Modulation of plasma antidiuretic hormone levels does not change the magnitude of the LPS-induced febrile response in Pekin ducks

The objective of this study was to determine the effect of modulating the plasma concentrations of the avian antidiuretic hormone, arginine vasotocin (AVT), upon the febrile response to lipopolysaccharide (LPS) in Pekin ducks. LPS, intravenously administered into conscious control birds at a dose of 1 μg · kg⁻¹, caused a monophasic increase in body temperature of 0.85 ± 0.12 °C associated with a Thermal Response Index of 2.5 ± 0.6 C° h. Plasma AVT concentrations in the control birds also increased with the progression of the fever response, more than doubling from their basal values. Ducks in which the circulating level of AVT had either been elevated by the intravenous infusion of the peptide or dehydration, or reduced by the administration of a specific AVT antibody prior to LPS administration, produced body temperature profiles and Thermal Response Index values that did not differ significantly from those of the control birds. The lack of any direct effect of variations in plasma AVT concentrations upon the magnitude of the fever response indicates that the LPS-induced elevation in plasma AVT is not associated with modulating the rise in body temperature obtained in avian fever. Accepted: 7 March 2000     

Ontogeny of deep-body cold sensitivity in Pekin ducklings Anas platyrhynchos

The ontogeny of deep-body cold sensitivity was studied in 1 to 12 days old Pekin ducklings Anas platyrhynchos. Deep-body cold sensitivity was determined by means of thermodes implanted in the abdominal cavity. The thermodes were perfused with cold water for 15-min periods to lower the core temperature. Cooling of the body core elicited increases in metabolic rate and vasoconstrictions in the legs of all the ducklings. From the changes induced in metabolic rate and core temperature, deep-body cold sensitivity values of between −5.17 and −6.36 W · kg⁻¹ · °C⁻¹, were estimated. These values, which are in the range of those reported previously for adult Pekin ducks, did not change with age, and it is concluded that deep-body cold sensitivity is fully developed at hatching. Our next aim was to investigate whether the autonomic responses elicited by exposure of ducklings to cold ambient conditions could be explained by temperature changes within the body core. During cold exposure, the increase in metabolic rate was not accompanied by a concomitant decrease in core temperature. On the contrary, deep-body temperature increased slightly during the initial phase of cold exposure. The ducklings attained a metabolic rate amounting to 85–90% of their peak metabolic rate before the core temperature fell below the regulated level measured at thermoneutrality. Thus, despite the findings that Pekin ducklings have a highly-developed deep-body cold sensitivity, their metabolic cold defence under natural conditions seems to be mediated primarily by peripheral thermoreceptors. Accepted: 7 January 1997     

Water influx and efflux in free-flying pigeons

We used tritium-labeled water to measure total body water, water influx (which approximated oxidative water production) and water efflux in free-flying tippler pigeons (Columba livia) during flights that lasted on average 4.2 h. At experimental air temperatures ranging from 18 to 27 °C, mean water efflux by evaporation and excretion [6.3 ± 1.3 (SD) ml · h⁻¹, n = 14] exceeded water influx from oxidative water and inspired air (1.4 ± 0.7 ml · h⁻¹, n = 14), and the birds dehydrated at 4.9 ± 0.9 ml · h⁻¹. This was not significantly different from gravimetrically measured mass loss of 6.2 ± 2.1 g · h⁻¹ (t = 1.902, n = 14, P>0.05). This flight-induced dehydration resulted in an increase in plasma osmolality of 4.3 ± 3.0 mosmol · kg⁻¹ · h⁻¹ during flights of 3–4 h. At 27 °C, the increase in plasma osmolality above pre-flight levels (ΔP _osm = 7.6±4.29 mosmol · kg⁻¹ · h⁻¹, n = 6) was significantly higher than that at 18 °C (ΔP _osm = 0.83±2.23 mosmol · kg⁻¹ · h⁻¹, (t = 3.43, n = 6, P < 0.05). Post-flight haematocrit values were on average 1.1% lower than pre-flight levels, suggesting plasma expansion. Water efflux values during free flight were within 9% of those in the one published field study (Gessaman et al. 1991), and within the range of values for net water loss determined from mass balance during wind tunnel experiments (Biesel and Nachtigall 1987). Our net water loss rates were substantially higher than those estimated by a simulation model (Carmi et al. 1992) suggesting some re-evaluation of the model assumptions is required. Accepted: 8 April 1997     

