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Karyotype analysis and report on B-chromosome in Gloriosa superba L. by differential staining. THE NUCLEUS 2019. [DOI: 10.1007/s13237-018-0259-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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2
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Acosta MC, Moscone EA, Cocucci AA. Using chromosomal data in the phylogenetic and molecular dating framework: karyotype evolution and diversification in Nierembergia (Solanaceae) influenced by historical changes in sea level. PLANT BIOLOGY (STUTTGART, GERMANY) 2016; 18:514-526. [PMID: 26718314 DOI: 10.1111/plb.12430] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 12/22/2015] [Indexed: 06/05/2023]
Abstract
Karyotype data within a phylogenetic framework and molecular dating were used to examine chromosome evolution in Nierembergia and to infer how geological or climatic processes have influenced in the diversification of this solanaceous genus native to South America and Mexico. Despite the numerous studies comparing karyotype features across species, including the use of molecular phylogenies, to date relatively few studies have used formal comparative methods to elucidate chromosomal evolution, especially to reconstruct the whole ancestral karyotypes. Here, we mapped on the Nierembergia phylogeny one complete set of chromosomal data obtained by conventional staining, AgNOR-, C- and fluorescent chromosome banding, and fluorescent in situ hybridisation. In addition, we used a Bayesian molecular relaxed clock to estimate divergence times between species. Nierembergia showed two major divergent clades: a mountainous species group with symmetrical karyotypes, large chromosomes, only one nucleolar organising region (NOR) and without centromeric heterochromatin, and a lowland species group with asymmetrical karyotypes, small chromosomes, two chromosomes pairs with NORs and centromeric heterochromatin bands. Molecular dating on the DNA phylogeny revealed that both groups diverged during Late Miocene, when Atlantic marine ingressions, called the 'Paranense Sea', probably forced the ancestors of these species to find refuge in unflooded areas for about 2 Myr. This split agrees with an increased asymmetry and heterochromatin amount, and decrease in karyotype length and chromosome size. Thus, when the two Nierembergia ancestral lineages were isolated, major divergences occurred in chromosomal evolution, and then each lineage underwent speciation separately, with relatively minor changes in chromosomal characteristics.
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Affiliation(s)
- M C Acosta
- Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
| | - E A Moscone
- Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
| | - A A Cocucci
- Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina
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Grabowska-Joachimiak A, Kula A, Gernand-Kliefoth D, Joachimiak AJ. Karyotype structure and chromosome fragility in the grass Phleum echinatum Host. PROTOPLASMA 2015; 252:301-6. [PMID: 25056831 PMCID: PMC4287660 DOI: 10.1007/s00709-014-0681-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 07/14/2014] [Indexed: 05/11/2023]
Abstract
Phleum echinatum Host (2n = 2x = 10) is an annual Mediterranean species which differs from other representatives of the genus Phleum by reduced chromosome number, asymmetric karyotype and unusually high amount of DNA in the genome. Chromosomes of this plant were studied using conventional acetic-orcein staining and fluorescence in situ hybridization (FISH). FISH showed the major 35S ribosomal DNA (rDNA) site at the secondary constriction of satellite chromosome (3) and the minor 35S rDNA site near 5S rDNA cluster in the monobrachial chromosome 5. Telomeric repeats were detected at all chromosome ends within secondary constriction in satellited chromosome 3 and at the centromeric regions of chromosomes 1 and 2. Intrachromosomally located telomeric repeats are probably traces of chromosomal rearrangements that have shaped P.echinatum genome; they were prone to breakage which was manifested in chromosome fragmentation. The most distinct telomeric signals, suggesting massive amplification of interstitial telomeric sequences (ITRs), were observed at the nucleolar organizer region (NOR) of the third chromosome pair. Double FISH confirmed co-localization of telomeric and 35S rDNA repeats in this locus characterized by the biggest fragility in the karyotype. Fragile sites of P.echinatum, composed of amplified telomeric repeats, may bear a resemblance to metazoan rare fragile sites enriched in microsatellite repeats.
