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Akinori Awazu

Publications and source records attributed to Akinori Awazu.

4 recordsLinked to original sources

Integrative modeling of the genome structure and dynamics in fission yeast.

Genome organization in the nucleus is highly structured and dynamic. Recent advances in genomic technology have enabled the measurement of genome-wide architecture and locus-specific motion, yielding contact maps and live-cell trajectories. However, these outcomes are derived from different modalities and are not directly comparable, with their quantitative integration being a key challenge. Here we establish a genome-wide live-cell imaging platform in fission yeast Schizosaccharomyces pombe, tracking 131 chromosomal loci, along with the spindle pole body (SPB) and nucleolus, to construct a quantitative map of locus dynamics. By integrating these dynamics with contact data through polymer modeling of Hi-C data, we build a physics-based "digital twin" of the S. pombe genome consistent with the spatiotemporal dynamics of interphase chromatin. We validate it against genome-wide mobility patterns and known architectural features, including centromere and telomere clustering. The model also identifies distinct dynamical regimes: centromere- and telomere-proximal loci relax within [Formula: see text]150 s, whereas the remaining loci relax within [Formula: see text]70 s. We measure semiperiodic dynamics of SPB motion, including a characteristic peak near 225 s and [Formula: see text] fluctuations. We use the model with SPB-directed forcing to show how these low-frequency components propagate through the genome to drive genome-wide chromatin displacements. Together, this predictive physics-based modeling framework integrates genome structure and dynamics to reveal how nuclear mechanical driving forces shape chromosome motion, linking mechanically driven chromatin responses to genome maintenance and regulation.

Schizosaccharomyces↗

Extrinsic heterogeneity: Collectivity in isotropic conformational fluctuations of chromosomes.

Eukaryotic interphase chromosomes maintain a three-dimensional conformation within the nucleus and undergo fluctuations. However, the analysis of chromosome conformational fluctuations has been mainly limited to chromosome conformation capture data that record the contact frequencies between chromosomal regions. Herein, we investigated chromosome fluctuations as polymers based on experimental data from sequential fluorescence in situ hybridization using a multiomics methodology. To describe the principal modes of chromosome fluctuations, we applied principal-component analysis to the three-dimensional conformation information of single chromosomes in 446 mouse embryonic stem cells obtained from sequential fluorescence in situ hybridization data analysis for spatial genomics and signals of nuclear factors (histone marks, repeat DNAs, and proteins in interchromosomal nuclear compartments). We found that chromosome fluctuations exhibit both isotropic and anisotropic modes. The isotropic conformational fluctuations of all chromosome types tended to synchronize each other, reflecting extrinsic heterogeneity in chromosome conformation that is independent of the cell cycle. In contrast, anisotropic conformational fluctuations, occurring in a spindle-like shape, were associated with the interactions between repeat DNAs and nuclear factors. These results highlight the importance of dissecting cell-cycle-independent nuclear organization based on the conformational folding of chromosomes and the interactions between genomic regions and nuclear factors.

Animals↗

Pulse replications and spatially differentiated structure formation in one-dimensional lattice dynamical system.

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.

Diffusion↗

Relaxation to equilibrium can be hindered by transient dissipative structures.

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.

Journal Article↗