Bioaccumulation, cytotoxicity and oxidative stress of the acute exposure selenium in Oreochromis mossambicus

Selenium Nanoparticles Act Potentially on the Growth Performance, Hemato-Biochemical Indices, Antioxidative, and Immune-Related Genes of European Seabass (Dicentrarchus labrax)

The current study investigated the role of selenium (Se) nanoparticles on the growth performance, hemato-biochemical indices, antioxidative, and immune-related genes of European seabass (Dicentrarchus labrax). Therefore, fish with initial weight of 20.53 ± 0.10 g/fish were fed diets with 0, 0.25, 0.5, and 1 mg Se nanoparticles/kg diet for 90 days. The final body weight, weight gain, and specific growth rate of fish fed dietary nano-Se varying levels were significantly higher than the control with the highest performances and lowest FCR in the group of fish fed nano-Se at 0.5 mg/kg. The values of Hb, PCV, RBCs, and WBCs were significantly higher in fish fed varying levels of Se nanoparticles than fish fed the basal diets. The values of total serum protein and globulin were significantly higher in fish fed varying levels of Se nanoparticles than fish fed the basal diets. Additionally, globulin had higher value in the group of fish fed 0.25 and 0.5 mg nano-Se/kg than fish fed 1 mg nano-Se/kg (P < 0.05). No significant alterations were observed on albumin, ALT, and AST variables (P > 0.05). Phagocytic index, phagocytic, lysozyme activities were significantly higher in fish fed varying levels of Se nanoparticles than fish fed the basal diets in a dose dependent manner (P < 0.05). Further, SOD activity had higher value in the group of fish fed 0.25 and 0.5 mg nano-Se/kg than fish fed 1 mg nano-Se/kg, whereas CAT was increased in the group of fish fed dietary 0.5 mg nano-Se/kg diet (P < 0.05). The level of MDA was significantly lowered by dietary nano-Se where the group of fish fed 0.25 mg/kg had the lowest level followed by those fed 0.5 and 1 mg/kg. The expression of GH, IGF-1, IL-8, and IL-1β genes had the highest mRNA levels in the group of fish fed 0.25 and 0.5 mg/kg followed by those fed 1 mg/kg, whereas HSP70 was downregulated. Based on the overall results, Se nanoparticles are recommended at the rate of 0.5-1 mg/kg diet to maintain the optimal growth performance, hemato-biochemical indices, antioxidative status, and immune-related genes in European seabass.

Transcriptome analysis reveals the importance of exogenous nutrition in regulating antioxidant defenses during the mouth-opening stage in oviparous fish

Antioxidant system is crucial for protecting against environmental oxidative stress in fish life cycle. Although the effects of starvation on the antioxidant defenses in several adult fish have been defined, no relevant researches have been reported in the larval stage, particularly during the transition from endogenous to exogenous feeding. To clarify the molecular response of antioxidant system that occurs during the mouth-opening stage under starvation stress and explore its association with energy metabolism, we employed RNA-seq to analyze the gene expression profiles in zebrafish larvae that received a delayed first feeding for 3 days. Our data showed that delayed feeding resulted in downregulation of 7078 genes and upregulation of 497 genes. These differentially expressed genes are mainly involved in growth regulation (i.e., DNA replication and cell cycle), energy metabolism (i.e., glycolysis/gluconeogenesis and fatty acid metabolism), and antioxidant defenses. We demonstrated that the starved larvae are in an extremely malnourished state in the absence of exogenous nutrition, and the consequence is that numerous antioxidant genes are downregulated. Meanwhile, the antioxidant defenses also respond negatively to oxidative stress. After nutritional supply, the expression of these inhibited antioxidant genes was restored. These results suggest that the establishment of antioxidant defenses during the mouth-opening stage depends highly on exogenous nutrition. Our findings would contribute to comprehending the nutritional stress and metabolic switches during the mouth-opening stage and are essential for reducing high mortality in commercial fish farming.

Selenium toxicity, bioaccumulation, and distribution in earthworms (Eisenia fetida) exposed to different substrates

Selenium (Se) is an essential microelement for human or animal health. At high concentrations, it can cause Se poisoning. Human activities (such as coal burning and mining) threaten soil biota by mobilizing high levels of Se. We used the earthworm Eisenia fetida as a bio-indicator of environmental pollutants to investigate Se acute toxicity, enrichment, and distribution through exposure tests using filter paper, artificial soil and cow manure. The 24 h- and 48 h-LC₅₀ for the filter paper contact test were 2.7 and 1.52 μg/cm². In artificial soil test, the 14 d-LC₅₀ and 14 d-biomass inhibition concentration (IC₂₀) were 63.86 and 59.81 mg/kg, respectively. The cow manure resulted in a 2.2- and 2.6-fold higher LC₅₀ and IC₂₀ than artificial soil results, respectively. Earthworms accumulated the largest Se load (89.47 mg/kg) in artificial soil containing 80 mg Se/kg and only accumulated 90.3 mg/kg in cow manure containing 160 mg Se/kg; 46.6-60.59% of the total Se was distributed in the tail of E. fetida. The Se enrichment rate (SER_Se) and bioaccumulation factor (BAF_Se) scored higher in artificial soil than in cow manure with the same Se concentration exposure, and the highest SER_Se was 6.21 and 6.31 mg Se/kg earthworm/d, respectively. The highest BAF_Se was 1.49 in artificial soil and 0.75 in cow manure. Our results demonstrate that selenite is more toxic to earthworms living in artificial soil than in cow manure. E. fetida possesses certain Se detoxification mechanisms by distributing Se in the tail.

Ecology of oxidative stress in the Danube barbel (Barbus balcanicus) from a winegrowing district: Effects of water parameters, trace and rare earth elements on biochemical biomarkers

Fish can be highly vulnerable to environmental pressures because they are exposed to oxidative stressors in the aquatic environment. Such stressors can affect the levels of antioxidant biomarkers against reactive oxygen species (ROS). With this study we investigated the oxidative stress ecology in Danube barbel (Barbus balcanicus) from the Barbucina creek (northeast Italy), a watercourse in the Collio winegrowing district. To do this, superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) activity was measured in gills, liver, and muscle, while metallothioneins (MT) and trace and rare earth elements (REEs) levels were determined in muscle. The effect of environmental factors (physicochemical parameters of water, trace elements and REEs) on oxidative stress biomarkers was thus assessed. High concentrations were determined for cerium (Ce), scandium (Sc), neodymium (Nd), lanthanum (La), yttrium (Y), and praseodymium (Pr) among the REEs. Among the trace elements, arsenic (As), copper (Cu), and mercury (Hg) levels were higher compared to published data, suggesting their role as stressors. The multiple linear regression (MLR) model showed a statistically significant association (R² = 0.858; F = 10.07; p = 0.015) between As, Cu, Hg, and Pr and SOD activity in the gills, indicating a functional relationship between them. Differently, CAT activity was significantly higher in the liver, probably in response to long-term Cu contamination of the watercourse. This was confirmed by the MLR model that showed a significant association (R² = 0.638; F = 8.152; p = 0.02) between the concentration of MT and of Cu. Our data show a biochemical defensive response by Danube barbel to the disturbances in the aquatic ecosystem of the Barbucina creek. These insights advance our understanding of the role and the effects of environmental factors as trace elements and REEs on oxidative stress in fish.

Effects of heavy metals speciations in sediments on their bioaccumulation in wild fish in rivers in Liuzhou-A typical karst catchment in southwest China

Although fish are widely confirmed to be susceptible to heavy metals (HMs) contamination in sediments, this bioconversion haven't been detailed. This is especially the case in karst areas, where HMs are less stably retained in the sediments and are more bioavailable. Therefore, we surveyed representative karst rivers in Liuzhou, China, in order to study the relationship between the speciations of seven HMs in the sediments with their bioaccumulation in wild fish. The results showed that the HMs in sediments are all below their permissible exposure limit (PEL), but Cd and Zn are significantly higher than soil basline. Most HMs are in residual fraction, while their exchangeable fractions are present in extremely low proportions. The concentration of Zn, Cr and Cd in some fish are above their maximum recommended limit (MRL). The concentrations of most of the HMs in the fish are significantly correlated with the levels in the sediments and given the higher correlation coefficients for their carbonate-bound phase, this phase can be seen to play a critical role in HMs bioconversion. However, the presence of this phase in low proportions enables other phases, especially oxidizable form, to play a greater role in HMs bioaccumulation. Apart from Do, HMs in the fish samples are significantly correlated with multiple environmental factors, demonstrating environmental fluctuations can manipulate HMs bioconversion from sediments; however, their significance depend heavily on the proportion of particular species. HMs in reducible and oxidizable fraction are more important in regulating, rather than promoting, their bioconversion during environmental fluctuations. Fluctuations in EC, TDS and pH can increase the impacts of HMs in carbonate-bound fraction on their bioconversion. Given the higher background values of EC and TDS and lower pH values during the monsoon period, careful attention should be paid to the increased bioconversion of HMs in karst rivers during this season.

