Serendipita indica mitigates drought-triggered oxidative burst in trifoliate orange by stimulating antioxidant defense systems.

Soil drought is detrimental to plant growth worldwide, particularly by triggering reactive oxygen species (ROS) burst. Serendipita indica (Si), a culturable root-associated endophytic fungus, can assist host plants in dealing with abiotic stresses; however, it is unknown whether and how Si impacts the drought tolerance of citrus plants. To unravel the effects and roles of Si on drought-stressed plants, trifoliate orange (Poncirus trifoliata L. Raf.; a citrus rootstock) seedlings were inoculated with Si and exposed to soil drought, and growth, gas exchange, ROS levels, antioxidant defense systems, and expression of genes encoding antioxidant enzymes and fatty acid desaturases in leaves were measured. Soil drought suppressed plant biomass, whereas Si inoculation significantly increased plant biomass (10.29%-22.47%) and shoot/root ratio (21.78%-24.68%) under ample water and drought conditions, accompanied by improved net photosynthetic rate (105.71%), water use efficiency (115.29%), chlorophyll index (55.34%), and nitrogen balance index (63.84%) by Si inoculation under soil drought. Soil drought triggered an increase in leaf hydrogen peroxide and superoxide anion levels, while Si inoculation significantly reduced these ROS levels under soil drought, resulting in lower membrane lipid peroxidation with respect to malondialdehyde changes. Furthermore, Si-inoculated seedlings under soil drought had distinctly higher levels of ascorbate and glutathione, as well as catalase, peroxidase, and glutathione peroxidase activities, compared with no-Si-inoculated seedlings. Si inoculation increased the expression of leaf PtFAD2, PtFAD6, PtΔ9, PtΔ15, PtFe-SOD, PtCu/Zn-SOD, PtPOD, and PtCAT1 genes under both ample water and soil drought conditions. Overall, Si-inoculated trifoliate orange plants maintained a low oxidative burst in leaves under drought, which was associated with stimulation of antioxidant defense systems. Therefore, Si has great potential as a biostimulant in enhancing drought tolerance in plants, particularly citrus.

An endophytic fungus, Piriformospora indica, enhances drought tolerance of trifoliate orange by modulating the antioxidant defense system and composition of fatty acids.

A cultivable endophytic fungus, Piriformospora indica, improves growth and enhances stress tolerance of host plants, but the underlying mechanisms remain unknown. We hypothesized that P. indica enhanced the drought tolerance of the host by regulating the antioxidant defense system and composition of fatty acids. Trifoliate orange (Poncirus trifoliata) seedlings were inoculated with P. indica under ample water and drought stress to analyze the change in plant growth, reactive oxygen species (ROS) levels, antioxidant enzyme activities, non-enzymatic antioxidant concentrations, fatty acid compositions, and expressions of both antioxidant enzyme genes and fatty acid desaturase (FAD) genes. The 9-week soil water deficit significantly increased the colonization of P. indica to roots, and P. indica promoted the increase of shoot biomass under drought. Soil drought triggered an elevation of hydrogen peroxide in roots, while the inoculated plants had lower levels of ROS (hydrogen peroxide and superoxide anion radicals) and lower degree of membrane lipid peroxidation (based on malondialdehyde levels) under drought. Drought treatment also elevated ascorbic acid and glutathione concentrations, and the elevation was further amplified after P. indica inoculation. Inoculated plants under drought also recorded significantly higher iron-superoxide dismutase (Fe-SOD), manganese-superoxide dismutase (Mn-SOD), peroxidases, catalase, glutathione reductase and ascorbate peroxidase activities, accompanied by up-regulation of PtFe-SOD and PtCu/Zn-SOD expressions. Inoculation with P. indica significantly increased total saturated fatty acids (e.g., C6:0, C15:0, C16:0, C23:0 and C24:0) concentration and reduced total unsaturated fatty acids (e.g., C18:1N9C, C18:2N6, C18:3N3, C18:1N12 and C19:1N9T) concentrations, leading to a decrease in the unsaturation index of fatty acids, which may be associated with the up-regulation of PtFAD2 and PtFAD6 and down-regulation of PtΔ9. It was concluded that the colonization of P. indica can activate enzyme and non-enzyme defense systems and regulate the composition of fatty acids under drought, thus alleviating the oxidative damage to the host caused by drought.

