摘要:

AbstractEscherichia coliisolated from the intestinal tract of marine fish captured along polluted beaches of the city of Rio de Janeiro, Brazil, were investigated in terms of resistance to seven antibiotics and to four heavy metals. Approximately 40% of the strains were resistant to one or more antibiotics, with predominance of mono‐ and biresistance. Overall resistance to heavy metals was 70.7%, and exclusive resistance to these elements was more elevated than resistance to antibiotics only. Resistance to mercury was closely associated with resistance to antibiotics and with multiple resistance in particular. Most of the strains analyzed transferred resistance determinants to standard receptor strains during conjugation, the phenomenon being particularly outstanding for the transfer of the copper marker. The epidemiological and ecological aspects of the results obtained are discussed. © 1993 John Wiley&Sons, I

ISSN:1053-4725    

DOI:10.1002/tox.2530080102

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

年代:1993

数据来源: WILEY

摘要:

AbstractHeterotrophic bacteria isolated from drinking water distribution systems were examined to determine if they possessed putative virulence factors such as hemolysins, proteases, or cytotoxins. Representative samples of colonies from several different distribution systems indicated that the median percentage of heterotrophic bacteria having at least one putative virulence characteristic was about 11% and all of the samples contained bacteria expressing at least one putative virulence characteristic. The overall frequency of bacteria from drinking water distribution samples expressing more than one putative virulence factor ranged from 0 to 8%. The eukaryotic cell culture cytotoxicity test appeared to be the most reliable indicator of those bacteria expressing multiple virulence factors. The results also indicated that the expression of putative virulence factors was highly dependent upon the type of isolation medium used. Although slow‐growing heterotrophic bacteria occurred at high densities in certain systems, they expressed very few of the putative virulence factors observed in this study. © 1993 John Wiley&Sons, I

ISSN:1053-4725    

DOI:10.1002/tox.2530080103

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

年代:1993

数据来源: WILEY

摘要:

AbstractCrayfish 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 Wile

ISSN:1053-4725    

DOI:10.1002/tox.2530080104

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

年代:1993

数据来源: WILEY

摘要:

AbstractA comprehensive assessment of the potential toxicological effects of an environmental chemical or mixture of chemicals must take into account the possibility of genetic damage to cellular organisms. In conventional assays (e.g., the Ames test), point mutations (both base‐pair substitutions and frameshifts) have come into widespread use as indicators of genetic damage, but it is important that such end points be supplemented by indicators of more extensive genetic damage such as deletions or other large scale rearrangements of sections of genetic material. In the present paper, the ability of certain chemicals to cause gross changes to DNA sequences will be reviewed. The changes to be considered are primarily those that result from movements of mobile genetic elements, and focus especially on description and discussion of factors that enhance or inhibit the movement of transposons such as Tn10. © 1993 John Wiley&Sons, I

ISSN:1053-4725    

DOI:10.1002/tox.2530080105

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

年代:1993

数据来源: WILEY

摘要:

AbstractNatural populations of phytoplankton from the lower River Rhine were exposed to selected pollutants in order to estimate their sensitivity to chemical pollution. The photosynthesis, measured as14C incorporation, was inhibited by 50% when circa 100 μg · L−1copper or atrazine was added. Potassium dichromate (K2Cr2O7) and an anionic detergent (tetrapropylbenzenesulphonate) affected the photosynthesis of Rhine phytoplankton only at concentrations of about 3 and 40 mg L−1, respectively. A tenfold concentrate of the organic compounds from river water, harvested on XAD resin, inhibited the photosynthesis by 50%. Comparison of the results of this study with literature data indicate that the algal populations in the River Rhine are as sensitive and not more tolerant than several algae from less polluted habitats. These observations on the Rhine plankton also indicate that the pollution level in the River Rhine is likely to affect the photosynthesis of phytoplankton. This supports the request for a further reduction in toxicant input in the River Rhine. © 1993 John Wiley&Son

ISSN:1053-4725    

DOI:10.1002/tox.2530080106

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

年代:1993

数据来源: WILEY

摘要:

AbstractTo study toxicity of 76 laboratory‐grown strains of planktonic cyanobacteria to mosquito larvae, hydrophilic and lipophilic cell‐free extracts of cyanobacteria were incubated with larvae of theAedes aegyptimosquito and death percentages were followed during 2 days. Toxicity was clearly associated with hepato ‐ and neurotoxins of the samples. A strain ofMicrocystis aeruginosawas most effective, and caused death of the larvae due to a single hepatotoxin. Pure mammalian neurotoxin, anatoxin‐a, was also toxic, and probably acted as a neurotoxin with the mosquito

ISSN:1053-4725    

DOI:10.1002/tox.2530080107

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe inhibitory effect of copper, 2,4‐D, Roundup, and an industrial effluent on chemoattraction responses of the ciliateTetrahymena pyriformiswas 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 environmen

ISSN:1053-4725    

DOI:10.1002/tox.2530080108

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

年代:1993

数据来源: WILEY

摘要:

AbstractA quantitative structure—activity relationship study is carried out with use of the toxicity (LC50) of the various kinds of fish obtained from the references. The equation obtained contained the parameters of molecular weight (MW) and mean ionization potential (IP):log(1/LC50) = 28.665 + 0.01095MW ‐ 2.570IP(R2= 0.695,n= 581). This equation could estimate the toxicity of the chemicals detected in the environment of Japan by Environment Agency (r= 0.80,n= 53). In order to evaluate the hazardousness, we propose the Ecotoxicological Risk Quotient (ERQ):ERQc= ‐log Concentration in the environment/Effective concentration in the testERQa= ‐log Σ Concentration in the environment/Effective concentration in the testERQcand ERQaare the indices of the hazardousness of a chemical and chemicals in an area, respectively. ERQ could explain the status of pollution in water environment

ISSN:1053-4725    

DOI:10.1002/tox.2530080109

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

年代:1993

数据来源: WILEY

ISSN:1053-4725    

DOI:10.1002/tox.2530080110

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

年代:1993

数据来源: WILEY

ISSN:1053-4725    

DOI:10.1002/tox.2530080101

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

年代:1993

数据来源: WILEY