Lipotropes protect against pathogen-aggravated stress and mortality in low dose pesticide-exposed fish

Acute toxicity of mercury in response to metallothionein expression and oxidative and cellular metabolic stress in Barbonymus gonionotus

Mercury (Hg) is one of the most harmful contaminates posing significant health risks to ecosystems worldwide. Fish, recognized for its affordability and accessibility, serves as a vital source of protein for the global population. To understand the impact of Hg exposure, an experiment was conducted using Barbonymus gonionotus (average weight: 9.64 ± 0.76 g) to determine the median lethal concentration (96 h-LC50) and the definitive dose of Hg. This study employed a static, non-renewable bio-assay to assess acute toxicity, using Hg concentrations of 0.3, 0.4, 0.5, 0.6, and 0.7 mg L⁻¹ in the definitive acute toxicity test. These concentrations were further evaluated for their effects on stress and cellular biomarkers, including metallothionein expression, oxidative stress indicators, histopathology, and bioaccumulation. Metallothionein (MT) expression in the liver was evaluated at 48 and 96 h, while oxidative stress markers were assessed in the liver, gill, kidney, and brain tissues. Additionally, glycolytic enzyme activity in the liver, gill, muscle, and kidney, as well as protein metabolic enzymes in the liver, gill, and kidney, were examined over the 96-hour exposure period to understand the effects of Hg at varying concentrations on B. gonionotus. Histopathological changes in the liver and gill and observed, along with the bioaccumulation of Hg in experimental water and different fish tissues. The study concluded that acute Hg exposure caused significant adverse effects on metallothionein expression, stress biomarkers, and the cellular and metabolic activities of B. gonionotus.

Unraveling gene regulation mechanisms in fish: insights into multistress responses and mitigation through iron nanoparticles

The recent trend of global warming poses a significant threat to ecosystems worldwide. This global climate change has also impacted the pollution levels in aquatic ecosystems, subsequently affecting human health. To address these issues, an experiment was conducted to investigate the mitigating effects of iron nanoparticles (Fe-NPs) on arsenic and ammonia toxicity as well as high temperature stress (As+NH3+T). Fe-NPs were biologically synthesized using fish waste and incorporated into feed formulations at 10, 15, and 20 mg kg-1 diet. A total of 12 treatments were designed in triplicate following a completely randomized design involving 540 fish. Fe-NPs at 15 mg kg-1 diet notably reduced the cortisol levels in fish exposed to multiple stressors. The gene expressions of HSP 70, DNA damage-inducible protein (DDIP), and DNA damage were upregulated by stressors (As+NH3+T) and downregulated by Fe-NPs. Apoptotic genes (Cas 3a and 3b) and detoxifying genes (CYP 450), metallothionein (MT), and inducible nitric oxide synthase (iNOS) were downregulated by Fe-NPs at 15 mg kg-1 diet in fish subjected to As+NH3+T stress. Immune-related genes such as tumor necrosis factor (TNFα), immunoglobulin (Ig), and interleukin (IL) were upregulated by Fe-NPs, indicating enhanced immunity in fish under As+NH3+T stress. Conversely, Toll-like receptor (TLR) expression was notably downregulated by Fe-NPs at 15 mg kg-1 diet in fish under As+NH3+T stress. Immunological attributes such as nitro blue tetrazolium chloride, total protein, albumin, globulin, A:G ratio, and myeloperoxidase (MPO) were improved by dietary Fe-NPs at 15 mg kg-1 diet in fish, regardless of stressors. The antioxidant genes (CAT, SOD, and GPx) were also strengthened by Fe-NPs in fish. Genes associated with growth performance, such as growth hormone regulator (GHR1 and GHRβ), growth hormone (GH), and insulin-like growth factor (IGF 1X and IGF 2X), were upregulated, enhancing fish growth under stress, while SMT and MYST were downregulated by Fe-NPs in the diet. Various growth performance indicators were improved by dietary Fe-NPs at 15 mg kg-1 diet. Notably, Fe-NPs also enhanced arsenic detoxification and reduced the cumulative mortality after a bacterial infection. In conclusion, this study highlights that dietary Fe-NPs can effectively mitigate arsenic and ammonia toxicity as well as high temperature stress by modulating gene expression in fish.

Toxicological assessment of bromoxynil and 2-methyl-4-chlorophenoxyacetic acid herbicide in combination on Cirrhinus mrigala using multiple biomarker approach

The widespread application of herbicides raises concerns about their impact on non-target aquatic organisms. This study aimed to evaluate the toxicity of a commercially available herbicide formulation containing Bromoxynil+MCPA (2-Methyl-4-chlorophenoxyacetic acid) on Cirrhinus mrigala (economically significant fish). A total of 210 juvenile fish were subjected to a triplicate experimental setup, with 70 fish allocated to each replicate, exposed to seven different concentrations of herbicide: 0 mg/L, 0.133 mg/L, 0.266 mg/L, 0.4 mg/L, 0.5 mg/L, 0.66 mg/L, and 0.8 mg/L, respectively, for a duration of 96 h. The median lethal concentration (LC50) was determined to be 0.4 mg/L. Significant hematological alterations were observed, including decreases in RBC counts, hemoglobin, hematocrit, and lymphocyte counts, along with an increase in erythrocyte indices. Biochemical analysis revealed elevated levels of neutrophils, WBCs, bilirubin, urea, creatinine, ALT, AST, ALP, and glucose in treated groups. Morphological abnormalities in erythrocytes and histopathological changes in gills, liver, and kidneys were noted. Pathological alterations in gills, liver and kidneys including epithelial cell uplifting, lamellar fusion, hepatolysis, and renal tubule degeneration were observed. Oxidative stress biomarkers such as TBARS (Thiobarbituric Acid Reactive Substance), ROS (Reactive Oxygen Species), and POD (Peroxides) activity increased, while antioxidant enzymatic activities decreased as toxicant doses increased from low to high concentrations. The study reveals that Bromoxynil+MCPA significantly disrupts physiological and hematobiochemical parameters in Cirrhinus mrigala, which highlights the substantial aquatic risks. In conclusion, the herbicide formulation induced significant alterations in various fish biomarkers, emphasizing their pivotal role in assessing the environmental impact of toxicity. This multi-biomarker approach offers valuable insights regarding the toxicological effects, thereby contributing substantially to the comprehensive evaluation of environmental hazards.

Protective role of selenium and selenium-nanoparticles against multiple stresses in Pangasianodon hypophthalmus

Pollution and climate change pose significant threats to aquatic ecosystems, with adverse impacts on aquatic animals, including fish. Climate change increases the toxicity of metal in aquatic ecosystems. To understand the severity of metal pollution and climate change, an experiment was conducted to delineate the mitigation potential of selenium (Se) and selenium nanoparticles (Se-NPs) against lead (Pb) and high temperature stress in Pangasianodon hypophthalmus. For the experiment, five isonitrogenous and isocaloric diets were prepared, varying in selenium supplementation as Se at 0, 1, and 2 mg kg-1 diet, and Se-NPs at 1 and 2 mg kg-1 diet. The fish in stressor groups were exposed to Pb (1/20th of LC50 concentration, 4 ppm) and high temperature (34 °C) throughout the experiment. The results demonstrated that dietary supplementation of Se at 1 and 2 mg kg-1 diet, as well as Se-NPs at 1 mg kg-1 diet, significantly reduced (p < 0.01) the levels of lactate dehydrogenase and malate dehydrogenase in both liver and muscle tissues. Additionally, the levels of alanine aminotransferase and aspartate aminotransferase in both gill and liver tissues were significantly decreased (p < 0.01) with the inclusion of Se and Se-NPs in the diets. Furthermore, the enzymes glucose-6-phosphate dehydrogenase in gill and liver tissues, fructose 1,6-bisphosphatase in liver and muscle tissues, and acid phosphatase in liver tissue were remarkably reduced (p < 0.01) due to the supplementation of Se and Se-NPs. Moreover, dietary supplementation of Se and Se-NPs significantly enhanced (p < 0.01) the activity of pyruvate kinase, glucokinase, hexokinase, alkaline phosphatase, ATPase, protease, amylase, lipase, and RNA/DNA ratio in the fish. Histopathological examination of gill and liver tissues also indicated that Se and Se-NPs protected against structural damage caused by lead and high-temperature stress. Moreover, the study examined the bioaccumulation of selenium and lead in muscle, water, and diets. The aim of the study revealed that Se and Se-NPs effectively protected the fish from lead toxicity and high-temperature stress, while also improving the function of cellular metabolic enzymes in P. hypophthalmus.

Synergistic effect of nickel and temperature on gene expression, multiple stress markers, and depuration: an acute toxicity in fish

Aquatic animals are prone to extinction due to metal pollution and global climate change. Even though the fish and their products are also unsafe for human consumption, their exports have been rejected due to inorganic and organic contaminants. Nickel (Ni) is a metal that induces toxicity and accumulates in the aquatic ecosystem, posing health threats to humans, animals, and fish. In light of the above, our present investigation aimed to determine the median lethal concentration (96 h-LC50) of nickel alone and concurrent with high temperature (34 °C) (Ni + T) using static non-renewable bioassay toxicity test in Pangasianodon hypophthalmus. The groups treated under exposure to Ni reared under control condition (25-28.9 °C) and Ni + T exposure group reread under 34 °C. In this study, chose the definitive dose of Ni and Ni + T as 17, 18, 19, and 20 mg L-1 after the range finding test. The median lethal concentration of Ni and Ni + T was determined as 19.38 and 18.75 mg L-1, respectively at 96 h. Oxidative stress viz. catalase (CAT), superoxide dismutase (SOD), glutathione-s-transferase (GST), and glutathione peroxidase (GPx) in the liver, gill, and kidney were noticeably elevated with Ni and Ni + T during 96 h. Whereas, the CAT, GPx, and SOD gene expressions were significantly upregulated with Ni and Ni + T. Trilox equivalent anti-oxidant capacity (TEAC), cupric reducing anti-oxidant capacity (CUPRIC), ferric reducing ability of plasma (FRAP), ethoxy resorufin-O-deethylase (EROD), and acetylcholine esterase (AChE) were reduced due to exposure to Ni and Ni + T. Cellular metabolic stress and lipid peroxidation were highly affected due to Ni and Ni + T exposure. The immunological status, as indicated by total protein, albumin, globulin, A:G ratio, and nitro blue tetrazolium chloride (NBT), was severely affected by the toxicity of Ni and Ni + T. Moreover, the gene expression of interleukin (IL), tumor necrosis factor (TNFα), toll-like receptor (TLR), and total immunoglobulin (Ig) was remarkably downregulated following exposure to Ni and Ni + T. HSP 70, iNOS expression, ATPase, Na + /K + -ATPase, cortisol, and blood glucose was significantly elevated with Ni and Ni + T in P. hypophthalmus. The bioaccumulation of Ni in fish tissues and experimental water was determined. The kidney and liver tissues were highly accumulated with Ni, whereas DNA damage was reported in gill tissue. Interestingly, depuration study revealed that at the 28th day, the Ni bioaccumulation was below the maximum residue limit (MRL) level. Therefore, the present study revealed that Ni and Ni + T led to dysfunctional gene and metabolic regulation affecting physiology and genotoxicity. The bioaccumulation and depuration results also indicate higher residual occurrence of Ni in water and aquatic organisms for longer periods.