Effect of manipulation of the renin-angiotensin system in control of drinking in juvenile Atlantic salmon (Salmosalar L) in fresh water and after transfer to sea water

Drinking in Atlantic salmon (Salmo salar) juveniles was investigated in fresh water and following transfer to sea water. There was a significant effect of fish size on drinking, and smolts (20–30 g) imbibed about ten times less water than alevins of 0.2–0.3 g. Freshwater smolts drank at a rate of 0.15 ± 0.03 ml · kg⁻¹ · h⁻¹ and administration of doses of 10 or 20 mg · kg⁻¹ of papaverine (stimulator of the renin- angiotensin system RAS) or [Asn¹, Val⁵]-Angiotensin II (0.4 μmol · kg⁻¹) resulted in significant increases in drinking, while administration of the angiotensin converting enzyme inhibitor, enalapril (50 mg · kg⁻¹) had no effect on drinking. Transfer of Atlantic salmon smolts to 1/3, 2/3 and full strength sea water resulted in significant increases in drinking to 1.06 ± 0.12, 1.24 ± 0.0.16 and 3.89 ± 0.28 ml · kg⁻¹ · h⁻¹, respectively. In sea water, stimulation of the endogenous RAS by administration of papaverine (20 mg · kg⁻¹) resulted in a 20% increase in drinking, while administration of enalapril to doses of 50 and 200 mg · kg⁻¹ lowered drinking to 1.99 ± 0.48 and 0.32 ± 0.06 ml · kg⁻¹ · h⁻¹, respectively. All treatments were without effect on blood plasma levels of Na⁺ and Cl⁻ in fresh water, while in sea water smolts both stimulation and inhibition of drinking resulted in hemoconcentration of Na⁺ and Cl⁻. The role of the renin angiotensin system in control of drinking and hydromineral balance in Atlantic salmon is discussed. Accepted: 27 February 1997     

Active calcium ion transport in Xenopuslaevis skin

The skin of intact, free-swimming Xenopus laevis transports Ca²⁺ inwardly in a manner that is proportional to the external [Ca²⁺] up to about 0.3 mmol · l⁻¹, saturates above 0.3 mmol · l⁻¹, and is opposed to the electrochemical gradient. Efflux is relatively constant at external concentrations between 0.016 and 0.6 mmol · l⁻¹; net flux which is negative below 0.125 mmol · l⁻¹ becomes positive above this external [Ca²⁺]. Allometric analysis suggests that both Ca²⁺ influx and efflux scale to the 2/3 power approximately like surface area. There were no significant differences in influx between summer and fall animals; however, efflux was greater in the fall and this resulted in a change from positive balance in the summer to negative balance in the fall. Isolated skins were shown to support a Ca²⁺ uptake rate of nearly 30 nmol · cm⁻² · h⁻¹. The phenylalkylamine verapamil in the apical bathing solution significantly inhibited this at 25 μmol · l⁻¹. The benzothiazepine diltiazem was also effective at 50 μmol · l⁻¹ while the dihydropyradine nifedipine was ineffective up to 100 μmol · l⁻¹. The inorganic ion La³⁺ was effective at blocking Ca²⁺ uptake at 300 μmol · l⁻¹; Ni²⁺ was also effective at 500 μmol · l⁻¹ but Co²⁺ was ineffective up to 500 μmol · l⁻¹. These results suggest that apical calcium channels in Xenopuslaevis skin have properties similar to mammalian L-channels and fish gill Ca²⁺ channels. Accepted: 23 January 1997     

Water and sodium balances and metabolic physiology of house mice (Mus domesticus) and short-tailed mice (Leggadina lakedownensis) under laboratory conditions

