Chlorpyrifos and dimethoate are overused agricultural pesticides that can trigger trophic cascades, resulting in toxicity to both terrestrial and aquatic organisms as well as altered ecosystems. In previous studies, s...Chlorpyrifos and dimethoate are overused agricultural pesticides that can trigger trophic cascades, resulting in toxicity to both terrestrial and aquatic organisms as well as altered ecosystems. In previous studies, substantial attention has been given to the effects of pesticides on vertebrate species and, to a lesser extent, species of zooplankton. The present study was designed to show that the fission time effective concentration in ciliates is a potential aquatic detection index for environmental monitoring. The ciliate Urostyla grandis was treated with doses of chlorpyrifos and dimethoate. After exposed to the pesticides, the LC_(50)(i.e., concentration that killed 50% of the ciliate cells within 24 h) values were 0.029 mg L^(-1) for chlorpyrifos and 0.0685 mg L^(-1) for dimethoate. The fission time effective concentrations after 168 h of exposure were 0.0075–0.0093 mg L^(-1) for chlorpyrifos and 0.2640–0.2750 mg L^(-1) for dimethoate. These results show that the fission time effective concentration is lower than the LC_(50) value in ciliates, indicating that fission time effective concentration is more suitable than the LC_(50) value for environmental monitoring using ciliates. The effects of chlorpyrifos and dimethoate on ciliate cell ultrastructures included agglutination of chromatin in the macronucleus, protruded and discontinuous macronuclear and micronuclear membranes, loss of integrity of mitochondrial membranes and contents, and abscission and deformation of the adoral zone of membranelles.展开更多
Total dissolved gas(TDG) supersaturation caused by dam sluicing can result in gas bubble trauma(GBT) in fish and threaten their survival.In the present study,Chinese suckers(Myxocyprinus asiaticus Bleeker) were expose...Total dissolved gas(TDG) supersaturation caused by dam sluicing can result in gas bubble trauma(GBT) in fish and threaten their survival.In the present study,Chinese suckers(Myxocyprinus asiaticus Bleeker) were exposed to TDG supersaturated water at levels ranging from 120% to 145% for 48 h.The median lethal concentration(LC 50) and the median lethal time(LT 50) were determined to evaluate acute lethal effects on Chinese suckers.The results showed that the LC 50 values of 4,6,8,and 10 h were 142%,137%,135%,and 130%,respectively.The LT 50 values were 3.2,4.7,7.8,9.2,and 43.4 h,respectively,when TDG supersaturated levels were 145%,140%,135%,130%,and 125%.Furthermore,the biological responses in Chinese suckers were studied by assaying the catalase(CAT) activities in gills and muscles at the supersaturation level of 140% within LT 50.The CAT activities in the gills and muscle tissues exhibited a regularity of a decrease after an increase.CAT activities in the muscles were increased significantly at 3/5LT 50(P<0.05) and then came back to the normal level.However,there were no significant differences between the treatment group(TDG level of 140%) and the control group(TDG level of 100%) on CAT activities in the gills before 3/5LT 50(P>0.05),but the activities were significantly lower than the normal level at 4/5LT 50 and LT 50(P<0.05).展开更多
The effect of a terrestrial humic acid （HA） and Suwannee River HA on the cytotoxicity of engineered zinc oxide nanoparticles （ZnONPs） and titanium dioxide nanoparticles （TiO2NPs） to natural aquatic bacterial ass...The effect of a terrestrial humic acid （HA） and Suwannee River HA on the cytotoxicity of engineered zinc oxide nanoparticles （ZnONPs） and titanium dioxide nanoparticles （TiO2NPs） to natural aquatic bacterial assemblages was measured with spread plate counting. The effect of HA （10 and 40 ppm） on the cytotoxicity of ZnONPs and TiO2NPs was tested factorially in the presence and absence of natural sunlight （light irradiation （LI））. The experiment was of full factorial, completely randomized design and the results were analyzed using the General Linear Model in SAS analytical software. The method of least squares means was used to separate the means or combinations of means. We determined the mechanism of toxicity via measurements of oxidative stress and metal ions. The toxicity of ZnONPs and TiO2NPs to natural aquatic bacterial assemblages appears to be concentration dependent. Moreover, the cytotoxicity of ZnONPs and TiO2NPs appeared to be affected by HA concentration, the presence of sunlight irradiation, and the dynamic multiple interactions among these factors. With respect to light versus darkness in the control group, the data indicate that bacterial viability was inhibited more in the light exposure than in the darkness exposure. The same was true in the HA treatment groups. With respect to terrestrial versus Suwanee River HA for a given nanoparticle, in light versus darkness, bacterial viability was more inhibited in the light treatment groups containing the terrestrial HA than in those containing Suwanee River HA. Differences in the extent of reactive oxygen species formation, adsorption/binding of ZnONPs/TiO2NPs by HA, and the levels of free metal ions were speculated to account for the observed cytotoxicity. TEM images indicate the attachment and binding of the tested nanoparticles to natural bacterial assemblages. Besides the individual parameter, significant effects on bacterial viability count were also observed in the following combined treatments： HA-ZnONPs, HA-LI, ZnONPs-LI, and HA-ZnONPs-LI. The main effects of all independent variables, plus interaction effects in all cases were significant with TiO2NPs.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 31601866 and 31501844)the Heilongjiang Province Colleges and Universities Youth Innovative Training Program (Nos. UNPYSCT2017178 and 2017180)
