The impact of infection on host competition and its relationship to parasite persistence in a Daphnia microparasite system

Evolutionary studies often estimate fitness components with the aim to make predictions about the outcome of selection. Depending on the system and the question, different fitness components are used, but their usefulness for predicting the outcome of selection is rarely tested. Here we estimate host fitness components in different ways with the aim to test how well they agree with each other and how well they predict host fitness at the population level in the presence of the parasite. We use a Daphnia magna-microparasite system to study the competitive ability of host clones in the absence and presence of the parasite, the infection intensity of the parasite in individuals of twelve host clones (an estimate of both host resistance and parasite reproductive success), and parasite persistence in small host populations (an estimate of R 0 of the parasite). Analysis of host competitive ability and parasite persistence reveals strong host genotype effects, while none are found for infection intensity. Host competitive ability further shows a genotype-specific change upon infection, which is correlated with the relative persistence of the parasite in the competing hosts. Hosts in which the parasite persists better suffer a competitive disadvantage in the parasite's presence. This suggests that in this system, parasite-mediated selection can be predicted by parasite persistence, but not by parasite infection intensit

Efficacy of Armicarb (potassium bicarbonate) against scab and sooty blotch on apples.

A novel formulation of potassium bicarbon-ate (Armicarb) was evaluated in 2004 and 2005 as agent against apple scab and sooty blotch in several field trials. Armicarb controlled scab equally well as the reference treatments sulphur and copper. Armi-carb showed also excellent activity against sooty blotch. However, potential side-effects such as lenti-cell spot development need further investigation. At present, potassium bicarbonate is considered by the Swiss registration authorities as non-toxic to humans and in consequence, no residue levels have been specified. Armicarb has very interesting properties as a plant protection agent and its composition and risk profile are expected to fulfil the IFOAM standards for acceptance of novel plant protection agents to a very large extent

Production de spiruline à la ferme : produire de la spiruline à la ferme grâce au digestat et à la chaleur excédentaire d’une installation de biogaz

The development of projects coupling an agricultural anaerobic digestion installation with the production of spirulina is an attractive concept, since the waste streams from the methanisation and from biogas valorization can be used to produce a high value product. This principle allows a better energetic valorization of surplus heat and of exhaust gases coming from the cogeneration unit. The limits of this configuration have been evaluated for Switzerland to study if the implementation of such coupling increases the competitiveness of agricultural anaerobic digestion. The thermal autonomy of the plant has been established as the main criterion to design the spirulina production units. For different working conditions (light radiation, nutrients source, size of methanisation units), the potential production of spirulina has been evaluated. The process energy yield, the environmental impact and the process economy show that 50% of surplus heat can be valorized, being 85-90% of heat contained in the exhaust gases; that the decrease in carbon dioxide emissions is not relevant and that, for the conditions tested, the operating costs are currently too high to allow the economic feasibility of the project

Einfluss von Armicarb (Kalium Bikarbonat) auf den Schorf und Regenfleckenkrankheit des Apfels

In den Jahren 2004 und 2005 wurde eine neue Formulierung von Kaliumbicarbonat (Armicarb) gegen Schorf und gegen Regenflecken geprüft. Armicarb zeigte ähnlich gute Ergebnisse wie die Referenzverfahren Netzschwefel und Kupfer. Auch gegen die Regenfleckenkrankheiten zeigte Armicarb ausgezeichnete Wirkung. Mögliche Nebenwirkungen wie die Förderung von ‚Lentizellen-Spot’ müssen noch näher überprüft werden. Armicarb wird vom Bundesamt für Gesundheit (BAG) als nicht-toxisch eingestuft und es wurden deshalb auch keine Grenzwerte festgelegt. Armicarb hat sehr interessante Eigenschaften als Pflanzenschutzprodukt und wir erwarten, dass die bio-spezifischen Anforderungen bezüglich Zusammensetzung und Risiko-Profil weitgehend erfüllt werden

Influence du Armicarb (bicarbonate de potassium) sur la tavelure et la maladies des taches de suie de la pomme

En 2004 et 2005, une nouvelle formulation du bicarbonate de potassium (Armicarb) a été testée contre la tavelure et contre les taches de suie. Armicarb a donné d'aussi bons résultats que les traitements de référence au soufre mouillable et au cuivre. Armicarb a également démontré un bon effet contre la maladie des taches de suie. D'éventuels effets secondaires tels que l'augmentation de la pourriture des lenticelles doivent encore être examinés de manière plus approfondie. L'Office fédéral de la santé publique (OFSP) a classifié Armicarb comme produit non toxique, c'est pour cela qu'aucune valeur limite n'a été définie. Armicarb a des propriétés très intéressantes comme produit phytosanitaire et nous nous attendons à ce que les exigences spécifiques à l'agriculture biologique concernant la composition et le profil des risques soient en grande partie remplies

Cytological and molecular description of Hamiltosporidium tvaerminnensis gen. et sp. nov., a microsporidian parasite of Daphnia magna, and establishment of Hamiltosporidium magnivora comb. nov

We describe the new microsporidium Hamiltosporidium tvaerminnensis gen. et sp. nov. with an emphasis on its ultrastructural characteristics and phylogenetic position as inferred from the sequence data of SSU rDNA, alpha- and beta-tubulin. This parasite was previously identified as Octosporea bayeri Jírovec, 1936 and has become a model system to study the ecology, epidemiology, evolution and genomics of microsporidia - host interactions. Here, we present evidence that shows its differences from O. bayeri. Hamiltosporidium tvaerminnensis exclusively infects the adipose tissue, the ovaries and the hypodermis of Daphnia magna and is found only in host populations located in coastal rock pool populations in Finland and Sweden. Merogonial stages of H. tvaerminnensis have isolated nuclei; merozoites are formed by binary fission or by the cleaving of a plasmodium with a small number of nuclei. A sporogonial plasmodium with isolated nuclei yields 8 sporoblasts. Elongated spores are generated by the most finger-like plasmodia. The mature spores are polymorphic in shape and size. Most spores are pyriform (4·9-5·6×2·2-2·3 μm) and have their polar filament arranged in 12-13 coils. A second, elongated spore type (6·8-12·0×1·6-2·1 μm) is rod-shaped with blunt ends and measures 6·8-12·0×1·6-2·1 μm. The envelope of the sporophorous vesicle is thin and fragile, formed at the beginning of the sporogony. Cytological and molecular comparisons with Flabelliforma magnivora, a parasite infecting the same tissues in the same host species, reveal that these two species are very closely related, yet distinct. Moreover, both cytological and molecular data indicate that these species are quite distant from F. montana, the type species of the genus Flabelliforma. We therefore propose that F. magnivora also be placed in Hamiltosporidium gen. no

Cytological and molecular description of Hamiltosporidium tvaerminnensis gen. et sp. nov., a microsporidian parasite of Daphnia magna, and establishment of Hamiltosporidium magnivora comb. nov.

We describe the new microsporidium Hamiltosporidium tvaerminnensis gen. et sp. nov. with an emphasis on its ultrastructural characteristics and phylogenetic position as inferred from the sequence data of SSU rDNA, alpha-and beta-tubulin. This parasite was previously identified as Octosporea bayeri Jirovec, 1936 and has become a model system to study the ecology, epidemiology, evolution and genomics of microsporidia - host interactions. Here, we present evidence that shows its differences from O. bayeri. Hamiltosporidium tvaerminnensis exclusively infects the adipose tissue, the ovaries and the hypodermis of Daphnia magna and is found only in host populations located in coastal rock pool populations in Finland and Sweden. Merogonial stages of H. tvaerminnensis have isolated nuclei; merozoites are formed by binary fission or by the cleaving of a plasmodium with a small number of nuclei. A sporogonial plasmodium with isolated nuclei yields 8 sporoblasts. Elongated spores are generated by the most finger-like plasmodia. The mature spores are polymorphic in shape and size. Most spores are pyriform (4.9-5.6x2.2-2.3 mu m) and have their polar filament arranged in 12-13 coils. A second, elongated spore type (6.8-12.0x1.6-2.1 mu m) is rod-shaped with blunt ends and measures 6.8-12.0x1.6-2.1 mu m. The envelope of the sporophorous vesicle is thin and fragile, formed at the beginning of the sporogony. Cytological and molecular comparisons with Flabelliforma magnivora, a parasite infecting the same tissues in the same host species, reveal that these two species are very closely related, yet distinct. Moreover, both cytological and molecular data indicate that these species are quite distant from F. montana, the type species of the genus Flabelliforma. We therefore propose that F. magnivora also be placed in Hamiltosporidium gen. nov

Improving the evaluation and treatment of neuroendocrine disorders

The aim of this thesis was to improve the diagnosis and treatment of neuroendocrine disorders. In addition, it shows further possibilities to achieve this goal in the long term

Hyponatremia Intervention Trial (HIT):Study Protocol of a Randomized, Controlled, Parallel-Group Trial With Blinded Outcome Assessment

Background: Hyponatremia is the most common electrolyte disorder with a prevalence of up to 30% in hospitalized patients. In contrast to acute hyponatremia where the need for immediate treatment is well-recognized, chronic hyponatremia is often considered not clinically relevant. This is illustrated by reports showing that appropriate laboratory tests are ordered in &lt;50% of patients and that up to 75% are still hyponatremic at discharge. At the same time, emerging evidence suggests an association between hyponatremia and adverse events including increased risk of mortality and rehospitalization. Methods: This is a randomized (1:1 ratio) controlled, superiority, parallel-group international multi-center trial with blinded outcome assessment. In total 2,278 participants will be enrolled. Participants will be randomly assigned to undergo either targeted correction of plasma sodium levels or standard of care during hospitalization. The primary outcome is the combined risk of death or re-hospitalization within 30 days. Discussion: All data on hyponatremia and mortality are derived from observational studies and often lack methodologic robustness. Consequently, the direct impact of hyponatremia on mortality and rehospitalization risk is still debated, resulting in a clinical equipoise whether in-hospital chronic hyponatremia should be treated or not. Therefore, a randomized controlled trial is required to study whether targeted plasma sodium correction reduces the risk of mortality and rehospitalization associated with hyponatremia. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT03557957.</p

Tripartite species interaction : eukarotic hosts suffer more from phage susceptible than from phage resistant bacteria

Background: Evolutionary shifts in bacterial virulence are often associated with a third biological player, for instance temperate phages, that can act as hyperparasites. By integrating as prophages into the bacterial genome they can contribute accessory genes, which can enhance the fitness of their prokaryotic carrier (lysogenic conversion). Hyperparasitic influence in tripartite biotic interactions has so far been largely neglected in empirical host-parasite studies due to their inherent complexity. Here we experimentally address whether bacterial resistance to phages and bacterial harm to eukaryotic hosts is linked using a natural tri-partite system with bacteria of the genus Vibrio, temperate vibriophages and the pipefish Syngnathus typhle. We induced prophages from all bacterial isolates and constructed a three-fold replicated, fully reciprocal 75 × 75 phage-bacteria infection matrix. Results: According to their resistance to phages, bacteria could be grouped into three distinct categories: highly susceptible (HS-bacteria), intermediate susceptible (IS-bacteria), and resistant (R-bacteria). We experimentally challenged pipefish with three selected bacterial isolates from each of the three categories and determined the amount of viable Vibrio counts from infected pipefish and the expression of pipefish immune genes. While the amount of viable Vibrio counts did not differ between bacterial groups, we observed a significant difference in relative gene expression between pipefish infected with phage susceptible and phage resistant bacteria. Conclusion: These findings suggest that bacteria with a phage-susceptible phenotype are more harmful against a eukaryotic host, and support the importance of hyperparasitism and the need for an integrative view across more than two levels when studying host-parasite evolution