Okayama University / 2025-06-02 /eng/research_highlights/index_id245.html Release Subtitle: Photosystem II–FCPII complex found in a marine alga could shape the future of artificial photosynthesis Release Summary Text: Haptophytes—the unicellular photosynthetic marine algae—are one of the major contributors to marine biomass. Scientists at Okayama University, Japan, unveil the first high-resolution structure of the photosystem II–FCPII (photosynthetic supercomplex) in a marine haptophyte, Chrysotila roscoffensis. This discovery sheds light on the unique approach of sunlight capture and energy management by the complex, offering new insights into marine biology and potential advances in artificial photosynthesis technology. Full text of release: Photosynthesis, the natural process of converting sunlight energy into chemical energy and generating molecular oxygen, is a remarkable natural phenomenon that not only forms the basis for sustaining almost all living organisms on Earth but also provides a blueprint for artificial photosynthesis. For decades, researchers have been working on technologies that could replicate this process artificially. Artificial photosynthetic systems use technology to store solar energy in chemical bonds, potentially creating sustainable fuels like hydrogen. A deep understanding of the plant"s light-harvesting structures is vital for such future applications. Uncovering one such structure, a team of researchers led by Assistant Professor Romain La Rocca, along with Associate Professor Fusamichi Akita, and Professor Jian-Ren Shen from Okayama University, Japan, conducted a high-resolution analysis of a photosynthetic complex found in a marine alga, Chrysotila roscoffensis. This marine alga belongs to the coccolithophore species known for producing calcium carbonate plates and fixing carbon at the ocean surface. Published online on May 5, 2025, in Nature Communications, the study describes the unique photosynthetic machinery of the haptophyte species and gives a deeper insight into its unique light-capturing and energy transfer mechanism. Marine algae, especially haptophytes, are vital for marine life, contributing up to 50% of the ocean’s biomass and playing a major role in the global carbon cycle. However, despite their importance, the molecular details of photosynthesis in these species have remained underexplored. The process of photosynthesis mainly involves two protein-pigment complexes, which are photosystem I (PSI) and photosystem II (PSII). PSII is responsible for initiating the process of photosynthesis using light to split water into oxygen, protons, and electrons, while PSI uses the electrons from PSII and excites them to a higher energy level so they can be used in the process of synthesizing sugars. PSII is found in the thylakoid membrane of chloroplasts and is composed of antenna proteins, which are light-harvesting complexes that capture sunlight, and a reaction center called the photosynthetic core (with special chlorophylls (P680) and a water-splitting complex). Using advanced imaging techniques with cryo-electron microscopy (cryo-EM) at an impressive 2.2 Å resolution, the researchers mapped the PSII-fucoxanthin chlorophyll c-binding protein (FCPII) supercomplex in the haplophyte species. “This study analyzed the first structural model of a PSII-FCPII complex in haptophytes,” explains Dr. La Rocca. “Surprisingly, unlike other PSII systems, the complex in the haptophyte shows a unique arrangement of the antenna proteins around the photosystem core.” The structure showed a characteristic arrangement and structure of the antenna proteins, which are made up of six FCPII antenna protein units per monomer of PSII. The arrangement of these proteins was quite different from those seen in diatoms and green algae, indicating the adaptation of this marine alga to its living environment. The FCPII units are responsible for gathering light and transferring energy to the core of the photosystem. According to the cryo-EM structure, one antenna protein, FCPII-2, stands out as a central hub in this process. It is positioned in such a way that it receives energy from its surrounding antennas and passes it directly to the PSII core subunit CP47. The FCPII-2 protein is also rich in fucoxanthin pigments, which can effectively absorb light while dissipating excess light energy, preventing cell damage from strong light. The researchers also identified and sequenced Psb36, a previously uncharacterized PSII subunit that is found at the interface between the core and the antenna system. While this structure has been seen in earlier studies of diatoms and red algae, its sequence wasn’t determined until now. This study reveals significant details to deepen our knowledge of photosynthetic systems and is also expected to contribute to the development of artificial photosynthesis systems, as the unique arrangement of the light-harvesting system indicates the efficiency of light-harvesting under some light conditions. “These algae are extremely efficient at harnessing sunlight for energy; by understanding the structure of their photosystems, we get one step closer to mimicking these natural systems for artificial light energy harvesting,” concludes Dr. Shen. Release URL: https://www.eurekalert.org/news-releases/1085791 Reference: Structure of a photosystem II-FCPII supercomplex from a haptophyte reveals a distinct antenna organization Journal: Nature Communications DOI: 10.1038/s41467-025-59512-9 Contact Person: Romain La Rocca Dr. Romain La Rocca is an Assistant Professor at Okayama University"s Research Institute for Interdisciplinary Science. He holds a PhD in structural biology and specializes in protein crystallography and biophysical techniques. He has five publications to his credit, with over 64 citations. His notable works include studies on tau protein aggregation and microtubule-targeting agents. He is currently working on the structures of photosynthetic protein complexes using protein purification and cryo-electron microscopy techniques. 2025-06-02 /eng/research_highlights/index_id244.html Plants require phosphorus to grow and survive. In environments with low levels of available soil phosphorus, plants need to adjust to stay alive. The pincushion hakea is a large woody, evergreen shrub native to southwestern Australia, an area that has amazingly low levels of soil phosphorus. This plant has adapted to these conditions by forming cluster roots—a large number of smaller rootlets extending from the root axis that resemble a bottlebrush—to extract the small amount of phosphorus in the soil. Cluster roots help plants in low-nutrient soils by increasing the amount of root surface area in contact with the soil, improving their ability to extract limited resources. Additionally, cluster roots secrete chemicals and enzymes to enhance the bioavailability of nutrients, primarily phosphorus, in the soil. Acid phosphatase, for example, is an enzyme secreted by cluster roots that converts organic phosphorus into a form that plants can readily absorb. Improved understanding of these survival mechanisms could ultimately help researchers develop food crops that can thrive in nutrient-deficient soils. While researchers have successfully identified many of the chemicals secreted