摘要:

AbstractThe temperature dependence of liver microsomal CYP2E1 (cytochrome P450 2E1) activity was examined in selected genotypes of the viviparous fishPoeciliopsisActivity of this enzyme, as a function of incubation temperature, was determined by measuring 6 OH‐chlorzoxazone formation from chlorzoxazone, a specific CYP2E1 substrate Chlorzoxazone 6 hydroxylase activity was examined among five species ofPoeciliopsis, as well as among nine genotypes within a species,P monachaAmongPoeciliopsisgenotypes,P monachacontained the greatest activity, 9 5 ± 1 5 U (where 1 U is defined as 1 μg 6 OH chlorzoxazone produced/min/mg protein,n= 6) with a temperature optimum (To) of 25°C The lowest activity was inP occidentalis, 0 65 ± 0 11 U, with aToof 27 to 28°C,P prolifica, P fasciata, P lucida, andP viriosahad intermediate levels of activities, 1 1 to 5 5 U, andTofrom 25 to 31°C To determine if metabolic differences exist within species, enzyme activity was examined from nine genotypes ofP monachaby comparing expression amongP monacha‐lucidahybrids These hybrids were given identical paternal genomes oflucidabut retained the original maternalmonachagenomes sampled from wild gene pools The greatest activity was found in genotype T70 3PCw, 3 6 ± 0 1 U, at aToof 29°C, and the lowest was in genotype SV73 7s, 0 40 ± 0 12 U, at aToof 27°C The other naturally occurring genotypes, M65 24, M65–26 SV73 7v, as well as the laboratory produced synthetic hybrids, Syn4 and Syn5, had intermediate activities, 0 73 ± 0 38 to 2 1 ± 0 69 U, andToof 25 to 27°C No hybrid had activity levels as high as the maternal parent,P monacha, and only one had aToas low as either parent Apparently the genes involved in xenobiotic activity vary widely among the closely related species ofPoeciliopsisbut also within species suggesting that these phenotypes can be acted upon b

ISSN:0730-7268    

DOI:10.1002/etc.5620140101

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThis article describes the results of laboratory batch solubility experiments with five chlorinated solvents (chloroform, carbon tetrachloride, 1,1,1‐trichloroethane, trichloroethylene, and tetrachloroethylene) present alone or in binary or ternary mixtures. The measured aqueous solubility values of the pure compounds revealed significant deviation from the widely used literature values for trichloroethylene and tetrachloroethylene. The experiments with binary and ternary solvent mixtures showed that the chlorinated solvents used in this study exhibited close to ideal behaviour. That means the concentration of an organic compound in the aqueous phase in equilibrium with an organic phase can be described as the mole fraction in the organic phase times the aqueous solubility of the pure compound. The UNIFAC (universal quasi chemical functional group activity coefficients) method was used in this study to estimate the appropriate activity coefficients for the experiments with binary mixtures. The UNIFAC method predicted nonideal behaviour for some of the mixtures. However, the deviation was only significant at relatively low mole fractions. Experiments indicated that the assumption of ideal behaviour for the chlorinated solvents used in this study is a reasonable one. The assumption of ideal behaviour simplifies the use of models to simulate the dissolution of chlorinated solvent mixtures in ground wate

ISSN:0730-7268    

DOI:10.1002/etc.5620140102

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe presence of chloride ions in the Microtox® test can cause problems when testing metal toxicity, both due to extraction of metals from solid samples and formation of chloro complexes of metals in the liquid phase. To investigate alternatives to NaCl in the Microtox test, the toxicity of Cu, Cd, Pb, and Zn toPhotobacterium phosphoreumwas tested in 28 osmotic surrogates for NaCl. It was found that Na+must be present to keep the blank luminescence stable for 30 min. The results point to NaClO4as the most satisfactory surrogate solution as it has an inert behaviour and does not form complexes with any metal of environmental interest. Raw, digested, and reference sewage sludges were tested in the osmotic surrogates. The EC50 values for sludges were lower in solutions of NaNO3, Na2SO4, and NaClO4, and higher in sucrose, mannitol, and KCl, compared to NaCl. NaClO4can be recommended as an osmotic surrogate for sewage sludge testing. Another problem with the Microtox assay is the lack of pH control in the cuvette. Copper toxicity tests were carried out in Tris buffer and KH2PO4at two different concentrations and at pH 7 and 8. The results show that 1 mM phosphate buffer, pH 7.0, can be recommended for solid samples. However, owing to formation of KClO4a buffer containing potassium is not recommended in combination with NaClO4

