3-O-methyl-D-glucose transport in tumoral insulin-producing cells

1986 ◽  
Vol 251 (6) ◽  
pp. C841-C846 ◽  
Author(s):  
W. J. Malaisse ◽  
M. H. Giroix ◽  
F. Malaisse-Lagae ◽  
A. Sener
Keyword(s):  
Plasma Membrane ◽  
Low Temperature ◽  
Glucose Transport ◽  
Concentration Gradient ◽  
Glucose Oxidation ◽  
Temperature Sensitive ◽  
Insulin Producing Cells ◽  
Different Temperatures ◽  
High Concentrations ◽  
Tumoral Cells

Tumoral insulin-producing cells of the RINm5F line were exposed at different temperatures, and for various lengths of time to increasing concentrations of 3-O-methyl-D-[U-14C]glucose. The uptake of the hexose represented a temperature-sensitive and saturable process, so that no rapid equilibration of hexose concentrations across the plasma membrane was reached, especially at low temperature and/or high concentrations of 3-O-methyl-D-glucose. The uptake of 3-O-methyl-D-[U-14C]glucose was not affected by a prior loading of the cells with the unlabeled hexose and its release from prelabeled cells was observed in the absence of any concentration gradient across the plasma membrane. The uptake of D-[U-14C]glucose and utilization of D-[5-3H]glucose was inhibited by 3-O-methyl-D-glucose, which failed, however, to affect D-[U-14C]glucose oxidation. At variance with the situation found in normal insulin-producing cells, the transport of D-glucose into the tumoral cells may thus play a regulatory role in its metabolism.

scholarly journals Functional expression, quantification and cellular localization of the Hxt2 hexose transporter of Saccharomyces cerevisiae tagged with the green fluorescent protein

1999 ◽  
Vol 339 (2) ◽  
pp. 299-307 ◽  
Author(s):  
Arthur L. KRUCKEBERG ◽  
Ling YE ◽  
Jan A. BERDEN ◽  
Karel van DAM
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Green Fluorescent Protein ◽  
Glucose Transport ◽  
Cellular Localization ◽  
Fluorescent Protein ◽  
Hexose Transporter ◽  
High Concentrations ◽  
Green Fluorescent

The Hxt2 glucose transport protein of Saccharomyces cerevisiae was genetically fused at its C-terminus with the green fluorescent protein (GFP). The Hxt2-GFP fusion protein is a functional hexose transporter: it restored growth on glucose to a strain bearing null mutations in the hexose transporter genes GAL2 and HXT1 to HXT7. Furthermore, its glucose transport activity in this null strain was not markedly different from that of the wild-type Hxt2 protein. We calculated from the fluorescence level and transport kinetics that induced cells had 1.4×105 Hxt2-GFP molecules per cell, and that the catalytic-centre activity of the Hxt2-GFP molecule in vivo is 53 s-1 at 30 °C. Expression of Hxt2-GFP was induced by growth at low concentrations of glucose. Under inducing conditions the Hxt2-GFP fluorescence was localized to the plasma membrane. In a strain impaired in the fusion of secretory vesicles with the plasma membrane, the fluorescence accumulated in the cytoplasm. When induced cells were treated with high concentrations of glucose, the fluorescence was redistributed to the vacuole within 4 h. When endocytosis was genetically blocked, the fluorescence remained in the plasma membrane after treatment with high concentrations of glucose.

scholarly journals Effects of glucocorticoid excess on the sensitivity of glucose transport and metabolism to insulin in rat skeletal muscle

1997 ◽  
Vol 321 (3) ◽  
pp. 707-712 ◽  
Author(s):  
George DIMITRIADIS ◽  
Brendan LEIGHTON ◽  
Mark PARRY-BILLINGS ◽  
Shlomo SASSON ◽  
Martin YOUNG ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Glucose Transport ◽  
Soleus Muscle ◽  
Glucose Oxidation ◽  
Glycogen Synthesis ◽  
Total Content ◽  
Glucose Transporters ◽  
Lactate Formation

