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首页> 外文学位 >The Mechanisms and Pathways of the Uptake of Inorganic Mercury and Methylmercury Species in Escherichia coli: Possible Implications for Mercury Cycling in the Marine Environment.
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The Mechanisms and Pathways of the Uptake of Inorganic Mercury and Methylmercury Species in Escherichia coli: Possible Implications for Mercury Cycling in the Marine Environment.

机译：在大肠杆菌中吸收无机汞和甲基汞物种的机制和途径：对海洋环境中汞循环的可能影响。

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摘要

The objectives of this research were to construct a biosensor that can quantify CH3HgII uptake, and use this bioreporter to document the pathways of inorganic mercury (HgII) and CH 3HgII uptake in the microbe Escherichia coli. To this end we modified the mer-lux plasmid pRB28 by adding the gene merB, such that when CH3Hg II is in the cell it is broken down to Hg2+ which then triggers the release bioluminescence in proportion to the amount of Hg 2+ present. Using this tool we investigated the impact of chloride ion, humic acids, and amino acids, on the uptake of CH3Hg II. The role of glutathione transport proteins in the uptake of Hg II and CH3HgII was also investigated by comparing uptake rates in a strain that has a functioning ABC transport system to a strain where this transport system has been disabled by deleting two essential genes. 2 sections of Long Island Sound (LIS) were sampled for total mercury and thiols, and a mechanistic model was developed to predict the speciation of HgII and CH3HgII as well as the bioavailable proportions of HgII and CH3Hg II.;It was observed that the bioreporter displayed a minimum detection limit of 2.5 nM CH3HgII, and chloride reacts with CH 3H+ to a form neutral complex that passively diffuses into the cell. Humic acids reduced the bioavailability of CH3Hg II by forming bulky complexes that contained charged groups, and their binding constants (log K) with CH3Hg+ ranged from 10.8 to 12. The formation of the Hg(cysteine)2 and CH3Hg--cysteine complexes resulted in increased uptake of HgII and CH 3HgII. This was attributed to the activity of transport proteins. There were differences in uptake rates of the HgII and CH3HgII in the strain that had a functioning transporter when compared to the strain whose transport system had been disabled in complex medium. The formation of Hg(glutathione)2 and CH 3Hg-glutathione complexes in minimum medium resulted in decreases in uptake. Nanomolar quantities of thiols were measured in LIS, and glutathione was found to control the speciation of both HgII and CH 3HgII. Active processes were also found to be important in the uptake of HgII and CH3HgII in LIS.
机译：这项研究的目的是构建一种可以量化CH3HgII摄取量的生物传感器，并使用该生物报告器记录微生物大肠杆菌中无机汞（HgII）和CH 3HgII摄取的途径。为此，我们通过添加基因merB修饰了mer-lux质粒pRB28，使得当CH3Hg II在细胞中时，它被分解为Hg2 +，然后触发了与存在的Hg 2+数量成比例的生物发光。使用该工具，我们研究了氯离子，腐殖酸和氨基酸对CH3Hg II吸收的影响。谷胱甘肽转运蛋白在Hg II和CH3HgII吸收中的作用也通过比较具有正常ABC转运系统的菌株的吸收速率与已通过删除两个必需基因而使该转运系统失效的菌株进行了研究。采样了2个长岛之声（LIS）的总汞和硫醇样品，并建立了一个机械模型来预测HgII和CH3HgII的形态以及HgII和CH3Hg II的生物利用比例。最低检测限为2.5 nM CH3HgII，氯化物与CH 3H +反应生成中性复合物，该复合物被动扩散到细胞中。腐殖酸通过形成带有电荷基团的大体积复合物降低了CH3Hg II的生物利用度，它们与CH3Hg +的结合常数（log K）在10.8至12之间。Hg（半胱氨酸）2和CH3Hg-半胱氨酸复合物的形成导致增加HgII和CH 3HgII的吸收。这归因于转运蛋白的活性。与转运系统已在复杂培养基中被禁用的菌株相比，在具有正常转运蛋白的菌株中，HgII和CH3HgII的吸收率存在差异。 Hg（谷胱甘肽）2和CH 3Hg-谷胱甘肽复合物的形成导致最低吸收。在LIS中测量了纳摩尔量的硫醇，发现谷胱甘肽可控制HgII和CH 3HgII的形态。还发现活跃的过程对LIS中HgII和CH3HgII的吸收很重要。

著录项

  • 作者

    Ndu, Udonna Chinedu.;

  • 作者单位

    University of Connecticut.;

  • 授予单位 University of Connecticut.;
  • 学科 Chemical oceanography.;Chemical engineering.;Microbiology.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 131 p.
  • 总页数 131
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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