Once again about the functional coupling between mitochondrial creatine kinase and adenine nucleotide translocase

The synthesis of creatine phosphate (CP) by mitochondrial creatine kinase during oxidative phosphorylation was terminated when the mass action ratio of the creatine kinase reaction = [ADP]·[CP][ATP]·[Cr] became equal to the apparent equilibrium constant (K _eq ^app) of this reaction. Subsequent excess of over the K _eq ^app was due to an increase in the ADP concentration in the medium. A comparable increase in the ADP concentration also occurred in the absence of creatine (Cr) in the incubation medium. Increase in the ADP concentration was shown to be associated with a decrease in the rate of oxidative phosphorylation and with a relative increase in the ATPase activity of mitochondria during the incubation. A low concentration of ADP (<30 M) and relatively high concentrations (1-6 mM) of other components of the creatine kinase reaction prevented the detection of the reverse reaction within 10 min after exceeded the K _eq ^app, but the reverse reaction became evident on more prolonged incubation. The reverse reaction was accompanied by a further increase in . Low ADP concentration in the medium was also responsible for the lack of an immediate conversion of the excess creatine phosphate added although > K _eq ^app. The findings are concluded to be in contradiction with the concept of microcompartment formation between mitochondrial creatine kinase and adenine nucleotide translocase.     

Quantitative measurement of cell-bubble attachment in bubble columns using foam flotation techniques

A simple and convenient system for quantitatively measuring the number of adsorbed animal cells per unit of bubble surface area (, unit: cells/cm2) was developed. The system was successfully applied to recombinant Chinese hamster ovary (r-CHO) suspension cultures to investigate the dynamic cell-bubble attachment in a bubble column. In serum-free medium, values increased with bubble rising height (H) and cell concentration (C) and then became constant (about 1750 cells/cm2) when H and C were sufficiently high. In medium containing protective additives, the trends of values with H were similar to that in serum-free medium. Compared with serum-free medium, polyvinyl-pyrrolidone (PVP) increased the values to 1941 cell/cm2 whereas other tested additives decreased the values of in some different degree.     

Intraspecific variation for CO2 compensation point and differential growth among variants in a C3−C4 intermediate plant

CO₂ compenstation point (), the concentration of CO₂ at which photosynthesis and respiration are at equilibrium, is a commonly used diagnostic for the C₄ photosynthetic pathway, since it reflects the reduced photorespiration that is a property of C₄ photosynthesis. Geographic variation for was examined within Flaveria linearis, a C₃–C₄ intermediate species. Collections from four widely separated Floridian populations were propagated in a greenhouse and measured for . Little differentiation among populations was found, but significant within-population variation was present. Temperature is a hypothesized selective agent for the C₄ photosynthetic pathway. To test this hypothesis, plants exhibiting a range of were cloned and placed in growth chambers at 25°C and 40°C. After 7 weeks, valves were remeasured and plants were harvested and weighed. There was a poor correlation between initial and final measures of for a given genotype (r=0.38, P>0.1). Broad sense heritability for was computed to be 0.10. At 25°C, there was no relationship between final size and . At 40°C, more C₄-like plants, as indicated by their low , had grown larger. Differences in relative growth rate were attributable more to differences in net assimilation rate than in leaf area ratio. Taken together, these results demonstrate that although significant plasticity exists in the amount of photorespiration in this C₃–C₄ species, high temperature appears to be an effective selective agent for the reduction of photorespiration and the enhancement of C₄-like traits.     