Alteration of lipid metabolism, autophagy, apoptosis and immune response in the liver of common carp (Cyprinus carpio) after long-term exposure to bisphenol A

Bisphenol A (BPA), as a phenolic compound, is harmful to human health, and its residue in the aquatic environment also threatens the health of aquatic animals. In this research, the toxicity effects of BPA on liver tissues were evaluated in common carp (Cyprinus carpio) after long-term exposure. Fish were exposed to five concentrations of BPA (0, 0.01, 0.1, 0.5 and 2 mg/L) for 30 days. The blood and liver tissues were gathered to analyze biochemical indices and genes transcription levels. The data related to lipid metabolism showed that BPA exposure increased serum total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) levels, upregulated the expressions of fatp1, pparγ, fas, atgl, hsl, pparα, cpt1b, acox-1, and downregulated the expression of dgat1 in liver. Antioxidative parameters displayed a reduced antioxidant ability and increased lipid peroxidation after BPA exposure. Meanwhile, the upregulations of nrf2, ho-1, cyp1a and cyp1b genes revealed an adaptive response mechanism against oxidative stress-induced adverse effects. After 30 days of exposure, BPA induced apoptosis and endoplasmic reticulum stress (ERS) via upregulating the expression levels of apoptosis and ERS-related genes and increasing Ca²⁺ concentration in liver. Moreover, the downregulation of mtor and the upregulation of atg3, atg7, tfeb, uvrag and mcoln1 indicated that BPA could influence the normal process of autophagy. Furthermore, BPA exposure activated toll like receptors (TLRs) pathway to mediate the inflammatory response. Our results demonstrated that BPA exposure disturbed lipid metabolism, and induced oxidative stress, ERS, apoptosis, autophagy and inflammatory response in the liver of common carp. These findings contributed to the understanding of hepatotoxicity mechanism induced by BPA in fish.

Toxicity and bioaccumulation of manganese and chromium in different organs of common carp (Cyprinus carpio) fish

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Heavy metals effects fishes when its concentration arises from its normal.

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Bioaccumulation of manganese and chromium was studied in Cyprinus carpio on hematological and biochemical parameters.

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In organ, bioaccumulation is highest in the gills followed by intestine > muscles > skin > bones.

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It is concluded that heavy metal can readily bio accumulate in the organs of fish.

The present research work was carried out to determine the bioaccumulation of manganese and chromium in the gills, intestine, muscles, skin and bones, as well as its acute toxicity and effects on hematological and biochemical parameters in Common carp (Cyprinus carpio). Adult carps were exposed for 96 h to manganese sulphate and chromium chloride solution, a sub lethal concentration was used in the experiment. Bioaccumulation was highest in the gills followed by intestine > muscles > skin > bones. The concentration of hematocrit (HCT) (37.3 ± 0.36), hemoglobin (HGB) (9.0 ± 0.04), Red Blood Cells (RBCs) (3.7 ± 0.025), mean corpuscular volume (MCV) (121.2 ± 0.36), mean corpuscular hemoglobin (MCH) (41.3 ± 0.3) and mean corpuscular hemoglobin concentration (MCHC) (41.06 ± 0.072) was significantly higher at 96 h (P < 0.01) after exposure to manganese and chromium, while the concentration of platelets (PLT) (16.8 ± 0.12) and white blood cells (WBCs) (62.7 ± 0.11) was lower at 96 h of exposure. Serum glutamic pyruvic transaminase (SGPT) (40.6 ± 0.4), Blood Urea (13 ± 0.1), serum triglycerides (231.21 ± 0.04), high-density lipoprotein (HDL) (39 ± 0.07), serum Alkaline PO₄ (242 ± 0.2), lactate dehydrogenase (LDH) (1239 ± 13.21), and serum Uric Acid (4.81 ± 0.33) were significantly higher (P < 0.01) at 96 h of exposure. The highest concentration of serum cholesterol (339 ± 0.09), serum reatinine (0.9 ± 0.01), low density lipid (240 ± 0.2) was observed at 24 h. Serum glutamic-oxaloacetic transaminase (SGOT) (19 ± 0.13), and serum albumin were at the highest level at 72 h (3.19 ± 0.07) (P < 0.01) post exposure.

Effect of allicin on antioxidant defense system, and immune response after carbofuran exposure in Nile tilapia, Oreochromis niloticus

In this work, allicin was evaluated as an immunostimulant and antioxidant agent preventing Nile tilapia; Oreochromis niloticus against carbofuran toxicity. Fish (60 ± 8 g) were allocated to five groups; the first group (control), the second group was fed 1 g/kg allicin-supplemented diets without carbofuran intoxication, the third group exposed to 1/10 LC₅₀ carbofuran (0.246 mg/L). While the fourth, and fifth groups were fed allicin supplemented diet at concentration of 0.5 and 1 g/kg diet, respectively, and exposed to carbofuran at the same concentration similar to the one of the third group. After 30 days, fish exposed to carbofuran showed high ALT, AST, ALP, cholesterol, glucose, cortisol, uric acid, and creatinine levels. However, serum AChE, total proteins, immunoglobulins, and lysozyme activity were markedly (P ≤ 0.05) reduced in carbofuran exposed tilapia fish. Moreover, malondialdehyde (MDA) level was significantly increased in liver, and kidneys tissues of carbofuran exposed fish. Whereas, catalase (CAT) activity, superoxide dismutase (SOD), and total antioxidant capacity (TAC) were decreased (P ≤ 0.05) significantly in both liver, and kidneys tissues after exposure to carbofuran. Interestingly, tilapia fish treated with carbofuran (0.246 mg/L) and fed (0.5 and 1 g/kg diet) allicin in both the 4th & 5th groups, respectively, decreased serum biochemical parameters; and hepatorenal (MDA) levels, as well as increased AChE, immunological profile, and oxidative stress biomarkers. The results suggested that co- administration of allicin at the high dose is more capable of improving the biochemical, and immunological parameters, and tissue antioxidant responses of carbofuran treated fish.

Combined toxicity assessment of myclobutanil and thiamethoxam to zebrafish embryos employing multi-endpoints

It is necessary to understand the interactions between different pesticides in ecotoxicology because pesticides never appear as individual compounds but rather in combinations with other compounds. In this study, we planned to explicate the combined toxic effect of myclobutanil (MYC) and thiamethoxam (THI) on the zebrafish (Danio rerio) by adopting multiple biomarkers. Results unraveled that the 96-h LC₅₀ values of MYC to D. rerio at various life phases ranged from 5.2 to 10.3 mg L^-1, which were lower than those of THI ranging from 147 to 246 mg L^-1. Combinations of MYC and THI exhibited synergetic toxicity to zebrafish embryos. The activities of antioxidative enzymes (T-SOD, Cu/Zn-SOD and POD) and detoxification enzyme (GST) were obviously varied in most of the MYC, THI and combined exposures compared to the control. The mRNA expressions of eight genes (Cu-sod, cas3, il-8, cxcl, erα, crh, cyp17 and dio1) involved in antioxidation, apoptosis, immunity and endocrine were obviously altered in the combined exposure of MYC and THI compared to their individual exposures. Our findings hinted the threats when YMC and THI co-existed, which would be beneficial for the risk assessments of pesticide mixtures.

Effect of chrysophanic acid on immune response and immune genes transcriptomic profile in Catla catla against Aeromonas hydrophila

The effect of chrysophanic acid (CA) (2, 4, and 8 mg kg-1) on the immunity and immune-related gene profile of Catla catla against Aeromonas hydrophila is reported. In both control and treated groups fed with 2 mg kg-1 (2 CA), the phagocytosis, hemolytic, myeloperoxidase content, and superoxide anion production decreased significantly between 6th and 8th weeks, whereas when fed with 4 mg kg-1 CA (4 CA) the H2O2 production and nitric oxide synthase increased significantly between 4th and 8th week. When fed with 2 CA and 4 CA diets, the total protein, bactericidal, and antibody titer increased significantly from the 4th week onwards. When fed with 2 CA, the IL-1β and IL-10 mRNA expression of head kidney leucocytes were significant between weeks 6 and 8. The expressions of toll-like receptors significantly increased when fed with a 4 CA diet from 4th week onwards. The 4 CA group significantly increased in TNF-α, TNF receptor-associated factor 6 (NOD), which influences protein expression, after the 4th week. The mRNA transcription of MHCI, lysozyme-chicken and goose type expressions significantly increased in 4 CA group within the 4th week. In summary, the dietary administration of 4 mg kg-1 of CA (4 CA) provides better immunity and enhances the up-regulation of immune-related genes in Catla against A. hydrophila.

Selenium accumulation, speciation, and its effect on nutritive value of Flammulina velutipes (Golden needle mushroom)

Flammulina velutipes is one of the most popular edible mushrooms worldwide. A selenium-biofortification method for its fruiting body was developed using selenite. This study investigated the selenium content, distribution, speciation and the effect of selenium on mushroom growth, nutritive value, and mineral accumulation. Results showed that F. velutipes accumulated nearly 108 μg/g of organic selenium under treatment with 20 μg/g selenite, which accounts for over 97% of total selenium. Most (60-74%) of selenium combined with the protein fraction, whereas 15-21% combined with the polysaccharide fraction. Selenomethionine (56.8%), selenocysteine (22.8%), and methylselenocysteine (17.3%) were the main organic selenium compounds in the fruiting body. Selenium biofortification increased the biomass yield of fruiting body and elevated the content of polysaccharides, proteins, total amino acids, essential amino acids, and several minerals, including iron, calcium, and copper. F. velutipes might become a suitable selenium supplement.

