Search results for "DISEASES"
showing 10 items of 20537 documents
Colonization of flax roots and early physiological responses of flax cells inoculated with pathogenic and nonpathogenic strains of Fusarium oxysporum
2003
ABSTRACT Fusarium oxysporum includes nonpathogenic strains and pathogenic strains that can induce necrosis or tracheomycosis in plants. The objective of this study was to compare the abilities of a pathogenic strain (Foln3) and a nonpathogenic strain (Fo47) to colonize flax roots and to induce early physiological responses in flax cell culture suspensions. Both strains colonized the outer cortex of the root; however, plant defense reactions, i.e., the presence of wall appositions, osmiophilic material, and collapsed cells, were less frequent and less intense in a root colonized by Foln3 than by Fo47. Early physiological responses were measured in flax cell suspensions confronted with germin…
Host manipulation in the face of environmental changes: Ecological consequences
2015
Several parasite species, particularly those having complex life-cycles, are known to induce phenotypic alterations in their hosts. Most often, such alterations appear to increase the fitness of the parasites at the expense of that of their hosts, a phenomenon known as “host manipulation”. Host manipulation can have important consequences, ranging from host population dynamics to ecosystem engineering. So far, the importance of environmental changes for host manipulation has received little attention. However, because manipulative parasites are embedded in complex systems, with many interacting components, changes in the environment are likely to affect those systems in various ways. Here, …
Relationships between helminth communities and diet in Canarian lizards: the evidence from Gallotia atlantica (Squamata: Lacertidae)
2014
Diet and helminth fauna were analysed in the lizard Gallotia atlantica (Squamata: Lacertidae), the smallest species of this genus endemic to Lanzarote and Fuerteventura (Canary Islands), in an attempt to confirm previous claims of relationships between these ecological traits in this genus. A total of 70 lizards belonging to the subspecies atlantica (central southern Lanzarote), laurae (northern Lanzarote) and mahoratae (Fuerteventura) were examined. Compared with other Gallotia, the helminth fauna was impoverished, particularly in Fuerteventura, where the absence of larval cestodes suggests low predation pressure. Diet was omnivorous, the plant fraction (73.03–84.26%) included seeds and fr…
Mutations in voltage-gated sodium channels from pyrethroid resistant salmon lice (Lepeophtheirus salmonis)
2018
BACKGROUND Parasitic salmon lice (Lepeophtheirus salmonis) cause high economic losses in Atlantic salmon farming. Pyrethroids, which block arthropod voltage-gated sodium channels (Nav 1), are used for salmon delousing. However, pyrethroid resistance is common in L. salmonis. The present study characterized Nav 1 homologues in L. salmonis in order to identify channel mutations associated to resistance, called kdr (knockdown) mutations. RESULTS Genome scans identified three L. salmonis Nav 1 homologues, LsNav 1.1, LsNav 1.2 and LsNav 1.3. Arthropod kdr mutations map to specific Nav 1 regions within domains DI-III, namely segments S5 and S6 and the linker helix connecting S4 and S5. The above …
Disentangling phylogeography, polyploid evolution and taxonomy of a woodland herb (Veronica chamaedrys group, Plantaginaceae s.l.) in southeastern Eu…
2010
Southeastern Europe is a centre of European biodiversity, but very little is known about factors causing the observed richness. Here, we contribute to fill this gap by reconstructing the spatio-temporal diversification of the cytologically variable and taxonomically intricate complex of Veronica chamaedrys (Plantaginaceae s.l.), growing in open forests, forest edges and grasslands, with flow cytometry, molecular markers (AFLPs, plastid DNA sequences) and morphometry. Our results show that both diploid and tetraploid cytotypes are widespread, but diploids predominate on the southern Balkan Peninsula. Plastid sequences suggest a first split into three main lineages in the mid-Pleistocene and …
Driving factors of dinoflagellate cyst distribution in surface sediments of aMediterranean lagoon with limited access to the sea
2016
International audience; Seasonal distribution of dinoflagellate cysts were studied at five surface sediment study stations in Ghar El MelhLagoon (GML) (Tunisia) in relation to physicochemical parameters and phytoplankton abundance in the watercolumn. At least sixteen dinocyst types were identified, dominated mainly by Protoperidinium spp., Scrippsiellatrochoidea complex, Lingulodinum machaerophorum, Alexandrium spp. and Gymnodinium spp., along with manyround brown cysts. Cyst abundance ranged from 0 to 229 g−1 dry sediment. No significant differences in cyst distributionwere found among stations, though a significant variation was observed among seasons with cyst dominancein autumn. No sign…
Species richness and food web structure of soil decomposer community as affected by the size of habitat fragment and habitat corridors
2005
While most ecologists agree that the effects of fragmentation on diversity of organisms are predominantly negative and that the scale of fragmentation defines their severity, the role of habitat corridors in mitigating those effects still remains controversial. This ambiguousness rests largely on various difficulties in experimentation, a problem partially solved in the present paper by the use of easily manipulated soil communities. In this 2.5-year-long field experiment, we investigated the responses of soil decomposer organisms (from microbes to mesofaunal predators) to habitat fragment size, in the presence or absence of habitat corridors connecting the fragments. The habitat fragments …
III. Biochemistry of S-layers
1997
During evolution prokaryotes have developed different envelope structures exterior to the cell wall proper. Among these surface components are regularly arranged S-layers and capsules. The structural characterization and the detailed chemical analysis of these surface molecules is a prerequisite to understand their biosynthesis and functional role(s) at the molecular level. Of particular interest are the glycosylated S-layer proteins which belong to the first prokaryotic glycoproteins ever described. Their characterization was performed on strains belonging to the thermophilic Bacillaceae and included structural studies and experiments to learn about the pathways for the glycan biosynthesis…
Effects of small-scale habitat fragmentation, habitat corridors and mainland dispersal on soil decomposer organisms
2006
Abstract Habitat corridors have been suggested to be one possible way to reduce the often negative effects of habitat fragmentation. In the present experiment, we focused on small habitat fragments (humus patches) inhabited by soil decomposer organisms. These fragments were either unconnected or connected with each other by habitat (humus) corridors. Moreover, these systems were either isolated from the mainland by a dispersal barrier (plastic “walls”) or were open to dispersal from the mainland. The fragments and corridors were embedded in a matrix of mineral soil that was expected to be uninhabitable or at least an unpreferred habitat for the organisms studied. Undisturbed forest soil fun…
Dynamic Mathematical Modelling of the Removal of Hydrophilic VOCs by Biotrickling Filters
2015
A mathematical model for the simulation of the removal of hydrophilic compounds using biotrickling filtration was developed. The model takes into account that biotrickling filters operate by using an intermittent spraying pattern. During spraying periods, a mobile liquid phase was considered, while during non-spraying periods, a stagnant liquid phase was considered. The model was calibrated and validated with data from laboratory- and industrial-scale biotrickling filters. The laboratory experiments exhibited peaks of pollutants in the outlet of the biotrickling filter during spraying periods, while during non-spraying periods, near complete removal of the pollutant was achieved. The gaseou…