by cluster roots to improve phosphorus availability, the genes and molecular pathways responsible for cluster-root secretion and uptake in the Proteaceae plant family, including pincushion hakea, had not been identified. In order to better understand how cluster roots function at a molecular level, researchers from Hiroshima University, The University of Western Australia, Okayama University, Hokkaido University, Yamagata University and other institutions collaboratively performed an RNA-Seq experiment on pincushion hakea to identify the genes expressed in its cluster roots. The team published their research on February 24 in the journal New Phytologist. “Our main question was: How does the pincushion hakea, Hakea laurina, survive in its extremely phosphorus-limited environment? Our hypothesis was that Hakea laurina has distinct strategies to maximize the release of root exudates, such as carboxylates and acid phosphatases, from its cluster roots, which are important for enhancing soil phosphorus availability,” said Dr Hirotsuna Yamada, assistant professor (special appointment) at the Graduate School of Integrated Sciences for Life at Hiroshima University and first author of the research paper. The researchers compared the genes expressed in mature cluster roots to those in adjacent lateral roots as a control. This comparison identified 4,210 genes that were expressed at higher levels in cluster roots, providing a large number of prospective genes associated with increased cluster-root secretion and absorption. These included phosphate transporters involved in phosphate uptake into the root and acid phosphatases. Additionally, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated these cluster roots enhanced carboxylate metabolism, which would support an increase in the supply of the carboxylates malate and citrate for secretion into low-phosphorus soils. One of the highly expressed genes in pincushion hakea cluster roots was an aluminum-activated malate transporter (ALMT) protein that the researchers identified as HalALMT1. This HalALMT1 shares 51% of its deduced amino acid sequence with LaALMT1, a Lupinus albus (white lupin) malate transporter that secretes malate into the soil and thus enhances phosphorus availability. Electrophysiological assays and overexpression in Arabidopsis thaliana established that HalALMT1 mediated malate release into the soil. Its activity was further enhanced in the presence of aluminum, which can be toxic to plants in acidic soil. These results suggest that HalALMT1 helps to both mobilize phosphorus and reduce aluminum toxicity to plants through malate secretion. The researchers also found a unique expression pattern of HalALMT1 in cluster roots that further contributes to survival in phosphorus-deficient soil. “Our results show that cortex cells in the cluster rootlets of Hakea laurina are sites of carboxylate and acid phosphatase secretion, potentially facilitating a rapid release of root exudates. The absence of a suberized exodermis, a diffusion barrier, further enhances this trait, offering novel insights into plant adaptations to phosphorus deficiency,” said Dr Jun Wasaki, professor in the Graduate School of Integrated Sciences for Life at Hiroshima University and senior author of the research paper. While the discovery of a new secretion pathway in cluster roots has significantly contributed to the field’s understanding of plant survival mechanisms, additional questions remain. “It is essential to gain a comprehensive understanding of the formation and physiological functions of cluster roots, as well as to identify the key factors that regulate them, to apply the exquisite phosphorus-acquisition strategies of cluster roots to crops. Our research team plans to further advance the understanding of cluster roots with the goal of applying this knowledge to crop improvement,” said Dr Yamada. This paper received funding from Hiroshima University to cover open access fees. About the study Journal:New Phytologist Title: HalALMT1 mediates malate efflux in the cortex of mature cluster rootlets of Hakea laurina,occurring naturally in severely phosphorus-impoverished soil Author: Hirotsuna Yamada, Lydia Ratna Bunthara, Akira Tanaka, Takuro Kohama, Hayato Maruyama,Wakana Tanaka, Sho Nishida, Tantriani, Akira Oikawa, Keitaro Tawaraya, Toshihiro Watanabe, ShuTong Liu, Patrick M. Finnegan, Hans Lambers, Takayuki Sasaki & Jun Wasaki DOI: 10.1111/nph.70010 2025-05-15 /eng/research_highlights/index_id243.html Release Subtitle: Researchers discover a mini-hairpin structured nascent peptide in Escherichia coli that induces translation arrest Release Summary Text: Translation, or the synthesis of proteins, is a complex process orchestrated by the ribosome. However, translation may be stalled by the interaction of the ribosome with ‘ribosome arrest peptides’ (RAPs). While translation arrest helps regulate downstream gene expression, precise mechanisms underlying RAP activity remain poorly understood. Researchers from Japan have now characterized RAPs from Escherichia coli and uncovered a novel mini-hairpin-shaped nascent peptide that induces translation arrest through a unique mechanism. Full text of release: Proteins form the structural and functional backbone of the cell, and any perturbation in their synthesis can disrupt normal cellular functions. The DNA blueprint is carefully read, transcribed, and translated into functional proteins through a tightly regulated process. The ‘ribosome’ plays a crucial role in orchestrating the translation of the messenger RNA transcript by assembling amino acids into the corresponding polypeptide sequence. Ribosomal functions beyond protein synthesis have been uncovered over the years, revealing its role not only in the synthesis of proteins but also in the regulation of the complex process through interactions with several regulatory factors and the nascent (newly synthesized) peptide itself. Translation initiation begins with the ribosome recognizing the initiation site and catalyzing the transfer of amino acids to the growing peptide chain through elongation. However, some nascent peptides interact with the ribosomal tunnel and rearrange the internal structure, resulting in elongation stalling—known as ""translation arrest."" Interestingly, translation arrest in bacterial cells is often triggered by environmental factors such as the presence/absence of specific nutrients and growth factors or inhibitory agents such as antibiotics as a mechanism to regulate the expression of downstream genes. However, ribosome arrest peptides (RAPs), which are encoded by upstream small open reading frames (sORFs) and induce translation arrest, remain largely elusive. To bridge this knowledge gap, Dr. Yuhei Chadani, an Associate Professor at the Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Japan, together with Yushin Ando (a master’s student), Associate Professor Yuzuru Itoh from the University of Tokyo, and Akinao Kobo (a doctoral student) from the Institute of Science Tokyo, sought to identify and characterize RAPs from Escherichia coli (E. coli) and examine the mechanisms underlying translation arrest. Giving further insight into their work published in Volume 16 of Nature Communications on 08 March 2025, Dr. Chadani says, “Understanding the structural diversity of nascent peptides formed in the ribosomal tunnel and their role in translational regulation can aid the elimination of bottlenecks in protein synthesis and the development of biosensors utilizing regulatory nascent peptides.” Overexpression of TnaC, a tryptophan-dependent RAP, is known to impede cell growth and induce cytotoxicity, thus reflecting RAP activity. The researchers screened and analyzed 38 sORFs: 26 annotated and 12 putative sequences. Upon overexpression, 18 sORFs induced growth inhibition. Notably, their cytotoxic effects were not associated with the regulation of downstream genes. In bacterial cells, cold shock proteins (CSPs) are expressed in response to the inhibition of translation elongation induced by environmental and intrinsic stressors. The researchers conducted a comparative proteomic analysis to elucidate the effects of RAP activity and stress response. TnaC and antibiotic-mediated translation arrest are associated with the expression of CSPs. Similarly, overexpression of 12 sORFs was associated with an increased expression of CSPs. Ribosome profiling and analysis of the peptidyl-tRNA intermediates that accumulate due to translation arrest revealed that the arrest peptides ‘PepNL’ and ‘NanCL’ induced translation arrest in E. coli. The researchers further analyzed the structure of the ribosome arrested by the PepNL nascent peptide. Their findings revealed that the PepNL nascent peptide adopts a stable mini-hairpin conformation in the exit tunnel of the ribosome. Normally, on subsequently encountering a stop codon in the transcript, peptide release factors (RF) trigger the dissociation of the peptide chain from the transfer RNA. Structural comparisons between the arrested ribosome and canonical translation termination revealed steric clashes between the nascent peptide and amino acid residues in the ribosomal RNA, leading to a rearrangement in RF2, shifting it to an inactive conformation. Notably, folding of the PepNL nascent peptide within the ribosomal tunnel does not require an arrest inducer, unlike other sensory RAPs like TnaC, and functions by recognizing the stop codon read-through as an arrest cue. Overall, these findings reveal two previously unknown RAPs in E. coli and shed light on novel structural mechanisms underlying their regulatory roles in gene regulation and environmental adaptation. “Our approaches to identifying PepNL and NanCL, as well as the distinct molecular mechanism of translation stalling and regulation, provide valuable insights into deciphering the hidden genetic codes within polypeptide sequences,” Dr. Chadani concludes. Release URL: https://www.eurekalert.org/news-releases/1080810 Reference: Title of original paper: A mini-hairpin shaped nascent peptide blocks translation termination by a distinct mechanism Journal: Nature Communications DOI:10.1038/s41467-025-57659-z Contact Person: Yuhei Chadani Dr. Yuhei Chadani is currently an Associate Professor at the Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Japan. His research focuses on decoding gene regulatory elements in peptide sequences and understanding the mechanisms of gene regulation and translation dynamics, and ribosome stabilization using bacteria and yeast model systems. He is a recipient of several awards from the Genetics Society of Japan and is affiliated with various academic societies and research groups. He has authored several research articles in his research domain. 2025-04-18 /eng/research_highlights/index_id242.html Release Subtitle: Keratinocytes produce collagen fibers, while deeper fibroblasts later modify the collagen fibers initially formed by keratinocytes Release Summary Text: Challenging the long-standing belief that fibroblasts produce skin collagen, researchers at Okayama University have investigated collagen formation in the ‘glass-skinned’ amphibian axolotl and other vertebrates. They discovered that keratinocytes, the surface cells of the skin, are responsible for producing collagen, which is then transferred deeper to form the dermis. Later, fibroblasts migrate into this collagen layer, modifying and reinforcing its structure. Full text of release: The skin consists of two primary layers. The epidermis, the outermost layer, is predominantly made up of keratinocytes, while the deeper dermis contains blood vessels, nerves, and structural proteins such as collagen, which give the skin its strength and texture. Traditionally, fibroblasts—specialized supporting cells within the dermis—have been believed to play a key role in producing collagen. In humans, collagen is formed before and after birth. It has been believed that fibroblasts play an exclusive role in collagen production in the skin, and no keratinocytes contribute to collagen production. The statement “Collagen production in the human skin is achieved by fibroblasts” has been an unspoken agreement in the skin research field. However, in a groundbreaking study published in Volume 16 of Nature Communications on February 24, 2025, scientists from Okayama University, Japan, challenged this long-standing belief. Using the transparent skin of axolotls, an aquatic amphibian widely used in dermatology research, they uncovered a different mechanism for dermal collagen formation. To track collagen development, the researchers examined axolotl skin at different growth stages—5 cm, 8 cm, 10 cm, and 12 cm in length—using advanced fluorescence-based microscopy techniques. At 5 cm, the axolotl’s skin consisted of an epidermis with keratinocytes and a thin, fibroblast-free collagen layer in the dermis, which they named the stratum coniunctum. As the axolotl grew, the collagen layer thickened, and only later did fibroblasts begin migrating into it, eventually forming three distinct dermal layers beneath the epidermis: the stratum baladachinum, stratum spongiosum, and stratum compactum. Each of these layers had a unique collagen structure, none of which matched the original pattern of the stratum coniunctum. Since collagen was already present before fibroblasts start contributing the dermal collagen formation, the team searched for the source of collagen production by a novel collagen labeling technique that can clarify newly synthesized collagen fibers. The results were surprising: strong fluorescent signals were detected in collagen fibers made by keratinocytes, not fibroblasts. “So far, fibroblasts have been thought to be the major contributors to skin collagen. All efforts in cosmetic science and skin medical research have focused on fibroblast regulation. But the present study demands a change in mindset. We clarified that keratinocytes are primarily responsible for dermal collagen formation,” explains Ayaka Ohashi, a Ph.D. student at the Graduate School of Environmental, Life, Natural Science, and Technology at Okayama University. Further investigation revealed that keratinocytes produce collagen in a structured, grid-like arrangement on their undersurface. Later, fibroblasts, which have a lattice-like structure and finger-like projections, migrated into this collagen layer, modifying, and reinforcing it. To confirm that this process is not unique to axolotls, the researchers examined other vertebrate models, including zebrafish, chick embryos, and mammalian (mouse) embryos. Their findings were consistent across all species, suggesting that keratinocyte-driven collagen production is an evolutionarily conserved mechanism. Understanding how collagen forms before birth is crucial for addressing skin aging and developing new treatments for collagen-related conditions. “Axolotls can maintain good skin texture and appearance for a long time. I mean, they have a sort of eternal youth,” says Professor Akira Satoh from Okayama University. “This might be because they continue producing collagen in keratinocytes for a long time. On the other hand, we humans cannot maintain collagen production in keratinocytes after birth. If we can clarify the mechanism that allows axolotls to keep keratinocytes producing collagen throughout their lifetime, we might be able to achieve eternal youth, just like axolotls.” This discovery reshapes our understanding of skin biology and could lead to breakthroughs in regenerative medicine, wound healing, and cosmetic formulations. Current skincare products primarily target fibroblast activity, but future treatments may need to focus on stimulating keratinocyte-driven collagen production instead. By overturning a decades-old belief, this research paves the way for a new era in skincare science—one that could bring us closer to maintaining youthful, resilient skin for a lifetime. Release URL: https://www.eurekalert.org/news-releases/1076487/ Reference: Title of original paper: Keratinocyte-driven dermal collagen formation in the axolotl skin Journal: Nature Communications DOI:10.1038/s41467-025-57055-7 Contact Person:Akira Satoh Dr. Akira Satoh is a faculty of the Graduate School of Environmental, Life, Natural Science, and Technology at Okayama University, Japan. He has a total of 68 publications to his name, with his primary focus being Life Sciences and Developmental Biology. He works on amphibian limb models to understand why humans have lost their ability to regenerate organs. He was conferred ‘The Young Scientists’ Prize – 2015’ by the Minister of Education, Culture, Sports, Science, and Technology, Japan. Contact Person:Ayaka Ohashi Ayaka Ohashi is a Ph.D. student at the Graduate School of Environmental, Life, Natural Science, and Technology at Okayama University, Japan. She works with amphibian animal models, primarily axolotl to gain deeper insights into various aspects of developmental biology, with 9 publications to her credit. Her recent works were focused on skin, muscle, and limb regeneration. 2025-03-13 /eng/research_highlights/index_id241.html Release Subtitle: Researchers discover mitochondrial transfer between cancer cells and immune cells as a key immune evasion strategy Release Summary Text: Immunotherapy, which uses programmed immune cells to selectively destroy cancer cells, has transformed cancer treatment. However, cancer cells have developed immune evasion strategies, leading to poor treatment responses. Now, researchers from Japan have identified the transfer of mitochondria with mutated DNA from cancer cells to immune cells as a key mechanism of immune evasion and resistance to immunotherapy. Targeting this transfer could enhance the effectiveness of cancer immunotherapy. Full text of release: The immune system plays a key role in detecting and destroying cancer cells. Cancer immunotherapy works by programming immune cells to recognize and eliminate cancer cells. However, many cancers can escape immune surveillance through various mechanisms, resulting in resistance to treatment. This highlights the need to better understand the molecular processes that enable immune evasion. The tumor microenvironment (TME)—the space surrounding a tumor—plays a critical role in interactions between cancer and immune cells. Cancer cells can reshape the TME to their advantage, weakening tumor-infiltrating lymphocytes (TILs), the immune cells that attack tumor. Mitochondria, also known as the ‘powerhouse of the cell,’ are small organelles that produce energy for various cellular processes. They play a significant role in the metabolic reprogramming of cancer cells and TILs. However, precise mechanisms underlying mitochondrial dysfunction and its impact on the TME are poorly understood. To address this knowledge gap, a team of researchers led by Professor Yosuke Togashi from Okayama University, Japan, has uncovered novel insights into mitochondrial dysfunction in cancer immune evasion. Working alongside Tatsuya Nishi and Tomofumi Watanabe from Okayama University, as well as Hideki Ikeda, Katsushige Kawase, and Masahito Kawazu from the Chiba Cancer Center Research Institute, the team identified mitochondrial transfer as a key mechanism of immune evasion. This study was published online in Nature on January 22, 2025. Prof. Togashi explains, “We have discovered mitochondrial transfer as one of the key mechanisms of immune evasion. Our research adds a new dimension to the understanding of how tumors resist immune responses, potentially leading to the development of more comprehensive and tailored approaches in treating different cancers.” Mitochondria carry their own DNA (mtDNA), which encodes proteins crucial for energy production and transfer. However, mtDNA is prone to damage, and mutations in mtDNA can promote tumor growth and metastasis. In this study, the researchers examined TILs from patients with cancer and found that they contained the same mtDNA mutations as the cancer cells. Further analysis revealed that these mutations were linked to abnormal mitochondrial structures and dysfunction in TILs. Using a fluorescent marker, the researchers tracked mitochondrial movement between cancer cells and T cells. They found that mitochondria were transferred via direct cell-to-cell connections called tunneling nanotubes, as well as through extracellular vesicles. Once inside T cells, the cancer-derived mitochondria gradually replaced the original T cell mitochondria, leading to a state called ‘homoplasmy,’ where all mtDNA copies in the cell are identical. Normally, damaged mitochondria in TILs are removed through a process called mitophagy. However, mitochondria transferred from cancer cells appeared to resist this degradation. The researchers discovered that mitophagy-inhibiting factors were co-transferred with the mitochondria, preventing their breakdown. As a result, TILs experienced mitochondrial dysfunction, leading to reduced cell division, metabolic changes, increased oxidative stress, and impaired immune response. In mouse models, these dysfunctional TILs also showed resistance to immune checkpoint inhibitors, a type of immunotherapy. By identifying mitochondrial transfer as a novel immune evasion mechanism, this study opens new possibilities for improving cancer treatment. Blocking mitochondrial transfer could enhance immunotherapy response, particularly in patients with treatment-resistant cancers. Cancer therapies often involve high costs and significant side effects, particularly when they are ineffective. Enhancing the success of immunotherapy by inhibiting mitochondrial transfer could reduce the burden of cancer and improve patient outcomes. Prof. Togashi concludes by saying, “Existing cancer treatments are not universally effective, and there is a pressing need for new therapies that can overcome