Resistance to oxidative stress in a freshwater fish Channa punctatus after exposure to inorganic arsenic

The biochemical toxicity of arsenic trioxide (As^III) in a freshwater edible fish Channa punctatus has been studied on exposures ranging from 7 to 90 d. The arsenic concentration increased exponentially in liver, kidney, gills, and muscles of fish up to 60 d of exposure to arsenic. However, arsenic concentration in these tissues declined at 90 d of exposure. This relationship between period of exposure and concentration of arsenic in selected tissues suggests an adaptive response of fish to arsenic. Furthermore, exposure to arsenic-induced lipid peroxidation in these organs increased initially at 7 d of exposure; however, it decreased up to 60 d of exposure but increased again at 90 d of treatment. Values of reduced glutathione (GSH) reflected the observations of lipid peroxidation. The role of GSH in this adaptive response has been discussed.     

Bisphenol A induced toxicity in blood cells of freshwater fish Channa punctatus after acute exposure

The widespread use of bisphenol A (BPA) has led to its ubiquity in the natural environment. It is extensively incorporated into different industrial products and is associated with deleterious health effects on both public and wildlife. The current trial was conducted to determine the toxic potential of bisphenol A using various parameters viz haematological, biochemical, and cytological in freshwater fish Channa punctatus. For this purpose, fish were exposed to 1.81 mg/l (1/4 of LC₅₀) and 3.81 mg/l (1/2 of LC₅₀) of BPA along with positive (acetone) and negative controls (water) for 96 h. The blood samples were collected at 24, 48, 72, and 96 h post-exposure. Compared to the control group, fish after acute exposure to BPA showed a significant decrease in HB content, number of red blood cells, PCV values whereas a significant increase in WBCs count was recorded with an increase in the exposure period. Besides, oxidative stress (determined as malondialdehyde content) increased as BPA concentration increased. Further, the activity of different antioxidant enzymes like catalase, and superoxide dismutase decreased significantly after treatment. Results also showed significantly increased frequency of morphological alterations, nuclear changes, and increased DNA damage potential of BPA in red blood cells. Further structural analysis of erythrocytes in maximally damaged group using Scanning Electron Microscopy was performed. The study concludes that BPA exhibits genotoxic activity and oxidative stress could be one of the mechanisms leading to genetic toxicity.     

Effect of ammonia-stress on the total autolytic levels of proteins in tissues of an air-breathing fish,Channa punctatus (Bloch)

G season-specific effect of a sub-lethal ambient ammonium chloride concentration on the total autolysis of protein in different tissues of the Indian air-breathing murrel,Chauna punctatos (Bloch), has been demonstrated. While its effect on the autotytie levels of protein of different tissues (except white muscle) was marginal in the winter-adapted fish, the same in the summer-adapted fish was more pronounced. In general a reduction in the autolysic levels of the tissue protein of the ammonium chloride-stressed fish was observed. In certain tissues like white muscle of an ammonium chloride-stressed fish and gill of the ammonium hydroxide-stressed fish, augmented levels of autolysis were noticed. The present findings suggest that the accumulation of amino acids in different tissues of the ammonia-stressed fish, as observed earlier, can be explained best by mechanisms other than ammonia induced increased breakdown of proteins.     

Modulatory effect of copper on nonenzymatic antioxidants in freshwater fish Channa punctatus (Bloch.)

Effect of the low level of copper exposure on nonenzymatic antioxidants was studied in a freshwater fish Channa punctatus (Bloch.). Fish were exposed to cupric chloride at the concentration of 10 ppb for 4 wk (28 d) in a static culture condition. Copper significantly (p < 0.001) increased the serum ceruloplasmin level and total iron-binding capacity. A significant (p < 0.05) increase in reduced glutathione level was recorded in all of the tissues. With regard to nonprotein thiols, copper decreased their level in the liver, but increased it in the gill. The protein-bound thiols remained unaltered except for an increase in the liver. Metallothionein (MT) induction was observed in liver only. Copper exposure had no significant effect on the ascorbic acid level and induced no lipid peroxidation over control values. It is suggested that by modulating the ceruloplasmin level, copper indirectly protects the fish, as it facilitates conversion of pro-oxidant iron to nonoxidant iron. It also induces an array of antioxidants that may be beneficial to fish in the case of oxidative stress resulting from chemical pollutants.     

