3 resultados para Dio Cassius Cocceianus.

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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盐胁迫是限制高等植物和藻类生长和产量的主要环境因子之一。PSII对环境胁迫的响应被认为是光合作用适应逆境过程中最重要的一个环节。尽管盐胁迫对PSII的影响已进行了大量的研究,但有关盐胁迫对PSII作用方式和位点的研究仍存在着争议。我们主要研究了盐胁迫对螺旋藻PSII结构和功能的影响,以探讨盐胁迫对PSII的作用方式和位点以及该藻细胞PSII对盐胁迫的适应机理。主要研究结果如下: 1. 用0、0.2、0.4、0.6、0.8M NaCl处理螺旋藻细胞12小时。随盐浓度的增加,螺旋藻细胞的Chla、carotenoid、PC、APC及蛋白含量均呈下降趋势,说明盐胁迫抑制了上述色素及蛋白的合成或加速了它们的降解,从而影响了螺旋藻的光合作用。 2. 随盐浓度的增加,螺旋藻细胞光合放氧活性和PS II电子传递活性显著降低,表明盐胁迫引起藻细胞PS II活性的下降。 3. 通过放氧活性、热致发光(TL)、多相荧光瞬态上升动力学曲线的测定以及Western 杂交,来探讨盐胁迫对螺旋藻细胞PS II供体侧电子传递及OEC33蛋白含量的影响。结果显示:随盐浓度的增加,螺旋藻细胞光合放氧活性和PS II电子传递活性下降;TL B-band和Q-band强度降低,在0-0.6M NaCl下,B-band的周期性振荡清楚,最大值出现在第二次和第六次闪光,而在0.8M NaCl时,S态振荡基本上消失,S 态氧化还原循环受阻;Fm, J、I和P相荧光水平降低。以上结果都表明盐胁迫使PS II的放氧侧受损伤。且随盐浓度的增加,盐分引起螺旋藻细胞外周蛋白OEC33的降解,在蓝藻中首次提出放氧机构的S态循环受阻,放氧活性降低。 4. 通过OJIP曲线的测定以及JIP-test、闪光诱导的可变荧光衰减动力学、热致发光(TL)的分析,我们研究了盐胁迫对螺旋藻细胞PS II受体侧的影响。结果显示: JIP-test的参数Ψo和φEo随盐浓度的增加而下降,显示QA-到QB 电子传递受阻;可变荧光衰减动力学快相组分半衰期延长,所占总可变荧光百分比下降,表明QA-到QB 电子转移变慢,中相组分半衰期延长、所占百分比下降,说明空的QB位点对PQ的结合减慢,有可能PQ分子对QB位点的结合能力下降;TL B-band和Q-band的峰温度出现了位移,可能QA、QB的氧化还原电势发生了改变。以上结果表明,盐胁迫伤害了PSII受体侧的电子传递。 5. 首次运用闪光诱导下的叶绿素荧光上升及其衰减动力学来研究盐胁迫对PS II受体侧的影响。 6. 盐胁迫下,PS II供体侧和受体侧电子传递受抑制,有活性的PSII反应中心数量下降,说明盐胁迫对螺旋藻细胞PSII的伤害也可能是多位点的作用方式。此外,盐胁迫下,藻细胞放氧活性的下降快于受体侧QA 到QB电子传递所占百分比的下降,有可能PS II放氧侧先受损伤,然后是反应中心和受体侧。上述结果表明盐胁迫下PSII活性的降低是由于PSII供体侧和受体侧电子传递的抑制,有活性的PSII反应中心的减少。 7. 借助螺旋藻类囊体膜的Western杂交分析,来研究盐胁迫对螺旋藻类囊体膜PSII相关蛋白的影响。结果表明,上述PSII活性的抑制是由于类囊体膜蛋白的损失。主要与PSII反应中心CP43、CP47和OEC33蛋白含量的下降有关。 8. PS II机构对盐胁迫的适应涉及以下几个方面:降低吸收横截面,(PC/chla,APC/chla比值的降低);光系统II光化学反应的改变,通过关闭的PS II反应中心比例的增加,使得PS II机构免于过多激发能的伤害而得以保护;提高了剩余的有活性反应中心的耗能效率(DIo/RC增加);保持有活性反应中心高的激发能转化效率,比如,TRo/RC保持不变;另外,随盐浓度的增加,由藻胆体向光系统I的能量传递增加,避免过量激发能对 PSII的伤害,使螺旋藻细胞适应盐胁迫环境。

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The Ultrahigh Pressure Metamorphic (UHPM) eclogite, which was resulted from deep subduction of crustal continent, is very significant due to its continental dynamic implications. Further more, this kind of rocks experienced great P-T, fluid and stresses changes during its forming and exhumation, causing mineral reactions occur intensively, which resulted in a lot of fantastic micro-texture. The micro-texture was preserved duo to a rapid exhumation of the eclogite. This PhD dissertation takes such micro-textures in 10 Donghai eclogite samples South Sulu UHPM terrene, as research object to reveal the transformation of the eclogite to amphibolite. Microscope and Scanning Electron Microscope were employed to observe the micro-texture. Basing on microprobe analysis of minerals, the ACF projections and iso-con analysis were used to uncover the mineral reactions during the transformation. Micro-texture observation (both of Microcopy and Electron Scanning Microscope), demonstrated: l.The peak mineral assemblage of the researched Donghai eclogites is garnet + omphacite + rutile (+ kyanite + aptite +coesite). 