67 research outputs found
Inductive and Functional Types in Ludics
Ludics is a logical framework in which types/formulas are modelled by sets of terms with the same computational behaviour. This paper investigates the representation of inductive data types and functional types in ludics. We study their structure following a game semantics approach. Inductive types are interpreted as least fixed points, and we prove an internal completeness result giving an explicit construction for such fixed points. The interactive properties of the ludics interpretation of inductive and functional types are then studied. In particular, we identify which higher-order functions types fail to satisfy type safety, and we give a computational explanation
Types inductifs, fonctionnels et non-linéaires en ludique
This thesis investigates the types of ludics. Within the context of the CurryâHoward correspondence,l udics is a framework in which the dynamic aspects of both logic and programming can be studied. The basic objects, called designs, are untyped infinitary proofs that can also beseen as strategies from the perspective of game semantics, and a type or behaviour is a set of designs well-behaved with respect to interaction. We are interested in observing the interactive properties of behaviours. Our attention is particularly focused on behaviours representing the types of data and functions, and on non-linear behaviours which allow the duplication of objects. A new internal completeness result for infinite unions unveils the structure of inductive data types. Thanks to an analysis of the visitable paths, i.e., the possible execution traces, we prove that inductive and functional behaviours are regular, paving the way for a characterisation of MALL in ludics. We also show that a functional behaviour is pure, a property ensuring the safety of typing, if and only if it is not a type of functions taking functions as argument. Finally,we set the bases for a precise study of non-linearity in ludics by recovering a form of internal completeness and discussing the visitable paths.Cette thĂšse est consacrĂ©e Ă une exploration des types de la ludique. Sâinscrivant dans un contexte marquĂ© par la correspondance de CurryâHoward, la ludique est un cadre permettant dâĂ©tudier lâaspect dynamique de la logique et de la programmation. Les objets de base, appelĂ©s desseins, sont des preuves infinitaires non-typĂ©es qui peuvent Ă©galement ĂȘtre vues comme des stratĂ©gies sous lâangle de la sĂ©mantique des jeux, et un type ou comportement est un ensemble de desseins se conduisant de la mĂȘme maniĂšre du point de vue de lâinteraction. On sâintĂ©resse aux propriĂ©tĂ©s interactives des comportements. Notre attention se porte en particulier sur les comportements reprĂ©sentant les types de donnĂ©es et de fonctions, et sur les comportements non-linĂ©aires qui permettent la duplication dâobjets. Un nouveau rĂ©sultat de complĂ©tude interne pour les unions infinies dĂ©voile la structure des types de donnĂ©es inductifs. GrĂące Ă une analyse des chemins visitables,câest-Ă -dire des possibles traces dâexĂ©cution, on prouve que les comportements inductifs et fonctionnels sont rĂ©guliers, ouvrant la voie pour une caractĂ©risation de MALL en ludique. On montre Ă©galement quâun comportement fonctionnel est pur, une propriĂ©tĂ© garantissant la sĂ»retĂ© du typage, si et seulement si ce nâest pas un type de fonctions prenant des fonctions en argument. Enfin, on pose les bases dâune Ă©tude prĂ©cise de la non-linĂ©aritĂ© en ludique en retrouvant une forme de complĂ©tude interne et en discutant des chemins visitables
Chemical Ecology of the toxic dinoflagellate Ostreopsis cf. ovata in N.W. Mediterranean Sea
Les microalgues toxiques sont connues pour produire un grand nombre de mĂ©tabolites, dont les effets sur lâenvironnement demeurent relativement mĂ©connus Ă ce jour. Dans ce contexte, le travail prĂ©sentĂ© ici sâest focalisĂ© sur lâĂ©cologie chimique du dinoflagellĂ© benthique toxique Ostreopsis cf. ovata en MĂ©diterranĂ©e nord occidentale. Dans un premier temps, un suivi de lâabondance cellulaire dâO. cf. ovata sur les substrats biotiques (macroalgues) ainsi que dans la colonne dâeau, a Ă©tĂ© rĂ©alisĂ© Ă diffĂ©rentes Ă©chelles de temps et dâespace, permettant de confirmer la nature tychoplanctonique de ce dinoflagellĂ©. En raison de ces migrations journaliĂšres, il va donc impacter aussi bien les Ă©cosystĂšmes benthiques que planctoniques. Afin dâĂ©tudier les interactions quâO. cf. ovata entretient avec son environnement au cours de ces diffĂ©rentes phases, nous avons Ă©valuĂ© lâeffet dâO. cf. ovata sur la survie, la croissance et le mĂ©tabolisme secondaire de diffĂ©rents modĂšles biologiques incluant un compĂ©titeur (diatomĂ©e) et plusieurs espĂšces de prĂ©dateurs directs (copĂ©podes benthiques et planctoniques) et indirects (oursins) au cours dâanalyses in situ et en laboratoire. Les suivis rĂ©alisĂ©s in situ et les expĂ©riences en laboratoire nâont pas permis de mettre en Ă©vidence un effet nĂ©faste dâO. cf ovata sur la physiologie et le comportement des oursins, suggĂ©rant que câest lâhypoxie engendrĂ©e par les efflorescences dâO. cf. ovata qui est le facteur Ă lâorigine des mortalitĂ©s de masse dâinvertĂ©brĂ©s dĂ©crites en milieu naturel. En revanche, nos rĂ©sultats montrent quâO. cf. ovata impacte nĂ©gativement la croissance des diatomĂ©es compĂ©titrices, tandis que ces derniĂšres inhibent en retour sa croissance et son efficacitĂ© photosynthĂ©tique. Concernant les interactions avec les copĂ©podes, nos rĂ©sultats montrent une rĂ©ponse espĂšce-dĂ©pendante, avec en particulier un effet reprotoxique sur les copĂ©podes benthiques. Afin dâanalyser plus rapidement, facilement et de façon reproductible la toxicitĂ© des diffĂ©rentes souches dâO. cf. ovata ainsi que lâĂ©volution de cette toxicitĂ© au cours dâune efflorescence, nous avons ensuite adaptĂ© Ă ce dinoflagellĂ© un test de toxicitĂ© utilisant le crustacĂ© Artemia fransciscana. Enfin, ces expĂ©rimentations ont Ă©tĂ© couplĂ©es Ă une approche mĂ©tabolomique qui a permis dâĂ©tudier la nature des mĂ©tabolites secondaires produits par O. cf ovata. Parmi ces mĂ©tabolites, les toxines semblent participer aux interactions biotiques mises en Ă©vidences au cours des expĂ©riences dĂ©crites prĂ©cĂ©demment. En outre, nos rĂ©sultats suggĂšrent que dâautres mĂ©tabolites, dont la nature nâest pas encore connue, contribuent Ă©galement Ă lâĂ©cologie chimique de cette espĂšce. En conclusion, notre travail montre quâO. cf. ovata, par la rĂ©currence de ses efflorescences, sa nature tychoplanctonique, lâabondance et la diversitĂ© des mĂ©tabolites secondaires quâil produit, sâavĂšre ĂȘtre un excellent modĂšle pour Ă©tudier lâĂ©cologie chimique des microalgues marines toxiques.Toxic microalgae are known to produce a large panel of secondary metabolites whose effect on the environment remains so far poorly understood. To better understand this ecological problematic, this thesis aimed to decipher the chemical ecology of the benthic, toxic dinoflagellate Ostreopsis cf. ovata in the Northern Occidental Mediterranean Sea. First, we realized a monitoring of O. cf. ovata abundances on biotic substrates (macroalgae) and in the water column to confirme the tychoplanctonic lifestyle of O. cf. ovata, meaning that this dinoflagellate alternatively switches between benthic and planktonic phase within a single day. Because of these daily changes, it thus impacts both benthic and planktonic ecosystems. In order to study the interactions between O. cf. ovata and its environment during both benthic and planktonic phases, we evaluated its impact on survival, growth, and metabolome of various biologic models, including competitors (diatoms), several direct (benthic and planktonic copepods) and indirect (sea urchins) predators during in situ and laboratory assays. Both in situ and laboratory monitoring could not reveal any effect of O. cf. ovata on the physiology and behavior of sea urchins, suggesting that the invertebrate mass mortality episodes that have been previously documented rather result of the hypoxia linked to O. cf ovata blooms. By contrast, our results showed that O. cf. ovata inhibits the growth of competitor diatoms, while the later in return inhibits photosynthetic efficiency and growth of O. cf. ovata. Finally, our results exhibited species-related effects on copepods, with most importantly reprotoxic effects on benthic species. To further analyze toxic effects of O. cf. ovata strains during blooms in a faster, easier