Search results for "IOS"
showing 10 items of 8115 documents
Risk of predation makes foragers less choosy about their food.
2017
18 pages; International audience; Animals foraging in the wild have to balance speed of decision making and accuracy of assessment of a food item's quality. If resource quality is important for maximizing fitness, then the duration of decision making may be in conflict with other crucial and time consuming tasks, such as anti-predator behaviours or competition monitoring. Individuals facing the risk of predation and/or competition should adjust the duration of decision making and, as a consequence, their level of choosiness for resources. When exposed to predation, the forager could either maintain its level of choosiness for food items but accept a reduction in the amount of food items con…
Interactions between dark septate endophytes, ectomycorrhizal fungi and root pathogens in vitro
2019
ABSTRACT Dark septate endophytes (DSEs) are widely distributed worldwide and can promote plant growth. Therefore, they are considered potentially important plant allies, especially in stressful environments. Previous studies have reported that DSEs cohabit roots with other microorganisms such as ectomycorrhizal (ECM), endophytic and pathogenic fungi/oomycetes. However, interactions between different DSE species have not yet been reported, and studies on the interactions between DSEs and other fungi are scarce. Using a simple and reproducible pairwise growth assay in vitro, we studied the synergistic/antagonistic interactions between eight DSEs, two ECM fungi and three root pathogens. Most o…
Impacts of arbuscular mycorrhizal fungi on nutrient uptake, N2 fixation, N transfer, and growth in a wheat/faba bean intercropping system
2019
Arbuscular mycorrhizal fungi (AMF) can play a key role in natural and agricultural ecosystems affecting plant nutrition, soil biological activity and modifying the availability of nutrients by plants. This research aimed at expanding the knowledge of the role played by AMF in the uptake of macro- and micronutrients and N transfer (using a 15 N stem-labelling method) in a faba bean/wheat intercropping system. It also investigates the role of AMF in biological N fixation (using the natural isotopic abundance method) in faba bean grown in pure stand and in mixture. Finally, it examines the role of AMF in driving competition and facilitation between faba bean and wheat. Durum wheat and faba bea…
Diversity of arbuscular mycorrhizal fungi colonising roots of the grass species Agrostis capillaris and Lolium perenne in a field experiment
2004
Analysis of arbuscular mycorrhizal (AM) fungal diversity through morphological characters of spores and intraradicular hyphae has suggested previously that preferential associations occur between plants and AM fungi. A field experiment was established to investigate whether AM fungal diversity is affected by different host plants in upland grasslands. Indigenous vegetation from plots in an unimproved pasture was replaced with monocultures of either Agrostis capillaris or Lolium perenne. Modification of the diversity of AM fungi in these plots was evaluated by analysis of partial sequences in the large subunit (LSU) ribosomal RNA (rDNA) genes. General primers for AM fungi were designed for t…
Glomales species associated with surface and deep rhizosphere of Faidherbia albida in Senegal
2000
Five arbuscular mycorrhizal (AM) fungal species were isolated and propagated from surface and deep rhizospheres of Faidherbia albida trees growing in two ecoclimatic zones of West Africa: the semi-arid Sahelian and the more humid Sudano-Guinean areas. Of these species, Glomus aggregatum, Glomus caledonium, and Glomus mosseae were trapped by F. albida roots when cultivated with either surface or deep soils. Glomus fasciculatum was found exclusively at the semi-arid Sahelian sites of Louga and Diokoul and Gigaspora margarita was isolated only from 16.5-m and 34-m-deep samples. Comparable glomalean fungal species richness was identified in deep (1.5–34 m) and surface (0.15 m) samples. The isol…
Nitric oxide: comparative synthesis and signaling in animal and plant cells.
2001
Since its identification as an endothelium-derived relaxing factor in the 1980s, nitric oxide has become the source of intensive and exciting research in animals. Nitric oxide is now considered to be a widespread signaling molecule involved in the regulation of an impressive spectrum of mammalian cellular functions. Its diverse effects have been attributed to an ability to chemically react with dioxygen and its redox forms and with specific iron- and thiol-containing proteins. Moreover, the effects of nitric oxide are dependent on the dynamic regulation of its biosynthetic enzyme nitric oxide synthase. Recently, the role of nitric oxide in plants has received much attention. Plants not only…
Mycorrhizae differentially influence the transfer of nitrogen among associated plants and their competitive relationships
2021
Abstract The formation of a common mycorrhizal network among roots of different plant species growing close to each other can influence plant community dynamics, regulating plant relationships through the differential transfer of nutrients from one plant to another. However, knowledge of the mechanisms that regulate this process is poor. Here we quantify the contribution of arbuscular mycorrhizae to the transfer of N among heterospecific plants growing adjacent to each other and examine whether the differential transfer of N within the plant community via mycorrhizae can alter competitive relationships among plant species. Plants of four species (wheat, pea, flax, and chicory) were grown in…
Impact of host nutritional status on infection dynamics and parasite virulence in a bird-malaria system.
2014
10 pages; International audience; Host resources can drive the optimal parasite exploitation strategy by offering a good or a poor environment to pathogens. Hosts living in resource-rich habitats might offer a favourable environment to developing parasites because they provide a wealth of resources. However, hosts living in resource-rich habitats might afford a higher investment into costly immune defences providing an effective barrier against infection. Understanding how parasites can adapt to hosts living in habitats of different quality is a major challenge in the light of the current human-driven environmental changes. We studied the role of nutritional resources as a source of phenoty…
Antagonistic effects of a Mhc class I allele on malaria-infected house sparrows.
2008
8 pages; International audience; Genes of the Major Histocompatibility Complex (Mhc) play a fundamental role during the immune response because MHC molecules expressed on cell surface allow the recognition and presentation of antigenic peptides to T-lymphocytes. Although Mhc alleles have been found to correlate with pathogen resistance in several host-parasite systems, several studies have also reported associations between Mhc alleles and an accrued infection risk or an accelerated disease progression. The existence of these susceptibility alleles is puzzling, as the cost generated by the infection should rapidly eliminate them from the population. Here, we show that susceptibility alleles…
Sensitive measure of prevalence and parasitaemia of haemosporidia from European blackbird (Turdus merula) populations: value of PCR-RFLP and quantita…
2006
8 pages; International audience; Haemosporidian parasites are common in birds in which they act as an important selective pressure. While most studies so far have focused on the effect of their prevalence on host life-history traits, no study has measured the effect of parasitaemia. We developed molecular methods to detect, identify and quantify haemosporidia in 2 natural populations of the Blackbird Turdus merula. Three different parasite genotypes were found - 1 Haemoproteus and 2 Plasmodium. A PCR-RFLP screening revealed that only approximately 3% of blackbirds were free of parasites, compared to the 34% of uninfected birds estimated by blood smear screening. A quantitative PCR (q-PCR) a…