Recently, a variety of ultraviolet-driven photochemically active catalysts designated as photocat... more Recently, a variety of ultraviolet-driven photochemically active catalysts designated as photocatalysts coated with titanium dioxide (TiO2) has been developed and applied for hygiene and antimicrobial purposes. The likely mechanism of such catalysts involves the generation of reactive oxygen species (ROS) on the surface of the catalyst as expected (not fully proven) from the previously proposed models.1 However, no attempt to confer long-lasting chemical properties to the waters (e.g., preparation of waters rich in ROS) has been reported, despite of the increasing demands for the use of photocatalysts in various environments including the use in aqueous phase. In the present study, novel water conditioning photocatalytic apparatus (exPCAW-1, K2R Inc., Kitakyushu, Japan) equipped with sheets of TiO2-coated photocatalytic fibers were applied for The preparation of ROS-containing water. We attempted to detect the generation of superoxide anion and hydroxyl radical as the key members of ROS generated in the water circulated in exPCAW-1 by using the superoxide anion-specific chemiluminescent probe Cypridina luciferin analog (CLA), and a spin trapping agent, DMPO (5, 5-Dimethyl-1-pyrroline-N-Oxide) that readily forms an adduct with hydroxyl radical. Some other factors such as the effects of pH on the superoxide generation were also studied.
A water conditioning photocatalytic apparatus (exPCAW1.2, K2R Inc., Kitakyushu, Japan) equipped w... more A water conditioning photocatalytic apparatus (exPCAW1.2, K2R Inc., Kitakyushu, Japan) equipped with the sheets of TiO2-coated photocatalytic fibers were applied for preparation of reactive water rich in reactive oxygen species (ROS). Interestingly, the conditioned water has unusual long-lasting ROS-generating nature. One likely use of the conditioned water is controlling of the biological responses of living plant cells since it has been well documented that various physiological and biochemical events during the plant life cycle, such as germination of seeds, induction of defense mechanism against pathogenic microorganisms and adaptation to severe environments, are controlled by ROS. To assess if the level of ROS produced in the conditioned water attained and remained at the level actively inducing the responses of living plant cells, we tested the responses of tobacco cell suspension culture (BY-2, expressing aequorin gene) to addition of the water treated with exPCAW1.2. Presence of superoxide anion in the conditioned water-treated cell suspension culture was detected with the chemiluminescence of Cypridina luciferin analog (CLA) and the movement of calcium ion (mediated with ROS-responsive calcium channels) across the plasma membrane was assessed with aequorin luminescence in the presence and absence of specific inhibitors.
Al(3+) toxicity in growing plants is considered as one of the major factors limiting the producti... more Al(3+) toxicity in growing plants is considered as one of the major factors limiting the production of crops on acidic soils worldwide. In the last 15 years, it has been proposed that Al(3+) toxicity are mediated with distortion of the cellular signaling mechanisms such as calcium signaling pathways, and production of cytotoxic reactive oxygen species (ROS) causing oxidative damages. On the other hand, zinc is normally present in plants at high concentrations and its deficiency is one of the most widespread micronutrient deficiencies in plants. Earlier studies suggested that lack of zinc often results in ROS-mediated oxidative damage to plant cells. Previously, inhibitory action of Zn(2+) against lanthanide-induced superoxide generation in tobacco cells have been reported, suggesting that Zn(2+) interferes with the cation-induced ROS production via stimulation of NADPH oxidase. In the present study, the effect of Zn(2+) on Al(3+)-induced superoxide generation in the cell suspension ...
Zeitschrift für Naturforschung. C, Journal of biosciences
Effects of naturally existing rare-earth metals (REMs; atomic numbers, 39, 57-60, 62-71; Y, La, C... more Effects of naturally existing rare-earth metals (REMs; atomic numbers, 39, 57-60, 62-71; Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), added as chloride salts, on Ca2+ influx induced by two different stimuli, namely hypoosmotic shock and hydrogen peroxide, were examined in a suspension-cultured transgenic cell line of BY-2 tobacco cells expressing aequorin, a Ca(2+)-sensitive luminescent protein in cytosol. Most REM salts used here showed inhibitory effect against Ca2+ influx. Especially NdCl3, SmCl3, EuCl3, GdCl3 and TbCl3 showed the most robust inhibitory action. In contrast, LuCl3, YbCl3, ErCl3 and YCl3 were shown to be poor inhibitors of Ca2+ influx. Since REMs tested here form a sequential range of ionic radii from 86.1 to 103.2 pm and the optimal range of ionic radii required for blocking the flux of Ca2+ was determined for each stimulus. The hydrogen peroxide-induced Ca2+ influx was optimally blocked by REMs with a broad range of ionic radii (93.8-101 pm) whi...