Cotton root and shoot response to localized supply of nitrate,phosphate and potassium: Split-pot studies with nutrient solution and vermiculitic soil

Vertical stratification of plant-available K in vermiculitic soil profiles contributes to a late-season K deficiency that limits cotton (Gossypium hirsutum L.) yields on affected soils. Split-root solution culture and split-pot soil experiments were conducted to determine whether root distribution and cultivar differences in root extension in these stratified profiles result from a compensatory response to localized enrichment with NO₃-N, PO₄-P, and/or K in the root zone. Compensatory root growth was greatest in response to localized NO₃-N enrichment. For two cultivars examined in solution culture, 74% of new root development occurred in the half-pot providing 90% of the total NO₃-N supply. Only 60% of cultivar root development occurred in the half-pot providing 90% of the PO₄-P. No compensatory root growth was observed in response to localized K enrichment. In the split-pot system, the proportion of total root surface area developing in a half-pot was highly correlated with localized soil NO₃-N levels (r²=0.81), while increased K availability in one half of the root zone did not affect root distribution. Mean soil NO₃-N supply to the whole root system determined shoot N accumulation (r²=0.97). Shoot K accumulation was not related to soil K availability but was strongly correlated with mean root surface area density (r²=0.86). Cultivar Acala GC510, known to be less sensitive to K deficiency than Acala SJ-2, had significantly larger root diameter in all nutrient-supply environments. Under conditions of K stress, Acala GC510 had increased root branching and allocated greater dry matter to roots relative to shoots than Acala SJ-2. The results demonstrate that K acquisition by cotton is strongly influenced by the quantity and distribution of NO₃-N in the root zone through its effects on root proliferation, and that distinct cultivar differences associated with crop performance on low K soils can be detected in short-term, solution culture growth systems.     

Die Bedeutung der “feedback”-Hemmung der Threonin-Desaminase für die Synthese von Valin und Leucin

Zusammenfassung In Arthrobacter Stamm 23 führte die durch Mutation verursachte allosterische Unempfindlichkeit der Threonin-Desaminase zur dereprimierten Bildung der Enzyme im Isoleucin-Valin-Leucin-Biosyntheseweg. Derepression erfolgte auch, wenn Wildtypzellen in Gegenwart von -Ketobuttersäure inkubiert wurden. In beiden Fällen wurde Isoleucin überproduziert und ins Kulturmedium ausgeschieden. Wie aus Wachstumsexperimenten hervorging, verursachte der Überschuß an -Ketobuttersäure im Medium primär einen Valin- und Leucin-Mangel, der zu einer vorübergehenden Wachstumshemmung führte. Durch die dereprimierte Bildung der Enzyme im Isoleucin-Valin-Biosyntheseweg konnte die Wachstumshemmung überwunden werden.Der vorübergehende Hemmeffekt der -Ketobuttersäure ließ sich auf eine Konkurrenz der Substrate am ersten gemeinsamen Enzym im Isoleucin-Valin-Biosyntheseweg, der Acetohydroxysäure-Synthase, zurückführen. Wegen des niedrigen K _m-Wertes für -Ketobuttersäure wird dieses Substrat vom Enzym bevorzugt umgesetzt. Durch gaschromatographische Bestimmungen der Acetoin- und Acetyläthylcarbinol-Bildung in Enzymtests mit variierten Substrat-Konzentrationen konnte nachgewiesen werden, daß relativ geringe Konzentrationen an -Ketobuttersäure genügen, um die -Acetolacetat-Bildung vollständig zu unterdrücken. Diese Ergebnisse erklären die durch -Ketobuttersäure verursachte vorübergehende Wachstumshemmung bei Bakterien.

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The effect of the feedback inhibition of threonine deaminase on valine-leucine biosynthesis

In Arthrobacter strain 23 the allosteric insensitivity of threonin deaminase caused by mutation resulted in derepressed formation of the enzymes of the isoleucine-valine-leucine pathway. Derepression was also observed, when wild type cells were incubated in the presence of -oxobutyrate. In both cases isoleucine was overproduced and excreted. As growth experiments indicated the excess of -oxobutyrate in the medium caused endogenous valine and leucine deficiency and a transient inhibition of growth. Derepressed formation of the isoleucinevaline biosynthetic enzymes resulted in relief of growth inhibition.The transient inhibitory effect of -oxobutyrate has been traced back to substrate competition at the first enzyme common to the isoleucine and valine pathway, acetohydroxy acid synthase. Due to the low K _m of the enzyme for -oxobutyrate this substrate is preferentially converted. As proven by gaschromatographical measurements of acetoin and acetylethyl carbinol produced in enzyme (acetohydroxy acid synthase) assays with varied substrate concentrations, relatively low concentrations of -oxobutyrate are able to suppress the formation of -acetolactate completely. These results explain the transient inhibitory effect of -oxobutyrate on the growth of bacteria.

