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Gifu-shi, Japan

Gifu Woman's University is a four-year private university in the city of Gifu, Gifu Prefecture, Japan, and founded in 1968. Its name is abbreviated as Gifu Joshi Dai or G Wikipedia.

Nomura H.,Gifu Womens University | Shiina T.,Kyoto Prefectural University
Molecular Plant | Year: 2014

Recent studies have demonstrated that chloroplasts and mitochondria evoke specific Ca2+ signals in response to biotic and abiotic stresses in a stress-dependent manner. The identification of Ca2+ transporters and Ca2+ signaling molecules in chloroplasts and mitochondria implies that they play roles in controlling not only intra-organellar functions, but also extra-organellar processes such as plant immunity and stress responses. It appears that organellar Ca2+ signaling might be more important to plant cell functions than previously thought. This review briefly summarizes what is known about the molecular basis of Ca2+ signaling in plant mitochondria and chloroplasts. © The Author 2014.

Tatsumi H.,Nagoya University | Toyota M.,University of Wisconsin - Madison | Toyota M.,Japan Science and Technology Agency | Furuichi T.,Gifu Womens University | Sokabe M.,Nagoya University
Plant Signaling and Behavior | Year: 2014

Gravity influences the growth direction of higher plants.Changes in the gravity vector (gravistimulation) immediately promote the increase in the cytoplasmic free calcium ion concentration ([Ca2+]c) in Arabidopsis (Arabidopsis thaliana) seedlings.When the seedlings are gravistimulated by reorientation at 180°, a transient two peaked (biphasic) [Ca2+]c-increase arises in their hypocotyl and petioles.Parabolic flights (PFs) can generate a variety of gravity-stimuli, and enables us to measure gravity-induced [Ca2+]c-increases without specimen rotation, which demonstrate that Arabidopsis seedlings possess a rapid gravity-sensing mechanism linearly transducing a wide range of gravitational changes into Ca2+ signals on a sub-second timescale.Hypergravity by centrifugation (20 g or 300 g) also induces similar transient [Ca2+]c-increases.In this review, we propose models for possible cellular processes of the garavi-stimulus-induced [Ca2+]c-increase, and evaluate those by examining whether the model fits well with the kinetic parameters derived from the [Ca2+]c-increases obtained by applying gravistimulus with different amplitudes and time sequences. © 2014 Landes Bioscience.

Tatsumi H.,Nagoya University | Furuichi T.,EcoTopia Science Institute | Furuichi T.,Gifu Womens University | Nakano M.,Tokyo Gakugei University | And 5 more authors.
Plant Biology | Year: 2014

Mechanosensitive (MS) channels are expressed in a variety of cells. The molecular and biophysical mechanism involved in the regulation of MS channel activities is a central interest in basic biology. MS channels are thought to play crucial roles in gravity sensing in plant cells. To date, two mechanisms have been proposed for MS channel activation. One is that tension development in the lipid bilayer directly activates MS channels. The second mechanism proposes that the cytoskeleton is involved in the channel activation, because MS channel activities are modulated by pharmacological treatments that affect the cytoskeleton. We tested whether tension in the cytoskeleton activates MS channels. Mammalian endothelial cells were microinjected with phalloidin-conjugated beads, which bound to stress fibres, and a traction force to the actin cytoskeleton was applied by dragging the beads with optical tweezers. MS channels were activated when the force was applied, demonstrating that a sub-pN force to the actin filaments activates a single MS channel. Plants may use a similar molecular mechanism in gravity sensing, since the cytoplasmic Ca2+ concentration increase induced by changes in the gravity vector was attenuated by potential MS channel inhibitors, and by actin-disrupting drugs. These results support the idea that the tension increase in actin filaments by gravity-dependent sedimentation of amyloplasts activates MS Ca2+-permeable channels, which can be the molecular mechanism of a Ca2+ concentration increase through gravistimulation. We review recent progress in the study of tension sensing by actin filaments and MS channels using advanced biophysical methods, and discuss their possible roles in gravisensing. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

Iida H.,Tokyo Gakugei University | Furuichi T.,EcoTopia Science Institute | Furuichi T.,Gifu Womens University | Nakano M.,Tokyo Gakugei University | And 4 more authors.
Plant Biology | Year: 2014

The mechano-sensitive channels of plants may sense increases in tension induced by mechanical stimuli, such as touch, wind and turgor pressure, and a gravitational stimulus. Recent studies have identified plant homologues of the bacterial mechano-sensitive channel MscS, which is gated by membrane tension and reduces intracellular osmolality by releasing small osmolytes from bacterial cells. However, the physiological roles of these homologues have not yet been clearly elucidated, and only two of them have been shown to be involved in the protection of osmotically stressed plastids in Arabidopsis thaliana. We identified another group of candidates for mechano-sensitive channels in Arabidopsis, named MCA1 and MCA2, whose homologues are exclusively found in plant genomes. MCA1 and MCA2 are composed of 421 and 416 amino acid residues, respectively, share 73% homology in their amino acid sequences, and are not homologous to any known ion channels or transporters. Our structural study revealed that the N-terminal region (one to 173 amino acids) of both proteins was necessary and sufficient for Ca2+ influx activity. Interestingly, this region had one putative transmembrane segment containing an Asp residue whose substitution mutation abolished this activity. Our physiological study suggested that MCA1 expressed at the root tip was required for sensing the hardness of the agar medium or soil. In addition, MCA1 and MCA2 were shown to be responsible for hypo-osmotic shock-induced increases in [Ca2+]cyt. Thus, both proteins appear to be involved in the process of sensing mechanical stresses. We discussed the possible role of both proteins in sensing mechanical and gravitational stimuli. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

Yamamoto K.,Gifu University | Isa Y.,Gifu Womens University | Nakagawa T.,Gifu University | Hayakawa T.,Gifu University
Bioscience, Biotechnology and Biochemistry | Year: 2012

Vitamin B6 (B6) deficiency affects homocysteine metabolism, and this leads to hyperhomocysteinemia. In this study, we examined i) the effects of B6-deficiency and graduated levels of dietary methionine on homocysteine metabolism, and ii) the effects of fortified folate on homocysteine metabolism. In experiment 1, Wistar male rats were fed a control or a B6-deficient diet supplemented with L-methionine at a level of 3, 6, or 9 g/kg of diet for 5 weeks. The resulting plasma homocysteine levels in the B6-deficient groups increased in relation to the increase in dietary methionine level. Next, in experiment 2, rats were fed a control, B 6-deficient, or folate enriched (10mg pteroylmonoglutamic acid/kg) B6-deficient diet containing L-methionine at 9g/kg for 5 weeks. Although the B6-deficient diet induced hyperhomocysteinemia, folate fortification ameliorated the plasma homocysteine concentration. Overall, our results indicate that folate fortification ameliorates the hyperhomocysteinemia induced by B6 deficiency and supplemental methionine intake.

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