86 research outputs found
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, QuÂŽebec, 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
Characterization of the bioaccumulation and toxicity of copper pyrithione, an antifouling compound, on juveniles of rainbow trout
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, QuÂŽebec, 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 problÚmes
Les simulations Ă©ducatives adisciplinaires sont des animations informatiques dont lâapparence, les fonctions et lâinteractivitĂ© sont trĂšs proches des simulations habituelles mais qui, parce quâelles visent lâapprentissage ou lâĂ©valuation dâhabiletĂ©s gĂ©nĂ©riques, ont Ă©tĂ© construites dans une perspective dâĂ©vitement ou dâĂ©loignement disciplinaire. Nous avons dĂ©veloppĂ© trois simulations de ce type pour trois Ă©tudes distinctes. Dans la premiĂšre, des Ă©tudiants de premier cycle universitaire utilisaient deux simulations structurellement identiques, lâune disciplinaire et lâautre non. La seconde, menĂ©e auprĂšs dâĂ©tudiants en formation des maĂźtres, employait une simulation affichant des entitĂ©s apparentĂ©s Ă des objets existants mais relevant dâunivers disciplinaires diffĂ©rents. Dans la troisiĂšme, des Ă©lĂšves du secondaire utilisaient une simulation dâune activitĂ© simple (mettre au point une recette de cuisine). Les phĂ©nomĂšnes prĂ©sentĂ©s par ces trois simulations adisciplinaires Ă©taient rĂ©gis par des relations mathĂ©matiques Ă©lĂ©mentaires et arbitraires, souvent alĂ©atoires. Les deux premiĂšres proposaient aux participants une dĂ©marche dâinvestigation et de questionnement ouverte; la derniĂšre comprenait des tĂąches spĂ©cifiques (tests de quantitĂ©s, analyses des rĂ©sultats, observations de graphiques) pouvant susciter le raisonnement hypothĂ©ticodĂ©ductif tel quâon le mobilise dans la rĂ©solution de problĂšmes scientifiques. Nous prĂ©senterons briĂšvement ces simulations, en prĂ©cisant ce que nous entendons par leur nature adisciplinaire, puis dĂ©crirons nos questions et mĂ©thodes de recherche et, enfin, justifierons leur intĂ©rĂȘt pour lâĂ©tude de la rĂ©solution de problĂšmes
Le calcanéus « Regourdou 2 » : étude morphométrique comparative et discussion autour de sa place dans la variabilité des Néandertaliens
1 - Introduction En 2008, lors du rĂ©colement des collections au MusĂ©e National de PrĂ©histoire aux Eyzies-de-Tayac, des restes humains sont retrouvĂ©s dans les caisses de faune du site de Regourdou parmi lesquels des fragments de la ceinture pelvienne, un important fragment de fĂ©mur, une patella, des fragments du tibia et de la fibula gauche. Ces restes appartiennent au squelette Regourdou 1 (Madelaine et al. 2008) et ils complĂštent parfaitement lâinventaire des piĂšces dĂ©couvertes 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), QuÂŽebec, 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, QuÂŽebec, 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
0â3, 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 contrÎle total de la chaßne 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 prĂ©sentons quelques applications de lâimagerie mĂ©dicale et de la reconstitution 3D dans le domaine de lâanthropologie biologique. Lâacquisition et lâexploitation dâimages scanner CT permettent dâaccĂ©der aux structures internes, de reconstituer des parties manquantes et dâexploiter des caractĂ©ristiques bio-mĂ©caniques. Nous proposons Ă©galement lâargumentation dâune hypothĂšse culturelle en relation avec un amĂ©nagement pratiquĂ© sur un os humain
Cell wall biochemical alterations during Agrobacterium -mediated expression of haemagglutinin-based influenza virus-like vaccine particles in tobacco
International audienceInfluenza virusâlike 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. Plantâbased biotechnology allows for the largeâscale 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 Agrobacteriumâmediated 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 postâAgrobacterium infiltration. Indeed, Agrobacterium infection induced deposition of callose and lignin, modified the pectin methylesterification and increased both arabinosylation of RGâI side chains and the expression of arabinogalactan proteins. Moreover, these modifications were slightly greater in plants expressing haemagglutininâbased VLP than in plants infiltrated with the Agrobacterium strain containing only the p19 suppressor of silencing
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