Biology subjects

Yoshioka, M.

Publications and source records attributed to Yoshioka, M..

8 recordsLinked to original sources

bioRxiv2026

Alliance formation and complexity of Indo-Pacific bottlenose dolphins (Tursiops aduncus) around Mikura Island, Japan

In this study, we investigate alliance formation and complexity in male Indo-Pacific bottlenose dolphins around Mikura Island using five years of data collected through underwater observations. Focusing on 18 mature males, we examined affiliative behaviors (proximity and rubbing), consortships, and associations. To determine male relationships, we evaluated a simple model (small units) and a complex model (large units). In both models, units were identified by association, and models were evaluated by the extent to which affiliative behaviors and consortship were concentrated within units. All types of behaviors were more concentrated within units determined by the complex model than the simple model, and thus the former was further investigated. The unit sizes determined by the complex model were three, seven, and eight, and variation in association frequency was observed within units. Within units, two to four males engaged in a single consortship irrespective of association frequency. Given that units are mediated by affiliative and cooperative relationships, it is reasonable to interpret units as alliances. Considering the variation in both alliance size and within-alliance relationships, as well as the fact that only a few males cooperate in a single consortship, we suggest that a multi-level structure is plausible in the Mikura community.

zoology↗

bioRxiv2026

In vivo brain temperature measurement using quantum dot imaging temperature sensors

Temperature regulation in the brain is essential for maintaining neuronal function and preventing thermally induced damage. Here, we report the development and in vivo application of quantum dots (QDs) to high-resolution thermometry in the mouse brain using two-photon excitation microscopy. These QDs, via the red-to-green photoluminescence (PL) intensity ratios, enabled stable temperature measurements in both normal and chronically hypo-perfused cerebral tissue. Our findings show that localized neuronal activity leads to transient heat generation, which is rapidly dissipated by cerebrovascular responses. In a chronic hypoperfusion model, impaired vascular function resulted in exaggerated and prolonged brain temperature elevations. This thermometry system provides unprecedented insight into the mechanisms of cerebral thermoregulation and highlights the importance of vascular cooling in protecting the brain from heat-induced stress, particularly in pathological conditions such as stroke.

bioengineering↗

bioRxiv2025

Calcium-dependent protein kinases participate in RBOH-mediated sustained ROS burst during plant immune cell death

The sensing of pathogen effector by an intracellular receptor called nucleotide-binding leucine-rich repeat receptor (NLR), induces a robust immune response, effector-triggered immunity (ETI). Sustained reactive oxygen species (ROS) production is accomplished by Nicotiana benthamiana RBOHB, an NADPH oxidase. However, molecular mechanisms connecting effector recognition and ROS production are unclear. Here, we show that calcium-dependent protein kinases (CDPKs) contribute to sustained ROS production downstream of NLR activation. We found that NbCDPK4 and NbCDPK5 directly phosphorylate NbRBOHB Ser-123 and provokes ROS production. In addition, constitutively active NbCDPKs upregulated NbRBOHB transcription. The phosphorylation of Ser-123 was significantly increased in a Ca2+-dependent manner during the ETI-like responses, which execute hypersensitive cell death. Moreover, transient expression of an autoactive helper NLR, NRC4, induced phosphorylation of Ser-123 dependent on its N-terminal conserved motif required for Ca2+ channel activity. These findings uncover a critical role for the NbCDPK-NbRBOHB module in regulating sustained ROS production during ETI.

plant biology↗

bioRxiv2023

NADPH oxidase-mediated sulfenylation of cysteine derivatives is key regulatory events for plant immune responses

