Energetics of the growth of Methanobacterium thermoautotrophicum and Methanococcus thermolithotrophicus on ammonium chloride and dinitrogen

Methanobacterium thermoautotrophicum was grown in continuous culture in a fermenter gassed with H₂ and CO₂ as sole carbon and energy sources, and in a medium which contained either NH₄Cl or gaseous N₂ as nitrogen source. Growth was possible with N₂. Steady states were obtained at various gas flow rates with NH₄Cl and with and the maintenance coefficient varied with the gas input and with the nitrogen source. Growth of Methanococcus thermolithotrophicus in continuous culture in a fermenter gassed with H₂, CO₂ as nitrogen, carbon and energy sources was also examined.Abbreviations molecular growth yield (g dry weight of cells per mol of CH₄ evolved) - growth rate (h^-1) - D dilution rate (h^-1) - rate (h_-1); relation of Neijssel and Tempest and of Stouthamer and Bettenhaussen - energy     

Energetics of the budding cycle of Saccharomyces cerevisiae during glucose limited aerobic growth

Summary A method for the estimation of the yield on energy (Y _ATP) and of the efficiency of oxidative phosphorylation, in vivo (P/O ratio) is described, which is based on the measurement of effective gas exchange values ( and ) and of the yield coefficient Y of continuously growing populations of baker's yeast which vary in the degree of fermentation and respiration. For Y _ATP a value of 12.0±0.5 and for P/O ratio one of 1.1±0.05 was found and seems to be independent of the type of glucose catabolism (under glucose limitation).The gas exchange of populations of Saccharomyces cerevisiae synchronized at different growth rates was determined. The specific oxygen uptake and carbon dioxide formation rate, Q _{O 2}, and Q _{CO 2}, are shown to depend on the state of the cells in the budding cycle. Increase in gas metabolism and therefore increased energy generation coincides with the initiation of budding. The longer the generation time g the more expressed are these oscillations of energy formation over the budding cycle. The relationship between the course of energy generation and energy storage and the sequence of budding and single cell phase over the division cycle is discussed.     

Severe hypoxia decreases oxygen uptake relative to intensity during submaximal graded exercise

The effect of severe acute hypoxia (fractional concentration of inspired oxygen equalled 0.104) was studied in nine male subjects performing an incremental exercise test. For power outputs over 125 W, all the subjects in a state of hypoxia showed a decrease in oxygen consumption ( O₂) relative to exercise intensity compared with normoxia (P < 0.05). This would suggest an increased anaerobic metabolism as an energy source during hypoxic exercise. During submaximal exercise, for a given O₂, higher blood lactate concentrations were found in hypoxia than in normoxia (P < 0.05). In consequence, the onset of blood lactate accumulation (OBLA) was shifted to a lower O₂ ( O₂ 1.77 l·min^–1 in hypoxia vs 3.10 l·min^–1 in normoxia). Lactate concentration increases relative to minute ventilation ( _E) responses were significantly higher during hypoxia than in normoxia (P < 0.05). At OBLA, _E during hypoxia was 25% lower than in the normoxic test. This study would suggest that in hypoxia subjects are able to use an increased anaerobic metabolism to maintain exercise performance.     

\vec H^ + /2\bar e Stoichiometry of the NADH:Ubiquinone Reductase Reaction Catalyzed by Submitochondrial Particles

Mitochondrial NADH:ubiquinone-reductase (Complex I) catalyzes proton translocation into inside-out submitochondrial particles. Here we describe a method for determining the stoichiometric ratio (n) for the coupled reaction of NADH oxidation by the quinone acceptors. Comparison of the initial rates of NADH oxidation and alkalinization of the surrounding medium after addition of small amounts of NADH to coupled particles in the presence of Q₁ gives the value of n = 4. Thermally induced deactivation of Complex I [1,2] results in complete inhibition of the NADH oxidase reaction but only partial inhibition of the NADH:Q₁-reductase reaction. N-Ethylmaleimide (NEM) prevents reactivation and thus completely blocks the thermally deactivated enzyme. The residual NADH:Q₁-reductase activity of the deactivated, NEM-treated enzyme is shown to be coupled with the transmembraneous proton translocation (n = 4). Thus, thermally induced deactivation of Complex I as well as specific inhibitors of the endogenous ubiquinone reduction (rotenone, piericidin A) do not inhibit the proton translocating activity of the enzyme.     

