Label-free affinity screening, design and synthesis of inhibitors targeting the <i>Mycobacterium tuberculosis</i> L-alanine dehydrogenase

The ability of Mycobacterium tuberculosis (Mtb) to persist in its host may enable an evolutionary advantage for drug resistant variants to emerge. A potential strategy to prevent persistence and gain drug efficacy is to directly target the activity of enzymes that are crucial for persistence. We present a method for expedited discovery and structure-based design of lead compounds by targeting the hypoxia-associated enzyme L-alanine dehydrogenase (AlaDH). Biochemical and structural analyses of AlaDH confirmed binding of nucleoside derivatives and showed a site adjacent to the nucleoside binding pocket that can confer specificity to putative inhibitors. Using a combination of dye-ligand affinity chromatography, enzyme kinetics and protein crystallographic studies, we show the development and validation of drug prototypes. Crystal structures of AlaDH-inhibitor complexes with variations at the N6 position of the adenyl-moiety of the inhibitor provide insight into the molecular basis for the specificity of these compounds. We describe a drug-designing pipeline that aims to block Mtb to proliferate upon re-oxygenation by specifically blocking NAD accessibility to AlaDH. The collective approach to drug discovery was further evaluated through in silico analyses providing additional insight into an efficient drug development strategy that can be further assessed with the incorporation of in vivo studies

Growth and saikosaponin production of the medicinal herb Bupleurum chinense DC. under different levels of nitrogen and phosphorus

Dried roots of Bupleurum spp. have been used medicinally in China for over 2000 years. The roots, which are called Bupleuri Radix, are used in at least 66% of the formulations/prescriptions in traditional Chinese medicine and Kampo medicine. Demand for Bupleuri Radix is increasing and B. chinense is one of the most important Bupleurum spp. in China. We conducted a 2-year pot experiment to investigate the effect of nitrogen (N) and phosphorus (P) fertilizer on biomass production and root saikosaponin a (SSa) and saikosaponin d (SSd) content of B. chinense. The experiment included seven combinations of N and P fertilizer. The results showed that medium levels of N and P fertilizer significantly increased the biomass and SSa content of B. chinense roots, but had no significant effect on root SSd content. The application of moderate amounts of N or P fertilizer increased total SSa and SSd yield significantly compared to the unfertilized control, but the greatest increase in total SSa and SSd yield occurred when N and P were applied together. This suggests that N and P have a synergistic effect on B. chinense growth and saikosaponin production. When high amounts of N and P fertilizer were used total SSa and SSd yields declined. This implied that there was a nutrient supply threshold for the biosynthesis of saikosaponins. Total SSa and SSd yields were greater in treatments which received only P fertilizer compared to treatments that received only N fertilizer. Our results reinforce the importance of soil testing and the application of recommended amounts N and P fertilizers for the cultivation of B. chinense. (C) 2008 Elsevier B.V. All rights reserved

Factors Influencing the Visitation and Revisitation of Urban Parks: A Case Study from Hangzhou, China

Visitors’ satisfaction and willingness to revisit urban parks are closely linked to park longevity. However, few details of this relationship have been studied. We explored the factors influencing urban park use and factors motivating revisitation in six urban parks in Hangzhou, China. Data from 600 park visitors were collected over three months using a face-to-face questionnaire. These included socio-demographic data, residential data, personal characteristics, park satisfaction, motivations for visit, and other information. A hierarchical regression model was applied to analyze the contribution of each variable to visitation by park users. Physical and mental benefits and previous positive experiences were the main factors motivating park visitation. Age and distance to the nearest park were the main factors driving park revisitation, and they were positively and negatively correlated with visitation frequency, respectively. Long-term and short-term residents, who commute by cycling or walking, made up the majority of park visitors. Interestingly, park features had no significant impact on revisitation. Weather and time limitations were major factors limiting visitation to parks, and traffic and inadequate park facilities limited revisitation. Our results could be useful for urban planners as they develop guidelines to improve visitor satisfaction and promote the longevity of urban parks

A Hybrid GA–PSO–CNN Model for Ultra-Short-Term Wind Power Forecasting

Accurate and timely wind power forecasting is essential for achieving large-scale wind power grid integration and ensuring the safe and stable operation of the power system. For overcoming the inaccuracy of wind power forecasting caused by randomness and volatility, this study proposes a hybrid convolutional neural network (CNN) model (GA–PSO–CNN) integrating genetic algorithm (GA) and a particle swarm optimization (PSO). The model can establish feature maps between factors affecting wind power such as wind speed, wind direction, and temperature. Moreover, a mix-encoding GA–PSO algorithm is introduced to optimize the network hyperparameters and weights collaboratively, which solves the problem of subjective determination of the optimal network in the CNN and effectively prevents local optimization in the training process. The prediction effectiveness of the proposed model is verified using data from a wind farm in Ningxia, China. The results show that the MAE, MSE, and MAPE of the proposed GA–PSO–CNN model decreased by 1.13–9.55%, 0.46–7.98%, and 3.28–19.29%, respectively, in different seasons, compared with Single–CNN, PSO–CNN, ISSO–CNN, and CHACNN models. The convolution kernel size and number in each convolution layer were reduced by 5–18.4% in the GA–PSO–CNN model

