绿原酸对莴苣生长的化感作用及其机理研究

酚酸类化合物是一类重要的化感物质,广泛存在于农作物等植物体内以及耕作土壤中,与植物的化感效应以及连作障碍密切相关。该研究以蔬菜类植物莴苣为受体,采用植物细胞和生理学方法,分析酚酸类化感物质绿原酸抑制莴苣生长的活性效应及其作用机理,以揭示绿原酸介导的化感作用及连作障碍机制。结果显示:(1)绿原酸对莴苣的根长、茎长以及鲜重等生长指标均表现出低浓度(0.1和1.0μmol/L)促进、高浓度(10、100和1 000μmol/L)抑制的活性作用模式,其在10μmol/L及以上浓度时对根长和鲜重具有显著抑制作用,但在各浓度下对莴苣茎长无显著影响。(2)绿原酸处理后,莴苣根尖细胞分裂指数明显下降,随处理浓度的升高,各分裂时期的细胞比例也显著降低,导致细胞分裂过程受阻。(3)较低浓度(0.1、1.0和10μmol/L)绿原酸对莴苣根尖细胞活力无明显影响,较高浓度绿原酸(100和1 000μmol/L)使莴苣根尖死细胞显著增多,根尖端绝大部分细胞失去活力。(4)DHE荧光染色显示,与对照相比,低浓度(0.1和1.0μmol/L)绿原酸对莴苣根部的活性氧积累无明显影响,当绿原酸处理浓度大于10μmol/L时,随处理浓度升高莴苣根部的活性氧积累明显大量增多。研究表明,绿原酸能够诱导莴苣体内活性氧产生并积累,从而导致莴苣细胞分裂受阻、细胞活力降低,最终影响莴苣幼苗的生长发育。     

二氢血根碱对莴苣幼苗根生长及其细胞分裂的影响

以莴苣幼苗为受体,用培养皿法检测从细果角茴香中分离得到的二氢血根碱对莴苣幼苗根生长和根毛发育的影响,并采用根尖细胞有丝分裂检测和单细胞凝胶电泳法对其可能的作用机制进行了初步研究.结果显示:较低浓度(25、50μmol/L)二氢血根碱能显著促进莴苣根的生长,较高浓度(200、300μmol/L)二氢血根碱显著抑制根的生长;二氢血根碱(10、20、30、40、50μmol/L)对莴苣幼苗根毛发育有极显著的抑制作用,且两者均表现了浓度依赖性.较低浓度(25、50μmol/L)二氢血根碱使根尖细胞有丝分裂指数显著增加,而对根尖细胞DNA没有显著影响;较高浓度(200、300μmol/L)二氢血根碱使根尖细胞有丝分裂指数显著下降,同时根尖细胞DNA受到显著性损伤.研究发现,低浓度的二氢血根碱对莴苣幼苗根生长的促进作用主要是由于根尖细胞有丝分裂活力增加所致;而高浓度二氢血根碱对莴苣幼苗根的抑制作用极可能是由于根尖细胞DNA受到损伤,使得细胞分裂活力降低,分裂期细胞数目减少,从而导致根生长受到抑制.     

8-甲氧基二氢血根碱化感潜能的评估

以莴苣幼苗为材料,检测了分离自细果角茴香的生物碱对莴苣幼苗根生长及根毛发育的影响。结果表明:50~200μmol·L-1浓度范围内,8-甲氧基二氢血根碱对莴苣幼苗根长显著抑制;10、20和30μmol·L-18-甲氧基二氢血根碱对莴苣幼苗根毛的长度和数量有显著的抑制作用,且抑制作用均表现了浓度依赖性。通过对莴苣根尖细胞有丝分裂研究发现,50μmol·L-1的8-甲氧基二氢血根碱能显著抑制根尖细胞的有丝分裂,而且莴苣幼苗净增值率与根尖细胞的有丝分裂之间呈正相关,证明8-甲氧基二氢血根碱主要通过抑制根尖细胞有丝分裂对莴苣根的生长产生影响。     