Reactive oxygen species (ROS) are rapidly generated during plant immune responses by RBOH, which is a plasma membrane-localizing NADPH oxidase. Although regulatory mechanisms of RBOH activity have been well documented, the ROS-mediated downstream signaling is unclear. We here demonstrated that ROS sensor proteins play a central role in the ROS signaling via oxidative post-translational modification of cysteine residues, sulfenylation. To detect protein sulfenylation, we used dimedone, which specifically and irreversibly binds to sulfenylated proteins. The sulfenylated proteins were labeled by dimedone in Nicotiana benthamiana leaves, and the conjugates were detected by immunoblotting. In addition, a reductant dissociated H2O2-induced conjugates, suggesting that cysteine persulfide and/or polysulfides are involved in sulfenylation. Sulfenylation of cysteine and its derivatives in ROS sensor proteins were continuously increased during both PTI and ETI in an RBOH-dependent manner. Pharmacological inhibition of ROS sensor proteins by dimedone perturbated cell death, ROS accumulation induced by INF1 and MEK2DD, and defense against fungal pathogens. On the other hand, Rpi-blb2-mediated ETI responses were rather enhanced by dimedone. These results suggest that the sulfenylation of cysteine and its derivatives in various ROS sensor proteins are important events in downstream of RBOH-dependent ROS burst to regulate plant immune responses. HighlightNADPH oxidase-mediated ROS production induces sulfenylation of cysteine residues or their derivatives of ROS sensor proteins, which regulates HR cell death, ROS accumulation, and defense against diverse plant pathogens.

immunology↗

bioRxiv2023

Evolution of wheat blast resistance gene Rmg8 accompanied by differentiation of variants recognizing the powdery mildew fungus

Wheat blast, a devastating disease having spread recently from South America to Asia and Africa, is caused by Pyricularia oryzae pathotype Triticum which emerged in 1985. Rmg8 and Rmg7, genes for resistance to wheat blast found in common wheat and tetraploid wheat, respectively, recognize the same avirulence gene, AVR-Rmg8. Here, we show an evolutionary process in which resistance gene(s), which had obtained an ability to recognize AVR-Rmg8 before the differentiation of Triticum and Aegilops, has expanded its target pathogens. Molecular cloning revealed that Rmg7 was one of alleles of Pm4 (Pm4a), a gene for resistance to wheat powdery mildew on 2AL, whereas Rmg8 was its homoeolog on 2BL ineffective against wheat powdery mildew. Rmg8 variants with the ability to recognize AVR-Rmg8 were distributed not only in Triticum spp. but also in Aegilops speltoides, Ae. umbellulata, and Ae. comosa. This result suggests that the origin of resistance gene(s) recognizing AVR-Rmg8 dates back to the time before differentiation of A, B, S, U, and M genomes, that is, [~]5 million years before the emergence of its current target, the wheat blast fungus. Phylogenetic analyses suggested that, in the evolutionary process thereafter, some of their variants gained the ability to recognize the wheat powdery mildew fungus and evolved into genes for resistance to wheat powdery mildew.

plant biology↗

bioRxiv2023

Breeding of a near-isogenic wheat line resistant to wheat blast at both seedling and heading stages through incorporation of Rmg8

Wheat blast caused by Pyricularia oryzae Triticum pathotype (MoT) has been transmitted from South America to Bangladesh and Zambia and is now spreading in these countries. To prepare against its further spread to Asian countries, we introduced Rmg8, a gene for resistance to wheat blast, into a Japanese elite cultivar, Chikugoizumi (ChI), through recurrent backcrosses, and established ChI near-isogenic lines, #2-1-10 with the Rmg8/Rmg8 genotype and #4-2-10 with the rmg8/rmg8 genotype. A molecular analysis suggested that at least 96.6% of the #2-1-10 genome was derived from the recurrent parent ChI. The #2-1-10 line was resistant to MoT not only in primary leaves at the seedling stage but also in spikes and flag leaves at the heading stage. The strength of the resistance in spikes of this Rmg8 carrier was comparable to that of a carrier of the 2NS segment which has been the only one genetic resource released to farmers field for wheat blast resistance. On the other hand, the 2NS resistance was not expressed on leaves at the seedling stage nor flag leaves at the heading stage. Considering that leaf blast has been increasingly reported and regarded as an important inoculum source for spike blast, Rmg8 expressed at both the seedling and heading stages, or more strictly in both leaves and spikes, is suggested to be useful to prevent the spread of MoT in Asia and Africa.

