The acute lethal toxicity to rainbow trout of mixtures of copper,phenol, zinc and nickel†

The acute lethal toxicities to rainbow trout, Salmo gairdneri Richardson, of mixtures of copper and phenol, of copper, zinc and phenol, and of copper, zinc and nickel, over an exposure period of 48 h were determined. The concentrations selected for testing were such that each poison theoretically contributed equally to the toxicity of the mixture. It was found that the toxicities of these mixtures could be adequately predicted by summation of the fractional toxicities of the particular poisons which were present.     

INTERACTION OF ASTRINGENCY AND TASTE CHARACTERISTICS1

The perception of astringency and basic taste in mixtures and their interaction effects were investigated by two procedures. In Experiment 1, focused and nonfocused testing procedures were compared using mixtures of low and high concentrations of alum and basic taste solutions. Both procedures yielded taste and astringency intensities that were modality‐dependent. Nonfocused testing was used in Experiment 2 to investigate the interactions of astringent phenolic (tannic acid) and nonphenolic (alum) compounds with each basic taste. Sweetness of sucrose increased with increased concentration with or without alum or tannin present. Changes in salty, bitter, and sour taste intensities were modality‐dependent. Astringency either remained unchanged or decreased with the addition of sucrose, sodium chloride, citric acid, or caffeine depending upon the taste concentration. Bitterness of tannin and alum at high concentrations was suppressed by the addition of sucrose, sodium chloride, or citric acid; sourness also decreased in the presence of sucrose or sodium chloride as well as a high level of caffeine.     

硫磺菌原变种液体培养代谢物生物活性分析

硫磺菌原变种Laetiporus sulphureusvar.sulphureus在液体培养条件下对果蝇具有致死效应,研究发现在液体培养过程中分泌到细胞外的代谢产物是致死效应的主要原因,并且上清液对果蝇的生物活性受pH值的影响。离子交换树脂柱和高效液相色谱分离分析表明草酸存在于硫磺菌原变种培养液的上清液中并且是果蝇致死效应和培养体系pH下降的一个重要因素。硫磺菌原变种在气升式反应器ALR/ff培养体系中草酸的浓度、菌丝体量和pH值呈简单相关。进一步分析发现还有另外一种结构未知、在碱性条件下呈紫红色的色素也具有致死效应。     

Physical and chemical studies of Thiobacillus ferroxidans lipopolysaccharides.

The lipopolysaccharides (LPS) of the obligate acidophile Thiobacillus ferroxidans grown on iron, sulfur, and glucose as energy sources were examined for various physical and chemical properties. Both qualitative and quantitative variation were found among the three preparations. The LPS extracted from iron-grown cells (Fe-LPS) contained less than 3% protein compared to 18 to 25% in LPS extracted from either sulfur-grown cells (S-LPS) or glucose-grown cells (G-LPS). S-LPS showed two distinct sedimentable species, 61S and 9.3S, which could be fractionated on a column of Sepharose 4B. The relative densities of both S-LPS and G-LPS were found to be significantly greater than that of Fe-LPS. Spectral differences were noted when each LPS was reacted with a carbocyanine dye. Fe-LPS showed a single absorbance maximum at 472 nm, S-LPS displayed its maximum at 650 nm, and G-LPS showed two maxima, the first at 468 nm and the other at 655 nm. Analysis of the methyl ester derivatives of the LPS fatty aicds using gas chromatography-mass spectrometry revealed the presence of a very stable species, tentatively identified as a methoxy methyl ester with a formula of CH3-3-C10H10-COOCH3, as the major component from each LPS. beta-Hydroxymyristic acid was found only in Fe-LPS.     

Interactions of astringent substances

Two-component mixtures of astringent materials were rated forperceived intensity of astringent and taste attributes overtime. Components included alum (a complex salt), gallic acid(the monomeric component of hydrolyzable tannins), catechin(the monomeric component of condensed tannins) and citric acid.Mixtures of alum and gallic acid showed mixture suppression,in that the 50/50 mixture was less intense than either componentin astringency, drying, roughing and puckery/drawing sensations.Suppression was seen at concentration levels producing moderateto strong astringency but was absent or less pronounced at lowerconcentration levels. A similar pattern held for citric acid,although the suppressive effects were less pronounced. Catechinand gallic acid mixtures were additive. Sensory interactionsbetween astringent materials appears to depend on the substancesinvolved and their concentrations (or intensity levels).     