Biochemical and Biophysical Research Communications, 2005
Previously, effect of Al ions on calcium signaling was assessed in tobacco cells expressing a Ca ... more Previously, effect of Al ions on calcium signaling was assessed in tobacco cells expressing a Ca 2+-monitoring luminescent protein, aequorin and a newly isolated putative plant Ca 2+ channel protein from Arabidopsis thaliana, AtTPC1 (two-pore channel 1). TPC1 channels were shown to be the only channel known to be sensitive to Al and they are responsive to reactive oxygen species and cryptogein, a fungal elicitor protein. Thus, involvement of TPC1 channels in calcium signaling leading to development of plant defense mechanism has been suggested. Then, the use of Al as a specific inhibitor of TPC1-type plant calcium channels has been proposed. Here, using transgenic tobacco BY-2 cells expressing aequorin, we report on the evidence in support of the involvement of Al-sensitive signaling pathway requiring TPC1-type channel-dependent Ca 2+ influx in response to salicylic acid, a key plant defense-inducing agent, but not to an elicitor prepared from the cell wall of rice blast disease fungus Magnaporthe grisea. In addition, involvement of Al-sensitive Ca 2+ channels in response to cold shock was also tested. The data suggested that the elicitor used here induces the Ca 2+ influx via Al-insensitive path, while salicylic acid and cold-shock-stimulate the influx of Ca 2+ via Al-sensitive mechanism.
A variety of ciliated and flagellated protozoan species have been used as bio-indicators for eco-... more A variety of ciliated and flagellated protozoan species have been used as bio-indicators for eco- toxic impacts of chemicals especially in aquatic environments such as rivers, ponds, lakes and wetlands. It has not been widely concerned that quality of water drastically alters the toxic actions of various chemicals against various aquatic organisms including fishes, algae, and other microbes. Previously, we
Generation of reactive oxygen species is useful for various medical, engineering and agricultural... more Generation of reactive oxygen species is useful for various medical, engineering and agricultural purposes. These include clinical modulation of immunological mechanism, enhanced degradation of organic compounds released to the environments, removal of microorganisms for the hygienic purpose, and agricultural pest control; both directly acting against pathogenic microorganisms and indirectly via stimulation of plant defense mechanism represented by systemic acquired resistance and hypersensitive response. By aiming to develop a novel classes of artificial redox-active biocatalysts involved in production and/or removal of superoxide anion radicals, recent attempts for understanding and modification of natural catalytic proteins and functional DNA sequences of mammalian and plant origins are covered in this review article.
Medaka fish (Oryzias latipes red-orange variety) habitable in both fresh and brackish waters, wer... more Medaka fish (Oryzias latipes red-orange variety) habitable in both fresh and brackish waters, were used to determine the toxicities of fire-fighting foams (FFFs) in three different waters, namely ultra-pure water (UPW), local tap water (TW), and brackish water (BW) equivalent to 25% (v/v) seawater. In the presence of FFFs, LC50 at 12, 24, and 48 h were determined. In all waters tested, the LC50 for commercial FFFs ranged from 2 to 200 ppm (w/v). Three commercial FFFs showed higher toxicity in TW and BW compared to the toxicity in UPW, while one commercial FFF showed highest toxicity in UPW. The impact of newly developed soap-based FFF was also assessed. The LC50 values obtained for the soap formula was around 55-65 ppm in UPW. Toxicity of soap FFF fell into much safer levels in TW (200-400 ppm) and BW (640-4000 ppm), possibly due to the cation-dependent detoxification. This is a successful demonstration of the water-dependent changes in toxicity of putative pollutants, using a single organism habitable in diverse water conditions. This work may help designing the eco-toxicity assays dealing with chemical pollutants in diversified aquatic environments.
