Oxidative stress in digestive gland and gill of the brown mussel (Perna perna) exposed to air and re-submersed

Mussels Perna perna were exposed to air for 24 h showing a clear increase in the levels of lipid peroxidation and oxidative DNA damage, measured as 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo). The levels of lipid peroxidation increased both in the digestive gland and gills, while oxidative DNA damage increased only in the gills. After the 24 h of air exposure, mussels were re-submersed for a period of 3 h, leading values to return to a pre-aerial exposure levels. Control animals were kept immersed during the whole period. Several antioxidant and complementary enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PDH), glutathione S-transferase (GST) and the levels of total glutathione (Total GSH) were assayed in a second set of experiments where one group of mussels were exposed to air for 18 h and other to 1 h re-submersion after 18 h aerial exposure. Only a 52% increase in the glutathione S-transferase activity was observed in the digestive gland, which remained elevated to about 40% after 1 h re-submersion, showing that defense systems can be modulated even during oxygen deprivation in P. perna. The DNA and lipid oxidative damage observed after aerial exposure indicates that mussels face an oxidative challenge, and are able to counteract such an “insult” as values of lipid peroxidation and DNA damage returned to control values after 3 h re-submersion.     

Investigation of Cadmium-Induced Genotoxicity and Oxidative Stress Response in Indian Major Carp,Labeo rohita

We investigated genotoxicity and oxidative stress in the gills of Labeo rohita exposed to 33.6, 67.1, and 100.6 mg L^–1of cadmium chloride at 96 h. Genotoxicity was assessed using single cell gel electrophoresis whereas oxidative stress was monitored through lipid peroxidation induction and antioxidant response parameters, namely reduced glutathione (GSH), glutathione peroxidase, glutathione-S-transferase, superoxide dismutase, and catalase (CAT) activities. Significant (p < .05) effect of both concentration and time of exposure was observed on the extent of DNA damage in treated fish. Similarly, malondialdehyde content, level of GSH, and activities of antioxidant enzymes were significantly elevated in treated groups, except CAT. The increased DNA damage and lipid peroxidation (LPO) content along with fluctuation in antioxidant defense system in fish indicated the interaction of cadmium (Cd) with DNA repair processes and production of reactive oxygen species. Thus, Cd is liable for induction of LPO, alteration of antioxidant defenses, and DNA damage in gills of L. rohita.     

Genotoxicity and oxidative stress in fish after a short-term exposure to silver nanoparticles

This study examined the effects of waterborne silver nanoparticles (AgNPs) on juvenile fish Piaractus mesopotamicus (“pacú”), and analyzed toxicological endpoints such as metal burdens, oxidative stress and genotoxicity in a short-term assay. Fish were individually exposed to 0 (control), 2.5, 10, and 25 μg AgNPs/L. After 24 h, silver accumulation was greater in the brain than the liver and gills at all silver concentrations. Fish exposed to higher AgNPs concentrations showed major alterations in oxidative stress markers. An increase in lipid peroxidation (LPO) levels was observed in the liver of fish exposed to 10 μg AgNPs/L with no changes in the antioxidant enzymes activities. In the case of the 25 μg AgNPs/L treatment, a hepatic activation of the enzymatic antioxidant defense occurred, and LPO levels resulted unaltered. On the other hand, the brain presented the highest LPO levels at both 10 and 25 μg AgNPs/L exposures. The AgNPs toxicity was also evidenced by the DNA damage in fish erythrocytes at higher concentrations. Summarizing, a short exposure to sublethal concentrations of AgNPs is enough to generate deleterious effects on fish, including DNA damage.     

