Springer Acta Medica Okayama 0918-9440 2026 CDPKs as Ca2+ signaling decoders in guard cell signaling EN Izumi C. Mori Institute of Plant Science and Resources, Okayama University Stomatal movements are essential for balancing photosynthetic carbon dioxide uptake with water conservation and defense against pathogens. These processes are controlled by complex signaling networks in guard cells, in which calcium ions (Ca2+) act as a ubiquitous second messenger. Although stimulus-specific Ca2+ signatures have been well documented, how these signals are decoded into distinct physiological responses remains a central question in plant biology. Increasing evidence highlights calcium-dependent protein kinases (CDPKs) as key signal decoders in guard cell signaling. This mini-review summarizes recent advances in our understanding of how CDPKs perceive and translate Ca2+ fluctuations into stomatal responses. We focus on the roles of CDPKs in signaling pathways triggered by diverse stimuli, including phytohormones such as abscisic acid ABA, jasmonates, and salicylic acid, as well as biotic cues such as microbe- or pathogen-associated molecular patterns (MAMPs/PAMPs) and pathogen infection. We also discuss how gaseous signals and metabolic cues are integrated into CDPK-mediated pathways. In addition to their established role as downstream decoders of Ca2+ signals, emerging studies suggest that CDPKs can act upstream of Ca2+ oscillations and may also function through Ca2+-independent mechanisms. Together, these findings highlight the context-dependent and integrative roles of CDPKs in regulating stomatal behavior, contributing to plant fitness under fluctuating environmental conditions. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 0971-5894 2026 Suppression of salt-enhanced apoplastic flow by salicylic acid in rice EN Md. Asadulla Al Galib Graduate School of Environmental and Life Science, Okayama University Maoxiang Zhao Graduate School of Environmental and Life Science, Okayama University Toshiyuki Nakamura Graduate School of Environmental and Life Science, Okayama University Yoshimasa Nakamura Graduate School of Environmental and Life Science, Okayama University Yoshihiko Hirai Graduate School of Environmental and Life Science, Okayama University Yoshitaka Nakashima Graduate School of Environmental and Life Science, Okayama University Shintaro Munemasa Graduate School of Environmental and Life Science, Okayama University Izumi C. Mori Institute of Plant Science and Resources, Okayama University Yoshiyuki Murata Graduate School of Environmental and Life Science, Okayama University Salinity enhances apoplastic flow, resulting in an increment of Na+ uptake and a lower K+/Na+ ratio. Salicylic acid (SA) plays an important role in improving salinity tolerance in plants. The effect of exogenous SA on apoplastic flow in salt-treated rice seedlings was studied using an apoplastic tracer, 8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS) in light. Application of NaCl at 25 mM to the hydroponic solution significantly increased PTS uptake, while 25 mM NaCl did not affect seedling growth. Application of 25 mM NaNO3 increased PTS uptake to the same degree. Salinity significantly increased sodium (Na+) content but had no significant effect on potassium (K+) content, resulting in a lower K+/Na+ ratio. The application of SA at 0.05 mM and 0.1 mM to the hydroponic solution reduced Na-enhanced PTS uptake. Salicylic acid at 0.05 mM and 0.1 mM significantly reduced Na+ content and slightly increased K+ content in the shoots of rice seedlings, resulting in a higher K+/Na+ ratio. However, SA at up to 0.1 mM did not increase SA contents in shoots under salt stress. These results suggest that exogenous SA reduces Na+ uptake by suppressing Na+-enhanced apoplastic flow in rice seedlings. These findings provide insight into modulation of Na+ transport pathways from roots to shoots by SA and may allow us to utilize brackish water for rice cultivation and to improve salt-tolerant rice through suppression of salt-enhanced apoplastic flow by chemicals such as salicylic acid. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 0718-9508 2025 Suppression of Na+ Uptake Via Apoplastic Flow by Chitosan in Rice EN Maoxiang Zhao Graduate School of Environmental and Life Science, Okayama University Md. Asadulla Al Galib Graduate School of Environmental and Life Science, Okayama University Toshiyuki Nakamura Graduate School of Environmental and Life Science, Okayama University Yoshimasa Nakamura Graduate School of Environmental and Life Science, Okayama University Yoshihiko Hirai Graduate School of Environmental and Life Science, Okayama University Yoshitaka Nakashima Shintaro Munemasa Graduate School of Environmental and Life Science, Okayama University Izumi C. Mori Institute of Plant Science and Resources, Okayama University Yoshiyuki Murata Graduate School of Environmental and Life Science, Okayama University Purpose: Chitosan enhances tolerance to salinity in rice. Apoplastic flow plays a crucial role in the accumulation of sodium (Na+) in rice under salinity. This study investigated the effects of exogenous chitosan on apoplastic flow and Na+ uptake in NaCl-treated rice seedlings. Methods: We employed an apoplastic tracer, trisodium salt of 8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS), in order to evaluate apoplastic flow in rice (Oryza sativa L., cv. Nipponbare) seedlings that were hydroponically grown in the solution containing NaCl (0 and 25 mM), and chitosan (0 mg L− 1, 10 mg L− 1, and 50 mg L− 1). Results: Application of 25 mM NaCl significantly increased PTS uptake and Na+ content in shoots but did not affect K+ content, resulting in a lower K+/Na+ ratio although 25 mM NaCl did not affect the seedling growth. The application of chitosan suppressed Na+-enhanced PTS uptake and Na+ accumulation in shoots without affecting the K+ content, which led to a higher K+/Na+ ratio. Moreover, chitosan did not affect the reducing sugar content or electrical conductivity in the solution containing NaCl. Conclusions: These results suggest that application of chitosan suppressed Na+-enhanced apoplastic flow to reduce Na+ uptake in rice seedlings. No potential conflict of interest relevant to this article was reported.

MDPI AG Acta Medica Okayama 2073-4409 14 17 2025 Discovery and Functional Characterization of Novel Aquaporins in Tomato (Solanum lycopersicum): Implications for Ion Transport and Salinity Tolerance 1305 EN Newton Chandra Paul Institute of Plant Science and Resources, Okayama University Shahin Imran Institute of Plant Science and Resources, Okayama University Anri Mitsumoto Institute of Plant Science and Resources, Okayama University Izumi C. Mori Institute of Plant Science and Resources, Okayama University Maki Katsuhara Institute of Plant Science and Resources, Okayama University Aquaporins (AQPs) are membrane proteins that facilitate the transport of water and solutes. Among AQPs, plasma membrane intrinsic proteins (PIPs) play a critical role in maintaining water balance between the internal and external cell environments. This study focuses on the tomato due to its economic importance and cultivation under moderate salinity conditions in Japan. A swelling assay using X. laevis oocyte confirmed that all five examined tomato SlPIP2 isoforms showed water transport activity. Among them, two-electrode voltage clamp (TEVC) experiments showed that only SlPIP2;1, SlPIP2;4, and SlPIP2;8 transport Na+ and K+, with no transport activity for Cs+, Rb+, Li+, or Cl−. CaCl2 (1.8 mM) reduced ionic currents by approximately 45% compared to 30 µM free-Ca2+. These isoforms function as very low-affinity Na+ and K+ transporters. Expression analysis showed that SlPIP2;4 and SlPIP2;8 had low, stable expression, while SlPIP2;1 was strongly upregulated in roots NaCl treatment (200 mM, 17days), suggesting distinct physiological roles for these ion-conducting AQPs (icAQPs). These data hypothesized that tomato icAQPs play a critical role in ion homeostasis, particularly under salinity stress. In conclusion, the first icAQPs have been identified in the dicotyledonous crop. These icAQPs are essential for plant resilience under salt stress. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 0140-7791 2025 Amino Acid Substitutions in Loop C of Arabidopsis PIP2 Aquaporins Alters the Permeability of CO2 EN Shaila Shermin Tania Institute of Plant Science and Resources, Okayama University Shigeko Utsugi Institute of Plant Science and Resources, Okayama University Yoshiyuki Tsuchiya Institute of Plant Science and Resources, Okayama University Shizuka Sasano Institute of Plant Science and Resources, Okayama University Maki Katsuhara Institute of Plant Science and Resources, Okayama University Izumi C. Mori Institute of Plant Science and Resources, Okayama University The transport of CO2 across biomembranes in plant cells is essential for efficient photosynthesis. Some aquaporins capable of CO2 transport, referred to as ‘COOporins’, are postulated to play a crucial role in leaf CO2 diffusion. However, the structural basis of CO2 permeation through aquaporins remains largely unknown. Here, we show that amino acids in loop C are critical for the CO2 permeability of Arabidopsis thaliana PIP2 aquaporins. We found that swapping tyrosine and serine in loop C to histidine and phenylalanine, which differ between AtPIP2;1 and AtPIP2;3, altered CO2 permeability when examined in the Xenopus laevis oocyte heterologous expression system. AlphaFold2 modelling indicated that these substitution induced a conformational shift in the sidechain of arginine in the aromatic/arginine (ar/R) selectivity filter and in lysine at the extracellular mouth of the monomeric pore in PIP2 aquaporins. Our findings demonstrate that distal amino acid substitutions can trigger conformational changes of the ar/R filter in the monomeric pore, modulating CO2 permeability. Additionally, phylogenetic analysis suggested that aquaporins capable of dual water/CO2 permeability are ancestral to those that are water-selective and CO2-impermeable, and CO2-selective and water impermeable. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 0031-9317 177 4 2025 CNGC2 Negatively Regulates Stomatal Closure and Is Not Required for flg22- and H2O2-Induced Guard Cell [Ca2+]cyt Elevation in Arabidopsis thaliana e70396 EN Rojina Akter Graduate School of Environmental and Life Science, Okayama University Yasuhiro Inoue Graduate School of Environmental and Life Science, Okayama University Saori Masumoto Faculty of Agriculture, Okayama University Yoshiharu Mimata Graduate School of Environmental and Life Science, Okayama University Takakazu Matsuura Institute of Plant Science and Resources, Okayama University Izumi C. Mori Toshiyuki Nakamura Graduate School of Environmental and Life Science, Okayama University Yoshimasa Nakamura Graduate School of Environmental and Life Science, Okayama University Yoshiyuki Murata Graduate School of Environmental and Life Science, Okayama University Shintaro Munemasa Graduate School of Environmental and Life Science, Okayama University In guard cells, cytosolic Ca2+ acts as a second messenger that mediates abscisic acid (ABA)- and pathogen-associated molecular pattern (PAMP)-induced stomatal closure. It was reported that Arabidopsis cyclic nucleotide-gated ion channel 2 (CNGC2) functions as hydrogen peroxide (H2O2)- and PAMP-activated Ca2+-permeable channels at the plasma membrane of mesophyll cells and mediates Ca2+-dependent PAMP-triggered immunity. In this study, we examined the role of CNGC2 in the regulation of stomatal movement because CNGC2 is also expressed in guard cells. We found that stomata of the CNGC2 disruption mutant cngc2-3 are constitutively closed even in the absence of ABA or the flagellar-derived PAMP, flg22. Consistently, leaf temperatures of the cngc2-3 mutant were higher than those of wild-type (WT) plants. The stomatal phenotype of the cngc2-3 mutant was restored by complementation with wild-type CNGC2 under the control of the guard cell preferential promoter, pGC1. Elevation of cytosolic free Ca2+ concentration in guard cells induced by flg22 and H2O2 remained intact in the cngc2-3 mutant. The introduction of the ost1-3 mutation into the cngc2-3 background did not alter the stomatal phenotype. However, the stomatal phenotype of the cngc2-3 mutant was successfully rescued in the double disruption mutant cngc2-3aba2-2. Taken together, these results suggest that CNGC2 negatively regulates stomatal closure response and does not function as flg22– and H2O2-activated Ca2+ channels in guard cells. Though CNGC2 is responsive for H2O2- and flg22-induced [Ca2+]cyt elevation in mesophyll cells, the involvement of CNGC2 in the response to H2O2 and flg22 in guard cells is questionable. No potential conflict of interest relevant to this article was reported.

