Chlorophyll-nutrient relationships in North Island lakes (New Zealand)

A model for the prediction of chlorophyll a in the near surface waters (1 m) of North Island lakes was developed using data from the literature and our own study of 12 North Island lakes. Annual geometric mean concentrations of chlorophyll a, total nitrogen and total phosphorus were used since no distinct growing season was discernable. Annual mean ratios of total nitrogen to total phosphorus in the near surface waters ranged between 10 and 59 (by weight). Strong correlations were obtained between log-transformed values of chlorophyll a and total nitrogen (r² = 0.53, n = 16), chlorophyll a and total phosphorus (r² = 0.71, n = 21), and between total nitrogen and total phosphorus (r² = 0.69, n = 16). However, after correcting for the high interdependency between total nitrogen and total phosphorus, only total phosphorus was found to be important in predicting chlorophyll concentrations. Much of the variance in the chlorophyll-phosphorus relation was attributable to differences in mean lake depth. Lakes with mean depths less than 11 m had significantly more chlorophyll a per unit of total phosphorus ( = 0.54 µg · µg^–1, SE = 0.05, n = 6) than lakes of greater mean depth ( = 0.17 µg · µg^–1, SE = 0.02, n = 14). When the effect of mean depth was taken into account, 89% of the variance in chlorophyll a was explained compared with 71% for the simple linear regression on total phosphorus alone.     

Effects of root temperature on uptake of nitrate and ammonium ions by barley grown in flowing-solution culture

Summary Barley plants (Hordeum vulgare L.) grown from seed for 28 days in flowing solution culture were subjected to different root temperatures (3, 5, 7, 9, 11, 13, 17, 25°C) for 14 days with a common air temperature of 25/15°C (day/night). Uptake of NH₄ and NO₃ ions was monitored separately and continuously from solutions maintained at 10 M NH₄NO₃ and pH 6.0. Effects of root temperature on unit absorption rate , flux and inflow were compared. After 5 days , and increased with temperature over the range 3–11°C for NH₄ ions and over the range 3–13°C for NO₃ ions, with little change for either ion above these temperatures. Q₁₀ temperature coefficients for NH₄ ions (3–13°C) were 1.9, 1.7 and 1.6 for , and respectively, the corresponding values for NO₃ ions being 5.0, 4.5 and 4.6. For both ions, , and changed with time as did their temperature dependence over the range 3–25°C, suggesting that rates of ontogenetic development and the extent of adaptation to temperature may have varied among treatments.     

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)     

Effect of temperature and humidity on evaporative water loss in Anna's hummingbird (Calypte anna)

Summary Evaporative water loss (EWL), oxygen concumption , and body temperature (T_b) of Anna's Hummingbirds (Calypte anna; ca. 4.5g) were measured at combinations of ambient temperature (T_a) and water vapor density (_va) ranging from 20 to 37 °C and 2 to 27 g·m^-3, respectively. The EWL decreased linearly with increasing _va at all temperatures. The slopes of least squares regression lines relating EWL to _va at different temperatures were not significantly different and averaged-0.50 mg H₂O·m^-3·g^-2·h^-1 (range:-0.39 to-0.61). Increased _va restricted EWL in C. anna more than has been reported for other endotherms in dry air. The percent of metabolic heat production dissipated by evaporation ( ) was lower than that of other birds in dry air, but higher than that for other birds at high humidity when T_a 33 °C. When T_a>33 °C the effect of humidity on was similar to that in other birds. Calypte anna might become slightly hyperthermic at T_a>37 °C, which could augment heat transfer by increasing the T_b-T_a gradient. Body temperature for C. anna in this study was 43 °C (intramuscular) at T_as between 25 and 35 °C, which is above average for birds. It is estimated that field EWL is less than 30% of daily water loss in C. anna under mild temperature conditions (<35 °C).Abbreviations BMR basal metabolic rate - EWL evaporative water loss - percent of metabolic heat production dissipated by evaporation - ambient water vapor density - body surface water vapor density - RMR resting metabolic rate - T_a ambient-temperature - T_b body temperature - T_d dew-point temperature - TNZ thermoneutral zone - T_s body surface temperature - carbon dioxide production - oxygen consumption     

Oxygen controlled batch cultivations of Schizophyllum commune for enhanced production of branched β-1,3-glucans

Oxygen and shear stress are the key factors for enhanced glucan production with Schizophyllum commune. During batch cultivation control of or (specific oxygen uptake rate) was achieved by variation of the impeller speed. Biomass was modelled by using the carbon and oxygen balance derived from exhaust data. At mycel growth a of 0.042 h^–1 presents just the border before oxygen limitation arises and is simultaneously the optimum operation condition for maximum glucan formation. Related to an overall cultivation time of 72 h a maximum of both productivity (4.3 kg m^–3 d^–1) and yield (13 kg m^–3) were obtained.List of Symbols C kg m^–3 concentration - k _L a h ^–1 volume related oxygen transfer coefficient - K _s mol m^–3 substrate saturation constant - N rpm impeller speed - % oxygen partial pressure of the liquid phase - kg m^–3h^–1 oxygen uptake rate - h^–1 specific oxygen uptake rate, kg O₂ (kg biomass h)^–1 - t h time - yield coefficient (biomass formed/oxygen consumed) Greek Symbols h^–1 specific growth rate Indices O ₂ oxygen - X biomass - L liquid phase - * gas/liquid interface - S substrate (glucose) Dedicated to the 65th birthday of Professor Fritz Wagner.This work was kindly supported in parts by B. Braun Biotech International. The authors are grateful to Prof. Dr. Fritz Wagner for scientific support and appreciate the technical assistance of Detlev Rasch     

Ventilatory responses to exercise and carbon dioxide in elderly and younger humans

The present investigation examined the relationship between CO₂ sensitivity [at rest (S _R) and during exercise (S _E)] and the ventilatory response to exercise in ten elderly (61–79 years) and ten younger (17–26 years) subjects. The gradient of the relationship between minute ventilation and CO₂ production ( _E/ CO₂) of the elderly subjects was greater than that of the younger subjects [mean (SEM); 32.8 (1.6) vs 27.3 (0.4); P<0.01]. At rest, S _R was lower for the elderly than for the younger group [10.77 (1.72) vs 16.95 (2.13) 1 · min^–1 · kPa^–1; 1.44 (0.23) vs 2.26 (0.28) 1 · min^–1 · mmHg^–1; P<0.05], but S _E was not significantly different between the two groups [17.85 (2.49) vs 19.17 (1.62) l · min^–1 · kPa^–1; 2.38 (0.33) vs 2.56 (0.21) 1 · min^–1 · mmHg^–1]. There were significant correlations between both S _R and S _E, and _E/ CO₂ (P<0.05; P<0.001) for the younger group, bot none for the elderly. The absence of a correlation for the elderly supports the suggestion that _E/ CO₂ is not an appropriate index of the ventilatory response to exercise for elderly humans.     

Cardiovascular responses to facial cooling during low and moderate intensity exercise

To investigate the hypothesis that facial cooling (FC) exerts a greater influence on the cardiovascular system at lower versus higher levels of exercise, this study examined the effect of facial cooling [mean (SE): 0 (2)°C at 0.8 m·s^–1 wind velocity] during 30 min low [35% maximum oxygen consumption ( O_2max)] and moderate (70% O_2max) levels of cycle ergometry in the supine position. Five male subjects were assigned in random order to four exercise conditions: (1) FC at 35% O_2max(FC35), (2) no cooling (NFC35), (3) FC at 70% O_2max(FC70), and (4) no cooling (NFC70). Heart rate (f _c), stroke volume (V _s), and cardiac output ( _c) were measured at rest and every 10 min of exercise using impedance cardiography. During FC35, the change in f _c [mean (SE)] was significantly lower (P < 0.05) than NFC35 at 10 [22 (5) vs 31 (3) beats· min^–1], 20 [29 (6) vs 35 (3) beats·min^–1], and 30 [29 (5) vs 38 (4) beats·min^–1] min. No differences in f _c were observed between FC70 and NFC70. Furthermore, FC had no effect on V _s or _cat either exercise intensity. However, when comparing the FC70 and NFC70 conditions, there was a significant main effect (P<0.05) in mean arterial pressure (P _a) response with cooling despite the fact that neither V _s or _cwere different from the NFC70 control. The increase (P < 0.05) in the estimated change in systemic vascular resistance ( _a· _c ^–1) could partly explain the relative rise in _aat FC70. No pressor effect of cooling was observed at 35% O_2max. The results suggest that the FC condition promotes exercise bradycardia at low levels of exercise and exerts a greater pressor response during moderate exercise.     

