bluuebunny/crossref_metadata_2025 huggingface dataset:
Tip‐enhanced optical spectroscopy for surface analysis in biosciences
Authors: Hartschuh A. , Qian H. , Meixner A. J. , Anderson N. , Novotny L.
Published: October 2006

Optical spectroscopy provides a wealth of information on the electronic and vibronic states of biological materials and surfaces, thus allowing for a detailed analysis of the sample constituents. Furthermore, information on photoprocesses such as excited‐state relaxation, charge transfer and coupling of individual quantum systems, as for example, in light‐harvesting complexes, can also be obtained. Advances in near‐field optics open up new means to overcome the diffraction limit and extend the range of optical measurements to the length scales of most nanosystems. In this paper, we describe a near‐field microscopic technique that relies on the enhanced electric field near a sharp, laser‐irradiated metal tip. This confined light source can be used for highly localized excitation of photoluminescence (PL) and Raman scattering. We study the properties of the enhanced fields and demonstrate PL and Raman imaging of single‐walled carbon nanotubes (SWCNTs) with sub‐15 nm resolution. The existing studies on biomaterials using tip‐enhanced techniques in the literature are reviewed and potential applications together with the requirements on sample materials are discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Uptake and exclusion of plutonium by bacteria isolated from soil near Nagasaki, Japan
Authors: Kauri Tiit , Kauri Tiiu , Santry D. C. , Kudo A. , Kushner D. J.
Published: October 2006

The ability to bind Pu4+ during growth in the presence of low concentrations of this ion was compared in 5 strains of bacteria isolated from soil that had been contaminated with Pu by fallout for more than 40 years. Although Pu became associated with all bacterial strains studied, the strength of association varied greatly. These results suggest that different bacteria use different techniques in dealing with Pu4+ ions. This, in turn, could greatly affect the fate of these ions in natural environments and their subsequent availability for other forms of life.
Absorption, distribution, and elimination of arsenic in New Zealand white rabbits (Oryctalagus cuniculus) following multiple oral doses of monosodium methane arsonate
Authors: Jaghabir Madi Wali , Abdelghani Assa F. A. , Anderson Ann C.
Published: October 2006

This work consisted of uptake and clearance studies resulting from the exposure of arsenic to New Zealand White rabbits. After two weeks' exposure to 5 mg monosodium methane arsonate/kg, the order of arsenic concentration in tissues was kidney > liver > muscle. By the end of four weeks' exposure, redistribution had taken place: liver > kidney > muscle. Arsenic was also detected in the fur (6.36 mg/kg) following four weeks' exposure.

Clearance studies showed that arsenic disappeared rapidly in the liver; however, trace amounts were detected in the kidney and the muscle two weeks following termination of continuous exposure. Arsenic was excreted in both urine and feces. Arsenic in rabbit fur showed no indication of elimination during the two weeks following continuous exposure.
Coliphages and other microbial indicators in stabilization ponds
Authors: Castillo G. C. , Trumper B. A.
Published: October 2006

Coliphages have been reported as promising indicators of viral inactivation in wastewater treatment. Their use in different aquatic environments, however, needs characterization prior to their application. The study of the behavior of coliphages in Chilean stabilization ponds is reported. The experimental system was a discontinuous reactor, subjected to the natural different climate conditions. Chile is a temperate country and this study concentrated on the significantly different behavior of ponds during summer and fall seasons. Coliphages counts using Escherichia coli C (ATCC 13706) as host were compared to most probable number fecal coliforms, Salmonella, and fecal streptococci. The results indicate that coliphages were more resistant to pond treatment than fecal coliforms and Salmonella. Furthermore, coliphages did not reflect climate changes as much as enteric bacteria did, as coliphage die‐off rates during warm and cold seasons were 0.5 and 0.3 (Kb, day−1). Summer die‐off rates of fecal coliforms (2.0, Kb, day−1) and Salmonella (1.7, Kb, day−1) drastically fell (0.6, Kb, day−1) in the fall. Coliphages and fecal streptococci removal tended to be similar, especially in cold season. It was observed that environmental factors, pH, dissolved oxygen, and algae biomass equally affected removal of all indicators, to different extents. These results suggest that to assess the microbiological efficiency of stabilization ponds, coliphages and fecal coliforms should be considered, as the first represents viral removal while the second represents pathogenic bacterial removal. Both parameters complement each other, particularly when important weather changes are expected.
Microbial purification in slow sand filter
Authors: Datta Amal K. , Chaudhuri Malay
Published: October 2006

Laboratory slow sand filter was characterized in terms of variation in catalase activity and standard plate count with depth as well as its effectiveness in inactivation of enteric microorganisms, using Escherichia coli as a model. The term inactivation was used to describe the overall process of removal/inactivation of enteric microorganisms in the filter, including predation, antagonism, etc. The following equation was proposed and used to estimate the inactivation potential of various filter bed depths from data on decay of E. coli in reactors with sand microorganism suspension from corresponding depths: dN/dt = −kN −(pG)N, in which N is the population of E. coli in reactor at time t, k is the decay rate of E. coli in control reactor, p is the inactivation potential, and G is the weight of sand sample corresponding to the sand microorganism suspension inoculum. Efforts were also made to examine the relative role of procaryotes and eucaryotes in the inactivation. It was observed that a matured filter bed was well populated throughout with active microorganisms, with its maximum in the top 10 or 25‐cm layer. Distribution of the population was independent of the rate of filtration. In general, the top 10 or 25 cm of the filter bed supported a microbial population that contributed most significantly to inactivation of E. coli.; the entire bed, however, was active in such inactivation. Both procaryotes and eucaryotes were active in the filter, with procaryotes more dominant near the top surface.
Contamination of domestic water heaters with Legionella pneumophila: Impact of water temperature on growth and dissemination of the bacterium
Authors: Dewailly E. , Joly Jean R.
Published: October 2006

Sediment and tap water from 255 randomly selected domestic water heaters were cultured on buffered charcoal yeast extract agar and two semiselective media to detect the presence of Legionellaceae. Different serogroups of L. pneumophila, the only species of Legionellaceae identified in this study, were found in 84 of the 255 water heaters and this contamination occurred only in electric water heaters (n = 205).

