Effect of sublethal concentration of metasystox on selected oxidative enzymes,tissue respiration,and hematology of the freshwater air-breathing fish,Channa striatus (Bleeker)

Sublethal exposure (LC₅₀, 1.7 mg/liter) of metasystox decreased succinic dehydrogenase activity and tissue respiration, while lactic dehydrogenase activity increased in gill, brain, muscle, liver, and kidney tissues of Channa striatus (Bleeker). Metasystox also decreased blood parameters like WBC, MCV, MCH, and MCHC. Increase observed in RBC, PCV, and Hb was statistically significant. Possible reasons for these changes are discussed.     

Acute toxicity of organophosphorous pesticide diazinon and its effects on behavior and some hematological parameters of fingerling European catfish (Silurus glanis L.)

Diazinon is commonly used for pest control in the agricultural fields surrounding freshwater reservoirs. So this study was conducted to determine the acute toxicity of this organophosphorous pesticide, contaminating aquatic ecosystems as a pollutant, and its effects on behavior, and some hematological parameters of fingerling European catfish, Silurus glanis. Diazinon was applied at concentrations of 1, 2, 4, 8, 16, 32, and 64 mg L⁻¹. The water temperature in the experimental units was kept at 16 ± 1 °C. The number of dead fishes significantly increased in response to diazinon concentrations 2-64 mg L⁻¹ (p < 0.05). With increasing diazinon concentrations, the fishes exposed duration 1 to 96 h significantly increased the number of dead fishes (p < 0.05 for each cases). The 1, 24, 48, 72, and 96 h LC₅₀ values (with 95% confidence limits) of diazinon for fingerling European catfish were estimated as 14.597 (12.985-16.340), 12.487 (11.079-14.471), 8.932 (7.907-10.348), 6.326 (no data because of p > 0.05), and 4.142 (no data because of p > 0.05) mg L⁻¹, respectively. Compared to the control specimens, fish after an acute exposure to diazinon was significantly lower erythrocyte, leukocyte, hemoglobin, hematocrit, MCV, MCH, and MCHC values (p < 0.05). In addition, it was also showed a significantly negative correlation between these hematological parameters and exposure times of diazinon (p < 0.01).     

Intoxication effects of lindane (γ-BHC) on the carbohydrate metabolism in the climbing perch, Anabas testudineus (Bloch)

The effects of an acute lethal (0.59 mg/liter) and a sublethal (0.075 mg/liter) concentration of lindane on the levels of glycogen (liver and muscle), glucose (blood), and lactic acid (liver, muscle, and blood) of a freshwater fish, Anabas testudineus (Bloch) were determined. A marked decrease in the liver glycogen and significant increase in blood glucose and muscle glycogen at 1 hr of exposure to 0.075 mg/liter lindane was noted. These results indicate extensive utilization of energy stores in the liver and simultaneous buildup of fuel reserves in the muscle. After 3 hr of exposure, glycogenesis possibly becomes operative in liver through the Cori cycle. The activity of the cycle was observed in the fish in all the subsequent periods of exposure studied. At 120 hr, the decreases observed in muscle and liver glycogen indicate near exhaustion of glycogen stores. Though changes in glycogen content of both muscle and liver were similar in 0.59 mg/liter lindane, they have less adaptive value since mortality of fish was significantly high at all three peroids studied.     

Impact of sodium cyanide on catalase activity in the freshwater exotic carp, Cyprinus carpio (Linnaeus)

The Cyprinus carpio fingerlings on exposure to lethal (1 mg/L) and sub lethal concentrations (0.066 mg/L) of sodium cyanide showed inhibition in the activity of catalase. The disruption of catalase activity in freshwater fish, C. carpio is demonstrated in the present study using UV–visible spectrophotometer at 240 nm using hydrogen peroxide as a substrate. It suggests toxic effects of sodium cyanide and consequent accumulation of hydrogen peroxide in the functionally different tissues namely, liver, gill, muscle and brain. This might lead to cellular damages, and create widespread physiological disturbance. The results suggest that catalase activity can be a good diagnostic tool for sodium cyanide toxicity in biomonitoring programme.     