Oxygen transport and cardiovascular responses in skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) exposed to acute hypoxia

Summary Responses to acute hypoxia were measured in skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) (1–3 kg body weight). Fish were prevented from making swimming movements by a spinal injection of lidocaine and were placed in front of a seawater delivery pipe to provide ram ventilation of the gills. Fish could set their own ventilation volumes by adjusting mouth gape. Heart rate, dorsal and ventral aortic blood pressures, and cardiac output were continuously monitored during normoxia (inhalant water (PO ₂>150 mmHg) and three levels of hypoxia (inhalant water PO ₂130, 90, and 50 mmHg). Water and blood samples were taken for oxygen measurements in fluids afferent and efferent to the gills. From these data, various measures of the effectiveness of oxygen transfer, and branchial and systemic vascular resistance were calculated. Despite high ventilation volumes (4–71·min^-1·kg^-1), tunas extract approximately 50% of the oxygen from the inhalant water, in part because high cardiac outputs (115–132 ml·min^-1·kg^-1) result in ventilation/perfusion conductance ratios (0.75–1.1) close to the theoretically ideal value of 1.0. Therefore, tunas have oxygen transfer factors (ml O₂·min^-1·mmHg^-1·kg^-1) that are 10–50 times greater than those of other fishes. The efficiency of oxygen transfer from water in tunas (65%) matches that measured in teleosts with ventilation volumes and order of magnitude lower. The high oxygen transfer factors of tunas are made possible, in part, by a large gill surface area; however, this appears to carry a considerable osmoregulatory cost as the metabolic rate of gills may account for up 70% of the total metabolism in spinally blocked (i.e., non-swimming) fish. During hypoxia, skipjack and yellowfin tunas show a decrease in heart rate and increase in ventilation volume, as do other teleosts. However, in tunas hypoxic bradycardia is not accompanied by equivalent increases, in stroke volume, and cardiac output falls as HR decreases. In both tuna species, oxygen consumption eventually must be maintained by drawing on substantial venous oxygen reserves. This occurs at a higher inhalant water PO₂ (between 130 and 90 mmHg) in skipjack tuna than in yellowfin tuna (between 90 and 50 mmHg). The need to draw on venous oxygen reserves would make it difficult to meet the oxygen demand of increasing swimming speed, which is a common response to hypoxia in both species. Because yellowfin tuna can maintain oxygen consumption at a seawater oxygen tension of 90 mmHg without drawing on venous oxygen reserves, they could probably survive for extended periods at this level of hypoxia.Abbreviations BP_da, BP_va dorsal, ventral aortic blood pressure - C _aO₂, C _vO₂ oxygen content of arterial, venous blood - DO₂ diffusion capacity - E_b, E_w effectiveness of O₂ uptake by blood, and from water, respectively - Hct hematocrit - HR heart rate - PCO₂ carbon dioxide tension - P _aCO₂, P _vCO₂ carbon dioxide tension of arterial and venous blood, respectively - PO₂ oxygen tension - P _aO₂, P _vO₂, P _iO₂, P _cO₂ oxygen tension of arterial blood, venous blood, and inspired and expired water, respectively - pHa, pHv pH of arterial and venous blood, respectively - P_w—b effective water to blood oxygen partial pressure difference - Pg partial pressure (tension) gradient - cardiac output - R vascular resistance - SV stroke volume - SEM standard error of mean - TO₂ transfer factor - U utilization - _g ventilation volume - O₂ oxygen consumption     

Sodium influx in isolated gills of the freshwater mussel,Ligumia subrostrata

Summary Isolated gills of the freshwater mussel,Ligumia subrostrata, accumulate Na from a pondwater bathing medium. The rate of Na transport by the isolated gill is 13.2±1.1 mol (g dry gill·10 min)^–1 which equals or exceeds the estimated Na transport rate of intact animals. Sodium influx is saturable with aV _max of 13.6±1.2 mol (g dry gill·10 min)^–1 and an affinity (K _s) of 0.17 mM Na/l. The isolated gills survive prolonged exposure to pondwater with a constant of 890 l O₂ (g dry gill·h)^–1 over a 4 h period. Sodium transport in the isolated gills is stimulated 80% above control values by 10^–4 M serotonin, 60% by 0.5 mM cAMP and 60% by 12.5 g/ml nystatin. Sodium influx is inhibited by 0.5 mM amiloride and 1 mM lithium.     

