Mortality, bioaccumulation and physiological responses in juvenile freshwater mussels (Lampsilis siliquoidea) chronically exposed to copper

As little is known about the toxic mode of action and sub-lethal effects of copper exposure in freshwater mussels, the study examined physiological effects of long-term copper exposure (survival, growth, copper bioaccumulation, whole-body ion content, oxygen consumption, filtration rate, ATPase activities, and biomarkers of oxidative stress) in juvenile (6 month old) mussels (Lampsilis siliquoidea). Results indicate that ionoregulatory disruption in freshwater mussels chronically exposed to copper is the main mechanism of toxicity and that redox parameters do not appear to be useful as indicators of sub-lethal copper toxicity

Anesthetic activity and bio-guided fractionation of the essential oil of Aloysia gratissima (Gillies & Hook.) Tronc. in silver catfish Rhamdia quelen

This work aimed to determine the efficacy of the essential oil of A. gratissima as anesthetic for silver catfish, and to perform the bio-guided fractionation of essential oil aiming to isolate compounds responsible for the noted effects. Fish were submitted to anesthesia bath with essential oil, its fractions and isolated compounds to determine time of anesthetic induction and recovery. Eugenol (50 mg L-1) was used as positive control. Essential oil of A. gratissima was effective as an anesthetic at concentrations of 300 to 900 mg L-1. Fish presented involuntary muscle contractions during induction and recovery. The bio-guided fractionation of essential oil furnishedE-(-)-pinocamphone, (-)-caryophyllene oxide, (-)-guaiol and (+)-spathulenol. E-(-)-pinocamphone caused the same side effects observed for essential oil. (-)-Caryophyllene oxide, (-)-guaiol and (+)-spathulenol showed only sedative effects at proportional concentrations to those of the constituents in essential oil. (+)-Spathulenol (51.2 mg L-1) promoted deep anesthesia without side effects. A higher concentration of (+)-spathulenol, and lower or absent amounts ofE-(-)-pinocamphone could contribute to increase the activity and safety of the essential oil of A. gratissima. (+)-Spathulenol showed potent sedative and anesthetic activities in silver catfish, and could be considered as a viable compound for the development of a new anesthetic

Survival, growth and metabolic parameters of silver catfish, Rhamdia quelen, juveniles exposed to different waterborne nitrite levels

High nitrite (NO2-) levels may develop in aquaculture systems due to high fish density, but studies of lethal concentration values and the effect of NO2- on metabolic parameters and growth are scarce. Consequently, in this study was verified the lethal concentration at 96 h (LC50-96h) for (NO2-) in juvenile silver catfish, Rhamdia quelen and the effect of four waterborne NO2- concentrations (0.06, 0.46, 1.19, and 1.52 mg.L-1) on growth, and hepatic and muscular lactate, glucose, glycogen and protein. Nitrite LC50-96h was 20.46 (confidence interval: 16.10-23.68) mg.L-1. In the growth experiment, exposure to NO2- did not affect weight, length or specific growth rate, but due to mortality (66.7% and 100% after 20 and 40 days, respectively), biomass of juveniles exposed to 1.52 mg.L-1 NO2- was significantly lower than the biomass of juveniles exposed to other treatments. Therefore, the safe level of nitrite for growth of silver catfish juveniles is below 1.19 mg.L-1 (2% of LC50-96h). Exposure of silver catfish to NO2- for 40 days reduced lactate levels in muscle, but lactate levels increased in liver tissue of fish maintained at 1.19 mg.L-1 NO2-. In addition, glucose levels in muscle and liver tissues were significantly lower in silver catfish exposed to the highest NO2- level. These results indicate that chronic NO2- exposure causes anaerobic substrate oxidation to meet energy demand.<br>Altos níveis de nitrito (NO2-) podem ocorrer em sistemas de cultivo com alta densidade de estocagem, mas análises sobre os valores de concentração letal e o efeito do NO2- em parâmetros metabólicos e no crescimento são escassos. Neste estudo foi analisada a concentração letal em 96 h (CL50-96h) para nitrito (NO2-) em juvenis de jundiá, Rhamdia quelen, e o efeito de quatro níveis de nitrito (0,06; 0,46; 1,19 e 1,52 mg.L-1) no crescimento e no lactato, glicose, glicogênio e proteína hepática e muscular. A CL50-96h para NO2- foi 20,46 (intervalo de confiança: 16,10-23,68) mg.L-1. No experimento de crescimento, a exposição ao NO2- não afetou o peso, comprimento ou taxa de crescimento específico, mas devido à mortalidade (66,7% e 100% após 20 e 40 dias, respectivamente), a biomassa dos juvenis expostos a 1,52 mg.L-1. NO2- foi significativamente mais baixa que a biomassa dos juvenis expostos aos outros tratamentos. Deste modo, o nível seguro de NO2- para o crescimento do jundiá é abaixo de 1,19 mg.L-1 (2% da CL50-96h). A exposição do jundiá ao NO2- por 40 dias diminuiu os níveis de lactato no músculo, mas esses níveis aumentaram nos exemplares mantidos em 1,19 mg.L-1 NO2-. Além disso, os níveis de glicose no músculo e fígado foram significativamente mais baixos nos jundiás expostos à concentração mais elevada de NO2-. Estes resultados indicam que a exposição crônica ao NO2- provoca uma oxidação anaeróbica do substrato para obtenção de energia

