Binding of triclosan to human serum albumin: insight into the molecular toxicity of emerging contaminant

Purpose

The interaction between triclosan (TCS) and human serum albumin (HSA) was investigated in order to obtain the binding mechanism, binding constant, the type of binding force, the binding distance between the donor and acceptor, and the effect of TCS on the conformation change of HSA.

Methods

A HSA solution was added to the quartz cell and then titrated by successive addition of TCS. The fluorescence quenching spectra and synchronous spectra were recorded with the excitation and emission slits of the passage of band set at 10 and 20 nm. Three-dimensional fluorescence spectra of HSA were recorded before and after the addition of TCS. The capillary electrophoresis was conducted with the pressure injection mode at 0.5 psi for 5 s, separation under 25 kV, and detection at 214 nm.

Results

Fluorescence data indicated the fluorescence quenching of HSA by TCS was static quenching, and the quenching constants (K _a ) were 1.14?×?10⁵, 8.75?×?10⁴, 6.67?×?10⁴, and 5.00?×?10⁴ at 293, 298, 303, and 309 K, respectively. The thermodynamic parameters, enthalpy change (??H) and entropy change (??S) for the interaction were calculated to be ?37.9 kJ mol^?1 and 32.6 J?mol^?1 K^?1. The binding distance between TCS and tryptophan residues of HSA was obtained to be 1.81 nm according to F??rster nonradioactive energy transfer theory. The UV-Vis absorption spectroscopy, the synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy, and circular dichroism spectroscopy revealed the alterations of HSA secondary structure in the presence of TCS. Finally, the interaction between TCS and HSA was further confirmed by capillary electrophoresis.

Conclusions

TCS was bound to HSA to form the TCS-HSA complex, with the binding distance of 1.81 nm. Hydrophobic interaction and hydrogen bond were dominated in the binding. TCS could change the secondary conformation of HSA. This work provides an insight into noncovalent interaction between emerging pollutants and protein, helping to elucidate the toxic mechanism of such pollutants.     

1，2-二氯苯在3种基质中的吸附研究

采用平衡振荡法研究了1,2-二氯苯在3种人工湿地基质中的吸附情况。结果表明,1,2-二氯苯在12 h达到吸附平衡,可由Lagergren一级吸附动力学模型得出3种土壤的吸附速率常数分别为0.3338 h-1、0.2679 h-1和0.2537 h-1,壤土的吸附效果明显好于细砂、粗砂。30℃的吸附等温线既符合Freud...     

基于关联矩阵的土地利用导向分区研究

研究探讨土地利用开发与生态保护之间的联动耦合关系,建立土地利用开发-保护二维关联矩阵;提出在ArcGIS支持下,基于土地利用开发-保护二维关联矩阵实现土地利用导向分区的方法与技术路线,选择位于北京东部发展带的重要结点河北省廊坊市为实证研究区,开展土地利用导向分区的方法与实证研究,并提出基于土地利用导向分区的廊坊市土地利用策略,以期为区域合理配置土地资源提供理论与方法依据,希望对研究区以至相关区域可持续发展有所帮助.研究主要结论和建议:①实证研究结果表明土地利用开发-保护二维关联矩阵是进行土地利用导向分区行之有效的方法,分区结果能基本反映廊坊市经济社会发展战略实际情况;研究提出的矩阵构建思路以及基于土地利用开发-保护关联矩阵在ArcGIS中实现土地利用导向分区的操作路线和方法具有普适性;②根据土地利用开发-保护二维关联矩阵划分出廓坊市四个土地利用导向区:重点开发利用区、适度开发利用区、适度保护用地区与重点保护用地区;③提出基于土地利用导向分区的廊坊市土地利用策略:重点开发利用区,推荐点-轴开发模式;适度开发利用区,采用集群发展模式;适度保护用地区,实行点状集约利用开发模式;重点保护用地区,采用疏解保护模式.     

Increased urinary 8-hydroxy-2��-deoxyguanosine levels in workers exposed to di-(2-ethylhexyl) phthalate in a waste plastic recycling site in China

Background

Di-(2-ethylhexyl) phthalate (DEHP) is a common plasticizer used in industrial and diverse consumer products. Animal studies indicate DEHP caused developmental, reproductive, and hepatic toxicities. However, human studies of the potential effects of DEHP are limited.

Methods

The exposed site with a history of over 20 years of waste plastic recycling was located in Hunan Province, China. The reference site without known DEHP pollution source was about 50 km far away from the exposed site. In this study, 181 workers working in plastic waste recycling and 160 gender?Cage matched farmers were recruited. DEHP concentrations in water and cultivated soil samples, serum thyroid-stimulating hormone, malondialdehyde (MDA), superoxide dismutase (SOD), urinary 8-hydroxy-2??-deoxyguanosine (8-OHdG), and micronuclei frequency in human capillary blood lymphocytes were analyzed.

Results

Mean levels of DEHP were greater in environment at the recycling site than at reference site (industry wastewater for the exposed: 42.43 ??g/l; well water: 14.20 vs. 0.79 ??g/l, pond water: 135.68 vs. 0.37 ??g/l, cultivated soil: 13.07 vs. 0.81 mg/kg, p?p?p?Conclusions The occupational DEHP exposure might contribute to oxidative deoxyribonucleic acid damage in the male workers.     

