Physiological (haematological, growth and endocrine) and biochemical biomarker responses in air-breathing catfish, Clarias batrachus under long-term Captan® pesticide exposures.

The sub-lethal toxicity of Captan® on selected haematological (Hemoglobin, Haematocrit, Mean Corpuscular Hemoglobin) growth (Condition factor, Hepatosomatic Index, Specific Growth Rate), biochemical (serum glucose, protein), and endocrine parameters (growth hormone, T3 and T4) in Clarias batrachus was examined under chronic exposures. Captan® was administered at predetermined exposure concentrations (0.53 and 1.06 mg/L) and monitored on days 15, 30, and 45 of the experimental periods. The experimental groups showed significantly lower values (p < 0.05) of haemoglobin content, hematocrit, MCH in Captan® exposed fish compared to control. Serum protein, k-factor and SGR were significantly lower in exposed fish. Endocrine responses (T3 and T4) emerged as the most sensitive biomarker category, depicting modulated responses between sub-chronic exposure at day-15 and chronic responses at day-45. In general, biomarker depictions indicate that Captan® exposures are capable of inducing stress-specific effects at the biochemical and physiological levels negatively impacting the overall health and longevity of such animals.

Intraperitoneal injection of genistein affects the distribution and metabolism of cholesterol in female yellow catfish Tachysurus fulvidraco.

Genistein is an abundant phytoestrogen in soybean. This study aimed to determine the effects of genistein on cholesterol distribution and metabolism in female yellow catfish. Three hundred fish (49.2 ± 1.4 g) were randomly divided into five treatments and received intraperitoneal injections as follows: (1) blank, no injection; (2) control, vehicle only; (3) E2, 17ß-estradiol at 10 µg·g-1 body weight; (4) low genistein doses, genistein at 10 µg·g-1 body weight; (5) high genistein doses, genistein at 100 µg·g-1 body weight. Both high and low genistein doses significantly reduced (p < 0.05) serum TC and LDL-C 24 h after injection. Moreover, the high genistein doses significantly reduced (p < 0.05) serum HDL-C. Both high and low doses of genistein significantly increased (p < 0.05) hepatic TC. Only high genistein doses significantly increased (p < 0.05) ovary TC. In the liver, both high and low genistein doses significantly increased (p < 0.05) protein and mRNA expression of ldlr. Meanwhile, high genistein doses significantly decreased (p < 0.05) mRNA expression of hmgcr. In ovary tissue, high genistein doses significantly decreased (p < 0.05) mRNA expression of cyp11a1. These results suggested that genistein affected the cholesterol distribution in female yellow catfish. Both high and low doses of genistein reduced cholesterol content in blood and increased its content in the liver by increasing the uptake of blood cholesterol. Meanwhile, high genistein doses may inhibit hepatic cholesterol synthesis. Additionally, high genistein doses could increase cholesterol transfer from serum into the ovary and disturb cholesterol conversion to pregnenolone.

Biomarkers for assessing chronic toxicity of carbamazepine, an anticonvulsants drug on Pangasianodon hypophthalmus (Sauvage, 1878).

In recent times, carbamazepine (CBZ) as an anticonvulsants drug has raised attention because of its safety concern in the aquatic environment. The present study aimed to evaluate the sub-lethal effects of CBZ (1%, 0.1 % and 0.01 % of 96 h LC50) on P. hypophthalmus for 60 days based on haematological, biochemical, and genotoxicity biomarkers. Chronic exposure of CBZ altered blood profiles (total erythrocyte count, packed cell volume, haemoglobin) and serum biomarkers such as alkaline phosphates, cholesterol, lactate dehydrogenase and transaminase enzymes. Oxidative stress biomarkers such as superoxide dismutase (SOD) and catalase (CAT) activity were also substantially affected in all treatments. Genotoxicity study revealed the formation of micronucleus in erythrocytes of exposed fish. Integrated Biomarker Response (IBR) study showed cholesterol, serum glutamic oxaloacetic transaminase (SGOT) in serum and SOD, CAT in liver tissue are the best organ-based enzyme biomarkers. The present report concludes that an environmentally realistic concentration of CBZ can pose a serious threat to aquatic organisms.

