Biology subjects

Morita, R.

Publications and source records attributed to Morita, R..

12 recordsLinked to original sources

bioRxiv2026

OsPATROL1 overexpression accelerates stomatal opening to enhance photosynthetic induction and growth under fluctuating light in rice

Slow stomatal opening after increases in irradiance constrains carbon gain under fluctuating light, yet stomatal kinetics remain an underexplored target for crop improvement. Here, we investigated Oryza sativa PROTON ATPASE TRANSLOCATION CONTROL 1 (OsPATROL1), which encodes a Munc13-like protein implicated in stomatal regulation in Arabidopsis thaliana. OsPATROL1 overexpression had modest, condition-dependent effects on steady-state gas exchange and did not alter stomatal morphology or biochemical traits. In contrast, it consistently accelerated stomatal opening and photosynthetic induction, reducing the stomatal conductance time constant during induction by 41-43%. During 12 h of simulated natural fluctuating light, OsPATROL1-overexpressing plants maintained higher stomatal conductance and net CO2 assimilation rate, increasing cumulative assimilation by 8-12% while maintaining their intrinsic water-use efficiency (iWUE). Under artificial fluctuating light, overexpression alleviated growth reductions relative to steady light. Under glasshouse conditions, total biomass increased by 34-44%, accompanied by greater tiller number, root biomass, bleeding sap rate, and leaf nitrogen content. Taken together, these results indicate that OsPATROL1 overexpression accelerates stomatal opening, enhances photosynthetic induction and daytime carbon gain without compromising iWUE, and is associated with greater growth.

plant biology↗

bioRxiv2026

Rice Jumonji706 confers the photoperiod sensitivity in rice by distinct regulation of short-day and long-day flowering time regulatory pathways.

Photoperiod sensitivity (PS) is a key biological response in plants as they adapt to specific environments. Rice (Oryza sativa L.) exhibits a clear PS, as it implements critical phase transition decisions based on PS signals. In this study, we identified a novel PS gene, JMJ706, that is expected to deliver photoperiod-related signals to the flowering-time regulatory network in a day-length-dependent manner. The JMJ706 mutants exhibit early flowering under LD and later flowering under SD compared to WT plants. The gene encodes an H3K9me2 demethylase, and under long-day (LD) conditions, its demethylase activity facilitates the expression of Grain number, Plant height, and Heading-date7 (Ghd7). Since Ghd7 is a floral repressor in LD, it promotes the vegetative phase by delaying flowering. Under short-day conditions (SD), H3K9me2 demethylase activity facilitates Early heading-date 1 (Ehd1) expression, and it acts as a floral accelerator by inducing Heading date 3 (Hd3a) and RICE FLOWERING LOCUS T 1 (RFT1). Furthermore, we propose that the daylength-dependent promotion of target genes (Ghd7 and Ehd1) occurs through demethylation of specific promoter regions at a crucial time window. In addition, JMJ706 may play an important role in regulating plant architecture, including plant height. The natural variation in JMJ706 alleles shows high frequencies across major rice subpopulations, suggesting that JMJ706 could play an important role in the geographical distribution and adaptation of rice cultivars. Our results may add a new layer to the rice flowering-time regulatory pathway, supporting regional adaptation and potential for future breeding.

plant biology↗

bioRxiv2026

Structural basis of lenacapavir-induced HIV-1 capsid disruption during virion maturation

Long-acting lenacapavir (LEN) has emerged as a highly effective, potentially game-changing therapy for HIV treatment and prevention1-5. Although its mechanism of action in the early phase of HIV-1 replication, when the capsid directs key post-entry steps such as reverse transcription, nuclear import, and integration, has been well characterized1,2,6-8, its effects during the late phase of replication, when the capsid assembles and matures within budding virions, remain poorly understood. Here, we determine the cryo-electron microscopy structure of the mature HIV-1 capsid lattice assembled within virus-like particles in the presence of LEN. Our structural analyses revealed that LEN alters interhexamer interactions, perturbs capsid lattice curvature, and thereby prevents the formation of a functional cone-shaped capsid. Biochemical analyses further demonstrated that LEN-containing cores lose reverse transcriptase due to a compromised capsid integrity, whereas integrase and viral RNA remain associated. Functionally, viruses produced in the presence of LEN exhibited markedly reduced infectivity, low reverse transcription activity, and poor integration. Together, these findings provide mechanistic insight into the late-phase action of LEN and provide key directions for the design of future inhibitors.

