外源水杨酸(SA)对高温胁迫下葡萄幼苗耐热性诱导研究

为探讨外源水杨酸(SA)对高温胁迫下葡萄幼苗耐热性的影响,以二年生克瑞森无核葡萄扦插苗为试验材料,对清洗干净的葡萄叶片喷施浓度为150μmol/L的水杨酸(SA)溶液,之后置于45℃高温胁迫10,30,60,120,240,480min,以喷施蒸馏水后置于45℃高温胁迫10,30,60,120,240,480min为对照,研究外源水杨酸对可溶性蛋白含量、蛋白激酶活性、游离脯氨酸含量、电解质渗透率、丙二醛含量生理指标的影响。结果表明,高温胁迫下外源水杨酸(SA)增加可溶性蛋白和游离脯氨酸的含量;外源水杨酸诱导葡萄叶片蛋白激酶活性,促进蛋白磷酸化反应。可溶性蛋白含量变化与蛋白激酶活性的变化具有高度的一致性,即胁迫60min时可溶性蛋白含量增加到最大,蛋白激酶活性也同时增高到最大值;随着胁迫时间的延长(60min),外源水杨酸显著降低丙二醛的含量和相对电导率。外源水杨酸随着高温胁迫时间的延长(60min)可以显著增加葡萄幼苗叶片内可溶性蛋白和游离脯氨酸含量,降低丙二醛含量和电解质渗透率,显著降低细胞膜质过氧化伤害;增强蛋白激酶活性,促进蛋白磷酸化的反应,提高葡萄的耐热性。     

缓释外源一氧化氮(NO)与缓释水杨酸(SA)对盐胁迫下冬小麦生理特性的影响

为探讨缓释外源一氧化氮供体硝普钠(SNP,一种外源NO供体)和水杨酸(SA),添加到土壤中缓解植物盐胁迫的效应及其机理。研究以冬小麦(山农22)为试验材料,采用盆栽试验的研究方法,以常规固体SNP和SA粉末处理为对照,研究了缓释外源NO(SRSNP)与SA(SRSA)对滨海盐土上冬小麦生理特性的影响,结果表明:SNP和SA均能够缓解盐胁迫对冬小麦生长的抑制作用。缓释SNP和缓释SA可以显著提高盐胁迫下冬小麦的发芽率,提高叶片叶绿素含量,进而促进光合作用;提高了小麦各叶位超氧化物歧化酶(SOD)、过氧化物歧化酶(POD)和过氧化氢酶(CAT)活性以及脯氨酸和可溶性蛋白含量;降低了超氧阴离子(O_2~--)产生速率、过氧化氢(H_2O_2)和丙二醛(MDA)含量,减轻了膜脂过氧化伤害。与直接添加进入土壤的SNP和SA相比,缓释外源NO与缓释SA可以在较长时间内保持SNP和SA对小麦盐胁迫的缓解效应,显著改善了冬小麦的生理特性,提高了小麦的耐盐性,促进了小麦的生长。     

灌浆期高温胁迫下外源水杨酸对小麦旗叶抗氧化生理特性的影响

为探讨外源水杨酸(SA)对缓解小麦花后高温伤害的作用,本研究于2019—2020年进行盆栽试验,以扬麦18号为材料,在田间增温棚中进行花后15~19 d的高温胁迫处理,比较不同时期预喷施外源SA处理下小麦的抗氧化生理特性。结果表明,高温胁迫处理导致丙二醛(MDA)和过氧化氢(H₂O₂)含量增加,旗叶超氧阴离子( {{\mathrm{O}}_2}^{.-})产生速率加快,小麦细胞膜脂过氧化程度加剧,对小麦旗叶造成损害;喷施外源SA后,灌浆期小麦旗叶超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)等抗氧化酶活性有所提高,抗逆指标苯丙氨酸解氨酶(PAL)和多酚氧化酶(PPO)活性提高,表明外源SA增强了小麦对高温环境的抵抗能力;不同时期喷施外源SA后,开花期预喷施SA处理相对其他处理缓解高温胁迫伤害效果最好。综上,喷施外源SA可通过提高小麦旗叶抗氧化酶和抗逆酶的活性缓解灌浆期高温胁迫对小麦旗叶的损伤程度,且开花期喷施效果较佳。本研究结果为减轻高温对小麦生产的危害提供了新的技术途径。     