Activity of antioxidant enzymes and physiological responses in ark shell,Scapharca broughtonii,exposed to thermal and osmotic stress: Effects on hemolymph and biochemical parameters

Changes in water temperature and salinity are responsible for a variety of physiological stress responses in aquatic organisms. Stress induced by these factors was recently associated with enhanced reactive oxygen species (ROS) generation, which caused oxidative damage. In the present study, we investigated the time-related effects of changes in water temperature and salinity on mRNA expression and the activities of antioxidant enzymes (SOD and CAT) and lipid peroxidation (LPO) in the gills and digestive glands of the ark shell, Scapharca broughtonii. To investigate physiological responses, hydrogen peroxide (H₂O₂), lysozyme activity, aspartate aminotransferase (AspAT), and alanine aminotransferase (AlaAT) were measured in the hemolymph. Water temperature and salinity changes significantly increased antioxidant enzyme mRNA expression and activity in the digestive glands and gills in a time-dependent manner. H₂O₂ concentrations increased significantly in the high-temperature and hyposalinity treatments. LPO, AspAT and AlaAT levels also increased significantly in a time-dependent manner, while lysozyme activity decreased. These results suggest that antioxidant enzymes play important roles in reducing oxidative stress in ark shells exposed to changes in water temperature and salinity.     

Ichthyotoxicity of Chattonella marina (Raphidophyceae) to damselfish (Acanthochromis polycanthus): the synergistic role of reactive oxygen species and free fatty acids

This investigation aimed to elucidate the relative roles of putative brevetoxins, reactive oxygen species and free fatty acids as the toxic principle of the raphidophyte Chattonella marina, using damselfish as the bioassay. Our investigations on Australian C. marina demonstrated an absence or only very low concentrations of brevetoxin-like compounds by radio-receptor binding assay and liquid chromatography–mass spectroscopy techniques. Chattonella is unique in its ability to produce levels of reactive oxygen species 100 times higher than most other algal species. However, high levels of superoxide on their own were found not to cause fish mortalities. Lipid analysis revealed this raphidophyte to contain high concentrations of the polyunsaturated fatty acid eicosapentaenoic acid (EPA; 18–23% of fatty acids), which has demonstrated toxic properties to marine organisms. Using damselfish as a model organism, we demonstrated that the free fatty acid (FFA) form of EPA produced a mortality and fish behavioural response similar to fish exposed to C. marina cells. This effect was not apparent when fish were exposed to other lipid fractions including a triglyceride containing fish oil, docosahexaenoate-enriched ethyl ester, or pure brevetoxin standards. The presence of superoxide together with low concentrations of EPA accelerated fish mortality rate threefold. We conclude that the enhancement of ichthyotoxicity of EPA in the presence of superoxide can account for the high C. marina fish killing potential.     

Proteasome and antioxidant responses in Cottus gobio during a combined exposure to heat stress and cadmium

Temperature and trace metals are common environmental stressors, and their importance is increasing due to global climate change and anthropogenic pollution. Oxidative damage and antioxidant properties have been studied in liver and gills of the European bullhead (Cottus gobio) subjected to cadmium (CdCl(2) at nominal concentrations of 0.01 and 1mg/L) for 4 days at either 15°C or 21°C. First, exposure to 1mg Cd/L induced a high mortality rate (67%) in fish held at 21°C. Regarding the antioxidant enzymes, exposure to 0.01 mg Cd/L significantly increased the activity of superoxide dismutase (SOD) and decreased the activity of glutathione reductase (GR) in liver, independently of heat stress. In gills, exposure to 21°C resulted in a significantly increased activity of glutathione peroxidase (GPx), whereas the activity of glutathione S-transferase (GST) was significantly reduced as compared to fish exposed to 15°C. Furthermore, regardless of Cd stress, exposure to elevated temperature resulted in a significant decrease of lipid peroxidation (LPO) level in liver and in a significant increase in the activity of chymotrypsin-like 20S proteasome in both studied tissues of C. gobio. Overall, the present results indicated that elevated temperature and cadmium exposure independently influenced the antioxidant defense system in bullhead with clear tissue-specific and stress-specific antioxidant responses. Further, elevated temperature affected the hepatic lipid peroxidation and the activity of 20S proteasome in both tissues.     

