Histological and molecular changes in gill and liver of fish (Astyanax lacustris Lütken, 1875) exposed to water from the Doce basin after the rupture of a mining tailings dam in Mariana, MG, Brazil.

The effects of the rupture of a mining tailings dam were investigated using the gills and liver of Astyanax lacustris as a proxy for environmental quality. The fish were exposed for seven days to water sampled forming four groups: upstream of the dam rupture (P1), and 22 km (P2); 48 km (P3); and 70 km (P4) downstream from the dam rupture in the Doce River basin. The control group received dechlorinated tap water. The dissolved concentrations of metals were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). We evaluated the histology of the gills and liver, as well as, immunohistochemistry for HSP70 and Na+/K+ ATPase (NKA) in the gills, and for P-gp in liver. In all sites we observed a mix of metals, with higher concentrations of Mn, Cd, As, and Cu/Cr in P1, P2, P3, and P4, respectively. All treatments groups showed histological changes in gills and liver, with the highest amount of these alterations found in the P2 group. Disorganization of the secondary lamellae, epithelial lifting, and mitochondria-rich cells (MRC) were observed in the gills. The parenchyma of the liver was rather disorganized, and hepatocytes and nuclei showed hypertrophy, vacuolization and cytoplasmic degeneration. A higher immunoreaction of HSP70 in P2 when compared with the other groups and lower labeling of HSP70 in the P4 was registered. In P2 and P3, NKA-positive cells were observed with hypertrophy and disorganization. Morphometric analyses of the liver revealed that all treatment groups presented a lower immunolabeling of P-gp when compared with the control group. Thus, the experimental approach revealed that the water from Doce basin can promote histological alterations in fish's liver and gills, as well as modulation of disruption of ionic balance, cellular responses to stress, and cell detoxification pathways.

Parâmetros morfométricos da Lagoa Central ( Lagoa Santa, Estadode Minas Gerais ): comparação de duas metodologias / Morphometric features of Lagoa Central ( Lagoa Santa, Minas Gerais State ): comparison of two methodologies

O presente estudo avaliou a precisão de dois protocolos usados para a confecçãode uma carta batimétrica para a Lagoa Central (Lagoa Santa, Estado de Minas Gerais, Brasil).Numa segunda etapa, o estudo estimou todos os parâmetros morfométricos primários esecundários desse ambiente. Finalmente, o estudo avaliou a importância dessas informaçõesna qualidade de água e na ecologia geral do sistema. Os protocolos foram baseados no usode dois sistemas distintos, usados para o levantamento batimétrico: uma ecossondaBiosonics DT-X (Biosoncs Inc.) e um Ecobatímetro SonarLite (Ohmnex Ltda), ambosacoplados a um D-GPS (Differential Global Positioning System) para a obtenção dascoordenadas geográficas de cada profundidade medida. A Lagoa Central de Lagoa Santa éum pequeno lago natural, raso (Zmax < 7,5 m), com profundidade relativa baixa (Zr =0,5%) e formato côncavo. Essas características a tornam menos propensa à formação deestratificação térmica estável e, portanto, menos sensível à formação de gradientes químicosverticais na coluna de água. Essa configuração pode ser vista como um dos fatores principaisque impedem o agravamento do processo de eutrofização verificado nesse sistema.(AU)

The goal of this study was to verifythe utility and accuracy of two tools to obtain a bathymetric chart for Lagoa Central (LagoaSanta, State of Minas Gerais, Brazil) and also to assess the morphometric parameters of thelake and their implications in the ecology of this system. The tested tools were theBiosonics DT-X (Biosonics Inc.) echosounder and the SonarLite (Ohmnex Ltda)bathymeter, both coupled to a Differential Global Positioning System (DGPS) to obtain thegeographic coordinates associated with the depth in each point. Lagoa Central is a small,shallow (Zmax < 7.5 m), with low relative depth values (Zr = 0.5%) and concave. Thismakes the water body less prone to thermal stratification and more susceptible toeutrophication. Both investigated equipments demonstrated to be suitable for the survey,user-friendly, low-cost and with sub-metric accuracy.(AU)

Parâmetros morfométricos da Lagoa Central (Lagoa Santa, Estado de Minas Gerais): comparação de duas metodologias / Morphometric features of Lagoa Central (Lagoa Santa, Minas Gerais State): comparison of two methodologies

O presente estudo avaliou a precisão de dois protocolos usados para a confecção de uma carta batimétrica para a Lagoa Central (Lagoa Santa, Estado de Minas Gerais, Brasil). Numa segunda etapa, o estudo estimou todos os parâmetros morfométricos primários e secundários desse ambiente. Finalmente, o estudo avaliou a importância dessas informações na qualidade de água e na ecologia geral do sistema. Os protocolos foram baseados no uso de dois sistemas distintos, usados para o levantamento batimétrico: uma ecossonda Biosonics DT-X (Biosoncs Inc.) e um Ecobatímetro SonarLite (Ohmnex Ltda), ambos acoplados a um D-GPS (Differential Global Positioning System) para a obtenção das coordenadas geográficas de cada profundidade medida. A Lagoa Central de Lagoa Santa é um pequeno lago natural, raso (Zmax < 7,5 m), com profundidade relativa baixa (Zr = 0,5%) e formato côncavo. Essas características a tornam menos propensa à formação de estratificação térmica estável e, portanto, menos sensível à formação de gradientes químicos verticais na coluna de água. Essa configuração pode ser vista como um dos fatores principais que impedem o agravamento do processo de eutrofização verificado nesse sistema.

The goal of this study was to verify the utility and accuracy of two tools to obtain a bathymetric chart for Lagoa Central (Lagoa Santa, State of Minas Gerais, Brazil) and also to assess the morphometric parameters of the lake and their implications in the ecology of this system. The tested tools were the Biosonics DT-X (Biosonics Inc.) echosounder and the SonarLite (Ohmnex Ltda) bathymeter, both coupled to a Differential Global Positioning System (DGPS) to obtain the geographic coordinates associated with the depth in each point. Lagoa Central is a small, shallow (Z max < 7.5 m), with low relative depth values (Zr = 0.5%) and concave. This makes the water body less prone to thermal stratification and more susceptible to eutrophication. Both investigated equipments demonstrated to be suitable for the survey, user-friendly, low-cost and with sub-metric accuracy.