microbiology↗

bioRxiv2026

Structural volume composition of internodes determines culm non-structural carbohydrates accumulation in rice

Non-structural carbohydrates (NSC) stored in the stem play a crucial role in supporting yield formation in rice. However, internode morphological determinants of NSC accumulation are unclear. This study aimed to clarify the relationship between internode morphology and NSC accumulation and to identify a robust morphological indicator for evaluating NSC accumulation capacity. Two years of field experiments were conducted using multiple cultivars. The NSC content was quantified for individual internodes and at the whole-plant culm level, and its relationships with internode morphological traits were analyzed. Since the upper internodes (UIN; first and second internodes) and lower internodes (LIN; third and subsequent internodes) exhibited contrasting roles in NSC accumulation, a novel index was introduced, the volume composition ratio (VCR) of UIN/LIN, which represents their relative volumetric contributions within a culm. The VCR of UIN/LIN showed the strongest correlation with culm NSC and high reproducibility across years, outperforming simple morphological traits. Manipulation of internode development using plant growth regulators demonstrated that altering VCR effectively modified culm NSC accumulation. Accordingly, the VCR of UIN/LIN serves as a robust morphological indicator of culm NSC accumulation capacity, providing a practical framework for improving NSC accumulation to achieve high and stable yield performance in rice. HighlightThis novel internode structural index robustly predicts the culm non-structural carbohydrate accumulation capacity, providing a practical morphological indicator for improving yield stability in rice.

plant biology↗

bioRxiv2025

Identification of an early-heading mutant in Indonesian native rice cultivar: 'Gemdjah Beton'

Rice is one of the worlds most widely cultivated field crops and a short-day adapted plant. It possesses a complex genetic regulatory mechanism for heading date determination. Gemdjah Beton (GB) is an Indonesian rice cultivar that takes approximately 17 weeks to flower after being transplanted into a rice field in Japan. We isolated early-heading mutant line GB-10 (flowers around two to three weeks early in the field). Under long-day (LD) conditions, GB-10 flowered approximately two weeks earlier than GB. Under short-day conditions, the heading date between GB-10 and GB plants shows no apparent difference. In agreement with the heading date, Hd3a and RFT1 expressions show around a 10-time relative transcript quantity difference under LD conditions in GB-10 compared to GB. Interestingly, Ghd7 expression was significantly reduced in GB-10, which may trigger the Hd3a and RFT1 activation. A bulk segregation analysis indicated that a single nucleotide variant on chromosome 7 was genetically linked to the early heading phenotype of GB-10 lines. Taken together, we reported the successful isolation of GB-10 as an early-heading mutant.

plant biology↗

bioRxiv2025

IL-18 produced by pregnant uterus promotes essential inflammatory responses and fetoplacental growth

Placental insufficiency affects fetomaternal health throughout life. Although the interaction between the maternal uterine immune milieu and fetal-derived cells plays a crucial role in placental formation, several aspects remain unclear. Therefore, we conducted this study to investigate the effects of interleukin (IL)- 18, a unique cytokine with both proinflammatory and anti-inflammatory properties, on the uterine immune milieu and placental development. Our results identified pregnant uterine smooth muscle cells as an important source of IL-18, which supports homeostatic type 1 immune responses. IL-18 facilitates appropriate placental development through uterine vascular remodeling and placental angiogenesis. Smooth muscle cell-specific Il18-knockout dam mice exhibited impaired fetoplacental growth and elevated maternal blood pressure, reflecting preeclampsia-like phenotypes. Their offspring demonstrated a tendency toward excessive weight gain and delayed neurodevelopment. Overall, this study emphasizes the essential role of IL-18 in placental formation and its wider implications for fetomaternal health. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/649615v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@27862eorg.highwire.dtl.DTLVardef@da4786org.highwire.dtl.DTLVardef@8dd7e2org.highwire.dtl.DTLVardef@584c41_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LISmooth muscle cells in the pregnant uterine myometrium sufficiently produce IL-18 C_LIO_LIIL-18 induces type 1 immune responses in the uterine immune milieu C_LIO_LIIL-18 promotes maternal uterine vascular remodeling and placental angiogenesis C_LIO_LIIL-18-signaling deficiency in the mouse model shows the preeclampsia-like clinical course C_LI

immunology↗

bioRxiv2024

Ex vivo SIM-AFM measurements reveal the spatial correlation of stiffness and molecular distributions in 3D living tissue

