Recrutement des symbiotes dans un contexte d'ensemencement : cas du Saumon atlantique (Salmo salar)

Ce projet s’est intéressé à l’impact qu’exerce l’ensemencement du Saumon atlantique sur le processus de recrutement des souches microbiennes commensales en milieu naturel. Puisque le taux de survie des saumons ensemencés reste faible par rapport à celui des individus sauvages de la même population génétique, il est essentiel d’évaluer dans quelle mesure l’acclimatation du microbiote aux conditions de pisciculture persiste après l’introduction des individus en milieu naturel. L’objectif de ce projet était de comparer la composition du microbiote de tacons de saumons, nés en pisciculture, deux mois suivant leur introduction en rivière avec celle des tacons sauvages. L’hypothèse était que l’élevage en pisciculture induit un effet à long terme sur le microbiote des individus ensemencés. Différents sites corporels ont été comparés; le mucus cutané, trois sections de l’intestin (proximale, médiane, et distale) ainsi que le bol alimentaire associé à chacune de ces trois sections, en plus du contenu stomacal. Enfin, tous les individus ont été génotypés à l’aide de 17 marqueurs microsatellites. Les résultats présentés montrent que les individus ensemencés ont un microbiote différent de celui de leurs congénères sauvages. Ces résultats mettent en évidence une empreinte sur le microbiote des conditions précoces. Une capacité d’acclimatation du microbiote cutané ainsi qu’une forte résistance à la colonisation du microbiote intestinal aux bactéries sauvages ont été notés. Ce projet génère des connaissances inédites dans le domaine de l’écologie microbienne, utilisables pour l’optimisation des méthodes de conservation et supporte les recommandations de reconstituer le plus possible l’environnement naturel lors de l’élevage de poissons destinés à la restauration de populations naturelles. Des études complémentaires seront nécessaires afin d’approfondir notre compréhension des processus moléculaires liés au recrutement du microbiote et sur la relation entre la faible survie des individus ensemencés et l’impossibilité de recruter certaines fonctions bactériennes clés après l’ensemencement.Here we examine the impact exerted by the Atlantic salmon stocking methods on the microbiota recruitment processes of microbial commensals in the wild. Because mortality rate of stocked salmon remains higher than that of wild ones despite sharing the same genetic background, it becomes essential to assess to which extent the acclimation of the microbiota in hatchery persists after the introduction of fishes in the wild. Our objective was to compare hatchery reared and stocked parrs with wild parrs’ microbiota belonging to the same genetic population, two months after stocking. We hypothesized that rearing conditions in hatcheries had long-term effects on the microbiota of stocked parrs after stocking. To do so, we examined the microbiota composition from various samples of stocked and wild parrs; the cutaneous mucus, three sections of the intestine (proximal, median and posterior) and the food bowl associated to these sections, as well as the stomach content. In addition, all specimens were genotyped with 17 microsatellites markers. The results show that stocked parrs’ microbiota differs than that from their wild relatives and suggest that hatchery conditions have long term effects on the microbiota. Moreover, our results suggest an imprinting on the microbiota associated with early conditions. Moreover, a high adaptive capacity of the cutaneous mucus microbiota and a high colonization resistance of the intestinal microbiota were observed. In addition to generate knowledge regarding the long-term effects of early life conditions on the microbiota composition, this project support previous recommendation to mimic the natural environment (including the microbial environment) in hatchery for conservation programs. Further studies on the molecular processes occurring during the microbiota ontogeny in hatchery as well as on the contribution of the microbiota for stocked parrs’ survival after their introduction in the wildand their incapacity to recruit key symbionts in the wild would be needed

Exploring justice tensions in the Barnahus model

Barnahus is to support children and their families during the justice and recovery process from experiencing abuse or violence. Yet, many perspectives of justice exist in the multi-disciplinary systems involved in Barnahus. The intersection of these systems can cause tension, which affects service delivery and, ultimately, the experience of the justice and recovery journey. The purpose of this chapter is to outline the needs, rights, and responsibilities of those involved in Barnahus as key stakeholders, including children, their families, criminal justice professionals, social and health care professionals, and professionals working in non-governmental organisations (NGOs) that support children and families. We also discuss the justice-related tensions that arise in the Barnahus model and how Barnahus can situate and advance a child-friendly justice model

Sea Ice and Substratum Shape Extensive Kelp Forests in the Canadian Arctic

The coastal zone of the Canadian Arctic represents 10% of the world’s coastline and is one of the most rapidly changing marine regions on the planet. To predict the consequences of these environmental changes, a better understanding of how environmental gradients shape coastal habitat structure in this area is required. We quantified the abundance and diversity of canopy forming seaweeds throughout the nearshore zone (5–15 m) of the Eastern Canadian Arctic using diving surveys and benthic collections at 55 sites distributed over 3,000 km of coastline. Kelp forests were found throughout, covering on average 40.4% (±29.9 SD) of the seafloor across all sites and depths, despite thick sea ice and scarce hard substrata in some areas. Total standing macroalgal biomass ranged from 0 to 32 kg m–2 wet weight and averaged 3.7 kg m–2 (±0.6 SD) across all sites and depths. Kelps were less abundant at depths of 5 m compared to 10 or 15 m and distinct regional assemblages were related to sea ice cover, substratum type, and nutrient availability. The most common community configuration was a mixed assemblage of four species: Agarum clathratum (14.9% benthic cover ± 12.0 SD), Saccharina latissima (13% ± 14.7 SD), Alaria esculenta (5.4% ± 1.2 SD), and Laminaria solidungula (3.7% ± 4.9 SD). A. clathratum dominated northernmost regions and S. latissima and L. solidungula occurred at high abundance in regions with more open water days. In southeastern areas along the coast of northern Labrador, the coastal zone was mainly sea urchin barrens, with little vegetation. We found positive relationships between open water days (days without sea ice) and kelp biomass and seaweed diversity, suggesting kelp biomass could increase, and the species composition of kelp forests could shift, as sea ice diminishes in some areas of the Eastern Canadian Arctic. Our findings demonstrate the high potential productivity of this extensive coastal zone and highlight the need to better understand the ecology of this system and the services it provides.publishedVersio

Importance et rôle de la phosphatase PPEF1 dans les spermatozoïdes

La phosphatase PPEF1 (protein phosphatase with EF-hand domain 1) est impliquée dans plusieurs processus cellulaires chez les mammifères comme la réponse aux stress, la survie cellulaire et la prolifération. Cette protéine est présente de manière universelle chez les eucaryotes et elle est majoritairement exprimée dans le cerveau des tissus fœtaux et dans les testicules. Une expérience ayant pour but d’étudier le rôle de la calmoduline dans les mécanismes entourant l’activité des spermatozoïdes nous a permis de découvrir cette phosphatase. PPEF1 n’a jamais été caractérisée dans un contexte reproductif, et a été très peu étudiée de manière plus générale comparativement aux autres phosphatases. Cette étude vise à élucider le rôle de cette phosphatase dans les spermatozoïdes et à vérifier notre hypothèse selon laquelle elle pourrait être impliquée dans la motilité et la capacitation des spermatozoïdes. Les résultats obtenus démontrent la présence de cette protéine et de ses transcrits dans les testicules et les spermatozoïdes. PPEF1 est localisée aux membranes et palmitoylée ; la protéine est relocalisée dans les spermatozoïdes au cours de leur capacitation. L’immunoprécipitation de PPEF1 a permis d’identifier des interacteurs possibles, impliqués dans les processus biologiques de capacitation et de motilité des spermatozoïdes, de même que dans l’interaction avec l’ovocyte. L’immunoprécipitation de PPEF1, de même qu’une protéine recombinante, nous ont permis de déterminer que PPEF1 possède une activité phosphatase. Les résultats obtenus corroborent l’hypothèse de départ. Davantage d’études seront toutefois nécessaires pour déterminer les cibles de déphosphorylation et les interacteurs de PPEF1 dans les spermatozoïdes. Il s’agit d’une première étude sur la phosphatase PPEF1 dans un contexte reproductif.PPEF1 phosphatase (protein phosphatase with EF-hand domain 1) is involved in several cellprocesses such as stress response, cell survival and proliferation. This protein is ubiquitously expressed in eukaryotes, mostly in brain fetal tissues and in testis. A study to unravel the role ofcalmodulin in sperm function led us to the discovery of this phosphatase in spermatozoa. PPEF1 hasnever been studied in a reproductive context and has been poorly described compared to other phosphatases. The purpose of this study is to understand the role of this phosphatase in spermatozoa .Our hypothesis is that PPEF1 is involved in sperm motility and capacitation. Results show the presence of this protein and its transcript variants in testis and sperm cells. PPEF1 localizes to sperm membranes and is palmitoylated; the protein is relocated in spermatozoa during capacitation. Immunoprecipitation of PPEF1 led to the identification of putative interactors that are involved inbiological processes of capacitation and motility of spermatozoa, as well as in sperm-oocyte interaction. This protein shows a phosphatase activity when immunoprecipitated; it is also the case of a PPEF1 recombinant protein. Our results corroborate the initial hypothesis. Other studies will benecessary to identify the proteins de phosphorylated by PPEF1 and to confirm its interactions withother proteins in spermatozoa. It is the first study on the phosphatase PPEF1 in a reproductive context

Différenciation biotique et perte de plantes de milieux humides dans les tourbières ombrotrophes boisées

Le boisement est un phénomène de plus en plus observé dans les tourbières ombrotrophes en réponse aux pressions exercées par les activités humaines et le réchauffement climatique. Nous avons évalué les effets de la présence d’un couvert forestier sur la richesse et la diversité floristiques (alpha et bêta) des tourbières ombrotrophes dans 775 parcelles d’inventaires réparties dans 5 domaines ou sous-domaines bioclimatiques au Québec. Nos résultats montrent que la richesse et la diversité floristiques augmentent avec le couvert forestier, principalement dans les tourbières les plus méridionales. Cette hausse est associée à l’installation d’espèces vasculaires d’affinité terrestre et de mousses ayant comme substrats des débris ligneux. En contrepartie, nous observons une baisse d’espèces obligées des milieux humides et des sphaignes. Nous avons aussi montré que plus le couvert forestier des tourbières méridionales était élevé, plus les communautés floristiques étaient distinctes d’un site à l’autre. L’effet est moins important dans les régions plus nordiques probablement en raison d’un ensemble régional d’espèces plus semblable à celui des tourbières. En fonction de ces résultats, nous croyons important de réfléchir à des méthodes pour freiner ou ralentir le processus de boisement afin d’assurer la conservation de la flore particulière des tourbières.Because of human disturbances and climate warming, tree encroachment has become widespread in ombrotrophic peatlands (bogs). The present study used floristic data collected in 775 survey plots in bogs in 5 bioclimatic domains or subdomains in Québec (Canada), to evaluate the impact of this phenomenon on plant richness and alpha and beta diversity. The results showed that plant richness and diversity generally increased with tree cover, mainly in the southernmost bogs. This was due to the establishment of vascular plants with a stronger affinity for drier habitats and of mosses that grow on woody debris, as well as to a decrease in obligate wetlands species and Sphagnum mosses. By contrast, the effect was less significant in bogs in more northern regions. This was probably due to closer similarities between the local plant species assemblages and the species typically found within bogs. The results also showed that the difference in the floristic community between sites in southern bogs increased with increased tree cover. Based on these results, it is important to consider methods to stop or reduce the rate of tree encroachment to ensure the conservation of the unique flora found within bogs

Morphological differentiation in northern pike (Esox lucius L.): The influence of environmental conditions and sex on body shape

Morphological differentiation may allow individuals to cope with prevailing environmental conditions. Morphological differentiation in fish characterized by sagittiform shape and ambush predator behaviour, such as northern pike (Esox lucius Linnaeus, 1758), has rarely been addressed. Morphological differentiation was assessed in two rivers exhibiting contrasting flow regimes: a hydropeaking river characterized by large and frequent flows fluctuations and an unregulated river.. An increase in northern pike movement rate was observed in the hydropeaking river. Therefore, morphological features enhancing sustained and burst swimming, and manoeuvrability were expected. Our objectives are to: 1) compare morphology between the two rivers, and 2) assess morphological differentiation between sexes. Using geometric morphometrics, shape significantly diverged between rivers irrespective of sex and between sexes in the hydropeaking river. Individuals from the hydropeaking river had more elongated heads, deeper bodies and caudal peduncles, and longer dorsal fin insertions than individuals from the unregulated river. Caudal fin differences between rivers were not consistent between sexes. Morphological differentiation suggested a trade-off among adaptations for sustained and burst swimming, and manoeuvrability to cope with variable flows in a hydropeaking river. Morphological differentiation may allow the exploitation of spatially and temporally variable environmental conditions, including those stemming from river flow regulation.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author