Nano-copper Enhances Gene Regulation of Non-specific Immunity and Antioxidative Status of Fish Reared Under Multiple Stresses

Arsenic pollution, water temperature, and pH are the major concern for aquaculture. Moreover, the aim of the present investigation was to delineate the role of nano-copper (Cu-NPs) in the mitigation of arsenic toxicity, high temperature (34 °C) and low pH (6.5) stress on Pangasianodon hypophthalmus. Four isonitrogenous and isocaloric experimental diets of Cu-NPs at 0, 1.0, 1.5 and 2.0 mg kg-1 were formulated and prepared. Arsenic pollution, low pH and high temperature stress significantly reduced the anti-oxidative status (super oxide dismutase, catalase, glutathione peroxidase and glutathione-s-transferase), lipid peroxidation, total anti-oxidative capacity and lipid profiling (cholesterol, total lipid, phospholipid, very low-density lipoprotein and triglyceride). Further, the supplementation of Cu-NPs at 1.5 and 1.0 mg kg-1 diets noticeably improve the anti-oxidant status and capacity. The stressors groups (As + pH + T, As + T and As) significantly reduced fish immunity viz. albumin, globulin, total protein, albumin globulin ratio (A:G ratio), myeloperoxidase, respiratory burst activities, tumor necrosis factor, total immunoglobulin, and interleukin. Whereas supplementation of Cu-NPs at 1.5 and 1.0 mg kg-1 diets improved the immunity of the fish reared under multiple stresses (As + pH + T). Tail DNA %, DNA damage-inducible protein (DDIP) and inducible nitric oxide (iNOS) synthase gene expression were significantly enhanced with exposure to arsenic, low pH and high temperature but supplementation of Cu-NPs protects the tissues against DNA damage and improved the gene expression of iNOS and DDIP. Cu-NPs at 1.5 and 1.0 mg kg-1 diets significantly enhanced the body weight gain %, protein efficiency ratio, specific growth rate, daily growth index, relative feed intake and reduced the feed conversion ratio. Whereas, the growth-related gene expression such as myostatin (MYST), somatostatin (SMT) was downregulated by Cu supplementation and upregulated the gene expression of growth hormone regulator 1 and β (GHR1 and GHR β) and growth hormone (GH) gene in fish. Dietary Cu-NPs supplementation protects the fish against bacterial infection and enhances arsenic detoxification in different tissues. The present investigation revealed that supplementation of Cu-NPs at 1.5 and 1.0 mg kg-1 diet has the potential to mitigate multiple stress (As + pH + T) in fish.

Insight into three water additives: Revealing the protective effects on survival and stress response under cold stress for Pacific white shrimp Litopenaeus vannamei

The reproduction, development and growth of shrimp were hindered by cold stress, and even death was caused in severe cases. Moreover, huge economic losses to the shrimp aquaculture industry were caused every year by cold currents. The purpose of this study was to investigate the potential protective effects of water additives on the cold stress resistance of Pacific white shrimp (Litopenaeus vannamei) and their ability to improve the survival and stress response of the shrimp. Three potential cold-resistant additives adenosine triphosphate (A), soybean phospholipid (SP) and Clostridium butyricum (CB) on Pacific white shrimp under cold stress were added to the water with three concentrations for each additive. The mortality, activities of antioxidation enzymes and expression of anti-stress related genes in each group under cold stress were detected. The results showed that the cumulative mortality of low concentration for adenosine triphosphate (AL) and soybean phospholipid (SPL), medium concentration for soybean phospholipid (SPM) and high concentration for Clostridium butyricum (CBH) groups were significantly lower than that of the control (C) group when temperature maintained at 13 °C for 6 days. Total antioxidant capacity (T-AOC) content in shrimp plasma was significantly higher, while malondialdehyde (MDA) content was significantly lower than that in the C group. Gene expression analysis showed that 0.4 mg/L of adenosine triphosphate could regulate the immune defense ability and decrease apoptosis level of Pacific white shrimp under cold stress. Soybean phospholipid (2 mg/L) could enhance the immune ability of hepatopancreas, and Clostridium butyricum (10 mg/L) could significantly increase the expression of stress-related genes in shrimp intestine. Overall, these findings suggested that adenosine triphosphate and soybean phospholipid have the potential to be used as cold-resistant additives in Pacific white shrimp culture. This study provided valuable insights into addressing the problem of cold stress in shrimp culture.

Fructooligosaccharide and Bacillus subtilis synbiotic combination promoted disease resistance, but not growth performance, is additive in fish

Species diversification from major to minor carps for their sturdiness and initial higher growth, and also a quest for antibiotic-free aqua farming in the subcontinent, mandates search for and evaluation of alternatives. An experiment was performed to investigate the potential of fructooligosaccharide (FOS) and Bacillus subtilis (BS) (alone or as synbiotics) in promoting growth and immunity against infections in Labeo fimbriatus fingerlings. Six iso-nitrogenous and iso-lipidic diets containing combinations of two levels of FOS (0% and 0.5%) and three levels of BS (0, 104, 106 CFU/g feed) were fed to fish for 60 days. At the end of the feeding trial, twenty-four fish from each group were injected intra-peritoneally with pathogenic strain of Aeromonas hydrophila O:18 to test the immunoprotective efficacy of the supplements against bacterial infection. BS, but not FOS, significantly improved (P < 0.05) growth and feed utilisation attributes like percentage weight gain (PWG), specific growth rate (SGR) and feed conversion ratio (FCR). There were interactive effects of FOS and BS on PWG, SGR and FCR; however, the effects were not additive in nature. These beneficial effects of BS, alone or in combination with FOS, were corroborated by increased protease activity, microvilli density and diameter and number of goblet cells. Overall beneficial effects of FOS and BS included improved erythrocyte (RBC), hemoglobin (Hb), total protein and globulin levels. Total leucocyte (WBC) count and immunological parameters like respiratory burst activity of leucocytes (NBT reduction), lysozyme activity, albumin: globulin ratio and post-challenge survival were significantly improved by both FOS and BS, and their dietary combination yielded the highest improvement in these parameters. Synergistic effects of FOS and BS as dietary supplements indicate that a combination of 106 CFU/g BS and 0.5% FOS is optimal to improve growth, feed utilisation, immune functions, and disease resistance in L. fimbriatus fingerlings.

Multi biomarker approach to assess manganese and manganese nanoparticles toxicity in Pangasianodon hypophthalmus

Manganese (Mn) is an essential element for humans and animals including, fish. It is a still poorly studied in aquatic organisms, where it can be noticeably useful for dietary components and also found pollutant in aquatic environment at high concentrations. On the above information, an experiment was delineated to determine the lethal concentration of manganese (Mn) and manganese nanoparticles (Mn-NPs) alone and with high temperature (34 °C) and its effect on various biochemical markers in Pangasianodon hypophthalmus. The median lethal concentration (96-LC₅₀) of Mn alone (111.75 mg L^-1) and along with high temperature (110.76 mg L^-1), Mn-NPs alone (93.81 mg L^-1) and with high temperature (34 °C) (92.39 mg L^-1) was determined in P. hypophthalmus. The length and weight of the fish were 6.32 ± 0.23 cm and 7.57 ± 1.35 g. The present investigation used five hundred forty-six fish, including range finding (216 fish) and definitive test (330 fish). The acute definitive doses were applied to assess the effect of oxidative stress, glycolytic biomarkers, protein biomarkers, fish immunity, neurotransmitter, energy level, stress hormone and histopathology. Oxidative stress (catalase, superoxide dismutase, glutathione-s-transferase and glutathione peroxidase), stress biomarkers (lipid peroxidation, cortisol, heat shock protein, and blood glucose), lactate and malate dehydrogenase, alanine and aspartate aminotransferase, a neurotransmitter, glucose-6-phosphate dehydrogenase (G6PDH), ATPase, immune system biomarkers (NBT, total protein, albumin, globulin and A:G ratio) were altered with exposure to Mn and Mn-NPs. The histopathology of the liver and gill were also changed due to exposure to Mn and Mn-NPs. The bioaccumulation of Mn in the liver, gill, kidney, brain and muscle tissues, and experimental water at different intervals of 24, 48, 72 and 96 h were determined. Based on the present results, it is strongly suggested that Mn and Mn-NPs exposure alone and with high temperature (34 °C) enhanced toxicity and altered biochemical and morphological attributes. This study also suggested that essential elements in both forms (inorganic and nano) at higher concentrations of Mn and Mn-NPs lead to pronounced deleterious alteration in cellular and metabolic activities and histopathology of P. hypophthalmus.

