Many classical therapeutants are going to be banned in Europe, and an urgent need for alternatives is emerging. This issue can be exemplified by one major parasitic disease in aquaculture and ...ornamental fish breeding: velvet disease. This disease, caused by dinoflagellates of the genera Amyloodinium and Piscinoodinium, is an important infection affecting cultured freshwater and marine ornamental and food fish, and consistently causes great financial loss to the associated industries. Therapeutants available contain copper, malachite green, or methylene blue, and which can be toxic to non‐target organisms in the surrounding environment. As a result, these chemicals are banned for use by the aquaculture industry in several countries, and a prohibition for commercial ornamental fishkeeping is likely to follow in most countries. Increasing development of resistance to therapeutants, and growing public awareness for animal welfare and environmental protection, have prompted research in the areas of alternative treatment options and immunostimulants. Hydrogen peroxide and peracetic acid are possible ‘green’ therapeutants which do not contribute residues to the environment. Natural feed supplements such as pre‐ and probiotics can increase animal welfare and prevent stress and/or infections. Humic substances are another promising, natural immunostimulants which will be considered in depth. The aim of this review is to provide an overview of risks and benefits of current treatment options and new approaches to replace harmful therapeutants and minimize the number of toxic residues discharged into the environment. Treatments will be discussed on various parasitic infections and focus, where available, on Amyloodinium and Piscinoodinium.
Quercetin, Caffeic- and Rosmarinic acid exposure extend lifespan in
Caenorhabditis elegans
. This comparative study uncovers basic common and contrasting underlying mechanisms: For all three ...compounds, life extension was characterized by hormetic dose response curves, but
hsp
-level expression was variable. Quercetin and Rosmarinic acid both suppressed bacterial growth; however, antibacterial properties were not the dominant reason for life extension. Exposure to Quercetin, Caffeic- and Rosmarinic acid resulted in reduced body size, altered lipid-metabolism and a tendency towards a delay in reproductive timing; however the total number of offspring was not affected. An indirect dietary restriction effect, provoked by either chemo-repulsion or diminished pharyngeal pumping was rejected. Quercetin and Caffeic acid were shown to increase the antioxidative capacity in vivo and, by means of a lipofuscin assay, reduce the oxidative damage in the nematodes. Finally, it was possible to demonstrate that the life and thermotolerance enhancing properties of Caffeic- and Rosmarinic acid both rely on
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in the case of Caffeic acid. Taken together, hormesis, in vivo antioxidative/prooxidative properties, modulation of genetic players, as well as the re-allocation of energy all contribute (to some extent and dependent on the polyphenol) to life extension.
Aquaculture has become imperative to cover the demands for dietary animal protein. Simultaneously, it has to overcome prejudices from excessive use of antibiotics and environmental impacts. Natural ...supplements are traditionally applied orally. In this study, we demonstrated another pathway: the gills. Humic substances are immunostimulants and a natural part of every aquatic ecosystem, making them ideal to be used as bath stimulants. Five and 50 mg C/L of a fulvic acid-rich humic substance was added for 28 days to the water of juvenile rainbow trout (Oncorhynchus mykiss). This fulvic acid is characterized by a high content of phenolic moieties with persistent free radicals and a high electron exchange capacity. The high concentration of the fulvic acid significantly increased growth and reduced the food conversion ratio and the response to a handling-stressor. Phagocytosis and potential killing activity of head kidney leukocytes were increased, as well as the total oxyradical scavenging capacity (TOSC) and lysozyme activity in the gills. In conclusion, immunostimulation via gills is possible with our fulvic acid, and the high phenolic content improved overall health and stress resistance of fish.
Biomass chars are known to be intrinsically redox-reactive toward some organic compounds, but the mechanisms are still unclear. To address this, a char made anoxically at 500 °C from dealkaline ...lignin was reacted either in the fresh state or after 180-day aging in air with
-nitrophenol (NO
-P),
-hydroxybenzaldehyde (CHO-P), phenol (H-P), or
-methoxyphenol (MeO-P). The reactions were carried out under oxic or anoxic conditions. Degradation occurred in all cases. Both oxidation and reduction products were identified, with yields dependent on the presence or absence of air during reaction or storage. They included oligomers, amines, and ring-hydroxylated compounds, among others. Exposure to air suppressed sorption, annihilated reducing sites, and provided a source of reactive oxygen species that assisted degradation. Sorption suppression was due to the incorporation of hydrophilic groups by chemisorption of oxygen, and possibly blockage of sites by products. Fresh char has comparable electron-donating and accepting capacity, whereas there is a preponderance of electron-accepting over donating capacity in aged char. Under anoxic conditions, both oxidation and reduction occurred. Under oxic conditions or after aging in air, oxidation predominated, and linear free energy relationships were found between the rate constant and the Hammett or Brown substituent electronic parameter or the standard electrode potential of the phenol. The results demonstrate that chars possess heterogeneous redox activities depending on reaction pairs, reaction conditions, and aging.
Inflammation is an essential process as a reaction towards infections or wounding. Exposure to hazardous environmental pollutants can lead to chronic inflammations, where the resolving phase is ...delayed or blocked. Very contradictory studies have been reported on the pro- and anti-inflammatory effects of humic substances (HSs) leading to significant disagreements between researchers. To a certain extent, this can be attributed to the chemical heterogeneity of this group of xenobiotics. Here we show for the first time that pro- and anti-inflammatory effects can occur by one HSs. We adapted an assay that uses green fluorescence-labeled zebrafish larvae and CuSO
to indue an inflammation. In wild-type larvae, exposure to 50 µM CuSO
for 2 h activated the production of reactive oxygen species, which can be monitored with a fluorescence dye (H2DCFDA) and a microplate reader. This allows not only the use of wild-type fish but also a temporal separation of copper exposure and inflammatory substance while retaining the high throughput. This modified assay was then used to evaluate the inflammatory properties of a fulvic acid (FA). We found, that the aromatic structure of the FA protects from inflammation at 5 and 50 mg C/L, while the persistent free radicals enhance the copper-induced inflammation at ≥ 300 mg C/L.
Biochars are being increasingly applied in soil for carbon sequestration, fertility improvement, as well as contamination remediation. Phosphoric acid (H3PO4) pretreatment is a method for biochar ...modification, but the mechanism is not yet fully understood. In this work, biochars and the raw biomass were treated by H3PO4 prior to pyrolysis. Due to an acid catalysis and crosslink, the micropores of the pretreated particles were much more than those without H3PO4 pretreatment, resulting in the dramatical enhancement of specific surface areas of the pretreated particles. Crystalline cellulose (CL) exhibited a greater advantage in the formation of micropores than of amorphous lignin (LG) with H3PO4 modification. The formation mechanisms of micropores were: (a) H+ from H3PO4 contributes to micropores generation via H+ catalysis process; (b) the organic phosphate bridge protected the carbon skeleton from micropore collapse via the crosslinking of phosphate radical. The sorption capacities to carbamazepine (CBZ) and bisphenol A (BPA) increased after H3PO4 modification, which is ascribed to the large hydrophobic surface areas and more abundant micropores. Overall, H3PO4 pretreatment produced biochars with large surface area and high abundance of porous structures. Furthermore, the H3PO4 modified biochars can be applied as high adsorbing material as well as P-rich fertilizer.
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•Phosphoric acid treatment enhances surface area due to the generated micropores.•Cellulose produces more micropores than lignin after phosphoric acid treatment.•Acid catalysis and crosslinking contribute to micropore generation.•Large surface area and pore volume of the treated biochars enhanced the sorption.•Phosphoric acid modified biochars could be applied in P-depleted soil.
H3PO4 pretreatment enhances the sorption of organic pollutants on biochars by generation of micropores.
Phytoremediation of waters by aquatic organisms such as algae has been recently explored for the removal of organic pollutants possessing endocrine disrupting capacity. Monoraphidium braunii, a green ...alga known for rapid growth and good tolerance to different natural organic matter (NOM) qualities, was tested in this study for the ability to tolerate and remove the endocrine disruptor bisphenol A at concentrations of 2, 4 and 10mgL−1, either in NOM-free or NOM-containing media. NOM at concentrations of 2, 5 and 20mgL−1 of DOC, was added because it may interfere with xenobiotics and modify their effects, modulate algal growth performances or produce a trade-off of both effects. After 2 and 4days of algal growth, the cell number and size, the maximum quantum yield of photosystem II in the dark or light adapted state, and the chlorophyll a content were recorded in order to evaluate the algal response to bisphenol A. Moreover, the residual bisphenol A was measured in the algal cultures by chromatographic technique. Results indicated that after 2 and 4days bisphenol A at the lower concentrations was not toxic for alga, whereas at the highest concentration it reduced algal growth and photosynthetic efficiency. The sole NOM and its combinations with bisphenol A at the lower concentrations increased the cell number and the chlorophyll a content of algae. After 4-day growth, good removal efficiency was exerted by M. braunii at concentrations of 2, 4 and 10mgL−1 removing, respectively, 39%, 48% and 35% of the initial bisphenol A. Lower removal percentages were found after 2-day growth in the different treatments. NOM at any concentration scarcely influenced the bisphenol A removal. On the basis of data obtained, the use of M. braunii could be reasonably recommended for the phytoremediation of aquatic environments from bisphenol A.