A laboratory study investigated the metabolic physiology, and response to variable periods of water and sodium supply, of two arid-zone rodents, the house mouse (Mus domesticus) and the Lakeland Downs short-tailed mouse (Leggadina lakedownensis) under controlled conditions. Fractional water fluxes for M. domesticus (24 ± 0.8%) were significantly higher than those of L. lakedownensis (17 ± 0.7%) when provided with food ad libitum. In addition, the amount of water produced by M. domesticus and by L. lakedownensis from metabolic processes (1.3 ± 0.4 ml · day⁻¹ and 1.2 ± 0.4 ml · day⁻¹, respectively) was insufficient to provide them with their minimum water requirement (1.4 ± 0.2 ml · day⁻¹ and 2.0 ± 0.3 ml · day⁻¹, respectively). For both species of rodent, evaporative water loss was lowest at 25 °C, but remained significantly higher in M. domesticus (1.1 ± 0.1 mg H₂O · g^−0.122 · h⁻¹) than in L. lakedownensis (0.6 ± 0.1 mg H₂O · g^−0.122 · h⁻¹). When deprived of drinking water, mice of both species initially lost body mass, but regained it within 18 days following an increase in the amount of seed consumed. Both species were capable of drinking water of variable saline concentrations up to 1 mol · l⁻¹, and compensated for the increased sodium in the water by excreting more urine to remove the sodium. Basal metabolic rate was significantly higher in M. domesticus (3.3 ± 0.2 mg O₂ · g^−0.75 · h⁻¹) than in L. lakedownensis (2.5 ± 0.1 mg O₂ · g^−0.75 · h⁻¹). The study provides good evidence that water flux differences between M. domesticus and L. lakedownensis in the field are due to a requirement for more water in M. domesticus to meet their physiological and metabolic demands. Sodium fluxes were lower than those observed in free-ranging mice, whose relatively high sodium fluxes may reflect sodium associated with available food. Accepted: 16 August 1999     

Uptake of 3-O-methyl-D-[U-14C]glucose into brain of rainbow trout: possible effects of melatonin

The influx of glucose into the brain and plasma glucose disappearance were estimated in rainbow trout (Oncorhynchus mykiss) intravenously injected (1 ml · kg⁻¹ body weight) with a single dose (15 μCi · kg⁻¹ body weight) of 3-O-methyl-D-[U-¹⁴C]glucose ([U-¹⁴C]-3-OMG) at different times (2–160 min), and after intravenous injection at 15 min of increased doses (10–60 μCi · kg⁻¹ body weight) of [U-¹⁴C]-3-OMG. Brain and plasma radiotracer concentrations were measured, and several kinetic parameters were calculated. The apparent brain glucose influx showed a maximum after 15–20 min of injection then decreased to a plateau after 80 min. Brain distribution space of 3-OMG increased from 2 min to 20 min reaching equilibrium from that time onwards at a value of 0.14 ml · g⁻¹. The unidirectional clearance of glucose from blood to brain (k₁) and the fractional clearance of glucose from brain to blood (k₂) were estimated to be 0.093 ml · min⁻¹ · g⁻¹, and 0.867 min⁻¹, respectively. A linear increase was observed in brain and plasma radiotracer concentrations when increased doses of [U-¹⁴C]-3-OMG were used. All these findings support a facilitative transport of glucose through the blood-brain barrier of rainbow trout with characteristics similar to those observed in mammals. The injection of different doses of melatonin (0.25–1.0 mg · kg⁻¹) significantly increased brain glucose influx suggesting a possible role for melatonin in the regulation of glucose transport into the brain. Accepted: 26 January 2000     

Effects of ANG II and III and angiotensin receptor blockers on nasal salt gland secretion and arterial blood pressure in conscious Pekin ducks (Anas platyrhynchos)

