Aerobic Biotransformation of N-Nitrosodimethylamine and N-Nitrodimethylamine by Benzene-, Butane-, Methane-, Propane-, and Toluene-Fed Cultures

N-Nitrosodimethylamine (NDMA) is an emerging contaminant of concern. N-nitrodimethylamine (DMNA) is a structural analog to NDMA. NDMA and DMNA have been found in drinking water, groundwater, and other media and are of concern due their toxicity. The authors evaluated biotransformation of NDMA and DMNA by cultures enriched from contaminated groundwater growing on benzene, butane, methane, propane, or toluene. Maximum specific growth rates of enriched cultures on butane (μ_max = 1.1 h^?1) and propane (μ_max = 0.65 h^?1) were 1 to 2 orders of magnitude higher than those presented in the literature. Growth rates of mixed cultures grown on benzene (μ_max = 1.3 h^?1), methane (μ_max = 0.09 h^?1), and toluene (μ_max = 0.99 h^?1) in these studies were similar to those presented in the literature. NDMA biotransformation rates for methane oxidizers (υ_max = 1.4 ng min^?1 mg^?1) and toluene oxidizers (υ_max = 2.3 ng min^?1 mg^?1) were comparable to those presented in the literature, whereas the biotransformation rate for propane oxidizers (υ_max = 0.37 ng min^?1 mg^?1) was lower. NDMA biotransformation rates for benzene oxidizers (υ_max = 1.02 ng min^?1 mg^?1) and butane oxidizers (υ_max = 1.2 ng min^?1 mg^?1) were comparable to those reported for other primary substrates. These studies showed that DMNA biotransformation rates for benzene (υ_max = 0.79 ng min^?1 mg^?1), butane (υ_max = 1.0 ng min^?1 mg^?1), methane (υ_max = 2.1 ng min^?1 mg^?1), propane (υ_max = 1.46 ng min^?1 mg^?1), and toluene (υ_max = 0.52 ng min^?1 mg^?1) oxidizers were all comparable. These studies highlight potential bioremediation methods for NDMA and DMNA in contaminated groundwater.     

The energetics of the common mole rat Cryptomyś, a subterranean eusocial rodent from Zambia

Body temperature, oxygen consumption, respiratory and cardiac activity and body mass loss were measured in six females and four males of the subterranean Zambian mole rat Cryptomys sp. (karyotype 2 n=68), at ambient temperatures between 10 and 35°C. Mean body temperature ranged between 36.1 and 33.2°C at ambient temperatures of 32.5–10°C and was lower in females (32.7°C) than in males (33.9°C) at ambient temperatures of 10°C but dit not differ at thermoneutrality (32.5°C). Except for body temperature, mean values of all other parameters were lowest at thermoneutrality. Mean basal oxygen consumption of 0.76 ml O₂·g^-1· h^-1 was significantly lower than expected according to allometric equations and was different in the two sexes (females: 0.82 ml O₂·g^-1·h^-1, males: 0.68 ml O₂·g¹·h^-1) but was not correlated with body mass within the sexes. Basal respiratory rate of 74·min^-1 (females: 66·min¹, males: 87·min^-1) and basal heart rate of 200·min^-1 (females: 190·min^-1, males: 216·min^-1) were almost 30% lower than predicted, and the calculated thermal conductance of 0.144 ml O₂·g^-1·h¹·°C^-1 (females; 0.153 ml O₂·g^-1·h^-1·°C^-1, males: 0.131 ml O₂·g^-1·h^-1·°C^-1) was significantly higher than expected. The body mass loss in resting mole rats of 8.6–14.1%·day^-1 was high and in percentages higher in females than in males. Oxygen consumption and body mass loss as well as respiratory and cardiac activity increased at higher and lower than thermoneutral temperatures. The regulatory increase in O₂ demand below thermoneutrality was mainly saturated by increasing tidal volume but at ambient temperatures <15°C, the additional oxygen consumption was regulated by increasing frequency with slightly decreasing tidal volume. Likewise, the additional blood transport capacity was mainly effected by an increasing stroke volume while there was only a slight increase of heart frequency. In an additional field study, temperatures and humidity in different burrow systems have been determined and compared to environmental conditions above ground. Constant temperatures in the nest area 70 cm below ground between 26 and 28°C facilitate low resting metabolic rates, and high relative humidity minimizes evaporative water loss but both cause thermoregulatory problems such as overheating while digging. In 13–16 cm deep foraging tunnels, temperature fluctuations were higher following the above ground fluctuations with a time lag. Dominant breeding females had remarkably low body temperatures of 31.5–32.3°C at ambient temperatures of 20°C and appeared to be torpid. This reversible hypothermy and particular social structure involving division of labour are discussed as a strategy reducing energy expenditure in these eusocial subterranean animals with high foraging costs.Abbreviations BMR basal metabolic rate - br breath - C thermal conductance - HR neart rate - LD light/dark - M _b body mass - MR metabolic rate - OP oxygen pulse - PCO₂ partial pressure of carbon dioxide - PO₂ partial pressure of oxygen - RMR resting metabolic rate - RR respiratory rate - T _a ambient temperature - T _b body temperature - TNZ thermal neural zone - O₂ oxygen consumption     

A short cut procedure for the design and monitoring of continuous flow sedimentation or thickening tanks

A Short cut graphical procedure has been developed analogous to stepwise for the design of continuous flow sedimentation or thickening tanks.In this technique, several computer programs have been set up in order to reduce the data input, necessary for performing all intermediate calculations by computer. The data describing the settling of particles and movement of the particle-liquid interface as a function of time and operating conditions are the only data required. The method predicts the time required to attain the prescribed underflow concentration, the rate of hindered settling subsidence, the area required for clarification, the thickener area and dimensions. The proposed method has been applied to illustrate the effect of different chemical treatment doses on a typical industrial effluent from the manufacture of starch and byproducts from American yellow corn.List of Symbols A1 cm First falling zone line intercept - A2 cm Settling zone curve intercept - A3 cm Compression zone line intercept - A4 cm Angle bisector intercept - A5 cm Tangent interception at the compression point - ACL m² Minimum clarification area - ALPHA() Angle between line 1 and line 2, radians - ATH m² Minimum thickening area - ATH1 m² Area of each individual tank - B1 cm · min^–1 First falling zone line slope - B2 Settling zone curve power - B3 cm · min^–1 Compression zone line slope - B4 cm · min^–1 Angle bisector slope - B5 cm · min^–1 Tangent slope at the compression point - BT m Approximate width of the tank - BT1 m Actual width of the tank - CC Conversion criteria - CO mg/dm³ Initial solid concentration - CU mg/dm³ Underflow solid concentration - D m Basin depth - DIAM m Diameter of circular tank - DMIN m Minimum allowable liquid depth - DT h Minimum allowable detention time - DT1 h Calculated detention time - HT cm Subsiding particle-liquid interface height - HT1 min Subsiding particle-liquid interface coordinate for line 1 and line 2 intersection - HTR cm Subsiding particle-liquid interface coordinate for compression point - L m Approximate length of the tank - L1 m Actual length of the tank - LMAX m Maximum allowable tank length - LMIN m Minimum allowable tank length - NI Number of iterations - NO Number of tanks - PI Const. - Q m³/h Wastewater flowrate - SL m³/(m² · d) Surface loading - T1 Tan() - T3 Tan (/2) - TM min Time of measuring subsiding particle-liquid interface - TM1 min Time coordinate for line 1 and line 2 intersection - TML min Lower limit of the root - TMR min Time coordinate for compression point - TMU min Upper limit of the root - TU min Time required to attain underflow concentration - ZO cm Initial height of sludge - ZU cm Settled height of sludge interface - FI m Inert depth (typically taken as 1 m)     

Metabolic rates in harvestmen (Arachnida, Opiliones): the influence of running activity

Abstract. Metabolic rates of adult Lophopilio palpinalis (Herbst, 1799) (Arachnida, Opiliones, Phalangioidea) and Paranemastoma quadripunctatum (Perty, 1833) (Arachnida, Opiliones, Troguloidea) are measured during rest and activity. Carbon dioxide release during rest is continuous in both species. Mean values at 20 °C are 4.2 µL min⁻¹ g⁻¹ for the males of P. quadripunctatum, 4.1 µL min⁻¹ g⁻¹ for the males of L. palpinalis and 4.7 µL min⁻¹ g⁻¹ for the females of L. palpinalis, thus being significantly higher in the egg-producing females. In L. palpinalis, respiratory quotient at rest is 0.84. Spontaneous walking activity with speeds of 15–30 cm min⁻¹ raises the metabolic rate by up to three-fold in both species. Lophopilio palpinalis is made to undertake constant running on a treadmill with speeds of 60, 72 and 96 cm min⁻¹. Enforced activity causes the animals to raise their metabolic rates by up to five-fold above resting rates. Animals reach a steady state of CO₂ release on the treadmill and show a fast t_1/2 on-response, indicating aerobic exercise. The minimum cost of locomotion is determined to be 2.5 × 10⁻³ J cm⁻¹ g⁻¹, thus fitting the predicted values for terrestrial locomotion.     

Fatty-acid synthesis in chloroplasts from mustard (Sinapis alba L.) cotyledons: formation of acetyl coenzyme A by intraplastid glycolytic enzymes and a pyruvate dehydrogenase complex

Chloroplasts from the cotyledons of mustard (Sinapis alba L.) seedlings were isolated on Percoll gradients, and showed a high degree of intactness (92%) and purity as judged by electron microscopy and marker-enzyme analysis (cytoplasmic contamination lower than 0.4% on a protein basis). The chloroplasts synthesized longchain fatty acids from both precursors [1-¹⁴C] acetate and [2-¹⁴C]pyruvate; maximum incorporation rates were 96 nmol·(mg Chl)^-1·h^-1 for acetate and 213 nmol·(mg Chl)^-1·h^-1 for pyruvate. Acetyl-CoA-producing enzymatic activities, namely acetyl-CoA synthetase (EC 6.2.1.1.) and a pyruvate dehydrogenase complex, showed specific activities of 14.8 nmol·(mg protein)^-1·min^-1 and 18.2 nmol·(mg protein)^-1·min^-1, respectively. The glycolytic enzymes phosphoglyceromutase (EC 2.7.5.3) phosphopyruvate hydratase (EC 4.2.1.11) and pyruvate kinase (EC 2.7.1.40) were all found to be components of these chloroplasts, thus indicating a possible pathway for intraplastid acetyl-CoA formation.Abbreviations ACS acetyl coenzyme A synthetase - Chl chlorophyll - DTE 1,4-dithioerythritol - PDHC pyruvate dehydrogenase complex - 3-PGA 3-phosphoglyceric acid     

Bacterivory of metazooplankton, ciliates and flagellates in a newly flooded reservoir

Bacterial consumption by metazoan zooplankton and phagotrophic protists was measured in situ during the period of thermal stratification in the epilimnion (1 m) and metalimnion (7 m) of a newly flooded reservoir (Sep reservoir, France). The mean bacterial consumption was 2.53 x 10⁶ bacterial l^-1 h^-1 at 1m and 0.97 x 10⁶ bacteria l^-1 h^-1 at 7m. The main consumers over the whole study period were the cladocerans Daphnia longispina and Ceriodaphnia quadrangula, accounting on average for 72% of the potential total predation of bacteria at 1 m and 56% at m, especially during the months of May-June and August. Heterotrophic nanoflagellates (HNF), which accounted for 12% estimated total predation of bacteria at 1 m and 13% at 7m, only exerted a limited predation, mainly by a Monas-type cell. Ciliates, dominated in terms of abundance by Pelagohalteria viridis, accounted for 4% of total predation in the epilimnion (0.00-0.42 x 10⁶ bacteria l^-1 h^-1). In a newly flooded reservoir, metazoan zooplankton appear to be the main consumers of bacteria. Predation of ciliates and HNF by zooplanktonic crustaceans could account for the low contribution of components of the microbial loop to bacterial consumption.      

