RESUMO
Due to the presence of the exoskeleton, the moult cycle is a required event in the life of crustaceans. In order for the exoskeleton to be replaced, it is necessary for these animals to uptake water from the environment for their body tissues during the late pre-moult, ecdysis and in the early post-moult for the expansion of the new cuticle. The mechanisms and organs used to uptake water in these events are not yet completely clear. In this study, we investigated the participation of aquaporins and Na+/K+-ATPase in cells of two potential organs responsible for the uptake of water (gills and gut) at three different stages of the moult cycle in freshwater shrimp Palaemon argentinus. We showed the participation of these two proteins with different functional patterns in gills and intestinal cells as water uptake pathways for moult and early post-moult. Our results indicate that Na+/K+-ATPase promotes the necessary osmotic gradient in the gills for water uptake through the gut cells during the pre-moult. This process, in turn, remains active during the post-moult stage with the addition of water influx through the gill cells.
Assuntos
Aquaporinas/metabolismo , Proteínas de Artrópodes/metabolismo , Muda/fisiologia , Palaemonidae/fisiologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Água/metabolismo , Animais , Tamanho Celular , Cloretos/metabolismo , Feminino , Trato Gastrointestinal/citologia , Brânquias/citologia , Hemolinfa/metabolismo , Masculino , Osmose , Potássio/metabolismo , Sódio/metabolismoRESUMO
The present study evaluated the effects of low salinity on the early larval development of Oreochromis niloticus, specifically histological damage to white muscle, morphology of the yolk-sac surface and trunk area, and molecular expression of apoptosis and cell proliferation biomarkers. Newly hatched larvae were submitted to four salinity treatments for a period of 48 or 72 h, in duplicate: (S0) freshwater, (S2) 2 g l-1, (S4) 4 g l-1, and (S6) 6 g l-1NaCl. Larval development was examined using histology, electron microscopy, enzyme-linked immunosorbent assay (ELISA), and morphometry. At the yolk-sac surface, larvae of S4 and S6 displayed alterations to the apical opening of chloride cells that may be related to osmotic expenditure caused by the increased salinity. Caspase-3 expression did not differ significantly among treatments, however significantly lower proliferating cell nuclear antigen (PCNA) expression (P < 0.05) suggested minor cell proliferation in larvae of S4 and S6 compared with S0 and S2. Furthermore, there was a significant reduction in both trunk area and percentage of normal white muscle fibres (WF) in larvae of S4 and S6. Vacuolated areas and myofibrils concentrated at the cell periphery and found in the white muscle from larvae exposed to saline environments suggested disturbance to muscle development. Oedema and mononuclear infiltrate were also observed in the white muscle of S4 and S6 larvae. Together these results indicated that treatments with 4 and 6 g l-1 NaCl may cause osmoregulation expenditure, morphological alterations to the yolk-sac surface and histological damage to skeletal muscle that negatively affected the early larval development of O. niloticus.
Assuntos
Ciclídeos/crescimento & desenvolvimento , Larva/efeitos dos fármacos , Salinidade , Cloreto de Sódio/farmacologia , Animais , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Água Doce , Brânquias/citologia , Brânquias/efeitos dos fármacos , Brânquias/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Larva/ultraestrutura , Microscopia Eletrônica , Músculo Esquelético/citologia , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/crescimento & desenvolvimento , Osmorregulação/efeitos dos fármacosRESUMO
The gill structure of the Amazonian fish Arapaima gigas (Cuvier 1829) shows ontogenetic changes during development, particularly due the transition from the aquatic to the obligatory air breathing mode of respiration. However, three main cell types can be found in the gills: mitochondrial rich cells, pavement cells and mucous cells (MCs). The MCs are involved in the secretory pathway. The functions of the secreted molecules include mechanical protection of epithelia, protection against parasites and bacterial infection, and role on ion regulation. In this study, we analysed mucous cell location and mucous cell type, based on pH, during the development of A. gigas. Using samples obtained from the environment, gills were collected and fixed in buffered solution. Histological techniques for the identification of MCs were performed Alcian Blue (AB) and periodic acid-Schiff (PAS). The results showed the presence of PAS+ and AB+ cells in the whole filament in all examined fish. In animals less than 50 g, few MCs were present, and no differences were observed in AB+ and PAS+ cells. In animals weighing close to 500 g, more PAS+ cells than AB+ cells were observed, and in animals that weighed more than 1,000 g, more AB+ cells than PAS+ cells were observed. These observations may be a result of the ontogenetic changes in the gill epithelia, which can change the osmorespiratory compromise in ion regulation functions as well the glycosaminoglycans secreted by PAS cells, which in large animals can play a role in the protection against parasites and bacterial infection.