Potential environmental toxicity of sewage effluent with pharmaceuticals

Sewage effluent effects on the biochemical parameters of Astyanax bimaculatus organs were investigateted. Treated sewage was collected in a treatment plant; 43 compounds, among them, pharmaceuticals and hormones, were investigated. Caffeine, ciprofloxacin, clindamycin, ofloxacin, oxytetracycline, paracetamol, sulfadiazine, sulfamethoxazole, sulfathiazole and tylosin waste was detected in the collected material. Fish were divided into four groups: control, TSE (treated sewage effluent), TSE + P (TSE with increased concentration of five pharmaceuticals) and PTSE (TSE + P post-treated with O₃/H₂O₂/UV). Biochemical parameters were evaluated in different organs after 14-day exposure. TBARS levels increased significantly in the brain of animals in the TSE and TSE + P groups in comparison to the control. There was significant reduction in TBARS levels recorded for the liver, muscle and gills of animals in the PTSE group in comparison to those of animals in the other groups. AChE activity reduced in the muscle of animals in the groups showing the highest pharmaceutical concentrations. CAT activity in the liver of animals in groups exposed to pharmaceutical effluent was inhibited. GST activity increased in brain of animals in the TSE + P and PTSE groups, whereas reduced levels of this activity were observed in liver of animals in the TSE group. Increased GST activity was observed in the brain of animals in TSE + P and PTSE groups. Based on integrated biomarker response values, the TSE + P group presented greater changes in the analyzed parameters. Results point out that pharmaceutical waste can cause oxidative stress, as well as affect biochemical and enzymatic parameters in Astyanax sp. Post-treatment can also reduce damages caused to fish, even in case of the likely formation of metabolites. Based on these results, these metabolites can be less toxic than the original compounds; however, they were not able to fully degrade the pharmaceutical waste found in the sewage, which can interfere in fish metabolism.

Combined effects of moderate hypoxia, pesticides and PCBs upon crucian carp fish, Carassius carassius, from a freshwater lake- in situ ecophysiological approach

Nowadays, depletion of oxygen or hypoxia has become a real concerning problem worldwide in freshwater, marine, and estuarine ecosystems and very often co-occurs with xenobiotics. Even though the acute and severe hypoxia is heavily studied in environment and laboratory studies, the in situ combined effects of these stressors on freshwater lake organisms are poorly understood. The current study sought to understand how the combined effects of moderate hypoxia, pesticides and PCBs affect the biochemistry, physiology and organ morphology of Carassius carassius, residing in the Lake Seferani, Dumrea region (Elbasan, Albania), a natural karst freshwater system declared as Nature Monument situated in central Albania. Crucian carp is used as a model organism, because of its residency and ecological relevance to the Lake, as well as for its amenability for the environmental toxicology studies. For this purpose, blood, liver and kidney samples of fish were processed for hematological, biochemical and histopathological analysis. We found a significant increase of blood glucose (GLU), cortisol levels, hematocrit (PCV) and hemoglobin (Hb) which clearly indicate the presence of stress in fish. Based on the histopathological evaluation and organ index results, liver and kidney organs displayed moderate-to-heavy histological-architecture changes. Our results provide a strong evidence that both, hypoxia and the presence of pesticides and PCB congeners found in Seferani Lake, put a heavy load on C. carassius energy metabolism and endocrine system, leading to an elevation of the biochemical and physiological parameters (hemoglobin level, hematocrit, glucose and cortisol), as well as the histopathological alterations. Additionally, in the presence of moderate hypoxia, the toxic effects of pesticides and PCBs on C. carassius are exacerbated. Further studies are needed to evaluate possible effects of pesticide and PCBs toxicity in human health, since crucian carp has an economic value for the population of the zone and it is used often as food sustenance. Elucidation of these kinds of responses can better improve our understanding of response of highly tolerant species, like Carassius carassius, to multiple stressors interactions, helping us to better predict and manage the consequences of the exposure of the freshwater biota to complex stressors in an environment that changes rapidly.

Amelioration of hexavalent chromium-induced bioaccumulation, oxidative stress, tight junction proteins and immune-related signaling factors by Allium mongolicum Regel flavonoids in Ctenopharyngodon idella

Chromium (Cr) is the most common heavy metal and that becomes toxic when present at higher concentrations in aquatic environments. Allium mongolicum Regel flavonoids (AMRF) has been documented to possess detoxification, antioxidant and anti-inflammatory properties. The aim of this study was to explore the potential of dietary AMRF and Cr exposure on bioaccumulation, oxidative stress, and immune response in Ctenopharyngodon idella. After acclimation, 360 fish were randomly distributed into six groups. The fish were fed with diets supplemented with Cr and/or AMRF for 4 weeks (28 days), the Cr concentrations were 0, 120, and 240 mg/kg and the concentrations of AMRF were 0 or 40 mg/kg, respectively. The results shown that Cr accumulation in the kidney, liver, spleen, intestine and gill were significantly increased following Cr exposure, dietary AMRF supplementation attenuated the increased in Cr accumulation. Dietary AMRF supplementation significantly reduced the levels of malondialdehyde (MDA) and protein carbonyl (PC) in liver, spleen and gill compared with the same Cr dose groups. When fish were supplemented with AMRF significantly increased lysozyme activity (LZM), complement 3 (C3) in kidney and intestine compared with the same Cr dose groups. Serum glutamic oxalate transaminase (GOT) and glutamic pyruvate transaminase (GPT) were significantly increased following exposure to Cr. Dietary AMRF supplementation significantly decreased GOT and GPT activity in the serum. In addition, AMRF supplementation can decrease the expression of inflammatory (NF-κB p65, TNF-α and IL-1β) and increased the expression of tight junction proteins (occludin and ZO-1) following Cr exposure in C. idella. These results indicate that AMRF has the potential to alleviate the effects of Cr toxicity in C. idella.

The adverse effects of selenomethionine on skeletal muscle, liver, and brain in the steelhead trout (Oncorhynchus mykiss)

Juvenile Oncorhynchus mykiss (average weight: 22.3 g) were fed one of five selenomethionine diets (1.09, 8.79, 15.37, 30.79, or 61.58 mg Se/kg diet). After 4 weeks, hepatic catalase activity over 15.37 mg Se/kg diets was significantly decreased, and the glutathione peroxidase activity over 30.79 mg Se/kg diets was elevated compared to the controls. In the brain, the dopamine levels at 61.58 mg Se/kg diet and the serotonin levels over 15.37 mg Se/kg diets were significantly increased, whereas the 3,4-dihydroxyphenylacetic acid, homovanillic acid, and dopamine turnover, and the 5-hydroxyindoleacetic acid and serotonin turnover over 30.79 mg Se/kg diets were decreased. In muscle, the 3-nitrotyrosine level over 15.37 mg Se/kg diets, acetylcholine esterase activity over 30.79 mg Se/kg diets, and histological alterations over 8.79 mg Se/kg diets were increased. Our current results showed that selenomethionine disrupted dopamine and serotonin metabolism in the brain and damaged the neuromuscular system in skeletal muscle.

Acanthocephalans parasites of two Characiformes fishes as bioindicators of cadmium contamination in two neotropical rivers in Brazil

Studies have demonstrated the role of acanthocephalan as environmental bioindicators. The dynamics in the parasite-host relationship that define the patterns of distribution of trace metals in parasites and, in its host, are extremely variable. In addition, the neotropical region, which is a major maintainer of the biodiversity of fish and parasites, remains little explored in this subject. Therefore, our objective was to analyze and compare the concentration of Cadmium (Cd) in the tissues of Prochilodus lineatus and Serrasalmus marginatus collected from Baía and Paraná rivers, as well as to assess the use of acanthocephalan as environmental bioindicators of pollution and their Cd bioaccumulation capacity. We collected 53 fish, 20 specimens of Prochilodus lineatus from Paraná River and 17 from Baía River, in addition to 16 specimens of Serrasalmus marginatus from Baía River, in September 2017 and March 2018. Tissues of the fish along with their parasites were subjected a Cd concentration analysis by Atomic Absorption Spectroscopy. The results revealed that the parasites had higher concentrations than all the tissues of S. marginatus, P. lineatus from Baía River and Paraná River. The high Cd concentrations in these parasites derived from their bioaccumulation capacity, because of the absorption of nutrients directly from the intestinal content of the fish through the tegument, as well as for the presence of Cd on the surface waters of Praná River floodplain. Besides that, the Coefficient of Spearman Rank Correlation showed that the infrapopulation size seems to affect Cd bioaccumulation in the parasites, smaller infrapopulations demonstrate a higher accumulation capacity compared to the larger ones. With that, we concluded that the two acanthocephalans species analyzed in this study have a good capacity for Cd accumulation, and can be used as accumulation indicators of trace-metal pollution. Accumulation indicators provide important information on the biological availability of pollutants.

How potential endocrine disruptor deltamethrin effects antioxidant enzyme levels and total antioxidant status on model organisms

Objective

Deltamethrin, synthetic pyrethroid, is a suspected endocrine disruptor contaminating ecosystems as toxic pollutant via agricultural activities and vector controls. The objective of the study is to determine the possible effects on human by evaluating antioxidant enzyme levels and total antioxidant status (TAS) of invertebrate model organism crayfish exposure to sublethal deltamethrin.

Materials and methods

Crayfish were exposed to 0.05 μg/L deltamethrin for 48 h and 7 days. Hemolymph samples were taken for TAS and total haemocyte counts (THCs). Gill, hepatopancreas and muscle tissues were examined for superoxide dismutase (SOD), glutathion peroxidase (GPx) and catalase (CAT) enzyme activities.

Results

THCs were decreased (p < 0.05) and hemolymph TAS levels were increased according to control groups. Gill SOD, CAT and GPx enzyme activities were significantly rised. Hepatopancreas SOD activities unchanged. Hepatopancreas CAT activities were increased significantly after 48 h (p < 0.05), but returned back to controls after 7 days. Hepatopancreas GPx and muscle SOD activities were rised (p < 0.05), while muscle CAT and GPx values did not affect from deltametrin.

Conclusion

Deterioration of ecosystems are directly affect the humans. The toxic effects of deltamethrin for different stages of organisms on the food web will provide basic data to understand and estimate the effects on the human beings.

