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Němečková A, Koláčková V, Vrána J, Doležel J, Hřibová E. DNA replication and chromosome positioning throughout the interphase in three-dimensional space of plant nuclei. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:6262-6272. [PMID: 32805034 DOI: 10.1093/jxb/eraa370] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 07/31/2020] [Indexed: 05/23/2023]
Abstract
Despite much recent progress, our understanding of the principles of plant genome organization and its dynamics in three-dimensional space of interphase nuclei remains surprisingly limited. Notably, it is not clear how these processes could be affected by the size of a plant's nuclear genome. In this study, DNA replication timing and interphase chromosome positioning were analyzed in seven Poaceae species that differ in their genome size. To provide a comprehensive picture, a suite of advanced, complementary methods was used: labeling of newly replicated DNA by ethynyl-2'-deoxyuridine, isolation of nuclei at particular cell cycle phases by flow cytometric sorting, three-dimensional immunofluorescence in situ hybridization, and confocal microscopy. Our results revealed conserved dynamics of DNA replication in all species, and a similar replication timing order for telomeres and centromeres, as well as for euchromatin and heterochromatin regions, irrespective of genome size. Moreover, stable chromosome positioning was observed while transitioning through different stages of interphase. These findings expand upon earlier studies in suggesting that a more complex interplay exists between genome size, organization of repetitive DNA sequences along chromosomes, and higher order chromatin structure and its maintenance in interphase, albeit controlled by currently unknown factors.
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Affiliation(s)
- Alžběta Němečková
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Veronika Koláčková
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Jan Vrána
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Jaroslav Doležel
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Eva Hřibová
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
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2
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Wear EE, Song J, Zynda GJ, Mickelson-Young L, LeBlanc C, Lee TJ, Deppong DO, Allen GC, Martienssen RA, Vaughn MW, Hanley-Bowdoin L, Thompson WF. Comparing DNA replication programs reveals large timing shifts at centromeres of endocycling cells in maize roots. PLoS Genet 2020; 16:e1008623. [PMID: 33052904 PMCID: PMC7588055 DOI: 10.1371/journal.pgen.1008623] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 10/26/2020] [Accepted: 08/28/2020] [Indexed: 12/20/2022] Open
Abstract
Plant cells undergo two types of cell cycles–the mitotic cycle in which DNA replication is coupled to mitosis, and the endocycle in which DNA replication occurs in the absence of cell division. To investigate DNA replication programs in these two types of cell cycles, we pulse labeled intact root tips of maize (Zea mays) with 5-ethynyl-2’-deoxyuridine (EdU) and used flow sorting of nuclei to examine DNA replication timing (RT) during the transition from a mitotic cycle to an endocycle. Comparison of the sequence-based RT profiles showed that most regions of the maize genome replicate at the same time during S phase in mitotic and endocycling cells, despite the need to replicate twice as much DNA in the endocycle and the fact that endocycling is typically associated with cell differentiation. However, regions collectively corresponding to 2% of the genome displayed significant changes in timing between the two types of cell cycles. The majority of these regions are small with a median size of 135 kb, shift to a later RT in the endocycle, and are enriched for genes expressed in the root tip. We found larger regions that shifted RT in centromeres of seven of the ten maize chromosomes. These regions covered the majority of the previously defined functional centromere, which ranged between 1 and 2 Mb in size in the reference genome. They replicate mainly during mid S phase in mitotic cells but primarily in late S phase of the endocycle. In contrast, the immediately adjacent pericentromere sequences are primarily late replicating in both cell cycles. Analysis of CENH3 enrichment levels in 8C vs 2C nuclei suggested that there is only a partial replacement of CENH3 nucleosomes after endocycle replication is complete. The shift to later replication of centromeres and possible reduction in CENH3 enrichment after endocycle replication is consistent with a hypothesis that centromeres are inactivated when their function is no longer needed. In traditional cell division, or mitosis, a cell’s genetic material is duplicated and then split between two daughter cells. In contrast, in some specialized cell types, the DNA is duplicated a second time without an intervening division step, resulting in cells that carry twice as much DNA. This phenomenon, which is called the endocycle, is common during plant development. At each step, DNA replication follows an ordered program in which highly compacted DNA is unraveled and replicated in sections at different times during the synthesis (S) phase. In plants, it is unclear whether traditional and endocycle programs are the same, especially since endocycling cells are typically in the process of differentiation. Using root tips of maize, we found that in comparison to replication in the mitotic cell cycle, there is a small portion of the genome whose replication in the endocycle is shifted in time, usually to later in S phase. Some of these regions are scattered around the genome and mostly coincide with active genes. However, the most prominent shifts occur in centromeres. The shift to later replication in centromeres is noteworthy because they orchestrate the process of separating duplicated chromosomes into daughter cells, a function that is not needed in the endocycle.
