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Komoto T, Ikeo K, Yaguchi S, Yamamoto T, Sakamoto N, Awazu A. Assembly of continuous high-resolution draft genome sequence of Hemicentrotus pulcherrimus using long-read sequencing. Dev Growth Differ 2024. [PMID: 38634255 DOI: 10.1111/dgd.12924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 03/13/2024] [Accepted: 04/02/2024] [Indexed: 04/19/2024]
Abstract
The update of the draft genome assembly of sea urchin, Hemicentrotus pulcherrimus, which is widely studied in East Asia as a model organism of early development, was performed using Oxford nanopore long-read sequencing. The updated assembly provided ~600-Mb genome sequences divided into 2,163 contigs with N50 = 516 kb. BUSCO completeness score and transcriptome model mapping ratio (TMMR) of the present assembly were obtained as 96.5% and 77.8%, respectively. These results were more continuous with higher resolution than those by the previous version of H. pulcherrimus draft genome, HpulGenome_v1, where the number of scaffolds = 16,251 with a total of ~100 Mb, N50 = 143 kb, BUSCO completeness score = 86.1%, and TMMR = 55.4%. The obtained genome contained 36,055 gene models that were consistent with those in other echinoderms. Additionally, two tandem repeat sequences of early histone gene locus containing 47 copies and 34 copies of all histone genes, and 185 of the homologous sequences of the interspecifically conserved region of the Ars insulator, ArsInsC, were obtained. These results provide further advance for genome-wide research of development, gene regulation, and intranuclear structural dynamics of multicellular organisms using H. pulcherrimus.
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Affiliation(s)
- Tetsushi Komoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Kazuho Ikeo
- Department of Genomics and Evolutionary Biology, National Institute of Genetics, Shizuoka, Japan
| | - Shunsuke Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Japan
| | - Takashi Yamamoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima, Japan
| | - Naoaki Sakamoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima, Japan
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima, Japan
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2
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Sakamoto N, Watanabe K, Awazu A, Yamamoto T. CRISPR-Cas9-Mediated Gene Knockout in a Non-Model Sea Urchin, Heliocidaris crassispina. Zoolog Sci 2024; 41:159-166. [PMID: 38587910 DOI: 10.2108/zs230052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 10/25/2023] [Indexed: 04/10/2024]
Abstract
Sea urchins have been used as model organisms in developmental biology research and the genomes of several sea urchin species have been sequenced. Recently, genome editing technologies have become available for sea urchins, and methods for gene knockout using the CRISPRCas9 system have been established. Heliocidaris crassispina is an important marine fishery resource with edible gonads. Although H. crassispina has been used as a biological research material, its genome has not yet been published, and it is a non-model sea urchin for molecular biology research. However, as recent advances in genome editing technology have facilitated genome modification in non-model organisms, we applied genome editing using the CRISPR-Cas9 system to H. crassispina. In this study, we targeted genes encoding ETS transcription factor (HcEts) and pigmentation-related polyketide synthase (HcPks1). Gene fragments were isolated using primers designed by inter-specific sequence comparisons within Echinoidea. When Ets gene was targeted using two sgRNAs, one successfully introduced mutations and impaired skeletogenesis. In the Pks1 gene knockout, when two sgRNAs targeting the close vicinity of the site corresponding to the target site that showed 100% mutagenesis efficiency of the Pks1 gene in Hemicentrotus pulcherrimus, mutagenesis was not observed. However, two other sgRNAs targeting distant sites efficiently introduced mutations. In addition, Pks1 knockout H. crassispina exhibited an albino phenotype in the pluteus larvae and adult sea urchins after metamorphosis. This indicates that the CRISPRCas9 system can be used to modify the genome of the non-model sea urchin H. crassispina.
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Affiliation(s)
- Naoaki Sakamoto
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima 739-8526, Japan,
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Kaichi Watanabe
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Akinori Awazu
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Takashi Yamamoto
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
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Awazu A, Takemoto D, Watanabe K, Sakamoto N. Possibilities of skin coat color-dependent risks and risk factors of squamous cell carcinoma and deafness of domestic cats inferred via RNA-seq data. Genes Cells 2023; 28:893-905. [PMID: 37864512 DOI: 10.1111/gtc.13076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 10/02/2023] [Accepted: 10/06/2023] [Indexed: 10/23/2023]
Abstract
The transcriptome data of skin cells from domestic cats with brown, orange, and white coats were analyzed using a public database to investigate the possible relationship between coat color-related gene expression and squamous cell carcinoma risk, as well as the mechanism of deafness in white cats. We found that the ratio of the expression level of genes suppressing squamous cell carcinoma to that of genes promoting squamous cell carcinoma might be considerably lower than the theoretical estimation in skin cells with orange and white coats in white-spotted cat. We also found the possibility of the frequent production of KIT lacking the first exon (d1KIT) in skin cells with white coats, and d1KIT production exhibited a substantial negative correlation with the expression of SOX10, which is essential for melanocyte formation and adjustment of hearing function. Additionally, the production of d1KIT was expected to be due to the insulating activity of the feline endogenous retrovirus 1 (FERV1) LTR in the first intron of KIT by its CTCF binding sequence repeat. These results contribute to basic veterinary research to understand the relationship between cat skin coat and disease risk, as well as the underlying mechanism.
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Affiliation(s)
- Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Hiroshima, Japan
| | - Daigo Takemoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Kaichi Watanabe
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Naoaki Sakamoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Hiroshima, Japan
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Watanabe K, Fujita M, Okamoto K, Yoshioka H, Moriwaki M, Tagashira H, Awazu A, Yamamoto T, Sakamoto N. The crucial role of CTCF in mitotic progression during early development of sea urchin. Dev Growth Differ 2023; 65:395-407. [PMID: 37421304 DOI: 10.1111/dgd.12875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 07/10/2023]
Abstract
CCCTC-binding factor (CTCF), an insulator protein with 11 zinc fingers, is enriched at the boundaries of topologically associated domains (TADs) in eukaryotic genomes. In this study, we isolated and analyzed the cDNAs encoding HpCTCF, the CTCF homolog in the sea urchin Hemicentrotus pulcherrimus, to investigate its expression patterns and functions during the early development of sea urchin. HpCTCF contains nine zinc fingers corresponding to fingers 2-10 of the vertebrate CTCF. Expression pattern analysis revealed that HpCTCF mRNA was detected at all developmental stages and in the entire embryo. Upon expressing the HpCTCF-GFP fusion protein in early embryos, we observed its uniform distribution within interphase nuclei. However, during mitosis, it disappeared from the chromosomes and subsequently reassembled on the chromosome during telophase. Moreover, the morpholino-mediated knockdown of HpCTCF resulted in mitotic arrest during the morula to blastula stage. Most of the arrested chromosomes were not phospholylated at serine 10 of histone H3, indicating that mitosis was arrested at the telophase by HpCTCF depletion. Furthermore, impaired sister chromatid segregation was observed using time-lapse imaging of HpCTCF-knockdown embryos. Thus, HpCTCF is essential for mitotic progression during the early development of sea urchins, especially during the telophase-to-interphase transition. However, the normal development of pluteus larvae in CRISPR-mediated HpCTCF-knockout embryos suggests that disruption of zygotic HpCTCF expression has little effect on embryonic and larval development.
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Affiliation(s)
- Kaichi Watanabe
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Megumi Fujita
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Kazuko Okamoto
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Japan
- Amphibian Research Center, Hiroshima University, Higashi-Hiroshima, Japan
| | - Hajime Yoshioka
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Miki Moriwaki
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Hideki Tagashira
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Akinori Awazu
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima, Japan
| | - Takashi Yamamoto
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima, Japan
| | - Naoaki Sakamoto
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima, Japan
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Wakao S, Saitoh N, Awazu A. Mathematical model of structural changes in nuclear speckle. Biophys Physicobiol 2023; 20:e200020. [PMID: 38496241 PMCID: PMC10941963 DOI: 10.2142/biophysico.bppb-v20.0020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 04/26/2023] [Indexed: 03/19/2024] Open
Abstract
Nuclear speckles are nuclear bodies consisting of populations of small and irregularly shaped droplet-like molecular condensates that contain various splicing factors. Recent experiments have revealed the following structural features of nuclear speckles: (I) Each molecular condensate contains SON and SRRM2 proteins, and MALAT1 non-coding RNA surrounds these condensates; (II) During normal interphase of the cell cycle in multicellular organisms, these condensates are broadly distributed throughout the nucleus. In contrast, when cell transcription is suppressed, the condensates fuse and form strongly condensed spherical droplets; (III) SON is dispersed spatially in MALAT1 knocked-down cells and MALAT1 is dispersed in SON knocked-down cells because of the collapse of the nuclear speckles. However, the detailed interactions among the molecules that are mechanistically responsible for the structural variation remain unknown. In this study, a coarse-grained molecular dynamics model of the nuclear speckle was developed by considering the dynamics of SON, SRRM2, MALAT1, and pre-mRNA as representative components of the condensates. The simulations reproduced the structural changes, which were used to predict the interaction network among the representative components of the condensates.