Synthesis of L-methionine-loaded chitosan nanoparticles for controlled release and their in vitro and in vivo evaluation

Therapeutically popular controlled release-enabling technology has forayed into the nutrition sector. Polymer coated forms of L-methionine used in soy protein diets, and its intermediate metabolite, S-adenosyl-L-methionine, used in myriad of medical conditions have proved more efficacious over (highly catabolized) free forms. In this premier study, L-methionine-loaded chitosan nanoparticles (M-NPs) were synthesized using ionic gelation method and their efficacy was evaluated. Biophysical characterization of the NPs was done using a Nanopartica SZ 100 analyser, transmission electron microscopy, and Fourier transform infrared spectroscopy. The M-NPs were spherical and smooth and 218.9 ± 7.4 nm in size and in vitro testing confirmed the controlled release of methionine. A 60-days feeding trial in L. rohita fish fingerlings was conducted. A basal diet suboptimal (0.85%) in methionine was provided with one of the supplements as under: none (control), 0.8% chitosan NPs (0.8% NPs), 1.2% L-methionine (1.2% M) (crystalline free form), 0.6% M-NPs and 1.2% M-NPs. While the addition of 0.6% M-NPs to the basal diet complemented towards meeting the established dietary requirement and resulted in significantly highest (P < 0.05) growth and protein efficiency and sero-immunological test scores (serum total protein, serum globulin, serum albumin: globulin ratio, phagocytic respiratory burst/NBT reduction and lysozyme activity), 1.2% supplementation in either form (free or nano), for being 0.85% excess, was counterproductive. Liver transaminases and dehydrogenases corroborated enhanced growth. It was inferred that part of the methionine requirement in nano form (M-NPs) can confer intended performance and health benefits in animals relying on plant proteins-based diets limiting in this essential amino acid. The study also paves the way for exploring chitosan NPs-based sustained delivery of amino acids in human medical conditions.

Exposure to Nickel Oxide Nanoparticles Induces Alterations in Antioxidant System, Metabolic Enzymes and Nutritional Composition in Muscles of Heteropneustes fossilis

The current study was performed to explore potential toxic effect of nickel oxide nanoparticles (NiO NPs) on muscle tissue of catfish, Heteropneustes fossilis. Fishes were exposed to different concentrations of NiO NPs (12 mg/L, 24 mg/L, 36 mg/L and 48 mg/L) for a period of 14 days. Results revealed that NiO NPs caused significant increase in Ni accumulation, metallothionein content, lipid peroxidation and activity of different antioxidant enzymes (catalase, glutathione s transferase and glutathione reductase) while decrease in activity of superoxide dismutase (p < 0.05). Data also reported induction of Na⁺/K⁺ ATPase activity initially and then its decrease in concentration dependent manner. Fourier transform infrared spectroscopy revealed shift and changes in spectra of muscle of NiO NPs treated fishes. Fluctuations in activity of aspartate amino transferase, alanine amino transferase and alkaline phosphatase were also noticed. Nutritional contents like protein, lipid, and moisture significantly reduced while glucose and ash percent increased.

Nano‑zinc enhances gene regulation of non‑specific immunity and antioxidative status to mitigate multiple stresses in fish

The toxicity of ammonia surged with arsenic pollution and high temperature (34 °C). As climate change enhances the pollution in water bodies, however, the aquatic animals are drastically affected and extinct from nature. The present investigation aims to mitigate arsenic and ammonia toxicity and high-temperature stress (As + NH₃ + T) using zinc nanoparticles (Zn-NPs) in Pangasianodon hypophthalmus. Zn-NPs were synthesized using fisheries waste to developing Zn-NPs diets. The four isonitrogenous and isocaloric diets were formulated and prepared. The diets containing Zn-NPs at 0 (control), 2, 4 and 6 mg kg^-1 diets were included. Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-s-transferase (GST) were noticeably improved using Zn-NPs diets in fish reared under with or without stressors. Interestingly, lipid peroxidation was significantly reduced, whereas vitamin C and acetylcholine esterase were enhanced with supplementation of Zn-NPs diets. Immune-related attributes such as total protein, globulin, albumin, myeloperoxidase (MPO), A:G ratio, and NBT were also improved with Zn-NPs at 4 mg kg^-1 diet. The immune-related genes such as immunoglobulin (Ig), tumor necrosis factor (TNFα), and interleukin (IL1b) were strengthening in the fish using Zn-NPs diets. Indeed, the gene regulations of growth hormone (GH), growth hormone regulator (GHR1), myostatin (MYST) and somatostatin (SMT) were significantly improved with Zn-NPs diets. Blood glucose, cortisol and HSP 70 gene expressions were significantly upregulated by stressors, whereas the dietary Zn-NPs downregulated the gene expression. Blood profiling (RBC, WBC and Hb) was reduced considerably with stressors (As + NH₃ + T), whereas Zn-NPs enhanced the RBC, WBC, and Hb count in fish reread in control or stress conditions. DNA damage-inducible protein gene and DNA damage were significantly reduced using Zn-NPs at 4 mg kg^-1 diet. Moreover, the Zn-NPs also enhanced the arsenic detoxification in different fish tissues. The present investigation revealed that Zn-NPs diets mitigate ammonia and arsenic toxicity, and high-temperature stress in P. hypophthalmus.

Assessment of hazardous impact of nickel oxide nanoparticles on biochemical and histological parameters of gills and liver tissues of Heteropneustes fossilis

BACKGROUND

The aim of the present study was to assess the hazardous impact of nickel oxide nanoparticles (NiO NPs) on gills and liver of Heteropneustes fossilis.

METHODS

Fishes were treated with four concentrations of NiO NPs for a period of 14 days. Nickel accumulation, lipid peroxidation, antioxidant enzymes activities (superoxide dismutase, catalase, glutathione s transferase & glutathione reductase), liver enzymes activities (aspartate amino transferase, alanine transaminase, & alkaline phosphatase), Na⁺/K⁺ ATPase activity, FTIR, metallothionein content, ethoxyresorufin-o-deethylase activity, immunohistochemistry, histology and scanning electron microscopy were analyzed in both gills and liver tissues.

RESULTS

Results revealed increased accumulation of nickel in both the tissues of exposed fishes. Lipid peroxidation and activities of different antioxidant enzymes increased (except superoxide dismutase) in both the tissues after exposure. Fluctuations in liver enzymes activities and variation in the activity of Na⁺/K⁺ ATPase were also observed. FTIR data revealed shift in peaks position in both the tissues. Level of metallothionein and its expression as well as activity of ethoxyresorufin-o-deethylase and expression of CYP1A also increased in both the target tissues of treated fishes. Furthermore, histological investigation and scanning electron microscopy showed structural damages in gills as well as liver tissues of exposed fishes.

CONCLUSION

Our results suggest that NiO NPs cause deteriorating effects on the gill and liver tissues of fish, therefore effluents containing these nanoparticles should be treated before their release into water bodies.

Selenium nanoparticles and omega-3 fatty acid enhanced thermal tolerance in fish against arsenic and high temperature

The aquatic ecosystem is prone to global climate change and pollution affecting aquatic animals, including fish. In light of the above, we experimented with delineate the role of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) with selenium nanoparticles (Se-NPs) to enhance the thermal tolerance in Pangasianodon hypophthalmus reared under control or concurrent exposure to high temperature and arsenic (As + T) for 112 days. Se-NPs were synthesized using the green approach. Four experimental diets viz. EPA + DHA at 0.2, 0.4 and 0.6 % along with Se-NPs at 0.2 mg kg^-1 diet were formulated and prepared. End of the experiment (112 days), the thermal tolerance viz. CTmin (critical thermal minima) CTmax (critical thermal maxima), LTmin (lethal thermal minima) and LTmax (lethal thermal maxima) were determined. Supplementation of EPA + DHA along with Se-NPs noticeably improved the thermal tolerance of the fish reared under stress (As + T) and control condition. Superoxide dismutase, glutathione-s-transferase, catalase, glutathione peroxides and LPO were enhanced by As + T, whereas EPA + DHA at 0.4 % and Se-NPs reduced the oxidative stress. Further, acetylcholine esterase was inhibited by arsenic alone and concurrent with temperature but dietary supplementation significantly enhanced the brain AChE activity. Exposure to arsenic and concurrent with a temperature significantly reduced the ATPase. Whereas supplementation of EPA + DHA at 0.4 % and Se-NPs enhanced the ATPase in liver and gill tissues. Arsenic bioaccumulation was also reduced with EPA + DHA at 0.4 % and Se-NPs. The present investigation concluded that EPA + DHA at 0.4 % and Se-NPs at 0.2 mg kg^-1 diet protects the P. hypophthalmus against arsenic pollution and thermal stress.

Determination of Median Lethal Concentration (LC50) for Endosulfan, Heptachlor and Dieldrin Pesticides to African Catfish, Clarias gariepinus and Their Impact on Its Behavioral Patterns and Histopathological Responses

Pesticides such as endosulfan, heptachlor and dieldrin persist in aquatic environments as a result of their resistance to biodegradation. However, there is no adequate information about the toxicity of endosulfan, heptachlor and dieldrin to the aquatic organism, African catfish (Clarias gariepinus)-a high valued widely distributed commercially interesting species. The current experiment was performed with the aim to determine the median lethal concentration (LC50) of endosulfan, heptachlor and dieldrin to African catfish (Clarias gariepinus); their behavioral abnormalities and histopathological alterations in several vital organs. A total of 324 juvenile fish were exposed for 96 h to six concentrations of endosulfan and dieldrin at 0, 0.001, 0.002, 0.004, 0.008 and 0.016 ppm, and to heptachlor at concentrations of 0, 0.02, 0.04, 0.08, 0.16 and 0.32 ppm for dose-response tests. The study demonstrated that the species is highly susceptible to those contaminants showing a number of behavioral abnormalities and histopathological changes in gill, liver and muscle. The 96-h LC50 value of endosulfan, dieldrin and heptachlor for the African catfish was found as 0.004 (0.001-0.01) mg/L, 0.006 mg/L and 0.056 (0.006-0.144) mg/L, respectively. Abnormal behaviors such as erratic jerky swimming, frequent surfacing movement with gulping of air, secretion of mucus on the body and gills were observed in response to the increasing exposure concentrations. Histopathological alterations of liver, gill and muscle tissues were demonstrated as vacuolization in hepatocytes, congestion of red blood cells (RBCs) in hepatic portal vein; deformed secondary lamellae and disintegrated myotomes with disintegrated epidermis, respectively. These findings are important to monitor and responsibly manage pesticide use in and around C. gariepinus aquacultural areas.

