scholarly journals A direct pathway for the conversion of propionate into pyruvate in Moraxella lwoffi

1968 ◽  
Vol 107 (1) ◽  
pp. 7-18 ◽  
Author(s):  
B. Hodgson ◽  
J. D. McGarry
Keyword(s):  
Carbon Dioxide ◽  
Nitrogen Source ◽  
Open System ◽  
Closed System ◽  
Isocitrate Lyase ◽  
Endogenous Respiration ◽  
Reserve Material ◽  
Propionate Metabolism ◽  
Cell Material ◽  
Lyase Activity

1. The identity of the organism previously known as Vibrio O1 (N.C.I.B. 8250) with a species of Moraxella is established. 2. The ability of cells to oxidize propionate is present only in cells with an endogenous respiration and this ability is increased 80-fold when the organism is grown with propionate. 3. Isocitrate lyase activity in extracts from propionate-grown cells is the same as that in extracts from lactate-grown cells, about tenfold greater than that in extracts from succinate-grown cells and slightly greater than half the activity in extracts from acetate-grown cells. 4. With arsenite as an inhibitor conditions were found in which the organism would catalyse the quantitative oxidation of propionate to pyruvate. When propionate was completely utilized pyruvate was metabolized further to 2-oxoglutarate. 5. The oxidation of propionate by cells was incomplete both in a ‘closed system’ with alkali to trap respiratory carbon dioxide and in an ‘open system’ with an atmosphere of oxygen+carbon dioxide (95:5). Acetate accumulated. Under these conditions [2−14C]- and [3−14C]-propionate gave rise to [14C]acetate. The rate of conversion of [2−14C]propionate into 14CO2, although much less than the rate of conversion of [1−14C]propionate into 14CO2, was slightly greater than the rate of conversion of [3−14C]propionate into 14CO2. 6. The oxidation of propionate by cells was complete in an ‘open system’ with an atmosphere of either oxygen or air. Under these conditions very little [1−14C]propionate was converted into 14C-labelled cell material. The conversion of [2−14C]- and [3−14C]-propionate into 14C-labelled cell material occurred at an appreciable rate, the rate for the incorporation of [3−14C]propionate being slightly more rapid. In the absence of a utilizable nitrogen source part of the [14C]propionate was incorporated into some reserve material, which was oxidized when added substrate had been completely utilized. 7. [14C]-Pyruvate produced from [14C]propionate was chemically degraded. The C(1) of propionate was found only in C(1) of pyruvate. At least 86% of C(2) of pyruvate was derived from C(2) of propionate and at least 92% of C(3) of pyruvate from C(3) of propionate. 8. These results are incompatible with the operation of any of the previously described pathways for propionate metabolism except the direct one, perhaps via an activated acrylate.

scholarly journals Solute Acquisition in Glacial Melt Waters. II Argentière (French Alps): Bulk Melt Waters with Open-System Characteristics

1984 ◽  
Vol 30 (104) ◽  
pp. 44-48 ◽  
Author(s):  
A.G. Thomas ◽  
R. Raiswell
Keyword(s):  
Carbon Dioxide ◽  
Ground Water ◽  
Open System ◽  
Closed System ◽  
Atmospheric Carbon Dioxide ◽  
Major Ions ◽  
Total Alkalinity ◽  
Flow Conditions ◽  
Solute Acquisition ◽  
System Characteristics

AbstractVariations in dissolved cations, total alkalinity, sulphate, and field pH are recorded for subglacial melt and bulk melt waters (those emerging from the portal) at Argentière (France), in peak and recession flow conditions. Calcium and bicarbonate are the major ions and the bulk melt waters are demonstrated to have acquired solutes by weathering and dissolution in a system open to atmospheric carbon dioxide. Subglacial melt waters have closed-system characteristics, are close to saturation with calcite and quartz, and must be in near-equilibrium with weathered particulates. Recession-flow bulk melt waters are chemically similar to subglacial melt but have open-system characteristics, either due to re-equilibration with the atmosphere for ground-water mixing.