2.The transformation of the Donghai eclogite to amphibolite can be divided into two stages: The earlier one is Symplectization, resulting in the forming of diopside + albite (+magnetite) symplectite that occurred only along the boundary between two adjacent omphacite grains. Other minerals were not involved in such reaction. The latter stage is Fluid-Infiltration of the eclogite, which was caused by fluid-intrusion. The infiltration is demonstrated by amphibolization of the symplectite, decomposition of garnet and the forming of some hydrous minerals such as phengite and epidote, and resulted in an amphibole + plagioclase + phengite + epidote or ziosite assemblage. Basing on microprobe analysis of the minerals, ACF projections indicated: In the ACF diagrams, the two joint lines of peak Grt + Omp and Dio + Ab crossed at Omp projection-point, indicating that the garnet had not taken part in the forming reaction of the Dio + Ab symplectite, just like that had been pointed out by micro-texture observation. In the ACF diagrams, the hornblende + plagioclase + epidote + phengite quadrilateral intersected with Dio + Ab + Grt triangle, demonstrating that the hydrous mineral assemblage was formed by fluid infiltration through garnet, diopside and albite. Iso-con (mass-balance) analysis of the symplectization and infiltration reveals: 1.The symplectization of the omphacite has a very complex mass exchange: Some symplectite gained only silicon from its surroundings; and some one requires Ca, but provides Na to its surroundings; while other symplectite provides Ca, Mg and Fe to its surroundings. 2.The infiltration cause variable mass exchanges occurring among the garnet, diopside and albite: In some eclogite sample, no mass, except H2O, exchange occurred during the infiltration. Meanwhile, there was not any hydrous mineral except hornblende formed in the sample accordingly. In some samples, the mass exchange among the three minerals is complex: amphibolization of the diopside in a symplectite gained Al from garnet, and provided Si and Ca to its surrounding, resulting in a Si, Ca and Al-rich fluid. Correspondingly, there was a lot of phengite and ziosite occurred in the sample. In other samples, the amphibolization of a symplectite provided Fe and Mg besides Si and Ca to its surrounding while gained Al. In such kind of sample, epidote occurred within the hydrous mineral assemblage. Synthesizing the micro-texture observation, ACF analysis and iso-con analysis, we deduced the transformation procedure as following: 1. A symplectite after an omphacite was resulted by one, or two, or all of following mineral reactions together: Jd (Ca-Tsch) +SiO2=Ab (An) (1) 4NaA IS i.A+CaO=2NaAlS i308+Na20+CaAl2S 1208 (2) 2NaAlSi2OB (Jd in Omp)+CaMgSi;,0B(Dio in Omp)-2NaAlSi:,O"(Ab)+Ca0+Mg0 (3) 2(CaAl2Si0fi) (Ca-tsch in Omp)+CaFeSi2O6(Hed in 0mp)-H>2CaAl2Si208(An)+Ca0 + FeO (4) A CO2-rich fluid is suggested as cataclysm for the above reactions, which largely increased the mobility of Ca, Mg and Na resulted from reaction (2), (3) and (4). The immobile product Fe2* combined with rutile to form ilmenite, resulting in rutile + ilmenite symplectite. Or, the Fe was precipitated as hematite locally. A procedure of the fluid infiltration as following is suggested: I .A hydrous fluid intruded into the eclogite, and reacted first with garnet to form hornblende and extra Al, resulting in a hornblende film around the garnet grain and an Al-rich fluid. 2.The Al-rich fluid infiltrated through the symplectite, OH" and part of the Al in the fluid combined with Dio while some Si and Ca in the Dio were dissolved made the Dio transferred to amphibole. Meanwhile, plagioclase-type cation exchange occurred between the fluid and plagioclase in the symplectite, making the plagioclase have a higher An-content. 