外源水杨酸(SA)对NaCl胁迫下棉花幼苗生理生化特性的影响

以棉花幼苗为试验材料,在液培条件下,研究叶面喷施0.1mmol/L SA对100mmol/L NaCl胁迫下棉花幼苗生理特性的影响。结果表明:每隔一天向叶面喷施0.1mmol/L SA较每天和每隔两天喷施更能显著缓解NaCl胁迫对棉花幼苗造成的伤害,可明显提高抗氧化酶的活性、可溶性蛋白含量和游离脯氨酸含量;降低叶片的超氧阴离子产生速率、H2O2含量以及丙二醛(MDA)含量。但是每天喷施导致过量SA对棉花幼苗盐胁迫的缓解作用显著降低甚至加剧盐伤害。因此,每隔一天喷施SA可以通过提高抗氧化酶活性等途径提高棉花幼苗的抗盐性,减轻和缓解NaCl胁迫对棉花幼苗的伤害。     

水杨酸对高温胁迫下水稻幼苗抗热性的影响

以"西农优1号"水稻品种为材料,研究了水杨酸(SA)预处理对高温胁迫下水稻幼苗抗热性的影响,结果表明:0.5 mmol·L-1 SA预处理可减缓水稻幼苗的电解质渗出,降低MDA含量和超氧阴离子产生速率,提高高温胁迫下水稻幼苗体内过氧化氢、脯氨酸、可溶性糖、可溶性蛋白质、抗坏血酸和GSH的含量.表明SA预处理可提高高温胁迫下水稻幼苗的抗热性.     

外源一氧化氮与水杨酸对盐胁迫下小麦幼苗生理特性的影响

在液培条件下,以小麦(山农22号)为试验材料,外源一氧化氮(Nitric oxide, NO)供体硝普钠(Sodiumnitroprusside,SNP)和水杨酸(Salicylicacid,SA)作为调控物质,研究外源NO和SA单独及复配施用对120mmol·L~(-1)NaCl胁迫下小麦生长及生理特性的影响。结果表明,120mmol·L~(-1)NaCl胁迫严重抑制了小麦幼苗的生长,添加适宜浓度的SNP(100μmol·L~(-1))或SA(100μmol·L~(-1))均能显著缓解盐胁迫对小麦造成的伤害。而与单独添加SNP或SA相比,SA+SNP复合调控更能明显降低盐胁迫诱导的活性氧(Reactive oxygen species, ROS)积累、丙二醛(Malondialdehyde,MDA)含量以及电解质渗出率;提高小麦叶绿素含量、抗氧化酶活性和脯氨酸含量,从而提高其抗盐性;通过提高根系活力来促进对矿质元素的吸收,从而提高小麦幼苗的干物质积累;同时抑制了小麦对Na的吸收,以此减缓盐胁迫的毒害。由此说明NO与SA在缓解小麦幼苗盐胁迫中表现出积极的协同作用。试验各处理中施用50μmol·L~(-1) SA+50μmol·L~(-1) SNP的处理缓解小麦盐胁迫的效果最为明显。     

外源NO对NaCl胁迫下山葡萄叶片叶绿素荧光和抗氧化酶活性的影响

为探究NO对山葡萄耐盐性影响的生理机制,以1年生双丰山葡萄扦插苗为试材,采用营养液栽培方法,研究了外源NO供体硝普钠(SNP)处理对50 mmol·L-1 NaCl胁迫下山葡萄叶片叶绿素含量、叶绿素荧光参数和抗氧化酶活性的影响.结果表明,外源NO能显著提升盐胁迫下山葡萄叶片超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性,减少丙二醛(MDA)的产生和积累,保护光合机构免受活性氧伤害,从而提高叶片叶绿素含量;另一方面,外源NO使盐胁迫下山葡萄叶片的PSⅡ最大光化学效率(Fv/Fm)、PSⅡ实际光化学效率(ΦPSⅡ)、光化学淬灭系数(qP)和保护性热耗散(ΦNPQ)升高,而初始荧光(Fo)和非调节性能量耗散(ΦNO)显著下降,表明外源NO通过保护性热耗散机制缓解盐胁迫引起的光抑制,增强光合电子传递效率,进而维持PSⅡ的正常功能,最终提高了山葡萄耐盐性.     