Continuous ethanol production using induced yeast aggregates

Summary The induction of yeast cell aggregates in a column reactor was initiated by packing yeast cell paste of Saccharomyces uvarum into the column, and then YMP broth was fed into the column from the bottom at a linear flow rate of 2.5 cm/h. Thereafter, yeast cells aggregated in the column within 48 h without a supply of oxygen. When this yeast aggregate column reactor was used for continuous ethanol production, a final ethanol concentration of 10.8% (w/v) was obtained from 23% (w/v) of glucose in a YMP broth with a dilution rate of 0.05 h^-1, and 4.9% (w/v) was obtained from 10% (w/v) of glucose with a dilution rate of 0.6 h^-1. The theoretical yield was above 97% in both cases. The ethanol production rates were 13 g¹ h^-1 l^-1 and 90 g¹ h^-1 l^-1 for producing 10.8% (w/v) and 4.9% (w/v) of ethanol respectively. This column reactor was maintained at a steady state for more than one month.     

Photosynthetic activity and respiration in an equatorial African soda lake

SUMMARY. Photosynthetic activity and respiration in Lake Sonachi (Kenya), a meromictic soda lake lying in a volcanic crater, were measured through diel cycles during a 15-month period. A pattern of thermal stratification in the morning and mixing in the afternoon and night occurred in the mixolimnion. Diel variations in dissolved oxygen at 50 cm were 2.2–7.5 mgO₂ 1^-11% of the incident photosynthetically available irradiance (PAR) reached a depth of 1.3–2.4 m and, as a consequence, the steepest thermal gradients and highest oxygen concentrations occurred in the top 1–2 m. Vertical profiles of dissolved oxygen were used in three ways to estimate photosynthetic and respiration rates. Changes in dissolved oxygen at the depth of maximal photosynthesis (c. 50 cm) during mid-morning were corrected for vertical diffusion to determine net free water oxygen increases of 70-1800 mg O₂ m^-3 h^-1 Variations in areal oxygen content at successive intervals throughout the day and night were corrected for air-water oxygen exchange to calculate net free water oxygen change per h. Maximal rates of increase (550–4850 mg O₂ m^-2 h^-1) usually occurred in late morning or early afternoon; maximal rates of decrease (440–2600 mg O₂ m^-2 h^-1) were common at sunset. The correction for air-water exchange was usually small because of the low wind speeds and the nearness to saturation of the surface water. Summation of daytime and night-time rates of oxygen change provide estimates of net (-3.4–12 gO₂ m ^-2) and gross (-0.7-18.7 g O₂ m^-2) daily photosynthesis and respiration (0.8-7.2 gO₂ m^-2). Photosynthetic rates of bottled samples ranged from 150 to 870 mgO₂m ^-2h ^-1 and 1.4 to 6.8 g O₂, m^-2 day ^-1The efficiency of utilization of PAR incident on the lake surface varied from 1.0 to 7.2 mmol O₂E^-1 periods with higher irradiance typically had lower efficiencies. Free water estimates of photosynthesis usually exceeded the rates measured in bottles. For example, net, free water changes per hour were 1.2–10 times higher than gross areal rates per hour in bottles. Photosynthetic activity in Lake Sonachi in 1973 and 1974 was modest when compared to other tropical African soda lakes.     

Cell wall strength of Hansenula polymorpha in continuous cultures in relation to the recovery of methanol oxidase (MOX)