3.Above infiltration and cation exchange resulted in an Al, Si, Ca (and K, providing the primary hydrous fluid contain K)-rich fluid. 4.Under suitable conditions, the solute in the fluid precipitated to form phengite firstly. After the K element in the fluid was consumed up, ziosite or epidote was formed. If the fluid did not contain any K. element, only ziosite or epidote was precipitated. For those eclogites, where all omphacite had been replaced by symplectite before infiltration, neither element exchange occurred, nor did phengite or epidote form during the infiltration. At the last stage, the garnet was oxidized and breakdown: garnet + H2O = epidote + hornblende + hematite, due to more and more fluid intruding into the eclogite. At this time, all the peak minerals were replaced by amphibolite-phase ones, and the eclogite transformed to an amphibolite completely. Tentative pressure calculation indicates that the infiltration occurred at 3-6kbar (about 10-20km depth), where the deformation mechanics transformed from brittle to ductile yield. At such depth, the surface water can permeate the rocks through fault system, causing a rapid cooling.

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Influences of seven organic modifiers, including urea, methanol (MeOH), dioxane (DIO), tetrahydrofuran (THF), acetonitrile (ACN), 1-propanol (1-PrOH) and 2-propanol (2-PrOH), on the solute retention and the electrokinetic migrations in micellar electrokinetic capillary chromatography (MEKC) are investigated with sodium dodecyl sulfate (SDS) micelle as pseudostationary phase. It is observed that in the limited concentration ranges used in the MEKC systems the effect of organic modifier concentration on the retention can be described by the equation logk'=logk'(w)-SC for most binary aqueous-organic buffer, but deviations from this retention equation are observed at ACN and particularly THF as organic modifiers. With parameter S as a measure of the elutropic strength, the elutropic strength of the organic modifiers is found to follow a general order urea DIO, while THF is found to be the most abundant modifier in selectivity among the organic modifiers studied. The electroosmotic mobility decreases linearly with increasing modifier concentrations. The strength of modifiers to suppress the electroosmotic mobility follows the order urea < MeOH, ACN < DIO, THF, 1-PrOH, 2-PrOH. The addition of ACN affects the electrophoretic mobility of the SDS micelle in different patterns depending on the buffer composition used, while the addition of the other modifiers leads to a rough linear decrease of the electrophoretic mobility of the SDS micelle. The suppressing strength of THF on the electrophoretic mobility of the SDS micelle is strongly related to the buffer composition, whereas the suppressing strength for the other modifiers follows the sequence urea < MeOH < DIO, 1-PrOH, 2-PrOH. The migration time window is expanded by the use of organic modifiers. Urea and MeOH have the least expanding strength while ACN, DIO, THF, 1-PrOH and 2-PrOH have the highest expanding strength on the migration time window.