Evaluation of dietary zinc on antioxidant-related gene expression, antioxidant capability and immunity of soft-shelled turtles Pelodiscussinensis

Zinc (Zn) plays a role in the antioxidant capacity and immunity of aquatic animals. A twelve-week feeding experiment was performed to estimate the impact of dietary zinc on antioxidant enzyme-related gene expression, antioxidant enzyme activity and non-specific immune functions of soft-shelled turtles, Pelodiscus sinensis. Six fishmeal-based experimental diets with 32.45% protein were formulated, which contained 35.43, 46.23, 55.38, 66.74, 75.06 and 85.24 mg/kg Zn, respectively. Catalase (CAT), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) levels improved with an elevation in dietary Zn from 35.43 to 55.38 mg/kg and then reduced when dietary Zn was further elevated. The expression levels of Nrf2 and antioxidant-related genes CuZnSOD, MnSOD, CAT, GPX1, GPX2, GPX3 and GPX4 escalated with elevating Zn concentration up to 55.38 mg/kg in diets and then reduced as dietary Zn elevated. The expression levels of Kelch-like ECH-associating protein 1 (keap1) showed a reverse trend with that of Nrf2. The contents of malondialdehyde (MDA) in the 55.38 and 66.74 mg/kg Zn diet-fed groups were the lowest. Alkaline phosphatase activity (AKP), superoxide anion (O₂^-), lysozyme activity and total antioxidant capacity (T-AOC) improved with an escalation in dietary Zn concentration up to 66.74 mg/kg. Optimal dietary Zn improved antioxidant capability, immunity, and antioxidant enzyme-related gene expression. The dietary Zn demand for soft-shelled turtles were 60.93 and 61.63 mg/kg, based on second regression analysis of SOD and T-AOC activity, respectively.

Metal determination and biochemical status of marine fishes facilitate the biomonitoring of marine pollution

In the present study, the bioaccumulation of chromium, manganese, cobalt, copper, zinc, selenium, arsenic, strontium, cadmium, tin, antimony and lead in tissues of thirty marine fish species collected from New Ferry Whorf, Sassoon dock and Versova fishing harbour in Mumbai, India, were analysed. The bioaccumulation patterns of these twelve elements were determined to assess pollution biomarkers based on cellular and oxidative stresses. Catalase, superoxide dismutase and glutathione-s-transferase, glycolytic enzymes viz. lactate dehydrogenase and malate dehydrogenase, protein metabolism enzymes viz. aspartate transferase and alanine transferase, and lipid peroxidation were significantly higher in muscle and gill tissues. The activities of the neurotransmitter enzyme acetylcholine esterase in muscle and brain tissues was inhibited due to pollution. This study suggested that biochemical attributes such as oxidative stress enzymes, cellular biomarkers, neurotransmitter enzymes and metal and metalloid contamination could be successfully employed, even at low concentrations, as reliable biomarkers for biomonitoring of contaminated marine ecosystems.

Dietary soy lecithin augments antioxidative defense and thermal tolerance but fails to modulate non-specific immune genes in endangered golden mahseer (Tor putitora) fry

A 70-day experiment was carried out to assess the effect of different levels (0, 1 and 2%) of soy lecithin in the diet on growth, survival, antioxidant defense markers, immune gene expression and thermal tolerance limits of golden mahseer, Tor putitora fry. Percentage weight gain, specific growth rate (SGR %) and survival of mahseer fed lecithin supplemented diets were not significantly different from those of the control group. Also, the mRNA expression levels of different immune related genes such as tnfα, il-1β, il-10, complement-3, interferon-gamma (ifnγ) and tlr4 were unaffected by dietary lecithin supplementation. Nevertheless, superoxide dismutase (SOD) activity was significantly greater in the lecithin-fed groups than the control fish. The glutathione-S-transferase (GST) activity was exceptionally high in the 2% lecithin supplemented group compared to the rest two groups. This increase in antioxidant status with dietary lecithin supplementation, however, was not reflected in the whole body malonaldehyde (MDA) levels, as it did not vary significantly among the dietary groups. Importantly, dietary inclusion of soy lecithin significantly increased upper thermal tolerance limits as evidenced by higher CTmax and LTmax values. Likewise, golden mahseer fry fed with lecithin supplemented diets (both 1 and 2%) registered significantly lower critical and lethal thermal minimum (CTmin and LTmin) values than the control group, indicating higher cold tolerance capacity. Our results thus demonstrate that the dietary inclusion of soy lecithin could enhance the upper and lower thermal tolerance limits and antioxidant status of golden mahseer fry and failed to enhance immune related gene expression.

Influence of Feeding Quinoa (Chenopodium quinoa) Seeds and Prickly Pear Fruit (Opuntia ficus indica) Peel on the Immune Response and Resistance to Aeromonas sobria Infection in Nile Tilapia (Oreochromis niloticus)

Simple Summary

The inclusion of dietary supplements as feed additives in fish feed promotes the growth, immunity, and health of the fish, thereby accomplishing extraordinary outcomes in the net gain of the farm. Therefore, the present study was conducted to evaluate the influence of using quinoa seeds (QU) and prickly pear fruit peel (PP) as dietary supplements for fish, at the dose levels of 10% and 20% of the diet, on the immune response and disease resistance against pathogens, providing a novel perspective in aquaculture. Our findings indicated that the inclusion of PP and QU into the diets of Nile tilapia (Oreochromis niloticus) as feed supplements improved the survival rate, as well as the hematological, digestive, antioxidant, and immunological parameters. Moreover, an improvement in the strength of Nile tilapia immune response against Aeromonas sobria (A. sobria) infection was observed, evidenced by the improvement in the survival rate of infected fish. This was accomplished through the protection of the hepatic tissue and modulation of the expression of immune-encoding genes, including the downregulation of the gene encoding TGF-β and upregulation of the IFN-γ-encoding gene. Moreover, histological restoration of the morphological structures of intestine, liver, and spleen tissues was observed, particularly at the supplementation level of 20%.

Abstract

In recent times, nutraceuticals have been used extensively to identify promising feed additives for the improvement of the aquaculture industry through the enhancement of growth and survival rates, potentiation of the immune responses, and fortification of the resistance against infectious bacterial diseases. In this study, Nile tilapia (Oreochromis niloticus) were fed with diets supplemented with quinoa seeds (QU) or prickly pear fruit peel (PP) at the dose levels of 10% or 20% of the diet. After 45 days of the feeding trial, the fish were exposed to Aeromonas sobria (A. sobria) challenge. The pre-challenge indices indicated that both supplements mediated a significant improvement in most of the estimated parameters, including survival rate, antioxidant status, hematological and immunological indices, and hepatoprotective potential. These effects were recorded in the groups fed with high doses of the supplements (20%). The least changes were observed in the QU₁₀-supplemented fish. In the spleen tissue, the TGF-β gene was upregulated in the PP₁₀-, PP₂₀- and QU₂₀-supplemented groups, while the expression of the IFN-γ gene remained unaffected in all the supplemented groups, except for the PP₂₀-supplemented group, which showed an upregulation. After the challenge with A. sobria, the relative survival percentage was improved by the supplementation of PP and QU, particularly in the PP₂₀-supplemented group, possibly via the promotion of immunological responses, hepatoprotective potency, and modulation of the studied genes. Moreover, the morphological structure of the tissues showed marked recovery. The findings suggest that Nile tilapia fed with different levels of PP peel and QU seeds, particularly at the level of 20%, enhanced the immune response in fish and improved their resistance against A. sobria infection.

Mitigation potential of selenium nanoparticles and riboflavin against arsenic and elevated temperature stress in Pangasianodon hypophthalmus

Climate change impact has disturbed the rainfall pattern worsening the problems of water availability in the aquatic ecosystem of India and other parts of the world. Arsenic pollution, mainly through excessive use of groundwater and other anthropogenic activities, is aggravating in many parts of the world, particularly in South Asia. We evaluated the efficacy of selenium nanoparticles (Se-NPs) and riboflavin (RF) to ameliorate the adverse impacts of elevated temperature and arsenic pollution on growth, anti-oxidative status and immuno-modulation in Pangasianodon hypophthalmus. Se-NPs were synthesized using fish gill employing green synthesis method. Four diets i.e., Se-NPs (0 mg kg^-1) + RF (0 mg kg^-1); Se-NPs (0.5 mg kg^-1) + RF (5 mg kg^-1); Se-NPs (0.5 mg kg^-1) + RF (10 mg kg^-1); and Se-NPs (0.5 mg kg^-1) + RF (15 mg kg^-1) were given in triplicate in a completely randomized block design. The fish were treated in arsenic (1/10th of LC₅₀, 2.68 mg L^-1) and high temperature (34 °C). Supplementation of the Se-NPs and RF in the diets significantly (p < 0.01) enhanced growth performance (weight gain, feed efficiency ratio, protein efficiency ratio, and specific growth rate), anti-oxidative status and immunity of the fish. Nitroblue tetrazolium (NBT), total immunoglobulin, myeloperoxidase and globulin enhanced (p < 0.01) with supplementation (Se-NPs + RF) whereas, albumin and albumin globulin (A:G) ratio (p < 0.01) reduced. Stress biomarkers such as lipid peroxidation in the liver, gill and kidney, blood glucose, heat shock protein 70 in gill and liver as well as serum cortisol reduced (p < 0.01) with supplementation of Se-NPs and RF, whereas, acetylcholine esterase and vitamin C level in both brain and muscle significantly enhanced (p < 0.01) in compared to control and stressors group (As + T) fed with control diet. The fish were treated with pathogenic bacteria after 90 days of experimental trial to observe cumulative mortality and relative survival for a week. The arsenic concentration in experimental water and bioaccumulation in fish tissues was also determined, which indicated that supplementation of Se-NPs and RF significantly reduced (p < 0.01) bioaccumulation. The study concluded that a combination of Se-NPs and RF has the potential to mitigate the stresses of high temperature and As pollution in P. hypophthalmus.

Synergistic effect of zinc nanoparticles and temperature on acute toxicity with response to biochemical markers and histopathological attributes in fish

In the present study, an experiment was carried out to delineate the lethal concentration of (LC₅₀) zinc nanoparticles (Zn-NPs) alone and with concurrent to high temperature (34 °C) in Pangasianodon hypophthalmus. The lethal concentration of Zn-NPs alone and with high temperature was estimated as 21.89 and 19.74 mg/L respectivey in P. hypophthalmus. The lethal concentration was decided with the help of definite concentration via 16, 18, 20, 22, 24, 26, 28 and 30 mg/L. The Zn-NPs were significantly alter the biochemical and histopathology of different fish tissues. The stress biomarkers such as oxidative stress (catalase superoxide dismutase and glutathione-s-transferase, lipid peroxidation) was studied in the liver, gill and kidney tissue, which was noticeable (p < 0.01) enhanced with higher concentration in both condition (Zn-NPs alone and Zn-NPs-T) in dose dependent manners. The carbohydrate (lactate dehydrogenase and malate dehydrogenase) and protein metabolic enzymes (alanine amino transferase and aspartate amino transferase) were also remarkable enhanced (p < 0.01) with higher concentration of Zn-NPs and Zn-NPs-T. The neurotransmitter (acetylcholine esterase) activities were significant inhibited (p < 0.01) with exposure to Zn-NPs and Zn-NPs-T and digestive enzymes such as protease and amylase were non-significant (p > 0.01) with the exposure of Zn-NPs and Zn-NPs-T, further, lipase were significantly reduced (p < 0.01) with exposure to Zn-NPs and temperature exposure group. The histopathological alteration were also observed in the liver and gill tissue. The present investigation suggested that, essential trace elements at higher concentration in acute exposure led to pronounced deleterious alteration on histopathology and cellular and metabolic activities in fish.

Effect of zinc on growth performance and cellular metabolic stress of fish exposed to multiple stresses

Global warming due to increasing temperature and contamination in aquatic environment has been found to be inducing cellular metabolic stress in fish. The present study focused on temperature and contamination in aquatic ecosystems and its alleviation/mitigation. Hence, this study was conducted to evaluate the role of zinc to improve growth performance, cellular metabolic stress, and digestive enzymes of the Pangasianodon hypophthalmus reared under lead (Pb) and high temperature. Two hundred and seventy-three fishes were distributed randomly into seven treatments, each with three replicates. Three isocaloric and isonitrogenous diets with graded levels of zinc at 0 mg/kg, 10 mg/kg, and 20 mg/kg were prepared. The Pb in treated water was maintained at the level of 1/21th of LC₅₀ (4 ppm) and maintained at a temperature of 34 °C in exposure groups. The growth performance in terms of weight gain (%), protein efficiency ratio (PER), and specific growth rate (SGR) was found to be inhibited, and the feed conversion ratio (FCR) was enhanced in the Pb and high temperature-exposed group, whereas zinc supplementation has improved weight gain (%), FCR, PER, and SGR. The liver, gill, muscle, and kidney tissues of carbohydrate metabolic enzymes (LDH and MDH), protein metabolic enzymes (ALT and AST), and liver, gill, and muscle G6PDH and ATPase as well as intestinal digestives enzymes (proteases, amylase, and lipase) and intestinal ALP were significantly affected (p < 0.01) by Pb and high temperature exposure to P. hypophthalmus. We herein report the role of zinc in mitigating cellular metabolic stress in fish exposed to Pb and high temperature.

Synergistic effect of dietary selenium nanoparticles and riboflavin on the enhanced thermal efficiency of fish against multiple stress factors

An experiment was designed to delineate the efficacy of a dietary mixture of selenium nanoparticles (Se-NPs) and riboflavin (RF) on the thermal efficiency/tolerance of Pangasianodon hypophthalmus reared under arsenic (2.8 mg/L) and high-temperature (34 °C) stress. A green synthesis method was employed for the synthesis of Se-NPs using fish gills, which are normally discarded as by-products. Four isocaloric and iso-nitrogenous experimental diets were used, namely, a control diet (Se-NPs and RF @ 0 mg/kg diet) and diets containing RF @ 5, 10 or 15 mg/kg diet and Se-NPs @ 0.5 mg/kg diet, and feeding was performed for 95 days. At the end of the feeding trial, the thermal tolerance was evaluated by determination of the following parameters: critical thermal minimum (CTMin), lethal thermal minimum (LTMin), critical thermal maximum (CTMax), and lethal thermal maximum (LTMax). The anti-oxidative status in the form of catalase (CAT), glutathione-s-transferase (GST) and glutathione peroxidase (GPx) activities was significantly (p < 0.01) enhanced upon concurrent exposure to arsenic and high temperature at LTMin and LTMax, whereas a non-significant (p > 0.05) change in superoxide dismutase (SOD) activity was observed in the brain at LTMin and brain, gill and kidney at LTMax. Supplementation with Se-NPs @ 0.5 mg/kg diet and RF @ 5, 10 or 15 mg/kg diet significantly (p < 0.01) improved the anti-oxidative status with or without stressors. AChE activity in the brain was significantly (p < 0.01) inhibited upon concurrent exposure to arsenic and high temperature and improved in the treatment group supplemented with Se-NPs and RF. The arsenic concentration in muscle and experimental water and Se concentration in muscle and experimental feed were analysed. Overall, the results indicated that supplementation with RF @ 5 mg/kg diet and Se-NPs @ 0.5 mg/kg diet could confer protection to the fish against arsenic and thermal stress and led to enhanced thermal efficiency/tolerance of P. hypophthalmus.

Impacts of acute toxicity of arsenic (III) alone and with high temperature on stress biomarkers, immunological status and cellular metabolism in fish

The water bodies are greatly influenced by heavy metal contamination and global increasing temperature. Arsenic (As) is one of the most dangerous widespread pollutants that pose health threats to human, animals and fishes. Considering the above, the study has been carried out to delineate 96 h median lethal concentration of arsenic alone and in combination with high temperature (As-T, 34 °C) by conducting static non-renewable bio-assay acute toxicity in Pangasianodon hypophthalmus (average weight 6.25 ± 0.69 g, length 5.32 cm). Effect of definitive doses such as 25, 26, 27, 28, 29 and 30 mg/L of As alone and in combination with high temperature (As-T) were evaluated on stress biomarkers and cellular metabolism of P. hypophthalmus. The lethal concentration (96 h LC₅₀) of As alone and in combination with high temperature was found to be 28.16 mg/L and 26.88 mg/L, respectively. The stress biomarkers in terms of catalase, superoxide dismutase (SOD) and glutathione-s-transferase (GST) in liver, gill, brain and kidney, blood glucose and NBT were remarkable higher (p < 0.01) in comparison to unexposed group (control group). Brain neurotransmitter enzyme, AChE, immunological status (blood glucose and NBT) and cellular metabolic enzymes (lactate dehydrogenase LDH, malate dehydrogenase MDH, aspartate aminotransferase AST, and alanine aminotransferase ALT, glucose-6-phosphate dehydrogenase G6PDH and ATPase) were noticeably (p < 0.01) altered by As and As-T exposure. The histopathological study exhibited devastating changes with exposure to As and As-T such as bile stagnation, hepatocyte with irregular nucleus, eosinophilic granules in the cytoplasm, necrosis, and nuclear hypertrophy in liver and curling of secondary lamellae, hypertrophy of lamellar epithelium, blood congestion, incomplete fusion of secondary lamellae, complete fusion of several lamellae and aneurysm in gill. Overall results clearly indicate that acute exposure of As and high temperature led to pronounced deleterious alterations on stress biomarkers and cellular and metabolic activities of P. hypophthalmus.

Oxidative and Cellular Metabolic Stress of Fish: An Appealing Tool for Biomonitoring of Metal Contamination in the Kolkata Wetland, a Ramsar Site

The present study delineate the various biochemical and histopathological tool to evaluate as strong biomarker in the field condition for detection of the least and maximize level of pollution and contamination. We have collected Labeo rohita from 13 different sites from East Kolkata wetland to determine biochemical and histopathological status to analyse metal contamination in the significant biological hot spot EKW. The biochemical marker as antioxidative status, i.e., catalase, superoxide dismutase (SOD), and glutathione-S-transferase (GST) in liver and gill, were remarkably higher (p < 0.01) at some of the sampling sites, but catalase in brain, SOD in kidney, GST in brain and kidney, and neurotransmitter as acetylcholine esterase (AChE) in brain were not significant (p > 0.05) among the sampling sites. The glycolytic enzymes, such as lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) in liver, gill, and muscle, and protein metabolic enzymes, such as alanine amino transferase (ALT) and aspartate amino transferase (AST) in liver, gill, muscle, and kidney, were noticeably higher (p < 0.01) at some of the sampling sites. The histopathology of the liver and gill were altered at different sampling sites, such as blood congestion, leucocyte infiltration with parenchymal vacuolisation, nucleus with blood vessels, hepatocytes granular degeneration, haemorrhage, karyorrhexis, shrink nucleus, and pyknotic nuclei in liver. In the gill, structural changes, such as complete destruction and shortening of secondary gill lamellae, blood vessel in gill arch, curling of secondary gill lamellae, aneurism in gill lamellae, and neoplasia, were observed. Most of the metals were found within the safe limit all along the 13 sampling sites, indicating that fishes are safe for the consumption. Based on our finding, we could recommend that a rational application of biochemical profiles, such as oxidative and metabolic stress parameters, including histopathology to be used as biomarkers for biomonitoring the metal contamination in the aquatic environment.