外源水杨酸对盐胁迫下毛豆种子萌发和幼苗生理特性的影响

实验以毛豆品种双福"7"号为实验材料,在150 mmol/L Na Cl胁迫处理下,研究添加不同浓度(0、0.5、1.0、1.5、2.0和2.5 mmol/L)SA(水杨酸)对毛豆种子萌发和幼苗生理特性的影响。结果发现,外源SA可在一定程度上缓解盐胁迫对毛豆种子萌发和幼苗生长的影响。其中,添加0.5、1.0和1.5 mmol/L的SA对盐胁迫条件下种子的发芽指标显著提高;幼苗生的长指标显著增加;但干质量差异不显著,电导率和丙二醛(MDA)含量显著降低。结果表明,0.5~1.5 mmol/L的SA处理,可有效缓解毛豆的盐伤害,尤其添加1.0 mmol/L的SA效果最佳,2.0~2.5 mmol/L的SA处理未见明显缓解,甚至使毛豆的盐胁迫伤害加重。     

外源亚精胺对盐胁迫下黄瓜幼苗活性氧代谢的影响

采用营养液水培,研究了盐胁迫下外源亚精胺(Spd)对抗盐能力不同的2个黄瓜品种幼苗叶片和根系内活性氧(ROS)水平和抗氧化酶活性的影响.结果表明,外源Spd降低了50 mmol/L NaCl胁迫下幼苗体内O-.2产生速率、H2O2和丙二醛(MDA)含量,提高了抗氧化酶SOD、POD和CAT的活性;与抗盐性较强的"长春密刺"品种相比,Spd处理对抗盐性较弱的"津春二号"品种效果更明显.表明外源Spd处理通过促进盐胁迫下植株体内抗氧化酶活性的提高,降低ROS水平,从而缓解NaCl对黄瓜幼苗的盐伤害.     

褪黑素对葡萄幼苗生长及硒富集的影响

  目的  探讨在硒胁迫下外源褪黑素对葡萄生长和硒富集的影响,筛选出能够促进葡萄生长和硒富集的最佳褪黑素浓度。  方法  以‘夏黑’葡萄扦插苗为材料,采用盆栽试验,研究了在硒胁迫下褪黑素对葡萄幼苗生长、生理及硒富集的影响。  结果  不同浓度的褪黑素在一定程度上提高了葡萄幼苗的生物量和提高了根冠比,其中浓度为150 μmol L?1的褪黑素对葡萄幼苗地上部分生物量的提高幅度最大(18.22%)。褪黑素处理也在一定程度上增加了葡萄幼苗叶绿素和类胡萝卜素含量,提高了光合能力和抗氧化酶活性,降低了脯氨酸含量、可溶性蛋白含量、相对电导率和丙二醛含量。不同浓度褪黑素均提高了葡萄幼苗的硒含量,其中浓度为150 μmol L?1的褪黑素对葡萄幼苗地上部分硒含量的提高幅度最大(112.71%)。回归分析表明,褪黑素浓度与葡萄幼苗根系生物量、地上部分生物量、根系硒含量和地上部分硒含量均存在二次多项式或线性回归关系。  结论  外源褪黑素能促进硒胁迫下的葡萄生长和硒富集,其中以150 μmol L?1的浓度为最佳。     

Identification of oxidation products of (-)-epigallocatechin gallate and (-)-epigallocatechin with H(2)O(2)

(-)-Epigallocatechin gallate (EGCG) and (-)-epigallocatechin (EGC) are two important antioxidants in tea. They also display some antitumor activities, and these activities are believed to be mainly due to their antioxidative effects. However, the specific mechanisms of antioxidant action of tea catechins remain unclear. In this study are isolated and identified two novel reaction products of EGCG and one product of EGC when they were reacted separately with H(2)O(2). These products are formed by the oxidation and decarboxylation of the A ring in the catechin molecule. This study provides unequivocal proof that the A ring of EGCG and EGC may also be an antioxidant site. This study also indicates an additional reaction pathway for the oxidation chemistry of tea catechins.     

Excretion of (14)C-fumonisin B(1), (14)C-hydrolyzed fumonisin B(1), and (14)C-fumonisin B(1)-fructose in rats.

14C-Fumonisin B(1) (FB(1)) was produced by Fusarium proliferatum M-5991 in modified Myro liquid medium and purified to >95% purity with a specific activity of 1.7 mCi/mmol. Nine male and nine female F344/N rats were each dosed by gavage with 0.69 micromol of (14)C-FB(1), (14)C-hydrolyzed FB(1), or (14)C-FB(1)-fructose/kg body weight. Urinary excretion of (14)C-FB(1) and (14)C-FB(1)-fructose was 0.5% and 4.4% of the total dose, respectively, and was similar between male and female rats. Urinary excretion of (14)C-hydrolyzed HFB(1) was significantly greater (P > 0.05) in female rats as compared with male rats (17.3% vs 12.8% of the total dose, respectively). There were no significant (P > 0.05) differences in biliary excretion of the three fumonisin compounds with a mean of 1. 4% of the dose excreted at 4 h after dosing. Lesser amounts continued to be excreted up to 9.25 h after dosing. Although biliary excretion of the (14)C-FB(1), (14)C-hydrolyzed FB(1), and (14)C-FB(1)-fructose was similar, increased urinary excretion of the (14)C-hydrolyzed FB(1) as compared to (14)C-FB(1) and (14)C-FB(1)-fructose indicated a greater absorption of the hydrolyzed form.     

