Bioremediation of hemotoxic and oxidative stress induced by polyethylene microplastic in Clarias gariepinus using lycopene, citric acid, and chlorella.

Despite extensive research on the toxic effects of microplastics (MPs), there is no obtainable data on the use of phytobioremediation against MPs toxicity in fish. This study aimed to investigate the protective role of lycopene, citric acid, and chlorella against the toxic effects of MPs in African catfish (Clarias gariepinus) using hematology, biochemical, antioxidants, erythron profiles (poikilocytosis and nuclear abnormalities) and the accumulation of MPs in tissues as biomarkers. Five groups of fish received: normal diet (control); MPs (500 mg/kg diet) (Group 2); MPs (500 mg/kg diet) + lycopene (500 mg/kg diet) (Group 3); MPs (500 mg/kg diet) + citric acid (30 g/kg diet) (Group 4); and MPs (500 mg/kg diet) + chlorella (50 g/kg diet) (Group 5) for 15 days. Group 2 had significantly higher amounts of MPs in the stomach, gills, and feces, electrolyte imbalances (HCO3, Fe, Na+, K+, Ca+2, Cl-, and anion gap, hematobiochemical alterations, and decreases in the activities of superoxide dismutase, catalase, total antioxidant capacity, and glutathione S-transferases compared to the control group. Additionally, Group 2 had significant increase in the percentage of poikilocytosis, and nuclear abnormalities in RBC's compared to the control group. The co-treatment of MPs-exposed fish with lycopene, citric acid, and chlorella-supplemented diets ameliorated the hematological, biochemical, and erythron profile alterations, but only slightly enhanced the antioxidant activity. Overall, lycopene, citric acid, and chlorella can be recommended as a feed supplement to improve hematobiochemical alterations and oxidative damage induced by MPs toxicity in the African catfish (C. gariepinus).

Interactive effects of freshwater acidification and selenium pollution on biochemical changes and neurotoxicity in Oreochromis mossambicus.

Effect of selenium and acidification in freshwater environment was assessed solitary but no reports are available on the impacts of both factors act together. In the present study, effects of combined simultaneous exposure to selenium (Se) and low pH were assessed in Mozambique tilapia, Oreochromis mossambicus. Responses were measured based on antioxidant defenses (enzymatic SOD, CAT, GPx and non-enzymatic GSH), biotransformation enzyme (GST), metallothionein levels (MT), oxidative damage (LPO, CP), Na+/K+-ATPase (NKA) activity in gills and liver tissues and neurotoxicity (acetylcholinesterase, AChE) response in brain tissue. Fish were exposed to combined treatment at different pH levels (7.5, control (optimum pH for tilapia growth); 5.5, low pH) and Se concentrations (0, 10, and 100 µg L-1). Toxicity levels of Se were not significantly different under control and low pH indicating that pH did not affect Se toxicity. Levels of GSH and MT were enhanced in Se-exposed fish at both pH. Combined effects of high Se concentration and low pH decreased SOD and CAT activities and increased those of GPx and GST. However, organisms were not able to prevent cellular damage (LPO and CP), indicating a condition of oxidative stress. Furthermore, inhibition of Na+/K+-ATPase activity was showed. Additionally, neurotoxicity effect was observed by inhibition of cholinesterase activity in organisms exposed to Se at both pH conditions. As a result, the combined stress of selenium and freshwater acidification has a slight impact on antioxidant defense mechanisms while significantly inhibiting cholinesterase and Na+/K + -ATPase activity in fish. The mechanisms of freshwater acidification mediating the toxic effects of trace non-metal element on freshwater fish need to investigate further.

Toxicity of gamma aluminium oxide nanoparticles in the Mediterranean mussel (Mytilus galloprovincialis): histopathological alterations and antioxidant responses in the gill and digestive gland.

