Search results for "Competition"
showing 10 items of 1409 documents
Inter- and intraspecific variability in invertebrate acute toxicity response to Arsenic and Fluoride exposure
2018
The adverse effects of arsenic and fluoride exposure on six groups of freshwater invertebrates were investigated. Acute toxicity tests (48-h) with arsenic trioxide (As2NO3) resulted in the following pattern of sensitivity: Daphnia magna 24-h-old = Brachionus patulus 72-h-old = Daphnia. cf. prolata, 21-d-old = D. magna 5-d-old > Heterocypris incongruens juvenile instars > Culex sp. Heterocypris juv. incongruens instars were the second group more tolerant to arsenic and the second group that bioconcentrates arsenic the least. In contrast, invertebrates exposed to sodium fluoride (NaF), showed a different pattern of sensitivity: H. incongruens instars > B. patulus = D. magna 24-h-old > D. cf. …
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…
Effect of temperature on the prevalence of Saccharomyces non-cerevisiae species against a S. cerevisiae wine strain in wine fermentation: competition…
2017
Saccharomyces cerevisiae is the main microorganism responsible for the fermentation of wine. Nevertheless, in the last years wineries are facing new challenges due to current market demands and climate change effects on the wine quality. New yeast starters formed by non-conventional Saccharomyces species (such as S. uvarum or S. kudriavzevii) or their hybrids (S. cerevisiae x S. uvarum and S. cerevisiae x S. kudriavzevii) can contribute to solve some of these challenges. They exhibit good fermentative capabilities at low temperatures, producing wines with lower alcohol and higher glycerol amounts. However, S. cerevisiae can competitively displace other yeast species from wine fermentations,…
Competing species system as a qualitative model of radiation therapy
2016
To examine complex features of tumor dynamics we analyze a competing-species lattice model that takes into account the competition for nutrients or space as well as interaction with therapeutic factors such as drugs or radiation. Our model might be interpreted as a certain prey–predator system having three trophic layers: (i) the basal species that might be interpreted as nutrients; (ii) normal and tumor cells that consume nutrients, and (iii) therapeutic factors that might kill either nutrient, normal or tumor cells. Using a wide spectrum of parameters we examined survival of our species and tried to identify the corresponding dynamical regimes. It was found that the radiotherapy influence…
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…
Burying beetles regulate the microbiome of carcasses and use it to transmit a core microbiota to their offspring
2017
Necrophagous beetles utilize carrion, a highly nutritious resource that is susceptible to intense microbial competition, by treating it with antimicrobial anal and oral secretions. However, how this regulates the carcass microbiota remains unclear. Here, we show that carcasses prepared by the burying beetle Nicrophorus vespilloides undergo significant changes in their microbial communities subsequent to their burial and ‘preparation’. Prepared carcasses hosted a microbial community that was more similar to that of beetles’ anal and oral secretions than to the native carcass community or the surrounding soil, indicating that the beetles regulated the carcass microbiota. A core microbial comm…