钙对盐胁迫下棉苗离子吸收分配的影响

研究了钙对NaCl胁迫下棉花幼苗体内离子分布的影响及其与根系质膜H^ -ATP酶、液泡膜H^ -dATP酶和H^ -PP酶活性的关系。不同器官离子含量和根系横切面X-射线微区分析结果表明,NaCl胁迫下外源钙明显减少棉花幼苗对Na^ 的吸收及其向茎杆、叶片的运输,增加对K^ 和Ca^2 的吸收及其向茎相杆、叶片的运输,增强棉苗体内的盐分区域化分配,提高根冠比和干物质积累,根系电解质渗漏率下降,钙明显提高盐胁迫下幼根细胞质膜H^ -ATP酶、液泡膜H^ -ATP酶和H^ -PP酶的活性,与钙调节棉花对离子的吸收、分配相一致,说明这些酶可以为根细胞中的Na^ 在液泡中积累以及K^ 、Ca^2 的选择性吸收和运输提供动力。     

钙对盐胁迫下棉苗离子吸收分配的影响

研究了钙对NaCl胁迫下棉花幼苗体内离子分布的影响及其与根系质膜H+-ATP酶、液泡膜H+-ATP酶和H+-PP酶活性的关系。不同器官离子含量和根系横切面X-射线微区分析结果表明,NaCl胁迫下外源钙明显减少棉花幼苗对Na+的吸收及其向茎杆、叶片的运输,增加对K+和Ca2+的吸收及其向茎杆、叶片的运输,增强棉苗体内的盐分区域化分配,提高根冠比和干物质积累,根系电解质渗漏率下降。钙明显提高盐胁迫下幼根细胞质膜H+-ATP酶、液泡膜H+-ATP酶和H+-PP酶的活性,与钙调节棉花对离子的吸收、分配相一致,说明这些酶可以为根细胞中的Na+在液泡中积累以及K+、Ca2+的选择性吸收和运输提供动力。     

钙对高温胁迫下烟草幼苗抗氧化代谢的影响

用10mmol/LcaCl2溶液处理烟草幼苗,能减缓高温胁迫所引发的一些胁变反应,如叶绿素破坏、积累膜脂质过氧化产物MDA,增加细胞膜相对透性,降低内源抗氧化剂（AsA,GSH）和脯氨酸含量,在高温胁迫下,SOD和CAT等抗氧化酶活性呈现先升后降的变化趋势。恢复生长以后,钙处理和未处理的烟草幼苗其内源抗氧化剂含量和抗氧化酶活性均有不同程度的回升。由此认为,高温胁迫后烟草幼苗体内抗氧化酶活性受抑,活性氧积累以及由此引发的膜脂过氧化作用是烟草幼苗高温伤害的原因之一。     

水分胁迫期间及胁迫解除后桃树叶片中的碳水化合物代谢

水分胁迫期间、盆栽桃幼树叶片中淀粉和蔗糖含量降低,山梨醇、葡萄糖和果糖则升高;淀粉酶、6－磷酸醛糖还原酶（A6PR）、酸性转化酶（AI）和蔗糖合酶（SS）涤性升高,ADPG焦磷酸化酶（ADPGPPase）、中性转化酶（NI）、山梨醇脱氢酶（SDH）和磷酸蔗糖合酶（SPS）的活性降低。胁迫解除后,淀粉和葡萄糖含量恢复,山梨醇和果糖仍高于对照;A6PR、SDH和ADPGPase活性维持在原水平上;淀粉酶活性恢复;SPS活性增加而AI活性降低。     

干旱胁迫下腐植酸对燕麦叶片非结构性碳水化合物代谢的影响

以燕麦品种'燕科2号'为试验材料,采用盆栽方式,分别在正常供水(75％田间持水量)、中度干旱胁迫(60％田间持水量)和重度干旱胁迫(45％田间持水量)3个水分条件下喷施腐植酸(HA)和等量清水(CK),对燕麦叶片中非结构性碳水化合物(NSC)含量及相关酶活性和籽粒产量进行测定,以明确腐植酸在干旱胁迫下对燕麦叶片非结构性...     