The vertebrate renin-angiotensin system controls cardiovascular, renal and osmoregulatory functions. Angiotensin II (ANG II) is the most potent hormone of the RAS but in some vertebrate animals angiotensin III (Val⁴-ANG III) may be a hormone. We studied the effects of some angiotensins and mammalian ANG II receptor antagonists on nasal salt gland function and arterial blood pressure in conscious white Pekin ducks. Nasal salt gland fluid secretion (NFS) was induced by a 10 ml · kg⁻¹ bw i.v. injection of a NaCl solution (1000 mosmol · kg⁻¹ H₂O) and maintained by a continuous i.v. infusion of the same solution at a rate of 0.97 ml · min⁻¹. There was a positive linear correlation between nasal fluid [Na⁺] and osmolality, between [Na⁺] and [K⁺], and also between the rate of NFS and [Na⁺] and [K⁺]. [Asp¹,Val⁵]-ANG II (1 nmol · kg⁻¹ i.v.) inhibited NFS but did not change ionic concentrations. Val⁴-ANG III (1 or 5 nmol · kg⁻¹) and ANG I (1-7) (20 nmol · kg⁻¹) had no effect on NFS. [Sar¹, Ile⁸]-ANG II (SARILE) acted as an ANG II receptor agonist and resulted in a prolonged and complete inhibition of NFS. The AT₁ receptor antagonist, losartan (DuP 753) and the AT₂ receptor antagonist, PD 123319 both failed to block the inhibitory effect of [Asp¹, Val⁵]-ANG II on the nasal salt glands. [Asp¹,Val⁵]-ANG II (2 nmol · kg⁻¹ i.v.) increased mean arterial blood pressure (MABP), whereas the same dose of [Asn¹,Val⁵]-ANG II (teleost) had only 30% of the pressor potency of the avian ANG II. Neither 1 nor 5 nmol · kg⁻¹ of Val⁴-ANG III i.v. nor 20 nmol · kg⁻¹ of ANG I (1-7) had any measurable effect on MABP. SARILE blocked completely the pressor response to [Asp¹,Val⁵]-ANG II but the AT₁ antagonists losartan and CGP 48933 and the AT₂ antagonist PD 123319 all failed to block the pressor response to [Asp¹,Val⁵]-ANG II. These results have substantiated an important role of the nasal salt gland in potassium regulation and highlighted a pharmacological dimorphism of saralasin, namely agonist and antagonist to angiotensin II-mediated inhibition of nasal salt gland function and pressor response, respectively. Using specific nonpeptidergic angiotensin II receptor antagonists, we have confirmed the distinct pharmacology of the avian angiotensin II receptors in a nongallinaceous species and the absence of significant angiotensin I (1-7) and angiotensin II effects on the cardiovascular system and nasal salt gland. Accepted: 6 November 1997     

The use of amiloride to uncouple branchial sodium and proton fluxes in the brown trout, Salmo trutta

Resting proton, ammonium and sodium fluxes in Salmo trutta were 492.6 ± 19.5 (n = 29); 122.9 ± 34.2 (n = 28) and 277.1 ± 18.5 (n = 50) μmol · kg⁻¹ · h⁻¹, respectively. The resting transepithelial potential was found to be composed of three successive potentials, the outermost averaging −7.36 ± 0.19mV, the second, −14.3 ± 1.4 mV and the third −37 ± 1.7 mV. Amiloride inhibits the proton, ammonium and sodium fluxes in a dose-dependent manner at concentrations of 0.5 mmol · 1⁻¹ and 0.1 mmol · l⁻¹, but at 0.01 mmol · l⁻¹, proton and ammonium fluxes remained at control levels whilst the sodium was reduced to 70.59 ± 7.29 μmol · kg⁻¹ · h⁻¹. The trans-epithelial potential was effected in a bi-phasic manner by 0.5 mmol · l⁻¹ amiloride. An initial hyperpolarisation of ca. 6 mV was followed by a sustained depolarisation of ca. 14 mV (towards zero) which persisted until the amiloride was washed off the gill. The initial hyperpolarisation was thought to reflect a rapid inhibition of a positive inward sodium current and the subsequent depolarisation was due to the inhibition of a positive outward current (proton) which would abolish the transepithelial potential. However, at 0.01 mmol ·  l⁻¹ only the hyperpolarisation was seen, due to the inhibition of only the inward sodium current. Acetazolamide (0.1 mmol · l⁻¹) was found to have no significant effect on the proton, ammonium and sodium fluxes. These results indicate that the proton and sodium fluxes across the gill of the freshwater trout are not tightly linked. While this suggests that the trout gill resembles the model of Ehrenburg et al. (1985) of sodium uptake in frog skin, the apical potentials measured in the pavement epithelial cell(s) are too low to account for sodium uptake unless the activity of the sodium in the cells is very low. Accepted: 8 August 1996     

RNA turnover and protein synthesis in fish cells

Protein synthesis in fish has been previously correlated with RNA content. The present study investigates whether protein and RNA synthesis rates are similarly related. Protein and RNA synthesis rates were determined from ³H-phenylalanine and ³H-uridine incorporation, respectively, and expressed as % · day⁻¹ and half-lives, respectively. Three fibroblast cell lines were used: BF-2, RTP, CHSE 214, which are derived from the bluegill, rainbow trout and Chinook salmon, respectively. These cells contained similar RNA concentrations (∼175 μg RNA · mg⁻¹ cell protein). Therefore differences in protein synthesis rates, BF-2 (31.3 ± 1.8)>RTP (25.1 ± 1.7)>CHSE 214 (17.6 ± 1.1), were attributable to RNA translational efficiency. The most translationally efficient RNA (BF-2 cells), 1.8 mg protein synthesised · μg⁻¹ RNA · day⁻¹, corresponded to the lowest RNA half-life, 75.4 ± 6.4 h. Translationally efficient RNA was also energetically efficient with BF-2 cells exploiting the least costly route of nucleotide supply (i.e. exogenous salvage) 3.5–6.0 times more than the least translationally efficient RNA (CHSE 214 cells). These data suggest that differential nucleotide supply, between intracellular synthesis and exogenous salvage, constitutes the area of pre-translational flexibility exploited to maintain RNA synthesis as a fixed energetic cost component of protein synthesis. Accepted: 12 November 1999     