Effects of anesthetic MS-222 on stress and reproduction of South American silver catfish (Rhamdia quelen) males.

Anesthesia is a common practice used in fish research and aquaculture. It is important to understand anesthetic effects on the animal and tissues of interest to ensure validity of data and to improve animal welfare in research and fish production endeavors. The production of some captive fish species is only possible by imposing artificial reproduction procedures, and manipulation of fish for these purposes is a stressor. The purpose of this study, therefore, was to evaluate effects of different concentrations (100, 200, and 300 mg/L) of the anesthetic MS-222 (tricaine methanesulfonate) on cortisol concentrations and effects on sperm quality in Rhamdia quelen. After hormonal induction of gamete production, 28 sexually mature males were randomly assigned to treatments, and milt and blood samples were collected. Anesthesia induction time, motility rate, sperm concentration and morphology, plasma cortisol concentrations, and reproductive hormone concentrations (testosterone, 17-α-hydroxyprogesterone, and estradiol) were evaluated. Sperm motility was greater in the control than 300 mg/L treatment group but did not differ among the control, 100, and 200 mg/L groups. The estradiol concentration was greater in non- anesthetized than anesthetized Rhamdia quelen, but plasma cortisol concentrations did not differ among treatment groups (182.50 ±â€¯42.03 ng/mL). The anesthetic MS-222 at concentrations of 100, 200, and 300 mg/L did not inhibit the stress response due to handling of Rhamdia quelen males. In addition, treatment with MS-222 was not effective in inhibiting detrimental effects on sperm quality because this treatment was associated with impaired sperm motility and lesser concentrations of plasma estradiol.

Tissue-specific genotoxicity and antioxidant imbalance of titanium dioxide nanoparticles (NPTiO2) and inorganic lead (PbII) in a neotropical fish species.

The aquatic environment is the major recipient of wastes containing nanoparticles and other contaminants. Titanium dioxide nanoparticles (NPTiO2) are one of the most produced and used nanoparticle worldwide. This study investigated the toxicity of NPTiO2, as well as the toxicity interaction between NPTiO2 and lead (Pb), in response to genetic and biochemical biomarkers using freshwater fish Rhamdia quelen, as an animal model. The results showed genotoxicity in blood and kidney tissues. No effect of NPTiO2 alone or in co-exposure with Pb on liver genotoxicity were observed. Alterations in the antioxidant hepatic enzymes activities, as well as alterations in glutathione levels indicated that NPTiO2 alone or in co-exposure with Pb can cause antioxidant imbalance. The lipid peroxidation was also raised after exposure to NPTiO2. In general, the results of this study indicated that both NPTiO2 alone and their co-exposure with Pb are capable of producing significant toxic effects in short-term exposure.

Effect of nitrite exposure on haematological status, oxidative stress, immune response and apoptosis in yellow catfish (Pelteobagrus fulvidraco).

Nitrite can cause fishes poisoning. This study evaluated the effects of nitrite exposure on haematological status, ion concentration, antioxidant enzyme activity, immune response, cytokine release and apoptosis in yellow catfish. In this study, yellow catfish were exposed to three levels of nitrite (0, 3.00 and 30.00 mg L-1) for 96 h. The results showed that nitrite poisoning could lead to blood deterioration (red blood cell and hemoglobin reduced; white blood cell and methemoglobin elevated), ion imbalance (Na+ and Cl- declined; K+ elevated), oxidative stress (total antioxidant capacity, superoxide dismutase, catalase and glutathione peroxidase activities declined; malondialdehyde accumulation), immunosuppression (lysozyme activity, 50% hemolytic complement, immunoglobulin M, respiratory burst and phagocytic index declined) and cytokines release (TNF, IL 1 and IL 8 elevated). In addition, nitrite poisoning could induce up-regulation of antioxidant enzymes (Cu/Zn-SOD, Mn-SOD, CAT and GPx), cytokines (TNF, IL 1 and IL 8) and apoptosis (P53, Bax, Cytochrome c, Caspase 3, Caspase 9, ERK and JNK) genes transcription. This study suggesting that the nitrite exposure triggers blood deterioration, disrupts the ionic homeostasis, induces oxidative stress, immunosuppression, inflammation and apoptosis in yellow catfish.

