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Cromer L, Tiscareno-Andrade M, Lefranc S, Chambon A, Hurel A, Brogniez M, Guérin J, Le Masson I, Adam G, Charif D, Andrey P, Grelon M. Rapid meiotic prophase chromosome movements in Arabidopsis thaliana are linked to essential reorganization at the nuclear envelope. Nat Commun 2024; 15:5964. [PMID: 39013853 PMCID: PMC11252379 DOI: 10.1038/s41467-024-50169-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 07/02/2024] [Indexed: 07/18/2024] Open
Abstract
Meiotic rapid prophase chromosome movements (RPMs) require connections between the chromosomes and the cytoskeleton, involving SUN (Sad1/UNC-84)-domain-containing proteins at the inner nuclear envelope (NE). RPMs remain significantly understudied in plants, with respect to their importance in the regulation of meiosis. Here, we demonstrate that Arabidopsis thaliana meiotic centromeres undergo rapid (up to 500 nm/s) and uncoordinated movements during the zygotene and pachytene stages. These centromere movements are not affected by altered chromosome organization and recombination but are abolished in the double mutant sun1 sun2. We also document the changes in chromosome dynamics and nucleus organization during the transition from leptotene to zygotene, including telomere attachment to SUN-enriched NE domains, bouquet formation, and nucleolus displacement, all of which were defective in sun1 sun2. These results establish A. thaliana as a model species for studying the functional implications of meiotic RPMs and demonstrate the mechanistic conservation of telomere-led RPMs in plants.
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Affiliation(s)
- Laurence Cromer
- Université Paris-Saclay, INRAE, AgroParisTech, Institute Jean-Pierre Bourgin for Plant Sciences (IJPB), 78000, Versailles, France
| | - Mariana Tiscareno-Andrade
- Université Paris-Saclay, INRAE, AgroParisTech, Institute Jean-Pierre Bourgin for Plant Sciences (IJPB), 78000, Versailles, France
| | - Sandrine Lefranc
- Université Paris-Saclay, INRAE, AgroParisTech, Institute Jean-Pierre Bourgin for Plant Sciences (IJPB), 78000, Versailles, France
| | - Aurélie Chambon
- Université Paris-Saclay, INRAE, AgroParisTech, Institute Jean-Pierre Bourgin for Plant Sciences (IJPB), 78000, Versailles, France
| | - Aurélie Hurel
- Université Paris-Saclay, INRAE, AgroParisTech, Institute Jean-Pierre Bourgin for Plant Sciences (IJPB), 78000, Versailles, France
| | - Manon Brogniez
- Université Paris-Saclay, INRAE, AgroParisTech, Institute Jean-Pierre Bourgin for Plant Sciences (IJPB), 78000, Versailles, France
| | - Julie Guérin
- Université Paris-Saclay, INRAE, AgroParisTech, Institute Jean-Pierre Bourgin for Plant Sciences (IJPB), 78000, Versailles, France
| | - Ivan Le Masson
- Université Paris-Saclay, AgroParisTech, INRAE, UMR Agronomie, 91120, Palaiseau, France
| | - Gabriele Adam
- Université Paris-Saclay, CNRS, INRAE, Institute of Plant Sciences Paris-Saclay (IPS2), 91190, Gif sur Yvette, France
- Université Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91190, Gif sur Yvette, France
- Université Paris Cité, CNRS, INRAE, Institute of Plant Sciences Paris-Saclay (IPS2), 91190, Gif sur Yvette, France
| | - Delphine Charif
- Université Paris-Saclay, INRAE, AgroParisTech, Institute Jean-Pierre Bourgin for Plant Sciences (IJPB), 78000, Versailles, France
| | - Philippe Andrey
- Université Paris-Saclay, INRAE, AgroParisTech, Institute Jean-Pierre Bourgin for Plant Sciences (IJPB), 78000, Versailles, France
| | - Mathilde Grelon
- Université Paris-Saclay, INRAE, AgroParisTech, Institute Jean-Pierre Bourgin for Plant Sciences (IJPB), 78000, Versailles, France.
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2
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Kobayashi-Ooka Y, Ozoe F, Kawamukai M. Mutational analyses of the interacting domains of Schizosaccharomyces pombe Byr2 with 14-3-3s. Curr Genet 2024; 70:8. [PMID: 38913087 PMCID: PMC11196315 DOI: 10.1007/s00294-024-01293-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 06/10/2024] [Accepted: 06/16/2024] [Indexed: 06/25/2024]
Abstract
The Byr2 kinase of fission yeast Schizosaccharomyces pombe is recruited to the membrane with the assistance of Ras1. Byr2 is also negatively regulated by 14-3-3 proteins encoded by rad24 and rad25. We conducted domain and mutational analysis of Byr2 to determine which region is critical for its binding to 14-3-3 proteins. Rad24 and Rad25 bound to both the Ras interaction domain in the N-terminus and to the C-terminal catalytic domain of Byr2. When amino acid residues S87 and T94 of the Ras-interacting domain of Byr2 were mutated to alanine, Rad24 could no longer bind to Byr2. S402, S566, S650, and S654 mutations in the C-terminal domain of Byr2 also abolished its interaction with Rad24 and Rad25. More than three mutations in the C-terminal domain were required to abolish completely its interaction with 14-3-3 protein, suggesting that multiple residues are involved in this interaction. Expression of the N-terminal domain of Byr2 in wild-type cells lowered the mating ratio, because it likely blocked the interaction of Byr2 with Ste4 and Ras1, whereas expression of the catalytic domain of Byr2 increased the mating ratio as a result of freeing from intramolecular regulation by the N-terminal domain of Byr2. The S87A and T94A mutations of Byr2 increased the mating ratio and attenuated inhibition of Byr2 by Rad24; therefore, these two amino acids are critical for its regulation by Rad24. S566 of Byr2 is critical for activity of Byr2 but not for its interaction with 14-3-3 proteins. In this study, we show that 14-3-3 proteins interact with two separate domains in Byr2 as negative regulators.
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Affiliation(s)
- Yasuyo Kobayashi-Ooka
- Department of Life Sciences, Faculty of Life and Environmental Sciences, Shimane University, 1060 Nishikawatsu, Matsue, 690-8504, Japan
- Nitto Denko Corporation Ibaraki Plant, 1-1-2, Shimohozumi, Ibaraki, Osaka, 567-8680, Japan
| | - Fumiyo Ozoe
- Department of Life Sciences, Faculty of Life and Environmental Sciences, Shimane University, 1060 Nishikawatsu, Matsue, 690-8504, Japan
| | - Makoto Kawamukai
- Department of Life Sciences, Faculty of Life and Environmental Sciences, Shimane University, 1060 Nishikawatsu, Matsue, 690-8504, Japan.