Oxford University Press (OUP) Acta Medica Okayama 0032-0781 2025 Sulfur dioxide-induced guard cell death and stomatal closure are attenuated in nitrate/proton antiporter AtCLCa mutants EN Lia Ooi Institute of Plant Science and Resources, Okayama University Takakazu Matsuura Institute of Plant Science and Resources, Okayama University Izumi C. Mori Institute of Plant Science and Resources, Okayama University Guard cells surrounding the stomata play a crucial role in regulating the entrance of hazardous gases such as SO2 into leaves. Stomatal closure could be a plant response to mitigate SO2 damage, although the mechanism for SO2-induced closure remains controversial. Proposed mediators for SO2-induced stomatal closure include phytohormones, reactive oxygen species, gasotransmitters, and cytosolic acidification. In this study, we investigated the mechanism of stomatal closure in Arabidopsis in response to SO2. Despite an increment in auxin and jasmonates after SO2 exposure, the addition of auxin did not cause stomatal closure and jasmonate-insensitive mutants exhibited SO2-induced stomatal closure suggesting auxin and jasmonates are not mediators leading to the closure. In addition, supplementation of scavenging reagents for reactive oxygen species and gasotransmitters did not inhibit SO2-induced closure. Instead, we found that cytosolic acidification is a credible mechanism for SO2-induced stomatal closure in Arabidopsis. CLCa mutants coding H+/nitrate antiporter, involved in cytosolic pH homeostasis, showed less sensitive stomatal phenotype against SO2. These results suggest that cytosolic pH homeostasis plays a tenable role in SO2 response in guard cells. No potential conflict of interest relevant to this article was reported.

Oxford University Press (OUP) Acta Medica Okayama 1347-6947 88 10 2024 Cytosolic acidification and oxidation are the toxic mechanisms of SO2 in Arabidopsis guard cells 1164 1171 EN Mahdi Mozhgani Institute of Plant Science and Resources, Okayama University Lia Ooi Institute of Plant Science and Resources, Okayama University Christelle Espagne Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC) Sophie Filleur Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC) Izumi C Mori Institute of Plant Science and Resources, Okayama University SO2/H2SO3 can damage plants. However, its toxic mechanism has still been controversial. Two models have been proposed, cytosolic acidification model and cellular oxidation model. Here, we assessed the toxic mechanism of H2SO3 in three cell types of Arabidopsis thaliana, mesophyll cells, guard cells (GCs), and petal cells. The sensitivity of GCs of Chloride channel a (CLCa)-knockout mutants to H2SO3 was significantly lower than those of wildtype plants. Expression of other CLC genes in mesophyll cells and petal cells were different from GCs. Treatment with antioxidant, disodium 4,5-dihydroxy-1,3-benzenedisulfonate (tiron), increased the median lethal concentration (LC50) of H2SO3 in GCs indicating the involvement of cellular oxidation, while the effect was negligible in mesophyll cells and petal cells. These results indicate that there are two toxic mechanisms of SO2 to Arabidopsis cells: cytosolic acidification and cellular oxidation, and the toxic mechanism may vary among cell types. No potential conflict of interest relevant to this article was reported.

