Search results for " Competition"
showing 10 items of 819 documents
Effect of resource availability on evolution of virulence and competition in an environmentally transmitted pathogen
2018
Understanding ecological and epidemiological factors driving pathogen evolution in contemporary time scales is a major challenge in modern health management. Pathogens that replicate outside the hosts are subject to selection imposed by ambient environmental conditions. Increased nutrient levels could increase pathogen virulence by pre-adapting for efficient use of resources upon contact to a nutrient rich host or by favouring transmission of fast-growing virulent strains. We measured changes in virulence and competition in Flavobacterium columnare, a bacterial pathogen of freshwater fish, under high and low nutrient levels. To test competition between strains in genotype mixtures, we devel…
Coinfection outcome in an opportunistic pathogen depends on the inter-strain interactions
2017
Background In nature, organisms are commonly coinfected by two or more parasite strains, which has been shown to influence disease virulence. Yet, the effects of coinfections of environmental opportunistic pathogens on disease outcome are still poorly known, although as host-generalists they are highly likely to participate in coinfections. We asked whether coinfection with conspecific opportunistic strains leads to changes in virulence, and if these changes are associated with bacterial growth or interference competition. We infected zebra fish (Danio rerio) with three geographically and/or temporally distant environmental opportunist Flavobacterium columnare strains in single and in coinf…
FT-IR spectroscopy : A powerful tool for studying the inter- and intraspecific biodiversity of cultivable non-Saccharomyces yeasts isolated from grap…
2016
International audience; The efficiency of the FT-IR technique for studying the inter- and intra biodiversity of cultivable non-Saccharomyces yeasts (NS) present in different must samples was examined. In first, the capacity of the technique FF-IR to study the global diversity of a given sample was compared to the pyrosequencing method, used as a reference technique. Seven different genera (Aureobasidium, Candida, Cryptococcus, Hanseniaspora, Issatchenkia, Metschnikowia and Pichia) were identified by FT-IR and also by pyrosequencing. Thirty-eight other genera were identified by pyrosequencing, but together they represented less than 6% of the average total population of 6 musts. Among the sp…
Competition between strains of Borrelia afzelii inside the rodent host and the tick vector
2018
Multiple-strain pathogens often establish mixed infections inside the host that result in competition between strains. In vector-borne pathogens, the competitive ability of strains must be measured in both the vertebrate host and the arthropod vector to understand the outcome of competition. Such studies could reveal the existence of trade-offs in competitive ability between different host types. We used the tick-borne bacteriumBorrelia afzeliito test for competition between strains in the rodent host and the tick vector, and to test for a trade-off in competitive ability between these two host types. Mice were infected via tick bite with either one or two strains, and these mice were subse…
Comparison of sperm motility subpopulation structure among wild anadromous and farmed male Atlantic salmon (Salmo salar) parr using a CASA system.
2017
Atlantic salmon (Salmo salar) is an endangered freshwater species that needs help to recover its wild stocks. However, the priority in aquaculture is to obtain successful fertilisation and genetic variability to secure the revival of the species. The aims of the present work were to study sperm subpopulation structure and motility patterns in wild anadromous males and farmed male Atlantic salmon parr. Salmon sperm samples were collected from wild anadromous salmon (WS) and two generations of farmed parr males. Sperm samples were collected from sexually mature males and sperm motility was analysed at different times after activation (5 and 35 s). Differences among the three groups were anal…
Microbiome-assisted carrion preservation aids larval development in a burying beetle
2018
Significance Ephemeral diets such as carrion are high-quality resources that are susceptible to microbial spoilage. Carrion-feeding insects that breed on decaying carcasses must overcome challenges arising from competing microbes. Here we report that a carrion-feeding burying beetle preserves carcasses by regulating its microbial growth, resulting in changes in its biochemical properties including the reduction of toxic polyamines associated with putrefaction and nutrient loss. The beetle’s microbial symbionts form a biofilm-like matrix on carcasses, which is important for optimal larval development. The beetles and their microbiome thus coordinate a specialized adaptive strategy of carrion…
Place and space in home-making processes and the construction of identities in transnational migration
2016
AbstractIn this era of increasing migration and the trend of growing social, political, and cultural integration worldwide, it is questionable whether the concept of home in its traditional meaning still applies or has to be redefined. Many social scientists agree that the mobile individual of the twenty-first century has become uprooted and thus disoriented or that the idea of home has lost its significance. Since home is still closely tied to one’s identity, the current discussions on the construction of identity must also be incorporated in the analytical processes of home-making. The objective is to point out new ways of understanding the idea of home by taking into consideration and an…
The Portret of a Contemporary Child and Youngster in the Global Education Space
2018
The world of transformations changes radically the education process. Theoreticians and practitioners of pedagogy recognize that methods and strategies consolidated over centuries very often have become ineffective in modern education practice. Therefore, the researchers' interest in childhood studies nowadays is natural. They define children's and youngster`s culture as different, unknown and incomprehensible. The researchers initiate a number of questions that need to be answered in order to cooperate with children and youngsters in school and in the family. How can teachers work efficiently in the modern school? How should adults implement modern pedagogical goals and which pedagogical m…
Spatial Perspective on Everyday Transitions Within a Toddler Group Care Setting
2017
This chapter builds on spatial approaches to study everyday life, and in particular to consider Henri Lefebvre’s (1901–1991) theory on the social production of space. Lefebvre’s ideas on the social production of space are based on a dynamic “spatial triad” of conceived (representations of space), perceived (socio-spatial practices), and lived space (representational space). The aim of this chapter is to discuss, by building on Lefebvre’s approach, the spatial dynamics involved within the small-scale (horizontal) transitions for children in toddler group care. The discussion is based on a study where one Finnish day care group for 1- to 3-year-olds was investigated by applying a spatial, rel…
Teacher Guidance in Mathematical Problem-Solving Lessons: Insights from Two Professional Development Programs
2019
When implementing a problem-solving lesson, the teacher needs to provide students appropriate guidance during problem solving. This demanding task requires understanding students’ work in progress and giving them necessary help without constraining their thinking. In this article, we share insights from two professional development programs on how teachers guided students’ problem solving and how they reflected on these instances. One of the programs included Finnish pre-service teachers, while the other program included US in-service teachers. We analyzed video-recorded problem-solving lessons from 16 Finnish and 2 US teachers in grades 6–9. We found two themes about teacher guidance of st…