resistance mechanisms. Developing drugs that inhibit mitochondrial transfer between cancer cells and immune cells may enhance the efficacy of immunotherapies, thereby providing personalized treatment options for patients with cancers that are resistant to current therapies.” This discovery offers exciting new insights into cancer biology and could pave the way for more effective therapies in the future. Release URL: https://www.eurekalert.org/news-releases/1073102 Reference: Title of original paper: Immune evasion through mitochondrial transfer in the tumour microenvironment Journal: Nature DOI:10.1038/s41586-024-08439-0 Contact Person:Yosuke Togashi Yosuke Togashi is a Professor at the Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Japan. He completed his MD from Kyoto University and PhD from Kindai University. His research interests include respiratory medicine, lung cancer, cancer Immunology, and tumor biology. He is an esteemed member of several cancer societies and associations. Prof. Togashi is a recipient of various prestigious young investigator awards in cancer biology and immunology. He has authored over 130 research papers in various international peer-reviewed journals. 2025-02-12 /eng/research_highlights/index_id240.html Release Subtitle: Breakthrough discovery of the Shoot-Silicon-Signal protein reveals how an optimal level of silicon enhances plant resilience and productivity Release Summary Text: A breakthrough study reveals that the Shoot-Silicon-Signal (SSS) protein plays a crucial role in managing silicon uptake and distribution in rice and other grasses. This study sheds light on how SSS helps plants adapt to environmental stresses. Understanding the role of silicon could provide valuable information on crop resilience and solutions to enhance agricultural productivity and sustainability, especially in the face of climate change. Full text of release: Silicon (Si) is one of the most abundant elements on Earth, found in large quantities in soil. While Si is not essential for land plants, many plants, such as rice and grasses, have used Si to develop powerful defense mechanisms against various environmental stresses. Si accumulates in plant leaves and aerial organs as amorphous silica (SiO2), which offers protection against pathogens, herbivores, and environmental challenges like drought. Understanding the processes through which plants manage this beneficial element could enhance crop resilience and productivity, especially in the face of climate change. In a breakthrough study, a team of researchers led by Dr. Naoki Yamaji, from the Institute of Plant Science and Resources, Okayama University, Japan, has uncovered a key signaling protein, Shoot-Silicon-Signal (SSS), that regulates Si uptake, distribution, and accumulation in rice and other grasses. Their research focused on Oryza sativa, a rice variety known for its high Si accumulation, and relies heavily on Si for healthy growth and productivity. The team consisted of Dr. Namiki Mitani-Ueno and Dr. Jian Feng Ma from the Institute of Plant Science and Resources, Okayama University, Japan. This study, published online in Volume 15 of Nature Communications on December 27, 2024, sheds light on the evolution of SSS in rice crops as a defense mechanism. Dr. Yamaji says, “We have been studying Si nutrition in plants and have identified several Si transporters for Si uptake, distribution, and accumulation. Now, we have researched the signaling protein.” SSS is an unusually exceptional homolog of florigen, a hormone that regulates flowering in plants. While florigen plays a role in plant development, SSS plays a crucial role in regulating Si. The researchers discovered that when Si is available, the level of SSS protein in the plant drops, signaling the plant to adjust its Si intake accordingly. They used wild-type (naturally occurring) rice variety, modified (mutated) cell lines of the SSS gene, and a transgenic cell line of rice containing genes of SSS protein and green fluorescent protein. The team utilized multiple biotechnological advancements to create mutated and transgenic cell lines. They then performed various analyzes on the expression of the SSS gene and the presence of SSS protein in various parts of the plant. In rice plants with mutated SSS gene, Si uptake from the roots was significantly reduced, causing a drop in the grain yield. This highlights the important role of SSS in regulating Si absorption and accumulation. Also, the scientists found that in leaves, the SSS gene is expressed in the phloem—a tissue that helps in the transportation of food in plants. The findings have exciting implications for agriculture. By using SSS protein as a marker, scientists can better estimate the Si requirements of a plant and consequently optimize Si fertilization. This could result in more resilient crops that are better equipped to cope with environmental stresses, ultimately boosting agricultural productivity and sustainability. Dr. Yamaji emphasizes, “Si accumulation in plants alleviates various biotic and abiotic stresses. Therefore, optimization of Si makes more stress-tolerant crops. It contributes to the productivity and sustainability of agriculture”. Si accumulation and regulation also help the plant to adapt to the environmental conditions. Though Si is not considered an essential element for plant growth, the study proves its indispensable role as an adaptive element. Dr. Yamaji adds about the potential implications of the study, “This discovery opens up new possibilities for improving Si management in crops, particularly in regions where Si availability in soil is lowered by cultivation. By better understanding how plants regulate Si, we can design more efficient fertilization strategies and enhance crop resilience globally.” As climate change continues to threaten agricultural stability, improving Si management could become a key strategy for ensuring a more resilient food supply. Dr. Yamaji concludes, “Si is not just an element that plants accumulate, it’s an adaptive tool that helps them thrive and survive. By harnessing the power of Si, we can help ensure a more sustainable and productive agricultural future.” Release URL: https://www.eurekalert.org/news-releases/1071394 Reference: Title of original paper: Shoot-Silicon-Signal protein to regulate root silicon uptake in rice Journal: Nature Communications DOI:10.1038/s41467-024-55322-7 Contact Person:Naoki Yamaji Dr. Naoki Yamaji is an Associate Professor at the Institute of Plant Science and Resources, Okayama University, Japan. He has published over 200 research papers, 40,000 reads and more than 25,000 citations. He was honored with the Young Scientists’ Prize in 2017, a prestigious national recognition. His research primarily focuses on plant physiology, rice, plant biotechnology, plant environmental stress physiology, and plant molecular biology. Additionally, Dr. Yamaji’s work delves into plant molecular biology, aiming to enhance crop resilience and productivity through a deeper understanding of plant responses to environmental challenges. 