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Abkürzungen -KBS -Ketobuttersäure - FAD Flavin-adenin-dinucleotid - AHS Acetohydroxysäure - IPM Isopropylmalat - TPP Thiaminpyrophosphat     

Dissociation of human alphaB-crystallin aggregates by thiocyanate is structurally and functionally reversible

Conformational modifications and changes in the aggregation state of human B-crystallin were investigated at different concentrations of SDS, KBr, urea, and NH₄SCN and at different temperatures. Intrinsic fluorescence measurements indicated complete and reversible unfolding of the protein at 2 M NH₄SCN, whereas the concentration of urea required for complete and irreversible unfolding was 6 M. Gel permeation chromatography indicated almost complete dissociation of the micelle-like aggregate of B-crystallin in 2 M NH₄SCN, but only partial dissociation into large-sized aggregates in 6 M urea. Thiocyanate-treated B-crystallin recovered its chaperone-like activity upon dilution of the dissociating agent, whereas the urea-treated protein did not.     

Integrins: cell adhesives and modulators of cell function

Summary Integrins encompass a family of cell-surface molecules which play a crucial role in cell-cell and cell-extracellular matrix interaction. Of these heterodimeric transmembrane glycoproteins (consisting of an and chain) as yet at least 20 different types have been described, all with a different pattern of reactivity with extracellular matrix components. In this review the cell and tissue distribution of the integrins is discussed, with special emphasis on immunohistochemical localization of the ₁ integrins and the ₆₄ integrin. The ₁ integrins comprise a subfamily in which eight chains combine with one (the ₁) chain. The ₂₁, ₃₁ and ₆₁ and the ₆₄ integrins are expressed on a wide variety of epithelia on the basolateral surface or exclusively on the basal surface facing the basement membrane (e.g. ₆₁ and ₆₄). Leucocyte integrins, which share a common ₂ chain, occur almost exclusively on white blood cells and their precursors. The vitronectin receptors, which share a common _v chain, occur in a wide variety of cell types. Integrins play a major role in the interaction of the cell with the extracellular matrix in order to create and maintain tissue architecture. It has become clear, however, that through integrin-ligand interaction cell function is also modulated. Furthermore, in pathological conditions integrins play a role of some significance. Integrins mediate leucocyte traffic in developing inflammatory processes and function in neoplastic growth when it comes to invasion and metastasis.     

The effect of some macronutrients on adventitious root development on scion apple cultivars in vitro

The influence of some macronutrients, especially NH₄NO₃ and KNO₃, on root development of microcuttings from 3 apple scion cultivars is discussed. A reduction of the level of NH₄NO₃ in the medium from full strength to 1/4 strength significantly increased the percentage rooting of Gala and Royal Gala, but not Jonagold. Further reduction of NH₄NO₃ level from 1/4 strength to zero significantly reduced the percentage of rooting in Gala but not Royal Gala. Jonagold rooted best at zero concentration NH₄NO₃. Without NH₄NO₃, rooting percentages were as high as 100% for all 3 cultivars when KNO₃ was provided at full strength. The results show that adventitious roots can be induced on apple scion cultivars by media manipulation.     

