The Impact of Sublethal Concentrations of Treated Leachate on Nile tilápia (Oreochromis niloticus).

The objective of this study was to evaluate the impact of sublethal concentrations of treated landfill leachate on Oreochromis niloticus individuals after exposure for 96 h, by assessing biochemical, genotoxic and immunologic biomarkers. Among biochemical biomarkers (activities of ALT, AST and GST enzymes), the treated landfill leachate did not cause significant alterations on O. niloticus and did not significantly affect leukocytes used as an immunologic biomarker. On the other hand, treated leachate induced genotoxic damages, since an increase in erythrocytic micronuclei and in DNA damage (comet assay) were observed in fish exposed to all treatment (2, 4 and 6 mL L-1). Acute toxicity of treated leachate in O. niloticus caused only genotoxic changes in blood cells, showing that micronuclei and comet assay, together, are effective biomarkers in determining the acute toxicity of treated leachate in aquatic environments. This work also shows that leachate, although treated, caused some damages to O. niloticus, which indicates the employed treatment was not efficient in eliminating all genotoxic substances from the leachate.

Temperature affects the hypoxia tolerance of neotropical Cichlid Geophagus brasiliensis

Oxygen and temperature are the most limiting factors in aquatic environments. Several species are exposed to variations of these factors in water because of physical, chemical and biological processes. The objective of this study was to evaluate the metabolic profile and the tolerance to the hypoxia of Geophagus brasiliensis exposed to changes in temperature and oxygen availability. The fish were exposed to 20 and 90% of oxygen saturation combined with different temperatures (20°, 24° and 28° C) for 8 h. Hepatic and muscular glycogen, as well as the activities of lactate dehydrogenase (LDH), malate dehydrogenase (MDH), citrate synthase (CS) and their ratios were evaluated. Both glycogen and MDH activity showed a significant difference in the liver. While CS showed increased activity only in the heart. The increase in LDH activity in the white muscle shows the importance of the anaerobic pathway as energy source in this tissue. The MDH / LDH ratio increased in all tissues, while CS / LDH increased in the liver and decreased in the heart. Based on the results of the present study it may be concluded that this species used the anaerobic metabolism as the main strategy for hypoxia tolerance.(AU)

O oxigênio e a temperatura são os fatores mais limitantes em ambientes aquáticos. Várias espécies são expostas a variações destes fatores na água como resultado de processos físicos, químicos e biológicos. O estudo objetivou avaliar o perfil metabólico e a tolerância à hipóxia de Geophagus brasiliensis expostos a alterações na temperatura e disponibilidade de oxigênio. Os peixes foram expostos a 20% e 90% de saturação de oxigênio combinadas com diferentes temperaturas (20 ° C, 24 ° C e 28 ° C) durante 8h. Foram avaliados o glicogénio hepático e muscular, assim como as atividades das enzimas lactato desidrogenase (LDH), malato desidrogenase (MDH), citrato sintase (CS) e suas razões. Tanto o glicogênio quanto a atividade da MDH apresentaram diferença significativa no fígado. Enquanto a CS apresentou aumento de sua atividade apenas no coração. O aumento da atividade LDH no músculo branco mostra a importância da via anaeróbia como fonte de energia neste tecido. A razão MDH/LDH aumentou em todos os tecidos, enquanto CS/LDH apresentou aumento no fígado e diminuição no coração. Os resultados obtidos permitem concluir que esta espécie utilizou o metabolismo anaeróbio como principal estratégia de tolerância à hipóxia.(AU)

Seahorse (Hippocampus reidi) as a bioindicator of crude oil exposure.