Impact of herbicide pretilachlor on reproductive physiology of walking catfish, Clarias batrachus (Linnaeus).

Herbicide pretilachlor is widely used in paddy fields to control annual weeds. The present study has been carried out in walking catfish, Clarias batrachus, to evaluate the impact of herbicide pretilachlor on reproductive physiology after chronic exposure. Based on the median lethal concentration value (96 h), fish were exposed to three nominal test concentrations of pretilachlor ((SL-I (1/20th LC50), SLII (1/15th LC50), and SL-III (1/10th LC50)) for 30, 45, and 60 days after which plasma sex steroid profile, plasma vitellogenin concentration, and gonadal aromatase activity were analyzed in both sexes. Plasma concentration of testosterone decreases in herbicide-exposed male fish. Significant increase in plasma 17ß-estradiol, plasma vitellogenin concentration, and gonadal aromatase activity were observed in herbicide-exposed male fish. All these alterations in reproductive parameters in male fish are dependent on concentration and exposure duration of herbicide. On the other hand, significant decrease in plasma concentration of testosterone was observed in female fish which was also dependent on concentration and exposure duration of herbicide. No significant changes in plasma 17ß-estradiol concentrations, plasma vitellogenin concentration, and gonadal aromatase activity were observed in female fish. Above findings clearly suggested that herbicide pretilachlor acts as endocrine disruptor in fish and affects overall reproductive physiology of fish, but its ability to induce reproductive toxicity in male and female differs considerably.

Titanium dioxide nanoparticles-induced cytogenotoxicity and alterations in haematological indices of Clarias gariepinus (Burchell, 1822).

The application of titanium dioxide (TiO2) nanoparticles (NPs) in the manufacturing of consumer products has increased tremendously and with the potential to induce deleterious effects on aquatic biota. There have been reports on metal oxide NP toxicity in aquatic organisms, however, information on cytotoxicity and genotoxicity of TiO2 NPs on the African catfish, Clarias gariepinus, is scarce. In this study, we investigated the genotoxicity and haematotoxicity of TiO2 NPs in C. gariepinus using the micronucleus (MN) assay and haematological analysis, respectively. Juvenile C. gariepinus were exposed to 6.25, 12.5, 25.0, 50.0 and 100.0 mg L-1 concentrations of TiO2 NPs for 7 and 28 days. Benzene (0.05 mL L-1) and dechlorinated tap water were used as positive and negative controls, respectively. Data of the MN showed a significant (p < 0.05) concentration-dependent increase in the frequency of MN at both exposure periods in comparison to negative control. Red blood cells, haematocrit, platelets and heterophils significantly reduced with an increased mean corpuscular haemoglobin concentration and lymphocytes at the 7-day exposure period, while in the 28-day exposure period, mean cell volume, mean corpuscular haemoglobin and lymphocytes had a significant increase in comparison with the negative control. This study indicates that TiO2 NPs induced cytogenetic and haematological alterations in C. gariepinus and is of relevance in biodiversity and aquatic health management.

Hematological and immunological responses in the African catfish Clarias gairepinus exposed to sublethal concentrations of herbicide Ronstar®.