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Ruffini Castiglione M, Gelati MT, Cremonini R, Frediani M. The intergenic spacer region of the rDNA in Haplopappus gracilis (Nutt.) Gray. PROTOPLASMA 2013; 250:683-689. [PMID: 22948831 DOI: 10.1007/s00709-012-0441-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 07/24/2012] [Indexed: 06/01/2023]
Abstract
In this paper, we provide further information on the genome organisation of Haplopappus gracilis, one of the six angiosperms showing the lowest chromosome number, i.e. 2n = 4, by determining the nucleotide sequence of the intergenic spacer region of the ribosomal RNA genes and its cytological localization on metaphase chromosomes. DNA sequence analysis reveals the occurring of a product of 4,382 bp in length, characterised by the presence of four blocks of different repeated sequences. Our analysis also evidenced putative promoter regions with three transcription initiation sites for polymerase I, as previously reported in Artemisia absinthium, belonging to the same Asteraceae family. A fluorescent in situ hybridization with the intergenic spacer probe indicates the presence of rDNA genes only in the satellited chromosomes of H. gracilis; besides, differences in the signal intensity between homologous chromosomes were frequently observed, thus suggesting for these chromosome sites the presence of a variable number of rDNA gene copies, even if a divergent chromatin organisation in corresponding regions cannot be ruled out.
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MESH Headings
- Base Sequence
- Chromosome Mapping
- Chromosomes, Plant
- DNA, Ribosomal Spacer/genetics
- Genes, Plant
- Haplopappus/genetics
- Molecular Sequence Annotation
- Molecular Sequence Data
- Promoter Regions, Genetic
- RNA, Ribosomal/genetics
- RNA, Ribosomal, 18S/genetics
- RNA, Ribosomal, 5.8S/genetics
- Sequence Analysis, DNA
- Transcription Initiation Site
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Agulló-Antón MÁ, Olmos E, Pérez-Pérez JM, Acosta M. Evaluation of ploidy level and endoreduplication in carnation (Dianthus spp.). PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2013; 201-202:1-11. [PMID: 23352398 DOI: 10.1016/j.plantsci.2012.11.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 10/26/2012] [Accepted: 11/19/2012] [Indexed: 05/12/2023]
Abstract
Carnation (Dianthus caryophyllus L.) is one of the fifth most important ornamental species worldwide. Many desirable plant characteristics, such as big size, adaptation under stress, and intra or interspecific hybridization capability, are dependent on plant ploidy level. We optimized a quick flow cytometry method for DNA content determination in wild and cultivated carnation samples that allowed a systematic evaluation of ploidy levels in Dianthus species. The DNA content of different carnation cultivars and wild Dianthus species was determined using internal reference standards. The precise characterization of ploidy, endoreduplication and C-value of D. caryophyllus 'Master' makes it a suitable standard cultivar for ploidy level determination in other carnation cultivars. Mixoploidy was rigorously characterized in different regions of several organs from D. caryophyllus 'Master', which combined with a detailed morphological description suggested some distinctive developmental traits of this species. Both the number of endoreduplication cycles and the proportion of endopolyploid cells were highly variable in the petals among the cultivars studied, differently to the values found in leaves. Our results suggest a positive correlation between ploidy, cell size and petal size in cultivated carnation, which should be considered in breeding programs aimed to obtain new varieties with large flowers.
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Schallau A, Arzenton F, Johnston AJ, Hähnel U, Koszegi D, Blattner FR, Altschmied L, Haberer G, Barcaccia G, Bäumlein H. Identification and genetic analysis of the APOSPORY locus in Hypericum perforatum L. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 62:773-84. [PMID: 20202173 DOI: 10.1111/j.1365-313x.2010.04188.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The introduction of apomixis - seed formation without fertilization - into crop plants is a long-held goal of breeding research, since it would allow for the ready fixation of heterozygosity. The genetic basis of apomixis, whether of the aposporous or the diplosporous type, is still only poorly understood. Hypericum perforatum (St John's wort), a plant with a small genome and a short generation time, can be aposporous and/or parthenogenetic, and so represents an interesting model dicot for apomixis research. Here we describe a genetic analysis which first defined and then isolated a locus (designated HAPPY for Hypericum APOSPORY) associated with apospory. Amplified fragment length polymorphism (AFLP) profiling was used to generate a cleaved amplified polymorphic sequence (CAPS) marker for HAPPY which co-segregated with apospory but not with parthenogenesis, showing that these two components of apomixis are independently controlled. Apospory was inherited as a dominant simplex gene at the tetraploid level. Part of the HAPPY sequence is homologous to the Arabidopsis thaliana gene ARI7 encoding the ring finger protein ARIADNE7. This protein is predicted to be involved in various regulatory processes, including ubiquitin-mediated protein degradation. While the aposporous and sexual alleles of the HAPPY component HpARI were co-expressed in many parts of the plant, the gene product of the apomict's allele is truncated. Cloning HpARI represents the first step towards the full characterization of HAPPY and the elucidation of the molecular mechanisms underlying apomixis in H. perforatum.