This study explored the suitability of the seahorse Hippocampus reidi (Ginsburg, 1933) for assessing biomarkers of genotoxic effects and its use as a sentinel organism to detect the effects of acute exposure to petroleum hydrocarbons. Fish were exposed to three concentrations of crude oil (10, 20 and 30 g/kg) for 96 h, and the activity of phase II biotransformation enzyme glutathione S-transferase (GST) was measured. In addition, we performed genotoxicity assays, such as comet assay, micronucleus (MN) test and nuclear abnormalities (NA) induction, on the erythrocytes of the fish species. Our results revealed that the inhibition of hepatic GST activity in H. reidi was dependent on increasing crude oil concentrations. In contrast, an increase in the damage index (DI) and MN frequency were observed with increased crude oil concentrations. These results indicate that the alkaline comet assay and micronucleus test were suitable and useful in the evaluation of the genotoxicity of crude oil, which could improve determinations of the impact of oil spills on fish populations. In addition, H. reidi is a promising "sentinel organism" to detect the genotoxic impact of petroleum hydrocarbons.

Acute copper toxicity in juvenile fat snook Centropomus parallelus (Teleostei: Centropomidae) in sea water

Three experiments were designed to assess the accumulation and acute toxicity of copper (Cu) in juvenile fat snook Centropomus parallelus. The first experiment was performed to determine the 96-h lethal concentration (LC50) of Cu. The second experiment was designed to assess the effects of sublethal concentrations of Cu (0.47 and 0.94 mg/L), while the third one allowed us to test the recovery capacity of fish exposed to the sublethal concentrations Cu and kept in sea water without Cu addition. The LC50 value for Cu was found to be 1.88 mg/L Cu. Fish exposed to the sublethal concentrations of Cu showed a significant accumulation of Cu in gills at 96 h respect to the control ones (0.43 µg/g Cu). No significant difference was observed in the accumulation of Cu in gills between fish exposed to 0.47 mg/L (1.09 µg/g Cu) and 0.94 mg/L (1.26 µg/g Cu). Exposure (24 and 96 h) to the sublethal concentrations of Cu tested induced DNA damage in the erythrocytes. The results show that acute exposure to sublethal concentrations induces Cu accumulation and DNA damage in fish, these effects being recovered after 240 h in sea water without Cu addition.

Três experimentos foram realizados para avaliar o acúmulo e toxicidade aguda do cobre (Cu) em juvenis de robalo-peva Centropomus parallelus. O primeiro experimento foi realizado para determinar a concentração letal (96h-CL50) de Cu. O segundo experimento foi realizado para avaliar os efeitos de concentrações subletais de Cu (0,47 e 0,94 mg/L), enquanto o terceiro permitiu testar a capacidade de recuperação dos peixes expostos a concentrações subletais do Cu e posteriormente mantidos em água do mar sem acréscimo de Cu. O valor de LC50 encontrado para o Cu foi de 1,88 mg/L. Os peixes expostos as concentrações subletais de Cu mostraram um acúmulo significativo nas brânquias em relação ao controle em 96 h de exposição (0,43 µg/g Cu). Nenhuma diferença significativa foi observada entre os peixes expostos a 0,47 mg/L de Cu (1,09 µg/g) e 0,94 mg/L de Cu (1,26 µg/g). A exposição (24 e 96 h) para as concentrações subletais de Cu induziram danos no DNA. Os resultados mostram que a exposição aguda a concentrações subletais induz o acúmulo de Cu e danos ao DNA nas brânquias dos peixes, onde estes efeitos são recuperados após 240 h em água do mar sem adição de Cu.

Sodium fluxes in tamoatá, Hoplosternum litoralle, exposed to formation water from Urucu Reserve (Amazon, Brazil).