Living tissues each exhibit a distinct stiffness, which provides cells with key environmental cues that regulate their behaviors. Despite this significance, our understanding of the spatiotemporal dynamics and the biological roles of stiffness in three-dimensional tissues is currently limited due to a lack of appropriate measurement techniques. To address this issue, we propose a new method combining upright structured illumination microscopy (USIM) and atomic force microscopy (AFM) to obtain precisely coordinated stiffness maps and biomolecular fluorescence images of thick living tissue slices. Using mouse embryonic skin as a representative tissue with mechanically heterogeneous structures inside, we validate the measurement principle of USIM-AFM. Live measurement of tissue stiffness distributions revealed the highly heterogeneous mechanical nature of embryonic skin as well as the role of collagens in maintaining its integrity. Furthermore, quantitative comparisons of stiffness distributions of preserved tissue samples unveiled the distinct impacts of conventional tissue preservation techniques on the tissue stiffness pattern. This series of experiments highlights the importance of live mechanical testing of tissue-scale samples. Our USIM-AFM technique provides a new methodology to reveal the dynamic nature of tissue stiffness and its correlation with biomolecular distributions in live tissues and thus could serve as a technical basis for exploring tissue-scale mechanobiology. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=89 SRC="FIGDIR/small/595975v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@8a32f5org.highwire.dtl.DTLVardef@117a350org.highwire.dtl.DTLVardef@e2fb99org.highwire.dtl.DTLVardef@1f41d24_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2023

Col4a2-eGFP mouse model reveals the molecular and functional dynamics of basement membrane remodelling in hair follicle morphogenesis

The precisely controlled remodelling of the basement membrane (BM) is considered vital for morphogenesis. However, the molecular and tissue-level dynamics of the BM during morphogenesis and their functional significance remain largely unknown, especially in mammals, due to limited visualization tools. We developed knock-in mouse lines in which the endogenous collagen IV gene (Col4a2) was fused with a fluorescent tag. Through live imaging of developing hair follicles, we revealed a spatial gradient in the turnover rate of COL4A2 that is closely coupled with the BM expansion rate. The proliferation of epithelial progenitors coincided with the increased expansion of their underlying BM. Epithelial progenitors displaced with directionally expanding BM, but did not actively migrate on stable BM. The addition of a matrix metalloproteinase inhibitor delayed the turnover of COL4A2, restrained the expansion of the BM, and induced a directional shift in the division angle of epithelial progenitors, altering the hair follicle morphology. Our findings revealed spatially distinct BM dynamics within the continuous epithelial BM and affirmed their significance in orchestrating the proliferation, movement and fate of progenitor cells, as well as the macro-level shape of organs during development.

developmental biology↗

bioRxiv2023

Yeast PRPP amidotransferase assembles into fine granules to promote de novo purine synthesis through intermolecular substrate channeling

De novo purine synthesis (DPS) is up-regulated under conditions of high purine demand to ensure the production of genetic materials and chemical energy, thereby supporting cell proliferation. However, the regulatory mechanisms governing DPS remain largely unclear. We herein show that PRPP amidotransferase (PPAT), the rate-limiting enzyme in DPS, forms dynamic and motile condensates in Saccharomyces cerevisiae cells under a purine-depleted environment. The formation of condensates requires phase separation, which is driven by target of rapamycin complex 1 (TORC1)-induced ribosome biosynthesis. The self-assembly of PPAT molecules facilitates condensate formation, with intracellular PRPP and purine nucleotides both regulating this self-assembly. Moreover, molecular dynamics simulations suggest that clustering-mediated PPAT activation occurs through intermolecular substrate channeling. Cells unable to form PPAT condensates exhibit growth defects, highlighting the physiological importance of condensation. These results suggest that PPAT condensation is an adaptive mechanism that regulates DPS in response to both TORC1 activity and cellular purine demands. HighlightsO_LIPRPP amidotransferase (PPAT) in budding yeast forms dynamic intracellular condensates in response to environmental purine deprivation. C_LIO_LIRibosome crowding in the cytoplasm, induced by TORC1, drives the assembly of PPAT condensates. C_LIO_LIThe purified PPAT protein alone condensates into submicron-sized particles in vitro under molecular crowding conditions. C_LIO_LIPurine nucleotides inhibit the self-assembly of PPAT, while PRPP promotes this process and counteracts the inhibition. C_LIO_LIThe condensation of PPAT facilitates the intermolecular channeling of intermediates, thereby enhancing de novo purine synthesis. C_LI

cell biology↗

bioRxiv2022

Autism-associated mutation in Hevin/Sparcl1 induces endoplasmic reticulum stress through structural instability

