Concentrations Of Mercury Chloride Research Articles

Metrics Profiles of Melanomacrophages Centre on the Spleen of Carp (Cyprinus carpio) Exposed to Mercury Chloride

Increasing the number of heavy metals in the aquatic environment results in the accumulation of contaminants in fish body tissue, making fish an ideal bio-indicator of environmental pollution. The spleen included in the hematopoietic tissue contains macrophages. Macrophages form aggregates that contain pigments referred to melanomacrophage centres (MMCs). This research aims to analyse the metric profiles of MMCs on the common carp (Cyprinus carpio) spleen as a non-specific cellular immune response against mercury chloride exposure. This study used a Completely Randomized Design method with four treatments at different concentrations of mercury chloride (HgCl2) of 0 mg.l-1 , 0.01 mg.l-1 , 0.05 mg.l-1 , and 0.1 mg.l-1 . Each treatment was replicated five times. Data on the number and size of MMCs were analyzed by Analysis of Variance (ANOVA) and continued by using Duncan's Multiple Range Test (DMRT) to determine the differences between treatments. The result showed that the concentration of mercury chloride in water affects the metrics profile of spleen MMCs of carp. The number and size of MMCs of carp spleen increased at the concentration of 0.01 mg.l-1 and 0.05 mg.l-1 but decreased at the level of 0.1 mg.l-1 . The results suggest that the profile of MMCs as a non-specific cellular immune response can function as bio-indicators of environmental pollution.

Arsenic and mercury tolerant rhizobacteria that can improve phytoremediation of heavy metal contaminated soils.

Mining deposits often contain high levels of toxic elements such as mercury (Hg) and arsenic (As) representing strong environmental hazards. The purpose of this study was the isolation for plant growth promoting bacteria (PGPBs) that can improve phytoremediation of such mine waste deposits. We isolated native soil bacteria from the rhizosphere of plants of mine waste deposits and agricultural land that was previously mine tailings from Tlalpujahua Michoacán, Mexico, and were identified by their fatty acid profile according to the MIDI Sherlock system. Plant growth promoting traits of all bacterial isolates were examined including production of 3-indoleacetic acid (IAA), siderophores, biofilm formation, and phosphate solubilization. Finally, the response of selected bacteria to mercury and arsenic was examined an in-vitro assay. A total 99 bacterial strains were isolated and 48 identified, representing 34 species belonging to 23 genera. Sixty six percent of the isolates produced IAA of which Pseudomonas fluorescens TL97 produced the most. Herbaspirillum huttiense TL36 performed best in terms of phosphate solubilization and production of siderophores. In terms of biofilm formation, Bacillus atrophaeus TL76 was the best. Most of the bacteria isolates showed high level of tolerance to the arsenic (as HAsNa2O4 and AsNaO2), whereas most isolates were susceptible to HgCl2. Three of the selected bacteria with PGP traits Herbispirillum huttiense TL36, Klebsiella oxytoca TL49 and Rhizobium radiobacter TL52 were also tolerant to high concentrations of mercury chloride, this might could be used for restoring or phytoremediating the adverse environmental conditions present in mine waste deposits.

Study of the Effect of Mercury Salt on the Presence of Annelida (Lumbricus terrestris) in Soil and the Histological Changes on the Skin Tissue

The earthworm is the most beneficial organism for assessing metallic contamination due to the fact that critical high-quality correlations have been determined between earthworm steel concentrations and soil cadmium, copper, lead, zinc, and mercury concentrations. The mercury compounds are very poisonous for most organisms. Here, we investigated the ability of earthworms (Lumbricus terrestris) to HgCl2 (below laboratory conditions). A study of the effect of five different salt concentrations of mercury chloride (HgCl2) 1 ppm, 5 ppm, 10 ppm, 50 ppm, and 100 ppm was studied on worm survival and calculation of the concentration required to destroy half the number of worms (LC50). The results showed that there is an inverse relationship between these salt concentrations and the time required to perish 100% of worms. It was found that the concentration of 100 ppm is the lethal concentration of half the number (LC50) of the earthworm (Lumbricus terrestris). The effects of the salt concentrations used confirmed their effect on the experimental worm weights as well, so the concentration of 50 ppm was the most influential on earthworm weights of the type of Lumbricus terrestris, as it caused a reduction 12% of worm weights with a significant difference, while the concentrations 1 ppm and 100 ppm were the least effective, as they caused the worms to decrease by only (5%), while the remaining two concentrations 5 ppm and 10 ppm caused their effect to decrease by 7% only. Thus, it can be concluded that lower worm weights have nothing to do with the lethal concentrations of the heavy metal salt (HgCl2). The histological study also showed that low concentrations of mercury chloride salt have less effect on earthworms’ skin tissue compared to higher concentrations.