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Affiliation(s)
- Emily E. Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
- * E-mail:
| | - Jawon Song
- Texas Advanced Computing Center, University of Texas, Austin, Texas, United States of America
| | - Gregory J. Zynda
- Texas Advanced Computing Center, University of Texas, Austin, Texas, United States of America
| | - Leigh Mickelson-Young
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Chantal LeBlanc
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Tae-Jin Lee
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - David O. Deppong
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - George C. Allen
- Department of Horticultural Science, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Robert A. Martienssen
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Matthew W. Vaughn
- Texas Advanced Computing Center, University of Texas, Austin, Texas, United States of America
| | - Linda Hanley-Bowdoin
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - William F. Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
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3
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Dumur T, Duncan S, Graumann K, Desset S, Randall RS, Scheid OM, Prodanov D, Tatout C, Baroux C. Probing the 3D architecture of the plant nucleus with microscopy approaches: challenges and solutions. Nucleus 2019; 10:181-212. [PMID: 31362571 PMCID: PMC6682351 DOI: 10.1080/19491034.2019.1644592] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 06/24/2019] [Accepted: 07/01/2019] [Indexed: 12/18/2022] Open
Abstract
The eukaryotic cell nucleus is a central organelle whose architecture determines genome function at multiple levels. Deciphering nuclear organizing principles influencing cellular responses and identity is a timely challenge. Despite many similarities between plant and animal nuclei, plant nuclei present intriguing specificities. Complementary to molecular and biochemical approaches, 3D microscopy is indispensable for resolving nuclear architecture. However, novel solutions are required for capturing cell-specific, sub-nuclear and dynamic processes. We provide a pointer for utilising high-to-super-resolution microscopy and image processing to probe plant nuclear architecture in 3D at the best possible spatial and temporal resolution and at quantitative and cell-specific levels. High-end imaging and image-processing solutions allow the community now to transcend conventional practices and benefit from continuously improving approaches. These promise to deliver a comprehensive, 3D view of plant nuclear architecture and to capture spatial dynamics of the nuclear compartment in relation to cellular states and responses. Abbreviations: 3D and 4D: Three and Four dimensional; AI: Artificial Intelligence; ant: antipodal nuclei (ant); CLSM: Confocal Laser Scanning Microscopy; CTs: Chromosome Territories; DL: Deep Learning; DLIm: Dynamic Live Imaging; ecn: egg nucleus; FACS: Fluorescence-Activated Cell Sorting; FISH: Fluorescent In Situ Hybridization; FP: Fluorescent Proteins (GFP, RFP, CFP, YFP, mCherry); FRAP: Fluorescence Recovery After Photobleaching; GPU: Graphics Processing Unit; KEEs: KNOT Engaged Elements; INTACT: Isolation of Nuclei TAgged in specific Cell Types; LADs: Lamin-Associated Domains; ML: Machine Learning; NA: Numerical Aperture; NADs: Nucleolar Associated Domains; PALM: Photo-Activated Localization Microscopy; Pixel: Picture element; pn: polar nuclei; PSF: Point Spread Function; RHF: Relative Heterochromatin Fraction; SIM: Structured Illumination Microscopy; SLIm: Static Live Imaging; SMC: Spore Mother Cell; SNR: Signal to Noise Ratio; SRM: Super-Resolution Microscopy; STED: STimulated Emission Depletion; STORM: STochastic Optical Reconstruction Microscopy; syn: synergid nuclei; TADs: Topologically Associating Domains; Voxel: Volumetric pixel.
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Affiliation(s)
- Tao Dumur
- Gregor Mendel Institute (GMI) of Molecular Plant Biology, Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna, Austria
| | - Susan Duncan
- Norwich Research Park, Earlham Institute, Norwich, UK
| | - Katja Graumann
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Sophie Desset
- GReD, Université Clermont Auvergne, CNRS, INSERM, Clermont–Ferrand, France
| | - Ricardo S Randall
- Department of Plant and Microbial Biology, Zürich-Basel Plant Science Center, University of Zürich, Zürich, Switzerland
| | - Ortrun Mittelsten Scheid
- Gregor Mendel Institute (GMI) of Molecular Plant Biology, Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna, Austria
| | - Dimiter Prodanov
- Environment, Health and Safety, Neuroscience Research Flanders, Leuven, Belgium
| | - Christophe Tatout
- GReD, Université Clermont Auvergne, CNRS, INSERM, Clermont–Ferrand, France
| | - Célia Baroux
- Department of Plant and Microbial Biology, Zürich-Basel Plant Science Center, University of Zürich, Zürich, Switzerland
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4
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Isoda M, Oyama T. Use of a duckweed species, Wolffiella hyalina, for whole-plant observation of physiological behavior at the single-cell level. PLANT BIOTECHNOLOGY (TOKYO, JAPAN) 2018; 35:387-391. [PMID: 31892827 PMCID: PMC6905221 DOI: 10.5511/plantbiotechnology.18.0721a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We developed a new model system to analyze physiological behavior at the single-cell level in whole plants. Wolffiella hyalina is a species of rootless duckweed, which has a thin and very small structure and can grow rapidly on the surface of culture medium. Epidermal and mesophyll cells were transfected with a reporter gene using particle bombardment and were observed at the single-cell level in the whole living plant. An EM-CCD camera system with a macro zoom microscope was used to capture time-lapse images of bioluminescence, and we successfully detected circadian rhythms in individual cells that expressed a luciferase gene under the control of a circadian promoter. We also detected individual S-phase cells in meristematic tissues of intact W. hyalina plants by using a 5-ethynyl-2'-deoxyuridine (EdU)-labeling assay. Our observations indicated that low-molecular-weight compounds could access the inside of the plant body. Thus, W. hyalina showed the experimental characteristics suitable for single-cell analyses that could be combined with whole-plant observations and/or pharmacological analyses/chemical biology.