Recently, a variety of ultraviolet-driven photochemically active catalysts designated as photocat... more Recently, a variety of ultraviolet-driven photochemically active catalysts designated as photocatalysts coated with titanium dioxide (TiO2) has been developed and applied for hygiene and antimicrobial purposes. The likely mechanism of such catalysts involves the generation of reactive oxygen species (ROS) on the surface of the catalyst as expected (not fully proven) from the previously proposed models.1 However, no attempt to confer long-lasting chemical properties to the waters (e.g., preparation of waters rich in ROS) has been reported, despite of the increasing demands for the use of photocatalysts in various environments including the use in aqueous phase. In the present study, novel water conditioning photocatalytic apparatus (exPCAW-1, K2R Inc., Kitakyushu, Japan) equipped with sheets of TiO2-coated photocatalytic fibers were applied for The preparation of ROS-containing water. We attempted to detect the generation of superoxide anion and hydroxyl radical as the key members of ROS generated in the water circulated in exPCAW-1 by using the superoxide anion-specific chemiluminescent probe Cypridina luciferin analog (CLA), and a spin trapping agent, DMPO (5, 5-Dimethyl-1-pyrroline-N-Oxide) that readily forms an adduct with hydroxyl radical. Some other factors such as the effects of pH on the superoxide generation were also studied.
A water conditioning photocatalytic apparatus (exPCAW1.2, K2R Inc., Kitakyushu, Japan) equipped w... more A water conditioning photocatalytic apparatus (exPCAW1.2, K2R Inc., Kitakyushu, Japan) equipped with the sheets of TiO2-coated photocatalytic fibers were applied for preparation of reactive water rich in reactive oxygen species (ROS). Interestingly, the conditioned water has unusual long-lasting ROS-generating nature. One likely use of the conditioned water is controlling of the biological responses of living plant cells since it has been well documented that various physiological and biochemical events during the plant life cycle, such as germination of seeds, induction of defense mechanism against pathogenic microorganisms and adaptation to severe environments, are controlled by ROS. To assess if the level of ROS produced in the conditioned water attained and remained at the level actively inducing the responses of living plant cells, we tested the responses of tobacco cell suspension culture (BY-2, expressing aequorin gene) to addition of the water treated with exPCAW1.2. Presence of superoxide anion in the conditioned water-treated cell suspension culture was detected with the chemiluminescence of Cypridina luciferin analog (CLA) and the movement of calcium ion (mediated with ROS-responsive calcium channels) across the plasma membrane was assessed with aequorin luminescence in the presence and absence of specific inhibitors.
Al(3+) toxicity in growing plants is considered as one of the major factors limiting the producti... more Al(3+) toxicity in growing plants is considered as one of the major factors limiting the production of crops on acidic soils worldwide. In the last 15 years, it has been proposed that Al(3+) toxicity are mediated with distortion of the cellular signaling mechanisms such as calcium signaling pathways, and production of cytotoxic reactive oxygen species (ROS) causing oxidative damages. On the other hand, zinc is normally present in plants at high concentrations and its deficiency is one of the most widespread micronutrient deficiencies in plants. Earlier studies suggested that lack of zinc often results in ROS-mediated oxidative damage to plant cells. Previously, inhibitory action of Zn(2+) against lanthanide-induced superoxide generation in tobacco cells have been reported, suggesting that Zn(2+) interferes with the cation-induced ROS production via stimulation of NADPH oxidase. In the present study, the effect of Zn(2+) on Al(3+)-induced superoxide generation in the cell suspension ...
Zeitschrift für Naturforschung. C, Journal of biosciences
Effects of naturally existing rare-earth metals (REMs; atomic numbers, 39, 57-60, 62-71; Y, La, C... more Effects of naturally existing rare-earth metals (REMs; atomic numbers, 39, 57-60, 62-71; Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), added as chloride salts, on Ca2+ influx induced by two different stimuli, namely hypoosmotic shock and hydrogen peroxide, were examined in a suspension-cultured transgenic cell line of BY-2 tobacco cells expressing aequorin, a Ca(2+)-sensitive luminescent protein in cytosol. Most REM salts used here showed inhibitory effect against Ca2+ influx. Especially NdCl3, SmCl3, EuCl3, GdCl3 and TbCl3 showed the most robust inhibitory action. In contrast, LuCl3, YbCl3, ErCl3 and YCl3 were shown to be poor inhibitors of Ca2+ influx. Since REMs tested here form a sequential range of ionic radii from 86.1 to 103.2 pm and the optimal range of ionic radii required for blocking the flux of Ca2+ was determined for each stimulus. The hydrogen peroxide-induced Ca2+ influx was optimally blocked by REMs with a broad range of ionic radii (93.8-101 pm) whi...