甘薯幼苗对NaCl胁迫的生理响应及外源钙的缓解效应

以甘薯品种‘徐薯22’为试验材料,研究了不同浓度NaCI胁迫对甘薯幼苗生根、叶片抗氧化能力、渗调物质含量、光合气体交换参数、荧光参数及叶片离子含量的影响及不同浓度Ca^2＋处理对300mmol·L^-1NaCl胁迫的缓解效应。结果表明,低浓度NaCl（50和100mmol·L^-1）胁迫对甘薯幼苗生根及叶片相对电导率和MDA含量影响较小,随着盐度的增加,叶片SOD活性呈先增加后降低趋势,脯氨酸和可溶性糖含量持续增加,叶片Pn、Tr、Gs、F√Fm、RC／CS0、TR0／CS0、ET0／CS0、ФE0及K^＋、Ca^2＋含量、K^＋／Na^＋不断降低,ФD0和Na^＋含量升高;高浓度NaCl（300mmol·L^-1）胁迫下,甘薯幼苗的正常生理代谢受到显著抑制。适当浓度外源ca2’能显著缓解Nacl胁迫对甘薯幼苗的毒害作用,能促进盐胁迫下甘薯幼苗生根,改善细胞的渗透平衡,提高渗透调节能力,降低膜脂过氧化程度,使甘薯叶片维持较高的Fv√Fm、RC／CS0、TR0／CS0、ET0／CS0、ФE0和较低的ФD0,增强光合作用和气孔蒸腾作用效率,说明外施Ca^2＋是提高甘薯耐盐性的一种有效方法。     

叶施NO对NaCl胁迫下红砂幼苗叶片和根系中氮代谢酶及营养物质的影响

以当年生红砂（Reaumuria soongorica）幼苗为材料,采用盆栽实验,考察叶面喷施不同浓度(0、0.01、0.10、0.25、0.50、1.00 mmol·L^-1)NO供体硝普钠（SNP）对NaCl(300 mmol·L^-1)胁迫下红砂根、叶中可溶性蛋白、游离氨基酸和硝态氮含量,以及谷氨酰胺合成酶（GS）、谷氨酸合酶（GOGAT）、硝酸还原酶（NR）活性的影响,并采用主成分分析和隶属函数法筛选NO对NaCl胁迫缓解效应的氮代谢指标和最佳NO浓度,以探讨外源NO对NaCl胁迫下红砂缓解效应的氮代谢响应机制。结果表明:（1）在300 mmol·L^-1 NaCl胁迫处理下,红砂幼苗根、叶中可溶性蛋白、硝态氮含量以及GS、GOGAT、NR活性均比对照显著下降。（2）外源NO能显著提高盐胁迫下红砂叶、根中GS、GOGAT、NR活性和硝态氮含量,增加根中可溶性蛋白和游离氨基酸含量。（3）NR和GOGAT活性可用于评价NO对NaCl胁迫下红砂幼苗的缓解作用,外源NO（SNP）对红砂幼苗在NaCl胁迫下的缓解效果强弱表现为0.25 mmol·L^-1> 0.50 mmol·L^-1> 0.10 mmol·L^-1> 1.00 mmol·L^-1> 0.01 mmol·L^-1。研究发现,300 mmol·L^-1 NaCl胁迫显著抑制了红砂幼苗氮代谢,外源NO（SNP）有助于提高盐胁迫下红砂NR活性,加快硝态氮转化为铵态氮,促进红砂叶片和根中GS/GOGAT对转化物的同化,从而增强红砂幼苗的耐盐性,并以0.25 mmol·L^-1SNP处理时缓解作用最佳;NR和GOGAT活性可作为NO缓解盐胁迫的评价指标。     