The aim of the study was to investigate the effects of sublethal concentrations (0.3, 0.6 and 1.2 mg L-1) of the herbicide Ronstar on the hematology and some immune parameters in Clarias gariepinus juvenile (mean weight and length 58.72 ± 2.46 g and 27.60 ± 1.62 cm, respectively). The hematological and some immune parameters were studied for 21 days in a static renewal bioassay system in which the water and the herbicide were changed daily. The erythrocyte count, hemoglobin concentration (Hb), and packed cell volume (PCV) were significantly (p < 0.05) reduced in the treatment groups. When compared with the control, there were significant (p < 0.05) leucocytosis, lymphocytosis, neutropenia and monocytopenia in the treatment groups. Both the mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV) were reduced ((p < 0.05) in the Ronstar-exposed fish. The result showed that the treated fish suffered hypochromic microcytic anemia. The total immunoglobulin and phagocytic indices (phagocytic capacity and phagocytic index) were significantly (p < 0.05) reduced in the treatment groups. while the respiratory burst was significantly (p < 0.05) increased in the treatment groups. The result showed that exposure to Ronstar had adverse effects on the hematology and immunocompetency of the fish.

Toxicological response of silver catfish (Rhamdia quelen) after acute exposure to a commercial insecticide containing thiamethoxam.

This study assessed the hematological, enzymatic and osmoregulatory responses of silver catfish (Rhamdia quelen) exposed to sublethal concentrations (1.125 and 3.750 µg/L) of a commercial thiamethoxam-containing insecticide used on rice crops. Groups of 6 fish per tank (in triplicate, n = 3, total 54 fish) were exposed for up to 96 h to different concentrations of the compound. After this period, fish were placed in clean water for 48 h. Two fish from each tank (6 per treatment) that had been exposed to the insecticide for 24 h were anesthetized with eugenol and blood was collected to evaluate hematological and biochemical parameters. Blood, liver and muscle were collected for determination of metabolic parameters, plasma cortisol, Cl-, Na+ and K+ levels and H+-ATPase and Na+/K+-ATPase activity in the gill. H+-ATPase activity was higher in fish exposed to 1.125 µg/L insecticide at 24 h compared to control (0.0 µg/L). Differences in cortisol levels were evidenced throughout the experimental period. These results indicated that exposure to the insecticide changed the hematological, biochemical and metabolic profile of the animals, suggesting concern about environmental safety. Therefore, we discourage the use of this pesticide in areas that come into contact with water bodies inhabited by fish.

Morphological, haematological and biochemical changes in African catfish Clarias gariepinus (Burchell 1822) juveniles exposed to clotrimazole.

Clotrimazole (CLO) is an imidazole fungicide used in human and veterinary medicine for treating fungal infection. This study evaluated the changes in morphological, haematological and biochemical indices in Clarias gariepinus juveniles exposed to CLO. After the acute exposure, the 96 h LC50 value of CLO determined by probit analysis was 38.79 mgl-1. Based on this value, fish were exposed to sublethal concentrations of 7.76, 3.89, 1.94 and 0.00 mgl-1 (control) of CLO for 21 days and were allowed to recover for 7 days. The result revealed no significant effect on the hepatosomatic index and condition factor of the exposed fish. There were concentration and time-dependent significant decreases in red blood cell (RBC), haemoglobin (Hb), packed cell volume (PCV) and mean corpuscular volume (MCV) with significant increase in the white blood cell (WBC), mean corpuscular haemoglobin concentration (MCHC), and mean corpuscular haemoglobin (MCH) in the exposed group when compared with the control. A mixed trend was observed in the levels of neutrophils, lymphocytes, monocytes and eosinophils. The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and glucose values significantly increased, while protein levels were reduced (p < 0.05) throughout the 21-day exposure and the 7-day recovery period. The present research indicated that CLO may have potential toxic effect on non-target organisms especially fish and, therefore, should be monitored in the aquatic ecosystem.

Acrylamide-induced hematotoxicity, oxidative stress, and DNA damage in liver, kidney, and brain of catfish (Clarias gariepinus).

This study was carried out to explore the possible deleterious impacts of acrylamide (ACR) on catfish (Clarias gariepinus). The estimation of mortalities, the examination of the clinical picture, the evaluation of blood parameters, oxidative stress, DNA damage, and the histopathological picture were performed in the liver, kidney, and brain samples of the experimentally ACR-exposed catfish. The 96 hours LC50 value was estimated to be 133 mg/L by the hydrostatic method. Fish were reared in water containing four different concentrations of ACR as follows: 20%, 40%, 60%, and 80% of the estimated LC50 for 2 weeks. Abnormal behavioral, clinical, and postmortem responses were depicted. The anemic response including significant decreases in red blood cells, hemoglobin, and packed cell volume following the ascending concentrations of ACR were recorded. The malondialdehyde was significantly increased, whereas reduced glutathione level, superoxide dismutase, and total antioxidant capacity were significantly decreased. The DNA fragmentation assay illustrated a clear laddering pattern in all the tested organs. Notably, the brain was the most influenced organ. It is presumed that ACR contamination showed adverse impacts on the catfish.

Contaminant levels and endocrine disruptive effects in Clarias gariepinus exposed to simulated leachate from a solid waste dumpsite in Calabar, Nigeria.

Solid waste dumpsites (SWDs) and landfills are significant sources of emerging contaminants to terrestrial and aquatic ecosystems. We have studied the endocrine disruptive effects of simulated leachate from a solid waste dumpsite in Calabar, Nigeria. Juvenile C. gariepinus were exposed to simulated leachate, diluted to 0:0 (control), 1:10, 1:50, 1:100 for 3, 7 and 14 days. In addition, 17ß-estradiol (E2: 100 µg/L)-exposed positive control group was included. Hepatic transcripts for the genes encoding vitellogenin (vtg), estrogen receptor-α (er-α), and aromatase (cyp19a1) were analyzed by real-time PCR. Protein expression for Vtg and Cyp19 were measured by immunoblotting and plasma steroid hormones (testosterone: T and E2) were measured using enzyme immunoassay (EIA). Soil samples from the dumpsite were analyzed for selected group of contaminants showing that DEHP was the only detected phthalate ester (PE) at 1300 ±â€¯400 ng/g. Further, perfluoroalkyl substances (PFASs) such as PFBS, PFOS, PFHxA, PFOA, PFNA, PFDA, PFUnDA and PFDoDA were detected in the soil samples from the dumpsite. We observed significant and apparent concentration-dependent increases in mRNA (vtg, er-α, and cyp19a1) and their corresponding functional protein products, after exposure to the simulated leachates. Further, the simulated leachate produced concentration-specific changes in plasma E2 and T levels. In general, the estrogenic endocrine and reproductive alterations in the exposed fish may directly be attributed to the PFASs and DEHP detected at the dumpsites. However, in addition to PFASs and DEHP, there could be other estrogenic contaminants in the leachate. Given the rapid utilization, for residential purposes, and increases in human settlement in areas around the Lemna SWDs, this study provides a direct cause-and-effect evidence of the potential contaminants at the dumpsite with significant environmental and human health consequences.

Metabolic responses to dietary carbohydrate/lipids ratios in neotropical hybrid catfish (♂Pseudoplatystoma corruscans×♀Pseudoplatystoma fasciatum).

The purpose of this study was to assess the effect of different carbohydrate and lipid (CHO/L) ratios on the performance and energy metabolism of hybrid catfish (♂Pseudoplatystoma corruscans × â™€ Pseudoplatystoma fasciatum). One hundred and sixty-eight fish (104.9±16.5 g BW) were distributed into 24 100-L tanks. The experiment was performed using a randomised block design with four CHO/L ratios (0.45, 1.00, 1.66 and 2.85) and six replications. Growth performance, protein content, glucose and triglycerides in plasma, muscle and liver, and the hepatic activity of the malic and glucose-6-phosphate dehydrogenase (G6PD) enzymes were measured after 60 feeding days. No significant differences were observed in growth performance, protein and triglycerides of plasma and muscle, hepatic protein or malic enzyme activity. CHO/L: 2.85 provided the highest plasma and liver glucose, while CHO/L: 0.45 showed high liver triglycerides. A linear effect was found for the hepatic activity of G6PD and dietary starch levels (R2=0.93). The hepatic activity of G6PD was greater in CHO/L=2.85 than for CHO/L: 0.45. In conclusion, the limit of dietary starch inclusion and lipids were 15% and 9.00%, respectively (CHO/L: 1.66), and this level did not affect the energy metabolism of the juvenile hybrid catfish.

Assessment of hematological, hepato-renal, antioxidant, and hormonal responses of Clarias gariepinus exposed to sub-lethal concentrations of oxyfluorfen.

Little is known about the effects of oxyfluorfen, a diphenyl ether herbicide, exposure on the African catfish (Clarias gariepinus) health. Consequently, the existing investigation was designed to highlight the impacts of oxyfluorfen exposure on C. gariepinus hematological indices, liver and kidney functions, reproductive hormones, and oxidative status. Furthermore, a consequent 10-day depuration period was adopted to evaluate the recovery of the disturbed indicators to normal values. In the first experiment, the 96-h lethal concentration 50 (LC50) of oxyfluorfen for C. gariepinus was determined using probit analysis. Next, in a second experiment, 180 healthy fish (average initial body weight: 164.23 ±â€¯0.24) were randomly assigned to 4 experimental groups exposed to 0, 1/10, 1/8, or 1/5 96-h LC50 of oxyfluorfen. The hematological profile, hepatic enzymes, kidney damage byproducts, reproductive hormones, oxidative stress, and lipid peroxidation indicators together with acetylcholinesterase (AChE) content were assessed. A histopathological examination of the hepatic, renal, brain, and testicular tissues was accomplished. Moreover, the expression of the oxidative stress-related gene was carried out. The results showed that 96-h LC50 of oxyfluorfen for C. gariepinus was 11.698 mg/L. Exposure to sublethal levels of oxyfluorfen induced macrocytic hypochromic anemia, leukopenia, lymphopenia, monocytopenia, and eosinopenia. Also, a concentration-dependent increase in alanine transaminase, alkaline phosphatase, aspartate transaminase, urea, creatinine, catalase, and malondialdehyde was detected following oxyfluorfen exposure together with upregulation of catalase gene. But, significant concentration-dependent reductions in AChE, glutathione transferase, reduced to oxidized glutathione ratio, estradiol, and testosterone activities were recorded. These biochemical alterations were accompanied by pathological perturbations in hepatic, renal, brain, and testicular tissues. Following 10 days of recovery, only the hematological impairments were abolished. Conclusively, the herbicides oxyfluorfen could induce multiple negative impacts on C. gariepinus with oxidative stress as a probable underlying mechanism. Additionally, a recovery period of 10 days was not enough to restore these impairments.

Ameliorative effect of Spirulina platensis against lead nitrate-induced cytotoxicity and genotoxicity in catfish Clarias gariepinus.

The present study was designed to investigate the protective role of dietary supplementation of Spirulina platensis (SP) against cytotoxic and genotoxic effects of lead nitrate in Clarias gariepinus. Four groups of fishes were used: first group as control which fed on basal diet, second group fed on basal diet and exposed to (1 mg/L of lead nitrate), third group fed on diet containing 0.25% SP and exposed to (1 mg/L of lead nitrate), and fourth group fed on diet containing 0.5%SP and exposed to (1 mg/L of lead nitrate). Fish samples were taken at 2nd and 4th week of exposure. The hematological indices of lead nitrate-exposed group were decreased significantly compared to the control group at 2nd and 4th week of exposure. Lead nitrate caused a significant increase in the percentage of poikilocytosis, micronuclei, and apoptotic cells as well as comet tail length and olive tail moment compared with the control group at 2nd and 4th week of exposure. The highest level of damage was found on 4th week of exposure with all parameters. Dietary inclusion of SP ameliorated these cytotoxic and genetic changes, as well as this amelioration was concentration and time dependent. Consequently, the present study proposed that the addition of SP to the fish diet can be used as a promising protective agent to oppose cytotoxic and genotoxic effects of lead nitrate in aquaculture. Graphical abstract.

Hematological analysis of Ctenopharyngodon idella, Megalobrama amblycephala and Pelteobagrus fulvidraco: Morphology, ultrastructure, cytochemistry and quantification of peripheral blood cells.

The grass carp (Ctenopharyngodon idella), blunt snout bream (Megalobrama amblycephala) and yellow catfish (Pelteobagrus fulvidraco) are economically important fishes in China. Fish hematological features, especially the type and number of peripheral blood cells, are crucial for the evaluation of fish health and the diagnosis of fish diseases. Since the automatic blood cell count equipment for human is not suitable for fishes, the manual method is critical in the quantification of fish blood cells. To make sense of the comparison and interpretation of the blood cell count studies in different articles, the standardization of blood cell classification is necessary. In this study, erythrocytes (red blood cell, RBC), thrombocytes (TC) and leucocytes (i.e. white blood cells, WBC, including lymphocytes, neutrophils and monocytes) were well distinguished in blood smears with Giemsa staining and confirmed by transmission electron microscopy. RBC, TC and WBC were directly counted with an improved Neubauer counting chamber in a modified diluting solution. The differential leucocyte count (DLC) was carried out in blood smears. In view of the labeling characteristics of peroxidase (PO) positivity in neutrophils and non-specific esterase (α-ANAE) positivity in monocytes, PO positive cell percentage and α-ANAE positive cell percentage were also determined in cytochemistry staining smears. No difference was found for the percentages of neutrophils and monocytes between Giemsa staining and cytochemistry staining. The standardized classification, normal count ranges and sizes of the peripheral blood cells by the present systemic studies will provide useful references for monitoring the health status of grass carp, blunt snout bream and yellow catfish.

Toxicity bioassay and sub-lethal effects of diazinon on blood profile and histology of liver, gills and kidney of catfish, Clarias gariepinus / Toxicidade bioensaio e efeitos sub-letais do diazinon no perfil sangüíneo e histologia do fígado, brânquias e rim de peixe-gato, clarias gariepinus

Abstract The catfish, Clarias gariepinus, was exposed to different acute concentrations (5-10 mg/l) of diazinon and the Lc50 value was recorded as high as 7.3 mg/l for 96 hours. The fishes exposed to three sub-lethal levels of diazinon (0.73, 1.095 and 1.46 mg/l) for 30 days showed that the pesticide induces changes in different blood parameters. Number of red blood cells (RBC), haemoglobin level and haematocrit values were elevated whereas white blood cells (WBC) count was reduced. Various blood indices like mean corpuscular volume (MCV), mean corpuscular haemoglobine (MCH) and mean corpuscular haemoglobine concentration (MCHC) vary insignificantly in the fish treated with diazinon. Glucose level and activity level of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) was increased in Clarias gariepinus exposed to diazinon. Protein level in plasma of fish treated with pesticide was changed but the change was insignificant. Histological changes in the liver, gills and kidney of fishes exposed to diazinon were apparent when compared to control. Hepatocytes necrosis and bleeding were more distinct in the fishes exposed to pesticide. Glomerulus hypertrophy and bleeding in kidneys; and fusion and degeneration of secondary lamellae and epithelial hyperplasia in gills were also observed in the exposed fish.

Resumo O peixe-gato, Clarias gariepinus, foi exposto a diferentes concentrações agudas (5-10 mg / l) de diazinon e o valor de Lc50 foi registrado tão alto quanto 7,3 mg / l por 96 horas. Os peixes expostos a três níveis sub-letais de diazinon (0,73, 1,095 e 1,46 mg / l) por 30 dias mostraram que o pesticida induz mudanças nos diferentes parâmetros sanguíneos. O número de glóbulos vermelhos, o nível de hemoglobina e os valores do hematócrito foram elevados, enquanto a contagem de leucócitos foi reduzida. Vários índices sanguíneos, como volume corpuscular médio (VCM), hemoglobina corpuscular média (HCM) e concentração de hemoglobina corpuscular média (CHCM) variam insignificantemente nos peixes tratados com diazinon. Nível de glicose e nível de atividade de AST e ALT foi aumentado em Clarias gariepinus expostos a diazinon. O nível de proteína no plasma de peixes tratados com pesticidas foi alterado, mas a mudança foi insignificante. Alterações histológicas no fígado, brânquias e rins de peixes expostos ao diazinon foram aparentes quando comparados ao controle. A necrose e o sangramento de hepatócitos foram mais distintos nos peixes expostos ao agrotóxico. Hipertrofia do glomérulo e sangramento nos rins; e fusão e degeneração de lamelas secundárias e hiperplasia epitelial em brânquias também foram observadas nos peixes expostos.

Photo-thermal regulation of neuropeptide Y (NPY) expression in ovarian follicles and ovarian activity of the catfish, Clarias batrachus.

Authors have recently reported a gradual increase in neuropeptide Y expression in the ovarian follicles of Clarias batrachus with the progression of oogenesis, coinciding with increasing photoperiod and temperature. This indicates the involvement of photoperiod and temperature in controlling NPY expression. Therefore, a study was designed to investigate the role of photoperiod and temperature in regulation of NPY expression in ovarian follicles. The catfish were exposed to different photo-thermal regimes during the late-quiescence and late-recrudescence phases for one month, and the expression of NPY was analyzed along with other ovarian activities. Though the exposure of catfish to long photoperiod induced a marginal increase (1.5 fold) in NPY expression in follicular cells, the high temperature stimulated its expression more effectively (6-10 fold), irrespective of photoperiodic exposures. Exposure to long photoperiod and high temperature together induced NPY expression maximally in granulosa and thecal cells of fully grown oocytes, but exposure to low temperature decreased its expression significantly. The oogenic and steroidogenic activities were also promoted simultaneously after the exposure to high temperature and long photoperiod alone or in combination. However, the low temperature exposure suppressed the ovarian activities leading to atresia of advanced follicles. Thus it is suggested that photoperiod and temperature both affect NPY expression and ovarian recrudescence in fish but the influences of temperature seem to be more prominent.

Effects of Microencapsulated Saccharomyces cerevisiae on Growth, Hematological Indices, Blood Chemical, and Immune Parameters and Intestinal Morphology in Striped Catfish, Pangasianodon hypophthalmus.

This study investigated the effects of dietary probiotic Saccharomyces cerevisiae in the striped catfish, Pangasianodon hypophthalmus, which is an important aquaculture species. Freeze-dried microencapsulated probiotic S. cerevisiae with guar gum was performed and used for fish feed supplementation. Striped catfish were fed for 120 days with one of three experimental diets: basal diet (control), basal diet supplemented with 106-CFU S. cerevisiae g-1 diet (S. cerevisiae 106), and basal diet supplemented with 108-CFU S. cerevisiae g-1 diet (S. cerevisiae 108). The S. cerevisiae-supplemented diets significantly improved growth performance including growth rate and feed conversion ratio over 120 days of culture period (P < 0.05). The rate of survival was similar in all experimental groups. Supplementation with S. cerevisiae did not significantly affect whole body proximate composition (P > 0.05). In addition, probiotic S. cerevisiae had no effects on hematological indices and blood chemistry values (glucose, cholesterol, triglycerides, protein, albumin, blood urea nitrogen, chloride, calcium, magnesium, iron, and phosphorus) (P > 0.05). However, dietary S. cerevisiae led to increases in humoral immune parameters including total immunoglobulin, lysozyme, and alternative complement activities (P < 0.05). Dietary S. cerevisiae led to increase intestinal villus height in the anterior part of intestine (P < 0.05). Taken together, while the dietary S. cerevisiae had no detectable effects on hematological indices and several metabolic indicators, significant beneficial probiotic effects were observed on rates of growth, feed conversion ratio, and immune parameters.