GA3、ABA对未成熟‘博Ⅱ优15’水稻种子萌发的影响

以未成熟水稻'博II优15'种子为材料,用不同浓度GA3、ABA浸种24 h,研究其对水稻种子萌发的影响.结果表明,GA3 0.10～2.00 g/L处理能极显著促进种子萌发,其中0.50 g/L效果最好,第4天发芽率高于对照(CK)56%;浓度大于0.50 g/L ABA处理显著抑制种子萌发;GA3与ABA协同处理时, GA3/ABA = 1:1(浓度0.05 g/L)和 GA3/ABA = 1:2(浓度0.01 g/L)均能极显著促进种子萌发,第7天种子发芽率分别比CK高30%和20%.进一步研究表明,GA3和ABA对未成熟水稻种子萌发的影响与α-淀粉酶活性相关.     

外源脱落酸和马来酰肼对杂交水稻F1穗上种子发芽的抑制效应

杂交稻F1齐穗后21 d(灌浆期)施用ABA 1000mg/L或MH 4000 mg/L,可以抑制穗芽的发生,降低种子活力.ABA处理F1发芽种子使GA1含量下降,淀粉酶活性表达滞后,活性下降,有效发芽期延长;MH处理没有引起F1发芽种子GA1含量与淀粉酶活性下降,但使未发芽种子中GA1与淀粉酶活性明显下降,并丧失发芽能力.因此,ABA对杂交稻F1穗芽的抑制作用可视为"后熟效应",而MH对穗芽的抑制作用可视为"遏制作用".     

ABA抑制花生侧根发生

本实验研究了ABA对花生侧根发生的影响。结果表明：用10umol·L-1 ABA浸泡处理花生种子1h或在含ABA的培养基上培养,均抑制侧根的发生,侧根发生率降低,数目减少,长度降低,发生的时间推迟1-2d;用ABA合成抑制剂25umol·L-1 NAPR浸泡后的种子,无论在1／2MS还是在含NAA培养基上培养,侧根发生率、侧根的数目和长度均增加。用NAA的极性运输抑制剂10umol·L-1 TIBA浸泡处理种子后,再在含ABA培养基上培养,侧根不发生,说明ABA抑制花生侧根的发生与种子内源ABA和IAA的水平相关。     

胡桃醌对小麦种子萌发及幼苗生长的化感效应

以小麦种子为试验材料,采用培养皿药膜法、生化分析法研究了胡桃醌对小麦种子萌发和幼苗生长的化感效应。结果显示:(1)与对照相比,低浓度胡桃醌(4和20μmol.L-1)处理能促进小麦种子萌发和幼苗生长,种子α-淀粉酶活性增大,幼苗中可溶性蛋白含量升高,丙二醛(MDA)含量减少,超氧化物歧化酶(SOD)活性无显著变化。(2)当胡桃醌浓度大于100μmol.L-1时,对小麦种子萌发和幼苗生长开始呈现抑制作用,种子α-淀粉酶活力降低,幼苗相对含水量、可溶性蛋白含量降低,MDA含量升高,SOD活性先增大后减小。(3)在最大浓度胡桃醌(1 250μmol.L-1)处理下,小麦幼根的细胞形状不规则,排列混乱,层次不分明,维管束模糊不清,幼苗细胞质壁分离,叶绿体萎缩坏死,细胞核变形。研究表明,高浓度胡桃醌通过抑制受体小麦保护酶活性,加重膜脂过氧化程度,导致幼根、幼苗细胞结构的破坏,从而产生化感效应,且化感效应随浓度的增加不断增强。     

人工疏果对黄皮果实品质及部分内源激素含量的影响

以'大鸡心'黄皮为材料,研究了不同程度人工疏果对黄皮果实品质及内源激素含量的影响.结果表明:与对照相比,疏果50%和25%后,黄皮果实中可溶性糖、维生素C、可食率等显著提高,可滴定酸含量显著降低;疏果50%和疏果25%后,黄皮果实种子及果皮的IAA、GA3、ZT含量增加,ABA含量降低.实验表明,人工疏果可以提高黄皮果实的品质,提高果实内促进生长类激素含量、降低抑制生长类激素含量.     