Singular effects of Bacillus subtilis C-3102 or Saccharomyces cerevisiae type 1 on the growth, gut morphology, immunity, and stress resistance of red sea bream (Pagrus major)

The beneficial effects of Bacillus subtilis C-3102 and Saccharomyces cerevisiae type 1 were tested in red sea bream (Pagrus major) feeds. A basal diet (control) and two other diets were prepared by supplementation with B. subtilis C-3102 (PB) or S. cerevisiae type 1 (PY). After 60 days, both probiotic-supplemented groups exhibited significant enhancement in growth performance, the protein efficiency ratio (PER), and digestive enzyme secretion (protease and amylase) compared to the control group (P<0.05). The anterior, middle, and posterior parts of the intestines exhibited significantly increased values of intestinal fold height (hF), enterocyte height (hE), and microvillus height (hMV) in fish fed PB- or PY-supplemented diets (P<0.05). Serum peroxidase, anti-protease, and bactericidal activities were enhanced significantly in both probiotic-treated groups compared to the control group (P<0.05). Serum and mucus lysozyme activities improved significantly in the PB group compared to the control group (P<0.05). Catalase activity was also significantly decreased in both probiotic groups, with relatively lower activity observed in the PY group (P<0.05). Both probiotic groups showed increased tolerance considerably to freshwater exposure (P<0.05). In conclusion, B. subtilis C-3102 and S. cerevisiae type 1 can be used as functional probiotics to enhance the growth performance, digestion capacity, gut morphology, immune response, and stress resistance of the red sea bream with relatively higher efficiency by B. subtilis C-3102.

Effects of chronic exposure of waterborne copper on the antioxidant system and tissue accumulation in golden trout (Oncorhynchus mykiss aguabonita)

We assessed the acute and chronic effects of copper (Cu²⁺) on the antioxidant system in golden trout (Oncorhynchus mykiss aguabonita). The median lethal concentration after 96 h was determined as 0.24 mg L^-1. We then used 0.06 (L) and 0.12 mg L^-1 (H) Cu²⁺ to assess the responses of the antioxidant system to long-term exposure. The activities of superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase, glutathione reductase, reduced glutathione, and oxidized glutathione were measured in gill and liver tissue after 24 and 72 h and 7, 14, 21, and 28 days of exposure, as well as after 16 days of recovery in Cu²⁺-free water. Cu²⁺ accumulated to a greater extent in the liver than in the gill (0.61-0.75 mg kg^-1 vs. 24.0-69.9 mg kg^-1 in L group and 0.98-1.47 mg kg^-1 vs. 33.3-66.03 mg kg^-1 in H group). In the gill, we observed increases in the activities of superoxide dismutase, catalase, and glutathione peroxidase, as well as in the concentrations of reduced glutathione and oxidized glutathione. In the liver of L group, we observed increases in glutathione reductase activity and in the levels of reduced glutathione and oxidized glutathione. In L group, the activity of superoxide dismutase and reduced glutathione content increased after 24 h and then decreased over time, while catalase and glutathione reductase activity and oxidized glutathione levels increased. Data from the recovery period indicated that higher concentrations of Cu²⁺ may induce irreversible oxidative damage to the gill of golden trout.

Oxidative stress and antioxidant response in rainbow trout fry exposed to acute hypoxia is affected by selenium nutrition of parents and during first exogenous feeding

Selenium (Se) deficiency is a problem widely encountered in humans and terrestrial livestock production with increasing attention also in aquaculture. Se supports the antioxidant system, which becomes especially important during stressful conditions. In the present study, the effect of Se-supplementation in broodstock and fry diets on the performance and antioxidant metabolism of rainbow trout fry under acute hypoxia was investigated. Rainbow trout broodstock were fed plant-ingredient based diets either without any Se-supplementation (Se level: 0.3 mg/kg) or supplemented with Se supplied as sodium selenite or as hydroxy-selenomethionine (Se level: 0.6 mg/kg respectively) for 6 months prior to spawning. The progenies were subdivided into three triplicate feeding groups and fed diets with similar Se levels compared to the parental diets, resulting in a 3x3 factorial design. After 11 weeks of feeding, the fry were either sampled or subjected to a hypoxic stress challenge. One hundred fish were transferred to tanks containing water with a low oxygen level (1.7 ± 0.2 ppm) and monitored closely for 30 min. When a fish started to faint it was recorded and transferred back to normoxic water. Direct fry feeding of the hydroxy-selenomethionine supplemented diet improved the resistance towards the hypoxic stress. On the contrary, fry originating from parents fed Se-supplemented diets showed a lower stress resistance compared to fry originating from parents fed the control diet. Fry subjected to hypoxia showed elevated oxidative stress with reduced glutathione (GSH) levels and increased isoprostanes (IsoP) and phytoprostanes (PhytoP) levels produced by lipid peroxidation of polyunsaturated fatty acids (PUFA), arachidonic and α-linolenic acids respectively. Increased mRNA expression of transcription factors (nrf2, nfκb, keap1X2) and decreased mRNA expression of antioxidant enzymes (trxr, sod, gstπ) indicated a transcriptional regulation of the antioxidant response. In stressed fry, the mRNA expression of several antioxidant genes including gr, msr and gstπ was found to be higher when fed the control diet compared to the sodium selenite treatment, with a contrary effect for parental and direct Se nutrition on gpx. The long-term parental effect becomes of greater importance in stressed fry, where more than half of the genes were significantly higher expressed in the control compared to the selenite supplemented group.

Bioremediation of Aquaculture Wastewater with Algal-Bacterial Biofilm Combined with the Production of Selenium Rich Biofertilizer

The discharge of aquaculture wastewater and the excessive selenium in aquaculture effluent caused by selenium addition to aquatic feed are posing a serious risk for the marine environment. In this study, batch tests were carried out to investigate the feasibility of utilizing algal–bacterial biofilm for the treatment of selenium-rich aquaculture wastewater. The effects of four different types of commercial biofilm carriers on the attached growth of biofilms and the contaminant removal capacity were examined. The braided cotton biofilm carrier had the best performance on biofilm growth, while in an exponential growth period the dry weight density of the biofilm was above 2.0 g L−1. By utilizing the braided cotton carrier with a hydraulic retention time (HRT) of 6 days, the removal rate of N and P from the raw aquaculture wastewater was 88.5 ± 6.2% and 99.8 ± 0.2%, respectively. After that, the effects of different initial wastewater load ratios (IWLR) and HRT on the effluent quality of the treatment process were studied. The decrease in IWLR and the extension of HRT could improve the treatment performance. The effluent N, P and Se concentrations in the group with 50% IWLR and 6-day HRT were 0.75 ± 0.10 mg L−1, 0.015 ± 0.02 mg L−1, 35.2 ± 3.2 μg L−1, respectively, indicating an effective removal of the main contaminants. The algal–bacterial biofilm harvested from the batch test was rich in N, P and Se, where the Se content was 21.8 ± 3.4 mg kg−1, which has the potential to be used as an Se-rich biofertilizer.

Selenium accumulation in protein fractions of Tenebrio molitor larvae and the antioxidant and immunoregulatory activity of protein hydrolysates

Although numerous types of organisms have been used to enrich selenium, a low-cost and efficient organism is yet to be identified. This study aimed to develop a new means of selenium enrichment using Tenebrio molitor larvae. Our results indicated that the total selenium content in larvae was increased 83-fold to 54.21 ± 1.25 μg/g, and of this content, organic selenium accounted for over 97% after feeding the larvae with 20 μg/g of sodium selenite. Selenium was distributed unequally in the protein fraction with following order: alkali-soluble protein-bound selenium (36.32%) > salt-soluble protein-bound selenium (19.41%) > water-soluble protein-bound selenium (17.03%) > alcohol-soluble protein-bound selenium (3.21%). Additionally, 81% of the selenium within the soluble proteins was distributed in subunits possessing molecular weights of <40 kDa. After hydrolysis by alcalase, the protein hydrolysate of selenium-enriched larvae possessing 75% selenium recovery exhibited stronger antioxidant and immunoregulatory activities than those of regular larvae.

Synergistic Effects of Selenium Nanoparticles and Vitamin E on Growth, Immune-Related Gene Expression, and Regulation of Antioxidant Status of Nile Tilapia (Oreochromis niloticus)

The present study was conducted to investigate the effects of nano-selenium (Nano Se) or/and vitamin E (VE) on growth performance, blood health, intestinal histomorphology, oxidative status, and immune-related gene expression of Nile tilapia. Nano Se or/and VE at a rate of 0, 1 mg Nano Se/kg, 100 mg VE/kg, and 1 mg Nano Se/kg + 100 mg VE diet were fed to fish for 8 weeks. FBW was significantly (P < 0.05) increased in fish fed with Nano Se and VE, while fish fed with Nano Se or Nano Se and VE diets displayed significantly (P < 0.05) higher WG and SGR than the other groups. The lowest FCR was significantly (P < 0.05) detected in fish fed with Nano Se and VE, while the highest value was observed in fish VE diet. The intestinal morphometry (villi length and width) of fish fed with Nano Se or/and VE reported significantly (P < 0.05) the highest values with high number of goblet cells. Blood hematology and biochemistry parameters of fish fed with Nano Se or/and VE showed normal values with insignificant differences except for the blood total protein increased in fish fed with Nano Se or/and VE (P < 0.05). Dietary Nano Se or Nano Se and VE significantly (P < 0.05) increased the GPX, SOD, CAT, NBT, lysozyme, and phagocytosis values with decreased MDA. Liver and spleen TNF-α and IL-1β expressions were significantly (P < 0.05) upregulated in fish fed on Nano Se or Nano Se and VE. Thus, Nano Se or/and VE can be used effectively in tilapia diets for improving the growth, intestinal health, blood health, oxidative status, and immune-related gene expression.

