Hontela A. Role of calcium channels in cadmiuminduced disruption of cortisol synthesis in rainbow trout (Oncorhynchus mykiss

Abstract The mechanisms of toxicity of cadmium (Cd 2+ ) in adrenal steroidogenesis were investigated in vitro in adrenocortical cells of rainbow trout (Oncorhynchus mykiss). Toxicity of Cd 2+ was increased in absence of extracellular Ca 2+ , but was prevented in Ca 2+ -supplemented medium. Pretreatment of cells with BAY K8644 (BAY), an agonist of voltage-dependent calcium channels, increased the Cd 2+ -mediated inhibition of ACTH-stimulated secretion but not pregnenolone (PREG)-stimulated secretion. Nicardipine, an antagonist of voltage-dependent calcium channels, also increased the inhibition of adrenocorticotropic hormone (ACTH)-stimulated secretion by Cd 2+ . These results suggest that opening of voltage-dependent calcium channels with BAY may allow Cd 2+ entry at the same time as calcium, thus increasing toxicity of Cd 2+ , however voltage-dependent calcium channels may not be the only way of entry into adrenocortical cells. The influx of Cd 2+ , measured as intracellular Cd 2+ using Fluo-3 in PREG-stimulated adrenocortical cells, was significantly enhanced by the stimulation. These results suggest that the deleterious effect of Cd 2+ on cortisol steroidogenesis may be enhanced when the endocrine stress response is triggered

Data from: Metabolic traits of westslope cutthroat, introduced rainbow trout and their hybrids in an ecotonal hybrid zone along an elevation gradient

In the Upper Oldman River, Alberta, introduced non-native hatchery rainbow trout hybridize with native westslope cutthroat trout, resulting in a hybrid swarm. Rainbow trout dominate at low elevations (1400 m), and hybrids are numerically dominant in the mid-elevation range. We hypothesized that metabolism of rainbow trout would exceed that of cutthroat trout, and that the elevation gradient in genetic makeup would be mirrored by a gradient in metabolic traits, with intermediate traits in the hybrid dominated ecotone. Metabolic traits were measured and regressed against the genetic makeup of individuals and elevation. Rainbow trout had higher oxygen consumption rates (OCR), higher white muscle lactate dehydrogenase (LDH) and citrate synthase (CS) activity, and higher plasma acetylcholinesterase (AchE) than cutthroat trout. Hybrids had intermediate OCR and AchE, but LDH activity as high as rainbow trout. While hybrid zones are usually modeled as a balance between cross species mating and selection against hybrids, ecotonal hybrid zones, where hybrids proliferate in intermediate habitats and have traits that appear well suited to ecotonal conditions, have been proposed for some plants and animals, and may have important implications for resource management and conservation

Metabolic traits of westslope cutthroat trout, introduced rainbow trout and their hybrids in an ecotonal hybrid zone along an elevation gradient

In the Upper Oldman River, Alberta, introduced non-native hatchery rainbow trout (Oncorhynchus mykiss) hybridize with native westslope cutthroat trout (O. clarkii), resulting in a hybrid swarm. Rainbow trout dominate at low elevations (\u3c 1250 m) in the river mainstem, cutthroat in high-elevation tributaries (\u3e 1400 m), and hybrids are numerically dominant in the mid-elevation range. We hypothesized that metabolism of rainbow trout would exceed that of cutthroat trout, and that the elevation gradient in genetic makeup would be mirrored by a gradient in metabolic traits, with intermediate traits in the hybrid-dominated ecotone. Metabolic traits were measured and regressed against the genetic makeup of individuals and elevation. Rainbow trout had higher oxygen consumption rates (OCRs), higher white muscle lactate dehydrogenase (LDH), and citrate synthase (CS) activity, and higher plasma acetylcholinesterase (AchE) than cutthroat trout. Hybrids had intermediate OCRs and AchE, but LDH activity as high as rainbow trout. While hybrid zones are usually modelled as a balance between cross species mating and selection against hybrids, ecotonal hybrid zones, where hybrids proliferate in intermediate habitats and have traits that appear well suited to ecotonal conditions, have been proposed for some plants and animals, and may have important implications for resource management and conservation. (C) 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 5672

Rasmussen et al data file

The data set contains a number of measurements of metabolic traits measured on field caught fish (oxygen consumption rate, white muscle LDH and CS, and plasma acetylcholinesterase, together with the genotypes (pure rainbow trout, pure cutthroat trout or hybrid) body size data and the elevation of the site at which each was captured. These were the data used to generate the models presented in the paper

Contamination and Biomarkers in the Great Blue Heron, an Indicator

breeding colonies of the great blue heron on the St. Lawrence River and its 12 estuary (Que´bec, Canada) were investigated in the framework of a biomonitoring program. Fledglings from 13 colonies in freshwater were more contaminated with mercury, PCBs and many organic contaminants than 14 those from estuarine colonies. The level of contamination in the St. Lawrence River is generally below the 15 levels of toxicological effects for the great blue heron. The molar ratio of retinol: retinyl palmitate in heron 16 eggs was correlated with total PCBs (r=0.79) and mirex (r=0.90). In plasma, all biochemical parameters 17 were significantly different between freshwater and marine colonies. Plasma retinol concentrations at the 18 Dickerson and He´ron colonies were significantly lower compared with those at Grande Ile (p<0.05) and 19 Steamboat (p<0.001). Based on retinoid and b-carotene concentrations in eggs, low plasma retinol was not 20 associated with possible dietary deficiency. Plasma retinol was negatively correlated with many PCB 21 congeners, total PCBs (r=)0.78), p,p¢-DDE, trans-nonachlor and a-HCH. Similarly, the hormone T3 was 22 correlated with many PCB congeners, total PCBs (r=)0.69) and the same organochlorine chemicals. 23 Plasma LDH concentrations were different among freshwater colonies, Grande Ile and He´ron colonies 24 having LDH values significantly greater than those of Steamboat (respectively, p<0.05 and p<0.01). 25 Globally, the health status of the St. Lawrence great blue heron population was judged to be acceptable, 26 however, several biomarkers indicated positive responses to contaminants

Développement d’outils d’évaluation du milieu récepteur pour l’industrie minière

From 2001 to 2004, we conducted a research project to develop tools for the ecological assessment of aquatic environments receiving mining effluents. These tools were designed to contribute to better define environmental discharge objectives for these types of effluents. Our project focused on two rivers in the Abitibi-James Bay mining region in northwestern Quebec. The most convincing results of our research include the development of a technique for the direct measurement of the free metal ion in solution (Cd, Ni, Zn); the validation of three organisms as biomonitors of trace metal contamination in lotic environments: the burrowing larvae of the Ephemera Hexagenia limbata, the amphipod crustacean Hyalella azteca, the bivalve Pyganodon grandis; and the identification of a laboratory toxicity test using the microalga Pseudokirchneriella subcapitata as a metal-sensitive assay to test waters from the receiving environment.De 2001 a 2004, nous avons mené un projet de recherche visant a développer et/ou à valider des outils de diagnostic des effets écotoxicologiques des effluents miniers dans le milieu aquatique afin de mieux définir des objectifs environnementaux de rejets pour l’industrie minière. Ce projet a été réalisé sur deux rivières de la région minière de l’Abitibi-Baie-James dans le nord-ouest du Québec. Parmi les outils diagnostiques les plus importants qui ont été développés et/ou validés, notons une technique de mesure directe de l’ion métallique libre en solution (Cd, Ni, Zn) ; l’utilisation de trois organismes comme biomoniteurs de contamination métallique en milieu lotique : la larve fouisseuse de l’éphémère Hexagenia limbata, le crustacé amphipode Hyalella azteca, le bivalve Pyganodon grandis ; et le test de toxicité en laboratoire, sur l’eau du milieu récepteur, avec la micro-algue Pseudokirchneriella subcapitata