Saikosaponin accumulation and antioxidative protection in drought-stressed Bupleurum chinense DC. plants

Dried root of Bupleurum spp. is one of the most popular ingredients in many oriental medicinal preparations. Potted Bupleurum chinense DC. seedlings were subjected to progressive drought stress by withholding irrigation followed by a rewatering phase. The changes in antioxidant system, hydrogen peroxide (H(2)O(2)), superoxide radicals (O(2)(-)), and malondialdehyde (MDA) contents as well as saikosaponin a (SSa) and saikosaponin d (SSd) content in B. chinense roots were investigated. Additionally, the antioxidant activity of the roots extract was evaluated. The results showed that B. chinense root appeared highly resistant to water deficit. Both SSa and SSd content increased with the progressive water deficit, however, decreased tinder severe drought conditions or after water recovery. Moderate drought treatment resulted in 83% increase in SSa content and 22% increase in SSd content compared to the well-hydrated treatment. And increased SSa and SSd content during drought were accompanied by enhanced O(2)(-) content and superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) activity until severe drought stress. Notably, in vitra antioxidant tests demonstrated that the lipid peroxidation inhibition capacity was positively correlated with the content of SSa and SSd, particularly significant at p=0.05 with SSd content. These results suggest that B. chinense roots exhibit effective antioxidative protection mechanism to withstand drought stress. And it could be speculated that drought-induced SSa and SSd accumulation in B. chinense roots may be stimulated via active oxygen species, and consequently involve in mitigating the oxidative damage due to its high anti-lipid peroxidation capacity. (c) 2009 Published by Elsevier B.V

Assessment of the Soil Organic Carbon Sink in a Project for the Conversion of Farmland to Forestland: A Case Study in Zichang County, Shaanxi, China

<div><p>The conversion of farmland to forestland not only changes the ecological environment but also enriches the soil with organic matter and affects the global carbon cycle. This paper reviews the influence of land use changes on the soil organic carbon sink to determine whether the Chinese “Grain-for-Green” (conversion of farmland to forestland) project increased the rate of SOC content during its implementation between 1999 and 2010 in the hilly and gully areas of the Loess Plateau in north-central China. The carbon sink was quantified, and the effects of the main species were assessed. The carbon sink increased from 2.26×10⁶ kg in 1999 to 8.32×10⁶ kg in 2010 with the sustainable growth of the converted areas. The black locust (<i>Robinia pseudoacacia L.</i>) and alfalfa (<i>Medicago sativa L.</i>) soil increased SOC content in the top soil (0–100 cm) in the initial 7-yr period, while the sequestration occurred later (>7 yr) in the 100–120 cm layer after the “Grain-for-Green” project was implemented. The carbon sink function measured for the afforested land provides evidence that the Grain-for-Green project has successfully excavated the carbon sink potential of the Shaanxi province and served as an important milestone for establishing an effective organic carbon management program.</p></div

Proline accumulation in leaves of Periploca sepium via both biosynthesis up-regulation and transport during recovery from severe drought.

Drought resistance and recovery ability are two important requisites for plant adaptation to drought environments. Proline (Pro) metabolism has been a major concern in plant drought tolerance. However, roles of Pro metabolism in plant recovery ability from severe drought stress are largely unexplored. Periploca sepium Bunge has gained increasing attention for its adaptation to dry environments. Here, we investigated Pro metabolism in different tissues of P. sepium seedlings in the course of drought stress and recovery. We found that leaf Pro metabolism response during post-drought recovery was dependant on drought severity. Pro biosynthesis was down-regulated during recovery from -0.4 MPa but increased continually and notably during recovery from -1.0 MPa. Significant correlation between Pro concentration and Δ1-pyrroline-5-carboxylate synthetase activity indicates that Glutamate pathway is the predominant synthesis route during both drought and re-watering periods. Ornithine δ-aminotransferase activity was up-regulated significantly only during recovery from -1.0 MPa, suggesting positive contribution of ornithine pathway to improving plant recovery capacity from severe drought. In addition to up-regulation of biosynthesis, Pro transport from stems and roots also contributed to high Pro accumulation in leaves and new buds during recovery from -1.0 MPa, as indicated by the combined analysis of Pro concentration and its biosynthesis in stems, roots and new buds. Except its known roles as energy, carbon and nitrogen sources for plant rapid recovery, significant positive correlation between Pro concentration and total antioxidant activity indicates that Pro accumulation can also promote plant damage repair ability by up-regulating antioxidant activity during recovery from severe drought stress

Contribution of different factors to the variation of SOC content (variance components, n = 45).

<p>Contribution of different factors to the variation of SOC content (variance components, n = 45).</p

SOC^a at the different depth of the alfalfa (<i>Medicago sativa L</i>) and black locust (<i>Robinia pseudoacacia L</i>) following the afforestation.

a<p>Data in the column are mean values (n = 3 for alfalfa and black locust), which are compared among different depths within each ages and are not different at the</p><p>5% level of significance if followed by the same letter.</p