Identification and characterization of an anti-fibrotic benzopyran compound isolated from mangrove-derived Streptomyces xiamenensis

An anti-fibrotic compound produced by Streptomycesn xiamenensis, found in mangrove sediments, was investigated for possible therapeutic effects against fibrosis. The compound, N-[[3,4-dihydro-3S-hydroxy-2S-methyl-2-(4'R-methyl-3'S-pentenyl)-2H-1-benzopyran-6-yl]carbonyl]-threonine (1), was isolated from crude extracts and its structure, including the absolute configuration was determined by extensive spectroscopic data analyses, Mosher's method, Marfey's reagent and quantum mechanical calculations. In terms of biological effects, this compound inhibits the proliferation of human lung fibroblasts (WI26), blocks adhesion of human acute monocytic leukemia cells (THP-1) to a monolayer of WI26 cells, and reduces the contractile capacity of WI26 cells in three-dimensional free-floating collagen gels. Altogether, these data indicate that we have identified a bioactive alkaloid (1) with multiple inhibitory biological effects on lung excessive fibrotic characteristics, that are likely involved in fibrosis, suggesting that this molecule might indeed have therapeutic potential against fibrosis.     

智能灌溉系统的可靠性仿真研究

介绍了一种智能灌溉系统的构成及其工作原理,并对该系统的可靠性进行了研究;分析了系统的失效模式,进而建立了系统的故障树;利用Monte Carlo法进行可靠性仿真,给出了仿真结果,并根据仿真结果对系统的改进完善提出了建议,为提高智能灌溉系统的可靠性和维修性提供参考依据,对提高农业生产具有重大意义.     

初学者对冷冲压中冲裁模设计刃口尺寸计算(配做法)中容易出现的几个误区

模具工业是国民经济的重要基础工业之一。模具是工业生产中的基础工艺装备,是一种高附加值的高精密集型产品,也是高新技术产业化的重要领域,其技术水平的高低已经成为衡量一个国家制造业水平的重要标志。     

磷酸盐缓冲液的浓度和pH对革胡子鲶肠道抗菌蛋白/肽分级盐析的影响

[目的]探讨磷酸盐缓冲液的pH和浓度在分级盐析时,对革胡子鲶肠道各组分蛋白/肽的影响。[方法]以不同浓度和pH的磷酸盐缓冲液作为组织匀浆缓冲液,在硫酸铵饱和度为20%、40%、60%、80%和100%的条件下,对革胡子鲶肠道抗菌蛋白/肽进行分级盐析,并对盐析产物进行称重、电泳检测和抑菌活性分析。[结果]磷酸盐缓冲液的pH为6.0或7.4时,其浓度对盐析产物产量、蛋白沉淀和抑菌效果无显著影响。而pH为8.0、浓度为0.05 mol/L时,硫酸铵饱和度为60%和100%的粗蛋白/肽的产量显著高于浓度为0.02 mol/L的磷酸盐缓冲液粗蛋白含量;大分子蛋白能更好地在硫酸铵饱和度为20%和40%时沉淀下来,而在饱和度为60%、80%和100%能获得分子量相对较小的抗菌蛋白/肽。磷酸盐缓冲液的pH和浓度对抑菌效果无显著影响。[结论]pH8.0,浓度为0.05 mol/L的磷酸盐缓冲液更适于革胡子鲶肠道抗菌蛋白/肽的提取。     

抗寒茶树品种的筛选研究

为了获得抗寒茶树品种或资源,提高茶园防冻减灾的能力,分别采用田间自然鉴定法、叶片解剖结构和电导法对24个茶树品种和优质资源的抗寒性进行了鉴定。结果表明,‘浙农113’、‘中茶102’、‘翠峰’等茶树品种在以上抗寒性鉴定方法的评价结果中均表现为较强抗寒性,属于抗寒茶树品种。不同鉴定方法评价茶树抗寒性的结果有一定的差异,综合鉴定比较的结果较单一鉴定方法的结果更可靠,更符合生产实际。     

不同抗寒性茶树品种秋季新梢的生理特性研究

为了探明茶树品种的抗寒机理,在前期抗寒性茶树品种筛选研究的基础上,选择强抗寒性、中抗寒性和弱抗寒性茶树品种各2份,分别比较了其秋季新梢中过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)和多酚氧化酶(PPO)等抗寒性相关酶的活性,并对可溶性蛋白质、可溶性糖、丙二醛含量等生理生化特性进行测定。结果表明,强抗寒性茶树品种的秋季新梢POD活性和可溶性糖含量较高,而弱抗寒性的茶树品种POD活性和可溶性糖含量较低。可溶性蛋白质含量高低与抗寒性强弱有一定关系,CAT、SOD和PPO活性及丙二醛含量高低与抗寒性强弱之间无明显规律可循。因此,POD活性和可溶性糖含量高低可以作为判断茶树品种或资源新梢抗寒性强弱的鉴定指标。     