Sediment contamination by L. pneumophila was strongly associated with water temperature. The bacterium was detected in 45% (80/176) of the sediments with temperature lower than 40°C and in only 14% (4/29) of the sediments at this or higher temperatures. When the peripheral water temperature was lower than 56°C, 23% (9/39) of the tap water samples were contaminated with Legionella while only one of the 161 samples that were above this temperature contained Legionella.

These results do suggest that reducing the water temperature in electric water heaters could play a role in the multiplication of L. pneumophila in the water heaters and in its dissemination in the household.
A multiparameter chemical toxicity test using Salmonella typhimurium and Spirochaeta aurantia
Authors: Kupillas Gregory E. , Pill Kenneth G. , Picardal Flynn W. , Arnold Robert G.
Published: October 2006

A battery of measurements, including specific growth rate, intracellular ATP level, and respiration rate, was designed to measure the responses of Salmonella typhimurium and Spirochaeta aurantia to chemical toxicants. The test battery provided both a measure of relative toxicity and an indication of the biochemical mechanism of chemical toxicity.

The utility of the battery was investigated using chemicals (cyanide, 2,4‐dinitrophenol, chloramphenicol, and dicyclohexylcarbodiimide) for which toxic mechanisms have been clearly established. Test battery results provided a reproducible “signature” for each model compound, which was useful for differentiating among compounds whose primary mechanism of toxicity involves (a) inhibition of catabolic activity leading to oxidative phosphorylation, (b) disruption of membrane integrity, and (c) interference with biosynthetic activity. The responses of the two test organisms to model inhibitors were qualitatively identical and paralleled predictions based on theoretical grounds.

In theory, the test battery can measure toxicity among classes of compounds that alternative, single‐parameter microbial tests would classify as nontoxic. The microbial test battery described may eventually provide a theoretically superior and economically attractive alternative to established toxicity testing procedures.
Testing the influence of chemicals on soil autotrophic ammonium oxidation
Authors: Hansson G.‐B. , Klemedtsson L. , Stenström J. , Torstensson L.
Published: October 2006

Nitrification is crucial for the content of inorganic nitrogen in soil and hence of considerable ecological and agricultural importance. The first step in the nitrification process, the oxidation of ammonium to nitrite, is particularly sensitive to chemicals, and the ammonium oxidation activity of soils may thus be used as an indicator of chemical disturbances. A method for the determination of potential nitrification has been tested that measures ammonium oxidation specifically and under optimal conditions, has a good reproducibility, and makes it possible to screen a large number of chemicals during a short period of time. The method has been tested with a number of pesticides. Dithio‐carbamate fungicides gave the most pronounced inhibition of ammonium oxidation.
Fast method for detecting toxic Cyanophyte blooms
Authors: Volterra L. , Bruno M. , Gucci P. M. B. , Pierdominici E.
Published: October 2006

Owing to Cyanophytes, toxic blooms may originate in drinking water supplies. Since it is vitally important for human health that such blooms are rapidly identified and treatment plant for water potabilization is readily adapted, we have performed experiments aiming at assessing the usefulness of Microtox™ as a tool for detecting biotoxins caused by Cyanobacteria as rapidly as possible. Comparison between instrumental results and data obtained with Microtox has shown a discrepancy, but has also pointed out Microtox's sensitivity and therefore its application in monitoring Cyanophyte blooms in order to detect algal biotoxins, whose chemical characterization requires further examination following identification by the Microtox system.
Firefly assay of ATP from freshwater zooplankton: Comparison of extraction methods
Authors: Amyot M. , Pinel‐Alloul B. , Bastien C. , Méthot G. , Blaise C. , van Coillie R. , Thellen C.
Published: October 2006

Investigations were conducted to compare the efficiency of adenosine triphosphate (ATP) extraction from freshwater zooplankton species (Skistodiaptomus oregonensis, Tropocyclops prasinus mexicanus, Daphnia magna, and Bosmina longirostris) using DMSO and cold H2SO4 extraction procedures. DMSO was found to extract more ATP (particularly in copepod species) while cold H2SO4 provided more consistent results. Homogenization by grinding samples during extraction was shown to be a very important step. Juvenile and adult specimens of D. magna were extracted. Adults gave higher ATP values. The necessity for a 24‐h acclimation period was tested. Although acclimation appeared to provide more consistent results, no marked lowering of ATP level in organisms was registered without acclimation. No unique method was found to be optimal for all studied species. © 1992 John Wiley & sons, Inc.
Bioaccumulation and depuration of ethylene glycol by crayfish (procambarus spp.)
Authors: Khoury Ghassan A. , Abdelghani Assaf A. , Anderson Ann C.
Published: October 2006

Crayfish were exposed to 50, 200, or 1000 μg/mL ethylene glycol (EG) daily for 61 days, and were subsequently transferred to clean water for a 67‐day decontamination phase. During uptake and loss, samples were analyzed for EG in gills, muscle, gastrointestinal tract, and hepatopancreas. An open one‐compartment mathematical model described the uptake and loss phases data.