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3
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Kawamukai M. Regulation of sexual differentiation initiation in Schizosaccharomyces pombe. Biosci Biotechnol Biochem 2024; 88:475-492. [PMID: 38449372 DOI: 10.1093/bbb/zbae019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 02/05/2024] [Indexed: 03/08/2024]
Abstract
The fission yeast Schizosaccharomyces pombe is an excellent model organism to explore cellular events owing to rich tools in genetics, molecular biology, cellular biology, and biochemistry. Schizosaccharomyces pombe proliferates continuously when nutrients are abundant but arrests in G1 phase upon depletion of nutrients such as nitrogen and glucose. When cells of opposite mating types are present, cells conjugate, fuse, undergo meiosis, and finally form 4 spores. This sexual differentiation process in S. pombe has been studied extensively. To execute sexual differentiation, the glucose-sensing cAMP-PKA (cyclic adenosine monophosphate-protein kinase A) pathway, nitrogen-sensing TOR (target of rapamycin) pathway, and SAPK (stress-activating protein kinase) pathway are crucial, and the MAPK (mitogen-activating protein kinase) cascade is essential for pheromone sensing. These signals regulate ste11 at the transcriptional and translational levels, and Ste11 is modified in multiple ways. This review summarizes the initiation of sexual differentiation in S. pombe based on results I have helped to obtain, including the work of many excellent researchers.
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Affiliation(s)
- Makoto Kawamukai
- D epartment of Life Sciences, Faculty of Life and Environmental Sciences, Shimane University, Nishikawatsu, Matsue, Japan
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4
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Ohshima T, Jiajun Z, Fukamachi T, Ohno Y, Senoo H, Matsuo Y, Kawamukai M. A dominant negative 14-3-3 mutant in Schizosaccharomyces pombe distinguishes the binding proteins involved in sexual differentiation and check point. PLoS One 2023; 18:e0291524. [PMID: 37788281 PMCID: PMC10547172 DOI: 10.1371/journal.pone.0291524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 08/30/2023] [Indexed: 10/05/2023] Open
Abstract
The homothallic fission yeast Schizosaccharomyces pombe undergoes sexual differentiation when starved, but sam (skips the requirement of starvation for mating) mutants such as those carrying mutations in adenylate cyclase (cyr1) or protein kinase A (pka1) mate without starvation. Here, we identified sam3, a dominant negative allele of rad24, encoding one of two 14-3-3 proteins. Genetic mapping and whole-genome sequencing showed that the sam3 mutation comprises a change in nucleotide at position 959 from guanine to adenine, which switches the amino acid at position 185 from glutamic acid to lysine (E185K). We generated the rad24-E185K integrated mutant and its phenotype was similar to that of the sam3 mutant, including calcium sensitivity and UV non-sensitivity, but the phenotype is different from that of the Δrad24 strain. While the UV-sensitive phenotype was observed in the Δrad24 mutant, it was not observed in the sam3 and rad24-E185K mutants. The expression of the rad24-E185K gene in wild type cells induced spore formation in the nutrient rich medium, confirming rad24-E185K is dominant. This dominant effect of rad24-E185K was also observed in Δras1 and Δbyr2 diploid mutants, indicating that rad24-E185K generate stronger phenotype than rad24 null mutants. Ste11, the key transcription factor for sexual differentiation was expressed in sam3 mutants without starvation and it predominantly localized to the nucleus. The Rad24-E185K mutant protein retained its interaction with Check point kinase1 (Chk1), whereas it reduced interaction with Ste11, an RNA binding protein Mei2, and a MAPKKK Byr2, freeing these proteins from negative regulation by Rad24, that account for the sam phenotype and UV non-sensitive phenotype. Glucose depletion in rad24-E185K or Δpka1 Δrad24 double mutation induced haploid meiosis, leading to the formation of spores in haploid. The position of glutamic acid 185 is conserved in all major 14-3-3s; hence, our finding of a dominant negative allele of 14-3-3 is useful for understanding 14-3-3s in other organisms.
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Affiliation(s)
- Tomohito Ohshima
- Faculty of Life and Environmental Sciences, Department of Life Sciences, Shimane University, Matsue, Shimane, Japan
| | - Zhang Jiajun
- Faculty of Life and Environmental Sciences, Department of Life Sciences, Shimane University, Matsue, Shimane, Japan
| | - Takuki Fukamachi
- Faculty of Life and Environmental Sciences, Department of Life Sciences, Shimane University, Matsue, Shimane, Japan
| | - Yuko Ohno
- Faculty of Life and Environmental Sciences, Department of Life Sciences, Shimane University, Matsue, Shimane, Japan
| | - Hiroko Senoo
- Faculty of Life and Environmental Sciences, Department of Life Sciences, Shimane University, Matsue, Shimane, Japan
| | - Yasuhiro Matsuo
- Faculty of Life and Environmental Sciences, Department of Life Sciences, Shimane University, Matsue, Shimane, Japan
| | - Makoto Kawamukai
- Faculty of Life and Environmental Sciences, Department of Life Sciences, Shimane University, Matsue, Shimane, Japan
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5
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Mixing and Matching Chromosomes during Female Meiosis. Cells 2020; 9:cells9030696. [PMID: 32178277 PMCID: PMC7140621 DOI: 10.3390/cells9030696] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 03/08/2020] [Accepted: 03/11/2020] [Indexed: 01/17/2023] Open
Abstract
Meiosis is a key event in the manufacturing of an oocyte. During this process, the oocyte creates a set of unique chromosomes by recombining paternal and maternal copies of homologous chromosomes, and by eliminating one set of chromosomes to become haploid. While meiosis is conserved among sexually reproducing eukaryotes, there is a bewildering diversity of strategies among species, and sometimes within sexes of the same species, to achieve proper segregation of chromosomes. Here, we review the very first steps of meiosis in females, when the maternal and paternal copies of each homologous chromosomes have to move, find each other and pair. We explore the similarities and differences observed in C. elegans, Drosophila, zebrafish and mouse females.
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6
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Huraiova B, Pozgajova M, Gregan J. Sexual Reproduction: Preventing Re-fertilization in Fission Yeast. Curr Biol 2018; 28:R1300-R1303. [PMID: 30458148 DOI: 10.1016/j.cub.2018.09.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
During sexual reproduction, two haploid cells fuse to produce a diploid cell called a zygote. A new study describes how fission yeast prevents a zygote from being formed by the fusion of more than two cells.
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Affiliation(s)
- Barbora Huraiova
- Department of Genetics, Comenius University, Ilkovicova 6, 84215 Bratislava, Slovak Republic
| | - Miroslava Pozgajova
- AgroBioTech Research Centre, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 94976 Nitra, Slovakia
| | - Juraj Gregan
- Department of Genetics, Comenius University, Ilkovicova 6, 84215 Bratislava, Slovak Republic; Advanced Microscopy Facility, Vienna Biocenter Core Facilities, Dr. Bohr-Gasse 3, 1030 Vienna, Austria; Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria.