This study examines the mechanisms of glucocorticoid-induced insulin resistance in rat soleus muscle. Glucocorticoid excess was induced by administration of dexamethasone to rats for 5 days. Dexamethasone decreased the sensitivity of 3-O-methylglucose transport, 2-deoxyglucose phosphorylation, glycogen synthesis and glucose oxidation to insulin. The total content of GLUT4 glucose transporters was not decreased by dexamethasone; however, the increase in these transporters in the plasma membrane in response to insulin (100 m-units/litre) was lessened. In contrast, the sensitivity of lactate formation to insulin was normal. The content of 2-deoxyglucose in the dexamethasone-treated muscle was decreased at 100 m-units/litre insulin, while the contents of glucose 6-phosphate and fructose 2,6-bisphosphate were normal at all concentrations of insulin studied. The maximal activity of hexokinase in the soleus muscle was not affected by dexamethasone; however, inhibition of this enzyme by glucose 6-phosphate was decreased. These results suggest the following. (1) Glucocorticoid excess causes insulin resistance in skeletal muscle by directly inhibiting the translocation of the GLUT4 glucose transporters to the plasma membrane in response to insulin; since the activity of hexokinase is not affected, the changes in the sensitivity of glucose phosphorylation to insulin seen under these conditions are secondary to those in glucose transport. (2) The sensitivity of glycogen synthesis and glucose oxidation to insulin is decreased, but that of glycolysis is not affected: a redistribution of glucose away from the pathway of glycogen synthesis and glucose oxidation could maintain a normal rate of lactate formation although the rate of glucose transport is decreased.

scholarly journals A role for sulfhydryl groups in granulocyte aggregation

Blood ◽  
1984 ◽  
Vol 63 (5) ◽  
pp. 1056-1059 ◽  
Author(s):  
EH Kraut ◽  
AL Jr Sagone
Keyword(s):  
Plasma Membrane ◽  
Sulfonic Acid ◽  
Polymorphonuclear Leukocytes ◽  
Glucose Oxidation ◽  
Binding Agent ◽  
Tertiary Butyl ◽  
Aggregation Response ◽  
High Concentrations ◽  
Induced Aggregation ◽  
Cellular Aggregates

Abstract Polymorphonuclear leukocytes (PMN) stimulated by high concentrations of the complement component C5A form cellular aggregates, and both the rate and degree of aggregation are influenced by changes in the PMN plasma membrane and cytoskeleton. Since sulfhydryls are important constituents of the plasma membrane and cytoskeleton, we investigated the effect of agents that oxidize and bind sulfhydryls on C5A-induced aggregation. PMN incubated with diamide, a nonspecific sulfhydryl- oxidizing agent, had a marked increase in their aggregation response to C5A. Tertiary butyl hydroperoxide (BHP), which reacts specifically with the soluble sulfhydryl glutathione (GSH), had no effect on aggregation. The enhancement of PMN aggregation by diamide, but not BHP, suggested that oxidation of non-GSH sulfhydryls contributes to the aggregation response. To test the requirement for sulfhydryls in PMN aggregation, PMN were treated with the sulfhydryl-binding agent N-ethylmaleimide (NEM). NEM markedly impaired aggregation without affecting resting or methylene blue-stimulated [14C]-L-glucose oxidation of the granulocytes. P-chloromercuriphenyl sulfonic acid (PCMPSA), an external sulfhydryl-binding agent, had no effect on aggregation. These studies suggest that cellular sulfhydryls are required for optimal PMN aggregation and that oxidation of these sulfhydryls may be one of the biochemical changes that contributes to aggregation.

Adaptations of plasma membrane glucose transport facilitate cryoprotectant distribution in freeze-tolerant frogs

1993 ◽  
Vol 265 (5) ◽  
pp. R1036-R1042 ◽  
Author(s):  
P. A. King ◽  
M. N. Rosholt ◽  
K. B. Storey
Keyword(s):  
Plasma Membrane ◽  
Glucose Transport ◽  
Plasma Membranes ◽  
Membrane Vesicles ◽  
Rana Sylvatica ◽  
Glucose Transporters ◽  
Freeze Tolerance ◽  
Leopard Frog ◽  
Freeze Tolerant ◽  
High Concentrations

Natural freeze tolerance in several anuran species involves the accumulation of high concentrations of glucose as a cryoprotectant in body fluids and tissues. The present study identifies an important new molecular mechanism supporting freeze tolerance, an adaptive increase in the capacity for facilitated transport of cryoprotectant across plasma membranes by increasing the numbers and/or activity of plasma membrane glucose transporters. Glucose transport by membranes isolated from liver and skeletal muscle was analyzed in two species, the freeze-tolerant wood frog Rana sylvatica and the freeze-intolerant leopard frog Rana pipiens. Membranes from both liver and muscle of R. sylvatica displayed much higher rates of carrier-mediated glucose transport, measured by a rapid filtration technique, compared with corresponding rates for R. pipiens membranes. For the liver Vmax values for glucose transport by membrane vesicles were 69 +/- 18 and 8.4 +/- 2.3 nmol.mg protein-1.s-1 at 10 degrees C for R. sylvatica and R. pipiens, respectively. This difference was due primarily to a greater number of glucose transporters in R. sylvatica liver membranes; the total number of transporter sites, determined by cytochalasin B binding, was 4.7-fold higher in the freeze-tolerant species. For muscle membranes, the Vmax for glucose transport was 4.9 +/- 1 and 0.6 +/- 0.16 nmol.mg-1 x s-1 at 22 degrees C for R. sylvatica and R. pipiens, respectively. However, in muscle there were no differences in the number of membrane transporters between species.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals A role for sulfhydryl groups in granulocyte aggregation

