Ameliorative effect of selenium yeast supplementation on the physio-pathological impacts of chronic exposure to glyphosate and or malathion in Oreochromis niloticus

Glyphosate and aminomethylphosphonic acid impact on redox status and biotransformation in fish and the mitigating effects of diet supplementation

Fish reared under seminatural conditions can be challenged by exposure to herbicides. Farming facilities relying on the surrounding area's water quality can be affected by glyphosate and aminomethylphosphonic acid (AMPA) contamination. This review summarizes findings on how glyphosate and AMPA in the amounts registered in surface waterbodies affect redox status and biotransformation in fish and covers the aspect of diet supplementation for oxidative stress relief. Environmentally relevant concentrations of glyphosate and AMPA can alter the transcription and catalytic activities of antioxidant enzymes, decrease the content of reduced glutathione, and increase the accumulation of lipid peroxidation products, all of which are signs of a redox imbalance. Glyphosate has been shown to affect complex I in the mitochondrial respiratory chain and dysregulate iron transport-related genes, causing redox disturbance. Relatively high but environmentally realistic glyphosate concentrations can initiate the induction of cytochrome P450 biotransformation enzymes, alter the regulation of ABC exporters, and cause the inhibition of the redox-sensitive Nrf2 signaling pathway. Studies on reducing herbicide toxicity through dietary supplementation are a promising area of research. Natural functional supplements have been proven to have great potential for mitigating glyphosate-induced oxidative stress and thereby improving fish health, which in turn means maintaining productivity in fish farms that use natural water. However, data on the effects of AMPA on fish are scarce, and studies on the alleviation of its toxicity in fish are lacking. Considering the variety of AMPA contamination routes, one cannot underestimate the need for further research.

Enhancing Selenium Accumulation in Rhodotorula mucilaginosa Strain 6S Using a Proteomic Approach for Aquafeed Development

It is known that selenium (Se) is an essential trace element, important for the growth and other biological functions of fish. One of its most important functions is to contribute to the preservation of certain biological components, such as DNA, proteins, and lipids, providing protection against free radicals resulting from normal metabolism. The objective of this study was to evaluate and optimize selenium accumulation in the native yeast Rhodotorula mucilaginosa 6S. Sodium selenite was evaluated at different concentrations (5-10-15-20-30-40 mg/L). Similarly, the effects of different concentrations of nitrogen sources and pH on cell growth and selenium accumulation in the yeast were analyzed. Subsequently, the best cultivation conditions were scaled up to a 2 L reactor with constant aeration, and the proteome of the yeast cultured with and without sodium selenite was evaluated. The optimal conditions for biomass generation and selenium accumulation were found with ammonium chloride and pH 5.5. Incorporating sodium selenite (30 mg/L) during the exponential phase in the bioreactor after 72 h of cultivation resulted in 10 g/L of biomass, with 0.25 mg total Se/g biomass, composed of 25% proteins, 15% lipids, and 0.850 mg total carotenoids/g biomass. The analysis of the proteomes associated with yeast cultivation with and without selenium revealed a total of 1871 proteins. The results obtained showed that the dynamic changes in the proteome, in response to selenium in the experimental medium, are directly related to catalytic activity and oxidoreductase activity in the yeast. R. mucilaginosa 6S could be an alternative for the generation of selenium-rich biomass with a composition of other nutritional compounds also of interest in aquaculture, such as proteins, lipids, and pigments.

Fish Responses to Alternative Feeding Ingredients under Abiotic Chronic Stress

Aquaculture has become one of the most attractive food production activities as it provides high-quality protein for the growing human population. However, the abiotic chronic stress of fish in intensive fish farming leads to a detrimental condition that affects their health and somatic growth, comprising productive performance. This work aims to comprehensively review the impact of alternative and novel dietary protein sources on fish somatic growth, metabolism, and antioxidative capacity under environmental/abiotic stressors. The documental research indicates that ingredients from rendered animal by-products, insects, bacteria as single-cell proteins, and fungal organisms (e.g., yeast, filamentous fungus, and mushrooms) benefit fish health and performance. A set of responses allows fish growth, health, and survival to remain unaffected by feeding with alternative ingredients during chronic environmental stress. Those ingredients stimulate the production of enzymes such as catalase, glutathione peroxidase, and selenoproteins that counteract ROS effects. In addition, the humoral immune system promotes immunoglobulin production (IgM) and cortisol plasmatic reduction. Further investigation must be carried out to establish the specific effect by species. Additionally, the mixture and the pre-treatment of ingredients such as hydrolysates, solid fermentations, and metabolite extraction potentialize the beneficial effects of diets in chronically stressed fish.