ISSN:0730-7268    

DOI:10.1002/etc.5620140103

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractPast studies have shown that extremely high concentrations of alachlor in soil can depress microbial biomass and bioactivity; consequently, degradation of alachlor is also inhibited. Studies were undertaken to further characterize the relationship among alachlor concentration in soil, dehydrogenase activity (as an indicator of microbial activity), and degradation rate. Alachlor initially inhibited soil dehydrogenase in soil at concentrations as low as 250 mg/kg with prolonged inhibition through at least 21 d occurring at concentrations ≥750 mg/kg. The inhibition of soil dehydrogenase was associated with a prolonged persistence of alachlor beyond the previously reported ranges of half‐life observed at normal field rates of application. Amendment of soil with cornmeal caused degradation of 10 to 250 mg/kg alachlor at rates substantially faster than previously reported for laboratory incubations. At alachlor concentrations ≥750 mg/kg, dehydrogenase activities in amended soils surpassed levels in corresponding no‐pesticide controls after 21 d; coincidentally,>50% of the initially added alachlor had degraded during the same period. These results suggested that stimulation of microbial bioactivity by addition of organic amendments may enhance co‐metabolism of high concentrations of pesticide

ISSN:0730-7268    

DOI:10.1002/etc.5620140104

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe polysubstrate monooxygenase (PSMO) system response to hydrophobic xenobiotics is both intensive in oxidizing power and extensive in enzyme quantity. Under in vitro pseudo‐first‐order rate conditions the extensive properties become irrelevant, and the intensive rate‐determining step depends on chemical structure. Xenobiotics react with PSMO either as inducers (adaptation domain) or as substrates (reaction domain) to produce “intended” hydroxylation, but “accidental” oxidations may also occur. Both the induction of intensive oxidizing power in the adaptation domain and the efficiency of reaction in the reaction domain depend on the strength of the weakest CH bond in the xenobiotic, consistent with either a free radical or an ionic SE2 reaction process. Only the ionic SE2 mechanism is sensitive to the electrical charge on the carbon atom of the weakest CH bond. In this study systematic “treatment” of simple hydrocarbon structures by adjacent polarizing heteroatoms N, Cl, and O inhibited substrate metabolism in direct proportion to their polarizing power. With this evidence of preferential SE2 behaviour, a QSAR is proposed that allows prediction of four types of disease end points. These arise as combination of conditions of intended or accidental oxidations combined with release of metabolites into cyt

ISSN:0730-7268    

DOI:10.1002/etc.5620140105

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractAn analysis of digitized three‐dimensional video records of free‐swimmingDaphnia pulexidentified six measurements of swimming behavior that can be used to quantify individual behavioral responses to pesticides or natural chemical signals. Protocols are given for measuring the parameters that showed statistically significant changes in pesticide treatments. The most efficient experimental design would involve observing as many animals as possible, with one observation per animal. Parameters most likely to be useful in future studies are velocity, turning angle, upward and downward angles during hops, variance in vertical position, and hopping frequency. The parameters varied in usefulness, defined as the ratio of within‐treatment to among‐treatment variance (Fratios). Velocity was the most useful (i.e., had the highestFratio); hopping frequency was the least useful.Daphniaexhibited three kinds of swimming behavior, as defined by eight parameters: (a) “spinning” (extreme and continuous escape response) to acutely toxic levels of Carbaryl (40 ppb); (b) “irritation” (an increase in escape‐like behavior) to low levels of Carbaryl (1 ppb); and (c) “null” behavioral responses toChaoborus‐conditioned water, in which there was no detectable change in any measurement of swimming behavior. In predation trials, bluegill sunfish preferentially selected individuals showing “spinning” behavior. Results from this and other studies ofDaphniaswimming behavior suggest a conservative‐swimming hypothesis for understanding constrain