Effect of phenolic compounds on the germination of six weeds species

Low molecular weight phenolic compounds have been identified in fresh leaves and in soils in which leaves of five varieties of Capsicum annuum L. were decomposing. Six phenolic compounds were tested in laboratory bioassays for their allelopathic effects on germination and seedling growth of six weeds. Ferulic acid, gallic acid, p-coumaric acid, p-hydroxybenzoic acid, vanillic acid, and p-vanillin were bioassayed in concentrations of 10, 1, 0.1, and 0.01 mM. Equimolar mixtures containing all these phenolics were prepared at the final total concentration of 10, 1, 0.1, and 0.01 mM to test for possible interactive effects. Chenopodium album L., Plantago lanceolata L., Amaranthus retroflexus L., Solanum nigrum L., Cirsium sp. and Rumex crispus L. were the selected target weeds. The highest concentration of the compounds inhibited the germination of all these weeds, but lower concentrations had no effect or were stimulatory. However, effects varied with the weed species, the concentration of the compound tested and the compound itself. In assays with the mixture of phenolics we found evidence of some additive effects.     

Determination of each constituent in mixtures of catechol and protocatechuic acid,quinol and gentisic acid,phenol and p-hydroxybenzoic acid,and pyrogallol and gallic acid

Simple, rapid spectrophotofluorometric methods were developed for determining each constitutent in the mixtures of catechol and protocatechuic acid and in mixtures of quinol and gentisic acid. A colorimetric method involving the use of 4-aminoantipyrine and extraction with chloroform was proposed for determining each constituent in mixtures of phenol and p-hydroxybenzoic acid. Two simple and rapid colorimetric methods were used in conjunction to determine each constituent in mixtures of pyrogallol and gallic acid. The accuracy of all methods was within ±5%.     

Some effects of exposing rainbow trout (Salmo gairdneri Richardson) to phenol solutions

Phenol (C₆H₅OH) at non-lethal concentrations in hard water had no effect on the urine flow rate or haematocrit of rainbow trout for exposure times of 24 h. Phenol was detected in the urine in a non-conjugated form and unchanged phenol was also extracted from muscle, blood and brain. Uptake of phenol into tissue was found to be rapid with an equilibrium concentration being reached in 3 h. Loss of phenol after exposure was as rapid. The equilibrium concentration for muscle was similar to the phenol concentration to which the fish were exposed. Blood and brain contained smaller amounts. Close to or above the lethal threshold concentration (48-h lc₅₀9 mg 1^-l; 15°C) the fish had higher than ambient concentrations in their tissues most notably in the brain. Above the lethal threshold there is evidence of a large uptake of phenol by erythrocytes.     

Acid hydrolases of the rat uterus in relation to pregnancy, post-partum involution and collagen breakdown

1. The rat uterus contains acid cathepsin, beta-glucuronidase, beta-galactosidase, acid phosphatase and deoxyribonuclease II at concentrations comparable with those found in liver. Two non-hydrolytic uterine enzymes, cytochrome c oxidase and aspartate aminotransferase, display only 2-6% of the activity found in liver. 2. The concentrations of acid cathepsin and beta-glucuronidase are significantly decreased in pregnancy and increase 3-4-fold during post-partum involution. 3. The concentrations of beta-galactosidase and acid phosphatase are not decreased in pregnancy and increase only 2-3-fold during involution. 4. The concentrations of these four acid hydrolases increase linearly during the first 4 days post partum and reach their peak values at the same time that wet weight and collagen content fall to their lowest point. 5. The concentration of deoxyribonuclease is depressed in pregnancy but does not rise above normal in the post-partum period. 6. Only a small proportion of each hydrolytic activity can be isolated in the mitochondrial-lysosomal fraction of sucrose homogenates of the rat uterus. This proportion increases during involution. However, the extensive mitochondrial rupture occurring during homogenization indicates that the technique is probably too harsh to obtain a true measure of the proportion of lysosomes present in the intact tissue. 7. There are no significant changes in either the concentration or subcellular distribution of the five acid hydrolases in the livers of the experimental rats during pregnancy or involution. In each case the largest proportion of the activity is found in the mitochondrial-lysosomal fraction of liver homogenates. 8. The results are interpreted in terms of the lysosomal theory of intracellular digestion.     