Decrease in maximal sodium permeability and slow sodium inactivation produced by trimecaine in the Ranvier node

The action of trimecaine on sodium permeability of the membrane was studied by the voltage clamp method in single nodes of Ranvier. Like procaine, trimecaine was shown to reduce maximal sodium permeability ( _Na) and to induce slow sodium inactivation. The slow inactivation arising in the presence of trimecaine was qualitatively very similar to that observed during the action of procaine or a high external potassium concentration. Dose-effect curves were obtained for _Na and slow inactivation and they showed that one molecule of trimecaine reacts with one sodium channel in the mechanism of both these effects. The local anesthetic has greater affinity for the receptor responsible for slow inactivation (equilibrium constants about 0.3·10^–3 M for _Na and 0.2·10^–14 M for slow inactivation.A. V. Vishnevskii Institute of Surgery, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 8, No. 4, pp. 418–425, July–August, 1976.     

Capacitance,short-circuit current and osmotic water flow across different regions of the isolated toad skin

Summary The amphibian antidiuretic hormone, arginine vasotocin, stimulated osmotic water flow across isolated skin from the pelvic but not the pectoral skin of the toad, Bufo woodhouseii. Changes in the apical membrane capacitance were not observed for either region of the skin following treatment with arginine vasotocin when there was an osmotic gradient across the tissue. In the absence of an osmotic pressure gradient, the apical membrane capacitance of the pelvic skin increased from 2.8±0.5 to 3.3±0.6 F · cm^-2 after treatment with 5 · 10^-8 M arginine vasotocin. Under these conditions, apical membrane capacitance of the pectoral skin was 1.8±0.1 F · cm^-2 and did not change significantly after arginine vasotocin treatment. The amiloride-sensitive short-circuit current across the pelvic skin was stimulated by arginine vasotocin as was the density of channels in the apical membrane as determined by fluctuation analysis. Values for channel density in the pelvic skin also correlated with apical membrane capacitance and increased from 90 to 273 channels per m² of estimated membrane area following arginine vasotocin treatment. In the pectoral skin the stimulation of short-circuit current following arginine vasotocin treatment was small and an increase in channel density could not be demonstrated. The current through single Na⁺ channels in both regions of the skin did not different either before or after arginine vasotocin treatment.Abbreviations A amiloride - ADH antidiuretic hormone - AVT arginine vasotocin - C capacitance - C _a capacitance of apical membrane - f _c corner frequency - i single-channel current - osmotic water flow - IMP intramembrane particles - I _sc short-circuit current - amiloride-sensitive short-circuit current - M channel density - P _o probability of a channel being open - R channel receptor - R _a apical resistance - R _p paracellular resistance     

Differentiation between acetate and higher volatile acids in the modeling of the anaerobic biomethanation process

This paper presents a model for the single-stage completely-mixed anaerobic digestion of complex substrates containing no volatile acids. In the model, volatile acids produced by the acidogenic bacteria are no longer considered together. Acetate is assumed to be representative of the substrate and propionate and butyrate act only as inhibitors for the methanogenic bacteria.Nomenclature ···0 represents factors associated with the influent - ···1 represents factors associated with the acidogenic bacteria - ···2 represents factors associated with the methanogenic bacteria - Q hydraulic flow (1/d) - V reactor liquid volume (1) - T temperature of the mixed liquor (° C) - S microorganisms concentration (mg/1) - L volatile solids concentration (mg VS/1) - Lb biodegradable volatile solids concentration (mg VS/1) - VA2 acetate concentration (mg/1) - VA3 volatile acids with 3 to 5 carbon atoms concentration (mg/1) - methane rate production (1 CH₄/1_digester.d) - Km saturation coefficient (mg/l) - Ki inhibition coefficient (mg/l) - specific growth rate (1/d) - maximum specific growth rate (1/d) - b biological decay coefficient (1/d) - Arrhénius coefficient (–) - yield of acidogenic bacteria per mg of biodegradable matter consumed (mg S₁/mg L_b) | (mg S₂/mg VA2) - yield of methanogenic bacteria per mg of VA2 consumed - yield of methane production per mg of S₂ formed (1 CH₄/mg S₂) - proportion of VA2 produced per mg of S₁ biosynthetised - proportion of VA3 produced per mg of S₁ biosynthetised - Y_sp volume of CH₄ produced per g of volatile solids eliminated     