Protection against the Phytotoxic Effect of Mercury Chloride by Catechin and Quercetin

Plants when exposed to toxic levels of metals can suffer morphological or physiological damage because toxic metals can interact with several vital molecules in the plant. One possibility to remove these contaminants from the environment is through the phytoremediation technique, since secondary metabolites produced by plants can reverse these damages. To evaluate the cytoprotective activity, the dry mass and possible damage to the membranes of Lactuca sativa (lettuce) seedlings subjected to different concentrations of mercury chloride in association with catechin and quercetin in suballelopathic concentration were determined. The coordination of mercury chloride with substances was also evaluated using vibrational spectroscopy (Raman and FTIR). The interaction of the mentioned flavonoids with mercury chloride was evidenced through vibrational spectroscopy. When the metal was associated with catechin and quercetin, there was an increase in dry mass of almost 3 times when compared with the HgCl2 alone, demonstrating that these flavonoids act as cytoprotective agents. However, in the presence of catechin and quercetin, membrane damage caused by mercury chloride has a level similar to that observed in control plants, demonstrating none statistical difference. Comparing the highest concentration with the lowest concentration of the metal associated with quercetin, it can be seen that the intensity of the peaks in this region decreases when the concentration of the metal increases, indicating an interaction between the metallic compound and the flavonoid. In this context, the use of secondary metabolites can be an alternative in the process of remediation of areas contaminated by mercury chloride, as they mitigate the effects of mercury chloride on lettuce seedlings.

Acute Toxicity Assessment of Mercury Chloride to Freshwater Air Breathing Fish Clarias batrachus (Linnaeus, 1758): In vivo Study

Background: Mercury is the most noxious heavy metal. Because of its environmental persistence and ability to be accumulated in the fatty tissues of aquatic organism, it poses serious threat to the fish community. Methods: In the present study, freshwater air breathing fish Clarias batrachus were exposed separately to different concentrations of Mercury chloride (HgCl2) for 24 hrs, 48 hrs, 72 hrs and 96 hrs. Firstly, median lethal concentration (LC50) of HgCl2 to fish was determined by Probit analysis and was confirmed by pilot test. The behavioral and locomotary changes were monitored.Result: Test group showed random irregular and rapid swimming, restless activity. Along with these activities the test group became hyperactive, started jumping and changing their direction and position in an irregular manner. Some of the noticeable physiological symptoms during the initial stage of toxicity assessment were rapid opercular movement and frequent gulping of air. Both jerky movement and rapid respiratory response were reported to be occasional and slower in the longer duration exposure. Acute toxicity assessment provides first hand information to keep a check on pollution and to observe and track rigours of aquatic ecosystems.

Mercury exposure induces the release of neutrophil extracellular traps and apoptosis in carp neutrophils

Mercury, an important toxic contaminant, has been reported to have toxic effects on fish and mammals. Neutrophil extracellular traps (NETs) not only plays an important role in defending against infection but also leads to the damage of the tissues. In this study, we aimed to investigate the effects of mercury exposure on the formation of NETs in carp neutrophils. Neutrophils were isolated from the blood of common carps and incubated with different concentrations of mercury chloride. The formation of NETs were observed by laser confocal microscopy and quantitatively measured by picoGreen. The results showed that mercury chloride significantly induced the formation of NETs in carp neutrophils, which was a DNA-based network structure modified with myeloperoxidase (MPO) and histone (H3). Meanwhile, treatment of mercury chloride increased the production of reactive oxygen species (ROS), and decreased the activities of SOD and CAT. Furthermore, mercury treatment could induce the apoptosis of carp neutrophils. In addition, the results showed that mercury chloride-induced NETs were not inhibited by NADPH oxidase inhibitor DPI, AMPK inhibitor Compound C and p38 inhibitor SB202190, suggesting it was independent of ROS, AMPK, and p38. In conclusion, the results indicated that mercury chloride could induce the formation of NETs, which plays an important foundation for further study on the influence and mechanism of mercury chloride on the immune system.