Enhancement of a constructed wetland water treatment system for selenium removal

Selenium (Se) is essential to most animals, whereas the gap between necessity and toxicity is narrow. Our previous work showed constructed wetlands were a promising solution to Se contamination in aquatic habitats. This study further examined effects of organic amendments and hydrologic regimes on Se removal by constructed wetlands. Our results suggest the removal efficiency exceeded 94% within 8 days for the systems with moderate and low organic carbon contents in the substrate, as a 98% removal of Se was obtained in three weeks for the system subjected to the 2-day wet/dry cycle. To mimic field wetlands, a litter layer was added to the cattail treatment system, which reduced waterborne Se much more rapidly than control, achieving a 77% removal of Se within 4 days. XAS results show all sediment Se was transformed to Se⁰ in the presence of litter, as SeMet (47%) dominated the Se adsorbed by the litter. The findings indicate the Se removal capacity of a constructed wetland would improve over time, especially via Se volatilization into the atmosphere and Se stabilization in the sediment with litter accumulating at the surface. Another mesocosm experiment showed the cattail floating system effectively removed Se, particularly selenate, by 99% in 48 h. To confirm that high performance, seven constructed wetland types were set up for comparison. The results show the cattail floating system was most effective in Se removal (93-100% at around 35 °C in summer and 51-100% at about 5 °C in winter). More research is needed to test the floating system under more field conditions and investigate the biomagnification and biotransformation of the removed Se along food chains. Seven constructed wetland types were set up for comparison.

In situ experiment to evaluate biochemical responses in the freshwater mussel Diplodon chilensis under anthropogenic eutrophication conditions

An in-situ experiment was performed to study metabolic responses of the freshwater mussel Diplodon chilensis to water contaminated by leachates from an open dump and cattle activity, in order to analyze both the effects of those contaminants on aquatic environments and the potential use of a native bivalve to evaluate the effects of anthropic influence and eutrophication. Bivalves from a reference site were cage-transplanted to a control site (site A) and to a temporal water pond (site B) over 30 and 60 periods. Water quality analyses revealed that the site B was affected by anthropogenic influence. Mussel's hemocytes from site B showed 50% lower reactive oxygen species production and 130% higher lysosomal membrane stability in the site B mussels. In addition, no oxidative stress was evident in gills, despite the elevated copper and iron concentrations recorded in the site B water samples (Cu_B = 0.3350 ± 0.0636 mg. L^-1vs. Cu_A = 0.0045 ± 0.0007 mg. L^-1; Fe_B = 3.8650 ± 0.4031 mg. L^-1vs. Fe_A = 0.0365 ± 0.0049 mg. L^-1). In contrast, the adductor muscle accumulated more Fe (~10-20-fold) than the gills and showed signs of oxidative stress, e.g. superoxide dismutase activity and TBARS levels were increased by 10% were 34%, respectively, in the site B compared with the site A after 60 days of exposure. Additionally, the adductor muscle showed signs of anaerobic metabolism activation. Cu is accumulated in gills from both sites' individuals, at 60 days, in concordance with the increase in the activity of the cu-containing enzyme cytochrome-c-oxidase. There was a reduction in the overall condition and digestive gland index in bivalves exposed at site B, associated with diminished levels of lipid and protein contents. Metal-pollution and eutrophication affects D. chilensis metabolism and is associated to tissue-specific exposure, anaerobic metabolism and general energetic condition depletion.

Effects of fucoidan on the hematic indicators and antioxidative responses of Nile tilapia (Oreochromis niloticus) fed diets contaminated with aflatoxin B1

Fucoidan is a rich source of medicinally active immunostimulants that possess various pharmacological properties. This study examined the potential impact of fucoidan on the hematic indicators and antioxidative responses of Nile tilapia fed diets contaminated with aflatoxin B₁ (AFB₁). Fish (60 ± 6.1 g) were allocated to five groups; the first (control) and second groups were fed 0% or 1% fucoidan-supplemented diets without AFB₁ contamination, while the third, fourth, and fifth groups were fed diets contaminated with AFB₁ and supplemented with 0%, 0.5%, and 1% fucoidan, respectively. After 30 days, fish fed AFB₁ showed high ALT, AST, ALP, cholesterol, urea, and creatinine levels; furthermore, total blood protein and tissue (liver, kidney, and gill) glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) activity significantly (P ≤ 0.05) decreased in fish fed AFB₁, while tissue malondialdehyde significantly increased (P ≤ 0.05). Interestingly, fish fed fucoidan showed decreased ALT, AST, ALP, cholesterol, urea, and creatinine, as well as increased blood protein, GSH, GPx, SOD, and CAT activity. The results suggested that fucoidan is capable of inducing protective activity against AFB₁ toxicity in Nile tilapia by enhancing the serum biochemical and tissue antioxidant responses of fish.

Prevalence and distribution analysis of antibiotic resistance genes in a large-scale aquaculture environment

This study examined the profiles of antibiotic resistance genes (ARGs) in water and sediments from one large-scale freshwater pond farming system. A qPCR array was used to quantify ARGs (16S, Tetx, Tetw, TetG, Intll, and Sull) and microbial community structure was analyzed by 16S rRNA gene sequencing. A large number of ARGs (2 8 8) were detected. The ARG richness of the sediments was significantly higher than that of water and an average of 15 more genes were detected (p < 0.01). Sediment samples showed significantly higher taxonomic diversity and higher abundance of Gammaproteobacteria, Betaproteobacteria, and Flavobacteria. A significant correlation was observed between antibiotic resistance genes and breeding periods. The taxonomic diversity of the samples in ponds was significantly higher than that in ditch samples (p < 0.05), suggesting that pond farming systems could act as a local reservoir to spread ARGs into aquatic environments of rural communities.

Effect of sub-chronic exposure to selenium and astaxanthin on Channa argus: Bioaccumulation, oxidative stress and inflammatory response

Selenium (Se) is the most common micronutrient and that becomes toxic when present at higher concentrations in aquatic environments. Astaxanthin (AST) has been documented to possess antioxidant and anti-inflammatory properties. The aim of this study was to explore the potential of dietary AST and Se exposure on oxidative stress, and inflammatory response in Channa argus. After acclimation, 540 fish were randomly distributed into nine groups housed in twenty-seven glass tanks. The fish were exposed for 8 weeks to waterborne Se at 0, 100 and 200 μg L^-1 or dietary AST at 0, 50 and 100 mg kg^-1. The results shown that Se accumulation in the kidney, liver, spleen, intestine and gill were significantly increased following Se exposure, dietary 50 and 100 mg kg^-1 AST supplementation decreased the accumulation of Se in the kidney, liver, spleen, and intestine. In addition, AST supplementation can decrease oxidative stress and inflammatory response in the liver and spleen following exposure to waterborne Se. These results indicate that AST has the potential to alleviate the effects of Se toxicity in C. argus.

Evaluation of softwood and hardwood sawmill wastes impact on the common carp "Cyprinus carpio" and its aquatic environment: An oxidative stress study

The aquatic pollution due to sawmill wood wastes constitutes a major threat to hydro-chemical and fauna characteristics of the aquatic ecosystems. When this kind of organics wastes enter aquatic environment it can be taken up by aquatic organisms through respiration and/or through their diet. This could concurrently result in oxidative stress and later having adverse effect on physiological and biochemical function. The importance of fish in the society cannot be over emphasized, hence there is the need to know the influence of sawmill wood wastes on the water quality and fish. Therefore, this work aims to study the impact of five species of wood wastes on a type of fish named common carp (Cyprinus carpio) known as the most widely cultured fish species in the world and on its aquatic environment. The monitoring of water parameters showed deterioration in water quality. The activities of superoxide dismutase (SOD), Catalase (CAT), glutathione peroxidase (GPx) and lipid peroxidation (MDA) were investigated to evaluate the degree of oxidative stress. According to t-student, there was a significant difference compared to control (P < 0.05) in the level of SOD, CAT, GPx and MDA activities in fish exposed to 5 g·l^-1 of each sawdust except for GPx, a non-significant difference (p > 0.05) was noted in the case of Beech and Dibetou. When the dispersed amount was about 0.375 g·l^-1 we noted a significant difference in the level of SOD and GPx, except for GPx a non-significant difference was detected in the case of Cedar. The level of CAT was significantly difference just in the case of Cedar and Dibetou and that of MDA was significantly difference just in the case of Beech and Mahogany. We conclude therefore that sawmill wood waste not only impact the water quality adversely but also alters the levels of different enzymes activities in Cyprinus Carpio fish by the inhibition of SOD, CAT and GPx activities and by the production of MDA, which reflects response to oxidative stress. This study provides a rational use of these enzymes as suitable biomarkers with different degrees of specificity and as important tool for environmental monitoring.

The effect of foodborne sertraline on rainbow trout (Oncorhynchus mykiss)

The worldwide consumption of antidepressants is raising as well as their concentrations in the aquatic environment. This increases the risk of food chain contamination and bioaccumulation in aquatic biota. The aim of this study was to describe a potential risk of sertraline as a pollutant from water environment, wherein rainbow trout (Oncorhynchus mykiss) has been chosen as the test organism, because predatory fish are on the top of the food chain in the aquatic environment. The effects of foodborne sertraline were tested on rainbow trout during a 28-day toxicity test according to OECD 215 method. Sertraline was incorporated in commercial feed at a dose of 4.4 µg/kg (environmental concentration), 42 µg/kg and 400 µg/kg. The results confirmed that sertraline has a significant effect on fish behaviour, resulting in suppression of the escape reflex and increased resistance to stress. Moreover, increased Fultońs condition factor was found in fish fed with the highest concentration of sertraline. Haematological analysis revealed a statistically significant increase in the number of neutrophilic bands and neutrophil/lymphocyte ratio, and decreased number of lymphocytes. The results of biochemical examination showed a statistically significant decrease in ammonia and lactate concentrations and histological examination revealed changes in gills and caudal kidney. Although sertraline reduces stress in fish, the decline in nonspecific immunity is a risk to fish population stability.

