ADSORPTION OF FULVIC ACID ON ALGAL SURFACES AND ITS EFFECT ON CARBON UPTAKE

Adsorption of Suwannee River fulvic acid (SRFA) to algal surfaces of three green algae was studied at environmentally relevant pH values (4 –7) and SRFA concentrations (5–100 mg·L ^{− 1}). The influence of adsorbed SRFA on carbon uptake of Scenedesmus subspicatus Chodat was also examined. Although no adsorption was observed at neutral pH values (pH 6 and 7), at pH 4 up to 31 mg SRFA·m ^{− 2} and at pH 5 up to 4 mg SRFA·m ^{− 2} was adsorbed to the algal surfaces. Electrophoretic mobility measurements of S. subspicatus demonstrated an increase in the negative surface charge of the alga in the presence of SRFA at pH 4. The adsorbed SRFA also influenced ¹⁴C uptake in S. subspicatus; in this case, enhanced carbon uptake could be related to the amount of adsorbed SRFA. The binding of humic substances by algal surfaces was interpreted as the result of hydrogen bonding and hydrophobic interactions.     

Seasonal changes in some blood chemistry parameters and in relative liver and gonad weights of pike (Esox lucius L.) from the River Danube

Samples from a natural population of pike (Esox lucius L.) from the River Danube were used in a 12-month study to determine seasonal variations in biochemical parameters of pike blood sera, hepatosomatic index (HSI) and gonadosomatic index (GSI). The ranges of enzyme activities for sample means were: aspartate aminotransferase (ASAT) 252.0–583.8 U 1⁻¹, alanine aminotransferase (ALAT) 4.9–11 -2 U1 and alkaline phosphatase (AP) 39.5–91.8 U1⁻¹. The ranges of other parameters analysed in serum were total protein 27.7–40.1 g 1 ¹, urea 0.57–l.52 mmol 1 ¹ and creatinine 21.2–118.6 μmol 1 ¹. The range of sample means for HSI and GSI were 1.28–4.16 and 0.07–20.2 respectively. Temperature ranged from 4.5 to 23.5°C. The activity of serum AP was positively correlated to water temperature in males only, while urea and creatinine showed a positive correlation to water temperature in individuals of both sexes. GSI was correlated significantly with HSI in females. Total protein reached the lowest values during the spawning period, while creatinine levels depended on both the sex and season.     

Embryonic and larval development of brown trout, Salmo trutta L.: exposure to trace metal mixtures in soft water

Freshly fertilized ova of brown trout, Salmo trutta L., were exposed to all possible mixtures of Al (6000 nmol 1¹), Cu (80 nmol 1⁻¹), Pb (50 nmol 1⁻¹) and Zn (300 nmol 1 ¹). In a separate experiment, newly hatched brown trout yolk-sac fry were exposed to Mn (1500 nmol 1⁻¹), Fe (2500 nmol 1 ¹), Ni (200 nmol 1⁻¹) or Cd (4 nmol 1 ¹), separately, and in mixtures with either Al or Cu. Both experiments were conducted in flowing, artificial softwater media nominally at pH 5.6 [Ca] 20 μmol 1 ¹ and 10° C.
Mortalities were high in fry subjected to treatments which contained both Al and Cu (31–72%), and to the Cu + Fe treatment (78%) compared with those from the other trace metal mixtures (0–22%). In all the treatments tested, fry exposed to trace metal mixtures containing Al and/or Cu had reduced whole body Ca, Na and K content, and seriously impaired skeletal calcification. Whole body Mg content was variable. In trace metal mixtures which contained Cu but not Al, the effects on fry survival and whole body mineral content were in general more deleterious than the corresponding mixtures but with Al present rather than Cu. The presence of Pb and/or Zn in mixtures with Al and/or Cu had a slight ameliorative effect in terms both of fry survival and whole body mineral content.     

