RESUMO
Hydrophobic chemicals are known to associate with sediment particles including those from both suspended particulate matter and bottom deposits. The complex and variable composition of natural particles makes it very difficult therefore, to predict the bioavailability of sediment-bound contaminants. To overcome these problems we have previously devised a test system using artificial particles, with or without humic acids, for use as an experimental model of natural sediments. In the present work we have applied this experimental technique to investigate the bioavailability and bioaccumulation of pyrene by the freshwater fingernail clam Sphaerium corneum. The uptake and accumulation of pyrene in clams exposed to the chemical in the presence of a sample of natural sediment was also investigated. According to the results obtained, particle surface properties and organic matter content are the key factors for assessing the bioavailability and bioaccumulation of pyrene by clams.
Assuntos
Bivalves/química , Pirenos/análise , Testes de Toxicidade/métodos , Poluentes Químicos da Água/análise , Absorção , Análise de Variância , Animais , Disponibilidade Biológica , Sedimentos Geológicos , Substâncias Húmicas , Tamanho da PartículaRESUMO
Acute static bioassays were performed using three freshwater invertebrate species (the oligochaete Lumbriculus variegatus, the fingernail clam Sphaerium corneum and the larvae Chironomus riparius) exposed separately to a variety of 14C radiolabelled contaminants. The aim of this work was to investigate if the chemicals remained as parent compounds after the treatments. Chemicals used were 2,4-dichlorophenol; 2,4,5-trichlorophenol; pentachlorophenol; pyrene; Fenpropidin, and Trifluralin. Homogenates of the whole body tissue of each organism were prepared and total radioactivity was measured. Contaminants were then extracted into organic solvents and analysed by high-pressure liquid chromatography techniques. Chromatograms showed that most of the substances extracted were present as parent compounds in S. corneum and in L. variegatus. In contrast, for C. riparius a low proportion of the chemicals was recovered as parent compounds. These results suggest that different metabolic processes could take place in the different species.
Assuntos
Água Doce/química , Invertebrados/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Bioensaio , Biotransformação , Bivalves/metabolismo , Radioisótopos de Carbono , Clorofenóis/metabolismo , Cromatografia Líquida de Alta Pressão , Larva/metabolismo , Oligoquetos/metabolismo , Pentaclorofenol/metabolismo , Piperidinas/metabolismo , Pirenos/metabolismo , Trifluralina/metabolismoRESUMO
The uptake of anthropogenic chemicals by benthic bivalves may occur through the water phase and also by the ingestion of particles from both the suspended matter and bottom sediments. Many chemicals sorb to sediments and, subsequently, are released in the digestive tract of animals. The assessment of sediment-bound chemicals has been difficult because of the complexity of the association between these chemicals and natural particles. To simplify this complexity, we previously devised a test system using artificial particles with known chemical structures. In the present work, we improved this experimental design by adding humic materials as a source of organic matter. Bioassays were conducted by exposing the fingernail clam Sphaerium corneum to sublethal levels of pentachlorophenol (PCP) in the presence or absence of the artificial particles, treated with or without a commercial preparation of humic acids. The results showed that the bioavailability and bioaccumulation could be explained on the basis of the interactions of PCP with the active groups and/or the backbone of the resins, both in systems with or without humic acids. This model may constitute a useful approach to modeling and predicting the uptake and accumulation of chemicals bound to natural sediments.
Assuntos
Bivalves , Exposição Ambiental , Poluentes Ambientais/farmacocinética , Modelos Biológicos , Pentaclorofenol/farmacocinética , Poluentes Químicos da Água/farmacocinética , Animais , Disponibilidade Biológica , Poluentes Ambientais/análise , Previsões , Substâncias Húmicas/análise , Substâncias Húmicas/farmacocinética , Tamanho da Partícula , Pentaclorofenol/análise , Medição de Risco , Distribuição Tecidual , Poluentes Químicos da Água/análiseRESUMO
Medical and biochemical analysis were performed on 58 patients with chronic alcoholism. In accordance with medical characterisation, patients were divided in three groups: A (patients having only hepatopathy), B (patients with hepatopathy and neuropathy) and C (patients having only alcoholic neuropathy). Simultaneously, several parameters related to heme biosynthesis were examined. Urinary delta-aminolevulic acid (ALA), porphobilinogen (PBG) and porphyrins and fecal porphyrins measurements did not show significant difference among all studied groups. The activities of ALA-dehydratase (ALA-D), uroporphyrinogen-I-synthase (URO-I-S) and uroporphyrinogen-III-synthase (URO-III-S) were monitored in peripheral erythrocytes. From the enzymes measured, only ALA-D levels in groups B and C were significantly depressed (p < 0.002) compared with normal subjects. The decrease in ALA-D correlated with the degree of neuropathy.
