Hexose uptake by developing cotyledons of Vicia faba: physiological evidence for transporters of differing affinities and specificities

2005 ◽  
Vol 32 (11) ◽  
pp. 987 ◽  
Author(s):  
Gregory N. Harrington ◽  
Katherine E. Dibley ◽  
Raymond J. Ritchie ◽  
Christina E. Offler ◽  
John W. Patrick
Keyword(s):  
Vicia Faba ◽  
Plasma Membranes ◽  
Sugar Transport ◽  
Transfer Cell ◽  
Transport Mechanisms ◽  
Cell Complexes ◽  
Stage Of Development ◽  
Storage Parenchyma ◽  
Hexose Uptake ◽  
And Storage

Cotyledons of broad bean (Vicia faba L.) develop in an apoplasmic environment that shifts in composition from one dominated by hexoses to one dominated by sucrose. During the latter phase of development, sucrose / H+ symporter activity and expression is restricted to cotyledon epidermal transfer cell complexes that support sucrose fluxes that are 8.5-fold higher than those exhibited by the storage parenchyma. In contrast, the flux difference between these cotyledon tissues is only 1.7-fold for hexoses. Glucose and fructose uptake was shown to be sensitive to PCMBS and phloridzin, both of which slow H+-sugar transport. A low Km (or high affinity transporter, HAT) mechanism transports glucose and glucose-analogues exclusively. No HAT system for fructose could be found. A high Km (low affinity transporter, LAT) mechanism transports a broader range of hexoses, including glucose and fructose. Consistent with glucose and fructose transport being H+-coupled, their uptake was inhibited by dissipating the proton motive force (pmf) by treating cotyledons with carbonyl cyanide m-chlorophenol hydrazone, propionic acid or tetraphenylphosphonium ion. Erythrosin B inhibited hexose uptake, indicating a role for the P-type H+-ATPase in establishing the pmf. It is concluded that H+-coupled glucose and fructose transport mechanisms occur at plasma membranes of dermal transfer cell complexes and storage parenchyma cells. These transport mechanisms are active during pre- and storage phases of cotyledon development. However, hexose symport only makes a quantitative contribution to cotyledon biomass gain during the pre-storage stage of development.

Hepatic Subcellular Storage of Beta-Carotene in Rats Following Diet Supplementation

1999 ◽  
Vol 69 (1) ◽  
pp. 3-7 ◽  
Author(s):  
Bianchi-Santamaria ◽  
Stefanelli ◽  
Cembran ◽  
Gobbi ◽  
Peschiera ◽  
...  
Keyword(s):  
Liver Tissue ◽  
Plasma Membranes ◽  
Beta Carotene ◽  
Subcellular Fractions ◽  
Organ Distribution ◽  
Total Liver ◽  
Opposite Behavior ◽  
The Mean ◽  
White Fat ◽  
And Storage

Beta-carotene (BC) storage was measured in liver and its subcellular fractions (plasma membranes, mitochondria, microsomes and nuclei) of rats fed BC added to diet. The BC supplementation dose was about 350 mg/week/rat. After 15 weeks of this supplementation, rats were killed and their livers were immediately excised and processed to obtain total liver tissue and its subcellular fractions. Their BC contents were measured by HPLC as pmols/mg protein. Intact BC was found to be stored in all the above subcellular fractions, thus showing that BC is probably taken up by liver cell lipid moiety. Interestingly, the mean BC concentrations in plasma membranes and mitochondria were significantly higher than that in total liver tissue. Our data confirmed that rodents are a good animal model for the study of BC metabolism and its effects on several pathologies, and cancer prevention and treatment in humans in spite of the fact that rodents are classified as white-fat animals because of their poor BC absorption and storage in fat and blood plasma, whereas humans are classified as yellow-fat organisms because of their opposite behavior in BC uptake and organ distribution.

