ISSN:0730-7268    

DOI:10.1002/etc.5620081201

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThis overview examines the utility of mixed‐function oxygenase (MFO) enzymes as a bio‐effects monitor for wildlife (amphibians, reptiles, birds and mammals) in view of their widespread use as indicators of contaminant exposure in aquatic invertebrates and fish. Phylogenetic trends in MFO activity, toxicological implications of induction and the relationship between contaminant exposure and MFO activity are discussed. Field studies using avian embryos and hatchlings suggest that MFO induction has utility for documenting contaminant exposure; however, findings in adult birds and mammals are equivocal. Age, sex and season are sources of variation that require consideration when undertaking field trials. Further understanding of MFO inducibility among species and application of recently developed analytical techniques including quantification of specific cytochrome P‐450 isozymes are warr

ISSN:0730-7268    

DOI:10.1002/etc.5620081202

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe study of biochemical responses in aquatic animals comprises a vigorous area of inquiry within ecotoxicology for a number of reasons, including the perceived need for basic research in the field, the desire for highly sensitive biomarkers useful for biomonitoring and the particular concern for elevated rates of neoplasia observed in some aquatic systems. In this paper, an approach only recently investigated by aquatic toxicologists will be described and reviewed in detail. This approach is based on theories of oxyradical generation and subsequent oxidative stress in biological systems. Of particular concern to environmental toxicologists with respect to these phenomena are the abilities of a number of common and diverse compounds to undergo enzymatically facilitated redox cycling in cells and thereby generate oxyradicals under aerobic conditions. Mechanisms of oxyradical generation, toxicological consequences of these processes and endogenous antioxidant defense systems are described. In addition, methodologies for studying these phenomena are discussed and recent studies demonstrating their applicability to aquatic toxicology are reviewed.

ISSN:0730-7268    

DOI:10.1002/etc.5620081203

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effect of methyl parathion on dietary discrimination ability was assessed in two‐week‐old northern bobwhite (Colinus virginianus). An initial oral dose of methyl parathion (0, 3 or 6 mg/kg: O,O‐dimethyl O‐(4‐nitrophenyl) ester) was given to two subgroups of bobwhite before a 6‐d food discrimination test; one group was tested with a choice of food treated with 45 ppm methyl parathion versus normal food and the second with a choice of 90 ppm treated food versus normal food. The average discrimination ratios (i.e., amount of treated to untreated food consumed) were used to indicate the chicks' ability to discriminate and avoid contaminated food. Chicks administered 6 mg/kg methyl parathion did not discriminate between treated and untreated food at either food treatment level and initially chose treated over untreated food (ratio = 1.28;p<0.05). Brain cholinesterase activity in the 6 mg/kg groups averaged 50% of control levels, indicating high exposure to methyl parathion, which correlated with a behavioral disturbance (i.e., preference for treated food on day 1). Cholinesterase activity did not correlate with the discrimination ratios throughout the remainder of the 6‐d exposure period due to the strong side preference that developed in the treated groups. This study demonstrates that feeding behavior and taste discrimination ability of bobwhite chicks was impaired due to exposure to met

ISSN:0730-7268    

DOI:10.1002/etc.5620081204

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

Abstract2‐Chloropropenal (2‐chloroacrolein), a constituent of softwood kraft chlorination effluent that gives strongly positive results in theSalmonellamutagenicity assay (Ames Test), was reacted with various nucleophiles and the resulting effect on mutagenicity monitored. Nucleophiles such as hydroxide ion and sulfur dioxide (HSO−3, SO3) proved very effective in reducing the mutagenicity of aqueous 2‐chloropropenal solutions. The application of other strong nucleophiles, (glutathione, pyrrolidine and sodium thiosulfate) to 2‐chloropropenal also produced substantial benefits in terms of mutagenicity reduction. Further experimentation revealed that the loss of mutagenicity was not the result of the removal of organically bound chlorine but rather the removal of the ethylenic group in 2‐chloropropenal, possibly as a consequence of undergoing Michael‐type 1,4‐addition reactions with the various nucleophiles. In the treatment of 2‐chloropropenal with alkali (pH 9), additional condensation of the acrolein derivative to a polymer was demonstrated by gel permea