Potential of active excretion of ammonia in three different haline species of crabs

Isolated perfused gills of stenohaline crabs Cancer pagurus adapted to seawater, brackish water-adapted euryhaline shore crabs Carcinus maenas and freshwater-adapted extremely euryhaline Chinese crabs Eriocheir sinensis were tested for their capacity to excrete ammonia. Gills were perfused with haemolymph-like salines and bathed with salines equal in adaptation osmolality. Applying 100 μmol · l⁻¹ NH₄Cl in the perfusion saline and concentrations of NH₄Cl in the bath that were stepwise increased from 0 to 4000 μmol · l⁻¹ allowed us to measure transbranchial fluxes of ammonia along an outwardly as well as various inwardly directed gradients. The gills of all three crab species were capable – to different extents – of active excretion of ammonia against an inwardly directed gradient. Of the three crab species, the gills of Cancer pagurus revealed the highest capacity for active excretion of ammonia, being able to excrete it from the haemolymph (100 μmol · l⁻¹ NH⁺ ₄) through the gill epithelium against ambient concentrations of up to 800 μmol · l⁻¹, i.e. against an eightfold gradient. Carcinus maenas and E. sinensis were able to actively excrete ammonia against approximately fourfold gradients. Within the three crab species, the gills of E. sinensis exhibited the greatest capacity to resist influx at very high external concentrations of up to 4000 μmol · l⁻¹. We consider the observed capacities for excretion of ammonia against the gradient as ecologically meaningful. These benthic crustaceans protect themselves by burying themselves in the sediment, where, in contrast to the water column, concentrations of ammonia have previously been reported that greatly increase haemolymph levels. Electrophysiological results indicate that the permeabilities of the gill epithelia are a clue to understanding the species-specific differences in active excretion of ammonia. During the invasion of brackish water and freshwater, the permeabilities of the body surfaces greatly decreased. The gills of marine Cancer pagurus exibited the greatest permeability (ca. 250 mS cm⁻²), thus representing practically no influx barrier for ions including NH⁺ ₄. We therefore assume that C. pagurus had to develop the strongest mechanism of active excretion of ammonia to counteract influx. On the other hand, freshwater-adapted E. sinensis exhibited the lowest ion permeability (ca. 4 mS cm⁻²) which may reduce passive NH⁺ ₄ influxes at high ambient levels. Accepted: 14 October 1998     

Ca2+ regulation of heart contractility in Octopus

Isometric force development of electrically paced preparations isolated from the systemic heart of Octopus vulgaris were utilized to examine the regulation of contractility by Ca²⁺. Increases in extracellular Ca²⁺, to the physiological level, resulted in enhancement of twitch force. For instance, at 36 beats · min⁻¹ an increase in Ca²⁺ from 3 to 9 mmol · l⁻¹ resulted in a threefold increase in twitch force development. When steady-state contraction at 12 beats · min⁻¹ was followed by a rest period of either 5 or 10 min, the first contraction always exhibited either an increase in twitch force or stayed unchanged such that post-rest twitch force was about 133% of the last value in the steady-state train. Ryanodine (12.5 μmol · l⁻¹), which is considered to be a specific inhibitor of the Ca²⁺ storage and release capabilities of the sarcoplasmic reticulum (SR), was applied to further assess Ca²⁺ handling. Twitch force fell to about 22% of the preteatment level in preparations paced at either 12 or 36 beats · min⁻¹. In all preparations the frequency transition from 12 to 36 beats · min⁻¹ was associated with an increase in resting tension. The␣increase␣was 37 ± 14% prior to ryanodine treatment and was significantly elevated to 127 ± 33% following treatment. When steady-state contraction at 36 beats · min⁻¹ was followed by a rest period of 10 s, the first contraction was not significantly different from the last beat in the train prior to ryanodine; however, with ryanodine treatment, post-rest twitch force development significantly decreased. Twitch force development was regular at pacing rates of up to 300 beats · min⁻¹. Twitch force was maintained up to rates of 84 beats · min⁻¹ but␣decreased thereafter and reached a value of about 10% at 300 beats · min⁻¹. Resting tension increased substantially as frequency was elevated from 12 to 36 beats · min⁻¹ and then gradually increased as frequency was further elevated to 180 beats · min⁻¹. In conclusion, the Octopus ventricle is dependent upon extracellular Ca²⁺ for contraction. A post-rest potentiation of force development, the negative impact of ryanodine, and the ability to respond regularly at high pacing rates imply a strong reliance on the SR in Ca²⁺ cycling based on criteria established for vertebrate hearts. Accepted: 19 January 1997     

