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1.
Toxicol Lett ; 179(2): 101-7, 2008 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-18514445

RESUMO

The problem of toxicity of cyanobacterial toxins is of increasing concern, as the incidence of such blooms grows. Among the toxins, the most abundant in the environment are hepatotoxins known as nodularins and microcystins. These toxins are responsible for almost all known cases of fresh and brackish water intoxication and are responsible for recurrent episodes of human and animal illness and death. Moreover, they are believed to be potent tumor promoters and initiators. However, the mechanisms by which these toxins induce liver cancer are not well understood. The aim of the present study was to determine the effect of nodularin on the kinetics of nucleotide excision repair (NER) in Chinese hamster ovary (CHO) cells exposed to UV radiation. The first set of experiments was performed to define the optimal treatment conditions for nodularin to avoid the possibility of encountering false positive signals in the comet assay due to the apoptogenic activity of nodularin. Based on the analysis of apoptosis, the 6-h treatment time of cells with nodularin (1mug/ml, 10mug/ml and 20mug/ml) was chosen for the alkaline comet assay. The kinetics of NER was determined in CHO cell lines: AA8 (wild-type) and mutant cell lines: UV135 (XPG(-)), UV41 (XPF(-)) and UV20 (ERCC1(-)) exposed to 20J/m(2) UV radiation. The micronucleus assay was performed to determine a residual DNA damage in four cell lines treated with nodularin (10mug/ml) and exposed to equitoxic doses UV radiation. Radiation doses of UV producing 50% of survival for AA8, UV135, UV20 and UV41 cell lines were calculated from UV survival curves. The results show that nodularin impairs the incision/excision step of NER in CHO cells by the ERCC1/XPF inactivation and leads to an increased level of UV-induced cytogenetic DNA damage.


Assuntos
Dano ao DNA , Reparo do DNA , Proteínas de Ligação a DNA/genética , Peptídeos Cíclicos/toxicidade , Animais , Apoptose/efeitos dos fármacos , Apoptose/efeitos da radiação , Células CHO , Ensaio Cometa , Cricetinae , Cricetulus , Micronúcleos com Defeito Cromossômico/efeitos dos fármacos , Micronúcleos com Defeito Cromossômico/efeitos da radiação , Testes para Micronúcleos , Mutação , Nodularia/química , Peptídeos Cíclicos/isolamento & purificação , Raios Ultravioleta
2.
Environ Toxicol ; 18(1): 52-60, 2003 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-12539144

RESUMO

The mass occurrence of toxic cyanobacteria is a recurrent phenomenon in the Baltic Sea. Grazers may obtain toxins either through ingestion or by direct exposure to dissolved toxins. Despite this, there is little knowledge about the accumulation of cyanobacterial toxins in planktonic organisms present during these blooms. Toxin analyses of tissue samples are complicated to carry out and, because of the small size of microscopic planktonic organisms, often difficult to execute. Therefore, we wanted to use a precise and sensitive method to study toxin uptake and accumulation in zooplankton. We used chemically tritiated nodularin, (3)H-dihydronodularin, to study the uptake of dissolved nodularin, a cyanobacterial hepatotoxin produced by Nodularia spumigena. Cultures of the calanoid copepods Acartia tonsa and Eurytemora affinis, and an oligotrich ciliate Strombidium sulcatum were exposed to (3)H-dihydronodularin in filtered seawater, using naturally occurring concentrations of dissolved nodularin (5 microg L(-1)). All three species took up measurable amounts of radiolabeled nodularin. After 48 h we detected 0.37 +/- 0.22 microg toxin g C(-1) (mean +/- sd) in A. tonsa and 0.60 +/- 0.15 microg toxin g C(-1) in E. affinis, whereas 1.55 +/- 0.50 microg toxin g C(-1) was detected in S. sulcatum after 24 h. The minimum bioconcentration factor (BCF) of (3)H-dihydronodularin was 12 for A. tonsa and 18 for E. affinis. For S. sulcatum our results indicate a maximum BCF of 22. However, because the uptake studies for this species were done in the presence of bacteria, possible particulate transfer cannot be excluded. Nevertheless, our results indicate that dissolved nodularin can be taken up by planktonic organisms. Therefore, the vectorial transport of dissolved toxins to higher trophic levels seems possible, even if some planktonic grazers would avoid feeding on toxic cyanobacteria filaments.