and steadier way, we then adapted to this dinoflagellate an Artemia fransciscana based toxicity assay. Finally, this work was complemented by a metabolomic approach, which allowed us to identify the nature of the secondary metabolites produced by O. cf. ovata. Among these metabolites, toxins are likely to take part in the biological interactions mentioned above. In addition, our results further suggested that other metabolites of unknown nature also contribute to the chemical ecology of this species. In sum, our work demonstrates that O. cf. ovata is a valuable biological model to study chemical ecology of toxic marine microalgae, because of its frequent blooms, its tychoplanctonic lifestyle as well as the great diversity of secondary metabolites it produces
Ecologie chimique du dinoflagellé toxique Ostreopsis cf. ovata en Méditerranée Nord Occidentale
Toxic microalgae are known to produce a large panel of secondary metabolites whose effect on the environment remains so far poorly understood. To better understand this ecological problematic, this thesis aimed to decipher the chemical ecology of the benthic, toxic dinoflagellate Ostreopsis cf. ovata in the Northern Occidental Mediterranean Sea. First, we realized a monitoring of O. cf. ovata abundances on biotic substrates (macroalgae) and in the water column to confirme the tychoplanctonic lifestyle of O. cf. ovata, meaning that this dinoflagellate alternatively switches between benthic and planktonic phase within a single day. Because of these daily changes, it thus impacts both benthic and planktonic ecosystems. In order to study the interactions between O. cf. ovata and its environment during both benthic and planktonic phases, we evaluated its impact on survival, growth, and metabolome of various biologic models, including competitors (diatoms), several direct (benthic and planktonic copepods) and indirect (sea urchins) predators during in situ and laboratory assays. Both in situ and laboratory monitoring could not reveal any effect of O. cf. ovata on the physiology and behavior of sea urchins, suggesting that the invertebrate mass mortality episodes that have been previously documented rather result of the hypoxia linked to O. cf ovata blooms. By contrast, our results showed that O. cf. ovata inhibits the growth of competitor diatoms, while the later in return inhibits photosynthetic efficiency and growth of O. cf. ovata. Finally, our results exhibited species-related effects on copepods, with most importantly reprotoxic effects on benthic species. To further analyze toxic effects of O. cf. ovata strains during blooms in a faster, easier and steadier way, we then adapted to this dinoflagellate an Artemia fransciscana based toxicity assay. Finally, this work was complemented by a metabolomic approach, which allowed us to identify the nature of the secondary metabolites produced by O. cf. ovata. Among these metabolites, toxins are likely to take part in the biological interactions mentioned above. In addition, our results further suggested that other metabolites of unknown nature also contribute to the chemical ecology of this species. In sum, our work demonstrates that O. cf. ovata is a valuable biological model to study chemical ecology of toxic marine microalgae, because of its frequent blooms, its tychoplanctonic lifestyle as well as the great diversity of secondary metabolites it produces.Les microalgues toxiques sont connues pour produire un grand nombre de mĂ©tabolites, dont les effets sur lâenvironnement demeurent relativement mĂ©connus Ă ce jour. Dans ce contexte, le travail prĂ©sentĂ© ici sâest focalisĂ© sur lâĂ©cologie chimique du dinoflagellĂ© benthique toxique Ostreopsis cf. ovata en MĂ©diterranĂ©e nord occidentale. Dans un premier temps, un suivi de lâabondance cellulaire dâO. cf. ovata sur les substrats biotiques (macroalgues) ainsi que dans la colonne dâeau, a Ă©tĂ© rĂ©alisĂ© Ă diffĂ©rentes Ă©chelles de temps et dâespace, permettant de confirmer la nature tychoplanctonique de ce dinoflagellĂ©. En raison de ces migrations journaliĂšres, il va donc impacter aussi bien les Ă©cosystĂšmes benthiques que planctoniques. Afin dâĂ©tudier les interactions quâO. cf. ovata entretient avec son environnement au cours de ces diffĂ©rentes phases, nous avons Ă©valuĂ© lâeffet dâO. cf. ovata sur la survie, la croissance et le mĂ©tabolisme secondaire de diffĂ©rents modĂšles biologiques incluant un compĂ©titeur (diatomĂ©e) et plusieurs espĂšces de prĂ©dateurs directs (copĂ©podes benthiques et planctoniques) et indirects (oursins) au cours dâanalyses in situ et en laboratoire. Les suivis rĂ©alisĂ©s in situ et les expĂ©riences en laboratoire nâont pas permis de mettre en Ă©vidence un effet nĂ©faste dâO. cf ovata sur la physiologie et le comportement des oursins, suggĂ©rant que câest lâhypoxie engendrĂ©e par les efflorescences dâO. cf. ovata qui est le facteur Ă lâorigine des mortalitĂ©s de masse dâinvertĂ©brĂ©s dĂ©crites en milieu naturel. En revanche, nos rĂ©sultats montrent quâO. cf. ovata impacte nĂ©gativement la croissance des diatomĂ©es compĂ©titrices, tandis que ces derniĂšres inhibent en retour sa croissance et son efficacitĂ© photosynthĂ©tique. Concernant les interactions avec les copĂ©podes, nos rĂ©sultats montrent une rĂ©ponse espĂšce-dĂ©pendante, avec en particulier un effet reprotoxique sur les copĂ©podes benthiques. Afin dâanalyser plus rapidement, facilement et de façon reproductible la toxicitĂ© des diffĂ©rentes souches dâO. cf. ovata ainsi que lâĂ©volution de cette toxicitĂ© au cours dâune efflorescence, nous avons ensuite adaptĂ© Ă ce dinoflagellĂ© un test de toxicitĂ© utilisant le crustacĂ© Artemia fransciscana. Enfin, ces expĂ©rimentations ont Ă©tĂ© couplĂ©es Ă une approche mĂ©tabolomique qui a permis dâĂ©tudier la nature des mĂ©tabolites secondaires produits par O. cf ovata. Parmi ces mĂ©tabolites, les toxines semblent participer aux interactions biotiques mises en Ă©vidences au cours des expĂ©riences dĂ©crites prĂ©cĂ©demment. En outre, nos rĂ©sultats suggĂšrent que dâautres mĂ©tabolites, dont la nature nâest pas encore connue, contribuent Ă©galement Ă lâĂ©cologie chimique de cette espĂšce. En conclusion, notre travail montre quâO. cf. ovata, par la rĂ©currence de ses efflorescences, sa nature tychoplanctonique, lâabondance et la diversitĂ© des mĂ©tabolites secondaires quâil produit, sâavĂšre ĂȘtre un excellent modĂšle pour Ă©tudier lâĂ©cologie chimique des microalgues marines toxiques
HYDROCĂPHALIE ET CARDIOPATHIE HĂRĂDITAIRES EN RACE BOVINE LIMOUSINE
International audienc
Chemical Ecology of the Benthic Dinoflagellate Genus Ostreopsis: Review of Progress and Future Directions
International audienceThe genus Ostreopsis includes some species that produce high biomass blooms and/or synthesize toxic compounds that can be transferred through the marine food webs or aerosolized causing ecological, human health and socioeconomic impacts. Ostreopsis species are increasing their biogeographic distribution from tropical to more temperate waters and causing recurrent blooms in certain coastal areas, thus constituting an emerging concern worldwide. The proliferation capacity of Ostreopsis is due to a complex and poorly understood combination of multiple factors, and may be a paradigm of chemical ecology reviewed here. A first section summarizes the basic knowledge on the different Ostreopsis species, the toxins they produce and the described foodborne and airborne effects of Ostreopsis toxins on humans. Secondly, direct and indirect interactions between Ostreopsis species and their environment are reviewed. Mucopolysaccharide substances produced by the cells to attach to different substrates appear to be a key element on the chemical ecology and requires further study. However, this research is challenged by technical limitations to conduct ecologically realistic and harmonized studies where organisms can be in direct contact with Ostreopsis cells, their mucus and/or the released extracellular toxic compounds. Understanding the transfer mechanisms of these substances within the food web, potentially affecting humans is critical and requires further study with new analytical tools. Still, the progress in knowledge achieved in the last years, combined with experimental and field studies using cutting edge methods will facilitate to address the open questions on the chemical ecology of Ostreopsis and understand its bloom dynamics now, and under future climate and anthropogenic change scenarios
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