Deltamethrin induced alterations of hematological and biochemical parameters in fingerlings of Catla catla (Ham.) and their amelioration by dietary supplement of vitamin C

The present study was carried out to investigate the sub-lethal toxicity of technical grade deltamethrin (a synthetic pyrethroid) of concentration 1.61 μg/L (1/3rd of 96 h LC₅₀) on hematological and biochemical parameters of catla (Catla catla) fingerlings and its amelioration through dietary vitamin C. The deltamethrin exposed fishes were fed with different levels of supplemented vitamin C such as 50, 250, 500 and 1000 mg/kg diet to see its ameliorating effect by assaying hematological parameters viz. total erythrocyte count (TEC), total leukocyte count (TLC), hemoglobin content (Hb), total serum protein, albumin, globulin, albumin–globulin ratio and biochemical parameters such as lactate dehydrogenase (LDH), acetylcholine esterase (AChE), alanine amino transferase (ALT), aspartate amino transferase (AST), total adenosine triphosphatase (ATPase), magnesium adenosine triphosphatase (Mg²⁺-ATPase) and sodium potassium adenosine triphosphatase (Na⁺, K⁺-ATPase) activities. The finding of this study showed that deltamethrin had negative effect on the hematological and biochemical parameters of Catla catla. The experimental group, which was exposed to deltamethrin and fed with normal diet showed significantly lower values (P ? 0.05) of all parameters studied except ALT activity. This might be due to possible disruption of hematopoiesis and proteosynthesis. However, the fish fed with varied concentration of vitamin C in diets neutralized the toxic effect of deltamethrin, as evidenced by significantly lowered hematological and biochemical response. Vitamin C @ 1000 mg/kg diet was the most effective in amelioration of harmful effect of deltamethrin on hematological and biochemical parameters of catla fingerlings. The result suggests that vitamin C can be effectively used to neutralize the toxic effect of deltamethrin on catla.     

Protective effect of melatonin administration on abamectin-induced immunotoxicity in Spodoptera litura (Insecta: Lepidoptera)

In vertebrates, many studies verified the immunomodulatory effect of melatonin in various tissues. Its exact role in lower organisms like insects has been very sketchy. The present study deals with understanding the immunomodulatory effect of melatonin in pesticide exposed insects. Total hemocyte count, Differential hemocyte count, Prophenoloxidase activity, and nodulation mechanism at different time intervals were studied. Results showed the abamectin results in significant increase (p < 0.01) in haemocytes numbers at 6, 48, and 72 h. Abamectin toxicity was counteracted by melatonin, with decreasing the hemocytes at 2, 4, and 12 h. Prophenoloxidase activity and protein content (p < 0.001) at 48 and 72 h of Melatonin + abamectin were slightly decreased. There was a significant decrease in nodule formation in 12–24 h in melatonin treated groups and it was clearly visible at 6 h. Increased Prohemocytes, Plasmatocytes, and Oenocytoids numbers decline in melatonin treatment. Melatonin treatment increased the survival rate on pesticide exposed insects. Results suggest that melatonin exposure significantly reduces the toxicity in pesticide exposed larvae which in turn brings back immunological profile in a time dependent manner.     

Toxicity and metabolism of endosulfan and its effect on oxygen consumption and total nitrogen excretion of the fish Macrognathus aculeatum

Experiments were conducted with the freshwater fish Macrognathus aculeatum to study the toxicity and metabolism of endosulfan and the effect of the pesticide on the oxygen consumption and total nitrogen excretion. The 96-hr LC₅₀ value was 3.5 ± 0.2 ppb. In brain, gills, gut, liver, and kidney, endosulfan was metabolized to endosulfan sulfate, but this appears to be only an intermediary step as the nontoxic endosulfan ether was found only in the liver and kidney, the principal organs of elimination of toxicants in fish. The pesticide, both at sublethal and lethal concentrations, decreased oxygen consumption and total nitrogen excretion.     