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Affiliation(s)
- Shingo Wakao
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Hiroshima 739-8526, Japan
| | - Noriko Saitoh
- Division of Cancer Biology, The Cancer Institute of Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Hiroshima 739-8526, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashihiroshima, Hiroshima 739-8526, Japan
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6
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Shirai M, Takayama K, Takahashi H, Hirose Y, Fujii M, Awazu A, Shimoda N, Kikuchi Y. Methylome data derived from maternal-zygotic DNA methyltransferase 3aa zebrafish. Data Brief 2022; 44:108514. [PMID: 36034642 PMCID: PMC9399957 DOI: 10.1016/j.dib.2022.108514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/21/2022] [Accepted: 07/29/2022] [Indexed: 11/30/2022] Open
Abstract
Genomic DNA methylation is an epigenetic marker mediated by DNA methyltransferases (Dnmts); in vertebrates, it comprises of a maintenance DNA methyltransferase, Dnmt1, and two de novo DNA methyltransferases (Dnmt3a and Dnmt3b). In zebrafish, there are two homologs of the mammalian Dnmt3a: Dnmt3aa and Dnmt3ab. A knockout (KO) mutant of zebrafish dnmt3aa was generated using the CRISPR/Cas9 genome-editing system as a new model for DNA methylation research. Since zebrafish dnmt3aa KO mutants were viable and fertile, a maternal-zygotic dnmt3aa deficient mutant (MZdnmt3aa) was generated. We performed whole-genome bisulfite sequencing (WGBS) to reveal the DNA methylation profile using this mutant and identified genomic regions with altered CpG methylation as differentially methylated regions (DMRs) in this mutant compared to those in the wild-type fish. We provided novel raw and processed datasets using the MZdnmt3aa KO mutant, and the raw data of WGBS are available through the Gene Expression Omnibus (GEO), accession number GSE178690.
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Affiliation(s)
- Masaki Shirai
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526 Japan
| | - Kazuya Takayama
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526 Japan
| | - Haruko Takahashi
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526 Japan
- Graduate School of Integrated Sciences for Life, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Yudai Hirose
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526 Japan
| | - Masashi Fujii
- Graduate School of Integrated Sciences for Life, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Nobuyoshi Shimoda
- Laboratory of Molecular Analysis, Research and Development Management Center, National Center for Geriatrics and Gerontology, 7-430, Morioka, Obu, Aichi 474-8522, Japan
| | - Yutaka Kikuchi
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526 Japan
- Graduate School of Integrated Sciences for Life, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Corresponding author.
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Shirai M, Nara T, Takahashi H, Takayama K, Chen Y, Hirose Y, Fujii M, Awazu A, Shimoda N, Kikuchi Y. Identification of aberrant transcription termination at specific gene loci with DNA hypomethylated transcription termination sites caused by DNA methyltransferase deficiency. Gene 2022; 97:139-152. [PMID: 35718462 DOI: 10.1266/ggs.21-00092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
CpG methylation of genomic DNA is a well-known repressive epigenetic marker in eukaryotic transcription, and DNA methylation of promoter regions is correlated with gene silencing. In contrast to the promoter regions, the function of DNA methylation during transcription termination remains to be elucidated. A recent study revealed that mouse DNA methyltransferase 3a (Dnmt3a) mainly functions in de novo methylation in the promoter and gene body regions, including transcription termination sites (TTSs), during development. To investigate the relationship between DNA methylation overlapping the TTSs and transcription termination, we performed bioinformatics analysis using six pre-existing Dnmt-/- mouse cell datasets: four types of neurons (three Dnmt3a-/- and one Dnmt1-/- mutants) and two types of embryonic fibroblasts (MEFs) (Dnmt3a-/- and Dnmt3b-/- mutants). Combined analyses using methylome and transcriptome data revealed that read counts downstream of hypomethylated TTSs were increased in three types of neurons (two Dnmt3a-/- and one Dnmt1-/- mutants). Among these, an increase in chimeric transcripts downstream of the TTSs was observed in Dnmt3a-/- mature olfactory sensory neurons and Dnmt3a-/- agouti-related peptide (protein)-producing neurons, thereby indicating that read-through occurs in hypomethylated TTSs at specific gene loci in these two mutants. Conversely, in Dnmt3a-/- MEFs, we detected reductions in read counts downstream of hypomethylated TTSs. These results indicate that the hypomethylation of TTSs can both positively and negatively regulate transcription termination, dependent on Dnmt and cell types. This study is the first to identify the aberrant termination of transcription at specific gene loci with DNA hypomethylated TTSs attributable to Dnmt deficiency.
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Affiliation(s)
- Masaki Shirai
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima
| | - Takuya Nara
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima
| | - Haruko Takahashi
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima.,Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima
| | - Kazuya Takayama
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima
| | - Yuan Chen
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima
| | - Yudai Hirose
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima
| | - Masashi Fujii
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima
| | - Nobuyoshi Shimoda
- Laboratory of Molecular Analysis, Core Facilities, National Center for Geriatrics and Gerontology
| | - Yutaka Kikuchi
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima.,Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima
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Komoto T, Fujii M, Awazu A. Epigenetic-structural changes in X chromosomes promote Xic pairing during early differentiation of mouse embryonic stem cells. Biophys Physicobiol 2022; 19:1-14. [PMID: 35797402 PMCID: PMC9174021 DOI: 10.2142/biophysico.bppb-v19.0018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 05/02/2022] [Indexed: 12/01/2022] Open
Abstract
X chromosome inactivation center (Xic) pairing occurs during the differentiation of embryonic stem (ES) cells from female mouse embryos, and is related to X chromosome inactivation, the circadian clock, intra-nucleus architecture, and metabolism. However, the mechanisms underlying the identification and approach of X chromosome pairs in the crowded nucleus are unclear. To elucidate the driving force of Xic pairing, we developed a coarse-grained molecular dynamics model of intranuclear chromosomes in ES cells and in cells 2 days after the onset of differentiation (2-day cells) by considering intrachromosomal epigenetic-structural feature-dependent mechanics. The analysis of the experimental data showed that X-chromosomes exhibit the rearrangement of their distributions of open/closed chromatin regions on their surfaces during cell differentiation. By simulating models where the excluded volume effects of closed chromatin regions are stronger than those of open chromatin regions, such rearrangement of open/closed chromatin regions on X-chromosome surfaces promoted the mutual approach of the Xic pair. These findings suggested that local intrachromosomal epigenetic features may contribute to the regulation of cell species-dependent differences in intranuclear architecture.
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Affiliation(s)
- Tetsushi Komoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Masashi Fujii
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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9
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Nakahata S, Komoto T, Fujii M, Awazu A. Mathematical model of chromosomal dynamics during DNA double strand break repair in budding yeast. Biophys Physicobiol 2022; 19:1-12. [PMID: 35749629 PMCID: PMC9160732 DOI: 10.2142/biophysico.bppb-v19.0012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 03/31/2022] [Indexed: 12/01/2022] Open
Abstract
During the repair of double-strand breaks (DSBs) in DNA, active mobilizations for conformational changes in chromosomes have been widely observed in eukaryotes, from yeast to animal and plant cells. DSB-damaged loci in the yeast genome showed increased mobility and relocation to the nuclear periphery. However, the driving forces behind DSB-induced chromatin dynamics remain unclear. In this study, mathematical models of normal and DSB-damaged yeast chromosomes were developed to simulate their structural dynamics. The effects of histone degradation in the whole nucleus and the change in the physical properties of damaged loci due to the binding of SUMOylated repair proteins were considered in the model of DSB-induced chromosomes based on recent experimental results. The simulation results reproduced DSB-induced changes to structural and dynamical features by which the combination of whole nuclear histone degradation and the rigid structure formation of repair protein accumulations on damaged loci were suggested to be primary contributors to the process by which damaged loci are relocated to the nuclear periphery.