低氧胁迫下钙对樱桃根系功能及氮代谢的影响

以樱桃组培苗‘吉塞拉5号’为试材,采用营养液水培控制溶氧浓度的方法,研究短期低氧胁迫下钙对其根系功能及氮代谢的影响.结果表明:与对照相比,低氧加钙处理的樱桃植株根系活力显著升高,根系呼吸速率抑制作用明显减轻,与氮代谢相关的硝酸还原酶(NR)、谷氨酰胺合成酶(GS)及谷氨酸脱氢酶(NADH-GDH)活性也显著升高,从而为低氧逆境下樱桃根系的吸收作用提供足够的能量,保证了糖酵解和电子传递的顺利进行,缓解了樱桃的低氧伤害,且10 mmol·L-1 Ca2+处理的缓解效果优于5 mmol·L-1处理;低氧缺钙处理的樱桃植株根系活力显著下降,根系呼吸速率抑制作用明显加重,NR、GS及NADH-GDH活性显著降低;表明适当提高生长介质中的Ca2浓度可缓解低氧胁迫对樱桃根系的伤害.     

NaCl胁迫对甘薯苗期生长、IAA代谢的影响及其与耐盐性的关系

随NaCl胁迫浓度的提高 ,甘薯苗期株高和叶面积生长受抑制 ;叶片IAA水平下降 ,而IAA氧化酶和POD活性提高 .不耐盐品种生长受抑制程度及IAA水平下降幅度均大于中耐盐品种和耐盐品种 ,叶片IAA氧化酶和POD活性上升的幅度大于中耐盐及耐盐品种 .同时浓度NaCl胁迫还引起了叶片绿原酸含量的增加 ,中耐盐品种栗子香和不耐盐品种胜利百号在 170mmol·L-1的NaCl浓度胁迫下 ,绿原酸含量上升达到最高值 ,耐盐品种徐薯 18绿原酸含量达到最高值的浓度是 2 5 5mmol·L-1,而后随NaCl胁迫浓度的提高 ,绿原酸含量均有下降 ,但仍高于对照 .     

NaCl胁迫及钙调节对青钱柳根部组织离子分布的影响

运用X-射线微区分析法研究了NaCl胁迫及钙调节下,青钱柳〔Cyclocarya paliurus(Batal.)Iljinskaja〕幼苗根部组织中离子的浓度和分布情况。结果表明,3.0和5.0 g.L-1NaCl胁迫下,青钱柳幼苗根部各层组织中Na 和Cl-的相对含量增加,K 、Ca2 和Mg2 的相对含量降低;5.0 g.L-1NaCl胁迫下加入3.0 g.L-1Ca(NO3)2后,Na 的相对含量降低,K 的相对含量增加,Cl-的相对含量变化较小。随NaCl浓度的升高,中柱和皮层中Cl-的相对含量增高;Na 大部分沉积在皮层及表皮上;K 由皮层进入中柱的比率增大;Ca2 由表皮进入皮层的比率减少,由皮层进入中柱的比率增大。5.0 g.L-1NaCl胁迫下加入高浓度Ca(NO3)2后,Cl-的分布比率变化不明显;Na 由表皮进入皮层的比率增加,从皮层进入中柱的比率下降;K 和Ca2 的分布比率变化不明显。高浓度NaCl胁迫破坏了青钱柳幼苗根部的离子平衡,加入外源Ca(NO3)2(1.0~3.0 g.L-1)后,缓解作用不明显。     

外源钙和亚精胺对NaCl胁迫条件下玉米幼苗体内离子平衡和多胺水平的调节

研究了钙离子和亚精胺对盐胁迫条件下玉米幼苗生长状况、电解质渗漏、离子含量和多胺水平的影响。结果表明盐胁迫下,钠离子和腐胺含量升高,质膜受到严重伤害,而钾离子、钙离子、亚精胺以及精胺水平降低。外加氯化钙和亚精胺不但能逆转氯化钠带来的离子平衡失调、多胺代谢紊乱,而且还能减轻氯化钠导致的生长抑制和质膜伤害。在盐胁迫条件下,二环己基胺引起多胺含量严重下降的情况在一定程度上能被外加氯化钙处理所缓解。这些结果提示,钙、多胺代谢以及盐渍环境下玉米生长之间可能存在一定的关系。     

Effect of chlorocholine chloride sprays on the carbohydrate composition and activities of sucrose metabolising enzymes in potato (Solanum tuberosum L.)