亚致死浓度烯啶虫胺对水稻抗性物质及褐飞虱生殖参数的影响

为明确烯啶虫胺对褐飞虱Nilaparvata lugens的防控效果,采用稻茎浸渍法测定亚致死浓度烯啶虫胺对水稻生理生化指标以及褐飞虱雌成虫繁殖力的影响。结果表明,亚致死浓度烯啶虫胺处理后,水稻中草酸含量在第2天时无明显变化,在第4天时升高了20.5%;类黄酮含量分别升高了9.6%和40.6%;游离氨基酸含量分别下降了20.1%和42.4%;蔗糖含量在第2天时与对照间无显著差异,在第4天时升高了38.5%。亚致死浓度烯啶虫胺对褐飞虱生殖存在显著影响,雌成虫羽化2 d和4 d时,卵巢中可溶性蛋白含量分别下降了31.2%和40.9%;脂肪体中可溶性蛋白含量分别下降了19.0%和38.8%。亚致死浓度烯啶虫胺处理抑制了雌成虫卵巢发育,褐飞虱卵黄原蛋白（Nilaparvata lugens vitellogenin,NlVg）基因表达量在第 2 天时与对照间无显著差异,在第 4 天下降了57.5%;同时显著影响了褐飞虱生殖力,雌成虫产卵量减少了58.1%,产卵历期缩短了36.7%,寿命缩短了28.0%,但对雌成虫产卵前期无显著影响。表明亚致死浓度烯啶虫胺处理后可能通过诱导水稻次生代谢产物含量上升来提高水稻对褐飞虱的抗性,而且对褐飞虱繁殖力也有显著影响。     

高效氯氰菊酯亚致死浓度对桃小食心虫成虫体内解毒酶活性的影响

为研究高效氯氰菊酯亚致死浓度对桃小食心虫Carposina sasakii Matsumura雌、雄蛾体内解毒酶活性的影响,采用药膜法,以LC10、LC20和LC40浓度的高效氯氰菊酯处理桃小食心虫成虫24 h,分别测定药剂压力解除后0、6、12和24 h桃小食心虫雌、雄蛾体内细胞色素P450单加氧酶7-乙氧基香豆素-O-脱乙基酶（ECOD）、羧酸酯酶（CarE）和谷胱甘肽S-转移酶（GSTs）的活性,并分析其动态变化。结果表明:与对照相比,高效氯氰菊酯LC10浓度处理能抑制桃小食心虫成虫的ECOD比活力,且随处理浓度增加,高效氯氰菊酯对ECOD活性的诱导作用逐渐体现,LC40浓度处理组ECOD活性显著高于对照;此外,LC20和LC40浓度处理组可诱导桃小食心虫雄蛾CarE和GSTs比活力的增加,但对于雌蛾则结果相反。当药剂压力解除后,随着处理时间的延长,成虫体内ECOD、CarE和GSTs活性总体表现为先增加后降低,而药剂浓度越高对其解毒酶的诱导或抑制作用越显著,且存在一定性别差异。研究显示,从短期响应来看,桃小食心虫雌、雄蛾体内的3种解毒酶在高效氯氰菊酯亚致死浓度胁迫后均表现较为活跃,酶活性呈现出先增加后降低的动态变化。由于雌、雄蛾个体的生理机能以及对药剂敏感性的差异,这种生理响应机制存在一定的剂量和性别差异。     