Lactobacillus plantarum L-137 and/or β-glucan impacted the histopathological, antioxidant, immune-related genes and resistance of Nile tilapia (Oreochromis niloticus) against Aeromonas hydrophila

A trial was operated to assess the potential of using Lactobacillus plantarum L-137 (L-137) and/or β-glucan (BG) in improving the resistance of Nile tilapia against Aeromonas hydrophila. Control diet and 3 diets supplemented with L-137, BG or L-137 + BG were prepared. Final body weight, specific growth rate, superoxide dismutase, and catalase showed considerably (P < .05) increased values in L-137 or L-137/BG groups, while glutathione peroxidase increased significantly (P < .05) only in L-137/BG group. Fish fed L-137 and/or BG diets showed that feed conversion ratio and malonaldehyde levels were significantly decreased (P < .05). Also, both L-137 and BG helped Nile tilapia to have high phagocytosis activity and relative expression of tumor necrosis factor-alpha (TNF-α) and interleukin 1 beta (IL-1β) and interferon-gamma (INF-γ) genes. After A. hydrophila challenge, the intestinal villi epithelium of the L-137/BG group was intact and denser than the other groups. The hepatopancreas and spleen of the control group displayed severe necrosis in hepatocytes and congestion of blood sinusoids in addition to diffuse vacuolation. Regarding the L-137, BG and L-137/BG groups, there was a moderate and normal degree of vacuolation with focal necrosis and mild to moderate degree of congestion of blood sinusoids. Red blood cells, hemoglobin, and albumin showed meaningfully (P < .05) increased values in L-137 or L-137/BG groups. TNF-α, IL-1β, and INF-γ expressions were upregulated by L-137 and/or BG. The obtained results revealed the ability of L-137 and/or BG to protect Nile tilapia from the effects of A. hydrophila infection by the motivation of the immune, antioxidative, and antiinflammation responses.

Effects of chlorothalonil on the antioxidant defense system of mussels Perna perna

Chlorothalonil is an effective fungicide used in agriculture and formulations of antifouling paints, which use and possible toxicity has been generating great concern. Thus, the present study investigated the effects of chlorothalonil on the antioxidant defense system (ADS) of the mussel Perna perna. The ADS was evaluated in gills and digestive gland after 24 h and 96 h of exposure to environmental relevant levels of chlorothalonil (0.1 and 10 μg/L). The activity of the enzymes superoxide dismutase (SOD), catalase (CAT), glutamate cysteine-ligase (GCL) and glutathione S-transferase (GST), levels of non-enzymatic defenses, represented by glutathione (GSH), and lipoperoxidation (LPO) and protein carbonyls (PCO) were evaluated. Results indicated that exposure to chlorothalonil is affecting the ADS in both tissues. While the activity of SOD increased and GST and GSH were not altered in gills, they decreased in digestive gland after 24 h of exposure to 10 μg/L of chlorothalonil. The contrasting results indicate that gills and digestive gland presented different patterns of responses after exposure to chlorothalonil. Moreover, a tissue-specific response to chlorothalonil was observed. Gills could be acting as the first line of defense, presenting higher enzymatic levels with minor effects on the parameters analyzed. On the other hand, digestive gland, with lower levels of antioxidant defenses, was the most affect organ by chlorothalonil. It also should be highlighted that the fungicide reduced the glutathione metabolism in the digestive gland, which can lead to an imbalance of the redox state within the cells of animals.

The potential role of nano-selenium and vitamin C on the performances of Nile tilapia (Oreochromis niloticus)

Functional trace elements and vitamins can boost immunity and antioxidative response in aquatic animals without creating environmental hazards. While nano-selenium (Nano-Se) and vitamin C (VC) have been used as immunomodulators and antioxidants in animal and poultry feed, there is little data on Nano-Se and/or VC supplementation in aquatic animals. Thus, the current study evaluated the impact of adding Nano-Se and VC to the diets of Nile tilapia for 8 weeks. Four diets were formulated and offered to the fish: no supplementation (control), 1 mg Nano-Se/kg, 500 mg VC/kg, and 1 mg Nano-Se + 500 mg VC/kg of food. Growth-related parameters (final body weight, weight gain, and specific growth rate) were significantly increased in tilapia fed Nano-Se and VC, with a reduced feed conversion ratio (P < 0.05). Intestinal villus length and width as well as the number of goblet cells were increased in tilapia fed Nano-Se and/or VC (P < 0.05). Additionally, dietary Nano-Se and/or VC significantly increased nitro-blue tetrazolium (NBT) level, superoxide dismutase, glutathione peroxidase, catalase, the phagocytic index, and lysozyme and phagocytic activities (P < 0.05). However, significantly reduced levels of malonaldehyde were observed in fish fed Nano-Se and/or VC (P < 0.05). TNF-α and IL-1β gene expressions in the liver and spleen of the fish were significantly upregulated by Nano-Se and/or VC (P < 0.05). The results revealed the potential role of Nano-Se and/or VC in enhancing growth, intestinal morphometry, and immune and antioxidative responses in Nile tilapia.

Immunotoxicity of microplastics and two persistent organic pollutants alone or in combination to a bivalve species

Both microplastics and persistent organic pollutants (POPs) are ubiquitously present in natural water environment, posing a potential threat to aquatic organisms. While it has been suggested that the immune responses of aquatic organisms could be hampered by exposure to microplastics and POPs, the synergistic immunotoxic impact of these two types of pollutants remain poorly understood. In addition, little is known about the mechanism behind the immunotoxic effect of microplastics. Therefore, in the present study, the immunotoxicity of microplastics and two POPs, benzo[a]pyrene (B[a]P) and 17β-estradiol (E2), were investigated alone or in combination in a bivalve species, Tegillarca granosa. Evident immunotoxicity, as indicated by alterations of haemocyte count, blood cell composition, phagocytic activity, intracellular content of ROS, concentration of Ca²⁺ and lysozyme, and lysozyme activity, was revealed for both microplastics and the two POPs examined. In addition, the expression of six immune-, Ca²⁺ signalling-, and apoptosis-related genes was significantly altered by exposure of clams to the contaminants studied. Furthermore, the toxicity of POPs was generally aggravated by smaller microplastics (500 nm) and mitigated by larger ones (30 μm). This size dependent effect on POP toxicity may result from size dependent interactions between microplastics and POPs. Data obtained in this study also indicate that similar to exposure to B[a]P and E2, exposure to microplastics may hamper the immune responses of clams through a series of interdependent physiological and molecular processes.

Seasonal variations in antibiotic resistance genes in estuarine sediments and the driving mechanisms

Estuary sediments are chemically contaminated by adjacent coastal industrial cities, but the impact of organic pollutants on antibiotic resistance genes (ARGs) in estuarine sediments is unknown. We comprehensively analyzed the complex interactions between chemical pollutants (heavy metals and organic pollutants), mobile genetic elements (MGEs), and ARGs in estuarine sediments during various seasons. The results indicate that under the effects of the chemically polluted river water, the number of different estuarine sediment ARGs increased by 76.9%-92.3% in summer and 5.9%-35.3% in winter, and the abundance of these ARGs increased by 29-5195 times in summer and 48-239 times in winter. The abundance of sediment ARGs in distinct estuaries showed different seasonal trends. Seasonal changes had a greater impact on the abundance of estuarine sediment ARGs than on their diversity. The diversity of estuarine sediment ARGs was positively correlated with the chemical pollution levels. Furthermore, chemical pollution was positively correlated with MGEs, and MGEs were correlated with ARG abundance. These results indicate that ARGs are enriched in bacteria via horizontal gene transfer triggered by chemical pollution, promoting multi-antibiotic resistance in estuarine sediment bacteria. These findings have implications for our understanding of the distribution and propagation of ARGs in chemically polluted estuarine sediments.

Ameliorative effects of Lactobacillus plantarum L-137 on Nile tilapia (Oreochromis niloticus) exposed to deltamethrin toxicity in rearing water

Deltamethrin (DLM) is a synthetic pyrethroid used for agricultural purposes to control insects and has been found to pollute the aquatic environment and leads to serious health problems. Lactobacillus plantaruml-137 (L-137) has gained more popularity as functional supplement for its immunomodulatory effects and antioxidant potential. This study was designed to examine the potential of l-137 on liver function, histopathology, immune and antioxidant related gene expressions in Nile tilapia exposed to subacute DLM for 30 days. Fish (mean weight of 28.18 ± 1.34 g) was distributed into four groups (triplicates): the first and second groups fed the control diet, while the third and fourth groups fed l-137 at 50 mg/kg and the second and fourth groups were exposed to DLM (15 μg/L) in rearing water (control, DLM, l-137 and DLM + L-137, respectively). DLM-treated fish groups showed a significant increase in blood biochemical parameters (creatinine, urea and bilirubin) as well as hepatic enzymes (ALP, AST and ALT) (P < 0.05). Blood total protein, globulin, albumin, WBCs, RBCs, Hb, phagocytic index, phagocytic and lysozyme activities were significantly decreased in fish exposed to DLM (P < 0.05). Additionally, DLM toxicity downregulated the transcription of immune genes (IL-1β and IL-8), while upregulated the stress related genes (HSP70 and CASP3). The histopathological images of Nile tilapia exposed to DLM revealed damage in gills, intestine, spleen and liver which confirmed the toxic effects. Conversely, l-137 presented protective effects and restored the aforementioned parameters when fish exposed to DLM and fed l-137. Further, l-137 restored the antioxidative capacity (CAT and GPx). Thus, l-137 supplementation exhibited defensive effects against DLM toxicity in Nile tilapia through improving blood biochemical responses, immune, and antioxidant related gene expressions as well as histopathological effects.