Oxford University Press (OUP) Acta Medica Okayama 1347-6947 87 11 2023 The effect of exogenous dihydroxyacetone and methylglyoxal on growth, anthocyanin accumulation, and the glyoxalase system in Arabidopsis 1323 1331 EN Maoxiang Zhao Graduate School of Environmental and Life Science, Okayama University Toshiyuki Nakamura Graduate School of Environmental and Life Science, Okayama University Yoshimasa Nakamura Graduate School of Environmental and Life Science, Okayama University Shintaro Munemasa Graduate School of Environmental and Life Science, Okayama University Izumi C Mori Institute of Plant Science and Resources, Okayama University Yoshiyuki Murata Graduate School of Environmental and Life Science, Okayama University Dihydroxyacetone (DHA) occurs in wide-ranging organisms, including plants, and can undergo spontaneous conversion to methylglyoxal (MG). While the toxicity of MG to plants is well-known, the toxicity of DHA to plants remains to be elucidated. We investigated the effects of DHA and MG on Arabidopsis. Exogenous DHA at up to 10 mM did not affect the radicle emergence, the expansion of green cotyledons, the seedling growth, or the activity of glyoxalase II, while DHA at 10 mM inhibited the root elongation and increased the activity of glyoxalase I. Exogenous MG at 1.0 mM inhibited these physiological responses and increased both activities. Dihydroxyacetone at 10 mM increased the MG content in the roots. These results indicate that DHA is not so toxic as MG in Arabidopsis seeds and seedlings and suggest that the toxic effect of DHA at high concentrations is attributed to MG accumulation by the conversion to MG. No potential conflict of interest relevant to this article was reported.

Oxford University Press Acta Medica Okayama 0022-0957 71 16 2020 Low temperature modulates natural peel degreening in lemon fruit independently of endogenous ethylene 4778 4796 EN Oscar W. Mitalo Graduate School of Environmental and Life Science, Okayama University Takumi Otsuki Graduate School of Environmental and Life Science, Okayama University Rui Okada Graduate School of Environmental and Life Science, Okayama University Saeka Obitsu Graduate School of Environmental and Life Science, Okayama University Kanae Masuda Graduate School of Environmental and Life Science, Okayama University Yuko Hojo Institute of Plant Science and Resources, Okayama University Takakazu Matsuura Institute of Plant Science and Resources, Okayama University Izumi C. Mori Institute of Plant Science and Resources, Okayama University Daigo Abe National Agriculture and Food Research Organization, Shikoku Research Station William O. Asiche Department of Research and Development, Del Monte Kenya Ltd Takashi Akagi Graduate School of Environmental and Life Science, Okayama University Yasutaka Kubo Graduate School of Environmental and Life Science, Okayama University Koichiro Ushijima Graduate School of Environmental and Life Science, Okayama University Peel degreening is an important aspect of fruit ripening in many citrus fruit, and previous studies have shown that it can be advanced by ethylene treatment or by low-temperature storage. However, the important regulators and pathways involved in natural peel degreening remain largely unknown. To determine how natural peel degreening is regulated in lemon fruit (Citrus limon), we studied transcriptome and physiochemical changes in the flavedo in response to ethylene treatment and low temperatures. Treatment with ethylene induced rapid peel degreening, which was strongly inhibited by the ethylene antagonist, 1-methylcyclopropene (1-MCP). Compared with 25 degrees C, moderately low storage temperatures of 5-20 degrees C also triggered peel degreening. Surprisingly, repeated 1-MCP treatments failed to inhibit the peel degreening induced by low temperature. Transcriptome analysis revealed that low temperature and ethylene independently regulated genes associated with chlorophyll degradation, carotenoid metabolism, photosystem proteins, phytohormone biosynthesis and signalling, and transcription factors. Peel degreening of fruit on trees occurred in association with drops in ambient temperature, and it coincided with the differential expression of low temperature-regulated genes. In contrast, genes that were uniquely regulated by ethylene showed no significant expression changes during on-tree peel degreening. Based on these findings, we hypothesize that low temperature plays a prominent role in regulating natural peel degreening independently of ethylene in citrus fruit. No potential conflict of interest relevant to this article was reported.

© 2020 The Authors. Published by Elsevier Ltd. Acta Medica Okayama 00456535 247 2020 Application of the cellular oxidation biosensor to Toxicity Identification Evaluations for high-throughput toxicity assessment of river water 125933 EN Lia Ooi Institute of Plant Science and Resources, Okayama University Keisuke Okazaki Institute of Plant Science and Resources, Okayama University Carlos R. Arias-Barreiro nstitute of Plant Science and Resources, Okayama University Lee Yook Heng Southeast Asia Disaster Prevention Research Initiative (SEADPRI-UKM), Institute for Environment and Development (LESTARI), The National University of Malaysia Izumi C. Mori Institute of Plant Science and Resources, Okayama University Toxicity Identification Evaluation (TIE) is a useful method for the classification and identification of toxicants in a composite environment water sample. However, its extension to a larger sample size has been restrained owing to the limited throughput of toxicity bioassays. Here we reported the development of a high-throughput method of TIE Phase I. This newly developed method was assisted by the fluorescence-based cellular oxidation (CO) biosensor fabricated with roGFP2-expressing bacterial cells in 96-well microplate format. The assessment of four river water samples from Langat river basin by this new method demonstrated that the contaminant composition of the four samples can be classified into two distinct groups. The entire toxicity assay consisted of 2338 tests was completed within 12 h with a fluorescence microplate reader. Concurrently, the sample volume for each assay was reduced to 50 μL, which is 600 to 4700 times lesser to compare with conventional bioassays. These imply that the throughput of the CO biosensor-assisted TIE Phase I is now feasible for constructing a large-scale toxicity monitoring system, which would cover a whole watershed scale. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 0140-7791 42 2 2018 The mechanism of SO2 -induced stomatal closure differs from O3 and CO2 responses and is mediated by nonapoptotic cell death in guard cells. 437 447 EN Lia Ooi Institute of Plant Science and Resources, Okayama University Takakazu Matsuura Institute of Plant Science and Resources, Okayama University Shintaro Munemasa Graduate School of Environmental and Life Science, Okayama University Yoshiyuki Murata Graduate School of Environmental and Life Science, Okayama University Maki Katsuhara Institute of Plant Science and Resources, Okayama University Takashi Hirayama Institute of Plant Science and Resources, Okayama University Izumi C. Mori Institute of Plant Science and Resources, Okayama University Plants closing stomata in the presence of harmful gases is believed to be a stress avoidance mechanism. SO2 , one of the major airborne pollutants, has long been reported to induce stomatal closure, yet the mechanism remains unknown. Little is known about the stomatal response to airborne pollutants besides O3 . SLOW ANION CHANNEL-ASSOCIATED 1 (SLAC1) and OPEN STOMATA 1 (OST1) were identified as genes mediating O3 -induced closure. SLAC1 and OST1 are also known to mediate stomatal closure in response to CO2 , together with RESPIRATORY BURST OXIDASE HOMOLOGs (RBOHs). The overlaying roles of these genes in response to O3 and CO2 suggested that plants share their molecular regulators for airborne stimuli. Here, we investigated and compared stomatal closure event induced by a wide concentration range of SO2 in Arabidopsis through molecular genetic approaches. O3 - and CO2 -insensitive stomata mutants did not show significant differences from the wild type in stomatal sensitivity, guard cell viability, and chlorophyll content revealing that SO2 -induced closure is not regulated by the same molecular mechanisms as for O3 and CO2 . Nonapoptotic cell death is shown as the reason for SO2 -induced closure, which proposed the closure as a physicochemical process resulted from SO2 distress, instead of a biological protection mechanism. No potential conflict of interest relevant to this article was reported.