Evaluation of genotoxic and oxidative stress response to dimethoate in freshwater fish Channa punctatus (Bloch)

Abstract

Dimethoate is one of the organophosphate insecticides widely used in agriculture throughout the world and is an inhibitor of cholinesterase in animals. The objective of the present study was to detect oxidative stress and DNA damage induced by dimethoate in the freshwater fish Channa punctatus (C. punctatus). The LC₅₀-96 h value of technical grade dimethoate was estimated at 19.10 μg L^-1 in a semi-static system and, on the basis of the LC₅₀ value, three concentrations were determined. The fish were exposed to these concentrations of dimethoate for 96 h and samplings were done at 24 and 96 h for assessment of oxidative stress and DNA damage. After exposure to dimethoate, the level of superoxide dismutase declined while lipid peroxidation, glutathione, induction of micronucleus and DNA damage were increased in C. punctatus as the concentration and exposure time increased. Thus our results suggest that dimethoate induces genotoxic effects which invariably accompanied and correlated with oxidative stress.     

Neurotoxicological assessment of pendimethalin in freshwater fish Channa punctata Bloch

Over the years, indiscriminate usage of pesticides has resulted in situations which are not conducive for a good environment. In aquatic toxicology, fishes have been developed as established models for studying toxic responses of xenobiotics including pesticides. Pendimethalin (PD), an herbicide, is widely present in the aquatic environment, but little is known regarding its potential neurotoxicity in fish. The present study was conducted on Channa punctata Bloch exposed to sub-lethal doses of PD (0.5 and 0.8 ppb) for 96 h. The exposure resulted in alterations in epinephrine levels in the fish brain. Epinephrine levels decreased significantly in a dose dependent manner with increase in the PD exposure. A marked decrease in the activity of acetylcholinesterase along with reduction in Na⁺-K⁺-ATPase and monoamine oxidase activity was also observed. In comparison with the corresponding controls, the sub-lethal doses of PD also caused significant changes in the oxidative stress markers (lipid peroxidation and carbonyl derivatives of protein oxidative destruction levels) and antioxidant defenses (reduced glutathione levels, catalase, glutathione-s-transferase activity) in brain tissue. Our results reflect that a detailed investigation is warranted regarding the toxicity potential of PD.     

Profenofos induced DNA damage in freshwater fish, Channa punctatus (Bloch) using alkaline single cell gel electrophoresis

The aim of the present study was to evaluate the induced genotoxicity (DNA damage) due to organophosphate pesticide profenofos (PFF) in gill cells of freshwater fish Channa punctatus using single cell gel electrophoresis (SCGE)/Comet assay. The 96h LC(50) value of PFF (50% EC) was estimated for the fish species in a semistatic system and then three sub-lethal of LC(50) concentrations viz the sub-lethal 1, sub-lethal 2 and sub-lethal 3 concentrations were determined as 0.58ppb, 1.16ppb and 1.74ppb, respectively. The fish specimens were exposed to these concentrations of the pesticide and the gill tissue samplings were done on 24h, 48h, 72h and 96h post exposure for assessment of DNA damage in terms of percentage of DNA in comet tails. In general, a concentration dependent response was observed in the gill cells with induction of maximum DNA damage at the highest concentration of PFF. The results of the present investigation indicated that PFF could potentially induce genotoxic effect in fish, even in sub-lethal concentrations and SCGE as a sensitive and reliable tool for in vivo assessment of DNA damage caused by the genotoxic agents.     