Ventilation and control of acid-base status during temperature acclimation in the crab,Cancer magister

Summary Frequencies of scaphognathite (ventilatory,f _sc) and heart (f _h) pumping, oxygen consumption ( ), and hemolymph oxygen, carbon dioxide and pH levels were measured in adult Dungeness crabs (Cancer magister) during 7–10 day periods of exposure to 7, 12, and 17°C seawater. Ventilation volume ( ) was calculated for individual animals fromf _sc and a previously determined relationship between stroke volume and animal mass. increases (Q₁₀=2.3) with temperature were associated with larger increases inf _sc (Q₁₀=3.3) and (Q₁₀=3.5) and smaller increases inf _h (Q₁₀=1.5). The incidence of unilateral scaphognathite pumping and pausing decreased as temperature rose.Postbranchial oxygen tension was maintained in vivo but hemolymph oxygen content decreased both in vivo and in vitro as temperature rose. Postbranchial carbon dioxide tension did not change significantly but relative alkalinity was maintained as temperature rose by loss of hemolymph bicarbonate. The effects of increased ventilation volume and potential mechanisms of bicarbonate regulation are discussed.The responses of the essentially subtidalCancer magister are compared with those of subtidal, intertidal and terrestrial crabs demonstrating that the concepts of acid-base regulation developed for water and air breathing vertebrates are also applicable to water and air breathing crabs, and that intertidal crabs may exhibit transitional states.This work was supported by Grant No. A.5762 National Research Council of Canada     

A new technique for continuous measurement of the heat of fermentation

Summary A special temperature control system has been developed and applied to continuous measuring of the heat evolved during a fermentation process. In this system, the fermentation broth was overcooled by a given constant cooling water flow. The excess heat removed from the fermentor was then made up by an immersion electrical heater. The action of the temperature controller was precisely monitored as it varied in response to the amount of heat produced by the microbial activities.The technique was used for determining the heat evolution byEscherichia coli grown on glucose. The ratio between quantities of total heat release and total oxygen consumption has been determined to be 0.556 MJ/mol O₂.The newly developed technique can be employed as an online sensor to monitor the microbial activities of either aerobic or anaerobic fermentation systems.Symbols C_c Heat capacity of cooling water (MJ/kg · °C) - C_p Heat capacity (MJ/kg · °C) - I Current of immersion heater (A) - K Constant in Equation (2) (h) - K Constant in Equation (13) (m³ · h · °C/MJ) - Q_c Flow rate of cooling water (m³/h) - Heat of agitation (MJ/m³ · h) - Heat dissipated by the bubbling gas (MJ/m³ · h) - Heat removal by the action of controller (MJ/m³ · h) - Heat of fermentation (MJ/m³ · h) - Heat loss to the surroundings (MJ/m³ · h) - Q_pass Constant average power dissipated by the immersion heater (MJ/m³ · h) - Fluctuating power dissipated by the immersion heater (MJ/m³ · h) - Power dissipated by the immersion heater (MJ/m³ · h) - T Temperature of fermentation broth (°C) - Constant average temperature of fermentation broth (°C) - Fluctuating temperature of fermentation broth (°C) - T_a Temperature of the ambient air (°C) - T_c Inlet temperature of cooling water (°C) - U₁A₁ Specific heat transfer coefficient for determination of heat loss to the surroundings (MJ/m³ · h · °C) - U₂A₂ Specific heat transfer coefficient for cooling surfaces (MJ/m³ · h · °C) - U₃A₃ Constant in Equation (16) (MJ/m³ · h · °C) - V Voltage of immersion heater (V) - V_L Liquid volume (m³) - OUR Oxygen uptake rate (mol O₂/m³ · h) Greek Letters H_fo The ratio between the total heat release and the total oxygen uptake (MJ/mol O₂) - _c Density of cooling water (kg/m³) - Time constant defined in Equation (6) (h) - _iM_iC_pi Heat capacity of system components (fermentation broth + fermentor jar + stainless steel) (MJ/m³ · °C)     

Seasonal changes in the activation of crossbridge motions of isolated thick filament from Limulus striated muscle