Reduction of the phytotoxic effect of mercury chloride by rutin and evaluation of interactions by vibrational spectroscopy (Raman and FTIR)

Toxic metals can cause toxicity problems in the organisms exposed to them. Many substances are able to reverse this toxicity. Among the secondary metabolites of plant origin investigated are flavonoids. To evaluate the cytoprotective activity, dry mass and possible damage to the membranes of Lactuca sativa (lettuce) seedlings subjected to different concentrations of mercury chloride in association with rutin in suballelopathic concentration (8 μg/mL) were determined. It was observed that rutin gives cytoprotection to lettuce seedlings, allowing greater growth and development of the roots of these seedlings, probably through the coordination of mercury with the rutin molecule. The interaction of rutin with mercury chloride was evidenced through vibrational spectroscopy (Raman and FTIR). Although mercury chloride causes cytotoxicity in several plant species, its complex with rutin can mitigate these effects.

Assessment of the Effect of Light, HgCl<sub>2</sub> and Organic Compound on <i>Enterococcus faecalis</i> and <i>Escherichia coli</i> Cells Survive in Aquatic Microcosm

The aim of this study was to determine the cultivability of E. faecalis and enteropathogenic E. coli (EPEC) under different light intensities in the presence of different concentrations of mercury chloride (HgCl2) and biodegradable organic compound (BOC). Studied light intensities were 0, 500, 1000, 1500 and 2000 lux while studied HgCl2 concentrations were 0.001, 0.01, 0.1 and 1μg/L. The BOC used was glucose at concentrations of 0.001, 0.01, 0.1 and 1mg/L and at pH 7. The BOC used was glucose at concentrations of 0.001, 0.01, 0.1 and 1mg/L and at pH 7. The duration of incubation under light was 6 h. Results showed that E. faecalis and EPEC bacteria are inactivated by HgCl2 irrespective of studied concentration. The cells inhibition percentage (CIP) of E. faecalis varied from 94.46% to 99.53% at 0.001μg/L, from 94.77% to 99.55% at 0.01μg/L, from 94.92% to 99.57% at 0.1μg/L and from 96.97% to 99.77% at 1μg/L of HgCl2. For EPEC cells, the CIP fluctuated between 89.87% and 98.99%, between 90.67% and 99.14%, between 92.05% and 99.14% and 93.50% and 99.25% respectively in solutions containing 0.001, 0.01, 0.1 and 1µg/L of HgCl2. The highest abundance was observed under 1500 lux for E. faecalis and 500 lux for EPEC. Exposure to light seemed to intensify the toxic action of HgCl2 in the medium. Cells metabolism reactivations under 2000 lux for E. faecalis and 1000 lux for EPEC were nevertheless observed. The level of this photo-reactivation varies from one organism species to another. The oligotrophic nature of the medium could not allow studied the microorganisms to set up specific protection mechanism against HgCl2 and light.

Response of phase I and II detoxification enzymes, glutathione, metallothionein and acetylcholine esterase to mercury and dimethoate in signal crayfish (Pacifastacus leniusculus)

Metals and pesticides are common pollutants and the modulation of biomarkers can indicate sub-lethal influences on the physiology of organisms inhabiting impacted aquatic systems. We examined the effects of mercury and the organophosphate pesticide dimethoate on EROD, MROD, glutathione S-transferase (GST), acetylcholine esterase (AChE), metallothionein (MT) and glutathione (GSH) in the signal crayfish (Pacifastacus leniusculus). Crayfish were injected with mercury chloride or dimethoate (0.3, 0.6, 0.9 μg kg−1) and dissected after 72 h. EROD activity in the hepatopancreas did not change in response to mercury chloride treatment but exhibited a dose dependent decrease at all concentrations of dimethoate tested. MROD (hepatopancreas) exhibited a significant decrease at the 0.9 μg kg−1 treatment for both chemicals. GST (hepatopancreas) demonstrated a significant dose dependent decrease at all concentrations of both mercury chloride and dimethoate. AChE (tail muscle) decreased at the 0.6 and 0.9 μg kg−1 concentrations of dimethoate and 0.9 μg kg−1 mercury chloride. In gill tissue, MT increased in response to 0.3 and 0.6 μg kg−1 of mercury chloride but no effect was observed at the 0.9 μg kg−1 concentration of mercury chloride or any concentrations of dimethoate tested. MT did not change in response to mercury or dimethoate in tail tissue. Furthermore, neither chemical modulated GSH concentrations. Our results indicate that, apart from GSH, these markers are sensitive to the pollutants tested and that animals exposed in the wild are potentially compromised in their ability to detoxify environmental contaminants and carry out normal cellular processes.