扑草净对远志幼苗根系活力及氧化胁迫的影响

以远志(Polygala tenuifolia Willd.)为材料,应用组织化学和生物化学的方法研究不同浓度扑草净(0—400 mg/L)对远志幼苗生长、根系活力、膜脂过氧化、活性氧含量及抗氧化酶活性等的影响。10 mg/L扑草净对远志幼苗根系活力、细胞膜完整性及活性氧的积累几乎无显著影响,而25—400 mg/L扑草净处理则显著增加活性氧的积累,明显抑制根系活力且破坏细胞膜完整性;上述结果进一步被膜脂过氧化、质膜完整性、活性氧产生(O.2-和H2O2)的非损伤组织化学染色所证明。远志幼苗可通过多种抗氧化酶(SOD、POD、CAT、APX等)和非酶抗氧化剂(如脯氨酸)的相互协调作用,清除低浓度扑草净胁迫诱发产生的活性氧,减轻对细胞的伤害。研究结果表明,发芽期是远志对扑草净处理的敏感时期,较为安全的扑草净临界浓度为10 mg/L;25mg/L扑草净处理即引起远志幼苗氧化胁迫和膜脂过氧化,使细胞膜的完整性受到破坏,根系活力下降,抑制了远志幼苗的生长发育。该研究为远志抗除草剂胁迫机制及其栽培过程中除草剂的安全合理使用提供理论依据。     

Effects of arsenic (As) exposure on the antioxidant status of gills of the zebrafish Danio rerio (Cyprinidae)

In fishes, arsenic (As) is absorbed via the gills and is capable of causing disturbance to the antioxidant system. The objective of present study was to evaluate antioxidant responses after As exposure in gills of zebrafish (Danio rerio, Cyprinidae). Fish were exposed for 48 h to three concentration of As, including the highest As concentration allowed by current Brazilian legislation (10 μg As/L). A control group was exposed to tap water (pH 8.0; 26 °C; 7.20 mg O₂/L). As exposure resulted in (1) an increase (p < 0.05) of glutathione (GSH) levels after exposure to 10 and 100 μg As/L, (2) an increase of the glutamate cysteine ligase (GCL) activity in the same concentrations (p < 0.05), (3) no significant differences in terms of glutathione reductase, glutathione-S-transferase and catalase activities; (4) a significantly lower (p < 0.05) oxygen consumption after exposure to 100 μg As/L; (4) no differences in terms of oxygen reactive species generation and lipid peroxidation content (p > 0,05). In the gills, only inorganic As was detected. Overall, it can be concluded that As affected the antioxidant responses increasing GCL activity and GSH levels, even at concentration considered safe by Brazilian legislation.     

A comparative study: Assessment of the antioxidant system in the invasive green alga Caulerpa racemosa and some macrophytes from the Mediterranean

Reactive oxygen species (ROS) are of great importance in plant metabolism. However, uncontrolled activation of ROS might have deleterious effects in cells. Eleven Mediterranean countries are still under threat of an introduced taxon of Caulerpa racemosa var. cylindracea. In the present study, it has been aimed to compare the antioxidant status of this highly invasive alga with some Mediterranean macrophytes collected in the same habitat. For this purpose, such antioxidant enzyme activities as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and lipid peroxidation (LPO) as well, levels have been determined in C. racemosa, Cystoseira barbata C. Agardh, Padina pavonica (Linnaeus) Thivy and Enteromorpha sp. The highest SOD, CAT, GSH-Px enzyme activities and the lowest LPO level have been measured in the invasive C. racemosa. In conclusion, C. racemosa var. cylindracea seems more tolerant in warring with ROS than the Mediterranean species tested do. These results could partly explain the amazing success of C. racemosa var. cylindracea introduced in the Mediterranean.     