外源脱落酸对小麦幼苗抗镉胁迫能力的影响

以小麦(Triticum aestivum L.)为试材,采用水培法研究了100mg/L镉(Cd2+)胁迫条件下施用外源脱落酸(ABA)对小麦幼苗生长及某些生理生化指标的影响。结果表明:(1)100mg/L Cd2+胁迫下,小麦叶片膜脂过氧化产物丙二醛(MDA)含量显著提高,植株生长受到抑制;(2)外源ABA能够明显提高Cd2+胁迫小麦幼苗的根系活力,增加其叶片SOD、CAT和POD活性,促进其脯氨酸积累,降低MDA的含量,并以5.0μmol/L ABA的效果最明显;(3)1.0～5.0μmol/L外源ABA不同程度地缓解Cd2+胁迫对小麦幼苗生长的抑制作用,且5.0μmol/L时效果最明显,其株高、根长、总干重分别比单一Cd2+胁迫处理显著提高6.73%、149%和10.52%,而10.0μmol/LABA反而加重了Cd2+对小麦幼苗生长的伤害。因此,适宜浓度的外源ABA能够通过增加体内保护酶活性和脯氨酸含量来缓解Cd2+胁迫对小麦幼苗生长的抑制作用,增强小麦幼苗的抗Cd2+胁迫能力,并以5.0μmol/L ABA处理效果最好。     

HPLC法测定大果山楂果实中八种酚酸类成分的含量

建立HPLC法同时测定大果山楂果实中原儿茶酸、绿原酸、二氢咖啡酸、咖啡酸、根皮酸、p-香豆酸、阿魏酸和肉桂酸的方法,并通过HPLC法分析这八种酚酸在不同产地大果山楂果实中的含量。采用ZORBAX SB-C18色谱柱,以甲醇/1.5%甲酸水溶液(v/v)为流动相,梯度洗脱,柱温35℃,流速1.0 m L·min~(-1),检测波长280、320 nm。结果表明:(1)在线性范围内八种酚酸质量浓度与色谱峰峰面积的线性关系良好,相关系数均0.997,检出限0.08～0.20μg·m L~(-1),定量下限0.27～0.67μg·m L~(-1),变异系数均5.0%,加标回收率99.3%～103.3%;(2) 10个不同产地的大果山楂果实中酚酸含量丰富,均检出原儿茶酸、绿原酸、二氢咖啡酸、咖啡酸、根皮酸、阿魏酸和肉桂酸七种酚酸,其中,二氢咖啡酸、根皮酸、阿魏酸均为首次检出,以绿原酸为主(8 410.2～13 826.7μg·g~(-1)),占总酚酸的80%以上,总酚酸的质量分数在10 187.8～15 583.9μg·g~(-1)之间,其中广西百色靖西和桂林恭城产的果实总酚酸质量分数相对较高,均大于15 000μg·g~(-1)。综上结果表明,该研究的HPLC法适用于大果山楂果实中酚酸含量的测定,可为大果山楂优良品种的选育、产品质量控制及深度开发利用提供方法和科学参考。     