Assuntos
Alcoolismo/metabolismo , Sintase do Porfobilinogênio/metabolismo , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The high level of delta-aminolaevulinate synthetase (ALA-S) in Rhodopseudomonas palustris cells grown under photosynthetic conditions decreased when they were vigorously aerated; moreover, the bacteriochlorophyll synthesis suddenly stopped. When aeration was interrupted, enzymatic level increased notably, but bacteriochlorophyll level did not. Chloramphenicol added to cultures when aeration was interrupted did not affect the increase of enzymic level. When it was added as the aeration started, the enzymic level decayed, but did not increase as notably when the aeration was interrupted. ALA-S in extracts of aerated cells underwent spontaneous activation when homogenates were stored at 4 degrees C. The effect of several activators on different forms of ALA-S is postulated in order to explain these findings.
Assuntos
Rodopseudomonas/fisiologia , 5-Aminolevulinato Sintetase/biossíntese , Proteínas de Bactérias/biossíntese , Bacterioclorofilas/biossíntese , Cloranfenicol/farmacologia , Oxigênio/farmacologia , Sintase do Porfobilinogênio/biossíntese , Rodopseudomonas/efeitos dos fármacos , Succinato-CoA Ligases/biossíntese , TemperaturaRESUMO
The high level of delta-aminolaevulinate synthetase (ALA-S) in Rhodopseudomonas palustris cells grown under photosynthetic conditions decreased when they were vigorously aerated; moreover, the bacteriochlorophyll synthesis suddenly stopped. When aeration was interrupted, enzymatic level increased notably, but bacteriochlorophyll level did not. Chloramphenicol added to cultures when aeration was interrupted did not affect the increase of enzymic level. When it was added as the aeration started, the enzymic level decayed, but did not increase as notably when the aeration was interrupted. ALA-S in extracts of aerated cells underwent spontaneous activation when homogenates were stored at 4 degrees C. The effect of several activators on different forms of ALA-S is postulated in order to explain these findings.
Assuntos
Adulto , Humanos , Feminino , Manifestações Neurológicas , Porfirias , Transtornos PsicofisiológicosAssuntos
Adulto , Humanos , Feminino , Transtornos Psicofisiológicos , Manifestações Neurológicas , PorfiriasRESUMO
The enzymatic formation of delta-aminolevulinic acid (ALA) in extracts of Rhodopseudomonas palustris has been studied. Some properties of delta-aminolevulinate synthetase (ALA-S), including molecular weight km for glycine and the inhibition of enzyme activity by ALA are reported.
Assuntos
5-Aminolevulinato Sintetase/metabolismo , Proteínas de Bactérias/metabolismo , Rodopseudomonas/enzimologia , 5-Aminolevulinato Sintetase/antagonistas & inibidores , 5-Aminolevulinato Sintetase/isolamento & purificação , Proteínas de Bactérias/isolamento & purificação , Cinética , Peso Molecular , Especificidade por SubstratoRESUMO
The enzymatic formation of delta-aminolevulinic acid (ALA) in extracts of Rhodopseudomonas palustris has been studied. Some properties of delta-aminolevulinate synthetase (ALA-S), including molecular weight km for glycine and the inhibition of enzyme activity by ALA are reported.
RESUMO
The enzymatic formation of delta-aminolevulinic acid (ALA) in extracts of Rhodopseudomonas palustris has been studied. Some properties of delta-aminolevulinate synthetase (ALA-S), including molecular weight km for glycine and the inhibition of enzyme activity by ALA are reported.