ISSN:0730-7268    

DOI:10.1002/etc.5620081205

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe in vitro effects of copper and cadmium on fish enzyme activity were assayed by combining the metals with the biochemical stains used to resolve these enzyme systems on starch gels. The effects of copper and cadmium on the activity of PGM‐2, GPI‐2 and IDH‐2 enzymes in mosquitofish were assayed using stain‐metal mixtures containing 2.0 ml 0.1mCuSO4· 5H2O or 0.1 m CdSO4. Enzymes whose activities were effected by copper in this initial test were resolved using a series of stain‐metal mixtures containing copper at lower concentrations to determine effect threshold concentration ranges and to determine concentration ranges that might produce differential effects on activity among allozymes of a single protein. Interspecific differences in the effect of copper on the activity of PGM‐2 enzyme variants were examined for 17 fish species from seven locations.Copper was found to effect the activity of PGM‐2, GPI‐2, and IDH‐2 enzymes in mosquitofish and intraspecific and interspecific differences existed in the copper sensitivity of enzymes in a number of the fish species tested. Allozyme phenotypes at the PGM‐2 locus in mosquitofish observed on test gels (0.9 mg Cu/L) suggests that two isoalleles, one copper‐tolerant and one copper‐sensitive, a

ISSN:0730-7268    

DOI:10.1002/etc.5620081206

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe potential for anaerobic biodegradation of 12 heterocyclic model compounds was studied. Nine of the model compounds were biotransformed in aquifer slurries under sulfate‐reducing or methanogenic conditions. The nitrogen and oxygen heterocyclic compounds were more susceptible to anaerobic biodegradation than those compounds containing a sulfur heteroatom. Carboxy‐substituted compounds were anaerobically metabolized more readily than unsubstituted or methylated analogues. In methanogenic incubations, 47 to 84% of the expected amount of carbon in pyridine, 4‐picoline, nicotinic acid and 2‐thiophene carboxylic acid was recovered as methane. In contrast, only small amounts of methane were detected in aquifer slurries amended with compounds containing an oxygen heteroatom, even though a decrease in the parent substrate concentration occurred. Pyridine, 2‐picoline and 4‐picoline were biotransformed within three months under sulfate‐reducing conditions. However, longer incubation times were required for the degradation of these substrates in methanogenic aquifer slurries. A literature survey reveals the widespread contamination of ground waters with heterocyclic compounds from waste management practice and fossil‐fuel‐r

ISSN:0730-7268    

DOI:10.1002/etc.5620081207

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractAn investigation of the aqueous chlorination (NaOCl) of resorcinol is reported. The following intermediates were detected in moderate to high yield at different pH values and varying percentages of chlorination: 2‐chloro‐, 4‐chloro‐, 2,4‐dichloro‐, 4,6‐dichloro‐ and 2,4,6‐trichlororesorcinol. Only trace amounts of the intermediates were detected when the chlorination was conducted in the presence of phosphate buffer. This result has significant implications since resorcinol in phosphate buffer has been used as a model compound in several recent studies on the formation of chlorinated hydrocarbons during chlorination of drinking water. Relative rates of chlorination were determined for resorcinol and several of the chlorinated resorcinols. Resorcinol was found to chlorinate only three times faster than 2,4,6‐trichlororesorcinol. The structure 2,4,6‐trichlororesorcinol was established as a monohydrate even after sublimation. A tetrachloro or pentachloro intermediate was not detected, suggesting that the ring‐opening step of such an int

ISSN:0730-7268    

DOI:10.1002/etc.5620081208

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractRiboflavin, a known photosensitizer, when initially added at 5 m̈m to solutions of added phenols or anilines (structurally related to common environmental contaminants) greatly accelerated the rate of their loss in the presence of light. The sensitized photolysis rates increased in the absence of oxygen, suggesting a mechanism involving direct energy or electron transfer between flavin excited states and acceptor molecules. A preliminary kinetic model was developed to calculate loss rates. Riboflavin itself was rapidly converted in aqueous solution by Pyrex‐filtered mercury arc light to products that had variable efficiencies as sensitize

ISSN:0730-7268    

DOI:10.1002/etc.5620081209

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe environmental persistence and fate of ethyl 2‐[4‐[(6‐chloro‐2‐benzoxazolyl)oxy]phen‐oxy]propanoate (fenoxaprop‐ethyl), a herbicide proposed for selective control of grasses in California rice, have been investigated under laboratory and field conditions. In the field, it dissipated rapidly from both water and soil, with half‐lives in water<4 h and soil residues below detectability within 6 d. The photolysis half‐life in sterile, distilled water was 269 · 19 h; in field water a combination of microbial and photochemical reactions resulted in a half‐life of 29 · 2 h. Products included the corresponding acid, 6‐chlorobenzoxazolinone, ethyl 2‐(4‐hydroxyphenoxy)propanoate and 2‐(4‐hydroxyphenoxy)propanoic acid. Hydrolysis was slow at pH 6.1 and 7.4 but resulted in a half‐life of only 8.3 h at pH 9.1. Fenoxaprop‐ethyl is essentially nonvolatile (Henry's Law constant = 3 × 10−7) and was bound moderately to soil (Koc= 6800). These properties represent a

ISSN:0730-7268    

DOI:10.1002/etc.5620081210

出版商:Wiley Periodicals, Inc.    

年代:1989

数据来源: WILEY