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Abstract JEM-EUSO is an international program for the development of space-based Ultra-High Energy Cosmic Ray observatories. The program consists of a series of missions which are either under development or in the data analysis phase. All instruments are based on a wide-field-of-view telescope, which operates in the near-UV range, designed to detect the fluorescence light emitted by extensive air showers in the atmosphere. We describe the simulation software ESAF in the framework of the JEM-EUSO program and explain the physical assumptions used. We present here the implementation of the JEM-EUSO, POEMMA, K-EUSO, TUS, Mini-EUSO, EUSO-SPB1 and EUSO-TA configurations in ESAF. For the first time ESAF simulation outputs are compared with experimental data.

The fusion reaction involving proton (p) and boron (11B) has unique advantages over deuterium-tritium (DT) fusion in terms of number of neutrons generated and availability of the fuel components. Here the authors demonstrate the (p,11B) fusion reaction in a magnetically confined plasma at the Large Helical Device.

Recently, experiments on basic plasma physics issues for solving future problems in fusion energy have been performed on a Large Helical Device. There are several problems to be solved in future devices for fusion energy. Emerging issues in burning plasma are: alpha-channeling (ion heating by alpha particles), turbulence and transport in electron dominant heating helium ash exhaust, reduction of the divertor heat load. To solve these problems, understanding the basic plasma physics of (1) wave–particle interaction through (inverse) Landau damping, (2) characteristics of electron-scale (high- k ) turbulence, (3) ion mixing and the isotope effect, and (4) turbulence spreading and detachment, is necessary. This overview discusses the experimental studies on these issues and turbulent transport in multi-ion plasma and other issues in the appendix.

TAE Technologies’ fifth-generation fusion device, C-2W (also called ‘Norman’), is the world’s largest compact-toroid device and has made significant progress in field-reversed configuration (FRC) plasma performance. C-2W produces record breaking, macroscopically stable, high-temperature advanced beam-driven FRC plasmas, dominated by injected fast particles and sustained in steady state, which is primarily limited by neutral-beam (NB) pulse duration. The NB power supply system has recently been upgraded to extend the pulse length from 30 ms to 40 ms, which allows for a longer plasma lifetime and thus better characterization and further enhancement of FRC performance. An active plasma control system is routinely used in C-2W to produce consistent FRC performance as well as for reliable machine operations using magnet coils, edge-biasing electrodes, gas injection and tunable-energy NBs. Google’s machine learning framework for experimental optimization has also been routinely used to enhance plasma performance. Dedicated plasma optimization experimental campaigns, particularly focused on the external magnetic field profile and NB injection (NBI) optimizations, have produced a superior FRC plasma performance; for instance, achieving a total plasma energy of ∼13 kJ, a trapped poloidal magnetic flux of ∼16 mWb (based on the rigid-rotor model) and plasma sustainment in steady state up to ∼40 ms. Furthermore, under some operating conditions, the electron temperature of FRC plasmas at a quiescent phase has successfully reached up to ∼1 keV at the peak inside the FRC separatrix for the first time. The overall FRC performance is well correlated with the NB and edge-biasing systems, where higher total plasma energy is obtained with higher NBI power and applied voltage on biasing electrodes. C-2W operations have now reached a mature level where the machine can produce hot, stable, long-lived, and repeatable plasmas in a well-controlled manner.

This study successfully developed a refueling technique for a field-reversed configuration (FRC) via axial plasmoid injection and demonstrated it on the FAT-CM device at Nihon University. The target FRC is generated using the collisional-merging formation technique combined with conical theta-pinch formation. Plasmoids with an FRC-like configuration are coaxially injected from both ends of the FAT-CM device toward the preexisting target FRC. Postinjection, the system achieves equilibrium, resulting in increases by factors of 1.8 and 2.4 in the total inventory and plasma energy, respectively, compared to cases without injection. This method effectively accomplishes FRC refueling while preserving the intrinsic characteristics of a simply connected, axisymmetric configuration and a high beta value approaching unity. Therefore, this approach offers potential for repetitive refueling in the reactor stage having a FRC plasma core. Experimental outcomes are compared with magnetohydrodynamic simulation results. In the collisional merging process, the characteristics of the pre-collision plasmoids, such as the strong toroidal rotation and coherent FRC-like magnetic field structures of the FRC, are not preserved. Experimental environments have been constructed to investigate such unique properties of the resulting FRCs.

Aneutronic fusion using commonly available fuel such as hydrogen and boron 11 ( ^11 B) is one of the most attractive potential energy sources. On the other hand, it requires 30 times higher temperature than deuterium–tritium fusion in a thermonuclear fusion reactor condition. Development of techniques to realize its potential for the experimental capability to produce proton-boron 11 (p- ^11 B) fusion in the magnetically confined fusion device using neutral beam injection is desired. Here we report clear experimental exploration and measurements of p- ^11 B fusion reactions supported by intense hydrogen beams and impurity powder dropper installed in the magnetic confinement plasma Large Helical Device. We measured a significant amount of fusion alpha particle emission using a custom designed alpha particle detector based on a passivated implanted planar silicon detector. Intense negative-ion-based hydrogen beam injectors created a large population of up to 160 keV energetic protons to react with the boron-injected plasma. The p- ^11 B alpha particles having MeV energy were measured with the alpha particle detector which gave a fusion rate in a good agreement with the global p- ^11 B alpha emission rate calculated based on classical confinement of energetic proton, using experimentally obtained plasma parameters.