Characteristics of dipeptide transport in pig jejunum in vitro

 Characteristics of dipeptide transport in pig jejunum were investigated in vitro by applying the Ussing-chamber technique and mucosal uptake studies. Addition of both glycyl-l-glutamine and glycyl-l-sarcosine (20 mmol · l⁻¹) to the mucosal buffer solution significantly increased the short-circuit current by 2.60 ± 0.15 and 1.57 ± 0.20 μeq · cm⁻² · h⁻¹, respectively. Concentration-dependent changes in short-circuit current followed Michaelis-Menten kinetics with similar affinity constants for both dipeptides. From unidirectional flux rates for radiolabelled glycyl-l-sarcosine, a net flux rate for glycyl-l-sarcosine of 49.8 ± 6.7 nmol · cm⁻² · h⁻¹ was calculated. In mucosal uptake experiments, the apical influx of ¹⁴C-labelled glycyl-l-sarcosine into isolated porcine mucosa was pH dependent and significantly inhibited by glycyl-l-glutamine. Moreover, RT-PCR studies with primers derived from rabbit PepT1 identified two PCR fragments of identical size to rabbit PepT1 from pig intestinal mRNA preparations. In conclusion, our studies revealed key features of mammalian intestinal peptide transporters and give evidence for a PepT1-like transporter in the pig jejunum that could significantly contribute to the overall amino acid absorption from the gut. Accepted: 30 June 1999     

The effect of recombinant human granulocyte/macrophage-colony-stimulating factor (rHu GM-CSF) and rHu G-CSF administration on neutrophil chemiluminescence assay in patients following cyclic chemotherapy

Secondary infections related to neutropenia and functional defects of phagocytes are common consequences in patients treated for cancer. The hematopoietic colony-stimulating factors (CSF) have been introduced into clinical practice as additional supportive measures that can reduce the incidence of infectious complications in patients with cancer and neutropenia. The aim of this study was to determine the role of␣granuolcyte/macrophage(GM)-CSF and granulocyte(G)-CSF in enhancing in vivo human neutrophil function. A luminol-dependent chemiluminescence assay was developed to evaluate whether the repair in neutropenia accompanies the ability of neutrophils to function. A dose of 5 μg G-CSF kg⁻¹ day⁻¹ [recombinant human (rHu) G-CSF; filgrastim] or 250 μg GM-CSF m⁻² day⁻¹ (rHu GM-CSF; molgramostim) was administered subcutaneously once daily to 12 metastatic cancer patients being treated with different cytotoxic regimens. All injections of CSF were given after the initiation of neutropenia and continued until the occurrence of an absolute neutrophil recovery. rHu GM-CSF and rHu G-CSF, administered once daily at the 250 μg m⁻² day⁻¹ and 5 μg kg⁻¹ day⁻¹ level, were effective in increasing the absolute neutrophil count and neutrophil function, as measured by an automated chemiluminescence system. Received: 26 February 1998 / Accepted: 21 May 1998     

Organic halogen removal from chlorinated humic ground water and lake water by nitrifying fluidized-bed biomass characterised by electron microscopy and molecular methods

