Impact de pollutions chimiques chroniques (hydrocarbures, pesticides) sur l'état sanitaire et le système immunitaire du poisson

L'écotoxicité des hydrocarbures et des pesticides, a été recherchée chez le poisson adulte à des concentrations d'exposition in vivo correspondant à celles retrouvées chroniquement in situ. Le statut sanitaire et l'état de santé ont été évalués chez le bar commun, Dicentrarchus labrax exposés à un mélange d'hydrocarbures via la fraction soluble d'un pétrole brut et chez la truite arc en ciel, Oncorhynchus mykiss contaminée à une substance active de pesticide, la pendiméthaline. Les molécules polluantes ont été quantifiées à la fois dans l'eau d'exposition et les poissons (muscles et bile), confirmant l'efficacité des systèmes expérimentaux utilisés. L'exposition chronique à ces polluants dégrade l'état sanitaire du poisson, augmentant le risque potentiel pour la santé du consommateur. De plus, l'état de santé du poisson évalué via le suivi de plusieurs paramètres physiologiques, biochimiques et immunologiques est perturbé. En effet, une leucopénie expliquée par une lymphopénie, ainsi qu'une diminution de l'activité phagocytaire sont systématiquement observées chez les poissons exposés aux xénobiotiques, affectant l'immunité adaptative et innée. Lors d'une épreuve infectieuse au virus de la septicémie hémorragique virale, la pendiméthaline entraîne une mortalité plus précoce des individus et un nombre de poissons séropositifs supérieur. Enfin, les impacts observés à des concentrations d'exposition inférieures aux concentrations sans effet prévisible (PNEC) estimées actuellement, soulignent l'intérêt de prendre en compte l'état sanitaire et les composants du système immunitaire des organismes aquatiques dans l'établissement de seuils de qualité environnementale.The ecotoxicity of hydrocarbons and pesticides, was investigated in adult fish at in vivo exposure concentrations similar to those found chronically in the natural environment. The sanitary status, i.e. the health status of fish, with regard to chemical pollution and physiological status, was evaluated in sea bass, Dicentrarchus labrax exposed to a mixture of hydrocarbons using the water soluble fraction of crude oil and in rainbow trout, Oncorhynchus mykiss, contaminated by an active substance present in pesticide, pendimethalin. The pollutant molecules were quantified both in the exposure water and the fish (muscle and bile), confirming the efficiency of the experimental systems used. Chronic exposure to these pollutants deteriorates sanitary status in fish, increasing the potential risk for the health of human consumers. In addition, the health of fish assessed by monitoring several physiological, biochemical and immunological parameters was shown to be disturbed. Indeed, leucopenia due to lymphopenia and a decrease in phagocytic activity were observed in fish whatever the experimental exposure conditions, affecting innate and adaptive immunity. Following the infectious challenge with the viral hemorrhagic septicemia virus, pendimethalin seemed to accelerate fish mortality and a high number of seropositive fish was recorded compared to the group of control fish. Finally, these effects were observed at exposure levels below the currently estimated predicted no-effect concentrations (PNEC), highlighting the importance of taking into account sanitary status and the components of the immune system in aquatic organisms when establishing environmental quality thresholds.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Impact of chronic exposure of rainbow trout, Oncorhynchus mykiss, to low doses of glyphosate or glyphosate-based herbicides

International audienceGlyphosate is an herbicidal active substance (AS) entering in the composition of a large diversity of pesticide products (glyphosate-based herbicides; GBH) used in modern intensive agriculture. This compound has a favorable environmental safety profile but was suspected to induce deleterious effects in aquatic organisms, with a potential effect of some associated co-formulants. This study aimed to assess the impact of direct and chronic exposure to glyphosate on the health status of rainbow trout, Oncorhynchus mykiss. A total of 36 genitors were exposed daily for 10 months to a dose of glyphosate representative of environmental concentrations (around 1 μg L-1) using the AS alone or two GBHs formulations (i.e. Roundup Innovert® and Viaglif Jardin®) and findings were compared to an unexposed control group (n=12). The effects of chemical exposure on the reproductive capacities, hemato-immunologic functions, energetic metabolism, oxidative stress and specific biomarkers of exposure were analyzed over a period of 4 months covering spawning. A limited mortality between 15% and 30% specific to the spawning occurred under all conditions. No differences were observed in reproduction parameters i.e. mean weights, relative fertility and fecundity. Red blood cell count, hematocrit index, mean corpuscular volume and white blood cell counts were similar for all the sampling dates. Significant changes were observed two months before spawning with a 70% decrease of the proportion of macrophages in trout exposed to Viaglif only and a reduction of 35% of the phagocytic activity in fish exposed to the two GBHs. Trends towards lower levels of expression of tumor necrosis factor-α (between 38% and 66%) were detected one month after the spawning for all contaminated conditions but without being statistically significant. Biomarkers of exposure, i.e. acetylcholine esterase and carbonic anhydrase activities, were not impacted and none of the chemical contaminants disturbed the oxidative stress or metabolism parameters measured. These results suggest that a 10 months exposure of rainbow trout to a concentration of 1 μg L-1 of glyphosate administered using the pure active substance or two GBHs did not significantly modify their global health including during the spawning period. The immunological disturbances observed will need to be further explored because they could have a major impact in response to infectious stress

Seawater carbonate chemistry and survival rate of F2 Dicentrarchus labrax after viral challenge

Background: Progressive CO2-induced ocean acidification (OA) impacts marine life in ways that are difficult to predict but are likely to become exacerbated over generations. Although marine fishes can balance acid–base homeostasis efficiently, indirect ionic regulation that alter neurosensory systems can result in behavioural abnormalities. In marine invertebrates, OA can also affect immune system function, but whether this is the case in marine fishes is not fully understood. Farmed fish are highly susceptible to disease outbreak, yet strategies for overcoming such threats in the wake of OA are wanting. Here, we exposed two generations of the European sea bass (Dicentrarchus labrax) to end-of-century predicted pH levels (IPCC RCP8.5), with parents (F1) being exposed for four years and their offspring (F2) for 18 months. Our design included a transcriptomic analysis of the olfactory rosette (collected from the F2) and a viral challenge (exposing F2 to betanodavirus) where we assessed survival rates. Results: We discovered transcriptomic trade-offs in both sensory and immune systems after long-term transgenerational exposure to OA. Specifically, RNA-Seq analysis of the olfactory rosette, the peripheral olfactory organ, from 18-months-old F2 revealed extensive regulation in genes involved in ion transport and neuronal signalling, including GABAergic signalling. We also detected OA-induced up-regulation of genes associated with odour transduction, synaptic plasticity, neuron excitability and wiring and down-regulation of genes involved in energy metabolism. Furthermore, OA-exposure induced up-regulation of genes involved in innate antiviral immunity (pathogen recognition receptors and interferon-stimulated genes) in combination with down-regulation of the protein biosynthetic machinery. Consistently, OA-exposed F2 challenged with betanodavirus, which causes damage to the nervous system of marine fish, had acquired improved resistance. Conclusion: F2 exposed to long-term transgenerational OA acclimation showed superior viral resistance, though as their metabolic and odour transduction programs were altered, odour-mediated behaviours might be consequently impacted. Although it is difficult to unveil how long-term OA impacts propagated between generations, our results reveal that, across generations, trade-offs in plastic responses is a core feature of the olfactory epithelium transcriptome in OA-exposed F2 offspring, and will have important consequences for how cultured and wild fish interacts with its environment

Immunological and metabolic effects of acute sublethal exposure to glyphosate or glyphosate-based herbicides on juvenile rainbow trout, Oncorhynchus mykiss

International audienceGlyphosate is a commonly used agrochemical active substance co-formulated in glyphosate-based herbicides (GBHs) whose environmental safety is still a subject of debate in the European Union. We evaluated the effects of acute sublethal exposure to glyphosate on rainbow trout by measuring changes in their metabolic and hemato-immunologic functions and their ability to survive a viral challenge. Juvenile fish were exposed for 96 h to 500 μg L−1 of glyphosate through the active substance alone or two GHBs, Roundup Innovert® and Viaglif Jardin®, and fish were then infected with the infectious hematopoietic necrosis virus. Red and white blood cell counts (RBCC and WBCC), as well as several enzymatic activities (citrate synthase, CS; cytochrome-c oxidase, CCO; lactate dehydrogenase, LDH; glucose-6-phosphate dehydrogenase, G6PDH; acetylcholinesterase, AChE), were measured 96 h after chemical contamination (S1), and 96 h post-viral infection (S2). Mortality rates were monitored, and virus titers at the mortality peaks and seropositivity of the survivors were analyzed at 60 days post-viral infection (S3). Cumulative mortalities, viral titers, and seropositivity induced by virus infection were similar among conditions. Hematological analysis revealed significant increases of 30% for RBCC for Roundup at S1, and of 22% for WBCC at S2. No changes were observed in metabolic enzyme activities at S1. At S2, CCO and G6PDH activities were significantly higher than controls in all the chemically contaminated groups (+61 to 62% and +65 to 138%, respectively). LDH and AChE activities were increased for the Viaglif (p = 0.07; +55%) and for glyphosate and Roundup conditions (p < 0.05, +62 to 79%), respectively. Rainbow trout acutely exposed to glyphosate or GBHs presented no major physiological changes. Viral infection revealed disruptions, potentially modulated by co-formulants, of hematological and metabolic parameters, showing that it is essential to consider the stressful natural environment of fish in the chemical assessment

Changes in defense capacity to infectious hematopoietic necrosis virus (IHNv) in rainbow trout intergenerationally exposed to glyphosate

International audienceGlyphosate, the most widely used herbicide active substance worldwide, has raised many scientific, political and public debates in the context of its recent re-registration in the European Union, highlighting in particular a lack of data concerning its potential generational effects. In this study, we investigated the intergenerational toxicity of this active substance used alone or coformulated in glyphosate-based herbicides (GBHs) on the ability of rainbow trout (Oncorhynchus mykiss) to face a viral challenge. Juvenile trout from parents exposed for eight months to four different chemical exposure conditions (non-exposed control, pure glyphosate, Roundup Innovert®, and Viaglif Jardin® were experimentally infected with the infectious hematopoietic necrosis virus (IHNv). Various enzymatic and hemato-immunological markers were assessed before and after the viral challenge. Chemical contamination with GBHs strongly modulated viral trout susceptibility. Pure glyphosate induced a cumulative mortality of 35.8%, comparable to the control (37.0%), which was significantly reduced with Roundup Innovert® (−9.9%) and increased (+14.8%) with Viaglif Jardin®. No modification was observed for the biomarkers analysed for any conditions. These results demonstrate that the nature of the co-formulants associated to glyphosate in GHBs can modulate the susceptibility of fish to pathogens

Developmental effect of parental or direct chronic exposure to environmental concentration of glyphosate on the larvae of rainbow trout, Oncorhynchus mykiss

International audienceThe environmental safety profile of glyphosate, the most commonly used herbicide worldwide, is still a subject of debate and little is known about the generational toxicity of this active substance (AS) and the associated commercial formulations called "glyphosate-based herbicides" (GBHs). This study investigated the impact of parental and direct exposure to 1μgL(-1) of glyphosate using the AS alone or one of two GBH formulations (i.e. Roundup Innovert® and Viaglif Jardin®) in the early developmental stages of rainbow trout. Three different modes of exposure on the F1 generation were studied: (1) intergenerational (i.e. fish only exposed through their parents); (2) direct (i.e. fish exposed only directly) and (3) multigenerational (i.e. fish both exposed intergenerationally and directly). The impact of chemical treatments on embryo-larval development (survival, biometry and malformations), swimming behaviour, biochemical markers of oxidative stress equilibrium (TBARS and catalase), acetylcholine esterase (AChE) and energy metabolism (citrate synthase, CS; cytochrome-c oxidase, CCO; lactate dehydrogenase, LDH; glucose-6-phosphate dehydrogenase, G6PDH) was explored. Chemical exposure did not affect the survival of F1 embryos or malformation rates. Direct exposure to the AS induced some biometric changes, such as reduction in head size (with a 10% decrease in head length), independently of co-formulants. Intergenerational exposure to the AS or the Roundup GBH increased swimming activity of the larvae, with increase of between 78 and 102% in travel speeds. Viaglif co-formulants appear to have counteracted this behavioural change. The minor changes detected in the assayed biochemical markers suggested that observed effects were not due to oxidative damage, AChE inhibition or alterations to energy metabolism. Nonetheless, multi- and intergenerational exposure to Roundup increased CS:CCO and LDH:CS ratios by 46% and 9%, respectively, with a potential modification of the aerobic-to-anaerobic energy production balance. These biochemical effects were not correlated with those observed on individual level of biological organization. Therefore, further studies on generational toxicity of glyphosate and its co-formulants are needed to identify the other mechanisms of glyphosate toxicity at the cellular level