ISSN:0730-7268    

DOI:10.1002/etc.5620140106

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractAerated and nonaerated windrow composts of explosives‐contaminated sediments at the Umatilla Army Depot Activity (UMDA, Hermiston, OR) were characterized chemically and toxicologically as a function of composting time. The concentrations of explosives in organic solvent extracts of the composts and in the aqueous leachates of the composts, the bacterial mutagenicity of organic solvent extracts from the composts, and the toxicity of aqueous leachates from the composts toCeriodaphnia dubiaall declined rapidly (97.5%, respectively). Extractable mutagenicity declined 99.7 and 97.9%, respectively, for strains TA‐98 and TA‐100 (without S‐9 metabolic activation) in the nonaerated compost. The two types (aerated and nonaerated) of windrow composts had about the same level of efficiency in lowering leachable toxicity (by 92% and 87%, based on reductions inC. dubiasurvival and fecundity, respectively). Thus, windrow composting appeared to be at least as effective as static‐pile and mechanically stirred composting evaluated previously. Windrow composting also appeared to be somewhat more effective for HMX trans

ISSN:0730-7268    

DOI:10.1002/etc.5620140107

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractExperiments were conducted to study the absorption, phytotoxicity, and internal distribution of mercury (Hg) in tobacco plants (Nicotiana miersii) exposed to elemental mercury vapor (Hg0) through the shoot or to ionic mercury (Hg2+) through the root. Tobacco plants grown hydroponically were exposed to varying Hg0treatment concentrations (0 to 100 mg/m3) in a specially designed chamber system, examined for visible symptoms of toxicity, and analyzed for Hg content by cold vapor atomic absorption, 1 and 10 d following treatment. In a separate experiment, the roots of hydroponic tobacco plants were exposed to Hg2+in the form of a mercury chloride solution (0 to 100 μg/ml) and analyzed for growth changes and Hg content. Accumulation, toxicity response, and Hg distribution differed between the two exposure routes, even when internal Hg concentrations in the treated plants were similar. Plants exposed to Hg0accumulated Hg in the shoots with no movement to roots. Visible signs of Hg0stress were apparent at 1.0 mg/m3exposure levels and greater. Root‐exposed plants showed accumulation of Hg in the roots with movement to the shoots by day 10. Inhibition of root and shoot growth occurred at treatment levels of 1.0 μg/ml and greater with very limited tissue damage at higher treatment lev

ISSN:0730-7268    

DOI:10.1002/etc.5620140108

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA microcosm consisting of water, sediment, and air compartments was used to simulate mercury geochemical cycling in a mercury‐contaminated (μg L−1) pond at Oak Ridge, Tennessee. Total and dissolved mercury and total methylmercury were analyzed in water and sediment; total gaseous mercury and head‐space mercury were analyzed in the water and head space, respectively. The production of gaseous mercury was correlated to dissolved mercury (0.2‐μm filtration), and methylmercury was mainly produced in the sediment compartment. Addition of mercuric chloride to the system increased the production of head‐space mercury by a factor of 10 but did not affect the methylation rate. Saturation of gaseous mercury in microcosm water varied from 480 to 1,500% of the solubility of elemental mercury and was controlled by unidentified factors. The microcosm maintained stable conditions for up to 3 weeks, and a mass balance indicated that it reasonably simulated the cycling of mercury in the pond. This microcosm could be used to test remedial treatments aimed at decreasing the amount of mercury that is available for accumulati

ISSN:0730-7268    

DOI:10.1002/etc.5620140109

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA carcinogenicity‐ and mutagenicity‐directed fractionation approach was used to identify the carcinogenic compounds in contaminated sediments that are putatively responsible for the high prevalence of tumors in bottom‐dwelling fish from Hamilton Harbour, Ontario. Mutagenic activity was detected with Ames tester strains (TA98, TA100) in relatively nonpolar fractions of sediment extract containing PAHs and nitrogen‐containing aromatic compounds (NCACs). These fractions were also carcinogenic in an in vivo carcinogenicity bioassay with rainbow trout (Oncorhynchus mykiss). When a more polar extract fraction was tested for mutagenicity and carcinogenicity, weak mutagenic activity was detected with anO‐acetyltransferase‐enriched Ames tester strain (YG1024), and weak carcinogenic activity was detected in the rainbow trout assay. These data indicate that PAHs in contaminated Hamilton Harbour sediments are potent fish carcinogens, but it is also evident that other organic compounds in the sediment, such as NCACs and nitroarenes, may contribute to carc

ISSN:0730-7268    

DOI:10.1002/etc.5620140110

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY