scholarly journals The Physiology of Sugar-Cane III. Characteristics of Sugar Uptake in Slices of Mature and Immature Storage Tissue

1960 ◽  
Vol 13 (3) ◽  
pp. 203 ◽  
Author(s):  
RL Bieleski
Keyword(s):  
Sugar Cane ◽  
Free Space ◽  
Sugar Concentration ◽  
Sugar Uptake ◽  
Accumulation Process ◽  
Anaerobic Conditions ◽  
Storage Tissue ◽  
Constant Rate ◽  
Two Stages ◽  
Initial Uptake

Sugar uptake by slices of sugar-cane storage tissue took place in two stages. The initial uptake reached an equilibrium within 1 hr, the level being proportional to the external sugar concentration, independent of the sugar, and unaffected by anaerobic conditions. This sugar diffused out rapidly when the tissue was placed in water. It was thus contained in the apparent free space, 10-20 per cent. of the tissue volume. The secondary uptake continued up to 60 hr at a slow, constant rate, 1-5 mgjgjday, independent of sugar concentration above 2� 0 per cent., dependent on the sugar, and inhibited by anaerobic conditions. This sugar did not diffuse out when the tissue was placed in water. It was concluded that the secondary uptake was an active accumulation process.

The Anatomy of the Storage Tissue of Sugar-cane in Relation to Sugar Uptake

1977 ◽  
Vol 41 (2) ◽  
pp. 401-404 ◽  
Author(s):  
O. O. OWORU ◽  
C. R. McDAVID ◽  
D. MACCOLL
Keyword(s):  
Sugar Cane ◽  
Sugar Uptake ◽  
Storage Tissue

In vitro sugar uptake by grapefruit (Citrus paradisi) juice-sac cells

2005 ◽  
Vol 32 (4) ◽  
pp. 357 ◽  
Author(s):  
Moshe Huberman ◽  
Uri Zehavi ◽  
Wilfred D. Stein ◽  
Ed Etxeberria ◽  
Raphael Goren
Keyword(s):  
Metabolic Inhibitors ◽  
Sugar Uptake ◽  
Citrus Paradisi ◽  
Citrus Juice ◽  
14Co2 Evolution ◽  
Independent Process ◽  
Initial Uptake ◽  
Juice Sacs ◽  
Slight Inhibition

To further our understanding of the mechanisms of sugar uptake and accumulation into grapefruit (Citrus paradisi Macf. cv. Marsh seedless), the patterns of uptake and utilisation of sucrose, glucose and fructose by Citrus juice cells was investigated. Analyses were conducted on sliced juice sacs that were incubated in radioactive [14C]-sugar solutions with unlabelled sugars, in the presence or absence of metabolic inhibitors. Both hexoses demonstrated an initial uptake peak in December and a second uptake peak in February–March. From March through April the rates of sucrose uptake increased to levels comparable to those of glucose and fructose. Sucrose and its moieties fructose and glucose entered the juice cells of Citrus juice fruit by an insaturable, and mostly by an independent, process. However, NaN3 and carbonylcyanide m-chlorophenylhydrazone (CCCP) produced slight inhibition of these processes. Cells took up hexoses at a greater rate than sucrose, with accumulation reaching a plateau by 4–8 h, and then continuing unabated, in the case of glucose, for 42 h. Uptake of all three sugars increased linearly in the range of sugar concentrations tested, which extended from 0.01 to 320 mm, denoting an insaturable system for sugar uptake. 14CO2 evolution was relatively low in all the experiments, the lowest evolution being recorded when the uptake of [14C]-sucrose was studied, while the highest 14CO2 evolution was recorded when the uptake of [14C]-glucose was studied. The data demonstrate a preferential utilisation of glucose over fructose and sucrose. In all the experiments, the two metabolic inhibitors significantly inhibited the decarboxylation of the three sugars.

Evidence for the Consequences of a Barrier to Solute Diffusion Between the Apoplast and Vascular Bundles in Sugarcane Stalk Tissue

1992 ◽  
Vol 19 (6) ◽  
pp. 611 ◽  
Author(s):  
GE Welbaum ◽  
FC Meinzer ◽  
RL Grayson ◽  
KT Thornham
Keyword(s):  
Free Space ◽  
Xylem Sap ◽  
Dry Weight ◽  
Solute Diffusion ◽  
Vascular Bundles ◽  
Storage Tissue ◽  
Sugarcane Stalk ◽  
Large Molecular Weight ◽  
Osmotic Water ◽  
Storage Parenchyma

In a previous study we found that the apoplast of mature sugarcane stalk tissue contains up to 700 mM sucrose. In the current study, we found that xylem sap, exuded under root pressure from decapitated stalks, was virtually free of sucrose. This suggested that the apoplast of sugarcane stalk tissue contains at least two separate compartments: one within the free space of the vascular bundles, which is nearly free of sucrose, and another in the free space of the surrounding storage tissue. Anatomical observations indicated that these putative compartments were separated by the sclerenchymatous bundle sheath cell walls that were suberised and lignified early in development, constituting a barrier to the movement of relatively large molecular weight solutes but not water. It was hypothesised that this semipermeability would enable sucrose and other solutes in the apoplast of the storage tissue to provide a gradient for osmotic water flow from the xylem, generating a hydrostatic pressure in the apoplast. Additional lines of evidence were obtained to support this hypothesis: (i) apoplastic dyes were restricted to the xylem and did not accumulate in the apoplast of storage tissue when water-stressed plants were rehydrated, (ii) water potential measured with in situ psychrometers decreased when sections of intact stalks were cut, (iii) mature internode tissue of well-watered plants often cracks after maximum fresh and dry weight accumulation, and (iv) internode sections typically shrink in diameter immediately upon excision. The existence of a semipermeable barrier separating the vascular bundles from the storage parenchyma apoplast would require that phloem unloading involve a symplastic step in order to traverse the barrier. The presence of plasmodesmatal connections between companion, sclerenchyrna, and storage parenchyma cells supported this conclusion.