红薯叶片浸提液对5种主要农田杂草种子萌发及幼苗生长的化感作用

以发芽率、发芽势、根长、茎长和鲜重变化为种子萌发和幼苗生长参数,研究了作物红薯叶片水浸液对云南省农田5种恶性杂草牛膝菊、藿香蓟、鬼针草、马唐和稗草的化感作用。结果表明,红薯叶片水浸液对5种受体杂草种子发芽率的影响不明显,但对发芽势有显著抑制作用。牛膝菊、藿香蓟、鬼针草和马唐的根长和生物量随红薯叶片水浸液浓度增加而显著降低,其中对马唐的抑制最强,高浓度0.1 g/m L时对根长和生物量抑制率分别为92.04%和73.33%,而低浓度0.0125 g/m L时分别为40.99%和46.67%;其次为鬼针草、藿香蓟、牛膝菊;最差的是稗草,随浓度的变化趋势均不明显。随红薯叶片水浸液浓度增加牛膝菊、鬼针草和马唐的茎长显著地降低,其中对马唐的抑制最强,高浓度0.1 g/m L和低浓度0.0125 g/m L时分别为86.85%和70.64%;其次为鬼针草和牛膝菊;相反藿香蓟和稗草的茎长随浓度增加而显著增加,高浓度0.1 g/m L和低浓度0.0125 g/m L时对藿香蓟的促进率分别为86.97%和16.03%。红薯叶片水浸液低浓度0.0125 g/m L时对牛膝菊的茎长和生物量有促进作用(低促高抑)。从化感作用响应指数和综合效应指数的综合对比来看,红薯对牛膝菊、藿香蓟、鬼针草、马唐具有显著的化感抑制作用,随浓度增加其抑制能力显著增加;其中对马唐的为最强,其次为鬼针草、牛膝菊和藿香蓟,相反对稗草具有促进作用(除了浓度0.1 g/m L)。所有这些表明,红薯叶片水浸液对5种杂草化感作用的敏感性趋势总体为:马唐鬼针草牛膝菊藿香蓟,最不敏感或者具有促进作用的是稗草。     

茄子自毒物质对辣椒种子萌发及枯萎菌的化感效应

运用模拟的方式,采用生物测定和室内培养的方法,研究了两种茄子自毒物质香草醛和肉桂酸各浓度对辣椒种子萌发和幼苗生长的化感效应,及其对辣椒枯萎菌菌丝生长的影响.结果表明:这两种自毒物质对辣椒种子萌发和幼苗生长具有低浓度促进,高浓度抑制的化感效应.香草醛和肉桂酸对辣椒和茄子种子的化感效应存在较大差异,辣椒种子受这两种自毒物质的抑制强度明显弱于茄子种子.香草醛和肉桂酸对辣椒枯萎菌菌丝生长表现为各浓度(0.1, 0.5, 1, 4mmol/L)下均具有抑制作用,作用强度随着浓度增加而增强,肉桂酸低浓度时对菌丝生长的抑制作用即达到显著水平.     

茄子根系分泌物中香草醛和肉桂酸对黄萎菌的化感效应

采用室内培养和生物测定的试验方法,研究了不同浓度的香草醛和肉桂酸对黄萎菌（Verticillium dahliae）及茄子种子萌发、幼苗生长的化感效应.结果表明,香草醛和肉桂酸对茄子黄萎菌的化感效应存在差异,表现为所有浓度的肉桂酸都抑制了黄萎菌孢子萌发,当浓度为0.5mmol/L时抑制作用最大;香草醛在浓度为0.1mmol/L时抑制孢子萌发,其余浓度则表现出促进作用.对香草醛和肉桂酸的生物测定结果显示,当浓度为0.1mmol/L时,肉桂酸促进茄子种子萌发和幼苗生长,其余浓度则表现为抑制作用,并且随着浓度的加大抑制作用增强;香草醛在各浓度水平下都促进了茄子种子萌发和幼苗生长,当浓度为0.5mmol/L时促进作用最大.     

