Search results for "genetics [RNA Splicing]"
showing 10 items of 2994 documents
Cucumispora dikerogammari n. gen. (Fungi: Microsporidia) infecting the invasive amphipod Dikerogammarus villosus: a potential emerging disease in Eur…
2010
SUMMARYDikerogammarus villosusis an invasive amphipod that recently colonized the main rivers of Central and Western Europe. Two frequent microsporidian parasites were previously detected in this species, but their taxonomic status was unclear. Here we present ultrastructural and molecular data indicating that these two parasites are in fact a single microsporidian species. This parasite shares numerous characteristics ofNosemaspp. It forms elongate spores (cucumiform), developing in direct contact with host cell cytoplasm; all developmental stages are diplokaryotic and the life cycle is monomorphic with disporoblastic sporogony. Initially this parasite was described asNosema dikerogammariO…
Parasite and host assemblages: embracing the reality will improve our knowledge of parasite transmission and virulence.
2010
10 pages; International audience; Interactions involving several parasite species (multi-parasitized hosts) or several host species (multi-host parasites) are the rule in nature. Only a few studies have investigated these realistic, but complex, situations from an evolutionary perspective. Consequently, their impact on the evolution of parasite virulence and transmission remains poorly understood. The mechanisms by which multiple infections may influence virulence and transmission include the dynamics of intrahost competition, mediation by the host immune system and an increase in parasite genetic recombination. Theoretical investigations have yet to be conducted to determine which of these…
Première contribution à l'étude des mycorhizes des îles Kerguelen
1999
Abstract Until recently mycorrhizae had not been studied in the Antarctic region. Some studies have demonstrated that mycorrhizae occur in some southern circumpolar islands. This paper gives the first results on the mycorrhizae in the Kerguelen islands (Sub-antarctic). Twenty-one plant root systems, fixed in the field, were examined microscopically in the laboratory to determine their mycorrhizal status. No ectomycorrhiza, arbutoid or ericoid were noted. Six plant species showed vesicular arbuscular mycorrhizae: Ranunculus biternatus, Galium antarcticum, Festuca erecta, Poa kerguelensis, Agrostis magellanica and Poa annua. However, the mycorrhizal status varied according to the site studied.
Identification d'arômes par CPG-SM
1997
National audience
Free Radicals Mediate Systemic Acquired Resistance
2014
Summary: Systemic acquired resistance (SAR) is a form of resistance that protects plants against a broad spectrum of secondary infections. However, exploiting SAR for the protection of agriculturally important plants warrants a thorough investigation of the mutual interrelationships among the various signals that mediate SAR. Here, we show that nitric oxide (NO) and reactive oxygen species (ROS) serve as inducers of SAR in a concentration-dependent manner. Thus, genetic mutations that either inhibit NO/ROS production or increase NO accumulation (e.g., a mutation in S-nitrosoglutathione reductase [GSNOR]) abrogate SAR. Different ROS function additively to generate the fatty-acid-derived azel…
Use of chlorophyll fluorescence induction kinetics to study translocation and detoxication of DCMU-type herbicides in plant leaves
1984
Transient levels of the fluorescence induction rise were used to quantify partial photosynthesis inhibition by DCMU -type herbicides in whole leaves. Assays in different crop or weed species showed a good accuracy in measurements (generally, variation was lower than 5%). This technique was applied to the problem of varietal selectivity of wheat towards chlortoluron.
Negative associations between parasite avoidance, resistance and tolerance predict host health in salmonid fish populations
2020
Genetic variation in defence against parasite infections is fundamental for host–parasite evolution. The overall level of defence of a host individual or population includes mechanisms that reduce parasite exposure (avoidance), establishment (resistance) or pathogenicity (tolerance). However, how these traits operate and evolve in concert is not well understood. Here, we investigated genetic variation in and associations between avoidance, resistance and tolerance in a natural host–parasite system. Replicated populations of Atlantic salmon ( Salmo salar ) and sea trout (an anadromous form of brown trout, Salmo trutta ) were raised under common garden conditions and infected with the eye fl…
Conservation status of freshwater mussels in Europe: state of the art and future challenges
2016
Freshwater mussels of the Order Unionida provide important ecosystem functions and services, yet many of their populations are in decline. We comprehensively review the status of the 16 currently recognized species in Europe, collating for the first time their life-history traits, distribution, conservation status, habitat preferences, and main threats in order to suggest future management actions. In northern, central, and eastern Europe, a relatively homogeneous species composition is found in most basins. In southern Europe, despite the lower species richness, spatially restricted species make these basins a high conservation priority. Information on freshwater mussels in Europe is uneve…
Infection by Endosymbiotic “Male-Killing” Bacteria in Coleoptera
2018
Wolbachia, Rickettsia, Spiroplasma and Cardinium are endosymbiotic and intracellular bacteria known to cause numerous disorders in host reproduction, reflected in their common name “male-killers”. In this study, 297 beetle species from various taxonomic groups were screened with the use of molecular markers for the presence of infection by any of these endosymbionts. Wolbachia was found to be the most common “male-killer” among beetle hosts as it infected approx. 27% of species. Rickettsia, Spiroplasma and Cardinium were much less prevalent as they infected: 8%, 3% and 2%, respectively, of the studied beetle species. This is the first report of Cardinium presence in beetle hosts. Incidences…
Is the impact of environmental noise visible in the dynamics of age-structured populations?
2001
Climate change has ignited lively research into its impact on various population–level processes. The research agenda in ecology says that some of the fluctuations in population size are accountable for by the external noise (e.g. weather) modulating the dynamics of populations. We obeyed the agenda by assuming population growth after a resource–limited Leslie matrix model in an age–structured population. The renewal process was disturbed by superimposing noise on the development of numbers in one or several age groups. We constructed models for iteroparous and semelparous breeders so that, for both categories, the population growth rate was matching. We analysed how the modulated populatio…