Summary In dynamic light scattering, measurements of the intensity-intensity time correlation function from a suspension of rod-like particles of length L could reveal dynamical information related to translational and internal motions of those particles. For a suspension of thick filaments isolated from the myosin-regulated, striated muscles of Limulus at KL>1 (where K is the scattering vector), the average characteristic linewidth ( ) increased with the addition of Ca²⁺ or with the depletion of ATP. The increase in the with the addition of Ca²⁺ could be due to the presence of energy-requiring, high-frequency motions of the crossbridges activated by Ca²⁺. The increase in which occurred with the depletion of ATP was assumed to be mainly due to the thermal motions of the crossbridges after they had moved radially away from the filament backbone. The percentage increase in following the addition of Ca²⁺ was found to be seasonal, i.e., values of obtained from thick filaments isolated between the middle of June and the middle of September were smaller than those obtained during the rest of the year. The effect of temperature on the percentage increase in was also different. The increase showed a maximum at about 35°C during the summer and at about 25°C at other times. However, the percentage increase in developed under ATP-depleted conditions showed no temperature-related maximum. The number of bound Ca²⁺ per myosin molecule was 1 during the summer and 2 at other times.Abbreviations DLS dynamic light scattering - L length - K scattering vector - SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis - average characteristic line width Deceased     

Energy expenditure and cardiorespiratory responses at the transition between walking and running

We investigated whether the spontaneous transition between walking and running during moving with increasing speed corresponds to the speed at which walking becomes less economical than running. Seven active male subjects [mean age, 23.7 (SEM 0.7) years, mean maximal oxygen uptake ( ), 57.5 (SEM 3.3) ml·kg ^–1·min ^–1, mean ventilatory threshold (VTh), 37.5 (SEM 3) ml·kg ^–1 ·min ^–1] participated in this study. Each subject performed four exercise tests separated by 1-week intervals: test 1, and VTh were determined; test 2, the speed at which the transition between walking and running spontaneously occurs (ST) during increasing speed (increases of 0.5 km·h ^–1 every 4 min from 5 km·h ^–1) was determined; test 3, the subjects were constrained to walk for 4 min at ST, at ST ± 0.5 km·h ^–1 and at ST ± 1 km·h ^–1; and test 4, the subjects were constrained to run for 4 min at ST, at ST±0.5 km·-h ^–1 and at ST±1 km·h ^–1. During exercise, oxygen uptake ( ), heart rate (HR), ventilation ( ), ventilatory equivalents for oxygen and carbon dioxide (% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmOvayaaca% WaaSbaaSqaaiaabweaaeqaaOGaai4laiqadAfagaGaamaaBaaaleaa% caqGYaaabeaakiaacYcacaqGGaGaaeiiaiqadAfagaGaamaaBaaale% aacaqGfbaabeaakiaac+caceWGwbGbaiaacaqGdbGaae4tamaaBaaa% leaacaaIYaaabeaaaaa!4240!\[\dot V_{\text{E}} /\dot V_{\text{2}} ,{\text{ }}\dot V_{\text{E}} /\dot V{\text{CO}}_2 \]), respiratory exchange ratio (R), stride length (SL), and stride frequency (SF) were measured. The results showed that: ST occurred at 2.16 (SEM 0.04) m·s ^–1; , HR and speed at ST were significantly lower than the values measured at VTh (P< 0.001, P< 0.001 and P< 0.05, respectively); changed significantly with speed (P< 0.001) but was greater during running than walking below ST (ST minus 1 km·h ^–1, P< 0.001; ST minus 0.5 km·h ^–1, P< 0.05) with the converse above ST (ST.plus 1 km·h ^–1, P<0.05), whereas at ST the values of were very close [23.9 (SEM 1.1) vs 23.7 (SEM 0.8) ml·kg ^–1 · min ^–1 not significant, respectively, for walking and running]; SL was significantly greater during walking than running (P<0.001) and SF lower (P<0.001); and HR and were significantly greater during running than walking below ST (ST minus 1 km·h ^–1, P<0.01; ST minus 0.5 km·h ^–1, P{<0.05) with the converse above ST (ST plus 1 km·h ^–1, P·< 0.05), whereas no difference appeared for and R between the two types of locomotion. We concluded from this study that ST corresponded to the speed at which the energy expenditure of running became lower than the energy expenditure of walking but that the mechanism of the link needed further investigation.     

