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Pócsi I, Szigeti ZM, Emri T, Boczonádi I, Vereb G, Szöllősi J. Use of red, far-red, and near-infrared light in imaging of yeasts and filamentous fungi. Appl Microbiol Biotechnol 2022; 106:3895-3912. [PMID: 35599256 PMCID: PMC9200671 DOI: 10.1007/s00253-022-11967-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 05/02/2022] [Accepted: 05/07/2022] [Indexed: 11/30/2022]
Abstract
Abstract While phototoxicity can be a useful therapeutic modality not only for eliminating malignant cells but also in treating fungal infections, mycologists aiming to observe morphological changes or molecular events in fungi, especially when long observation periods or high light fluxes are warranted, encounter problems owed to altered regulatory pathways or even cell death caused by various photosensing mechanisms. Consequently, the ever expanding repertoire of visible fluorescent protein toolboxes and high-resolution microscopy methods designed to investigate fungi in vitro and in vivo need to comply with an additional requirement: to decrease the unwanted side effects of illumination. In addition to optimizing exposure, an obvious solution is red-shifted illumination, which, however, does not come without compromises. This review summarizes the interactions of fungi with light and the various molecular biology and technology approaches developed for exploring their functions on the molecular, cellular, and in vivo microscopic levels, and outlines the progress towards reducing phototoxicity through applying far-red and near-infrared light. Key points • Fungal biological processes alter upon illumination, also under the microscope • Red shifted fluorescent protein toolboxes decrease interference by illumination • Innovations like two-photon, lightsheet, and near IR microscopy reduce phototoxicity
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Affiliation(s)
- István Pócsi
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary.
| | - Zsuzsa M Szigeti
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary
| | - Tamás Emri
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary
| | - Imre Boczonádi
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary
| | - György Vereb
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary.,MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary.,Faculty of Pharmacy, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary
| | - János Szöllősi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary.,MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Egyetem tér 1, 4032, Debrecen, Hungary
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King GA, Goodman JS, Schick JG, Chetlapalli K, Jorgens DM, McDonald KL, Ünal E. Meiotic cellular rejuvenation is coupled to nuclear remodeling in budding yeast. eLife 2019; 8:e47156. [PMID: 31397671 PMCID: PMC6711709 DOI: 10.7554/elife.47156] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 07/19/2019] [Indexed: 12/12/2022] Open
Abstract
Production of healthy gametes in meiosis relies on the quality control and proper distribution of both nuclear and cytoplasmic contents. Meiotic differentiation naturally eliminates age-induced cellular damage by an unknown mechanism. Using time-lapse fluorescence microscopy in budding yeast, we found that nuclear senescence factors - including protein aggregates, extrachromosomal ribosomal DNA circles, and abnormal nucleolar material - are sequestered away from chromosomes during meiosis II and subsequently eliminated. A similar sequestration and elimination process occurs for the core subunits of the nuclear pore complex in both young and aged cells. Nuclear envelope remodeling drives the formation of a membranous compartment containing the sequestered material. Importantly, de novo generation of plasma membrane is required for the sequestration event, preventing the inheritance of long-lived nucleoporins and senescence factors into the newly formed gametes. Our study uncovers a new mechanism of nuclear quality control and provides insight into its function in meiotic cellular rejuvenation.