Influence of nitrogen form and NH4 +-N/:NO3 −-N ratios on adventitious shoot formation from pear (Pyrus communis) leaf explants in vitro

The effect of various basal salts media, containing different nitrogen levels on in vitro adventitious shoot regeneration from leaf explants of Louise Bonne Panachee and Seckel pear (Pyrus communis L.) were investigated. Among the different basal salt formulae tested, Nitsch (1969) gave significantly better regeneration in most of the experiments. Shoot regeneration was altered with different NH₄ ⁺-N/NO₃ ^–-N ratios. The best regeneration was obtained when NH₄ ⁺:NO₃ ^– was either 1:2 or 1:3 regardless of overall N concentration. In addition, these data show that NH₄ ⁺ was essential for adventitious shoot regeneration from pear leaf explants on White's (1943) medium.     

Uteroferrin contains complex and high mannose-type oligosaccharides when synthesized in vitro

Mature uteroferrin (Uf; M = 35,500) is a progesterone-induced acid phosphatase secreted by the pig uterus. It contains a single, unphosphorylated, high mannose-type oligosaccharide. Endometrial explants cultured in vitro secrete Uf with a M of 37,000 (37k Uf) having phosphorylated high mannose oligosaccharides. In this report we demonstrate that 37k Uf contains two N-linked oligosaccharides which are a mixture of complex and high mannose-type oligosaccharides. The complex-type glycopeptides are biantennary and a portion may be fucosylated on the GlcNac of the chitobiose core proximal to the peptide. Only a portion of the high mannose-type oligosaccharides are phosphorylated. The remainder appear to be typical Man_6-4GlcNac₂ oligosaccharides found on mature Uf.Abbreviations Uf Uteroferrin - ConA Concanavalin A - WGA Wheat Germ Agglutinin - endoH endo--N-acetylglucosaminidase H - SDS Sodium Dodecyl Sulfate - SDS-PAGE polyacrylamide gel electrophoresis in the presence of SDS     

Sequence- and Regio-Selectivity in the Montmorillonite-Catalyzed Synthesis of RNA

The six binary montmorillonite clay-catalyzed reactions of the5-phosphorimidazolides of adenosine, cytidine, guanosine anduridine were performed and the eight dimers from each reactionwere separated and analyzed by HPLC. A 16–51-fold higher yieldof the 5-purine-pyrimidine dimers over that of the5-pyrimidine-purines was observed. The total yield of the5-purine-pyrimidine dimers was in the 50–70% range while thatof the 5-pyrimidine-purine dimers was 1.3–7.0%. Less sequenceselectivity was observed in the homodimers formed.Regioselectivity for the formation of 3, 5-phosphodiesterbonds over that found in the absence of clay was observed. The5-purine-pyrimidine, 5-pyrimidine-pyrimidine and5-purine-purine dimers had 3, 5-links in about half of theirphosphodiester bonds. The percent phosphodiester links in the5-pyrimidine-pyrimidine dimers was 18%, a value close to thatobserved in the absence of the montmorillonite catalyst. Themontmorillonite-catalyzed reaction of all four activatednucleotides was performed and the 24 products were separated andanalyzed. The trends observed in the binary reactions wereconfirmed and the results also showed that the relativereactivity of the activated monomers was A>G>C>U in theratio 8.2: 4.8: 1.3: 1 respectively. No 5-pyrimidine-purineswith a 5-U and pG³pU, pC³pAand pC³pG weredetected. These studies suggest that a limited population ofRNAs would have formed in catalyzed prebiotic reactions.     

Variation in the natural abundance of 15N in the halophyte,Salicornia virginica,associated with groundwater subsidies of nitrogen in a southern California salt-marsh

To provide insight into the importance of the salt-marsh ecotone as a sink for inorganic nitrogen in perched groundwater, measurements were made of the natural abundance of ¹⁵N in dissolved NO₃-N and NH₄-N and in the salt-marsh halophyte, Salicornia virginica, along an environmental gradient from agricultural land into a salt-marsh. The increase in the natural abundance of ¹⁵N (expressed by convention as ¹⁵N) of NO₃-N, accompanied by the decrease in NO₃-N (and total dissolved inorganic N, DIN) concentration along the gradient, suggested that the salt-marsh ecotone is a site of transformation, most likely through denitrification, of inorganic nitrogen in groundwater. ¹⁵N enrichment in S. virginica (and the parasitic herb, Cuscuta salina), along the tidal marsh boundary, relative to high and middle marsh locations, indicated the retention of groundwater nitrogen as vegetative biomass. The correlation between ¹⁵N _Salicornia and ¹⁵N_NH4 suggested a preference for NH₄-N over NO₃-N during uptake by this plant. Groundwater inputs enhanced the standing crop, above-ground productivity, and nitrogen content of S. virginica but the ralative effects of pore water salinity and DIN concentration on these parameters were not determined. ¹⁵N enrichment of marsh plants by groundwater DIN inputs could prove useful in tracing the fate of these inputs in the marsh food web.     

The influence of ammonium nitrate supplementation on degradation and in vitro digestibility of straw colonized by higher fungi

Summary The digestion of straw by nine higher fungi and the influence of ammonium nitrate supplementation was investigated using loss of organic matter, degradation of lignin and in vitro digestibility as indices of digestion.The decomposition rates of organic matter were influenced differently by ammonium nitrate supplementation. The rates of decomposition by Pleurotus salmoneo stramineus and Pleurotus eryngii decreased, while those of Lentinus edodes and Pleurotus sp. Florida increased at low NH₄NO₃ concentrations, but decreased at higher concentrations. The decomposition rates of Agrocybe aegerita, Stropharia rugosoannulata, Kuehneromyces mutabilis, and Ganoderma applanatum were generally higher than those of the control at all NH₄NO₃ levels.The ability to degrade lignin varied greatly. Flammulina velutipes did not attack lignin at all while Agrocybe aegerita did only slightly. The highest lignin degradation rate was found with Pleurotus sp. Florida. The lignin decomposition rates of Lentinus edodes, Pleurotus eryngii and Pleurotus salmoneo stramineus were depressed at all NH₄NO₃ levels. No correlation between lignin degradation and nitrogen supplementation was found with Ganoderma applanatum and Pleurotus sp. Florida. Only Agrocybe aegerita could be stimulated with NH₄NO₃.The in vitro digestibility of the substrate with and without nitrogen supplementation was decreased with Agrocybe aegerita, Flammulina velutipes, and Ganoderma applanatum. All the other fungi enhanced the in vitro digestibility when no NH₄NO₃ was added to the substrate. At all NH₄NO₃ levels, the in vitro digestibility was lower than that of the unsupplemented control. At 1.25% NH₄NO₃ it fell below the fungus free control value.The results are explained in terms of altered relative decomposition rates for organic matter and lignin after nitrogen supplementation.     

Ambiguity and the evolution of the genetic code

The evolution of the genetic code is an extremely complex problem. The addition of a new method by which the code could evolve, however, allows much to be explained about the way in which the present codes (₃ and ₃ ) originated. The idea that ambiguity would allow the length of the codon to change is very useful, since it predicts the distribution of the 4-blocs and 2-blocs in the code, determines where variations in the code are probable, and presents a scenario for the evolution of the code.     

Molecular mapping of a new gene Rrs4 CI 11549 for resistance to barley scald (Rhynchosporium secalis)

Doubled haploid (DH) progeny from a cross between the scald susceptible barley (Hordeum vulgare L.) cultivar Ingrid and the resistant accession CI 11549 (Nigrinudum) was evaluated for resistance in the pathogen Rhynchosporium secalis (Oudem) J.J. Davis. Two linked and incompletely dominant loci confer resistance CI 11549 against isolate 4004. One is an allele at the complex Rrs1 locus on chromosome 3H close to the centromere; the other is located 22 cM distally on the long arm. The latter locus is designated Rrs4. In BC₃-lines into Ingrid from CI 2222 (another Nigrinudum) resistance seems governed by one locus close to the telomeric region of chromosome 7H, probably allelic to Rrs2. In neither case did we find any trace of the recessive gene rh8 reported to be present in Nigrinudum. Various resistance donors of Ethiopian origin designated as Nigrinudum, Jet or Abyssinian were identical to a great extent with respect to markers, but differed in resistance to different isolates of scald or in barley yellow dwarf virus (BYDV) resistance. The implications for their use as differentials in scald tests and screening of germplasm collections are discussed.     

