Competitor and substrate sizes and diffusion together define enzymatic depolymerization and microbial substrate uptake rates

2019 ◽  
Vol 139 ◽  
pp. 107624 ◽  
Author(s):  
Jinyun Tang ◽  
William J. Riley
Keyword(s):  
Substrate Uptake ◽  
Uptake Rates ◽  
And Diffusion ◽  
Enzymatic Depolymerization

The specificity of purine base and nucleoside uptake in promastigotes ofLeishmania braziliensis panamensis

Parasitology ◽  
1982 ◽  
Vol 85 (2) ◽  
pp. 271-282 ◽  
Author(s):  
B. D. Hansen ◽  
J. Perez-Arbelo ◽  
J. F. Walkony ◽  
L. D. Hendricks
Keyword(s):  
Competitive Interactions ◽  
Leishmania Braziliensis ◽  
Purine Base ◽  
Purine Bases ◽  
Uptake Rates ◽  
Nucleoside Uptake ◽  
And Diffusion

SUMMARYPromastigotes ofLeishmania braziliensis panamensisabsorbed the purines adenine, hypoxanthine, adenosine and inosine by a combination of diffusion and mediated components. When the uptake rates for these substrates were corrected for diffusion and compared, the purine bases adenine and hypoxanthine were transported at a significantly slower rate than the purine nucleosides adenosine and inosine. Competitive interactions among those purines tested confirmed the presence of mediated and diffusion components and suggested that three transport loci may be operating (Fig. 6). The first transport locus, designated Locus 1, transported inosine, Locus 2, the purine bases hypoxanthine and adenine and Locus 3, adenosine. In addition, adenine and hypoxanthine inhibited the uptake of one another competitively. A comparison of Kivalues derived from double reciprocal plots of labelled hypoxanthine and adenine uptake in the presence of the unlabelled substrates as inhibitors suggested that adenine has a greater affinity for the transport locus.

AMPKα2 deficiency uncovers time dependency in the regulation of contraction-induced palmitate and glucose uptake in mouse muscle

2011 ◽  
Vol 111 (1) ◽  
pp. 125-134 ◽  
Author(s):  
Marcia J. Abbott ◽  
Lindsey D. Bogachus ◽  
Lorraine P. Turcotte
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Muscle Contraction ◽  
Glucose Uptake ◽  
Time Dependent ◽  
Substrate Uptake ◽  
Dependent Manner ◽  
Mouse Muscle ◽  
Uptake Rates ◽  
Intracellular Ca

AMP-activated protein kinase (AMPK) is a fuel sensor in skeletal muscle with multiple downstream signaling targets that may be triggered by increases in intracellular Ca2+ concentration ([Ca2+]). The purpose of this study was to determine whether increases in intracellular [Ca2+] induced by caffeine act solely via AMPKα2 and whether AMPKα2 is essential to increase glucose uptake, fatty acid (FA) uptake, and FA oxidation in contracting skeletal muscle. Hindlimbs from wild-type (WT) or AMPKα2 dominant-negative (DN) transgene mice were perfused during rest ( n = 11), treatment with 3 mM caffeine ( n = 10), or muscle contraction ( n = 11). Time-dependent effects on glucose and FA uptake were uncovered throughout the 20-min muscle contraction perfusion period ( P < 0.05). Glucose uptake rates did not increase in DN mice during muscle contraction until the last 5 min of the protocol ( P < 0.05). FA uptake rates were elevated at the onset of muscle contraction and diminished by the end of the protocol in DN mice ( P < 0.05). FA oxidation rates were abolished in the DN mice during muscle contraction ( P < 0.05). The DN transgene had no effect on caffeine-induced FA uptake and oxidation ( P > 0.05). Glucose uptake rates were blunted in caffeine-treated DN mice ( P < 0.05). The DN transgene resulted in a greater use of intramuscular triglycerides as a fuel source during muscle contraction. The DN transgene did not alter caffeine- or contraction-mediated changes in the phosphorylation of Ca2+/calmodulin-dependent protein kinase I or ERK1/2 ( P > 0.05). These data suggest that AMPKα2 is involved in the regulation of substrate uptake in a time-dependent manner in contracting muscle but is not necessary for regulation of FA uptake and oxidation during caffeine treatment.

