scholarly journals The Hexose efflux from the peeled grape berry

OENO One ◽  
2019 ◽  
Vol 53 (2) ◽  
Author(s):  
Predrag Nenad Božović ◽  
Suzy Rogiers ◽  
Alain Deloire
Keyword(s):  
Transport Mechanism ◽  
Sugar Transport ◽  
Inhibitory Effect ◽  
Cellular Level ◽  
Grape Berry ◽  
Sugar Accumulation ◽  
Ethanesulfonic Acid ◽  
Two Stages ◽  
Process Elements ◽  
Vacuolar Membranes

Aim: The transport of sugars into grape berry mesocarp cells across the plasma and vacuolar membranes after onset of ripening is a complex process. Elements of the sugar transport mechanism may be assessed by exposing the mesocarp cells and investigating sugar movement across the membranes. The purpose of this study was to gain insights into the nature of the transport mechanism by creating conditions conducive to hexose efflux from the peeled berry.Methods and results: The experimental technique employed was a derivate of the ‘berry-cup’ technique. The skin of ripening cv. Shiraz berries was peeled in situ and, after an initial wash, hexose efflux into a collection medium (MES buffer) was monitored. Additionally, during the period of intensive sugar accumulation (one week after veraison) and two weeks later, hexose efflux was assessed following three modifications: (i) using berries excised from the vine, (ii) using MES buffer (2-(N-morpholino)ethanesulfonic acid, pH 5.5) containing PCMBS (p-chloromercuribenzenesulfonic acid, 1mM), and (iii) using cold (10°C) or warm (40°C) MES buffer. Hexose quantities collected into the buffer were dependent on ripening stage and buffer temperature, but they were not dependent on an intact berry-to-cluster connection. The inhibitory effect of PCMBS was observed early in ripening, but not two weeks later.Conclusions: These results lead us to the conclusion that the origin of the collected hexoses was vacuolar as opposed to vascular, and that the hexose efflux mechanism is differently sensitive to PCMBS at the two stages of ripening.Significance and impact of the study: This simple technique was effective at providing insights into hexose transport within the grape berry at the cellular level.

scholarly journals VvSWEET10 Mediates Sugar Accumulation in Grapes

Genes ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 255 ◽  
Author(s):  
Zhan Zhang ◽  
Luming Zou ◽  
Chong Ren ◽  
Fengrui Ren ◽  
Yi Wang ◽  
...  
Keyword(s):  
Sugar Content ◽  
Sugar Transport ◽  
Grape Berry ◽  
Critical Event ◽  
Sugar Accumulation ◽  
Sugar Transporters ◽  
Market Values ◽  
Berry Quality ◽  
Sugar Levels

Sugar accumulation is a critical event during grape berry ripening that determines the grape market values. Berry cells are highly dependent on sugar transporters to mediate cross-membrane transport. However, the role of sugar transporters in improving sugar accumulation in berries is not well established in grapes. Herein we report that a Sugars Will Eventually be Exported Transporter (SWEET), that is, VvSWEET10, was strongly expressed at the onset of ripening (véraison) and can improve grape sugar content. VvSWEET10 encodes a plasma membrane-localized transporter, and the heterologous expression of VvSWEET10 indicates that VvSWEET10 is a hexose-affinity transporter and has a broad spectrum of sugar transport functions. VvSWEET10 overexpression in grapevine calli and tomatoes increased the glucose, fructose, and total sugar levels significantly. The RNA sequencing results of grapevine transgenic calli showed that many sugar transporter genes and invertase genes were upregulated and suggest that VvSWEET10 may mediate sugar accumulation. These findings elucidated the role of VvSWEET10 in sugar accumulation and will be beneficial for the improvement of grape berry quality in the future.

scholarly journals Energization of the Sugar Transport Mechanism in the Plasmalemma of Isolated Mesophyll Protoplasts

1980 ◽  
Vol 65 (3) ◽  
pp. 550-553 ◽  
Author(s):  
Micha Guy ◽  
Leonora Reinhold ◽  
Michaela Rahat
Keyword(s):  
Transport Mechanism ◽  
Sugar Transport ◽  
Mesophyll Protoplasts

Galactose transport inhibition by cytochalasin E in rat intestine in vitro

1999 ◽  
Vol 77 (2) ◽  
pp. 96-101 ◽  
Author(s):  
Ana Díez-Sampedro ◽  
Elena Urdaneta ◽  
M Pilar Lostao ◽  
Ana Barber
Keyword(s):  
Brush Border Membrane ◽  
Sugar Transport ◽  
Membrane Vesicles ◽  
Inhibitory Effect ◽  
Rat Intestine ◽  
Cytochalasin E ◽  
Galactose Transport ◽  
Wet Weight ◽  
Everted Sacs