Uptake was dependent upon the aqueous concentration of EG. Crayfish did not concentrate EG above the water concentration. Bioaccumulation factors for the selected tissues at 61 days of exposure to 50, 200, and 1000 μg/mL EG, respectively were as follows: 0.40, 0.21, and 0.21 for gills; 0.48, 0.21, and 0.21 for muscle; 0.61, 0.42, and 0.27 for gastrointestinal tract; and 0.60, 0.33, and 0.22 for hepatopancreas. Time to equilibrium was 5,4,5, and 4 days for gills, muscle, gastrointestinal tract, and hepatopancreas, respectively, at 50 μg/mL aqueous concentration; 5, 4, 6, and 4 days, respectively, at 200 μg/mL aqueous concentration; and 7, 5, 7, and 5 days, respectively, at 1000 μg/mL aqueous concentration.

Crayfish eliminated the accumulated EG within 5 days for animals exposed to 50 μg/mL EG and 6 days for those exposed to 200 and 1000 μg/mL EG. © 1993 John Wiley & Sons, Inc.
Effect of copper, herbicides, and a mixed effluent on chemoattraction of tetrahymena pyriformis
Authors: Roberts Robert O. , Berk Sharon G.
Published: October 2006

The inhibitory effect of copper, 2,4‐D, Roundup, and an industrial effluent on chemoattraction responses of the ciliate Tetrahymena pyriformis was examined using a microcapillary technique. Each toxicant was tested with four replicates on three separate occasions. All toxicants inhibited chemoattraction at sublethal concentrations; although at lower concentrations of the herbicides, complete recovery to control levels was observed with longer exposures.

Results indicate that sublethal concentrations of certain chemical pollutants may interfere with the ciliate's motility or chemosensory abilities. This may ultimately affect the ecosystem by inhibiting their ability to maintain their population levels and roles in the environment.
Protein production during heat stress and exposure to toxicants in alcaligenes eutrophus JMP228
Authors: Amy Penny S. , Hiatt Hermi D. , Keith Dupre R.
Published: October 2006

In an effort to determine whether heat‐shock proteins might serve as useful indicators of environmental stress, the aquatic bacterium, Alcaligenes eutrophus JMP228, was exposed to two chemical stressors: a toxic heavy metal ion, cadmium, and a nonbiodegradable organic herbicide, 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T). Protein synthesis was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, comparing the protein patterns of chemically stressed cells to those exhibited by nontreated and heat‐shocked cells. Heat‐shock proteins were produced in response to both chemical stressors and heat. Proteins induced in response to all three experimental stresses include molecules with approximate molecular weights of 58–60 and 106 kDa. Still other stress proteins were only expressed following chemical stress. A 106 kDa protein was only produced following cadmium treatment, whereas proteins of 37, 39, 46, 49, and 77 kDa were only produced in response to 2,4,5‐T. The synthesis of some of the unique stress proteins varied in a dose‐dependent fashion with the concentration of the individual stressors. The presence of these proteins may be useful indicators of the “health” of an environment. © 1993 John Wiley & Sons, Inc.
Pseudomonas aeruginosa and other microbial indicators of pollution in fresh and marine waters of rio de janeiro, Brazil
Authors: Guimarães Vanessa F. , Araújo Marlise A. V. , Mendonçla‐hagler Leda C. S. , Hagler Allen N.
Published: October 2006

Counts of Pseudomonas aeruginosa had a high positive correlation with counts of coliforms, fecal streptococci, presumptive pathogenic yeasts, and heterotrophic bacteria in surface waters of Rio de Janeiro. Pseudomonas aeruginosa counts were notably higher in fresh than in marine waters, and it was isolated from about 50% of marine and 100% of nonchlorinated freshwater samples that passed the fecal coliform based Brazilian bathing standards. The most probable number method for enumeration of P. aeruginosa contained this microbe in 90% of the positive tubes from freshwater samples, but it had reduced selectivity in marine waters with 37.5% false negative and 35% false positive results. Microbial indicators of fecal pollution were not effective for noting the presence of P. aeruginosa in freshwaters. © 1993 John Wiley & Sons Inc.
An amperometric algal biosensor for herbicide detection employing a carbon cathode oxygen electrode
Authors: Pandard Pascal , Rawson David M.
Published: October 2006

A method is described for continuous monitoring of the photosynthetic oxygen evolution of the microalga Chlorella vulgaris, which was immobilized between alumina filters on the surface of a teflon‐covered carbon electrode. Sensitivity of the algal biosensor to herbicides was tested using an electrochemical flow cell with illumination provided by light‐emitting diodes. This configuration also allows the biosensor to be used in real‐time environmental monitoring. The herbicides atrazine, isoproturon, and propanil were detected within 30 min at concentrations below 100 μ dm−3, while the herbicide bromoxynil was only detected after several hours at mg dm−3 concentrations. Good sensor stability was obtained in the absence of pollutants, with more than 24 h of continuous monitoring being achieved. © 1993 John Wiley & Sons. Inc.
Using the metabolic capacity of rhodobacter sphaeroides to assess heavy metal toxicity
Authors: Balsalobre C. , Calonge J. , Jiménez E. , Lafuente R. , Mouriño M. , Muñoz M. T. , Riquelme M. , Mas‐castellà J.
Published: October 2006

Heavy metals can produce differential toxic effects on bacterial growth depending on the kind of metabolism the cells are using in relation to oxygen. Rhodobacter sphaeroides is a purple, nonsulfur, photosynthetic, gram‐negative bacterium that grows preferentially in anaerobic conditions acting as a photoheterotroph, but it can also behave as a photoautotroph. In aerobic conditions, this microorganism has a chemoheterotrophic metabolism. Aerobic and anaerobic metabolism may differ in their susceptibility to heavy metal toxicity. The metabolic duality of R. sphaeroides allowed us to assay this issue.