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Affiliation(s)
- Minako Isoda
- Department of Botany, Graduate School of Science, Kyoto University, Kitashirakawa-oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Tokitaka Oyama
- Department of Botany, Graduate School of Science, Kyoto University, Kitashirakawa-oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
- E-mail: Tel: +81-75-753-4135 Fax: +81-75-753-4137
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5
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Turpin ZM, Vera DL, Savadel SD, Lung PY, Wear EE, Mickelson-Young L, Thompson WF, Hanley-Bowdoin L, Dennis JH, Zhang J, Bass HW. Chromatin structure profile data from DNS-seq: Differential nuclease sensitivity mapping of four reference tissues of B73 maize ( Zea mays L). Data Brief 2018; 20:358-363. [PMID: 30175199 PMCID: PMC6117953 DOI: 10.1016/j.dib.2018.08.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 07/12/2018] [Accepted: 08/06/2018] [Indexed: 11/17/2022] Open
Abstract
Presented here are data from Next-Generation Sequencing of differential micrococcal nuclease digestions of formaldehyde-crosslinked chromatin in selected tissues of maize (Zea mays) inbred line B73. Supplemental materials include a wet-bench protocol for making DNS-seq libraries, the DNS-seq data processing pipeline for producing genome browser tracks. This report also includes the peak-calling pipeline using the iSeg algorithm to segment positive and negative peaks from the DNS-seq difference profiles. The data repository for the sequence data is the NCBI SRA, BioProject Accession PRJNA445708.
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Affiliation(s)
- Zachary M. Turpin
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA
| | - Daniel L. Vera
- Center for Genomics and Personalized Medicine, Florida State University, Tallahassee, FL, USA
| | - Savannah D. Savadel
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA
| | - Pei-Yau Lung
- Department of Statistics, Florida State University, Tallahassee, FL, 32306, USA
| | - Emily E. Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh 27606, USA
| | - Leigh Mickelson-Young
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh 27606, USA
| | - William F. Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh 27606, USA
| | - Linda Hanley-Bowdoin
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh 27606, USA
| | - Jonathan H. Dennis
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA
| | - Jinfeng Zhang
- Department of Statistics, Florida State University, Tallahassee, FL, 32306, USA
| | - Hank W. Bass
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA
- Corresponding author.
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6
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Dvořáčková M, Raposo B, Matula P, Fuchs J, Schubert V, Peška V, Desvoyes B, Gutierrez C, Fajkus J. Replication of ribosomal DNA in Arabidopsis occurs both inside and outside the nucleolus during S phase progression. J Cell Sci 2018; 131:jcs.202416. [PMID: 28483825 DOI: 10.1242/jcs.202416] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 04/06/2017] [Indexed: 12/14/2022] Open
Abstract
Ribosomal RNA genes (rDNA) have been used as valuable experimental systems in numerous studies. Here, we focus on elucidating the spatiotemporal organisation of rDNA replication in Arabidopsis thaliana To determine the subnuclear distribution of rDNA and the progression of its replication during the S phase, we apply 5-ethynyl-2'-deoxyuridine (EdU) labelling, fluorescence-activated cell sorting, fluorescence in situ hybridization and structured illumination microscopy. We show that rDNA is replicated inside and outside the nucleolus, where active transcription occurs at the same time. Nascent rDNA shows a maximum of nucleolar associations during early S phase. In addition to EdU patterns typical for early or late S phase, we describe two intermediate EdU profiles characteristic for mid S phase. Moreover, the use of lines containing mutations in the chromatin assembly factor-1 gene fas1 and wild-type progeny of fas1xfas2 crosses depleted of inactive copies allows for selective observation of the replication pattern of active rDNA. High-resolution data are presented, revealing the culmination of replication in the mid S phase in the nucleolus and its vicinity. Taken together, our results provide a detailed snapshot of replication of active and inactive rDNA during S phase progression.
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Affiliation(s)
- Martina Dvořáčková
- Laboratory of Molecular Complexes of Chromatin, Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Kamenice 5, Brno 62500, Czech Republic
| | - Berta Raposo
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, Madrid 28049, Spain
| | - Petr Matula
- Department of Computer Graphics and Design, Faculty of Informatics, Masaryk University, Botanická 554/68a, Brno 60200, Czech Republic
| | - Joerg Fuchs
- Breeding Research Department, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstrasse 3, Stadt Seeland D-06466, Germany
| | - Veit Schubert
- Breeding Research Department, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstrasse 3, Stadt Seeland D-06466, Germany
| | - Vratislav Peška
- Laboratory of Molecular Complexes of Chromatin, Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Kamenice 5, Brno 62500, Czech Republic.,Department of Cell Biology and Radiology, Institute of Biophysics ASCR, v.v.i., Královopolská 135, Brno 61265, Czech Republic
| | - Bénédicte Desvoyes
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, Madrid 28049, Spain
| | - Crisanto Gutierrez
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, Madrid 28049, Spain
| | - Jiří Fajkus
- Laboratory of Molecular Complexes of Chromatin, Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Kamenice 5, Brno 62500, Czech Republic .,Department of Cell Biology and Radiology, Institute of Biophysics ASCR, v.v.i., Královopolská 135, Brno 61265, Czech Republic.,Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137, Czech Republic
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7
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Pass DA, Sornay E, Marchbank A, Crawford MR, Paszkiewicz K, Kent NA, Murray JAH. Genome-wide chromatin mapping with size resolution reveals a dynamic sub-nucleosomal landscape in Arabidopsis. PLoS Genet 2017; 13:e1006988. [PMID: 28902852 PMCID: PMC5597176 DOI: 10.1371/journal.pgen.1006988] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 08/21/2017] [Indexed: 02/06/2023] Open
Abstract