A novel method of measuring an electron beam’s energy spectrum and divergence using Compton-scattered x rays created by colliding a laser with an electron beam has been developed and tested using the compact laser-Compton x-ray source at LLNL. The method only requires an x-ray imaging device and a filter material whose K-edge energy matches that of the Compton-scattered x rays. K-edge filtering of energy-angle correlated Compton x rays causes large variations in intensity over the viewing angle. These intensity variations contain information about the electron beam’s properties. By using simulation tools and adjusting the beam parameters to match the shape of the acquired image, the electron beam can be characterized. As a demonstration of this technique, a 75-μm Sn foil was used to filter 30-keV Compton x rays created from Compton scattering of a 532-μm laser beam by a 30-MeV electron beam. The measured parameters were mean energy E=28.51±0.06 MeV, energy spread σ_{E}

We present the laboratory results of immersion freezing efficiencies of cellulose particles at supercooled temperature (T) conditions. Three types of chemically homogeneous cellulose samples are used as surrogates that represent supermicron and submicron ice-nucleating plant structural polymers. These samples include microcrystalline cellulose (MCC), fibrous cellulose (FC) and nanocrystalline cellulose (NCC). Our immersion freezing dataset includes data from various ice nucleation measurement techniques available at 17 different institutions, including nine dry dispersion and 11 aqueous suspension techniques. With a total of 20 methods, we performed systematic accuracy and precision analysis of measurements from all 20 measurement techniques by evaluating T-binned (1 ∘C) data over a wide T range (−36 ∘C 

The ferromagnetic state of the spin-polarized ferromagnet La1−xSrxMnO3 is stabilized in the metallic region by strong coupling between localized spins in the t2g orbital and conduction electrons in the eg orbital. We prepared polycrystalline La1−xSrxMnO3 films (x = 0.15, 0.25, or 0.30) by deposition on an oxidized Si substrate. The three types of La1−xSrxMnO3 films were in the ferromagnetic rhombohedral phase, and their Curie temperatures, TC, evaluated from the midpoint of ac magnetization, were 305 K, 335 K, and 338 K, respectively. By applying expansion-mode acoustic vibration to the crystal structure of La1−xSrxMnO3, we observed a remarkable decrease (as large as 70 K) in TC. The applied structural perturbation causes a decrease in the possibility of conduction electron hopping and an increase in the Jahn–Teller distortion. The former is more effective for decreasing TC than the latter.

The westerly wind travelling at high altitudes over eastern Asia transports aerosols from the Asian deserts and urban areas to downwind areas such as Japan. These long-range-transported aerosols include not only mineral particles but also microbial particles (bioaerosols), that impact the ice-cloud formation processes as ice nuclei. However, the detailed relations of airborne bacterial dynamics to ice nucleation in high-elevation aerosols have not been investigated. Here, we used the aerosol particles captured in the snow cover at altitudes of 2450 m on Mt Tateyama to investigate sequential changes in the ice-nucleation activities and bacterial communities in aerosols and elucidate the relationships between the two processes. After stratification of the snow layers formed on the walls of a snow pit on Mt Tateyama, snow samples, including aerosol particles, were collected from 70 layers at the lower (winter accumulation) and upper (spring accumulation) parts of the snow wall. The aerosols recorded in the lower parts mainly came from Siberia (Russia), northern Asia and the Sea of Japan, whereas those in the upper parts showed an increase in Asian dust particles originating from the desert regions and industrial coasts of Asia. The snow samples exhibited high levels of ice nucleation corresponding to the increase in Asian dust particles. Amplicon sequencing analysis using 16S rRNA genes revealed that the bacterial communities in the snow samples predominately included plant associated and marine bacteria (phyla Proteobacteria) during winter, whereas during spring, when dust events arrived frequently, the majority were terrestrial bacteria of phyla Actinobacteria and Firmicutes. The relative abundances of Firmicutes (Bacilli) showed a significant positive relationship with the ice nucleation in snow samples. Presumably, Asian dust events change the airborne bacterial communities over Mt Tateyama and carry terrestrial bacterial populations, which possibly induce ice-nucleation activities, thereby indirectly impacting climate change.

The collective interaction between intense ion beams and plasmas is studied by simulations and experiments, where an intense proton beam produced by a short pulse laser is injected into a pre-ionized gas. It is found that, depending on its current density, collective effects can significantly alter the propagated ion beam and the stopping power. The quantitative agreement that is found between theories and experiments constitutes the first validation of the collective interaction theory. The effects in the interaction between intense ion beams and background gas plasmas are of importance for the design of laser fusion reactors as well as for beam physics.

Magnetic fusion reactors with higher ratio of plasma kinetic pressure to magnetic pressure are economically desirable. The authors demonstrate a path to such a reactor in a field reversed configuration that can attain microstability and reduced particle and thermal fluxes by manipulating the shear flow.

In order to implement radiotherapy based on a laser accelerator, it is necessary to precisely control the spatial distribution and energy spectrum of the proton beams to meet the requirements of the radiation dose distribution in the three-dimensional biological target. A compact laser plasma accelerator has been built at Peking University, which can reliably generate and transport MeV-energy protons with a specified energy onto the irradiation platform. In this paper, we discuss several technologies for the accurate control of a laser-accelerated proton beam with large divergence angle and broad energy spread, including the determination of the beam source position with micron accuracy, a tuning algorithm for the transport line which we refer to as “matching-image-point two-dimensional energy analysis” to realize accurate energy selection, and the control of beam distribution uniformity. In the prototype experiment with low energy protons and 0.5-Hz irradiation rate, a tailored energy deposition is demonstrated, which shows the potential feasibility of future irradiation based on laser-accelerated proton beams.