Über Romanowsky-Farbstoffe und den Romanowsky-Giemsa-Effekt

Zusammenfassung Es wurden analysenreine Proben der Romanowsky-Farbstoffe Eosin Y, Erythrosin B und Tetrachlorfluoreszein hergestellt.Im DC der Farbstoffproben konnten keine Verunreinigungen nachgewiesen werden. Die Absorptionsspektren der Farbstoffdianionen in wäßriger alkalischer Lösung und der Farbstoffsäuren in 95%igem Ethanol wurden bei sehr kleinen Farbstoffkonzentrationen gemessen und der molare Extinktionskoeffizient der längstwelligen Absorptionsbande der monomeren Farbstoffspezies bestimmt (Tabelle 1). Die Extinktionskoeffizienten können zur Standardisierung von Farbstoffproben verwendet werden. Die Absorptionsspektren von Eosin Y hängen in wäßriger Lösung von der Farbstoffkonzentration ab. Aus der Konzentrationsabhängigkeit wurden mit einem neuen, sehr empfindlichen Verfahren zwei Assoziationsgleichgewichte ermittelt. Bereits in sehr verdünnter Lösung bilden sich Dimere, bei erhöhter Konzentration Tetramere, Die Dissoziationskonstante der DimerenD in MonomereM beträgt bei pH=12, 293K:K ₂₁=2,9 × 10^–5 M; der TetramerenQ in DimereD:K ₄₂=2,4 × 10^–3 M. Aus den gemessenen Spektren von Eosinlösungen verschiedener Konzentration, pH=12, und den GleichgewichtskonstantenK ₂₁,K ₄₂ haben wir die Spektren der reinen Monomeren, Dimeren und Tetrameren bestimmt.M hat eine langwellige Absorptionsbande: , _M =1,03 x 10₅ M_-1 cm_-1;D eine Bande: , _D =1,74 x 10₅ M_-1 cm_-1;Q zwei Banden: , , _Q1=1,65 x 10⁵, _Q2=1,96 x 10⁵ M^-1 cm^-1. Das Absorptionsspektrum der Dimeren wird quantenmechanisch interpretiert.

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Romanowsky dyes and Romanowsky-Giemsa effect. 2. Eosin Y, Erythrosin B, tetrachlorofluorescein, Spectroscopic characterization of pure dyes, association of Eosin Y

Summary Analytically pure smaples of the Romanowsky dyes eosin y, erythrosin b and tetrachlorofluorescein are prepared. DC of the dye samples shows no contaminations. We measured the absorption spectra of the dye dianions in alkaline aqueous solution and of the dye acids in 95% ethanol at very low dye concentrations. The molar extinction coefficients of the long wavelength absorption of the monomeric dye species are determined (Table 1). The extinction coefficients may be used for standardisation of dye samples. The absorption spectra of eosin y in aqueous solution are dependend on concentration. Using a new very sensitive method it was possible to identify two association equilibria from the concentration dependency of the spectra. Dimers are formed even in very dilute solutions, at higher concentrations tetramers. The dissociation constant of the dimersD in monomersM at 293 K, pH=12, isK ₂₁=2,9×10^–5 M; of the tetramersQ in dimersDK ₄₂=2,4×10^–3 M. From the experimental spectra of eosin solutions at various concentrations, pH=12, and the equilibrium constantsK ₂₁,K ₄₂ the absorption spectra of the pure monomers, dimers and tetramers are calculated. M has one long wavelength absorption band, , _M =1,03 x 10₅ M_-1 cm_-1;D also one absorption band, , _D =1,74 x 10₅ M_-1 cm_-1;Q two absorption bands, , , _Q1=1,65 x 10⁵, _Q2=1,96 x 10⁵ M^-1 cm^-1. The absorption spectrum of the dimers is discussed by quantum mechanics.