Chlorocholine chloride (CCC) was sprayed on a potato crop 25 days after sowing (DAS) at 5 day intervals for a total of 7 sprays. Activity of sucrose synthase (SS) in the sucrose cleavage direction was many fold higher than that of acid invertase in all the tissues. The activity of alkaline invertase was negligible. A sharp decline in the starch content of stolons of the CCC-sprayed crop was observed between 60 DAS and 70 DAS. This could divert the carbon towards tubers and thus enhancing its availability for starch synthesis. The CCC-treated crop, in general, had higher SS (cleavage) activity in stem, stolons and tubers. A higher sucrose content in the stem of the CCC-treated crop could be due to the high sucrose phosphate synthase (SPS) activity observed in this plant part. In tubers of CCC-treated crops a higher SS (cleavage) activity along with a high sucrose content in tubers during the active tuber filling stage could lead to better availability of UDP-glucose for its conversion to glucose-1-phosphate, which could enter into the amyloplast leading to higher starch content. High SPS activity in tubers of CCC-treated plants ensures that reducing sugars formed are reconverted efficiently to sucrose. The efficiency of developing tubers from CCC-sprayed plants to convert 14C sucrose fed through stolons into starch was about 2.5 times more than in the control.     

外源NO对NaCl胁迫下黄瓜幼苗氮化合物和硝酸还原酶活性的影响

采用营养液水培的方法,研究了外源一氧化氮(nitric oxide,NO)对50 mmol?L-1NaCl胁迫下黄瓜(Cucu-mis sativusL.)幼苗根系和叶片内硝酸还原酶(nitrate reductase,NR)活性、硝态氮(NO3--N)、铵态氮(NH4 -N)及可溶性蛋白含量的影响.结果表明:100μmol?L-1外源NO供体硝普钠(sodium nitroprusside,SNP)能明显提高NaCl胁迫下黄瓜幼苗叶片和根系内NR的活性,缓解由于盐胁迫造成的NO3--N含量的下降,减少NH4 -N在植株体内的过量积累,提高渗透调节物质可溶性蛋白的含量,从而减轻由于盐胁迫对黄瓜幼苗植株造成的伤害.     

热应激大鼠心肌钙代谢的变化及其机理探索

心肌细胞内钙离子对心功能的调节有着极其重要的作用。本研究观察了不同热应激强度下大鼠心肌细胞内质网、线粒体中钙含量,Ｃａ２＋－ＡＴＰ酶活力,内质网Ｃａ２＋主动转运速率及心肌ＡＴＰ含量的变化。研究结果表明,热应激大鼠心肌细胞内质网、线粒体钙含量随肛温升高显著下降;大鼠肛温达４２℃时,其钙含量分别较对照下降３２．２％和４６．５％;心肌细胞内质网和线粒体Ｃａ２＋－ＡＴＰ酶活力亦明显降低,线粒体Ｃａ２＋－ＡＴＰ酶活力下降幅度更为激烈。热应激大鼠心肌内质网Ｃａ２＋主动转运速率和Ｃａ２＋－ＡＴＰ酶活力变化趋势相同,且两者呈密切相关关系。热应激大鼠心肌ＡＴＰ含量亦随肛温升高大幅度降低,当动物肛温超过４２℃时,其可降至对照动物的３７．５％;热应激大鼠心肌ＡＴＰ含量的变化与内质网Ｃａ２＋－ＡＴＰ酶活力关系密切。实验结果提示：热应激心肌细胞质膜受损所致细胞Ｃａ２＋主动转运功能紊乱及心肌能量代谢障碍是心肌钙稳态失调的主要原因;心肌细胞钙代谢紊乱是诱导心肌细胞严重受损,导致热应激机体心血管功能失调,甚至心功能衰竭的重要机制     