Selenium Nanoparticles Ameliorate Adverse Impacts of Aflatoxin in Nile Tilapia with Special Reference to Streptococcus agalactiae Infection

Aflatoxin B1 (AFB1) is a plant-origin toxin that could induce oxidative stress in fish. The micromineral selenium (Se) possesses well-documented antioxidant properties. To assess the ameliorative effects of SeNPs (1 mg/kg fish feed) on oxidative stress induced by AFB1 (500 μg/kg fish feed), Nile tilapia (32.2±1.7 g body weight) were distributed randomly and even in six groups for 8-week feeding trial. Live enzymes, AST, ALT, and ALP levels were increased in the serum of fish fed AFB1-contaminated diet, and the addition of SeNPs could restore normal values compared to the control. The gene expression of antioxidant enzymes, superoxide dismutase (SOD) enzyme and catalase (CAT) enzyme, and DNA fragmentation were significantly increased in response to aflatoxin exposure, while dietary SeNPs could mitigate the generated oxidative stress. The innate immunity, serum antibacterial activity (SAA), oxidative burst activity (OBA), phagocytic activities (PA and PI), and gene expression of cytokines (interleukin (IL)-1β, heat shock protein70 (Hsp), and tumor necrosis factor (TNF)-α) revealed a status of immunosuppression in Nile tilapia fed on AFB1-contaminated diet. These findings showed that fish became more vulnerable to Streptococcus agalactiae infection with a high mortality rate while dietary SeNPs provided a high relative protection level (RPL). From the obtained findings, SeNPs could mitigate the oxidative stress induced by feeding the AFB1 diet and could boost the immunity of stressed Nile tilapia.

Glyphosate-induced liver and kidney dysfunction, oxidative stress, immunosuppression in Nile tilapia, but ginger showed a protection role

The water-borne herbicides are involved in the toxicity of aquatic animals resulting in impaired health status and low productivity. Dietary medicinal herbs present a practical solution to relieve the impacts of herbicides toxicity on the performances of aquatic animals. Herein, we investigated the toxicity of commercial glyphosate-induced oxidative stress, immunosuppression, liver and kidney dysfunction, and the protective role of ginger or ginger nanoparticles in Nile tilapia. Fish were allocated into four groups: the first group presented the control without glyphosate toxicity and ginger feeding, the second group intoxicated with glyphosate at 0.6 mg/L and fed ginger free diet, the third group intoxicated with glyphosate and fed ginger at 2.5 g/kg, and the fourth group intoxicated with glyphosate and fed ginger nanoparticles at 2.5 g/kg. Fish were kept under the experimental conditions for four weeks, and the samples of blood and tissues were collected after 2 and 4 weeks. Markedly, fish exposed to glyphosate showed the highest ALT and AST activities, glucose and cortisol levels, and malondialdehyde levels (MDA) in gills and tissues. While fish in the control and fish intoxicated with glyphosate and fed ginger nanoparticles had the lowest ALT and AST activities, glucose and cortisol levels, and MDA levels after 2 and 4 weeks (P < 0.05). Fish fed dietary ginger had lower ALT and AST activities, glucose and cortisol levels, and MDA levels than the glyphosate intoxicated group after 2 and 4 weeks (P < 0.05). Interestingly, fish-fed ginger nanoparticles showed lower urea and creatinine levels and higher total protein, albumin, and globulin than the glyphosate intoxicated group (P < 0.05) and similar to the control (P > 0.05). Further, fish intoxicated with glyphosate and fed ginger nanoparticles had the highest GSH, lysozyme activity, and immunoglobulin levels after 2 and 4 weeks (P < 0.05). In conclusion, ginger nanoparticles are superior to the standard ginger form in enhancing the antioxidative and immune responses of Nile tilapia exposed to glyphosate.