     

Transport of H+, K+, Na+ and Ca++ in Streptococcus

Summary The streptococci differ from other bacteria in that cation translocations (with the possible exception of one of the K⁺ uptake systems) occur by primary transport systems, i.e., by cation pumps which use directly the free energy released during hydrolysis of chemical bonds to power transport. Transport systems in other bacteria, especially for Na⁺ and Ca⁺⁺, are often secondary, using the free energy of another ion gradient to drive cation transport. In streptococci H⁺ efflux occurs via the F₁F₀-ATPase. This enzyme is composed of eight distinct subunits. Three of the subunits are embedded in the membrane and form a H⁺ channel; this is called the F₀ portion of the enzyme. The other five subunits form the catalytic part of the enzyme, called F₁, which faces the cytoplasm and can easily be stripped from the membrane. Physiologically, this enzyme functions as a H⁺-ATPase, pumping protons out of the cell to form an electrochemical proton gradient, . The F₁F₀-ATPase, however, is fully reversible and if supplied with P_i, ADP and a + of sufficient magnitude (ca –200 mv) catalyzes the synthesis of ATP. Streptococcus faecalis can accumulate K⁺ and establish a gradient of 50 000:1 (in>out) under some conditions. Uptake occurs by two transport systems. The dominant, constitutive system requires both an electrochemical proton gradient and ATP to operate. The minor, inducible K⁺ transport system, which has many similarities to the K⁺-ATPase of the Kdp transport system found in Escherichia coli, requires only ATP to power K⁺ uptake.Sodium extrusion occurs by a Na⁺/H⁺-ATPase. Exchange is electroneutral and there is no requirement for a . The possibility that the Na⁺/H⁺-ATPase may consist of two parts, a catalytic subunit and a Na⁺/H⁺ antiport subunit, is suggested by the finding that damage to the Na⁺ transport system either through mutation or protease action leads to the appearance of -requiring Na⁺/H⁺ antiporter activity.Ca⁺⁺ like Na⁺ is extruded from metabolizing, intact cells. Transport requires no but does require ATP. Reconstitution of Ca⁺⁺ transport activity with accompanying Ca⁺⁺-stimulated ATPase activity into proteoliposomes suggests that Ca⁺⁺ is transported by a Ca⁺⁺-translocating ATPase.Where respiring organelles and bacteria use secondary transport systems the streptococci have developed cation pumps. The streptococci, which are predominantly glycolyzing bacteria, generate a much inferior to that of respiring organisms and organelles. The cation pumps may have developed simply in response to an inadequate .Abbreviations electrochemical potential of protons - membrane potential - pH pH gradient - p proton-motive force - DCCD N,Na¹-dicyclohexlcarbodiimide - TCS tetrachlorosalicylanilide - FCCP carbonylcyanide-p-trifluoromethylphenylhydrazone - CCCP carbonylcyanie-m-chlorophenylhydrazone - TPMP⁺ triphenylmethyl phosphonium ion - DDA⁺ dibenzyldimethylammonium ion - Hepes 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid - EGTA ethyleneglycol-bis (amino-ethyl-ether)-N,N-tetraacetic acid     

The effect of ambient temperature on the relationship between ventilation and metabolism in a small parrot (Agapornis roseicollis)

Summary Values for basal metabolism, standard tidal volume (V _T), standard minute volume ( ), and mean extraction efficiency (EO₂) in the thermal neutral zone (TNZ) inAgapornis roseicollis (1.84 ml·min^–1; 0.95 ml·br^–1, STPD; and 33.3 ml·min^–1, STPD; and 22.5%; respectively) were all very similar to values for these parameters previously measured inBolborhynchus lineola, a similarly sized, closely related species from a distinctly different habitat.Having both a lower critical temperature (T_lc) below and an upper critical temperature (T_uc) above those ofB. lineola, the TNZ ofA. roseicollis extended from 25° to at least 35°C. The thermal conductance below the TNZ ofA. roseicollis was 14% less than that ofB. lineola. Therefore, at 5°C the standard metabolic rate (SMR) of the former is 17% less than that of the latter, and at 35°C it is 20% less. At 5°CA. roseicollis has a lower EO₂ and at 35°C a higher EO₂ than that ofB. lineola. The patterns of resting energy metabolism and of ventilation ofA. roseicollis and ofB. lineola are consistent with the former species being better suited to living in a more variable thermal environment than the latter.MeanV _T has a weak positive correlation with the rate of oxygen consumption ( ) at a constant ambient temperature (T _a) but a much stronger correlation when resting increases in response to a decrease inT _a.V _t is the only ventilatory parameter which is linearly correlated toT _a from 35° to –25°C. The data suggest thatT _a may have a regulatory effect onV _T somewhat independent of or .     