After incubation of R. sphaeroides, several indicators of bacterial growth such as optical density, dissolved oxygen concentration, protein content, and pigment content were determined. The parameter values obtained showed that the inhibitory effect exerted by zinc and cadmium on R. sphaeroides was stronger in aerobic conditions than in anaerobic ones. Microbial growth was considerably reduced when heavy metal concentration was higher than 1 mg L−1. Besides, R. sphaeroides was quite tolerant to copper. Cultures to which copper was added from 0.01 to 10 mg L−1 showed a relatively constant growth, both in aerobic and anaerobic conditions.

Thus, we have shown that assessment of heavy metal toxicity using bacterial tests must take into account that bacteria may react in a different way when grown in anaerobic environments.
Aflatoxin‐producing fungi associated with Nigerian maize
Authors: Aja‐Nwachukwu Jane , Emejuaiwe S. O.
Published: October 2006

Maize samples were obtained from different locations—namely Aba, Abakaliki, Afikpo, Okigwe, and Owerri—all in southeast Nigeria. Twelve mold species of the genera Aspergillus, Penicillium, Cladosporium, Alternaria, Fusarium, and Acremonium (Cephalosporium) were isolated. The presence of aflatoxin B1 was detected in 80% of the samples by the characteristic blue fluorescence that appeared on silica gel coated thin layer chromatography plates when viewed with a long‐wave ultraviolet radiation source alongside an aflatoxin standard. Eight isolates of the Aspergillus flavus group obtained from the maize samples were tested for aflatoxin production. Natural medium (maize) at 26°C and moisture content adjusted to no less than 20% was used. Aflatoxin was produced to some degree by 87.5% of the isolates. There was no aflatoxin production at a market moisture content of 5.4% and temperature of 25, 30, and 35°C. However, at 26°C and increased moisture contents of 22.3–24.9%, varying amounts of aflatoxin were produced. © 1994 by John Wiley & Sons, Inc..
Studies on Bacillus thuringiensis H‐14 strains isolated in Egypt. VI. Correlation between specific plasmids and δ‐endotoxin production
Authors: Abdel‐Hameed A. , Carlberg G. , Lindström K. , El‐Tayeb O. M.
Published: October 2006

The crystal‐producing (cry+) strains M1 and S128 of Bacillus thuringiensis H‐14, and several noncrystal‐producing (cry−) mutants derived from them, were analyzed for the presence of plasmid DMA in attempts to correlate δ‐endotoxin production with the presence of a specific plasmid(s). Plasmid analysis of both parent strains revealed the presence of several plasmids in the size range of 3.2–130 megadalton (Mdal). The two strains were found to have identical plasmid profiles, except that strain M1 contained an additional plasmid of 68 Mdal. All the cry− mutants derived from the cry+ parental strains had lost at least a 75 Mdal plasmid. On the other hand, plasmid analysis of cry+ derivatives cured of one or more plasmids revealed that they all harbored the 75 Mdal plasmid. This correlation was further confirmed by a plasmid transfer experiment in which strain M1 transmitted the crystal‐producing phenotype to a noncrystal‐producing B. thuringiensis recipient. Agarose gel electrophoresis showed that the 75 Mdal plasmid was present in all the isolated cry+ transcipients and absent in all the isolated cry− transcipients. These results demonstrate that the structural genes for the δ‐endotoxin in the isolated strains of B. thuringiensis H‐14 are borne on the 75 Mdal plasmid. © 1994 by John Wiley & Sons, Inc..
Fertilizer applications, nitrate loading patterns, water resources quality and their ecotoxicological implications in Awka area of Nigeria
Authors: Ezeonu F. C. , Egboka B. C. E. , Aze S. S.
Published: October 2006

Nitrogen fertilizer applications at the mean rate of 500 kg ha−1 nitrogen–phosphorus–potassium, 280 kg ha−1 urea, and 200 kg ha−1 calcium ammonium nitrate reported for the year 1990 in the Awka area of Nigeria exceeded the recommended doses for the region. An inestimable amount of these are unabsorbed by plants and are leached as soluble nitrates into surface and groundwater environments. © 1994 by John Wiley & Sons, Inc..
Rapid toxicity assessment using esterase biomarkers in Brachionus calyciflorus (rotifera)
Authors: Burbank Susan E. , Snell Terry W.
Published: October 2006

