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Kus A, Szymanowska-Pułka J, Kwasniewska J, Hasterok R. Detecting Brachypodium distachyon Chromosomes Bd4 and Bd5 in MH- and X-Ray-Induced Micronuclei Using mcFISH. Int J Mol Sci 2019; 20:ijms20112848. [PMID: 31212692 PMCID: PMC6612364 DOI: 10.3390/ijms20112848] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 05/22/2019] [Accepted: 06/08/2019] [Indexed: 12/18/2022] Open
Abstract
Micronuclei are biomarkers of genotoxic effects and chromosomal instability. They are formed when chromosome fragments or whole chromosomes fail to disjoin into daughter nuclei. We present qualitative and quantitative analyses of the involvement of specific chromosome regions of chromosomes Bd4 and Bd5 in the formation of micronuclei of Brachypodium distachyon root tip cells following maleic hydrazide (MH) treatment and X-radiation. This is visualised by cytomolecular approaches using bacterial artificial chromosome (BAC)-based multicolour fluorescence in situ hybridisation (mcFISH) in combination with 5S and 25S rDNA probes. The results showed that the long arm of submetacentric chromosome Bd4 forms micronuclei at twice the frequency of its short arm, suggesting that the former is more prone to double-strand breaks (DSBs). In contrast, no difference was observed in the frequency of micronuclei derived from the long and short arms of submetacentric chromosome Bd5. Interestingly, the proximal region of the short arm of Bd5 is more prone to DSBs than its distal part. This demonstrates that 5S rDNA and 35S rDNA loci are not "hot spots" for DNA breaks after the application of these mutagens.
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Affiliation(s)
- Arita Kus
- Department of Plant Anatomy and Cytology, Faculty of Biology and Environmental Protection, University of Silesia in Katowice, 28 Jagiellonska Street, 40-032 Katowice, Poland.
| | - Joanna Szymanowska-Pułka
- Department of Biophysics and Morphogenesis of Plants, Faculty of Biology and Environmental Protection, University of Silesia in Katowice, 28 Jagiellonska Street, 40-032 Katowice, Poland.
| | - Jolanta Kwasniewska
- Department of Plant Anatomy and Cytology, Faculty of Biology and Environmental Protection, University of Silesia in Katowice, 28 Jagiellonska Street, 40-032 Katowice, Poland.
| | - Robert Hasterok
- Department of Plant Anatomy and Cytology, Faculty of Biology and Environmental Protection, University of Silesia in Katowice, 28 Jagiellonska Street, 40-032 Katowice, Poland.
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Rocha LC, Ferreira MTM, Cunha IMF, Mittelmann A, Techio VH. 45S rDNA sites in meiosis of Lolium multiflorum Lam.: variability, non-homologous associations and lack of fragility. PROTOPLASMA 2019; 256:227-235. [PMID: 30069603 DOI: 10.1007/s00709-018-1292-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 07/23/2018] [Indexed: 05/27/2023]
Abstract
In this study, we evaluated the behavior of 45S ribosomal DNA (rDNA) sites during the meiosis of Lolium multiflorum. The reason to study it in this species is that 45S rDNA sites are usually visualized as gaps in mitotic metaphase chromosomes and were initially denominated fragile sites (FSs). In different species, FSs were related to rearrangements that alter the karyotype and affect the chromosome pairing in meiosis. However, our findings show that the chromosome pairing in L. multiflorum is regular and, as in mitosis, the number of sites is variable. In diakinesis with five sites, one of the bivalents was in hemizygous state while, in diakinesis with seven sites, one of the bivalents had three conspicuous signals, two in syntheny in one of the homologous. Only four cells had gaps in the region of the 45S rDNA. Owing to the lower number of signals observed at the initial stages of meiosis, it is assumed that they are involved both in homologous and non-homologous associations and that they might assist the chromosome pairing. Regarding segregation, only meiocytes with five and six 45S rDNA signals were observed, and they were characterized by the segregation of 2/3 signals in the poles of anaphases I up to metaphases II; 2/2 and 3/3 in anaphases II and telophases II; and also 2/2 and 4/4 in the nuclei of tetrads, unlike the number of 45S signals expected. The numerical non-equivalence of sites among nuclei at later stages of meiosis is explained by the presence of chromosomes with hemizygous sites.
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Affiliation(s)
- Laiane Corsini Rocha
- Department of Biology, Federal University of Lavras-UFLA, Lavras, Minas Gerais State, Brazil
| | | | | | - Andréa Mittelmann
- Embrapa Gado de Leite/Embrapa Clima Temperado, Pelotas, Rio Grande do Sul State, Brazil
| | - Vânia Helena Techio
- Department of Biology, Federal University of Lavras-UFLA, Lavras, Minas Gerais State, Brazil.
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Ben Ali SE, Schamann A, Dobrovolny S, Indra A, Agapito-Tenfen SZ, Hochegger R, Haslberger AG, Brandes C. Genetic and epigenetic characterization of the cry1Ab coding region and its 3′ flanking genomic region in MON810 maize using next-generation sequencing. Eur Food Res Technol 2018. [DOI: 10.1007/s00217-018-3062-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Rocha LC, Jankowska M, Fuchs J, Mittelmann A, Techio VH, Houben A. Decondensation of chromosomal 45S rDNA sites in Lolium and Festuca genotypes does not result in karyotype instability. PROTOPLASMA 2017; 254:285-292. [PMID: 26758880 DOI: 10.1007/s00709-016-0942-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 01/04/2016] [Indexed: 05/17/2023]
Abstract
Fragile sites (FSs) in plants have been described for species like Lolium and other grasses. Whereas in humans FSs were shown to be involved in genome instabilities; the consequences of FSs expression in plants are not known yet. To evaluate whether FSs cause karyotype instabilities, we assessed the frequency of micronuclei and lagging chromosomes in meristematic cells, the stability of the DNA content, and the occurrence of neocentromeres in the presumed chromosomal fragments of Lolium perenne, Lolium multiflorum, Festuca arrundinacea, and two Festulolium hybrids. The cell cycle analysis along with flow cytometric genome size measurements showed high stability in all genomes evaluated. Neocentromeric activity was neither observed in the presumed fragments nor in any other chromosomal region, then this is not the mechanism responsible by the stability. However, Fluorescence in situ hybridization (FISH) with a 45S ribosomal DNA (rDNA) probe in combination with YOYO staining of metaphasic chromosomes showed that many extended nucleolus organizing region (NOR) form very thin YOYO-positive chromatin fibers connecting the acentric 'fragment' with the centromere-containing chromosome region. The obtained data indicate that the expression of FSs does not result in genome instabilities or neocentromere formation. The FS-containing 45S rDNA carrying chromatin fibers undergo a cell cycle and gene activity-dependent dynamic decondensation process.
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Affiliation(s)
- Laiane Corsini Rocha
- Department of Biology, Federal University of Lavras-UFLA, Lavras, Minas Gerais State, Brazil
| | - Maja Jankowska
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), OT Gatersleben, 06466, StadtSeeland, Germany
| | - Joerg Fuchs
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), OT Gatersleben, 06466, StadtSeeland, Germany
| | - Andréa Mittelmann
- Embrapa Dairy Cattle/Embrapa Temperate Agriculture, Pelotas, Rio Grande do Sul State, Brazil
| | - Vânia Helena Techio
- Department of Biology, Federal University of Lavras-UFLA, Lavras, Minas Gerais State, Brazil.
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), OT Gatersleben, 06466, StadtSeeland, Germany.
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Lan H, Chen CL, Miao Y, Yu CX, Guo WW, Xu Q, Deng XX. Fragile Sites of 'Valencia' Sweet Orange (Citrus sinensis) Chromosomes Are Related with Active 45s rDNA. PLoS One 2016; 11:e0151512. [PMID: 26977938 PMCID: PMC4792391 DOI: 10.1371/journal.pone.0151512] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 02/29/2016] [Indexed: 12/12/2022] Open
Abstract
Citrus sinensis chromosomes present a morphological differentiation of bands after staining by the fluorochromes CMA and DAPI, but there is still little information on its chromosomal characteristics. In this study, the chromosomes in 'Valencia' C. sinensis were analyzed by fluorescence in situ hybridization (FISH) using telomere DNA and the 45S rDNA gene as probes combining CMA/DAPI staining, which showed that there were two fragile sites in sweet orange chromosomes co-localizing at distended 45S rDNA regions, one proximally locating on B-type chromosome and the other subterminally locating on D-type chromosome. While the chromosomal CMA banding and 45S rDNA FISH mapping in the doubled haploid line of 'Valencia' C. sinensis indicated six 45S rDNA regions, four were identified as fragile sites as doubled comparing its parental line, which confirmed the cytological heterozygosity and chromosomal heteromorphisms in sweet orange. Furthermore, Ag-NOR identified two distended 45S rDNA regions to be active nucleolar organizing regions (NORs) in diploid 'Valencia' C. sinensis. The occurrence of quadrivalent in meiosis of pollen mother cells (PMCs) in 'Valencia' sweet orange further confirmed it was a chromosomal reciprocal translocation line. We speculated this chromosome translocation was probably related to fragile sites. Our data provide insights into the chromosomal characteristics of the fragile sites in 'Valencia' sweet orange and are expected to facilitate the further investigation of the possible functions of fragile sites.
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Affiliation(s)
- Hong Lan
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, 430070, China
| | - Chun-Li Chen
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yin Miao
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Chang-Xiu Yu
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wen-Wu Guo
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, 430070, China
| | - Qiang Xu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, 430070, China
| | - Xiu-Xin Deng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, 430070, China
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Ben Ali SE, Madi ZE, Hochegger R, Quist D, Prewein B, Haslberger AG, Brandes C. Mutation scanning in a single and a stacked genetically modified (GM) event by real-time PCR and high resolution melting (HRM) analysis. Int J Mol Sci 2014; 15:19898-923. [PMID: 25365178 PMCID: PMC4264145 DOI: 10.3390/ijms151119898] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 10/11/2014] [Accepted: 10/21/2014] [Indexed: 12/02/2022] Open
Abstract
Genetic mutations must be avoided during the production and use of seeds. In the European Union (EU), Directive 2001/18/EC requires any DNA construct introduced via transformation to be stable. Establishing genetic stability is critical for the approval of genetically modified organisms (GMOs). In this study, genetic stability of two GMOs was examined using high resolution melting (HRM) analysis and real-time polymerase chain reaction (PCR) employing Scorpion primers for amplification. The genetic variability of the transgenic insert and that of the flanking regions in a single oilseed rape variety (GT73) and a stacked maize (MON88017 × MON810) was studied. The GT73 and the 5' region of MON810 showed no instabilities in the examined regions. However; two out of 100 analyzed samples carried a heterozygous point mutation in the 3' region of MON810 in the stacked variety. These results were verified by direct sequencing of the amplified PCR products as well as by sequencing of cloned PCR fragments. The occurrence of the mutation suggests that the 5' region is more suitable than the 3' region for the quantification of MON810. The identification of the single nucleotide polymorphism (SNP) in a stacked event is in contrast to the results of earlier studies of the same MON810 region in a single event where no DNA polymorphism was found.
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Affiliation(s)
- Sina-Elisabeth Ben Ali
- Austrian Agency for Health and Food Safety, Spargelfeldstrasse 191, 1220 Vienna, Austria.
| | - Zita Erika Madi
- Austrian Agency for Health and Food Safety, Spargelfeldstrasse 191, 1220 Vienna, Austria.
| | - Rupert Hochegger
- Austrian Agency for Health and Food Safety, Spargelfeldstrasse 191, 1220 Vienna, Austria.
| | - David Quist
- Centre for Biosafety-GenØk, PB 6418 Science Park, 9294 Tromsoe, Norway.
| | - Bernhard Prewein
- Austrian Agency for Health and Food Safety, Spargelfeldstrasse 191, 1220 Vienna, Austria.
| | - Alexander G Haslberger
- Department of Nutritional Sciences, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
| | - Christian Brandes
- Austrian Agency for Health and Food Safety, Spargelfeldstrasse 191, 1220 Vienna, Austria.
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