Morphofunctional Alterations in Zebrafish (Danio rerio) Gills after Exposure to Mercury Chloride.

Mercury (Hg) is a global pollutant that may exert its toxic effects on living organisms and is found in both aquatic and terrestrial ecosystems in three chemical forms; elemental, organic, and inorganic. The inorganic form (iHg) tends to predominantly accumulate in aquatic environments. The gill apparatus is a very dynamic organ that plays a fundamental role in gas exchange, osmoregulation, acid-base regulation, detoxification, and excretion, and the gills are the primary route of waterborne iHg entrance in fish. In the present work we investigated the morphofunctional and ultrastructural effects in Danio rerio gills after 96 h exposure to two low HgCl2 concentrations (7.7 and 38.5 µg/L). Our results clearly demonstrated that a short-term exposure to low concentrations of mercury chloride resulted in gill morphology alterations and in the modifications of both Na+/K+-ATPase and metallothioneins (MTs) expression pattern. The main morphological effects recorded in this work were represented by hyperplasia and ectopia of chloride cells (CCs), lamellar fusion, increased mucous secretion, alteration of pavement cells (PVCs), detachment of the secondary epithelium, pillar cell degeneration, degeneration, and apoptosis. Trough immunohistochemistry and real-time PCR analysis also showed a dose-related modulation of Na+/K+-ATPase and MTs.

Integrated biomarker response: An approach to assess antioxidant response in nesting green turtles

To extend the current understanding of the mercury-mediated cytotoxic effect, five neural cell lines established from different animal species were comparatively analyzed using three different endpoint bioassays: thiazolyl blue tetrazolium bromide, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay (MTT), neutral red uptake assay (NRU), and Coomassie blue assay (CB). Following a 24-hr exposure to selected concentrations of mercury chloride (HgCl2) and methylmercury (II) chloride (MeHgCl), the cytotoxic effect on test cells was characterized by comparing their 50% inhibition concentration (IC50) values. Experimental results indicated that both these forms of mercury were toxic to all the neural cells, but at very different degrees. The IC50 values of MeHgCl among these cell lines ranged from 1.15 ± 0.22 to 10.31 ± 0.70 μmol/L while the IC50 values for HgCl2 were much higher, ranging from 6.44 ± 0.36 to 160.97 ± 19.63 μmol/L, indicating the more toxic nature of MeHgCl. The IC50 ratio between HgCl2 and MeHgCl ranged from 1.75 to 96.0, which confirms that organic mercury is much more toxic to these neural cells than inorganic mercury. Among these cell lines, HGST-BR and TriG44 derived from marine sea turtles showed a significantly high tolerance to HgCl2 as compared to the three mammalian neural cells. Among these neural cells, SK-N-SH represented the most sensitive cells to both chemical forms of mercury.

In vitro evaluation of inorganic and methyl mercury mediated cytotoxic effect on neural cells derived from different animal species

To extend the current understanding of the mercury-mediated cytotoxic effect, five neural cell lines established from different animal species were comparatively analyzed using three different endpoint bioassays: thiazolyl blue tetrazolium bromide, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay (MTT), neutral red uptake assay (NRU), and Coomassie blue assay (CB). Following a 24-hr exposure to selected concentrations of mercury chloride (HgCl2) and methylmercury (II) chloride (MeHgCl), the cytotoxic effect on test cells was characterized by comparing their 50% inhibition concentration (IC50) values. Experimental results indicated that both these forms of mercury were toxic to all the neural cells, but at very different degrees. The IC50 values of MeHgCl among these cell lines ranged from 1.15±0.22 to 10.31±0.70μmol/L while the IC50 values for HgCl2 were much higher, ranging from 6.44±0.36 to 160.97±19.63μmol/L, indicating the more toxic nature of MeHgCl. The IC50 ratio between HgCl2 and MeHgCl ranged from 1.75 to 96.0, which confirms that organic mercury is much more toxic to these neural cells than inorganic mercury. Among these cell lines, HGST-BR and TriG44 derived from marine sea turtles showed a significantly high tolerance to HgCl2 as compared to the three mammalian neural cells. Among these neural cells, SK-N-SH represented the most sensitive cells to both chemical forms of mercury.