NaCl胁迫对茄子嫁接苗叶片多胺代谢和ABA含量的影响

以日本引进的茄子设施栽培专用耐盐品种'Torvum Vigor'为砧木,栽培品种'苏崎茄'为接穗,研究了80 mmol·L-1 NaCl胁迫下茄子嫁接苗和自根苗生长、多胺代谢和ABA含量的变化.结果表明,在NaCl胁迫下,茄子嫁接苗的生长量、3种不同形态多胺(游离态、结合态和束缚态)和ABA含量均显著高于自根苗.NaCl胁迫显著增加了叶片精胺和ABA含量;腐胺和亚精胺含量在胁迫前期上升,后期下降.嫁接苗的腐胺和亚精胺含量降低幅度低于自根苗,而精胺和ABA含量上升幅度则高于自根苗.嫁接苗生长和多胺代谢受NaCl胁迫的影响小于自根苗,NaCl胁迫下ABA的快速积累和保持相对高的多胺含量与嫁接苗耐盐性有关.     

Growth and Carbohydrate Metabolism of Sulfobacilli

The moderately thermophilic acidophilic bacteria Sulfobacillus thermosulfidooxidans, strain 1269, S. thermosulfidooxidanssubsp. asporogenes, strain 41, and the thermotolerant strain S. thermosulfidooxidanssubsp. thermotolerans K1 prefer mixotrophic growth conditions (the concomitant presence of ferrous iron, thiosulfate, and organic compounds in the medium). In heterotrophic and autotrophic growth conditions, these sulfobacilli can grow over only a few culture transfers. In cell-free extracts of these sulfobacilli, key enzymes of the Embden–Meyerhof–Parnas, pentose-phosphate, and Entner–Doudoroff pathways were found. The role of a particular pathway depended on the cultivation conditions. All of the enzymes assayed were most active under mixotrophic conditions in the presence of Fe²⁺and glucose, suggesting the operation of all of the three major pathways of carbohydrate metabolism under these conditions. However, the operation of the Entner–Doudoroff pathway in strain 41 was restricted under mixotrophic conditions. After the first culture transfer from mixotrophic to heterotrophic conditions, the utilization of glucose occurred only via the Embden–Meyerhof–Parnas and Entner–Doudoroff pathways. After the first culture transfer from mixotrophic to autotrophic conditions, the activity of carbohydrate metabolism enzymes decreased in all of the strains studied; in strain K1, only the glycolytic pathway remained operative. The high activity of fructose-bisphosphate aldolase, remaining in strain 41 cells under these conditions, suggests the involvement of this enzyme in the reactions of the Calvin cycle or of gluconeogenesis.     

Effects of moderate ammonium enrichment on three submersed macrophytes under contrasting light availability

1. Increased ammonium concentrations and decreased light availability in a water column have been reported to adversely affect submersed vegetation in eutrophic waters worldwide. 2. We studied the chronic effects of moderate enrichment (NH₄–N: 0.16–0.25 mg L^?1) on the growth and carbon and nitrogen metabolism of three macrophytes (Ceratophyllum demersum, Myriophyllum spicatum and Vallisneria natans) under contrasting light availability in a 2‐month experiment. 3. The enrichment greatly increased the contents of free amino acids and nitrogen in the shoot / leaf of the macrophytes. This indicates that was the dominant N source for the macrophytes. 4. Soluble carbohydrate contents remained relatively stable in the shoot / leaf of the macrophytes irrespective of the treatments. Under ambient light, the starch contents in the shoot / leaf of C. demersum and M. spicatum increased with enrichment, whereas V. natans did not exhibit any change. The starch contents decreased in C. demersum, increased in M. spicatum and remained unchanged in V. natans after the combined treatment of enrichment and reduced light. 5. The enrichment did not affect the growth of the three macrophytes under the ambient light. However, it did suppress the growth of C. demersum and M. spicatum under the reduced light. The results indicate that a moderate enrichment was not directly toxic to the macrophytes although it might change their viability in eutrophic lakes in terms of the carbon and nitrogen metabolism.