Invasion of Ceratomyxa shasta (Myxozoa) and comparison of migration to the intestine between susceptible and resistant fish hosts

The myxozoan parasite Ceratomyxa shasta infects salmonids causing ceratomyxosis, a disease elicited by proliferation of the parasite in the intestine. This parasite is endemic to the Pacific Northwest of North America and salmon and trout strains from endemic river basins show increased resistance to the parasite. It has been suggested that these resistant fish (i) exclude the parasite at the site of invasion and/or (ii) prevent establishment in the intestine. Using parasites pre-labeled with a fluorescent stain, carboxyfluorescein succinimidyl diacetate (CFSE), the gills were identified as the site of attachment of C. shasta in a susceptible fish strain. In situ hybridization (ISH) of histological sections was then used to describe the invasion of the parasites in the gill filaments. To investigate differences in the progress of infection between resistant and susceptible fish, a C. shasta-susceptible strain of rainbow trout (Oncorhynchus mykiss) and a C. shasta-resistant strain of Chinook salmon (Oncorhynchus tshawytscha) were sampled at consecutive time points following exposure at an endemic site. Using ISH in both species, the parasite was observed to migrate from the gill epithelium into the gill blood vessels where replication and release of parasite stages occurred. Quantitative PCR verified entry of the parasite into the blood. Parasite levels in blood increased 4 days p.i. and remained at a consistent level until the second week when parasite abundance increased further and coincided with host mortality. The timing of parasite replication and migration to the intestine were similar for both fish species. The field exposure dose was unexpectedly high and apparently overwhelmed the Chinook salmon’s defenses, as no evidence of resistance to parasite penetration into the gills or prevention of parasite establishment in the intestine was observed.     

The interactive effect of elevated temperature on deltamethrin-induced biochemical stress responses in Channa punctata Bloch

There are reports showing interactive effect of environmental factors with the toxic outcome of chemicals. We studied the interactive effect of elevated temperature as an abiotic stressor on deltamethrin-induced biochemical stress responses in a freshwater fish, Channa punctata Bloch. Heat stress (∼12 °C above ambient temperature for 3 h) and pesticide exposure (deltamethrin 0.75 ppb for 48 h) showed significant induction of heat shock protein-70 (HSP70) in liver, kidney and gills of fishes. Elevated temperature when followed by deltamethrin exposure showed synergistic effect showing a high level of HSP70 in liver and gills whereas response in the kidney was opposite. On the contrary, when deltamethrin exposure followed the heat stress, no significant difference was observed. Protein carbonylation was found to be more pronounced in heat-stressed group compared with control fish group. A significant increase in lipid peroxidation (LPO) was observed in different tissues of fish exposed to either of the stressors. In the kidney of fish exposed to heat stress followed by deltamethrin, LPO was relatively lower as compared to other treatments. Thiols content such as reduced glutathione (GSH), total thiols (T-SH), non-protein thiols (NP-SH) and protein thiols (P-SH) showed no consistent pattern in different tissues. In deltamethrin-exposed group that was subsequently exposed to heat stress, the GSH content was higher in liver and lower in both kidney and gills when compared with other groups. Alteration in the activities of antioxidant enzymes such as catalase (CAT), glutathione S-transferase (GST), glutathione reductase (GR) and glutathione peroxidase (GPx) was also observed when fish were exposed to heat stress and/or deltamethrin. Our study demonstrated that heat stress modulated biochemical stress responses in fish showing a tissue specific pattern. This implies that fish has the capacity to elicit differential response to exposure to abiotic stressors in order to reduce the systemic magnitude of stress which may otherwise lead to severe dysfunction of vital tissues.     