scholarly journals The Saccharomyces cerevisiae ICL2 Gene Encodes a Mitochondrial 2-Methylisocitrate Lyase Involved in Propionyl-Coenzyme A Metabolism

2000 ◽  
Vol 182 (24) ◽  
pp. 7007-7013 ◽  
Author(s):  
Marijke A. H. Luttik ◽  
Peter Kötter ◽  
Florian A. Salomons ◽  
Ida J. van der Klei ◽  
Johannes P. van Dijken ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nitrogen Source ◽  
Coenzyme A ◽  
Isocitrate Lyase ◽  
Significant Activity ◽  
Mrna Levels ◽  
Wild Type ◽  
Cell Extracts ◽  
Lyase Activity ◽  
Null Mutants

ABSTRACT The Saccharomyces cerevisiae ICL1 gene encodes isocitrate lyase, an essential enzyme for growth on ethanol and acetate. Previous studies have demonstrated that the highly homologousICL2 gene (YPR006c) is transcribed during the growth of wild-type cells on ethanol. However, even when multiple copies are introduced, ICL2 cannot complement the growth defect oficl1 null mutants. It has therefore been suggested thatICL2 encodes a nonsense mRNA or nonfunctional protein. In the methylcitrate cycle of propionyl-coenzyme A metabolism, 2-methylisocitrate is converted to succinate and pyruvate, a reaction similar to that catalyzed by isocitrate lyase. To investigate whetherICL2 encodes a specific 2-methylisocitrate lyase, isocitrate lyase and 2-methylisocitrate lyase activities were assayed in cell extracts of wild-type S. cerevisiae and of isogenicicl1, icl2, and icl1 icl2 null mutants. Isocitrate lyase activity was absent in icl1 andicl1 icl2 null mutants, whereas in contrast, 2-methylisocitrate lyase activity was detected in the wild type and single icl mutants but not in the icl1 icl2mutant. This demonstrated that ICL2 encodes a specific 2-methylisocitrate lyase and that the ICL1-encoded isocitrate lyase exhibits a low but significant activity with 2-methylisocitrate. Subcellular fractionation studies and experiments with an ICL2-green fluorescent protein fusion demonstrated that theICL2-encoded 2-methylisocitrate lyase is located in the mitochondrial matrix. Similar to that of ICL1, transcription of ICL2 is subject to glucose catabolite repression. In glucose-limited cultures, growth with threonine as a nitrogen source resulted in a ca. threefold induction ofICL2 mRNA levels and of 2-methylisocitrate lyase activity in cell extracts relative to cultures grown with ammonia as the nitrogen source. This is consistent with an involvement of the 2-methylcitrate cycle in threonine catabolism.

scholarly journals Solute Acquisition in Glacial Melt Waters. II Argentière (French Alps): Bulk Melt Waters with Open-System Characteristics

1984 ◽  
Vol 30 (104) ◽  
pp. 44-48 ◽  
Author(s):  
A.G. Thomas ◽  
R. Raiswell
Keyword(s):  
Carbon Dioxide ◽  
Ground Water ◽  
Open System ◽  
Closed System ◽  
Atmospheric Carbon Dioxide ◽  
Major Ions ◽  
Total Alkalinity ◽  
Flow Conditions ◽  
Solute Acquisition ◽  
System Characteristics

AbstractVariations in dissolved cations, total alkalinity, sulphate, and field pH are recorded for subglacial melt and bulk melt waters (those emerging from the portal) at Argentière (France), in peak and recession flow conditions. Calcium and bicarbonate are the major ions and the bulk melt waters are demonstrated to have acquired solutes by weathering and dissolution in a system open to atmospheric carbon dioxide. Subglacial melt waters have closed-system characteristics, are close to saturation with calcite and quartz, and must be in near-equilibrium with weathered particulates. Recession-flow bulk melt waters are chemically similar to subglacial melt but have open-system characteristics, either due to re-equilibration with the atmosphere for ground-water mixing.