New species and new records of Callionymus from the Pacific Ocean (Teleostei: Callionymidae)

Recently obtained material of Callionymus from the Pacific Ocean includes: Callionymus marquesensis sp. n. (Marquesas Islands), characterized within the C. variegatus-group of the subgenus Calliurichthys by its preopercular spine formula of with an upcurved main tip and a bony keel between the points on the dorsal margin, and a spotted dorsal fin without filaments which is higher than the 1st D₂ ray in both sexes; C. pleurostictus Fricke, 1982, record from New Britain and Solomon Islands, with a discussion of competition with C. delicatulus; C.simplicicornis Valenciennes, 1837, record from Society Islands and Marquesas Islands, with a discussion of competition with C. marquesensis; C. obscurus sp. n. (Ambon, Indonesia) which is characterized within the subgenus Spini-capitichthys by its preopercular spine formula with an upcurved main tip and very small ventral serrae, its weakly armed head, and its 7 anal fin rays.     

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 effect of respiratory chain composition on the growth efficiencies of aerobic bacteria

The relationship between respiratory chain redox carrier composition and the efficiency of aerobic growth in continuous culture under carbon-limited conditions has been investigated for nine species of bacteria.True molar growth yields with respect to molecular oxygen ( ) or dissimilated carbon source (Y _{substrate ox.} ^max ) were not significantly affected by the nature either of the major quinone component (ubiquinone or menaquinone), of the major cytochrome oxidase moiety (cytochrome aa ₃ or o) or of the transhydrogenase segment (energy-dependent transhydrogenase, energy-independent transhydrogenase or no transhydrogenase), but were significantly influenced by the presence or absence of a high potential, membrane-bound cytochrome c. Under glycerol-limited conditions the presence of cytochrome c raised the average from 51.1 to 84.3 g cells · mole O ₂ ^–1 , and the average Y _{glycerol ox.} ^max from 154.6 to 233.2 g cells · mole glycerol oxidised^–1; the presence of this redox carrier also elicited increases in and Y _{substrate ox.} ^max of a similar order during growth under lactate, and glucose-limited conditions.The average efficiencies of aerobic energy conservation calculated from these true molar growth yields were 3.4 mole ATP equivalents · mole O ₂ ^–1 for organisms with respiratory chains which were deficient in cytochrome c and 5.9 mole ATP equivalents · mole O ₂ ^–1 for organisms with respiratory chains which contained cytochrome c.It is concluded from these data, and from parallel measurements of whole cell H⁺/O ratios, that bacterial respiratory systems invariably exhibit energy conservation at sites 1 and 2 but that the presence of a highpotential, membrane-bound cytochrome c is an obligatory prerequisite for energy conservation at site 3.     

Isolation and characterization of thiosulfate reductases from the green alga Chlorella fusca

Thiosulfate-reductase activity (TSR) measured as sulfide release from thiosulfate was detected in crude extracts of Chlorella using dithioerythritol (DTE) as electron donor. Purification of this activity by ammonium-sulfate precipitation between 35% and 80% followed by Sephadex G-50 gel filtration, diethylaminoethyl-cellulose chromatography, and gel filtration on Biogel A 1.5 M led to four distinct proteins having molecular weights of: TSR I, 28000; TSR II, 26500; TSR III_a, 55000; TSR III_b, 24000 daltons. These thiosulfate reductases were most active with DTE; the monothiols glutathione, l-cysteine, and -mercaptoethanol had little activity towards this system. The following pH optima were obtained: for TSR I and TSR II, 9.0; for TSR III_a, 8.5; and for TSR III_b, 9.5. The apparent-K_m data for DTE and thiosulfate were determined to: TSR I, 0.164 mmol·l^-1 and TSR II, 0.156 mmol·l^-1; K_mDTE TSR I, 1.54 mmol·l^-1 and TSR II 1.54 mmol·l^-1. The thiosulfate reductases III_a and III_b were further stimulated by addition of thioredoxin. All TSR fractions catalyzed SCN formation from thiosulfate and cyanate and thus had rhodanese activity; this activity, however, could only be detected in the presence of thiols.Abbreviations DTE dithioerythritol - TSR thiosulfate reductase Dedicated to Professor Dr. Hubert Ziegler on the occasion of his 60th birthday     