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Affiliation(s)
- Grant A King
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
| | - Jay S Goodman
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
| | - Jennifer G Schick
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
| | - Keerthana Chetlapalli
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
| | - Danielle M Jorgens
- Electron Microscope LabUniversity of California, BerkeleyBerkeleyUnited States
| | - Kent L McDonald
- Electron Microscope LabUniversity of California, BerkeleyBerkeleyUnited States
| | - Elçin Ünal
- Department of Molecular and Cell BiologyUniversity of California, BerkeleyBerkeleyUnited States
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Yamamoto TG, Ding DQ, Nagahama Y, Chikashige Y, Haraguchi T, Hiraoka Y. Histone H2A insufficiency causes chromosomal segregation defects due to anaphase chromosome bridge formation at rDNA repeats in fission yeast. Sci Rep 2019; 9:7159. [PMID: 31073221 PMCID: PMC6509349 DOI: 10.1038/s41598-019-43633-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 04/28/2019] [Indexed: 11/16/2022] Open
Abstract
The nucleosome, composed of DNA and a histone core, is the basic structural unit of chromatin. The fission yeast Schizosaccharomyces pombe has two genes of histone H2A, hta1+ and hta2+; these genes encode two protein species of histone H2A (H2Aα and H2Aβ, respectively), which differ in three amino acid residues, and only hta2+ is upregulated during meiosis. However, it is unknown whether S. pombe H2Aα and H2Aβ have functional differences. Therefore, in this study, we examined the possible functional differences between H2Aα and H2Aβ during meiosis in S. pombe. We found that deletion of hta2+, but not hta1+, causes defects in chromosome segregation and spore formation during meiosis. Meiotic defects in hta2+ deletion cells were rescued by expressing additional copies of hta1+ or by expressing hta1+ from the hta2 promoter. This indicated that the defects were caused by insufficient amounts of histone H2A, and not by the amino acid residue differences between H2Aα and H2Aβ. Microscopic observation attributed the chromosome segregation defects to anaphase bridge formation in a chromosomal region at the repeats of ribosomal RNA genes (rDNA repeats). These results suggest that histone H2A insufficiency affects the chromatin structures of rDNA repeats, leading to chromosome missegregation in S. pombe.
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Affiliation(s)
- Takaharu G Yamamoto
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan
| | - Da-Qiao Ding
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan
| | - Yuki Nagahama
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan
| | - Yuji Chikashige
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan.,Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, 565-0871, Japan
| | - Yasushi Hiraoka
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan. .,Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, 565-0871, Japan.
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Nucleolar Division in the Promastigote Stage of Leishmania major Parasite: A Nop56 Point of View. BIOMED RESEARCH INTERNATIONAL 2018; 2018:1641839. [PMID: 30406129 PMCID: PMC6199852 DOI: 10.1155/2018/1641839] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 08/14/2018] [Accepted: 09/13/2018] [Indexed: 11/23/2022]
Abstract
Nucleogenesis is the cellular event responsible for the formation of the new nucleoli at the end of mitosis. This process depends on the synthesis and processing of ribosomal RNA (rRNA) and, in some eukaryotes, the transfer of nucleolar material contained in prenucleolar bodies (PNBs) to active transcription sites. The lack of a comprehensive description of the nucleolus throughout the cell cycle of the human pathogen Leishmania major prompted us to analyze the distribution of nucleolar protein 56 (Nop56) during interphase and mitosis in the promastigote stage of the parasite. By in silico analysis we show that the orthologue of Nop56 in L. major (LmNop56) contains the three characteristic Nop56 domains and that its predicted three-dimensional structure is also conserved. Fluorescence microscopy observations indicate that the nucleolar localization of LmNop56 is similar, but not identical, to that of the nucleolar protein Elp3b. Notably, unlike other nucleolar proteins, LmNop56 remains associated with the nucleolus in nonproliferative cells. Moreover, epifluorescent images indicate the preservation of the nucleolar structure throughout the closed nuclear division. Experiments performed with the related parasite Trypanosoma brucei show that nucleolar division is carried out by an analogous mechanism.
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Abstract
The Cas9 protein (CRISPR-associated protein 9), derived from type II CRISPR (clustered regularly interspaced short palindromic repeats) bacterial immune systems, is emerging as a powerful tool for engineering the genome in diverse organisms. As an RNA-guided DNA endonuclease, Cas9 can be easily programmed to target new sites by altering its guide RNA sequence, and its development as a tool has made sequence-specific gene editing several magnitudes easier. The nuclease-deactivated form of Cas9 further provides a versatile RNA-guided DNA-targeting platform for regulating and imaging the genome, as well as for rewriting the epigenetic status, all in a sequence-specific manner. With all of these advances, we have just begun to explore the possible applications of Cas9 in biomedical research and therapeutics. In this review, we describe the current models of Cas9 function and the structural and biochemical studies that support it. We focus on the applications of Cas9 for genome editing, regulation, and imaging, discuss other possible applications and some technical considerations, and highlight the many advantages that CRISPR/Cas9 technology offers.