Hyperglycemia after protein ingestion concurrent with injection of a GLP-1 receptor agonist in rats: a possible role for dietary peptides

Protein ingestion after injection of the glucagon-like peptide-1 receptor agonist Exendin-4 (Ex-4) causes hyperglycemia in rats. The objectives of this study were to determine the components of protein digestion responsible for this effect and to associate it with changes in the concentrations of other metabolites and hormones. Two experiments were conducted. In the first experiment, food-deprived rats were gavaged with intact whey (WP) or albumin protein, their hydrolysates, amino acid mixtures (1 g/2.5 ml), or water 5 min after injection of either PBS or Ex-4 (0.5 microg/rat). Tail vein blood was analyzed for glucose over 2 h. In the second experiment, food-deprived rats were gavaged with WP with or without Ex-4. Groups of conscious rats were killed by decapitation either before, or at selected times after gavage. Plasma concentrations of glucose, amino acids, free fatty acids (FFA), glycerol, insulin, glucagon, and leptin were measured. In experiment 1, blood glucose was higher when intact proteins and protein hydrolysates, but not amino acid mixtures, were given with than without Ex-4 (P < 0.05). In experiment 2, concentrations of glucose, FFA, and the ratio of tyrosine to branched-chain amino acid were higher (P < 0.01), but leptin and essential amino acid concentrations were lower (P < 0.05), and insulin, glucagon, and glycerol were similar when WP was given with or without Ex-4. We conclude that the hyperglycemia caused by the administration of Ex-4 concurrently with dietary protein arises from the action of peptides released during digestion and their interaction with Ex-4 in the regulation of glucose, fatty acid, and amino acid metabolism.     

Precolumn extraction and reversed-phase high-pressure liquid chromatography of prostaglandins and leukotrienes

Prostaglandins, leukotrienes, and other metabolites of arachidonic acid can be conveniently and efficiently extracted from biological media using a precolumn containing octadecylsilyl silica connected to a 6-port switching valve that is in line with an analytical HPLC column. This procedure makes it possible to extract complex mixtures of eicosanoids and to analyze them by reversed-phase HPLC in a single step. The requirement to evaporate solvents from extracts prior to HPLC is therefore eliminated, saving time and reducing the possibilities for loss and contamination. The effects on recoveries of various media for loading the sample onto the precolumn were investigated, and it was concluded that 15% methanol at neutral pH gives the best overall results. It is therefore not necessary to acidity the sample prior to extraction, which simplifies the procedure and improves the recoveries of acid-labile eicosanoids. Following extraction, eicosanoids can be introduced onto the HPLC column by changing the position of the 6-port switching valve. We have investigated several approaches to the analysis of complex mixtures of these products by reversed-phase HPLC. The best results were obtained using a ternary gradient with a non-end-capped column of octadecylsilyl silica. Metabolites of arachidonic acid other than peptido-leukotrienes were first eluted by increasing the concentrations of acetonitrile and methanol in the mobile phase, which contained a constant concentration of trifluoroacetic acid (0.001%). Peptido-leukotrienes were then eluted with a second gradient, in which the concentrations of acetonitrile and methanol were kept constant, but the concentration of trifluoroacetic acid was increased to 0.0091%. Leukotrienes C4, D4, and E4 appear as sharp peaks at the end of the chromatogram and are completely separated from other types of arachidonic acid metabolites.     

Lysis of Streptococcus mutans by hen egg white lysozyme and inorganic sodium salts.