Summary The changes in cell wall strength of Hansenula polymorpha have been investigated in continuous cultures with respect to the recovery of methanol oxidase (MOX). Cultures grown on several substrate mixtures that enable induction of MOX have been compared with cultures grown on methanol as the sole inducer. The effects of dilution rate (D) on lysis properties have been studied. The cell wall strength was consistently influenced by growth media and D. Media containing glycerol/methanol showed the slowest lysis kinetics, with a large fraction of non-degradable cell wall material. In continuous cultures grown on a mixture of glucose and methanol both the resistance to zymolyase and the mean cell wall thickness increased at D<0.1 h^–1. The yield of MOX by zymolyase lysis is reproducible and up to 100% higher than that of the standard ultrasonic treatment. The lysis kinetics indicated that zymolyase punctures the cell wall; since the release rate of MOX is lower than that of protein, the cell contents will leak through. At D-values>0.2 h^–1, both protein and MOX release rates increase, reflecting a change in lysis mechanism due to the increased fraction of thin daughter cells. Kinetic analysis of zymolyase lysis using both physical and enzymatic methods provides information for achieving optimal recovery of MOX.Abbreviations and symbols C _MOX MOX activity [MOX units·g X^–1] - D dilution rate [h^–1] - MOX methanol oxidase - k_c decay rate constant of A 610 nm [min^–1] - k_d decay constant of MOX activity [min^–1] - k_dis dissociation rate constant [min^–1] - k_MOX release rate constant of MOX activity [min^–1] - k_p release rate constant of protein [min^–1] - R recovery efficiency of enzyme [-] - St stability of enzyme [-]     

Water loss from cut grass with special reference to hay-making

Water loss from cut grass was studied to determine factors limiting the drying process. An apparatus, used to measure water loss at 28±1°C from blotting paper and from leaves and stem internodes of cocksfoot, consisted of four channels in which air speed was controlled at 25–80 cm s^-1 and relative humidity at 7–68%. The maximum rate of water loss from wet blotting paper was 10500 mg water dm^-2 h^-1 but from leaves and stem internodes supplied with water it was less than 250 mg dm^-2 h^-1. The rate of loss from both plant specimens and blotting paper was linearly related to the vapour pressure differences between the specimen and the surrounding air but was not increased when air speed was changed from 40 to 80 cm s^-1. Grass specimens supplied with water had lower rates of water loss than wet blotting paper because of tissue resistances which were calculated for (a) untreated leaf and stem specimens, (b) rubbed leaves, (c) cut leaves, (d) leaves exposed to steam for 60 s. Treatments (b)-(d) greatly reduced tissue resistances. The rates of drying of leaves and stem internodes not supplied with water changed only slightly in response to faster air speeds but were significantly increased by treatments (b), (c), (c_s) (split stems), (d) and (e) (exposure to petroleum vapour for 60 s). The most effective treatments trebled the drying rates of leaves and increased the drying rates of stem internodes by 10 times. Reductions in relative humidity had little effect on drying rate following treatments (a), (b), (c) and (d), but when treatments (c_s) and (e) were given, additional significant increases in drying rates were obtained when the relative humidity was reduced. Grass specimens given the most effective treatments and dried under the most favourable conditions did not utilize the full drying capacity of the environment, for the rates of water loss from these specimens were at least three times lower than those from wet blotting paper. The results indicate that high rates of drying could be achieved at 28 ^oC or similar temperatures if practical treatments were developed to remove or greatly reduce the high resistance to water loss in cut grass.     

Relationships between metabolic rate, muscle electromyograms and swim performance of adult chinook salmon

Oxygen consumption rates of adult spring chinook salmon Oncorhynchus tshawytscha increased with swim speed and, depending on temperature and fish mass, ranged from 609 mg O₂ h^?1 at 30 cm s^?1 (c. 0·5 BL s^?1) to 3347 mg O₂ h^?1 at 170 cm s^?1 (c. 2·3 BL s^?1). Corrected for fish mass, these values ranged from 122 to 670 mg O₂ kg^?1 h^?1, and were similar to other Oncorhynchus species. At all temperatures (8, 12·5 and 17° C), maximum oxygen consumption values levelled off and slightly declined with increasing swim speed >170 cm s^?1, and a third‐order polynomial regression model fitted the data best. The upper critical swim speed (U_crit) of fish tested at two laboratories averaged 155 cm s^?1 (2·1 BL s^?1), but U_crit of fish tested at the Pacific Northwest National Laboratory were significantly higher (mean 165 cm s^?1) than those from fish tested at the Columbia River Research Laboratory (mean 140 cm s^?1). Swim trials using fish that had electromyogram (EMG) transmitters implanted in them suggested that at a swim speed of c. 135 cm s^?1, red muscle EMG pulse rates slowed and white muscle EMG pulse rates increased. Although there was significant variation between individual fish, this swim speed was c. 80% of the U_crit for the fish used in the EMG trials (mean U_crit 168·2 cm s^?1). Bioenergetic modelling of the upstream migration of adult chinook salmon should consider incorporating an anaerobic fraction of the energy budget when swim speeds are ≥80% of the U_crit.     