2025-01-27 /eng/research_highlights/index_id239.html Release Subtitle: Scientists map the circadian rhythm-regulating neurons and elucidate their roles in regulating behaviors in Drosophila Release Summary Text: Scientists from Okayama University, Julius-Maximilians-University of Würzburg, and University of Nevada Reno have constructed a comprehensive map of synaptic connection for the circadian clock in Drosophila melanogaster. The study identified 250 neurons, including novel subtypes, and revealed the expression of novel neuropeptides. These findings emphasize how these circadian clock neurons regulate the feeding and reproductive behaviors in Drosophila via peptidergic signaling. The research also highlights the importance of contralateral synaptic connectivity in maintaining circadian rhythm. Full text of release: The circadian clock, an internal timekeeping system, enables organisms to respond to rhythmic environmental changes occurring over 24 hours. The master circadian clock located in the brain regulates several peripheral clocks in different tissues through endocrine and systemic signaling. These neurons, along with neurotransmitters, neuropeptides, and gap junctions, form a neuronal network. The circadian clock neural network is highly conserved across species, making the fruit fly Drosophila melanogaster an ideal model for circadian clock studies. A collaborative study led by Professor Taishi Yoshii from Okayama University, Nils Reinhard and Charlotte Helfrich-Förster from the University of Würzburg, and Meet Zandawala from the University of Nevada Reno has made a breakthrough in understanding the regulation of rhythmic physiology through the circadian clock. The team has constructed a comprehensive map of the synaptic connectome of clock neurons in Drosophila. The study was published online on December 05, 2024, in the Journal Nature Communications. Prof. Yoshii said, “The connectome developed in this study revealed the importance of clock neurons in regulating the feeding and mating behaviors of Drosophila.” Using the FlyWire connectome, the researchers identified 242 clock neurons based on morphology, known connectivity, and location of their soma. Prof. Yoshii said, “The number of clock neurons identified in this study is higher than the previously reported 150 neurons, indicating the presence of novel neurons.” The study also identified new neuron subtypes, including dorsal neurons (DN3 and DN1p), and connections among different subgroups across both brain hemispheres. Particularly, DN1pA was identified as an important center linking the clock networks across the two brain hemispheres as it formed both ipsilateral and contralateral connections. This extensive contralateral synaptic connectivity indicates that the neurons on the opposite sides of the brain are connected. The study revealed that light input pathways influence clock neurons. Photoreceptor cells of the compound eyes, Hofbauer-Buchner eyelets, and ocelli provided indirect inputs to the clock neurons, indicating a new layer of complexity in how light stimulus plays an important role in the functioning of the circadian neurons. Furthermore, the study suggests that the output of the clock network neurons was directed toward the intrinsic brain neurons, especially central brain neurons. The clock network utilized descending neurons, such as Allostatin-C and SIFamine (SIFa) peptidergic neurons, which are involved in regulating feeding, mating, and sleep behaviors. Neurotransmitter analysis showed that most of the lateral clock neurons expressed the excitatory neurotransmitter acetylcholine, whereas most of the dorsal clock neurons expressed glutamate. In remarks on this, Prof. Yoshii explained, “The inhibitory neurotransmitter GABA was absent in clock neurons. Glutamatergic (small-central projecting DN3) and cholinergic clock neurons were involved in synaptic outputs to neurons that regulate hunger, thirst, and mating behaviors.” Additionally, the study identified 12 neuropeptides that were upregulated in the clock network. Among these neuropeptides, DH44 and Proctolin were the novel neuropeptides identified in this study. This suggests that clock neurons communicate through peptidergic paracrine signaling. These findings significantly improved our understanding of the connectivity and functioning of clock neurons and have potential implications for the development of therapeutic strategies for circadian disorders, such as sleep and mood disorders in humans. Release URL: https://www.eurekalert.org/news-releases/1070701 Reference: Title of original paper: Synaptic connectome of the Drosophila circadian clock Journal: Nature Communications DOI:10.1038/s41467-024-54694-0 Contact Person:Taishi Yoshii Dr. Taishi Yoshii has been a Professor at the Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, Japan, since April 2022. He completed his PhD from Okayama University in 2006 and his Master’s degree from Yamaguchi University, Yamaguchi, Japan, in 2003. He was awarded the Excellent Poster Award at the 19th Academic Conference of the Japanese Chronobiology Society. He has published his research in various peer-reviewed journals, such as the Journal of Biological Rhythms, Cell Reports, and Biochemical and Biophysical Research Communications. His research interests are chronobiology, circadian rhythms, and Drosophila melanogaster. 2025-01-17 /eng/research_highlights/index_id238.html ◆Key pointsTo observe the state of the universe before the hot Big Bang, it is necessary to observe the polarization of the afterglow of the Big Bang across the entire sky with an accuracy that is an order of magnitude higher than the past experiments.In this study, we developed a high-speed simulator Falcons and, for the first time in the world, explored observation parameters in a multi-dimensional space to find an observation method that minimizes polarization measurement systematic errors.These research results provide important design guidelines for future space missions aimed at probing the state of the universe immediately after its birth.An international collaborative research group including Yusuke Takase, a third-year Ph.D. student at the Graduate School of Natural Science and Technology, Okayama University (JSPS Research Fellow), Prof. Hirokazu Ishino of the Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Dr. Léo Vacher of the International School for Advanced Studies (SISSA) in Italy, Dr. Guillaume Patanchon (ILANCE, CNRS, Université Paris Cité, University of Tokyo), and Dr. Ludovic Montier (France, IRAP), has discovered a method to minimize systematic errors in satellite observation methods to explore the mysteries of the universe"s creation. The hot Big Bang of the universe is thought to have been caused by a rapid expansion of space, called inflation, that occurred in an extremely short time before it. To find evidence of this, it is necessary to measure the polarization of the cosmic microwave background, the afterglow of the Big Bang, with an accuracy that is an order of magnitude higher than conventional methods. To suppress errors due to uncertainties in instrument performance, it is necessary to optimize the observing parameters in a multi-dimensional space. This time, we developed a high-speed simulator (Falcons) and succeeded in finding the optimal solution for the first time. These results provide important design guidelines for future precise polarization observations, including the LiteBIRD space telescope project led by the Japan Aerospace Exploration Agency (JAXA). The results were published on Dec. 12 in the Italian ""Journal of Cosmology and Astroparticle Physics"".