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Affiliation(s)
- Anna Schallau
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466 Gatersleben, Germany
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7
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Barros e Silva AE, Guerra M. The meaning of DAPI bands observed after C-banding and FISH procedures. Biotech Histochem 2010. [DOI: 10.3109/10520290903149596] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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8
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Dantas LG, Guerra M. Chromatin differentiation between Theobroma cacao L. and T. grandiflorum Schum. Genet Mol Biol 2010; 33:94-8. [PMID: 21637611 PMCID: PMC3036076 DOI: 10.1590/s1415-47572009005000103] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 07/16/2009] [Indexed: 11/29/2022] Open
Abstract
A comparative analysis of mitotic chromosomes of Theobroma cacao (cacao) and T. grandiflorum (cupuaçu) was performed aiming to identify cytological differences between the two most important species of this genus. Both species have symmetric karyotypes, with 2n = 20 metacentric chromosomes ranging in size from 2.00 to 1.19 μm (cacao) and from 2.21 to 1.15 μm (cupuaçu). The interphase nuclei of both species were of the arreticulate type, displaying up to 20 chromocentres, which were more regularly shaped in cacao than in cupuaçu. Prophase chromosomes of both species were more condensed in the proximal region, sometimes including the whole short arm. Both species exhibited only one pair of terminal heterochromatic bands, positively stained with chromomycin A 3 , which co-localized with the single 45S rDNA site. Each karyotype displayed a single 5S rDNA site in the proximal region of another chromosome pair. Heterochromatic bands were also observed on the centromeric/pericentromeric regions of all 20 chromosomes of cacao after C-banding followed by Giemsa or DAPI staining, whereas in cupuaçu they were never detected. These data suggest that the chromosomes of both species have been largely conserved and their pericentromeric chromatin is the only citologically differentiated region.
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Affiliation(s)
- Liliane G Dantas
- Laboratório de Citogenética Vegetal, Departamento de Botânica, Universidade Federal de Pernambuco, Pernambuco, Recife Brazil
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Kim ES, Bolsheva NL, Samatadze TE, Nosov NN, Nosova IV, Zelenin AV, Punina EO, Muravenko OV, Rodionov AV. The unique genome of two-chromosome grasses Zingeria and Colpodium, its origin, and evolution. RUSS J GENET+ 2009. [DOI: 10.1134/s1022795409110076] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Castiglione MR, Kotseruba V, Cremonini R. Methylated-rich regions and tandem repeat arrays along the chromosome complement of Colpodium versicolor (Stev.) Schmalh. PROTOPLASMA 2009; 237:13-18. [PMID: 19621206 DOI: 10.1007/s00709-009-0063-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Accepted: 07/02/2009] [Indexed: 05/26/2023]
Abstract
The grass Colpodium versicolor (Stev.) Schmalh is one of six angiosperms with extremely reduced chromosome set 2n = 2x = 4. The chromosome complement of this species was studied. The DNA methylation pattern was determined with a specific monoclonal antiboby. 5-Methylcytosine residues are present in different chromosomal sites, with specific occurrence, some methylated bands showing differences between homologous chromosomes. Moreover, a fluorescent in situ hybridisation with telomere repeats and 45S rDNA sequences were performed. Hybridisation signals of telomeric repeats are detectable at the distal ends of the two pair of chromosomes, while 45S rDNA is localised in one chromosomal site, corresponding to the secondary constriction. In addition, 45S rDNA, as well as telomere-associated sequences, results to be 5-methylcytosine-enriched. The results are discussed and compared with those previously obtained in other plant systems 2n = 4 with the aim to enable a better knowledge of the lengthwise differentiation of this chromosome complement.