Evidence against H+−HCO 3 − symport as the mechanism for HCO 3 − transport in the cyanobacteriumAnabaena variabilis

Summary The rate of inorganic carbon uptake and its steadystate accumulation ratio (intracellular/extracellular concentration) was determined in the cyanobacteriumAnabaena variabilis as a function of extracellular pH. The free energy of protons ( ) across the plasmalemma was calculated from determinations of membrane potential, and intracellular pH, as a function of the extracellular pH. While inward proton motive force decreased with increasing extracellular pH from 6.5 to 9.5, rate of HCO ₃ ^– influx and its accumulation ration increased. The latter is several times larger than would be expected should HCO ₃ ^– influx be driven by . It is concluded that HCO ₃ ^– transport in cyanobacteria is not driven by the proton motive force.     

Mathematical modeling of mixing in a horizontal rotating tubular bioreactor: “Simple flow” model

The construction of the horizontal rotating tubular bioreactor (HRTB) represents a combination of a thin-layer bioreactor and a biodisc reactor. The bioreactor was made of a plastic tube whose interior was divided by the O-ring shaped partition walls. For the investigation of mixing properties in HRTB the temperature step method was applied. The temperature change in the bioreactor as a response to a temperature step in the inlet flow was monitored by six Pt-100 sensors (t ₉₀ response time 0.08 s and resolution 0.002 °C) which were connected with an interface unit and personal computer. Mixing properties of the bioreactor were modeled using the modified tank in series concept which divided the bioreactor into ideally mixed compartments. A mathematical mixing model with simple flow was developed according to the physical model of the compartments network and corresponding heat balances. Numerical integration of an established set of differential equations was done by the Runge-Kutt-Fehlberg method. The final mathematical model with simple flow contained four adjustable parameters (N1,Ni, F _cr andF _p ) and five fixed parameters.List of Symbols A _u m² inner surface of bioreactor's wall - A _ui m² i-th part of inner surface of bioreactor's wall - A _v m² outlet surface of bioreactor's wall - A _vi m² i-th part of outlet surface of bioreactor's wall - C _p kJ kg^–1 K^–1 heat capacity of liquid - C _pr kJ kg^–1 K^–1 heat capacity of bioreactor's wall - D h^–1 dilution rate - E °C °C^–1 h^–1 error of mathematical model - F _cr dm³s^–1 circulation flow in the model - F _p dm³ s^–1 back flow in the model - F _t dm³s^–1 inlet flow in the bioreactor - I °C intensity of temperature step, the difference in temperature between the temperature of the inlet liquid flow and the temperature of liquid in the bioreactor before the temperature step - K1 Wm^–2K^–1 heat transfer coefficient between the liquid and bioreactor's wall - K2 Wm^–2K^–1 heat transfer coefficient between the bioreactor's wall and air - m _s kg mass of bioreactor's wall - L m length of bioreactor - L _k m wetted perimeter of bioreactor - n min^–1 rotational speed of bioreactor - n _s number of temperature sensors - N1 number of cascades - Ni number of compartments inside the cascade - Nu Nusselt number - Pr Prandtl number - r _u m inner diameter of bioreactor - r _v m outside diameter of bioreactor - Re Reynolds number - s(t) step function - t s time - T °C temperature - T _c °C calculated temperature - T _m °C measured temperature - T _N1,Ni °C temperature of liquid in a defined compartment inside cascade - T _N1,S °C temperature of defined part of bioreactor's wall - T _S °C temperature of bioreactor's wall - T _v °C temperature of liquid in bioreactor - T _z °C temperature of surrounding air - V _t dm³ volume of liquid in the bioreactor Greek Symbols kJm^–1s^–1 K^–1 thermal conductivity of liquid in the bioreactor - kgm^–3 density of liquid in the bioreactor - m²s^–1 kinematic viscosity of liquid in the bioreactor Matrix Coefficient B - C - D - E B+C+D - G1 - G2 - G3 - A _ui - A _vi - Q ₁ - Q ₂ - Q ₃      

