摘要:

AbstractThe DNA‐cell binding (DCB) assay grew from our early studies demonstrating that in the presence of carcinogenic chemicals, radioactively labeled nucleic acids attached strongly to isolated cellular membranes and to intact prokaryotic and eucaryotic cells. A survey of over 300 chemicals revealed that this test is capable of correctly predicting carcinogenic potential in more than 95% of cases. Recently we began using formaldehyde‐treatedEscherichia coliindicator cells and noted that the accuracy of prediction and the sensitivity of the test are even greater. For example, a class of noncarcinogenic, intercalating agents that showed as false positives in the original study, scored negative in this modified version of DCB test. This assay has several advantages over other rapid tests for genotoxicity, including simplicity, rapidity, economy, and reproducibility. As demonstrated by our studies on a number of diverse products, it is especially suitable for analyzing industrial and other environmental chemicals and their mixtures. The increased DNA‐cell binding is due to a property shared by most, if not all, carcinogenic agents—their ability to produce macromolecular adducts between proteins and nucleic acids, as well as inter‐ and intramolecular complexes in DNA. The latter class of adducts is responsible for inducing chromosomal transposition‐like events that we observed in a separate set of experiments using transformation ofBacillus subtilisfor measuring distances between genetic markers. In these experiments markers were stably transferred to a different position on the chromosome as the result of DNA‐exposure to an ultimate carcinogen,N‐acetoxy N‐acetyl‐aminofluorene. If, as many investigators believe, the specific chromosomal translocations are the cause of neoplasia, the high predictive potential of the DCB test may be due to its capability to measure the production of specific macro

ISSN:0884-8181    

DOI:10.1002/tox.2540010402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractA rapid, simple, and inexpensive biochemical test for use in the mass screening of chemical compounds for toxicity was developed. The test is based on direct measurement of the inhibition of microbial dehydrogenase activity, as affected by a toxicant, in a well buffered DMSO‐resazurin solution. The addition of 5% DMSO to the reaction mixture allows the toxicity determination of compounds with low water solubility, thus facilitating measurement of the effects of important environmental contaminants on microbiota. The test has been applied to 15 selected chemicals which represent a vast range of environmental contaminants. As well as a routine screening procedure for chemical toxicity, this new resazurin test can be used as a tool in the study of structure‐activity relations

ISSN:0884-8181    

DOI:10.1002/tox.2540010403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractDimethyl sulfoxide extracts of betel nut (100g/L) and betel leaf (100g/L), and methanol and water extracts of betel nut (100g/L) were found to inhibit dehydrogenase activity ofBacillus subtilis. In contrast betel nut (100g/L) extracted by petroleum ether showed no inhibitory effect. Thin layer chromatography, ultraviolet spectroscopy and total polyphenols estimation indicated that betel nut contained large amounts of polyphenols. On the basis of toxicity assessment, the results implied that betel nuts and betel leaves contained a hydrophilic element which was toxic to living cells.

ISSN:0884-8181    

DOI:10.1002/tox.2540010404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractAn acetate enriched, methanogenic culture was exposed to cyanide in various exposure modes and concentrations. Methanogenic assays were made with cyanide as the model toxicant. The following variables were studied: solids retention time, toxicant administration pattern, fate of radioactively tagged cyanide, retention of acclimation after elapsed time intervals, effect of previous exposure to cyanide, and efficacy of remedial treatment additives. The culture was able to successfully acclimate to the presence of up to 30 mg/L of cyanide—approximately 10 fold the concentration tolerated by an unacclimated culture. The severity and duration of inhibition of methane fermentation by a slug dose of cyanide was proportional to cyanide concentration. The recovery of the methane fermentation of acetate after a 1.5 mg/L dose of cyanide was not due to significant reduction of cyanide and/or its intermediates. The methanogens maintained their acclimation potential to cyanide after 60 days of cyanide free growth. Cysteine, thiosulfate and dithionite all reduced the toxic effect of cyanid