Formation water (produce water or oil field brine) from oil and gas production usually has high concentrations of soluble salts and metals. The objective of this study was to examine the effect of formation water from Urucu Reserve, Amazon, on whole-body uptake and internal distribution of newly accumulated Na+ in juvenile tamoatá, Hoplosternum litoralle. Groups of fish were submitted to nine treatments for 3 h in 400-ml chambers: control (well water), 5% formation water, and well water with respective concentrations of 5% formation water of Ca2+, Fe, Mn, Ba2+, Fe+Ca2+, Mn+Ca2+, and Ba+Ca2+ added. Specimens of tamoatá exposed to 5% formation water presented a very high Na+ influx, probably due to the high Na+ levels in this water. Waterborne Fe and Mn stimulated Na+ influx, but Fe increased Na+ efflux, causing Na+ loss. Waterborne Mn, on the other hand, decreased Na+ efflux, reducing Na+ loss by this species. Waterborne Ca2+ also affected Na+ influx but had no significant effect on net Na+ fluxes. These results demonstrated that spilling of formation water in ion-poor Amazon rivers would dramatically disrupt osmoregulatory balance of tamoatá and probably other Amazon fish species, impairing their survival and reduce biodiversity.

Effects of hypoxia and petroleum on the genotoxic and morphological parameters of Hippocampus reidi.

Hypoxia events are common in many aquatic systems, which may be a natural event or provoked by anthropogenic actions, as well as accidents involving oil occurring throughout the world are frequent. Thus, through the possibility of occurrence of these two situations in same place the purpose of this study was to evaluate if damage caused by crude oil on genotoxic and morphological parameters in the marine fish species Hippocampus reidi will be aggravated by events of severe hypoxia. Sea horses were exposed during 8h to the following conditions: crude oil (OIL), severe hypoxia (HYP), association of severe hypoxia and crude oil (HYP+OIL) and normoxia without contaminant (CONT). An increase in micronuclei observed in OIL and HYP+OIL groups indicates that the crude oil exposure was a determining factor in the micronuclei induction and hypoxia did not intensify this result. In comet assays, both petroleum and hypoxia provoke DNA damage. The most frequent histopathology in the control groups and in those exposed to OIL and HYP+OIL groups were: hypertrophy and capillary dilation; hypertrophy and hyperplasia; hypertrophy, epithelial "lifting" and epithelial hyperplasia. An elongation of the lamellae was observed in fish from the two groups exposed to hypoxia, probably due to the fact that these groups required a greater flow of blood in the gills to increase the efficiency of gas exchange, since they were in a hypoxic environment. In summary, the micronuclei test and comet assay can be used as a good biomarker of contamination by petroleum. The association of hypoxia with crude oil in some aspects may exacerbate the responses of fish, in the light of the increase in DNA damage and the alterations in thickness of the gill epithelium.

Metabolic adjustments in Satanoperca aff. jurupari (Perciformes: Cichlidae)

In this paper, we describe the enzyme levels and isozyme distribution in skeletal and heart muscle of Satanoperca aff. jurupari, (Cichlidae, subgroup Geophaginae). LDH and CS were measured in skeletal and heart muscle. Starch gel electrophoresis was used to determine the isozyme/allozyme patterns in different tissues; LDH, MDHs, PGM, PGI, ADH, G-6-PDH and SOD were screened for the numbers of loci, presence of alleles, and tissue specificity. The LDH/CS ratio in heart and skeletal muscle were 173.36 and 6.1, respectively, indicating anaerobic metabolism in the former and aerobic metabolism in the latter muscle. No inhibition by pyruvate (based on the ratios of LDH activity with 1 mM and 10 mM pyruvate) was detected in heart and skeletal muscle, indicating the presence of physiological plasticity in heart muscle. The heart can cope with anaerobic metabolism for short periods of hypoxia such as occurs in nature. Isozyme patterns for most of the enzymes analyzed were similar to the general patterns for advanced teleosts. S. aff. jurupari had no reduced LDH-B* expression in heart muscle, but the, MDHs-B* locus was duplicated, as reported for most Amazon cichlids species. Only three out of the 13 loci analyzed (PGM, PGI and SOD) were variable. These results are consistent with the metabolic profile and life style of the most cichlids. A low genetic variability may be a counterpart for plasticity, and may be guaranteed by the regulation of invariable structural genes