Nutrient content and resorption efficiency of leaves of broad-leaved trees along altitudes in Wuyi Mountains, China.

To reveal the variation of leaf nutrient utilization strategies with altitude gradient in subtropical mountain broadleaved trees, 44 species of broadleaved trees at different altitudes (1400, 1600 and 1800 m) in Wuyi Mountains were selected to measure nutrient content, stoichiometric ratio, and nutrient resorption efficiency of green and senescent leaves, and analyzed their allometric growth relationships. The results showed that nitrogen (N) and phosphorus (P) contents in green leaves were significantly higher than those in senescent leaves, which increased with the increases of altitude. The average values of phosphorus resorption efficiency (PRE) and nitrogen resorption efficiency (NRE) were 48.3% and 34.9%, respectively. PRE was significantly higher than NRE. There was no significant difference in nutrient resorption efficiency with altitude. NRE had positive isokinetic growth with and mature leaf N content at low altitude (1400 m) and negative allometry growth with senescent leaf N content at high altitude (1800 m). PRE and N and P contents of senescent leaves had negative isokinetic growth at low altitude (1400 m) and negative allometry growth at high altitudes (1600 and 1800 m). PRE-NRE allometric growth index was 0.95 at each altitude. The nutrient contents of green and senescent leaves increased with the increases of altitude, but altitude did not affect nutrient resorption efficiency. Plants preferred to re-absorbed P from senescent leaves. Nutrient resorption efficiency of leaves at high altitude affected the nutrient status of senescent leaves.

[Nitrogen and phosphorus contents and resorption efficiency of thirty broadleaved woody plants in Yangjifeng, Jiangxi, China.] / æ±Ÿè¥¿é˜³é™ å³°30ç§é˜”å¶æ ‘å¶ç‰‡æ°®ç£·å«é‡åŠå†å¸æ”¶æ•ˆçŽ‡.

Nutrient resorption is an important strategy of nutrient conservation, which reflecting the ability of plants to conserve and utilize nutrients and adapt to environment. To explore the relationship between nutrient content and nutrient resorption of broadleaved woody species of different life forms (i.e., evergreen vs. deciduous), we sampled 30 broadleaved woody species in subtropical region of China located in Yangjifeng National Nature Reserve, Jiangxi Province. The nitrogen (N) and phosphorus (P) concentrations in green and senescent leaves of each species were measured to calculate nutrient resorption efficiency. Furthermore, we analyzed the relationship of leaf nutrient concentration and resorption efficiency for the different life forms. The results showed that N and P concentrations in green leaves were significantly higher in deciduous trees than those in evergreen trees. The P concentrations of senescent leaves in deciduous woody species was significantly higher than that in evergreen woody species. There was no significant difference of N concentration in senescent leaves between evergreen and deciduous species. Nitrogen resorption efficiency (NRE) and phosphorus resorption efficiency (PRE) of the 30 broadleaved woody species were 49.6% and 50.9%, respectively. There were no significant differences between the NRE and PRE of evergreen and deciduous species. NRE and PRE negatively correlated with N and P concentrations in senescent leaves, respectively. Additionally, evergreen and deciduous species showed similar relationships between nutrient resorption efficiency and nutrient concentration in senescent leaves. The sca-ling exponent of allometric relationship between NRE and PRE was 1.18 across all the species. The nutrient resorption efficiency of all the species were affected by the nutrient status of the senesced leaves. Plants examined in this study generally re-absorbed P from senescing leaves than N.

Effect of loureirin A against Candida albicans biofilms.

Loureirin A is a major active component of Draconis sanguis, a traditional Chinese medicine. This work aimed to investigate the activity of loureirin A against Candida albicans biofilms. 2, 3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT)reduction assay and scanning electron microscopy were used to investigate the anti-biofilm effect. Minimal inhibitory concentration testing and time-kill curve assay were used to evaluate fungicidal activity. Cell surface hydrophobicity (CSH) assay and hyphal formation experiment were respectively carried out to investigate adhesion and morphological transition, two virulence traits of C. albicans. Real-time RT-PCR was used to investigate gene expression. Galleria mellonella-C. albicans and Caenorhabditis elegans-C. albicans infection models were used to evaluate the in-vivo antifungal effect. Human umbilical vein endothelial cells and C. elegans nematodes were used to evaluate the toxicity ofloureirin A. Our data indicated that loureirin A had a significant effect on inhibiting C. albicans biofilms, decreasing CSH, and suppressing hyphal formation. Consistently, loureirin A down-regulated the expression of some adhesion-related genes and hypha/biofilm-related genes. Moreover, loureirin A prolonged the survival of Galleria mellonella and Caenorhabditis elegans in C. albicans infection models and exhibited low toxicity. Collectively, loureirin A inhibits fungal biofilms, and this effect may be associated with the suppression of pathogenic traits, adhesion and hyphal formation.

Optimization of extraction and analytical protocol for mass spectrometry-based metabolomics analysis of hepatotoxicity.

Drug-induced liver injury is a clinically leading side-effect of drugs. In the present study, a liquid chromatography mass spectrometry-based metabolomics protocol was optimized for extraction and analysis of endogenous metabolites from liver tissue during hepatotoxicity. Various extraction solutions, resuspension solutions, extraction folds and dissolution methods for the supernatant were compared using the number of extracted total ions, relative response and relative extraction efficiency of targeted metabolites from liver tissue. The polar and nonpolar endogenous metabolites associated with liver injury were analyzed by hydrophilic interaction chromatography and reversed-phase liquid chromatography with UPLC-QTOFMS. The results indicated that extraction with 10-fold 50% acetonitrile in water and the supernatant diluted (1:1) with 100% acetonitrile rather than resuspension was the optimal extraction protocol. Subsequently, the optimized method was able to examine the change in metabolites in mouse liver tissue resulting from treatment with a toxic natural product, toosendanin. Taken together, the optimized extraction and analytical protocol provides high reliability and reproducibility for polar and nonpolar metabolites in liver tissue and may be suitable for metabolomics analysis of liver injury induced by drugs or chemicals.

Effect of tetrandrine against Candida albicans biofilms.

Candida albicans is the most common human fungal pathogen and has a high propensity to develop biofilms that are resistant to traditional antifungal agents. In this study, we investigated the effect of tetrandrine (TET) on growth, biofilm formation and yeast-to-hypha transition of C. albicans. We characterized the inhibitory effect of TET on hyphal growth and addressed its possible mechanism of action. Treatment of TET at a low concentration without affecting fungal growth inhibited hyphal growth in both liquid and solid Spider media. Real-time RT-PCR revealed that TET down-regulated the expression of hypha-specific genes ECE1, ALS3 and HWP1, and abrogated the induction of EFG1 and RAS1, regulators of hyphal growth. Addition of cAMP restored the normal phenotype of the SC5314 strain. These results indicate that TET may inhibit hyphal growth through the Ras1p-cAMP-PKA pathway. In vivo, at a range of concentrations from 4 mg/L to 32 mg/L, TET prolonged the survival of C. albicans-infected Caenorhabditis elegans significantly. This study provides useful information for the development of new strategies to reduce the incidence of C. albicans biofilm-associated infections.