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Affiliation(s)
- Haifeng Wang
- Department of Bioengineering, Stanford University, Stanford, California 94305; , ,
| | - Marie La Russa
- Department of Bioengineering, Stanford University, Stanford, California 94305; , ,
- Biomedical Sciences Graduate Program, University of California, San Francisco, California 94158
| | - Lei S Qi
- Department of Bioengineering, Stanford University, Stanford, California 94305; , ,
- Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305
- Chemistry, Engineering and Medicine for Human Health (ChEM-H), Stanford University, Stanford, California 94305
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Jin SH, Jang SC, Lee B, Jeong HH, Jeong SG, Lee SS, Kim KP, Lee CS. Monitoring of chromosome dynamics of single yeast cells in a microfluidic platform with aperture cell traps. LAB ON A CHIP 2016; 16:1358-1365. [PMID: 26980179 DOI: 10.1039/c5lc01422k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Chromosome movement plays important roles in DNA replication, repair, genetic recombination, and epigenetic phenomena during mitosis and meiosis. In particular, chromosome movement in the nuclear space is essential for the reorganization of the nucleus. However, conventional methods for analyzing the chromosome movements in vivo have been limited by technical constraints of cell trapping, cell cultivation, oxygenation, and in situ imaging. Here, we present a simple microfluidic platform with aperture-based cell trapping arrays to monitor the chromosome dynamics in single living cells for a desired period of time. Under the optimized conditions, our microfluidic platform shows a single-cell trapping efficiency of 57%. This microfluidic approach enables in situ imaging of intracellular dynamics in living cells responding to variable input stimuli under the well-controlled microenvironment. As a validation of this microfluidic platform, we investigate the fundamental features of the dynamic cellular response of the individual cells treated with different stimuli and drug. We prove the basis for dynamic chromosome movement in single yeast cells to be the telomere and nuclear envelope ensembles that attach to and move in concert with nuclear actin cables. Therefore, these results illustrate the monitoring of cellular functions and obtaining of dynamic information at a high spatiotemporal resolution through the integration of a simple microfluidic platform.
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Affiliation(s)
- Si Hyung Jin
- Department of Chemical Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-Gu, Daejeon 305-764, Republic of Korea.
| | - Sung-Chan Jang
- Department of Chemical Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-Gu, Daejeon 305-764, Republic of Korea.
| | - Byungjin Lee
- Department of Chemical Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-Gu, Daejeon 305-764, Republic of Korea.
| | - Heon-Ho Jeong
- Department of Chemical Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-Gu, Daejeon 305-764, Republic of Korea.
| | - Seong-Geun Jeong
- Department of Chemical Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-Gu, Daejeon 305-764, Republic of Korea.
| | - Sung Sik Lee
- Institute of Biochemistry, ETH Zürich, Zürich, CH 8093, Switzerland. leesu@ ethz.ch and Scientific Center for Optical and Electron Microscopy (ScopeM), ETH Zürich, Zürich, CH-8093, Switzerland
| | - Keun Pil Kim
- Department of Life Science, Chung-Ang University, Seoul 156-756, Republic of Korea
| | - Chang-Soo Lee
- Department of Chemical Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-Gu, Daejeon 305-764, Republic of Korea.
