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排序方式: 共有125条查询结果,搜索用时 15 毫秒
1.
Harmful algal blooms pose a challenge regarding food safety due to their erratic nature and forming circumstances which are yet to be disclosed. The best strategy to protect human consumers is through legislation and monitoring strategies. Global warming and anthropological intervention aided the migration and establishment of emerging toxin producers into Europe’s temperate waters, creating a new threat to human public health. The lack of information, standards, and reference materials delay effective solutions, being a matter of urgent resolution. In this work, the recent findings of the presence of emerging azaspiracids, spirolildes, pinnatoxins, gymnodimines, palitoxins, ciguatoxins, brevetoxins, and tetrodotoxins on European Coasts are addressed. The information concerning emerging toxins such as new matrices, locations, and toxicity assays is paramount to set the risk assessment guidelines, regulatory levels, and analytical methodology that would protect the consumers. 相似文献
2.
Janaina Braga do Carmo Marisa de Cssia Piccolo Cristiano Alberto de Andrade Carlos Eduardo Pellegrino Cerri Brigitte Josefine Feigl Erclito Sousa Neto Carlos Clemente Cerri 《Soil & Tillage Research》2007,96(1-2):250-259
Anthropogenic conversion of primary forest to pasture for cattle production is still frequent in the Amazon Basin. Practices adopted by ranchers to restore productivity to degraded pasture have the potential to alter soil N availability and N gas losses from soils. We examined short-term (35 days) effects of tillage prior to pasture re-establishment on soil N availability, CO2, NO and N2O fluxes and microbial biomass C and N under degraded pasture at Nova Vida ranch, Rondônia, Brazilian Amazon. We collected soil samples and measured gas fluxes in tilled and control (non tilled pasture) 12 times at equally spaced intervals during October 2001 to quantify the effect of tillage. Maximum soil NH4+ and NO3− pools were 13.2 and 6.3 kg N ha−1 respectively after tillage compared to 0.24 and 6.3 kg N ha−1 in the control. Carbon dioxide flux ranged from 118 to 181 mg C–CO2 m2 h−1 in the control (non-tilled) and from 110 to 235 mg C–CO2 m2 h−1 when tilled. Microbial biomass C varied from 365 to 461 μg g−1 in the control and from 248 to 535 μg g−1 when tilled. The values for N2O fluxes ranged from 1.22 to 96.9 μg N m−2 h−1 in the tilled plots with a maximum 3 days after the second tilling. Variability in NO flux in the control and when tilled was consistent with previous measures of NO emissions from pasture at Nova Vida. When tilled, the NO/N2O ratio remained <1 after the first tilling suggesting that denitrification dominated N cycling. The effects of tilling on microbial parameters were less clear, except for a decrease in qCO2 and an increase in microbial biomass C/N immediately after tilling. Our results suggest that restoration of degraded pastures with tillage will lead to less C matter, at least initially. Further long-term research is needed. 相似文献
3.
Fedoriw AM Stein P Svoboda P Schultz RM Bartolomei MS 《Science (New York, N.Y.)》2004,303(5655):238-240
The imprinted regulation of H19 and Insulin-like growth factor 2 expression involves binding of the vertebrate insulator protein, CCCTC binding factor (CTCF), to the maternally hypomethylated differentially methylated domain (DMD). How this hypomethylated state is maintained during oogenesis and the role of CTCF, if any, in this process are not understood. With the use of a transgenic RNA interference (RNAi)-based approach to generate oocytes with reduced amounts of CTCF protein, we found increased methylation of the H19 DMD and decreased developmental competence of CTCF-deficient oocytes. Our results suggest that CTCF protects the H19 DMD from de novo methylation during oocyte growth and is required for normal preimplantation development. 相似文献
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Participation in conservation programs is often viewed as a necessity, but understanding of this participation is limited. This research takes a different approach by also examining participation in non-conservation-related activities. Questionnaires (N = 339) were administered in four Brazilian coastal communities where the national sea turtle conservation project conducts monitoring and outreach. Employing social capital as a conceptual framework, measurements included participation in civic, community, and social activities along with group participation and collective action. Confirmatory factor analysis was used for validating measures of social capital and conservation perceptions. Structural equation modeling indicated that social capital has a positive relationship with participation in sea turtle conservation, suggesting that general levels of participation and community norms of participation could be just as influential as conservation perceptions to engage communities in conservation. Information gained by deconstructing participation may be used to design and target conservation programs, improving overall participation. 相似文献
6.
Robert J. Johnston James J. Opaluch Thomas A. Grigalunas Marisa J. Mazzotta 《Growth and change》2001,32(3):305-325
This paper investigates differences in non‐market farmland amenity values estimated using distinct methodologies, with a focus on the potential causes and policy implications. The paper compares farmland amenity values generated by a hedonic property value model and a contingent choice model, both estimated from data collected in the Peconic Estuary System of Suffolk County, NY. The analysis demonstrates that a combination of non‐market valuation methodologies can provide policy insights not otherwise available to those relying on any single approach, and illustrates types of information that may be obscured by methodologies used in isolation. 相似文献
7.