多杀霉素亚致死浓度对棉铃虫幼虫生理及代谢的影响

为明确田间使用多杀霉素亚致死浓度对棉铃虫Helicoverpa armigera幼虫的影响,用含多杀霉素亚致死浓度LC₂₅的人工饲料持续饲喂棉铃虫3龄幼虫,并对饲喂后其体重、取食量、累计蛹化率、蛹发育历期和蛹重等生长发育及脂肪体内甘油三脂（triglyceride,TG）含量和相关基因SREBP、FAS和HSL表达情况进行测定。结果表明,多杀霉素对棉铃虫的亚致死浓度LC₂₅为0.21 mg/kg;多杀霉素亚致死浓度处理4~6 d后,棉铃虫3龄幼虫体重分别为0.065、0.263和0.329 g,较对照显著降低;处理6 d后,其取食量为0.082 g,较对照显著降低;处理4~7 d后,其累计化蛹率分别为60.90%、63.20%、65.50%和65.50%,较对照显著降低。多杀霉素亚致死浓度处理后,棉铃虫蛹发育历期由对照9.89 d显著延长至10.74 d,单头蛹重为0.274 g,显著低于对照的0.324 g;其脂肪体TG含量较对照显著降低。多杀霉素亚致死浓度处理24~72 h后,参与脂肪酸合成信号通路中重要基因SREBP和FAS的相对表达量较对照均显著下调,而参与脂肪代谢的重要基因HSL则较对照显著上调。     

Catalase activity as a potential vital biomarker of fish intoxication by the herbicide aminotriazole

The objective of this study was to investigate the effects of the herbicide 3-amino-1,2,4-triazole (AMT) on the activities of catalase and lactate dehydrogenase (LDH) in blood (plasma and erythrocytes) and eight solid tissues of goldfish, Carassius auratus. Injection of goldfish with AMT (0.5 mg/gww AMT in 0.9% NaCl) resulted in a significant decrease in catalase activity 24 h post-injection in most tissues investigated. In white and red muscle, kidney, heart, liver, brain and erythrocytes the activity of catalase decreased by 61%, 69%, 64%, 48%, 40%, 27% and 26%, respectively, in comparison to the values seen in animals injected with physiological saline (0.9% NaCl). However, the activity of LDH decreased only in red muscle (by 19%) after AMT injection, whereas in plasma it increased by 137%. Protein carbonyl levels, a measure of oxidative damage to proteins, did not change in plasma in goldfish injected with AMT and total hemoglobin levels in AMT-injected fish, although lower compared with uninjected controls, did not differ from values in saline-injected controls. It is proposed that catalase activity in erythrocytes and white muscle might be usefully developed as a potential marker for fish intoxication by aminotriazole and other related herbicides.     

Effect of methyl parathion and chlorpyrifos on certain biomarkers in various tissues of guppy fish, Poecilia reticulata

Tests of acute toxicity were performed on the most common species of aquarium fish, Poecilia reticulata. Guppies (P. reticulata) were exposed to progressive concentrations of methyl parathion (MP) and chlorpyrifos (CPF); a semi-static method according to guidelines of OECD was used. Tests of acute toxicity were conducted using 10 fish for each separate concentration and for the control group. The results were subjected to probit analysis to determine the 96 h LC₅₀ values. The 96 h LC₅₀ values of MP and CPF to P. reticulata were 8.48 ppm/L (5.98–10.89) and 0.176 ppm/L (0.313–0.224) respectively. In addition, behavioral changes at each concentration were observed for the individual fish. Fish were exposed for 96 h to different sublethal concentrations of MP and CPF (¼ LC₅₀, 1/8 LC₅₀ and 1/10 LC₅₀) and their oxidative stress-induction potential was estimated in brain, liver and gills of fish. MDA content is induced in all tissues but maximum rise was observed in gills (161% and 153% for MP and CPF respectively). With regard to antioxidant defense system (ADS), GSH level decreased in the brain, liver and gills of tissues of MP treated fishes (22%, 6% and 13% respectively) and showed increase in brain and gills CPF treated (23% and 21% respectively). CAT, GST, GR and SOD levels fluctuated in all treatment groups relative to the control. Brain AChE showed dose-dependent inhibition in fish exposed to the higher concentrations reached 45% and 66% for MP and CPF respectively. Collective findings demonstrated that pesticide exposure of fish induced an increase in MDA and fluctuated ADS along with inhibited AChE. These findings may be used as valuable biomarkers for evaluation of water pollution.     

Biotransformation of the Insecticide Lindane by the White Rot Basidiomycete Phanerochaete chrysosporium

Biotransformation of the insecticide lindane by the white rot basidiomycete Phanerochaete chrysosporium has been investigated in liquid cultures. Some polar metabolites and carbon dioxide were produced from the pesticide. Among the metabolites identified were tetrachlorocyclohexene, tetrachlorocyclohexene epoxide and tetrachlorocyclohexenol. When used as a substrate, tetrachlorocyclohexene was also converted by the fungus to tetrachlorocyclohexenol, polar metabolites and carbon dioxide. Three incubation conditions leading to low and high peroxidase production were assayed. Data from these experiments, as well as in-vitro incubations with purified enzymes, ruled out any involvement of the peroxidases in lindane biotransformation and mineralization. Moreover, 1-aminobenzotriazole (a P450 inactivator) drastically reduced pesticide metabolism. Conversely, phenobarbital (a P450 inducer) did not significantly increase lindane breakdown.     

两种昆虫生长调节剂对黑腹果蝇和斑翅果蝇的生物活性

为探讨昆虫生长调节剂氟铃脲和虱螨脲对黑腹果蝇Drosophila melanogaster和斑翅果蝇D.suzukii的毒性机制,采用室内生测法测定氟铃脲、虱螨脲对2种果蝇2龄幼虫的毒力,以及其在亚致死浓度LC_(10)、LC_(20)下对2种果蝇体内几丁质酶活性的影响。结果显示,经不同浓度的氟铃脲和虱螨脲处理后,随着时间的延长和浓度的增加,2种果蝇的死亡率均明显增加,氟铃脲处理可使2种果蝇的死亡率最高达到83.33%,明显高于虱螨脲处理后黑腹果蝇(65.00%)和斑翅果蝇(66.66%)的死亡率。亚致死浓度LC_(10)和LC_(20)的虱螨脲处理果蝇2龄幼虫24 h后,黑腹果蝇2龄幼虫体内的几丁质酶活性呈下降趋势,而斑翅果蝇2龄幼虫体内的几丁质酶活性则呈上升趋势。另外,亚致死浓度的氟铃脲可明显抑制黑腹果蝇体内几丁质酶的活性。表明昆虫生长调节剂氟铃脲和虱螨脲对果蝇有较强的毒力,氟铃脲的毒力高于虱螨脲,且果蝇体内几丁质酶的活性与氟铃脲和虱螨脲密切相关。     

Anti-oxidative and immuno-hematological status of Tilapia (Oreochromis mossambicus) during acute toxicity test of endosulfan

Endosulfan is an organochlorine pesticide widely used in agriculture and hence finds its way into natural water bodies, thus affecting aquatic life. The purpose of this study was to determine LC₅₀ of endosulfan (99%; α:β ratio of 7:3) in Tilapia, Oreochromis mossambicus and study its effect on anti-oxidative enzymes (superoxide dismutase, glutathione-S-transferase and catalase), immuno-hematological profile (RBC, WBC, Hb, serum protein, albumin-A, globulin-G, A/G ratio, phygocytic activity as indicated by nitroblue tetrazolium reduction, serum cortisol and serum lipid peroxidation) and neurotransmitter acetylcholine esterase enzyme activity. The LC₅₀ value at 96 h and 95% confidence limit for tilapia (46.78 g) was estimated as 3.6 μg/L. Activities of anti-oxidative enzymes, immuno-hematological profile, blood glucose and neurotransmitter activity was significantly influenced (P < 0.01) in dose dependent manner. This was reflected in the behavior of fish that was altered from normal during acute toxicity.     