High expression of the mRNA of cytochrome P450 and phase II enzymes in the lung and kidney tissues of cattle

The objective of this study was to investigate the tissue-specific mRNA expression of different cytochrome P450 (CYP) isoforms, UDP glucuronsyl transferase 1A1 (UGT1A1) and glutathione-S-transferase (GSTA1) in the different tissues (liver, mammary gland, lungs, spleen, kidney cortex, heart, masseter muscle and tongue) of cattle, using quantitative real-time polymerase chain reaction (qPCR). CYP1A1-like mRNA was expressed in all of the tissues examined, including the liver, with the highest expression level in the kidney. CYP1A2-, 2E1- and 3A4-like mRNAs were only expressed hepatically. Interestingly, significant expression of CYP2B6-like mRNA was recorded in the lung tissue, while CYP2C9-like mRNA was expressed in the liver and kidney tissues of the cattle examined. UGT1A1- and GSTA1-like mRNAs were expressed in all of the examined tissues, except the mammary glands, and the highest expression levels were recorded in the kidney. The high expression of UGT1A1 in the lung tissue and GSTA1 in the liver tissue was unique to cattle; this has not been reported for rats or mice. The findings of this study strongly suggest that the liver, kidneys and lungs of cattle are the major organs contributing to xenobiotics metabolism.     

Studies on the proteolytic enzymes of invertebrates constituting fish food

Studies were carried out on the proteolytic activity of trypsin and pepsin-like enzymes of invertebrates consituting fish food. Relations between proteolytic activity of enzymes, pH, and temperature were established.     

Propiconazole induced toxicological alterations in brain of freshwater fish Channa punctata Bloch

Fungicides are a class of pesticides which are used indiscriminately in large amounts and pose a serious threat to the environment. Propiconazole (PCZ) is a systemic foliar fungicide with a broad range of activity. The potential of this fungicide to induce toxicity has not been fully explored. The present study was designed to investigate the dose dependent neurotoxic effect of propiconazole (PCZ), with Channa punctata Bloch as a model organism. Effect of PCZ on the brain specific enzyme activity such as acetylcholinesterase (AChE), monoamine oxidase (MAO) and Na⁺-K⁺-ATPase was determined in the fish brain tissue exposed to sub-lethal concentrations (0.5 and 5 ppm) for 96 h. Also, levels of oxidative stress reflected by various enzymatic and non-enzymatic antioxidants were measured. Neurotransmitter (epinephrine) level was also assessed. PCZ exposure induced oxidative stress as reflected by the significant increase in fish brain lipid peroxidation and protein carbonyl content with decrease in reduced glutathione levels, as well as the significant inhibition of glutathione dependent metabolizing enzymes and CAT activities. In addition, AChE, MAO and Na⁺-K⁺-ATPase activities were significantly lowered along with reduction in epinephrine levels in PCZ exposed fishes than those of the control in a dose dependent manner. Also, histopathological alterations were observed in fish brain of the treated fishes. The results point towards the potential neurotoxicity in the fish caused by PCZ exposure but the application of these findings will need more detailed study before they can be established as special biomarkers for toxicity monitoring the aquatic environment.     

Study on properties and regulation peculiarities of glycogenolysis enzymes in fish skeletal muscles depending on peculiarities of the species motor activity

The activity values, properties and peculiarities of activation of glycogen phosphorylase (GP, EC 2.4.1.1) and glycogen phosphorylase kinase (GPK, EC 2.7.138) were studied in the white skeletal muscle of fishes differing in motor behavior. No differences in the GP and GPK activity levels were revealed in porgy Diplodus annularis (L.), horse mackerel Trachurus mediterraneus ponticus, trout Salmo trutta morphario, scorpionfish Scorpaena porcus, flounder Scophtalnus maeoticus maeoticus, and carp Cyprinus carpio; however, properties of the isolated enzymes and peculiarities of formation of their activated forms during swimming in a hydrodynamic tube are determined by functional peculiarities of the muscle tissue and are associated with the motor activity character of the species. The more rapid ion regulation prevails in fishes capable for the burst swimming type (scorpionfish, trout). The glycogenolysis hormonal regulation leading to a change of the GPK activity index has been found in other species.     

A study of lipid- and water-soluble arsenic species in liver of Northeast Arctic cod (Gadus morhua) containing high levels of total arsenic

In the present study liver samples (n = 26) of Northeast Arctic cod (Gadus morhua), ranging in total arsenic concentrations from 2.1 to 240 mg/kg liver wet weight (ww), were analysed for their content of total arsenic and arsenic species in the lipid-soluble and water-soluble fractions. The arsenic concentrations in the lipid fractions ranged from 1.8 to 16.4 mg As/kg oil of liver, and a linear correlation (r² = 0.80, p < 0.001) was observed between the total arsenic concentrations in liver and the total arsenic concentrations in the respective lipid fractions of the same livers. The relative proportion of arsenolipids was considerably lower in liver samples with high total arsenic levels (33–240 mg/kg ww), which contained from 3 to 7% of the total arsenic in the lipid-soluble fraction. In contrast liver samples with low arsenic concentrations (2.1–33 mg/kg ww) contained up to 50% of the total arsenic as lipid-soluble species. Arsenic speciation analysis of the lipid-soluble fractions of the livers, using reversed-phase high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC–ICP-MS), revealed the presence of several arsenolipids. Three major arsenic-containing hydrocarbons (C₁₇H₃₉AsO, C₁₉H₄₁AsO and C₂₃H₃₇AsO) and five arsenic-containing fatty acids (C₁₇H₃₅AsO₃, C₁₉H₃₉AO₃, C₁₉H₃₇AsO₃, C₂₃H₃₇AsO₃ and C₂₄H₃₇AsO₃) were identified using HPLC coupled to quadrupole time-of-flight mass spectrometry (qTOF-MS). Arsenobetaine was the major arsenic species in the water-soluble fraction of the livers, while dimethylarsinate, arsenocholine and inorganic arsenic were minor constituents. Inorganic arsenic accounted for less than 0.1% of the total arsenic in the liver samples.     

Effect of ascorbic acid deficiency on the uptake of iodine by thyroid and non-thyroid tissues of an air-breathing freshwater fish Channa punctatus Bloch

Using ¹³¹I as tracer, iodine uptake by various thyroid and non-thyroid tissues has been reported in Channa punctatus in which vitamin C deficiency was experimentally induced by feeding vitamin C deficient diet to a level when morphological deficiency syndromes appeared. This was compared with a parallel control, fed a complete diet. The study showed a highly significant decrease in iodine uptake by thyroid tissues in vitamin C deficient fish as compared to the controls. However, the blood and other non-thyroid tissues recorded a significant increase in absorption and distribution of iodine. These findings suggested hypofunctioning of thyroid gland due to a prolonged deficiency of vitamin C.     

Expression of antioxidant enzymes in rat kidney during ischemia-reperfusion injury

The effect of ischemia-reperfusion on activity, protein and m-RNA levels of catalase, copper-zinc and manganese containing superoxide dismutases and glutathione peroxidase, the enzymes that are involved in free radical detoxification was studied in rat kidney. Ischemia alone did not alter either the activities or protein levels of superoxide dismutase and glutathione peroxidase. However, catalase activity was found to be inhibited to 82% of control. The inhibition of catalase was due to the inactivation of the enzyme as there was no significant change in enzyme protein level. Reperfusion following ischemia, however, led to a significant decrease in both the activities as well as the protein levels of all the antioxidant enzymes. The observed overall decrease in total superoxide dismutase activity was the net effect of a decrease in copper-zinc superoxide dismutase while manganese superoxide dismutase activity was found to be increased following reperfusion. This observed increased manganese superoxide dismutase activity was the result of its increased protein level. The mRNA levels for catalase, superoxide dismutases, and glutathione peroxidase were observed to be increased (100–145% of controls) following ischemia; reperfusion of ischemic kidneys, however, resulted in a significant decrease in the levels of mRNAs coding for all the enzymes except manganese superoxide dismutase which remained high. These results suggest that in tissue, the down regulation of the antioxidant enzyme system could be responsible for the pathophysiology of ischemia-reperfusion injury.     

Population ecology of the paddy field-dwelling fish Channa gachua (Günther) (Perciformes, Channidae) in Sri Lanka

A population of Channa gachua in a small irrigation canal that supplies rice fields was studied by monthly sampling over 2 years. The population density was positively correlated with the rainfall and varied from 0.34 to 0.95 individuals m⁻². The growth parameters of the von Bertalanffy growth equation determined on monthly size–frequency data were L_x = 179 mm total length and K =0.50. Overall male to female ratio was 0.82 and there were more females than males in the middle size classes. Spawning occurred throughout the year, but all evidence indicated enhanced breeding during major rainy periods of May to July and October to December. The length at first spawning was 102 mm, which is reached in about 20 months. Fecundity, which varied between 389 and 2130, was positively correlated with gonad weight, body weight and total length. Longevity and natural mortality were estimated as 6 years and l.27 yr⁻¹, respectively. However, 99% of the population appeared to live for only 3 years. The mean biomass, average annual production and turnover ratio of the population were 7.35 g m⁻², 12.06 g m⁻² and 1.64, respectively.     

西花蓟马或二斑叶螨为害的菜豆对两者间后取食者体内保护酶和解毒酶活性的影响

【目的】害虫取食后会导致植物的防御反应;取食同种植物的不同种害虫其生理适应性可能不同。本研究旨在阐明一种害虫取食后的植物对后取食的另一种害虫虫体酶活性的影响。【方法】采用生化分析法研究了西花蓟马Frankliniella occidentalis 2龄若虫或二斑叶螨Tetranychus urticae雌成螨为害后的菜豆对后取食不同时间下的二斑叶螨第2若螨和雌成螨及西花蓟马2龄若虫和雌成虫体内保护酶[过氧化物酶(POD)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)]和解毒酶[多功能氧化酶(MFO)、羧酸酯酶(Car E)、谷胱甘肽-S-转移酶(GSTs)和乙酰胆碱酯酶(Ach E)]活性的影响。【结果】二斑叶螨雌成螨取食西花蓟马为害菜豆5 h时,POD,CAT和SOD这3种保护酶的活性均明显高于取食健康植株(P0.01),取食蓟马为害的菜豆18 h时只有POD活性低于取食健康植株(P0.01);二斑叶螨第2若螨取食蓟马为害菜豆后只有CAT活性在5 h时明显高于取食健康植株(P0.01)。二斑叶螨雌成螨取食蓟马为害菜豆5 h时,解毒酶MFO和Car E的活性受到抑制(P0.01),但GSTs和Ach E活性均比取食健康菜豆高(P0.01);取食18 h时,只有MFO的活性变化与5 h不同。第2若螨取食蓟马为害菜豆只有MFO的活性不论在5 h还是18 h时明显高于取食健康菜豆(P0.01)。西花蓟马取食二斑叶螨雌成螨为害菜豆时,雌成虫体内的3种保护酶的活性不论取食5 h还是18 h均明显升高(P0.01),但2龄若虫只有CAT活性在这两个时间段下明显升高(P0.01)。西花蓟马雌成虫取食螨害菜豆5 h时,解毒酶活性的变化同二斑叶螨雌成螨,取食18 h时只有GSTs活性变化状态与取食5 h不同;西花蓟马2龄若虫取食螨害菜豆时除GSTs外解毒酶的活性变化在这两个时间下正好相反。【结论】西花蓟马或二斑叶螨为害的菜豆能诱导后取食的二斑叶螨和西花蓟马产生一系列应激生化反应,且两种害虫成虫体内所有的保护酶和解毒酶活性在5 h时变化状态相同,但在其余时间和虫态下酶活性的变化状态不同。说明这两种昆虫体内保护酶和解毒酶活性的变化既有共性,又与害虫种类、虫(螨)态、取食时间相关,两种害虫对虫害植物的生理适应性不完全相同。