All eukaryotic genomes are packaged as chromatin, with DNA interlaced with both regularly patterned nucleosomes and sub-nucleosomal-sized protein structures such as mobile and labile transcription factors (TF) and initiation complexes, together forming a dynamic chromatin landscape. Whilst details of nucleosome position in Arabidopsis have been previously analysed, there is less understanding of their relationship to more dynamic sub-nucleosomal particles (subNSPs) defined as protected regions shorter than the ~150bp typical of nucleosomes. The genome-wide profile of these subNSPs has not been previously analysed in plants and this study investigates the relationship of dynamic bound particles with transcriptional control. Here we combine differential micrococcal nuclease (MNase) digestion and a modified paired-end sequencing protocol to reveal the chromatin structure landscape of Arabidopsis cells across a wide particle size range. Linking this data to RNAseq expression analysis provides detailed insight into the relationship of identified DNA-bound particles with transcriptional activity. The use of differential digestion reveals sensitive positions, including a labile -1 nucleosome positioned upstream of the transcription start site (TSS) of active genes. We investigated the response of the chromatin landscape to changes in environmental conditions using light and dark growth, given the large transcriptional changes resulting from this simple alteration. The resulting shifts in the suites of expressed and repressed genes show little correspondence to changes in nucleosome positioning, but led to significant alterations in the profile of subNSPs upstream of TSS both globally and locally. We examined previously mapped positions for the TFs PIF3, PIF4 and CCA1, which regulate light responses, and found that changes in subNSPs co-localized with these binding sites. This small particle structure is detected only under low levels of MNase digestion and is lost on more complete digestion of chromatin to nucleosomes. We conclude that wide-spectrum analysis of the Arabidopsis genome by differential MNase digestion allows detection of sensitive features hereto obscured, and the comparisons between genome-wide subNSP profiles reveals dynamic changes in their distribution, particularly at distinct genomic locations (i.e. 5'UTRs). The method here employed allows insight into the complex influence of genetic and extrinsic factors in modifying the sub-nucleosomal landscape in association with transcriptional changes.
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Affiliation(s)
- Daniel Antony Pass
- Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - Emily Sornay
- Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - Angela Marchbank
- Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - Margaret R. Crawford
- Genome Centre, University of Sussex, Sussex House, Falmer, Brighton, United Kingdom
| | - Konrad Paszkiewicz
- Geoffrey Pope Building, University of Exeter, Stocker Road, Exeter, United Kingdom
| | - Nicholas A. Kent
- Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - James A. H. Murray
- Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
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8
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Zynda GJ, Song J, Concia L, Wear EE, Hanley-Bowdoin L, Thompson WF, Vaughn MW. Repliscan: a tool for classifying replication timing regions. BMC Bioinformatics 2017; 18:362. [PMID: 28784090 PMCID: PMC5547489 DOI: 10.1186/s12859-017-1774-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 07/30/2017] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Replication timing experiments that use label incorporation and high throughput sequencing produce peaked data similar to ChIP-Seq experiments. However, the differences in experimental design, coverage density, and possible results make traditional ChIP-Seq analysis methods inappropriate for use with replication timing. RESULTS To accurately detect and classify regions of replication across the genome, we present Repliscan. Repliscan robustly normalizes, automatically removes outlying and uninformative data points, and classifies Repli-seq signals into discrete combinations of replication signatures. The quality control steps and self-fitting methods make Repliscan generally applicable and more robust than previous methods that classify regions based on thresholds. CONCLUSIONS Repliscan is simple and effective to use on organisms with different genome sizes. Even with analysis window sizes as small as 1 kilobase, reliable profiles can be generated with as little as 2.4x coverage.
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Affiliation(s)
- Gregory J Zynda
- Texas Advanced Computing Center, University of Texas at Austin, 10100 Burnet Road, Austin, 78758-4497, TX, USA
| | - Jawon Song
- Texas Advanced Computing Center, University of Texas at Austin, 10100 Burnet Road, Austin, 78758-4497, TX, USA
| | - Lorenzo Concia
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, 27695-7612, NC, USA
| | - Emily E Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, 27695-7612, NC, USA
| | - Linda Hanley-Bowdoin
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, 27695-7612, NC, USA
| | - William F Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, 27695-7612, NC, USA
| | - Matthew W Vaughn
- Texas Advanced Computing Center, University of Texas at Austin, 10100 Burnet Road, Austin, 78758-4497, TX, USA.
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9
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Savadel SD, Bass HW. Take a look at plant DNA replication: Recent insights and new questions. PLANT SIGNALING & BEHAVIOR 2017; 12:e1311437. [PMID: 28375043 PMCID: PMC5437822 DOI: 10.1080/15592324.2017.1311437] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 03/20/2017] [Indexed: 05/21/2023]
Abstract
Recent advances in replicative DNA labeling technology have allowed new ways to study DNA replication in living plants. Temporal and spatial aspects of DNA replication programs are believed to derive from genomic structure and function. Bass et al. (2015) recently visualized DNA synthesis using 3D microscopy of nuclei at three sub-stages of S phase: early, middle and late. This addendum expands on that study by comparing plant and animal DNA replication patterns, by considering implications of the two-compartment model of euchromatin, and by exploring the meaning of the DNA labeling signals inside the nucleolus. Finally, we invite the public to explore and utilize 300 image data sets through OMERO, a teaching and research web resource for visualization, management, or analysis of microscopic data.
