Digital light microscopy as a tool in toxicological evaluation of fish erythrocyte morphological abnormalities

Mitigation of haemato-genotoxic and stress response effects in Cyprinus carpio via silymarin dietary supplementation following deltamethrin exposure

The study examined the potential of Silymarin, a blend of bioactive flavonolignans extracted from the milk thistle Silybum marianum, to mitigate Deltamethrin-induced toxicity in the blood of Cyprinus carpio. Fish were exposed to Deltamethrin (0.66 μg/L), the plant extract, or a combination of both for a duration of thirty days. Various parameters, including serum biochemical markers, erythrocytic abnormalities, and genotoxicity endpoints, were assessed. Results indicated a significant (p < 0.05) increase in the levels of AST, ALT, ALP, blood urea nitrogen, creatinine, glucose, cholesterol, and TLC in the fish exposed to the pesticide. Conversely, total protein, TEC, and Hb showed a notable decrease. There was also a notable rise in micronuclei and erythrocytic abnormalities such as acanthocytes, microcytes, and notched cells. Under ultrastructural examination, phenotypic deformities like spherocytosis, discocytes, and clumped erythrocytes were observed. However, dietary supplementation of silymarin (1 g/kg) significantly restored the biochemical, genetic, and cellular parameters, resembling those of the control group. This suggests the potential of this plant extract in protecting the common carp, Cyprinus carpio, from Deltamethrin-induced damage by scavenging free radicals and reducing DNA oxidative stress.

Assessment of dietary polyvinylchloride, polypropylene and polyethylene terephthalate exposure in Nile tilapia, Oreochromis niloticus: Bioaccumulation, and effects on behaviour, growth, hematology and histology

Microplastics (MPs) have been recognized as emerging aquatic pollutants receiving major concern due to their detrimental effects on aquatic life. Nile Tilapia, Oreochromis niloticus is a model species considered in toxicological studies to address the effects of pollutants in freshwater animals. However, comprehensive knowledge comparing the impacts on fish across various MPs polymers is scarce. Therefore, the overarching aim of the current study was to examine the bioconcentration of MPs polymers: polyvinylchloride (PVC), polypropylene (PP), and polyethylene terephthalate (PET), and their toxic effects on growth, and behavioral responses, hematology, and histology of gills, liver, and intestine in O. niloticus. Fishes were subjected to a 21-day dietary exposure to MPs by assigning them into six treatment groups: T1 (4% of PVC), T2 (4% of PP), T3 (4% of PET), T4 (8% of PVC), T5 (8% of PP), T6 (8% of PET), and control (0% of MPs), to assess the effects on fish across the polymers and dosage. Results showed several abnormalities in anatomical and behavioral parameters, lower growth, and high mortality in MPs-exposed fish, indicating a dose-dependent relationship. The elevated dosage of polymers raised the bioavailability of PVC, PP, and PET in gills and gut tissues. Noteworthy erythrocyte degeneration referred to cytotoxicity and stress imposed by MPs, whereas the alterations in hematological parameters were possibly due to blood cell damage, also indicating mechanisms of defense against MPs toxicity. Histopathological changes in the gills, liver, and intestine confirmed the degree of toxicity and associated dysfunctions in fish. A higher sensitivity of O. niloticus to PET-MPs compared to other polymers is likely due to its chemical properties and species-specific morphological and physiological characteristics. Overall, the present study reveals valuable insights into the emerging threat of MPs toxicity in freshwater species, which could be supportive of future toxicological research.

Erythrocyte alterations in specimens of Danio rerio caused by exposure to metformin

The antidiabetic drug metformin is widely prescribed around the world. However, its permanence in different environmental concentrations has been associated with adverse toxicological effects in organisms that do not target its therapeutic action. In the aquatic environment, fish such as the Zebrafish (Danio rerio) have been considered potential bioindicators of environmental impacts and used as experimental models in toxicological studies due to the sensitivity of these species to different types of contaminants, including pharmaceuticals. Thus, this study aimed to analyze metformin's cytotoxic effects on Danio rerio erythrocytes. The animals were submitted to different concentrations of the drug (50 µg/L, 100 µg/L, 150 µg/L, and 10000 µg/L) for 365 days and subsequently observed employing light microscopy and scanning electron microscopy (SEM) to evaluate the alterations that occurred. Exposure of animals to metformin led to significant erythrocyte cell abnormalities across all tested concentrations, with a particularly pronounced effect at the higher concentration previously defined as the NOEC (No Observed Effect Concentration). Remarkable abnormalities included cytoplasmic vacuoles, echinocytes, and vesicle-like cytoplasmic fragments. These findings suggest that metformin, even at concentrations similar to those found in nature and at the NOEC level, exhibits cytotoxic potential in D. rerio, raising concerns about its potential health impacts.