Streptococcus mutans BHT was grown in a synthetic medium containing radioactive thymidine to monitor deoxyribonucleic acid release. Kinetic experiments demonstrated that although lysozyme alone could not liberate deoxyribonucleic acid, cellular deoxyribonucleic acid was liberated from lysozyme-treated cells by addition of low concentrations of inorganic sodium salts. When the salts were tested for their ability to dislodge cell-bound tritiated lysozyme, the extent of the initial release of enzyme by individual anions correlated with the anion potency for deoxyribonucleic acid liberation (SCN- greater than ClO4- greater than I- greater than Br- greater than NO3- greater than Cl- greater than F-), although the total amount of lysozyme dislodged did not correspond directly with cell lysis. Differences in the effectiveness of anions (SCN-, HCO3-, Cl- and F-) in potentiating cell lysis could be enhanced or minimized by varying the lysozyme, anion, and bacterial cell concentrations. As the anion concentration was increased for each enzyme concentration and cell concentration, the lysis increased, in some cases markedly, until maximum levels of released deoxyribonucleic acid were attained. The maximum levels of lysis of SCN- and HCO3- were similar and were greater than those for Cl- and F-. In addition, the maximum levels were observed to increase for each of the anions as the concentration of lysozyme increased.     

The effect of feeding with a tryptophan-free amino acid mixture on rat liver magnesium ion-activated deoxyribonucleic acid-dependent ribonucleic acid polymerase

1. The Widnell & Tata (1966) assay method for Mg(2+)-activated DNA-dependent RNA polymerase was used for initial-velocity determinations of rat liver nuclear RNA polymerase. One unit (U) of RNA polymerase was defined as that amount of enzyme required for 1 mmol of [(3)H]GMP incorporation/min at 37 degrees C. 2. Colony fed rats were found to have a mean RNA polymerase activity of 65.9muU/mg of DNA and 18h-starved rats had a mean activity of 53.2muU/mg of DNA. Longer periods of starvation did not significantly decrease RNA polymerase activity further. 3. Rats that had been starved for 18h were used for all feeding experiments. Complete and tryptophan-deficient amino acid mixtures were given by stomach tube and the animals were killed 15-120min later. The response of RNA polymerase to the feeding with the complete amino acid mixture was rapid and almost linear over the first hour of feeding, resulting in a doubling of activity. The activity was still elevated above the starvation value at 120min after feeding. The tryptophan-deficient amino acid mixture produced a much less vigorous response about 45min after the feeding, and the activity had returned to the starvation value by 120min after the feeding. 4. The response of RNA polymerase to the feeding with the complete amino acid mixture was shown to occur within a period of less than 5min to about 10min after the feeding. 5. Pretreatment of the animals with puromycin or cycloheximide was found to abolish the 15min RNA polymerase response to the feeding with the complete amino acid mixture, but the activity of the controls was unaffected. 6. The characteristics of the RNA polymerase from 18h-starved animals and animals fed with the complete or incomplete amino acid mixtures for 1h were examined. The effects of Mg(2+) ions, pH, actinomycin D and nucleoside triphosphate omissions were determined. The [Mg(2+)]- and pH-activity profiles of the RNA polymerase from the animal fed with the complete mixture appeared to differ from those of the enzyme from the other groups, but this difference is probably not significant. 7. [5-(3)H]Orotic acid incorporation by rat liver nuclei in vivo was shown to be affected by the amino acid mixtures in a similar manner to the RNA polymerase. 8. The tryptophan concentrations of plasma and liver were determined up to 120 min after feeding with the amino acid mixtures. Feeding with the complete mixture produced a rapid increase in free tryptophan concentrations in both plasma and liver, but feeding with the incomplete mixture did not alter the plasma concentration. The liver tryptophan concentration increased at about 45min after feeding with the tryptophan-deficient diet. 9. There was a good correlation between the liver tryptophan concentration and RNA polymerase activity in all groups of animals. 10. It was concluded that the rat liver nucleus responded to an increase in amino acid supply by increased synthesis of RNA as a result of synthesis of RNA polymerase de novo. The correlation of tryptophan concentration and RNA polymerase activity appears to reflect the general amino acid concentration required to support hepatic protein synthesis and to produce new RNA polymerase. This new polymerase appears to differ from the basal RNA polymerase by its rapid synthesis and destruction, which may be a means of regulating RNA synthesis by the amino acid concentration in the liver.     