Subchronic effects of dietary selenium yeast and selenite on growth performance and the immune and antioxidant systems in Nile tilapia Oreochromis niloticus

Selenium is an essential element but toxic at high levels in animals. The effects of Se on growth performance and the immune system in Nile tilapia remain inconclusive. In this study, Nile tilapia Oreochromis niloticus was fed on selenium yeast (Se(Y))- and selenite (Se(IV))-enriched feed at 0, 3, 6, and 12 μg/g (dry wt) for 45 and 90 d. The growth, bioaccumulation, biochemical markers related to antioxidant, immunological, nervous and digestive systems were evaluated in various fish tissues (liver, intestine, kidney, muscle, brain, spleen, gills). The results showed that the accumulation of Se(Y) was 1.3-2 folds of Se(IV) in most tissues. The growth of tilapia was enhanced by both Se(Y) and Se(IV) at 3 μg/g after 90 d, with Se(Y) better than Se(IV) in tilapia feed. After 45 d, the levels of lipid peroxidation, the activity of the antioxidant enzymes, and the transcriptional levels of the immune related genes (IL-1β, IFN-γ and TNF-α) and stress proteins (HSP70 and MT) were enhanced in all treatments, except that of MT in the 12 μg/g Se(Y) group. In addition, both Se species inhibited the activity of acetylcholinesterase (AChE) in the brain and one digestive enzyme α-glucosidase (α-Glu) in the intestine at 12 μg/g. However, after 90 d, the effects on most biochemical markers were less pronounced, implying a possible acclimation after prolonged duration. The results demonstrate Se is beneficial to O. niloticus at low levels and toxic at elevated levels. The immunostimulation by Se might be greatly weakened after long term feeding Se-enriched feed. This study helps to better understand the effects of Se on the antioxidant and immune systems and to establish the optimal Se levels in the feed and duration for O. niloticus.

Changes of enzyme activity and gene expression in embryonic zebrafish co-exposed to beta-cypermethrin and thiacloprid

Pesticides often occur as mixtures of complex compounds in water environments, while most of studies only focus on the toxic effects of individual pesticides with little attention to the joint toxic effects. In the present study, we aimed to the mixture toxicity of beta-cypermethrin (BCY) and thiacloprid (THI) to zebrafish (Danio rerio) employing multiple toxicological endpoints. Results displayed that the 96-h LC₅₀ values of BCY to D. rerio at various developmental stages ranged from 2.64 × 10 (1.97 × 10-3.37 × 10) to 6.03 × 10³ (4.54 × 10³-1.05 × 10⁴) nM, which were lower than those of THI ranging from 2.97 × 10⁴ (1.96 × 10⁴-4.25 × 10⁴) to 2.86 × 10⁵ (2.19 × 10⁵-5.87 × 10⁵) nM. Mixtures of BCY and THI exhibited synergistic response in embryonic zebrafish. Meanwhile, the enzyme activities of antioxidants (CAT and SOD) and detoxification enzyme (CarE), endogenous T-GSH and MDA contents, as well as gene expressions (tsh, crh, cxcl and bax) involved in oxidative stress, cellular apoptosis, immune system and endocrine system were obviously changed in the mixture exposure compared with the respective BCY or THI treatment. Consequently, the increased toxicity of pesticide mixture suggested that the toxicological data acquired from individual pesticide tests might underrate the toxicity risk of pesticides that actually arise in the real environment. Taken together, our present study provided evidence that mixture exposure of BCY and THI could induce additional toxic effect compared with their respective individual pesticides on D. rerio, offering valuable insights into the toxic mechanism of pesticide mixture.

Microbial community successional patterns in offshore sediments impacted by chemical pollution from Taizhou and Xiamen Cities in China

An Illumina-based next-generation sequencing was employed to characterise the sediment microbiome adjacent to coastal industrial and tourist cities, Taizhou and Xiamen, in China, and their associations with chemical pollution were explored. The results indicated that chemical pollution of sediments from Taizhou was higher than that from Xiamen. The number of sediment bacterial genera was negatively (Taizhou) or positively (Xiamen) correlated with offshore distance, owing to shifts in the primary and secondary status of organic matter and chemical pollutants for the promotion or inhibition of the sediment microbiome. The total number of the operational taxonomic units (OTUs) in sediments from Taizhou was larger than from Xiamen, while the number of core OTUs was smaller indicating that Taizhou had more impact on core microbes in sediments than Xiamen. This study suggests that chemical pollutants and organic matter result in different co-regulation of the off-shore sediment microbiome of coastal industrial and tourist cities.

Perkinsus mediterraneus infection induces oxidative stress in the mollusc Mimachlamys varia

Perkinsus mediterraneus is a protozoan parasite that can cause marine mollusc diseases known as perkinsosis being a serious threat for clam cultures worldwide. The aim of the present study was first to determine the Perkinsus species infecting the variegated scallop Mimachlamys varia and then to evaluate the existence of oxidative stress in gills of M. varia according to different degrees of infection. DNA sequencing confirmed that P. mediterraneus was the species infecting M. varia. ROS production was progressively increasing with the degree of infection although the differences were only significant in the high-infected group. Low degree of infection significantly increased superoxide dismutase (SOD) and glutathione S-transferase (GST) activities and nitrite levels with respect to the control group. In the high-infected group, a significant increase was evidenced in all analysed enzymes, catalase, SOD, glutathione reductase and GST. Non-significant differences in MDA levels were observed between the control and low-infected groups; however, a significant increase in MDA levels was observed in the high-infected group. In conclusion, the infection by Perkinsus mediterraneus in M. varia induces oxidative stress and an antioxidant response directly related to the infection degree that can contribute to the pathogenicity of the infection.

The effect of the antidepressant venlafaxine on gene expression of biotransformation enzymes in zebrafish (Danio rerio) embryos

The effect of venlafaxine, a pharmaceutical commonly found in aquatic environment, was analyzed on non-target organism, Danio rerio (Hamilton, 1822). D. rerio embryos were treated by two different concentrations of venlafaxine: either concentration relevant in aquatic environment (0.3 μg/L) or concentration that was two orders of magnitude higher (30 μg/L) for the evaluation of dose-dependent effect. Time-dependent effect was rated at 24, 96, and 144 h post-fertilization (hpf). For gene expression, genes representing one of the phases of xenobiotic biotransformation (0 to III) were selected. The results of this study showed that the effect of venlafaxine on the zebrafish embryos is the most evident at hatching (96 hpf). At this time, the results showed a downregulation of gene expression in each phase of biotransformation and in both tested concentrations. In contrast, an upregulation of most of the genes was observed 144 hpf for both tested venlafaxine concentrations. The study shows that venlafaxine can affect the gene expression of biotransformation enzymes in D. rerio embryos even in the environmentally relevant concentration and thus disrupt the process of biotransformation. Moreover, the pxr regulation of genes seems to be disrupted after venlafaxine exposure in dose- and time-dependent manner.

Inhibitory effect of metals on animal and plant glutathione transferases

Glutathione transferases (GSTs) represent a widespread enzyme superfamily in eukaryotes and prokaryotes catalyzing different reactions with endogenous and xenobiotic substrates such as organic pollutants. The latter are often found together with metal contamination in the environment. Besides performing of essential functions, GSTs protect cells by conjugation of glutathione with various reactive electrophiles. The interference of toxic metals with this functionality of GSTs may have unpredictable toxicological consequences for the organisms. In this review results from the recent literature are summarized and discussed describing the ability of metals to inhibit intracellular detoxification processes in animals and plants.

Evaluation of single and combined effects of cadmium and micro-plastic particles on biochemical and immunological parameters of common carp (Cyprinus carpio)

The growing accumulation of microplastics (MPs) in aquatic environments is a global concern. MPs are capable to interact with other environmental contaminants, including heavy metals, altering their toxicity. The aim of the study was to investigate the sub-lethal effects of cadmium chloride (Cd) alone and in combination with MPs on common carp (Cyprinus carpio). Multi-biomarkers, including plasma biochemical parameters and intrinsic immunological factors, were measured after 30 days of exposure. Exposure to Cd or NPs reduced the plasma activities of acetylcholinesterase (AChE) and gamma-glutamyl-transferase (GGT) and increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and alkaline phosphatase (ALP). Exposure to both compounds enhanced the observed effects except for AST activity and ALP at the highest concentrations, whereas evidenced an antagonistic interaction in ALT. Plasma total protein, albumin, and globulin levels were decreased, and the levels of glucose, triglyceride, and cholesterol levels increased mainly in the Cd groups with no additional effects derived from the co-exposure to both stressors. Lysozyme and alternative complement (ACH50) activities and the levels of total immunoglobulins, and complement C3 and C4 in fish exposed to Cd and MPs were lower than those in the control group and this decrease was more significant by the mixture of both compounds. These findings showed that the exposure to Cd or MPs alone is toxic to fish altering the biochemical and immunological parameters. Moreover, these alterations are even greater when the Cd and the MPS are combined suggesting synergistic effects in increasing Cd toxicity and vice versa.