We have developed biomarkers of sublethal toxicity in the freshwater rotifer Brachionus calyciflorus based on the reduction of enzyme activity. Esterase and phospholipase A2 activity was quantified in single rotifers using image analysis and a fluorescence detection system. Esterase activity was localized in the gut and phospholipase A2 activity in the corona of females. Quantitation of enzyme activity demonstrated that toxicant stress reduced activity in a dose‐dependent manner. Concentration‐response relationships are described for 10 compounds representing a variety of toxicant classes and NOECs are reported. Esterase and phospholipase A2 activities were generally less sensitive end points than reproduction NOECs, but usually were more sensitive than LC50s. Since in vivo enzyme activity can be assessed in 1 h, these biomarkers will be useful where rapid results are important. The cost of performing in vivo enzyme inhibition tests is substantially less than traditional whole animal tests because these require three times more person‐hours to execute. Obtaining test animals by hatching cysts, their sensitivity to toxicants, and the rapid results make the rotifer esterase and phospholipase A2 tests good candidates for inclusion in a test battery for rapid toxicity assessment. © 1994 by John Wiley & Sons, Inc..
Physiological stress in fish during toxicological procedures: A potentially confounding factor
Authors: Pottinger T. G. , Calder G. M.
Published: October 2006

An increasing body of evidence suggests that stress may modulate the response of an animal to toxicological challenge. The degree of stress inherent in the procedures comprising a fish LC50 study (OECD guidelines for the testing of chemicals, “Fish, Acute Toxicity Test” No. 203, adopted May 12, 1981) was assessed by measuring plasma cortisol levels (rainbow trout) and whole‐body levels of immunoreactive corticosteroids (zebra fish). Aspects of the 96 h LC50 protocol which were found to evoke corticosteroidogenic activity in the test fish included transfer from holding tanks to test tanks, tank transfer during semistatic procedures, and disturbance associated with water quality measurement. There was evidence for acclimation of the fish to repetitive stimuli such as tank transfer, but, overall, the data suggest that the 96 h test protocols evoke a state of chronic stress in the test population. The removal of fish from test vessels during longer term studies was also found to evoke a stress response in fish remaining within the vessel, suggesting that these conditions may expose test fish to a regime of intermittent periods of acute stress. The possibility that physiological stress may interfere with the accurate estimation of toxicological end points was examined. In three independent LC50 tests the toxicity of the arylmethane dye, malachite green, to rainbow trout was found to be markedly and consistently reduced when the degree of disturbance and handling during the test period was minimized. © by John Wiley & Sons, Inc.
Tissue lipid levels of the clam, Villorita cyprenoides var. cochinensis, following exposure to endosulfan, malathion, and methyl parathion
Authors: Sujatha C. H. , Nair S. M. , Chacko J.
Published: October 2006

Sublethal stress of toxicants on organisms is generally measured through metabolic changes. The effects of three pesticides (endosulfan, malathion, and methyl parathion) on tissue lipid levels in the estuarine bivalve, Villorita cyprenoids var. cochinensis, have been measured. The reduction in lipid content was expressed as a function of the pesticide concentrations and the duration of the exposure periods (24, 48, 72, and 96 h). The results point to the existence of a direct relationship between the applied stress and the fall in the lipid content. The order of toxicity was endosulfan > malathion > methyl parathion. The depletion in lipid content observed may reflect an adaptive response of the organism to pesticide stress. Thus lipids in bivalves have been shown to be an important reserve material that may be utilized under stressed conditions as an energy source. © by John Wiley & Sons, Inc.
Inhibition of respiration of activated sludge: Variability and reproducibility of results
Authors: King E. F. , Painter H. A.
Published: October 2006

Assessment of the toxicity of chemicals to the respiration of activated sludge microorganisms is a relatively simple and reproducible method when applied to a standard population of bacteria. However, activated sludge is, by nature, a variable commodity, and varying results are often reported. Within‐plant variations can occur from day to day as a result of shifts in the bacterial population, probably caused by changes in the strength of components of the sewage feed. Between‐plant variations can be considerably greater. Factors such as differing operating conditions and presence of industrial waste waters in the sewage can result in differing species composition of the sludge, which, in turn, may account for differing biooxidation rates of components of the waste water and thus different respiration rates. Sludge from different sources, and/or grown under different conditions, may also vary in response to inhibitors, because of varying degrees of reaction of some inhibitors with non‐living sludge components. Therefore, in practice, it has been usual to consider EC50 values from the inhibition of respiration of activated sludge test in terms of order of magnitude. Variations in EC50 results of the ‘ISO’ inhibition of respiration test have been quantified for a number of chemicals, both within and between batches of sludge, and with sludges from different sources. The coefficient of variation of EC50 results within batches of sludge was found to be approximately 9%. Between batch and between source variations were 28–76% depending on the test chemical.
Rapid test for toxicity in wastewater systems
Authors: Dutton R. J. , Bitton G. , Koopman B.
Published: October 2006

A test employing sewage bacteria was developed for rapid screening of chemical toxicity in wastewater systems. The procedure entails incubation of sewage samples with 2–(p–iodophenol)–3–(p–nitrophenyl)–5–phenyl tetrazolium chloride (INT) followed by concentration of bacteria on membrane filters, dissolution of the filters with concomittant extraction of INT‐formazan in dimethylsulfoxide, and spectrophotometric determination of the INT‐formazan.

