Biology subjects

Tanabe, H.

Publications and source records attributed to Tanabe, H..

5 recordsLinked to original sources

bioRxiv2026

Light-dependent changes in the higher-order DNA structure of the cyanobacterium Synechocystis sp. PCC 6803

Chromosome spatial organization plays critical roles in transcriptional regulation and DNA protection. In cyanobacteria--photosynthetic bacteria that experience dramatic fluctuations in light intensity--chromosome reorganization could facilitate rapid transcriptional reprogramming and protect DNA from photodamage. However, chromosome organization in these polyploid organisms has remained technically challenging to observe, leaving light-dependent responses unexplored. Here, we show that higher-order chromosome organization in Synechocystis sp. PCC 6803 is associated with light intensity, revealing a previously unrecognized light-dependent adaptation in cyanobacteria. We established fluorescence in situ hybridization (FISH) methods for this model cyanobacterium carrying multi-copy genomes, together with a computational pipeline to assign paired FISH signals to individual genome copies. The slope relating genomic and spatial distance was steeper under standard conditions ({beta} = 0.972 nm/kbp, R{superscript 2} = 0.12) than under high-light conditions ({beta} = 0.450 nm/kbp, R{superscript 2} = 0.02), indicating that local chromosome organization is substantially disrupted by elevated light intensity. The spatial distribution of the multiple genome copies also differed between conditions, independently supporting condition-dependent chromosome reorganization. Hi-C analysis corroborated these findings, revealing reduced chromosomal interactions within the 10-100 kbp range under high-light conditions. Together, these results demonstrate that light intensity is a previously unrecognized determinant of higher-order chromosome organization in a photosynthetic bacterium.

microbiology↗

bioRxiv2025

Condensin II collaborates with cohesin to establish and maintain interphase chromosome territories

Despite the well-established role of condensin II in mitotic chromosome assembly, its function in interphase chromosome organization remains poorly understood. Here, we applied multiscale fluorescence in situ hybridization (FISH) techniques to human cell lines engineered for single or double depletion of condensin II and cohesin, and examined their functional interplay at two distinct stages of the cell cycle. Our results demonstrate that a functional "handover" from condensin II to cohesin during the mitosis-to-G1 transition is critical for establishing chromosome territories (CTs) in the newly assembling nucleus. During G2 phase, condensin II and cohesin cooperate to maintain global CT morphology, although they act at different genomic scales. Strikingly, double depletion of both complexes causes CTs to collapse and accumulate abnormally at the nucleolar periphery. Based on these findings, we will discuss how the condensin and cohesin complexes act in an orderly and cooperative manner to orchestrate chromatin dynamics across genomic scales, thereby supporting higher-order chromosome organization throughout the cell cycle.

cell biology↗

bioRxiv2025

Immune-induced TCR-like antibodies regulate specific T cell response

Antigen-specific regulation of T cell response is crucial for limiting hyperimmune response. In this study, we discovered that antibodies specific to the antigen peptide-MHC class II complex are produced during helper T cell responses to various antigens. These antibodies specifically inhibited T cell receptor (TCR) recognition of MHC class II molecules presenting specific antigen peptide. We have termed these antibodies immuneinduced TCR-like antibodies (iTabs). Immunization with peptides containing flanking residues induced iTabs, whereas immunization with peptides lacking flanking residues did not. Furthermore, immunization of iTab-inducible peptide as well as iTab treatment suppressed autoimmune disease development. Our findings provide a strategy for suppressing antigen-specific helper T cell responses using specific peptides, potentially controlling autoimmune diseases.

immunology↗

bioRxiv2024

B chromosome and its non-Mendelian inheritance in Atractylodes lancea

Supernumerary B chromosomes contribute to intraspecific karyotypic variation. B chromosomes have been detected in more than 2000 organisms; they possess unique and diverse features, including non-Mendelian inheritance. Here we report one or more B chromosomes in the gynodioecious plant, Atractylodes lancea. Among 54 A. lancea lines, 0-2 B chromosomes were detected in both hermaphroditic and female plants, with the B chromosomes appearing as DAPI-bright regions within the nuclei. Genomic in situ hybridization revealed that the B chromosomes had no conserved A chromosome DNA sequences, which was confirmed by fluorescence in situ hybridization probed with independently dissected B chromosomes. In male meiosis, the B chromosome did not pair with an A chromosome and was therefore eliminated; accordingly, only 20.1% and 18.6% of these univalent B chromosomes remained at the end of meiosis for the 1B lines of KY17-148 and KY17-118, respectively. However, we also found that B chromosomes were transmitted from male parents in 40.8%-44.2% and 47.2% of the next generation; although these transmission rates from male parents were not essentially different from Mendelian inheritance (0.5), the transmission of gametes carrying B chromosomes increased through fertilization or seed development. B chromosomes were transmitted from three of four 1B female parents to 64.3%-92.6% of the next generation, suggesting B chromosome accumulation. We propose that the B chromosome of A. lancea has a specific sequence and persists via non-Mendelian inheritance from female parents. Overall, A. lancea is a useful material for understanding the structure, evolution, and mechanism of non-Mendelian inheritance of B chromosomes.

genetics↗

bioRxiv2022

Analysis of IGHA1 and other salivary proteins post half marathon in female participants

BackgroundHigh intensity exercise, such as in marathons and triathlons, suppresses transient local and systemic immunity. Much is known about the systemic immunosuppression response, but little is known about its local response in the oral cavity, lungs, bronchial tubes, and skin. The oral cavity is an entrance for bacteria or viruses to enter the body. Saliva covers the epidermis of the oral cavity and plays an important role in the local stress response by preventing infection. In this study, we examined the properties of saliva secreted during the local stress response induced by a half marathon (HM) using quantitative proteomic analysis. MethodsThe Exercise group (ExG), 19 healthy female university students participated in (HM) race. The non-exercise group (NExG), 16 healthy female university students had not participated in the ExG. In ExG, saliva samples were collected 1h pre and 2h and 4h post HM. NExG were collected in same time interval. Saliva volume, protein concentration and relative IGHA1 expression were analyzed. In addition, 1h pre and 2h post HM saliva were analyzed by iTRAQ. The identified factors of iTRAQ, analyzed for the ExG and NExG by western blotting. ResultsWe identified kallikrein 1 (KLK1), immunoglobulin kappa chain (IgK) and cystatin S (CST4) as suppression factors, as well as immunoglobulin heavy constant alpha 1 (IGHA1), which has been reported as an immunological stress marker. KLK1 (p = 0.011), IGK (p = 0.002), and CST4 (p = 0.003) were suppressed 2 h post-HM compared to pre-HM, and KLK1 (p = 0.004) and CST4 (p = 0.006) were suppressed 4 h post-HM. There was also a positive correlation between IGHA1, IGK, and CST4 2 and 4 h post-HM. In addition, KLK1 and IGK after 2 h post-HM showed a positive correlation. ConclusionOur study demonstrated that the salivary proteome is regulated and antimicrobial proteins are suppressed post-HM. These results suggest that oral immunity was transiently suppressed post-HM. The positive correlation of each protein at 2 and 4 h post-HM suggests that the suppressed state was similarly regulated up to 4 h after a HM. The proteins identified in this study may have applications as stress markers for recreational runners and individuals who perform high- and moderate-intensity exercises in their daily lives.

physiology↗