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11
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Matoba H, Nagano K, Hoshi Y. The Tendency of Chromosomal Evolution in Some Japanese Artemisia using Numerical Analysis of Karyotypes. CYTOLOGIA 2007. [DOI: 10.1508/cytologia.72.181] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Hideyuki Matoba
- Department of Applied Biological Science, College of Bioresource Sciences, Nihon University
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12
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Kotseruba V, Gernand D, Meister A, Houben A. Uniparental loss of ribosomal DNA in the allotetraploid grass Zingeria trichopoda (2n = 8). Genome 2003; 46:156-63. [PMID: 12669808 DOI: 10.1139/g02-104] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Analysis of the grass Zingeria trichopoda (2n = 8, 2C = 5.3 pg) revealed a dynamic evolution with the following characteristics. (i) Genomic in situ hybridization (GISH) demonstrates that Z. trichopoda evolved from an interspecific hybrid involving a species like contemporary Zingeria biebersteiniana (2n = 4) and a second species with a similar low number of chromosomes. The nucleus of Z. trichopoda is spatially organized at the genome level and the two parental genomes occupy distinct and separate domains of lateral arrangements. (ii) The copy number of the Z. biebersteiniana specific pericentromeric tandem repeat family Zbcen1 is drastically reduced in Z. trichopoda. (iii) GISH in combination with labeled rDNA sequences simultaneously discriminated the two parental genomes and the corresponding 5S and 45S rDNA sites. Hence, following allopolyploidization of Z. trichopoda the Z. biebersteiniana like parental chromosomes probably underwent drastic loss of 45S rDNA. This could have arisen either through the loss of Z. biebersteiniana derived 45S rDNA or through Z. trichopoda genome-wide homogenization of Z. biebersteiniana type 45S rDNA and subsequent elimination of 45S rDNA loci from Z. biebersteiniana derived chromosomes. Finally, 5S rDNA loci are present in both subgenomes of Z. trichopoda and the chromosomal position of these loci is similar for both Z. biebersteiniana and the Z. biebersteiniana like parental genome of Z. trichopoda.
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Affiliation(s)
- Violetta Kotseruba
- Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Gatersleben, Germany
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13
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Saunders VA, Houben A. The pericentromeric heterochromatin of the grass Zingeria biebersteiniana (2n = 4) is composed of Zbcen1-type tandem repeats that are intermingled with accumulated dispersedly organized sequences. Genome 2001; 44:955-61. [PMID: 11768222 DOI: 10.1139/g01-092] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
DNA reassociation and hydroxyapatite chromatography were used to isolate high-copy DNA of the grass Zingeria biebersteiniana (2n = 4). In situ hybridization demonstrated that the DNA isolated was enriched for pericentromere-specific repetitive sequences. One abundant pericentromere-specific component is the differentially methylated tandem-repeat family Zbcen1. Other sequences isolated, Zb46 and Zb47A, are dispersed and display similarity to parts of the gypsy- and copia-like retrotransposable elements of other grasses. In situ hybridization with the copia-like sequence Zb47A resulted in dispersed labelling along the chromosome arms, with a significant signal accumulation in the pericentromeric region of all chromosomes. It is concluded that the pericentromeric heterochromatin of Z. biebersteiniana is composed of members of the Zbcen1 tandem repeat family and that these tandem arrays are intermingled with accumulated putative copia-like retrotransposon sequences. An observed Rab1 interphase orientation suggests that the length of the chromosomes rather than the genome size is the determining factor of the Rab1 phenomenon.
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Affiliation(s)
- V A Saunders
- Molecular Biosciences (Genetics), Adelaide University, SA, Australia
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15
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Abstract
Grasses are the single most important plant family in agriculture. In the past years, comparative genetic mapping has revealed conserved gene order (colinearity) among many grass species. Recently, the first studies at gene level have demonstrated that microcolinearity of genes is less conserved: small scale rearrangements and deletions complicate the microcolinearity between closely related species, such as sorghum and maize, but also between rice and other crop plants. In spite of these problems, rice remains the model plant for grasses as there is limited useful colinearity between Arabidopsis and grasses. However, studies in rice have to be complemented by more intensive genetic work on grass species with large genomes (maize, Triticeae). Gene-rich chromosomal regions in species with large genomes, such as wheat, have a high gene density and are ideal targets for partial genome sequencing.
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Affiliation(s)
- B Keller
- Dept of Plant Molecular Biology, University of Zürich, Switzerland.