Assuntos
Peixes/crescimento & desenvolvimento , Brânquias/citologia , Mucosa/citologia , Animais , Brasil , Brânquias/crescimento & desenvolvimento , Lagos , Metacrilatos , Microscopia Eletrônica de Transmissão , Respiração , Vesículas Secretórias/ultraestrutura , Inclusão do TecidoRESUMO
ABSTRACT The gill mitochondria-rich cells of the juvenile Amazonian fish Colossoma macropomum were analyzed using light and scanning and transmission electron microscopy after 96 h exposure to 0.04 and 0.2 mM nitrite. Although the number of mitochondria-rich cells decreased significantly in the lamellar epithelium, no decrease was found in the interlamellar region of the gill filament. Nitrite exposure caused significant reduction on the apical surface area of individual mitochondria-rich cells (p < 0.05), with a resulting reduction of the fractional area of these cells in both the lamellar and filament epithelium. Swelling of endoplasmic reticulum cisternae, nuclear envelope and mitochondria were the main changes found in the mitochondria-rich cells. Cristae lysis and matrix vacuolization characterized the mitochondrial changes. The overall ultrastructural changes indicated cellular functional disruption caused by exposure to nitrite. The changes observed in the gill indicate that the cellular structures involved in the process of energy production become severely damaged by exposure to nitrite indicating irreversible damage conducting to cell death.
Assuntos
Animais , Morte Celular , Exposição Ambiental , Characidae , Brânquias/citologia , Brânquias/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Microscopia Eletrônica de Varredura , Análise de Variância , Microscopia Eletrônica de Transmissão , Nitritos/toxicidadeRESUMO
The gill mitochondria-rich cells of the juvenile Amazonian fish Colossoma macropomum were analyzed using light and scanning and transmission electron microscopy after 96 h exposure to 0.04 and 0.2 mM nitrite. Although the number of mitochondria-rich cells decreased significantly in the lamellar epithelium, no decrease was found in the interlamellar region of the gill filament. Nitrite exposure caused significant reduction on the apical surface area of individual mitochondria-rich cells (p < 0.05), with a resulting reduction of the fractional area of these cells in both the lamellar and filament epithelium. Swelling of endoplasmic reticulum cisternae, nuclear envelope and mitochondria were the main changes found in the mitochondria-rich cells. Cristae lysis and matrix vacuolization characterized the mitochondrial changes. The overall ultrastructural changes indicated cellular functional disruption caused by exposure to nitrite. The changes observed in the gill indicate that the cellular structures involved in the process of energy production become severely damaged by exposure to nitrite indicating irreversible damage conducting to cell death.