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Vještica A, Merlini L, Nkosi PJ, Martin SG. Gamete fusion triggers bipartite transcription factor assembly to block re-fertilization. Nature 2018; 560:397-400. [PMID: 30089908 DOI: 10.1038/s41586-018-0407-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 06/25/2018] [Indexed: 02/08/2023]
Abstract
The ploidy cycle, which is integral to sexual reproduction, requires meiosis to halve chromosome numbers as well as mechanisms that ensure zygotes are formed by exactly two partners1-4. During sexual reproduction of the fungal model organism Schizosaccharomyces pombe, haploid P and M cells fuse to form a diploid zygote that immediately enters meiosis5. Here we reveal that rapid post-fusion reconstitution of a bipartite transcription factor blocks re-fertilization. We first identify mutants that undergo transient cell fusion involving cytosol exchange but not karyogamy, and show that this drives distinct cell fates in the two gametes. The P partner undergoes lethal haploid meiosis, whereas the M cell persists in mating. The zygotic transcription that drives meiosis is rapidly initiated first from the P parental genome, even in wild-type cells. This asymmetric gene expression depends on a bipartite complex formed post-fusion between the cytosolic M-cell-specific peptide Mi and the nuclear P-cell-specific homeobox protein Pi6,7, which captures Mi in the P nucleus. Zygotic transcription is thus poised to initiate in the P nucleus as fast as Mi reaches it after fusion, a design that we reconstruct using two synthetic interactors localized to the nucleus and the cytosol of two respective partner cells. Notably, delaying zygotic transcription-by postponing Mi expression or deleting its transcriptional target in the P genome-leads to zygotes fusing with additional gametes, thus forming polyploids and eventually aneuploid progeny. The signalling cascade to block re-fertilization shares components with, but bifurcates from, meiotic induction8-10. Thus, a cytoplasmic connection upon gamete fusion leads to asymmetric reconstitution of a bipartite transcription factor to rapidly block re-fertilization and induce meiosis, ensuring genome maintenance during sexual reproduction.
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Affiliation(s)
- Aleksandar Vještica
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Laura Merlini
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Pedro Junior Nkosi
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Sophie G Martin
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland.
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8
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Yamashita A, Sakuno T, Watanabe Y, Yamamoto M. Analysis of Schizosaccharomyces pombe Meiosis. Cold Spring Harb Protoc 2017; 2017:pdb.top079855. [PMID: 28733417 DOI: 10.1101/pdb.top079855] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Meiosis is a specialized cell cycle that generates haploid gametes from diploid cells. The fission yeast Schizosaccharomyces pombe is one of the best model organisms for studying the regulatory mechanisms of meiosis. S. pombe cells, which normally grow in the haploid state, diploidize by conjugation and initiate meiosis when starved for nutrients, especially nitrogen. Following two rounds of chromosome segregation, spore formation takes place. The switch from mitosis to meiosis is controlled by a kinase, Pat1, and an RNA-binding protein, Mei2. Mei2 is also a key factor for meiosis-specific gene expression. Studies on S. pombe have offered insights into cell cycle regulation and chromosome segregation during meiosis. Here we outline the current understanding of the molecular mechanisms regulating the initiation and progression of meiosis, and introduce methods for the study of meiosis in fission yeast.
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Affiliation(s)
- Akira Yamashita
- Laboratory of Cell Responses, National Institute for Basic Biology, Okazaki, Aichi, 444-8585, Japan;
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Takeshi Sakuno
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi, Tokyo 113-0032, Japan
| | - Yoshinori Watanabe
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi, Tokyo 113-0032, Japan
| | - Masayuki Yamamoto
- Laboratory of Cell Responses, National Institute for Basic Biology, Okazaki, Aichi, 444-8585, Japan;
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Myodaiji, Okazaki, Aichi 444-8585, Japan
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9
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Katsumata K, Nishi E, Afrin S, Narusawa K, Yamamoto A. Position matters: multiple functions of LINC-dependent chromosome positioning during meiosis. Curr Genet 2017; 63:1037-1052. [PMID: 28493118 DOI: 10.1007/s00294-017-0699-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 04/14/2017] [Accepted: 04/29/2017] [Indexed: 10/19/2022]
Abstract
Chromosome positioning is crucial for multiple chromosomal events, including DNA replication, repair, and recombination. The linker of nucleoskeleton and cytoskeleton (LINC) complexes, which consist of conserved nuclear membrane proteins, were shown to control chromosome positioning and facilitate various biological processes by interacting with the cytoskeleton. However, the precise functions and regulation of LINC-dependent chromosome positioning are not fully understood. During meiosis, the LINC complexes induce clustering of telomeres, forming the bouquet chromosome arrangement, which promotes homologous chromosome pairing. In fission yeast, the bouquet forms through LINC-dependent clustering of telomeres at the spindle pole body (SPB, the centrosome equivalent in fungi) and detachment of centromeres from the SPB-localized LINC. It was recently found that, in fission yeast, the bouquet contributes to formation of the spindle and meiotic centromeres, in addition to homologous chromosome pairing, and that centromere detachment is linked to telomere clustering, which is crucial for proper spindle formation. Here, we summarize these findings and show that the bouquet chromosome arrangement also contributes to nuclear fusion during karyogamy. The available evidence suggests that these functions are universal among eukaryotes. The findings demonstrate that LINC-dependent chromosome positioning performs multiple functions and controls non-chromosomal as well as chromosomal events, and that the chromosome positioning is stringently regulated for its functions. Thus, chromosome positioning plays a much broader role and is more strictly regulated than previously thought.
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Affiliation(s)
- Kazuhiro Katsumata
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Eriko Nishi
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Sadia Afrin
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Kaoru Narusawa
- Department of Chemistry, Faculty of Science, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Ayumu Yamamoto
- Department of Science, Graduate School of Integrated Science and Technology, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka, 422-8529, Japan.
- Department of Chemistry, Faculty of Science, Shizuoka University, Ohya 836, Suruga-ku, Shizuoka, 422-8529, Japan.
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A Taz1- and Microtubule-Dependent Regulatory Relationship between Telomere and Centromere Positions in Bouquet Formation Secures Proper Meiotic Divisions. PLoS Genet 2016; 12:e1006304. [PMID: 27611693 PMCID: PMC5017736 DOI: 10.1371/journal.pgen.1006304] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 08/17/2016] [Indexed: 01/01/2023] Open
Abstract
During meiotic prophase, telomeres cluster, forming the bouquet chromosome arrangement, and facilitate homologous chromosome pairing. In fission yeast, bouquet formation requires switching of telomere and centromere positions. Centromeres are located at the spindle pole body (SPB) during mitotic interphase, and upon entering meiosis, telomeres cluster at the SPB, followed by centromere detachment from the SPB. Telomere clustering depends on the formation of the microtubule-organizing center at telomeres by the linker of nucleoskeleton and cytoskeleton complex (LINC), while centromere detachment depends on disassembly of kinetochores, which induces meiotic centromere formation. However, how the switching of telomere and centromere positions occurs during bouquet formation is not fully understood. Here, we show that, when impaired telomere interaction with the LINC or microtubule disruption inhibited telomere clustering, kinetochore disassembly-dependent centromere detachment and accompanying meiotic centromere formation were also inhibited. Efficient centromere detachment required telomere clustering-dependent SPB recruitment of a conserved telomere component, Taz1, and microtubules. Furthermore, when artificial SPB recruitment of Taz1 induced centromere detachment in telomere clustering-defective cells, spindle formation was impaired. Thus, detachment of centromeres from the SPB without telomere clustering causes spindle impairment. These findings establish novel regulatory mechanisms, which prevent concurrent detachment of telomeres and centromeres from the SPB during bouquet formation and secure proper meiotic divisions. Meiosis is a type of cell division, that generates haploid gametes and is essential for sexual reproduction. During meiosis, telomeres cluster on a small region of the nuclear periphery, forming a conserved chromosome arrangement referred to as the “bouquet”. Because the bouquet arrangement facilitates homologous chromosome pairing, which is essential for proper meiotic chromosome segregation, it is of great importance to understand how the bouquet arrangement is formed. In fission yeast, the bouquet arrangement requires switching of telomere and centromere positions. During mitosis, centromeres are located at the fungal centrosome called the spindle pole body (SPB). Upon entering meiosis, telomeres cluster at the SPB, and centromeres become detached from the SPB, forming the bouquet arrangement. In this study, we show that centromere detachment is linked with telomere clustering. When telomere clustering was inhibited, centromere detachment was also inhibited. This regulatory relationship depended on a conserved telomere component, Taz1, and microtubules. Furthermore, we show that the regulatory relationship is crucial for proper meiotic divisions when telomere clustering is defective. Our findings reveal a hitherto unknown regulatory relationship between meiotic telomere and centromere positions in bouquet formation, which secures proper meiotic divisions.