Sodium-induced aggregation of phosphatidic acid and mixed phospholipid vesicles

Sodium-induced aggregations of sonicated vesicles prepared from synthetic phosphatidic acid and from its 1 : 1 mixtures with synthetic phosphatidylethanolamine and phosphatidylcholine were studied by turbidimetric measurements. The aggregation reactions were almost completely reversible on change in the Na⁺ concentration, pH or temperature. The threshold concentrations of Na⁺ for aggregation of pure dipalmitoylphosphatidic acid vesicles and mixed dipalmitoylphosphatidylenolamine- and dimyristoylphosphatidylcholine-dipalmitoylphosphatidic acid vesicles were found to be 200, 310 and 550 mM, respectively, at 25° and pH 7.2. The hydrocarbon chain lengths of phosphatidic acid and phosphatidylethanolamine had little effect on the threshold concentrations. The threshold concentrations for phospholipid vesicles composed of phosphatidic acid alone or its 1 : 1 mixture with phosphatidylethanolamine were changed by varying either the pH or temperature, while that for phosphatidylcholine-phosphatidic acid vesicles was almost independent of the pH and temperature, implying that aggregation of the latter vesicles is induced by a somewhat different mechanism.     

Bioaccumulation of cadmium: toxicity in Mugil cephalus

A series of 12 lethal and sublethal concentrations of Cd were applied in seawater to determine LC50 for two sizes of fish. Fries were found to be more sensitive to Cd toxicity than juveniles. During 2, 4, 6 and 8 week exposure periods to graded Cd concentrations, mortality increased but no significant effect on growth occurred. From subacute experiments, the MATC for fries and juveniles were 0.05-0.02 ppm Cd2+/1 and 2-0.1 ppm Cd2+/1, respectively. Liver was found to accumulate the highest concentration of Cd followed by gill, muscle, alimentary canal and finally the heart.     

Chemometric methods for simultaneous quantification of lactic,malic and fumaric acids

Lactic, fumaric and malic acids are commonly used in food and pharmaceutical industries. During microbial production of these compounds, it is important to determine their concentrations in the fermentation broth with a rapid and sensitive method. Spectrophotometry is commonly used. However, UV‐spectral overlap between these organic acids makes it difficult to determine each of them individually from the mixture. In order to overcome this problem, statistical methods, namely principal component regression (PCR) and partial least squares‐1 methods, were tested and compared with conventional HPLC techniques. The absorbance data matrix was obtained by measuring the absorbances of 21 ternary mixtures of lactic, fumaric and malic acids in a wavelength range of 210–260 nm. Calibration and validation were performed by using the data obtained in a mixture of these organic acids. The prediction abilities of the methods were tested by applying them to fermentation broths. The precision of the PCR method was better than that of the partial least squares‐1 method. In the PCR method, the correlation coefficients between actual and predicted concentrations of the organic acids were calculated as 0.970 for lactic acid and 0.996 for fumaric acid in fermentation broths. The concentration of malic acid was not detected due to its low concentration in samples. These results show that the PCR method can be applied for simultaneous determination of lactic, fumaric and malic acids in fermentation broths.     

Synthesis of lovastatin with immobilized Candida rugosa lipase in organic solvents: Effects of reaction conditions on initial rates

Lipase from Candida rugosa immobilized on a nylon support has been used to synthesize lovastatin, a drug which lowers serum cholesterol levels, by the regioselective acylation of a diol lactone precursor with 2-methylbutyric acid in mixtures of organic solvents. Analogs of lovastatin having a different side chain were also obtained through this method by reacting the diol substrate with different carboxylic acids. The selection of reaction conditions that maximize the initial reaction rate is investigated. Since the diol substrate has very low solubility in non-polar solvents, reaction solvents consisting of mixtures of hexane with a different, more polar cosolvent are considered. For each of the cosolvent mixtures studied, the reaction rate is maximum for an intermediate percentage of cosolvent in hexane. With total concentrations of the diol lactone in the range 6.25-12.5 mM, maximum initial rates correspond approximately to those cosolvent concentrations that permit a complete solubilization of the substrate. At higher cosolvent concentrations, lower rates are obtained. When considering the same dissolved substrate concentration, the reaction rate was found to increase with increasing values of logP(mix) and decreasing values of the dielectric constant, when varying the composition of a binary solvent mixture. However, when comparing different cosolvents, no general trend with respect to these properties was observed. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56:671-680, 1997.     