Assuntos
Toxinas Bacterianas/farmacocinética , Cilióforos , Copépodes , Toxinas Marinhas/farmacocinética , Peptídeos Cíclicos/farmacocinética , Animais , Toxinas Bacterianas/química , Países Bálticos , Cianobactérias/química , Cadeia Alimentar , Toxinas Marinhas/química , Peptídeos Cíclicos/química , Solubilidade , Distribuição Tecidual , Trítio/farmacocinética , Zooplâncton
3.
Environ Toxicol ; 16(5): 444-8, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11594032

RESUMO

Polyunsaturated fatty acids (PUFAs) are essential components of zooplankton diets. However, studies with PUFAs from cyanobacteria indicate toxic properties. We investigated the toxicity of the PUFA gamma-linolenic acid and the cyanobacterial peptide toxin microcystin-LR to Daphnia. The PUFA was acutely toxic at a concentration of 9 micrograms ml-1. The effect of microcystin-LR was not statistically significant at the concentration used (3 micrograms ml-1), but an additive effect with the PUFA was observed. Relative to LC50-values of well-known pollutants, the PUFA was intermediately toxic. The activity equaled that of microcystin-LR, which is commonly treated as one of the most potent cyanobacterial toxins. Our results suggest that the toxic properties of PUFAs deserve more attention.


Assuntos
Daphnia , Peptídeos Cíclicos/efeitos adversos , Ácido gama-Linolênico/efeitos adversos , Animais , Cadeia Alimentar , Dose Letal Mediana , Toxinas Marinhas , Microcistinas , Fitoplâncton
4.
J Chromatogr A ; 909(2): 225-36, 2001 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-11269522

RESUMO

Four C18 columns and a novel amide C16 column were assessed in the HPLC separation of eight microcystins and nodularin-R. Gradient mobile phases of acetonitrile combined with trifluoroacetic acid, formic acid or ammonium acetate were compared. Special attention was paid to the resolution of four possible coeluting microcystin pairs. Generally speaking, the acidic mobile phases were superior to the ammonium acetate-based mobile phase in terms of resolution and selectivity. The amide C16 column had the best overall performance and unique selectivity properties.


Assuntos
Toxinas Bacterianas/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Cianobactérias/química , Peptídeos Cíclicos/isolamento & purificação , Cromatografia Líquida de Alta Pressão/instrumentação , Espectrometria de Massas , Microcistinas , Peptídeos Cíclicos/química , Espectrofotometria Ultravioleta
5.
Toxicon ; 39(6): 831-6, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11137543

RESUMO

An immunoassay based on the time-resolved fluorometry (TR-FIA) was developed for microcystins, cyanobacterial peptide hepatotoxins. The assay was performed in a competitive mode and it utilised the monoclonal antibodies raised against microcystin-LR, and a europium chelate of microcystin-LR as a competitive antigen. The sensitivity of the assay was 0.1microg/l. The detection method of TR-FIA was compared to a commercially available kit based on the enzyme-linked immunosorbent assay (ELISA). The same level of sensitivity could be obtained with TR-FIA (in a non-optimised system). The simplified method of TR-FIA leads to a shorter analysis time.


Assuntos
Cianobactérias/química , Peptídeos Cíclicos/análise , Anticorpos Monoclonais/imunologia , Cromatografia Líquida de Alta Pressão , Ensaio de Imunoadsorção Enzimática , Toxinas Marinhas , Microcistinas , Peptídeos Cíclicos/imunologia
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