Effects of temperature on modulation of oxidative stress and antioxidant defenses in testes of tropical tasar silkworm Antheraea mylitta

High temperatures are known to cause physiological stress in organisms. This is often associated with enhanced generation of reactive oxygen species (ROS) leading to oxidative damage. The commercially important tropical tasar silkworm Antheraea mylitta has to endure high summer temperature before egg production on the onset of monsoon. In this study the status of pro-oxidants and antioxidants was studied in the testes of male pupae of tasar silkworm A. mylitta under thermal stress condition. Further, to find out the impact of temperature on physiological activity, oxygen consumption rate was measured. The result indicated higher level of thiobarbituric acid reactive substances (TBARS, as an index of lipid peroxidation) and total hydroperoxides in the male pupae exposed to high temperature (40±1 °C). Similarly, it was found that increased levels of antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), ascorbic acid (ASA) and low molecular thiols (L-SH) in testes are more prominent in high temperature rather than in moderate temperature (35±1 ^oC) suggesting the activation of physiological mechanism to scavenge the ROS produced during stress. Further more, the order of higher level of oxygen consumption rate was observed as high temperature (40±1°C) > moderate temperature (35±1°C) > control groups (28±1°C). Oxygen consumption rate was positively correlated with oxidative stress and antioxidant defence indices. We infer from these findings that the testes of A. mylitta pupae modulate testicular antioxidant responses to thermal stress.     

Antioxidant levels from different Antarctic fish caught around South Georgia Island and Shag Rocks

Antarctic fish have been isolated for over several million years in an environment with a very low and constant temperature and high oxygen concentration. In such conditions the oxidative stress might be an important factor affecting their metabolic adaptive strategies. Activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), vitamin E levels and total antioxidant capacity (TRAP) were measured in liver, gill, heart and muscle homogenates of red-blooded (Nototheniidae) and white-blooded (Channichthyidae) Antarctic fish. SOD activity was also measured in blood samples. Gill SOD activity was threefold higher in channichthyids than in nototheniids while CAT and GPx were significantly higher in the gills of channichthyids. The increased SOD activity of channichthyids probably reflects the large PO₂ gradient across their gills. The H₂O₂ produced seems to be preferentially eliminated by diffusion, according to the low levels of CAT and GPx found in the gills of these species. In contrast, blood SOD was about fivefold higher in the latter group, which possesses erythrocytes and thus a much higher oxygen-carrying capacity. CAT activity was always higher in nototheniids except in muscle. However, vitamin E did not show clear differences between families except for the pattern observed in muscle. The higher content of vitamin E in this tissue shown in channichthyids is related to the higher volume density of mitochondria reported for this group, since vitamin E is responsible for preventing membrane lipid peroxidation. Accordingly, TRAP (representative of hydrosoluble antioxidant capacity) was also higher in muscle of channichthyids. This is probably related to the role of ascorbic (a hydrosoluble compound) acid in regenerating vitamin E. Accepted: 4 September 1999     

Exposure to waterborne copper and high temperature induces the formation of reactive oxygen species and causes mortality in the Amazonian fish <Emphasis Type="Italic">Hoplosternum littorale</Emphasis>

Hoplosternum littorale is an Amazon fish that lives in urban areas surrounded by polluted igarapés, where elevated copper concentrations eventually occur. The central goal of this study was to evaluate the associated effects of high temperature and copper contamination on survival time and biochemical responses of the Amazonian fish species H. littorale. We exposed fish to two nominal dissolved copper concentrations (50 and 500 µg l^?1) and combined temperatures of 28 and 34°C. Our findings showed that the combination of these variables affects the survival time of this species. The activity of the biotransformation enzymes ethoxyresorufin-O-deethylase and glutathione-S-transferase showed no alterations in fish within all treatments. The increase of reactive oxygen species and the decrease in potential total antioxidant capacity promoted the imbalance in the antioxidant system. An induction in superoxide dismutase activity occurred in fish exposed to copper concentrations of 50 and 500 µg l^?1 at both temperatures, suggesting liver impairments. Thus, we suggest that H. littorale is sensitive to copper, and this sensitivity is increased further with exposure to high temperatures, particularly in the survival time and reactive oxygen species formation of this fish species.     