Effect of mercuric chloride on terrestrial slug Semperula maculata and histopathology of reproductive organs: a comprehensive study

Since the last few decades, terrestrial diversity is found to be under stress due to the contamination by various chemicals and gases of aquatic and agricultural media. The bioaccumulation of these compounds at certain concentrations in different tissues produces histopathological changes leading to behavioral changes in target animals. This study focused on terrestrial molluscan slug, Semperula maculata, against lethal concentrations of mercury chloride (HgCl2). Bioaccumulation of Hg was highest in ovotestis, while lowest in the molluscan penis. Histopathological changes were observed in the cellular arrangement of reproductive organs. Alterations in the penis and the dart gland included dilated unicellular, multicellular glands, and muscular dystrophy, dilated peripheral glandular cells, respectively; dilation being maximal in the prostate gland. Ovotestis showed depleted number of gametocytes. Vacoulized pre-vitellogenic oocytes with early vitellogenic oocytes were noted under light microscopy. Mercury produced toxicity on secretory functions and lowered the rate of reproduction in animals. Evidence indicates that Hg produced gamete degeneration, impacted reproductive capacity and survival of this species in the ecosystem.

Ameliorative effect of ascorbic acid on mercury chloride-induced changes on the spleen of adult wistar rats

Introduction: Mercury is a highly toxic metal that exerts its adverse effects on the health of humans and animals through air, soil, water and food. Aim: The present study was aimed at the evaluation of the effects of ascorbic acid on mercury chloride-induced changes on the histomorphology of the spleen of adult Wistar Rats. Method: Thirty adult Albino Wistar Rats of average weight of 200g were randomly divided into six groups of five rats per group. The animals were orally administered with different concentrations of mercury chloride daily for three weeks. Group one was administered with normal saline, Group two and three were administered with 52mg/kg body weight and 26.25mg/kg body weight of mercury chloride respectively while Groups four and five were administered with 52mg/kg of mercury chloride and 5mg/kg of ascorbic acid and 26.25mg/kg of mercury chloride and 5mg/kg of ascorbic acid respectively and Group 6 was administered 5mg/kg of ascorbic acid only. After three weeks of administration, the animals were sacrificed, blood and tissue samples were collected for tissue processing and analysis. Results: The results showed histo-morphological changes in the spleen of the rats. These changes were shown to be concentration dependent. Conclusion: Ascorbic acid administration was able to ameliorate mercury-induced changes in the spleen of adult Wistar rats.

Effect of Ascorbic acid on Mercury-induced changes on the liver in Adult Wistar Rats

Mercury is among the heavy metals that have been reported to cause devastating health problems worldwide. The present work was aimed at investigating the effects of mercury chloride and Vitamin C administration on the cyto-architecture of the liver and some liver parameters. Thirty adult Wistar Rats of average weight of 200g were randomly divided into six groups of five rats per group. The animals were administered with different concentrations of mercury chloride orally for three weeks. Group one was the Control and was administered with normal saline, Groups two and three were administered with 52mg/kg body weight and 26.25mg/kg body weight of mercury chloride respectively while Groups four and five were administered with 52mg/kg of mercury chloride +5mg/kg of ascorbic acid and 26.25mg/kg of mercury chloride+5mg/kg of ascorbic acid respectively and Group 6 was administered 5mg/kg of ascorbic acid only. After three weeks of administration, the animals were sacrificed humanely, blood and tissue samples were collected for analysis. The results showed there was significant increase in liver biochemical parameters such as AST, ALT and ALP levels in the serum of treated animals (p<0.05). The result showed that the administration of ascorbic acid resulted in ameliorative effects on biochemical parameters and the effect was most pronounced on the liver of treated rats at higher concentrations of mercuric chloride which was dose dependent.

Effect of Mercuric Chloride on Some Hematological, Biochemical Parameters in Silver Carp (Hypophthalmichthys Molitrix)

The mutual action between a toxicant and a biological system can be calculated using hematological, biochemical biomarkers. The immunological, hematological and biochemical indices of silver carp (Hypophthalmichthys molitrix ) were investigated under low (10%LC50) and high (50%LC50) concentrations of mercury chloride for 96h. In both concentrations Ht, Hb, RBC, lymphocyte were significantly (p<0/05, p<0/01) lower than controls group whereas MCH, MCHC, WBC, Glucose, neutrophil, eosinophil were significantly (p<0/05, p<0/01) larger contrasted to the respective controls group. In low and high concentrations MCV, cortisols respectively were lower than control group. A significant decrease in high concentrations in cortisol level may be as cortisol suppression due to high stresses. The consequential discoveries of this study are that mercury chloride concentrations (low and high) may cause some substitutions in the hematological, biochemical and immunological parameters of the studied fish, so estimation of these indices, could supply a useful indicator of mercury chloride of water bodies. It appears that MCH, eosinophil in low concentrations and lymphocyte in high concentrations is appropriate biomarkers of mercury chloride in silver carp .