Phosphorus release from ash and remaining tissues of two wetland species after a prescribed fire

Dead plant tissues and ash from a prescribed fire play an important role in nutrient balance and cycling in the Florida Everglades ecosystem. The objective of this study was to assess the dynamic changes in total phosphorus release (TPr) from ash or tissues of either cattail (Typha domingensis Pers.) or sawgrass (Cladium jamaicense Crantz) to water. Natural-dead (senesced-dead) and burning-dead (standing-dead due to a prescribed fire) cattail and sawgrass were collected from highly (H) and moderately (M) impacted zones in the Florida Everglades. This experiment was conducted by incubation and water-extraction of the materials in plastic bottles for 65 d at room temperature (24 +/- 1 degrees C). Results showed that 63 to 88%, 17 to 48%, 9 to 20%, and 13 to 28% of total P (TPp) were released as TPr from cattail and sawgrass ash, cattail tissues from the H zone, cattail tissues, and sawgrass tissues from the M zone, respectively. TPp means total P of plant tissues, whereas TPr is total P release from the tissues or ash. Most of the TPr was released within 24 h after burning. The quick release of TPr observed in this experiment may help explain the P surge in the surface water immediately following a fire in the marsh. These findings suggest that prescribed burning accelerates P release from cattail and sawgrass. They also imply that it is very important to keep the water stagnant in the first 24 h to maximize the benefits of a prescribed fire in the Everglades.     

基于TOPSIS方法的苏州市循环经济发展绩效评价研究

借助绩效评价理论探索分析了循环经济发展评价的指标和方法,并尝试运用多目标决策方法中的嫡值法（Technique for Order Preference by Similarity to Ideal Solution,TOPSIS）开展研究试点。通过对苏州市1997～2008年间的循环经济发展绩效进行综合评价,结果表明,10年来苏州市循环经济绩效水平呈U型发展趋势,近年来发展势头良好,但未来在提高低能耗第三产业比例、降低纺织业综合能耗、提高工业电力利用率等方面需要采取更有力的措施;苏州市循环经济发展绩效评价指标体系能够较好地反映该市循环经济发展状况,对于苏南同类城市有一定的借鉴意义;TOPSIS方法较好地避免了主观因素在综合分析过程中的影响,但无法就各评价因子对结果的影响程度、影响途径等进行更深层次的分析,需注意与其他方法相结合。     

海洋产业结构变动对海洋经济增长的贡献研究——以辽宁省为例

海洋产业结构变动是影响海洋经济增长的重要因素。以辽宁省为例,运用多部门经济模型和基于统计角度的GDP产业结构贡献度测算方法,分析了1997—2007年海洋产业结构变动对海洋经济增长的贡献,并进行了偏离—份额分析,揭示了海洋产业结构变动对海洋经济增长的影响,提出了对策,为优化海洋产业结构提供科学依据。     

大气气溶胶酸度的研究进展

大气气溶胶的环境效应、气候效应和健康效应均与气溶胶的物理化学性质直接相关,其中大气气溶胶酸度是其重要的性质之一。大气气溶胶酸度对酸沉降、灰霾的形成具有重要作用,并影响大气非均相化学反应,相关研究已成为国际研究的热点。对国内外学者近年来在大气气溶胶酸度对大气环境与人体健康的影响、大气气溶胶酸度的影响因素与变化规律、大气气溶胶酸度/酸化缓冲能力的测定与计算方法、大气气溶胶酸性成分采集系统等方面的研究进展作了较系统的综述,并对大气气溶胶酸度研究未来的发展进行了展望。     

溶胶-凝胶法制备复合光催化剂（MWNTs/TiO_2）工艺条件的研究

以多壁碳纳米管（MWNTs）为载体,在煅烧温度200~900℃、煅烧时间1~7 h、溶胶体系pH值为2~10的工艺条件下,采用溶胶-凝胶法制备复合光催化剂（MWNTs/TiO2）。通过其对甲基橙的光催化降解效果对比,评价各种复合光催化剂催化活性之间的差异,结果表明,随着煅烧温度的升高,复合光催化剂中纳米TiO2的晶型由锐钛型逐渐向金红石型转变,500℃时为2种晶型的混合相;pH值为2的强酸性条件有利于形成金红石晶型,pH值为5的中性及弱酸性条件则有利于形成锐钛型,而pH值为3时为2种晶型的混合相;在煅烧温度500℃、煅烧时间3 h、溶胶凝胶体系pH值为3的最佳制备工艺条件下,复合光催化剂催化活性最高,借助扫描电镜发现其TiO2均匀地包覆在多壁碳纳米管管壁上。     

论旅游地的环境解说

环境教育是全民的、终身的教育,环境解说是环境教育的重要方式。环境解说一方面有利于保护旅游地的生态环境,另一方面也是国民环境教育网络体系中的重要节点。本文在简要介绍了海外环境解说的理论发展后,总结了美国和我国台湾省国家公园环境解说方面的成功经验,对我国旅游地环境解说系统建设提出了建议。