Isolation of a Phytase-Producing Bacterial Strain from Agricultural Soil and its Characterization and Application as an Effective Eco-Friendly Phosphate Solubilizing Bioinoculant

In the present study, we isolated from agricultural soils, a Bacillus strain designated SD01N-014, expressing high-level extracellular phytase activity and investigated its potential to be used as a soil phosphate-solubilizing bioinoculant to improve soil phosphorus (P) availability and thus enhance plant growth. Soil inoculation test showed that being as an inoculant, SD01N-014 substantially enhanced soil P nutrition. Pot experiments showed that when applied to soils, SD01N-014 is capable of colonizing maize seedling roots, increasing plant-available P levels in the rhizosphere and promoting seedling growth. High tunnel trials with different vegetable plants demonstrated that SD01N-014 as a soil inoculant greatly promoted plant growth and was positively correlated with inoculum sizes. Together, these results indicate that SD01N-014 holds promising potential as a cheap, viable and eco-friendly alternative to chemical P fertilizers for increasing soil fertility and crop production in sustainable farming.     

Characteristics of canopy interception and its simulation with a revised Gash model for a larch plantation in the Liupan Mountains,China

Canopy interception is a significant proportion of incident rainfall and evapotranspiration of forest ecosystems. Hence, identifying its magnitude is vital for studies of eco-hydrological processes and hydrological impact evaluation. In this study, throughfall, stemflow and interception were measured in a pure Larix principis-rupprechtii Mayr.(larch) plantation in the Liupan Mountains of northwestern China during the growing season(May–October) of 2015, and simulated using a revised Gash model. During the study period, the total precipitation was499.0 mm; corresponding total throughfall, stemflow and canopy interception were 410.3, 2.0 and 86.7 mm,accounting for 82.2, 0.4 and 17.4% of the total precipitation, respectively. With increasing rainfall, the canopy interception ratio of individual rainfall events decreased initially and then tended to stabilize. Within the study period, the simulated total canopy interception, throughfall and stemflow were 2.2 mm lower, 2.5 mm higher and0.3 mm lower than their measured values, with a relative error of 2.5, 0.6 and 15.0%, respectively. As quantified by the model, canopy interception loss(79%) mainly consisted of interception caused by canopy adsorption, while the proportions of additional interception and trunk interception were small. The revised Gash model was highly sensitive to the parameter of canopy storage capacity,followed by the parameters of canopy density and mean rainfall intensity, but less sensitive to the parameters of mean evaporation rate, trunk storage capacity, and stemflow ratio. The revised Gash model satisfactorily simulated the total canopy interception of the larch plantation within the growing season but was less accurate for some individual rainfall events, indicating that some flaws exist in the model structure. Further measures to improve the model's ability in simulating the interception of individual rainfall events were suggested.     

村庄整治中的“小组微生”模式研究

成都市村庄整治中的"小组微生"模式在全国统筹城乡发展中独树一帜,受到多方关注并被称为"新农村建设的2.0版"。它具有先进的规划设计理念、"自民市法"的运行机制、"产村配治"的协同推进、"建改保"分类整治四大特色。该模式的实施,使得乡村形态更美丽、农民群众享福利、三产融合获发展。但从农民福利需求的角度看,存在着成本高、指标不足、轻发展等问题,需要有针对性地优化完善后加以推广应用。     

基于SRAP标记的黄瓜霜霉菌遗传多样性分析

本研究对来自黑龙江、辽宁、河北、山东、江苏5个省12个黄瓜主产区的77个黄瓜霜霉菌菌株,采用SRAP分子标记进行了遗传多样性分析。从35对SRAP引物中筛选出10对引物,共产生9 554条扩增条带,其中9 132条表现多态性,占95.6%。基于SRAP分子标记,77个黄瓜霜霉菌菌株的遗传距离为0.60~1.00,表明黄瓜霜霉菌具有丰富的遗传多样性。通过聚类分析,77个黄瓜霜霉菌菌株聚类为8个类群,并且来自相同地区的菌株大多数聚集于同一类群中,表明黄瓜霜霉菌群体的遗传多样性与其地理来源密切相关。