Hevin is a secreted extracellular matrix protein that is encoded by SPARCL1 gene. Recent studies show that Hevin plays an important role in regulating synaptogenesis and synaptic plasticity. Mutations in SPARCL1 gene increase the risk of autism spectrum disorder (ASD). However, the molecular basis of how mutations in SPARCL1 increase the risk of ASD has not been fully understood. In this study, we show that one of SPARCL1 mutations associated with ASD impairs normal Hevin secretion. We identified Hevin mutants lacking the EF-hand motif through analyzing ASD-related mice with vulnerable spliceosome functions. Hevin deletion mutants accumulate in the ER, leading to the activation of unfolded protein responses. We also found that a single amino acid substitution of Trp647 with Arg in the EF-hand motif associated with a familial case of ASD causes a similar phenotype with the EF-hand deletion mutant. Importantly, molecular dynamics (MD) simulation revealed that this single amino acid substitution triggers exposure of hydrophobic amino acid to the surface, increasing the binding of Hevin with a molecular chaperon, BIP. Taken together, these data suggest that the integrity of EF-hand motif in Hevin is crucial for proper folding and ASD-related mutation impairs an export of Hevin from the endoplasmic reticulum (ER). Our data provide a novel mechanism linking a point mutation in SPARCL1 gene to the molecular and cellular characteristics involved in ASD.

molecular biology↗

bioRxiv2020

Mapping the molecular and structural specialization of the skin basement membrane for inter-tissue interactions

Inter-tissue interaction is fundamental to multicellularity. Although the basement membrane (BM) is located at tissue interfaces, its mode of action in inter-tissue interactions remains poorly understood, mainly because the molecular and structural details of the BM at distinct inter-tissue interfaces remain unclear. By combining quantitative transcriptomics and immunohistochemistry, we systematically identify the cellular origin, molecular identity and tissue distribution of extracellular matrix molecules in mouse hair follicles, and reveal that BM composition and architecture are exquisitely specialized for distinct inter-tissue interactions, including epidermal-fibroblast, epidermal-muscle and epidermal-nerve interactions. The epidermal-fibroblast interface, namely, hair germ-dermal papilla interface, makes asymmetrically organized side-specific heterogeneity in BM, defined by the newly characterized interface, hook and mesh BMs. One component of these BMs, laminin 5, is required for the topological and functional integrity of hair germ-dermal papilla interactions. Our study highlights the significance of BM heterogeneity in distinct inter-tissue interactions.

developmental biology↗

bioRxiv2019

Exome sequencing of ion-beam-induced mutants facilitates the detection of candidate genes responsible for phenotypes of mutants in rice

Ion beams are physical mutagens used for plant and microbe breeding that cause mutations via a distinct mechanism from those of chemical mutagens or gamma rays. We utilized whole-exome sequencing of rice DNA in order to understand the properties of ion beam-induced mutations in a genome-wide manner. DNA libraries were constructed from selected carbon-ion-beam-induced rice mutants by capturing with a custom probes covering 66.3 M bases of nearly all exons and miRNAs predicted in the genome. A total of 56 mutations, including 24 single nucleotide variations, 23 deletions, and 5 insertions, were detected in five mutant rice lines (two dwarf and three early-heading-date mutants). The mutations were distributed among all 12 chromosomes, and the average mutation frequency in the M1 generation was estimated to be 2.7 x 10-7 per base. Many single base insertions and deletions were associated with homopolymeric repeats, whereas larger deletions up to seven base pairs were observed at polynucleotide repeats in the DNA sequences of the mutation sites. Of the 56 mutations, six were classified as high-impact mutations that caused a frame shift or loss of exons. A gene that was functionally related to the phenotype of the mutant was disrupted by a high-impact mutation in four of the five lines tested, suggesting that whole-exome sequencing of ion-beam-irradiated mutants could facilitate the detection of candidate genes responsible for the mutant phenotypes.

plant biology↗