Repetitive transcranial magnetic stimulation induces kf-1 expression in the rat brain

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive approach used for stimulating the brain, and has proven effective in the treatment of depression, however the mechanism of its antidepressant action is unknown. Recently, we have reported the induction of kf-1 in rat frontal cortex and hippocampus after chronic antidepressant treatment and repeated electroconvulsive treatment (ECT). In this study, we demonstrated the induction of kf-1 after rTMS in the rat frontal cortex and hippocampus, but not in hypothalamus. Our data suggest that kf-1 may be a common functional molecule that is increased after antidepressant treatment, ECT and rTMS. In conclusion, it is proposed that induction of kf-1 may be associated with the treatment induced adaptive neural plasticity in the brain, which is a long-term target for their antidepressant action.     

Characterization of the yam tuber storage proteins from Dioscorea batatas exhibiting unique lectin activities

Four major proteins designated DB1, DB2, DB3, and DB4 were isolated and characterized from the yam tuber Dioscorea batatas. The ratios of their yields were 20:50:20:10. DB1 was a mannose-binding lectin (20 kDa) consisting of 10-kDa subunits and was classified as the monocot mannose-binding lectin family. DB2, accounting for 50% of the total protein, was the storage protein, commonly called dioscorins consisting of a 31-kDa subunit. On the basis of amino acid sequence, DB2 was classified to be dioscorin A. DB3 was a maltose-binding lectin, having an apparent molecular mass of 120 kDa and composed of a 66-kDa subunit and two 31-kDa subunits (DB3S). The 66-kDa subunit was further composed of two 31-kDa subunits (DB3L) cross-linked by disulfide bonds. DB3L and DB3S (242 and 241 amino acid residues, respectively) were homologous with each other with 72% sequence identity. They showed a sequence homology to dioscorin B and dioscorin A from Dioscorea alata, with 90 and 93% identity, respectively, and to carbonic anhydrase from Arabidopsis thaliana with about 45% identity. DB3S had one intrachain disulfide bond located at Cys(28)-Cys(187), whereas DB3L had one interchain disulfide bond (Cys(40)-Cys(40)') in addition to the intrachain disulfide bond (Cys(28)-Cys(188)) to form a 66-kDa subunit. DB1 and DB3 agglutinated rabbit erythrocytes at 2.7 and 3.9 microg/ml, respectively. Despite the structural homology between DB2 and DB3, DB2 had no lectin activity. The 66-kDa subunit itself revealed the full hemagglutinating activity of DB3, indicating that DB3L but not DB3S was responsible for the activity. The hemagglutinating activity of DB3 required Ca(2+) ions and was exclusively inhibited by maltose and oligomaltoses (e.g. maltopentaose and maltohexaose) but not by d-glucose. DB3 could not be classified into any known plant lectin family. DB4 was a chitinase, homologous to an acidic chitinase from Dioscorea japonica. DB1, DB2, and DB3 did not show any activity of carbonic anhydrase, amylase, or trypsin inhibitor activity. These results show that two of the four major proteins isolated from the yam tubers D. batatas have unique lectin activities.     

Bioactive nanoparticles stimulate bone tissue formation in bioprinted three‐dimensional scaffold and human mesenchymal stem cells

Bioprinting based on thermal inkjet printing is a promising but unexplored approach in bone tissue engineering. Appropriate cell types and suitable biomaterial scaffolds are two critical factors to generate successful bioprinted tissue. This study was undertaken in order to evaluate bioactive ceramic nanoparticles in stimulating osteogenesis of printed bone marrow‐derived human mesenchymal stem cells (hMSCs) in poly(ethylene glycol)dimethacrylate (PEGDMA) scaffold. hMSCs suspended in PEGDMA were co‐printed with nanoparticles of bioactive glass (BG) and hydroxyapatite (HA) under simultaneous polymerization so the printed substrates were delivered with highly accurate placement in three‐dimensional (3D) locations. hMSCs interacted with HA showed the highest cell viability (86.62 ± 6.02%) and increased compressive modulus (358.91 ± 48.05 kPa) after 21 days in culture among all groups. Biochemical analysis showed the most collagen production and highest alkaline phosphatase activity in PEG‐HA group, which is consistent with gene expression determined by quantitative PCR. Masson's trichrome staining also showed the most collagen deposition in PEG‐HA scaffold. Therefore, HA is more effective comparing to BG for hMSCs osteogenesis in bioprinted bone constructs. Combining with our previous experience in vasculature, cartilage, and muscle bioprinting, this technology demonstrates the capacity for both soft and hard tissue engineering with biomimetic structures.     