Effect of dietary selenium on immuno-biochemical plasticity and resistance against Aeromonas veronii biovar sobria in fish reared under multiple stressors

The present investigation aims to study role of dietary selenium (Se) on growth performance, oxidative stress markers (catalase, superoxide dismutase and glutathione-s-transferase), stress biomarkers [blood glucose, cortisol and heat shock protein (HSP 70) and immunological status, Nitro blue tetrazolium (NBT), total protein, albumin, globulin, A/G ratio, total immunoglobulin and vitamin C] and survival of fish after Aeromonas veronii biovar sobria challenged. Pangasianodon hypophthalmus was treated with lead (Pb, 4 ppm), and high temperature (34 °C) for 60 days. The growth performance was reduced with declined in feed intake, growth rate and feed efficiency in case of group exposed with Pb alone and concurrent exposure to Pb high temperature (34 °C). The Se has immunomodulatory properties however, supplementation of the dietary Se @ 1 and 2 mg/kg diet has been realistically improved growth performance up to 240%, elevated antioxidative status in different tissues, and immunological status were also improved significantly in the P. hypophthalmus. The bacterial challenged with A. veronii biovar sobria in the P. hypophthalmus resulting in less cumulative mortality (%) and high relative (%) survival has been observed with supplementation of dietary Se @ 1 and 2 mg/kg diet. The bioaccumulation of Pb in muscle tissue has been also drastically reduced with supplementation of dietary Se in feed. Hence, overall results indicated that, dietary Se @ 1 and 2 mg/kg have ability to enhanced overall performance and alleviated multiple stresses in P hypophthalmus.

Effect of Dietary Zinc-Nanoparticles on Growth Performance, Anti-Oxidative and Immunological Status of Fish Reared Under Multiple Stressors

Zinc is one of the essential micronutrients that can be obtained via water and diet in aquatic animals to meet their physiological needs. The present study was designed to understand the effect of the supplementation of zinc nanoparticles (Zn-NPs) in mitigating abiotic and biotic stress in Pangasius hypophthalmus. Two zinc nanoparticle-incorporated diets with 10 and 20 mg/kg nanoparticles and a control without zinc nanoparticles were formulated. To study the effect of formulated feeds on stress tolerance, fish were exposed to sublethal dose (4 ppm) of Pb (lead) and temperature at 34 °C. Two hundred and seventy-three fish were randomly distributed into seven treatment groups in triplicates, namely a control group (no Zn-NPs and no Pb and temperature exposure, Ctr/Ctr), control diet fed and exposed to Pb (Ctr/Pb), control diet fed and concurrently exposed to Pb and temperature (Pb-T/Ctr), and Zn-NPs 10 and 20 mg/kg diet with or without stressors (Zn-NPs 10 mg/kg, Zn-NPs 20 mg/kg, Pb-T/Zn-NPs 10 mg/kg, Pb-T/Zn-NPs 20 mg/kg). The effect of Zn-NPs on growth performance, stress biomarkers, biochemical and immunological responses, and survival of P. hypophthalmus following challenge with pathogenic bacteria were evaluated. The growth performance was noticeably (p < 0.01) enhanced, and anti-oxidative stress (catalase, superoxide dismutase, and glutathione-s-transferase) significantly reduced in the Zn-NPs supplemented groups. Similarly, immunological parameters such as total protein, albumin, globulin, and A/G ratio significantly improved, and stress biomarkers such as blood glucose, cortisol, and HSP 70 were reduced in Zn-NPs supplemented groups. Overall, the results suggest that supplementation of dietary Zn-NPs with less concentration in the diet has a definitive role in the mitigation of abiotic and biotic stress in P. hypophthalmus.

Dietary nano-silver: Does support or discourage thermal tolerance and biochemical status in air-breathing fish reared under multiple stressors?

Unexpected fluctuations in weather parameters due to global climate change have been observed in all ecosystems worldwide. The aquatic ecosystem shelters a great diversity of fishes in the upper region of the ecosystem which adversely get affected due to their poikilothermic nature. The present study was designed to elucidate the impact of critical temperature minima (CTMin), lethal temperature minima (LTMin), critical temperature maxima (CTMax), and lethal temperature maxima (LTMax) on Channa striatus. Biologically synthesized silver nanoparticles (Ag-NPs) were evaluated for their potential to enhance thermal tolerance and improve the activities of biochemical enzymes of C. striatus reared under lead (Pb) and high temperature (34 °C) for 50 days. Three iso-caloric and iso-nitrogenous diets which included a basal diet and two supplemented diets with Ag-NPs @ 0.5 mg/kg, and 1 mg/kg were used in the study. Results suggested that CTMin and LTMin were significantly (p < 0.01) reduced and CTMax and LTMax were enhanced in the group fed with 0.5 mg/kg Ag-NPs supplemented feed. Pre-exposure to high temperature led to enhanced CTMax and LTMax in C. striatus. The biochemical enzymes involved in protein metabolism, carbohydrate metabolism, acetylcholine esterase and antioxidant activities were found to be normal in fish fed with 0.5 mg/kg Ag-NPs supplemented diet. Bioaccumulation of silver and Pb was determined in different fish tissues and experimental water. Overall, the incorporation of Ag-NPs at 0.5 mg/kg in diet can confer protection to fish against Pb and thermal stress and enhance thermal tolerance of C. striatus.

Immuno-protective role of biologically synthesized dietary selenium nanoparticles against multiple stressors in Pangasinodon hypophthalmus

An environment friendly and sustainable approach is being emerged in the area of nanotechnology for accelerated growth and development of culturable aquatic animals hence green chemistry is gaining momentum in recent years. The present study has been carried out to delineate the effects of selenium nanoparticles (Se-NPs) on growth performance, antioxidative status and immunity of fish reared under lead (Pb) and high temperature (34 °C). Three hundred and fifteen fish were equally distributed in seven treatments in triplicates. Three isocaloric and isonitrogenous experimental diets viz. control (Se-NPs-0 mg/kg), Se-NPs at 1 mg/kg and Se-NPs at 2 mg/kg were formulated. The fish were reared under lead (Pb, 1/21st of LC₅₀ (4 ppm)) and high temperature (34 °C) stress and fed with or without dietary Se-NPs. The effects of dietary Se-NPs were studied in terms of growth performance (Weight gain %, feed conversion ratio, protein efficiency ratio and specific growth rate), antioxidative status (catalase, superoxide dismutase, glutathione-S-transferase and glutathione peroxidase), neurotransmitter enzymes (AChE), stress biomarkers (heat shock protein 70, serum cortisol, blood glucose, vitamin C), immunological status (total protein, A/G ratio and respiratory burst activity) in Pangasinodon hypophthalmus post challenge with Aeromonas veronii biovar sobria. Results of the investigation demonstrated significant improvement of growth performance, antioxidative status, neurotransmitter enzyme activity, stress markers and more importantly enhanced immunity of the fish with dietary incorporation of Se-NPs at 1 mg/kg. In addition, post bacterial infection, the relative % survival increased and cumulative mortality % decreased in the group fed with Se-NPs at 1 mg/kg diet. Pb and high temperature treated and fed with control diet group showed devastating impact on the growth performance, antioxidative status, stress markers and immunity of the fish. Similarly, application of Se-NPs at 2 mg/kg showed poor growth performance and elevated level of oxidative stress and other stress biomarkers including other biochemical attributes. Inclusive results indicated that, Se-NPs at 1 mg/kg has capability to enhance overall performance and alleviate multiple stresses in P. hypophthalmus. Hence, Se-NPs at optimum level have ability to develop green chemistry in feed industry for better growth performance of the fish.

Effects of silver nanoparticles on stress biomarkers of Channa striatus: immuno-protective or toxic?

Nanotechnology is a novel arena with promising applications in the field of medicine, industry, and agriculture including fisheries. Cross-disciplinary interactions and the application of this technology in biological systems have led to the innovation of novel nanoparticle antioxidants, which are the subject of our study. In context with above background, we designed an experiment on nano-silver to elucidate its role for mitigation of abiotic and biotic stress. Three diets were formulated viz. silver nanoparticles (Ag-NPs) incorporated at 0.5 and 1 mg/kg diet and control diet (Ag-NPs at 0 mg/kg). Fish were exposed to sublethal level of 1/25th of LC₅₀ (4 ppm) of lead (Pb) and temperature at 34 °C. The effect of Ag-NPs on productive performance (weight gain %, feed conversion ratio, protein efficiency ratio, and specific growth rate), stress biomarkers (catalase, super oxide dismutase, glutathione-s-transferase, acetylcholine esterase, cortisol, heat shock protein), biochemical and immunological response (protein and carbohydrate metabolic enzymes, phagocytic activity, serum total protein and albumin: globulin ratio), histopathology alterations in the liver and gill as well as survival of Channa striatus, following challenge with pathogenic bacteria were evaluated. Dietary Ag-NPs at 0.5-mg supplementation improved growth performance, immunity, survival, and reduced stress biomarker such as HSP 70, cortisol, and blood glucose in various fish tissues. Exposure to Pb and high temperature and group fed with Ag-NPs (1 mg/kg diet) demonstrated remarkable changes in the histo-architect of liver such as pyknotic nuclei, pyknosis, leucocyte infiltration, hemorrhage and karyokinesis, blood vessels with nucleated, lipid vacuoles in the liver tissue. Histology of gill displayed hyperplasia, aneurism, blood congestion, severe telengiectiasis, epithelial lifting, curling of secondary lamella, hyperplasia of epithelial cell of secondary lamella in the group exposed to lead and high temperature and supplemented with Ag-NPs at 1 mg/kg diet. In addition to histopathology, feeding with Ag-NPs at 1 mg/kg diet deteriorated and altered all studied parameters including reduced growth performance. Results obtained in the present study suggest that supplementation of Ag-NPs at 0.5 mg/kg diet has a definitive role to play in the mitigation of abiotic and biotic stress in C. striatus.