Biodegradation of phenolic compounds by an acclimated activated sludge and isolated bacteria

1998 ◽  
Vol 37 (4-5) ◽  
pp. 371-378 ◽  
Author(s):  
Germán Buitrón ◽  
Ariel González ◽  
Luz M. López-Marín
Keyword(s):  
Activated Sludge ◽  
Uptake Rate ◽  
Specific Substrate ◽  
Substrate Uptake ◽  
Pseudomonas Sp ◽  
Uptake Rates ◽  
Viable Biomass ◽  
Substrate Uptake Rate ◽  
Chryseomonas Luteola ◽  
Acclimated Activated Sludge

The degradation of a mixture of phenol, 4-chlorophenol (4CP), 2,4-dichlorophenol (24DCP) and 2,4,6-trichlorophenol (246TCP) by acclimated activated sludge and by isolated bacteria was studied. Activated sludge was acclimated for 70 days to 40 mg phenols/l then the microorganisms responsible for the CP degradation were isolated and identified. Four types of Gram-negative bacteria (Aeromonas sp., Pseudomonas sp. Flavomonas oryzihabitans, and Chryseomonas luteola) were identified. Also, two acid-fast bacilli with distinct glycolipid patterns were isolated. From their chemical composition and their growth characteristics, both isolates appeared to be mycobacteria closely related to Mycobacterium peregrinum. The degradation kinetics of each phenol by Aeromonas sp., Pseudomonas sp. Flavomonas oryzihabitans, Chryseomonas luteola and activated sludge were determined. The acclimated activated sludge degradation rates were from one to two orders of magnitude higher than those of pure strains when uptake rates were calculated in terms of the viable biomass (CFU). The specific substrate uptake rate for acclimated activated sludge varied between 8.2 and 15.8 × 10−7 mg/CFU·d (407-784 mg/gVSS·d). Aeromonas sp. had the highest specific substrate uptake rate of the pure strains, based on a VSS basis (33-57 mg/gVSS·d) but, in terms of viable biomass (5.0-15.6 × 10−8 mg/CFU·d), the Pseudomonas sp. rate was the highest. Specific substrate uptake rates were 1.8 mg chlorinated phenols/g VSS·d for unacclimated activated sludge.

Adsorption and Diffusion in HZSM-5 Zeolite Studied by an Oscillating Microbalance

1997 ◽  
Vol 62 (12) ◽  
pp. 1832-1842 ◽  
Author(s):  
Hans P. Rebo ◽  
De Chen ◽  
Marit S. A. Brownrigg ◽  
Kjell Moljord ◽  
Anders Holmen
Keyword(s):  
Gas Phase ◽  
High Sensitivity ◽  
Probe Molecules ◽  
Additional Mass ◽  
Transfer Resistance ◽  
Partial Pressures ◽  
Uptake Rates ◽  
Flow Through ◽  
Tapered Element Oscillating Microbalance ◽  
And Diffusion

A novel microbalance technique has been used to study diffusion and adsorption in a commercial HZSM-5 zeolite. This new technique uses an inertial microbalance TEOM (Tapered Element Oscillating Microbalance) to measure mass changes in the zeolite bed. Time resolution as short as 0.1 s, a flow-through design where all the probe molecules see the zeolite bed and high sensitivity allowing zeolite loadings down to a few milligrams are the three most important properties of the TEOM. The probe molecules studied were o-xylene, p-xylene and toluene which were introduced at 303, 373 or 473 K and at partial pressures in the range of 0.2-10 kPa. The inverse characteristic uptakes (D/L2), corrected (D0/L2) and steady-state (Dss/L2) diffusion times are reported. The thermodynamic correction used for D0/L2 calculations almost eliminated the concentration dependence of the diffusivities. The Dss/L2 values were found to be rather unaffected by both temperature (373-473 K) and concentration, suggesting a certain degree of unification for diffusivities. o-Xylene uptake rates in the TEOM were found to be significantly higher than in a gravimetric microbalance under identical conditions, probably as a result of additional mass transfer resistance other than intracrystalline diffusion caused by poor contact between the gas phase and the zeolite in a conventional gravimetric microbalance.

scholarly journals Saccharomyces cerevisiae goes through distinct metabolic phases during its replicative lifespan