Cytochalasins are cytoskeleton disrupters, and cytochalasin E has been reported to increase intestinal paracellular permeability. In this study, the cytochalasin E effect on galactose transport has been investigated. Ussing-type chamber experiments show an inhibitory effect of 20 µM cytochalasin E on unidirectional mucosal to serosal flux of galactose. On the contrary, the opposite unidirectional flux is not modified by the inhibitor. Results using intestinal everted sacs and rings confirm that galactose uptake by the tissue is diminished by cytochalasin E. The effect appears already after 5 min incubation, depends on cytochalasin E concentration, and does not occur in the absence of Na+. The inhibition is accompanied by an increase in the apparent Km of the active sugar transport (11.5 vs.15.8 mM) without significant change in the Vmax (10.6 vs. 9.1 µmol·g-1 wet weight·5 min-1). Cytochalasin E does not modify either galactose uptake by brush border membrane vesicles or Na+-K+ ATPase activity in the enterocytes, indicating that the inhibitory effect on the Na+-dependent sugar transport cannot be explained as a direct effect on SGLT1 activity or as an indirect effect through the Na+-K+ ATPase. Thus, our results suggest that cytochalasin E decreases SGLT1 activity indirectly through cytoskeleton disruption.Key words: cytochalasin E, intestinal absorption, cytoskeleton.

scholarly journals Inhibitory Effect of Metalloproteinase Inhibitors on Skin Cell Inflammation Induced by Jellyfish Nemopilema nomurai Nematocyst Venom

Toxins ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 156 ◽  
Author(s):  
Aoyu Li ◽  
Huahua Yu ◽  
Rongfeng Li ◽  
Song Liu ◽  
Ronge Xing ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
Research Area ◽  
Cellular Level ◽  
Inflammatory Factors ◽  
Nemopilema Nomurai ◽  
Whole Process ◽  
Skin Cell ◽  
Tnf Α ◽  
Main Components ◽  
Jellyfish Venom

Jellyfish envenomations result in extensive dermatological symptoms, clinically named as jellyfish dermatitis, which can seriously affect the daily activities and physical health of people. Inflammatory response accompanies the whole process of jellyfish dermatitis and the complexity of jellyfish venom components makes it difficult to treat jellyfish dermatitis symptoms effectively. Moreover, inhibiting inflammation is essential for the treatment of jellyfish stings and exploring the main components of jellyfish venom that cause inflammation is an urgent research area. In this study, the inhibitory effects of matrix metalloproteinase (MMP) inhibitors for venom-induced inflammation were explored at a cellular level. The expression of the three inflammatory factors, IL-6, TNF-α and MCP-1 in two skin cell lines, human keratinocyte cells (HaCaT) and human embryonic skin fibroblasts cells (CCC-ESF-1), at the cellular level, after treatment with the inhibitors of jellyfish Nemopilema nomurai (N. nomurai) nematocyst venom (NnNV-I), were determined. The results showed that inhibitors of MMP can significantly reduce the toxic effects of jellyfish Nemopilema nomurai nematocyst venom (NnNV) to skin cells. The expression levels of the three inflammatory factors IL-6, MCP-1, and TNF-α in the cells were also significantly decreased, indicating that MMPs in jellyfish venom are probably vital factors leading to jellyfish dermatitis. This study is beneficial in the prevention and treatment of jellyfish stings.

Kinetic studies on transport of PAH and other organic acids in isolated renal tubules

1965 ◽  
Vol 208 (2) ◽  
pp. 391-396 ◽  
Author(s):  
K. C. Huang ◽  
Dorothy S. T. Lin
Keyword(s):  
Organic Acids ◽  
Partition Coefficient ◽  
Transport Mechanism ◽  
Hippuric Acid ◽  
Kinetic Studies ◽  
Inhibitory Effect ◽  
Renal Tubules ◽  
High Concentration ◽  
Low Concentration ◽  
Tubular Transport

Studies were made on the uptake and washout of PAH and other organic acids in isolated renal tubules and cells at 25 C. The renal tubules accumulated PAH rapidly in the first 30-min period. Probenecid, its diethyl- and dimethyl analogues, hippuric acid, and 2,4-dinitrophenol inhibited the tubular transport of PAH competitively. A relationship between the inhibitory effect and the partition coefficient of the compound was observed; the higher the partition coefficient, the greater the inhibition. DNP was also accumulated in the isolated renal tubules. This accumulation was depressed by probenecid, indicating that DNP is probably transported by the same tubular transport mechanism for PAH and other organic acids. In washout experiments probenecid and DNP showed a biphasic action, namely, they stimulated the PAH washout in low concentration and inhibited it in high concentration However, hippuric acid, which has a low partition coefficient, demonstrated an augmentation of PAH washout even at a concentration of 2 x 10–2 m

scholarly journals Active Sugar Transport by the Small Intestine

1968 ◽  
Vol 52 (3) ◽  
pp. 482-494 ◽  
Author(s):  
Robert G. Faust ◽  
Mary G. Leadbetter ◽  
Regina K. Plenge ◽  
Alston J. McCaslin
Keyword(s):  
Small Intestine ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Sugar Transport ◽  
Initial Step ◽  
Inhibitory Effect ◽  
Glucose Binding ◽  
Brush Borders