scholarly journals Model-assisted analysis of the peach pedicel–fruit system suggests regulation of sugar uptake and a water-saving strategy

2020 ◽  
Vol 71 (12) ◽  
pp. 3463-3474
Author(s):  
Dario Constantinescu ◽  
Gilles Vercambre ◽  
Michel Génard
Keyword(s):  
Sugar Transport ◽  
Water Saving ◽  
Lower Pressure ◽  
Sugar Concentration ◽  
Sugar Uptake ◽  
Pressure Potential ◽  
High Sugar Concentration ◽  
High Sugar ◽  
Diurnal Patterns ◽  
Assisted Analysis

Abstract We develop a model based on the biophysical representation of water and sugar flows between the pedicel, fruit xylem and phloem, and the fruit apoplast and symplast in order to identify diurnal patterns of transport in the pedicel–fruit system of peach. The model predicts that during the night water is mainly imported to the fruit through the xylem, and that fruit phloem–xylem transfer of water allows sugar concentrations in the phloem to be higher in the fruit than in the pedicel. This results in relatively high sugar transport to the fruit apoplast, leading to relatively high sugar uptake by the fruit symplast despite low sugar concentrations in the pedicel. At midday, the model predicts a xylem backflow of water driven by a lower pressure potential in the xylem than in the fruit apoplast. In addition, fruit xylem-to-phloem transfer of water decreases the fruit phloem sugar concentration, resulting in moderate sugar uptake by the fruit symplast, despite the high sugar concentration in the pedicel. Globally, the predicted fruit xylem–phloem water transfers buffer the sugar concentrations in the fruit phloem and apoplast, leading to a diurnally regulated uptake of sugar. A possible fruit xylem-to-apoplast recirculation of water through the fruit phloem reduces water lost by xylem backflow at midday.

scholarly journals Permeability Evaluation of Clay-quartz Mixtures Based on Low-Field NMR and Fractal Analysis

2020 ◽  
Vol 10 (5) ◽  
pp. 1585 ◽  
Author(s):  
Zhen Lu ◽  
Aimin Sha ◽  
Wentong Wang
Keyword(s):  
Prediction Model ◽  
Decay Rate ◽  
Fractal Analysis ◽  
Bound Water ◽  
Free Water ◽  
Evaporation Process ◽  
Permeability Coefficients ◽  
Constant Rate ◽  
Saturated Mixture ◽  
Two Stages

Nuclear magnetic resonance (NMR) technology has been widely used for predicting permeability coefficients of porous medium, such as shales, sandstones, and coals. However, there have been limited studies on the prediction model of clay-quartz mixtures based on NMR technology. In this study, evaporation tests at 40 °C and NMR tests were simultaneously performed on eight clay-quartz mixtures with different mineral compositions. The results show that during the evaporation process, the decay rate of T2 total signal amplitudes was constant at first, and then decreased to 0 after a period of time. Based on the decay rate, the evaporation process was divided into two stages: the constant rate stage and the falling rate stage. Based on the two stages, the T2 cut-offs of eight mixtures were determined. The water in the mixture was divided into two parts by the T2 cut-off: the free water and the bound water. The prediction model of permeability coefficients of clay-quartz mixtures was established based on the Timur-Coates model. In order to simplify the process of predicting the permeability coefficient, fractal analysis was used to develop the relationship between the T2 cut-off and fractal dimension of the T2 spectrum of saturated mixture. A simplified method for predicting permeability coefficients of clay-quartz mixtures based on NMR technology without centrifugal and evaporation experiments was also proposed.

scholarly journals The Physiology of Sugar-Cane IV. Effects of Inhibitors on Sugar Accumulation in Storage Tissue Slices

1960 ◽  
Vol 13 (3) ◽  
pp. 221 ◽  
Author(s):  
RL Bieleski
Keyword(s):  
Sugar Cane ◽  
Metabolic Inhibitors ◽  
Magnesium Ion ◽  
Sugar Accumulation ◽  
Tissue Slices ◽  
Storage Tissue ◽  
Cupric Ion ◽  
Mercuric Ion ◽  
Rate Of Accumulation

Various metabolic inhibitors, at pH 5� 5, affected sugar accumulation in immature sugar-cane storage tissues. The rate of accumulation was reduced by lO-5M mercuric ion, lO-<M p-chloromercuribenzoate, cyanide, and cupric ion, and 2 X lO-3M phloridzin. Accumulation was completely inhibited and sugar leakage induced by lO-5M dinitrophenol, lO-<M mercuric ion, and 10-3M p-chloromercuribenzoate, cyanide, cupric ion, azide, arsenate, and iodoacetate. The effects of 10-5M dinitrophenol and 10-4M cyanide were reversible, but that of 10-3M cyanide was irreversible. Only slight effects were produced by borate, phosphate, and magnesium ion.

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