Comparative study of selenium and selenium nanoparticles with reference to acute toxicity, biochemical attributes, and histopathological response in fish

Recent studies have demonstrated that selenium (Se) and selenium nanoparticles (Se-NPs) exhibited toxicity at a higher concentration. The lethal concentration of Se and Se-NPs was estimated as 5.29 and 3.97 mg/L at 96 h in Pangasius hypophthalmus. However, the effect of different definite concentration of Se (4.5, 5.0, 5.5, and 6.0 mg/L) and Se-NPs (2.5, 3.0, 3.5, and 4.0 mg/L) was decided for acute experiment. Selenium and Se-NPs alter the biochemical attributes such as anti-oxidative status [catalase (CAT), superoxide dismutase (SOD), and glutathione-S-transferase (GST) activities], neurotransmitter enzyme, cellular metabolic enzymes, stress marker, and histopathology of P. hypophthalmus in a dose- and time-dependent manner. CAT, SOD, and GST were significantly elevated (p < 0.01) when exposed to Se and Se-NPs, and similarly, a neurotransmitter enzyme (acetylcholine esterase (AChE)) was significantly inhibited in a time- and dose-dependent manner. Further, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and malate hydrogenase were noticeably (p < 0.01) affected by Se and Se-NPs from higher concentration to lower concentration. Stress markers such as cortisol and HSP 70 were drastically enhanced by exposure to Se and Se-NPs. All the cellular metabolic and stress marker parameters were elevated which might be due to hyperaccumulation of Se and Se-NPs in the vital organ and target tissues. The histopathology of liver and gill was also altered such as large vacuole, cloudy swelling, focal necrosis, interstitial edema, necrosis in liver, and thickening of primary lamellae epithelium and curling of secondary lamellae due to Se and Se-NP exposure. The study suggested that essential trace element in both forms (inorganic and nano) at higher concentration in acute exposure of Se and Se-NPs led to pronounced deleterious alteration on histopathology and cellular and metabolic activities of P. hypophthalmus.

Zinc nanoparticles potentiates thermal tolerance and cellular stress protection of Pangasius hypophthalmus reared under multiple stressors

A preliminary study was conducted to delineate the ameliorating effect of dietary zinc nanoparticles (Zn-NPs) against thermal stress in Pangasius hypophthalmus reared under concurrent exposure to lead (Pb) and elevated temperature (34°C). Three diets were formulated such as control (no Zn-NPs), Zn-NPs 10 and 20mg/kg diet. Two hundred and thirty four fish were randomly distributed in to six treatments groups in triplicates; such as control group (no Zn-NPs in diet and unexposed to Pb and temperature, Ctr/Ctr), control diet with concurrent exposure to Pb and temperature (Pb-T/Ctr), Zn-NPs 10 and 20mg/kg without stressors (Zn-NPs 10mg/kg, Zn-NPs 20mg/kg), Zn-NPs 10 and 20mg/kg diet with concurrent exposure to Pb and temperature (Pb-T/Zn-NPs 10mg/kg, Pb-T/Zn-NPs 20mg/kg). The Pb in treated water was maintained at the level of 1/21th of LC₅₀ (4ppm) at 34 °C temperature in stressors groups. Post 60 days feeding trial, critical thermal minimum (CTmin), lethal thermal minimum (LTmin), and critical thermal maximum (CTmax), lethal thermal maximum (LTmax) and biochemical attributes on P. hypophthalmus were evaluated. The results indicated that, dietary supplementation of Zn-NPs increased the CTmin, LTmin and CTmax, LTmax in P. hypophthalmus. Positive correlations were observed between CTmin LTmin (Y = - 0.495 + 10.08x, R², 0.896) and CTmax LTmax (Y = - 0.872 + 4.43x, R², 0.940). At the end of the thermal tolerance study, oxidative stress and lipid peroxidation (LPO) were significantly reduced and neurotransmitter enzyme was significantly increased in the groups fed with Zn-NPs @ 10mg and 20mg/kg diet. Overall results indicated that dietary Zn-NPs can confer protection against thermal stress in P. hypophthalmus.

Oxidative and cellular stress as bioindicators for metal contamination in freshwater mollusk Lamellidens marginalis

The concentrations of 14 metals, namely, chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), selenium (Se), arsenic (As), strontium (Sr), cadmium (Cd), tin (Sn), antimony (Sb), mercury, (Hg), and lead (Pb), have been studied in freshwater mollusk Lamellidens marginalis collected from Dhimbe reservoir. In addition, also studied the cellular and antioxidative status to assess metal contamination as pollution biomarkers. The levels of all the 14 metals were elevated in different sampling sites of Dhimbe reservoir. The level of metals in the L. marginalis was followed as Mn > Zn > Ni > Sr > Cr > Cu > Hg > Se > Sn > Pb > As > Co > Cd > Sb. The oxidative biomarkers viz. catalase (CAT), superoxide dismutase (SOD), and glutathione-S-transferase (GST); glycolytic enzymes viz. lactate dehydrogenase (LDH) and malate dehydrogenase (MDH); and protein metabolic enzymes viz. aspartate amino transferase (AST), alanine amino transferase (ALT), and lipid peroxidation (LPO) were significantly (p < 0.01) higher, while neurotransmitter enzymes such as acetylcholine esterase (AChE) were significantly inhibited in muscle of L. marginalis (p < 0.01) collected from different sampling sites. Therefore, based on our results, we could recommend that the Dhimbe reservoir is moderately metal contaminated and investigation based on biochemical parameters such as antioxidative enzymes, cellular biomarkers, and AChE are strong indicators for metal contamination; hence, these parameters are successfully applied as reliable biomarkers for monitoring contaminated freshwater ecosystems.

Dietary zinc promotes immuno-biochemical plasticity and protects fish against multiple stresses

The abiotic and biotic stress is an episode that effect on regulatory, neuro-endocrine and immune systems of animals including fish. The stress creates stimulatory and suppressive of immune system resulting in increases the incidence of infection. In view of these points, we have conducted an experiment to mitigate the stress through a nutritional approach through Zinc (Zn) supplementation in Pangasius hypophthalmus (initial weight-3.65 ± 0.75 g). Three isocaloric and isonitrogenous diets with graded levels of zinc 0, 10 and 20 mg/kg were prepared and fed to seven different groups with each in triplicate. The experimental group as follows as normal water with control diet (Ctr/Ctr), lead (Pb) exposed and fed with control diet (Ctr/Pb), control diet and exposed to Pb and temperature (Ctr/Pb-T), Zn 10 mg/kg fed without stressors (Zn- 10 mg/kg), Zn 20 mg/kg fed without stressors (Zn-20 mg/kg), Zn 10 mg/kg fed and Pb and temperature exposed (Pb-T/Zn 10 mg/kg) and Zn 20 mg/kg fed and exposed to Pb and temperature (Pb-T/Zn 20 mg/kg). The Pb in treated water was maintained at the level of 1/20th of LC₅₀ (4 ppm) and temperature at 34 ^°C in exposure groups. The neutraceuticals role of dietary Zn was studied in terms of antioxidative enzymes (catalase, superoxide dismutase, glutathione-S-transferase), stress markers (Heat shock protein 70, cortisol, acetylcholine esterase, blood glucose, Vitamin C), immunological parameters (Total protein, albumin, globulin, A/G ratio and NBT) and subsequent challenge with Aeromonas veronii biovar sobria. The antioxidative enzymes, stress markers, albumin were significantly (p < 0.01) elevated, brain AChE and immuno-hematological parameters were significantly (p < 0.01) decreased due to lead (Pb) and temperature exposure. The relative survival (%) was reduced due to the concurrent effect of Pb, high temperature stress and bacterial challenge. Zinc at the rate of 10 and 20 mg/kg was found to be restore the biochemical and immunological parameters against concurrent exposure to lead (Pb), temperature and pathogenic infection. Results obtained in the present study indicate that supplementation of 10 and 20 mg/kg of Zn in the diet has a definitive role in the mitigation of lead (Pb) and temperature exposure along with pathogenic infection in P. hypophthalmus.

Oxidative and cellular metabolic stress of Oreochromis mossambicus as biomarkers indicators of trace element contaminants

Antioxidative status, cellular metabolic stress and neurotransmitter enzyme assay as a pollution biomarker in Oreochromis mossambicus collected from Bhima river were investigated. O. mossambicus was collected from 18 different sites of Bhima river, which differ in their extent and type of contamination load. The antioxidative status were determined such as catalase (CAT), superoxide dismutase (SOD) and glutathione-s-transferase (GST) in the liver, gill, brain, gonad and kidney. All the studied parameters indicated potent signals for contamination of the aquatic water body. The antioxidative status was substantially high (p < 0.01) in the fish collected from Bhima river. The cellular stress enzymes such as lactate dehdrogenase (LDH), and malate dehydrogenase (MDH) in liver, gill, brain, gonad and muscle were remarkably (p < 0.01) elevated in O. mossambicus collected from Bhima river. The brain acetylcholine esterase (AChE) was noticeably inhibited (p < 0.01) whereas lipid peroxide (LPO) elevated in fish collected from a few sites. We also used morphological study as biomarkers indicators such as condition factor (CF), hepatosomatic index (HSI), gonadosomatic index (GSI). The results of condition factor and gonadosomatic index are significantly (p < 0.01) poor and hepatosomatic index was significantly (p < 0.01) elevated in O. mossambicus. The finding of the present investigation provides a rational application of oxidative stress, cellular stress, neurotransmitter, lipid peroxide and some morphological parameters to be used as biomarkers for biomonitoring the contamination of trace elements in polluted aquatic environment.