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Shichino Y, Yamashita A, Yamamoto M. Meiotic long non-coding meiRNA accumulates as a dot at its genetic locus facilitated by Mmi1 and plays as a decoy to lure Mmi1. Open Biol 2015; 4:140022. [PMID: 24920274 PMCID: PMC4077057 DOI: 10.1098/rsob.140022] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Long non-coding RNAs (lncRNAs) play key roles in the formation of nuclear bodies. In the fission yeast Schizosaccharomyces pombe, a lncRNA species termed meiRNA forms a nuclear dot structure at its own genetic locus, the sme2 locus, with its protein-binding partner Mei2. This dot structure, called Mei2 dot, promotes the progression of meiosis by suppressing Mmi1, a crucial factor involved in the selective elimination of meiosis-specific transcripts. The meiRNA itself is a target of Mmi1-mediated elimination and is supposed to function as a decoy to lure Mmi1. However, detailed mechanisms underlying the formation of Mei2 dot and inactivation of Mmi1 remain ambiguous. Here, we show that the localization of meiRNA, at its genetic locus sme2, depends on its association with Mmi1. We also demonstrate that one of the multiple Mmi1 foci in mitotic cells localizes to the sme2 locus. Furthermore, the overexpression of meiRNA promotes the accumulation of Mmi1 to the sme2 locus even in the absence of Mei2 and reduces the activity of Mmi1. These findings indicate that the retention of meiRNA at its genetic locus is facilitated by Mmi1, which then attracts scattered Mmi1 to inhibit its function.
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Affiliation(s)
- Yuichi Shichino
- Laboratory of Gene Function, Kazusa DNA Research Institute, 2-6-7 Kazusa-kamatari, Kisarazu, Chiba 292-0818, Japan Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Hongo, Tokyo 113-0033, Japan
| | - Akira Yamashita
- Laboratory of Gene Function, Kazusa DNA Research Institute, 2-6-7 Kazusa-kamatari, Kisarazu, Chiba 292-0818, Japan Laboratory of Cell Responses, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Masayuki Yamamoto
- Laboratory of Gene Function, Kazusa DNA Research Institute, 2-6-7 Kazusa-kamatari, Kisarazu, Chiba 292-0818, Japan Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Hongo, Tokyo 113-0033, Japan Laboratory of Cell Responses, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, Aichi 444-8585, Japan
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12
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Abstract
Sexual reproduction is a fundamental aspect of eukaryotic cells, and a conserved feature of gametogenesis is its dependency on a master regulator. The ste11 gene was isolated more than 20 years ago by the Yamamoto laboratory as a suppressor of the uncontrolled meiosis driven by a pat1 mutant. Numerous studies from this laboratory and others have established the role of the Ste11 transcription factor as the master regulator of the switch between proliferation and differentiation in fission yeast. The transcriptional and post-transcriptional controls of ste11 expression are intricate, but most are not redundant. Whereas the transcriptional controls ensure that the gene is transcribed at a high level only when nutrients are rare, the post-transcriptional controls restrict the ability of Ste11 to function as a transcription factor to the G1-phase of the cell cycle from where the differentiation programme is initiated. Several feedback loops ensure that the cell fate decision is irreversible. The complete panel of molecular mechanisms operating to warrant the timely expression of the ste11 gene and its encoded protein basically mirrors the advances in the understanding of the numerous ways by which gene expression can be modulated.
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13
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Arslanyolu M, Yıldız MT. Cloning, expression and characterization of a gene encoding mitogen activated protein kinase 2 (MPK2) from Tetrahymena thermophila. Gene 2014; 546:40-9. [PMID: 24858074 DOI: 10.1016/j.gene.2014.05.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Revised: 05/13/2014] [Accepted: 05/20/2014] [Indexed: 10/25/2022]
Abstract
Environmental effects and mitogens determine cell phenotype in eukaryotes mainly through MAPK pathways. However, MAPK signaling pathways in T. thermophila have not been studied comprehensively. This study aims to express recombinant MPK2, a MAPK from T. thermophila, in E. coli to characterize its kinase activity. MPK2 was cloned by RT-PCR using degenerate oligonucleotide primers and RACE method. The full-length cDNA of the MPK2 gene is 1705bp that includes 1281bp ORF coding for a putative protein of 426 amino acids having a mass of 50.2kDa. The putative MPK2 protein contains all eleven conserved subdomains that are characteristics of serine/threonine protein kinases, and a TDY motif, which is a putative dual phosphorylation site common in Protista. MPK2 displays highest 48% overall identity to human ERK5 (MAPK7). The expression vector pGEX4T-1-MPK2 was constructed by inserting the coding region of MPK2 cDNA into pGEX4T-1 after introducing the nine point mutations, and then transformed into E. coli BL21(DE3). Autophosphorylation of 76kDa GST-MPK2 at tyrosine residues was confirmed not only by Western blot using anti-phosphotyrosine monoclonal antibody but also by in vitro kinase assay. GST-MPK2 was also able to phosphorylate the artificial substrate myelin basic protein. This study concludes that the free-living unicellular protist T. thermophila MPK2 has commonly conserved MAPK enzyme features, possibly involved in the regulation of cell survival responding to abiotic or biotic stressors, and the production and movement of haploid gametic nuclei between pairs during conjugation.
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Affiliation(s)
- Muhittin Arslanyolu
- Anadolu University, Faculty of Sciences, Department of Biology, Yunusemre Campus, 26470 Eskisehir Turkey.
| | - Mehmet Taha Yıldız
- Fatih University, Faculty of Sciences, Department of Biology, Buyukcekmece Campus, 34500 Istanbul, Turkey.
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Synchronized fission yeast meiosis using an ATP analog-sensitive Pat1 protein kinase. Nat Protoc 2014; 9:223-31. [PMID: 24385151 DOI: 10.1038/nprot.2014.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Synchronous cultures are often indispensable for studying meiosis. Here we present an optimized protocol for induction of synchronous meiosis in the fission yeast Schizosaccharomyces pombe. Chemical inactivation of an ATP analog-sensitive form of the Pat1 kinase (pat1-as2) by adding the ATP analog 1-NM-PP1 in G1-arrested cells allows the induction of synchronous meiosis at optimal temperature (25°C). Importantly, this protocol eliminates detrimental effects of elevated temperature (34°C), which is required to inactivate the commonly used temperature-sensitive Pat1 kinase mutant (pat1-114). The addition of the mat-Pc gene to a mat1-M strain further improves chromosome segregation and spore viability. Thus, our protocol offers highly synchronous meiosis at optimal temperature, with most characteristics similar to those of wild-type meiosis. The synchronization protocol can be completed in 5 d (not including strain production, which may take as long as 2 or 3 months).