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Affiliation(s)
- Shinjiro Nakahata
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Tetsushi Komoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Masashi Fujii
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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10
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Watanabe K, Yasui Y, Kurose Y, Fujii M, Yamamoto T, Sakamoto N, Awazu A. Partial exogastrulation due to apical‐basal polarity of F‐actin distribution disruption in sea urchin embryo by omeprazole. Genes Cells 2022; 27:392-408. [PMID: 35347809 PMCID: PMC9325501 DOI: 10.1111/gtc.12934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/25/2022] [Accepted: 03/25/2022] [Indexed: 11/29/2022]
Affiliation(s)
- Kaichi Watanabe
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi‐Hiroshima Japan
| | - Yuhei Yasui
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi‐Hiroshima Japan
| | - Yuta Kurose
- Department of Mathematical and Life Sciences Graduate School of Science, Hiroshima University, Higashi‐Hiroshima Japan
| | - Masashi Fujii
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi‐Hiroshima Japan
| | - Takashi Yamamoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi‐Hiroshima Japan
| | - Naoaki Sakamoto
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi‐Hiroshima Japan
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi‐Hiroshima Japan
- Research Center for the Mathematics on Chromatin Live Dynamics Hiroshima University, Higashi‐Hiroshima Hiroshima Japan
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11
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Matsumori H, Watanabe K, Tachiwana H, Fujita T, Ito Y, Tokunaga M, Sakata-Sogawa K, Osakada H, Haraguchi T, Awazu A, Ochiai H, Sakata Y, Ochiai K, Toki T, Ito E, Goldberg IG, Tokunaga K, Nakao M, Saitoh N. Ribosomal protein L5 facilitates rDNA-bundled condensate and nucleolar assembly. Life Sci Alliance 2022; 5:5/7/e202101045. [PMID: 35321919 PMCID: PMC8942980 DOI: 10.26508/lsa.202101045] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 11/24/2022] Open
Abstract
High content image analysis, single molecule tracking, modeling, and DBA patient analysis revealed that ribosomal protein L5 facilitates rDNA-bundled condensate and nucleolar assembly. The nucleolus is the site of ribosome assembly and formed through liquid–liquid phase separation. Multiple ribosomal DNA (rDNA) arrays are bundled in the nucleolus, but the underlying mechanism and significance are unknown. In the present study, we performed high-content screening followed by image profiling with the wndchrm machine learning algorithm. We revealed that cells lacking a specific 60S ribosomal protein set exhibited common nucleolar disintegration. The depletion of RPL5 (also known as uL18), the liquid–liquid phase separation facilitator, was most effective, and resulted in an enlarged and un-separated sub-nucleolar compartment. Single-molecule tracking analysis revealed less-constrained mobility of its components. rDNA arrays were also unbundled. These results were recapitulated by a coarse-grained molecular dynamics model. Transcription and processing of ribosomal RNA were repressed in these aberrant nucleoli. Consistently, the nucleoli were disordered in peripheral blood cells from a Diamond–Blackfan anemia patient harboring a heterozygous, large deletion in RPL5. Our combinatorial analyses newly define the role of RPL5 in rDNA array bundling and the biophysical properties of the nucleolus, which may contribute to the etiology of ribosomopathy.
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Affiliation(s)
- Haruka Matsumori
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan
| | - Kenji Watanabe
- Cancer Institute of Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Hiroaki Tachiwana
- Cancer Institute of Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Tomoko Fujita
- Cancer Institute of Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Yuma Ito
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Makio Tokunaga
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Kumiko Sakata-Sogawa
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Hiroko Osakada
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan.,Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan.,Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, Higashi-Hiroshima, Japan
| | - Hiroshi Ochiai
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Yuka Sakata
- Cancer Institute of Japanese Foundation for Cancer Research, Tokyo, Japan
| | | | - Tsutomu Toki
- Department of Pediatrics, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Etsuro Ito
- Department of Pediatrics, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Ilya G Goldberg
- Image Informatics and Computational Biology Unit, Laboratory of Genetics, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Kazuaki Tokunaga
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan
| | - Mitsuyoshi Nakao
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan
| | - Noriko Saitoh
- Cancer Institute of Japanese Foundation for Cancer Research, Tokyo, Japan
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12
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Kameda T, Awazu A, Togashi Y. Molecular dynamics analysis of biomolecular systems including nucleic acids. Biophys Physicobiol 2022; 19:e190027. [DOI: 10.2142/biophysico.bppb-v19.0027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 08/18/2022] [Indexed: 12/01/2022] Open
Affiliation(s)
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University
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13
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Abstract
DNA methylation is associated with a number of biological phenomena, and plays crucial roles in epigenetic regulation of eukaryotic gene expression. It is also suggested that DNA methylation alters the mechanical properties of DNA molecules, which is likely to affect epigenetic regulation. However, it has not been systematically investigated how methylation changes the structural and dynamic features of DNA. In this research, to elucidate the effects of methylation on DNA mechanics, a fully atomic molecular dynamics simulation of double-stranded DNA with several methylation patterns was performed. Through the analysis of the relative positioning of the nucleotides (base-step variables), characteristic changes in terms of local flexibility were observed, which further affected the overall DNA geometry and stiffness. These findings may serve as a basis for a discussion on methylation-dependent DNA dynamics in physiological conditions.
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Affiliation(s)
- Takeru Kameda
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
- RIKEN Center for Biosystems Dynamics Research (BDR), Wako, Saitama, Japan
| | - Miho M Suzuki
- Graduate School of Medicine, Nagoya University, Nagoya, Aichi, Japan
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Yuichi Togashi
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
- RIKEN Center for Biosystems Dynamics Research (BDR), Higashi-Hiroshima, Hiroshima, Japan
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14
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Aoki D, Awazu A, Fujii M, Uewaki JI, Hashimoto M, Tochio N, Umehara T, Tate SI. Ultrasensitive Change in Nucleosome Binding by Multiple Phosphorylations to the Intrinsically Disordered Region of the Histone Chaperone FACT. J Mol Biol 2020; 432:4637-4657. [PMID: 32553729 DOI: 10.1016/j.jmb.2020.06.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 06/08/2020] [Accepted: 06/10/2020] [Indexed: 10/24/2022]
Abstract
Facilitates chromatin transcription (FACT) is a histone chaperone that functions as a nucleosome remodeler and a chaperone. The two subunits of FACT, Spt16 and SSRP1, mediate multiple interactions between the subunits and components of the nucleosome. Among the interactions, the role of the DNA-binding domain in SSRP1 has not been characterized. We reported previously that the DNA-binding domain in Drosophila SSRP1 (dSSRP1) has multiple casein kinase II phosphorylation sites, and the DNA binding affinity of the domain changes sigmoidally in response to the degree of phosphorylation ("ultrasensitive response"). In this report, we explored the molecular mechanisms for the ultrasensitive response of the DNA-binding domain in dSSRP1 using the shortest fragment (AB-HMG, residues 434-624) responsible for nucleosome binding. AB-HMG contains two intrinsically disordered (ID) regions: the N-terminal part rich in acidic residues (AID) and the C-terminal part rich in basic residues (BID) followed by the HMG box. NMR and coarse-grained molecular dynamics simulations revealed a phosphorylation-dependent change in intramolecular contacts between the AID and BID-HMG, which is mediated by a hinge bending motion of AB-HMG to enable the ultrasensitive response. Ultrasensitivity generates two distinct forms of dSSRP1, which are high- and low-affinity nucleosome-binding forms. Drosophila FACT (dFACT) switches function according to the degree of phosphorylation of the AID in dSSRP1. We propose that dFACT in various phosphorylation states functions cooperatively to facilitate gene regulation in the context of the chromatin.
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Affiliation(s)
- Daisuke Aoki
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8567, Japan; Laboratory for Epigenetics Drug Discovery, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro, Tsurumi, Yokohama 230-0045, Japan
| | - Akinori Awazu
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8567, Japan; Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan; Department of Mathematical and Life Sciences, Graduate School of the Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Masashi Fujii
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8567, Japan
| | - Jun-Ichi Uewaki
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8567, Japan; Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Manami Hashimoto
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8567, Japan
| | - Naoya Tochio
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8567, Japan; Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Takashi Umehara
- Laboratory for Epigenetics Drug Discovery, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro, Tsurumi, Yokohama 230-0045, Japan
| | - Shin-Ichi Tate
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8567, Japan; Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan; Department of Mathematical and Life Sciences, Graduate School of the Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
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15
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Kaneshige Y, Hayashi F, Morigaki K, Tanimoto Y, Yamashita H, Fujii M, Awazu A. Affinity of rhodopsin to raft enables the aligned oligomer formation from dimers: Coarse-grained molecular dynamics simulation of disk membranes. PLoS One 2020; 15:e0226123. [PMID: 32032370 PMCID: PMC7006936 DOI: 10.1371/journal.pone.0226123] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 01/13/2020] [Indexed: 12/16/2022] Open
Abstract
The visual photopigment protein rhodopsin (Rh) is a typical G protein-coupled receptor (GPCR) that initiates the phototransduction cascade in retinal disk membrane of rod-photoreceptor cells. Rh molecule has a tendency to form dimer, and the dimer tends to form rows, which is suggested to heighten phototransduction efficiency in single-photon regime. In addition, the dimerization confers Rh an affinity for lipid raft, i.e. raftophilicity. However, the mechanism by which Rh-dimer raftophilicity contributes to the organization of the higher order structure remains unknown. In this study, we performed coarse-grained molecular dynamics simulations of a disk membrane model containing unsaturated lipids, saturated lipids with cholesterol, and Rh-dimers. We described the Rh-dimers by two-dimensional particle populations where the palmitoyl moieties of each Rh exhibits raftophilicity. We simulated the structuring of Rh in a disk for two types of Rh-dimer, i.e., the most and second most stable Rh dimers, which exposes the raftophilic regions at the dimerization-interface (H1/H8 dimer) and two edges away from the interface (H4/H5 dimer), respectively. Our simulations revealed that only the H1/H8 dimer could form a row structure. A small number of raftophilic lipids recruited to and intercalated in a narrow space between H1/H8 dimers stabilize the side-by-side interaction between dimers in a row. Our results implicate that the nano-sized lipid raft domains act as a “glue” to organize the long row structures of Rh-dimers.