Japanese Society of Plant Physiologists Acta Medica Okayama 0032-0781 57 8 2016 Involvement of OST1 Protein Kinase and PYR/PYL/RCAR Receptors in Methyl Jasmonate-Induced Stomatal Closure in Arabidopsis Guard Cells 1779 1990 EN Ye Yin Graduate School of Environmental and Life Science, Okayama University Yuji Adachi Graduate School of Environmental and Life Science, Okayama University Yoshimasa Nakamura Graduate School of Environmental and Life Science, Okayama University Shintaro Munemasa Graduate School of Environmental and Life Science, Okayama University Izumi C. Mori Institute of Plant Science and Resources, Okayama University Yoshiyuki Murata Graduate School of Environmental and Life Science, Okayama University Methyl jasmonate (MeJA) induces stomatal closure. It has been shown that stomata of many ABA-insensitive mutants are also insensitive to MeJA, and a low amount of ABA is a prerequisite for the MeJA response. However, the molecular mechanisms of the interaction between ABA and MeJA signaling remain to be elucidated. Here we studied the interplay of signaling of the two hormones in guard cells using the quadruple ABA receptor mutant pyr1 pyl1 pyl2 pyl4 and ABA-activated protein kinase mutants ost1-2 and srk2e. In the quadruple mutant, MeJA-induced stomatal closure, H2O2 production, nitric oxide (NO) production, cytosolic alkalization and plasma membrane Ca(2+)-permeable current (ICa) activation were not impaired. At the same time, the inactivation of the inward-rectifying K(+) current was impaired. In contrast to the quadruple mutant, MeJA-induced stomatal closure, H2O2 production, NO production and cytosolic alkalization were impaired in ost1-2 and srk2e as well as in aba2-2, the ABA-deficient mutant. The activation of ICa was also impaired in srk2e. Collectively, these results indicated that OST1 was essential for MeJA-induced stomatal closure, while PYR1, PYL1, PYL2 and PYL4 ABA receptors were not sufficient factors. MeJA did not appear to activate OST1 kinase activity. This implies that OST1 mediates MeJA signaling through an undetectable level of activity or a non-enzymatic action. MeJA induced the expression of an ABA synthesis gene, NCED3, and increased ABA contents only modestly. Taken together with previous reports, this study suggests that MeJA signaling in guard cells is primed by ABA and is not brought about through the pathway mediated by PYR1, PYL1 PYL2 and PYL4. No potential conflict of interest relevant to this article was reported.

Elsevier Ltd. Acta Medica Okayama 0045-6535 120 2015 Toxicity of tetramethylammonium hydroxide to aquatic organisms and its synergistic action with potassium iodide 299 304 EN Izumi C. Mori Carlos R. Arias-Barreiro Apostolos Koutsaftis Atsushi Ogo Tomonori Kawano Kazuharu Yoshizuka Salmaan H. Inayat-Hussain Isao Aoyama The aquatic ecotoxicity of chemicals involved in the manufacturing process of thin film transistor liquid crystal displays was assessed with a battery of four selected acute toxicity bioassays. We focused on tetramethylammonium hydroxide (TMAH, CAS No. 75-59-2), a widely utilized etchant. The toxicity of TMAH was low when tested in the 72 h-algal growth inhibition test (Pseudokirchneriellia subcapitata, EC50 = 360 mg L−1) and the Microtox® test (Vibrio fischeri, IC50 = 6.4 g L−1). In contrast, the 24 h-microcrustacean immobilization and the 96 h-fish mortality tests showed relatively higher toxicity (Daphnia magna, EC50 = 32 mg L−1 and Oryzias latipes, LC50 = 154 mg L−1). Isobologram and mixture toxicity index analyses revealed apparent synergism of the mixture of TMAH and potassium iodide when examined with the D. magna immobilization test. The synergistic action was unique to iodide over other halide salts i.e. fluoride, chloride and bromide. Quaternary ammonium ions with longer alkyl chains such as tetraethylammonium and tetrabutylammonium were more toxic than TMAH in the D. magna immobilization test. No potential conflict of interest relevant to this article was reported.

岡山大学環境管理センター Acta Medica Okayama 0917-1533 31 2009 岡山大学資源生物科学研究所における屋上緑化による建物冷却効果 21 25 EN Maki Katsuhara Shigemi Tanakamaru Izumi C. Mori Akio Tani Shigeko Utsugi Takashi Enomoto Toshihiko Maitani Roof greening is known to be environmentally friendly technology. Recently developed new roof greening systems, such as the thin-layer/Excel soil© system and the wetland type greening system, were tested at the roof top of buildings of Research Institute for Bioresources, Okayama University. After a multi-year test, these new systems have been established during high-temperature and less-rainfall summer seasons in the south Okayama region. Data indicated that roof greening effectively reduced the temperature of the concrete surface (more than 10°C). The room temperature under the green roof was also reduced both in a stock room (up to 6°C) and in an office room (about 2°C). We also provided the estimation indicating that this roof greening is useful for the decrease in CO(2) emission through the reduction of the electric power for air-conditioning in the summer. No potential conflict of interest relevant to this article was reported.