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showing 10 items of 10735 documents
Spatiotemporal Structure of Host‐Pathogen Interactions in a Metapopulation
2009
International audience; The ecological and evolutionary dynamics of species are influenced by spatiotemporal variation in population size. Unfortunately, we are usually limited in our ability to investigate the numerical dynamics of natural populations across large spatial scales and over long periods of time. Here we combine mechanistic and statistical approaches to reconstruct continuous-time infection dynamics of an obligate fungal pathogen on the basis of discrete-time occurrence data. The pathogen, Podosphaera plantaginis, infects its host plant, Plantago lanceolata, in a metapopulation setting where the presence of the pathogen has been recorded annually for 6 years in similar to 4,00…
Bayesian spatio-temporal discard model in a demersal trawl fishery
2014
Spatial management of discards has recently been proposed as a useful tool for the protection of juveniles, by reducing discard rates and can be used as a buffer against management errors and recruitment failure. In this study Bayesian hierarchical spatial models have been used to analyze about 440 trawl fishing operations of two different metiers, sampled between 2009 and 2012, in order to improve our understanding of factors that influence the quantity of discards and to identify their spatio-temporal distribution in the study area. Our analysis showed that the relative importance of each variable was different for each metier, with a few similarities. In particular, the random vessel eff…
Molecular determinants of the Arabidopsis AKT1 K+ channel ionic selectivity investigated by expression in yeast of randomly mutated channels
1999
International audience; The Avabidopsis thaliana K+ channel AKT1 was expressed in a yeast strain defective for K+ uptake at low K+ concentrations (<3 mM). Besides restoring K+ transport in this strain, AKT1 expression increased its tolerance to salt (NaCl or LiCl), whatever the external K+ concentration used (50 mu M, 5 mM, or 50 mM), We took advantage of the latter phenomenon for screening a library of channels randomly mutated in the region that shares homologies with the pore forming domain (the so-called P domain) of animal K+ channels (Shaker family). Cassette mutagenesis was performed using a degenerate oligonucleotide that was designed to ensure, theoretically, a single mutation per …
Symbiosis-related plant genes modulate molecular responses in an arbuscular mycorrhizal fungus during early root interactions.
2009
To gain further insight into the role of the plant genome in arbuscular mycorrhiza (AM) establishment, we investigated whether symbiosis-related plant genes affect fungal gene expression in germinating spores and at the appressoria stage of root interactions. Glomus intraradices genes were identified in expressed sequence tag libraries of mycorrhizal Medicago truncatula roots by in silico expression analyses. Transcripts of a subset of genes, with predicted functions in transcription, protein synthesis, primary or secondary metabolism, or of unknown function, were monitored in spores and germinating spores and during interactions with roots of wild-type or mycorrhiza-defective (Myc–) mutan…
Agro-Morphological Characterization of Sicilian Chili Pepper Accessions for Ornamental Purposes
2020
The species belonging to the genus Capsicum have been widely used as decorative vegetables, however only a few genotypes are available for this purpose. The goal of the present work was the agro-morphological characterization of several chili pepper accessions cultivated into different pot sizes (10, 14, 18 or 20 cm diameters). The agro-morphological characterization of 19 accessions was performed following IPGR (International Plant Genetic Resources Institute) descriptors: plant height (PH), plant canopy width (PCW), PH/PCW ratio, plant growth habit, plant visual quality, first flower emission, fruiting start, end of harvest, fruit number, fruit length, fruit width, fruit color at mature s…
The shoot concept of the flower: Still up to date?
2016
Abstract The shoot concept of the flower suggests that flowers correspond to vegetative short-shoots except the fact that their lateral appendages are floral and not vegetative leaves. However, in view of the different properties of vegetative and flower meristems, this concept should be questioned. Differential meristem activity resulting in tubes, hypanthia and inferior ovaries, continuous meristem expansion providing space for stamen fascicles and additional structures and the process of (repeated) fractionation using a given space completely, are characteristics of flower meristems hardly explainable with the shoot concept. Linking instead flower development with recent findings in mole…
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…
Plasmodium relictum infection and MHC diversity in the house sparrow (Passer domesticus).
2010
Antagonistic coevolution between hosts and parasites has been proposed as a mechanism maintaining genetic diversity in both host and parasite populations. In particular, the high level of genetic diversity usually observed at the major histocompatibility complex (MHC) is generally thought to be maintained by parasite-driven selection. Among the possible ways through which parasites can maintain MHC diversity, diversifying selection has received relatively less attention. This hypothesis is based on the idea that parasites exert spatially variable selection pressures because of heterogeneity in parasite genetic structure, abundance or virulence. Variable selection pressures should select for…
Proposed Environmental Risk Management Elements in a Carpathian Valley Basin, within the Roşia Montană European Historical Mining Area
2021
Non-ferrous metals mining activities have long accompanied people, and began in the study area of South East Europe over 2000 years ago. The environment quality is significantly affected by both historic mining activities and contemporary impacts. All these problems, inducing synergic negative effects on local organism communities, have created a chronic state of pollution. The Corna Valley has one of the oldest historical human impacts in Romania due to the influence of mining. Fish and benthic macroinvertebrates have exhibited significant responses to long term mining effects on lotic systems. The analysis of macroinvertebrate communities, correlated with the lack of fish and some biotope…
Human-associated migration of Holarctic Saccharomyces uvarum strains to Patagonia
2020
Our results show that the greatest S. uvarum population diversity worldwide is observed in Patagonia, where strains of this species can be isolated from industrial and traditional fermentations as well as from natural environments. This greater Patagonian diversity is due to the presence of strains belonging to two genetically differentiated populations, South America B (SA-B), and Holarctic/South America A (H/SA-A). The H/SA-A population of Patagonia is directly related to apple fermentation environments, mainly from cider fermentations but also, to a lesser extent, from traditional apple chicha. Our data suggest that strains from the Holarctic population colonized Patagonia. This is possi…