Large scale preparation of PA-oligosaccharides from glycoproteins using an improved extraction method

We have developed a new method for the large scale preparation of pyridylaminated (PA-) oligosaccharides from glycoproteins. Phenol/chloroform extration was adapted for the removal of protein and excess 2-aminopyridine, improving the efficiency of preparation. From a 2.5 g sample of human apo-transferrin, 25–30 mol of agalacto biantennary PA-oligosaccharide could be obtained. By increasing the concentration of PA-oligosaccharide substrate, we were able to detect a very low level ofN-acetylglucosaminlytransferase IV activity in CHO cell extracts.Abbreviations PA 2-aminopyridine - SDS sodium dodecyl sulfate - GlcNAc N-acetylglucosamine - GnT N-acetylglucosaminyltransferase - Gn,Gn-bi-PA GlcNAc1-2Man1-3(GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc-2-aminopyridine - Gn,Gn,Gn-tri-PA GlcNAc1-2(GlcNAc1-4)Man1-3(GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc-2-aminopyridine - Gn,Gn,Gn-trí-PA GlcNAc1-2Man1-3({GlcNAc1-2(GlcNAc1-6)Man1-6})Man1-4GlcNac1-4GlcNAc-2-aminopyridine - Gn,(Gn),Gn-bi-PA GlcNAc1-2Man1-3(GlcNAc1-4)(GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc-2-aminopyridine     

High frequency of triplicated α-globin loci and absence or low frequency of α thalassemia in Polynesian Samoans

Summary Most of the population in certain areas of Melanesia have one -globin gene deletion ( thal₂). It is thought that the high frequencies of thal₂ in this population is due to a selective advantage given by malaria infection to carriers of thal₂. We are interested in neighboring Polynesia which, although adjacent to Melanesia, has always been free of malaria due to the absence of the vector anopheles. We studied 60 Polynesian Samoans and 150 Malaysians by restriction endonuclease gene mapping using Eco RI, Bam HI, and Bgl II and hybridization to ³²P-labeled -globin gene probe. Seven among the 60 (11.7%) Samoans had triplicated -globin loci type 1, while none had thal₂. On digestion with Bgl II the third -globin gene was found in an additional 3.7kb fragment in all seven Samoans with triplicated -globin loci, while digestion with Bam HI produced an abnormal elongated 18.2 kb fragment carrying -globin genes in addition to the normal 14.5 kb fragment. None of the Polynesian Samoans had thal₂ or thal₁. Only two of the Malaysians had triplicated -globin loci.     

Evidence for a light-dependent system for reassimilation of photorespiratory CO2, which does not include a C4 cycle,in the C3−C4 intermediate species Moricandia arvensis

Three methods of estimating photorespiratory rate in leaves of the C₃–C₄ intermediate species Moricandia arvensis and the related C₃ species Moricandia moricandioides were compared. The results indicated that the photorespiratory rate in M. arvensis is less than in M. moricandioides, and that this is caused partly by reduced carbon flux through the photorespiratory pathway, and partly by the presence of a mechanism for enhanced photorespiratory CO₂ reassimilation in the intermediate species. Measurements of the CO₂ compensation point () in the two species supported this conclusion. A functional C₄ pathway is unlikely to be involved in the reduction of photorespiratory rate in M. arvensis since pulse-chase experiments showed that carbon did not move from C₄ acids to the reductive pentose-phosphate pathway in attached leaves under steady-state conditions at .Abbreviations and symbols APR apparent photosynthetic rate - C_i, C_e intercellular, external CO₂ concentration - CO₂ compensation point - PAR photosynthetically active radiation - PFD photon flux density     

