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Cyclic Purine Mononucleotides: Induction of Gibberellin Biosynthesis in Barley Endosperm 总被引:1,自引:0,他引:1
The de novo synthesis of α-amylase in barley endosperm and isolated aleurone layers is induced by 3′,5′-cyclic purine mononucleotides and gibberellic acid. The induction of α-amylase by cyclic purine mononucleotides is prevented by 2,4-DNP, inhibitors of RNA and protein syntheses, CCC, AMO-1618 and phosfon. The induction of α-amylase formation by 3′,5′-cyclic purine mononucleotides, but not by gibberellic acid, is also blocked by inhibitors of DNA synthesis. Extracts from cyclic AMP-treated endosperm halves exhibit a characteristic gibberellin-like activity which is detectable within 12 hours from the addition of the cyclic AMP. On paper chromatograms this gibberellin-like activity is located at the Rf typical for GA3. Its formation is prevented by inhibitors of DNA synthesis, CCC and AMO-1618. Glucose inhibits the formation of α-amylase induced by gibberellic acid. Glucose has no effect on the cAMP-induced gibberellin biosynthesis. The evidence shows that the cyclic purine mononucleotides induce DNA synthesis, which results in gibberellin biosynthesis, which in turn activates the synthesis of α-amylase. 相似文献
73.
JAY R. KAPLAN 《American anthropologist》2006,108(3):572-573
Kinship and Behavior in Primates. Bernard Chapais and Carol M. Berman, eds. Oxford University Press, 2004. 507 pp. 相似文献
74.
The apparent photosynthetic affinity-for inorganic carbon inSpirulina is severely reduced by exposing the cells to CO2-depletedconditions in the light. The extent of reduction depends onthe length of exposure, the light intensity, and the O2 concentration.The photosynthetic dependence on inorganic carbon (CInorg) concentration,however, is similar at 3% O2 and at 25% O2 but in the presenceof catalase. The amount of O2 released following the additionof catalase to the cell suspension also depends on the O2 andCO2 concentrations. The addition of H2O2 either to the cellsuspension or by a treatment with methyl viologen caused a severeinhibition of the capability of the cells to accumulate inorganiccarbon internally. It is suggested that the reduction of thephotosynthetic apparent affinity to CInorg upon subjecting thecells to photoinhibitory conditions is caused by an alterationof their ability to accumulate CInorg due to the accumulationof H2O2. 相似文献
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Acclimation of stream-bed heterotrophic microflora: metabolic responses to dissolved organic matter 总被引:1,自引:0,他引:1
SUMMARY.
- 1 Studies were performed to assess the acclimation of the stream-bed heterotrophic microflora to sources of dissolved organic matter (DOM) typical of its environment and microfloral responses to pulses of DOM.
- 2 Microcosm measurements of dissolved organic carbon (DOC) uptake, dissolved oxygen uptake. ATP concentration and epitluorescence microscopic counts (EMC) were performed using stream-bed sediments and heterogeneous dissolved organic matter (DOM) sources.
- 3 Three study sites included an undisturbed woodlot spring seep, a small stream traversing a cattle pasture and a larger stream draining a catchment used for silage crops, pastures and woodlands.
- 4 The DOM sources were cold water extracts of forest floor leaf litter, bovine manure, the green alga Ulothrix and jewel weed (Impaliens capensis L.) leaves.
- 5 DOC uptake occurring in 2.5–5.0 h incubations indicated an acclimation of the microflora at each site to DOM sources generated by surrounding land use.
- 6 The sediment microflora from the larger stream did not readily metabolize bovine manure DOM and the latter was used in an acclimation experiment.
- 7 A minimum of 48 h of cumulative exposure to bovine manure DOM at 15–20°C were required to yield measurable changes in sediment microbial activity of sediment microbial biomass.
- 8 The same microflora retained an ability to readily metabolize the added DOM source after 72 h of exposure to unamended stream water.
- 9 The time frame of microfloral responses during acclimation indicated that changes leading to the metabolism of a DOM source were initially enzymatic and eventually involved growth and selection for specific decomposers within the microbial community.
- 10 We conclude that in order to utilize naturally occurring pulses of carbon and energy, stream-bed heterotrophs must be already enzymatically prepared, induced, when the pulse occurs.
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