On the export fluxes, seasonality and controls of particulate organic carbon in the northern South China Sea

基于234Th/238U不平衡法，本论文主要研究南海北部颗粒有机碳（POC）输出通量及其季节变化。南海为陆架边缘海，物理-生物地球化学过程的时空变化剧烈，需要高时空分辨率的234Th分布来估算POC输出通量，本研究采用改进的小体积二氧化锰测定234Th的方法，所需的海水体积由传统方法的20L缩减至2－4L，前处理流程亦大大简化，籍此我们进行了南海北部春、夏、秋、冬四个季节（2004－2005年）高空间分辨率的234Th调查，并参考了南海南部春季的结果。本论文亦分析了南海北部四个季节（2000－2004年）的POC分布特征。 本研究首先评估234Th示踪颗粒输出通量的方法，这包括不同采样方法（...Continental margins play a disproportionally important role in the global ocean carbon cycling and the flux of biologically produced organic carbon from the upper ocean implies the net sequestration of carbon dioxide (CO2) and the recycling of organic matter. However our understanding of the spatial and temporal variability of particulate organic carbon (POC) flux in the extremely dynamic marginal...学位：理学博士院系专业：海洋与环境学院环境科学与工程系_环境科学学号：B20033400

A Study of AID and Interacting Protein by Yeast Two-hybrid

AID(APPintracellulardomain)是由淀粉样前体蛋白APP经γ分泌酶切割产生的胞内端,它可能参与细胞凋亡,基因转录等活动,并对阿尔茨海默氏症的形成有一定影响.为进一步研究AID的功能,在本实验中,我们用AID为诱饵蛋白,运用酵母双杂交系统筛选与其结合的蛋白,得到其中两个阳性克隆,一个为RPS21,另一个为FLJ20551.接着又在酵母体系用β半乳糖苷酶报告基因验证了它们的相互作用,并在哺乳动物细胞中用免疫共沉淀的方法再次验证了它们相互作用的特异性.这些结果表明RPS21和FLJ20551可能通过与AID相互作用而影响阿尔茨海默氏症的形成.Amyloid precursor protein (APP),a key protein in pathogenesis of Alzheimer’s Disease (AD),is a type Ⅰ transmembrane protein which can be cleaved by β- and γ-secretase to release the amyloidogenic β-amyloid peptides and the APP intracellular domain (AID).While Aβ has been widely believed to initiate pathogenic cascades culminating AD,the physiological functions of AID remain elusive.To study the function of AID,we attempted to identify its interacting proteins by Yeast Two-Hybrid screening using AID as the bait.Among many positive clones identified,two candidates are particularly of interest:one encodes ribosomal protein S21 (RPS21),and the other encodes a fragment of a novel protein FLJ20551.The interaction specificity with AID of both the fragment and the full-length of the preys was confirmed by using the β-galatosidase reporter.Furthermore,we demonstrated,in mammalian 293T cells,the successful expression of the clone encoding RPS21 and verified the interaction between RPS21 and AID by co-immunoprecipitation approach.Our study identified two new AID binding proteins,RPS21 and FLJ20551,and may assign novel roles for the two proteins in mediating APP/AID functions in physiological and pathological processes including AD pathogenesis.国家自然科学基金(30270681, 30125021 );; 教育部“高校博士点基金”( 20030003087 );; 教育部回国人员科研启动基金资

INTERACTIONS BETWEEN COLLOIDS AND TRACE METALS IN MARINE ENVIRONMENTS

痕量金属的胶体结合态是海洋中金属的一种相当普遍的存在形式。胶体与痕量金属之间的相互作用影响着痕量金属在海水中的形态、迁移、生物可利用性及其归宿。总结了海洋胶体态金属的存在及其显著性,概述了胶体对金属在河口混合过程中行为的影响,并简要讨论了胶体在海水中痕量金属的固液相分配中的作用。 【英文摘要】 The colloidal fraction of trace metals is ubiquitous in seawater. The interaction between marine colloids and trace metals strongly controls the speciation, bioavailability, toxicity and the ultimate fate of metals in the ocean. The significance of colloidal trace metals and the role that colloidal particles play in the behavior of metals during the estuarine mixing is overviewed in this paper. A brief discussion was finally made on the potential role of colloids in the determination of distribution coeffic...国家重点基础研究发展规划项目"地球圈层相互作用中的深海过程和深海记录"(编号G2000078500);; 国家杰出青年科学基金项目"珠江三角洲及其邻近的南海海域中碳及微生物地球化学循环定量研究——胶体在该循环中的显著作用"(编号:49825111)资助

Nitrosation of malononitrile by HONO, ClNO and N2O3 : A theoretical study

Nitrosation of malononitrile by HONO, ClNO and N2O3 : A theoretical stud

SAMPLING AND DETERMINATION OF MARINE DISSOLVED ORGANIC CARBON

详细探讨了溶解有机碳(DOC)样品的采集与分析过程中的条件,以期发展DOC从采样到分析较为标准化(Robust)的方法步骤。影响DOC分析结果的关键有:采样过程中的样品瓶、垫片、滤膜、滤芯的选择及预处理,重力过滤,洁净台操作以及样品分析过程中仪器空白的确定。2001年5月和2002年11月两个航次在南海北部陆架上同一站位得到的DOC数据结果显示,夏季表层DOC浓度比冬季高10μmol/L,随深度增加DOC快速下降,50m以下DOC下降较为缓慢,冬、夏两季DOC分布特征基本相同。同一水样用不同方法(GF/F过滤采样方法与走航式滤芯过滤采样方法)所得到的DOC浓度的几次比对结果如下:盐度1.14,走航采样方法为(493±14)μmol/L(n=3),GF/F方法为(478±7)μmol/L(n=3);盐度20,走航采样方法为(112±2)μmol/L(n=3),GF/F方法为(123±2.6)μmol/L(n=3);盐度33.9,走航采样方法为(102±0.7)μmol/L(n=3),GF/F方法为(93±1.5)μmol/L(n=3)。结果表明,不论是在高盐度还是低盐度区域,两种方法结果基本相符,走航式采样过滤、方法可以应用于河口DOC的研究。Study on the dynamic behavior of DOC in seawater is important to understanding the global oceanic carbon cycle, in which the procedures of DOC sampling and determination remain to be improved for higher efficiency and accuracy. The authors developed a robust system to integrate all involving procedures from sampling, pretreatment, assaying (high temperature combustion oxidation, HTCO) and so on. The system was applied and has been proved valid on Chinese cases based on high quality data from the northern South China Sea sampled at a station in May 2001 and November 2002. Similar DOC concentration profiles between samples taken in the two periods were presented. Besides, a simplified sampling method-underway pumping and cartridge filtration—was applied; and the results are largely the same to that using traditional GF/F filtration method.国家自然科学基金项目“缺氧区形成机制——碳、氮生物地球化学过程的耦合分析”,40576036