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Kruitwagen T, Denoth-Lippuner A, Wilkins BJ, Neumann H, Barral Y. Axial contraction and short-range compaction of chromatin synergistically promote mitotic chromosome condensation. eLife 2015; 4:e1039. [PMID: 26615018 PMCID: PMC4755758 DOI: 10.7554/elife.10396] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 11/27/2015] [Indexed: 11/16/2022] Open
Abstract
The segregation of eukaryotic chromosomes during mitosis requires their extensive folding into units of manageable size for the mitotic spindle. Here, we report on how phosphorylation at serine 10 of histone H3 (H3 S10) contributes to this process. Using a fluorescence-based assay to study local compaction of the chromatin fiber in living yeast cells, we show that chromosome condensation entails two temporally and mechanistically distinct processes. Initially, nucleosome-nucleosome interaction triggered by H3 S10 phosphorylation and deacetylation of histone H4 promote short-range compaction of chromatin during early anaphase. Independently, condensin mediates the axial contraction of chromosome arms, a process peaking later in anaphase. Whereas defects in chromatin compaction have no observable effect on axial contraction and condensin inactivation does not affect short-range chromatin compaction, inactivation of both pathways causes synergistic defects in chromosome segregation and cell viability. Furthermore, both pathways rely at least partially on the deacetylase Hst2, suggesting that this protein helps coordinating chromatin compaction and axial contraction to properly shape mitotic chromosomes. DOI:http://dx.doi.org/10.7554/eLife.10396.001 DNA in humans, yeast and other eukaryotic organisms is packaged in structures called chromosomes. When a cell divides these chromosomes are copied and then the matching pairs are separated so that each daughter cell has a full set of its genome. To enable these events to take place, the DNA must become more tightly packed so that the chromosomes become rigid units with projections called arms. Any failure in this chromosome “condensation” leads to the loss of chromosomes during cell division. Within a chromosome, sections of DNA are wrapped around groups of proteins to make a series of linked units called nucleosomes, which resemble beads on a string. These units and other scaffold proteins together make a structure called chromatin and establish the overall shape of the chromosome. However, it is not exactly clear how the nucleosomes and scaffold proteins are rearranged during condensation. Kruitwagen et al. used microscopy to study chromosome condensation in budding yeast. The experiments reveal that condensation involves two separate processes. First, modifications to the nucleosomes result in these units becoming more tightly packed in a process called short-range compaction. Second, a group of proteins called condensin is responsible for rearranging the compacted chromatin to enforce higher-order structure on the arms of the condensed chromosome (long-range contraction). Further experiments suggest that an enzyme called Hst2 may help to co-ordinate these processes to ensure that chromosomes adopt the right shape before the cell divides. For example, Hst2 ensures that longer chromosomes condense more than shorter ones. A future challenge will be to find out whether chromosome condensation works in a similar way in humans and other large eukaryotes, which form much larger chromosomes with more complicated structures than yeast. DOI:http://dx.doi.org/10.7554/eLife.10396.002
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Affiliation(s)
- Tom Kruitwagen
- Institute of Biochemistry, Department of Biology, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | - Annina Denoth-Lippuner
- Institute of Biochemistry, Department of Biology, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | - Bryan J Wilkins
- Free Floater (Junior) Research Group "Applied Synthetic Biology," Institute for Microbiology and Genetics, Georg- August University Göttingen, Göttingen, Germany
| | - Heinz Neumann
- Free Floater (Junior) Research Group "Applied Synthetic Biology," Institute for Microbiology and Genetics, Georg- August University Göttingen, Göttingen, Germany
| | - Yves Barral
- Institute of Biochemistry, Department of Biology, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
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Li P, Shao Y, Jin H, Yu HG. Ndj1, a telomere-associated protein, regulates centrosome separation in budding yeast meiosis. ACTA ACUST UNITED AC 2015; 209:247-59. [PMID: 25897084 PMCID: PMC4411264 DOI: 10.1083/jcb.201408118] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 03/16/2015] [Indexed: 11/22/2022]
Abstract
A refined spindle pole body (SPB) affinity purification method reveals that the telomere-associated protein Ndj1 also localizes to yeast SPBs, protects them from premature separation, and therefore regulates both SPB cohesion and telomere clustering during meiosis. Yeast centrosomes (called spindle pole bodies [SPBs]) remain cohesive for hours during meiotic G2 when recombination takes place. In contrast, SPBs separate within minutes after duplication in vegetative cells. We report here that Ndj1, a previously known meiosis-specific telomere-associated protein, is required for protecting SPB cohesion. Ndj1 localizes to the SPB but dissociates from it ∼16 min before SPB separation. Without Ndj1, meiotic SPBs lost cohesion prematurely, whereas overproduction of Ndj1 delayed SPB separation. When produced ectopically in vegetative cells, Ndj1 caused SPB separation defects and cell lethality. Localization of Ndj1 to the SPB depended on the SUN domain protein Mps3, and removal of the N terminus of Mps3 allowed SPB separation and suppressed the lethality of NDJ1-expressing vegetative cells. Finally, we show that Ndj1 forms oligomeric complexes with Mps3, and that the Polo-like kinase Cdc5 regulates Ndj1 protein stability and SPB separation. These findings reveal the underlying mechanism that coordinates yeast centrosome dynamics with meiotic telomere movement and cell cycle progression.