Impact of natural metazooplankton assemblage on planktonic microbial communities in a newly flooded reservoir

The grazing impact of a natural assemblage of metazoan zooplankton on pigmented flagellates (PF), heterotrophic nanoflagellates (HNF), ciliates, and non-flagellate algae and microcyanobacteria (NFAM) was measured in situ during the period of thermal stratification in a newly flooded reservoir (Reservoir de la Sep, France). Experiments were conducted with diffusion chambers in the meta- and epilimnion over a period of 7 h. The mean mortalities of PF in the epi- and metalimnion (0.08 0.02 and 0.06 ± 0.03 h^-1, respectively), of HNF (0.04 ± 0.02 and 0.05 ± 0.02 h^-1) and ciliates (0.09 ± 0.04 and 0.11 ± 0.04 h^-1) demonstrate the impact of the metazoan zooplankton, and particularly of the rotifer Asplanchna priodonta, on the components of the microbial loop. The mortality of NFAM, accounting for 14 and 18% of total mortality, remained low throughout the study. The taxa with the highest mortality were pigmented flagellates of 4-19 m, HNF, and small-sized ciliates such as Halteria sp. (0.10 ± 0.02 h^-1 at 1 m and 0.30 ± 0.38 h^-1 at 7 m) and Urotricha furcata (0.11 ± 0.05 h^-1 at 1 m and 0.12 ± 0.06 h^-1 at 7 m). Large-sized ciliates (Paradileptus elephantinus) and sessile ciliates (Suctorida, Vorticella sp.) had a very low mortality (>0.04 h^-1). After reservoir flooding, the organisms in the microbial trophic loop, favoured by the high quantities of allochthonous organic matter, are subject to a higher mortality than the phytoplankton.      

Effect of oxygen transfer rate on the composition of the pectolytic enzyme complex of Aspergillus niger

Optimal agitation and aeration conditions [assuring O₂ transfer rates (OTR) from 12 to 179 mmol L^?1 h^?1] were determined for pectin lyase (PL) synthesis of an Aspergillus niger strain. Components of the pectolytic enzyme complex were also investigated in order to determine whether their O₂ demand is identical with or different from that of pectin lyase. Should the latter be the case, a possibility would be given to produce enzyme complexes of different agitation and aeration conditions. According to our results, mycelium yield of Aspergillus niger attained a maximum at an OTR of 100 mmol L^?1 h^?1. The yields of the various pectolytic enzymes reached maxima at different OTRs. Pectin lyase production was the highest (0.555 µmol min^?1 mL^?1) at an OTR of 60 mmol L^?1 h^?1. Endopolygalacturonase (PG) production showed a maximum at the OTR of 49 mmol L^?1 h^?1 with a second peak at 100?135 mmol O₂ L^?1 h^?1. Pectin esterase (PE) synthesis showed a maximum at on OTR of 12?14 mmol L^?1 h^?1, while both apple juice clarifying and macerating activities gave two maxima at 14 and 60 mmol L^?1 h^?1 due to the optima of PE and endo-PG. Macerating activity showed a high value at OTR optimal for PL production as well.     

Isolation of human fibrinogen by axial and radial flow chromatography from Nitschmann fraction I

An axial column (3×2.6 cm) and a radial flow column (3.5×5 cm) packed with DEAE Sepharose Fast Flow media had been evaluated for the separation of human fibrinogen. Nitschmann fraction I dissolved in buffered saline (0.015 M NaCl buffered with 0.06 M Tris/HCl to pH 7.5) was the starting material. Under radial flow conditions, sample flow up to 15 ml min^–1 (i.e., 18 bed volumes h^–1) was achieved. The operating pressures were below 0.2 MPa, even though the elution velocity was 30 ml min^–1 (i.e., 36 bed volumes h^–1).     