Assuntos
Morte Celular , Characidae , Exposição Ambiental , Brânquias/citologia , Brânquias/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Nitritos/toxicidade , Análise de Variância , Animais , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de TransmissãoRESUMO
Cytochrome P450 family 1 (CYP1) is involved in polycyclic aromatic hydrocarbons (PAHs) biotransformation. PAHs can induce CYP1 protein expression and enzyme activity, the latter being usually quantified as 7-ethoxyresorufin O-deethylase activity (EROD). The aim of this study was to characterize EROD activity in the bivalve mollusk Crassostrea brasiliana. EROD activity was evaluated in cytosolic and microsomal fractions of gills, digestive gland and mantle of C. brasiliana. No EROD activity was detected in mantle, but it was present in microsomal fraction of gills and digestive gland with NADPH as coenzyme. Optima temperature and pH for EROD assay were 30°C and 7.4, respectively. EROD apparent Km (Kmapp) was 4.32µM for gills and 5.56µM for digestive gland. EROD Vmax was 337.3fmol·min-1·mg of protein-1 in gills and 297.7fmol·min-1·mg of protein-1 in digestive gland. Compared to other bivalves, a higher Kmapp and a lower Vmax was found in oyster which may suggest that oyster CYP1-like enzyme has lower affinity for substrate 7-ethoxyresorufin (7-ER) than those species. CYP1 inhibitor ellipticine (ELP) inhibited EROD activity in all tested concentrations in both tissues. The higher ELP concentration, 100µM, inhibited 78% of EROD activity in gills and 47% in digestive gland. The CYP1 inhibitors α-naphthoflavone and furafylline did not inhibited EROD activity in microsomes of both tissues. In conclusion, EROD activity can be used to determine CYP1-like activity in oysters and possibly a CYP1A1/A2-like enzyme is responsible for this catalysis.
Assuntos
Crassostrea/enzimologia , Citocromo P-450 CYP1A1/metabolismo , Animais , Crassostrea/metabolismo , Brânquias/citologia , Concentração de Íons de Hidrogênio , Microssomos/metabolismo , Oxazinas/metabolismo , TemperaturaRESUMO
Gill cells of filter feeding mollusks have cellular defense mechanisms, such as multixenobiotic resistance (MXR), that allow them to extrude possible contaminants. To analyze the cytotoxicity and cellular defenses of gills in the clam Mesodesma mactroides, gill cells were exposed to copper in both iso- and hyposmotic solutions. Analysis of MXR activity by fluorescence microscopy showed that hyposmotic saline activated defenses, whereas the presence of copper in isosmotic solution inhibited the activation of defenses. Cell viability was decreased in cells exposed to copper in isosmotic saline, but not in cells exposed to hyposmotic saline. We conclude that when cells cannot defend themselves due to decreased MXR, cell death occurs. In addition, gill cells under hyposmotic conditions have a greater capacity for defense and a lower rate of cellular mortality than when they are maintained under isosmotic conditions.
Assuntos
Bivalves/citologia , Sobrevivência Celular/efeitos dos fármacos , Cobre/toxicidade , Resistência a Múltiplos Medicamentos/efeitos dos fármacos , Brânquias/citologia , Brânquias/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Animais , Bivalves/efeitos dos fármacos , Concentração Osmolar , Pressão Osmótica , Poluentes Químicos da Água/toxicidadeRESUMO
Carbofuran is a nematicide insecticide with a broad spectrum of action. Carbofuran has noxious effects in several species and has been banned in the USA and Europe; however, it is still used in Brazil. Aquatic organisms are not only exposed to pesticides but also to manufactured nanoparticles, and the potential interaction of these compounds therefore requires investigation. The aim of this study was to examine the histopathological alterations in the gills of Nile tilapia (Oreochromis niloticus) to determine possible effects of exposure to carbofuran, nitric acid-treated multiwalled carbon nanotubes (HNO3-MWCNTs) and the combination of carbofuran with nanotubes. Juvenile fish were exposed to different concentrations of carbofuran (0.1, 0.5, 2.0, 4.0 and 8.0mg/L), different concentrations of HNO3-MWCNTs (0.5, 1.0 and 2.0mg/L) or different concentrations of carbofuran (0.1, 0.5, 2.0, 4.0 and 8.0mg/L) with 1.0mg/L of HNO3-MWCNTs. After 24h of exposure, the animals were removed from the aquarium, the spinal cord was transversely sectioned, and the second gill arch was removed for histological evaluation. Common histological changes included dislocation of the epithelial cells, hyperplasia of the epithelial cells along the secondary lamellae, aneurism, and dilation and disarrangement of the capillaries. All the groups exposed to carbofuran demonstrated a dose-dependent correlation in the Histological Alteration Index; the values found for carbofuran and carbon nanotubes were up to 25% greater than for carbofuran alone. This result indicates an interaction between these toxicants, with enhanced ecotoxic effects. This work contributes to the understanding of the environmental impacts of nanomaterials on aquatic organisms, which is necessary for the sustainable development of nanotechnologies.
Assuntos
Carbofurano/toxicidade , Ciclídeos , Exposição Ambiental/efeitos adversos , Brânquias/efeitos dos fármacos , Inseticidas/toxicidade , Nanotubos de Carbono/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Brasil , Europa (Continente) , Brânquias/citologia , Brânquias/patologia , PraguicidasRESUMO
Pharmaceuticals, such as anti-inflammatory nonsteroidal drugs, are frequently detected in aquatic ecosystems. Studies about the effects of these substances in nontarget organisms, such as bivalves, are relevant. The aim of this study was to evaluate the effects on antioxidant status caused by ibuprofen (IBU) in oysters Crassostrea gigas exposed for 1, 4, and 7 days at concentrations 1 and 100 µg L(-1). Levels of IBU in tissues of oysters, as well as cell viability of hemocytes, were measured. The transcription of cytochrome P450 genes (CYP2AU2, CYP356A1, CYP3071A1, CYP30C1), glutathione S-transferase isoforms (GST-ω-like and GST-π-like), cyclooxygenase-like (COX-like), fatty acid binding protein-like (FABP-like), caspase-like, heat shock protein-like (HSP70-like), catalase-like (CAT-like), and the activity of catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione S-transferase (GST) were also evaluated in the gills of oysters. The highest levels of IBU were observed in animals exposed to 100 µg L(-1). A significant upregulation of CYP2AU1, CYP356A1, CYP3071A1, GST-ω-like, GST-π-like, COX-like, and FABP-like was observed in oysters exposed to IBU under different experimental conditions. Oysters exposed to 1 µg L(-1) for 7 days showed a significantly higher transcription of CYP2AU2, CYP356A1, CYP3071A1, GST-ω-like, and GST-π-like but lower GR activity. In conclusion, C. gigas exposed to environmentally relevant concentrations of IBU (1 µg L(-1)) exhibited increased transcription of certain genes and alterations on antioxidant and auxiliary enzymes, which could, in the the long term, cause damages to exposed organisms.
Assuntos
Crassostrea/efeitos dos fármacos , Crassostrea/metabolismo , Citotoxinas/toxicidade , Ecotoxicologia , Ibuprofeno/toxicidade , Transcrição Gênica/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Antioxidantes/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Crassostrea/citologia , Crassostrea/genética , Relação Dose-Resposta a Droga , Brânquias/citologia , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Hemócitos/citologia , Hemócitos/efeitos dos fármacosRESUMO
Roundup Transorb (RT) is a glyphosate-based herbicide and despite its wide use around the world there are few studies comparing the effects of the active ingredient with the formulated product. In this context the purpose of this study was to compare the genotoxicity of the active ingredient glyphosate with the formulated product RT in order to clarify whether the active ingredient and the surfactant of the RT formula may exert toxic effects on the DNA molecule in juveniles of fish Prochilodus lineatus. Erythrocytes and gill cells of fish exposed to glyphosate and to RT showed DNA damage scores significantly higher than control animals. These results revealed that both glyphosate itself and RT were genotoxic to gill cells and erythrocytes of P. lineatus, suggesting that their use should be carefully monitored considering their potential impact on tropical aquatic biota.