Antioxidant responses of citrus red mite, Panonychus citri (McGregor) (Acari: Tetranychidae), exposed to thermal stress

Relatively low or high temperatures are responsible for a variety of physiological stress responses in insects and mites. Induced thermal stress was recently associated with increased reactive oxygen species (ROS) generation, which caused oxidative damage. In this study, we examined the time-related effect of the relatively low (0, 5, 10, and 15 °C) or high (32, 35, 38, and 41 °C) temperatures on the activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), peroxidases (POX), and glutathione-S-transferase (GST), and the total antioxidant capacity (TEAC) of the citrus red mite, Panonychus citri (McGregor). The malondialdehyde (MDA) concentration, as a marker of lipid peroxidation in organisms, was also measured in the citrus red mite under thermal stress conditions. Results showed that SOD and GST activities were significantly increased and play an important role in the process of antioxidant response to thermal stress. Lipid peroxidation levels increased significantly (P < 0.001) and changed in a time-dependent manner. CAT and POX activity, as well as TEAC, did not vary significantly and play a minor role to remove the ROS generation. These results suggest that thermal stress leads to oxidative stress and antioxidant enzymes play an important role in reducing oxidative damage in the citrus red mite.     

Effect of thermal stress on metabolic and oxidative stress biomarkers of Hoplosternum littorale (Teleostei,Callichthyidae)

The present study aimed to investigate in Hoplosternum littorale (Hancock, 1828) the effects of different water temperatures (10 °C, 25 °C-control group- and 33 °C) on physiologic and metabolic traits following acute (1 day) and chronic (21 days) exposures. We analyzed several biomarker responses in order to achieve a comprehensive survey of fish physiology and metabolism under the effect of this natural stressor. We measured morphological indices, biochemical and hematological parameters as well as oxidative stress markers. To evaluate energy consumption, muscle and hepatic total lipid, protein and glycogen concentrations were also quantified. Extreme temperatures exposures clearly resulted in metabolic adjustments, being liver energy reserves and plasma metabolites the most sensitive parameters detecting those changes. We observed reduced hepatosomatic index after acute and chronic exposure to 33 °C while glycogen levels decreased at both temperatures and time of exposure tested. Additionally, acute and chronic exposures to 10 °C increased liver lipid content and plasma triglycerides. Total protein concentration was higher in liver and lower in plasma after chronic exposures to 10 °C and 33 °C. Acute exposition at both temperatures caused significant changes in antioxidant enzymes tested in the different tissues without oxidative damage to lipids. Antioxidant defenses in fish failed to protect them when they were exposed for 21 days to 10 °C, promoting higher lipid peroxidation in liver, kidney and gills. According to multivariate analysis, oxidative stress and metabolic biomarkers clearly differentiated fish exposed chronically to 10 °C. Taken together, these results demonstrated that cold exposure was more stressful for H. littorale than heat stress. However, this species could cope with variations in temperature, allowing physiological processes and biochemical reactions to proceed efficiently at different temperatures and times of exposure. Our study showed the ability of H. littorale to resist a wide range of environmental temperatures and contributes for the understanding of how this species is adapted to environments with highly variable physicochemical conditions.     

Effects of exposure to multiple trace metals on biochemical, histological and ultrastructural features of gills of a freshwater fish, Channa punctata Bloch