Endophytic fungus Serendipita indica accelerates ascorbate-glutathione cycle of white clover in response to water stress.

Ascorbate-glutathione cycle is an important pathway for plants to scavenge reactive oxygen species (ROS) under environmental stress conditions. The objective of this study was to investigate the effects of the endophytic fungus Serendipita indica on biomass, chlorophyll concent, ROS levels, antioxidant enzyme activities, and ascorbate-glutathione cycle in white clover under ample water and water stress conditions. The results showed that 46 days of soil water stress distinctly promoted root colonization by S. indica. Under water stress, S. indica inoculation significantly promoted shoot and root biomass, total chlorophyll content, and activities of superoxide dismutases (SOD; e.g., Fe-SOD and Cu/Zn-SOD) and peroxidase in roots, coupled with a decrease in malondialdehyde content in roots. In the ascorbate-glutathione cycle of roots, S. indica also significantly increased the activity of ascorbate peroxidase and glutathione reductase activities in water-stressed white clover, along with the increase in reduced ascorbic acid and reduced/oxidized glutathione contents, thus accelerating the ascorbate-glutathione cycle in inoculated plants to scavenge more ROS (e.g., hydrogen peroxide). As a result, S. indica enhanced the tolerance of white clover in response to water stress by enhancing antioxidant enzyme activities and accelerating the ascorbate-glutathione cycle.

Effects of realgar nanoparticles on B cell non-Hodgkin's lymphoma Raji cells in vitro / 中国药理学通报

Aim To observe the effects of realgar nano-particles on B cell non-Hodgkin's lymphoma Raji cells in vitro. Methods Realgar nanoparticles and crude realgar particles were characterized with a laser particle size analyzer, a transmission electron microscopy (TEM)and an atomic force microscopy(AFM). The morphological changes of proliferation of Raji cells brought about by the use of realgar naoparticles and crude realgar particles were observed with a light mi-croscope. The membrane changes of Raji cells treated with realgar naoparticles and crude realgar particles were observed with AFM. The ultrastructures of Raji cells were observed with TEM. The inhibitory effects of Raji cells treated with realgar naoparticles and crude realgar particles were measured with MTT. The nuclear apoptosis morphologies of Raji cells were observed with fluorescence microscopy. The apoptosis rates and the cell cycle distributions of Raji cells treated with real-gars were measured with flow cytometry. Results The size of realgar nanoparticles and crude realgar particles was (79 ± 8)nm and (1. 89 ± 0. 2)μm,respectively. Light microscopy showed that realgar nanoparticles could inhibit the aggregation growth of Raji cells. AFM showed that Raji cells treated with realgar nanoparticle became shrank, had smaller volume and lost the growth state of stretching out. Raji cells treated with crude realgars did not change significantly. TEM showed Raji cells treated with realgar nanoparticle had damaged subcellular organelles and mitochondria with increased vacuoles. The Raji cells treated with crude realgar did not change significantly. MTT assay showed that when treated with the final concentration of 50 mg ·L - 1 of realgar nanoparticle for 24 h,the cell survival rate of Raji cells was (40 ± 2)% . When treated with the same concentration of crude realgar,its survival rate was (65 ± 3)% . When treated with 50 mg·L - 1 of realgar nanoparticle for 48 h,its survival rate was only 10 % ,and when treated with crude realgar ,its survival rate was (42 ± 2 )% . Fluorescence micro-scope indicated that the Raji cells treated with realgar nanoparticle had obvious nuclear apoptosis,which was not obvious in crude realgar group. Flow cytometry showed that the total apoptosis rate of Raji cells in-duced by realgar nanoparticles and by crude realgar was 11. 14%,15. 9%,respectively. Compared with those treated with crude realgar,the Raji cells treated with realgar nanoparticles presented a significantly higher ratio cell distribution in G1 phase and an obvious decreased ratio in S phase. Conclusion Compared with crude realgar particles,the same dose of realgar nanoparticles can significantly inhibit the proliferation of Raji cells,destroy their sub-cellular structure,and induce the cell apoptosis of Raji cells.

[The Effect of Chronic Intermittent Hypoxia on Cognitive Function and Prefrontal Cortex Neurons in Rats].

OBJECTIVE: To determine the effect of chronic intermittent hypoxia on cognitive function and prefrontal cortex neurons in rats. METHODS: 48 adult male Wistar rats were randomly divided into two groups: control group and 50 mL/L intermittent hypoxia group (50 mL/L CIH). Rats in the CIH group were placed in the low oxygen tank, simulating intermittent hypoxia environment. At 7 d, 14 d, 21 d, and 28 d, the learning and memory ability of the rats was assessed with the Morris water maze (MWM) test; the expressions of cysteinyl aspartate specific protease (caspase)-8 protein in their prefrontal cortex were determined using Western blot method; the apoptosis of neurons was detected by the TdT mediated UTP nick end labeling (TUNEL) method. RESULTS: Compared with the controls, the CIH rats had significantly prolonged escape latency at 14 d, 21 d, and 28 d (P<0. 05) and decreased target quadrant time (P<0. 05). The prolonged escape latency increased and target quadrant time shortened with length of exposure to hypoxia (P<0. 05). Compared with controls, the CIH rats had gradually increased caspase-8 in their frontal cortex neurons, peaked at 28 d (P<0. 05). The CIH rats showed obvious structural damage and reduced neuron density in their frontal cortex neurons. They had higher levels of nerve cell apoptosis (P<0. 05), with apoptosis index increasing with length of exposure to hypoxia (P<0. 05). CONCLUSION: Severe chronic intermittent hypoxia can lead to pathological changes of frontal,cortex of rats, possibly

A catalyst-free one-pot construction of skeletons of 5-methoxyseselin and alloxanthoxyletin in water.

In refluxing water and without an additional catalyst, electron-rich phenols could react with alkynoic acids or alkynoates to provide coumarin structures. The skeletons of two natural pyranocoumarins, 5-methoxyseselin and alloxanthoxyletin, could be constructed (total yield up to 76%) in an aqueous multicomponent reaction in which isoprenyl acetate, propiolic acid, and phloroglucinol were simply mixed and refluxed in water.

[UV spectroscopy coupled with partial least squares to determine the enantiomeric composition in chiral drugs].

In the present study, sucrose was used as a chiral selector to detect the molar fraction of R-metalaxyl and S-ibuprofen due to the UV spectral difference caused by the interaction of the R- and S-isomer with sucrose. The quantitative model of the molar fraction of R-metalaxyl was established by partial least squares (PLS) regression and the robustness of the models was evaluated by 6 independent validation samples. The determination coefficient R2 and the standard error of calibration set (SEC) was 99.98% and 0.003 respectively. The correlation coefficient of estimated value and specified value, the standard error and the relative standard deviation (RSD) of the independent validation samples was 0.999 8, 0.000 4 and 0.054% respectively. The quantitative models of the molar fraction of S-ibuprofen were established by PLS and the robustness of models was evaluated. The determination coefficient R2 and the standard error of calibration set (SEC) was 99.82% and 0.007 respectively. The correlation coefficient of estimated value and specified value of the independent validation samples was 0.998 1. The standard error of prediction (SEP) was 0.002 and the relative standard deviation (RSD) was 0.2%. The result demonstrates that sucrose is an ideal chiral selector for building a stable regression model to determine the enantiomeric composition.

Desymmetrization of meso-1,2-diols via the dynamic kinetic resolution of its monodichloroacetates.

Enantioselective acylation catalyzed by the thioamide modified 1-methylhistidine methyl ester 1 in combination with DABCO-mediated racemization of the substrate led to the efficient dynamic kinetic resolution of meso-1,2-diol monodichloroacetates. In this way, cyclic and acyclic meso-1,2-diol monodichloroacetates can be transformed to the enantiomerically enriched (1S,2R)-heterosubstituted diol diesters which are stable in enantiomerically pure form and can be readily used for further organic transformations.