Blood ◽  
1984 ◽  
Vol 63 (5) ◽  
pp. 1056-1059
Author(s):  
EH Kraut ◽  
AL Jr Sagone
Keyword(s):  
Plasma Membrane ◽  
Sulfonic Acid ◽  
Polymorphonuclear Leukocytes ◽  
Glucose Oxidation ◽  
Binding Agent ◽  
Tertiary Butyl ◽  
Aggregation Response ◽  
High Concentrations ◽  
Induced Aggregation ◽  
Cellular Aggregates

Polymorphonuclear leukocytes (PMN) stimulated by high concentrations of the complement component C5A form cellular aggregates, and both the rate and degree of aggregation are influenced by changes in the PMN plasma membrane and cytoskeleton. Since sulfhydryls are important constituents of the plasma membrane and cytoskeleton, we investigated the effect of agents that oxidize and bind sulfhydryls on C5A-induced aggregation. PMN incubated with diamide, a nonspecific sulfhydryl- oxidizing agent, had a marked increase in their aggregation response to C5A. Tertiary butyl hydroperoxide (BHP), which reacts specifically with the soluble sulfhydryl glutathione (GSH), had no effect on aggregation. The enhancement of PMN aggregation by diamide, but not BHP, suggested that oxidation of non-GSH sulfhydryls contributes to the aggregation response. To test the requirement for sulfhydryls in PMN aggregation, PMN were treated with the sulfhydryl-binding agent N-ethylmaleimide (NEM). NEM markedly impaired aggregation without affecting resting or methylene blue-stimulated [14C]-L-glucose oxidation of the granulocytes. P-chloromercuriphenyl sulfonic acid (PCMPSA), an external sulfhydryl-binding agent, had no effect on aggregation. These studies suggest that cellular sulfhydryls are required for optimal PMN aggregation and that oxidation of these sulfhydryls may be one of the biochemical changes that contributes to aggregation.

NBD-labeled phosphatidylcholine enters the yeast vacuole via the pre-vacuolar compartment

2002 ◽  
Vol 115 (13) ◽  
pp. 2725-2733 ◽  
Author(s):  
Pamela K. Hanson ◽  
Althea M. Grant ◽  
J. Wylie Nichols
Keyword(s):  
Plasma Membrane ◽  
Low Temperature ◽  
Head Group ◽  
Temperature Sensitive ◽  
Vesicular Traffic ◽  
Yeast Vacuole ◽  
Golgi Transport ◽  
Vacuolar Compartment ◽  
Wild Type Yeast ◽  
Similar Enrichment

At low temperature, the short-chain fluorescent-labeled phospholipids,1-myristoyl-2-[6-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)aminocaproyl]-phosphatidylcholine (M-C6-NBD-PC) and its phosphatidylethanolamine analog, M-C6-NBD-PE, are internalized by flip across the plasma membrane of S. cerevisiae and show similar enrichment in intracellular membranes including the mitochondria and nuclear envelope/ER. At higher temperatures (24-37°C), or if low temperature internalization is followed by warming, M-C6-NBD-PC, but not M-C6-NBD-PE, is trafficked to the lumen of the vacuole. Sorting of M-C6-NBD-PC to the vacuole is blocked by energy-depletion and by null mutations in the VPS4 and VPS28 genes required for vesicular traffic from the pre-vacuolar compartment (PVC) to the vacuole. This sorting is not blocked by a temperature-sensitive mutation in SEC12,which inhibits ER to Golgi transport, a null mutation in VPS8, which inhibits Golgi to PVC transport, or temperature-sensitive and null mutations in END4, which inhibit endocytosis from the plasma membrane. Monomethylation or dimethylation of the primary amine head-group of M-C6-NBD-PE is sufficient for sorting to the yeast vacuole in both wild-type yeast and in strains defective in the phosphatidylethanolamine methylation pathway. These data indicate that methylation of M-C6-NBD-PE produces the crucial structural component required to sort these phospholipid analogues to the vacuole via the PVC.