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15
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Miller MP, Amon A, Ünal E. Meiosis I: when chromosomes undergo extreme makeover. Curr Opin Cell Biol 2013; 25:687-96. [PMID: 23916768 PMCID: PMC3836829 DOI: 10.1016/j.ceb.2013.07.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 07/02/2013] [Accepted: 07/15/2013] [Indexed: 12/01/2022]
Abstract
The ultimate success of cell division relies on the accurate partitioning of the genetic material. Errors in this process occur in nearly all tumors and are the leading cause of miscarriages and congenital birth defects in humans. Two cell divisions, mitosis and meiosis, use common as well as unique mechanisms to ensure faithful chromosome segregation. In mitosis, alternating rounds of DNA replication and chromosome segregation preserve the chromosome complement of the progenitor cell. In contrast, during meiosis two consecutive rounds of nuclear division, meiosis I and meiosis II, follow a single round of DNA replication to reduce the chromosome complement by half. Meiosis likely evolved through changes to the mitotic cell division program. This review will focus on the recent findings describing the modifications that transform mitosis into meiosis.
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Affiliation(s)
- Matthew P. Miller
- Koch Institute for Integrative Cancer Biology, Massachusetts Institute of Technology, Cambridge MA, USA
- Howard Hughes Medical Institute
| | - Angelika Amon
- Koch Institute for Integrative Cancer Biology, Massachusetts Institute of Technology, Cambridge MA, USA
- Howard Hughes Medical Institute
| | - Elçin Ünal
- Koch Institute for Integrative Cancer Biology, Massachusetts Institute of Technology, Cambridge MA, USA
- Howard Hughes Medical Institute
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Miller MP, Unal E, Brar GA, Amon A. Meiosis I chromosome segregation is established through regulation of microtubule-kinetochore interactions. eLife 2012; 1:e00117. [PMID: 23275833 PMCID: PMC3525924 DOI: 10.7554/elife.00117] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 10/18/2012] [Indexed: 11/13/2022] Open
Abstract
During meiosis, a single round of DNA replication is followed by two consecutive rounds of nuclear divisions called meiosis I and meiosis II. In meiosis I, homologous chromosomes segregate, while sister chromatids remain together. Determining how this unusual chromosome segregation behavior is established is central to understanding germ cell development. Here we show that preventing microtubule-kinetochore interactions during premeiotic S phase and prophase I is essential for establishing the meiosis I chromosome segregation pattern. Premature interactions of kinetochores with microtubules transform meiosis I into a mitosis-like division by disrupting two key meiosis I events: coorientation of sister kinetochores and protection of centromeric cohesin removal from chromosomes. Furthermore we find that restricting outer kinetochore assembly contributes to preventing premature engagement of microtubules with kinetochores. We propose that inhibition of microtubule-kinetochore interactions during premeiotic S phase and prophase I is central to establishing the unique meiosis I chromosome segregation pattern.DOI:http://dx.doi.org/10.7554/eLife.00117.001.
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Affiliation(s)
- Matthew P Miller
- Department of Biology , Massachusetts Institute of Technology , Cambridge , United States
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Zhang H, Li D, Wang M, Liu J, Teng W, Cheng B, Huang Q, Wang M, Song W, Dong S, Zheng X, Zhang Z. The Nicotiana benthamiana mitogen-activated protein kinase cascade and WRKY transcription factor participate in Nep1(Mo)-triggered plant responses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:1639-53. [PMID: 22835275 DOI: 10.1094/mpmi-11-11-0293] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Many bacterial, fungal, and oomycete species secrete necrosis and ethylene-inducing peptide 1 (Nep1)-like proteins (NLP) that trigger programmed cell death (PCD) and innate immune responses in dicotyledonous plants. However, how NLP induce such immune responses is not understood. Here, we show that silencing of the MAPKKKα-MEK2-WIPK mitogen-activated protein kinase (MAPK) cascade through virus-induced gene silencing compromises hydrogen peroxide accumulation and PCD induced by Nep1(Mo) from Magnaporthe oryzae. WIPK interacts with NbWRKY2, a transcription factor in Nicotiana benthamiana, in vitro and in vivo, suggesting an effector pathway that mediates Nep1(Mo)-induced cell death. Unexpectedly, salicylic acid-induced protein kinase (SIPK)- and NbWRKY2-silenced plants showed impaired Nep1(Mo)-induced stomatal closure, decreased Nep1(Mo)-promoted nitric oxide (NO) production in guard cells, and a reduction in Nep1(Mo)-induced resistance against Phytophthora nicotianae. Expression studies by real-time polymerase chain reaction suggested that the MEK2-WIPK-NbWRKY2 pathway regulated Nep1(Mo)triggered NO accumulation could be partly dependent on nitrate reductase, which was implicated in NO synthesis. Taken together, these studies demonstrate that the MAPK cascade is involved in Nep1(Mo)-triggered plant responses and MAPK signaling associated with PCD exhibits shared and distinct components with that for stomatal closure.
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Affiliation(s)
- Huajian Zhang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China
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Kim L, Hoe KL, Yu YM, Yeon JH, Maeng PJ. The fission yeast GATA factor, Gaf1, modulates sexual development via direct down-regulation of ste11+ expression in response to nitrogen starvation. PLoS One 2012; 7:e42409. [PMID: 22900017 PMCID: PMC3416868 DOI: 10.1371/journal.pone.0042409] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 07/04/2012] [Indexed: 11/26/2022] Open
Abstract
Gaf1 is the first GATA family zinc-finger transcription factor identified in Schizosaccharomyces pombe. Here, we report that Gaf1 functions as a negatively acting transcription factor of ste11+, delaying the entrance of cells exposed to transient nitrogen starvation into the meiotic cycle. gaf1Δ strains exhibited accelerated G1-arrest upon nitrogen starvation. Moreover, gaf1Δ mutation caused increased mating and sporulation frequency under both nitrogen-starved and unstarved conditions, while overexpression of gaf1+ led to a significant impairment of sporulation. By microarray analysis, we found that approximately 63% (116 genes) of the 183 genes up-regulated in unstarved gaf1Δ cells were nitrogen starvation-responsive genes, and furthermore that 25 genes among the genes up-regulated by gaf1Δ mutation are Ste11 targets (e.g., gpa1+, ste4+, spk1+, ste11+, and mei2+). The phenotype caused by gaf1Δ mutation was masked by ste11Δ mutation, indicating that ste11+ is epistatic to gaf1+ with respect to sporulation efficiency, and accordingly that gaf1+ functions upstream of ste11+ in the signaling pathway governing sexual development. gaf1Δ strains showed accelerated ste11+ expression under nitrogen starvation and increased ste11+ expression even under normal conditions. Electrophoretic mobility shift assay analysis demonstrated that Gaf1 specifically binds to the canonical GATA motif (5′-HGATAR-3′) spanning from −371 to −366 in ste11+ promoter. Consequently, Gaf1 provides the prime example for negative regulation of ste11+ transcription through direct binding to a cis-acting motif of its promoter.