Immersion freezing is the most relevant heterogeneous ice nucleation mechanism through which ice crystals are formed in mixed-phase clouds. In recent years, an increasing number of laboratory experiments utilizing a variety of instruments have examined immersion freezing activity of atmospherically relevant ice-nucleating particles. However, an intercomparison of these laboratory results is a difficult task because investigators have used different ice nucleation (IN) measurement methods to produce these results. A remaining challenge is to explore the sensitivity and accuracy of these techniques and to understand how the IN results are potentially influenced or biased by experimental parameters associated with these techniques. Within the framework of INUIT (Ice Nuclei Research Unit), we distributed an illite-rich sample (illite NX) as a representative surrogate for atmospheric mineral dust particles to investigators to perform immersion freezing experiments using different IN measurement methods and to obtain IN data as a function of particle concentration, temperature (T), cooling rate and nucleation time. A total of 17 measurement methods were involved in the data intercomparison. Experiments with seven instruments started with the test sample pre-suspended in water before cooling, while 10 other instruments employed water vapor condensation onto dry-dispersed particles followed by immersion freezing. The resulting comprehensive immersion freezing data set was evaluated using the ice nucleation active surface-site density, ns, to develop a representative ns(T) spectrum that spans a wide temperature range (−37 °C < T < −11 °C) and covers 9 orders of magnitude in ns. In general, the 17 immersion freezing measurement techniques deviate, within a range of about 8 °C in terms of temperature, by 3 orders of magnitude with respect to ns. In addition, we show evidence that the immersion freezing efficiency expressed in ns of illite NX particles is relatively independent of droplet size, particle mass in suspension, particle size and cooling rate during freezing. A strong temperature dependence and weak time and size dependence of the immersion freezing efficiency of illite-rich clay mineral particles enabled the ns parameterization solely as a function of temperature. We also characterized the ns(T) spectra and identified a section with a steep slope between −20 and −27 °C, where a large fraction of active sites of our test dust may trigger immersion freezing. This slope was followed by a region with a gentler slope at temperatures below −27 °C. While the agreement between different instruments was reasonable below ~ −27 °C, there seemed to be a different trend in the temperature-dependent ice nucleation activity from the suspension and dry-dispersed particle measurements for this mineral dust, in particular at higher temperatures. For instance, the ice nucleation activity expressed in ns was smaller for the average of the wet suspended samples and higher for the average of the dry-dispersed aerosol samples between about −27 and −18 °C. Only instruments making measurements with wet suspended samples were able to measure ice nucleation above −18 °C. A possible explanation for the deviation between −27 and −18 °C is discussed. Multiple exponential distribution fits in both linear and log space for both specific surface area-based ns(T) and geometric surface area-based ns(T) are provided. These new fits, constrained by using identical reference samples, will help to compare IN measurement methods that are not included in the present study and IN data from future IN instruments.

A compact laser plasma accelerator (CLAPA) that can stably produce and transport proton ions with different energies less than 10 MeV,

In the extreme high intensity regime of electromagnetic (EM) waves in plasma, the acceleration process is found to be dominated by the ponderomotive acceleration (PA). While the wakefields driven by the ponderomotive force of the relativistic intensity EM waves are important, they may be overtaken by the PA itself in the extreme high intensity regime when the dimensionless vector potential a_{0} of the EM waves far exceeds unity. The energy gain by this regime (in 1D) is shown to be (approximately) proportional to a_{0}^{2}. Before reaching this extreme regime, the coexistence of the PA and the wakefield acceleration is observed where the wave structures driven by the wakefields show the phenomenon of multiple and folded wave breakings. Investigated are various signatures of the acceleration processes such as the dependence on the mass ratio for the energy gain as well as the energy spectral features. The relevance to high energy cosmic ray acceleration and to the relativistic laser acceleration is considered.

With the increasing development of laser electron accelerators, electron energies beyond a GeV have been reached and higher values are expected in the near future. A conventional beam dump based on ionization or radiation loss mechanisms is cumbersome and costly, not to mention the radiological hazards. We revisit the stopping power theory of high-energy charged particles in matter and discuss the associated problem of beam dumping from the point of view of collective deceleration. The collective stopping length in an ionized gas can be several orders of magnitude shorter than that described by the Bethe-Bloch formulas and associated with multiple electromagnetic cascades in solids. At the same time, the tenuous density of the gas makes the radioactivation negligible. Such a compact beam dump without radioactivation works well for short and dense bunches, as they are typically generated from a laser wakefield accelerator. In addition, the nonuniform transverse wakefield can induce microbunching of the electron bunch by betatron oscillation. The microstructure could serve as a prebunched source for coherent radiation or feeding a free electron laser.

Since its birth, the laser has been extraordinarily effective in the study and applications of laser-matter interaction at the atomic and molecular level and in the nonlinear optics of the bound electron. In its early life, the laser was associated with the physics of electron volts and of the chemical bond. Over the past fifteen years, however, we have seen a surge in our ability to produce high intensities, 5 to 6 orders of magnitude higher than was possible before. At these intensities, particles, electrons, and protons acquire kinetic energy in the megaelectron-volt range through interaction with intense laser fields. This opens a new age for the laser, the age of nonlinear relativistic optics coupling even with nuclear physics. We suggest a path to reach an extremely high-intensity level 10^{26–28} W/cm^{2} in the coming decade, much beyond the current and near future intensity regime 10^{23} W/cm^{2}, taking advantage of the megajoule laser facilities. Such a laser at extreme high intensity could accelerate particles to frontiers of high energy, teraelectron volt, and petaelectron volt, and would become a tool of fundamental physics encompassing particle physics, gravitational physics, nonlinear field theory, ultrahigh-pressure physics, astrophysics, and cosmology. We focus our attention on high-energy applications, in particular, and the possibility of merged reinforcement of high-energy physics and ultraintense laser.

A recent study on a high energy accelerator system which involves multistage laser wakefield acceleration shows that the system is very sensitive to jitters due to misalignment between the beam and the wakefield. In particular, the effect of jitters in the presence of a strong focusing wakefield and initial phase space spread of the beam leads to severe emittance degradation of the beam. One way to improve the emittance control is to mitigate the wakefield by working with a plasma channel. However, there are limitations in this approach. Our present investigation does not involve a plasma channel. Instead of averaging over the full phase range of the quarter-wave acceleration, we treat the phase range as a variable. We have found that, for a fixed final acceleration energy and a small phase slip, the final emittance is inversely proportional to the total number of stages. This leads us to consider an accelerator system which consists of superunits, where each superunit consists of closely spaced short tubes, or chips, with the wakefield of each chip being created by an independent laser pulse. There is a relatively large gap between adjacent superunits. With this arrangement the beam electrons are accelerated with a small phase slip; i.e., the phase of the beam is approximately synchronous with respect to the wakefield. This system is designed to have resilience against jitters. It has its practical limitations. We also consider a “horn model” with an exact synchronous acceleration based on a scheme suggested by Katsouleas. Computer simulation of both the chip model and the horn model confirms an expected (sinψ)^{3/2} law for emittance degradation in the small phase angle region. Thus the choice of a small loading phase together with a small phase slip provides another important ingredient in controlling emittance degradation.

The dynamics of particles in laser pulse-driven wakefields over multistages in a collider is studied. A map of phase space dynamics over a stage of wakefield acceleration induced by a laser pulse (or electron beam) is derived. The entire system of a collider is generated with a product of multiple maps of wakefields, drifts, magnets, etc. This systems map may include offsets of various elements of the accelerator, representing noise and errors arising from the operation of such a complex device. We find that an unmitigated strong focusing of the wakefield coupled with the alignment errors of the position (or laser beam aiming) of each wakefield stage and the unavoidable dispersion in individual particle betatron frequencies leads to a phase space mixing and causes a transverse emittance degradation. The rate of the emittance increase is proportional to the number of stages, the energy of the particles, the betatron frequency, the square of the misalignment amplitude, and the square of the betatron phase shift over a single stage. The accelerator with a weakened focus in a channel can, therefore, largely suppress the emittance degradation due to errors.

Land plants have evolved a hydrophobic cuticle on the surface of aerial organs as an adaptation to ensure survival in terrestrial environments. Cuticle is mainly composed of lipids, namely cutin and intracuticular wax, with epicuticular wax deposited on plant surface. The composition and permeability of cuticle have a large influence on its ability to protect plants against drought stress. However, the regulatory mechanisms underlying cuticular wax biosynthesis in response to drought stress have not been fully elucidated. Here, we identified three AP2/ERF transcription factors (DREB26/ERF12, ERF13 and ERF14) involved in the regulation of water permeability of the plant surface. Transmission electron microscopy revealed thicker cuticle on the leaves of DREB26-overexpressing (DREB26OX) plants, and thinner cuticle on the leaves of transgenic plants expressing SRDX repression domain-fused DREB26 (DREB26SR). Genes involved in cuticular wax formation were upregulated in DREB26OX and downregulated in DREB26SR. The levels of very-long chain (VLC) alkanes, which are a major wax component, increased in DREB26OX leaves and decreased in DREB26SR leaves. Under dehydration stress, water loss was reduced in DREB26OX and increased in DREB26SR. The erf12/13/14 triple mutant showed delayed growth, decreased leaf water content, and reduced drought-inducible VLC alkane accumulation. Taken together, our results indicate that the DREB26/ERF12 and its closed family members, ERF13 and ERF14, play an important role in cuticular wax biosynthesis in response to drought stress. The complex transcriptional cascade involved in the regulation of cuticular wax biosynthesis under drought stress conditions is discussed., (© 2024 The Author(s). The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.)

Stomatitis, which is a common side effect of chemotherapy, currently lacks a standardized approach for its prevention. Therefore, this multicenter, randomized, open-label, controlled phase III trial aims to assess the efficacy and safety of a dexamethasone-based mouthwash for preventing chemotherapy-induced stomatitis in patients with early breast cancer. We will randomly assign 230 patients with early breast cancer scheduled to receive chemotherapy in a 1:1 ratio to either the dexamethasone-based mouthwash group (10 ml, 0.1 mg/ml; swish for 2 min and spit 4 times daily for 8 weeks) or the mouthwash-with-tap-water group. The incidence of stomatitis, measured using electronic patient-reported outcomes, is the primary endpoint., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Adaptation and tolerance to changes in heat and cold temperature are essential for survival and proliferation in plants and animals. However, there is no clear information regarding the common molecules between animals and plants. In this study, we found that heat, and cold tolerance of the nematode Caenorhabditis elegans is oppositely regulated by the RNA-binding protein EMB-4, whose plant homolog contains polymorphism causing heat tolerance diversity. Caenorhabditis elegans alters its cold and heat tolerance depending on the previous cultivation temperature, wherein EMB-4 respectively acts as a positive and negative controller of heat and cold tolerance by altering gene expression. Among the genes whose expression is regulated by EMB-4, a phospholipid scramblase, and an acid sphingomyelinase, which are involved in membrane lipid metabolism, were found to play essential roles in the negative regulation of heat tolerance., (© The Author(s) 2024. Published by Oxford University Press on behalf of National Academy of Sciences.)

Acquired osmotolerance induced by initial exposure to mild salt stress is widespread across Arabidopsis thaliana ecotypes, but the mechanism underlying it remains poorly understood. To clarify it, we isolated acquired osmotolerance-deficient 1 (aod1), a mutant highly sensitive to osmotic stress, from ion-beam-irradiated seeds of Zu-0, an ecotype known for its remarkably high osmotolerance. Aod1 showed growth inhibition with spotted necrotic lesions on the rosette leaves under normal growth conditions on soil. However, its tolerance to salt and oxidative stresses was similar to that of the wild type (WT). Genetic and genome sequencing analyses suggested that the gene causing aod1 is identical to CONSTITUTIVELY ACTIVATED CELL DEATH 1 (CAD1). Complementation with the WT CAD1 gene restored the growth and osmotolerance of aod1, indicating that mutated CAD1 is responsible for the observed phenotypes in aod1. Although CAD1 is known to act as a negative regulator of immune response, transcript levels in the WT increased in response to osmotic stress. Aod1 displayed enhanced immune response and cell death under normal growth conditions, whereas the expression profiles of osmotic response genes were comparable to those of the WT. These findings suggest that autoimmunity in aod1 is detrimental to osmotolerance. Overall, our results suggest that CAD1 negatively regulates immune responses under osmotic stress, contributing to osmotolerance in Arabidopsis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Calcium (Ca2+) is a major ion in living organisms, where it acts as a second messenger for various biological phenomena. The Golgi apparatus retains a higher Ca2+ concentration than the cytosol and returns cytosolic Ca2+ to basal levels after transient elevation in response to environmental stimuli such as osmotic stress. However, the Ca2+ transporters localized in the Golgi apparatus of plants have not been clarified. We previously found that a wild-type (WT) salt-tolerant Arabidopsis (Arabidopsis thaliana) accession, Bu-5, showed osmotic tolerance after salt acclimatization, whereas the Col-0 WT did not. Here, we isolated a Bu-5 background mutant gene, acquired osmotolerance-defective 6 (aod6), which reduces tolerance to osmotic, salt, and oxidative stresses, with a smaller plant size than the WT. The causal gene of the aod6 mutant encodes CATION CALCIUM EXCHANGER4 (CCX4). The aod6 mutant was more sensitive than the WT to both deficient and excessive Ca2+. In addition, aod6 accumulated higher Ca2+ than the WT in the shoots, suggesting that Ca2+ homeostasis is disturbed in aod6. CCX4 expression suppressed the Ca2+ hypersensitivity of the csg2 (calcium sensitive growth 2) yeast (Saccharomyces cerevisiae) mutant under excess CaCl2 conditions. We also found that aod6 enhanced MAP kinase 3/6 (MPK3/6)-mediated immune responses under osmotic stress. Subcellular localization analysis of mGFP-CCX4 showed GFP signals adjacent to the trans-Golgi apparatus network and co-localization with Golgi apparatus-localized markers, suggesting that CCX4 localizes in the Golgi apparatus. These results suggest that CCX4 is a Golgi apparatus-localized transporter involved in the Ca2+ response and plays important roles in osmotic tolerance, shoot Ca2+ content, and normal growth of Arabidopsis., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of American Society of Plant Biologists.)

We have previously reported a wide variation in salt tolerance among Arabidopsis thaliana accessions and identified ACQOS , encoding a nucleotide-binding leucine-rich repeat (NLR) protein, as the causal gene responsible for the disturbance of acquired osmotolerance induced after mild salt stress. ACQOS is conserved among Arabidopsis osmosensitive accessions, including Col-0. In response to osmotic stress, it induces detrimental autoimmunity, resulting in suppression of osmotolerance, but how ACQOS triggers autoimmunity remains unclear. Here, we screened acquired osmotolerance ( aot ) mutants from EMS-mutagenized Col-0 seeds and isolated the aot19 mutant. In comparison with the wild type (WT), this mutant had acquired osmotolerance and decreased expression levels of pathogenesis-related genes. It had a mutation in a splicing acceptor site in NUCLEOPORIN 85 ( NUP85 ), which encodes a component of the nuclear pore complex. A mutant with a T-DNA insertion in NUP85 acquired osmotolerance similar to aot19. The WT gene complemented the osmotolerant phenotype of aot19 . We evaluated the acquired osmotolerance of five nup mutants of outer-ring NUP s and found that nup96 , nup107 , and aot19/nup85 , but not nup43 or nup133 , showed acquired osmotolerance. We examined the subcellular localization of the GFP-ACQOS protein and found that its nuclear translocation in response to osmotic stress was suppressed in aot19 . We suggest that NUP85 is essential for the nuclear translocation of ACQOS, and the loss-of-function mutation of NUP85 results in acquired osmotolerance by suppressing ACQOS-induced autoimmunity in response to osmotic stress., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Mori, Murakoshi, Tamura, Kunitake, Nishimura, Ariga, Tanaka, Iuchi, Yotsui, Sakata and Taji.)

Background: This study aimed to examine whether the incidence of febrile neutropenia (FN) during perioperative chemotherapy for breast cancer increased in patients with periodontal disease who had received prior dental treatment., Methods: This retrospective cohort study conducted at a single tertiary care center included patients diagnosed with clinical stages I-III of breast cancer and had started neoadjuvant or adjuvant intravenous chemotherapy between July 2015 and November 2021. The exposure was periodontal disease (probing depth ≥6 mm) diagnosed by dentists before the start of chemotherapy. Almost all the patients received dental treatment and oral care before initiating chemotherapy. The primary outcome was FN incidence during chemotherapy. We used a multivariable logistic regression model adjusted for age, diabetes mellitus, chemotherapy regimen, and the mean relative dose intensity., Results: Based on the eligibility criteria of this study, 141 women were included. The incidence of FN in the periodontal group (probing depth ≥6 mm) and control group (probing depth <6 mm) was 36.4% and 25.9%, respectively. The crude odds ratio (OR) for FN incidence was 1.63 (95% confidence interval [CI], 0.71-3.74; P = 0.24), and the adjusted OR was 1.52 (95% CI, 0.62-3.73; P = 0.36).  Conclusions: Occurrence of FN during perioperative chemotherapy for breast cancer is not a concern in patients undergoing dental treatment for periodontal disease before or during chemotherapy., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Yamaguchi et al.)

Plants are often exposed not only to short-term (S-) but also to long-term (L-)heat stress over several consecutive days. A few Arabidopsis mutants defective in L-heat tolerance have been identified, but the molecular mechanisms are less understood for this tolerance than for S-heat stress tolerance. To elucidate the mechanisms of the former, we used a forward genetic screen for sensitive to long-term heat ( sloh ) mutants and isolated sloh3 and sloh63 . The mutants were hypersensitive to L- but not to S-heat stress, and sloh63 was also hypersensitive to salt stress. We identified the causal genes, SLOH3 and SLOH63 , both of which encoded splicing-related components of the MOS4-associated complex (MAC). This complex is widely conserved in eukaryotes and has been suggested to interact with spliceosomes. Both genes were induced by L-heat stress in a time-dependent manner, and some abnormal splicing events were observed in both mutants under L-heat stress. In addition, endoplasmic reticulum (ER) stress and subsequent unfolded protein response occurred in both mutants under L-heat stress and were especially prominent in sloh63 , suggesting that enhanced ER stress is due to the salt hypersensitivity of sloh63 . Splicing inhibitor pladienolide B led to concentration-dependent disturbance of splicing, decreased L-heat tolerance, and enhanced ER stress. These findings suggest that maintenance of precise mRNA splicing under L-heat stress by the MAC is important for L-heat tolerance and suppressing ER stress in Arabidopsis., (© The Author(s) 2023. Published by Oxford University Press on behalf of National Academy of Sciences.)

Natural genetic variation has facilitated the identification of genes underlying complex traits such as stress tolerances. We here evaluated the long-term (L-) heat tolerance (37°C for 5 days) of 174 Arabidopsis thaliana accessions and short-term (S-) heat tolerance (42°C, 50 min) of 88 accessions and found extensive variation, respectively. Interestingly, L-heat-tolerant accessions are not necessarily S-heat tolerant, suggesting that the tolerance mechanisms are different. To elucidate the mechanisms underlying the variation, we performed a chromosomal mapping using the F 2 progeny of a cross between Ms-0 (a hypersensitive accession) and Col-0 (a tolerant accession) and found a single locus responsible for the difference in L-heat tolerance between them, which we named Long-term Heat Tolerance 1 ( LHT1 ). LHT1 is identical to MAC7 , which encodes a putative RNA helicase involved in mRNA splicing as a component of the MOS4 complex. We found one amino acid deletion in LHT1 of Ms-0 that causes a loss of function. Arabidopsis mutants of other core components of the MOS4 complex- mos4-2 , cdc5-1 , mac3a mac3b , and prl1 prl2 -also showed hypersensitivity to L-heat stress, suggesting that the MOS4 complex plays an important role in L-heat stress responses. L-heat stress induced mRNA processing-related genes and compromised alternative splicing. Loss of LHT1 function caused genome-wide detrimental splicing events, which are thought to produce nonfunctional mRNAs that include retained introns under L-heat stress. These findings suggest that maintaining proper alternative splicing under L-heat stress is important in the heat tolerance of A. thaliana ., (© The Author(s) 2023. Published by Oxford University Press on behalf of National Academy of Sciences.)

Genome sizes are known to vary within and among closely related species, but the knowledge about genomic factors contributing to the variation and their impacts on gene functions is limited to only a small number of species. This study identified a more than 2-fold heritable genome size variation among the unicellular Zygnematophycean alga, Closterium peracerosum-strigosum-littorale (C. psl.) complex, based on short-read sequencing analysis of 22 natural strains and F1 segregation analysis. Six de novo assembled genomes revealed that genome size variation is largely attributable to genome-wide copy number variation (CNV) among strains rather than mating type-linked genomic regions or specific repeat sequences such as rDNA. Notably, about 30% of genes showed CNV even between strains that can mate with each other. Transcriptome and gene ontology analysis demonstrated that CNV is distributed nonrandomly in terms of gene functions, such that CNV was more often observed in the gene set with stage-specific expression. Furthermore, in about 30% of these genes with CNV, the expression level does not increase proportionally with the gene copy number, suggesting presence of dosage compensation, which was overrepresented in genes involved in basic biological functions, such as translation. Nonrandom patterns in gene duplications and corresponding expression changes in terms of gene functions may contribute to maintaining the high level of CNV associated with extensive genome size variation in the C. psl. complex, despite its possible detrimental effects., (© The Author(s) 2023. Published by Oxford University Press on behalf of Society for Molecular Biology and Evolution.)

Background: We investigated the barriers to and promoters of taking BRCA testing, after the start of national healthcare insurance coverage for non-metastatic breast cancer patients in Japan., Patients and Methods: This was a multi-center, retrospective, cohort study. We included stage 0 to III breast cancer patients who were diagnosed and met the criteria for insurance coverage of BRCA testing between April 2020 and December 2021. We examined the association between BRCA testing and possible exposures: breast cancer diagnosis at 45 years or younger, triple-negative breast cancer (TNBC) diagnosis at the age of 60 or younger, two or more primary breast cancers, family history of breast cancer or ovarian cancer in the third degree of relatives, male breast cancer, medical expense limits, and parity. We used logistic regression analysis., Results: We included 222 patients and 123 (55.4%) of them underwent the test. In univariate analysis, a family history of ovarian cancer (odds ratio (OR) 10.59; 95% CI 1.35-82.96, p = 0.025), diagnosis of breast cancer at the age of 45 or younger (OR 2.78; 95% CI 1.52-5.14, p = 0.0009), and diagnosis of TNBC at the age of 60 or younger (OR 3.95; 95% CI 1.55-10.07, p = 0.004) were associated with taking the test. After multivariate logistic regression analysis, a family history of ovarian cancer (adjusted OR 12.80; 95% CI 1.51-108.80, p = 0.0195), diagnosis of breast cancer at the age of 45 or younger (adjusted OR 4.43; 95% CI 1.98-9.90, p = 0.0003), and TNBC at the age of 60 or younger (adjusted OR 5.28; 95% CI 1.90-14.66, p = 0.0014) were consistently associated., Conclusion: For non-metastatic breast cancer patients whose BRCA testing is covered by insurance, costs would no longer be a definite barrier. Physicians should keep in mind that a family history of ovarian cancer, breast cancer diagnosis at 45 years of age or younger and TNBC diagnosis at 60 years of age or younger are strong promoters., (© 2022. The Author(s), under exclusive licence to The Japanese Breast Cancer Society.)

Background/aim: This study aimed to show the trend of neutrophil counts and frequency of febrile neutropenia after changing pegfilgrastim from 3.6 mg to 1.8 mg., Patients and Methods: This case-series study was performed between April 2016 and December 2021 at Hyogo Prefectural Amagasaki General Medical Center. All patients who reduced their normal dose of 3.6 mg pegfilgrastim to 1.8 mg due to adverse events or markedly elevated neutrophil counts were included. Any type of chemotherapy was acceptable. Patients who dropped out within 1 month of receiving 1.8 mg pegfilgrastim were excluded. The primary outcome was the neutrophil counts after receiving 1.8 mg pegfilgrastim. The secondary outcome was febrile neutropenia, which was evaluated by the Common Terminology Criteria for Adverse Events v5.0., Results: The study included seven patients who used a regimen of dose-dense epirubicin and cyclophosphamide, trastuzumab, pertuzumab, and docetaxel, docetaxel, or docetaxel and cyclophosphamide. After using 1.8 mg pegfilgrastim, neutrophil counts changed from a mean of 18,944 [standard deviation (SD)=-7,768] to only 4,447 (SD=1,224). The patients experienced grades 1 to 3 adverse events during the use of 1.8 mg and 3.6 mg pegfilgrastim doses, including febrile neutropenia, and pain. Four patients (57%) complained of grade 1 or 2 fatigue and anorexia. After switching from 3.6 mg pegfilgrastim to 1.8 mg, three patients (42%) experienced adverse events., Conclusion: In patients who experienced adverse events due to markedly elevated neutrophil counts with pegfilgrastim, reducing the dose of pegfilgrastim by half may reduce adverse events., (Copyright © 2023 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Purpose: The purpose of this study was to perform an in vitro evaluation of digital impressions using a mobile device and monoscopic photogrammetry in cases of orbital defects with undercuts., Methods: Three 10-mm-square cubes were attached to a diagnostic cast of a patient with a right orbital defect. Still images acquired with a mobile device were used to generate facial three-dimensional (3D) data. Two types of still images were used: one was a whole face image, and the other was a defect site-focused image. For comparison, an extraoral scanner was used to obtain facial 3D data. Five dental technicians fabricated 3D printed models using additive manufacturing and measured the distances between the measurement points using a digital caliper. The discrepancy between the distances measured on the diagnostic cast of the patient and the 3D printed model was calculated. Friedman test was used to analyze the discrepancy, and the Bonferroni test was used to verify the differences between the pairs., Results: Statistical significance was found with respect to the type of 3D model fabrication method., Conclusion: Within the limitations of this in vitro study, the results suggested that the workflow can be applied to digital impressions of the maxillofacial region.

Land plants exhibit various adaptation responses to unfavorable water environments, such as drought and flooding. The phytohormone abscisic acid (ABA) and ethylene play essential roles in plant adaptation to drought and flooding, respectively. It remains largely unknown how plants integrate environmental information for water availability. In the moss Physcomitrium patens, we recently reported that not only ethylene/flooding signaling but also ABA/osmostress signaling are mediated by ethylene receptor-related sensor histidine kinases (ETR-HKs). Subfamily I ETR-HKs of this moss were found to interact with a RAF kinase (ARK) and were required for ABA-dependent activation of SNF1-related protein kinase 2 (SnRK2) via ARK activation. To elucidate the mechanisms of ARK regulation by ETR-HKs, here we employed targeted in vivo mutagenesis of PpHK5, a member of subfamily I ETR-HKs. Analyses of ABA-insensitive Pphk5 mutants indicated that PpHK5 mutations affecting the interaction with ARK resulted in loss of PpHK5 function to activate ABA signaling. We also identified a PpHK5 mutation that does not affect ARK interaction but resulted in loss of PpHK5 function. These results suggest that physical interaction between ETR-HK and ARK is essential but not sufficient for the regulation of ARK activity, and the C-terminal response regulator domain is involved in regulating ARK activation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Introduction: Reflecting multicultural society, the diversity of the healthcare professional students' ethnicities and cultures is promoted around the world. However, most of the healthcare professional education in Japan had been targeted mainly at students who follow the Japanese language and culture. The aim of this study is to clarify what Japanese dental students have culturally experienced and how they developed intercultural competence during their school life with international dental students in Japan., Materials and Methods: We conducted semi-structured interviews with 18 of the sixth-grade students in standard Japanese undergraduate dental programmes who shared required classes in Japan with non-Japanese-speaking international dental students in preclinical programmes. Based on the qualitative analysis of the interviews, we administered a questionnaire survey to 82 dental trainees (the seventh grade) in clinical training programmes who just graduated from various Japanese dental schools. Then, the answers of the questionnaire were statically analysed., Results: The interview identified a total of 37 constituent elements regarding "students' attitudes and experiences in school days" and "perceptions and motivations." Analysis of the questionnaire showed that the group experiencing a learning environment with international students had various communication with and respect for their various classmates and had the ambition to develop themselves. Especially, the participants who had international experiences both in and out of classrooms showed more active attitude on intercultural communication., Conclusions: Overall, for Japanese dental students, daily contact with international students gave direct and indirect cross-cultural experiences and recognitions. In particular, the Japanese students were stimulated active perceptions. The findings of this study can be used for future discussion about the cross-cultural education and collaboration of healthcare professionals not only within Japan but also around the world., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

At the transition from vegetative to reproductive growth in rice (Oryza sativa), a developmental program change occurs, resulting in panicle (rice inflorescence) formation. The initial event of the transition is the change of the shoot apical meristem to an inflorescence meristem (IM), accompanied by a rapid increase in the meristem size. Suppression of leaf growth also occurs, resulting in the formation of bracts. The IM generates branch meristems (BMs), indeterminate meristems that reiteratively generate next-order meristems. All meristems eventually acquire a determinate spikelet meristem identity and terminate after producing a floret. ABERRANT PANICLE ORGANIZATION2 (APO2) is the rice ortholog of Arabidopsis (Arabidopsis thaliana) LEAFY (LFY), a plant-specific transcription factor (TF). APO2 is a positive regulator of panicle branch formation. Here, we show that APO2 is also required to increase the meristem size of the IM and suppress bract outgrowth. We identified genes directly and indirectly regulated by APO2 and identified APO2-binding sites. These analyses showed that APO2 directly controls known regulators of panicle development, including SQUAMOSA PROMOTER BINDING PROTEIN LIKE14 and NECK LEAF1. Furthermore, we revealed that a set of genes act as downstream regulators of APO2 in controlling meristem cell proliferation during reproductive transition, bract suppression, and panicle branch formation. Our findings indicate that APO2 acts as a master regulator of rice panicle development by regulating multiple steps in the reproductive transition through directly controlling a set of genes., (© American Society of Plant Biologists 2022. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

In plants, a first layer of inducible immunity is conferred by pattern recognition receptors (PRRs) that bind microbe- and damage-associated molecular patterns to activate pattern-triggered immunity (PTI). PTI is strengthened or followed by another potent form of immunity when intracellular receptors recognize pathogen effectors, termed effector-triggered immunity. Immunity signaling regulators have been reported to influence abiotic stress responses as well, yet the governing principles and mechanisms remain ambiguous. Here, we report that PRRs of a leucine-rich repeat ectodomain also confer salt tolerance in Arabidopsis thaliana , following recognition of cognate ligands such as bacterial flagellin (flg22 epitope) and elongation factor Tu (elf18 epitope), and the endogenous Pep peptides. Pattern-triggered salt tolerance (PTST) requires authentic PTI signaling components; namely, the PRR-associated kinases BAK1 and BIK1 and the NADPH oxidase RBOHD . Exposure to salt stress induces the release of Pep precursors, pointing to the involvement of the endogenous immunogenic peptides in developing plant tolerance to high salinity. Transcriptome profiling reveals an inventory of PTST target genes, which increase or acquire salt responsiveness following a preexposure to immunogenic patterns. In good accordance, plants challenged with nonpathogenic bacteria also acquired salt tolerance in a manner dependent on PRRs. Our findings provide insight into signaling plasticity underlying biotic or abiotic stress cross-tolerance in plants conferred by PRRs.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Acquired osmotolerance after salt stress is widespread among Arabidopsis thaliana (Arabidopsis) accessions. Most salt-tolerant accessions exhibit acquired osmotolerance, whereas Col-0 does not. To identify genes that can confer acquired osmotolerance to Col-0 plants, we performed full-length cDNA overexpression (FOX) hunting using full-length cDNAs of halophyte Eutrema salsugineum , a close relative of Arabidopsis. We identified EsCYP78A5 as a gene that can confer acquired osmotolerance to Col-0 wild-type (WT) plants. EsCYP78A5 encodes a cytochrome P450 monooxygenase and the Arabidopsis ortholog is known as KLU. We also demonstrated that transgenic Col-0 plants overexpressing AtKLU ( AtKLU ox) exhibited acquired osmotolerance. Interestingly, KLU overexpression improved not only acquired osmotolerance but also osmo-shock, salt-shock, oxidative, and heat-stress tolerances. Under normal conditions, the AtKLU ox plants showed growth retardation with shiny green leaves. The AtKLU ox plants also accumulated higher anthocyanin levels and developed denser cuticular wax than WT plants. Compared to WT plants, the AtKLU ox plants accumulated significantly higher levels of cutin monomers and very-long-chain fatty acids, which play an important role in the development of cuticular wax and membrane lipids. Endoplasmic reticulum (ER) stress induced by osmotic or heat stress was reduced in AtKLU ox plants compared to WT plants. These findings suggest that KLU is involved in the cuticle biosynthesis, accumulation of cuticular wax, and reduction of ER stress induced by abiotic stresses, leading to the observed abiotic stress tolerances., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Kajino, Yamaguchi, Oshima, Nakamura, Narushima, Yaguchi, Yotsui, Sakata and Taji.)