PURPOSE: Accumulation of Gamma aluminium oxide nanoparticles γ-Al2O3 NPs significant impact on aquatic ecosystems. However, the toxicity of γ-Al2O3 NPs in aquatic organisms has been limited investigated. This study investigated histopathological changes and antioxidant responses induced by different concentrations of γ-Al2O3 NPs in Mytilus galloprovincialis. MATERIAL AND METHODS: In this study, mussels were exposed to different concentrations of 5 nm γ-Al2O3 NPs (0, 5, 20 and 40 mg/L) for 96 h under controlled laboratory conditions. Gill and digestive gland from mussels were assessed to histopathological (light microscopy, histopathological condition indices, digestive gland tubule types), SOD, CAT, GPx activities. RESULTS: Histopathological indices calculated higher, and significantly different in all exposure groups compared to the control group in gill and digestive gland (p < 0.05). Atrophic phase tubules proportion very high in 20 and 40 mg/L γ-Al2O3 NPs exposure groups. No significant changes in CAT activities in the gill and digestive gland (p > 0.05). Superoxide dismutase (SOD) activities significantly different (p ≤ 0.05) in the digestive gland from 20 mg/L γ-Al2O3 NPs exposures, and GPx activities significantly different (p < 0.05) in gill from 40 mg/L γ-Al2O3 NPs exposures. CONCLUSION: These results indicate that contamination of γ-Al2O3 NPs negatively affects the aquatic organism.

Neurobehavioral, apoptotic, and DNA damaging effects of sub-chronic profenofos exposure on the brain tissue of Cyprinus carpio L.: Antagonistic role of Geranium essential oil.

Currently, the contamination of water with different insecticides like profenofos (PFF) is a critical concern in the aquatic ecosystem. There are limited studies available on the negative impacts of PFF on common carp fish (Cyprinus carpio L.). Therefore, the existing study was designed to investigate the effect of PFF exposure (1/10 of the 96 h-LC50) on the neurobehavior, growth performance, chemical composition, oxidative status, DNA damage, apoptotic status and histological indices of the brain and gill tissues. In addition, this study seeks to detect the ability of geranium essential oil (GEO) dietary supplementation to mitigate the negative impacts of PFF. Accordingly, a total of 120 healthy fish were divided into four groups: the control group, fed on basal diet only; the other groups were fed on a basal diet supplemented with 400 mg kg-1 GEO, basal diet and PFF in water (PFF group), and supplemented diet with GEO and PFF in water (GEO + PFF), respectively, for 60 days. The results showed that PFF significantly reduced fish growth performance, crude protein, and lipid contents. It caused several behavioral alterations including spiral movement, decreased activeness, and changes in feeding behavior. Moreover, PFF increased the DNA tail length, tail moment, and the level of 8-hydroxy-2'-deoxyguanosine. Histologically, PFF induced a wide array of circulatory, inflammatory, regressive and progressive alterations in the brain and gill tissues. PFF significantly downregulated Bcl-2 and upregulated caspase-3 immuno-expression in both organs. Further, it considerably depleted the antioxidant enzymes, including superoxide dismutase, catalase, and glutathione peroxidase. The GEO supplementation did not reach the respective control values but markedly improved most of the behavioral, physical, biochemical, oxidative, apoptotic, and inflammatory markers, altered by PFF exposure. It also protected the gill and brain tissues from the branchial and encephalopathic effects of PFF. These findings suggest that GEO dietary supplements could be advantageous for mitigating PFF negative impacts and presenting a promising feed additive for common carp in aquaculture.

Otx2b mutant zebrafish have pituitary, eye and mandible defects that model mammalian disease.

Combined pituitary hormone deficiency (CPHD) is a genetically heterogeneous disorder caused by mutations in over 30 genes. The loss-of-function mutations in many of these genes, including orthodenticle homeobox 2 (OTX2), can present with a broad range of clinical symptoms, which provides a challenge for predicting phenotype from genotype. Another challenge in human genetics is functional evaluation of rare genetic variants that are predicted to be deleterious. Zebrafish are an excellent vertebrate model for evaluating gene function and disease pathogenesis, especially because large numbers of progeny can be obtained, overcoming the challenge of individual variation. To clarify the utility of zebrafish for the analysis of CPHD-related genes, we analyzed the effect of OTX2 loss of function in zebrafish. The otx2b gene is expressed in the developing hypothalamus, and otx2bhu3625/hu3625 fish exhibit multiple defects in the development of head structures and are not viable past 10 days post fertilization (dpf). Otx2bhu3625/hu3625 fish have a small hypothalamus and low expression of pituitary growth hormone and prolactin (prl). The gills of otx2bhu3625/hu3625 fish have weak sodium influx, consistent with the role of prolactin in osmoregulation. The otx2bhu3625/hu3625 eyes are microphthalmic with colobomas, which may underlie the inability of the mutant fish to find food. The small pituitary and eyes are associated with reduced cell proliferation and increased apoptosis evident at 3 and 5 dpf, respectively. These observations establish the zebrafish as a useful tool for the analysis of CPHD genes with variable and complex phenotypes.

