in Diploid Bromegrass (Bromus riparius Rehm)

2001

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Previous cytogenetic studies of the genus Bromus L. were limited to chromosome counts and construction of karyotypes on the basis of Feulgen staining. Since the chromosomes of Bromus are similar in morphology, these karyotypes are of limited use for chromosome identification and genome analysis. The objectives of this study were to develop and evaluate a Giemsa C‐banding procedure to use in identification of individual bromegrass chromosomes and to develop a karyotype for diploid Bromus riparius Rehm. (2n = 14; PI 440215). All chromosomes had one or more C‐bands which were located mainly at telomeric regions. A group (I) of four pairs of chromosomes had telomeric bands on only one arm and could be differentiated. In this group, one pair had an interstitial C‐band along with a telomeric band, one pair had a nucleolus organizer region (NOR) at a subtelomeric location on the short arm, and the other two pair could be distinguished by centromere location. The other group (II) of three pairs of chromosomes had telomeric bands on both arms. The unequivocal identification of specific chromosomes of Group II was not possible in all cells because of their similarity and differential condensation of chromosomes. Chromosomes of both groups were either metacentric or submetacentric. The total length of individual chromosomes ranged from 5.58 to 6.87 μm and the arm ratios ranged from 1.02 to 1.5. The homologous chromosomes were paired and assigned numbers I to VII in decreasing length. A karyotype was constructed by means of the C‐bands, mean chromosome lengths, and arm ratios. The C‐banding procedure used in this study could be used to developed karyotypes for the other species of the genus Bromus and these C‐banded karyotypes could be used to compare genomes within the genus.

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Section: Resultssupporting

confidence: 52%

Karyotype and C‐Banding Patterns of Mitotic Chromosomes in Diploid Bromegrass (Bromus riparius Rehm)

2001

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“…In most cases, the chromosome pairs could not be distinguished by their C-banding pattern, the exceptions being chromosomes 1 and 4 which showed a distinct heterochromatin distribution clearly visible in metaphases stained with Giemsa and propidium iodide. A C-banded pericentromeric heterochromatin pattern with occasional intercalary and distal bands has also been found in many Leguminosae (Papilionoideae) genera, including Arachis (Cai et al, 1987), Cicer (Tayyar et al, 1994) and Medicago (Bauchan and Hossain, 1999), which have DNA C-values similar to or smaller (Bennett and Leitch, 1995) than C. juncea (1C = 1.23pg; see Gupta, 1976). Conversely, a variable distribution of heterochromatic regions has been observed in the genus Vicia, that has a considerable variation in haploid nuclear DNA content.…”

Section: Discussion Karyotype Analysis and C-banding Patternmentioning

confidence: 96%

Karyotype characterization of Crotalaria juncea (L.) by chromosome banding and physical mapping of 18S-5.8S-26S and 5S rRNA gene sites

2007

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The chromosomes of Crotalaria juncea, a legume of agronomic interest with a 2n = 16 karyotype composed of metacentric chromosomes, were analyzed using several cytogenetic techniques. C-banding revealed heterochromatic regions around the centromeres in all chromosomes and adjacent to the secondary constriction on the chromosome 1 short arm. Fluorescent staining with the GC-specific chromomycin A3 (CMA) highlighted these heterochromatic regions and a tiny site on the chromosome 1 long arm while the AT-specific stain 4'-6-diamidino-2-phenylindole (DAPI) induced a reversed pattern. Staining with CMA combined with AT-specific distamycin A (DA) counterstaining quenched the pericentromeric regions of all chromosomes, but enhanced fluorescence was observed at the heterochromatic regions around the secondary constriction and on the long arms of chromosomes 1 and 4. Fluorescence in situ hybridization (FISH) revealed 18S-5.8S-26S rRNA gene sites (45S rDNA) on chromosomes 1 and 4, and one 5S rDNA locus on chromosome 1. All the rDNA sites were co-located with the positive-CMA/DA bands, suggesting they were very rich in GC. Silver staining revealed signals at the main 45S rDNA locus on chromosome 1 and, in some cells, chromosome 4 was labeled. Two small nucleoli were detected in a few interphase cells, suggesting that the minor site on chromosome 4 could be active at some stages of the cell cycle.

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“…Satellite DNA, the main constituent of this genomic fraction, usually occurs in the centromeric region of chromosomes (Chaves et al , 2000), but is also frequently found at telomeres (Shore, 2001). The occurrence of CH at interstitial positions is much less common, although large blocks of interstitial CH have been found in the large chromosomes of some insects (John et al , 1985), plants (Bauchan and Hossain, 1999) and some mammals (Santos et al , 2004; Adega et al , 2007; Meles et al , 2008). …”

Section: Introductionmentioning

confidence: 99%

Hidden heterochromatin: characterization in the Rodentia species Cricetus cricetus, Peromyscus eremicus (Cricetidae) and Praomys tullbergi (Muridae)

et al. 2009

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The use of in situ restriction endonuclease (RE) (which cleaves DNA at specific sequences) digestion has proven to be a useful technique in improving the dissection of constitutive heterochromatin (CH), and in the understanding of the CH evolution in different genomes. In the present work we describe in detail the CH of the three Rodentia species, Cricetus cricetus, Peromyscus eremicus (family Cricetidae) and Praomys tullbergi (family Muridae) using a panel of seven REs followed by C-banding. Comparison of the amount, distribution and molecular nature of C-positive heterochromatin revealed molecular heterogeneity in the heterochromatin of the three species. The large number of subclasses of CH identified in Praomys tullbergi chromosomes indicated that the karyotype of this species is the more derived when compared with the other two genomes analyzed, probably originated by a great number of complex chromosomal rearrangements. The high level of sequence heterogeneity identified in the CH of the three genomes suggests the coexistence of different satellite DNA families, or variants of these families in these genomes.

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Constitutive heterochromatin DNA polymorphisms in diploid Medicago sativa ssp. falcata

Cited by 12 publications

References 9 publications

Karyotype and C‐Banding Patterns of Mitotic Chromosomes in Diploid Bromegrass (Bromus riparius Rehm)

Karyotype and C‐Banding Patterns of Mitotic Chromosomes in Diploid Bromegrass (Bromus riparius Rehm)

Karyotype characterization of Crotalaria juncea (L.) by chromosome banding and physical mapping of 18S-5.8S-26S and 5S rRNA gene sites

Hidden heterochromatin: characterization in the Rodentia species Cricetus cricetus, Peromyscus eremicus (Cricetidae) and Praomys tullbergi (Muridae)

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