2018 ◽  
Author(s):  
Simeon Leupold ◽  
Georg Hubmann ◽  
Athanasios Litsios ◽  
Anne C. Meinema ◽  
Alexandros Papagiannakis ◽  
...  
Keyword(s):  
Metabolic Changes ◽  
Cellular Aging ◽  
Substrate Uptake ◽  
Comprehensive Description ◽  
Cellular Processes ◽  
Metabolic Fluxes ◽  
Age Related ◽  
Uptake Rates ◽  
Inference Methods ◽  
Holistic Description

A comprehensive description of the phenotypic changes during cellular aging is key towards unraveling its causal forces. Using recently developed experimental tools, which previously had enabled us to map age related changes in proteome and transcriptome (Janssens et al., 2015), and model-based inference methods, here, we generated a comprehensive account of the metabolic changes during the entire replicative life of Saecharomyces cerevisiae. With age, we found decreasing metabolite levels, decreasing growth and substrate uptake rates accompanied by a switch from aerobic fermentation to a respiratory metabolism, with increased glycerol and acetate production. The identification of intracellular metabolic fluxes revealed an increase in redox cofactor turnover, likely to combat the increased production of reactive oxygen species. The identified metabolic changes possibly reflect a dynamic adaptation to the age-associated, non- homeostatic increase in volume. With metabolism being an important factor of the cellular phenotype, this work complements our recent mapping of the transcriptomic and proteomic changes towards a holistic description of the cellular processes during aging.

Application of Batch Kinetic Data to the Sizing of Continuous-Flow Activated Sludge Reactors

1987 ◽  
Vol 19 (3-4) ◽  
pp. 505-516 ◽  
Author(s):  
André van Niekerk ◽  
David Jenkins ◽  
M. G. Richard
Keyword(s):  
Activated Sludge ◽  
Continuous Flow ◽  
Kinetic Data ◽  
Substrate Uptake ◽  
Flow Reactors ◽  
Linear Rate ◽  
Substrate Removal ◽  
Uptake Rates ◽  
Non Linear ◽  
Continuous Flow Reactors

The removal of substrates from wastewaters by activated sludge is commonly expressed in terms of a collective substrate parameter such as COD, BOD5 or TOC. Several different linear and non-linear rate expressions are employed to describe complex substrate removal in the literature. The indiscriminate application of batch substrate uptake rates to the analysis or design of continuous-flow reactors can introduce errors. These potential errors have particular significance in the design of aerobic selectors used to control low F/M bulking.

Lactate transport by rainbow trout white muscle: kinetic characteristics and sensitivity to inhibitors

1997 ◽  
Vol 272 (5) ◽  
pp. R1577-R1587 ◽  
Author(s):  
Y. Wang ◽  
P. M. Wright ◽  
G. J. Heigenhauser ◽  
C. M. Wood
Keyword(s):  
Rainbow Trout ◽  
White Muscle ◽  
Fish Muscle ◽  
Retention Mechanism ◽  
Disulfonic Acid ◽  
Extracellular Concentration ◽  
Carrier Mediated Transport ◽  
Uptake Rates ◽  
Resting Muscle ◽  
And Diffusion