Evaluation de l’effet probiotique potentiel de souches marines du genre Pseudoalteromonas chez des bars européens imprégnés puis infectés expérimentalement avec Vibrio harveyi

National audienc

Evaluation de l’effet probiotique potentiel de souches marines du genre Pseudoalteromonas chez des bars européens imprégnés puis infectés expérimentalement avec Vibrio harveyi

National audienc

MERSEL FISH: Development and validation of a new analytical approach for the simultaneous speciation analysis of mercury and selenium by HPLC ICP MS

Mercury (Hg) is one of the most hazardous chemicals to the environment and the most worrisome contaminant for public health. This is due to its extreme toxicity, particularly in the methylated form which is biomagnified in the food chain, the main pathway of contamination of the humans. The great ability of CH3Hg+ to be bioaccumulated in the aquatic food chain leads to considerably elevated levels of Hg in aquatic organisms, despite nearly immeasurable quantities in the water column. No maximum level for CH3Hg+ is yet regulated by the European commission (EC) in fishery products, despite its extreme toxicity. This is most likely arising from the difficulty in performing accurate speciation analysis of CH3Hg+ in complex matrices such as fishery products. It is also interesting to note that mercury bio-availability seems to be linked to the selenium levels. Although it was shown for a few decades that selenium (Se) shows protective effects against Hg bioaccumulation and toxicity, the mechanism is very poorly understood nowadays. This work report the development and optimization of a new analytical approach for the simultaneous speciation analysis of mercury (Hg2+ and CH3Hg+) and selenium (SeIV, Se VI, SeMet and SeCys) in fish by HPLC-ICP-MS. This method will be employed further for the assessment of dietary exposure to Hg & Se species bio-accumulation by fish, for the analysis of cooked samples as well as for the in vitro simulated digestion studies, to achieve the main aim of this study which is a deep assessment of the Hg-Se interaction in fish and the human dietary exposure.Este trabalho foi desenvolvido com o apoio da FCT.N/

The relationships between growth rate and mitochondrial metabolism varies over time

Mitochondrial metabolism varies significantly between individuals of the same species and can influence animal performance, such as growth. However, growth rate is usually determined before the mitochondrial assay. The hypothesis that natural variation in mitochondrial metabolic traits is linked to differences in both previous and upcoming growth remains untested. Using biopsies to collect tissue in a non-lethal manner, we tested this hypothesis in a fish model (Dicentrarchus labrax) by monitoring individual growth rate, measuring mitochondrial metabolic traits in the red muscle, and monitoring the growth of the same individuals after the mitochondrial assay. Individual variation in growth rate was consistent before and after the mitochondrial assay; however, the mitochondrial traits that explained growth variation differed between the growth rates determined before and after the mitochondrial assay. While past growth was correlated with the activity of the cytochrome c oxidase, a measure of mitochondrial density, future growth was linked to mitochondrial proton leak respiration. This is the first report of temporal shift in the relationship between growth rate and mitochondrial metabolic traits, suggesting an among-individual variation in temporal changes in mitochondrial traits. Our results emphasize the need to evaluate whether mitochondrial metabolic traits of individuals can change over time