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1.
植物NHX属于Na＋/H＋逆向转运蛋白NHE/NHX亚家族的成员,为阳离子逆向转运蛋白家族的一个亚类,具有调节细胞内pH值和Na＋的浓度及维持细胞内离子稳态等多种功能。为进一步开发新疆盐生植物耐盐相关基因资源,本研究以盐生植物花花柴为材料,利用分子克隆技术,从总RNA中克隆编码Na＋/H＋逆向转运蛋白基因。依测序结果判断已从花花柴cD-NA中克隆到1253 bp的NHX基因片段,并对该序列进行数据库搜索和对序列比对分析。结果显示一致性达到68.77%,可以用于构建植物表达载体进行相应的功能鉴定。 相似文献
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Adenosine triphosphate (ATP)-binding cassette (ABC) transporters convert chemical energy from ATP hydrolysis to mechanical work for substrate translocation. They function by alternating between two states, exposing the substrate-binding site to either side of the membrane. A key question that remains to be addressed is how substrates initiate the transport cycle. Using x-ray crystallography, we have captured the maltose transporter in an intermediate step between the inward- and outward-facing states. We show that interactions with substrate-loaded maltose-binding protein in the periplasm induce a partial closure of the MalK dimer in the cytoplasm. ATP binding to this conformation then promotes progression to the outward-facing state. These results, interpreted in light of biochemical and functional studies, provide a structural basis to understand allosteric communication in ABC transporters. 相似文献
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偶联钠离子转运草酰乙酸脱羧酶是第一个被发现具有初级钠离子泵活性脱羧酶家族成员,由α,β,γ三个亚基以及生物素组成。由于其脱羧反应对柠檬酸发酵途径具有关键作用,并且在脱羧过程中偶联钠离子输出,该酶已受到学术界广泛关注。目前,该酶已在包括克雷伯菌属(Klebsiella)、沙门氏菌属(Salmonella)和弧菌属(Vibrio)等多个属细菌中被发现,并且其生理学基本特征已被鉴定。在肺炎克雷伯菌(Klebsiella pneumoniae)中,该酶中参与偶联脱羧反应钠离子输出重要氨基酸活性位点通过拓扑学分析、定点突变等方法被深入地进行鉴定,在此基础上能量偶联模型被提出以解释该酶偶联钠离子输出脱羧反应机制。本文对以上研究进展进行综述并对该酶未来研究方向加以展望。 相似文献
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Imura A Tsuji Y Murata M Maeda R Kubota K Iwano A Obuse C Togashi K Tominaga M Kita N Tomiyama K Iijima J Nabeshima Y Fujioka M Asato R Tanaka S Kojima K Ito J Nozaki K Hashimoto N Ito T Nishio T Uchiyama T Fujimori T Nabeshima Y 《Science (New York, N.Y.)》2007,316(5831):1615-1618
alpha-klotho was identified as a gene associated with premature aging-like phenotypes characterized by short lifespan. In mice, we found the molecular association of alpha-Klotho (alpha-Kl) and Na+,K+-adenosine triphosphatase (Na+,K+-ATPase) and provide evidence for an increase of abundance of Na+,K+-ATPase at the plasma membrane. Low concentrations of extracellular free calcium ([Ca2+]e) rapidly induce regulated parathyroid hormone (PTH) secretion in an alpha-Kl- and Na+,K+-ATPase-dependent manner. The increased Na+ gradient created by Na+,K+-ATPase activity might drive the transepithelial transport of Ca2+ in cooperation with ion channels and transporters in the choroid plexus and the kidney. Our findings reveal fundamental roles of alpha-Kl in the regulation of calcium metabolism. 相似文献