虱螨脲亚致死浓度对小菜蛾保护酶系和解毒酶系活力的影响

为阐明虱螨脲对小菜蛾亚致死效应的生化机制,采用室内生物测定法测定了LC_(10)和LC_(25)亚致死浓度处理小菜蛾3龄幼虫1、6、12、24、48和72 h后其体内保护酶系和解毒酶系的活力变化。结果表明:虱螨脲LC_(10)处理对小菜蛾幼虫体内超氧化物歧化酶(SOD)活力表现为早期诱导、后期抑制的作用,而对过氧化物酶(POD)则表现为先抑制后诱导的作用,对过氧化氢酶(CAT)仅在72h时具有诱导作用;LC_(25)处理对SOD表现为诱导-抑制-诱导-抑制的作用,对POD具有抑制作用,而对CAT具有诱导作用。经虱螨脲亚致死浓度处理后,小菜蛾幼虫体内酯酶和多功能氧化酶活力被明显抑制,且基本表现为浓度越高抑制作用越强;而谷胱甘肽S-转移酶(GST)活力仅在处理后1 h被诱导,之后被显著抑制。表明虱螨脲进入小菜蛾幼虫体内后,初期可诱导SOD、CAT和GST活力升高,以适应外界毒害的影响;但随着时间的延长,3种解毒酶活力被抑制,使其难以代谢,从而增强了对小菜蛾的毒性。     

棉铃虫表皮蛋白基因CP22和CP14的表达特征及其对甲氧虫酰肼的响应

为揭示棉铃虫Helicoverpa armigera表皮蛋白（cuticular protein，CP）基因在其生长发育及应对药剂胁迫中的作用，克隆棉铃虫2个CP基因CP22和CP14，利用实时荧光定量PCR技术分析其在不同发育阶段和不同组织中的相对表达量，并于显微镜下观察甲氧虫酰肼亚致死剂量处理后棉铃虫3龄幼虫的表皮形态，并用实时荧光定量PCR技术测定药后CP22和CP14基因的相对表达量。结果显示，CP22和CP14的开放阅读框全长分别为570 bp和393 bp，分别编码189个和130个氨基酸；CP22和CP14都具有1个几丁质结合域，属于CPR家族RR-1亚类；CP22和CP14基因均在棉铃虫5龄幼虫表皮中表达水平高；这2个基因在棉铃虫幼虫期的表达水平高于在卵期、蛹期和成虫期的表达水平，且在4龄幼虫体内表达量最高，在蜕皮后随着日龄的增加表达量逐渐降低；甲氧虫酰肼处理后棉铃虫3龄幼虫表皮黑化、皱缩，发生蜕皮异常，显微观察显示其内外表皮分离，真皮细胞解体；甲氧虫酰肼处理后24 h和48 h，棉铃虫CP22和CP14基因的相对表达量显著上调。表明棉铃虫CP22和CP14基因参与棉铃虫幼虫蜕皮，并且响应甲氧虫酰肼胁迫，可作为防治棉铃虫的潜在靶标基因。     

Immunotoxicity of aminocarb : I. Comparative studies of sublethal exposure to aminocarb and dieldrin in mice

Immunotoxicity of a carbamate pesticide, aminocarb (Matacil), introduced orally in sublethal doses to C57B1/6 inbred mice, has been compared to the immunosupressive effects of the organochlorine pesticide, dieldrin (served as a positive control), in bacterial and viral infections. In vivo infection of pesticide-exposed mice with Salmonella typhimurium and mouse hepatitis virus 3 (MHV3) showed that two subsequent LD₅₀ doses of aminocarb did not decrease the resistance of animals to the pathogens, whereas exposure to dieldrin resulted in augmented mortality. In vitro studies showed that the spread of MHV3 virus infection and virus-induced cytopathic effects (cpe) were augmented in peritoneal macrophages after exposure to aminocarb, albeit to a much less extent than in the dieldrin group. Similarly, a decrease in the anti-MHV3 IgM serum antibody titer by aminocarb was less marked than in the dieldrin group. Alternatively, immunization of animals with a neutral antigen, sheep red blood cells (SRBC), showed a significant increase in the anti-SRBC humoral response 10 days after a single oral exposure to LD₅₀ aminocarb. The cellular immune response, determined by mixed lymphocyte reaction, was unaffected by sublethal aminocarb exposure. In addition, macrophage antigen processing of a single protein, avidin, was unaffected by aminocarb, contrary to the inhibition of avidin processing in macrophages from dieldrin-gavaged mice. The data do not indicate that immunotoxic properties are associated with aminocarb, and only slight effects with high sublethal doses of orally given aminocarb on macrophage susceptibility to the MHV3 viral pathogen were observed at a terminal phase of the disease.     

六种农药对两种果蝇成虫室内毒力和主要解毒酶活性的影响

为明确田间常用农药对伊米果蝇Drosophila immigrans和海德氏果蝇D. hydei的毒力和解毒机制,采用药膜法在室内测定6种田间常用农药原药对2种果蝇实验种群成虫的LC_(10)、LC_(20)和LC_(50),并研究其中3种农药的亚致死剂量(LC_(10)、LC_(20))对果蝇谷胱甘肽S-转移酶(GST)、羧酸酯酶(CarE)、乙酰胆碱酯酶(AchE)3种主要解毒酶活性的影响。结果表明,乙基多杀菌素对伊米果蝇的毒力最大,LC_(10)、LC_(20)和LC_(50)分别为0.29、0.51和1.51 mg/L;甲维盐对海德氏果蝇的毒力最大,LC_(10)、LC_(20)和LC_(50)分别为0.14、0.36和2.09 mg/L;吡虫啉对2种果蝇的毒力均最低。不同亚致死浓度的乙基多杀菌素处理伊米果蝇24 h后,CarE和AchE活性均显著高于对照,而GST活性在低浓度时显著高于对照;高浓度甲维盐仅对海德氏果蝇AchE活性有显著抑制作用;吡虫啉可抑制伊米果蝇AchE和海德氏果蝇CarE活性。表明伊米果蝇和海德氏果蝇可通过改变3种解毒酶的活性来防御杀虫剂对其造成的影响。     

Effect of waterborne benomyl on the hematological and antioxidant parameters of the Nile tilapia, Oreochromis niloticus

The present study was conducted to determine the 96 h-LC₅₀ of benomyl to the Nile tilapia, Oreochromis niloticus and to investigate the biochemical or hematological indices of blood and the alterations in the antioxidant enzymes of this fish in response to sublethal concentrations of benomyl. Fish weighing 71.61 ± 12.05 g were used in this study; they were subjected to fasting for 4 weeks before treatment. An aqueous solution of benomyl (0, 0.5, 1, 2, 4, 8, and 16 mg L⁻¹) was administered for 96 h to determine the LC₅₀. The 96 h-LC₅₀ value of benomyl was 4.39 (3.23-5.60) mg L⁻¹ in the present study. For 5 weeks, the aqueous solution of benomyl (0, 100, 200, and 400 μg L⁻¹) was administered to investigate its effect on the hematological parameters and antioxidant enzymes. The predominant hematological findings in fish exposed to benomyl were as follows: no significant change in the Hb (g dL⁻¹) level, MCV (μm³), MCH (pg) and MCHC (%) as compared to the control. Benomyl exposure led to greater increases in the GPT, GOT (Karmen-unit), LDH (Wroblewski unit), total cholesterol, Fe, and Ca (mg dL⁻¹) values, whereas the levels of ALP (KA unit), total protein, triglyceride, albumin, and Mg (mg dL⁻¹) did not increase. Benomyl increased the in vivo HSI (%), GST (nmol min⁻¹ mg protein⁻¹), and SOD (U mg protein⁻¹) values in the fish livers in the test group, unlike those in the control group for 5 weeks. At concentrations higher than 100 μg L⁻¹, benomyl affected the GST and SOD levels of Nile tilapia in a dose- and time-dependent manner. The present findings suggest that the in vivo hepatotoxicity associated with benomyl may, in part, result from the hematological index, and antioxidants may provide limited protection against benomyl toxicity.