Biomarker responses as indication of contaminant effects in Oreochromis niloticus

The current study investigated oxidative stress parameters (enzymes activities, metallothionein content and lipid peroxidation) in freshwater fish, Oreochromis niloticus, tilapia exposure to Monjolinho River (in 4 months of year: January, April, July and November). One critical site in Monjolinho River (site B) was assessed in comparison to a reference site (site A). Water pH and oxygen concentration was lower than that recommended by CONAMA (Brazilian National Environmental Committee), resolution 357/2005 for protection of aquatic communities, and ammonium and the metals Cu, Zn, Mn and Fe (on all months) concentrations were higher than the maximum concentration recommended. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were significantly decreased in liver and muscle in tila. pia from Monjolinho River, throughout the year, in relation to reference except in gills that SOD activity increased. Glutathione S-transferase (GST) activity was significantly increased in liver of the tilapia from Monjolinho River in all sites, in relation to reference except in gills that GST activity increased in July and decreased in November, suggesting that GST activity could be induced to neutralize the pollutants toxicity. On the other hand, GST activity was significantly decreased in white muscle indicating a toxic effect of pollutants, resulting in a decreased ability of tilapia to perform defense reactions associated to GSTs. The decrease of catalase (CAT) activity in gills of the O. niloticus together with the increase of SOD activity, could explain the increased lipid peroxidation (LPO) level in this organ. Metallothionein levels in liver and gills were significantly high in all sites. Results indicate that the exposure to metals caused severe damage to tissues; despite the consensually assumed antioxidant induction as a sign of exposure to contaminants the effects seem in part to be mediated by suppression of antioxidant system with SOD, CAT and GPx as potential candidates for tissues toxicity biomarkers of pollutants. (c) 2012 Elsevier Ltd. All rights reserved.

Antioxidant defenses and biochemical changes in the neotropical fish pacu, Piaractus mesopotamicus: Responses to single and combined copper and hypercarbia exposure

This study investigated the potentially detrimental effects of copper and elevated aquatic CO2 (hypercarbia), alone or in combination, on pacu, Piaractus mesopotamicus. Fish were exposed for 48 h to control (no copper addition in normocarbia), to 400 mu g Cu2+L-1, to hypercarbic (1% CO2; PCO2=6.9 mm Hg) water and to 400 mu g Cu2+L-1+ hypercarbia. In liver the single factors caused an increase in lipid hydroperoxide concentration that was not observed when the factors were combined. Copper exposure elicited increased hepatic superoxide dismutase activity, irrespective of aquatic CO2 level. On the other hand, the effects of copper on hepatic glutathione peroxidase activity were dependent on water CO2 levels. The two stressors combined did not affect hepatic catalase activity. Hypercarbic water caused a decline in plasma glucose concentration, but this was not observed when hypercarbia was combined with copper exposure. Copper caused a decrease in branchial Na+/K+-ATPase activity that was independent of water CO2 level. Copper caused an increase in branchial metallothionein concentration that was independent of water CO2 level. Thus, branchial metallothionein and Na+/K+-ATPase were effective biomarkers of copper exposure that were not affected by water CO2 level. (C) 2012 Elsevier Inc. All rights reserved.

Development of spermatogenesis in captive-bred Spix's yellow-toothed cavy (Galea spixii)

The aim of this study was to evaluate the phases of sexual development and spermatogenesis of Spix's yellow-toothed cavy (Galea spixii) based on analyses of the structural components of the testes. The testes of animals from 0 to 150 days of age were collected by orchiectomy, weighed, and processed for analysis by light microscopy. At 45 days of age, spermatozoa were seen in the tubular lumen. Spermatogenesis was not established in animals from 45 to 150 days of age. The stages of sexual development may be classified into the following phases: from birth to the age of 15 days (immature); 30 days of age (prepubertal); 45-105 days of age (pubertal); and 120 and 150 days of age (postpubertal). This is the first study to address the male reproductive biology of Spix's yellow-toothed cavy.