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Abstract
Plants are the basis of life on earth. We cannot overemphasize their importance. The value of plant genome initiatives is self-evident. The need is to identify priorities for action. The angiosperm genome is highly variable, but the extent of this variability is unknown. Uncertainties remain about the number of genes and the number of species living. Many plants will become extinct before they are discovered. We risk losing both genes and vital information about plant uses. There are also major gaps in our karyotypic knowledge. No chromosome count exists for >70% of angiosperm species. DNA C values are known for only approximately 1% of angiosperms, a sample unrepresentative of the global flora. Researchers reported new relationships between genome size and characters of major interest for plant breeding and the environment and the need for more data. In 1997, a Royal Botanic Gardens Kew workshop identified gaps and planned international collaboration to fill them. An electronic version of the Angiosperm DNA C value database also was published. Another initiative, which will make a very significant contribution to the conservation of plant genetic diversity on a global scale is Kew's Millennium Seed Bank, partly funded by the U.K. Millennium Commission, celebrating the year 2000. Costing up to 80 million (1 = $1.62), its main aims are to collect and conserve the seed of almost all of the U.K. spermatophyte flora by the year 2000, to collect and conserve a further 10% of the world spermatophyte flora principally from the drylands by 2009, and to provide a world class building as the focus of this activity by 2000.
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Affiliation(s)
- M D Bennett
- Jodrell Laboratory, Royal Botanic Gardens Kew, Richmond, Surrey TW9 3DS, United Kingdom
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Kamstra SA, Kuipers AG, De Jeu MJ, Ramanna MS, Jacobsen E. Physical localisation of repetitive DNA sequences in Alstroemeria: karyotyping of two species with species-specific and ribosomal DNA. Genome 1997; 40:652-8. [PMID: 9352644 DOI: 10.1139/g97-086] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Fluorescence in situ hybridization (FISH) was used to localise two species-specific repetitive DNA sequences, A001-I and D32-13, and two highly conserved 25S and 5S rDNA sequences on the metaphase chromosomes of two species of Alstroemeria. The Chilean species, Alstroemeria aurea (2n = 16), has abundant constitutive heterochromatin, whereas the Brazilian species, Alstroemeria inodora, has hardly any heterochromatin. The A. aurea specific A001-I probe hybridized specifically to the C-band regions on all chromosomes. The FISH patterns on A. inodora chromosomes using species-specific probe D32-13 resembled the C-banding pattern and the A001-I pattern on A. aurea chromosomes. There were notable differences in number and distribution of rDNA sites between the two species. The 25S rDNA probe revealed 16 sites in A. aurea that closely colocalised with A001-I sites and 12 in A. inodora that were predominantly detected in the centromeric regions. FISH karyotypes of the two Alstroemeria species were constructed accordingly, enabling full identification of all individual chromosomes. These FISH karyotypes will be useful for monitoring the chromosomes of both Alstroemeria species in hybrids and backcross derivatives.
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Affiliation(s)
- S A Kamstra
- Department of Plant Breeding, Graduate School of Experimental Plant Sciences, Wageningen Agricultural University, The Netherlands. -
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Houben A, Belyaev ND, Leach CR, Timmis JN. Differences of histone H4 acetylation and replication timing between A and B chromosomes of brachycome dichromosomatica. Chromosome Res 1997; 5:233-7. [PMID: 9244450 DOI: 10.1023/b:chro.0000032297.10876.86] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Differences are demonstrated between A (transcriptionally active) and B (transcriptionally inactive) chromosomes that are characterized by a different level of histone H4 acetylation and a different timing of DNA replication. These differences between the chromatin of A and B chromosomes were found after immunolabelling of chromsomes of Brachycome dichromosomatica with antibodies specific for different acetylated forms (lysine 5, 8, 12 and 16) of histone H4. In contrast to the A chromosomes, which are labelled brightly in their entirety, the transcriptionally inactive B chromosomes are faintly labelled with antibodies against H4Ac5 and H4Ac8. No such difference between the chromosomes is found after immunostaining with the other antibodies H4Ac12 and H4Ac16. Analysis of DNA replication timing in root-tip meristems suggests that B chromosomes are labelled late in S-phase compared with A chromosomes. After C-banding the B chromosome appeared to have a similar amount of heterochromatin to the A chromosomes.
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Affiliation(s)
- A Houben
- Department of Genetics, The University of Adelaide, Australia.
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