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41.
Physiological and Biochemical Mechanisms Involved in the Response to Abscisic Acid in Maize Coleoptiles 总被引:2,自引:0,他引:2
The role of abscisic acid (ABA) in controlling growth and developmenthas been studied in maize (Zea mays L.) coleoptile segments.Application of ABA reduces the elongation rate by about 50%and affects ion fluxes. In particular, proton extrusion is decreasedwhile potassium efflux is greatly enhanced. Apparently, ABAdoes not: seem to influence calcium influx from the apoplastinto the cytosol, but more likely it influences its efflux.Alteration of cytosolic calcium concentration may also be obtainedby increasing its release from internal stores. This possibilitymight be sustained by the increased hydrolysis of phosphatidylinositolupon ABA application. Change in the balance of ion fluxes shouldresult from regulation of transport mechanisms at the membranelevel and should produce changes in the transmembrane electricalpotential. The H+- ATPase and the ATP-dependent calcium transportactivities are both influenced by the treatment with ABA, 55%and 40%, respectively. Under these conditions [Ca2+]cytand pHcyt can be modified and, as a consequence of their regulation,they may play an important role in mediating the physiologicaland biochemical effects of ABA, acting as second intracellularmessengers.
1Research supported by National Research Council of Italy, SpecialProject RAISA, Sub-Project N. 2, Paper n. 2782. 相似文献
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I De Carneri 《Parassitologia》1971,13(1):165-167
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Calf lens fiber membranes and fractions enriched in junction-like structures have been isolated in the absence and presence of EDTA. Their biochemical features have been studied. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting experiments have provided evidence that a distinct group of EDTA-extractable proteins, being one of the main protein components of calf lens fiber membranes and very likely also of junction-like structures, is bound to these membranes via calcium ions. In addition to these proteins, four polypeptides with apparent molecular weights between 14 000 and 17 000 are characteristic for detergent-insoluble lens fiber structures prepared in calcium-rich medium. The absence of EDTA-extractable proteins in the urea-soluble calcium-containing fraction implies that they are not components of the cytoskeleton and that the calcium-dependent binding of these proteins to the membrane is urea-resistant. The use of EDTA throughout the whole membrane isolation procedure results in their complete removal from the membranes which already starts during buffer washing. This indicates that EDTA-extractable proteins exclusively consist of extrinsic membrane proteins which probably are not involved in cytoskeleton binding. 相似文献
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S.Candeloro De Sanctis L. Toniolo T. Boschi G. Deganello 《Inorganica chimica acta》1975,12(1):251-254
Reaction of [Pd(1-3-η-allyl)Cl]2 with lithium triazenide (triazenide = p-XC6H4NN-NC6H4X-p; X = Cl, H, CH3) affords dimeric complexes of the type [Pd(1-3-η-allyl)(triazenide)]2. In the solid state the triazenido ligands are bridging two palladium atoms with their terminal nitrogen atoms, as shown by a preliminary X-ray determination of the complex with X = CH3. The allyl groups are stereochemically equivalent. 1H NMR spectra demonstrate the presence of two conformers in solution. The major component has the same configuration found in the solid. The other conformer has stereochemically non equivalent allyl groups. The concentration ratio of the two conformers is independent of the temperature, suggesting the absence of intramolecular processes and of palladium- triazenido bond breaking. This point is discussed also by comparing the (1-3-η-allyl)(triazenide)palladium (II) dimers with the closely related(1-3-η-allyl)(acetate)palladium(II) complexes. 相似文献
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M. T. Garcia J. J. Nieto A. Ventosa F. Ruiz-Berraquero 《Journal of applied microbiology》1987,63(1):63-66
Fifty-eight strains of the moderate halophile Vibrio costicola , including both culture collection strains and freshly isolated strains from solar salterns, were examined for their susceptibility to 10 heavy metal ions by using an agar dilution technique. All strains were sensitive to cadmium, copper, silver, zinc and mercury. This latter ion showed the highest activity even at 0·05 mmol/1 metal concentration. On the other hand, all strains were similarly tolerant to lead, and a great proportion of them were also tolerant to nickel (91%) and chromium (88%). Only 44% and 14% of them showed tolerance to arsenate and cobalt, respectively. The majority of strains (96·4%) were multiply metal-tolerant, with three different metal ion tolerances as the major pattern. 相似文献
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