This study used an isolated-perfused tail-trunk preparation of rainbow trout to examine the uptake and release of lactate (Lac) and metabolic protons (delta H+M) in resting and exercised fish white muscle. In exercised muscle, L(+)-Lac efflux was inhibited (approximately 40%) by 5 mM alpha-cyano-4-hydroxycinnamate (CIN), but not by 0.5 mM 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) or 0.1 mM amiloride. These results suggest that Lac release occurs through a Lac(-)-H- symport and the free diffusion of lactic acid (HLac) or Lac-, but not via the Lac-/HCO3(-)-Cl- antiporter. Lac efflux was accompanied by delta H+m influx in all treatments, and increased delta H+m influx occurred after SITS treatment. In resting muscle, Lac uptake rates were greater than Lac efflux rates in the postexercise preparation. L-Lac influx exhibited partial saturation kinetics, whereas D(-)-Lac influx was linearly related to its extracellular concentration (0-32 mM). At 16 mM extracellular L-Lac, with a negligible transmembrane L-HLac gradient and an outwardly directed not driving force on L-Lac-, CIN, and SITS reduced net L-Lac uptake by 75 and 45%, respectively. At 16 mM extracellular concentration, D-Lac influx was 64% of the net L-Lac influx. These results suggest that in trout muscle at 16 mM extracellular L-Lac, the Lac -H+ symport accounts for 30-36%, the Lac-/HCO3(-)-Cl- antiport for 39-45%, and diffusion for 19-25% of uptake, although the latter is probably overestimated and the former underestimated for methodological reasons. Net L-Lac efflux was not affected by extracellular D-Lac concentration and/or D-Lac influx, implying the existence of a concurrent L-Lac efflux during L-Lac influx. The D-Lac influx kinetics data indicated that the Lac-/HCO3 antiport was not saturable in the extracellular D-Lac concentration range of 0-32 mM. This study clearly demonstrates the involvement of carrier-mediated transport in transmembrane Lac movement in fish muscle and supports the "active lactate retention" mechanism proposed by Turner and Wood (J. Exp. Biol. 105: 895-401, 1983).

Nutrient relations of winter wheat: 2. Movement of nutrients to the root and their uptake

1979 ◽  
Vol 93 (2) ◽  
pp. 495-504 ◽  
Author(s):  
P. J. Gregory ◽  
D. V. Crawford ◽  
M. McGowan
Keyword(s):  
Winter Wheat ◽  
Mass Flow ◽  
Plant Uptake ◽  
Solution Concentration ◽  
Sodium Calcium ◽  
Uptake Rates ◽  
Calcium Magnesium ◽  
And Diffusion ◽  
Uptake Of Nutrients ◽  
Nutrient Relations

SUMMARYThe purpose of this work was to determine the relative importance of mass flow and diffusion in supplying nutrients to wheat plants and to calculate nutrient uptake rates by roots (inflow). Winter wheat was grown in the field and measurements of plant Na, K, Ca, Mg, P, S and N contents, root length, plant water uptake and soil solution concentration made at regular intervals during growth. The apparent contribution of mass flow to plant uptake of nutrients between mid- April and mid-June was greater than the measured plant uptake for sodium, calcium, magnesium and sulphur (14, 9, 2 and 4 times respectively); however, only 50 % of the measured plant uptake of nitrogen and potassium and 5% of the phosphorus was supplied in this way. There were some 7 day periods when mass flow was able to supply the measured uptake of nitrogen and potassium, and it is possible that for these nutrients the importance of mass flow and diffusion may change during growth. Mean inflows (uptake in mol/cm root/sec) were calculated from sowing until mid- June. Inflow decreased for all nutrients from high initial values to low values during the winter and rose again in mid-April and May before falling in June. The increase in inflow in mid-April was concomitant with increased shoot growth but the precise factors controlling plant demand for nutrients and uptake in the field are still ill-defined.

scholarly journals Saccharomyces cerevisiae goes through distinct metabolic phases during its replicative lifespan

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Simeon Leupold ◽  
Georg Hubmann ◽  
Athanasios Litsios ◽  
Anne C Meinema ◽  
Vakil Takhaveev ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Metabolic Changes ◽  
Cellular Aging ◽  
Substrate Uptake ◽  
Cellular Phenotype ◽  
Experimental Procedure ◽  
Metabolic Fluxes ◽  
Age Related ◽  
Uptake Rates ◽  
Holistic Description

A comprehensive description of the phenotypic changes during cellular aging is key towards unraveling its causal forces. Previously, we mapped age-related changes in the proteome and transcriptome (Janssens et al., 2015). Here, employing the same experimental procedure and model-based inference, we generate a comprehensive account of metabolic changes during the replicative life of Saccharomyces cerevisiae. With age, we found decreasing metabolite levels, decreasing growth and substrate uptake rates accompanied by a switch from aerobic fermentation to respiration, with glycerol and acetate production. The identified metabolic fluxes revealed an increase in redox cofactor turnover, likely to combat increased production of reactive oxygen species. The metabolic changes are possibly a result of the age-associated decrease in surface area per cell volume. With metabolism being an important factor of the cellular phenotype, this work complements our recent mapping of the transcriptomic and proteomic changes towards a holistic description of the cellular phenotype during aging.

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