Evidence for cross-adaptation between s-triazine herbicides resulting in reduced efficacy under field conditions

BACKGROUND: Enhanced atrazine degradation has been observed in agricultural soils from around the globe. Soils exhibiting enhanced atrazine degradation may be cross-adapted with other s-triazine herbicides, thereby reducing their control of sensitive weed species. The aims of this study were (1) to determine the field persistence of simazine in atrazine-adapted and non-adapted soils, (2) to compare mineralization of ring-labeled (14)C-simazine and (14)C-atrazine between atrazine-adapted and non-adapted soils and (3) to evaluate prickly sida control with simazine in atrazine-adapted and non-adapted soils.RESULTS: Pooled over two pre-emergent (PRE) application dates, simazine field persistence was 1.4-fold lower in atrazine-adapted than in non-adapted soils. For both simazine and atrazine, the mineralization lag phase was 4.3-fold shorter and the mineralization rate constant was 3.5-fold higher in atrazine-adapted than in non-adapted soils. Collectively, the persistence and mineralization data confirm cross-adaptation between these s-triazine herbicides. In non-adapted soils, simazine PRE at the 15 March and 17 April planting dates reduced prickly sida density at least 5.4-fold compared with the no simazine PRE treatment. Conversely, in atrazine-adapted soils, prickly sida densities were not statistically different between simazine PRE and no simazine PRE at either planting date, thereby indicating reduced simazine efficacy in atrazine-adapted soils.CONCLUSIONS: Results demonstrate the potential for cross-adaptation among s-triazine herbicides and the subsequent reduction in the control of otherwise sensitive weed species. Copyright (c) 2008 Society of Chemical Industry.     

Mozzarella干酪凝乳过程中理化特性及微观结构的变化

为了解牛奶凝乳过程中理化特性及微观结构的变化,研究了Mozzarella干酪凝乳过程中表观粘度、自由巯基含量、流变特性和微观结构的变化,结果表明,加入凝乳酶后,体系中的二硫键即开始减少,至30 min时出现明显增加趋势,而牛奶的表观粘度、弹性模量、粘性模量都在30～40 min出现升高,通过共聚焦激光显微镜可以观察到此时的蛋白质颗粒发生剧烈的凝集;随着凝乳的发展,二硫键生成量增加,凝乳的表观粘度、弹性模量、粘性模量也呈增加趋势,酪蛋白胶束越来越聚集、收缩.通过表观粘度和流变特性测定到的凝乳时间与用共聚焦显微镜观察到的凝乳时间都比较接近,说明3种方法都可用于凝乳时间的客观判断.     

Changes in the coagulation parameters in dogs with protein-losing enteropathy between before and after treatment

Protein-losing enteropathy (PLE) is known to induce hypercoagulability and resultant thromboembolism in dogs. We hypothesized that hypercoagulability would improve if remission was obtained in dogs with PLE after treatment. This study aimed to evaluate the changes in the coagulation parameters after treatment in dogs diagnosed with PLE. As coagulation parameters, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, thrombin-antithrombin complex (TAT), D-dimer, and antithrombin (AT) were measured. In addition to these parameters, rotational thromboelastometry (ROTEM), which evaluates the comprehensive coagulation and fibrinolysis reactions of whole blood, was conducted and the data of clotting time (CT), clot formation time (CFT), α angle (α), maximum clot firmness (MCF) and lysis index at 60 min (LI60) were obtained. Eleven of the 14 dogs diagnosed with PLE were classified as responders to the treatment based on the changes in their plasma albumin (ALB) concentration after treatment. Significant increase in CFT and decrease of α and MCF indicating the resolution of hypercoagulability were found after treatment in responder dogs; however, there was no significant change in the coagulation and fibrinolysis parameters other than those measured by ROTEM. This study demonstrated that the hypercoagulability detected by ROTEM was significantly improved after treatment in dogs with PLE.     