Cellular stress and histopathological tools used as biomarkers in Oreochromis mossambicus for assessing metal contamination

In the present study, we have analyzed various biochemical and histopathological biomarkers in the Oreochromis mossambicus collected from 18 sites at Bhima River. The biochemical biomarkers viz. antioxidative enzymes in muscle viz. catalase, SOD, and GST, glycolytic enzymes in kidney viz. LDH and MDH, protein metabolic enzymes in liver, gill, brain, gonad and muscle viz. ALT and AST, neurotransmitter enzymes in muscle AChE, lipid peroxidation and histopathology in the liver and gill have been evaluated. The oxidative biomarkers, glycolytic enzymes, protein metabolic enzymes and lipid peroxidation were significantly (p<0.01) higher and AChE in muscle were significantly inhibited (p<0.01) in fishes from different sampling sites. The histopathology of the liver and gill were altered at different sampling sites. The liver histopathology showed hepatocytes vacuolization, haemorrhage, karyokinesis, necrosis, pyknotic nuclei, dilation of sinusoids and hepatocyte granular degeneration and in the gill histopathology showed distal lamellar gill tissue, diffuse epithelial hyperplasia and multifocal mucus cell hyperplasia, extensive edema of epithelial cells, blood congestion and edema in secondary lamellae. All the indicators are giving strong signals for contamination of the aquatic water bodies. The Bhima River is surrounded by several cities and agriculture land indicates that vigorous industrial activity coupled with intensive use of chemicals in agricultural practices may held. Therefore, based on our results, we could recommend that the investigated tissue and cell alterations may be successfully applied as reliable biomarkers for monitoring contaminated freshwater ecosystems. This study suggests that, the importance of antioxidative enzymes, cellular biomarkers, AChE, and histopathology used as biomarkers in aquatic ecosystem biomonitoring.

Blue sharks (Prionace glauca) as bioindicators of pollution and health in the Atlantic Ocean: Contamination levels and biochemical stress responses

Marine ecosystems are constantly being threatened by contaminants produced by human activities. There is an urge to better understand their impacts on marine organisms and develop reliable tools for biomonitoring studies, while also assessing their potential impacts on human health. Given their position on top of food webs, sharks are particularly susceptible to bioaccumulation, making them potential sentinel species of marine contamination. The main objective of this study was to find suitable biomarkers for future marine pollution biomonitoring studies by correlating biochemical responses with tissue contaminant body burden in blue sharks (Prionace glauca), a species heavily caught and consumed by humans, while also addressing their general health. The chemical contaminants analysed comprised different persistent organic pollutants (POPs) families from polychlorinated compounds to brominated flame retardants (BFRs) and perfluorinated compounds (PFCs) and different trace and heavy metals. Concentrations of some contaminants in sharks' tissues were found to be above the legally allowed limits for human consumption. A canonical correspondence analysis (CCA) was performed and some strong associations were found between biochemical responses and contaminants' accumulation levels. DNA damage and lipid peroxidation levels, as well as the inhibition of the antioxidant enzyme glutathione peroxidase, were the main effects and consequences of contamination. The impact of contamination on these vital macromolecules underlines the suboptimal conditions of the sampled P. glauca, which can ultimately lead to the degradation of core ecological aspects, such as swimming, feeding, and reproduction. It can be concluded that P. glauca demonstrates great potential to be used as environmental sentinel and suitable biomarker candidates were identified in this work. Moreover, this study also highlights the risks that the consumption of blue shark derived products can pose to human health, which is of upmost interest as the sampled organisms were still juveniles and already presented values above regulatory limits.

Acute toxicity, biochemical and histopathological responses of endosulfan in Chanos chanos

This study investigated 96h median lethal concentration of endosulfan (99%, pure α: β ratio of 7:3) by conducting static non-renewable acute toxicity bio-assay in Chanos chanos juvenile with average weight (110±5.65g). Further, the effect of different definitive doses (18.5, 19.5, 20.5, 21.5 and 22.5µg/L) of endosulfan on metabolic, heamato-immunoligcal and histopathological response were probed. Anti-oxidative enzymes CAT, SOD and GST showed significant (p<0.01) increase of activity in the liver, gill and brain during exposure to endosulfan in a dose and time dependent manner. The brain AChE activity showed significant (p<0.01) inhibition from 18.5 to 22.5µg/L exposure of endosulfan than the control group. LDH and MDH activity gradually increased with consequent increasing dose of endosulfan exposure in the liver, gill and brain. Similarly, ALT, AST and G6PDH activities in both liver and gill increased with consequent increases in the dose of endosulfan exposure. Immunological profile such as blood glucose and serum cortisol level significantly enhanced while respiratory burst activity declined with consequent increasing doses of endosulfan exposure. Histopathological alteration in the gill demonstrated curling of secondary lamellae, thickening of primary epithelium, shorting of secondary lamellae, epithelial hyperplasia, fusion of secondary lamellae, aneurism, and collapsed secondary lamellae due to dose dependent exposure of endosulfan. Liver histology illustrated cloudy swelling and necrosis with pyknotic nuclei to the moderate dose of endosulfan, whereas higher dose of endosulfan (21.5µg/L) displayed severe necrosis of hepatic cells. Overall results clearly indicate that acute exposure of endosulfan led to pronounced deleterious alterations on biochemical, heamato-immunological, and histopathological responses of C. chanos juvenile.

Dietary pyridoxine potentiates thermal tolerance, heat shock protein and protect against cellular stress of Milkfish (Chanos chanos) under endosulfan-induced stress

We herein report the protective role of pyridoxine in enhancing thermal tolerance of Milkfish Chanos chanos reared under endosulfan-induced stress. Four isocaloric and isonitrogenous diets were prepared with graded levels of pyridoxine (0, 50, 75 and 100 mg/kg). Two hundred and twenty five fishes were randomly distributed into four treatment groups in triplicate, reared under endosulfan-treated water, which were fed with pyridoxine supplemented diet, while the negative control group was reared without endosulfan-treatment and control fed. The concentration of endosulfan in treated water was maintained at a level of 1/40th of LC50 i.e. 0.52 μg/L. Dietary pyridoxine supplementation had significant (p < 0.01) effect on temperature tolerance viz. CTmax (Critical temperature maxima), LTmax (Lethal temperature maxima), CTmin (Critical temperature minima) and LTmin (Lethal temperature minima) of milkfish. The positive correlation was observed between CT max and LTmax (Y = -1.54 + 15.6x, R(2), 0.943) as well as CTmin and LTmin (Y = -1.44 + 1.021x, R(2), 0.941). At the end of the thermal tolerance study, antioxidative status and HSP 70 were significantly reduced in pyridoxine supplemented groups, whereas brain AChE was significantly (p < 0.01) elevated compared to positive and negative control. It is concluded that CTmax, LTmax, CTmin and LTmin, antioxidative status, neurotransmitter enzyme and HSP 70 strengthened the enhancement of thermal tolerance of Milkfish.

Dietary Pyridoxine Protects against Stress and Maintains Immunohaematological Status in Chanos chanos Exposed to Endosulfan

The amelioration effect of water-soluble vitamin pyridoxine against stress was evaluated in milkfish, Chanos chanos exposed to endosulfan. Two hundred and twenty-five fish were distributed randomly into five treatments, each with three replicates. Four isocaloric and isonitrogenous diets with graded levels of pyridoxine feed were as follows: normal water and fed with control diet (En0/PY0); endosulfan-treated water and fed with control diet (En/PY0); and endosulfan-treated water and fed with 50 (En/PY 50 mg/kg), 75 (En/PY 75 mg/kg) and 100 mg/kg (En/PY 100 mg/kg) pyridoxine-supplemented feed. The endosulfan in treated water was maintained at a level of 1/40th of LC50 (0.52 ppb). The effect of dietary pyridoxine supplementation was studied in terms of antioxidative enzymes (catalase, superoxide dismutase, glutathione-S-transferase), stress markers [heat-shock protein 70, caspase-3, cortisol, acetylcholine esterase (AChE), blood glucose], immunohaematological parameters (total protein, albumin, globulin and A/G ratio, nitroblue tetrazolium, RBC, WBC, Hb), gill histopathology and a subsequent challenge study with Vibrio parahaemolyticus. The antioxidative enzymes, stress markers, albumin and A/G ratio were significantly (p < 0.01) elevated, brain AChE and immunohaematological parameters were significantly (p < 0.01) decreased, and chromosome aberration and gill histopathology were also altered due to endosulfan exposure. The relative survival % was reduced due to the combined effect of endosulfan stress and bacterial challenge. Fish fed the diet supplemented with pyridoxine at 75 and 100 mg/kg was found to restore the studied parameter towards normal compared with control and indicated protection against endosulfan-induced stress significantly (p < 0.01). Results obtained in the present study indicate that the supplementation of 75 and 100 mg/kg of pyridoxine in the diet has a definitive role in the mitigation of the endosulfan-induced stress in milkfish, C. chanos fingerlings.

Cellular metabolic, stress, and histological response on exposure to acute toxicity of endosulfan in tilapia (Oreochromis mossambicus)

Endosulfan is one of the most hazardous organochlorines pesticides responsible for environmental pollution, as it is very persistent and shows bio-magnification. This study evaluated the impact of acute endosulfan toxicity on metabolic enzymes, lysozyme activities, heat shock protein (Hsp) 70 expression, and histopathology in Tilapia (Oreochromis mossambicus). Among the indicators that were induced in dose dependent manner were the enzymes of amino acid metabolism (serum alanine aminotransferase and aspartate aminotransferase), carbohydrate metabolism (serum lactate dehydrogenase), pentose phosphate pathway (Glucose-6-phosphate dehydrogenase) as well as lysozyme and Hsp70 in liver and gill, while liver and gill Isocitrate dehydrogenase (TCA cycle enzyme) and marker of general energetics (Total adenosine triphosphatase) were inhibited. Histopathological alterations in gill were clubbing of secondary gill lamellae, marked hyperplasia, complete loss of secondary lamellae and atrophy of primary gill filaments. Whereas in liver, swollen hepatocyte, and degeneration with loss of cellular boundaries were distinctly noticed. Overall results clearly demonstrated the unbalanced metabolism and damage of the vital organs like liver and gill in Tilapia due to acute endosulfan exposure.