Preliminary results indicate that the test is sensitive to both heavy metals and toxic organics. Chemical concentrations inhibiting 50% of the response in controls (IC50's) for Ni+ +, Zn+ +, Cu+ +, Hg+ +, phenol, 3,4‐dichlorophenol, sodium dodecyl sulfate, tetrachloroethylene and formaldehyde were 4.8, 3.9, 0.59, 0.07, 1531, 74, 156, and 11.6 mg/l, respectively. IC50 values obtained with sewage from different collection systems or with sewage from the same system sampled on different days were in good agreement.
Methods for assessment of heavy metal toxicity towards fungi and yeasts
Authors: Gadd G. M. , Mowll J. L. , White C. , Newby P. J.
Published: October 2006

The analysis of K+ release, respiration rates and tests relying on diffusion processes in agar medium have applications for the study and assessment of heavy metal toxicity towards fungi and yeasts. Such techniques have been seldom exploited for this purpose but can provide information not only on toxicity but also on morphological and physiological responses towards heavy metals.
Use of the ATP bioassay to assess toxic effects in marsh treatment systems
Authors: Seyfried Patricia L. , Desjardins Robert M.
Published: October 2006

A firefly luciferase bioluminescent assay of bacterial adenosine triphosphate (ATP) was used to measure the toxic effects of metal ions on six bacterial genera isolated from two geographically different marsh treatment systems. The toxicity of eleven different metals, as well as metal mixtures, was monitored using the agar plate test and the resazurin reduction test in addition to measurement of intracellular ATP. All the organisms surveyed tended to be sensitive to much lower concentrations of metals when the metals were present in mixtures. Isolates from a marsh system constructed on normal soil exhibited lower metal resistance patterns than organisms isolated from a marsh built on mine tailings. The intracellular ATP assay appeared to be the most sensitive method of determining the viability of bacterial cells following metal treatment.
Microbial toxicity and degradation test methodology: An industrial perspective
Authors: Gledhill William E.
Published: October 2006

Numerous federal regulations are concerned with the release or potential release of chemicals to the environment. Testing that has been proposed under the Toxic Substances Control Act for microbiological effects and persistence has certain limitations. Improved and extremely sensitive procedures are now available to assess chemical toxicity to microorganisms and persistence at environmentally realistic concentrations. This paper discusses these aspects and presents preliminary data for a novel method based on thymidine uptake which offers promise as a routine sensitive assay for the effects of chemicals on biomass, and vice versa. The method has been shown to provide useful data about the persistence of chemicals at realistic environmental concentrations.
Toxicity of lead on microorganisms: Interaction with protein content of culture medium
Authors: Oliveira J. Santos , Rodrigues A. , Mendes B. , Dias M.
Published: October 2006

Lead is a significant environmental pollutant in Portugal, mainly as a consequence of its use as an antidetonant in gasoline. Due to the vast annual gas consumption, evidence of lead emission has been found in the air, soil, plants, and water. Concentrations of lead in Lisbon waste waters average 0.15 mg/L, with occasional levels reaching 1.5 mg/L. The biodegradability of these waste waters is affected by lead. To understand the interaction between lead toxicity and protein concentrations, a study was initiated using selected strains of Proteus mirabilis and Klebsiella pneumoniae and synthetic effluents. The toxicity of lead to bacteria was noted by an increase in the cell's metabolic activity, and a greater induction of ATP and RNA contents. However, bacterial replication was evidently uninhibited by the lead content in the test medium. While high peptone content in the growth medium caused an increase in the cell's biosynthesis, increased lead concentrations in the growth medium resulted in a substantial loss of metabolic product. This complex interaction was apparently responsible for lead's toxicity to bacteria.
Identification of Plasmid Containing Bacteria in an Activated Sludge Reactor
Authors: Trevors Jack T.
Published: October 2006

Samples taken from an activated sludge reactor used for the biodegradation of metal cutting fluids were studied for the presence of plasmid‐containing bacteria. Twenty different bacterial isolates contained one or more plasmids. After numerous transfers of the isolates through LB broth, 55% of the plasmids were spontaneously lost as evidenced by agarose gel electrophoresis. Eighty percent of the isolates were resistant to one or more antibiotics, 65% resistant to two or more antibiotics, 40% resistant to three or more, 20% resistant to four or more and 5% resistant to five antibiotics. The isolates were also tested for their sensitivity to several common metals. This study has demonstrated that activated sludge is a natural reservoir for plasmid‐containing bacteria involved in biodegradation of wastes.
Application of enzyme assays for toxicological water testing
Authors: Obst U. , Holzapfel‐Pschorn A. , Wiegand‐Rosinus M.
Published: October 2006

Two different criteria for biochemical toxicity testing are proposed: the effect of hazardous substances on the metabolic activity of the natural microflora and the determination of such substances by a standardized enzyme testing system. To measure effects on the microbial metabolic activity, there are various simple in vivo enzyme assays using chromogenic or fluorogenic substrates. To detect unknown substances with harmful effects, there exist some in vitro enzyme tests with commercial preparations of defined purity and sensitivity. The performance, sensitivity, and some data of the practical use of such tests are presented. The applicability of the two testing protocols is discussed.
The Bacillus subtilis/microsome rec‐assay for the detection of DNA‐damaging substances in waters of a night soil treatment plant
Authors: Matsui Saburo
Published: October 2006