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Affiliation(s)
- Savannah D. Savadel
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Hank W. Bass
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
- CONTACT Hank W. Bass Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, Florida, 32306–4295, USA
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10
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Brasil JN, Costa CNM, Cabral LM, Ferreira PCG, Hemerly AS. The plant cell cycle: Pre-Replication complex formation and controls. Genet Mol Biol 2017; 40:276-291. [PMID: 28304073 PMCID: PMC5452130 DOI: 10.1590/1678-4685-gmb-2016-0118] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Accepted: 08/16/2016] [Indexed: 01/07/2023] Open
Abstract
The multiplication of cells in all living organisms requires a tight regulation of DNA replication. Several mechanisms take place to ensure that the DNA is replicated faithfully and just once per cell cycle in order to originate through mitoses two new daughter cells that contain exactly the same information from the previous one. A key control mechanism that occurs before cells enter S phase is the formation of a pre-replication complex (pre-RC) that is assembled at replication origins by the sequential association of the origin recognition complex, followed by Cdt1, Cdc6 and finally MCMs, licensing DNA to start replication. The identification of pre-RC members in all animal and plant species shows that this complex is conserved in eukaryotes and, more importantly, the differences between kingdoms might reflect their divergence in strategies on cell cycle regulation, as it must be integrated and adapted to the niche, ecosystem, and the organism peculiarities. Here, we provide an overview of the knowledge generated so far on the formation and the developmental controls of the pre-RC mechanism in plants, analyzing some particular aspects in comparison to other eukaryotes.
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Affiliation(s)
- Juliana Nogueira Brasil
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.,Centro Universitário Christus, Fortaleza, CE, Brazil
| | - Carinne N Monteiro Costa
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.,Centro de Genômica e Biologia de Sistemas, Universidade Federal do Pará, Belém, PA, Brazil
| | - Luiz Mors Cabral
- Departamento de Biologia Celular e Molecular, Universidade Federal Fluminense, Niteroi, RJ, Brazil
| | - Paulo C G Ferreira
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Adriana S Hemerly
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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11
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Mickelson-Young L, Wear E, Mulvaney P, Lee TJ, Szymanski ES, Allen G, Hanley-Bowdoin L, Thompson W. A flow cytometric method for estimating S-phase duration in plants. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:6077-6087. [PMID: 27697785 PMCID: PMC5100020 DOI: 10.1093/jxb/erw367] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The duration of the DNA synthesis stage (S phase) of the cell cycle is fundamental in our understanding of cell cycle kinetics, cell proliferation, and DNA replication timing programs. Most S-phase duration estimates that exist for plants are based on indirect measurements. We present a method for directly estimating S-phase duration by pulse-labeling root tips or actively dividing suspension cells with the halogenated thymidine analog 5-ethynl-2'-deoxyuridine (EdU) and analyzing the time course of replication with bivariate flow cytometry. The transition between G1 and G2 DNA contents can be followed by measuring the mean DNA content of EdU-labeled S-phase nuclei as a function of time after the labeling pulse. We applied this technique to intact root tips of maize (Zea mays L.), rice (Oryza sativa L.), barley (Hordeum vulgare L.), and wheat (Triticum aestivum L.), and to actively dividing cell cultures of Arabidopsis (Arabidopsis thaliana (L.) Heynh.) and rice. Estimates of S-phase duration in root tips were remarkably consistent, varying only by ~3-fold, although the genome sizes of the species analyzed varied >40-fold.
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Affiliation(s)
- Leigh Mickelson-Young
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Emily Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Patrick Mulvaney
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Tae-Jin Lee
- Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695, USA
- Present address: Syngenta Crop Protection, LLC, Research Triangle Park, NC 27709, USA
| | - Eric S Szymanski
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
- Present address: Department of Biochemistry, Duke University, Durham, NC 27710, USA
| | - George Allen
- Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695, USA
| | - Linda Hanley-Bowdoin
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - William Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
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12
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Yin X, Tsukaya H. A pulse-chase strategy for EdU labelling assay is able to rapidly quantify cell division orientation. THE NEW PHYTOLOGIST 2016; 211:1462-1469. [PMID: 27121010 DOI: 10.1111/nph.13980] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 03/19/2016] [Indexed: 06/05/2023]
Abstract
Measurement of the direction of cell division is an important, yet difficult, task to analyse how a plant organ acquires its final shape from an initially small group of cells. We introduce a method that rapidly and easily quantifies cell division direction and is applicable to all plant species. A pulse-chase strategy for 5-ethynyl-2'-deoxyuridine (EdU) labelling assay was established and was shown to be successful for leaves of Arabidopsis thaliana (Arabidopsis) and Juncus prismatocarpus. By optimization of the pulse and chase periods, most of the signals obtained were sets of daughter nuclei. For Arabidopsis, the optimal time was a 45-min pulse and a 7-h chase. For J. prismatocarpus, the optimal time was a 2-h pulse and a 13.5-h chase. The positions of the daughter nuclei were used to quantify cell division direction in the Arabidopsis leaf primordia. Overall, cell division along the proximal-distal axis was more frequent than along the medial-lateral axis. In petiole, major vein, minor vein and margin areas, the major cell division direction seemed to be coincident with the direction of auxin flow. The advantages of our method over the few methods used previously are discussed. We anticipate that it will provide opportunities to study plant development in the near future.
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Affiliation(s)
- Xiaofeng Yin
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Hirokazu Tsukaya
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
- Bio-Next Project, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Yamate Building no. 3, 5-1, Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan
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13
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Yokoyama R, Hirakawa T, Hayashi S, Sakamoto T, Matsunaga S. Dynamics of plant DNA replication based on PCNA visualization. Sci Rep 2016; 6:29657. [PMID: 27417498 PMCID: PMC4945867 DOI: 10.1038/srep29657] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 06/21/2016] [Indexed: 11/22/2022] Open
Abstract
DNA replication is an essential process for the copying of genomic information in living organisms. Imaging of DNA replication in tissues and organs is mainly performed using fixed cells after incorporation of thymidine analogs. To establish a useful marker line to measure the duration of DNA replication and analyze the dynamics of DNA replication, we focused on the proliferating cell nuclear antigen (PCNA), which functions as a DNA sliding clamp for replicative DNA polymerases and is an essential component of replisomes. In this study we produced an Arabidopsis thaliana line expressing PCNA1 fused with the green fluorescent protein under the control of its own promoter (pAtPCNA1::AtPCNA1-sGFP). The duration of the S phase measured using the expression line was consistent with that measured after incorporation of a thymidine analog. Live cell imaging revealed that three distinct nuclear localization patterns (whole, dotted, and speckled) were sequentially observable. These whole, dotted, and speckled patterns of subnuclear AtPCNA1 signals were indicative of the G1 or G2 phase, early S phase and late S phase, respectively. The results indicate that the pAtPCNA1::AtPCNA1-sGFP line is a useful marker line for visualization of S-phase progression in live plant organs.
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Affiliation(s)
- Ryohei Yokoyama
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Takeshi Hirakawa
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Seri Hayashi
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Takuya Sakamoto
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Sachihiro Matsunaga
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
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14
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Hřibová E, Holušová K, Trávníček P, Petrovská B, Ponert J, Šimková H, Kubátová B, Jersáková J, Čurn V, Suda J, Doležel J, Vrána J. The Enigma of Progressively Partial Endoreplication: New Insights Provided by Flow Cytometry and Next-Generation Sequencing. Genome Biol Evol 2016; 8:1996-2005. [PMID: 27324917 PMCID: PMC4943206 DOI: 10.1093/gbe/evw141] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
In many plant species, somatic cell differentiation is accompanied by endoreduplication, a process during which cells undergo one or more rounds of DNA replication cycles in the absence of mitosis, resulting in nuclei with multiples of 2C DNA amounts (4C, 8C, 16C, etc.). In some orchids, a disproportionate increase in nuclear DNA contents has been observed, where successive endoreduplication cycles result in DNA amounts 2C + P, 2C + 3P, 2C + 7P, etc., where P is the DNA content of the replicated part of the 2C nuclear genome. This unique phenomenon was termed "progressively partial endoreplication" (PPE). We investigated processes behind the PPE in Ludisia discolor using flow cytometry (FCM) and Illumina sequencing. In particular, we wanted to determine whether chromatin elimination or incomplete genome duplication was involved, and to identify types of DNA sequences that were affected. Cell cycle analysis of root tip cell nuclei pulse-labeled with EdU revealed two cell cycles, one ending above the population of nuclei with 2C + P content, and the other with a typical "horseshoe" pattern of S-phase nuclei ranging from 2C to 4C DNA contents. The process leading to nuclei with 2C + P amounts therefore involves incomplete genome replication. Subsequent Illumina sequencing of flow-sorted 2C and 2C + P nuclei showed that all types of repetitive DNA sequences were affected during PPE; a complete elimination of any specific type of repetitive DNA was not observed. We hypothesize that PPE is part of a highly controlled transition mechanism from proliferation phase to differentiation phase of plant tissue development.
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Affiliation(s)
- Eva Hřibová
- Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany, Olomouc, Czech Republic
| | - Kateřina Holušová
- Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany, Olomouc, Czech Republic
| | - Pavel Trávníček
- Institute of Botany, the Czech Academy of Sciences, Průhonice, Czech Republic Department of Botany, Faculty of Science, Charles University in Prague, Czech Republic Biotechnological Centre, Faculty of Agriculture, University of South Bohemia in České Budějovice, Czech Republic
| | - Beáta Petrovská
- Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany, Olomouc, Czech Republic
| | - Jan Ponert
- Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Czech Republic Prague Botanical Garden, Prague, Czech Republic
| | - Hana Šimková
- Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany, Olomouc, Czech Republic
| | - Barbora Kubátová
- Biotechnological Centre, Faculty of Agriculture, University of South Bohemia in České Budějovice, Czech Republic
| | - Jana Jersáková
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia in České Budějovice, Czech Republic
| | - Vladislav Čurn
- Biotechnological Centre, Faculty of Agriculture, University of South Bohemia in České Budějovice, Czech Republic
| | - Jan Suda
- Institute of Botany, the Czech Academy of Sciences, Průhonice, Czech Republic Department of Botany, Faculty of Science, Charles University in Prague, Czech Republic
| | - Jaroslav Doležel
- Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany, Olomouc, Czech Republic
| | - Jan Vrána
- Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany, Olomouc, Czech Republic
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15
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Wear EE, Concia L, Brooks AM, Markham EA, Lee TJ, Allen GC, Thompson WF, Hanley-Bowdoin L. Isolation of Plant Nuclei at Defined Cell Cycle Stages Using EdU Labeling and Flow Cytometry. Methods Mol Biol 2016; 1370:69-86. [PMID: 26659955 DOI: 10.1007/978-1-4939-3142-2_6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
5-Ethynyl-2'-deoxyuridine (EdU) is a nucleoside analog of thymidine that can be rapidly incorporated into replicating DNA in vivo and, subsequently, detected by using "click" chemistry to couple its terminal alkyne group to fluorescent azides such as Alexa Fluor 488. Recently, EdU incorporation followed by coupling with a fluorophore has been used to visualize newly synthesized DNA in a wide range of plant species. One particularly useful application is in flow cytometry, where two-parameter sorting can be employed to analyze different phases of the cell cycle, as defined both by total DNA content and the amount of EdU pulse-labeled DNA. This approach allows analysis of the cell cycle without the need for synchronous cell populations, which can be difficult to obtain in many plant systems. The approach presented here, which was developed for fixed, EdU-labeled nuclei, can be used to prepare analytical profiles as well as to make highly purified preparations of G1, S, or G2/M phase nuclei for molecular or biochemical analysis. We present protocols for EdU pulse labeling, tissue fixation and harvesting, nuclei preparation, and flow sorting. Although developed for Arabidopsis suspension cells and maize root tips, these protocols should be modifiable to many other plant systems.
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Affiliation(s)
- Emily E Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695, USA
| | - Lorenzo Concia
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, 27695, USA
| | - Ashley M Brooks
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, 27695, USA
| | - Emily A Markham
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695, USA
| | - Tae-Jin Lee
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695, USA
- Syngenta Crop Protection, LLC, Research Triangle Park, NC, 27709, USA
| | - George C Allen
- Department of Horticultural Science, North Carolina State University, Raleigh, NC, 27695, USA
| | - William F Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695, USA
| | - Linda Hanley-Bowdoin
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC, 27695, USA.
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16
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Bass HW, Hoffman GG, Lee TJ, Wear EE, Joseph SR, Allen GC, Hanley-Bowdoin L, Thompson WF. Defining multiple, distinct, and shared spatiotemporal patterns of DNA replication and endoreduplication from 3D image analysis of developing maize (Zea mays L.) root tip nuclei. PLANT MOLECULAR BIOLOGY 2015; 89:339-51. [PMID: 26394866 PMCID: PMC4631726 DOI: 10.1007/s11103-015-0364-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 08/19/2015] [Indexed: 05/09/2023]
Abstract
Spatiotemporal patterns of DNA replication have been described for yeast and many types of cultured animal cells, frequently after cell cycle arrest to aid in synchronization. However, patterns of DNA replication in nuclei from plants or naturally developing organs remain largely uncharacterized. Here we report findings from 3D quantitative analysis of DNA replication and endoreduplication in nuclei from pulse-labeled developing maize root tips. In both early and middle S phase nuclei, flow-sorted on the basis of DNA content, replicative labeling was widely distributed across euchromatic regions of the nucleoplasm. We did not observe the perinuclear or perinucleolar replicative labeling patterns characteristic of middle S phase in mammals. Instead, the early versus middle S phase patterns in maize could be distinguished cytologically by correlating two quantitative, continuous variables, replicative labeling and DAPI staining. Early S nuclei exhibited widely distributed euchromatic labeling preferentially localized to regions with weak DAPI signals. Middle S nuclei also exhibited widely distributed euchromatic labeling, but the label was preferentially localized to regions with strong DAPI signals. Highly condensed heterochromatin, including knobs, replicated during late S phase as previously reported. Similar spatiotemporal replication patterns were observed for both mitotic and endocycling maize nuclei. These results revealed that maize euchromatin exists as an intermingled mixture of two components distinguished by their condensation state and replication timing. These different patterns might reflect a previously described genome organization pattern, with "gene islands" mostly replicating during early S phase followed by most of the intergenic repetitive regions replicating during middle S phase.
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Affiliation(s)
- Hank W Bass
- Department of Biological Science, Florida State University, 319 Stadium Drive, King Life Sciences Building, Tallahassee, FL, 32306-4295, USA.
| | - Gregg G Hoffman
- Department of Biological Science, Florida State University, 319 Stadium Drive, King Life Sciences Building, Tallahassee, FL, 32306-4295, USA
| | - Tae-Jin Lee
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695-7612, USA
| | - Emily E Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695-7612, USA
| | - Stacey R Joseph
- Department of Biological Science, Florida State University, 319 Stadium Drive, King Life Sciences Building, Tallahassee, FL, 32306-4295, USA
| | - George C Allen
- Department of Horticultural Science, North Carolina State University, Raleigh, NC, 27695-7609, USA
| | - Linda Hanley-Bowdoin
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695-7612, USA
| | - William F Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695-7612, USA
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17
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Endaya B, Cavanagh B, Alowaidi F, Walker T, de Pennington N, Ng JMA, Lam PYP, Mackay-Sim A, Neuzil J, Meedeniya ACB. Isolating dividing neural and brain tumour cells for gene expression profiling. J Neurosci Methods 2015; 257:121-33. [PMID: 26432933 DOI: 10.1016/j.jneumeth.2015.09.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 09/21/2015] [Accepted: 09/23/2015] [Indexed: 12/24/2022]
Abstract
BACKGROUND The characterisation of dividing brain cells is fundamental for studies ranging from developmental and stem cell biology, to brain cancers. Whilst there is extensive anatomical data on these dividing cells, limited gene transcription data is available due to technical constraints. NEW METHOD We focally isolated dividing cells whilst conserving RNA, from culture, primary neural tissue and xenografted glioma tumours, using a thymidine analogue that enables gene transcription analysis. RESULTS 5-ethynyl-2-deoxyuridine labels the replicating DNA of dividing cells. Once labelled, cultured cells and tissues were dissociated, fluorescently tagged with a revised click chemistry technique and the dividing cells isolated using fluorescence-assisted cell sorting. RNA was extracted and analysed using real time PCR. Proliferation and maturation related gene expression in neurogenic tissues was demonstrated in acutely and 3 day old labelled cells, respectively. An elevated expression of marker and pathway genes was demonstrated in the dividing cells of xenografted brain tumours, with the non-dividing cells showing relatively low levels of expression. COMPARISON WITH EXISTING METHOD BrdU "immune-labelling", the most frequently used protocol for detecting cell proliferation, causes complete denaturation of RNA, precluding gene transcription analysis. This EdU labelling technique, maintained cell integrity during dissociation, minimized copper exposure during labelling and used a cell isolation protocol that avoided cell lysis, thus conserving RNA. CONCLUSIONS The technique conserves RNA, enabling the definition of cell proliferation-related changes in gene transcription of neural and pathological brain cells in cells harvested immediately after division, or following a period of maturation.
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Affiliation(s)
- Berwini Endaya
- Griffith Health Institute, Griffith University, Southport, QLD 4222, Australia; Eskitis Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia
| | - Brenton Cavanagh
- Eskitis Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia
| | - Faisal Alowaidi
- Griffith Health Institute, Griffith University, Southport, QLD 4222, Australia; Eskitis Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia
| | - Tom Walker
- Griffith Health Institute, Griffith University, Southport, QLD 4222, Australia; Eskitis Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia
| | - Nicholas de Pennington
- Human Adult Neural Stem Cell Facility, Nuffield Department of Surgery, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, United Kingdom
| | - Jin-Ming A Ng
- Eskitis Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia
| | - Paula Y P Lam
- National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610, Singapore
| | - Alan Mackay-Sim
- Eskitis Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia
| | - Jiri Neuzil
- Griffith Health Institute, Griffith University, Southport, QLD 4222, Australia; Institute of Biotechnology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4-Krc, Czech Republic
| | - Adrian C B Meedeniya
- Griffith Health Institute, Griffith University, Southport, QLD 4222, Australia; Eskitis Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia.
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18
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Abstract
This review, written from a personal perspective, traces firstly the development of plant cell cycle research from the 1970s onwards, with some focus on the work of the author and of Dr Dennis Francis. Secondly there is a discussion of the support for and discussion of plant cell cycle research in the SEB, especially through the activities of the Cell Cycle Group within the Society's Cell Biology Section. In the main part of the review, selected aspects of DNA replication that have of been of special interest to the author are discussed. These are DNA polymerases and associated proteins, pre-replication events, regulation of enzymes and other proteins, nature and activation of DNA replication origins, and DNA endoreduplication. For all these topics, there is mention of the author's own work, followed by a brief synthesis of current understanding and a look to possible future developments.
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Affiliation(s)
- John Bryant
- School of Biosciences, CLES, University of Exeter, Exeter EX4 4PS, UK
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19
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Scofield S, Jones A, Murray JAH. The plant cell cycle in context. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2557-62. [PMID: 25025122 DOI: 10.1093/jxb/eru188] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
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20
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Murphy SP, Gumber HK, Mao Y, Bass HW. A dynamic meiotic SUN belt includes the zygotene-stage telomere bouquet and is disrupted in chromosome segregation mutants of maize (Zea mays L.). FRONTIERS IN PLANT SCIENCE 2014; 5:314. [PMID: 25071797 PMCID: PMC4093829 DOI: 10.3389/fpls.2014.00314] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 06/13/2014] [Indexed: 05/17/2023]
Abstract
The nuclear envelope (NE) plays an essential role in meiotic telomere behavior and links the cytoplasm and nucleoplasm during homologous chromosome pairing and recombination in many eukaryotic species. Resident NE proteins including SUN (Sad-1/UNC-84) and KASH (Klarsicht/ANC-1/Syne-homology) domain proteins are known to interact forming the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex that connects chromatin to the cytoskeleton. To investigate the possible cross-kingdom conservation of SUN protein functions in plant meiosis, we immunolocalized maize SUN2 using 3D microscopy of pollen mother cells from maize (Zea mays L.), a large-genome plant model with a canonical NE zygotene-stage telomere bouquet. We detected SUN2 at the nuclear periphery and found that it exhibited a distinct belt-like structure that transitioned to a half-belt during the zygotene stage and back to a full belt during and beyond the pachytene stage. The zygotene-stage half-belt SUN structure was shown by 3D immuno-FISH to include the NE-associated telomere cluster that defines the bouquet stage and coincides with homologous chromosome synapsis. Microtubule and filamentous actin staining patterns did not show any obvious belt or a retracted-like structure other than a general enrichment of tubulin staining distributed widely around the nucleus and throughout the cytoplasm. Genetic disruption of the meiotic SUN belt staining patterns with three different meiosis-specific mutants, desynaptic (dy1), asynaptic1 (as1), and divergent spindle1 (dv1) provides additional evidence for the role of the nuclear envelope in meiotic chromosome behavior. Taking into account all of the observations from this study, we propose that the maize SUN belt is directly or indirectly involved in meiotic telomere dynamics, chromosome synapsis, and possibly integration of signals and forces across the meiotic prophase nuclear envelope.
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Affiliation(s)
- Shaun P. Murphy
- Institute of Molecular Biophysics, Florida State UniversityTallahassee, FL, USA
| | - Hardeep K. Gumber
- Department of Biological Science, Florida State UniversityTallahassee, FL, USA
| | - Yunyun Mao
- Department of Biological Science, Florida State UniversityTallahassee, FL, USA
| | - Hank W. Bass
- Institute of Molecular Biophysics, Florida State UniversityTallahassee, FL, USA
- Department of Biological Science, Florida State UniversityTallahassee, FL, USA
- *Correspondence: Hank W. Bass, Department of Biological Science, Florida State University, King Life Sciences Building, 319 Stadium Drive Tallahassee, FL 32306-4795, USA e-mail:
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