The relative abundance of brown trout in acidic softwater lakes in relation to water quality in tributary streams

The influence of the water quality of tributary streams on the relative abundance in benthic gillnet catches (catch per unit effort, cpue) of allopatric brown Salmo trutta was assessed in associated acidic, softwater lakes. The study was carried out over 6 years (1989–1994) in 15 lakes located at altitudes between 230–715 m a.s.l. in two Norwegian catchments. The water quality of the main inlets and outlets varied little, as indicated by their of pH range (4·93–5·51) and calcium concentrations (0·19–0·44 mg 1⁻¹), but varied more with respect to concentrations of inorganic, monomeric aluminium (7·0–41·0 μg l⁻¹). Most of the lakes were also fed by secondary streams with better water quality: a maximum pH of 6·56, calcium levels of up to 0·74mg 1⁻¹, and inorganic aluminium levels as low as l·0 μg 1⁻¹. The cpue was inversely correlated with lake altitude ( r ²=0·50), and thus was adjusted to a mean altitude. The calcium concentration in the richest secondary stream to each lake, its richness judged on the basis of its acid-neutralizing capacity, had the highest predictive power of the variability in cpue ( r ² = 0·49).The calcium content in the other secondary streams or in the main inlets and outlets did not correlate with cpue. Alkalinity in the main outlets correlated to some extent with cpue ( r ² = 0·27). It is suggested that secondary streams with good water quality provide important refuges for the recruitment of brown trout in acidic softwater lakes.     

Normal ranges of some blood chemistry parameters in adult farmed Atlantic salmon, Salmo salar

Blood samples from healthy adult Atlantic salmon fed an optimal diet in net sea pens were collected at intervals from October to May. Haematological determinations and biochemical serum analyses were carried out on 20 fish in each of seven samples. The ranges of haemato-logical values for sample means were: haematocrit 44–49%, haemoglobin 8.9–10.4 g 100ml⁻¹, red blood cell count 0.85–1.10 × 10¹² l⁻¹, MCV 441–553 × 10⁻¹⁵ 1, MCH 94–106 × 10⁻⁶ g, MCHC 19.4–21.7 g 100ml⁻¹ and leucocrit 0.43–0.96%. The ranges of enzyme activities in serum, for sample means, were: alkaline phosphatase 647–988Ul⁻¹, aspartate aminotrans-ferase 202–351 Ul⁻¹ and alanine aminotransferase 4–8 Ul⁻¹. The ranges of the other parameters analyzed in serum were: total protein 41.6–56.6 gl⁻¹, albumin 18.3–24.3 gl⁻¹, albumin/total protein ratio 39.3–44.0%, creatinine 26–46 μmol, triglycerides 2.53–4.98 μmol and cholesterol 9.3–12.8 μmol. These values are considered to be the normal ranges in healthy fish. Variations due to seasonal changes, and the clinical significance of the selected parameters, are discussed. Data showing the reproducibility of the biochemical analyses in serum are presented.     

Distribution and biodegradation potential of oil-degrading bacteria in North Eastern Japanese coastal waters

Abstract The distribution of oil-degrading microorganism in samples of surface water and sediment from North Eastern Japanese coastal waters was studied. Modified natural sea water (NSW) agar supplemented with emulsified crude oil (Arabian light, 5 g 1⁻¹) was used to enumerate oil-degrading bacteria. In addition, filtered samples were inoculated into NSW broth containing weathered crude oil. Incubation was carried out at 20°C for 7–10 days. Populations of oil-degrading microorganisms ranged from 3–230 CFU 100 ml⁻¹ in surface waters and 2.9 × 10³ to 1.2 × 10⁵ CFU g⁻ in sediment samples. Analysis of variance showed that oil-degraders were heterogenously distributed. Six mixed populations selected from 20 samples were studied to determine which of the constituent microflora were capable of crude oil biodegradation. Among 51 strains selected for identification, only 61% could be identified which formed 17 different bacterial species. Acinetobacter species (14 strains), Psychrobacter immobilis (9 strains) and Gram-positive cocci (10 strains) were the predominant types. Oil-degrading activity by various mixed populations (three each from water and sediment samples) was determined by using a conventional total weight reduction technique. Reduction in amount of various aliphatic and aromatic hydrocarbon substrates was verified using gas chromatography and high pressure liquid chromatography. Biodegradation of crude oil ranged from 35–58%. One mixed population of the sediment samples degraded more hydrocarbon (both aliphatic and aromatic) and the biodegradation of the aromatic hydrocarbon reached as high as 48%.     