Thermotropic behavior and electronmicroscopic structures of mixtures of gangliosides and dipalmitoylphosphatidylcholine

The calorimetric properties and morphological structures of dispersed mixtures of 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and highly purified human brain gangliosides, GM2, GM1, GD1a, GD1b, and GT1b, were studied using a high-sensitivity differential scanning calorimeter and an electron-microscope, as a function of the ganglioside molar fraction. No thermal phase transitions of pure gangliosides in aqueous dispersions could be detected. In the mixtures of DPPC and gangliosides, the gel to liquid crystalline phase transition occurred at a higher temperature than in pure DPPC dispersions and progressed over a wide temperature range. As increasing amounts of the pure ganglioside species were added to DPPC, the temperature for the main transition gradually increased. The phase transition progressed differently among different gangliosides/DPPC mixtures. The enthalpy values were found to decrease linearly as the number of sialic acid residues increased. Electron-microscopically the ganglioside/DPPC mixtures formed multilamellar structures at lower concentrations of the gangliosides, and the structures changed to cylindrical and spherical micelles as the ganglioside concentration was increased. The polysialoganglioside/DPPC mixtures showed the micellar form even at lower ganglioside concentrations, contrary to the case of the monosialoganglioside/DPPC mixtures. The morphological changes of gangliosides/DPPC mixtures corresponded with changes in the calorimetric properties. These results show that individual gangliosides have different physicochemical effects on model membranes, possibly because of the interaction of their negatively charged head groups.     

Chlorine Dioxide Disinfection Temperature Effects

S ummary . Washed suspensions of Escherichia coli were exposed to different concentrations of chlorine dioxide at various temperatures. Platings of the mixtures to evaluate the numbers of surviving cells were made after 5–300 sec of contact. Survival data were best fitted by a reaction model that is first order with respect to cell concentration and to exposure time. Bactericidal rates were found to increase markedly with both increased disinfectant concentrations and increased temperatures. Activation energies at each concentration of chlorine dioxide are reported.     

Cohort sampling, anaesthesia and stocking-density effects on plasma cortisol, thyroid hormone, metabolite and ion levels in rainbow trout, Salmo gairdneri Richardson

The effect of serial removal of fish from aquaria, anaesthesia and stocking density on plasma cortisol, thyroid hormone, metabolite and ion levels was examined in rainbow trout, Salmo gairdneri , to determine the consequences of normal handling and maintenance procedures on the activity of the pituitary-adrenal and pituitary-thyroid axes in the species.
The capture and handling associated with serial removal of fish from an aquarium resulted in a rapid elevation of plasma cortisol concentrations and a slower rise in plasma glucose, Mg²⁺ and Na⁺ concentrations; plasma K.+ levels showed a transient fall shortly after commencing the sampling, followed by a significant increase.
A lethal concentration of 3-aminobenzoic acid ethyl ester (MS 222) of 125 mgl⁻¹ (but not a sublethal concentration of 62.5 ng 1⁻¹) prevented the capture stressor-associated changes in most of the measured parameters, including plasma cortisol levels, although plasma protein and ion concentrations were elevated in fish sampled after MS 222-anaesthesia.
Stocking densities from 1 to 64 fish 80 1⁻¹ aquarium did not appear to effect changes in the measured parameters, except for plasma T3/T4 ratios which decreased with increasing stocking density. The exception was found in fish which were stocked in pairs: one member of each pair had a markedly elevated plasma cortisol level and there was a high incidence of mortality, probably related to aggressive social interaction.