外源褪黑素对复合盐碱胁迫下黑果枸杞种子萌发和幼苗生长的缓解效应

以黑果枸杞种子为实验试材,将中性盐NaCl、Na₂SO₄和碱性盐NaHCO₃、Na₂CO₃按碱性盐占比由小到大模拟组成中性复合盐L(1∶1∶0∶0)、中度碱性复合盐M(1∶9∶9∶1)和重度碱性复合盐H(9∶1∶1∶9),采用纸上萌发法,研究外源褪黑素浓度(0.1、0.3、0.5、1.0 mmol/L)对不同盐碱组成(L、M、H)及其盐碱浓度(50、100、200 mmol/L)组合胁迫下黑果枸杞种子萌发和幼苗生长的影响。结果显示：(1)黑果枸杞幼苗的生长表型(长势)随盐碱浓度及碱性盐占比升高明显减弱;适当低中浓度外源褪黑素(0.1、0.3、0.5 mmol/L)能在一定程度上缓解盐碱胁迫对幼苗生长的伤害,过高浓度外源褪黑素(1.0 mmol/L)则使伤害加剧;施加外源褪黑素使黑果枸杞幼苗侧根数量明显增多。(2)黑果枸杞种子的萌发进程与盐碱组成、盐碱浓度及褪黑素浓度密切相关,随盐碱浓度和碱性盐占比升高,黑果枸杞种子萌发的起始时间延迟,萌发总时长缩短;施加适当浓度外源褪黑素能使盐碱胁迫下黑果枸杞种子萌发起始时间提前,并延长萌发总时长。(3)在L复合盐处理中,随盐碱胁迫浓度升高,黑果枸杞种子的发芽率(GR)、发芽势(GP)、发芽指数(GI)、活力指数(VI)、芽长(SL)、根长(RL)均先升后降,但在M和H复合盐碱处理中,各项萌发指标均随盐碱胁迫浓度升高呈逐渐下降趋势。(4) 外源褪黑素对黑果枸杞种子各项萌发指标具有明显“低促高抑”现象,L复合盐中,在3种盐碱浓度胁迫下,褪黑素浓度为0.1和0.3 mmol/L时对GP、GR、GI、VI、SL、RL有促进作用,并以0.1 mmol/L综合促进效果最佳,褪黑素浓度为0.5和1.0 mmol/L时对GP、GR、GI、VI产生抑制作用,褪黑素浓度为1.0 mmol/L对SL、RL有抑制作用;M和H复合盐中,在3种盐碱浓度胁迫下,褪黑素浓度为0.1、0.3、0.5 mmol/L时对各指标均有促进作用,并以0.3 mmol/L综合促进效果最佳,褪黑素浓度为1.0 mmol/L时则产生抑制。研究表明,低浓度中性复合盐处理对黑果枸杞种子萌发和幼苗生长有一定促进作用,高浓度中性复合盐及中度和重度碱性复合盐则产生抑制作用;外源褪黑素对盐碱胁迫下黑果枸杞种子萌发和幼苗生长的缓解具有明显剂量效应,0.1 mmol/L褪黑素对中性复合盐胁迫的综合促进效果更佳, 0.3 mmol/L褪黑素则对中度和重度碱性复合盐胁迫有最佳促进效果。     

酚酸物质对黄瓜幼苗及枯萎病菌菌丝生长的影响

研究了不同连作年限大棚土壤中酚酸物质的种类、含量及其对黄瓜幼苗和枯萎病菌菌丝生长的影响。结果表明:土壤中香草酸、对羟基苯甲酸及阿魏酸随黄瓜连作年限增加而呈现积累趋势;在连作7年的大棚土壤中3种酚酸类物质总量达29.8mg.kg-1干土,显著高于连作1年和3年土壤中的含量;酚酸物质可使黄瓜幼苗根长及茎粗显著降低,使株高及干物质量略有下降。与对照相比,酚酸物质使黄瓜幼苗体内过氧化物酶(POD)活性在短期内升高,5d后又呈下降趋势;对超氧化物歧化酶(SOD)活性的影响也表现出先升高后下降的变化趋势。高浓度酚酸使黄瓜幼苗丙二醛(MDA)含量持续升高。枯萎病菌菌丝生长测定表明:42h内,低浓度(≤50mg.L-1)酚酸对枯萎病菌丝生长有刺激作用;酚酸浓度高于50mg.L-1时,对菌丝生长有抑制作用;随酚酸处理时间延长,枯萎病菌对酚酸物质的耐受性增强,对高浓度酚酸的生长抑制作用表现不明显。     

Purification and Characterization of the Heat-Stable Factors Essential for the Conversion of Lignoceric Acid to Cerebronic Acid and Glutamic Acid: Identification of N-Acetyl-l-Aspartic Acid