A Bacillus subtilis/microsome Rec‐assay was improved by the introduction of a period for the test sample to interact with the bacteria before cultivation in a Monod tube. This method is called the “liquid B. subtilis/microsome Rec‐assay method.” Evaluation of the Rec‐assay is presented in terms of R50, S‐probit, and RS, which were analyzed with computer programs developed on Probit theory and Target theory. Results could be classified into four categories: strong DNA damaging, DNA damaging, not DNA damaging, and reverse. Application of the Rec‐assay to water samples from a night soil treatment plant showed that raw night soils contained a considerable amount of DNA‐damaging substances. The amount of DNA‐damaging substances in test samples was measured in terms of a new indicator, “Rec‐volume.” After the biological treatment of nitrification and denitrification process, and the tertiary treatment of chemical coagulation and floatation for phosphorus removal, DNA‐damaging substances were effectively reduced in the treated water. Following the tertiary treatment, ozonation was practiced for disinfection and color removal in this plant. Ozonation also showed effective reduction of DNA‐damaging substances in the treated waters. In order to concentrate DNA‐damaging substances in test samples, the adsorption method of XAD‐2 and XAD‐8 resins followed by ether and methanol extraction was employed.
Influence of some experimental factors on metal toxicity to Selenastrum capricornutum
Authors: Vasseur P. , Pandard P. , Burnel D.
Published: October 2006

Toxic effects of Cd++, Cu++, and Zn++ on Selenastrum capricornutum were evaluated in various experimental conditions in order to determine the influence of the composition of the test medium and of the concentration of the algal biomass on the toxicity of metals to algae. Four media recommended in different standard methods (International Standards Organisation, U.S. Environmental Protection Agency, Organisation for Economic Cooperation and Development, AFNOR) were compared. Results of algal bioassays showed that the sensitivity of algae during the exponential growth phase was not influenced by the concentration of macronutrients in the medium.

On the contrary, the numeration of the algal suspensions tested appeared determinant as the toxicity decreased when the quantity of algal inoculum was increased: with inocula of nearly 3 × 104, 2.5 × 105, 6 × 105, and 3 × 106 cells/mL at t = 0, the corresponding EC50 were 46, 80, 110, and up to 300 μg/L for cadmium, 10, 65, 105, and 280 μg/L for copper, and 90, 163, 225, and 365 μg/L for zinc. Modifications in the speciation forms of the metal induced by a rapid increase of the pH could be responsible for part of this decreased toxicity.
Testing pesticide fate and side effects in the terrestrial environment
Authors: Torstensson L.
Published: October 2006

Tests are needed to make predictions of pesticide fate and pattern of influence on nontarget organisms in the terrestrial environment. Problems connected with testing and the evaluation of test results are discussed. It is argued that if the effects of factors influencing qualitative and quantitative properties of pesticide decomposition could be expressed in mathematical form, such as equations with rate constants, this would be an efficient test system. There are two approaches to testing the influence of a pesticide on soil organisms; to establish the magnitude and type of any response, or to ascertain whether or not a pesticide constitutes a hazard to the soil organisms and consequently to soil fertility. It is concluded that there is a pressing need for development of means of interpreting data obtained in tests with pesticides.
Rapid, specific, defined substrate technology for the simultaneous detection of total coliforms and Escherichia coli
Authors: Edberg Stephen C. , Allen Martin J. , Smith Darrell B.
Published: October 2006

The Autoanalysis Colilert (AC) test is a modification of the defined substrate technology designed to enumerate specific target microbe(s) from a mixture. All ingredients are present in the tube or vessel in powdered form. The AC test is simple to perform—a measured amount of water is added to test tubes (for the most probable number test) or vessel [Presence/Absence (P/A) test]. After incubation, the development of a yellow color is specific for total coliforms. Fluorescence in the same tube(s) is specific for Escherichia coli. No confirmatory or completed tests need be performed. A national United States evaluation covering all sources and processing of water was conducted. The AC test was compared to multiple tube fermentation (quantitative) and P/A (qualitative) Standard Methods procedures. Testing protocol was that of the U.S. Environmental Protection Agency's Environmental Monitoring and Support Laboratory for establishing equivalency between methods. The quantitative comparison showed that the AC test was slightly more sensitive than MTF. For two of five sites it was more precise; for the other three it was equal. For the qualitative P/A the AC and Standard Methods analysis agreed 94%. Specificity of the AC method was established by subculturing a species of total coliform or E. coli from positives. The AC test was easy to use, can be performed by large and small utilities, and is less expensive than current methods. It can simultaneously, specifically enumerate total coliforms and E. coli without the need for confirmatory tests.
Waterborne Klebsiella and human disease
Authors: Duncan I. B. R.
Published: October 2006

Klebsiella occurs widely in nature and is often present in surface waters used for human consumption or for recreational purposes. The organism can survive in water distribution systems despite chlorination. Many strains give rise to a positive fecal coliform test even when they are the only organisms present in the water sample. The public health significance of Klebsiella in water is therefore an important concern. In the past Klebsiella was thought to be a significant pathogen in the community causing serious primary pneumonia, but such cases are now extremely rare. Serious Klebsiella infections are today commonly seen only in hospital patients whose resistance has been impaired by their primary disease condition. There is no evidence that waterborne Klebsiella play any significant part in the epidemiology of these hospital‐acquired infections. Klebsiella in water supplies should therefore not to be considered a hazard to human health.
Influence of metals on oxygen uptake, carbon dioxide fixation, and cytochrome reduction in Nitrobacter Agilis
Authors: Tsai Yu‐Li , Tuovinen Olli H.
Published: October 2006