Caffeine supplementation in diet mitigates Aeromonas hydrophila-induced impairment of the gill phosphotransfer network in grass carp Ctenopharyngodon idella.

Some evidence suggests the involvement of phosphotransfer network in the pathogenesis of fish bacterial diseases, catalyzed by creatine kinase (CK), pyruvate kinase (PK) and adenylate kinase (AK); nevertheless, the effects on fish affected by Aeromonas hydrophila remain unknown. Recent evidence suggested a potent protective effect of caffeine on the branchial phosphotransfer network of fish subjected to challenge conditions. Therefore, the aim of this study was to evaluate whether A. hydrophila infection impaired branchial bioenergetics. We also determined whether dietary supplementation with caffeine protected against A. hydrophila-induced gill bioenergetic imbalance. We found that branchial cytosolic CK and AK activities were significant lower in fish experimentally infected with A. hydrophila than in uninfected fish, while mitochondrial CK activity was significant higher. Branchial lactate dehydrogenase (LDH) activity and lactate levels were significant higher in fish experimentally infected by A. hydrophila than in uninfected fish, while sodium-potassium ion pump (Na+, K+-ATPase) activity and adenosine triphosphate (ATP) levels were significant lower. No significant difference was observed between groups with respect to branchial PK activity. The dietary supplementation with 8% caffeine improved the branchial CK (cytosolic and mitochondrial), AK, and LDH activities, as well as ATP levels, but did not prevent increases in branchial lactate levels or the inhibition of Na+, K+-ATPase activity elicited by aeromonosis. Based on this evidence, we believe that reduction of CK (cytosolic) and AK activities contributes to impairment of bioenergetic homeostasis, while augmentation of mitochondrial CK activity can be considered an attempt to prevent or reduce the energetic imbalance during aeromonosis caused by A. hydrophila. The use of 8% caffeine dietary supplementation improved the energetic metabolism via protective effects on CK and AK activities, avoiding the necessity of using anaerobic metabolism. In summary, 8% dietary caffeine can be used to improve branchial energetic homeostasis during aeromonosis caused by A. hydrophila.

Histopathological, biochemical and molecular studies on the toxic effect of used engine oil on the health status of Oreochromis niloticus.

The accidental spilling of petroleum oils into natural water resources expose fishes in the effluent area to serious problems.. Oreochromis niloticus were used in the current study as a model to investigate the toxicity of used engine oil and to evaluate the protective role of vitamin C against this toxicity. The oil concentration used in this study was previously determined to be 0.25 ml/l by 96 h-LC50. After 21 days of engine oil exposure, haematological and biochemical analyses revealed significant reduction in RBCs counts, haemoglobin concentrations and total proteins. However, ALT, AST and glucose levels were significantly increased by the end of the experiment indicating the damaging effects of the oil on fish tissues. Oxidative stress biomarkers were also measured; liver CAT activity was significantly decreased in the oil exposed group compared to control group, while MDA levels were significantly elevated. Histopathological examination showed the presence of several alterations in hepatic and branchial tissues in exposed group compared to the control group. Significant elevations in CYP1 A1 mRNA expression levels in hepatic tissue were also detected in the group exposed to used engine oil compared to the control group. However, supplementation of fishexposed to used engine oil with vitamin Csignificantly enhance the biochemical, oxidative and histological parameters.

Ameliorative effects of Moringa oleifera on copper nanoparticle induced toxicity in Cyprinus carpio assessed by histology and oxidative stress markers.

Nanoparticles (NPs) enter the environment mainly through waste water effluents, accidental spillage, and industrial runoffs. This is worrying because NPs can enter the human body owing to their large aspect-to-size ratio and reactive surfaces that facilitate their penetration through biological barriers and thus can induce oxidative stress in host cells. Therefore, there is a growing concern about the toxicity of NPs, which needs to be addressed. Thus, this study investigated the ameliorative effects of Moringa oleifera seed extract (MOSE) in Cyprinus carpio exposed to copper nanoparticles (Cu-NPs). For the in vivo assessment of the shielding effects of MOSE, 240 samples of C. carpio (40-45 g) were randomly allocated to 24 experimental tanks (10 fish/tank of 40 L) 24 h prior to the start of this experiment. The experimental fish were faced with the water-born exposure of a pre-determined dose of 1.5 mg Cu-NPs/l along with pre- and post-treatment with different doses (100 or 200 or 300 mg l-1) of MOSE for 28 days. The MOSE showed significant ameliorative effect on the antioxidant defense, in response to the elevated levels of Cu-NP-induced oxidative stress. It also played a protective role as indicated by the suppression of the histological alterations in the gills and liver of fish exposed to the Cu-NPs. It was concluded that the Cu-NP-induced toxicity in C. carpio was ameliorated by the use of MOSE in this study. Moreover, the post-Cu-NP treatment stage showed more protective effects of MOSE than the pre-Cu-NP treatment phase. Further studies are suggested to determine the optimum dose and delivery method of MOSE for similar or different NP exposed fish.

Toxicological effect of Al2O3 nanoparticles on histoarchitecture of the freshwater fish Oreochromis mossambicus.

In the present study, freshwater fish Oreochromis mossambicus were exposed to sub lethal concentrations (120, 150 and 180 ppm) of Aluminium oxide nanoparticles (Al2O3 NPs) for 96 h. Histological abnormalities were not observed in the organs of control fishes whereas severe damages and extensive architectural loss was found in the brain, gill, intestine, kidney and muscle tissues of treated fishes with more pronounced effects in 180 ppm. The results showed that the acute exposure to Al2O3NPs altered the histoarchitecture in various fish tissues.

Acute lion's mane jellyfish, Cyanea capillata (Cnideria: Scyphozoa), exposure to Atlantic salmon (Salmo salar L.).

Jellyfish-induced gill pathology relies upon occasional diagnostic observations yet the extent and impact of jellyfish blooms on aquaculture may be significant. Idiopathic gill lesions are often observed in apparently healthy fish. This study exposed Atlantic salmon (Salmo salar L.) smolts to macerated Cyanea capillata at 2.5 and 5 g/L for 2 hr under controlled laboratory conditions. Blood chemistry and gill histopathology were examined over a subsequent 4-week period. Fish showed an acute response to the presence of jellyfish, including characteristic external "whiplash" discoloration of the skin and acute increases in blood electrolytes and CO2 concentration; however, these were resolved within 4 days after exposure. Histopathologically, gills showed first an acute oedema with epithelial separation followed by focal haemorrhage and thrombus formation, and then progressive inflammatory epithelial hyperplasia that progressively resolved over the 4 weeks post-exposure. Results were consistent with the envenomation of gills with cytotoxic neurotoxins and haemolysins known to be produced by C. capillata. This study suggests that many focal hyperplastic lesions on gills, especially those involving focal thrombi, may be the result of jellyfish stings. Thus, the presence of jellyfish and their impact may be severe and understated in terms of marine fish aquaculture and fish welfare.

Effect of Dietary Supplementation of Novel Probiotic Bacteria Bacillus vireti 01 on Antioxidant Defence System of Freshwater Prawn Challenged with Pseudomonas aeruginosa.

The aim of the present work was to isolate probiotic bacteria from the intestinal tract of healthy freshwater prawn Macrobrachium rosenbergii and to examine the effect of the isolated probiotic Bacillus vireti 01 in controlling Pseudomonas aeruginosa infection. This is probably the first report on the isolation of probiotic B. vireti 01 from the intestine of M. rosenbergii. The compounds present in B. vireti 01 were identified using GC-MS analysis. The effect of B. vireti 01-incorporated diet on survival and antioxidant enzymes was studied in M. rosenbergii for 2 weeks. Decreased mortality was observed in M. rosenbergii which were administered with the probiotic diet compared to control diet. The antioxidant defence enzymes activities such as SOD, catalase and GSH were analysed in various organs of M. rosenbergii probiotic-treated and control groups. Antioxidant enzyme activities were considerably lowered (p < 0.01) in the muscles, hepatopancreas and gills of prawns infected by P. aeruginosa when compared to that of prawns fed with the probiotic-supplemented diet. The histopathological results suggest that the hepatopancreas, gills and muscles infected with P. aeruginosa were altered structurally. The result of the present work demonstrates that the probiotic B. vireti 01 could be used as a substitute to antibiotics for treating P. aeruginosa infection in prawns.

Towards the modulation of oxidative damage, apoptosis and tight junction protein in response to dietary leucine deficiency: A likely cause of ROS-induced gill structural integrity impairment.

The current study explored the protective effect of leucine on antioxidant status, apoptosis and tight junction damage in the gill of grass carp (Ctenopharyngodon idella Val.). The trial was conducted by feeding grass carp with six graded level of leucine (7.1, 8.9, 11.0, 13.3, 15.2 and 17.1 g kg-1 diet) for 8 weeks. The fish were fed to apparent satiation 4 times per day. The results indicated that compared with the leucine deficiency group, 8.9-11.3 g leucine kg-1 diet supplementations decreased protein carbonyl (PC), malondialdehyde (MDA) and ROS contents, which may be partially attributed to the improvement of antioxidant status in the gill by increasing hydroxyl radical capacity and anti-superoxide radicals, glutathione contents and the activities and mRNA levels of Cu/Zn superoxide dismutase (SOD1), glutathione peroxidase (GPx), catalase (CAT), glutathione-S-transferase (GST) and glutathione reductase (GR), that referring to the up-regulation of nuclear factor erythroid 2-related factor 2 (Nrf2) mRNA expression. Moreover, leucine deficiency induced DNA fragmentation via the up-regulation of caspase-3, caspase-8 and caspase-9 expressions and down-regulation of target of rapamycin and ribosomal S6 protein kinase 1 expressions. Furthermore, leucine deficiency increased interleukin-1ß (IL-1ß), interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α) mRNA expression and decreased IL-10 and transforming growth factor ß (TGF-ß), which was partly related to nuclear factor κB (NF-κB) and its inhibitor (IκB). In contrast, the relative mRNA expression of IL-1, IL-8 and TNF-α was down-regulated with 8.9-11.3 g leucine kg-1 diet supplementations. Finally, the relative mRNA expression of tight junction protein, including occludin, zonula occludens-1, claudin b, claudin 3 and claudin 12 was up-regulated with leucine diet supplementations. Our results indicate that leucine protected the fish gill structural integrity partially because of the inhibition of apoptosis, the improvement of antioxidant status, the regulation of tight junction protein and related signalling molecules mRNA expressions in the fish gill.

Water-soluble fraction of petroleum induces genotoxicity and morphological effects in fat snook (Centropomus parallelus).

Petroleum hydrocarbons are one of the primary organic chemicals found in water bodies, and the water-soluble fraction of petroleum (WSFP) may be responsible for much of the toxic effects. In the present study, genotoxicity assays and histopathological analysis of the gills were analyzed for two experimental protocols: 1) Juvenile Centropomus parallelus were exposed to different concentrations of WFSP (0%, 25%, 50% and 75%) for 96h; 2) A second fish group was exposed to 50% WFSP for 168h followed by a post-exposure period for 168h in clean water (recovery). The total benzene, toluene, ethyl benzene and xylene (BTEX) and polycyclic aromatic hydrocarbon (PAH) concentrations at time 0 were 254µgL-1 and 4.72µgL-1 in 25%; 552.9µgL-1 and 9.36µgL-1 in 50%; and 842.4µgL-1 and 9.97µgL-1 in 75% WSFP, respectively. Based on the alkaline comet assay, the damage index (DI) values of fish exposed to 25% WSFP for 96h were significantly higher than those in the control group, and in the micronucleus test, the higher damage values were found in fish exposed to 75% WSFP. Furthermore, this last genotoxic test showed recovery after 168h. At all concentrations of WSFP, several histopathological changes were observed, and overall, most of these changes observed in the gills were classified as proliferative changes and represented a protective mechanism against pollutant uptake. Based on the recovery experiment, the damage was also significantly reduced after recovery. Our results showed that short-term exposure to WSFP compounds triggered cellular alterations in C. parallelus, but total recovery did not occur with time. Additionally, the different periods of exposure were not sufficient to induce severe gill damage in C. parallelus. Moreover, this fish demonstrated its usefulness as a sentinel species.

Uranium (238U) bioaccumulation and its persuaded alterations on hematological, serological and histological parameters in freshwater fish Pangasius sutchi.

The early biomarkers for the hematological, serological and histological alterations due to the effect of ½ and » LC50 of 238U in different organs in freshwater fish Pangasius sutchi for water-borne 238U accumulation was investigated. The toxicological data due to 238U accumulation on the hematological parameters such as hemoglobin (Hb), red blood cells (RBCs), white blood cells (WBCs) and hematocrit (Hct) to evaluate the oxygen carrying capacity has been indicated as the secondary response of the organisms. The biomarkers of liver damage were determined as by Serum Glutamic Oxaloacetic Transaminase (SGOT), Serum Glutamic Pyruvic Transaminase (SGPT), Alkaline Phosphatase (ALP), γ-Glutamyl Transferase (γ-GT). Similarly, the renal biomarkers of kidney damage were accessed by creatinine, uric acid, triglycerides, and cholesterol. The decrease in hemoglobin in the experimental group due to disturbed synthesis of hemoglobin was directly proportional to the concentration and exposure duration of 238U. The histological studies proved that liver and gills are the target organ for 238U toxicity. The extensive histological lesions were observed in various tissues due to oxidative stress by the accumulation of 238U, and the 238U toxicity in the organs was in the order of Gills

Effect of feed supplementation with kynurenic acid on the morphology of the liver, kidney and gills in rainbow trout (Oncorhynchus mykiss Walbaum, 1792), healthy and experimentally infected with Yersinia ruckeri.

Kynurenic acid (KYNA) is an endogenous substance produced on the kynurenine pathway which is primarily known for its neuroactive properties. Recently, it has been proven that KYNA is a selective ligand for G protein-coupled receptor (GPR 35), presented on immunocompetent cells such as T lymphocytes. This opens up new possibilities of its application as an immunostimulating substance in aquaculture. Thus far, no histopathological investigations in fish have been completed to evaluate influence of KYNA supplementation in feed. This study has been undertaken to determine the effect of feed supplementation with KYNA (2.5, 25, 250 mg kg-1 of feed) for 28 days on the liver, gills and kidney in healthy fish and experimentally infected with Yersinia ruckeri. In a control group were observed a fatty liver, which is natural for this fish species in the autumn and winter season. As the dose of the supplement was increased, the fat liver changed, it decreased or completely disappeared. Additionally, inflammatory changes occurred in all the analysed organs, and their intensification was dose dependent. In the fish experimentally infected, KYNA caused aggravation of the signs in the liver, kidneys and gills, and the effect was dose dependent. The results implicate that KYNA may be a stressor for fish.

Concurrent environmental stressors and jellyfish stings impair caged European sea bass (Dicentrarchus labrax) physiological performances.

The increasing frequency of jellyfish outbreaks in coastal areas has led to multiple ecological and socio-economic issues, including mass mortalities of farmed fish. We investigated the sensitivity of the European sea bass (Dicentrarchus labrax), a widely cultured fish in the Mediterranean Sea, to the combined stressors of temperature, hypoxia and stings from the jellyfish Pelagia noctiluca, through measurement of oxygen consumption rates (MO2), critical oxygen levels (PO2crit), and histological analysis of tissue damage. Higher levels of MO2, PO2crit and gill damage in treated fish demonstrated that the synergy of environmental and biotic stressors dramatically impair farmed fish metabolic performances and increase their health vulnerability. As a corollary, in the current scenario of ocean warming, these findings suggest that the combined effects of recurrent hypoxic events and jellyfish blooms in coastal areas might also threaten wild fish populations.

Accumulation and effects of Cr(VI) in Japanese medaka (Oryzias latipes) during chronic dissolved and dietary exposures.

Chromium (Cr) is an essential metal and a nutritional supplement for both human and agricultural uses. It is also a pollutant from a variety of industrial uses. These uses can lead to elevated Cr levels in aquatic environments, where it can enter and affect aquatic organisms. Its accumulation and subsequent effects in fish have received relatively little attention, especially for chronic exposure. In the present study, Japanese medaka were chronically exposed to dissolved or dietary Cr(VI) for 3 months. Cr accumulation in liver, gills, intestine, and brain was evaluated. Effects on the antioxidant system, nervous system (acetylcholinesterase, AChE), digestive system (α-glucosidase, α-Glu), and tissue histology (liver and gills) were also assessed. Cr accumulation was observed in the intestine and liver of fish exposed to Cr-contaminated brine shrimp. However, chronic dissolved Cr exposure led to significant Cr accumulation in all organs tested. Analysis of the subcellular distribution of Cr in medaka livers revealed that 37% of the Cr was present in the heat stable protein fraction. The dissolved Cr exposure had pronounced effects on the antioxidant system in the liver, with an elevated ratio of reduced glutathione/oxidized glutathione (GSH/GSSG) and decreases in GSH and glutathione S-transferase (GST). The α-Glu activity in the intestine was significantly inhibited. In addition, Cr exposure caused histopathological alterations in the gills and liver. In general, the effects of dietary Cr were relatively minor, possible due to the much lower accumulation in the fish. Our results imply that Japanese medaka accumulate Cr mainly via uptake of dissolved Cr(VI).

Jellyfish Stings Trigger Gill Disorders and Increased Mortality in Farmed Sparus aurata (Linnaeus, 1758) in the Mediterranean Sea.

Jellyfish are of particular concern for marine finfish aquaculture. In recent years repeated mass mortality episodes of farmed fish were caused by blooms of gelatinous cnidarian stingers, as a consequence of a wide range of hemolytic, cytotoxic, and neurotoxic properties of associated cnidocytes venoms. The mauve stinger jellyfish Pelagia noctiluca (Scyphozoa) has been identified as direct causative agent for several documented fish mortality events both in Northern Europe and the Mediterranean Sea aquaculture farms. We investigated the effects of P. noctiluca envenomations on the gilthead sea bream Sparus aurata by in vivo laboratory assays. Fish were incubated for 8 hours with jellyfish at 3 different densities in 300 l experimental tanks. Gill disorders were assessed by histological analyses and histopathological scoring of samples collected at time intervals from 3 hours to 4 weeks after initial exposure. Fish gills showed different extent and severity of gill lesions according to jellyfish density and incubation time, and long after the removal of jellyfish from tanks. Jellyfish envenomation elicits local and systemic inflammation reactions, histopathology and gill cell toxicity, with severe impacts on fish health. Altogether, these results shows P. noctiluca swarms may represent a high risk for Mediterranean finfish aquaculture farms, generating significant gill damage after only a few hours of contact with farmed S. aurata. Due to the growth of the aquaculture sector and the increased frequency of jellyfish blooms in the coastal waters, negative interactions between stinging jellyfish and farmed fish are likely to increase with the potential for significant economic losses.

In Vivo toxicological assessment of biologically synthesized silver nanoparticles in adult Zebrafish (Danio rerio).

The present study examines the deleterious effect of biologically synthesized silver nanoparticles in adult zebrafish. Silver nanoparticles (AgNPs) used in the study were synthesized by treating AgNO3 with aqueous leaves extract of Malva crispa Linn., a medicinal herb as source of reductants. LC50 concentration of AgNPs at 96 h was observed as 142.2 µg/l. In order to explore the underlying toxicity mechanisms of AgNPs, half of the LC50 concentration (71.1 µg/l) was exposed to adult zebrafish for 14 days. Cytological changes and intrahepatic localization of AgNPs were observed in gills and liver tissues respectively, and the results concluded a possible sign for oxidative stress. In addition to oxidative stress the genotoxic effect was observed in peripheral blood cells like presence of micronuclei, nuclear abnormalities and also loss in cell contact with irregular shape was observed in liver parenchyma cells. Hence to confirm the oxidative stress and genotoxic effects the mRNA expression of stress related (MTF-1, HSP70) and immune response related (TLR4, NFKB, IL1B, CEBP, TRF, TLR22) genes were analyzed in liver tissues and the results clearly concluded that the plant extract mediated synthesis of AgNPs leads to oxidative stress and immunotoxicity in adult zebrafish.