Study the immunomodulation of anthracenedione in striped dwarf catfish, Mystus vittatus against pathogenic bacteria, Aeromonas hydrophila

Anthracenedione is a derivative of anthraquinone aromatic organic natural pigments found in senna, aloe latex, rhubarb, cascara, lichens, and fungi having broad range of bioactivity, including anti-cancer, anti-inflammatory, anti-microbial, anti-fungal, anti-oxidant, anti-viral activities suggesting potential for clinical purpose of many diseases. The effect of anthracenedione enriched diet on growth, hematology, innate and adaptive immune parameters as well as protection from Aeromonas hydrophila in Mystus vittatus was reported. The weight gain, feed intake, specific growth rate (SGR), and feed conversion ratio (FCR) were significantly increased in uninfected groups fed with 5 mg kg^-1 diet. The red blood cells (RBC) and white blood cells (WBC) count and the percentage of lymphocytes were significantly augmented in both infected and uninfected groups feeding with any diet. The percentage of monocytes, eosinophils, neutrophils and the biochemical profile such as total protein, albumin, and globulin also were significantly increased in the infected and uninfected groups fed with 5 mg kg^-1 enriched diet. The innate and adaptive immune parameters such as phagocytic activity, immunoglobulin M (IgM), respiratory burst activity, complement activity, and lysozyme activity were significantly increased in uninfected and infected groups fed with 5 or 10 mg kg^-1 diets but not with 1 mg kg^-1 diet. The serum superoxide dismutase (SOD) activity is significantly increased in the uninfected and infected fish fed with 5 mg kg^-1 diet but the increase was not significantly observed in 1 or 10 mg kg^-1 diets. The nitric oxide (NO) production is significantly elevated in both uninfected and infected groups fed with 5 mg kg^-1 diet. On the other hand, the lymphocyte proliferation and myeloperoxidase (MPO) activity were significantly increased the infected and uninfected groups fed with 5 and 10 mg kg^-1 diets. The cumulative mortality was found 5% with 1 and 5 mg kg^-1 diet groups while it was observed 10% mortality with 10 mg kg^-1 diet group. Based on the results, it is observed that feeding the uninfected and infected groups with 5 mg kg^-1 anthracenedione diet resulted in better improvement of growth, hematological, biochemical, and innate as well as adaptive immune parameters in M. vittatus against A. hydrophila.

Toxic effects of ornamental stone processing waste effluents on Geophagus brasiliensis (Teleostei: Cichlidae)

The ornamental stone industry generates considerable amounts of waste (OSPW), which may eventually reach natural environments and impact the local ecosystem. The aim of this study was to compare the toxic effects of two OSPW effluents in Geophagus brasiliensis: i) leachate effluent from a lagoon in an OSPW landfill (LE) and ii) decanted effluent from an ornamental stone processing industry (DE). G. brasiliensis were submitted to acute contamination with both OSPW effluents. After contamination, the gills were extracted for evaluation of histopathological alterations and ion concentration, while the liver underwent catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD) and glutathione s-transferase (GST) enzyme activity analysis. An induced biomarker response (IBRv2) index was determined to correlate the multi-biomarker response in G. brasiliensis. Fish gills exposed to DE showed increased concentration of Ca²⁺, Mg²⁺, Na⁺, and K⁺ when compared to those treated with LE. Histopathological lesions were observed in gills of animals exposed to both effluents. Micronucleus and comet assay were significantly greater in fish exposed to DE, when compared to those contaminated with LE. The evaluation of the enzymatic activity of CAT, GPx and SOD indicate greater oxidative stress in DE and LE-exposed fish, while GST activity was not altered. DE showed an IBRv2 value almost two-times higher in relation to LE, indicating that this waste may present higher toxic potential. The results demonstrate that both contaminants led to substantial toxic effects in G. brasiliensis, although the decanted waste induced the most remarkable responses in G. brasiliensis.

Selenium protection against mercury toxicity on the male reproductive system of Clarias gariepinus

The present study aimed to evaluate the protective role of Selenium (Se) (0.1 ppm) on the male reproductive system of the catfish Clarias gariepinus exposed to sublethal doses of Mercury (Hg) (0.04 and 0.12 ppm) for 30 days. Indicators of seminal and gonadal hormone disruption (testosterone, estradiol and 11 keto testosterone), antioxidants (total antioxidant capacity (TAO), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)), oxidative stress biomarkers (lipid peroxidation (LPO), percentage of DNA fragmentation, carbonylated proteins (CP) and nitric oxide (NO)) and histopathological alterations in testicles of Clarias gariepinus were determined. The exposure to Hg resulted in a high accumulation of residues of this metal in testicular tissues. The results showed a significant decrease in sperm count, activity and motility and in all gonadal hormones in Hg exposed groups. Hg exposure also induced a decline in TAO, SOD, CAT and GPx, whereas LPO, DNA fragmentation, CP and NO significantly increased in testicles of C. gariepinus respect to the control group. Although exposure to Se did not reduce the degree of mercury bioconcentration in the testicles, the sperm quality parameters were recovered. Moreover, TAO levels and GPx activity significantly increased after fish exposure to Se, whereas CP levels decreased. LPO, NO, CAT and SOD were also partially normalized when compared with the groups exposed to only Hg. In conclusion, the results showed that Hg, even in the small doses is capable to induce reproductive toxicity in the male catfish. Se exposure partially restored the values of biochemical parameters and sperm quality in Hg-treated fish suggesting protective effects against Hg reproductive toxicity.

Lactobacillus fermentum and/or ferulic acid improved the immune responses, antioxidative defence and resistance against Aeromonas hydrophila in common carp (Cyprinus carpio) fingerlings

This study investigates the possible effects of using Lactobacillus fermentum (LF) and/or ferulic acid (FA) in common carp (Cyprinus carpio) on some immunological parameters as well as resistance against Aeromonas hydrophila. Four diets were prepared including control diet and three diets supplemented with LF (10⁸ CFU/g), FA (100 mg kg^-1) or LF + FA (10⁸ CFU/g + 100 mg kg^-1). After 8 weeks, fish fed LF or/and FA had significantly higher final body weight, weight gain, and specific growth rate when compared to control group (P < 0.05). The feed conversion ratio of fish fed LF or/and FA were noticeably lower than control (P < 0.05). No alterations were observed in case of haematological parameters except red blood cells (RBCs), white blood cells (WBCs), hemoglobin (Hb), and hematocrit (HCT) which were significantly (P < 0.05) increased in fish fed FA or those fed both LF and FA. Also, the WBCs of fish treated with LF or/and FA were noticeably higher than control (P < 0.05). Feeding on LF and FA notably increased the serum total protein and albumin levels (P < 0.05). The serum respiratory burst and lysozyme activity were also enhanced (P < 0.05) in fish fed both LF or/and FA. In addition, evaluation of the serum antioxidant enzymes (catalase, glutathione peroxidase (GPX), and superoxide dismutase (SOD)) activity showed significant (P < 0.05) increase in fish fed FA or both LF and FA as compared to the control. Fish fed LF and FA supplemented diet had highest survival rate after experimental challenge with pathogenic A. hydrophila. The obtained results revealed that LF and/or FA can be used as beneficial feed additive to improve the immune responses and disease resistance in early stages of common carp culture.

Pharmacokinetics of Selenium in Healthy Piglets After Different Routes of Administration: Application of Pharmacokinetic Data to the Risk Assessment of Selenium

Selenium (Se) is a trace element in the environment. Although it is a necessary trace element for human and animal health, excessive Se can also pollute the environment and show toxic effects on humans and animals. Since the safe dose range of Se is narrow, it is important to study the pharmacokinetics of Se in order to make better use of the biological effects of Se. In the present study, we investigated the pharmacokinetic process of sodium selenate in healthy piglet plasma after either intramuscular injection or oral administrations, and examined dynamic changes of antioxidant system in healthy piglets after Se supplementation. The results showed that the Se reached the peak concentration of (0.2451 ± 0.0123) μg mL^-1 at (0.4237 ± 0.0185) h following intramuscular injection administration and (0.1781 ± 0.0142) μg mL^-1 at (2.1517 ± 0.1806) h following oral administration in the plasma. The average AUC of sodium selenite following intramuscular injection and oral administrations was (31.7260 ± 1.3574) and (75.1460 ± 3.4127) mg L^-1 h^-1, respectively. Total antioxidant capacity (T-AOC), glutathione peroxidase (GPx), and superoxide dismutase (SOD) generally show an upward trend and malondialdehyde (MDA) shows a downward trend, regardless of intramuscular injection or oral sodium selenite. An increased concentration of Se was observed in the serum of healthy piglets after intramuscular injection and oral sodium selenite. Our results indicated that the pharmacokinetic process of sodium selenate in healthy piglet blood conforms to the two-chamber open model. Its pharmacokinetic properties are rapid absorption and slow excretion. Antioxidant systems in healthy piglets vary with Se levels, but there is a significant lag period compared with the latter. Our current findings will provide a more complete understanding of clinical rational Se supplementation and avoid contamination of the environment by overdose.

Effects of pollution on freshwater aquatic organisms

This paper presents the reviews of scientific papers published in 2018 issues on the effects of anthropogenic pollution on the aquatic organisms dwelling in freshwater ecosystem at global scale. The first part of the study provides the summary of relevant literature reviews followed by field and survey based studies. The second part is based on categories of different classes/sources of pollutants which affect freshwater organism. This is composed of several sections including metals and metalloids, wastewater and effluents, sediments, nutrients, pharmaceuticals, polycyclic aromatic hydrocarbons, flame retardants, persistent organic pollutants, pharmaceuticals and illicit drugs, emerging contaminants, pesticides, herbicides, and endocrine disruptors. The final part of the study highlights the reviews of published research work on new pollutants such as microplastics and engineered nanoparticles which affect the freshwater organisms. PRACTITIONER POINTS: Heavy metals concentrations should be assessed at nano-scale in aquatic environment. Air pollutants could have long-term effects on freshwater ecosystem. Future studies should focus on bioremediations of freshwater pollution.