施氮量对花铃期短期渍水棉花叶片抗氧化酶活性和内源激素含量的影响

于2005—2006年在江苏南京(32°02′N,118°50′E)南京农业大学卫岗试验站进行盆栽试验,设置正常灌水和棉花花铃期短期渍水处理(渍水8d,恢复15d),每个水分处理设置3个施氮水平(0、240、480kgN.hm-2),研究施氮量对渍水棉花叶片抗氧化酶活性和内源激素含量的影响.结果表明:在渍水结束时,与正常灌水相比,渍水棉花叶片可溶性蛋白含量、超氧化物歧化酶和过氧化氢酶活性降低,过氧化物酶活性升高,丙二醛(MDA)含量升高;与此同时,内源激素含量发生变化,脱落酸(ABA)含量升高,玉米素核苷(ZR)、赤霉素(GA)、生长素(IAA)含量及ZR/ABA、GA/ABA、IAA/ABA降低;其中以240kgN.hm-2渍水棉花MDA和ABA含量最低,而ZR、GA和IAA含量及ZR/ABA、GA/ABA和IAA/ABA最高,净光合速率最高.到停止渍水15d时,渍水棉花叶片的抗氧化酶活性、MDA含量、内源激素含量与正常灌水处理的差异较小;施氮可提高渍水处理棉花叶片抗氧化酶活性,降低MDA含量,使ABA水平降低,ZR、GA、IAA水平及ZR/ABA、GA/ABA、IAA/ABA升高.本试验中,渍水条件下以240kgN.hm-2处理的效果最好,生物量和籽棉产量最高.     

多效唑(PP333)对山葵根茎膨大和内源激素含量的影响

山葵植株经100 mg*L-1 PP333处理后,山葵根茎重显著增加,根茎中内源吲哚乙酸(IAA)和赤霉素(GAs)含量降低,玉米素核苷(ZR)和脱落酸(ABA)含量增加,ZR/IAA、ZR/GAs、ABA/IAA和ABA/GAs比值提高.     

外源一氧化氮供体SNP对黑麦草种子萌发和幼苗生长的影响

采用水培试验,研究了不同浓度NO供体硝普钠(SNP)对黑麦草种子萌发和幼苗生长的影响。结果表明:50和100μmol.L-1SNP促进了黑麦草种子的发芽率、幼苗干物质积累速率、萌发种子α-淀粉酶活性、幼苗叶片可溶性蛋白质及叶绿素含量的提高。根和叶片中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性及还原型谷胱甘肽(GSH)、抗坏血酸(ASC)含量增加,超氧阴离子(O.2-)积累速率和过氧化氢(H2O2)含量下降,丙二醛(MDA)积累降低。高浓度SNP(500~2000μmol.L-1)抑制种子的萌发和幼苗生长,幼苗叶绿素、可溶性蛋白质及GSH、ASC含量下降,MDA含量和H2O2、O.2-产生速率提高,SOD、POD和APX活性降低,但叶片CAT活性升高。推测NO可能通过提高种子淀粉酶活性和幼苗活性氧清除能力,促进黑麦草种子的萌发和幼苗生长。     

外源GA3、ABA和Ca(NO3)2缓解盐对小麦种子萌发的抑制作用

盐胁迫下,DK961(耐盐)和LM15(盐敏感)小麦种子的发芽率(Gr)、发芽指数(Gi)和活力指数(Vi)均显著下降,LM15下降的幅度大于DK961.外源100 mg/L GA3、1×10-7 mol/L ABA和0.1% Ca(NO3)2处理均能缓解盐对小麦种子萌发的抑制作用,对盐胁迫下LM15种子萌发的缓解作用显著好于DK961,并且不同程度地缓解盐处理引起的种子内源GA 1+3含量和α淀粉酶的活性下降,从而降低盐胁迫对种子萌发的抑制作用.表明盐抑制小麦种子萌发的主要原因是盐胁迫导致种子内源GA 1+3含量和α淀粉酶的活性下降.     

