Harmful Elements in Estuarine and Coastal Systems

Estuaries and coastal zones are dynamic transitional systems which provide many economic and ecological benefits to humans, but also are an ideal habitat for other organisms as well. These areas are becoming contaminated by various anthropogenic activities due to a quick economic growth and urbanization. This chapter explores the sources, chemical speciation, sediment accumulation and removal mechanisms of the harmful elements in estuarine and coastal seawaters. It also describes the effects of toxic elements on aquatic flora and fauna. Finally, the toxic element pollution of the Venice Lagoon, a transitional water body located in the northeastern part of Italy, is discussed as a case study, by presenting the procedures adopted to measure the extent of the pollution, the impacts on organisms and the restoration activities

Localization of inorganic and organic mercury in the liver and kidney of Cyprinus carpio by autometallography

Mercury bioaccumulation in different tissues largely depends upon metal chemical form and has important implications on tissue-specific toxicity. Then, simple tools for mercury tissue localization are very useful for understanding the toxicity of mercurial compounds in fishes. In the present study, inorganic and organic mercury distribution was investigated in carp Cyprinus carpio, utilizing autometallography. Juvenile C. carpio were exposed through force-feeding with mercury contaminated pelleted food at doses of 0.5 μg g-1 of Hg+2 or MeHg twice at 15 days interval, and killed 15 days after the second exposure for sampling. Organic mercury was observed inside hepatocytes and in biliary ducts of liver, whereas inorganic form of mercury was observed only in biliary ducts. In the kidney, mercury was observed mainly in renal tubules, with the predominance of inorganic over organic mercury. The present study demonstrated that autometallography is a useful tool for the tissue localization of two mercurial compounds in the liver and kidney of C. carpio after trophic exposure.Keywords: Autometallography, mercury, liver, kidney, Cyprinus carpio

The FXR agonist 6ECDCA reduces hepatic steatosis and oxidative stress induced by ethanol and low-protein diet in mice

Excessive ethanol consumption can lead to development of hepatic steatosis. Since the FXR receptor regulates adipose cell function and liver lipid metabolism, the aim of this work was to examine the effects of the FXR agonist 6ECDCA on alcoholic liver steatosis development and on oxidative stress induced by ethanol consumption. Swiss mice (n=24) received a low-protein diet (6%) and a liquid diet containing 10% ethanol or water for 6weeks. In the last 15days mice received oral treatment with 6ECDCA (3mgkg(-1)) or 1% tween (vehicle). The experimental groups (n=6) were: water+tween, water+6ECDCA, ethanol+tween and ethanol+6ECDCA. Moreover, as a diet control, we used a basal group (n=6), fed by a normal-proteic diet (23%) and water. After the treatment period, the animals were anesthetized for sample collection to perform plasma biochemistry assays, hepatic oxidative stress assays, hepatic cholesterol and triglycerides measurements, liver histology and hepatic gene expression. Ethanol associated with low-protein diet induced hepatic oxidative stress, increased plasma transaminases and induced hepatic lipid accumulation. Many of these parameters were reversed by the administration of 6ECDCA, including amelioration of lipid accumulation and lipoperoxidation, and reduction of reactive oxygen species. These effects were possibly mediated by regulation of Srebpf1 and FAS gene expression, both reduced by the FXR agonist. Our data demonstrated that 6ECDCA reverses the accumulation of lipids in the liver and decreases the oxidative stress induced by ethanol and low-protein diet. This FXR agonist is promising as a potential therapy for alcoholic liver steatosi

Liver damages and nuclear abnormalities in erythrocytes of Atherinella brasiliensis (Actynopterigii, Atherinopsidade) from two beaches in Southeast of Brazil

There are few environmental studies using biomarkers for the species Atherinella brasiliensis in Brazil. In the present work, the presence of hepatic histopathological lesions and nuclear abnormalities in erythrocytes were investigated in A. brasiliensis from Lamberto, a beach under influence of domestic wastes and marine activities. For comparison, fish were also sampled in Puruba, a non-polluted beach, located in the northeastern of São Paulo State. The frequency of lesions found in liver was in higher numbers in individuals from Lamberto than Puruba beach. The most critical injuries observed in A. brasiliensis were the presence of necrotic areas, leucocytes infiltration and piknotic nucleus. A high occurrence of cells with vacuolization was also observed. The hepatic lesion index of the fish from Lamberto beach showed significant high values (Iorg=13) when compared with fish from Puruba beach (Iorg=7) suggesting the influence of the several human activities in the studied site. Notched and blebed nucleous were observed in this study, and significant differences were found between the studied sites. However, these differences did not reflect the total nuclear alterations.<br>Existem poucos estudos no Brasil usando biomarcadores em Atherinella brasiliensis. No presente trabalho foram investigadas a presença de lesões histopatológicas hepáticas e as alterações nucleares em eritrócitos de A. brasiliensis amostrados na praia do Lamberto, local submetido à influência de resíduos domésticos e atividades humanas. Para comparação, indivíduos da espécie foram também amostrados na praia de Puruba, local não impactado, localizado no noroeste do estado de São Paulo. Peixes provenientes da praia do Lamberto apresentaram lesões hepáticas em número maior do que aqueles da praia de Puruba. Áreas necróticas, infiltração de leucócitos e núcleos picnóticos foram os danos de maior importância observados em A. brasiliensis, apesar de uma elevada ocorrência de vacuolização também ter sido verificada. O índice de lesão hepática dos peixes da praia do Lamberto mostrou valores significantemente maiores (Iorg=13) quando comparados com o dos peixes da praia de Puruba (Iorg=7), sugerindo influência das diversas atividades humanas existentes na área avaliada. Em relação aos núcleos "notched" e "blebed", foram observadas diferenças significativas entre as áreas, mas não para as alterações nucleares totais