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Affiliation(s)
- Ping Li
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Yize Shao
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Hui Jin
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
| | - Hong-Guo Yu
- Department of Biological Science, Florida State University, Tallahassee, FL 32306
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Li P, Jin H, Yu HG. Condensin suppresses recombination and regulates double-strand break processing at the repetitive ribosomal DNA array to ensure proper chromosome segregation during meiosis in budding yeast. Mol Biol Cell 2014; 25:2934-47. [PMID: 25103240 PMCID: PMC4230583 DOI: 10.1091/mbc.e14-05-0957] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Condensin undergoes a sequestration, release, and reloading cycle at the rDNA array in budding yeast meiosis. It regulates rDNA stability by suppressing double-strand break (DSB) formation and promoting DSB processing. During meiosis, homologues are linked by crossover, which is required for bipolar chromosome orientation before chromosome segregation at anaphase I. The repetitive ribosomal DNA (rDNA) array, however, undergoes little or no meiotic recombination. Hyperrecombination can cause chromosome missegregation and rDNA copy number instability. We report here that condensin, a conserved protein complex required for chromosome organization, regulates double-strand break (DSB) formation and repair at the rDNA gene cluster during meiosis in budding yeast. Condensin is highly enriched at the rDNA region during prophase I, released at the prophase I/metaphase I transition, and reassociates with rDNA before anaphase I onset. We show that condensin plays a dual role in maintaining rDNA stability: it suppresses the formation of Spo11-mediated rDNA breaks, and it promotes DSB processing to ensure proper chromosome segregation. Condensin is unnecessary for the export of rDNA breaks outside the nucleolus but required for timely repair of meiotic DSBs. Our work reveals that condensin coordinates meiotic recombination with chromosome segregation at the repetitive rDNA sequence, thereby maintaining genome integrity.
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Affiliation(s)
- Ping Li
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370
| | - Hui Jin
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370
| | - Hong-Guo Yu
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370
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Sampaio TR, Pires LB, da Rosa R, Dias AL. Activity patterns of nucleolar organizer region during spermatogenesis of different curimatid species (Characiformes: Curimatidae). Genome 2014; 57:119-24. [DOI: 10.1139/gen-2013-0161] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The nucleolus is an important nuclear structure where transcription of ribosomal DNA (rDNA) takes place. During mitotic division, the nucleolus passes through different processes that inactivate rDNA transcription; in meiosis, its reassembly takes place during telophase II. The objective of this study was to identify the activity patterns and localization of nucleolar organizer regions (NORs) during meiotic division in fish species of the family Curimatidae. For this analysis, the meiotic division in five curimatid species was studied using silver nitrate impregnation, fluorescent in situ hybridization (FISH), and base-specific fluorochrome staining. Silver nitrate staining indicated the presence of a nucleolus in interphase nuclei, one chromosome pair in the spermatogonial metaphases, and one bivalent at the pachytene stage. No Ag-NORs were identified for cells at the diplotene, diakinesis, metaphase I, or metaphase II stages; however, FISH confirmed the presence of Ag-NORs in the nuclei, in spermatogonia, and at the pachytene phase. FISH identified this region during the other stages of meiosis, as did fluorochrome CMA3 staining, which revealed fluorescent marks corresponding to NORs during all stages of meiosis analyzed. The gene activity and localization of this ribosomal sequence during the different stages involved will also be discussed.
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Affiliation(s)
- Tatiane R. Sampaio
- Centro de Ciências Biológicas, Departamento de Biologia Geral, Universidade Estadual de Londrina, 86051-970, Londrina, Paraná, Brazil
| | - Larissa B. Pires
- Centro de Ciências Biológicas, Departamento de Biologia Geral, Universidade Estadual de Londrina, 86051-970, Londrina, Paraná, Brazil
| | - Renata da Rosa
- Centro de Ciências Biológicas, Departamento de Biologia Geral, Universidade Estadual de Londrina, 86051-970, Londrina, Paraná, Brazil
| | - Ana Lúcia Dias
- Centro de Ciências Biológicas, Departamento de Biologia Geral, Universidade Estadual de Londrina, 86051-970, Londrina, Paraná, Brazil
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