Tris-disrupted and intact brush border membrane preparations from mucosa of hamster jejunum were capable of preferentially binding actively transported D-glucose in a similar manner. Density gradient centrifugation of the Tris-disrupted brush borders indicated that D-glucose was bound to a fraction containing the cores or inner material of the microvilli. The properties of this binding were examined with the Tris-disrupted brush border preparation. Actively transported sugars competitively inhibited preferential D-glucose binding, whereas no effect was observed with nonactively transported sugars. Neither actively nor nonactively transported amino acids affected D-glucose binding. D-Glucosamine, which is not actively transported, was inhibitory to preferential D-glucose binding as well as to the active transport of D-glucose by everted sacs of hamster jejunum. No inhibitory effect was observed with the same concentration of D-galactosamine. Preferential D-glucose binding was also inhibited by sulfhydryl-reacting compounds, Ca2+, and Li+ ions. On the other hand, Mg2+ was shown to be stimulatory and Na+, NH4+, and K+ had no effect on this phenomenon. The results of these experiments suggest that preferential D-glucose binding to brush borders is related to the initial step in active sugar transport by the small intestine.

scholarly journals The Hexose-Proton Cotransport System of Chlorella

1974 ◽  
Vol 64 (5) ◽  
pp. 568-581 ◽  
Author(s):  
Ewald Komor ◽  
Widmar Tanner
Keyword(s):  
Sugar Transport ◽  
Protonated Form ◽  
Weak Acid ◽  
Sugar Uptake ◽  
Sugar Accumulation ◽  
Maximal Velocity ◽  
Uptake System ◽  
High Affinity ◽  
Ph Values ◽  
Proton Concentration

The proton concentration in the medium affects the maximal velocity of sugar uptake with a Km of 0.3 mM (high affinity uptake). By decreasing the proton concentration a decrease in high affinity sugar uptake is observed, in parallel the activity of a low affinity uptake system (Km of 50 mM) rises. Both systems add up to 100%. The existence of the carrier in two conformational states (protonated and unprotonated) has been proposed therefore, the protonated form with high affinity to 6-deoxyglucose, the unprotonated form with low affinity. A plot of extrapolated Vmax values at low substrate concentration versus proton concentration results in a Km for protons of 0.14 µM, i.e. half-maximal protonation of the carrier is achieved at pH 6.85. The stoichiometry of protons cotransported per 6-deoxyglucose is close to 1 at pH 6.0–6.5. At higher pH values the stoichiometry continuously decreases; at pH 8.0 only one proton is cotransported per four molecules of sugar. Whereas the translocation of the protonated carrier is strictly dependent on sugar this coupling is less strict for the unprotonated form. Therefore at alkaline pH a considerable net efflux of accumulated sugar can occur. The dependence of sugar accumulation on pH has been measured. The decrease in accumulation with higher pH values can quantitatively be explained by the decrease in the amount of protonated carrier. The properties of the unprotonated carrier resemble strikingly the properties of carrier at the inner side of the membrane. The inside pH of Chlorella was measured with the weak acid 5,5-dimethyl-2, 4-oxazolidinedion (DMO). At an outside pH of 6.5 the internal pH was found to be 7.2. To explain the extent of sugar accumulation it has to be assumed that the membrane potential also contributes to active sugar transport in this alga.

scholarly journals Dopamine as a Neuroactive Substance in the Jellyfish Polyorchis Penicillatus

1991 ◽  
Vol 156 (1) ◽  
pp. 433-451
Author(s):  
JUN-MO CHUNG ◽  
ANDREW N. SPENCER
Keyword(s):  
Motor Neurons ◽  
Reversal Potential ◽  
Inhibitory Effect ◽  
Cellular Level ◽  
Potassium Ions ◽  
Current Clamp ◽  
Polyorchis Penicillatus ◽  
Outward Currents ◽  
Neuroactive Substance ◽  
Current Clamp Mode

Recent studies have shown that nerve-rich tissues in the margin of Polyorchis penicillatus (Eschscholtz), one of the hydromedusae, contain dopamine. The present experiments were conducted to determine the physiological action of dopamine at the cellular level. In the current-clamp mode, dopamine, ranging from 10−8 to 10−3moll−1, applied to cultured swimming motor neurons of this jellyfish produced hyperpolarizations accompanied by a decrease of firing rate or complete inhibition of spiking produced by anodal break excitation. Dopamine in the voltage-clamp mode elicited outward currents at more positive levels than −55 mV, which is the reversal potential of the response. The results of a series of ionic experiments suggest that the inhibitory effect of dopamine is caused by an increased permeability to potassium ions.