Amino acid and hexose transport by cultured crypt cells from rat small intestine

1980 ◽  
Vol 239 (5) ◽  
pp. C190-C196 ◽  
Author(s):  
K. Inui ◽  
A. Quaroni ◽  
L. G. Tillotson ◽  
K. J. Isselbacher
Keyword(s):  
Amino Acid ◽  
Sugar Transport ◽  
Epithelial Cell Line ◽  
Acid Uptake ◽  
Substrate Uptake ◽  
Hexose Transport ◽  
Intestinal Crypt ◽  
Morphological Criteria ◽  
Hexose Uptake ◽  
Crypt Cells

The characteristics of amino acid and sugar transport in intestinal crypt epithelial cells have been examined by measuring substrate uptake in an established epithelial cell line. These cells (IEC-6 cells) have been characterized as derived from rat small intestinal crypt cells on the basis of morphological criteria (J. Cell. Biol. 80: 248-265, 1979). Amino acid transport appeared to be mediated by both Na+-dependent and Na+-independent systems. Hexose uptake was stereospecific and Na+ independent, and was markedly inhibited by phloretin and cytochalasin B. Since glucocorticoids are known to have profound effects on maturation of the intestinal epithelium in vivo, their effects on transport properties of the cultured crypt cells were studied. Hydrocortisone, while completely inhibiting cell growth, increased the initial uptake rates of various hexoses, while having little or nor effect on the initial rate of amino acid uptake. The increased hexose uptake appeared to be due to a change in Vmax rather than Km. Appearance of the Na+-dependent hexose transport system, which is present in differentiated enterocytes, was not elicited by in vitro treatment with glucocortcoids.

Characterization of two Mg2+transporters in sealed plasma membrane vesicles from rat liver

1998 ◽  
Vol 275 (4) ◽  
pp. C995-C1008 ◽  
Author(s):  
Christie Cefaratti ◽  
Andrea Romani ◽  
Antonio Scarpa
Keyword(s):  
Plasma Membrane ◽  
Rat Liver ◽  
Intracellular Signaling ◽  
Mammalian Cells ◽  
Plasma Membranes ◽  
Membrane Vesicles ◽  
Channel Blockers ◽  
Transport Mechanisms ◽  
Plasma Membrane Vesicles ◽  
New Information

The plasma membrane of mammalian cells possesses rapid Mg2+ transport mechanisms. The identity of Mg2+ transporters is unknown, and so are their properties. In this study, Mg2+ transporters were characterized using a biochemically and morphologically standardized preparation of sealed rat liver plasma membranes (LPM) whose intravesicular content could be set and controlled. The system has the advantages that it is not regulated by intracellular signaling machinery and that the intravesicular ion milieu can be designed. The results indicate that 1) LPM retain trapped intravesicular total Mg2+with negligible leak; 2) the addition of Na+ or Ca2+ induces a concentration- and temperature-dependent efflux corresponding to 30–50% of the intravesicular Mg2+; 3) the rate of flux is very rapid (137.6 and 86.8 nmol total Mg2+ ⋅ μm−2 ⋅ min−1after Na+ and Ca2+ addition, respectively); 4) coaddition of maximal concentrations of Na+ and Ca2+ induces an additive Mg2+ efflux; 5) both Na+- and Ca2+-stimulated Mg2+ effluxes are inhibited by amiloride, imipramine, or quinidine but not by vanadate or Ca2+ channel blockers; 6) extracellular Na+ or Ca2+ can stimulate Mg2+ efflux in the absence of Mg2+ gradients; and 7) Mg2+ uptake occurs in LPM loaded with Na+ but not with Ca2+, thus indicating that Na+/Mg2+but not Ca2+/Mg2+exchange is reversible. These data are consistent with the operation of two distinct Mg2+ transport mechanisms and provide new information on rates of Mg2+ transport, specificity of the cotransported ions, and reversibility of the transport.

scholarly journals Water Influx through the Wetted Surface of a Sweet Cherry Fruit: Evidence for an Associated Solute Efflux

Plants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 440
Author(s):  
Andreas Winkler ◽  
Deborah Riedel ◽  
Daniel Alexandre Neuwald ◽  
Moritz Knoche
Keyword(s):  
Water Uptake ◽  
Sweet Cherry ◽  
Dry Mass ◽  
Bathing Solution ◽  
Full Bloom ◽  
Stage Of Development ◽  
Water Influx ◽  
Fruit Skin ◽  
Sweet Cherries ◽  
And Storage