Attraction of zebrafish, Brachydanio rerio, to alanine and its suppression by copper

Preference responses of zebrafish to 10⁻³, 10⁻⁴ and 10⁻⁵M alanine (Ala) were concentration- dependent. Behavioural responses to copper (Cu) and Cu + Ala mixtures were also assessed. Zebrafish avoided 100 and 10 μg Cu l⁻¹, but not 1 μg l⁻¹. Mixtures of 10⁻³ m Ala+ 100 μg Cu l⁻¹ and 10 ⁴ M Ala + 10 μg Cu 1⁻¹ were avoided as intensely as was Cu alone. Responses to 10⁻³ M Ala + 10 or 1 μg Cu l⁻¹ and 10 ⁴ M Ala +1 μg Cu l⁻¹ did not differ statistically from controls (no detectable preference or avoidance). These results demonstrate, firstly, that a concentration of a pollutant avoided by itself (10 μg Cu l⁻¹) may not be avoided when encountered with an attractant chemical stimulus (Ala) and may suppress the preference for an attractant stimulus, and secondly, that a concentration of a pollutant not avoided by itself and not considered deleterious (1 μg Cu l⁻¹) suppresses attraction to Ala (an important constituent of prey odours for many fishes).     

Distribution and metabolism of root-applied cytokinins in Pisum sativum

When N ⁶ [8–¹⁴C] furfuryladenine was applied to the intact root system of Pisum sativum L. cv. Meteor seedlings it was almost completely metabolised to other compounds within 24 h. Of the total activity recovered from the plants 94.5% was retained in the root system itself. ¹⁴C was recovered in a number of ethanol-soluble compounds and in ribonucleic acid, deoxyribonucleic acid and protein fractions of roots, stems, leaves and axillary buds. In rapidly growing axillary buds released from apical dominance by removal of the shoot apex the combined nucleic acid fractions accounted for 63.3% of the total ¹⁴C recovered from these organs. Xylem exudate collected from decapitated plants 0 to 12 h after supplying N ⁵[8–¹⁴C]furfuryladenine to the roots consistently contained a single major ¹⁴C-labelled compound which, in three different solvent systems, had the same Rf values as a major endogenous cytokinin isolated from the xylem of unlabelled plants. The content of N ⁶ [8–¹⁴C] furfuryladenine itself in the xylem exudate was always low and in some experiments it could not be detected.
It is suggested that part of the label from N ⁶ [8- ¹⁴CJfurfuryladenine taken up by the intact root system may have become incorporated in an endogenous cylokinin before export to the shoot.     

Induction of nitrate reductase in needles of Scots pine seedlings by NOX and NO3−

The possibility to induce nitrate reductase (NR; EC 1.6.6.2) in needles of Scots pine ( Pinus sylvestris L.) seedlings was studied. The NR activity was measured by an in vivo assay. Although increased NR activities were found in the roots after application of NO₃⁻, no such increase could be detected in the needles. Detached seedlings placed in NO₃⁻ solution showed increasing NR activities with increasing NO₃⁻ concentrations. Exposure of seedlings to NO_x (70–80 ppb NO₂ and 8–12ppb NO) resulted in an increase of the NR activity from 10–20 nmol NO₂⁻ (g fresh weight)⁻¹ h⁻¹ to about 400 nmol NO₂⁻ (g fresh weight)⁻¹ h⁻¹. This level was reached after 2–4 days of exposure, thereafter the NR activity decreased to about 200 nmol NO₂⁻ (g fresh weight)⁻¹ h⁻¹. Analyses of free amino acids showed low concentrations of arginine and glutamine in NO_x-fumigated seedlings compared to corresponding controls.     

Photosynthetic characteristics of the submerged macrophyte Ceratophyllum demersum