The Effects of Hepes Buffer on Clotting Tests, Assay of Factors V and VIII and on the Hydrolysis of Esters by Thrombin and Thrombokinase

1976 ◽  
Vol 35 (01) ◽  
pp. 202-210 ◽  
Author(s):  
Phyllis S. Roberts ◽  
Haywood N. Hughes ◽  
Patricia B. Fleming
Keyword(s):  
Ionic Strength ◽  
Human Plasma ◽  
Inhibitory Effect ◽  
Clotting Factors ◽  
Bovine Thrombin ◽  
Hepes Buffer ◽  
Human Thrombin ◽  
Ethanesulfonic Acid ◽  
Hydrolysis Of Esters ◽  
Hydrolysis Of

SummaryShorter clotting times were found in the presence of 50 mM Hepes (N-2-hydroxyethylpiper-azine-N1-2-ethanesulfonic acid) buffer than of 50 mM Imidazole buffer in one-stage assays of factors V and VIII, in modified APTT and PT tests and in tests of the clotting of human plasma by purified human thrombin. All tests were performed at ionic strength 0.155 in the presence of either Hepes. NaOH or Imidazole. HC1 buffer, pH 7.4 at 37°. The faster clotting in the presence of Hepes buffer, therefore, is probably due, at least in part, to acceleration by Hepes of thrombin’s enzymatic action on fibrinogen and/or of the polymerization of the fibrin monomers.Hepes may also have effects on other blood clotting reactions. Rates of hydrolysis of TAME or BAME (p-toluenesulfonyl-or benzoyl-L-arginine methyl ester) at pH 7.4, 37° by purified human or bovine thrombin were essentially the same in 200 mM Hepes as in 250 mM Tris. HQ buffer (rates in Hepes. NaOH or Hepes. KOH buffers were compared with those in Tris. HQ plus NaCl for KC1). However, with purified bovine thrombokinase, rates of TAME hydrolysis in Hepes buffer were accelerated and rates of BAME hydrolysis slightly inhibited. Hepes, therefore, reacts with thrombokinase but whether this accelerates (or inhibits) the rate of converting prothrombin to thrombin remains to be determined. In addition, Hepes has an inhibitory effect on clotting since increasing the concentration of Hepes from 50 mM to 200 mM inhibits clotting in the PT, APTT and bovine thrombin-human plasma tests.Hepes buffer is being added to some plasmas and to some reagents used in clotting tests. It is, therefore, important to realize that its concentration must be monitored closely or erroneous results may be obtained in clotting tests and assays of clotting factors.The clotting times were the same in the presence of 50 mM Tris. HC1 as in Imidazole. HC1 buffers in APTT tests at three ionic strengths but they differed slightly in plasma-thrombin tests. Depending upon the ionic strength, 17 mM Barbital Sodium. HC1 buffer inhibited APTT tests but accelerated plasma-thrombin tests. All the buffers tested, therefore, have individual effects on the clotting tests.

A common pathway for sugar transport in hamster intestine

1961 ◽  
Vol 200 (1) ◽  
pp. 111-116 ◽  
Author(s):  
Charles R. Jorgensen ◽  
Bernard R. Landau ◽  
T. Hastings Wilson
Keyword(s):  
Small Intestine ◽  
Transport Mechanism ◽  
Sugar Transport ◽  
The Other ◽  
Common Pathway ◽  
In Vitro Method ◽  
Single Segment ◽  
Other Hand

The competition between different sugars for the transport mechanism of hamster small intestine was tested with an in vitro method which allowed the use of a single segment of intestine for both control and experimental periods. The transport of the test sugar d-galactose was inhibited by other sugars known to be actively absorbed by the intestine; namely, d-glucose, α-methyl-d-glucoside, i-deoxy-d-glucose, 6-deoxy-d-glucose and 3-o-methyl-d-glucose. On the other hand d-mannose and d-xylose, two sugars not actively transported, did not inhibit d-galactose absorption. In addition, sugars known to be actively absorbed produced an inhibition of transport of d-glucose and 6-deoxy-d-glucose when these were selected as test sugars. The results of these experiments are consistent with the view that all transported sugars compete for a common pathway in hamster intestine. Various hypotheses of sugar transport are discussed in light of the present data.

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