◆Comments from researcher It has been about five years since I immersed myself in the field of cosmology, which has interested me since childhood. I never imagined that I would be responsible for optimizing observation methods for the next generation of cutting-edge satellites, starting from nothing. LiteBIRD is a huge project involving about 400 researchers from Japan and abroad. The experience of developing software while struggling with fellow students from France and Italy is a fond memory. I look forward to the moment when LiteBIRD unravels the mysteries of the birth of the universe with the observation methods we have proposed.Yusuke Takase ■Paper Information Title：Multi-dimensional optimisation of the scanning strategy for the LiteBIRD space mission Journal：Journal of Cosmology and Astroparticle Physics Authors：Yusuke Takase, Léo Vacher, Hirokazu Ishino, Guillaume Patanchon, Ludovic Montier, other LiteBIRD collaborationLiteBIRD collaboration D O I：10.1088/1475-7516/2024/12/036 U R L：https://iopscience.iop.org/article/10.1088/1475-7516/2024/12/036 ■Research Funding This research was supported by the Grant-in-Aid for JSPS Fellows (JP23KJ1602). Additionally, this research was supported by Okayama University RECTOR and the JSPS Core-to-Core Program. We used KEKCC in the Inter-University Research Institute Corporation High Energy Accelerator Research Organization (KEK) as a computational resource. The Open Access version of this paper is supported by the “APC Support for High-Impact International Journals,” an initiative of the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT) under the Open Access Acceleration Project. ＜Contact＞ Faculty of Environmental, Life, Natural Science and Technology Professor ISHINO Hirokazu （TEL）086-251-7818 （FAX）086-251-7830 2025-01-07 /eng/research_highlights/index_id237.html Release Subtitle: The developed nanodiamonds with nitrogen-vacancy centers exhibit strong fluorescence and high-quality spin properties for biological applications Release Summary Text: Researchers have developed nanodiamond sensors with nitrogen-vacancy (NV) centers, offering exceptional brightness and spin properties for quantum sensing and bioimaging. These nanodiamonds outperform commercial options, requiring 20 times less energy and maintaining quantum states 11 times longer. Enhanced sensitivity to magnetic fields and temperature enables precise applications, including disease detection, battery analysis, and thermal management of electronics, marking a significant advancement in nanotechnology-driven quantum sensing for biological and industrial innovations. Full text of release: Quantum sensing is a rapidly developing field that utilizes the quantum states of particles, such as superposition, entanglement, and spin states, to detect changes in physical, chemical, or biological systems. A promising type of quantum nanosensor is nanodiamonds (NDs) equipped with nitrogen-vacancy (NV) centers. These centers are created by replacing a carbon atom with nitrogen near a lattice vacancy in a diamond structure. When excited by light, the NV centers emit photons that maintain stable spin information and are sensitive to external influences like magnetic fields, electric fields, and temperature. Changes in these spin states can be detected using optically detected magnetic resonance (ODMR), which measures fluorescence changes under microwave radiation. NDs with NV centers are biocompatible and can be designed to interact with specific biological molecules, making them valuable tools for biological sensing. However, NDs used for bioimaging generally exhibit lower spin quality compared to bulk diamonds, resulting in reduced sensitivity and accuracy in measurements. In a recent breakthrough, scientists from Okayama University in Japan developed nanodiamond sensors bright enough for bioimaging, with spin properties comparable to those of bulk diamonds. The study, published in ACS Nano, on 16 December 2024, was led by Research Professor Masazumi Fujiwara from Okayama University, in collaboration with Sumitomo Electric Company and the National Institutes for Quantum Science and Technology. “This is the first demonstration of quantum-grade NDs with exceptionally high-quality spins, a long-awaited breakthrough in the field. These NDs possess properties that have been highly sought after for quantum biosensing and other advanced applications,” says Prof. Fujiwara. Current ND sensors for bioimaging face two main limitations: high concentrations of spin impurities, which disrupt NV spin states, and surface spin noise, which destabilizes the spin states more rapidly. To overcome these challenges, the researchers focused on producing high-quality diamonds with very few impurities. They grew single-crystal diamonds enriched with 99.99% 12C carbon atoms and then introduced a controlled amount of nitrogen (30–60 parts per million) to create an NV center with about 1 part per million. The diamonds were crushed into NDs and suspended in water. The resulting NDs had a mean size of 277 nanometers and contained 0.6–1.3 parts per million of negatively charged NV centers. They displayed strong fluorescence, achieving a photon count rate of 1500 kHz, making them suitable for bioimaging applications. These NDs also showed enhanced spin properties compared to commercially available larger NDs. They required 10–20 times less microwave power to achieve a 3% ODMR contrast, had reduced peak splitting, and demonstrated significantly longer spin relaxation times (T1 = 0.68 ms, T2 = 3.2 µs), which were 6 to 11 times longer than those of type-Ib NDs. These improvements indicate that the NDs possess stable quantum states, which can be accurately detected and measured with low microwave radiation, minimizing the risk of microwave-induced toxicity in cells. To evaluate their potential for biological sensing, the researchers introduced NDs into HeLa cells and measured the spin properties using ODMR experiments. The NDs were bright enough for clear visibility and produced narrow, reliable spectra despite some impact from Brownian motion (random ND movement within cells). Furthermore, the NDs were capable of detecting small temperature changes. At temperatures around 300 K and 308 K, the NDs exhibited distinct oscillation frequencies, demonstrating a temperature sensitivity of 0.28 K/√Hz, superior to bare type-Ib NDs. With these advanced sensing capabilities, the sensor has potential for diverse applications, from biological sensing of cells for early disease detection to monitoring battery health and enhancing thermal management and performance for energy-efficient electronic devices. “These advancements have the potential to transform healthcare, technology, and environmental management, improving quality of life and providing sustainable solutions for future challenges,” says Prof. Fujiwara. Release URL: https://www.eurekalert.org/news-releases/1068901 Reference: Title of original paper: Bright quantum-grade fluorescent nanodiamonds Journal: ACS Nano DOI:10.1021/acsnano.4c03424 Contact Person:Masazumi Fujiwara Dr. Masazumi Fujiwara is a Research