Survival, growth and metabolic parameters of silver catfish, Rhamdia quelen, juveniles exposed to different waterborne nitrite levels

High nitrite (NO2-) levels may develop in aquaculture systems due to high fish density, but studies of lethal concentration values and the effect of NO2- on metabolic parameters and growth are scarce. Consequently, in this study was verified the lethal concentration at 96 h (LC50-96h) for (NO2-) in juvenile silver catfish, Rhamdia quelen and the effect of four waterborne NO2- concentrations (0.06, 0.46, 1.19, and 1.52 mg.L-1) on growth, and hepatic and muscular lactate, glucose, glycogen and protein. Nitrite LC50-96h was 20.46 (confidence interval: 16.10-23.68) mg.L-1. In the growth experiment, exposure to NO2- did not affect weight, length or specific growth rate, but due to mortality (66.7% and 100% after 20 and 40 days, respectively), biomass of juveniles exposed to 1.52 mg.L-1 NO2- was significantly lower than the biomass of juveniles exposed to other treatments. Therefore, the safe level of nitrite for growth of silver catfish juveniles is below 1.19 mg.L-1 (2% of LC50-96h). Exposure of silver catfish to NO2- for 40 days reduced lactate levels in muscle, but lactate levels increased in liver tissue of fish maintained at 1.19 mg.L-1 NO2-. In addition, glucose levels in muscle and liver tissues were significantly lower in silver catfish exposed to the highest NO2- level. These results indicate that chronic NO2- exposure causes anaerobic substrate oxidation to meet energy demand

Bioaccumulation and oxidative stress parameters in silver catfish (Rhamdia quelen) exposed to different thorium concentrations

The objective of this study was to evaluate the effect of chronic thorium (Th) exposure on bioaccumulation, metabolism (through biochemical parameters of the muscle) and oxidative parameters (lipidic peroxidation levels and antioxidant enzymes in the gills and in the hepatic and muscular tissues) of silver catfish (Rhamdia quelen). Silver catfish juveniles were exposed to different waterborne Th levels (in lg L1 ): 0 (control), 25.3 ± 3.2, 80.6 ± 12.0, 242.4 ± 35.6, and 747.2 ± 59.1 for 30 d. The gills and skin were the organs that accumulated the highest Th levels. The increase in the waterborne Th concentration corresponded to a progressive increase in the Th levels in the gills and kidney. Chronic Th exposure causes alterations in the oxidative parameters of silver catfish gills, which are correlated with the Th accumulation in this organ. The levels of GST decreased in the gills of fish exposed to 747.2 lg L1 Th and SOD activity decreased in silver catfish exposed to 242.4 and 747.2 lg L1 Th. In addition, the increase in the LPO in the gills exposed to 242.4 and 747.2 lg L1 Th suggests that higher oxidative damage occurred in the gills. However, in the liver and muscle, these alterations occurred mainly in the lowest waterborne Th level. Metabolic intermediates in the muscle were altered by Th exposure, but no clear relationship was found.Fil: Kochhann, Daiani. Universidade Federal de Santa Maria.; BrasilFil: Pavanato, Maria A.. Universidade Federal de Santa Maria.; BrasilFil: Llesuy, Susana Francisca. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Analítica y Fisicoquímica; ArgentinaFil: Correa, Lizelia M.. Universidade Federal de Santa Maria.; BrasilFil: Konzen Riffel, Ana P.. Universidade Federal de Santa Maria.; BrasilFil: Loro, Vania L.. Universidade Federal de Santa Maria.; BrasilFil: Mesko, Márcia F.. Universidade Estadual do Rio Grande do Sul ; Brasil. Universidade Federal de Santa Maria.; BrasilFil: Flores, Érico M.M.. Universidade Federal de Santa Maria.; BrasilFil: Dressler, Valderi L.. Universidade Federal de Santa Maria.; BrasilFil: Baldisserotto, Bernardo. Universidade Federal de Santa Maria.; Brasi

Metabolic and Behavior Changes in Surubim Acutely Exposed to a Glyphosate-Based Herbicide

This study examined the effect of glyphosate-based herbicide (Roundup Original), the major herbicide used in soybean crops in Mato Grosso state, at concentrations of 0, 2.25, 4.5, 7.5, and 15 mg L-1 on metabolic and behavior parameters of the hybrid fish surubim in an acute exposure lasting 96 h. Glycogen content, glucose, lactate, and protein levels were measured in different tissues. Plasma levels of cholesterol, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were also determined. Ventilatory frequency (VF) and swimming activity (SA) were considered behavior parameters. Results showed that herbicide exposure decreased plasma glucose levels and increased it in surubim liver. Lactate increased in both plasma and liver but decreased in muscle. Protein levels decreased in plasma and muscle but increased in liver. After herbicide exposure, liver and muscle glycogen was decreased. Cholesterol levels decreased in plasma at all concentrations tested. Plasma ALT increased, and no alterations were recorded for AST levels. VF increased after glyphosate exposure (5 min) and decreased after 96 h. SA showed differences among all groups (5 min). At the end of 96 h, SA was altered by the 7.5 mg L-1 concentration. Fish used anaerobic glycolysis as indicated by generally decreased glycogen levels and decreased lactate levels in muscle but increased ones in plasma and liver. We suggest that the studied parameters could be used as indicators of herbicide toxicity in surubim and may provide extremely important information for understanding the biology of the animal and its responsiveness to external stimuli (stressors)