Secondary Lamellae Research Articles

Kerusakan Histologi Insang Ikan Sapu-sapu (Pterygoplichthys pardalis) setelah Paparan Merkuri (HgCl2)

Mercury is a heavy metal that can undergo biomagnification in the tissue of aquatic organisms, including accumulating in the gills of fish. The main accumulation of mercury occurs in organisms that live in polluted waters, one of which is the suckermouth cat fish ( Pterygoplichtys pardalis ). The purpose of this study was to determine the histological damage of Pterygoplichtys pardalis gills against mercury (HgCl 2 ) exposure. This study used a Completely Randomized Design consisting of six treatments and three replications. The treatments consisted of control; 0.01 0.02; 0.04; 0.08; 0.16 ppm HgCl 2 concentration. The results of the study obtained forms of gill damage in the form of edema, hyperplasia, lamella fusion and epithelial lifting. The highest level of damage occurred at 0.16 ppm HgCl 2 concentration in the form of a reduction in secondary lamella structure. Exposure to mercury causes damage to P. pardalis fish gills

A practical guide to unbiased quantitative morphological analyses of the gills of rainbow trout (Oncorhynchus mykiss) in ecotoxicological studies.

Rainbow trout (Oncorhynchus mykiss) are frequently used as experimental animals in ecotoxicological studies, in which they are experimentally exposed to defined concentrations of test substances, such as heavy metals, pesticides, or pharmaceuticals. Following exposure to a broad variety of aquatic pollutants, early morphologically detectable toxic effects often manifest in alterations of the gills. Suitable methods for an accurate and unbiased quantitative characterization of the type and the extent of morphological gill alterations are therefore essential prerequisites for recognition, objective evaluation and comparison of the severity of gill lesions. The aim of the present guidelines is to provide practicable, standardized and detailed protocols for the application of unbiased quantitative stereological analyses of relevant morphological parameters of the gills of rainbow trout. These gill parameters inter alia include the total volume of the primary and secondary gill lamellae, the surface area of the secondary gill lamellae epithelium (i.e., the respiratory surface) and the thickness of the diffusion barrier. The featured protocols are adapted to fish of frequently used body size classes (300–2000 g). They include well-established, conventional sampling methods, probes and test systems for unbiased quantitative stereological analyses of light- and electron microscopic 2-D gill sections, as well as the application of modern 3-D light sheet fluorescence microscopy (LSFM) of optically cleared gill samples as an innovative, fast and efficient quantitative morphological analysis approach. The methods shown here provide a basis for standardized and representative state-of-the-art quantitative morphological analyses of trout gills, ensuring the unbiasedness and reproducibility, as well as the intra- and inter-study comparability of analyses results. Their broad implementation will therefore significantly contribute to the reliable identification of no observed effect concentration (NOEC) limits in ecotoxicological studies and, moreover, to limit the number of experimental animals by reduction of unnecessary repetition of experiments.

Dietary supplementation of levamisole modulates protein and lipid MALDI-TOF MS profiles of Nile tilapia without causing negative histological alterations

The aim of this study was to investigate the effects of the dietary supplementation of levamisole hydrochloride on Oreochromis niloticus lipid and protein profiles through matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and possible tissue lesions by histopathological analyzes. A total of 320 fingerlings were distributed into the following groups: fish fed supplemented diets with 100, 150 and 200 mg of levamisole kg−1 and fish fed a diet receiving no supplementation. After 8 days of feeding, stomach histopathology showed that fish fed the 100 and 150 mg kg−1 levamisole supplemented diets had a significantly lower intensity in the degeneration of columnar epithelial cells when compared to the control group (p < 0.05), possibly a result of a generalized superior health status caused by the supplementation. Liver analysis showed no significant alterations (p ≥ 0.05), while histopathology of gills showed significant alterations in the fusion of secondary lamellae, in which only fish fed the highest dose showed a significant higher value when compared to the control group (p < 0.05). In the protein analysis, a total of 106 m/z peaks were observed, where 28 peaks showed significant changes in their intensity (p < 0.05). In general, fish supplemented with 100 mg kg−1 of levamisole showed an increase in the intensity in the peaks within the m/z ranges 2814–3337, 3732–6998 and 9045–13,505, while fish fed with 150 mg kg−1 dose showed a reduction in the intensity at most of the peaks found within those intervals. Immune system related proteins occurring within those ranges suggest a positive modulation of the protein profile. There were also marked alterations in the lipid profiles. Levamisole supplemented fish showed a significant positive modulation in the glycerophosphocholines group (p < 0.05), whose function in improving fish resistance to cold water suggests an additional health benefit of this feed additive. Judging on the histopathological analyses and MALDI-TOF MS lipid and protein profiling, the 100 mg kg−1 levamisole supplementation dose provided the greatest benefits to Nile tilapia fingerlings.