Development of High Permeability Core Materials for Embeddable Inductors in Flexible Organic Substrates

2003 ◽  
Vol 769 ◽  
Author(s):  
C. K. Liu ◽  
P. L. Cheng ◽  
S. Y. Y. Leung ◽  
T. W. Law ◽  
D. C. C. Lam
Keyword(s):  
Low Temperature ◽  
Sol Gel ◽  
Circuit Board ◽  
Organic Substrates ◽  
Circuit Boards ◽  
High Permeability ◽  
Electrical Measurements ◽  
Different Temperatures ◽  
Spiral Inductors ◽  
Ceramic Tape

AbstractCapacitors, resistors and inductors are surface mounted components on circuit boards, which occupy up to 70% of the circuit board area. For selected applications, these passives are packaged inside green ceramic tape substrates and sintered at temperatures over 700°C in a co-fired process. These high temperature processes are incompatible with organic substrates, and low temperature processes are needed if passives are to be embedded into organic substrates. A new high permeability dual-phase Nickel Zinc Ferrite (DP NZF) core fabricated using a low temperature sol-gel route was developed for use in embedded inductors in organic substrates. Crystalline NZF powder was added to the sol-gel precursor of NZF. The solution was deposited onto the substrates as thin films and heat-treated at different temperatures. The changes in the microstructures were characterized using XRD and SEM. Results showed that addition of NZF powder induced low temperature transformation of the sol-gel NZF phase to high permeability phase at 250°C, which is approximately 350°C lower than transformation temperature for pure NZF sol gel films. Electrical measurements of DP NZF cored two-layered spiral inductors indicated that the inductance increased by three times compared to inductors without the DP NZF cores. From microstructural observations, the increase is correlated with the changes in microstructural connectivity of the powder phase.

scholarly journals GERMINATION AND VIGOUR IN SEEDS OF THE COWPEA IN RESPONSE TO SALT AND HEAT STRESS

2019 ◽  
Vol 32 (1) ◽  
pp. 143-151 ◽  
Author(s):  
Luma Rayane de Lima Nunes ◽  
Paloma Rayane Pinheiro ◽  
Charles Lobo Pinheiro ◽  
Kelly Andressa Peres Lima ◽  
Alek Sandro Dutra
Keyword(s):  
Salt Stress ◽  
Heat Stress ◽  
High Temperature ◽  
Low Temperature ◽  
Vigna Unguiculata ◽  
Salt Concentration ◽  
Dry Weight ◽  
Germination Percentage ◽  
Different Types ◽  
Different Temperatures

ABSTRACT Salinity is prejudicial to plant development, causing different types of damage to species, or even between genotypes of the same species, with the effects being aggravated when combined with other types of stress, such as heat stress. The aim of this study was to evaluate the tolerance of cowpea genotypes (Vigna unguiculata L. Walp.) to salt stress at different temperatures. Seeds of the Pujante, Epace 10 and Marataoã genotypes were placed on paper rolls (Germitest®) moistened with different salt concentrations of 0.0 (control), 1.5, 3.0, 4.5 and 6.0 dS m-1, and placed in a germination chamber (BOD) at temperatures of 20, 25, 30 and 35°C. The experiment was conducted in a completely randomised design, in a 3 × 4 × 5 scheme of subdivided plots, with four replications per treatment. The variables under analysis were germination percentage, first germination count, shoot and root length, and total seedling dry weight. At temperatures of 30 and 35°C, increases in the salt concentration were more damaging to germination in the Epace 10 and Pujante genotypes, while for the Marataoã genotype, damage occurred at the temperature of 20°C. At 25°C, germination and vigour in the genotypes were higher, with the Pujante genotype proving to be more tolerant to salt stress, whereas Epace 10 and Marataoã were more tolerant to high temperatures. Germination in the cowpea genotypes was more sensitive to salt stress when subjected to heat stress caused by the low temperature of 20°C or high temperature of 35°C.

scholarly journals Efforts towards a low-temperature-sensitive physics package for vapor cell atomic clocks

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Qiang Hao ◽  
Wenxiang Xue ◽  
Feng Xu ◽  
Kemu Wang ◽  
Peter Yun ◽  
...  
Keyword(s):  
Low Temperature ◽  
Temperature Sensitive ◽  
Atomic Clocks ◽  
Vapor Cell
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