Differential modulation of ammonia excretion, Rhesus glycoproteins and ion-regulation in common carp (Cyprinus carpio) following individual and combined exposure to waterborne copper and ammonia.

The main objective of this study was to understand the mode of interaction between waterborne copper (Cu) and high environmental ammonia (HEA) exposure on freshwater fish, and how they influence the toxicity of each other when present together. For this purpose, individual and combined effects of Cu and HEA were examined on selected physiological and ion-regulatory processes and changes at transcript level in the common carp (Cyprinus carpio). Juvenile carp were exposed to 2.6µM Cu (25% of the 96h LC50value) and to 0.65mM ammonia (25% of the 96h LC50value) singly and as a mixture for 12h, 24h, 48h, 84h and 180h. Responses such as ammonia (Jamm) and urea (Jurea) excretion rate, plasma ammonia and urea, plasma ions (Na(+), Cl(-) and K(+)), muscle water content (MWC) as well as branchial Na(+)/K(+)-ATPase (NKA) and H(+)-ATPase activity, and branchial mRNA expression of NKA, H(+)-ATPase, Na(+)/H(+) exchanger (NHE-3) and Rhesus (Rh) glycoproteins were investigated under experimental conditions. Results show that Jamm was inhibited during Cu exposure, while HEA exposed fish were able to increase excretion efficiently. In the combined exposure, Jamm remained at the control levels indicating that Cu and HEA abolished each other's effect. Expression of Rhcg (Rhcg-a and Rhcg-b) mRNA was upregulated during HEA, thereby facilitated ammonia efflux out of gills. On the contrary, Rhcg-a transcript level declined following Cu exposure which might account for Cu induced Jamm inhibition. Likewise, Rhcg-a was also down-regulated in Cu-HEA co-exposed fish whilst a temporary increment was noted for Rhch-b. Fish exposed to HEA displayed pronounced up-regulation in NKA expression and activity and stable plasma ion levels. In both the Cu exposure alone and combined Cu-HEA exposure, ion-osmo homeostasis was adversely affected, exemplified by the significant reduction in plasma [Na(+)] and [Cl(-)], and elevated plasma [K(+)], along with an elevation in MWC. These changes were accompanied by a decline in NKA activity. Gill H(+)-ATPase mRNA levels and activities were not affected by either Cu or HEA or both. Likewise, NHE-3 expression remained unaltered but tended to be numerically higher during HEA exposure. Overall, these data suggest that at equitoxic concentrations (25% of 96h LC50), the individual effect of Cu is more harmful while HEA induces quicker adaptive responses. Our findings also denote a competitive mode of interaction, exemplified by the inhibition of HEA -mediated adaptive responses in the presence of Cu.

Environmental quality of an estuary in Amazon delta using immunohistochemical and morphological analyses of gill as biomarkers / Qualidade ambiental de um estuário no delta amazônico utilizando análises imunohistoquímicas e morfológicas de brânquias como biomarcadores

In this study, histological, ultrastructural, and immunohistochemical observations of the gill tissue of two fish species (Plagioscion squamosissimus and Lithodoras dorsalis) were used as biomarkers to assess the ecological conditions of an estuary in the Amazon delta, by relating the health status of the fishes to environmental quality. The gill tissue was analyzed both qualitatively and semi-quantitatively. Marked differences in the type and severity of lesions were verified between species and among study sites. A variety of severe damages were confirmed histologically in specimens from the two impacted areas (B and C), including aneurysms, epithelial lifting, and intense hyperplasia. Electron microscopy and immunohistochemical analyses also revealed injuries in the gill tissue of specimens from these two areas. While, on area A only few specimens showed mild changes in gill tissues and rare marking of apoptosis. These results confirm the urgent need for the more effective control of the discharge of pollutants into the estuary as well as more effective urban planning, given the close proximity of a major industrial complex to residential areas.

Neste estudo foram utilizados biomarcadores histológicos, ultraestruturais e imunohistoquímicos em tecidos brânquiais de duas espécies de peixes, Plagioscion squamosissimus e Lithodoras dorsalis, para avaliar a situação ecológica em um estuário amazônico relacionando a saúde do peixe com a qualidade ambiental. O tecido branquial foi analisado qualitativamente e semiquantitativamente. Foram verificadas diferenças entre as espécies selecionadas e as áreas de estudo, no que se refere ao tipo e severidade das lesões no tecido branquial. Foi detectada uma variedade de alterações histopatológicas severas somente nos peixes capturados nas áreas B e C, tais como: Aneurisma, elevação epitelial e intensa hiperplasia. As análises de microscopia eletrônica e de imunohistoquímica confirmaram danos mais prejudiciais nas brânquias apenas nestas áreas de estudo. Enquanto que na área A poucos peixes apresentaram alterações leves nos tecidos e pouca marcação de apoptose. Estes resultados confirmam a necessidade de um efetivo controle dos dejetos de poluentes assim como um planejamento urbano eficaz nesta região, uma vez que esta área possui um complexo industrial importante próximo à área urbana.