CO2 control of fruiting in Schizophyllum commune: noninvolvement of sustained isocitrate lyase derepression

1970 ◽  
Vol 16 (7) ◽  
pp. 605-608 ◽  
Author(s):  
D. A. Cotter ◽  
A. J. LaClave ◽  
W. S. Wegener ◽  
D. J. Niederpruem
Keyword(s):  
Carbon Dioxide ◽  
Isocitrate Lyase ◽  
Schizophyllum Commune ◽  
Soluble Enzyme ◽  
Basidiomycetous Fungus ◽  
Lyase Activity

The activity of the enzyme, isocitrate lyase, was repressed in glucose cultures of Schizophyllum commune and derepressed in acetate-grown mycelium of this basidiomycetous fungus. The maximum acetate-derepressed level of this soluble enzyme was comparable in individual homokaryotic mycelium or in the dikaryon. Addition of CO2, NaHCO3, or CaCO3 did not significantly derepress isocitrate lyase activity in glucose-cultures. Neither normal dikaryotic fruiting nor its inhibition by carbon dioxide resulted in marked and sustained changes in isocitrate lyase. Thus, a fluctuation in isocitrate lyase activity does not appear to be the salient response of S. commune to increased CO2 tension.

scholarly journals Isocitrate Lyase Activity in Lactobacillus murinus CNRZ 313

1983 ◽  
Vol 66 (6) ◽  
pp. 1232-1236 ◽  
Author(s):  
M.C. Albizzatti de Rivadeneira ◽  
M.C. Manca de Nadra ◽  
A.A. Pesce de Ruiz Holgado ◽  
G. Oliver
Keyword(s):  
Isocitrate Lyase ◽  
Lyase Activity ◽  
Lactobacillus Murinus

Impact of flavours, device, nicotine levels and price on adult e-cigarette users’ tobacco and nicotine product choices

2021 ◽  
pp. tobaccocontrol-2021-056599
Author(s):  
Yong Yang ◽  
Eric N. Lindblom ◽  
Ramzi G. Salloum ◽  
Kenneth D. Ward
Keyword(s):  
Open System ◽  
Closed System ◽  
Smoking Status ◽  
Discrete Choice Experiments ◽  
User Characteristics ◽  
Product Attributes ◽  
Product Choices ◽  
Nicotine Level ◽  
The Difference ◽  
The Impact

IntroductionTo understand the impact of e-cigarette devices, flavours, nicotine levels and prices on adult e-cigarette users’ choices among closed-system and open-system e-cigarettes, cigarettes and heated tobacco products (HTPs).MethodsOnline discrete choice experiments were conducted among adult (≥18 years) e-cigarette users (n=2642) in August 2020. Conditional logit regressions were used to assess the relative impact of product attributes and the interactions between product attributes and user characteristics, with stratified analyses to examine differences by smoking status and primarily used e-cigarette device and flavour.ResultsOn average, participants preferred non-tobacco and non-menthol flavours most, preferred open-system over closed-system e-cigarettes and preferred regular nicotine level over low nicotine level. However, the preference varied by demographics, smoking status and the primarily used e-cigarette device and flavour. The differences in preference among products/devices were larger than the difference among flavours or nicotine levels. Participants who primarily used closed-system e-cigarettes exhibited similar preferences for closed-system and open-system e-cigarettes, but those who primarily used open-system e-cigarettes preferred much more open-system over closed-system e-cigarettes. HTP was the least preferred product, much lower than cigarettes in general, but participants living in states where IQOS is being sold had similar preferences to cigarettes and HTPs.ConclusionsPeople are unlikely to switch to another product/device because of the restriction of flavour or nicotine level. If non-tobacco and non-menthol flavours were banned from open-system e-cigarettes, users may switch to menthol flavour e-cigarettes. Intervention strategies should be tailored to specific groups.

