Нове дослідження з історії Волині

Рецензія на книгу: Пахолок З. О., Несторук І. М. Миколай Крушевський і Волинь : каталог-довідник. – Луцьк : Волинянин, 2012. – 156 с. : іл

Regression-based ranking of pathogen strains with respect to their contribution to natural epidemics

Peer reviewe

SNP Design from 454 Sequencing of Podosphaera plantaginis Transcriptome Reveals a Genetically Diverse Pathogen Metapopulation with High Levels of Mixed-Genotype Infection

Peer reviewe

Contrasted Patterns of Selection on MHC-Linked Microsatellites in Natural Populations of the Malagasy Plague Reservoir

Plague (Yersinia pestis infection) is a highly virulent rodent disease that persists in many natural ecosystems. The black rat (Rattus rattus) is the main host involved in the plague focus of the central highlands of Madagascar. Black rat populations from this area are highly resistant to plague, whereas those from areas in which the disease is absent (low altitude zones of Madagascar) are susceptible. Various lines of evidence suggest a role for the Major Histocompatibility Complex (MHC) in plague resistance. We therefore used the MHC region as a candidate for detecting signatures of plague-mediated selection in Malagasy black rats, by comparing population genetic structures for five MHC-linked microsatellites and neutral markers in two sampling designs. We first compared four pairs of populations, each pair including one population from the plague focus and one from the disease-free zone. Plague-mediated selection was expected to result in greater genetic differentiation between the two zones than expected under neutrality and this was observed for one MHC-class I-linked locus (D20Img2). For this marker as well as for four other MHC-linked loci, a geographic pattern of genetic structure was found at local scale within the plague focus. This pattern would be expected if plague selection pressures were spatially variable. Finally, another MHC-class I-linked locus (D20Rat21) showed evidences of balancing selection, but it seems more likely that this selection would be related to unknown pathogens more widely distributed in Madagascar than plague

Data from: Investigating the production of sexual resting structures in a plant pathogen reveals unexpected self-fertility and genotype-by-environment effects

The sexual stage of pathogens governs recombination patterns and often also provides means of surviving the off-season. Despite its importance for evolutionary potential and between-season epidemiology, sexual systems have not been carefully investigated for many important pathogens, and what generates variation in successful sexual reproduction of pathogens remains unexplored. We surveyed the sexually produced resting structures (chasmothecia) across 86 natural populations of fungal pathogen Podosphaera plantaginis (Ascomycota) naturally infecting Plantago lanceolata in the Åland archipelago, southwest of Finland. For this pathosystem, these resting structures are a key life-history stage, as more than half of the local pathogen populations go extinct every winter. We uncovered substantial variation in the level of chasmothecia produced among populations, ranging from complete absence to presence on all infected leaves. We found that chasmothecia developed within clonal isolates (single strain cultures). Additionally, these clonal isolates all contained both MAT1-1-1 and MAT1-2-1 genes that characterize mating-types in Ascomycetes. Hence, contrary to expectations, we conclude that this species is capable of haploid selfing. In controlled inoculations we discovered that pathogen genotypes varied in their tendency to produce chasmothecia. Production of chasmothecia was also affected by ambient temperature (E), and by the interaction between temperature and pathogen genotype (G × E). These G, E and G × E effects found both at a European scale, as well as within Åland, may partly explain the high variability observed among populations in chasmothecia levels. Consequently, they may be key drivers of the evolutionary potential and epidemiology of this highly dynamic pathosystem

Coévolution plantes-parasites en populations naturelles

International audienc

Evolutionary and epidemiological implications of multiple infection in plants

Recent methodological advances have uncovered tremendous microbial diversity cohabiting in the same host plant, and many of these microbes cause disease. In this review we highlight how the presence of other pathogen species, or other pathogen genotypes, within a plant can affect key components of host-pathogen interactions: (i) within-plant virulence and pathogen accumulation, through direct and host-mediated mechanisms; (ii) evolutionary trajectories of pathogen populations, through virulence evolution, generation of novel genetic combinations, and maintenance of genetic diversity; and (iii) disease dynamics, with multiple infection likely to render epidemics more devastating. The major future challenges are to couple a community ecology approach with a molecular investigation of the mechanisms operating under coinfection and to evaluate the evolution and effectiveness of resistance within a coinfection framework

Génétique et évolution du rat noir (Rattus rattus), réservoir de la peste à Madagascar

Les pressions de sélection exercées par les pathogènes peuvent induire des changements évolutifs extrêmement rapides chez leurs hôtes. C'est probablement le cas chez le rat noir (Rattus rattus) à Madagascar, qui présente des populations résistantes à la peste (infection à Yersinia pestis) dans la zone des hauts plateaux centraux, où la peste est endémique depuis un siècle environ, tandis que les populations de la zone de basse altitude, où la maladie est absente, sont sensibles. Le rat noir est actuellement le seul réservoir possible de la maladie à Madagascar. L'objectif de ce travail est d'étudier la résistance à la peste chez R. rattus, car ce trait a des conséquences importantes dans la transmission et le maintien de la maladie. Les patrons de génétique neutre sont en accord avec une colonisation unique de Madagascar par le rat noir, il y a 1000-2000 ans, en provenance de la Péninsule Arabique. Comme pour les populations humaines, des populations de rat noir se seraient d'abord installé dans les régions côtières, s'étendant ensuite sur les hauts plateaux centraux. Des travaux expérimentaux (infections contrôlées et croisements) ont permis d'étudier le phénotype de résistance et sa transmission à la descendance. La différence de niveau de résistance entre zone de peste et zone sans peste a ainsi été confirmée et étendue à d'autres localités. Enfin, des approches gènes candidats et génomiques ont conduit à l'identification de marqueurs génétiques potentiellement sous sélection divergente entre zone de peste et zone sans peste, et/ou associés à l'issue d'infections expérimentales par la peste.Selective pressure applied by pathogens can lead to extremely rapid evolutionary changes on their hosts. It could be the case for the black rat (Rattus rattus), which presents populations resistant to plague (Yersinia pestis infection), where plague have been endemic since about one century, whereas low altitude zone (where the disease is absent) populations are plague susceptible. The black rat is the only possible plague reservoir in Madagascar. This work aims to study plague resistance in R. rattus, as this trait has important consequences for the disease transmission and maintenance. Neutral genetic patterns agree with a unique colonization of Madagascar by the the black rat, 1000-2000 years ago, from Arabian Peninsula. As for humans, rat settlement would have begun by coastal regions, and latter expanded to the central highlands. Experimental work (controlled infestations and crosses) allowed the study of the resistance phenotype and its offspring transmission. Resistance level variation between plague focus and plague-free zone was confirmed and extended to other localities. Finally candidate gene and genomic approaches lead to detect genetic markers potentially undergoing divergent selection between plague focus and plague free zone than neutral loci and/or associated with experimental plague challenge issueMONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

dryad_exp

Excel file contening the results of the experiment described in the article as: "Experiment assessing the effect of pathogen genotype, environmental conditions and their interaction on chasmothecia production

Assembly_Dloop

D-loop final sequence assembly for the 36 haplotypes found in Malagasy R. rattu