► The alga Monoraphidium braunii tolerates high concentrations of bisphenol A. ► The alga Monoraphidium braunii removes relevant amount of bisphenol A from water. ► Natural organic matter reduces the bisphenol A toxicity on Monoraphidium braunii. ► Natural organic matter does not reduce bisphenol A removal by Monoraphidium braunii.
pH-development in a Desmodesmus armatus culture (A) and (B) growth inhibition of D. armatus over time by the polyphenols tannic acid, gallic acid and hydroquinone as well as by the indole alkaloid ...gramine. During the culture period, the initial pH of 7.64 rose to 10.95; data points are means of four replicates±standard deviation. For sake of comparison, one of the most aggressive polyphenol, hydroquinone, is included (redrawn from Bährs et al., 2013). Indicated are the concentrations which allow the kinetic approach. Display omitted
•We compare the algicidal properties of two polyphenols and one alkaloid.•Polyphenols, but not the alkaloid, lose their efficacy if the pH rises.•Most likely the efficacy of polyphenols is overrated.
Allelochemical action against planktonic phototrophs is one central issue in freshwater ecology and quality management. To determine some basic mechanisms of this toxic action, we exposed the coccal green alga, Desmodesmus armatus, and the coccal cyanobacterium, Microcystis aeruginosa, in a batch culture well-supplied with carbon dioxide to increasing concentrations of the polyphenols tannic acid and gallic acid and the alkaloid gramine. The phototrophs were checked after 2d and at the end of the culture for biomass-based growth rates, cell volume, maximum quantum yield of photosystem II (ΦPSIImax), chlorophyll a content (chla) after 2d and at the end of the culture, and lipid peroxidation only at the end of the culture. During the culture, the pH rose from 7.64 to 10.95, a pH characteristic of eutrophic freshwater bodies during nuisance algal blooms. All xenobiotics reduced the growth rate, ΦPSIImax, and chla during the first 2d with M. aeruginosa being more sensitive to the polyphenols than D. armatus. The efficacy of the polyphenols declined with increasing pH, indicating potential polymerization and corresponding reduced bioavailability of the polyphenols. In contrast to the polyphenols, gramine increased its toxic action over time, independent of the prevailing pH. All exposures caused slight to severe lipid peroxidation (LPO) in the phototrophs. Hence, one mechanism of growth inhibition may be oxidative stress-mediated reduction in photosynthesis. The presented results suggest that in successful field trials with leachate, the prevailing environmental conditions may inactivate polyphenols and xenobiotics other than polyphenols may be more effective.
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•Biochar pyrolysis generates condensed aromatic carbon structures.•Noncondensed carbon structures in biochar could be removed through bleaching.•Micropore formation is attributed to ...the formation of condensed structures.•Both micropore and condensed carbon contribute to the apparent sorption.•Aromatic carbons contribute more to the sorption than aliphatic carbon.
Biochar, a carbon-rich material, has attracted immense attention owing to its applications in soil remediation. However, the mechanisms by which heterogeneous carbon structures of biochars immobilize organic contaminants are not yet fully understood. In this study, the noncondensed aromatic components in biochars were selectively removed through bleaching. Different techniques, such as 13C nuclear magnetic resonance, were applied to characterize the biochar compositions, and thus the role of the different carbon structures in organic contaminant sorption was discussed. The aromatic carbon structures in biochars were gradually developed and evolved from noncondensed to condensed structure with increasing pyrolytic temperatures from 300 to 700 °C. Based on elemental analysis, the carbon removed by bleaching decreased from 43.9% to 5.92% with increasing temperatures. After the surface area normalization of the apparent sorption, bleaching increased the sorption of carbamazepine and bisphenol A on biochars produced at 500 °C, but not for those produced at 300 and 700 °C. Bleaching removed noncondensed aromatics and enriched condensed aromatics, which resulted in increased sorption. However, bleaching also resulted in the blockage of micropores in biochars with abundant condensed aromatics, causing decreased sorption. The apparent sorption was determined by the balancing of these two opposite effects.
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