scholarly journals STUDIES IN RESPIROMETRY

1932 ◽  
Vol 16 (1) ◽  
pp. 5-22 ◽  
Author(s):  
William R. Thompson
Keyword(s):  
Carbon Dioxide ◽  
Closed System ◽  
System A ◽  
Moist Environment ◽  
Considerable Detail ◽  
Oxygen Concentrations

A machine has been described which combines volumetric and refractometric means of observing changes in carbon dioxide and oxygen concentrations and amounts in a closed system suitable for containing a respiring system. A means of thermoregulation has been described briefly. The theory upon which estimation is based has been outlined in considerable detail and generality; indicating how dependence upon absorption of gases by reagents can be eliminated completely, although they may be used in certain instances as a means of independent check. An experiment of this nature has been reported as an illustration of one use of the machine. Data of other experiments in which a moist environment was employed for the respiring system will be given in another communication.

Acetate metabolism in Escherichia coli

1978 ◽  
Vol 24 (2) ◽  
pp. 149-153 ◽  
Author(s):  
T. M. Lakshmi ◽  
Robert B. Helling
Keyword(s):  
Isocitrate Dehydrogenase ◽  
Citrate Synthase ◽  
Isocitrate Lyase ◽  
Glyoxylate Cycle ◽  
Acetate Metabolism ◽  
Wild Type ◽  
Intermediary Metabolites ◽  
Lyase Activity ◽  
Acetate Medium ◽  
The Glyoxylate Cycle

Levels of several intermediary metabolites were measured in cells grown in acetate medium in order to test the hypothesis that the glyoxylate cycle is repressed by phosphoenolpyruvate (PEP). Wild-type cells had less PEP than either isocitrate dehydrogenase – deficient cells (which had greater isocitrate lyase activity than the wild type) or isocitrate dehydrogenase – deficient, citrate synthase – deficient cells (which are poorly inducible). Thus induction of the glyoxylate cycle is more complicated than a simple function of PEP concentration. No correlation between enzyme activity and the level of oxaloacetate, pyruvate, or citrate was found either. Citrate was synthesized in citrate synthase – deficient mutants, possibly via citrate lyase.

scholarly journals Water and fertilizers use efficiency in two hydroponic systems for tomato production

2020 ◽  
Vol 38 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Rodolfo De la Rosa-Rodríguez ◽  
Alfredo Lara-Herrera ◽  
Libia Iris Trejo-Téllez ◽  
Luz Evelia Padilla-Bernal ◽  
Luis Octavio Solis-Sánchez ◽  
...  
Keyword(s):  
Nutrient Solution ◽  
Open System ◽  
Closed System ◽  
Good Alternative ◽  
Fruit Production ◽  
Tomato Production ◽  
Hydroponic System ◽  
Production Water ◽  
Use Efficiency ◽  
Hydroponic Systems

ABSTRACT The amount of water and fertilizers used in the production of vegetables, specifically tomatoes, is high. This study was carried out to determine water and fertilizers use efficiency in closed and open hydroponic systems for tomato production under greenhouse conditions. Two treatments with eight replications were assessed; each replication consisted of 67 pots with two plants each. One treatment was a closed hydroponic system (with nutrient solution recirculation), and the other was an open hydroponic system (with non-recirculating nutrient solution). We quantified the amounts of water and fertilizers applied, as well as the losses (drained nutrient solution), in the two treatments during the entire cycle of tomato. In the nutrient solution (NS) we also measured electric conductivity (EC), pH, volume applied, and volume drained, and total weight of fruits (25 pickings). There were no significant differences between the two treatments on fruit production. Water use efficiency was 59.53 kg/fruit/m3 for the closed system and 46.03 kg/fruit/m3 in the open system. In comparison to the open system, the closed system produced 13.50 kg more fruit per cubic meter of water, while 10.31 grams less fertilizers per kilogram of fruit produced were only applied. Water and fertilizers use efficiency were higher in the closed system, by 22.68% and 22.69%, respectively. More efficiency was obtained in the closed system, regarding the open system. We concluded that the closed system is a good alternative to produce tomato and preserve the resources involved in the process (like water and fertilizers), thus reducing pollution.

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