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Induction of Cell Division in Leaf Cells of Coconut Palm by Alteration of pH and its Correlation with Glyoxalase-I Activity 总被引:1,自引:0,他引:1
Cell division in suspension cultures obtained from leaf cellsof coconut was influenced by pH of the culture media. A 3-foldincrease in cell number was obtained at pH 7.0 compared to suspensionsgrowing at pH 5.0. The pH of both cells and media changed after48 h of growth. Internal cell pH showed a significant increasewhen cultures were grown at pH 7.0 and 8.0 and increased onlyslightly at pH 5.0 and 6.0. Glyoxalase-I activity of cells insuspension culture was found to be pH-depcndent, showing maximumactivity at pH 7.0. Glutathione, a co-enzyme for the substratemethylglyoxaJ for glyoxalase-I, produced a 2-fold increase incell number at a concentration of 5 x 103 mol dm 3.The polyamine, spermidine, promoted cell division maximallyat a concentration of 106 mol dm3. Methylglyoxal-bis(guanylhydrazone), an inhibitor of spermidine biosynthesis,strongly inhibited cell division giving maximum inhibition ata concentration of 3 x 106 mol dm 3. These resultsindicate a positive correlation between cell division and glyoxalase-Iactivity. Key words: Cocos nucifera, glyoxalase-I, pH, spermidine 相似文献
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Phytochrome mediated induction of nitrate reductase activity in etiolated maize leaves 总被引:1,自引:0,他引:1
L. VIJAYA MOHAN RAO NEERAJ DATTA SUDHIR K. SOPORY SIPRA GUHA-MUKHERJEE 《Physiologia plantarum》1980,50(2):208-212
The effects of red and far-red light on the enhancement of in vitro nitrate reductase activity and on nitrate accumulation in etiolated excised maize leaves were examined. Illumination for 5 min with red light followed by a 4-h dark period caused a marked increase in nitrate reductase activity, whereas a 5-min illumination with far-red light had no effect on the enzyme activity. The effect of red light was completely reversed by a subsequent illumination with the same period of far-red light. Continuous far-red light also enhanced nitrate reductase activity. Both photoreversibility by red and far-red light and the operation of high intensity reaction under continuous far-red light indicated that the induction of nitrate reductase was mediated by phytochrome. Though nitrate accumulation was slightly enhanced by red and continuous far-red light treatments by 17% and 26% respectively, this is unlikely to account for the entire increase of nitrate reductase activity. The far-red light treatments given in water, to leaves preincubated in nitrate, enhanced nitrate reductase activity considerably over the dark control. The presence of a lag phase and inhibition of increase in enzyme activity under continuous far-red light-by tungstate and inhibitors of RNA synthesis and protein synthesis-rules out the possibility of activation of nitrate reductase and suggests de novo synthesis of the enzyme affected by phytochrome. 相似文献
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In shoot apices of 7-day-old dark-grown peas the addition of ammonium along with the inducer nitrate resulted in a more than two-fold increase in nitrate reductase activity. Individual amino acids, amides and amino-acid mixture could not replace the ammonium effect. Ammonium also stimulated NADH-glutamate dehydrogenase but not glucose-6-phosphate dehydrogenase. Sucrose caused a marked stimulation of nitrate reductase induction and showed synergistic effect with light. In presence of cordycepin and cycloheximide, induction of nitrate reductase was inhibited more if ammonium or sucrose was supplied along with the inducer. With actinomycin D, α-amanitin or chloramphenicol, no differential inhibition took place in presence of ammonium. The inhibition of enzyme activity by chloramphenicol and 3-(3,4-dichlorophenyl)-l,dimethyl urea was completely relieved by sucrose. Incorporation of 14C-lysine was markedly stimulated by sucrose, but was not affected by ammonium. The effect of sucrose and light on 14C-lysine