The trace metals are frequently encountered as mixtures of essential and non-essential elements. Therefore, evaluation of their toxic effects individually does not offer a realistic estimate of their impact on biological processes. We studied effects of a mixture of four essential and toxic metals (Cu, Cd, Fe and Ni) on biochemical and morphological characteristics of the gills of a biomarker freshwater fish Channa punctata (Bloch) using environmentally relevant concentrations. Fish were exposed to metal mixture through tank water for 7, 15 and 30 days. Biochemical studies as well as light microscopy (LM) and scanning electron microscopy (SEM) revealed significant metal exposure-induced alterations in gills. Besides ultastructural changes, activities of antioxidant enzymes such catalase (CAT), glutathione S-transferase (GST) and superoxide dismutase (SOD) were significantly altered in the gills of exposed fish. The reduced glutathione (GSH) was significantly (p<0.001) decreased, while lipid peroxidation (LPO) was significantly (p<0.001) increased. The main alterations in general morphology of fish gills included spiking and fusion of secondary lamellae, formation of club-shaped filaments, and vacuolization and necrosis of filament epithelium in the interlamellar regions. SEM studies showed gradual increase of the density and apical surface area of the chloride cells and transformation of the surface structure of the pavement cells. The results of this study indicate adaptive as well a toxic responses in fish gills exposed to mixture of trace metals. Low concentrations of trace metal appear to compromise the antioxidant defense of gills. Lesions in the gill morphology caused by the effect of low concentrations of trace metals could lead to functional alterations and interference with fundamental processes such as maintenance of osmoregulation, gas exchange and xenobiotic metabolism in the exposed fish populations.     

Responses of antioxidants and lipid peroxidation in mussels to oxidative damage exposure

• 1.1. The aim of this work was to evaluate the relationships between free radical scavengers and lipid peroxidation in the common mussel Mytilus edulis.
• 2.2. Mussels were exposed to compounds known for their ability to produce free radicals (carbon tetrachloride, CCl₄) and reactive oxygen species via redox cycling (menadione), and the effects on digestive gland, gills and remaining tissues were studied.
• 3.3. Lipid peroxidation parameters and the status of free radical scavengers (glutathione, vitamins A, E and C) were affected more by exposure to menadione than to CCl₄.
• 4.4. The observed changes in the free radical scavengers content are indicative of a role in detoxication of damaging reactive species.

     

Multi-organ toxicological impact of fungicide propiconazole on biochemical and histological profile of freshwater fish Channa punctata Bloch

Fungicides are a pesticide that particularly kills or destroy fungi responsible for several diseases associated to humans and other living organisms. Assessment of toxic effects and mechanisms of fungicide action is important because humans and domesticated animals get exposed to these pesticides through a wide variety of applications. Several fungicides are being used at the large scale for the crop protection from the fungal invasion. Propiconazole (PCZ), a trazole-containing fungicide, is widely used in China and various Asian countries for food crop protection which made it easily to exposed to the aquatic system. Long term usage of PCZ may contaminate the water bodies, but its toxicity to aquatic organisms is not well studied. In this study, freshwater fish, Channa punctata Bloch was exposed to different sub-lethal concentrations of the fungicide, PCZ (0.5 and 5 ppm) for a period of 96 h. Various biochemical assays and histological alterations were measured to determine the organ toxicity caused by PCZ exposure particularly in liver, kidney and gills of the fishes. Compared to the control group, fish exposed to PCZ (96 h) showed marked dose dependent toxicity. The levels of lipid peroxidation (LPO) and protein carbonyls (PC), oxidative stress biomarker of liver, kidney and gills in the experimental group were significantly higher (P < 0.05 and P < 0.001) compared to the control group. Levels of reduced glutathione (GSH) and non-protein thiols (NP-SH) decreased significantly (P <0.05–0.001) in all analyzed intoxicated organs of the PCZ exposed fishes. Activity of glutathione-S-transferase (GST), glutathione peroxidase (GPx) and catalase (CAT) in fungicide treated groups was significantly lowered (P < 0.05–0.001). In addition, histopathological examination in the organs showed significant changes like atrophy of primary and secondary gill lamellae, infiltrations, inflammation, hepatocyte degeneration, vacuolization and necrotic kidney. Thus, PCZ exposure altered the oxidative stress homeostasis and brought about histopathological changes which may serve as potential biomarkers of the PCZ toxicity in the laboratory set-up for potential risk assessment.