ISSN:0884-8181    

DOI:10.1002/tox.2540010405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractGrowth of 26 strains of sulfate‐reducing bacteria isolated from the environment was inhibited by two cationic surfactants, namely, Hyamine 2389 and Lutensit K‐LC at concentrations of 166 mg/1 or less. Hyamine 1622 (cationic) inhibited 21 strains at a concentration of 100 mg/1. Two strains were resistant to 100 mg/1 of Chloramine T, but 4 strains were resistant to 60 mg/1. Hydrogen peroxide at the concentration of 583 mg/1 was able to prevent the growth of 17 strains.Time‐kill tests indicated that the majority of the strains were sensitive to all tested biocides during the first few minutes of exposure which extended to about one hour at lower concentrations.Lowering the temperature during exposure of bacteria did not exert any substantial effect on the biocidal efficiency of the tested chemicals. Higher concentrations of the biocides may require the lowering or raising of the pH and in the presence of organic m

ISSN:0884-8181    

DOI:10.1002/tox.2540010406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractEcotoxicological effects of creosote contamination on benthic bacterial communities in the Elizabeth River, Virginia were investigated using both structural and functional microbial parameters. Parameters included direct counts, viable counts of heterotrophs and “cresol‐utilizers”, and bacterial production determined using the tritiated thymidine uptake method. Ancillary data included temperature, salinity, Eh profiles, concentrations of polycyclic aromatic hydrocarbons (PAHs), sediment granulometry and total organic carbon. Two reference stations in relatively nonpolluted areas were sampled for comparative data. Results indicated that cell specific and total heterotrophic bacterial production were depressed in a dose‐dependent manner with increasing sediment PAH concentrations. Sediment properties and seasonal changes in temperature appeared to modify the effects of PAHs on bacterial production. Direct bacterial counts and viable counts of total heterotrophs were depressed in the most contaminated sediments. Evidence of creosote adaptation was equivocal, with cresol‐utilizer densities not significantly elevated at contaminated stations. The presence of creosote was associated with shifts of Eh toward more negative values compared to nonpolluted sediments. Toxicants which reduce benthic bacterial production may indirectly impact other trophic groups through aberrant cycling of carbon or nutrients. Of the parameters examined, the tritiated thymidine production assay was found to be the most sensitive for detection of ecotoxicologica

ISSN:0884-8181    

DOI:10.1002/tox.2540010407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe use of microorganisms can be a valuable and powerful tool in assessing the toxicity of metals, but a number of factors must be considered if meaningful results are to be obtained. In many instances natural assemblages of microorganisms are preferred to pure cultures as test systems. Similarly, effects on microbial processes such as primary production, respiration, or nitrogen fixation can provide better evaluations of toxicity than are provided by measurements of viability on pure cultures. When possible, more than one measure of activity or viability should be used. In a large number of cases, the toxicity of a metal is influenced by the chemical species of the metal. The chemical species and the availability of a metal can be influenced markedly by physical and chemical conditions, which include conditions in the field and conditions of the assay itself. Thus, those using microorganisms to assay the toxicity of metals should take care to specify the assay conditions in detail, and they should be sure that the assay conditions are as close as possible toin situconditions. Moreover, caution should be used when extrapolating from laboratory to field situations, or from one field situation to another.

ISSN:0884-8181    

DOI:10.1002/tox.2540010408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractGlass, cellulose and chitin materials were used as immobilized supports for porous solid matrix attachment of bacterial strains in continuous flow biocatalyst studies for chlorinated phenols detoxification. Several bacterial strains, isolated from diverse aquatic environments in south Louisiana, were utilized in continuous biotransformation and detoxification of select chlorinated phenols typically found in industrial effluents. Toxicants included phenol, 2–chlorophenol, 2,4‐dichlorophenol, 2,4,5‐trichlorophenol and pentachlorophenol. Continuous removal of 100 ppm solutions were achieved for periods of 3 months or longer. Residual levels of 100 ppb or less were noted. Mathematical models of biotransformation kinetics were tested based on laboratory re

ISSN:0884-8181    

DOI:10.1002/tox.2540010409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0884-8181    

DOI:10.1002/tox.2540010410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0884-8181    

DOI:10.1002/tox.2540010411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY