Variation in resistance to multiple pathogen species:anther-smuts of Silene uniflora

The occurrence of multiple pathogen species on a shared host species is unexpected when they exploit the same micro-niche within the host individual. One explanation for such observations is the presence of pathogen-specific resistances segregating within the host population into sites that are differentially occupied by the competing pathogens. This study used experimental inoculations to test whether specific resistances may contribute to the maintenance of two species of anther-smut fungi, Microbotryum silenes-inflatae and Microbotryum lagerheimii, in natural populations of Silene uniflora in England and Wales. Overall, resistance to the two pathogens was strongly positively correlated among host populations and to a lesser degree among host families within populations. A few instances of specific resistance were also observed and confirmed by replicated inoculations. The results suggest that selection for resistance to one pathogen may protect the host from the emergence via host shifts of related pathogen species, and conversely that co-occurrence of two species of pathogens may be dependent on the presence of host genotypes susceptible to both

The Effect of Chemical Information on the Spatial Distribution of Fruit Flies: II Parameterization, Calibration, and Sensitivity

In a companion paper (Lof et al., in Bull. Math. Biol., 2008), we describe a spatio-temporal model for insect behavior. This model includes chemical information for finding resources and conspecifics. As a model species, we used Drosophila melanogaster, because its behavior is documented comparatively well

Lack of phenotypic and evolutionary cross-resistance against parasitoids and pathogens in Drosophila melanogaster

BackgroundWhen organisms are attacked by multiple natural enemies, the evolution of a resistance mechanism to one natural enemy will be influenced by the degree of cross-resistance to another natural enemy. Cross-resistance can be positive, when a resistance mechanism against one natural enemy also offers resistance to another; or negative, in the form of a trade-off, when an increase in resistance against one natural enemy results in a decrease in resistance against another. Using Drosophila melanogaster, an important model system for the evolution of invertebrate immunity, we test for the existence of cross-resistance against parasites and pathogens, at both a phenotypic and evolutionary level.MethodsWe used a field strain of D. melanogaster to test whether surviving parasitism by the parasitoid Asobara tabida has an effect on the resistance against Beauveria bassiana, an entomopathogenic fungus; and whether infection with the microsporidian Tubulinosema kingi has an effect on the resistance against A. tabida. We used lines selected for increased resistance to A. tabida to test whether increased parasitoid resistance has an effect on resistance against B. bassiana and T. kingi. We used lines selected for increased tolerance against B. bassiana to test whether increased fungal resistance has an effect on resistance against A. tabida.Results/ConclusionsWe found no positive cross-resistance or trade-offs in the resistance to parasites and pathogens. This is an important finding, given the use of D. melanogaster as a model system for the evolution of invertebrate immunity. The lack of any cross-resistance to parasites and pathogens, at both the phenotypic and the evolutionary level, suggests that evolution of resistance against one class of natural enemies is largely independent of evolution of resistance against the other

The Effect of Chemical Information on the Spatial Distribution of Fruit Flies: I Model Results

Animal aggregation is a general phenomenon in ecological systems. Aggregations are generally considered as an evolutionary advantageous state in which members derive the benefits of protection and mate choice, balanced by the costs of limiting resources and competition. In insects, chemical information conveyance plays an important role in finding conspecifics and forming aggregations. In this study, we describe a spatio-temporal simulation model designed to explore and quantify the effects of these infochemicals, i.e., food odors and an aggregation pheromone, on the spatial distribution of a fruit fly (Drosophila melanogaster) population, where the lower and upper limit of local population size are controlled by an Allee effect and competition. We found that during the spatial expansion and strong growth of the population, the use of infochemicals had a positive effect on population size. The positive effects of reduced mortality at low population numbers outweighed the negative effects of increased mortality due to competition. At low resource densities, attraction toward infochemicals also had a positive effect on population size during recolonization of an area after a local population crash, by decreasing the mortality due to the Allee effect. However, when the whole area was colonized and the population was large, the negative effects of competition on population size were larger than the positive effects of the reduction in mortality due to the Allee effect. The use of infochemicals thus has mainly positive effects on population size and population persistence when the population is small and during the colonization of an area

Parenteral provision of micronutrients to adult patients: an expert consensus paper

Background:Micronutrients, an umbrella term used to collectively describe vitamins and trace elements, are essential componentsof nutrition. Those requiring alternative forms of nutrition support are dependent on the prescribed nutrition regimen for theirmicronutrient provision. The purpose of this paper is to assist clinicians to bridge the gap between the available guidelines’recommendations and their practical application in the provision of micronutrients via the parenteral route to adult patients.Methods:Based on the available evidenced-based literature and existing guidelines, a panel of multidisciplinary healthcareprofessionals with significant experience in the provision of parenteral nutrition (PN) and intravenous micronutrients developedthis international consensus paper.Results:The paper addresses 14 clinically relevant questions regarding the importance and use ofmicronutrients in various clinical conditions. Practical orientation on how micronutrients should be prescribed, administered, andmonitored is provided.Conclusion:Micronutrients are a critical component to nutrition provision and PN provided without thempose a considerable risk to nutrition status. Obstacles to their daily provision—including voluntary omission, partial provision, andsupply issues—must be overcome to allow safe and responsible nutrition practice

The transition of CyberThèses to Open Source

CyberThèses is a platform for the archiving and dissemination of electronic theses and dissertations built on the use of structured document (initially SGML). An important step has been crossed with the evolution of the program towards XML and the evolution of the whole platform to open access. We now propose to the community a set of tools covering the production of XML document from traditional word processing formats, their indexation which the enrichment associated to structured document and their dissemination. The whole platform is available freely (GPL license) on a collaborative development web site (http://sourcesup.cru.fr/cybertheses). The benefits we aim from this transition are of different nature: - the political one: dissemination of the results of research shall be free and we do agree on that point with some larger initiatives' recommendations OAI, BOAI, NDLTD, etc., - the financial one: their won't be anymore economic barrier to the implementation of many ETD providers, - the practical one: we hope to enlarge the users and/or developers contributions to the CyberThèses program