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野大麦耐盐适应性反应机制的研究 总被引：3，自引：1，他引：3
【目的】探讨野大麦的耐盐适应性反应机制。【方法】采用原子吸收和X-ray微区分析等方法分析野大麦[Hordeum brevisubulatum (Trin.) Link]在NaCl胁迫下幼苗生长、K+和Na+吸收、运输、分配及外排等生理响应。【结果】在NaCl≤350 mmol•L-1时，茎叶和根系的干重变化不明显，盐浓度的增加对根生长的抑制作用小于茎叶，根Na+含量增加的幅度小于茎叶、茎叶和根中K+含量均下降，但茎叶可维持较高的K+含量；野大麦具有较强的K+-Na+吸收选择性；低盐胁迫时Na+主要贮存于液泡和细胞间质；高盐胁迫时主要通过外排Na+来维持体内离子平衡。【结论】野大麦在NaCl≤350mmol•L-1时生长正常，其耐盐性与根拒绝吸收Na+及茎叶维持高K+含量有关，Na+区域化与外排可能是野大麦主要的耐盐适应性反应机制。 相似文献
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Proton pumps in the plasma membrane of plants and yeasts maintain the intracellular pH and membrane potential. To gain insight into the molecular mechanisms of proton pumping, we built an atomic homology model of the proton pump based on the 2.6 angstrom x-ray structure of the related Ca2+ pump from rabbit sarcoplasmic reticulum. The model, when fitted to an 8 angstrom map of the Neurospora proton pump determined by electron microscopy, reveals the likely path of the proton through the membrane and shows that the nucleotide-binding domain rotates by approximately 70 degrees to deliver adenosine triphosphate (ATP) to the phosphorylation site. A synthetic peptide corresponding to the carboxyl-terminal regulatory domain stimulates ATPase activity, suggesting a mechanism for proton transport regulation. 相似文献
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Alteration of alpha 1 Na+,K(+)-ATPase 86Rb+ influx by a single amino acid substitution 总被引：3，自引：0，他引：3
The sodium- and potassium-dependent adenosine triphosphatase (Na+,K(+)-ATPase) maintains the transmembrane Na+ gradient to which is coupled all active cellular transport systems. The R and S alleles of the gene encoding the Na+,K(+)-ATPase alpha 1 subunit isoform were identified in Dahl salt-resistant (DR) and Dahl salt-sensitive (DS) rats, respectively. Characterization of the S allele-specific Na+,K(+)-ATPase alpha 1 complementary DNA identified a leucine substitution of glutamine at position 276. This mutation alters the hydropathy profile of a region in proximity to T3(Na), the trypsin-sensitive site that is only detected in the presence of Na+. This mutation causes a decrease in the rubidium-86 influx of S allele-specific sodium pumps, thus marking a domain in the Na+,K(+)-ATPase alpha subunit important for K+ transport, and supporting the hypothesis of a putative role of these pumps in hypertension. 相似文献
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过硫酸盐活化技术处理地下水中的BTEX及其动力学 总被引：2，自引：0，他引：2
利用模拟苯、甲苯、乙苯和二甲苯(BTEX)污染的地下水,研究过硫酸盐(Na2S2O8)活化氧化处理BTEX污染。结果表明,过硫酸盐对BTEX污染的地下水具有很好的处理能力。当Na2S2O8/BTEX(摩尔比)=20,Na2S2O8/Fe2+(摩尔比)=8的时候,BTEX的处理效果最好,甲苯、乙苯和二甲苯去除率均能达到80%以上;而苯的去除率稍低。整个试验过程中体系均处于强氧化环境,pH值降至3以下。过硫酸盐对苯、甲苯、乙苯和二甲苯(BTEX)的去除过程均符合二级反应动力学:1/ct=kt+1/c0。 相似文献