Preface: photosynthesis and hydrogen energy research for sustainability

Energy supply, climate change, and global food security are among the main chalenges facing humanity in the twenty-first century. Despite global energy demand is continuing to increase, the availability of low cost energy is decreasing. Together with the urgent problem of climate change due to CO₂ release from the combustion of fossil fuels, there is a strong requirement of developing the clean and renewable energy system for the hydrogen production. Solar fuel, biofuel, and hydrogen energy production gained unlimited possibility and feasibility due to understanding of the detailed photosynthetic system structures. This special issue contains selected papers on photosynthetic and biomimetic hydrogen production presented at the International Conference “Photosynthesis Research for Sustainability–2016”, that was held in Pushchino (Russia), during June 19–25, 2016, with the sponsorship of the International Society of Photosynthesis Research (ISPR) and of the International Association for Hydrogen Energy (IAHE). This issue is intended to provide recent information on the photosynthetic and biohydrogen production to our readers.     

Spatial and temporal variations in photosynthetic capacity of a temperate deciduous-evergreen forest

Key message

The understory evergreen trees showed maximal photosynthetic capacity in winter, while the overstory deciduous trees showed this capacity in spring. The time lag in productive ecophysiologically active periods between deciduous overstory and evergreen understory trees in a common temperate forest was clearly related to the amount of overstory foliage.

Abstract

In temperate forests, where deciduous canopy trees and evergreen understory trees coexist, understory trees experience great variation in incident radiation corresponding to canopy dynamics represented by leaf-fall and leaf-out. It is generally thought that changes in the light environment affect understory plants’ ecophysiological traits. Thus, to project and estimate annual energy, water, and carbon exchange between forests and the atmosphere, it is necessary to investigate seasonal variation in the ecophysiological activities of both evergreen trees in the understory and deciduous trees that make up the canopy/overstory. We conducted leaf-scale gas-exchange measurements and nitrogen content analyses for six tree species along their heights throughout a complete year. Photosynthetic capacity as represented by the maximum carboxylation rate (V _cmax25) and photosynthetic nitrogen use efficiency (PNUE) of deciduous canopy trees peaked immediately after leaf-out in late May, declined and stabilised during the mid-growing season, and drastically decreased just before leaf-fall. On the other hand, the timing of lowest V _cmax25 and PNUE for evergreen understory trees coincided with that of the highest values for canopy trees. Furthermore, understory trees’ highest values appeared just before canopy tree leaf-out, when incident radiation in the understory was highest. This implies that failing to consider seasonal variation in leaf ecophysiological traits for both canopy and understory trees could lead to serious errors in estimating ecosystem productivity and energy balance for temperate forests.

     

Hemagglutinins (lectins) in fruit bodies of Japanese higher fungi

Extracts from fruit bodies of 110 species of Japanese fungi were examined with trypsinized human and rabbit erythrocytes. More than 80% of the extracts showed the hemagglutination activities, a higher proportion than reported previously. Over half of species that had been reported to be inactive exhibited hemagglutination. Among them, some extracts showed human blood group specific-hemagglutination; A-specific,Panellus serotinus, Psathyrella piluliformis, Cantharellus cibarius andStropharia rugosoannulata; B-, O-specific,Gyroporus castaneus andPanellus stypticus; and Ospecific,Linderia bicolumnata andPhallus impudicus. Twenty-one species were reactive toward only rabbit erythrocytes. Several species exhibited very high hemagglutination activity. The results suggested that some of these Japanese fungi would be promising sources of lectins.     

