Cellular responses of Prochilodus lineatus hepatocytes after cylindrospermopsin exposure

AbstractCylindrospermopsin is a potent toxicant for eukaryotic cells produced by several cyanobacteria. Recently, primary hepatocyte cultures of Neotropical fish have been established, demonstrating to be a quite efficient in vitro model for cellular toxicology studies. In the current study, a protocol for culture of Prochilodus lineatus hepatocytes was established and utilized to investigate the cellular responses to purified cylindrospermopsin exposure. Hepatocytes were successfully dissociated with dispase, resulting in a cell yield of 6.36×107cellsg−1 of liver, viability of 97% and attachment on uncoated culture flasks. For investigation of cylindrospermopsin effects, hepatocytes were dissociated, cultured during 96h and exposed to three concentrations of the toxin (0.1, 1.0 or 10μgl−1) for 72h. Cylindrospermopsin exposure significantly decreased cell viability (0.1 and 1μgl−1) and multixenobiotic resistance mechanism, MXR (all exposed groups), but increased reactive oxygen/nitrogen species levels (all exposed groups) and lipid peroxidation (10μgl−1). On the other hand no significant alterations were observed for other biochemical biomarkers as 2GSH/GSSG ratio, protein carbonyl levels and DNA strand breaks or glutathione S-transferase and glucose 6-phosphate dehydrogenase activities. In conclusion, hepatocytes might be made sensitive to cylindrospermopsin, at least in part, due to reduction of xenobiotics and endobiotics efflux capacity by MXR. Additionally, the toxin exposure suggests important issues regarding hepatocytes survival at the lowest cylindrospermopsin concentrations

Diferentes densidades de estocagem na produção de alevinos de trairão (Hoplias cf. lacerdae) Effect of two stocking rates on the trairão (Hoplias cf. lacerdae) fingerlings performance

Alevinos de trairão (Hoplias cf. lacerdae), com peso e comprimento total médios de 12,52 g e 10,5 cm, respectivamente, previamente condicionados ao aceite de dietas artificiais, foram distribuídos em seis tanques de alvenaria (5m²) nas densidades de: 1 e 4 alevinos/m². Os peixes dos diferentes tratamentos foram alimentados ad libitum nos horários de 8 e 14 h com ração comercial extrusada contendo 42% de proteína bruta. A cada trinta dias realizou-se a troca do volume total de água de todos os tanques. Ao final do experimento (120 dias) foi avaliado o desempenho produtivo dos peixes, por meio da taxa de sobrevivência, conversão alimentar, ganhos em comprimento e em peso diário. Foram observadas taxas médias de sobrevivência de 86,7 e 96,7% para as densidades de 1 e 4 peixes/m², respectivamente. A conversão alimentar foi de 1,6 e 1,2; o ganho em peso diário e em comprimento de 0,70 e 0,38 g e 8,01 e 7,27 cm, respectivamente. Estes valores não diferiram entre si. Com os resultados obtidos pode-se concluir que as densidades de estocagem de 1 e 4 peixes/m² podem ser utilizadas no cultivo de alevinos de trairão sem que haja comprometimento no seu desempenho produtivo.<br>Trairão (Hoplias cf. lacerdae) fingerlings, averaging 12.52 g and 10.5 cm, respectively, previously trained to accept artificial feed, were stocked in six tanks (5 m²), under two stocking rates: 1 and 4 fingerling/m², constituting the treatments t1 and t2, respectively. The fishes of the different treatments were ad libitum fed an extruded commercial diet containing 42% crude protein, at 8 a.m. and 2 p.m. at each 30 days, the water volume of all tanks was 100% replaced. at the end of the experiment, 120 days, the fishes productive performance was evaluated by means of survival rate, feed:gain ratio and daily length and weight gains. average survival rates of 86.7 and 96.7% were observed for the stocking rates of 1 and 4 fish/m², respectively. feed:gain ratio of 1.6 and 1.2 and daily length and weight gains of .70 and .38 g and 8.01 and 7.27 cm, respectively, were obtained for both densities. these values did not differ from each other. it was concluded that it is viable to produce the trairao fingerlings, under the evaluated stocking rates, without reducing performance