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首次建立了Na+-Ti(SO4)2法检测草鱼中孔雀石绿残留的方法:孔雀石绿溶于浓硫酸显黄色,稀释后显暗黄色,Ti(SO4)2使其褪色,加入Na+变为白色沉淀,依据沉淀量对孔雀石绿残留进行定量分析。优化实验条件,采用pH=7.4、硫酸钛和氯化钠的浓度均为2.0 mol/L时,可有效地检测孔雀石绿残留。方法学实验结果表明:该方法最低检测量为0.08 mg/kg,在草鱼肌肉和肝脏中的回收率分别为65.00%~75.63%,63.75%~71.35%,相对标准偏差分别为4.82%~1.89%,4.93%~1.97%。该方法快速、简单、灵敏、准确,依据白色沉淀仅凭肉眼即可进行初筛,适合于快速检测孔雀石绿在水产品中的残留。 相似文献
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首次建立了Na+-Ti(SO4)2法检测草鱼中孔雀石绿残留的方法:孔雀石绿溶于浓硫酸显黄色,稀释后显暗黄色,Ti(SO4)2使其褪色,加入Na+变为白色沉淀,依据沉淀量对孔雀石绿残留进行定量分析。优化实验条件,采用pH=7.4、硫酸钛和氯化钠的浓度均为2.0 mol/L时,可有效地检测孔雀石绿残留。方法学实验结果表明:该方法最低检测量为0.08 mg/kg,在草鱼肌肉和肝脏中的回收率分别为65.00%~75.63%,63.75%~71.35%,相对标准偏差分别为4.82%~1.89%,4.93%~1.97%。该方法快速、简单、灵敏、准确,依据白色沉淀仅凭肉眼即可进行初筛,适合于快速检测孔雀石绿在水产品中的残留。 相似文献
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以缢蛏(Sinonovacula constricta)为实验对象,研究密度(60和120粒/m2)和盐度(20和30)对缢蛏渗透调节和抗氧化水平的影响,实验持续72 h,检测了缢蛏血淋巴Na+浓度和K+浓度,肝胰腺组织中超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量,以及鳃组织中Na+/K+-ATPase活性、钠氢逆向转运蛋白(Na+/H+ antiporter)和膜泡质子泵(V-ATPase)基因表达水平。结果显示：密度和盐度对缢蛏血淋巴Na+浓度、K+浓度无显著交互影响作用,高盐组Na+浓度、K+浓度显著高于对照组;在实验12 h和24 h时,密度和盐度对Na+/K+-ATPase活性的影响具有显著交互作用,并且高盐度组和高密度组Na+/K+-ATPa... 相似文献
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NaCl胁迫下栽培型番茄Na+、K+吸收、分配和转运特性 总被引：8，自引：2，他引：6
【目的】明确盐分胁迫下栽培型番茄离子吸收、分配和转运特性。【方法】以栽培番茄为试材,以NaCl溶液为盐分胁迫条件,通过苗期耐盐性鉴定,采用原子吸收光谱法测定不同耐盐性番茄品种体内离子含量,对盐分胁迫下番茄体内离子积累、分布和转运机制进行系统分析。【结果】番茄对Na+的吸收随盐分处理浓度和时间的增加而增加,在各器官的积累量顺序为根＞茎＞叶。对于较耐盐品种,Na+在体内的积累总量低于盐敏感品种。盐分胁迫后,番茄叶片、茎和根系中Na+/K+比均随NaCl浓度的升高而升高。耐盐品种的Na+/K+比低于盐敏感品种。离子在体内的区域化分布情况是,较耐盐品种的Na+在根茎中的分配比例较高,盐敏感品种趋向于向叶片分配。K+在较耐盐品种的分布集中于叶片。在盐胁迫初期,盐分处理浓度超过200 mmol•L-1时,番茄植株对K+向地上部的选择运输性随着胁迫时间的延长呈现出下降的趋势。低于200 mmol•L-1时,表现出很好的选择运输性,耐盐品种的Sk/Na(运输)高于盐敏感品种,根系表现出更强的向地上部运输K+的能力。【结论】盐分胁迫下,叶片中较低的Na+含量和更强的向地上部运输K+的能力是番茄耐盐性的重要特征。 相似文献
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[目的]探讨羊草在盐碱胁迫下的生理生化特性和K+、Na+含量的变化。[方法]在室内模拟不同pH盐碱土上种植羊草,并测定其生理生化指标和离子含量。[结果]随着土壤pH的逐渐升高和胁迫时间的延长,羊草体内的脯氨酸、可溶性蛋白、丙二醛的含量及氧化氢酶活性均随之增加,而后又逐渐降低。随着土壤pH的升高,羊草叶片的Na+含量逐渐增加,而K+含量逐渐减少,K+/Na+比值减小,但始终高于1。[结论]各项生理指标和K+、Na+含量的变化对维持羊草细胞的离子平衡起到了积极的调节作用。 相似文献
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Growth factors induce phosphorylation of the Na+/H+ antiporter, glycoprotein of 110 kD 总被引：30，自引：0，他引：30
The Na+/H+ antiporter, which regulates intracellular pH in virtually all cells, is one of the best examples of a mitogen- and oncogene-activated membrane target whose activity rapidly changes on stimulation. The activating mechanism is unknown. A Na+/H+ antiporter complementary DNA fragment was expressed in Escherichia coli as a beta-galactosidase fusion protein, and a specific antibody to the fusion protein was prepared. Use of this antibody revealed that the Na+/H+ antiporter is a 110-kilodalton glycoprotein that is phosphorylated in growing cells. Mitogenic activation of resting hamster fibroblasts and A431 human epidermoid cells with epidermal growth factor, thrombin, phorbol esters, or serum, stimulated phosphorylation of the Na+/H+ antiporter with a time course similar to that of the rise in intracellular pH. 相似文献