慢病毒载体介导成纤维细胞高效稳定表达绿色荧光蛋白

试验尝试建立稳定表达外源基因的人成纤维细胞系。取成年男性包皮皮肤的皮下组织,分离培养人皮肤成纤维细胞,分别采用脂质体和慢病毒载体介导转染人皮肤成纤维细胞表达绿色荧光蛋白。结果显示,来自成年人包皮皮下组织的成纤维细胞呈梭形,具有快速的增殖和稳定的生长性能。脂质体介导转染的人皮肤成纤维细胞绿色荧光蛋白表达不稳定,阳性细胞表达率低,转染后的人成纤维细胞变得更为细长,细胞生长速度降低。慢病毒载体介导人皮肤成纤维细胞高效稳定表达绿色荧光蛋白,转染后细胞生长性能和形态没有变化,经过多次传代和冻存复苏对人皮肤成纤维细胞绿色荧光蛋白的表达没有影响,通过流式细胞仪对慢病毒介导表达绿色荧光蛋白的人皮肤成纤维细胞检测显示,绿色荧光蛋白表达阳性率为99.85%,并且表达绿色荧光蛋白的人皮肤成纤维细胞细胞均一程度为76.05%。试验证实了慢病毒载体能够高效稳定介导人皮肤成纤维细胞表达绿色荧光蛋白。     

渭干河—库车河三角洲绿洲棉田土壤盐分估算及遥感反演

基于研究区的野外采样数据与Landsat 8遥感影像提取的增强型植被指数,构建渭干河—库车河三角洲绿洲棉田土壤盐分估算模型,并对土壤盐分的空间分布格局进行预测。结果表明:(1)由土壤含盐量与增强型归一化植被指数(ENDVI)构建的线性回归模型(y=-56.494x+22.687)拟合效果最好(R2=0. 886,RMSE=0. 907)。(2)通过选取的82个采样点,依据最佳遥感反演模型,预测出研究区土壤含盐量在9.33～26.99 g·kg-1之间变化,平均值为17.42 g·kg-1,标准差为2.30 g·kg-1,预测结果与土壤盐分的实测值较为一致。(3)利用地统计分析方法制作研究区棉田土壤盐分的空间分布图,分析可知土壤盐分从绿洲内部向外围呈逐渐增加的趋势。     

水稻叶绿体基因组定点表达载体的构建及增强型绿色荧光蛋白原核表达分析

分别克隆了水稻叶绿体基因组同源重组片段trnI和trnA、具有3种不同核糖体结合位点(RBS)序列的增强型绿色荧光蛋白基因(egfp)、来自烟草叶绿体的16S rRNA基因启动子Prrn和psbA基因终止子TpsbA,将上述元件通过酶切位点依次连接到质粒pUC19上,构建了3种能编码增强型绿色荧光蛋白(EGFP)的水稻叶绿体基因组定点整合表达载体pIA - EGFP1、pIA - EGFP2和pIA - EGFP3.进行分子检测验证后,对上述载体进行了大肠杆菌EGFP原核表达检测,结果携带来源于λ噬菌体T7基因10的5′端非翻译区的载体pIA - EGFP3荧光最强,适合用于水稻叶绿体转化.     

天然胶乳微生物凝固研究概况及建议

概述国内天然胶乳微生物凝固的研究发展情况,论述了当前在研究上存在的主要问题,根据国内目前天然橡胶生产实际,建议重视天然胶乳自然凝固的研究开发工作。     

Evaluation of Potential Thrombin Inhibitors from the White Mangrove (Laguncularia racemosa (L.) C.F. Gaertn.)

The aim of this work was to verify the effects of methanol (MeOH) and hydroalcoholic (HA) extracts and their respective partition phases obtained from white mangrove (Laguncularia racemosa (L.) C.F. Gaertn.) leaves on human thrombin activity. Among the extracts and phases tested, only the ethyl acetate and butanolic partitions significantly inhibited human thrombin activity and the coagulation of plasma in the presence of this enzyme. Chromatographic analyses of the thrombin samples incubated with these phases revealed that different compounds were able to interact with thrombin. The butanolic phase of the MeOH extract had the most potent inhibitory effects, reducing enzymatic activity and thrombin-induced plasma coagulation. Two glycosylated flavonoids in this partition were identified as the most potent inhibitors of human thrombin activity, namely quercetin-3-O-arabinoside (QAra) and quercetin-3-O-rhamnoside (Qn). Chromatographic analyses of thrombin samples incubated with these flavonoids demonstrated the chemical modification of this enzyme, suggesting that the MeOH extract contained other compounds that both induced structural changes in thrombin and diminished its activity. In this article, we show that despite the near absence of the medical use of mangrove compounds, this plant contains natural compounds with potential therapeutic applications.