"From shadows to shores"-quantitative analysis of CuO nanoparticle-induced apoptosis and DNA damage in fish erythrocytes: A multimodal approach combining experimental, image-based quantification, docking and molecular dynamics

The usage of copper (II) oxide nanoparticles (CuO NPs) has significantly expanded across industries and biomedical fields. However, the potential toxic effects on non-target organisms and humans lack comprehensive understanding due to limited research on molecular mechanisms. With this study, by combining the 96 h in vivo exposure of crucian carp fish, Carassius carassius, to sub-lethal CuO NPs doses (0.5 and 1 mg/dL) with image-based quantification, and docking and molecular dynamics approaches, we aimed to understand the mechanism of CuO NPs-induced cyto-genotoxicity in the fish erythrocytes. The results revealed that both doses of copper NPs used were toxic to erythrocytes causing oxidative stress response and serious red blood cell morphological abnormalities, and genotoxicity. Docking and 10-ns molecular dynamics confirmed favorable interactions (ΔG = -2.07 kcal mol-1) and structural stability of Band3-CuO NP complex, mainly through formation of H-bonds, implying the potential of CuO NPs to induce mitotic nuclear abnormalities in C. carassius erythrocytes via Band3 inhibition. Moreover, conventional and multiple ligand simultaneous docking with DNA revealed that single, double and triple CuO NPs bind preferentially to AT-rich regions consistently in the minor grooves of DNA. Of note, the DNA-binding strength subtantially increased (ΔG = -2.13 kcal mol-1, ΔG = -4.08 kcal mol-1, and ΔG = -6.03 kcal mol-1, respectively) with an increasing number of docked CuO NPs, suggesting that direct structural perturbation on DNA could also count for the molecular basis of in-vivo induced DNA damage in C. carassius erythrocytes. This study introduces the novel term "erythrotope" to describe comprehensive red blood cell morphological abnormalities. It proves to be a reliable and cost-effective biomarker for evaluating allostatic erythrocyte load in response to metallic nanoparticle exposure, serving as a distinctive fingerprint to assess fish erythrocyte health and physiological fitness.

Erythrocyte Recovery in Oreochromis niloticus Fish Exposed to Urban Effluents

Urban activities pollute aquatic ecosystems, and the integrity of organisms such as fish. The use of cytological techniques, such as the analysis of blood cellular integrity using the Micronucleus test, can help detect mutagenic damage as a result to urban effluents exposure. In this context, this study aimed to evaluate the frequency of micronucleus and other nuclear abnormalities in Oreochromis niloticus fish environmentally exposed to urban effluents in relation to their erythrocyte recovery capacity when exposed to clean water (30 and 45 days). The results indicated high copper, dissolved iron, nickel, and thermotolerant coliform levels in the urban stream. There was no difference in the frequency of micronuclei. In contrast, cells with nuclear nuclei, binucleates, kidney-shaped nuclei, notched nuclei, lobed nuclei, and segmented nuclei decreased according to the time the fish were exposed to clean water. When exposed to clean water, we conclude that urban fish recover from genotoxic and cytotoxic damage.

Toxic effects of sub-acute microplastic (polyamide) exposure on the accumulation, hematological, and antioxidant responses in crucian carp, Carassius carassius

The purpose of this study is to investigate the impact of microplastics (MPs) on fish and to confirm the toxic effects of MPs on fish, as well as to clarify the standard indicators. MPs are present in a large amount in the aquatic environment and can have various adverse effects on aquatic animals. Crucian carp, Carassius carassius (mean weight, 23.7 ± 1.6 g; mean length, 13.9 ± 1.4 cm), were exposed to PA (Polyamide) concentrations of 0, 4, 8, 16, 32 and 64 mg/L for 2 weeks. The PA accumulation profile in C. carassius decreased from the intestine to the gill to the liver. Hematological parameters such as red blood cell (RBC) counts, hemoglobin (Hb), and hematocrit (Ht) notably decreased at high levels of PA exposure. Plasma components such as calcium, magnesium, glucose, cholesterol, total protein, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) were significantly altered by PA exposure. The activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and glutathione (GSH) of liver, gill and intestine significantly increased following PA exposure. The results of this study suggest that MP exposure affects the hematological physiology and antioxidant responses in C. carassius as well as accumulation in specific tissues.