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大灰食蚜蝇对3种蚜虫的捕食作用研究 总被引：3，自引：1，他引：3
研究了大灰食蚜蝇对3种蚜虫的捕食作用,得到1,2,3龄幼虫对甘蓝蚜的捕食功能反应模型分别为Na=0.608 2 N/(1+0.608 2×0.113 2 N),Na=0.981 0 N/(1+0.981 0×0.011 7 N),Na=0.958 5 N/(1+0.958 5×0.004 6 N),日最大捕食量依次为8.8头、85.4头、217.4头;3龄幼虫对豌豆蚜虫的捕食功能反应模型为Na=1.178 7 N/(1+1.178 7×0.014 7 N),日最大捕食量为68.03头;1,2,3龄幼虫对桃蚜的捕食功能反应模型为Na=1.000 5 N/(1+1.000 5×0.095 8 N),Na=1.106 1 N/(1+1.106 1×0.018 0 N),Na=1.056 6 N/(1+1.056 6×0.006 0 N),日最大捕食量为10.44头,55.71头,166.67头。结果表明,利用大灰食蚜蝇防治蚜虫是具有一定潜力的。 相似文献
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The reaction K + NaBr --> KBr + Na is probed during the reactive collision by a continuous wave laser tuned to frequencies not resonant with excitation in either reagents or products. Transient [K..Br..Na] absorbs a laser photon giving [K..Br..Na](*), which can decompose to Na(*) + KBr. Emission from excited Na(*) at the sodium D lines provides direct evidence of laser absorption during the reaction. Different excitation spectra were observed, depending on which sodium D line was monitored. This difference is explicable if, in the absence of the laser, the reaction flux partially bifurcates to a second potential energy surface during the reaction. 相似文献
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Imaging elemental distribution and ion transport in cultured cells with ion microscopy 总被引：2，自引：0，他引：2
Both elemental distribution and ion transport in cultured cells have been imaged by ion microscopy. Morphological and chemical information was obtained with a spatial resolution of approximately 0.5 micron for sodium, potassium, calcium, and magnesium in freeze-fixed, cryofractured, and freeze-dried normal rat kidney cells and Chinese hamster ovary cells. Ion transport was successfully demonstrated by imaging Na+-K+ fluxes after the inhibition of Na+- and K+ -dependent adenosine triphosphatase with ouabain. This method allows measurements of elemental (isotopic) distribution to be related to cell morphology, thereby providing the means for studying ion distribution and ion transport under different physiological, pathological, and toxicological conditions in cell culture systems. 相似文献
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不同改良剂与石膏配施对滨海盐渍土离子组成的影响 总被引：5，自引：0，他引：5
针对滨海盐渍土的特点,采用4种盐碱土改良剂在滨海盐渍土上单独施用和与石膏配合施用,研究施用后对盐渍土离子组成的影响。结果表明:施用改良剂与石膏后,在0～40 cm土层,盐渍土中离子组成比例发生不同程度的变化。pH值、电导率、Na+、K+、Cl-和总碱度(HCO-3+CO23-)在盐渍土中分别降低了0.05～0.20、8～163μS.cm-1、10.35%～47.74%、12.07%～51.69%、3.39%～40.67%和20.18%～48.56%;Mg2+、Ca2+和SO24-的含量分别增加了3.06%～13.54%、15.58%～56.20%和12.24%～76.12%。结论:改良剂与石膏配施效果比单施改良剂好,其中腐殖酸与石膏配施的改良效果最佳。 相似文献