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Affiliation(s)
- Yukito Kaneshige
- Department of Mathematical and Life Sciences, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Japan
| | - Fumio Hayashi
- Graduate School of Science, Kobe University, Rokkodaicho, Nada, Kobe, Japan
| | - Kenichi Morigaki
- Biosignal Research Center, Kobe University, Rokkodaicho, Nada, Kobe, Japan
| | - Yasushi Tanimoto
- Graduate School of Science, Kobe University, Rokkodaicho, Nada, Kobe, Japan
| | - Hayato Yamashita
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan
| | - Masashi Fujii
- Department of Mathematical and Life Sciences, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Japan
| | - Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Japan
- * E-mail:
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16
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Kameda T, Awazu A, Togashi Y. Histone Tail Dynamics in Partially Disassembled Nucleosomes During Chromatin Remodeling. Front Mol Biosci 2019; 6:133. [PMID: 31850366 PMCID: PMC6896900 DOI: 10.3389/fmolb.2019.00133] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 11/11/2019] [Indexed: 11/13/2022] Open
Abstract
Nucleosomes are structural units of the chromosome consisting of DNA wrapped around histone proteins, and play important roles in compaction and regulation of the chromatin structure. While the structure and dynamics of canonical nucleosomes have been studied extensively, those of nucleosomes in intermediate states, that occur when their structure or positioning is modulated, have been less understood. In particular, the dynamic features of partially disassembled nucleosomes have not been discussed in previous studies. Using all-atom molecular dynamics simulations, in this study, we investigated the dynamics and stability of nucleosome structures lacking a histone-dimer. DNA in nucleosomes lacking a histone H2A/H2B dimer was drastically deformed due to loss of local interactions between DNA and histones. In contrast, conformation of DNA in nucleosomes lacking H3/H4 was similar to the canonical nucleosome, as the H2A C-terminal domain infiltrated the space originally occupied by the dissociated H3/H4 histones and restricted DNA dynamics in close proximity. Our results suggest that, besides histone chaperones, the intrinsic dynamics of nucleosomes support the exchange of H2A/H2B, which is significantly more frequent than that of H3/H4.
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Affiliation(s)
- Takeru Kameda
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan.,Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, Higashi-Hiroshima, Japan
| | - Yuichi Togashi
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan.,Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, Higashi-Hiroshima, Japan.,RIKEN Center for Biosystems Dynamics Research (BDR), Higashi-Hiroshima, Japan
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17
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Liu D, Awazu A, Sakuma T, Yamamoto T, Sakamoto N. Establishment of knockout adult sea urchins by using a CRISPR‐Cas9 system. Dev Growth Differ 2019; 61:378-388. [DOI: 10.1111/dgd.12624] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 06/23/2019] [Accepted: 06/24/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Daming Liu
- Department of Mathematical and Life Sciences Graduate School of Science Hiroshima University Hiroshima Japan
| | - Akinori Awazu
- Department of Mathematical and Life Sciences Graduate School of Science Hiroshima University Hiroshima Japan
- Division of Integrated Sciences for Life Graduate School of Integrated Sciences for Life Hiroshima University Hiroshima Japan
| | - Tetsushi Sakuma
- Department of Mathematical and Life Sciences Graduate School of Science Hiroshima University Hiroshima Japan
- Division of Integrated Sciences for Life Graduate School of Integrated Sciences for Life Hiroshima University Hiroshima Japan
| | - Takashi Yamamoto
- Department of Mathematical and Life Sciences Graduate School of Science Hiroshima University Hiroshima Japan
- Division of Integrated Sciences for Life Graduate School of Integrated Sciences for Life Hiroshima University Hiroshima Japan
| | - Naoaki Sakamoto
- Department of Mathematical and Life Sciences Graduate School of Science Hiroshima University Hiroshima Japan
- Division of Integrated Sciences for Life Graduate School of Integrated Sciences for Life Hiroshima University Hiroshima Japan
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18
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Shiraishi M, Takeuchi R, Nakagawa H, Nishimura SI, Awazu A, Nishimori H. Diverse stochasticity leads a colony of ants to optimal foraging. J Theor Biol 2019; 465:7-16. [PMID: 30629963 DOI: 10.1016/j.jtbi.2019.01.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 12/27/2018] [Accepted: 01/03/2019] [Indexed: 10/27/2022]
Abstract
A mathematical model of garden ants (Lasius japonicus) is introduced herein to investigate the relationship between the distribution of the degree of stochasticity in following pheromone trails and the group foraging efficiency. Numerical simulations of the model indicate that depending on the systematic change of the feeding environment, the optimal distribution of stochasticity shifts from a mixture of almost deterministic and mildly stochastic ants to a contrasted mixture of almost deterministic ants and highly stochastic ants. In addition, the interaction between the stochasticity and the pheromone path regulates the dynamics of the foraging efficiency optimization. Stochasticity could strengthen the collective efficiency when the variance in the sensitivity to pheromone for ants is introduced in the model.
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Affiliation(s)
- Masashi Shiraishi
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Kagamiyama, Higashi-hiroshima 739-8526, Japan; CREST, JST, Tokyo, Japan.
| | | | - Hiroyuki Nakagawa
- Department of Mathematical Sciences, Graduate School of Engineering, Osaka Prefecture University, Sakai 599-8531, Japan
| | - Shin I Nishimura
- T & S Co. Ltd., MM Park Build., 3-6-3, Minatomirai, Nishi-ku, Yokohama, Kanagawa, Japan
| | - Akinori Awazu
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Kagamiyama, Higashi-hiroshima 739-8526, Japan
| | - Hiraku Nishimori
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Kagamiyama, Higashi-hiroshima 739-8526, Japan.
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19
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Matsushima Y, Sakamoto N, Awazu A. Insulator Activities of Nucleosome-Excluding DNA Sequences without Bound Chromatin Looping Proteins. J Phys Chem B 2019; 123:1035-1043. [DOI: 10.1021/acs.jpcb.8b10518] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Yuki Matsushima
- Department of Mathematical and Life Sciences, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
| | - Naoaki Sakamoto
- Department of Mathematical and Life Sciences, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
- Research Center for Mathematics on Chromatin Live Dynamics, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
| | - Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
- Research Center for Mathematics on Chromatin Live Dynamics, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
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20
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Shi L, Fujioka K, Sakurai-Ozato N, Fukumoto W, Satoh K, Sun J, Awazu A, Tanaka K, Ishida M, Ishida T, Nakano Y, Kihara Y, Hayes CN, Aikata H, Chayama K, Ito T, Awai K, Tashiro S. Chromosomal Abnormalities in Human Lymphocytes after Computed Tomography Scan Procedure. Radiat Res 2018; 190:424-432. [PMID: 30040044 DOI: 10.1667/rr14976.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The incidence of chromosomal abnormalities and cancer risk correlates well with the radiation dose after exposure to moderate- to high-dose ionizing radiation. However, the biological effects and health risks at less than 100 mGy, e.g., from computed tomography (CT) have not been ascertained. To investigate the biological effects of low-dose exposure from a CT procedure, we examined chromosomal aberrations, dicentric and ring chromosomes (dic+ring), in peripheral blood lymphocytes (PBLs), using FISH assays with telomere and centromere PNA probes. In 60 non-cancer patients exposed to CT scans, the numbers of dicentric and ring chromosomes were significantly increased with individual variation. The individual variations in the increment of dicentric and ring chromosomes after CT procedures were confirmed using PNA-FISH analysis of PBLs from 15 healthy volunteers after in vitro low-dose exposure using a 137Cs radiation device. These findings strongly suggest that appropriate medical use of low-dose radiation should consider individual differences in radiation sensitivity.
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Affiliation(s)
- Lin Shi
- Departments of a Cellular Biology
| | | | | | - Wataru Fukumoto
- g Department of Diagnostic Radiology, Hiroshima University, Hiroshima 734-8553, Japan
| | - Kenichi Satoh
- c Environmetrics and Biometrics, Research Institute for Radiation Biology Medicine
| | | | - Akinori Awazu
- h Department of Mathematics.,i Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi Hiroshima 739-8530, Japan
| | | | - Mari Ishida
- d Departments of Cardiovascular Physiology and Medicine
| | - Takafumi Ishida
- j Department of Cardiovascular Medicine, Fukushima Medical University, Fukushima 960-1295, Japan
| | | | | | - C Nelson Hayes
- f Gastroenterology and Metabolism, Biomedical Sciences, Graduate School of Biomedical and Health Sciences
| | - Hiroshi Aikata
- f Gastroenterology and Metabolism, Biomedical Sciences, Graduate School of Biomedical and Health Sciences
| | - Kazuaki Chayama
- f Gastroenterology and Metabolism, Biomedical Sciences, Graduate School of Biomedical and Health Sciences
| | - Takashi Ito
- k Department of Biochemistry, Nagasaki University School of Medicine, Nagasaki 852-8523, Japan
| | - Kazuo Awai
- g Department of Diagnostic Radiology, Hiroshima University, Hiroshima 734-8553, Japan
| | - Satoshi Tashiro
- Departments of a Cellular Biology.,i Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi Hiroshima 739-8530, Japan
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21
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Awazu A, Tanabe T, Kamitani M, Tezuka A, Nagano AJ. Broad distribution spectrum from Gaussian to power law appears in stochastic variations in RNA-seq data. Sci Rep 2018; 8:8339. [PMID: 29844539 PMCID: PMC5974282 DOI: 10.1038/s41598-018-26735-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 05/09/2018] [Indexed: 11/21/2022] Open
Abstract
Gene expression levels exhibit stochastic variations among genetically identical organisms under the same environmental conditions. In many recent transcriptome analyses based on RNA sequencing (RNA-seq), variations in gene expression levels among replicates were assumed to follow a negative binomial distribution, although the physiological basis of this assumption remains unclear. In this study, RNA-seq data were obtained from Arabidopsis thaliana under eight conditions (21-27 replicates), and the characteristics of gene-dependent empirical probability density function (ePDF) profiles of gene expression levels were analyzed. For A. thaliana and Saccharomyces cerevisiae, various types of ePDF of gene expression levels were obtained that were classified as Gaussian, power law-like containing a long tail, or intermediate. These ePDF profiles were well fitted with a Gauss-power mixing distribution function derived from a simple model of a stochastic transcriptional network containing a feedback loop. The fitting function suggested that gene expression levels with long-tailed ePDFs would be strongly influenced by feedback regulation. Furthermore, the features of gene expression levels are correlated with their functions, with the levels of essential genes tending to follow a Gaussian-like ePDF while those of genes encoding nucleic acid-binding proteins and transcription factors exhibit long-tailed ePDF.
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Affiliation(s)
- Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan.
- Research Center for Mathematics on Chromatin Live Dynamics, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan.
| | - Takahiro Tanabe
- Department of Mathematical and Life Sciences, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Mari Kamitani
- Research Institute for Food and Agriculture, Ryukoku University, Yokotani 1-5, Seta Ohe-cho, Otsu, Shiga, 520-2194, Japan
| | - Ayumi Tezuka
- Research Institute for Food and Agriculture, Ryukoku University, Yokotani 1-5, Seta Ohe-cho, Otsu, Shiga, 520-2194, Japan
| | - Atsushi J Nagano
- Research Institute for Food and Agriculture, Ryukoku University, Yokotani 1-5, Seta Ohe-cho, Otsu, Shiga, 520-2194, Japan
- Faculty of Agriculture, Ryukoku University, Yokatani 1-5, Seta, Ohe-cho, Otsu-shi, Shiga, 520-2194, Japan
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22
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Matsushita M, Ochiai H, Suzuki KIT, Hayashi S, Yamamoto T, Awazu A, Sakamoto N. Dynamic changes in the interchromosomal interaction of early histone gene loci during development of sea urchin. J Cell Sci 2017; 130:4097-4107. [PMID: 29084822 DOI: 10.1242/jcs.206862] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 10/22/2017] [Indexed: 12/21/2022] Open
Abstract
The nuclear positioning and chromatin dynamics of eukaryotic genes are closely related to the regulation of gene expression, but they have not been well examined during early development, which is accompanied by rapid cell cycle progression and dynamic changes in nuclear organization, such as nuclear size and chromatin constitution. In this study, we focused on the early development of the sea urchin Hemicentrotus pulcherrimus and performed three-dimensional fluorescence in situ hybridization of gene loci encoding early histones (one of the types of histone in sea urchin). There are two non-allelic early histone gene loci per sea urchin genome. We found that during the morula stage, when the early histone gene expression levels are at their maximum, interchromosomal interactions were often formed between the early histone gene loci on separate chromosomes and that the gene loci were directed to locate to more interior positions. Furthermore, these interactions were associated with the active transcription of the early histone genes. Thus, such dynamic interchromosomal interactions may contribute to the efficient synthesis of early histone mRNA during the morula stage of sea urchin development.
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Affiliation(s)
- Masaya Matsushita
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Hiroshi Ochiai
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.,JST, PRESTO, Higashi-Hiroshima 739-8530, Japan
| | - Ken-Ichi T Suzuki
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Sayaka Hayashi
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Takashi Yamamoto
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.,Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Akinori Awazu
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.,Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Naoaki Sakamoto
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan .,Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
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23
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Kameda T, Isami S, Togashi Y, Nishimori H, Sakamoto N, Awazu A. The 1-Particle-per-k-Nucleotides (1PkN) Elastic Network Model of DNA Dynamics with Sequence-Dependent Geometry. Front Physiol 2017; 8:103. [PMID: 28382002 PMCID: PMC5361685 DOI: 10.3389/fphys.2017.00103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 02/07/2017] [Indexed: 11/18/2022] Open
Abstract
Coarse-grained models of DNA have made important contributions to the determination of the physical properties of genomic DNA, working as a molecular machine for gene regulation. In this study, to analyze the global dynamics of long DNA sequences with consideration of sequence-dependent geometry, we propose elastic network models of DNA where each particle represents k nucleotides (1-particle-per-k-nucleotides, 1PkN). The models were adjusted according to profiles of the anisotropic fluctuations obtained from our previous 1-particle-per-1-nucleotide (1P1N) model, which was proven to reproduce such profiles of all-atom models. We confirmed that the 1P3N and 1P4N models are suitable for the analysis of detailed dynamics such as local twisting motion. The models are intended for the analysis of large structures, e.g., 10-nm fibers in the nucleus, and nucleoids of mitochondrial or phage DNA at low computational costs. As an example, we surveyed the physical characteristics of the whole mitochondrial human and Plasmodium falciparum genomes.
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Affiliation(s)
- Takeru Kameda
- Department of Mathematical and Life Sciences, Hiroshima University Hiroshima, Japan
| | - Shuhei Isami
- Department of Mathematical and Life Sciences, Hiroshima University Hiroshima, Japan
| | - Yuichi Togashi
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University Hiroshima, Japan
| | - Hiraku Nishimori
- Department of Mathematical and Life Sciences, Hiroshima UniversityHiroshima, Japan; Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima UniversityHiroshima, Japan
| | - Naoaki Sakamoto
- Department of Mathematical and Life Sciences, Hiroshima UniversityHiroshima, Japan; Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima UniversityHiroshima, Japan
| | - Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima UniversityHiroshima, Japan; Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima UniversityHiroshima, Japan
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24
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Kawazoe H, Nakano Y, Ochi H, Takagi M, Hayashi Y, Uchimura Y, Tokuyama T, Watanabe Y, Matsumura H, Tomomori S, Sairaku A, Suenari K, Awazu A, Miwa Y, Soejima K, Chayama K, Kihara Y. Risk stratification of ventricular fibrillation in Brugada syndrome using noninvasive scoring methods. Heart Rhythm 2016; 13:1947-54. [DOI: 10.1016/j.hrthm.2016.07.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Indexed: 11/29/2022]
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25
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Awazu A. Prediction of nucleosome positioning by the incorporation of frequencies and distributions of three different nucleotide segment lengths into a general pseudo k-tuple nucleotide composition. Bioinformatics 2016; 33:42-48. [PMID: 27563027 PMCID: PMC5860184 DOI: 10.1093/bioinformatics/btw562] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 08/02/2016] [Accepted: 08/19/2016] [Indexed: 11/13/2022] Open
Abstract
Motivation Nucleosome positioning plays important roles in many eukaryotic intranuclear processes, such as transcriptional regulation and chromatin structure formation. The investigations of nucleosome positioning rules provide a deeper understanding of these intracellular processes. Results Nucleosome positioning prediction was performed using a model consisting of three types of variables characterizing a DNA sequence—the number of five-nucleotide sequences, the number of three-nucleotide combinations in one period of a helix, and mono- and di-nucleotide distributions in DNA fragments. Using recently proposed stringent benchmark datasets with low biases for Saccharomyces cerevisiae, Homo sapiens, Caenorhabditis elegans and Drosophila melanogaster, the present model was shown to have a better prediction performance than the recently proposed predictors. This model was able to display the common and organism-dependent factors that affect nucleosome forming and inhibiting sequences as well. Therefore, the predictors developed here can accurately predict nucleosome positioning and help determine the key factors influencing this process. Supplementary information Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Akinori Awazu
- Department of Mathematical and Life Sciences.,Research Center for Mathematics on Chromatin Live Dynamics, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima, 739-8526, Japan
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26
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Lee SS, Tashiro S, Awazu A, Kobayashi R. A new application of the phase-field method for understanding the mechanisms of nuclear architecture reorganization. J Math Biol 2016; 74:333-354. [PMID: 27241726 PMCID: PMC5206286 DOI: 10.1007/s00285-016-1031-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 05/10/2016] [Indexed: 02/06/2023]
Abstract
Specific features of nuclear architecture are important for the functional organization of the nucleus, and chromatin consists of two forms, heterochromatin and euchromatin. Conventional nuclear architecture is observed when heterochromatin is enriched at nuclear periphery, and it represents the primary structure in the majority of eukaryotic cells, including the rod cells of diurnal mammals. In contrast to this, inverted nuclear architecture is observed when the heterochromatin is distributed at the center of the nucleus, which occurs in the rod cells of nocturnal mammals. The inverted architecture found in the rod cells of the adult mouse is formed through the reorganization of conventional architecture during terminal differentiation. Although a previous experimental approach has demonstrated the relationship between these two nuclear architecture types at the molecular level, the mechanisms underlying long-range reorganization processes remain unknown. The details of nuclear structures and their spatial and temporal dynamics remain to be elucidated. Therefore, a comprehensive approach, using mathematical modeling, is required, in order to address these questions. Here, we propose a new mathematical approach to the understanding of nuclear architecture dynamics using the phase-field method. We successfully recreated the process of nuclear architecture reorganization, and showed that it is robustly induced by physical features, independent of a specific genotype. Our study demonstrates the potential of phase-field method application in the life science fields.
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Affiliation(s)
- S Seirin Lee
- Department of Mathematical and Life Sciences, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, 739-8530, Japan.
| | - S Tashiro
- Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi 1-2-3, Hiroshima, 734-8553, Japan
- Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, 739-8530, Japan
| | - A Awazu
- Department of Mathematical and Life Sciences and Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, 739-8530, Japan
| | - R Kobayashi
- Department of Mathematical and Life Sciences and Research Center for the Mathematics on Chromatin Live Dynamics, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, 739-8530, Japan
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27
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Takemoto A, Miyamoto T, Simono F, Kurogi N, Shirae-Kurabayashi M, Awazu A, Suzuki KIT, Yamamoto T, Sakamoto N. Cilia play a role in breaking left-right symmetry of the sea urchin embryo. Genes Cells 2016; 21:568-78. [DOI: 10.1111/gtc.12362] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 02/25/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Ayumi Takemoto
- Department of Mathematical and Life Sciences; Graduate School of Science; Hiroshima University; Higashi-Hiroshima 739-8526 Japan
| | - Tatsuo Miyamoto
- Department of Genetics and Cell Biology; Research Institute for Radiation Biology and Medicine; Hiroshima University; Hiroshima 734-8553 Japan
| | - Fumie Simono
- Hiroshima Prefectural Hiroshima Kokutaiji High School; Hiroshima 730-0042 Japan
- An Educational Project for Exciting Science Learning for Pupils; Hiroshima University; Higashi-Hiroshima 739-8524 Japan
| | - Nao Kurogi
- Department of Mathematical and Life Sciences; Graduate School of Science; Hiroshima University; Higashi-Hiroshima 739-8526 Japan
| | - Maki Shirae-Kurabayashi
- Sugashima Marine Biological Laboratory; Graduate School of Science; Nagoya University; Mie 517-0004 Japan
| | - Akinori Awazu
- Department of Mathematical and Life Sciences; Graduate School of Science; Hiroshima University; Higashi-Hiroshima 739-8526 Japan
- Research Center for the Mathematics on Chromatin Live Dynamics; Hiroshima University; Higashi-Hiroshima 739-8526 Japan
| | - Ken-ichi T. Suzuki
- Department of Mathematical and Life Sciences; Graduate School of Science; Hiroshima University; Higashi-Hiroshima 739-8526 Japan
| | - Takashi Yamamoto
- Department of Mathematical and Life Sciences; Graduate School of Science; Hiroshima University; Higashi-Hiroshima 739-8526 Japan
- Research Center for the Mathematics on Chromatin Live Dynamics; Hiroshima University; Higashi-Hiroshima 739-8526 Japan
| | - Naoaki Sakamoto
- Department of Mathematical and Life Sciences; Graduate School of Science; Hiroshima University; Higashi-Hiroshima 739-8526 Japan
- Research Center for the Mathematics on Chromatin Live Dynamics; Hiroshima University; Higashi-Hiroshima 739-8526 Japan
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28
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Isami S, Sakamoto N, Nishimori H, Awazu A. Simple Elastic Network Models for Exhaustive Analysis of Long Double-Stranded DNA Dynamics with Sequence Geometry Dependence. PLoS One 2015; 10:e0143760. [PMID: 26624614 PMCID: PMC4666469 DOI: 10.1371/journal.pone.0143760] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 11/09/2015] [Indexed: 11/19/2022] Open
Abstract
Simple elastic network models of DNA were developed to reveal the structure-dynamics relationships for several nucleotide sequences. First, we propose a simple all-atom elastic network model of DNA that can explain the profiles of temperature factors for several crystal structures of DNA. Second, we propose a coarse-grained elastic network model of DNA, where each nucleotide is described only by one node. This model could effectively reproduce the detailed dynamics obtained with the all-atom elastic network model according to the sequence-dependent geometry. Through normal-mode analysis for the coarse-grained elastic network model, we exhaustively analyzed the dynamic features of a large number of long DNA sequences, approximately ∼150 bp in length. These analyses revealed positive correlations between the nucleosome-forming abilities and the inter-strand fluctuation strength of double-stranded DNA for several DNA sequences.
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Affiliation(s)
- Shuhei Isami
- Department of Mathematical and Life Sciences, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
| | - Naoaki Sakamoto
- Department of Mathematical and Life Sciences, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
- Research Center for Mathematics on Chromatin Live Dynamics, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
| | - Hiraku Nishimori
- Department of Mathematical and Life Sciences, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
- Research Center for Mathematics on Chromatin Live Dynamics, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
| | - Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
- Research Center for Mathematics on Chromatin Live Dynamics, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
- * E-mail:
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29
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Awazu A. Nuclear dynamical deformation induced hetero- and euchromatin positioning. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 92:032709. [PMID: 26465500 DOI: 10.1103/physreve.92.032709] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Indexed: 06/05/2023]
Abstract
We studied the role of active deformation dynamics in cell nuclei in chromatin positioning. Model chains containing two types of regions, with high (euchromatic) or low (heterochromatic) mobility, were confined in a pulsating container simulating a nucleus showing dynamic deformations. Brownian dynamic simulations show that the positioning of low mobility regions changes from sites near the periphery to the center if the affinity between these regions and the container periphery disappears. The former and latter positionings are similar to the "conventional" and "inverted" chromatin positionings in nuclei of normal differentiated cells and cells lacking Lamin-related proteins. Additionally, nuclear dynamical deformation played essential roles in "inverted" chromatin positioning.
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Affiliation(s)
- Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University and Research Center for Mathematics on Chromatin Live Dynamics, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
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Sugawara T, Masuda K, Uewaki JI, Awazu A, Nishimori H, Ueno M. Quantification of Interphase Chromatin Dynamics in Fission Yeast. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.2952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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31
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Awazu A. Segregation and phase inversion of strongly and weakly fluctuating Brownian particle mixtures and a chain of such particle mixtures in spherical containers. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 90:042308. [PMID: 25375495 DOI: 10.1103/physreve.90.042308] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Indexed: 06/04/2023]
Abstract
We investigate the segregation pattern formation of strongly and weakly fluctuating Brownian particle mixtures confined in a three-dimensional spherical container. We consider systems where the particle motion is restricted by the harmonic external trapping potential and the container edge wall. In such systems, two segregation patterns are observed. When the container radius is sufficiently large, more weakly fluctuating particles accumulate near the center of the container than strongly fluctuating particles. On the other hand, the distributions of the strongly and weakly fluctuating particles are inverted when the container radius is small. With no external trapping potentials, we find similar segregation and phase inversion if the particles construct a chain (heterofluctuating polymer) and are confined in a three-dimensional spherical container. We could apply these phenomena in the study of biopolymer behavior, such as chromosomes in the cell nucleus.
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Affiliation(s)
- Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan and Research Center for Mathematics on Chromatin Live Dynamics. Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
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32
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Ikura YS, Heisler E, Awazu A, Nishimori H, Nakata S. Collective motion of symmetric camphor papers in an annular water channel. Phys Rev E Stat Nonlin Soft Matter Phys 2013; 88:012911. [PMID: 23944542 DOI: 10.1103/physreve.88.012911] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Indexed: 06/02/2023]
Abstract
We investigate the collective motion of symmetric self-propelled objects that are driven by a difference in the surface tension. The objects move around an annular water channel spontaneously and interact through the camphor layer that develops on the water surface. We found that two collective motion modes, discrete and continuous density waves, are generated depending on the number of self-propelled objects. The two modes are characterized by examining the local and global dynamics, and the collective motion mechanism is discussed in relation to the distribution of camphor concentration in the annular water channel. We conclude that the difference between these two modes originates from that of the driving mechanism that pushes a camphor paper away from a cluster, through which mechanism density waves are generated and maintained.
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Affiliation(s)
- Yumihiko S Ikura
- Department of Mathematical and Life Sciences, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
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Abstract
We investigate the influences of the excluded volume of molecules on biochemical reaction processes on 2-dimensional surfaces using a model of signal transduction processes on biomembranes. We perform simulations of the 2-dimensional cell-based model, which describes the reactions and diffusion of the receptors, signaling proteins, target proteins, and crowders on the cell membrane. The signaling proteins are activated by receptors, and these activated signaling proteins activate target proteins that bind autonomously from the cytoplasm to the membrane, and unbind from the membrane if activated. If the target proteins bind frequently, the volume fraction of molecules on the membrane becomes so large that the excluded volume of the molecules for the reaction and diffusion dynamics cannot be negligible. We find that such excluded volume effects of the molecules induce non-trivial variations of the signal flow, defined as the activation frequency of target proteins, as follows. With an increase in the binding rate of target proteins, the signal flow varies by monotonically increasing; increasing then decreasing in a bell-shaped curve; or increasing, decreasing, then increasing in an S-shaped curve. We further demonstrate that the excluded volume of molecules influences the hierarchical molecular distributions throughout the reaction processes. In particular, when the system exhibits a large signal flow, the signaling proteins tend to surround the receptors to form receptor-signaling protein clusters, and the target proteins tend to become distributed around such clusters. To explain these phenomena, we analyze the stochastic model of the local motions of molecules around the receptor.
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Affiliation(s)
- Masashi Fujii
- Department of Mathematical and Life Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan.
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34
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Heisler E, Suematsu NJ, Awazu A, Nishimori H. Swarming of self-propelled camphor boats. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 85:055201. [PMID: 23004811 DOI: 10.1103/physreve.85.055201] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Indexed: 06/01/2023]
Abstract
When an ensemble of self-propelled camphor boats move in a one-dimensional channel, they exhibit a variety of collective behaviors. Under certain conditions, the boats tend to cluster together and move in a relatively tight formation. This type of behavior, referred to as clustering or swarming here, is one of three types recently observed in experiment. Similar clustering behavior is also reproduced in simulations based on a simple theoretical model. Here we examine this model to determine the clustering mechanism and the conditions under which clustering occurs. We also propose a method of quantifying the behavior that may be used in future experimental work.
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Affiliation(s)
- Eric Heisler
- Department of Mathematical and Life Sciences, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Japan
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35
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Niiya H, Awazu A, Nishimori H. Bifurcation analysis of the transition of dune shapes under a unidirectional wind. Phys Rev Lett 2012; 108:158001. [PMID: 22587286 DOI: 10.1103/physrevlett.108.158001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Indexed: 05/31/2023]
Abstract
A bifurcation analysis of dune shape transition is made. By use of a reduced model of dune morphodynamics, the Dune Skeleton model, we elucidate the transition mechanism between different shapes of dunes under unidirectional wind. It was found that the decrease in the total amount of sand in the system and/or the lateral sand flow shifts the stable state from a straight transverse dune to a wavy transverse dune through a pitchfork bifurcation. A further decrease causes wavy transverse dunes to shift into barchans through a Hopf bifurcation. These bifurcation structures reveal the transition mechanism of dune shapes under unidirectional wind.
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Affiliation(s)
- Hirofumi Niiya
- Department of Mathematical and Life Sciences, Hiroshima University, Higashihiroshima, Hiroshima 739-8526, Japan
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36
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Fujii M, Awazu A, Nishimori H. Segregation-pattern reorientation of a granular mixture on a horizontally oscillating tray. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 85:041304. [PMID: 22680466 DOI: 10.1103/physreve.85.041304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Indexed: 06/01/2023]
Abstract
Reorientation of the segregation pattern of a binary granular mixture on a two-dimensional horizontally oscillating tray is numerically realized. The mixture consists of large and heavy particles and small and light particles, and the segregation pattern shows a transition between a striped pattern perpendicular to the oscillation and one parallel to the oscillating direction according to the change of area fractions of the two types of particle. The transition mechanism is discussed on the basis of a simplified one-dimensional dynamics.
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Affiliation(s)
- Masashi Fujii
- Department of Mathematical and Life Sciences, Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
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37
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Kawai R, Awazu A, Nishimori H. Effective stochastic resonance of coupled excitable elements under noise of unequal amplitude. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 84:021135. [PMID: 21928977 DOI: 10.1103/physreve.84.021135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Indexed: 05/31/2023]
Abstract
Effective stochastic resonance (SR) is numerically studied using a model of two coupled excitable FitzHugh-Nagumo elements exposed to noise of unequal amplitude. Compared to previous SR models of a single excitable element and of two coupled excitable elements exposed to noise of equal amplitude, the present model exhibits a more intense resonance to the external signal. To extract the key dynamics of this effective SR, the idea of triggered excitation is introduced. Triggered excitation means a process in which the noise-free element is excited synchronously to the external signal with the triggering action of another element that randomly fluctuates asynchronously to the external signal. A deterministic simulation simply proving the triggered excitation process supports our idea.
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Affiliation(s)
- Ryosuke Kawai
- Department of Mathematical and Life Sciences, Hiroshima University, Kagamiyama, Higashi-hiroshima 739-8526, Japan
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38
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Kawai R, Torigoe S, Yoshida K, Awazu A, Nishimori H. Effective stochastic resonance under noise of heterogeneous amplitude. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 82:051122. [PMID: 21230452 DOI: 10.1103/physreve.82.051122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 04/27/2010] [Indexed: 05/30/2023]
Abstract
Stochastic resonance is numerically and analytically studied using a model wherein two coupled particles are exposed to noise of heterogeneous (i.e., particle-dependent) amplitude. In a certain range of coupling constant and under noise of heterogeneous amplitude, a particle is observed to resonate intensively to the external field. In other words, one particle under noise of very small or zero amplitude exhibits intensive resonance with the assistance of a highly fluctuating second particle under noise of large amplitude. This intensive resonance is interpreted as a product of the unique combinatory dynamics between one particle that stochastically fluctuates and another particle that classically resonates to the external field.
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Affiliation(s)
- Ryosuke Kawai
- Department of Mathematical and Life Sciences, Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan
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39
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Fujii M, Awazu A, Nishimori H. Saddle-node bifurcation to jammed state for quasi-one-dimensional counter-chemotactic flow. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 82:015102. [PMID: 20866675 DOI: 10.1103/physreve.82.015102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Indexed: 05/29/2023]
Abstract
The transition of a counter-chemotactic particle flow from a free-flow state to a jammed state in a quasi-one-dimensional path is investigated. One of the characteristic features of such a flow is that the constituent particles spontaneously form a cluster that blocks the path, called a path-blocking cluster (PBC), and causes a jammed state when the particle density is greater than a threshold value. Near the threshold value, the PBC occasionally collapses on itself to recover the free flow. In other words, the time evolution of the size of the PBC governs the flux of a counter-chemotactic flow. In this Rapid Communication, on the basis of numerical results of a stochastic cellular automata (SCA) model, we introduce a Langevin equation model for the size evolution of the PBC that reproduces the qualitative characteristics of the SCA model. The results suggest that the emergence of the jammed state in a quasi-one-dimensional counterflow is caused by a saddle-node bifurcation.
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Affiliation(s)
- Masashi Fujii
- Department of Mathematical and Life Sciences, Hiroshima University, Hiroshima, Japan.
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Awazu A, Kaneko K. Discreteness-induced slow relaxation in reversible catalytic reaction networks. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 81:051920. [PMID: 20866274 DOI: 10.1103/physreve.81.051920] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 04/15/2010] [Indexed: 05/29/2023]
Abstract
Slowing down of the relaxation of the fluctuations around equilibrium is investigated both by stochastic simulations and by analysis of master equation of reversible reaction networks consisting of reactions between a pair of resource and the corresponding high-energy product that works as a catalyst for another resource-product reaction. As the number of molecules N is decreased, the relaxation time to equilibrium is prolonged due to the deficiency of catalysts, as demonstrated by the amplification compared to that by the continuum limit. This amplification ratio of the relaxation time is represented by a scaling function as h=N exp(-βV), and it becomes prominent as N becomes less than a critical value h ∼ 1, where β is the inverse temperature and V is the energy required to the transformation from resources to the corresponding products.
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Affiliation(s)
- Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
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Suematsu NJ, Nakata S, Awazu A, Nishimori H. Collective behavior of inanimate boats. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 81:056210. [PMID: 20866310 DOI: 10.1103/physreve.81.056210] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 03/16/2010] [Indexed: 05/29/2023]
Abstract
We propose an inanimate system composed of camphor boats in an annular water channel in order to understand the collective motions. The boats move on the water surface spontaneously and interact with one another through the concentration of the camphor molecules on the water. We observed several modes of collective motion, e.g., behaviors analogous to traffic flow or an ant trail. Our system provides a convenient experimental setup for the investigation of a variety of collective motions.
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Affiliation(s)
- Nobuhiko J Suematsu
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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Abstract
Study of reversible catalytic reaction networks is important not only as an issue for chemical thermodynamics but also for protocells. From extensive numerical simulations and theoretical analysis, slow relaxation dynamics to sustain nonequlibrium states are commonly observed. These dynamics show two types of salient behaviors that are reminiscent of glassy behavior: slow relaxation along with the logarithmic time dependence of the correlation function and the emergence of plateaus in the relaxation-time course. The former behavior is explained by the eigenvalue distribution of a Jacobian matrix around the equilibrium state that depends on the distribution of kinetic coefficients of reactions. The latter behavior is associated with kinetic constraints rather than metastable states and is due to the absence of catalysts for chemicals in excess and the negative correlation between two chemical species. Examples are given and generality is discussed with relevance to bottleneck-type dynamics in biochemical reactions as well.
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Affiliation(s)
- Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
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Awazu A, Kaneko K. Self-organized criticality of a catalytic reaction network under flow. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:010902. [PMID: 19658645 DOI: 10.1103/physreve.80.010902] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Revised: 06/03/2009] [Indexed: 05/28/2023]
Abstract
Self-organized critical behavior in a catalytic reaction network system induced by smallness in the molecule number is reported. The system under a flow of chemicals is shown to undergo a transition from a stationary to an intermittent reaction phase when the flow rate is decreased. In the intermittent reaction phase, two temporal regimes with active and halted reactions alternate. The number frequency of reaction events at each active regime and its duration time are shown to obey a universal power law with the exponents 4/3 and 3/2, respectively, independently of the parameters and network structure. These power laws are explained by a one-dimensional random-walk representation of the number of catalytically active chemicals. Possible relevance of the result to reaction dynamics in artificial and biological cells is briefly discussed.
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Affiliation(s)
- Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
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Awazu A. Input-dependent wave propagations in asymmetric cellular automata: possible behaviors of feed-forward loop in biological reaction network. Math Biosci Eng 2008; 5:419-427. [PMID: 18616349 DOI: 10.3934/mbe.2008.5.419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Dynamical aspects of the asymmetric cellular automata were investigated to consider the signaling processes in biological systems. As a meta-model of the cascade of feed-forward loop type network motifs in biological reaction networks, we consider the one dimensional asymmetric cellular automata where the state of each cell is controlled by a trio of cells, the cell itself, the nearest upstream cell and the next nearest upstream cell. Through the systematic simulations, some novel input-dependent wave propagations were found in certain asymmetric CA, which may be useful for the signaling processes like the distinction, the filtering and the memory of external stimuli.
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Affiliation(s)
- Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University, Higashi-Hiroshima, Japan.
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Abstract
Pattern formations in populations of "pulsating particles" which can autonomously vary their volumes were investigated. It was found that clusters of pulsating particles whose pulsation frequencies depend on the number of other particles in the vicinity form the following dynamical network structures: (i) void type networks exhibiting large voids, and (ii) branching type networks consisting of individual branches. Such global structures are formed through the annihilation and creation of local structures in the particle populations induced by tug-of-war-like interactions among them.
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Affiliation(s)
- Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
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Awazu A, Kaneko K. Discreteness-induced transition in catalytic reaction networks. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 76:041915. [PMID: 17995034 DOI: 10.1103/physreve.76.041915] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Revised: 09/13/2007] [Indexed: 05/25/2023]
Abstract
Drastic change in dynamics and statistics in a chemical reaction system, induced by smallness in the molecule number, is reported. Through stochastic simulations for random catalytic reaction networks, transition to a state is observed with the decrease in the total molecule number N , characterized by (i) large fluctuations in chemical concentrations as a result of intermittent switching over several states with extinction of some molecule species and (ii) strong deviation of time averaged distribution of chemical concentrations from that expected in the continuum limit, i.e., N-->infinity. The origin of transition is explained by the deficiency of the molecule leading to termination of some reactions. The critical number of molecules for the transition is obtained as a function of the number of molecule species M and that of reaction paths K, while total reaction rates, scaled properly, are shown to follow a universal form as a function of NK/M.
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Affiliation(s)
- Akinori Awazu
- Department of Mathematical and Life Sciences, Hiroshima University, Kagami-yama 1-3-1, Higashi-Hiroshima 739-8526, Japan
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Awazu A, Kaneko K. Pulse replications and spatially differentiated structure formation in one-dimensional lattice dynamical system. Math Biosci 2006; 201:90-100. [PMID: 16458329 DOI: 10.1016/j.mbs.2005.12.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Revised: 07/14/2005] [Accepted: 12/03/2005] [Indexed: 11/28/2022]
Abstract
Replication and differentiation of pulses are studied through a simple dynamical system on a one-dimensional lattice. Depending on the parameter values, our proposed system exhibits the following types of pulse replications: (I) each pulse replicates by itself, (II) each pulse replicates if two or more pulses collide each other, and (III) pulses replicate by the organization of pulse generators. Moreover, replicated pulses construct the spatial-temporal pattern when the number of pulses is large. By selecting local objects in such spatial-temporal patterns and replanting them numerically, it is found that there are two types differentiated local structures: one that continues the production of pulses and the other that does not.
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Affiliation(s)
- Akinori Awazu
- Department of Physics, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
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Abstract
Relaxation processes in a closed chemical reaction-diffusion system which can potentially form Turing-like patterns during the transient are investigated to address the question given by the title. We find that when certain conditions are fulfilled the relaxation process is indeed drastically hindered, once the pattern is formed. This slowing down is shown to be due to stepwise relaxation, where each plateau in the relaxation process corresponds to residence at a certain spatial pattern. Mechanism and universality of the phenomena are discussed.
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Affiliation(s)
- Akinori Awazu
- Department of Pure and Applied Sciences, University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan
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Awazu A. Liquid-solid phase transition of a system with two particles in a rectangular box. Phys Rev E Stat Nonlin Soft Matter Phys 2001; 63:032102. [PMID: 11308689 DOI: 10.1103/physreve.63.032102] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2000] [Indexed: 05/23/2023]
Abstract
We study the statistical properties of two hard spheres in a two-dimensional rectangular box. In this system, a relation similar to the van der Waals equation is obtained between the width of the box and the pressure working on the sidewalls. The autocorrelation function of each particle's position is calculated numerically. This calculation shows that, near the critical width, the time at which the correlation becomes zero gets longer as the height of the box increases. Moreover, fast and slow relaxation processes such as the alpha and beta relaxations in supercooled liquids are observed when the height of the box is sufficiently large. These relaxation processes are discussed with reference to the probability distribution of the relative positions of the two particles.
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Affiliation(s)
- A Awazu
- Department of Mathematical Sciences, Osaka Prefecture University, Sakai 599-8531, Japan.
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Awazu A. Size segregation and convection of granular mixtures almost completely packed in a thin rotating Box. Phys Rev Lett 2000; 84:4585-4588. [PMID: 10990746 DOI: 10.1103/physrevlett.84.4585] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/1999] [Indexed: 05/23/2023]
Abstract
We simulate size segregation in granular mixtures which are almost completely packed in a rotating drum. Instead of a 3D drum, we simulate a 2D thin rotating box which is almost completely packed with granular mixtures. The phase inversion of a radially segregated pattern which was found in a 3D experiment is qualitatively reproduced with this simulation. A global convection appears after a radial segregation pattern is formed, and this convection induces an axially segregated pattern.
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Affiliation(s)
- A Awazu
- Department of Mathematical Sciences, Osaka Prefecture University, Sakai 593, Japan
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