Oxygen uptake coupled with nitrite oxidation by washed cell suspensions of Nitrobacter agilis was tested in the presence of copper, nickel, aluminum, uranyl, and molybdate ions. Copper ion was slightly stimulatory at low concentrations and strongly inhibitory at 17 mM. Molybdate ion showed either slight enhancement or no inhibition at all test concentrations. With the other test ions, inhibition of oxygen uptake was observed. Carbon dioxide fixation was generally more sensitive to metal ions than was oxygen uptake. Cytochrome reduction in washed cells of N. agilis was demonstrated in the presence and absence of metal ions. Cytochrome aa3 and cytochrome a1 (α‐peak at 590 nm) were sensitive to aluminum, uranyl, and molybdate ions, whereas cytochrome c (β‐peak at 520 nm) was insensitive to test ions. All metal ions inhibited the reduction of cytochrome a1 (γ‐peak at 438 nm). This inhibition decreased when the concentration of copper and molybdate was increased to 1.7 mM. Only aluminum and nickel ions demonstrated a concentration‐dependent inhibition of cytochrome a1 (438 nm). The test ions blocked the activity of cytochrome c (α‐peak at 550 nm). The inhibition of cytochrome c at 415 nm (γ‐peak) was also apparent.
Effect of selenium on microbial communities in laboratory microcosms and outdoor streams
Authors: Pratt James R. , Bowers N. J.
Published: October 2006

Ecological effects of selenium (as sodium selenite) on naturally derived microbial communities were evaluated in laboratory microcosms and in outdoor experimental streams at the U.S. Environmental Protection Agency (U.S. EPA) Monticello Ecological Research Station (MERS). Microcosms were continuously dosed for 21 days at selenium concentrations ranging from 0 to 160μg Se/L. Outdoor streams were continuously dosed at 0, 10, and 30 μg Se/L, the highest concentration approximating the current U.S. EPA water quality criterion. In laboratory microcosms, protozoan species richness was reduced by 20%, and chlorophyll and hexosamine levels were reduced by 40% at μ80 μg Se/L. Total biomass and carbohydrate levels decreased with increasing Se, but these effects were not significant. Selenium had no effect on microcosm production to respiration ratios. In outdoor streams, microbial community biomass collected on artificial substrata was 2–3 times greater than in the laboratory. In general, adverse effects were not observed, confirming laboratory estimates of no adverse effects at <80 μg Se/L. However, low doses (10μg Se/L) consistently stimulated microbial biomass (protein, chlorophyll, hexosamine) and elevated production to biomass (P/B), consistent with reports of Se stimulation of algal growth. The highest Se dose (30 μg/L) caused decreased primary production and decreased P/B compared to controls. Experiments showed that ecological responses of laboratory microcosms and outdoor experimental ecosystems are similar, and are at least as sensitive as standard toxicological responses.
Biotoxicity of tributyltin acrylate polymers
Authors: Joshi Ravi R. , Gupta Sudhir K.
Published: October 2006

The biotoxicity of 3 tributyltin monomers, their homopolymers, and 8 copolymers of tributyltin α‐chloroacrylate (TCA) against 2 microorganisms (Pseudomonas aeruginosa, Sarcina lutea) and the larvae Artemia salina (Naupli II) is reported. Biotoxicity of the TCA monomer was found to be lower than that of the tributyltin acrylate (TBTAA) monomer. However, the toxicity of homopolymers of TCA was higher than that of TBTAA. The toxicity of copolymers increased with an increase in tributyltin content in the polymer. The biotoxicity could not be correlated with the chemical structure of the polymer.
Homer proteins control neuronal differentiation through IP3 receptor signaling
Authors: Tanaka Masahiko , Duncan R. Scott , McClung Nathalie , Yannazzo Jo-Ann S. , Hwang Sung-Yong , Marunouchi Tohru , Inokuchi Kaoru , Koulen Peter
Published: October 2006

Neurons expand, sustain or prune their dendritic trees during ontogenesis [Cline, H.T. (2001). Dendritic arbor development and synaptogenesis. Curr. Opin. Neurobiol. 11, 118–126; Wong, W.T. and Wong, R.O.L. (2000) Rapid dendritic movements during synapse formation and rearrangement. Curr. Opin. Neurobiol. 10, 118–124] which critically depends on neuronal activity [Wong, W.T., Faulkner‐Jones, B.E., Sanes, J.R. and Wong, R.O.L. (2000) Rapid dendritic remodeling in the developing retina: dependence on neurotransmission and reciprocal regulation by Rac and Rho. J. Neurosci. 20, 5024–5036; Li, Z., Van Aelst, L. and Cline, H.T. (2000) Rho GTPases regulate distinct aspects of dendritic arbor growth in Xenopus central neurons in vivo. Nat. Neurosci. 3, 217–225; Wong, W.T. and Wong, R.O.L. (2001) Changing specificity of neurotransmitter regulation of rapid dendritic remodeling during synaptogenesis. Nat. Neurosci. 4, 351–352.] and sub‐cellular Ca2+ signals [Lohmann, C., Myhr, K.L. and Wong, R.O. (2002) Transmitter‐evoked local calcium release stabilizes developing dendrites, Nature 418, 177–181.]. The role of synaptic clustering proteins connecting both processes is unclear. Here, we show that expression levels of Vesl‐1/Homer 1 isoforms critically control properties of Ca2+ release from intracellular stores and dendritic morphology of CNS neurons. Vesl‐1L/Homer 1c, an isoform with a functional WH1 and coiled‐coil domain, but not isoforms missing these features were capable of potentiating intracellular calcium signaling activity indicating that such regulatory interactions function as a general paradigm in cellular differentiation and are subject to changes in expression levels of Vesl/Homer isoforms.