Sublethal effects of phenol on histology of selected organs of freshwater fish Mystus vittatus.

Acute toxicity (96 h LC50) of phenol was analyzed in the cat fish Mystus vittatus in static bio-assay over a 96-h exposure period using probit method. The 24, 48, 72, and 96 h LC50 values (with 95% confidence limits) of phenol for fingerling catfish were found out as 13.98, 13.17, 12.62, and 12.21 mg/l respectively. Investigations pertaining to the histopathological sections have shown high degree of pathological lesions observed in various parts like gill, liver intestine, and kidney of the fish species. Analysis of gill section revealed observable changes in the experimental species such as fusion, malformation at the tip of secondary lamellae, vacuolation, hyperplasia, and epithelial damage. Exposure of phenol showed cytoplasmic vacuolation, tissue damage, and loss of hepatic cell wall in the liver of experimental organism. Lesions of tissue damage at the epithelial site, inflammation, and clumping of adjacent villi made of columnar epithelium have been observed in the intestine of fish, and also the excretory part of the fish kidney revealed various changes like glomerular atrophy, damage of Bowman's capsule, vacuolization, and degeneration of renal epithelium. The current study on histological changes observed in the experimental organisms has thrown light on the current scenario which poses threat and danger to the whole aquatic ecosystem, and this study plays a vital role in assessing the aquatic pollution.

Total replacement of fishmeal with poultry by-product meal affected the growth, muscle quality, histological structure, antioxidant capacity and immune response of juvenile barramundi, Lates calcarifer.

The present study investigates if the total replacement of dietary fishmeal (FM) with poultry by-product meal (PBM), supplemented with methionine influences the muscle fatty acids composition, normal gut morphology, histological traits of the liver, muscle, and gill, liver enzymes, immune and antioxidant response, and stress-related gene in juvenile barramundi, Lates calcarifer in relation to growth and feed utilization. Barramundi (3.58±0.01g) were randomly distributed into six 300 L seawater recirculating tanks (25 fish/tank) and fed two formulated isonitrogenous and isolipidic diets for 6 weeks. The control diet had FM as the sole animal protein source, whereas other test diet had only PBM as an animal protein source. Dietary PBM affected the fish performance and feed utilization. Regarding muscle fatty acid profile, total saturated fatty acids and monounsaturated fatty acids elevated while total PUFA particularly n-3 LC-PUFA and EPA decreased in PBM fed fish than control diet fed fish. Liver, muscle, gill, and intestinal histology showed no obvious alteration in control diet fed fish, however, more lipid droplets and hepatic vacuolization in the liver, necrotic myotome in muscle, hyperplasia in secondary lamellae in gill and short and broken folds in the intestine were observed in PBM fed fish. Similar to light microscopy observation of intestinal morphology, the transmission electron microscopy (TEM) analysis revealed shorter and smaller microvilli in fish fed PBM. Histopathological alterations in the liver of PBM fed fish were further associated with the elevated levels of aspartate aminotransferase (AST) and glutamate dehydrogenase (GLDH) and the significant upregulation of stress-related genes, HSP70 and HSP90. Also, a negative influence on lysozyme activity, and antioxidant enzymatic activities were recorded in fish fed PBM. Overall, it can be concluded that a total substitution of FM protein by methionine supplemented PBM negatively influenced the growth performance, liver health, histological traits of different organs, immune and antioxidant response, and expression of stress-related genes in juvenile barramundi.

Morpho-Functional Alterations in the Gills of a Seawater Teleost, the Ornate Wrasse (Thalassoma pavo L.), after Short-Term Exposure to Chlorpyrifos.

Chlorpyrifos (CPF) is an organophosphorus insecticide commonly used for domestic and agricultural purposes. The risk posed by environmental contamination from CPF is well acknowledged, and it has been detected worldwide in aquatic habitats and coastal areas. In addition, due to its slower degradation in seawater compared to freshwater, CPF is of particular concern for marine environments. Here, we investigated for the first time the morpho-functional alterations induced by CPF on the gills of Thalassoma pavo, a widespread species in the Mediterranean Sea. We tested the effects of two sublethal concentrations (4 and 8 µg/L) after 48 and 96 h. Our study demonstrates that the alterations induced by CPF are dose and time-dependent and highlight the harmful properties of this insecticide. After exposure to the low tested concentration, the more frequent alteration is an intense proliferation of the primary epithelium, whereas after exposure to the high concentration, the primary epithelium proliferation is less extensive, and the most evident effects are the thinning of secondary lamellae and the ectopia of chloride and goblet cells. CPF also modulated the expression of Na+/K+-ATPase. Dilation of lamellar apical tips, pillar cell degeneration, and appearance of aneurysms are often observed.

Histopathological analysis of the gills of fresh water fish Channa gachua exposed to fungicide Pydiflumetofen

Indiscriminate use of pesticides has become a serious problem among human and ambient environment. The present study is aimed to assess the damage caused to the fish Channa gachua (family: Channidae) exposed to fungicide Pydiflumetofen. Respiration in Channa gachua mainly occurs through their gills. Any change in the chemical quality of water directly affects the structure and function of gills. Fish gill also helps in osmoregulation and excretion besides respiration. When fish exposed to sub-lethal concentration of Pydiflumetofen pesticide for 10 days, 15days and 20days include Curling and fusion in secondary lamellae, Hyperplasia, reduction in the respiratory surface area of filaments, fusion at the tip of the lamellae, sub lamellar and sub epithelial space occur.

Effects of Acute Toxicity of Chlorpyrifos (EC 50%) and Associated Histological Alterations in Gills, Liver and Kidney of Mozambique Tilapia, Oreochromis mossambicus (Peters, 1852)

Background: The pesticides are known to adversely affect the quality of water and create hazards for aquatic life that results in severe damage to non-target freshwater organisms including fish. Among them, the organophosphorus pesticide, chlorpyrifos (CPF) is one of the most commonly used pesticides for controlling various kinds of pests in agriculture. Pesticides after entering in to the body of fish bring about histopathological and biochemical changes in different target and non-target organs. Hence, the present study aimed to investigate the toxicity effects of Chlorpyrifos (CPF) and associated histopathological changes in the gill, liver and kidney of the Mozambique Tilapia, Oreochromis mossambicus under the acute toxicity concentrations. Methods: Static bioassay was carried out for Chlorpyrifos with Oreochromis mossambicus as test animal for a period of 96 hrs as per standard methods and LC50 values were calculated through Probit analysis. The fishes were exposed to five acute concentrations (0.033, 0.066, 0.132, 0.264 and 0.528 ppb). The gill, liver and kidney tissues were collected from the fishes exposed to the pesticide and standard histology protocol was followed to investigate the histopathological changes. Result: The histological changes observed in the gill included lamellar aneurysm, curling of secondary lamellae, shortening of the secondary lamellae, hypertrophy of epithelial cell, fusion of secondary lamellae, deformation of the cartilage core, blood congestion, collapsed secondary lamellae, excessive mucus secretion, disorganization of the secondary lamellae, haemorrhage at primary lamellae, necrosis, haemorrhage at secondary lamellae. The most common histopathological changes in the liver were characterized by cellular necrosis, degeneration of hepatocytes, nuclear degeneration, fat deposition, rupture of nucleus, hypertrophied hepatocytes, blood congestion, blood sinusoids, cellular hypertrophy, increased pycnotic nucleus, cirrhosis and hemosiderosis. Further, histological changes like appearance of dilated lumen, hypertrophied epithelial cells, severe haemorrhage, blood congestion, melanomacrophage aggregation, narrowing of lumen, degenerated tubule, degenerated glomerulus, shrunken glomerulus and distended glomerulus were observed in the kidney. Thus, it is evident from the present study that Chlorpyrifos can be a potential toxicant affecting the fishes at tissue level on dose and time dependent manner which are expected to affect the other physiological processes in the long run.

Zinc Induced Histopathological Alternations in Gill, Liver, and Kidney of Freshwater Fish Gonoproktopterus kolus (Sykes)

The present study aims to investigate the histopathological changes in gill, liver, and kidney of fresh water fish Gonoproktopterus kolus (Sykes). The fingerlings of fish were exposed to Zinc (Zinc sulphate) in acute toxicity experiment (96 hrs.). The LC₀ and LC₅₀ concentrations were 2.430 ppm and 4.860 ppm respectively. After acute exposure, fish were sacrificed and tissues were obtained separately from control and LC₀ and LC₅₀ groups. These tissues were fixed in Bouin's fluid and standard protocol was followed to study histopathological alterations in gill, liver and kidney of experimental fish. In gills, fusion and degenerative changes were observed in secondary gill lamellae. In liver, hepatocytes showed hypertrophy due to degenerative changes in cellular structure. Empty hepatocytes showed shifting of nucleus. Kidney showed degenerative nuclei in the epithelial lining of the tubule. Haemopoetic tissue showed hypertrophy and disarray. Distended glomerulus was observed. Renal tubules showed disarrangement as compared to control. Thus, in present investigation, it was observed that heavy metal zinc is affecting the fishes at tissue level, which may interfere in physiological processes.

Effects of an anti-IGF-1 receptor monoclonal antibody on laminitis induced by prolonged hyperinsulinaemia in Standardbred horses.

Currently, there are no registered veterinary drugs for the treatment of endocrinopathic equine laminitis, and although this form of the disease is known to be caused by prolonged hyperinsulinaemia, the mechanism of insulin toxicity is unclear. One possibility is that high concentrations of insulin activate IGF-1 receptors (IGF-1R) in lamellar tissue, leading to uncontrolled cell proliferation and epidermal lamellar dysregulation. An equinized version of a human anti-IGF-1R therapeutic monoclonal antibody (mAb11) was generated to test this theory, using a modification of the prolonged euglycaemic-hyperinsulinaemic clamp technique. Healthy Standardbred horses were infused for 48 h with 0.9% saline (negative-control, n = 6), a combination of insulin (4.5 mIU/kgBW/min) and a variable infusion of 50% glucose to maintain euglycaemia (positive-control, n = 6), or insulin and glucose, preceded by a low dose of mAb11 (20 mg), designed to treat one foot only and delivered by retrograde infusion into one forelimb (mAb-treated, n = 7). Maximum insulin concentrations were 502 ± 54.4 and 435 ± 30.4 μIU/mL in the positive-control and mAb11-treated groups, respectively (P = 0.33). While the control group remained healthy, all the insulin-treated horses developed laminitis within 30 h, as judged by clinical examination, foot radiographs and histological analysis. Some effects of insulin were not attenuated by the antibody, however, relative to the positive-control group, horses treated with mAb11 showed less sinking of the distal phalanx (P < 0.05) and milder histological changes, with markedly less elongation at the tips of the secondary epidermal lamellae (P < 0.05). These differences were apparent in both front feet and were statistically significant when the values for both feet were combined. The results confirm that IGF-1R may have a role in insulin-induced laminitis and suggest that mAb11 warrants further research as a potential agent to prevent or treat the disease.

Assessment of cytotoxicity in gills of fish Labeo rohita reared in untreated and treated sewage water.

The unregulated discharge of untreated municipal sewage water to the natural water bodies is a major threat to the aquatic ecosystems. In the present study, the fingerlings of Labeo rohita were exposed to treated sewage water and 1/10th of LC50 and 1/20th of LC50 of untreated sewage water (UT) obtained from sewage water treatment plant, Ludhiana, India. After determining 96-h LC50 value of UT, fingerlings were divided into four groups: control, treated, 1/10th of LC50 UT and 1/20th of LC50 UT and exposed for a period of 2months. Our study revealed that 1/10th LC50 UT and 1/20th LC50 UT groups had significant reduction in body weight, total body length, standard body length and gills somatic index in comparison with the control and treated groups. Histopathological alterations in cellular structure of gills such as ruptured primary lamellae, broken secondary lamellae, distorted chloride cells and goblet cells, missing lamellae and disintegrated lamellar epithelium were also observed in 1/10th LC50 UT and 1/20th LC50 UT groups. A significantly high frequency of micronucleated (MN) cells was observed in 1/10th LC50 UT and 1/20th LC50 UT groups along with the presence of binucleated cells (BN), elongated nuclei (EN) and nuclear buds in gill cells. Genotoxic nature of UT was further confirmed from significantly high values of genetic damage index (GDI) and percentage (%) DNA damage in gill cells of fingerlings exposed to sub-lethal concentrations of UT. The study concluded that untreated sewage water has potential to induce anatomical and physiological defects in gills cells and the severity of toxicity increases with the increase in duration of exposure.

The structure changes of polypropylene precursor film with different die draw ratio during annealing

Two polypropylene precursor films with various die draw ratios (DDR) are made by melt extrusion. The crystal structure evolution analysis during annealing show that two precursor films have identical long periods and lamellae thickness but different lateral dimensions and tilted states of lamellae. Lower DDR generates shorter lateral dimension and more tilted state of lamellae, making the lamellae slip easier. As the annealing temperature rises, expect for the expectedly increasing long period and lamellae thickness, the new secondary lamellae appear at rigid amorphous regions, the lateral dimension also lengthens, while the inclination angle does not change, leading to the stabler lamellae during stretching and abundant micropores. Since the long period, lamellae thickness, and the secondary lamellae remain the same state when annealed at the same temperature, the different lamellae stability of two films and microporous structure after stretching should attribute to the difference of lateral dimensions after annealing.

Osmoregulatory profiles and gill histological changes in Nile tilapia (Oreochromis niloticus) exposed to lambda-cyhalothrin

Lambda-cyhalothrin is a synthetic pyrethroid that mimics the structure and insecticidal properties of pyrethrin, a natural insecticide derived from chrysanthemums. In fish, it disrupts the nervous system, causing motor paralysis and several other alterations associated with varying levels of mortality. This study aimed to evaluate osmoregulatory responses and histological changes in the gills of Oreochromis niloticus chronically exposed to a sublethal dosage (0.86 μg/L) of lambda-cyhalothrin. The mean serum values for Na2+, K+, Cl−, Ca2+, pH, lactate, H+, HCO3, and glucose along to degree of tissue change (DTC) at 24, 96, 168, and 240 h post-exposure (hpe) were evaluated. Lambda-cyhalothrin affected the neuronal motor function at 24 hpe, followed by the increase of the K+, Ca2+, H+, and glucose levels in the exposed group, compared to the control group. Lactate and H+ levels in the exposed group were higher than those in the control group at 168 and 240 hpe respectively. HCO3, and Cl- levels increased at 240 hpe, although there was no change in the pH values. DTC was higher in treated fish than in control fish, but there were no significant differences among time-exposure. The changes detected ranged from hyperemia of the branchial vasculature, eosinophilic granulocytic cell infiltration, mucous cell hyperplasia, and partial fusion of secondary lamellae at 24 hpe to vascular aneurysm formation, and necrosis of the lamellar epithelium at 240 hpe. Thus, a sublethal dosage of lambda-cyhalothrin in the long-term is toxic for Nile tilapia, characterized by hypokalemia, hypercalcemia, hyperglycemia, and respiratory alkalosis, followed by time-dependent histological changes.

Biomarker Evaluation in Nile Tilapia (Oreochromis niloticus) to Assess the Health Status of Aquaculture Areas in the Seven Lakes of San Pablo

The seven lakes of San Pablo have been subjected to different degrees of stresses brought about by intensive aquaculture, sewage discharges, and other anthropogenic disturbances, which could have serious implications on the health of these ecosystems. This study was conducted to assess the health condition of cage aquaculture areas in the lakes using biomarkers in the adult Nile tilapia (Oreochromis niloticus). A total of 84 cultured fish samples consisting of 12 individuals per lake were examined to determine the condition factor (K-factor); hepatosomatic index (HSI); splenosomatic index (SSI); and histopathological features of the liver, spleen, and gills. The measured values for K-factor are suggestive of isometric growth and good health condition; however, fish from Sampaloc Lake had relatively lower values in comparison to the other groups. Although all liver samples had normal microstructure, the HSI of fish in Sampaloc and Palakpakin Lakes was significantly reduced than those obtained in fish from Lakes Bunot, Calibato, and Yambo. All spleen samples showed melanomacrophage centers (MMCs), with fish in Calibato Lake having higher SSI compared to the others. The majority of the gill samples showed minimal to mild clubbing of secondary lamellae, thrombosis, and aneurysm. Based on the endpoints considered in this study, Yambo Lake had the most optimal condition for fish culture. Lakes Sampaloc, Palakpakin, and Mohicap – on the other hand – had the lowest environmental status.

Immunological status and histopathological appraisal of farmed Oreochromis niloticus exposed to parasitic infections and heavy metal toxicity

The aim of this study is to assess the toxicity of some heavy metals and parasitic infection in fishes as well as the immunological status of these fishes infected with different parasites. Between January 2018 and January 2019, 360 Nile tilapia (Oreochromis niloticus) near four farms and in the Nile River in Giza were examined for external and internal parasites. In addition, samples were expressed for two genes using quantitative real-time polymerase chain reaction. Samples were also taken from muscles and water for toxicological analysis of different heavy metals. In the skin, the mean TNF-α levels in the monogenea and mixed protozoan parasites (Trichodina and Myxobolus spp.) were 18.00 ± 0.67 and 13.65 ± 0.54, respectively. In the gills, the mean TNF-α of monogenea, Centrocestus formosanus, and encysted metacercaria (EMC) with monogenea group means was 20.45 ± 0.74, 23.00 ± 0.74, and 25.78 ± 0.74, respectively. In muscles with EMC, the mean TNF-α level was 14.67 ± 0.70. In livers with EMC, the mean TNF-α level was 26.78 ± 0.70. In the skin, the mean IL-1β level in monogenea and protozoan parasites (Trichodina and Myxobolus spp.) was significantly different (25.00 ± 0.69 and 15.00 ± 0.43, respectively). In the gills, the mean IL-1β level of the monogenean group was 21.00 ± 0.79, whereas C. formosanus showed the significantly highest value (27.00 ± 0.74). The mean IL-1β level of EMC with the monogenea group was 24.00 ± 1.54. Results showed that the level of Zn, Pb, Cu, and Cd was the highest in tissues of fish than permissible limits (PLs). Histopathological examination of different examined tissues exhibited serious pathological alterations. Monogenetic trematodes were detected in the examined fish, and their presence was accompanied by hyperplasia and fusion of the secondary gill lamellae. EMC of digenetic trematodes was frequently observed in the gills and in the cartilage rod. In conclusion, the parasite infection can upregulate the immunological cytokines with different levels with different infections.

Diagnosis of Vibriosis Involving Members of the Splendidus Clade in Cultured European Seabass (Dicentrarchus labrax) in Turkey

This study aimed to investigate a case of acute vibriosis associated with Splendidus clade members in cultured European sea bass (Dicentrarchus labrax) from the Aegean Region of Turkey. Moribund fish (150-250 g) had lesions on their skin that ranged from small patches to shallow haemorrhagic ulcers and fin rot. Gram-negative bacteria were isolated from the liver, kidney, and spleen of affected fish and through 16S rRNA gene sequencing these isolates were identified as Vibrio pomeroyi, Vibrio crassostreae, Vibrio sp., and Vibrio anguillarum. V. anguillarum was isolated from only one examined fish, the bacterium seems less important to this case of vibriosis than the other identified vibrio species. All isolates were susceptible to flumequine, kanamycin, oxytetracycline, florphenicol and enrofloxacine. Oval shaped Amyloodinium spp. on the skin and Diplectanum aquans among the secondary lamellae of gills were determined as secondary pathogens. Parasitical asphyxia, epithelial cells hyperplasia in the gills was observed in addition to typical histopathological findings associated with Vibriosis. In this study, V. crassostreae and V. pomeroyi have been reported for the first time in Turkey as a fish pathogen.

Sublethal concentrations of dichlorvos and paraquat induce genotoxic and histological effects in the Clarias gariepinus.

Non-target aquatic organisms such as fish may be impacted by agricultural activities through the run-off of pesticides from farms into aquatic ecosystems. In this study, the genotoxic (erythrocytic micronuclei) and histological effects of sublethal concentrations (1% and 10% of 96-h median lethal concentration (LC50) values) of two pesticides (dichlorvos and paraquat) were evaluated in Clarias gariepinus (the African Sharptooth Catfish) for 28 days. The 96-h LC50 of dichlorvos and paraquat against fingerlings of C. gariepinus was 730 μg/L and 50 μg/L, respectively. There was a significant dose-dependent increase (p<0.05) in micronuclei in the erythrocytes of exposed C. gariepinus (2.00±0.82 ‰ to 3.25±1.26 ‰ for dichlorvos and 2.25±0.96 ‰ to 4.75±0.96 ‰ for paraquat) compared to control (0.75±0.96 ‰) by day 28. Gill histological alterations such as mild to severe necrosis and blunting of secondary lamellae were observed in C. gariepinus exposed to higher sublethal concentrations of both pesticides. This study showed that non-target aquatic organisms like C. gariepinus may be at risk of adverse biological effects from exposure to pesticides from non-point sources. We recommend environmental monitoring and sensitization on responsible pesticide use to stakeholders. This will forestall potential adverse ecological effects in aquatic ecosystems.

Multi-biomarker approach to assess the acute effects of cerium dioxide nanoparticles in gills, liver and kidney of Oncorhynchus mykiss

Cerium oxide nanoparticles (CeO2-NP) have already been detected in the aquatic compartment, however, the evaluation of potential ecotoxicological effects on biota are scarce. The present study aimed to assess the toxic effects of CeO2-NP in Oncorhynchus mykiss in different organs/tissues (gills, liver and kidney) after acute exposure (96 h) to three concentrations: 0.25, 2.5 and 25 mg/L. Oxidative stress response (catalase - CAT; glutathione S-transferases - GSTs), lipid peroxidation (thiobarbituric acid reactive substances - TBARS), Na+/K+-ATPase activity, genotoxicity (genetic damage index - GDI) and histopathology (organ's pathological indices) were evaluated. CAT activity was increased in gills and decreased in liver of fish exposed to the highest CeO2–NPs concentration tested. However, GSTs and Na+/K+-ATPase activities and TBARS levels were not significantly altered in analysed organs. CeO2–NP caused marked changes in the gills (aneurysms, blood capillary congestion, lamellar hypertrophy and hyperplasia, secondary lamella fusion and epithelial lifting), in liver (pyknotic nucleus, hyperemia, enlargement of sinusoids and leucocyte infiltration) and kidney (shrinkage of the glomeruli, enlargement of the Bowman space, tubular degeneration and nuclear hypertrophy). Moreover, a semi-quantitative histopathological scoring system (pathological index) confirmed significant alterations in the three organs of all exposed fish. Furthermore, a significant increase of GDI indices observed in gills and liver, for all tested concentrations, indicated a dose-dependent effect. The present study suggests that the release of CeO2-NP into the aquatic environment promotes biochemical, genotoxic and histopathological damages in fish. However, the mechanisms underlying the occurrence of such effects require further investigation.

Chlorpyrifos mediated oxidative damage and histopathological alterations in freshwater fish Oncorhynchus mykiss in Northern Pakistan

The intensive applications of chlorpyrifos (CPF) in agricultural production have resulted in lethal effects on the environment, particularly on aquatic fauna. Thus, present study was aimed to assess the haematological responses, antioxidant enzymes (superoxide dismutase [SOD] and catalase [CAT]) activity, acetylcholinesterase enzyme (AChE) inhibition and histopathological alterations in liver and gill tissues of cold-water fish rainbow trout (Oncorhynchus mykiss) in their native habitat, when exposed to CPF. In total, 240 fingerlings were subjected to various CPF concentrations (0, 2, 4 and 6 μg/L) for acute and sub-lethal toxicity tests. Results revealed that increasing CPF concentration and exposure time have resulted in reduced erythrocyte count, haemoglobin concentration and haematocrit level; however, leucocyte count was increased. Additionally, decrease in AChE activity was also observed with increasing concentration. CPF concentrations at lowest exposure duration induced slight increase of SOD and CAT activity while the high exposure durations (14 and 21 days) exhausted the activity of antioxidant enzymes. Structural damages produced by CPF in liver tissues were hyperaemia, dilated central veins, sinusoids and degenerative changes, while the lesions observed in gill tissue were curling of secondary lamella, cell degeneration, cell necrosis, narrowing of water channels, hyperplasia, oedematous changes, fusion of secondary lamella and sloughing.

Disease Progression in Lake Trout (Salvelinus namaycush) Experimentally Infected With Epizootic Epitheliotropic Disease Virus (Salmonid Herpesvirus-3).

Epizootic epitheliotropic disease virus (salmonid herpesvirus-3; EEDV) is responsible for the death of millions of hatchery-raised lake trout (Salvelinus namaycush) in the Laurentian Great Lakes Basin. However, little is known about its biology, pathology, tropism, and host interactions. In this study, the presence and disease progression of EEDV were evaluated following exposure of naïve juvenile lake trout to EEDV via bath immersion under controlled laboratory conditions (n = 84 infected; n = 44 control). Individual tissues (n = 10 per fish), collected over 6 weeks, were analyzed for viral load by quantitative polymerase chain reaction, gross and histopathologic changes, and virus cellular targets using in situ hybridization. Skin, fin, and ocular tissues were the earliest viral targets and yielded the highest viral loads throughout the course of infection. Early gross lesions included exophthalmia, ocular hemorrhage, fin congestion, and hyperemia of visceral blood vessels. Advanced disease was characterized by multifocal to coalescing erosions and ulcerations of the skin, and congestion of visceral organs. Microscopically, there was cellular degeneration and necrosis in the epidermis and spleen, and lymphohistiocytic perivasculitis of the dermis, omentum, and the epicardium. EEDV DNA was first detected by in situ hybridization in epithelial cells of the epidermis, with subsequent labeling in the epithelial lining of primary and secondary gill lamellae. During advanced disease, EEDV was detected in endothelial and dendritic cells as well as blood monocytes. This study characterized EEDV tissue tropism and associated pathologic features, to guide research aimed at understanding EEDV disease ecology and improving strategies for disease control.