The photosynthetic and growth characteristics of Ceratophyllum demersum L. were investigated under laboratory conditions which simulated those encountered in the plants' normal environment. The carbon fixation rate of C. demersum measured with ¹⁴C at light and carbon saturation at pH 8.0 was 4.48 mg C (g ash-free dry weight)⁻¹ h⁻¹. It was lower at pH 6.5 than at pH 8.0. The light use efficiencies in quiescent plants and actively growing plants were 6.3 and 8.7 × 10⁻⁹ kg CO₂ J⁻¹, respectively, with corresponding maximum photosynthetic rates of 2.67 and 4.36 mg C (g ash-free dry weight)⁻¹ h⁻¹. Photorespiration in actively growing plants consumed 24% of the carbon fixed. Incubation with DCMU demonstrated that about one-third was refixed. The optimum temperature for carbon fixation was 25°C. The C₃-photosynthetic pathway was the main operational route as indicated by the early photosynthetic products (largely C₃-acids) and the absence of Krantz anatomy and the chlorophyll a:b ratio (2.7). The maximum relative growth rates ranged from 0.025 to 0.041 g ash-free dry weight (g ash-free dry weight)⁻¹ day⁻¹ in the field (Lake Vechten, 1 to 3 m depth classes).     

Efficacy of certain disinfectants against infectious pancreatic necrosis virus

The virucidal properties of iodophor, chlorine (sodium hypochlorite), formalin, thimerosal (organic mercurial compound), malachite green, and acriflavine were tested on infectious pancreatic necrosis virus (IPNV). Iodine and chlorine showed good activity, but efficacy depended on the concentration of virus, the presence of organic matter (calf serum), and water _pH. Water hardness (0-300 mg 1⁻¹ as CaCO₃) did not affect virucidal activity. In a 5 min exposure, 4 mg 1⁻¹ available iodine inactivated 10^3.9 TCID₅₀ m1⁻¹ IPNV but 16 mg 1⁻¹ iodine were needed for inactivation of 10^6.3TCID₅₀m1⁻¹. The addition of 0-5% calf serum significantly reduced the iodine concentration and the virucidal activity. In comparison, 4 mg 1⁻¹ chlorine were needed to inactivate 10⁴⁶ TCID₅₀ m1⁻¹ IPNV in 5 min. However, the addition of 0-07 % serum greatly reduced the chlorine concentration and extended the virucidal contact time to 30 min or more. IPNV at 10^6.3 TCID₆₀ m1⁻¹ was not inactivated by exposures for 60 min to 0-2% formalin, 10 min to 0-2% thimerosal, 60 min to 5 mg 1⁻¹ malachite green, or 20 min to 500 mg 1⁻¹ acriflavine. However, acriflavine at 0-5 mg 1⁻¹ in cell culture media prevented the development of cytopathology caused by IPNV and may be useful in the treatment of the disease.     

Content of low-molecular-weight thiols during the imbibition of Pea seeds

The metabolism of low-molecular-weight thiols was investigated in seeds of Pisum sativum L. cv. Kleine Rheinländerin during imbibition in water for 14 h. The amount of oxidized glutathione (GSSG) decreased from 319 nmol (g dry weight)⁻¹ in dry seeds to 38 nmol (g dry weight)⁻¹ within the first 14 h of imbibition. The decrease may have been due to the reduction of GSSG to reduced glutathione (GSH), catalyzed by the enzyme glutathione reductase (GR; EC 1.6.4.2). The enzyme activity was high in dry seeds [25 nkat (g dry weight)⁻¹] and decreased to 20 nkat (g dry weight)⁻¹ within 14 h of imbibition. The activity of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) decreased from 100 nkat (g dry weight)⁻¹ in dry seeds to 67 nkat (g dry weight)⁻¹ after 14 h of imbibition. Within 14 h the amount of γ-glutamyl-cysteine (γ-GC) decreased from 135 to 38 nmol (g dry weight)⁻¹, whereas the cysteine content rose from 81 nmol (g dry weight)⁻¹ in dry seeds to a maximum of 170 nmol (g dry weight)⁻¹ after 12 h of imbibition, which may be due to the degradation of γ-GC into cysteine.     

The inhibition of photosynthesis and photorespiration in isolated mesophyll cells of Phaseolus and Lycopersicon by reduced osmotic potentials

Mesophyll cells isolated from Phaseolus vulgaris and Lycopersicon esculentum show decreasing photosynthetic rates when suspended in media containing increasing concentrations of osmoticum. The photosynthetic activity was sensitive to small changes in osmotic potential over a range of sorbitol concentrations from 0.44 M (−1.08 MPa) to 0.77 M (−1.88 MPa). Photorespiration assayed by ¹⁴CO₂ release in CO₂-free air and by ¹⁴CO₂ release from the oxidation of [1–¹⁴C] glycolate also decreased as the osmotic potential of the incubation medium was reduced. The CO₂ compensation points of the cells increased with increasing concentration of osmoticum from approximately 60 μ I⁻¹1 at −1.08 MPa to 130 μl 1⁻¹ for cells stressed at −1.88 MPa. Changes in photosynthetic and photorespiratory activities occurred at moderate osmotic potentials in these cells suggesting that in whole leaves during a reduction in water potential, non- stomatal inhibition of CO₂ assimilation and glycolate pathway metabolism occurs simultaneously with stomatal closure.     

