Yeasts represent an important category of microorganisms used in biocontrol of diseases affecting postharvest fruits or vegetables, food-born microorganisms being previously reported as also having important antimicro...Yeasts represent an important category of microorganisms used in biocontrol of diseases affecting postharvest fruits or vegetables, food-born microorganisms being previously reported as also having important antimicrobial activity against human pathogens. However, the action of yeasts against species with pathogen potential for plants or humans is less understood. Our research was conducted on three Metschnikowia pulcherrima yeast strains isolated from white grapes （SG1, SG2） and cherries （CPMI） from Romania. The screening tests performed on yeast peptone glucose （YPG） medium on isolates from human infections revealed reduced antimicrobial activity with narrow inhibition zones against strain M6 （Candidaparapsilosis）. In the presence of C3 （Candida albicans）, SGI was the most active forming wider halos, followed closely by SG2, while for CPM1, no activity was described. Improvement of antagonistic action was observed especially for mixtures of SG1 with 0.5% and 1% sodium bicarbonate （NaHCO3）, respectively, 1% and 2% calcium chloride （CaCI2）. Utilization of yeast malt extract agar （YMA） medium favoring mycelium formation in cultures representing potential sensitive substrates seemed to facilitate the antimicrobial action of SG1. When compared to reference M. pulcherrima MUCL 29874, the Metschnikowia strains isolated from fruits were better antagonists probably due to variation of gene regulation or existence of adaptative responses.展开更多
The work is a study of the influence of Ca2+ (0.01 - 1 mM) on neuronal CI-, HCO3-, -ATPase complex: an enzyme that is a CI--pump which is functionally and structurally coupled to GABAA-receptors. It is found that infl...The work is a study of the influence of Ca2+ (0.01 - 1 mM) on neuronal CI-, HCO3-, -ATPase complex: an enzyme that is a CI--pump which is functionally and structurally coupled to GABAA-receptors. It is found that influence of Ca2+ on the multifunctional complex starts at concentration of 50·M and at concentration of 0.1 mM, it reduces the “basal” one and increases the CI-, HCO3-, -stimulated Mg2+-ATPase activities. GABA (0.1 - 100μM) activates the “basal” Mg2+-ATPase activity in the ab-sence of calcium. The effect of GABA on the enzyme in the presence of 0.01 ·M Ca2+ does not change. At the same time, 1 mM Ca2+eliminates the GABA effect on the “basal” Mg2+-ATPase activity. Competitive blocker of GABAA-receptors bicuculline (5 - 20 μM) in the absence of Ca2+ ions elimi-nates the stimulation of the “basal” Mg2+-ATPase by anions. When 0.25 mM Ca2+ is added to the in-cubation medium the inhibitory bicuculline effect on the enzyme does not appear. We found that 0.1 mM o-vanadate (protein tyrosine phosphatase blocker) reduces the GABA-activated ATPase activity. At the same time, 0.1 mM genistein (a protein tyrosine kinase blocker) has no effect on enzyme activity. In the presence of Ca2+ (0.25 mM), the effect of o-vanadate on the “basal” and CI-, HCO3-, -ATPase activities does not appear. It is shown for the first time that high concentrations of Ca2+prevent the action of GABAA-ergic ligands on the study ATPase. It is assumed that there is the involvement of protein kinases and protein phosphatases in the modulation of the enzyme activity by calcium. The observed effect of calcium on the ATPase may play an important role in the study of the mechanisms of epileptogenesis and seizure activity.展开更多
Surface modification of calcium bicarbonate powder with isopropyl triisostearoyl titanate (TTS) by microwave-assisted heating was studied in the present work. The features of microwave treated powder show obvious supe...Surface modification of calcium bicarbonate powder with isopropyl triisostearoyl titanate (TTS) by microwave-assisted heating was studied in the present work. The features of microwave treated powder show obvious superiority to those of powder samples treated by traditional surface modification method and of untreated calcium bicarbonate — in suspension turbidity, suction potential, contact angle with water, and mechanical properties of their composites with PVC resin.展开更多
文摘Yeasts represent an important category of microorganisms used in biocontrol of diseases affecting postharvest fruits or vegetables, food-born microorganisms being previously reported as also having important antimicrobial activity against human pathogens. However, the action of yeasts against species with pathogen potential for plants or humans is less understood. Our research was conducted on three Metschnikowia pulcherrima yeast strains isolated from white grapes （SG1, SG2） and cherries （CPMI） from Romania. The screening tests performed on yeast peptone glucose （YPG） medium on isolates from human infections revealed reduced antimicrobial activity with narrow inhibition zones against strain M6 （Candidaparapsilosis）. In the presence of C3 （Candida albicans）, SGI was the most active forming wider halos, followed closely by SG2, while for CPM1, no activity was described. Improvement of antagonistic action was observed especially for mixtures of SG1 with 0.5% and 1% sodium bicarbonate （NaHCO3）, respectively, 1% and 2% calcium chloride （CaCI2）. Utilization of yeast malt extract agar （YMA） medium favoring mycelium formation in cultures representing potential sensitive substrates seemed to facilitate the antimicrobial action of SG1. When compared to reference M. pulcherrima MUCL 29874, the Metschnikowia strains isolated from fruits were better antagonists probably due to variation of gene regulation or existence of adaptative responses.
文摘The work is a study of the influence of Ca2+ (0.01 - 1 mM) on neuronal CI-, HCO3-, -ATPase complex: an enzyme that is a CI--pump which is functionally and structurally coupled to GABAA-receptors. It is found that influence of Ca2+ on the multifunctional complex starts at concentration of 50·M and at concentration of 0.1 mM, it reduces the “basal” one and increases the CI-, HCO3-, -stimulated Mg2+-ATPase activities. GABA (0.1 - 100μM) activates the “basal” Mg2+-ATPase activity in the ab-sence of calcium. The effect of GABA on the enzyme in the presence of 0.01 ·M Ca2+ does not change. At the same time, 1 mM Ca2+eliminates the GABA effect on the “basal” Mg2+-ATPase activity. Competitive blocker of GABAA-receptors bicuculline (5 - 20 μM) in the absence of Ca2+ ions elimi-nates the stimulation of the “basal” Mg2+-ATPase by anions. When 0.25 mM Ca2+ is added to the in-cubation medium the inhibitory bicuculline effect on the enzyme does not appear. We found that 0.1 mM o-vanadate (protein tyrosine phosphatase blocker) reduces the GABA-activated ATPase activity. At the same time, 0.1 mM genistein (a protein tyrosine kinase blocker) has no effect on enzyme activity. In the presence of Ca2+ (0.25 mM), the effect of o-vanadate on the “basal” and CI-, HCO3-, -ATPase activities does not appear. It is shown for the first time that high concentrations of Ca2+prevent the action of GABAA-ergic ligands on the study ATPase. It is assumed that there is the involvement of protein kinases and protein phosphatases in the modulation of the enzyme activity by calcium. The observed effect of calcium on the ATPase may play an important role in the study of the mechanisms of epileptogenesis and seizure activity.
基金supported by the National Key Research and Development Program of China(No.2020YFC1909104)Science and Technology Major Project of Guangxi,China(No.Guike AA18242022)Key Research and Development Plan Project of Hebei Province,China(No.20374104D)。
文摘Surface modification of calcium bicarbonate powder with isopropyl triisostearoyl titanate (TTS) by microwave-assisted heating was studied in the present work. The features of microwave treated powder show obvious superiority to those of powder samples treated by traditional surface modification method and of untreated calcium bicarbonate — in suspension turbidity, suction potential, contact angle with water, and mechanical properties of their composites with PVC resin.