文摘Chlorpyrifos and dimethoate are overused agricultural pesticides that can trigger trophic cascades, resulting in toxicity to both terrestrial and aquatic organisms as well as altered ecosystems. In previous studies, substantial attention has been given to the effects of pesticides on vertebrate species and, to a lesser extent, species of zooplankton. The present study was designed to show that the fission time effective concentration in ciliates is a potential aquatic detection index for environmental monitoring. The ciliate Urostyla grandis was treated with doses of chlorpyrifos and dimethoate. After exposed to the pesticides, the LC_(50)(i.e., concentration that killed 50% of the ciliate cells within 24 h) values were 0.029 mg L^(-1) for chlorpyrifos and 0.0685 mg L^(-1) for dimethoate. The fission time effective concentrations after 168 h of exposure were 0.0075–0.0093 mg L^(-1) for chlorpyrifos and 0.2640–0.2750 mg L^(-1) for dimethoate. These results show that the fission time effective concentration is lower than the LC_(50) value in ciliates, indicating that fission time effective concentration is more suitable than the LC_(50) value for environmental monitoring using ciliates. The effects of chlorpyrifos and dimethoate on ciliate cell ultrastructures included agglutination of chromatin in the macronucleus, protruded and discontinuous macronuclear and micronuclear membranes, loss of integrity of mitochondrial membranes and contents, and abscission and deformation of the adoral zone of membranelles.
基金Project supported by the National Natural Science Foundation ofChina (No. 50979063)the Scientific Research Foundation for Young Teachers of Xihua University (No. Z1120412),China
文摘Total dissolved gas(TDG) supersaturation caused by dam sluicing can result in gas bubble trauma(GBT) in fish and threaten their survival.In the present study,Chinese suckers(Myxocyprinus asiaticus Bleeker) were exposed to TDG supersaturated water at levels ranging from 120% to 145% for 48 h.The median lethal concentration(LC 50) and the median lethal time(LT 50) were determined to evaluate acute lethal effects on Chinese suckers.The results showed that the LC 50 values of 4,6,8,and 10 h were 142%,137%,135%,and 130%,respectively.The LT 50 values were 3.2,4.7,7.8,9.2,and 43.4 h,respectively,when TDG supersaturated levels were 145%,140%,135%,130%,and 125%.Furthermore,the biological responses in Chinese suckers were studied by assaying the catalase(CAT) activities in gills and muscles at the supersaturation level of 140% within LT 50.The CAT activities in the gills and muscle tissues exhibited a regularity of a decrease after an increase.CAT activities in the muscles were increased significantly at 3/5LT 50(P<0.05) and then came back to the normal level.However,there were no significant differences between the treatment group(TDG level of 140%) and the control group(TDG level of 100%) on CAT activities in the gills before 3/5LT 50(P>0.05),but the activities were significantly lower than the normal level at 4/5LT 50 and LT 50(P<0.05).
基金supported by NSF-SBIR grant # IIP-0823040NSF-CREST Program with grant # HRD-0833178Strengthening the Environmental Science Ph.D Program in instruction, grant # P031B090210-11
文摘The effect of a terrestrial humic acid （HA） and Suwannee River HA on the cytotoxicity of engineered zinc oxide nanoparticles （ZnONPs） and titanium dioxide nanoparticles （TiO2NPs） to natural aquatic bacterial assemblages was measured with spread plate counting. The effect of HA （10 and 40 ppm） on the cytotoxicity of ZnONPs and TiO2NPs was tested factorially in the presence and absence of natural sunlight （light irradiation （LI））. The experiment was of full factorial, completely randomized design and the results were analyzed using the General Linear Model in SAS analytical software. The method of least squares means was used to separate the means or combinations of means. We determined the mechanism of toxicity via measurements of oxidative stress and metal ions. The toxicity of ZnONPs and TiO2NPs to natural aquatic bacterial assemblages appears to be concentration dependent. Moreover, the cytotoxicity of ZnONPs and TiO2NPs appeared to be affected by HA concentration, the presence of sunlight irradiation, and the dynamic multiple interactions among these factors. With respect to light versus darkness in the control group, the data indicate that bacterial viability was inhibited more in the light exposure than in the darkness exposure. The same was true in the HA treatment groups. With respect to terrestrial versus Suwanee River HA for a given nanoparticle, in light versus darkness, bacterial viability was more inhibited in the light treatment groups containing the terrestrial HA than in those containing Suwanee River HA. Differences in the extent of reactive oxygen species formation, adsorption/binding of ZnONPs/TiO2NPs by HA, and the levels of free metal ions were speculated to account for the observed cytotoxicity. TEM images indicate the attachment and binding of the tested nanoparticles to natural bacterial assemblages. Besides the individual parameter, significant effects on bacterial viability count were also observed in the following combined treatments： HA-ZnONPs, HA-LI, ZnONPs-LI, and HA-ZnONPs-LI. The main effects of all independent variables, plus interaction effects in all cases were significant with TiO2NPs.