Impact of Camellia sinensis Iron Oxide Nanoparticle on Growth, Hemato-biochemical and Antioxidant Capacity of Blue Gourami (Trichogaster trichopterus) Fingerlings

The effect of green tea (Camellia sinensis) iron oxide nanoparticles (nano-Fe) on the effectiveness, growth, antioxidant capacity, and immunological response of Trichogaster trichopterus (Blue gourami) fingerlings was investigated. UV-Visible, Fourier Transform Infrared, Scanning Electron Microscopy, Energy Dispersive X-ray, X-ray diffraction, Dynamic Light Scattering, and Zeta Potential spectroscopy were used to evaluate the biologically synthesized nano-Fe. Characterization revealed the hexagonal and spherical morphology with an average diameter of 114 nm. Six different experimental diets were supplied to the fish in duplicate for 60 days. The first diet served as a control (no nano-Fe supplementation), whereas the remaining five diets contained nano-Fe at concentrations of 10, 20, 30, 40, and 50 mg/kg (D1 to D5). The results indicated that fish fed a nano-Fe diet at a concentration of 40 mg/kg had improved growth performance, biochemical constituents, hematological parameters, and antioxidant activity in T. trichopterus, implying that it might be used as a vital feed supplement in ornamental fish culture.

Are BPA-free plastics safe for aquatic life? - Fluorene-9-bisphenol induced thyroid-disrupting effects and histopathological alterations in adult zebrafish (Danio rerio)

Fluorene-9-bisphenol (BPFL) is used as an alternative compound for bisphenol A, an endocrine disruptor compound which is present in various materials including plastic bottles and packaging. Although it is used extensively in products that are labelled BPA-free, its effect on wildlife and humans have not been fully studied. Therefore, this study aimed to investigate the effects of BPFL in adult zebrafish. In the preliminary experiments of the study, the median lethal concentration value (LC₅₀) of BPFL was 0.25 mg/L (95 % confidence interval 0.15-0.41) for 96 h. Following exposure to three different sublethal concentrations of BPFL after 96 h and 15 days, T4 hormone levels, expression levels of genes involved in thyroid metabolism and histopathological alterations were assessed. T4 hormone levels were found to be significantly higher in females at the lowest BPFL concentration following 96 h exposure (P < 0.05). Expression levels of trh, tshba and trhrb genes were upregulated following 96 h exposure at 0.025 mg/L concentration and crh was upregulated following 15 days exposure at 0.025 mg/L concentration in female zebrafish (P < 0.05). The most prominent histopathological findings in zebrafish exposed to 0.025 and 0.125 mg/L of BPFL were observed in the gill, liver, kidney and testis tissues. The gill tissues showed some hyperemia, lamellar fusion, hyperplasia, epithelial lifting, and telangiectasis, while passive hyperemia, hydropic degeneration, and necrosis were observed in the liver tissues. The BPFL is highly toxic to zebrafish even in sublethal concentrations according to the molecular and histopathological responses.

Antioxidant enzyme activity and pathophysiological responses in the freshwater walking catfish, Clarias batrachus Linn under sub-chronic and chronic exposures to the neonicotinoid, Thiamethoxam®

The hydrophilic nature and resultant persistence of neonicotinoids in aquatic systems increase the exposure duration for non-target organisms. The sublethal toxicity of the neonicotinoid Thiamethoxam® spanning sub-chronic and chronic durations was investigated in Clarias batrachus, a non-target freshwater fish species. 96 h LC₅₀ value of Thiamethoxam® on Clarias batrachus was 138.60 mg L^-1. Pre-determined exposure concentrations of Thiamethoxam® (6.93 and 13.86 mg L^-1) were used and effects were assessed at days 15, 30, and 45 exposure intervals. Biomarker effects were evaluated using antioxidant enzyme responses (CAT, SOD) neurotransmission (acetylcholinesterase activity), haematological and serum biochemistry changes (including haemoglobin content, total erythrocyte count, and serum albumin total leukocyte count, total serum protein, serum globulin, triglyceride, cholesterol, high-density lipoprotein, very low-density lipoprotein, low-density lipoprotein, phospholipid, and total serum glucose), histopathological alterations (gill and liver). Thiamethoxam®-exposed fish showed a marked reduction in haemoglobin content, total erythrocyte count, and serum albumin levels compared to control fish. Similarly, gill and liver antioxidant enzyme activity (CAT, SOD) and neurotransmission (acetylcholinesterase) also showed altered responses between sub-chronic exposure on day-15 and chronic responses on day-45. Histopathological observations in gill tissue revealed alterations ranging from vacuolation, hypertrophy, disruption of primary lamellar architecture, haemorrhage, the fusion of secondary lamella, and sloughing of outer epithelia. For liver tissue of exposed fish histopathological observations included increased sinusoidal spaces (ISS), necrosis of hepatocytes (NOH), nuclear degeneration (ND), disruption of architecture (DOA), macrophage infiltration of the central vein, vacuolation (V), hypertrophied hepatocytes, and haemorrhages. The gradients of toxic responses across exposure concentrations and depictions of impaired fish health with increasing thiamethoxam® exposure duration portend lowered physiological capacity for survival in the wild.