Professor in the Department of Chemistry at the Graduate School of Life, Environmental, Natural Science, and Technology, Okayama University, Japan. With a background in physics (PhD from Osaka City University and postdocs at Hokkido University and the Humboldt University of Berlin), he leads the Nanochemistry Laboratory, focusing on the development of nanomaterials, their applications in biological studies and quantum nanophotonics. Prof. Fujiwara has received multiple awards, including the 2015 Masao-Horiba Award, the 2020 Osaka City University Nambu Yoichiro Award, and the 2016 MEXT Fellowship for Excellent Young Researchers. His team has been actively engaged in international collaborative research, with a particular focus on projects such as the JST-ASPIRE program (JPMJAP2339). Website: https://www.nanochem-okayama-u.net/ Linkedin: https://www.linkedin.com/in/masazumi-fujiwara-779548194/ 2024-12-24 /eng/research_highlights/index_id236.html Release Subtitle: Researchers explore the pathogenic role of a surface protein expressed on Streptococcus mutans—a caries-causing pathogen—in IgA nephropathy Release Summary Text: IgA nephropathy (IgAN) is an immune response disease affecting the filtering units of the kidneys. It is an intractable disease with a complex physiological process. Streptococcus mutans, a dental caries-causing bacterial pathogen, has been linked to IgAN disease progression. Now, researchers from the Okayama University, Japan, have uncovered a virulent role of Cnm—a surface collagen-binding protein expressed on S. mutans in IgAN development, highlighting a potential link between dental caries and renal lesions. Full text of release: The kidneys act as a filtering system in the human body that help in the removal of excess fluids and unwanted wastes from the bloodstream. Inflammation of “glomeruli” or the tiny filtering units within the kidneys, also known as “glomerulonephritis,” results in the alteration to the functioning of kidneys. IgA nephropathy (IgAN) is the most common type of primary glomerulonephritis with deposition of the antibody—immunoglobulin A (IgA) in the glomerular region. The underlying disease progression is complex and multifactorial, and 30–40% of patients develop terminal kidney failure. Given the intractable nature of the disease, there is a need to understand specific pathological mechanisms contributing to IgAN, and develop targeted treatments. Tonsillitis (inflammation or immune response of the tonsils) and bacteria related to dental caries and periodontal disease have been implicated in IgAN pathogenesis. This is likely due to the entry of the pathogen into circulation during invasive dental procedures. Streptococcus mutans is one such bacterial caries-causing pathogen, known to cause bacterial sepsis (extreme response of immune system to an infection leading to death) and infective endocarditis (inflammation of the inner lining of the heart). Moreover, S. mutans expressing a surface collagen-binding protein (Cnm) has been found more frequently in patients with IgAN than in healthy individuals. The precise role in IgAN development is, however, unclear. A research team led by Dr. Shuhei Naka, including co-first author, Professor Michiyo Matsumoto-Nakano from Department of Pediatric Dentistry, Okayama University, Professor Kazuhiko Nakano from the Department of Pediatric Dentistry, Osaka University, Dr. Taro Misaki from the Seirei Hamamatsu General Hospital, and Assistant Professor Daiki Matsuoka from the Department of Pediatric Dentistry, Okayama University, Japan, were involved in this study. The team of researchers sought to uncover the potential virulent role of Cnm from S. mutans in the progression of IgAN disease. “Until now, oral pathogens and kidney disease have been studied independently. We have been able to obtain useful research results over 10 years by establishing a collaboration between clinicians and researchers in oral pathogens and kidney diseases,” says Dr. Naka as a personal motivation behind the study. The team has previously shown that injection of a Cnm-expressing S. mutans strain in rats induces the formation of IgA-like renal lesions following intensive caries and simulation of invasive dental procedures. The potential link between the oral pathogen and renal lesions prompted the researchers to assess the role of the Cnm protein itself. Explaining the rationale behind their current work published in Communications Biology, on 14 September, 2024, Dr. Naka, the corresponding author of the article, says, “Collagen-binding protein, one of the proteins present on the surface of dental caries, may be associated with the development of IgA nephropathy. Future development of research through medical-dental collaborations may lead to the development of a fundamental treatment for IgA nephropathy.” They injected a Cnm-positive strain of S. mutans isolated from the oral cavity of a patient with severe IgAN, a Cnm-deficient strain, a complementation strain (with a similar genetic makeup as Cnm positive), and recombinant Cnm protein ([rCnm], a genetically modified variant), intravenously in rats. Next, they went on to assess the clinical features of IgAN, namely proteinuria (presence of protein in urine), hematuria (presence of blood in urine), and renal function in the animals. Notably, while there was no change in proteinuria and renal function across the experimental animals, hematuria was significantly higher in the Cnm-positive, Cnm complementation groups, and rCnm groups, compared to the negative controls. This finding suggests that Cnm protein or Cnm-expressing S. mutans may induce hematuria in the early stages of IgAN. Next, the researchers evaluated stained tissue sections of kidneys isolated from the treated animals. Mesangial cell and matrix proliferation (types of cells in the kidney tissue which are altered in IgAN present in the supporting medium known as mesangial matrix) were significantly higher in the Cnm-positive and rCnm groups compared to Cnm-negative groups. Furthermore, tissue sections obtained from Cnm-positive rats showed higher deposition of IgA, complement C3, and IgG (a prominent feature of IgAN) in the mesangial region of the glomerulus. The researchers also noted the presence of Cnm protein in the mesangial region —another hallmark feature of IgAN—in animals injected with rCnm. Given that both Cnm-expressing S. mutans and rCnm induce IgA-like nephropathy, the Cnm protein by itself may have a pathogenic role in the development of IgAN. The researchers also highlight that the amount of Cnm protein present in one milligram of dental plaque is equivalent to the amount injected in the rat model. Therefore, invasive dental procedures which allow the entry of Cnm-expressing S. mutans can trigger IgAN-like nephropathy. Furthermore, Cnm deposition may independently, or in combination with IgA and/or IgG, contribute to the development of an IgAN. Talking to us about the long-term implications of these findings, Dr. Naka says “Our findings suggest that the kidneys’ condition may be improved by reducing carious bacteria through a preventive dental approach in patients with IgAN. We intend to further advance this project and obtain results that can be delivered to clinical settings.” Release URL: 2024-12-03