Live fast and die young: metal effects on condition and physiology of wild yellow perch from along two metal contamination gradients

Sherpa Romeo green journalThis review summarizes some of the main findings of our work with the Metals in the Environment Research Network examining seasonal and regional effects on metal accumulation, growth, condition, and physiology in wild yellow perch (Perca flavescens) from 10 lakes comprising two metal contamination gradients in the industrial regions of Sudbury, Ontario and Rouyn-Noranda, Qu´ebec, Canada. The specific objectives of this review are: (1) to propose threshold tissue metal concentrations to discriminate between fish from contaminated and reference sites; (2) to identify factors that can influence metal accumulation and fish condition; and (3) to define an experimental approach for measuring metal effects in wild yellow perch. Using tissue thresholds appeared useful not only for discriminating fish from clean or contaminated environments, but also provided a simple approach to examine metabolic consequences of tissue metal accumulation. Overall, fish from Sudbury grew faster, expressed higher aerobic capacities, and died younger, but also appeared better at limiting accumulation of some metals than Rouyn-Noranda fish. The condition of the latter fish was clearly more affected by metals than Sudbury fish. Finally, our dataset allows us to propose that yellow perch are highly suitable for ecological risk assessment studies of metal effects in wild fish, but that fish size, season, and region must be considered in sampling design and that several reference sites must be studied for meaningful conclusions to be reached.Ye

Seasonal and regional variations in metal contamination and condition indicators in yellow perch (Perca flavescens) along two polymetallic gradients. III. Energetic and physiological indicators

Sherpa Romeo green journalThe influences of metal contamination, fish size, season, and region on tissue metabolic capacities and protein concentrations were examined in yellow perch from two metal gradients (Sudbury, Ontario, and Rouyn-Noranda, Qu´ebec, Canada) in two seasons (spring and summer). In general, increased tissue Cu and Cd contamination was associated with lower aerobic capacities, suggesting direct metal inhibition of aerobic enzymes. However, our data also revealed that tissue Ni contamination positively affected aerobic capacities, possibly due to oxidative damage to mitochondrial membranes leading to compensatory increases in the activity of mitochondrial enzymes. Tissue aerobic capacities decreased, but anaerobic capacities increased, with size. Tissue protein concentrations and metabolic capacities were also influenced by season. A novel finding of this study is that size-corrected tissue enzyme activities can differ markedly in yellow perch sampled in the same season in similar lakes, but separated by a few hundred kilometers. Overall, the results from this large dataset support that tissue metabolic capacities are under seasonal and regional influences, but are also affected by metal contamination. Our study indicates that tissue metabolic enzyme activities should be considered as a tool for ecological risk assessment studies aiming at detecting metal stress in wild fish. However, fish should be sampled over a short period, and reference sites should be close to contaminated sitesYe

Simulations éducatives adisciplinaires et résolution de problèmes

Les simulations éducatives adisciplinaires sont des animations informatiques dont l’apparence, les fonctions et l’interactivité sont très proches des simulations habituelles mais qui, parce qu’elles visent l’apprentissage ou l’évaluation d’habiletés génériques, ont été construites dans une perspective d’évitement ou d’éloignement disciplinaire. Nous avons développé trois simulations de ce type pour trois études distinctes. Dans la première, des étudiants de premier cycle universitaire utilisaient deux simulations structurellement identiques, l’une disciplinaire et l’autre non. La seconde, menée auprès d’étudiants en formation des maîtres, employait une simulation affichant des entités apparentés à des objets existants mais relevant d’univers disciplinaires différents. Dans la troisième, des élèves du secondaire utilisaient une simulation d’une activité simple (mettre au point une recette de cuisine). Les phénomènes présentés par ces trois simulations adisciplinaires étaient régis par des relations mathématiques élémentaires et arbitraires, souvent aléatoires. Les deux premières proposaient aux participants une démarche d’investigation et de questionnement ouverte; la dernière comprenait des tâches spécifiques (tests de quantités, analyses des résultats, observations de graphiques) pouvant susciter le raisonnement hypothéticodéductif tel qu’on le mobilise dans la résolution de problèmes scientifiques. Nous présenterons brièvement ces simulations, en précisant ce que nous entendons par leur nature adisciplinaire, puis décrirons nos questions et méthodes de recherche et, enfin, justifierons leur intérêt pour l’étude de la résolution de problèmes

Le calcanéus « Regourdou 2 » : étude morphométrique comparative et discussion autour de sa place dans la variabilité des Néandertaliens

1 - Introduction En 2008, lors du récolement des collections au Musée National de Préhistoire aux Eyzies-de-Tayac, des restes humains sont retrouvés dans les caisses de faune du site de Regourdou parmi lesquels des fragments de la ceinture pelvienne, un important fragment de fémur, une patella, des fragments du tibia et de la fibula gauche. Ces restes appartiennent au squelette Regourdou 1 (Madelaine et al. 2008) et ils complètent parfaitement l’inventaire des pièces découvertes en septembre ..