plant biology↗

bioRxiv2020

Ameliorative effect of a quinazoline-based bromodomain inhibitor, CN210, on experimentally-induced Crohn's disease-like murine ileitis via inhibition of inflammatory cytokine expression

Inhibitors of bromodomain and extra-terminal motif proteins ("BET inhibitors") are emerging epigenetic therapeutics that exert their effects by suppressing the expression of genes that drive cancer and inflammation. The present study examined the anti-inflammatory effects of a quinazoline-based BET inhibitor, CN210, which also inhibits bromodomains of two paralogous histone acetyltransferases (HATs), such as cAMP-responsive element binding protein-binding protein (CBP) and p300. To assess its effectiveness against inflammatory bowel disease (IBD), CN210 was tested in an experimentally-induced murine Crohns disease (CD)-like ileitis model. Ileitis was induced in mice by subcutaneous administration of indomethacin and CN210 was given orally 30 min before and 24 h after the indomethacin administration. Whilst indomethacin produced severe ileitis accompanied by an increase in ileal mucosal myeloperoxidase (MPO) activity, administration of CN210 reduced the severity of ileitis in a dose-dependent manner and suppressed the MPO activity. Similarly, upregulation of inflammatory cytokines was observed in ileitis mucosa after indomethacin injection but this response was significantly attenuated by CN210 administration. To further characterize the effects of CN210 on inflammatory pathways, monocyte/macrophage-like cell line RAW264 treated with lipopolysaccharide (LPS) was exposed to CN210. CN210 significantly attenuated the expression of inflammatory cytokines and reversed the activation of NF-{kappa}B and MAP kinases induced by LPS. These findings suggest that CN210 ameliorates indomethacin-induced ileitis due at least in part to the inhibition of inflammatory cytokine expression via attenuation of NF-{kappa}B and MAP kinase pathways, thus representing a new mode of therapy for CD.

pharmacology and toxicology↗

bioRxiv2017

Robust direct differentiation and maturation of human pluripotent stem cells to hepatocyte-like cells

Liver-on-a-Chip technology holds considerable potential for applications in drug screening and chemical-safety testing. To establish such platforms, functional hepatocytes are required; however, primary hepatocytes are commonly used, despite problems involving donor limitations, lot-to-lot variation, and unsatisfactory two-dimensional culture methods. Although human pluripotent stem cells (hPSCs) may represent a strong alternative contender to address the aforementioned issues, remaining technological challenges include the robust, highly efficient production of high-purity hepatic clusters. In addition, current Liver-on-a-Chip platforms are relatively complicated and not applicable for high-throughput experiments. Here, we develop a very simple Liver-on-a-Chip platform with mature and functional hepatocyte-like cells derived from hPSCs. To establish a method for hepatic differentiation of hPSCs, cells were first treated by inhibiting the phosphoinositide 3-kinase- and Rho-associated protein kinase-signaling pathways to stop self-renewal and improve survival, respectively, which enabled the formation of a well-defined endoderm and facilitated hepatocyte commitment. Next, a simple microfluidic device was used to create a three-dimensional (3D) culture environment that enhanced the maturation and function of hepatocyte-like cells by increasing the expression of both hepatic maturation markers and cytochrome P450. Finally, we confirmed improvements in hepatic functions, such as drug uptake/excretion capabilities, in >90% of 3D-matured hepatocyte-like cells by indocyanin green assay. These results indicated that the incorporation of hPSC-derived hepatocytes on our Liver-on-a-Chip platform may serve to enhance the processes involved in drug screening and chemical-safety testing.

bioengineering↗