Seventy-six rhizobial isolates belonging to four different genera were obtained from the root nodules of several legumes (Vicia sativa, Vicia faba, Medicago sativa, Melilotus sp., Glycine max and Lotus corniculatus). The action of five commonly used herbicides [2,4-dichlorophenoxyacetic acid (2,4-D), glyphosate (GF), dicamba, atrazine and metsulfuron-methyl] on the growth of rhizobial strains was assessed. Subsequently, GF and 2,4-D were tested in a minimum broth as C and energy sources for 20 tolerant strains. The ability of these strains to metabolize different carbon sources was studied in order to detect further differences among them. Tolerance of the bacteria to agrochemicals varied; 2,4-D and GF in solid medium inhibited and diminished growth, respectively, in slow-growing rhizobial strains. Among slow-growing strains we detected Bradyrhizobium sp. SJ140 that grew well in broth + GF as the sole C and energy source. No strain was found which could use 2,4-D as sole C source. The 20 strains studied exhibited different patterns of C sources utilization. Cluster analysis revealed three groups, corresponding to four genera of rhizobia: Rhizobium (group I), Sinorhizobium (group II) and Mesorhizobium–Bradyrhizobium (group III). On the basis of the results obtained on responses to herbicides and C sources utilization by the isolates investigated, it was possible to differentiate them at the level of strains. These results evidenced a considerable diversity in rhizobial populations that had not been previously described for Argentinean soils, and suggested a physiological potential to use natural and xenobiotic C sources. 相似文献
8.
The influence of the provenance soil and vinification process on the wine multielemental composition was investigated. For this purpose, two different vineyards from the Douro wine district, Portugal, were selected. Monovarietal grapes from a 10 year old vineyard were used to produce a red table wine, in a very modern winery. Polyvarietal grapes from a 60-70 year old vineyard were used to produce a red fortified wine, similar to Port, through a traditional vinification process. The multielement compositions (Al, As, B, Ba, Be, Ca, Cd, Co, Cr, Cs, Cu, Fe, Ga, Hf, Li, Mn, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Sr, Ti, Th, Tl, U, V, W, Y, Zn, Zr, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) of soil, grape juices (prepared in the laboratory), and samples collected in the different steps of each winemaking process were measured. Inductively coupled plasma mass spectrometry was used, after suitable pretreatment of the samples (by UV irradiation for liquid samples and high-pressure microwave digestion for soil). Both vinification processes influenced the multielement composition of the wines. Most of the elements presented similar or even lower concentrations in the wine as compared to that observed in the respective grape juice, probably as a result of precipitation or coprecipitation with suspended particles during fermentation and/or wine aging. Evidence of effective contamination during grape pressing, fermentation, and/or fining of wines (depending on the element) was observed for Cd, Cr, Cu, Fe, Ni, Pb, V, and Zn in the fortified wine and Al, Cr, Fe, Ni, Pb, and V in the table wine. Nevertheless, significant correlations were obtained between the multielement composition of the wine and the respective grape juice (R = 0.997 and 0.979 for the fortified and table wines, respectively, n = 31, P < 0.01), as well as between that in the wine (median of the two studied wines) and the provenance soil (R = 0.994, n = 19, P < 0.01), for the set of elements determined in common in the different types of samples. These results are promising concerning the usefulness of the elemental patterns of both soil and wine as fingerprints of the origin of the studied wines. Nevertheless, more wines from the same and other wine districts must be studied in order to consolidate this conclusion. The multielement compositions of the studied wines were compared with those of wines of different characteristics and origins, as well as with the respective legal threshold limit values, when available. Relatively low metal levels, below their threshold limit values, were found in all cases. 相似文献
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Carmela Gallo Giusi Barra Marisa Saponaro Emiliano Manzo Laura Fioretto Marcello Ziaco Genoveffa Nuzzo Giuliana dIppolito Raffaele De Palma Angelo Fontana 《Marine drugs》2020,18(12)
Immunotherapy takes advantage of the immune system to prevent, control, and eliminate neoplastic cells. The research in the field has already led to major breakthroughs to treat cancer. In this work, we describe a platform that integrates in vitro bioassays to test the immune response and direct antitumor effects for the preclinical discovery of anticancer candidates. The platform relies on the use of dendritic cells that are professional antigen-presenting cells (APC) able to activate T cells and trigger a primary adaptive immune response. The experimental procedure is based on two phenotypic assays for the selection of chemical leads by both a panel of nine tumor cell lines and growth factor-dependent immature mouse dendritic cells (D1). The positive hits are then validated by a secondary test on human monocyte-derived dendritic cells (MoDCs). The aim of this approach is the selection of potential immunotherapeutic small molecules from natural extracts or chemical libraries. 相似文献