Toward a gibbsian approach to the problems of growth and cancer

Summary Certain sections ofJosiah Willard Gibbs's thermodynamics papers might be applicable to biological equilibrium and growth, normal or abnormal.Gibbs added terms _i dm _i to the differential of the internal energy d=td–pd, (t=temperature,p=pressure,=entropy,=volume) where is the potential of substancem _i , to provide for chemical as well as thermal and mechanical equilibrium. In this article a further generalization is suggested, to include biological equilibrium by adding to de terms of the form GdN, the variableN being the number of cells, where is a growth potential that measures exactly the resistance toward spontaneous growth. The functionG, like _i is intensive in nature (i.e. depends on intensive variables only) except for a conversion factor ,M=m _i , affording possible insight into why incipient abnormal growth is often independent of the number of cells. Useful applications might follow from identities between , or and or respectively. The following new function is studied, , a natural generalization of theGibbs free energy function , the possibility of measuring it electrically, and comparison of its role with that of for the possible experimental determination ofG. Gibbs's necessary and sufficient conditions for heterogeneous equilibrium ofn components inm phases are generalized and also modified to include broader restraining conditions like ,j=1,f,n, the > being characteristic of only living cellular phases. Careful appraisal of the term biological stability is followed by new criteria for stability, instability, and limits of stability, (neutral equilibrium) in terms of derivatives ofG, with possible medical applications. Three different sections of Gibbs's works tend to indicate that, for a biological phase, lower pressure usually increases its stability. The equation , where =surface tension,p, p = pressures,r, r=radii of curvature, is applied to possible control of tissue growth at interfaces. Methods of altering the equilibrum between three phasesA, B, C by varying the interfacial tensions _AB , _BC , _AC , using relations like _AB < _AC + _BC for stability of theA, B interface, suggest different means for shifting biological equilibrium between normal and abnormal cells through the introduction of new third phases at the interface. Various devices are mentioned for possible control of growth through proper channeling of surface or other equivalent forms of energy.     

Volume estimation of biological objects by systematic sections

The absolute volume of biological objects is often estimated stereologically from an exhaustive set of systematic sections. The usual volume estimator is the sum of the section contents times the distance between sections. For systematic sectioning with a random start, it has been recently shown that is unbiased when m, the ratio between projected object length and section distance, is an integer number (Cruz-Orive 1985). As this quantity is no integer in the real world, we have explored the properties of in the general and realistic situation m . The unbiasedness of under appropriate sampling conditions is demonstrated for the arbitrary compact set in 3 dimensions by a rigorous proof. Exploration of further properties of for the general triaxial ellipsoid leads to a new class of non-elementary real functions with common formal structure which we denote as np-functions. The relative mean square error (CE ²) of in ellipsoids is an oscillating differentiable np-function, which reduces to the known result CE ²= 1/(5m ⁴) for integer m. As a biological example the absolute volumes of 10 left cardiac ventricles and their internal cavities were estimated from systematic sections. Monte Carlo simulation of replicated systematic sectioning is shown to be improved by using m instead of m . In agreement with the geometric model of ellipsoids with some added shape irregularities, mean empirical CE was proportional to m ^–1.36 and m^–1.73 in the cardiac ventricle and its cavity. The considerable variance reduction by systematic sectioning is shown to be a geometric realization of the principle of antithetic variates.     

Bioenergetics: the evolution of molecular mechanisms and the development of bioenergetic concepts

Possible routes for the evolution of cell energetics are considered. It is assumed that u.v. light was the primary energy source for the precursors of the primordial living cell and that primitive energetics might have been based on the use of the adenine moiety of ADP as the u.v. chromophore. It is proposed that the excitation of the adenine residue facilitated phosphorylation of its amino group with subsequent transfer of a phosphoryl group to the terminal phosphate of ADP to form ATP. ATP-driven carbohydrate synthesis is considered as a mechanism for storing u.v.-derived energy, which was then used in the dark. Glycolysis presumably produced compounds like ethanol and CO₂ which easily penetrate the membrane and therefore were lost by the cell. Later lactate-producing glycolysis appeared, the end product being non-penetrant and, hence, retained inside the cell to be utilized to regenerate carboxydrates when light energy became available. Production of lactate was accompanied by accumulation of equimolar H⁺. To avoid acidification of the cell interior, an F₀-type H⁺ channel was employed. Later it was supplemented with F₁. This allowed the ATP energy to be used for uphill H⁺ pumping to the medium, which was acidified due to glycolytic activity of the cells.In the subsequent course of evolution, u.v. light was replaced by visible light, which has lower energy but is less dangerous for the cell. It is assumed that bacteriorhodopsin, a simple and very stable light-driven H⁺ pump which still exists in halophilic and thermophilic Archaea, was the primary system utilizing visible light. The formed was used to reverse the H⁺-ATPase, which began to function as H⁺-ATP-synthase. Later, bacteriorhodopsin photosynthesis was substituted by a more efficient chlorophyll photosynthesis, producing not only ATP, but also carbohydrates. O₂, a side product of this process, was consumed by the H⁺-motive respiratory chain to form in the dark. At the next stage of evolution, a parallel energy-transducing mechanism appeared which employed Na⁺ instead of H⁺ as the coupling ion (the Na⁺ cycle). As a result, the bioenergetic system became more stable under unfavorable conditions. Apparently, the latest inventions of evolution of biological energy transducers are those which can utilize and outside the coupling membrane, like the bacterial flagellar motor and the TonB-mediated uphill transport of solutes across the outer membrane of bacteria.     

