Synergism and antagonism of cadmium (Cd), copper (Cu) and selenium (Se) to biological toxicities in red soil, yellow brown soil and black soil were evaluated by MICROTOX method. The relation between forms of the teste...Synergism and antagonism of cadmium (Cd), copper (Cu) and selenium (Se) to biological toxicities in red soil, yellow brown soil and black soil were evaluated by MICROTOX method. The relation between forms of the tested metals in soil and the synergism or antagonism between them was also studied.Results showed that owing to the difference of soil chemical properties, toxicity of these metals in soils was different. In red soil with acid reaction and low in cation exchange capacity, antagonism occurred significantly between metals when they coexisted at high concentrations, while synergism occurred only under low concentrations. It is indicated that in red soil, toxicity of metals affected by synergism or antagonism depends on concentration of the metals present. For yellow brown soil and black soil with larger cation exchange capacity and lower exchangeable aluminium (A1), no toxicity of metals was observed even if metals were added to soil in high concentrations. Synergism and antagonism between Cd, Cu and Se were controlled by the forms of metals present. The amount of water-soluble metals was the most important factor in determining synergism and antagonism.In this paper, comparisons of synergism and antagonism between metals in soils and in water solutions were made. There occurred the synergism of metal toxicity in water solutions when the concentration of coexisting metals was high. This is just opposite to the case in soils.展开更多
Enterococcus faecalis isolates （87） were phenotypically and genotypically identified and subsequently subjected to the antagonism test and antimicrobial susceptibility. The lipolitic, hemolytic and DNAse activities ...Enterococcus faecalis isolates （87） were phenotypically and genotypically identified and subsequently subjected to the antagonism test and antimicrobial susceptibility. The lipolitic, hemolytic and DNAse activities were identified along with the genes gelE, cylL, cylS, ccf, cpd and cob that, encode virulence determinants. Thirty seven percent of isolates inhibited Listeria monocytogenes （CERELA）, Listeria innocuous （CERELA）, Staphylococcus aureus （ATCC25932）, Lactococcus lactis （IL1403）, Micrococcus luteus （ATCC 10240） and Enterococcusfaecalis （ATCC29212）. All strains were sensitive to the ampicillin antibiotic, but 47% were resistant to at least one antimicrobial agent and 6% of isolates presented multidrug resistance. Ninety seven percent of isolates contained the gelE gene, but 77% of these isolates showed gelatinase activity. Presence of cylL and cylS genes was observed in 25% of the isolates, but only 5% presented hemolytic activity. None isolates showed lipase and DNAse activities. Eight percent of isolates contained the ccf gene and 2% showed the presence of the cpd and cob genes. The ability to inhibit pathogenic bacteria, low resistance to antibiotics and absence of virulence factors make some of Enterococcusfaecalis strains characterized in the present study promising for exploitation in other applications such as probiotics in aquaculture.展开更多
Polychlorinated biphenyls(PCBs) can antagonize human pregnane X receptor(hPXR) activation.Such chemicals could pose a serious threat to the reproductive and developmental ability of humans.The quantitative structure a...Polychlorinated biphenyls(PCBs) can antagonize human pregnane X receptor(hPXR) activation.Such chemicals could pose a serious threat to the reproductive and developmental ability of humans.The quantitative structure activity relationship(QSAR) provides a promising method for the estimation of PCBs' antagonistic activity.In this investigation,a QSAR model was developed by using heuristic method and best subset modeling(r2 = 0.873,q2LOO=0.742).The built model was validated externally by splitting the original data set into training and prediction sets.The results of the model derived are as follows:r2 = 0.907,q2LOO=0.709,r2pred=0.676,suggesting developed QSAR model had good robustness and predictive ability.The applicability domain(AD) of the model was assessed by Williams plot.The antagonistic activity(?logKi) of 108 PCBs,which are unavailable by experiment at present,was predicted within the applicability domain of the model.The critical structural features related to the activity of PCBs were identified.展开更多
文摘Synergism and antagonism of cadmium (Cd), copper (Cu) and selenium (Se) to biological toxicities in red soil, yellow brown soil and black soil were evaluated by MICROTOX method. The relation between forms of the tested metals in soil and the synergism or antagonism between them was also studied.Results showed that owing to the difference of soil chemical properties, toxicity of these metals in soils was different. In red soil with acid reaction and low in cation exchange capacity, antagonism occurred significantly between metals when they coexisted at high concentrations, while synergism occurred only under low concentrations. It is indicated that in red soil, toxicity of metals affected by synergism or antagonism depends on concentration of the metals present. For yellow brown soil and black soil with larger cation exchange capacity and lower exchangeable aluminium (A1), no toxicity of metals was observed even if metals were added to soil in high concentrations. Synergism and antagonism between Cd, Cu and Se were controlled by the forms of metals present. The amount of water-soluble metals was the most important factor in determining synergism and antagonism.In this paper, comparisons of synergism and antagonism between metals in soils and in water solutions were made. There occurred the synergism of metal toxicity in water solutions when the concentration of coexisting metals was high. This is just opposite to the case in soils.
文摘Enterococcus faecalis isolates （87） were phenotypically and genotypically identified and subsequently subjected to the antagonism test and antimicrobial susceptibility. The lipolitic, hemolytic and DNAse activities were identified along with the genes gelE, cylL, cylS, ccf, cpd and cob that, encode virulence determinants. Thirty seven percent of isolates inhibited Listeria monocytogenes （CERELA）, Listeria innocuous （CERELA）, Staphylococcus aureus （ATCC25932）, Lactococcus lactis （IL1403）, Micrococcus luteus （ATCC 10240） and Enterococcusfaecalis （ATCC29212）. All strains were sensitive to the ampicillin antibiotic, but 47% were resistant to at least one antimicrobial agent and 6% of isolates presented multidrug resistance. Ninety seven percent of isolates contained the gelE gene, but 77% of these isolates showed gelatinase activity. Presence of cylL and cylS genes was observed in 25% of the isolates, but only 5% presented hemolytic activity. None isolates showed lipase and DNAse activities. Eight percent of isolates contained the ccf gene and 2% showed the presence of the cpd and cob genes. The ability to inhibit pathogenic bacteria, low resistance to antibiotics and absence of virulence factors make some of Enterococcusfaecalis strains characterized in the present study promising for exploitation in other applications such as probiotics in aquaculture.
基金supported by the Science and Technology Development Foundation Key Project of Nanjing Medical University (09NJMUZ16)Natural Science Research Project of Institution of Higher Education of Jiangsu Province (11KJB180006)
文摘Polychlorinated biphenyls(PCBs) can antagonize human pregnane X receptor(hPXR) activation.Such chemicals could pose a serious threat to the reproductive and developmental ability of humans.The quantitative structure activity relationship(QSAR) provides a promising method for the estimation of PCBs' antagonistic activity.In this investigation,a QSAR model was developed by using heuristic method and best subset modeling(r2 = 0.873,q2LOO=0.742).The built model was validated externally by splitting the original data set into training and prediction sets.The results of the model derived are as follows:r2 = 0.907,q2LOO=0.709,r2pred=0.676,suggesting developed QSAR model had good robustness and predictive ability.The applicability domain(AD) of the model was assessed by Williams plot.The antagonistic activity(?logKi) of 108 PCBs,which are unavailable by experiment at present,was predicted within the applicability domain of the model.The critical structural features related to the activity of PCBs were identified.