乙酰胆碱对管花肉苁蓉种子萌发及其内源IAA和ABA含量的影响

检测不同浓度乙酰胆碱对管花肉苁蓉种子发芽率和内源吲哚乙酸(IAA)和脱落酸(ABA)含量影响的结果表明:适宜浓度(1.0~3.0mmol·L~(-1))的乙酰胆碱可促进肉苁蓉种子萌发,并改变内源IAA和ABA含量。1.0mmol·L~(-1)乙酰胆碱是促进肉苁蓉种子萌发的临界点。     

Investigation of the mechanism of temperature sensitivity of the electroreceptors of ampullae of lorenzini

In experiments on Black Sea skates (Raja clavata), the potential of the receptor epithelium of the ampullae of Lorenzini and spike activity of single nerve fibers connected to them were investigated during electrical and temperature stimulation. Usually the potential within the canal was between 0 and –2 mV, and the input resistance of the ampulla 250–400 k. Heating of the region of the receptor epithelium was accompanied by a negative wave of potential, an increase in input resistance, and inhibition of spike activity. With worsening of the animal's condition the transepithelial potential became positive (up to +10 mV) but the input resistance of the ampulla during stimulation with a positive current was nonlinear in some cases: a regenerative spike of positive polarity appeared in the channel. During heating, the spike response was sometimes reversed in sign. It is suggested that fluctuations of the transepithelial potential and spike responses to temperature stimulation reflect changes in the potential difference on the basal membrane of the receptor cells, which is described by a relationship of the Nernst's or Goldman's equation type.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. I. M. Sechenov, Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Pacific Institute of Oceanology, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Neirofiziologiya, Vol. 12, No. 1, pp. 67–74, January–February, 1980.     

Shapes of curves of pH-dependence of reactions

A simple case is considered in which the rate of a two-step reaction depends on pH because the intermediate formed in the first step has to gain (or lose) a proton before it can react in the second step, and in which the rate-determining step therefore changes with pH. The curves of reaction rate against pH are shown to be symmetrical, and the sharpest peak possible has a width at half its height of 1.53pH units, i.e. of 2log(3+2 radical2). Any particular curve for this situation proves to be identical with a curve that could be generated for the pH-dependence of a single-step reaction in which the rate is proportional to the concentration of a particular ionic form of a reactant. Curves for the latter situation, however, can have forms impossible for the former case in which the rate-determining step changes, but only if the protonations that activate and deactivate the reactant are co-operative. The peak can then become even sharper, and its width at half its height can fall to 1.14pH units, i.e. to 2log(2+ radical3).     

Overview of mechanisms of action of lycopene

Dietary intakes of tomatoes and tomato products containing lycopene have been shown to be associated with decreased risk of chronic diseases such as cancer and cardiovascular diseases in numerous studies. Serum and tissue lycopene levels have also been inversely related to the risk of lung and prostate cancers. Lycopene functions as a very potent antioxidant, and this is clearly a major important mechanism of lycopene action. In this regard, lycopene can trap singlet oxygen and reduce mutagenesis in the Ames test. However, evidence is accumulating for other mechanisms as well. Lycopene at physiological concentrations can inhibit human cancer cell growth by interfering with growth factor receptor signaling and cell cycle progression specifically in prostate cancer cells without evidence of toxic effects or apoptosis of cells. Studies using human and animal cells have identified a gene, connexin 43, whose expression is upregulated by lycopene and which allows direct intercellular gap junctional communication (GJC). GJC is deficient in many human tumors and its restoration or upregulation is associated with decreased proliferation. The combination of low concentrations of lycopene with 1,25-dihydroxyvitamin D3 exhibits a synergistic effect on cell proliferation and differentiation and an additive effect on cell cycle progression in the HL-60 promyelocytic leukemia cell line, suggesting some interaction at a nuclear or subcellular level. The combination of lycopene and lutein synergistically interact as antioxidants, and this may relate to specific positioning of different carotenoids in membranes. This review will focus on the growing body of evidence that carotenoids have unexpected biologic effects in experimental systems, some of which may contribute to their cancer preventive properties in models of carcinogenesis. Consideration of solubility in vitro, comparison with doses achieved in humans by dietary means, interactions with other phytochemicals, and other potential mechanisms such as stimulation of xenobiotic metabolism, inhibition of cholesterogenesis, modulation of cyclooxygenase pathways, and inhibition of inflammation will be considered. This review will point out areas for future research where more evidence is needed on the effects of lycopene on the etiology of chronic disease.