Maximal oxygen uptake, maximal voluntary isometric contraction and physical activity in young Danish adults

In a randomly selected sample of 88 men and 115 women, aged 23–27 years from Denmark, maximal oxygen uptake ( O_2max), maximal voluntary isometric contraction (MVC) in four muscle groups and physical activity were studied. The O_2max was 48.0 ml · min^–1 kg^–1 and 39.6 ml · min^–1 · kg^–1 for the men and the women, respectively. The MVC was 10% lower than in a comparable group of Danes of the same age and height studied 35 years ago. Only in men was sports activity directly related to O_2max (ml · min^–1 · kg^–1; r=0.31, P<0.01). The MVC of the knee extensors was related to O_2max in the men (r=0.31, P<0.01), but there was no relationship between the other measurements of MVC and O_2max. In the women O_2max (ml · min^–1 · kg^–1) was only related to body size, i.e. body mass index, percentage body fat and body mass [(r= –0.47, –0.48 (both P<0.001) and –0.34. (P<0.01), respectively)]. There were differences in O_2max in the men, according to education and occupation. Blue collar workers and subjects attending vocational or trade schools in 1983 had lower O_2max and more of them were physically inactive. In the women differences were also found, but there was no clear pattern among the groups. More of the women participated regularly in sports activity, but more of the men were very active compared to the women.     

The human V pre B gene is located on chromosome 22 near a cluster of {\text{V}}_{\lambda _1 } gene segments

The chromosomal location of the human V _pre B gene was determined by Southern blotting analysis of restriction enzyme-digested DNAs from a panel of 17 mouse-human somatic cell hybrids. The pattern of hybridization of a V_preB-specific probe in conjunction with earlier analysis of several marker genes allowed the following conclusions: 1) V _pre B is on human chromosome 22 within band 22q11.2 distal to the bcr-like gene, bcr-2 and proximal to the bcr-like gene, bcr-4. 2) V_preB has been localized relative to several constitutional and tumor-specific breakpoints within 22q 11.2, segregates in hybrids retaining 22q^–chromosomes with some but not with all members of the subgroup of the V genes, and is amplified with these genes in K562 cells. 3) The order of the loci on chromosome 22 is centromerebcr-2, V _preB, .     

Altitudinal and seasonal effects on aerobic metabolism of deer mice

Summary I compared the maximal aerobic metabolic rates ( ), field metabolic rates (FMR), aerobic reserves ( -FMR), and basal metabolic rates (BMR) of wild and recently captured deer mice from low (440 m) and high (3800 m) altitudes. To separate the effects of the thermal environment from other altitudinal effects, I examined mice from different altitudes, but similar thermal environments (i.e., summer mice from high altitude and winter mice from low altitude). When the thermal environment was similar, , FMR, and aerobic reserve of low and high altitude mice did not differ, but BMR was significantly higher at high altitude. Thus, in the absence of thermal differences, altitude had only minor effects on the aerobic metabolism of wild or recently captured deer mice.At low altitude, there was significant seasonal variation in , FMR, and aerobic reserve, but not BMR. BMR was correlated with , but not with FMR. The significant positive correlation of BMR with indicates a cost of high , because higher BMR increases food requirements and energy use during periods of thermoneutral conditions.Abbreviations BMR basal metabolic rate - FMR field metabolic rate - partial pressure of oxygen - T _a ambient temperature - T _b body temperature - T _e operative temperature - maximal aerobic metabolic rate