Some effects on the growth of brown trout from exposure to aluminium at different pH levels

Yearling brown trout, Salmo trutta L., were exposed to various concentrations of inorganic aluminium (0–3.7 μM1⁻¹) over a pH range of 4.3–6.5 in a flow-through bioassay apparatus using synthetic test media. Low pH, in the absence of aluminium, produced little effect on growth or survival except at the lowest pH tested (4.3). At pH less than 5.5, concentrations of total aluminium in excess of 1 μM 1⁻¹ (27μg 1⁻¹) were found to retard growth. The effects of a given aluminium concentration were markedly reduced at pH above 5.5.
The change in aluminium toxicity with pH must be related to changes in aluminium chemistry. When growth rates are correlated with the different aluminium species, calculated using thermodynamic equilibrium constants given in the literature, it appears that the Al(OH)^{2 +} species is the most toxic, with a small contribution also coming from polymeric complexes.     

Identification and characterization of Bacillus anthracis by multiplex PCR analysis of sequences on plasmids pXO1 and pXO2 and chromosomal DNA

Abstract Bacillus anthracis can be identified on the basis of the detection of virulence factor genes located on two plasmids, pXO1 and pXO2. Thus isolates lacking both pXO1 and pXO2 are indistinguishable from closely related B. cereus group bacteria. We developed a multiplex PCR assay for characterization of B. anthracis isolates, and simultaneous confirmation of the species identity independent of plasmid content. The assay amplifies lef, cya, pag (pXO1) and cap (pXO2) genes, and a B. anthracis specific chromosomal marker, giving an easy-to-read profile. This system unambiguously identified virulent (pXO1⁺/2⁺) and avirulent (pXO1⁺/2⁻, pXO1⁻/2⁺ and pXO1⁻/2⁻) strains of B. anthracis and distinguished 'anthrax-like' strains from other B. cereus group bacteria.     

Cytochrome c-mediated caspase-9 activation triggers apoptosis in Streptococcus pyogenes-infected epithelial cells

Epithelial cells are the initial sites of host invasion by group A Streptococcus pyogenes (GAS), and their infection of epithelial cells has been suggested to induce apoptosis. However, the mechanism responsible for bacteria–host interaction and the induction of apoptosis has not been clearly understood. We demonstrate here that human pharyngeal epithelial HEp-2 cells became apoptotic with DNA fragmentation by invasion of GAS strains JRS4 (M6⁺, F1⁺) and JRS145 (M6⁻, F1⁺ mutant of JRS4), whereas apoptotic cellular changes were not observed in SAM1 (M6⁺, F1⁻ mutant) or SAM2 (M6⁻, F1⁻ mutant) infected HEp-2 cells. Confocal microscopy revealed that Bax translocation to mitochondria and cytochrome c release occurred after 4 h of infection. Western blot analyses showed that the amounts of Bcl-2 and Bcl-x_L were decreased in the mitochondria of infected cells. In addition, we demonstrated that the release of nuclear histone from infected cells was prevented by the addition of caspase-9 inhibitor (Ac-LEHD-CHO). We conclude that the internalization of GAS in epithelial cells is necessary and sufficient for the induction of apoptosis, which is initiated by mitochondrial dysfunction, and the mechanism of GAS-induced apoptosis is clearly different from that induced by other intracellular invasive bacteria, e.g. Shigella and Salmonella species.     

