1,720,977 research outputs found
Bioavailability of potentially toxic metals and chromium speciation by isotope dilution mass spectrometry in a sludge-polluted farmland under phytoremediation.
No full textBioavailability to plants and human beings of potentially toxic metals in two italian polluted soils.
No full textThe influence of growth conditions on biomass, toxins and pathogenicity of Fusarium oxysporum f. sp. orthoceras, a potential agent for broomrape biocontrol
No full textThe influence of different combinations of illumination
and shaking on the growth dynamics, pathogenicity and
toxin production of the fungus Fusarium oxysporum
f. sp. orthoceras, a biocontrol agent of Orobanche
cumana, was studied. The fastest biomass accumulation
was obtained under shaking, with or without illumination,
with the highest biomass obtained after 3–4 weeks
of growth. The biological activity of chloroform extracts
of the culture filtrate was characterised: it contained at
least two main toxic metabolites that caused necrosis
and wilting of various plants and led to mortality of
germinating seeds of O. cernua, O. aegyptiaca,
O. ramosa and O. cumana. The highest toxic activity
of the chloroform extract was obtained under illumination
without shaking after 3–4 weeks of growth. The
two toxic metabolites were purified and identified as
fusaric acid (FA) and 9,10-dehydrofusaric acid (DFA).
Both FA and DFA production began in the first week of
growth, increasing gradually to their maxima after
4 weeks. The highest level of pathogenic activity of the
fungus was obtained after three or more weeks of fungal
growth. It can be concluded that in order to produce
high levels of toxin and pathogenic activity, the fungus
should be grown under illumination without shaking for
4 weeks
The influence of growth conditions on biomass, toxins and pathogenicity of Fusarium oxysporum f. sp. orthoceras, a potential agent for broomrape biocontrol
No full textThe influence of different combinations of illumination
and shaking on the growth dynamics, pathogenicity and
toxin production of the fungus Fusarium oxysporum
f. sp. orthoceras, a biocontrol agent of Orobanche
cumana, was studied. The fastest biomass accumulation
was obtained under shaking, with or without illumination,
with the highest biomass obtained after 3–4 weeks
of growth. The biological activity of chloroform extracts
of the culture filtrate was characterised: it contained at
least two main toxic metabolites that caused necrosis
and wilting of various plants and led to mortality of
germinating seeds of O. cernua, O. aegyptiaca,
O. ramosa and O. cumana. The highest toxic activity
of the chloroform extract was obtained under illumination
without shaking after 3–4 weeks of growth. The
two toxic metabolites were purified and identified as
fusaric acid (FA) and 9,10-dehydrofusaric acid (DFA).
Both FA and DFA production began in the first week of
growth, increasing gradually to their maxima after
4 weeks. The highest level of pathogenic activity of the
fungus was obtained after three or more weeks of fungal
growth. It can be concluded that in order to produce
high levels of toxin and pathogenic activity, the fungus
should be grown under illumination without shaking for
4 weeks
Chemical and Spectroscopic Characteristics of the Wood of Vitis vinifera Cv. Sangiovese Affected by Esca Disease
No full textChemical and spectroscopic analyses (13C cross-polarization-magic angle spinning NMR and attenuated total reflection Fourier transform infrared spectroscopies) were carried out on the wood of Vitis vinifera cv. Sangiovese with brown-red discoloration and black streaks caused by esca disease. The analyses of the brown-red wood revealed the destruction of hemicelluloses and
noncrystalline cellulose as well as modifications in the pectic and ligninic wood fractions. The pectic fraction consisted of carbohydrates associated with polyphenols. The lignin fraction exhibited only a few changes in the aromatic systems and a partial demethylation, and it appeared to be associated with condensed phenolic components probably arising from response polyphenols. The degradation of hemicelluloses and noncrystalline cellulose in brown-red wood, where the pathogens Phaeoacremonium aleophilum and Phaeomoniella chlamydospora prevail with respect to the other fungus Fomitiporia mediterranea, was consistent with reports on the degradative activity of such fungi in vitro carried out on model substrates. The observed alterations could also be attributed to the radical oxidation process caused by the oxidative response of defense itself triggered by infection, as suggested by the accumulation of postinfectional compounds. The analyses of wood tissue with black streaks showed less marked deterioration; here, an increase in pectic and phenolic substances, which probably accumulate in the xylem vessels as a response to the infection, was observed
Copper accumulation in agricultural soils: Risks for the food chain and soil microbial populations
No full textThe long-term use of Cu-based fungicides at doses of several kilograms per hectare stimulated a wide debate about the human health and environmental risks of the progressive accumulation of Cu in agricultural soils. Here, the health risks due to copper accumulation in agricultural soils were evaluated with a survey in intensive agricultural land of the Campania region (Italy), aiming to evaluate Cu accumulation in food crops. The health risk due to dietary exposure was estimated by using the Hazard Quotient (HQ), calculated as the ratio between the average daily dose and the reference dose of copper, suggesting that when HQ > 1 there is a potential risk for consumers. According to a survey of soils with a Cu content up to 217 mg kg−1, no foodstuffs showed dietary risks. Nevertheless, the contribution of Cu contained in these foodstuffs to the overall intake of Cu by consumers could increase health risks since such risks must be evaluated on the basis of the whole standard diet by quantifying the Cu content not only in vegetables and fruits but also in other sources, such as cereals, not cultivated in the study area and thus not considered in this paper. The environmental risks due to copper accumulation in agricultural soils were then evaluated with a field experiment in a soil characterized by a very high Cu concentration (up to 1700 mg kg−1), aiming to study the impacts of Cu on native soil microorganisms. The study of the microbiota highlighted that the presence of Cu in soil did not reduce the total richness and diversity of microorganisms, which were not related to increasing concentrations of Cu in the soil. Nevertheless, Cu contamination was found to exert significant selection pressure on the soil microbiota, as shown by beta diversity and correlation analysis between taxa and Cu content
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