(三唑基-~(14)C-)粉锈宁的标记合成

本文报道了(三唑基-14C)-粉锈宁的制备。由14C-甲酸和重碳酸氨基胍形成(5-14C)-3-氨基-1,2,4-三唑,再经重氮化脱氨得到(5-14C)-1,2,4-三唑,最后再与对氯酚和二氯片呐酮反应得到(三唑基-14C)-粉锈宁。放化收率为26％(从甲酸-14C计),放化纯度大于95％。     

Chemoenzymatic synthesis of homochiral (R)- and (S)-karahanaenol from (R)-limonene

Terpinolene oxide, a monoterpene belonging to the p-menthane group, is easily derived from naturally abundant (R)-limonene. It was isomerized with montmorillonite clay catalyst to karahanaenone (2,2, 5-trimethylcyclohept-4-en-1-one) by ring enlargement. The enantiomers of the corresponding alcohol, karahanaenol (2,2, 5-trimethylcyclohept-4-en-1- ol), known for their individual organoleptic properties, were resolved through Pseudomonas cepacia lipase mediated enantiospecific alcoholysis of its acetate derivative.     

Theoretical speciation of ethylenediamine-N-(o-hydroxyphenylacetic)-N'-(p-hydroxyphenylacetic) acid (o,p-EDDHA) in agronomic conditions

The presence of ethylenediamine-N-(o-hydroxyphenylacetic)-N'-(p-hydroxyphenylacetic) acid (o,p-EDDHA) as the second largest component in commercial EDDHA iron chelates has recently been demonstrated. Here is reported the speciation of o,p-EDDHA by the application of a novel methodology through the determination of the complexing capacity, protonation, and Ca(2+), Mg(2+), Cu(2+), and Fe(3+) stability constants. The pM values and species distribution in solution, hydroponic, and soil conditions were obtained. Due to the para position of one phenol group in o,p-EDDHA, the protonation constants and Ca and Mg stability constants have different values from those of o,o-EDDHA and p,p-EDDHA regioisomers. o,p-EDDHA/Fe(3+) stability constants are higher than those of EDTA/Fe(3+) but lower than those of o,o-EDDHA/Fe(3+). The sequence obtained for pFe is o,o-EDDHA/Fe(3+) >/= o,p-EDDHA/Fe(3+) > EDTA/Fe(3+). o,p-EDDHA/Fe(3+) can be used as an iron chelate in hydroponic conditions. Also, it can be used in soils with limited Cu availability.     

Binding studies of oxovanadium(V) with ovalbumins (OA)

The effect of protein oxovanadium(V) ion concentration and pH on the ratio of diffusion current (id/id₀) was studied in vanadium(V) ovalbumin-S and denatured ovalbumin systems. In both the cases marked decrease in diffusion current was observed at the respective pH values, indicating that binding takes place with cationic groups of the proteins. The binding sites (n) were found to be pH dependent. The uniformity of logK and ΔG ⁰ value at all pH values indicated the involvement of same sites in interaction. Furthermore, the linear scatchard plots in both the systems supported the involvement of single class of independent sites in oxovanadium(V) anion interaction. The difference in binding sites (n) has been attributed to the folded structure of ovalbumin-S while unfolded one of denatured ovalbumin.     

Effect of pH on interaction between As(III) or As(V) and manganese(IV) oxide

The efficiency of As(III) oxidation by MnO₂, and retention of oxidation products varies with system pH. Maximum retention by hydrous Mn(IV) oxide occurs at pH < 5, declining at higher pH to about half total As at pH 10. The adsorption capacities of pyrolusite and cryptomelane at pH ～6.5 for As(V) species were 10 and 25 mmol kg^?1, respectively. HMO surface saturation (～10 mmol kg^?1) was reached with equilibrium As(V) levels of 5 to 8 × 10^?6 M but this was supplemented at higher levels by an absorption process where uptake increased linearly with concentration (e.g., 68 mmol kg^?1 with 2 × 10^?5 M As(V)). Added As(III) was avidly oxidized and most product retained at pH 3. At higher pH increasing amounts of As(III) remained unoxidized due to initial reactions apparently blocking access to internal pores. Added Na⁺ reduced the amount of As retained by the HMO, with the phosphate salt having a significant effect. Extraction studies confirmed that most As could be released by exposure to reducing agents or chelating agents (EDTA). The environmental significance of the results has been considered.