322,953 research outputs found
The Silkworm as a Source of Natural Antimicrobial Preparations: Efficacy on Various Bacterial Strains
No full textThe global spread of multi-resistant pathogens responsible for infections, which cannot be treated with existing drugs such as antibiotics, is of particular concern. Antibiotics are becoming increasingly ineffective and drug resistance is leading to more difficult-to-treat infections; therefore, new bioactive compounds with antimicrobial activity are needed and new alternative sources should be found. Antimicrobial peptides (AMPs) are synthesized by processes typical of the innate immune system and are present in almost all organisms. Insects are extremely resistant to bacterial infections as they can produce a wide range of AMPs, providing an effective first line of defense. The AMPs produced by insects therefore represent a possible source of natural antimicrobial molecules. In this paper, the possibility of using plasma preparations from silkworm (Bombyx mori) larvae as a source of antimicrobials was evaluated. After simple purification steps, insect plasma was analyzed and tested on different Gram-positive and Gram-negative bacterial strains. The results obtained are encouraging as the assays on Escherichia coli and Enterobacter cloacae showed significant decrease in the growth of these Gram-negative bacteria. Similar results were obtained on Gram-positive bacteria, such as Micrococcus luteus and Bacillus subtilis, which showed strong susceptibility to the silkworm AMPs pool. In contrast, Staphylococcus aureus displayed high resistance to Bombyx mori plasma. Finally, the tested plasma formulations were assessed for possible storage not only at 4 °C, but also above room temperature. In conclusion, partially purified plasma from silkworm could be a promising source of AMPs which could be used in formulations for topical applications, without additional and expensive purification steps
A dieci anni dall’emergenza DDT nel lago Maggiore: una proposta di “standard di qualità
No full textZooplankton as an early warning system of persistent organic pollutants contamination in a deep lake (lake Iseo, Northern Italy)
No full textThe lake Iseo has been recently contaminated by DDT residues, originated from the melting of a glacier that released the pollutants accumulated in the past. Because of this recent input, DDT residues concentrations rose more quickly in zooplankton than in fish during 2009. In autumn 2010 the ratio drastically dropped to one–two for all the compounds indicating that the glacial DDT load should have been ceased. The situation was different for PCBs that were released to a much lower extent from glaciers. The PCB 138 ratio between zooplankton and fish was always around one–two in both years. As the zooplankton response to pollution changes resulted particularly prompt, our research highlights the importance of this component as an early warning bioindicator of hydrophobic pollutants
Interconnected impacts of water resource management and climate change on microplastic pollution and riverine biocoenosis: A review by freshwater ecologists
No full textThe relationship between river hydrology and microplastic (MP) pollution is complex: increased discharge does not always mobilize more MPs, but floods can effectively flush out MPs from river catchments. Climate change and water resource management further influence MP pollution and its fate by altering river hydro-sedimentary regimes. This review investigates the interconnected impacts of these factors from a comprehensive perspective, focusing on how they affect MP concentration in freshwater ecosystems, particularly in regulated rivers and associated reservoirs. Our review reveals a scarcity of studies that jointly analyze the interrelated issues of MP pollution, water resource management, and climate change. Key findings indicate that variations in river discharge significantly influence MP mobilization, mainly depending on catchment land use, channel morphology, position within the catchment, and MP characteristics. Reservoirs function as both sinks and sources of MPs, underscoring their complex role in MP dynamics and the need for sustainable sediment management strategies. The increasing frequency of extreme weather events, driven by climate change, along with prolonged droughts intensified by water management practices, exacerbates MP pollution. These changes contribute to the local concentration of MPs, posing direct physical threats to aquatic organisms, particularly benthic species, through pollution and habitat alterations. Current policies on plastic pollution, water resources and climate change are underdeveloped, as these topics have been treated separately so far. In conclusion, this review provides perspectives on future research and policy directions to address challenges posed by MPs and to preserve rivers against multiple stressors
Downstream ecological impacts of controlled sediment flushing in an alpine valley river: a case study
No full textSediment flushing may be effective to tackle the loss of reservoir storage as a result of siltation. When operationally possible, the impact of this practice on the downstream aquatic environment can be mitigated by limiting the sediment concentration of the discharged waters (controlled sediment flushing). However, this topic is poorly documented, and concerns arise when limits are discussed. We present the results of a 3-year field investigation concerning the controlled sediment flushing of a small reservoir on the Adda River, the main tributary of Lake Como-Italy. Two limits for suspended solid concentration (SSC) were adopted: 1.5gL-1, as average value throughout the whole working day, and 3.0gL-1, as alert threshold to adjust the ongoing activity. These constraints were essentially fulfilled in the course of the documented operations. The first year sediment flushing was more significant than the following year: 25000 tons of fines below 2mm in diameter were flushed in six non-consecutive days in summer 2010, while, one year earlier, 75000 tons were flushed in 16 non-consecutive days. In the third year of investigation (2011), no sediment evacuation took place. The benthic macroinvertebrate and the fish communities were surveyed a short distance below the reservoir, that is, in the potentially more affected river reach. Clear pieces of evidence of environmental quality degradation were not detected; the adopted strategies can therefore be considered to be appropriate when planning sediment flushing management in comparable contexts
Recent DDT and PCB contamination in the sediment and biota of the Como Bay (Lake Como, Italy).
No full textDue to its peculiar geographical and morphological characteristics, Lake Como (Northern Italy) represents an interesting study-case for investigating the sub-basin scale circulation of persistent organic pollutants (POPs) that, despite being banned since the 1970s, have reached surprisingly high concentrations in some southern alpine lakes as a consequence of their release from melting glaciers in recent years. In particular, the Como Bay, which is located in the city of Como, seems noteworthy because its waters have a longer residence time than the other areas of the lake. The analyses of the historical concentration of PCBs, pp'DDT and its metabolites in a sediment core sampled from the Como Bay covering a time-period from their ban to recent times, showed that the DDTs have never experienced a significant (p b 0.05) decrease over time, with concentrations of the most abundant homologue, pp'DDE, ranging from 27 to 75 ng g-1 d.w. Conversely PCBs significantly (p b 0.05) decreased towards recent times, reaching concentrations around 80 ng g-1 d.w. The contribution of high altitude and local sources was recorded also in the food web: both zooplankton and the zooplanktivorous fish agone were mainly contaminated by pp'DDE (81.4 ng g-1 w.w. and 534.6 ng g-1 w.w. respectively) and by the PCB metabolite hexa-CB (449.7 ng g-1 w.w. and 1672.1 ng g-1 w.w. respectively). The DDT concentrations in the agone (sampled during the years 2006-2009) never exceeded the limits for human consumption in Italy,while concentrations of six selected PCBs exceeded human health advisory recommendations in one of the fish samples analysed, when it was approximately two times higher than the recommended value of 125 ng g-1 w.w
Valutazione dell’uso di specie ittiche per il biomonitoraggio degli inquinanti organici persistenti nelle acque
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