Selection of an adhesive phenotype of Streptococcus salivarius subsp. thermophilus for use in fixed-bed reactors

 Streptococcus salivarius subsp. thermophilus was cultivated in a chemostat in order to obtain an adhesive phenotype of this strain. When the system was operated at low dilution rates (D<0.2 h^-1) for about 4 weeks, the strain formed a visible film on the surface of the culture vessel. The biofilm cells were not washed out even when dilution rates were increased (D=6.9 h^-1), and this resulted in a high biomass productivity (P=4.1 g l^-1h^-1). On the other hand, when the culture was grown at dilution rates faster than 0.2 h^-1, only the free suspended cells were present in the culture broth, and were washed out at velocities of about 1.0 h^-1. The biomass productivity was consequently lower (P=1.33 g l^-1h^-1) than in the previous case. The selected adhesive phenotype was grown on different glass beads and the possibility of lactate fermentation in a continuous and semicontinuous mode was demonstrated. Received: 16 August 1995/Received revision: 18 March 1996/Accepted: 25 March 1996     

Phloem transport of 14C-labelled assimilates in Ricinus

Summary Exudate can be obtained from incisions made in the bark of the stem of actively growing Ricinus plants. ¹⁴C-labelled assimilates from a fed leaf are rapidly detected in the exudate. This movement was both acropetal and basipetal from the fed leaf, at rates of over 100 cm h^-1. Estimated rates within intact plants were 80–84 cm h^-1.In contrast with xylem sap obtained from the same plant, the exudate obtained had an alkaline pH (8.2), a high dry matter content (10–12.5%), high sugar content (8–10%) which was predominantly sucrose; high potassium content (60–80 mM) and low calcium content (0.5–1.0 mM).It is concluded, on the basis of the present evidence, that the exudate is a true sample of the sieve tube sap undergoing translocation.     

Splash dispersal of Coniothyrium minitans in the glasshouse

Coniothyrium minitans, a mycoparasite with biocontrol activity against Sclerotinia sclerotiorum, was found to disperse during glasshouse trials where overhead irrigation was used. Consequently, the role of water splash in dispersal of C. minitans was investigated using soil-incorporated inoculum and a range of irrigation regimes found to occur in the glasshouse. The resulting inoculum deposition over horizontal distances up to 2 m was measured. Using drops < 6 mm diameter at 680 mm h^-1, C. minitans was splash-dispersed at least 2.0 m, whereas with drops > 6 mm diameter at 30 mm h^-1 it was dispersed to only 1.75 m. Irrigation with droplets < 1mm diameter at 49 mm h^-1 failed to disperse inoculum beyond 0.5 m. The dispersal gradient produced by drops < 6 mm diameter at 680 mm h^-1 was best described mathematically by the power function, whereas irrigation with drops > 6 mm diameter at 30 mm h^- resulted in a gradient described well by power or exponential functions. The latter regime produced a significantly steeper gradient than irrigation with drops < 6 mm diameter at 680 mm h^-1. C. minitans was isolated using an Andersen air sampler at concentrations of 2839 cfu m^-3 or 22 cfu m^-3 during irrigation with drops < 6 mm diameter at 680 mm h^-1 or > 6 mm diameter at 30 mm h^-1, respectively. After irrigation, deposition of C. minitans-canying aerosol particles declined exponentially and distance from source had no effect on the amount of inoculum isolated. Conidia of C. minitans, splash-dispersed by irrigation with drops < 6 mm diameter at 680 mm h^-1 were able to infect sclerotia of S. sclerotiorum such that almost all sclerotia at 0.5 m from the inoculum source, and c. 50% of those at 2.0 m, became infected with the mycoparasite.     