Acquired osmotolerance induced after salt stress is widespread across Arabidopsis thaliana (Arabidopsis) accessions (e.g., Bu-5). However, it remains unclear how this osmotolerance is established. Here, we isolated a mutant showing an acquired osmotolerance-defective phenotype ( aod2 ) from an ion-beam-mutagenized M2 population of Bu-5. aod2 was impaired not only in acquired osmotolerance but also in osmo-shock, salt-shock, and long-term heat tolerances compared with Bu-5, and it displayed abnormal morphology, including small, wrinkled leaves, and zigzag-shaped stems. Genetic analyses of aod2 revealed that a 439-kbp region of chromosome 4 was translocated to chromosome 3 at the causal locus for the osmosensitive phenotype. The causal gene of the aod2 phenotype was identical to ECERIFERUM 10 ( CER10 ), which encodes an enoyl-coenzyme A reductase that is involved in the elongation reactions of very-long-chain fatty acids (VLCFAs) for subsequent derivatization into cuticular waxes, storage lipids, and sphingolipids. The major components of the cuticular wax were accumulated in response to osmotic stress in both Bu-5 WT and aod2 . However, less fatty acids, primary alcohols, and aldehydes with chain length ≥ C30 were accumulated in aod2 . In addition, aod2 exhibited a dramatic reduction in the number of epicuticular wax crystals on its stems. Endoplasmic reticulum stress mediated by bZIP60 was increased in aod2 under osmotic stress. The only cer10 showed the most pronounced loss of epidermal cuticular wax and most osmosensitive phenotype among four Col-0-background cuticular wax-related mutants. Together, the present findings suggest that CER10/AOD2 plays a crucial role in Arabidopsis osmotolerance through VLCFA metabolism involved in cuticular wax formation and endocytic membrane trafficking., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Fukuda, Oshima, Ariga, Kajino, Koyama, Yaguchi, Tanaka, Yotsui, Sakata and Taji.)

Initial exposure of plants to osmotic stress caused by drought, cold, or salinity leads to acclimation, termed acquired tolerance, to subsequent severe stresses. Acquired osmotolerance induced by salt stress is widespread across Arabidopsis (Arabidopsis thaliana) accessions and is conferred by disruption of a nucleotide-binding leucine-rich repeat gene, designated ACQUIRED OSMOTOLERANCE. De-repression of this gene under osmotic stress causes detrimental autoimmunity via ENHANCED DISEASE SUSCEPTIBILITY1 and PHYTOALEXIN DEFICIENT4 (PAD4). However, the mechanism underlying acquired osmotolerance remains poorly understood. Here, we isolated an acquired osmotolerance-defective mutant (aod13) by screening 30,000 seedlings of an ion beam-mutagenized M2 population of Bu-5, an accession with acquired osmotolerance. We found that AOD13 encodes the dual-specificity phosphatase MAP KINASE PHOSPHATASE1 (MKP1), which negatively regulates MITOGEN-ACTIVATED PROTEIN KINASE3/6 (MPK3/6). Consistently, MPK3/6 activation was greater in aod13 than in the Bu-5 wild-type (WT). The aod13 mutant was sensitive to osmotic stress but tolerant to salt stress. Under osmotic stress, pathogenesis-related genes were strongly induced in aod13 but not in the Bu-5 WT. Loss of PAD4 in pad4 aod13 plants did not restore acquired osmotolerance, implying that activation of immunity independent of PAD4 renders aod13 sensitive to osmotic stress. These findings suggest that AOD13 (i.e. MKP1) promotes osmotolerance by suppressing the PAD4-independent immune response activated by MPK3/6., (© The Author(s) 2022. Published by Oxford University Press on behalf of American Society of Plant Biologists.)

Plants are often exposed not only to short-term (S) heat stress but also to long-term (L) heat stress over several consecutive days. A few Arabidopsis mutants defective in L-heat tolerance have been identified, but the molecular mechanisms involved are less well understood than those involved in S-heat tolerance. To elucidate the mechanisms, we isolated the new sensitive to long-term heat5 (sloh5) mutant from EMS-mutagenized seeds of L-heat-tolerant Col-0. The sloh5 mutant was hypersensitive to L-heat but not to S-heat, osmo-shock, salt-shock or oxidative stress. The causal gene, SLOH5, is identical to elongatedmitochondria1 (ELM1), which plays an important role in mitochondrial fission in conjunction with dynamin-related proteins DRP3A and DRP3B. Transcript levels of ELM1, DRP3A and DRP3B were time-dependently increased by L-heat stress, and drp3a drp3b double mutants were hypersensitive to L-heat stress. The sloh5 mutant contained massively elongated mitochondria. L-heat stress caused mitochondrial dysfunction and cell death in sloh5. Furthermore, WT plants treated with a mitochondrial myosin ATPase inhibitor were hypersensitive to L-heat stress. These findings suggest that mitochondrial fission and function are important in L-heat tolerance of Arabidopsis., (© The Author(s) 2021. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)