The dechlorinating and genotoxicity-removing activities of nitrifying fluidized-bed reactor biomass towards chlorinated organic compounds in water were shown at level below 1 ppm. The removal rates of adsorbable organic halogens were 200 μg Cl (g VS day)⁻¹ for chlorinated humic ground water and 50 μyg Cl (g VS day)⁻¹ for chlorinated lake water when studied in batch mode. In a sequenced batch mode the removal rates μg Cl (g VS day)⁻¹] were 2000 from chlorohumus, 1400–1800 from chlorophenols in chlorinated ground water, and 430–720 from chlorohumus in chlorinated lake water. Genotoxicity was removed to a large extent (60%–80%) from the chlorinated waters upon incubation with nitrifying reactor biomass. 2,6-Di-, 2,4,6-tri and 2,3,4,6-tetrachlorophenols competed with chlorinated water organohalogens for dechlorination. The dechlorination of chlorophenols and chlorohumus required no ammonia and was not prevented by inhibitors of ammonia oxidation, nitrapyrin, parathion, sodium diethyldithiocarbamate, or allylthiourea. Electron microscopical inspection of the biomass showed the dominance of clusters of bacteria resembling known nitrifying species, Nitrosomonas, Nitrobacter, and Nitrosospira. This was supported by polymerase chain reaction amplification of the biomass DNA with four different primers, revealing the presence of 16S rDNA sequences assignable to the same species. The most intensive band obtained with the Nitroso4E primer was shown to be closely related to Nitrosomonas europaea by restriction analysis. Received: 27 March 1998 / Received revision: 30 July 1998 / Accepted: 31 July 1998     

Light response characteristics of a morphologically diverse group of southern hemisphere conifers as measured by chlorophyll fluorescence

Unlike northern hemisphere conifer families, the southern family, Podocarpaceae, produces a great variety of foliage forms ranging from functionally broad-, to needle-leaved. The production of broad photosynthetic surfaces in podocarps has been linked qualitatively to low-light-environments, and we undertook to assess the validity of this assumption by measuring the light response of a morphologically diverse group of podocarps. The light response, as apparent photochemical electron transport rate (ETR), was measured by modulated fluorescence in ten species of this family and six associated species (including five Cupressaceae and one functionally needle-leaved angiosperm) all grown under identical glasshouse conditions. In all species, ETR was found to increase as light intensity increased, reaching a peak value (ETR_max) at saturating quantum flux (PPFD_sat), and decreasing thereafter. ETR_max ranged from 217 μmol electrons · m⁻² · s⁻¹ at a PPFD_sat of 1725 μmol photons · m⁻² · s⁻¹ in Actinostrobus acuminatus to an ETR of 60 μmol electrons · m⁻² · s⁻¹ at a PPFD_sat of 745 μmol electrons · m⁻² · s⁻¹ in Podocarpus dispermis. Good correlations were observed between ETR_max and both PPFD_sat and maximum assimilation rate measured by gas-exchange analysis. The effective quantum yield at light saturation remained constant in all species with an average value of 0.278 ± 0.0035 determined for all 16 species. Differences in the shapes of light response curves were related to differences in the response of non-photochemical quenching (q _n), with q _n saturating faster in species with low PPFD_sat. Amongst the species of Podocarpaceae, the log of average shoot width was well correlated with PPFD_sat, wider leaves saturating at lower light intensities. This suggests that broadly flattened shoots in the Podocarpaceae are an adaptation to low light intensity. Received: 15 April 1996 / Accepted: 30 September 1996     

Batch and continuous cultivation of Anaerobiospirillum succiniciproducens for the production of succinic acid from whey

Batch and continuous cultivation of Anaerobiospirillum succiniciproducens were systematically studied for the production of succinic acid from whey. Addition of 2.5 g l⁻¹ yeast extract and 2.5 g l⁻¹ polypeptone per 10 g l⁻¹ whey was most effective for succinic acid production from both treated and nontreated whey. When 20 g l⁻¹ nontreated whey and 7 g l⁻¹ glucose were used as cosubstrates, the yield and productivity of succinic acid reached at the end of fermentation were 95% and 0.46 g (l h)⁻¹, respectively. These values were higher than those obtained using nontreated whey alone [93% and 0.24 g (l h)⁻¹ for 20 g l⁻¹ whey]. Continuous fermentation of A. succiniciproducens at an optimal dilution rate resulted in the production of succinic acid with high productivity [1.35 g (l h)⁻¹], high conversion yield (93%), and higher ratio of succinic acid to acetic acid (5.1:1) from nontreated whey. Received: 23 July 1999 / Received revision: 17 November 1999 / Accepted: 24 December 1999     

Optimization of culture medium for the continuous cultivation of the microalga Haematococcus pluvialis