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Affiliation(s)
- Lila Kim
- Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, Korea
| | - Kwang-Lae Hoe
- Graduate School of New Drug Discovery and Development, Chungnam National University, Daejeon, Korea
| | - Yeong Man Yu
- Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, Korea
| | - Ji-Hyun Yeon
- Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, Korea
| | - Pil Jae Maeng
- Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, Korea
- * E-mail:
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Affiliation(s)
- Hiroshi Murakami
- Department of Regulatory Biology; Graduate School of Science and Engineering; Saitama University; Saitama, Japan.
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Ohta M, Sato M, Yamamoto M. Spindle pole body components are reorganized during fission yeast meiosis. Mol Biol Cell 2012; 23:1799-811. [PMID: 22438582 PMCID: PMC3350546 DOI: 10.1091/mbc.e11-11-0951] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We show that spindle pole body (SPB) remodeling during meiosis in fission yeast is essential for meiosis. Many SPB components disappear during meiotic prophase and return to the SPBs at meiosis I onset. We found novel functions for Polo kinase/Plo1 and centrin/Cdc31 in the meiotic reorganization of SPB components. During meiosis, the centrosome/spindle pole body (SPB) must be regulated in a manner distinct from that of mitosis to achieve a specialized cell division that will produce gametes. In this paper, we demonstrate that several SPB components are localized to SPBs in a meiosis-specific manner in the fission yeast Schizosaccharomyces pombe. SPB components, such as Cut12, Pcp1, and Spo15, which stay on the SPB during the mitotic cell cycle, disassociate from the SPB during meiotic prophase and then return to the SPB immediately before the onset of meiosis I. Interestingly, the polo kinase Plo1, which normally localizes to the SPB during mitosis, is excluded from them in meiotic prophase, when meiosis-specific, horse-tail nuclear movement occurs. We found that exclusion of Plo1 during this period was essential to properly remodel SPBs, because artificial targeting of Plo1 to SPBs resulted in an overduplication of SPBs. We also found that the centrin Cdc31 was required for meiotic SPB remodeling. Thus Plo1 and a centrin play central roles in the meiotic SPB remodeling, which is essential for generating the proper number of meiotic SPBs and, thereby provide unique characteristics to meiotic divisions.
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Affiliation(s)
- Midori Ohta
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Tokyo, Japan
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21
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Funaya C, Samarasinghe S, Pruggnaller S, Ohta M, Connolly Y, Müller J, Murakami H, Grallert A, Yamamoto M, Smith D, Antony C, Tanaka K. Transient structure associated with the spindle pole body directs meiotic microtubule reorganization in S. pombe. Curr Biol 2012; 22:562-74. [PMID: 22425159 PMCID: PMC3382715 DOI: 10.1016/j.cub.2012.02.042] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 02/10/2012] [Accepted: 02/17/2012] [Indexed: 02/06/2023]
Abstract
Background Vigorous chromosome movements driven by cytoskeletal assemblies are a widely conserved feature of sexual differentiation to facilitate meiotic recombination. In fission yeast, this process involves the dramatic conversion of arrays of cytoplasmic microtubules (MTs), generated from multiple MT organizing centers (MTOCs), into a single radial MT (rMT) array associated with the spindle pole body (SPB), the major MTOC during meiotic prophase. The rMT is then dissolved upon the onset of meiosis I when a bipolar spindle emerges to conduct chromosome segregation. Structural features and molecular mechanisms that govern these dynamic MT rearrangements are poorly understood. Results Electron tomography of the SPBs showed that the rMT emanates from a newly recognized amorphous structure, which we term the rMTOC. The rMTOC, which resides at the cytoplasmic side of the SPB, is highly enriched in γ-tubulin reminiscent of the pericentriolar material of higher eukaryotic centrosomes. Formation of the rMTOC depends on Hrs1/Mcp6, a meiosis-specific SPB component that is located at the rMTOC. At the onset of meiosis I, Hrs1/Mcp6 is subject to strict downregulation by both proteasome-dependent degradation and phosphorylation leading to complete inactivation of the rMTOC. This ensures rMT dissolution and bipolar spindle formation. Conclusions Our study reveals the molecular basis for the transient generation of a novel MTOC, which triggers a program of MT rearrangement that is required for meiotic differentiation.
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Affiliation(s)
- Charlotta Funaya
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
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Complex formation, phosphorylation, and localization of protein kinase A of Schizosaccharomyces pombe upon glucose starvation. Biosci Biotechnol Biochem 2012; 75:1456-65. [PMID: 21869531 DOI: 10.1271/bbb.110125] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Nine sam mutants that undergo sexual differentiation without requiring starvation in Schizosaccharomyces pombe were previously isolated. In this study, we identified a nonsense mutation on the pka1 locus in the sam6 mutant. pka1 encodes a catalytic subunit of protein kinase A (PKA). Replacement and overexpression of pka1 suppressed the KCl sensitivity and hyper-mating phenotype of sam6, confirming that sam6 is an allele of pka1. To characterize further the regulation of Pka1, we tested the physical interaction between Pka1 and Cgs1 (a regulatory subunit of PKA). Pka1 and Cgs1 physically interacted under glucose-limited conditions but not under glucose-rich conditions. In addition, the formation of a Pka1-Cgs1 complex was detected under glucose-limited conditions by Blue Native PAGE. Furthermore, the Pka1 protein was found to be phosphorylated under glucose-starved conditions, and at the same time its localization shifted from the nucleus towards the cytoplasm (mainly the vacuoles), suggesting a strong relationship among phosphorylation, complex formation, and the cytoplasmic distribution of Pka1.
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Oowatari Y, Jeong H, Tanae K, Nakagawa T, Kawamukai M. Regulation and role of an RNA-binding protein Msa2 in controlling the sexual differentiation of fission yeast. Curr Genet 2011; 57:191-200. [DOI: 10.1007/s00294-011-0335-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 03/02/2011] [Accepted: 03/02/2011] [Indexed: 11/25/2022]
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Paul SK, Oowatari Y, Kawamukai M. A large complex mediated by Moc1, Moc2 and Cpc2 regulates sexual differentiation in fission yeast. FEBS J 2009; 276:5076-93. [PMID: 19682301 DOI: 10.1111/j.1742-4658.2009.07204.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sexual differentiation in Schizosaccharomyces pombe is triggered by nutrient starvation and is downregulated by cAMP. Screening programs have identified the moc1/sds23, moc2/ded1, moc3 and moc4/zfs1 genes as inducers of sexual differentiation, even in the presence of elevated levels of cAMP. To investigate possible interactions among Moc1, Moc2, Moc3 and Moc4 proteins, we first screened for individual Moc-interacting proteins using the yeast two-hybrid system and verified the interactions with other Moc proteins. Using this screening process, Cpc2 and Rpl32-2 were highlighted as factors involved in interactions with multiple Moc proteins. Cpc2 interacted with Moc1, Moc2 and Moc3, whereas the ribosomal protein Rpl32-2 interacted with all Moc proteins in the two-hybrid system. Physical interactions of Cpc2 with Moc1, Moc2 and Rpl32-2, and of Rpl32-2 with Moc2 were confirmed by coimmunoprecipitation. In addition, using Blue Native/PAGE, we revealed that each Moc protein exists as a large complex. Overexpression of Moc1, Moc2, Moc3, Moc4 and Rpl32-2 resulted in the efficient induction of a key transcription factor Ste11, suggesting that all proteins tested are positive regulators of Ste11. Considering that Moc2/Ded1 is a general translation factor and that Cpc2 associates with many ribosomal proteins, including Rpl32-2, it is possible that a large Moc-mediated complex, detected in this study, may act as a translational regulator involved in the control of sexual differentiation in S. pombe through the induction of Ste11.
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Affiliation(s)
- Swapan Kumar Paul
- Department of Applied Bioscience and Biotechnology, Shimane University, Matsue, Japan
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Wang X, Kam Z, Carlton PM, Xu L, Sedat JW, Blackburn EH. Rapid telomere motions in live human cells analyzed by highly time-resolved microscopy. Epigenetics Chromatin 2008; 1:4. [PMID: 19014413 PMCID: PMC2585561 DOI: 10.1186/1756-8935-1-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Accepted: 10/27/2008] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Telomeres cap chromosome ends and protect the genome. We studied individual telomeres in live human cancer cells. In capturing telomere motions using quantitative imaging to acquire complete high-resolution three-dimensional datasets every second for 200 seconds, telomere dynamics were systematically analyzed. RESULTS The motility of individual telomeres within the same cancer cell nucleus was widely heterogeneous. One class of internal heterochromatic regions of chromosomes analyzed moved more uniformly and showed less motion and heterogeneity than telomeres. The single telomere analyses in cancer cells revealed that shorter telomeres showed more motion, and the more rapid telomere motions were energy dependent. Experimentally increasing bulk telomere length dampened telomere motion. In contrast, telomere uncapping, but not a DNA damaging agent, methyl methanesulfonate, significantly increased telomere motion. CONCLUSION New methods for seconds-scale, four-dimensional, live cell microscopic imaging and data analysis, allowing systematic tracking of individual telomeres in live cells, have defined a previously undescribed form of telomere behavior in human cells, in which the degree of telomere motion was dependent upon telomere length and functionality.
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Affiliation(s)
- Xueying Wang
- Department of Biochemistry and Biophysics, University of California at San Francisco, California, USA.
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Chikashige Y, Haraguchi T, Hiraoka Y. Another way to move chromosomes. Chromosoma 2007; 116:497-505. [PMID: 17639451 DOI: 10.1007/s00412-007-0114-8] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Revised: 05/20/2007] [Accepted: 05/22/2007] [Indexed: 01/11/2023]
Abstract
A typical way of moving chromosomes is exemplified by mitotic segregation, in which the centromere is directly captured by spindle microtubules. In this study, we highlight another way of moving chromosomes remotely from outside the nucleus, which involves SUN and KASH domain nuclear envelope proteins. SUN and KASH domain protein families are known to connect the nucleus to cytoskeletal networks and play a role in migration and positioning of the nucleus. Recent studies in the fission yeast Schizossacharomyces pombe demonstrated an additional role for the SUN-KASH protein complex in chromosome movements. During meiotic prophase, telomeres are moved to rearrange chromosomes within the nucleus. The SUN-KASH protein complex located in the nuclear envelope is involved in this process. Telomeres are connected to the SUN protein on the nucleoplasmic side, and the dynein motor complex binds to the KASH protein on the cytoplasmic side. Telomeres are then moved along the nuclear envelope using cytoplasmic microtubules. These findings illustrate a general mechanism for transmitting a cytoskeletal driving force to chromosomes across the nuclear envelope.
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Affiliation(s)
- Yuji Chikashige
- Kobe Advanced ICT Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan
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Asakawa H, Haraguchi T, Hiraoka Y. Reconstruction of the kinetochore: a prelude to meiosis. Cell Div 2007; 2:17. [PMID: 17550626 PMCID: PMC1899494 DOI: 10.1186/1747-1028-2-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Accepted: 06/06/2007] [Indexed: 11/10/2022] Open
Abstract
In eukaryotic organisms, chromosomes are spatially organized within the nucleus. Such nuclear architecture provides a physical framework for the genetic activities of chromosomes, and changes its functional organization as the cell moves through the phases of the cell cycle. The fission yeast Schizosaccharomyces pombe provides a striking example of nuclear reorganization during the transition from mitosis to meiosis. In this organism, centromeres remain clustered at the spindle-pole body (SPB; a centrosome-equivalent structure in fungi) during mitotic interphase. In contrast, during meiotic prophase, centromeres dissociate from the SPB and telomeres cluster to the SPB. Recent studies revealed that this repositioning of chromosomes is regulated by mating pheromone signaling. Some centromere proteins disappear from the centromere in response to mating pheromone, leading to dissociation of centromeres from the SPB. Interestingly, mating pheromone signaling is also required for monopolar orientation of the kinetochore which is crucial for proper segregation of sister chromatids during meiosis. When meiosis is induced in the absence of mating pheromone signaling, aberrant chromosome behaviors are observed: the centromere proteins remain at the centromere; the centromere remains associated with the SPB; and sister chromatids segregate precociously in the first meiotic division. These aberrant chromosome behaviors are all normalized by activating the mating pheromone signaling pathway. Thus, action of mating pheromone on the centromere is important for coherent behavior of chromosomes in meiosis. Here we discuss repositioning and reconstruction of the centromere during the transition from mitosis to meiosis, and highlight its significance for proper progression of meiosis.
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Affiliation(s)
- Haruhiko Asakawa
- Kansai Advanced Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan
| | - Tokuko Haraguchi
- Kansai Advanced Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan
- Department of Biology, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043, Japan
| | - Yasushi Hiraoka
- Kansai Advanced Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan
- Department of Biology, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043, Japan
- Graduate School of Frontier Bioscience, Osaka University, 1-3 Yamadaoka, Suita 565-0871, Japan
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Chikashige Y, Tsutsumi C, Yamane M, Okamasa K, Haraguchi T, Hiraoka Y. Meiotic proteins bqt1 and bqt2 tether telomeres to form the bouquet arrangement of chromosomes. Cell 2006; 125:59-69. [PMID: 16615890 DOI: 10.1016/j.cell.2006.01.048] [Citation(s) in RCA: 275] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2005] [Revised: 12/14/2005] [Accepted: 01/09/2006] [Indexed: 11/25/2022]
Abstract
In many organisms, meiotic chromosomes are bundled at their telomeres to form a "bouquet" arrangement. The bouquet formation plays an important role in homologous chromosome pairing and therefore progression of meiosis. As meiotic telomere clustering occurs in response to mating pheromone signaling in fission yeast, we looked for factors essential for bouquet formation among genes induced under mating pheromone signaling. This genome-wide search identified two proteins, Bqt1 and Bqt2, that connect telomeres to the spindle-pole body (SPB; the centrosome equivalent in fungi). Neither Bqt1 nor Bqt2 alone functions as a connector, but together the two proteins form a bridge between Rap1 (a telomere protein) and Sad1 (an SPB protein). Significantly, when both Bqt1 and Bqt2 are ectopically expressed in mitotic cells, they also form a bridge between Rap1 and Sad1. Thus, a complex including Bqt1 and Bqt2 is essential for connecting telomeres to the SPB.