Fish histopathology and catalase activity as biomarkers of the environmental quality of the industrial district on the Amazon estuary, Brazil / Histopatologia e atividade catalase em peixes como biomarcadores da qualidade ambiental no distrito industrial, estuário Amazônico, Brasil

The environment quality of an industrial district on the river Pará, Amazon estuary, Brazil, based on the assessment of histological alterations and on the determination of catalase activity of the hepatic tissue of two fish species, Plagioscion squamossissimus and Lithodoras dorsalis, is provided. Histopathological changes were evaluated semi-quantitatively and qualitatively. Mean Assessment Values (MAV) and Histological Alteration Index (HAI) of organ lesions were calculated for each zone under analysis, with different impact levels: Zone 1 (industrial district, with high contamination risk); Zone 2 (medium risk) and Zone 3 (minimum risk). Strong positive catalase activity and histopathological changes were reported in Zone 1. None of the specimens of either species captured in Zones 1 and 2 was healthy, whereas more than 60% of the specimens from Zone 3 presented healthy hepatic tissue. The principal alterations observed in the tissue of the two species included an increase in the number of Melanomacrophagous centers, fatty degeneration, inflammation, congestion, hepatitis and focal necrosis. The carnivorous P. squamosissimus presented higher levels of alteration than the herbivorous L. dorsalis. Results showed that local anthropogenic impacts were affecting the health of the two fish species under analysis.

Com o presente estudo foi avaliada a qualidade ambiental em um distrito industrial no rio Pará, estuário Amazônico, Brasil, baseado nas alterações histológicas e na determinação da atividade da catalase no fígado para duas espécies de peixes: Plagioscion squamossissimus e Lithodoras dorsalis. As mudanças histopatológicas foram avaliadas semiquantitativamente e qualitativamente. Os Valores Médios de Avaliação (MAV) e o índice de alteração histológica (IAH) das lesões nos órgãos foram calculados para cada zona com diferentes níveis de impacto: Zona 1 (distrito industrial, com risco alto de contaminação); Zona 2 (risco médio) e Zona 3 (risco mínimo). Na Zona 1 foi observada, para as duas espécies, forte atividade catalase positiva e algum tipo de alteração histopatológica. Não foram observados indivíduos saudáveis nas Zonas 1 e 2. Na zona 3, mais de 60% dos espécimes estudados apresentaram tecido hepático saudável. As principais alterações observadas no tecido hepático para as duas espécies foram: aumento dos centros melanocacrófagos, degeneração gordurosa, inflamação, congestão, hepatite e necrose focal. A espécie carnívora P. squamosissimus apresentou níveis mais elevados de alteração que o herbívoro L. dorsalis. Estes resultados mostram que as alterações da qualidade ambiental no entorno do distrito industrial está afetando a saúde destas espécies de peixes.

Branchial histopathological study of Brachyplatystoma rousseauxii ( Castelnau, 1855 ) in the Guajará bay, Belém, Pará State, Brazil / Estudo histopatológico da brânquia de Brachyplatystoma rousseauxii na baía do Guajará, Belém, Estado do Pará, Brasil

This work analyzes the morphological alterations in Brachyplatystoma rousseauxii gills and evaluates whether this species can be considered an environmental monitoring biomarker of Guajará Bay. Sampling was carried out in four areas around Belém, Brazil, in four annual periods: dry/wet season, wet season, wet/dry season and dry season. Water pH, temperature and suspended material were evaluated. A total of 36 specimens were collected. The second right gill arch of each animal was removed and immediately fixed and processed for histopathology analysis with light microscopy. The physicochemical analysis of the water during the study period showed slight acidity, temperature and material in suspension within normal levels. Histopathological analysis of the gills from 14 individuals from area I presented no alterations, and only 2 individuals from this area presented some significant type of alteration. In contrast, all individuals captured in areas II, III, and IV presented at least one of the following alterations: aneurism-like alterations, epithelial elevation, infiltration, cell proliferation and cell hypertrophy. Based on the gill histopathological analysis, this organ is considered a good biomarker and the native species B. rousseauxii could be used as a bioindicator for environmental monitoring.

O objetivo deste trabalho foi analisar as alterações morfológicas branquiais em Brachyplatystoma rousseauxii e verificar se esta espécie pode ser considerada como indicador biológico para o monitoramento ambiental da baía do Guajará. As coletas aconteceram em quatro áreas ao redor da cidade de Belém: I (controle), II, III e IV (forte influência antrópica), nos quatro períodos anuais: estação seco/chuvoso, estação chuvoso, estação chuvoso/seco e estação seco. Nesses períodos foram medidos pH, temperatura e material em suspensão. Foram capturados 36 exemplares. O segundo arco branquial direito de cada animal foi retirado, imediatamente fixado e processado para análise histopatológica. A análise físico-química da água revelou pH levemente ácido, a temperatura e o material em suspensão se encontravam nos parâmetros de normalidade. As análises histopatológicas das brânquias de 14 animais da área I não apresentaram alterações branquiais e somente dois revelaram algum tipo de alteração. Todos os indivíduos capturados nas áreas II, III e IV apresentaram pelo menos uma das seguintes alterações: aneurisma, elevação epitelial, infiltração, proliferação celular, fusão lamelar e hipertrofia celular. De acordo com as análises histopatológicas branquiais, este órgão é considerado como um bom biomarcador e a espécie nativa B. rousseauxii pode ser utilizada como bioindicador no monitoramento ambiental.