Redistribution of Imipramine from Regions of the Brain Under the Influence of Circulating Specific Antibodies

Abstract: The kinetics of brain-to-blood redistribution of imipramine (IMI) was assessed in nine brain regions of control rats and rats given anti-tricyclic antidepressant (anti-TCA) antibody. Two antibodies were given intravenously 6 min after intravenous [³H]IMI (1 nmol/kg). One was a murine monoclonal IgG₁ ( K _a = 3.8 × 10⁷ M ⁻¹) at an IgG/IMI molar ratio of 1,000 (IgG1,000), and the other was a sheep polyclonal IgG (TAb; K _a = 1.3 × 10¹⁰ M ⁻¹) at IgG/IMI molar ratios of 1, 10, and 100 (TAb1, TAb10, and TAb100). In the control rats, IMI was rapidly taken up by the brain ( C _max at 5 min) with no significant differences among the brain regions (4.1 ± 0.4 to 5.4 ± 0.6 pmol/g), and brain IMI then declined monoexponentially with a half-life of 44.2 min (cerebellum) to 77.3 min (hippocampus). The greatest IMI content was in the frontal cortex and the lowest in the cerebellum. The antibodies (except TAb1) stimulated the extent and rate of IMI redistribution from all the brain regions depending on the immunoreactive capacity ( NK _a) of the antibody. The antibody with the highest NK _a (TAb100) had the greatest effect. The fraction of IMI removed from the brain was 58–74%, and the redistribution half-life was 7.9–15.6 min; the mean residence time was reduced by 66–75% (11.8–23.9 min). These results demonstrate that circulating anti-TCA IgG rapidly and reliably removes IMI from the brain, indicating that immunotoxicotherapy could be an efficient procedure for accelerating the removal of TCA from the brain.     

Changes of Nucleic Acids and Proteins in the Oocysts of Eimeria tenella during Sporulation

SYNOPSIS. The total content of DNA in Eimeria tenella , estimated at 5.8 × 10⁻¹² gm/oocyst, varies little during sporulation. Its buoyant density is 1.682 gm/cm³, reflecting a G + C content of ∼41%. Thymidine is not incorporated into any TCA insoluble fraction of sporulating oocysts, but radioactivity from [³H]uridine and [³H]deoxyuridine are incorporated into RNA at a linear rate during the first 5 hr of sporulation. The labeled RNA, found mainly in the paranuclear bodies of newly formed sporozoites, contains ∼0.15 nmole [³H]uridine/10⁶ oocysts at the completion of sporulation. One nmole of leucine is incorporated into the hot TCA insoluble fraction of 10⁶ oocysts during the first 7 hr of sporulation after an initial lag. The incorporated amino acid is mainly in the cytoplasm of the sporozoites, and an analysis by SDS-gel electrophoresis reveals most of the radioactivity in a narrow band with a molecular weight of ∼50,000 daltons. Incorporation of uridine and leucine, however, can be totally suppressed by respiratory inhibition. Further analysis of the proteins in the oocysts reveals that the total protein content remains relatively unchanged at 2.64 × 10⁻¹⁶ gm/oocyst during sporulation, but there is a shift of 13–14% of total protein from the soluble cytoplasm to the 15,000 g pellets. By polyacrylamide gel electrophoresis, a major protein band. possibly a glycoprotein, is shown in the soluble cytoplasm of unsporulated oocysts. This band disappears during sporulation.     

A light intensity threshold for schooling in the Atlantic mackerel, Scomber scombrus

The schooling behaviour of Atlantic mackerel was studied in a large tank at different light intensities in the range 12.6–1.8 × 10⁻¹⁰μEs⁻¹ m⁻². Variable light intensity was produced by accurately controlling the current to a green light-emitting diode (LED) 3 m above the experimental tank. Under high light levels (1.8 × 10⁻⁶μEs⁻¹ m⁻²) mackerel always formed a single school, whereas at lower levels (1.8 × 10⁻⁸μEs⁻¹ m⁻²) they swam as individuals. At light levels down to 1.0 × 10⁻⁶μEs⁻¹ m⁻² the mean nearest neighbour distance in a school remained relatively constant (0.3–0.9 body lengths), and individual mackerel swam along a path which deviated from the position of their nearest neighbours by less than 14°. As light dropped below 1.8 × 10⁻⁷μEs⁻¹ m⁻², both nearest neighbour distance and heading angle between nearest neighbours increased, with mean values of 1–1.8 body lengths and 23–92°, respectively, at 1.8 × 10⁻⁹μEs⁻¹ m⁻². The results are discussed in terms of ambient light conditions in the sea.