The freshwater microalga Haematococcus pluvialis is one of the best microbial sources of the carotenoid astaxanthin, but this microalga shows low growth rates and low final cell densities when cultured with traditional media. A single-variable optimization strategy was applied to 18 components of the culture media in order to maximize the productivity of vegetative cells of H. pluvialis in semicontinuous culture. The steady-state cell density obtained with the optimized culture medium at a daily volume exchange of 20% was 3.77 · 10⁵ cells ml⁻¹, three times higher than the cell density obtained with Bold basal medium and with the initial formulation. The formulation of the optimal Haematococcus medium (OHM) is (in g l⁻¹) KNO₃ 0.41, Na₂HPO₄ 0.03, MgSO₄ · 7H₂O 0.246, CaCl₂ · 2H₂O 0.11, (in mg l⁻¹) Fe(III)citrate · H₂O 2.62, CoCl₂ · 6H₂O 0.011, CuSO₄ · 5H₂O 0.012, Cr₂O₃ 0.075, MnCl₂ · 4H₂O 0.98, Na₂MoO₄ · 2H₂O 0.12, SeO₂ 0.005 and (in μg l⁻¹]) biotin 25, thiamine 17.5 and B₁₂ 15. Vanadium, iodine, boron and zinc were demonstrated to be non-essential for the growth of H. pluvialis. Higher steady-state cell densities were obtained by a three-fold increase of all nutrient concentrations but a high nitrate concentration remained in the culture medium under such conditions. The high cell productivities obtained with the new optimized medium can serve as a basis for the development of a two-stage technology for the production of astaxanthin from H. pluvialis. Received: 10 September 1999 / Received revision: 2 December 1999 / Accepted: 3 December 1999     

The effect of endurance exercise at moderate altitude on serum lipid peroxidation and antioxidative functions in humans

We investigated the effect of training and racing at moderate altitude (MA) on oxidative stress by assessment of serum diene conjugation (DC) and serum antioxidant potential (TRAP). Nine male top level skiers were studied during a national race (20–30 km) at sea level (SL). Thereafter, the athletes trained for 2 weeks at MA, after which they participated in a 20–30 km race at MA. Venous blood samples were taken before and after the race. The DC, indicating early events of lipid peroxi dation, did not change during the race at SL (16 850 vs 15 900 ΔAbsorbance · l⁻¹) or at MA (19 870 vs. 20 630 ΔAbs · l⁻¹). At MA serum DC was higher than at SL both before (25%) and after (30%) the race, the postrace difference being statistically significant (P < 0.05). The TRAP increased during the race at MA (from 1387 to 1943 μmol · 1⁻¹, P  =  0.016), but not at SL (1713 vs 1582 μmol · l⁻¹). These observations would suggest that the level of oxidative stress might be greater during living, training and racing at MA (higher DC levels). Increased TRAP during the race at MA may indicate that the physiological adaptation to extreme acute oxidative stress was altered. The physiological significance of this observation remains to be investigated. Accepted: 18 October 1996     

Inhibition of Clostridium butyricum by 1,3-propanediol and diols during glycerol fermentation

1,3-Propanediol inhibition during glycerol fermentation to 1,3-propanediol by Clostridium butyricum CNCM 1211 has been studied. The initial concentration of the 1,3-propanediol affected the growth of the bacterium more than the glycerol fermentation. μ _max was inversely proportional to the initial concentration of 1,3-propanediol (0–65 g l⁻¹). For glycerol at 20 g l⁻¹, the growth and fermentation were completely stopped at an initial 1,3-propanediol concentration of 65 g l⁻¹. However, for an initial 1,3-propanediol concentration of 50 g l⁻¹ and glycerol at 70 g l⁻¹, the final concentration (initial and produced) of 1,3-propanediol reached 83.7 g l⁻¹(1.1 M), with complete consumption of the glycerol. Therefore, during the fermentation, the strain tolerated a 1,3-propanediol concentration higher than the initial inhibitory concentration (65 g l⁻¹). The addition of 1,2-propanediol or 2,3-butanediol (50 g l⁻¹) in the presence of glycerol (50–100 g l⁻¹), showed that 2-diols reduced the μ _max in a similar way to 1,3-propanediol. The measurement of the osmotic pressure of glycerol solutions, diols and diol/glycerol mixtures did not indicate any differences between these compounds. The hypothesis of diol inhibition was discussed. Taking into account the strain tolerance of highly concentrated 1,3-propanediol during fermentation, the fermentation processes for optimising production were considered. Received: 15 November 1999 / Revision received: 1 February 2000 / Accepted: 4 February 2000