Abstract: The conversion of lignoceric acid to cerebronic acid, ceramides, cerebrosides, and glutamic acid is catalyzed by a rat brain particulate preparation. The heat-stable factor, prepared from calf cerebellum, together with the heat-labile factor, a pyridine nucleotide, and Mg²⁺ are essential to all of these metabolic pathways. Our previous work showed that the heat-stable factor is composed of at least two components, HSF-1 and HSF-2, and identified HSF-2 as d -glucose-6-phosphate. In the current investigation, HSF-1 was further purified and found to be N -acetyl- l -aspartic acid. In addition, it was discovered that a third component, HSF-3, is also required for heat-stable factor activity. A reconstituted system composed of N -acetylaspartic acid, glucose-6-phosphate, and HSF-3 fully replaced the heat-stable factor essential for the conversion of lignoceric acid to cerebronic acid and glutamic acid. The reconstituted heat-stable factor did not show the initial time lag always observed with the crude heat-stable factor.     

氨基酸分析仪测定饲料添加剂——叶酸的方法

用６ｍｏｌ／Ｌ盐酸于１１０℃条件下水解饲料添加剂——叶酸,使之游离出谷氨酸,用氢氧化钠中和调节ｐＨ到２,氨基酸分析仪测定谷氨酸含量,经与标准叶酸水解样品比较,计算出叶酸的纯度。该方法重现性好,变异系数ＣＶ＝０．０８％,平均回收率为９８．３４％,浓度与峰面积呈线性相关,相关系数ｒ＝０．９９８７,可随氨基酸分析同时进行,不需改变任何分析条件。     

Biochemical Studies on Hydrocyanic Acid Potential and Amino Acid in Sorghums

This research is conducted to study the HCN-p of several types of sorghum, as well as their changes in amino acid. The HCN-p of sorghum seedling reached its maximum in 4–6 days after germination. It was found that the first leaf of the seedling has the highest HCN-p. Among the 14 varieties studied, Atlas had the highest HCN-p (1984ppm), whereas NP-22 had the lowest value (479ppm). Light-grown seedlings had higher HCN-p. There was no obvious difference in protein amino acid in sorghum seedlings with .different HCN-p. However, the free amino acid content did vary in the sorghum varieties. The content of free tyrval, pheleu and ileu in etiolated Atlas seedlings was significantly higher than that in NP-22 seedlings. However, under condition of light, the five free amino acids lowers significantly in content in Atlas when compared be NP-22. This proves that Atlas had a more sensitive enzyme system and under presence of light, its free amino acid content was rapidly converted to cyanide.     

紫锥菊单咖啡酰酒石酸和菊苣酸提取工艺优化

采用正交试验设计,选取乙醇体积浓度百分比、提取温度、提取时间、抗氧化剂用量等因素,优化紫锥菊Echinacea purpurea单咖啡酰酒石酸和菊苣酸的加热回流提取工艺,并考察加入抗氧化剂对提取效果的影响。结果表明,优化的提取条件是以25%乙醇,在80 ℃回流提取90 min。抗氧化剂用量对提取效果影响不显著。优化后的加热回流提取条件对紫锥菊单咖啡酰酒石酸和菊苣酸的提取均适用,提取中无需加入抗氧化剂。     

在伤信号传导中茉莉酸与水杨酸的关系

近年来,发现茉莉酸和水杨酸都是植物体对外界伤害作出反应,表达抗性基因的信号分子。水杨酸可抑制茉莉酸类的合成及其所诱导的蛋白基因的表达;茉莉酸能阻止病原侵染后所产缮乃钏岬脑黾印＼岳蛩嵝藕抛纪揪逗退钏嵝藕抛纪揪洞嬖谧沤徊妫。牵裕薪岷蛋白和细胞分裂素可能起着信号开关的作用。     