Dark respiration of the stipe of Ecklonia cava (Laminariales, Phaeophyta) in relation to temperature

Sporophytes of Ecklonia cava Kjellman (Laminariales, Phaeophyta) with a stipe length of 22–102 cm were collected at 6–9 m depth in Nabeta Bay, Shimoda, central Japan by scuba diving in February (winter) and in August (summer) 1998. Dark respiration of the intact stipe of E. cava was measured at various water temperatures ranging from 15 to 27.5°C in winter and 15–30°C in summer in a closed system by using a dissolved oxygen meter. The stipe respiration was compared on whole stipe, length, surface area, volume, wet weight and dry weight bases. On each basis, the stipe respiration always increased with a rise in water temperature within the temperature range investigated. The stipes showed similar respiration rates on each basis of length, surface area, volume, wet weight and dry weight at each temperature, irrespective of the stipe length. The mean respiration rates in winter (at 15–27.5°C) were: length, 16.7–32.5 μL O₂ cm^?1 h^?1; surface area, 3.2–6.2 μL O₂ cm^?2 h^?1; volume, 7.6–15.0 μL O₂ cm^?3 h^?1; wet weight, 6.2–12.2 μL O₂ g (wet weight)^?1 h^?1; and dry weight, 43.8–88.0 μL O₂ g (dry weight)^?1 h^?1. Those for summer (at 15–30°C) were: length, 17.1–32.0 μL O₂ cm^?1 h^?1; surface area, 3.6–6.8 μL O₂ cm^?2 h^?1; volume, 9.7–18.7 μL O₂ cm^?3 h^?1; wet weight, 7.6–14.6 μL O₂ g (wet weight)^?1 h^?1; and dry weight, 49.4–95.8 μL O₂ g (dry weight)^?1 h^?1. This is the first report of the intact stipe respiration of E. cava at various temperatures.     

Aerobic fitness and performance in elite female futsal players

Despite its growing popularity, few studies have investigated specific physiological demands for elite female futsal. The aim of this study was to determine aerobic fitness in elite female futsal players using laboratory and field testing. Fourteen female futsal players from the Venezuelan National team (age =21.2±4.0 years; body mass =58.6±5.6 kg; height =161±5.0 cm) performed a progressive maximal treadmill test under laboratory conditions. Players also performed a progressive intermittent futsal-specific field test for endurance, the Futsal Intermittent Endurance Test (FIET), until volitional fatigue. Outcome variables were exercise heart rate (HR), VO₂, post-exercise blood lactate concentrations ([La]b) and running speeds (km · h^-1). During the treadmill test, VO₂max, maximal aerobic speed (MAS), HR and peak [La]b were 45.3±5.6 ml · kg^-1 · min^-1, 12.5±1.77 km · h^-1, 197±8 beats · min^-1 and 11.3±1.4 mmol · l^-1, respectively. The FIET total distance, peak running velocity, peak HR and [La]b were 1125.0±121.0 m, 15.2±0.5 km · h^-1, 199±8 beats · min^-1 and 12.5±2.2 mmol · l^-1, respectively. The FIET distance and peak speed were strongly associated (r= 0.85-87, p < 0.0001) with VO₂max and MAS, respectively. Peak HR and [La]b were not significantly different between tests. Elite female futsal players possess moderate aerobic fitness. Furthermore, the FIET can be considered as a valid field test to determine aerobic fitness in elite level female futsal players.     

Continuous culture of the hyperthermophilic archaeum Pyrococcus furiosus

Summary A system for continuous culture of the hyperthermophilic archaeum Pyrococcus furiosus in the absence of elemental sulphur has been developed. An all-glass gas-lift bioreactor was used to provide high mass transfer at low shear forces, whilst eliminating the potential for corrosion. Steady-state cell densities of P. furiosus were found to increase with higher inert gas flow rates, reaching a maximum in this system with 0.5 vol. vol^–1 min^–1 of nitrogen (N₂). N₂ permitted higher cell densities than the other inert gases tested (argon, helium and sulphur hexafluoride) under equivalent conditions. At 0.5 vol. vol^–1 min^–1 of N₂ a cell density in excess of 3 × 10⁹ ml^–1 could be maintained indefinitely at a dilution rate of 0.2 h^–1. Higher dilution rates gave progressively lower steady-state cell densities. Teh biomass production was maximal, however, at a dilution rate of 0.4 h^–1. At this dilution rate the bioreactor was able to generate more than 1.5 g wet weight of cells h^–1 l^–1 culture volume.Correspondence to: N. Raven