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Affiliation(s)
- Yuji Chikashige
- Cell Biology Group and CREST Research Project, Kansai Advanced Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan
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Yakura M, Ozoe F, Ishida H, Nakagawa T, Tanaka K, Matsuda H, Kawamukai M. zds1, a novel gene encoding an ortholog of Zds1 and Zds2, controls sexual differentiation, cell wall integrity and cell morphology in fission yeast. Genetics 2005; 172:811-25. [PMID: 16322512 PMCID: PMC1456246 DOI: 10.1534/genetics.105.050906] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
While screening for genes that reverse the sporulation-deficient phenotype of the ras1delta diploid Schizosaccharomyces pombe strain, we identified zds1. This gene shares sequence homology with the ZDS1 and ZDS2 genes from Saccharomyces cerevisiae, which appear to be involved in multiple cellular events. Expression of Zds1 in ras1delta diploid cells elevated their sporulation rate from 0.3 to 11.2%. Expression of the Zds1 C-terminal region increased the sporulation rate further (to 21.9%) while introduction of the Zds1 N-terminal region had no effect. zds1 expression did not induce sporulation in strains with mutations in genes participating in the downstream MAP kinase cascade. The zds1-disrupted strain is sensitive to CaCl2, and this effect is suppressed by the C-terminal region of Zds1. The growth of the zds1delta strain is markedly inhibited by cold temperatures, while its viability decreased in the stationary phase. Moreover, the zds1delta strain is round in shape and very sensitive to zymolyase, and its cell wall becomes thicker than that of wild type. Thus, zds1 must be required to maintain cell wall integrity. The Zds1-GFP fusion protein localized to the cytosol, the septum, and the cell cortex. Its localization in the septum was dependent on its C-terminal region. Overexpression of the C-terminal region of Zds1 induced multi-septa and abnormal zygotes. We propose that the C-terminal region is the functional domain of Zds1 while the N-terminal region is a negative regulatory region. Thus, Zds1 is involved in multiple cellular events in fission yeast, including sexual differentiation, Ca2+ tolerance, cell wall integrity, viability in the stationary phase, and cell morphology.
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Affiliation(s)
- Miyo Yakura
- Department of Life Science and Biotechnology, Shimane University, Matsue 690-8504, Japan
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Trelles-Sticken E, Adelfalk C, Loidl J, Scherthan H. Meiotic telomere clustering requires actin for its formation and cohesin for its resolution. J Cell Biol 2005; 170:213-23. [PMID: 16027219 PMCID: PMC2171397 DOI: 10.1083/jcb.200501042] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2005] [Accepted: 06/15/2005] [Indexed: 11/25/2022] Open
Abstract
In diploid organisms, meiosis reduces the chromosome number by half during the formation of haploid gametes. During meiotic prophase, telomeres transiently cluster at a limited sector of the nuclear envelope (bouquet stage) near the spindle pole body (SPB). Cohesin is a multisubunit complex that contributes to chromosome segregation in meiosis I and II divisions. In yeast meiosis, deficiency for Rec8 cohesin subunit induces telomere clustering to persist, whereas telomere cluster-SPB colocalization is defective. These defects are rescued by expressing the mitotic cohesin Scc1 in rec8delta meiosis, whereas bouquet-stage exit is independent of Cdc5 pololike kinase. An analysis of living Saccharomyces cerevisiae meiocytes revealed highly mobile telomeres from leptotene up to pachytene, with telomeres experiencing an actin- but not microtubule-dependent constraint of mobility during the bouquet stage. Our results suggest that cohesin is required for exit from actin polymerization-dependent telomere clustering and for linking the SPB to the telomere cluster in synaptic meiosis.
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Kjaerulff S, Lautrup-Larsen I, Truelsen S, Pedersen M, Nielsen O. Constitutive activation of the fission yeast pheromone-responsive pathway induces ectopic meiosis and reveals ste11 as a mitogen-activated protein kinase target. Mol Cell Biol 2005; 25:2045-59. [PMID: 15713656 PMCID: PMC549357 DOI: 10.1128/mcb.25.5.2045-2059.2005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the fission yeast Schizosaccharomyces pombe, meiosis normally takes place in diploid zygotes resulting from conjugation of haploid cells. In the present study, we report that the expression of a constitutively activated version of the pheromone-responsive mitogen-activated protein kinase kinase kinase (MAP3K) Byr2 can induce ectopic meiosis directly in haploid cells. We find that the Ste11 transcription factor becomes constitutively expressed in these cells and that the expression of pheromone-responsive genes no longer depends on nitrogen starvation. Epistasis analysis revealed that these conditions bypassed the requirement for the meiotic activator Mei3. Since Mei3 is normally needed for inactivation of the meiosis-repressing protein kinase Pat1, this finding suggests that the strong Byr2 signal causes inactivation of Pat1 by an alternative mechanism. Consistent with this possibility, we found that haploid meiosis was dramatically reduced when Ste11 was mutated to mimic phosphorylation by Pat1. The mutation of two putative MAPK sites in Ste11 also dramatically reduced the level of haploid meiosis, suggesting that Ste11 is a direct target of Spk1. Supporting this, we show that Spk1 can interact physically with Ste11 and also phosphorylate the transcription factor in vitro. Finally, we demonstrate that ste11 is required for pheromone-induced G1 arrest. Interestingly, when we mutated Ste11 in the sites for Pat1 and Spk1 phosphorylation simultaneously, the cells could still arrest in G1 in response to pheromone, suggesting the existence of yet a third bifurcation of the signaling pathway.
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Affiliation(s)
- Søren Kjaerulff
- Institute of Molecular Biology, University of Copenhagen, Øster Farimagsgade 2A, DK-1353 Copenhagen K, Denmark
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Asakawa H, Hayashi A, Haraguchi T, Hiraoka Y. Dissociation of the Nuf2-Ndc80 complex releases centromeres from the spindle-pole body during meiotic prophase in fission yeast. Mol Biol Cell 2005; 16:2325-38. [PMID: 15728720 PMCID: PMC1087238 DOI: 10.1091/mbc.e04-11-0996] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In the fission yeast Schizosaccharomyces pombe, centromeres remain clustered at the spindle-pole body (SPB) during mitotic interphase. In contrast, during meiotic prophase centromeres dissociate from the SPB. Here we examined the behavior of centromere proteins in living meiotic cells of S. pombe. We show that the Nuf2-Ndc80 complex proteins (Nuf2, Ndc80, Spc24, and Spc25) disappear from the centromere in meiotic prophase when the centromeres are separated from the SPB. The centromere protein Mis12 also dissociates during meiotic prophase; however, Mis6 remains throughout meiosis. When cells are induced to meiosis by inactivation of Pat1 kinase (a key negative regulator of meiosis), centromeres remain associated with the SPB during meiotic prophase. However, inactivation of Nuf2 by a mutation causes the release of centromeres from the SPB in pat1 mutant cells, suggesting that the Nuf2-Ndc80 complex connects centromeres to the SPB. We further found that removal of the Nuf2-Ndc80 complex from the centromere and centromere-SPB dissociation are caused by mating pheromone signaling. Because pat1 mutant cells also show aberrant chromosome segregation in the first meiotic division and this aberration is compensated by mating pheromone signaling, dissociation of the Nuf2-Ndc80 complex may be associated with remodeling of the kinetochore for meiotic chromosome segregation.
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Affiliation(s)
- Haruhiko Asakawa
- Cell Biology Group and CREST Research Project, Kansai Advanced Research Center, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
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Current awareness on yeast. Yeast 2005; 22:241-8. [PMID: 15762016 DOI: 10.1002/yea.1159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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