The relation of proton motive force,adenylate energy charge and phosphorylation potential to the specific growth rate and efficiency of energy transduction inBacillus licheniformis under aerobic growth conditions

The magnitude of the proton motive force (p) and its constituents, the electrical () and chemical potential (-ZpH), were established for chemostat cultures of a protease-producing, relaxed (rel ^–) variant and a not protease-producing, stringent (rel ⁺) variant of an industrial strain ofBacillus licheniformis (respectively referred to as the A- and the B-type). For both types, an inverse relation of p with the specific growth rate was found. The calculated intracellular pH (pH_in) was not constant but inversely related to . This change in pH_in might be related to regulatory functions of metabolism but a regulatory role for pH_in itself could not be envisaged. Measurement of the adenylate energy charge (EC) showed a direct relation with for glucose-limited chemostat cultures; in nitrogen-limited chemostat cultures, the EC showed an approximately constant value at low and an increased value at higher . For both limitations, the ATP/ADP ratio was directly related to .The phosphorylation potential (G'p) was invariant with . From the values for G'p and p, a variable H⁺/ATP-stoichiometry was inferred: H⁺/ATP=1.83+0.52µ, so that at a given H⁺/O-ratio of four (4), the apparent P/O-ratio (inferred from regression analysis) showed a decline of 2.16 to 1.87 for =0 to _max (we discuss how more than half of this decline will be independent of any change in internal cell-volume). We propose that the constancy of G'p and the decrease in the efficiency of energy-conservation (P/O-value) with increasing are a way in which the cells try to cope with an apparent less than perfect coordination between anabolism and catabolism to keep up the highest possible with a minimum loss of growth-efficiency. Protease production in nitrogen-limited cultures as compared to glucose-limited cultures, and the difference between the A- and B-type, could not be explained by a different energy-status of the cells.Abbreviations CCCP carbonylcyanide-p-trichloromethoxyphenylhydrazone - DW dry weight of biomass - F Faraday's constant, 96.6 J/(mV × mol) - Fo chemostat outflow-rate (ml/h) - FCCP carbonylcyanide-p-trifluoromethoxyphenylhydrazone - G'p phosphorylation potential, the Gibbs energy change for ATP-synthesis from ADP and P_i - G'⁰p standard Gibbs energy change at specified conditions - H⁺/ATP number of protons translocated through - ATP synthase in synthesis of one ATP - H⁺/O protons translocated during transfer of 2 electrons from substrate to oxygen - specific growth rate (1/h) - _H+ transmembrane electrochemical proton potential, J/mol - M_b molar weight (147.6 g/mol) of bacteria with general cell formula C_6.0H_10.8O_3.0N_1.2 - pH_out,in extracellular, intracellular pH - P_i (intracellular) inorganic phosphate - p proton motive force, mV - pH transmembrane pH-difference - transmembrane electrical potential, mV - P/O number of ADP phosphorylated to ATP upon reduction of one O^2– to H₂O by two electrons transferred through the electron transfer chain - P/O (H⁺/O) × (H⁺/ATP)^–1 - P/O_F, P/O_N P/O with the two electrons donated by resp. (NADH + H⁺) and FADH - q specific rate of consumption or production (mol/g DW × h) - rel ⁺,rel ^– stringent, relaxed genotype - R universal gas constant, 8.36 J/(mol × degree) - T absolute temperature - TPMP⁺ triphenylmethylphosphonium ion - TPP⁺ tetraphenyl phosphonium ion - Y growth yield, g DW/mol - Z conversion constant=61.8 mV for 310 K (37 °C) - ZpH transmembrane proton potential or chemical potential, mV