ABA-hypersensitive germination3 encodes a protein phosphatase 2C (AtPP2CA) that strongly regulates abscisic acid signaling during germination among Arabidopsis protein phosphatase 2Cs

The phytohormone abscisic acid (ABA) regulates physiologically important developmental processes and stress responses. Previously, we reported on Arabidopsis (Arabidopsis thaliana) L. Heynh. ahg mutants, which are hypersensitive to ABA during germination and early growth. Among them, ABA-hypersensitive germination3 (ahg3) showed the strongest ABA hypersensitivity. In this study, we found that the AHG3 gene is identical to AtPP2CA, which encodes a protein phosphatase 2C (PP2C). Although AtPP2CA has been reported to be involved in the ABA response on the basis of results obtained by reverse-genetics approaches, its physiological relevance in the ABA response has not been clarified yet. We demonstrate in vitro and in vivo that the ahg3-1 missense mutation causes the loss of PP2C activity, providing concrete confirmation that this PP2C functions as a negative regulator in ABA signaling. Furthermore, we compared the effects of disruption mutations of eight structurally related PP2C genes of Arabidopsis, including ABI1, ABI2, HAB1, and HAB2, and found that the disruptant mutant of AHG3/AtPP2CA had the strongest ABA hypersensitivity during germination, but it did not display any significant phenotypes in adult plants. Northern-blot analysis clearly showed that AHG3/AtPP2CA is the most active among those PP2C genes in seeds. These results suggest that AHG3/AtPP2CA plays a major role among PP2Cs in the ABA response in seeds and that the functions of those PP2Cs overlap, but their unique tissue- or development-specific expression confers distinct and indispensable physiological functions in the ABA response.     

Delayed fluorescence observed in the nanosecond time region at 77 K originates directly from the photosystem II reaction center

The excited-state dynamics of delayed fluorescence in photosystem (PS) II at 77 K were studied by time-resolved fluorescence spectroscopy and decay analysis on three samples with different antenna sizes: PS II particles and the PS II reaction center from spinach, and the PS II core complexes from Synechocystis sp. PCC 6803. Delayed fluorescence in the nanosecond time region originated from the 683-nm component in all three samples, even though a slight variation in lifetimes was detected from 15 to 25 ns. The relative amplitude of the delayed fluorescence was higher when the antenna size was smaller. Energy transfer from the 683-nm pigment responsible for delayed fluorescence to antenna pigment(s) at a lower energy level was not observed in any of the samples examined. This indicated that the excited state generated by charge recombination was not shared with antenna pigments under the low-temperature condition, and that delayed fluorescence originates directly from the PS II reaction center, either from chlorophyll a_D1 or P680. Supplemental data on delayed fluorescence from spinach PS I complexes are included.     

Mg-chelatase H subunit affects ABA signaling in stomatal guard cells,but is not an ABA receptor in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

Mg-chelatase H subunit (CHLH) is a multifunctional protein involved in chlorophyll synthesis, plastid-to-nucleus retrograde signaling, and ABA perception. However, whether CHLH acts as an actual ABA receptor remains controversial. Here we present evidence that CHLH affects ABA signaling in stomatal guard cells but is not itself an ABA receptor. We screened ethyl methanesulfonate-treated Arabidopsis thaliana plants with a focus on stomatal aperture-dependent water loss in detached leaves and isolated a rapid transpiration in detached leaves 1 (rtl1) mutant that we identified as a novel missense mutant of CHLH. The rtl1 and CHLH RNAi plants showed phenotypes in which stomatal movements were insensitive to ABA, while the rtl1 phenotype showed normal sensitivity to ABA with respect to seed germination and root growth. ABA-binding analyses using ³H-labeled ABA revealed that recombinant CHLH did not bind ABA, but recombinant pyrabactin resistance 1, a reliable ABA receptor used as a control, showed specific binding. Moreover, we found that the rtl1 mutant showed ABA-induced stomatal closure when a high concentration of extracellular Ca²⁺ was present and that a knockout mutant of Mg-chelatase I subunit (chli1) showed the same ABA-insensitive phenotype as rtl1. These results suggest that the Mg-chelatase complex as a whole affects the ABA-signaling pathway for stomatal movements.