Chronic exposure to low mercury chloride concentration induces object recognition and aversive memories deficits in rats

This work examines the effects of chronic exposure to low inorganic mercury (mercury chloride, HgCl2) concentration on the recognition and aversive memories. Forty male Wistar rats were divided into 4 groups treated during 30 or 60 days with saline (control) or HgCl2 doses. After treated the animals were tested considering object recognition and inhibitory avoidance behavioral memory paradigms. Elevated plus maze, open field and tail flick tests were used to assess anxiety, locomotor and exploratory activity and pain thresholds. Only exposure for 60 days to HgCl2 induced in memory deficits quantified in the object recognition task. In the inhibitory avoidance all the animals exposed to mercury (for 30 or 60 days) presented worst performance than control animals. Our results suggest that chronic exposure to low mercury chloride concentrations impairs memory formation.

Biochemical response of the African catfish, Clarias gariepinus (Burchell, 1822) to sublethal concentrations of mercury chloride with supplementation of selenium and vitamin E

The present investigation aimed to determine the toxicological effects of mercury chloride on biochemical parameters of the widely consumed African catfish, Clarias gariepinus. Adult specimens of Clarias gariepinus were exposed to sublethal concentrations (0.04 and 0.12 ppm) of mercury chloride for 7, 14, 21 and 28 days. Empirical data of results obtained were subjected to statistical analysis of variance (ANOVA) to test the effects of mercury, selenium, vitamin E and exposure periods. The mean values of Na+, Urea, Creatinine, AST, ALT and ALP were significantly increased from the control values, while mean values of K+, Glucose and Triglyceride were significantly decreased from the control values. Selenium and Vitamin E supplementation play appositive role in detoxification of mercury toxicity specially the low dose. The results suggest that mercury chloride can negatively affect the physiology of fish. It was observed that supplementation of selenium and vitamin E decreases the toxic effect of mercury.

Endocrine disruptions induced by artificial induction of mercury chloride on sea bream

There are a large number of chemicals, which are released into the Persian Gulf, capable of interfering with the synthesis and action of natural thyroid and testosterone hormones. These are considered as endocrine disruptors. In the present study, sea bream was exposed to four different concentrations (10, 20, 40, 80 μg l−1) of the widely used mercury chloride in a laboratory condition, and effects on the concentrations of serum testosterone and thyroid (T3 and T4) were assayed. Mercury chloride exhibited significant effects on both T3 and T4 (P 0.5); however, exposure to higher mercury chloride concentration showed suppressive effects on serum testosterone. Results of the present experiment indicated that mercury chloride induced alteration in the structure of the gonad and thyroid and can be considered as an endocrine disruptor substance in yellowfin sea bream.

In vivo genotoxicity of mercury chloride and lead acetate: Micronucleus test on acridine orange stained fish cells

The genotoxic effects of mercury chloride and lead acetate were evaluated in vivo using the micronucleus (MN) assay on acridine-orange (AO) stained peripheral blood erythrocytes, gill and fin epithelial cells of Carassius auratus auratus. Fish were exposed to three different concentrations of mercury chloride (MC) (1 μg/, 5 μg/L and 10 μg/L) and lead acetate (LA) (10 μg/L, 50 μg/L and 100 μg/L) for 2, 4 and 6 days. A single dose of 5 mg/L cyclophosphamide was used as a positive control. In addition to micronuclei, nuclear buds (NBs) were assessed in the erythrocytes. The ratio of polychromatic and normochromatic erythrocytes (PCE/NCE) in peripheral blood was also evaluated to assess cytotoxicity. MN frequencies in all three tissues were elevated in fish exposed to both LA and MC. However, NBs showed different sensitivity to metal treatments. MN frequencies in both control and treated fish were highest in gill cells and generally lower in erythrocytes and fin cells. PCE/NCE rations decreased in relation to MC and LA treatments. The results of this study indicate that LA and MC have genotoxic and cytotoxic damage in fish and confirmed that AO staining is a suitable technique for in vivo MN test in fish.