Sweet cherries are susceptible to rain-cracking. The fruit skin is permeable to water, but also to solutes. The objectives of this study were to (1) establish whether a solute efflux occurs when a sweet cherry fruit is incubated in water; (2) identify the solutes involved; (3) identify the mechanism(s) of efflux; and (4) quantify any changes in solute efflux occurring during development and storage. Solute efflux was gravimetrically measured in wetted fruit as the increasing dry mass of the bathing solution, and anthocyanin efflux was measured spectrophotometrically. Solute and anthocyanin effluxes from a wetted fruit and water influx increased with time. All fluxes were higher for the cracked than for the non-cracked fruit. The effluxes of osmolytes and anthocyanins were positively correlated. Solute efflux depended on the stage of development and on the cultivar. In ‘Regina’, the solute efflux was lowest during stage II (25 days after full bloom (DAFB)), highest for mid-stage III (55 DAFB), and slightly lower at maturity (77 DAFB). In contrast with ‘Regina’, solute efflux in ‘Burlat’ increased continuously towards maturity, being 4.8-fold higher than in ‘Regina’. Results showed that solute efflux occurred from wetted fruit. The gravimetrically determined water uptake represents a net mass change—the result of an influx minus a solute efflux.

Sugar transport across the plasma membranes of higher plants

1994 ◽  
Vol 26 (5) ◽  
pp. 1671-1679 ◽  
Author(s):  
Norbert Sauer ◽  
Kerstin Baier ◽  
Manfred Gahrtz ◽  
Ruth Stadler ◽  
J�rgen Stolz ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Higher Plants ◽  
Sugar Transport

Large seale isolation and storage of Neurospora plasma membranes

1979 ◽  
Vol 95 (2) ◽  
pp. 554-558 ◽  
Author(s):  
Paul Stroobant ◽  
Gene A. Scarborough
Keyword(s):  
Plasma Membranes ◽  
And Storage

Numerical Modeling of Fluidic Pumping in Micronetworks of Plants

2013 ◽  
Author(s):  
Tsun-kay Jackie Sze ◽  
Jin Liu ◽  
Prashanta Dutta
Keyword(s):  
Transport Model ◽  
Sucrose Concentration ◽  
Electrical Potential ◽  
Sugar Transport ◽  
Phloem Loading ◽  
Electrical Potential Difference ◽  
Transport Mechanisms ◽  
Sucrose Transport ◽  
Membrane Electrical Potential ◽  
Plant Transport

Plant transport mechanisms are of interest in developing micropump for engineering devices. We present a two-dimensional phloem loading and transport model incorporating protein level mechanics with cellular level fluid mechanics. Governing Navier-Stokes, continuity, and Nernst-Planck equations are numerically solved to determine fluid flow and sugar transport. Phloem loading mechanics for active loading is incorporated through a six-state proton sucrose pump kinetic model. The influence of binding rates constants, concentrations, and membrane electrical potential differences on resulting sucrose transport is studied. Numerical results show that increasing rates of the sucrose transporter will noticeably increase outflow. Simulation result also show that a lower leaf sieve sucrose concentration improves outflow. In addition, a more negative membrane electrical potential difference will increase outflow. This numerical model offers insight on parameters that may be significant for implementing plant transport mechanisms in microfluidic devices.

Potential impact of CO2leakage from carbon capture and storage systems on field bean (Vicia faba)

2012 ◽  
Vol 146 (3) ◽  
pp. 261-271 ◽  
Author(s):  
Manal Al-Traboulsi ◽  
Sofie Sjögersten ◽  
Jeremy Colls ◽  
Michael Steven ◽  
Colin Black
Keyword(s):  
Vicia Faba ◽  
Carbon Capture ◽  
Storage Systems ◽  
Carbon Capture And Storage ◽  
Field Bean ◽  
Potential Impact ◽  
And Storage
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