Hyaluronic Acid Degradation by Ascorbic Acid and Influence of Iron

The effects of ascorbic acid, iron and ADP on hyaluronic acid, a compound present in inflamed joints, were investigated in an in vitro system. Ascorbic acid induces degradation of hyaluronic acid which increased in the presence of FeCl, and which is additionally stimulated by ADP chelated ferric ions. The hyaluronic acid degrading reactions induced by the Fe-III/ADP/ascorbic acid system were inhibited by catalase and formate to various extents whereas the presence of superoxide dismutase did not exert any inhibitory effect. Desferrioxamine, a specific iron chelator, completely inhibited hyaluronic acid depolymerisation by ascorbic acid as well as in combination with FeCl₃ or FeCl₃/ADP, respectively. We suggest that the ultimate hyaluronic acid degrading species is OH', generated via the Fe-III/ADP catalysed Haber Weiss reaction. There is also an indication for the involvement of perferryl or/and ferryl species in the degradation process.     

Hyaluronic Acid Degradation by Ascorbic Acid and Influence of Iron

The effects of ascorbic acid, iron and ADP on hyaluronic acid, a compound present in inflamed joints, were investigated in an in vitro system. Ascorbic acid induces degradation of hyaluronic acid which increased in the presence of FeCl, and which is additionally stimulated by ADP chelated ferric ions. The hyaluronic acid degrading reactions induced by the Fe-III/ADP/ascorbic acid system were inhibited by catalase and formate to various extents whereas the presence of superoxide dismutase did not exert any inhibitory effect. Desferrioxamine, a specific iron chelator, completely inhibited hyaluronic acid depolymerisation by ascorbic acid as well as in combination with FeCl₃ or FeCl₃/ADP, respectively. We suggest that the ultimate hyaluronic acid degrading species is OH', generated via the Fe-III/ADP catalysed Haber Weiss reaction. There is also an indication for the involvement of perferryl or/and ferryl species in the degradation process.     

The Biological and Structural Similarity between Lunularic Acid and Abscisic Acid

Lunularic acid (LA) inhibited not only the germination and the growth of cress and lettuce at 1 mM but also the gibberellic acid (GA₃)-induced α-amylase induction in embryoless barley seeds at 120 μM, which was recognized as a specific activity of abscisic acid (ABA). Moreover LA and ABA equally inhibited the growth of Lunularia cruciata A18 strain callus at 40 and 120 μM. A computational analysis revealed that the stable conformers of LA could be superimposed on the stable ABA conformers. In addition, the antibody raised against the conjugate of C₁-ABA-bovine serum albumin (ABA-BSA) reacted with LA-horse-radish peroxidase (LA-HRP) conjugate as well as ABA-HRP conjugate, apparently. These results can explain why LA has ABA-like activity in higher plants. Moreover the results suggest that LA and ABA bind to the same receptor in higher plants.     

Turnover of Free Sialic Acid, CMP-Sialic Acid, and Bound Sialic Acid In Rat Brain

Abstract: Adult male rats were injected intraventricularly with N-[³H]acetylmannosamine. After different time intervals the rats were killed and free sialic acid, CMP-sialic acid, lipid- and protein-bound sialic acid were isolated from brain and the specific radioactivities determined. Maximal specific radioactivity was reached after approximately 4 h for CMP-sialic acid, after 10–12 h for free sialic acid and after approximately 42 h for lipid-and protein-bound sialic acid. After some days the specific radioactivities of all four pools were the same and decreased equally, with a calculated turnover rate of approximately 3.5 weeks. The conclusion was that this phenomenon was the result of reutilisation of sialic acid and/or precursors. Therefore, the calculated turnover is not the turnover of bound sialic acid, but merely the rate of leakage of sialic acid and/or precursors out of the brain, so that no real turnover can be measured by this method. The first few hours after injection the specific radioactivity of CMP-sialic acid rose above that of free sialic acid. It is supposed that a compartmentalization exists of free sialic acid. The newly synthesized sialic acid molecules are not secreted into the cytoplasmic pool but are preferentially used for the synthesis of CMP-sialic acid. The results and conclusions are discussed in view of the general problems concerning turnover measurements of glycoconjugates.