Search results for "Seasons"
showing 10 items of 361 documents
Organic carbon and nitrogen stable isotopes in the intertidal sediments from the Yangtze Estuary, China
2005
The natural isotopic compositions and C/N elemental ratios of sedimentary organic matter were determined in the intertidal flat of the Yangtze Estuary. The results showed that the ratios of carbon and nitrogen stable isotopes were respectively -29.8 per thousand to -26.0 per thousand and 1.6 per thousand-5.5 per thousand in the flood season (July), while they were -27.3 per thousand to -25.6 per thousand and 1.7 per thousand-7.8 per thousand in the dry season (February), respectively. The delta(13)C signatures were remarkably higher in July than in February, and gradually increased from the freshwater areas to the brackish areas. In contrast, there were relatively complex seasonal and spati…
Linking chlorophyll a fluorescence to photosynthesis for remote sensing applications: mechanisms and challenges
2014
Chlorophyll a fluorescence (ChlF) has been used for decades to study the organization, functioning, and physiology of photosynthesis at the leaf and subcellular levels. ChlF is now measurable from remote sensing platforms. This provides a new optical means to track photosynthesis and gross primary productivity of terrestrial ecosystems. Importantly, the spatiotemporal and methodological context of the new applications is dramatically different compared with most of the available ChlF literature, which raises a number of important considerations. Although we have a good mechanistic understanding of the processes that control the ChlF signal over the short term, the seasonal link between ChlF…
An Investigation of the Seasonal Pattern of Mannitol Content in Deciduous and Evergreen Species of the Oleaceae Growing in Northern Sicily
2002
In several species of the Oleaceae, mannitol, already present at considerable levels, accumulates in response to stress. This family comprises both deciduous and evergreen species, and we investigated the role of mannitol in deciduous malacophyll and evergreen sclerophyll species growing under the same conditions in the field. The relationship between mannitol content and changes in rainfall or temperature was also studied. The mannitol content of leaves of Fraxinus ornus L., F. angustifolia Vahl., Olea europaea L. and Phillyrea media L. was determined by gas chromatography. Leaf samples were collected once a month for 1 year. In the two ash species, the seasonal pattern of mannitol content…
Seasonal variations of antimicrobial activity and chemical composition of essential oils extracted from three Citrus limon L. Burm. cultivars
2014
In order to investigate the seasonal variations of antimicrobial properties and chemical composition of essential oils (EOs), three different cultivars of Citrus limon L. Burm. spp. (Femminello Santa Teresa, Monachello and Femminello Continella) were collected at 6-week intervals, from December 2012 to April 2013, for a total of four harvests. The EOs were extracted from lemon peel by hydro-distillation. The antimicrobial activity, tested by paper disc diffusion method, was evaluated against common food-related pathogenic bacteria (Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica and Enterobacter spp.). EOs were more effective against Gram-positive than Gram-negative bacte…
An MLSA approach for the taxonomic update of the Splendidus clade, a lineage containing several fish and shellfish pathogenic Vibrio spp.
2016
A multilocus sequence analysis was undertaken in order to redefine the Splendidus clade of the genus Vibrio, a large group of species containing several pathogenic members that affect fish and shellfish, and are difficult to identify through both phenotypic and genotypic approaches. The study included analysis of partial sequences of recA, gyrB, mreB, rpoD and pyrH genes, as well as the 16S rRNA gene. Seventeen type strain species were included that were complemented with other reference strains and a collection of isolates tentatively identified as members of this clade, as well as a set of other Vibrio species. The clade was well defined and stable in all analyses, and was confirmed to co…
Ribotyping of Vibrio Populations Associated with Cultured Oysters (Ostrea edulis)
2000
The intraspecific variability of Vibrio splendidus, V. harveyi and V. tubiashii recovered from oysters (Ostrea edulis) collected at the Mediterranean coast near Valencia, Spain, was analyzed by ribotyping. The two former species represented the most abundant ones, and the third one was the only species described as pathogenic for oysters. A total of 115 environmental strains were studied, 84 of V. splendidus, 23 of V. harveyi and 8 of V. tubiashii. Chromosomal DNA was digested with KpnI and hybridized with an oligonucleotide probe complementary to a highly conserved sequence in the 23S rRNA gene. Ribotyping among natural populations of the three species rendered 5 to 9 bands, and showed a h…
Borrelia burgdorferi sensu lato in Ixodes ricinus ticks collected from migratory birds in Southern Norway
2010
Abstract Background Borrelia burgdorferi sensu lato (s.l.) are the causative agent for Lyme borreliosis (LB), the most common tick-borne disease in the northern hemisphere. Birds are considered important in the global dispersal of ticks and tick-borne pathogens through their migration. The present study is the first description of B. burgdorferi prevalence and genotypes in Ixodes ricinus ticks feeding on birds during spring and autumn migration in Norway. Methods 6538 migratory birds were captured and examined for ticks at Lista Bird Observatory during the spring and the autumn migration in 2008. 822 immature I. ricinus ticks were collected from 215 infested birds. Ticks were investigated f…
Acidobacteria dominate the active bacterial communities of Arctic tundra with widely divergent winter-time snow accumulation and soil temperatures.
2012
The timing and extent of snow cover is a major controller of soil temperature and hence winter-time microbial activity and plant diversity in Arctic tundra ecosystems. To understand how snow dynamics shape the bacterial communities, we analyzed the bacterial community composition of windswept and snow-accumulating shrub-dominated tundra heaths of northern Finland using DNA- and RNA-based 16S rRNA gene community fingerprinting (terminal restriction fragment polymorphism) and clone library analysis. Members of the Acidobacteria and Proteobacteria dominated the bacterial communities of both windswept and snow-accumulating habitats with the most abundant phylotypes corresponding to subdivision …
Increase in norovirus activity reported in Europe.
2006
A large increase in norovirus outbreaks in Hungary and Germany was reported to European national health authorities via the Foodborne Viruses in Europe network
Seasonal diet-based resistance to anticoagulant rodenticides in the fossorial water vole (Arvicola amphibius)
2021
International audience; Anticoagulant rodenticides (AR) resistance has been defined as "a major loss of efficacy due to the presence of a strain of rodent with a heritable and commensurately reduced sensitivity to the anticoagulant". The mechanism that supports this resistance has been identified as based on mutations in the Vkorc1 gene leading to severe resistance in rats and mice. This study evaluates the validity of this definition in the fossorial water vole and explores the possibility of a non-genetic diet-based resistance in a strict herbivorous rodent species. Genetic support was explored by sequencing the Vkorc1 gene and the diet-based resistance was explored by the dosing of vitam…