Biochemical and Biophysical Research Communications, 2005
Previously, effect of Al ions on calcium signaling was assessed in tobacco cells expressing a Ca ... more Previously, effect of Al ions on calcium signaling was assessed in tobacco cells expressing a Ca 2+-monitoring luminescent protein, aequorin and a newly isolated putative plant Ca 2+ channel protein from Arabidopsis thaliana, AtTPC1 (two-pore channel 1). TPC1 channels were shown to be the only channel known to be sensitive to Al and they are responsive to reactive oxygen species and cryptogein, a fungal elicitor protein. Thus, involvement of TPC1 channels in calcium signaling leading to development of plant defense mechanism has been suggested. Then, the use of Al as a specific inhibitor of TPC1-type plant calcium channels has been proposed. Here, using transgenic tobacco BY-2 cells expressing aequorin, we report on the evidence in support of the involvement of Al-sensitive signaling pathway requiring TPC1-type channel-dependent Ca 2+ influx in response to salicylic acid, a key plant defense-inducing agent, but not to an elicitor prepared from the cell wall of rice blast disease fungus Magnaporthe grisea. In addition, involvement of Al-sensitive Ca 2+ channels in response to cold shock was also tested. The data suggested that the elicitor used here induces the Ca 2+ influx via Al-insensitive path, while salicylic acid and cold-shock-stimulate the influx of Ca 2+ via Al-sensitive mechanism.
A variety of ciliated and flagellated protozoan species have been used as bio-indicators for eco-... more A variety of ciliated and flagellated protozoan species have been used as bio-indicators for eco- toxic impacts of chemicals especially in aquatic environments such as rivers, ponds, lakes and wetlands. It has not been widely concerned that quality of water drastically alters the toxic actions of various chemicals against various aquatic organisms including fishes, algae, and other microbes. Previously, we
Generation of reactive oxygen species is useful for various medical, engineering and agricultural... more Generation of reactive oxygen species is useful for various medical, engineering and agricultural purposes. These include clinical modulation of immunological mechanism, enhanced degradation of organic compounds released to the environments, removal of microorganisms for the hygienic purpose, and agricultural pest control; both directly acting against pathogenic microorganisms and indirectly via stimulation of plant defense mechanism represented by systemic acquired resistance and hypersensitive response. By aiming to develop a novel classes of artificial redox-active biocatalysts involved in production and/or removal of superoxide anion radicals, recent attempts for understanding and modification of natural catalytic proteins and functional DNA sequences of mammalian and plant origins are covered in this review article.
Medaka fish (Oryzias latipes red-orange variety) habitable in both fresh and brackish waters, wer... more Medaka fish (Oryzias latipes red-orange variety) habitable in both fresh and brackish waters, were used to determine the toxicities of fire-fighting foams (FFFs) in three different waters, namely ultra-pure water (UPW), local tap water (TW), and brackish water (BW) equivalent to 25% (v/v) seawater. In the presence of FFFs, LC50 at 12, 24, and 48 h were determined. In all waters tested, the LC50 for commercial FFFs ranged from 2 to 200 ppm (w/v). Three commercial FFFs showed higher toxicity in TW and BW compared to the toxicity in UPW, while one commercial FFF showed highest toxicity in UPW. The impact of newly developed soap-based FFF was also assessed. The LC50 values obtained for the soap formula was around 55-65 ppm in UPW. Toxicity of soap FFF fell into much safer levels in TW (200-400 ppm) and BW (640-4000 ppm), possibly due to the cation-dependent detoxification. This is a successful demonstration of the water-dependent changes in toxicity of putative pollutants, using a single organism habitable in diverse water conditions. This work may help designing the eco-toxicity assays dealing with chemical pollutants in diversified aquatic environments.
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