Seasonal and regional variations of metal contamination and condition indicators in yellow perch (Perca flavescens) along two polymetallic gradients. I. Factors influencing tissue metal concentrations

Sherpa Romeo green journalThis study examined relationships among water, sediment, diet, and fish tissue metal (Cd, Cu, Ni, Se, and Zn) concentrations in yellow perch from metal gradients in two regions (Sudbury (S), Ontario, and Rouyn-Noranda (RN), Qu´ebec, Canada) in two seasons (spring and summer). The objectives of this study were (1) to examine the influences of aqueous and dietary metal contamination on yellow perch liver and kidney metal accumulation; (2) to compare the seasonal and regional variations in gut content and tissue metal concentrations along the two gradients studied; and (3) to investigate the potential of metals for tissue accumulation under conditions of life-long chronic exposure. Our results suggest a greater aqueous than dietary influence on tissue metal concentrations for all metals examined except Cd, where the opposite was observed. Metals did not accumulate in older fish, except for Cd that accumulated with age in RN, but not S, fish. Regional, but also metal-specific differences in metal handling capacities are proposed. Fish from neither region appeared capable of regulating tissue Cd concentrations, but fish from both regions regulated Zn tightly. Sudbury fish appeared better at regulating tissue Cu, Ni, and perhaps also Se concentrations than RN fish, suggesting acclimation or selection for metal tolerance. There were several significant seasonal effects on tissue metal concentrations. However, close examination of the dataset does not allow proposing the presence of a season-linked mechanism explaining these variations, precluding a modeling approach and implying that repeat sampling within and among years is required for proper ecological risk assessment.Ye

Seasonal and regional variations in metal contamination and condition indicators in yellow perch (Perca flavescens) along two polymetallic gradients. II. Growth patterns, longevity, and condition

Sherpa Romeo green journalWild yellow perch (Perca flavescens) were sampled from five lakes in each of two metal contamination gradients in Sudbury, Ontario, Canada (n = 1324) and Rouyn- Noranda, Qu´ebec, Canada (n = 1125) in the spring and summer of 2002 and 2003, respectively, in order to examine growth patterns, longevity, and the influences of season and region on fish condition. Fish from Rouyn-Noranda began rapid growth at a young age, whereas fish from Sudbury lakes showed slow growth rates between ages 0–3, after which growth rates improved. Fish from contaminated lakes grew faster and died younger than fish from reference lakes in both contamination gradients. Fish from Sudbury had lower condition than in Rouyn-Noranda, higher condition occurred in summer than spring, and fish from contaminated lakes had lower condition than those from cleaner lakes. Tissue Zn concentrations were correlated with fish condition and showed strong temporal stability. However, it is more likely that Zn covariates, such as Cd or Cu (which were more temporally variable) influenced condition, suggesting that long-term, broad-scale processes are more important than short-term, lake-specific processes for establishing growth patterns, longevity, and fish condition in metal-contaminated systems. Results from this study reveal that fish condition must be interpreted in the light of regional, seasonal, and other factors that can potentially influence fish growth patterns. Ecological risk assessments that fail to take these factors into account may draw erroneous conclusions about risk to indigenous populations.Ye

Imagerie médicale et patrimoine anthropologique : vers un contrôle total de la chaîne des traitements dans l'analyse morphométrique tridimensionnelle

International audienceThe objective of the present paper is to give some data in medical imaging and 3D reconstruction applied in bio-anthropological field. Scanner CT images are a powerful tool to explore internal structures, to reconstruct incomplete bones and to give biomechanical interpretation based on bone morphology. Further, we propose to argument a cultural hypothesis relatively to a deliberate treatment concerning a human boneNous présentons quelques applications de l’imagerie médicale et de la reconstitution 3D dans le domaine de l’anthropologie biologique. L’acquisition et l’exploitation d’images scanner CT permettent d’accéder aux structures internes, de reconstituer des parties manquantes et d’exploiter des caractéristiques bio-mécaniques. Nous proposons également l’argumentation d’une hypothèse culturelle en relation avec un aménagement pratiqué sur un os humain

Cell wall biochemical alterations during Agrobacterium -mediated expression of haemagglutinin-based influenza virus-like vaccine particles in tobacco

International audienceInfluenza virus‐like particles (VLPs) have been shown to induce a safe and potent immune response through both humoral and cellular responses. They represent promising novel influenza vaccines. Plant‐based biotechnology allows for the large‐scale production of VLPs of biopharmaceutical interest using different model organisms, including Nicotiana benthamiana plants. Through this platform, influenza VLPs bud from the plasma membrane and accumulate between the membrane and the plant cell wall. To design and optimize efficient production processes, a better understanding of the plant cell wall composition of infiltrated tobacco leaves is a major interest for the plant biotechnology industry. In this study, we have investigated the alteration of the biochemical composition of the cell walls of N. benthamiana leaves subjected to abiotic and biotic stresses induced by the Agrobacterium‐mediated transient transformation and the resulting high expression levels of influenza VLPs. Results show that abiotic stress due to vacuum infiltration without Agrobacterium did not induce any detectable modification of the leaf cell wall when compared to non infiltrated leaves. In contrast, various chemical changes of the leaf cell wall were observed post‐Agrobacterium infiltration. Indeed, Agrobacterium infection induced deposition of callose and lignin, modified the pectin methylesterification and increased both arabinosylation of RG‐I side chains and the expression of arabinogalactan proteins. Moreover, these modifications were slightly greater in plants expressing haemagglutinin‐based VLP than in plants infiltrated with the Agrobacterium strain containing only the p19 suppressor of silencing