Thesis (Ph. D.)--University of Wisconsin--Madison, 1944. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 36-38).

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La distomatosis bovina es una enfermedad que afecta enormemente a la ganadería a nivel nacional, no solo por la enfermedad en sí; si no también por las grandes pérdidas económicas que ocasiona y además por ser un problema en salud pública. Es causada por el tremátodo Fasciola hepatica y necesita del caracol del género Lymnaea para que se desarrolle su ciclo biológico. Este estudio tiene como objetivo determinar la prevalencia de Fasciola hepatica en bovinos beneficiados en el Centro de Faenamiento FRILISAC entre los años 2012 al 2015. Se evaluaron 48 Registros mensuales regionales de animales para beneficio según especie, sexo y procedencia del SENASA y 48 Consolidados mensuales de animales beneficiados y peso de carcasa según especie y sexo del SENASA pertenecientes al periodo de tiempo comprendido entre el mes de enero del 2012 hasta diciembre del 2015, de los cuales solamente se utilizó la información correspondiente a los bovinos y su procedencia; se almacenó por cada mes en una base de datos del programa Microsoft Office Excel y se analizó con tablas de frecuencias estadísticas. Los resultados demostraron que se benefició un total de 267 408 bovinos de los cuales 7 680 resultaron positivos a Fasciola hepatica, dando una prevalencia de 2.87%, en donde septiembre registra la mayor prevalencia con 5.29% (1219/23025) y de Junín registra la mayor prevalencia con 4.47% (830/18551). Además, se determinó que existió U$S 128 906.19 en pérdidas económicas directas producidas por el decomiso de hígados de bovinos parasitados con Fasciola hepatica.Bovine flukes is a disease that greatly affects livestock nationwide, not only by the disease itself; but also by large economic losses and also for being a public health problem. It is caused by the trematode Fasciola liver and needs snail Lymnaea gender to their biological cycle develops. This study aims was determine the prevalence of Fasciola hepatica in cattle slaughtered at the Center for Slaughtering FRILISAC between 2012 to 2015. Forty eight regional monthly records for the benefit animals were evaluated according to species, sex and origin of SENASA and 48 monthly Consolidated benefit animal and carcass weight per species and sex of SENASA belonging to the period between January 2012 to December 2015, of which only the share of cattle information and the source is used; It was stored for each month in a database of Microsoft Office Excel program and analyzed with statistical frequency tables. The results showed that a total of 267,408 cattle benefited 7,680 were positive to Fasciola hepatica, giving a prevalence of 2.87%, where in september recorded the highest prevalence with 5.29% (1219/23025) and Junín records higher prevalence with 4.47% (830/18551). In addition, it decided that there was U $ S 128 906.19 in direct economic losses caused by the seizure of parasitized livers of cattle with hepatic Fasciola.

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Long term memory (LTM) formation is a complex process involving signalling cascades, new protein synthesis and gene regulation. Increasing evidence demonstrates a role of intrinsic plasticity in memory formation, but the underlying molecular mechanisms remain relatively unknown. LTM was established using an aversive operant conditioning model in Lymnaea stagnalis. Using intracellular electrophysiology in an isolated preparation, increased gain of firing frequency was observed in the RPeD1 neuron after LTM. This provides the first demonstration of intrinsic plasticity after operant conditioning in RPeD1, a neuron required for the conditioned behaviour and LTM. I also determined the contribution of the transcription factor men1 to plasticity. Using in vivo RNAi silencing, I found that men1 is required for LTM and increasing RPeD1 excitability during consolidation, demonstrating men1-mediated intrinsic plasticity is critical for LTM. I propose a new model of memory formation in which men1-dependent increase of excitability during consolidation is required for LTM.

Long term memory (LTM) formation is a complex process involving signalling cascades, new protein synthesis and gene regulation. Increasing evidence demonstrates a role of intrinsic plasticity in memory formation, but the underlying molecular mechanisms remain relatively unknown. LTM was established using an aversive operant conditioning model in Lymnaea stagnalis. Using intracellular electrophysiology in an isolated preparation, increased gain of firing frequency was observed in the RPeD1 neuron after LTM. This provides the first demonstration of intrinsic plasticity after operant conditioning in RPeD1, a neuron required for the conditioned behaviour and LTM. I also determined the contribution of the transcription factor men1 to plasticity. Using in vivo RNAi silencing, I found that men1 is required for LTM and increasing RPeD1 excitability during consolidation, demonstrating men1-mediated intrinsic plasticity is critical for LTM. I propose a new model of memory formation in which men1-dependent increase of excitability during consolidation is required for LTM.

We hypothesized that populations exposed to chronic levels of genotoxins for many generations in situ will accumulate latent heritable genetic damage leading to increases in mutational load and decreased population fitness. Common pulmonate snails (Lymnaea stagnalis) were collected from three sites that differed in pollution level [Manitoulin Island (reference), Beauharnois (moderate pollution), and Varennes (highly polluted)]. These organisms have a rapid generation time and are capable of self-fertilization. Fitness indicators were clutch size, survival (hatching to day 30) and growth (length from hatching to day 90). Recessive deleterious mutations that have accumulated through time are masked as snails preferentially outcrossed, but are expressed when snails self-fertilize. Results obtained by comparing fitness components of snails derived from selfing and outcrossing experiments showed that in sites with higher levels of pollution inbreeding depression increased for clutch size and survival. Results for growth rate were similar to those for clutch size and survival in the two least polluted sites, but not for the most polluted site, due possibly to biased mortality of smaller snails at this site. After correction for size biased mortality, the growth estimates showed patterns similar for the two polluted sites when compared to the reference site. This study suggests that long-term in situ exposure to genotoxic pollution may effect population fitness due to the accumulation of latent heritable genetic damage.

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Les produits phytosanitaires contiennent des molécules qui peuvent interférer avec le système endocrinien et induire des effets délétères sur les êtres vivants. Ce sont des perturbateurs endocriniens. Afin d’assurer un niveau de protection satisfaisant pour les mollusques aquatiques, une bonne compréhension des perturbations du système endocrinien est nécessaire. L’organisation pour le développement et la coopération économique s’est exprimée en faveur de la mise en place de protocoles standards d’écotoxicité chez les mollusques, notamment sur la reproduction, dans le cadre des processus d’évaluation du risque écologique et des autorisations de mise sur le marché de nouvelles molécules. Cette thèse vise à proposer des tests standards et des outils d’analyse afin d’évaluer les effets de substances chimiques chez un escargot d’eau douce, Lymnaea stagnalis. Une série de tests de toxicité a été conduite dans laquelle les limnées ont été exposées à des androgènes, des oestrogènes et dessolvants. Les effets observés ont été évalués à l’aide d’approches statistiques standards et d’un modèle de toxicokinétique-toxicodynamique (TKTD). Les limnées ont montré une sensibilité uniquement au tributyltin et triphényltin à des concentrations réalistes d’un point de vue environnemental. Le triéthylène glycol et l’acétone étaient les solvants les moins nocifs. De plus, le modèle TKTD suggère un mécanisme généraliste dans l’action du composé. La manifestation des perturbations endocriniennes chez L. Stagnalis restent évasives et nécessitent d’autres recherches. Enfin, la thèse a montré que / Plant protection products and biocides may contain chemicals that interfere with the endocrine system and consequently induce adverse effects on wildlife. Such chemicals are known as endocrine disruptors (EDs). To ensure a satisfactory protection level for aquatic molluscs a comprehensive understanding of endocrine disruption is needed. The Organisation for Economic Co-operation and Development supports the standardisation of toxicity tests guideline on mollusc reproductive toxicity, which is intended for environmental risk assessments purposes. This PhD thesis aimed at improving toxicity test protocols and data analysis tools to evaluate effects of chemicals on the great pond snail Lymnaea stagnalis. A suite of toxicity tests was conducted in which snails were exposed to putative androgens (tributyltin, triphenyltin, methyltestosterone), putative oestrogens (alkylphenols and ethynyloestradiol), and solvents. Resulting effects were evaluated using standard statistical approachesand/or a toxicokinetic-toxicodynamic (TKTD) model. Snails were sensitive to tributyltin and triphenyltin, while none of the oestrogenic chemicals and methyltestosterone significantly impacted animals at environmentally relevant concentrations. Triethylene glycol and acetone were the least harmful solvents. Further, the analysis of data from the tributyltin test with the TKTD model suggested a generic mechanism of action of the compound (i.e., not specific for EDs). The demonstration of endocrine disruption in L. stagnalis remained elusive and deserves further research. Finally, the thesis highlight

Dans l'environnement, les organismes sont soumis à des stress de multiples natures (e.g., polluants et pathogènes/parasites). Dans ce contexte, le système immunitaire joue un rôle fondamental. La pression chimique exercée par les polluants peut impacter leur système immunitaire, affaiblir leur santé et les prédisposer à contracter des maladies infectieuses. En écotoxicologie, l'évaluation de marqueurs d'immunocompétence peut servir à diagnostiquer l'état de santé des organismes et mieux comprendre le danger immunotoxique des xénobiotiques. Lymnaea stagnalis est un gastéropode d'eau douce représentatif de nombreux milieux lentiques sur la planète. Des tests OCDE de reprotoxicité sont disponibles mais peu d'études se sont focalisées sur des paramètres immunotoxiques. Le premier axe de la thèse se porte sur la connaissance et le développement de méthodes pour évaluer l'immunocompétence de manière répétée à l'échelle individuelle chez L. stagnalis. Le deuxième axe évalue cette approche multibiomarqueurs dans différents contextes écotoxicologiques. Plusieurs populations (élevages vs terrain), temps d'expositions (3 vs 29 – 44 jours), concentrations d'exposition (environnementales vs non réalistes) et contaminants ont été évalués : des médicaments (les anti-cancéreux Etoposide et cyclophosphamide, l'anti-rejet de greffes cyclosporine A et l'antiinflammatoire diclofenac), l'insecticide deltaméthrine, le métal cadmium et des effluents de station d'épuration. Des comparaisons entre des traits de vie et des traits immunitaires ont été réalisées. La réflexion est bâtie sur les questionnements relatifs à (i) la sensibilité de l'approche, (ii) le temps de réponse des marqueurs, (iii) leur précocité physiologique, (iv) la transposition d'immunotoxicité de xénobiotiques entre le phylum des chordata et L. stagnalis et (vi) l'utilisation pratique de L. stagnalis (élevages, collecte en milieu naturel, calibration, reproduction) / In natural environments, animals encounter multiple stresses (e.g., pollutants and pathogens/ parasites). In this context, the immune system plays a pivotal role. Chemical insults from pollutants can jeopardize the immune system of these animals, weaken their health and make them vulnerable to contracting infectious diseases. In ecotoxicology, assessment of immunocompetence markers can be used to diagnose the health of organisms and better understand the immunotoxic hazard of xenobiotics. Lymnaea stagnalis is a freshwater gastropod representative of several lentic ecosystems on the planet. OECD reprotoxicity tests are available using this species, but too few studies have focused on immunotoxic parameters. The first part of this thesis covers the description, comprehension and development of the methods used to assess the immunocompetence at an individual scale and repeatedly within an experiment in L. stagnalis. The second part assesses this multibiomarker approach in several ecotoxicological contexts. Several populations (laboratory-bred vs collected in the field), time exposures (3 vs 29–44 days), concentrations (environmental vs unrealistic) and contaminants were evaluated : pharmaceuticals (the anti-cancer drugs etoposide and cyclophosphamide, the anti-xenograft rejection drug cyclosporine A, the anti-inflammatory drug diclofenac), the insecticide deltamethrin, the metal cadmium and wastewater treatment plant effluents. The general reasoning is built on questions relative to (i) the sensitivity of the approach, (ii) the rapidity of the response, (iii) their physiological precocity of alteration (immune vs life-history traits), (iv) the transposition of xenobiotic immunotoxicity between L. stagnalis and the Chordata phylum and (vi) the pragmatic use of L. stagnalis (breeding, collection in the environment, calibration and reproduction)