incorporation was additive. Cordycepin and cycloheximide did not have any differential effect on 14C-lysine incorporation in the presence of ammonium as well as sucrose. The inhibition of 14C-lysine incorporation caused by chloramphenicol was relieved by sucrose. Sucrose also caused a marked increase in 3H-uridine incorporation but ammonium had no effect. Actinomycin D and cordycepin blocked the sucrose dependent increase in 3H-uridine incorporation. The results suggest that ammonium mediated stimulation may depend on a regulatory protein(s) synthesized in response to ammonium, whereas sucrose acts mainly by an overall increase in RNA and protein synthesis. The effect of light does not seem to be dependent on photosynthetic light reactions. 相似文献
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RAJASEKHAR V. K.; GUHA-MUKHERJEE SIPRA; SOPORY SUDHIR K. 《Journal of experimental botany》1983,34(11):1444-1454
In 5-d-old etiolated seedlings of Sorghum bicolor, 12 h of darknessafter 5 min in red light eliminated a lag before the accumulationof chlorophylls in subsequent continuous white light. Increasingthe dark period to 24 h and 36 h, increased the rate of chlorophyllaccumulation in the later stages of greening. Exogenous -aminolevulinicacid neither completely removed the lag, nor increased the rateof chlorophyll accumulation. Cycloheximide (25 µg ml1)and 6-methyl purine (5.0 µg ml1), given continuouslyor only until the 12 h dark period following the red light irradiation,restored the lag and decreased the rate of chlorophyll accumulation.D-threo-chloramphenicol (400µg ml1) also decreasedthe rate of chlorophyll accumulation but did not restore thelag. Addition of these inhibitors even 12 h after red lightirradiation decreased the rate of chlorophyll accumulation.Rifampicin (Rifamycin SV, 400 µg ml1) did not havesuch effects. Key words: Chlorophylls, Phytochrome, -Aminolevulinic acid, Sorghum bicolor 相似文献
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VIJAYARAGHAVAN S. JANAKI; GUPTA ADITYA; GUHA-MUKHERJEE SIPRA; SOPORY SUDHIR K. 《Journal of experimental botany》1982,33(4):705-716
Light-enhanced nitrate reductase (NR) activity was 8 times greaterthan the dark control. Exogenous application of sucrose, glucoseand fructose increased the induction of NR in the light as wellas in the dark, whereas glycolate had no effect. DCMU [3-(3,4-dichlorophenyl)-1, 1-dimethyl urea] completely inhibited thedevelopment of NR in light. Sucrose, when added with DCMU, reversedthis inhibitory effect NR in vivo was more stable in light thanin darkness, the half-lives being 9.6 h and 6.4 h, respectively.The addition of sucrose did not change the half-life of NR ineither light or darkness. Ammonium, the end product of the inorganicnitrogen assimilatory pathway, stimulated the NR activity whereasamino acids decreased it. Key words: Spirodela oligorrhiza, nitrate reductase, ammonium, light 相似文献
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DUREJA INAM; GUHA-MUKHERJEE SIPRA; PRASAD RAJENDRA 《Journal of experimental botany》1984,35(7):1022-1031
The uptake of L-leucine and glycine into pea protoplasts wasstudied under various conditions. The uptake of both L-leucineand glycine was pH dependent with the optimal pH being 4.0 and5.0 for L-leucine and glycine, respectively. A kinetic studyof L-leucine uptake showed that uptake is multiphasic; Km valuesof different phases were 1.1 mol m3, 33.3 mol m3and 100 mol m3. A similar analysis for glycine at a concentrationrange of 0.110 mol m3 also showed a multiphasictransport system for it. The uptake of L-leucine at lower concentrations(between0.12.0 mol m3) was energy dependent, since arsenate,azide, dinitrophenol and iodoacetate inhibited the uptake. However,the uptake of L-leucine was not inhibited by ouabain at anyconcentration of L-leucine employed. The uptake of glycine wasnot inhibited by any of these inhibitors suggesting that glycineuptake was not mediated by an active process. Key words: Pea protoplast, L-Leucine, Glycine transport, Active transport, Mediated transport 相似文献