The effect of short-term fasting and a single meal on protein synthesis and oxygen consumption in cod,Gadus morhua

Summary Rates of protein synthesis and oxygen consumption ( O₂) in cod were compared in both fasted and refed animals. During a 14-day fast both protein synthesis and respiration rates fell to stable values after 6 days. When a meal of whole sandeel at 6% body weight was fed to fish fasted for 6 days, protein synthesis and ( O₂) increased to a maximum at between 12 and 18 h after feeding. Peak ( O₂) was about twice the pre-feeding values, while whole animal protein synthesis increased four-fold. There were differences between tissues in the timing of maximum protein synthesis; the liver and stomach responded faster than the remainder of the body. Maximum protein synthesis rates in the liver and stomach occurred at 6 h after feeding, at which time their calculated contribution to total ( O₂) was 11%. Similar calculations suggested that the integrated increment in whole animal protein synthesis contributed between 23% and 44% of the post-prandial increase in ( O₂). It was concluded that protein synthesis is an important contributor to increased ( O₂) after feeding in cod.Abbreviations A _s absolute rate of protein synthesis - ASDA apparent specific dynamic action - ATP adenosine triphosphate - k _s fractional rate of protein synthesis - k _s/RNA amount of protein synthesized per unit RNA - ( O₂) oxygen consumption - PCA perchloric acid - RNA ribonucleic acid     

Carbon dioxide desorption from fermentation broth by use of oxygen vectors

The ability of oxygen vector to extract produced carbon dioxide has been tested in an anaerobic fermentation. During the continuous culture of Clostridium acetobutylicum at pH 4.6 and at a dilution rate of 0.124 h^–1, a feed composed of an emulsion of 18.5% by volume of Forane F66E was able to extract about 9% of the total CO₂ produced under CO₂ partial pressure equal to 0.42 atm. A theoretical evaluation of the extracted amount, based on the hypothesis of total saturation of the vector by carbon dioxide, has lead to very good agreement.List of Symbols [AA] g/l acetic acid concentration - [BA] g/l butyric acid concentration - D 1/h Q _w /V dilution rate - [ETH] g/l ethanol concentration - H _w Henry constant of CO₂ for water at 37°C (=23.91 mmol/(l atm)) - H _F Henry constant of CO₂ for Forane at 37°C (=83.4 mmol/(l atm)) - H _i g/mol molar mass of componenti - P _i atm partial pressure of gasi - W _w l/h aqueous flow - Q_f 1/h Forane flow - mmol/(lh) dissolved CO₂ flow in aqueous effluent - mmol/(lh) CO₂ gas flow - mmol/(lh) CO₂ gas flow without Forane - mmol/(lh) CO₂ gas flow with Forane - mmol/(lh) total CO₂ production - r _X g/(lh) biomass production rate - r _G mmol/(lh) total gas flow - mmol/(lh) hydrogen production - mmol/(lh) nitrogen flow - r _S mmol/(lh) glucose input - V 1 fermentor volume     

Phytoplankton dynamics,primary productivity and community metabolism in a north-central Texas pond

Phytoplankton diversity, primary productivity and community metabolism were measured for 1 year in a 0.94 ha pond located in north-central Texas. Gross primary production ranged from 4.5 to 46.8 kcal m⁻² day⁻¹ ( =22.0 kcal m⁻² day⁻¹) and community metabolism ranged from 7.3 to 32.4 kcal m⁻² day⁻¹ ( =14.8 kcal m⁻² day⁻¹). Average production/respiration ratio (1.5) showed that the pond was principally autotrophic. Photosynthetic efficiency (gross primary production/0.5 total solar radiation) ranged from 0.32 to 2.8 with a mean of 1.2. Phytoplankton diversity based on numbers and biomass fluctuated greatly. Highest gross primary productivity occurred during Cyanophyta blooms in late summer-early fall when species diversity was minimal. Water temperature and turbidity, which governed light penetration, were the principal determinants of primary production.