Effects of glyphosate-based herbicide on gametes fertilization and four developmental stages in Clarias gariepinus

Comparative toxicology continues to provide information on how the age of every living organism affects the frequency, severity, and nature of the potentially toxic agent. We investigated the effect of glyphosate-based herbicide (GBH) exposure on gametes and four developmental stages of Clarius gariepinus (C. gariepinus) (African Catfish). Gametes from healthy gravid female and mature male C. gariepinus were exposed to GBH in sublethal concentrations of 0.0 (G1, control), 0.02 (G2), 0.05 (G3), 0.1 (G4), 0.5 (G5), and 1.0 (G6) mg/L for 24 h at the standard conditions of temperature and water quality parameters. The surviving embryos were examined microscopically for malformation rate and edema occurrence post-GBH exposure. In a separate experiment; postfryer, fingerling, posfingerling and juvenile C. gariepinus were exposed to G1, G2, G3, G4, G5 and G6 of GBH concentrations daily consecutively for 28 days. Fish growth performance, behavioural changes, haematology, oxidative stress, and histology were assessed. From our results, GBH showed altered morphology 24 h post-fertilization, decreased body weight, growth parameters, behavioural indices, and survival rate in the various developmental stages. Oxidative stress metabolite, malondialdehyde levels, increases in the postfryer > postfingerlin > fingerling > juvenile C. gariepinus following GBH exposure. Leukopenia and thrombocytosis were observed in the postfingerlings and juvenile fish and decrease in the levels of reduced glutathione and activity of superoxide dismutase compared with the control. Histology showed gross necrosis of the fish gills, liver, brain, and cardiac myocytes in the exposed fish. Hence, our findings provide an insight into C. gariepinus developmental toxicity due to GBH, although continuous measurement of glyphosate levels in the fish and fish environment is essential.

Selenium-enriched yeast modulates the metal bioaccumulation, oxidant status, and inflammation in copper-stressed broiler chickens

Copper (Cu) could be seriously hazardous when present at excessive levels, despite its vital contribution to various cellular processes. Selenium-enriched yeast (SeY) was reported to improve the health and metabolic status in broiler chicken. Hence, our study was endeavored to illustrate the mitigating efficacy of SeY on Cu-induced hepatic and renal damage. Cobb chicks aged 1 day were allocated into four experimental groups and offered a basal diet, SeY (0.5 mg/kg), CuSO₄ (300 mg/kg), or SeY plus CuSO₄ in their diets for 42 days. Our results revealed that SeY supplement antagonized significantly the Cu accumulation in livers and kidneys of exposed birds. Marked declines were also detected in the AST, ALT, urea, and creatinine levels, besides marked increases in total protein, glycerides, and cholesterol in the SeY-supplemented group. Moreover, enhancement of cellular antioxidant biomarkers (superoxide dismutase, CAT, GPx, and GSH) along with lowered MDA contents were achieved by SeY in hepatic and renal tissues. Further, SeY exerted a noteworthy anti-inflammatory action as indicated by decreased inflammatory biomarkers (IL-1β and TNF-α) and NO levels in both organs. Noticeable histopathological alterations of both organs further validated the changes in the markers mentioned above. To sum up, our findings indicate that SeY can be considered a potential feed supplement for alleviating Cu-induced hepatic and renal damage in broilers, possibly via activation of antioxidant molecules and lessening the inflammatory stress.

Pesticide Pollution: Detrimental Outcomes and Possible Mechanisms of Fish Exposure to Common Organophosphates and Triazines

Pesticides are well known for their high levels of persistence and ubiquity in the environment, and because of their capacity to bioaccumulate and disrupt the food chain, they pose a risk to animals and humans. With a focus on organophosphate and triazine pesticides, the present review aims to describe the current state of knowledge regarding spatial distribution, bioaccumulation, and mode of action of frequently used pesticides. We discuss the processes by which pesticides and their active residues are accumulated and bioconcentrated in fish, as well as the toxic mechanisms involved, including biological redox activity, immunotoxicity, neuroendocrine disorders, and cytotoxicity, which is manifested in oxidative stress, lysosomal and mitochondrial damage, inflammation, and apoptosis/autophagy. We also explore potential research strategies to close the gaps in our understanding of the toxicity and environmental risk assessment of organophosphate and triazine pesticides.