Ecotoxicological Effects of Pesticides on Hematological Parameters and Oxidative Enzymes in Freshwater Catfish, Mystus keletius

Hematological parameters and changes in stress-induced functionalities of cellular enzymes have been recognized as valuable tools for monitoring fish health and determining the toxic effects of pesticides. The present study was conducted to evaluate the toxic effect of selected pesticides viz., Ekalux (EC-25%), Impala (EC-55%), and Neemstar (EC-15%) on freshwater catfish Mystus keletius. Fish were exposed to sub-lethal concentrations (mg/L) of the selected pesticide for a period of 7, 14, 21, and 28 days. Hematological parameters viz., total erythrocyte (RBC), hemoglobin (Hb), and hematocrit (Ht) packed cell volume values decreased with an increase in exposure time to pesticides, whereas the values for parameters viz., leucocytes (WBC), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH) increased significantly. A decrease in packed cell volume (PCV) and hemoglobin values coupled with decreased and deformed erythrocytes as signs of anemia were also observed. The effect of pesticides on RBC content was 1.43 (million/mm3) on day 7 and reduced to 1.18 (million/mm3) on days 14 and 21. A similar trend was found for Impala on RBC, which had an initial value of 1.36 (million/mm3) on day 7 and reached a value of 1.10 (million/mm3) on day 28. In contrast, the value of Neemstar decreased from 1.59 (million/mm3) on day 7 in control to 1.02 (million/mm3) on day 28. Data indicates that the order of toxic effect of pesticides recorded a maximum for Impala followed by Ekalux and Neemstar in the selected fish model. Likewise, the overall pattern of pesticidal activity on cellular enzymes (GDH, MDH, and SDH) recorded a maximum toxic effect for Impala followed by Ekalux and Neemstar. Results indicate that Chlorpyrifos pesticide-Impala evoked maximum toxic effect on selected tissues compared to the other two pesticides tested. Statistical analysis of the summative data using two way ANOVA was statistically significant (p-value < 0.001). The differences in the hematological parameters analyzed are attributed to the physiological acclimatization of the fish to the local conditions, which influences the energy metabolism and consequently determines the health status of the fish. Overall, Impala exhibited the highest pesticidal activity on cellular enzyme, followed by Ekalux and Neemstar. Results suggest that natural pesticides may be preferable for rice field application in terms of environmental safety.

Effects of heavy metals on fish physiology - A review

The pollution by heavy metals poses a serious threat to the aquatic environment and to the organisms if the concentration of heavy metals in the environment exceeds the safe limits. Due to their non-biodegradable and long persistence nature in the environment, heavy metals cause toxicity in fish by producing oxygen reactive species through oxidizing radical production. In this review, we investigated the effects of heavy metals on fish physiology with special emphasis on hemato-biochemical properties, immunological parameters especially hormones and enzymes, histopathology of different major organs and underlying molecular mechanisms. All those parameters are significantly affected by heavy metal exposure and are found to be important bio-monitoring tools to assess heavy metal toxicity. Hematological and biochemical alterations have been documented including cellular and nuclear abnormalities in different fish species exposed to different concentrations of heavy metals. Major fish organs (gills, liver, kidneys) including intestine, muscles showed different types of pathology specific to organs in acute and chronic exposure to different heavy metals. This study also revealed the expression of different genes involved in oxidative stress and detoxification of heavy metals. In a nutshell, this article shades light on the manipulation of fish physiology by the heavy metals and sought attention in the prevention and maintenance of aquatic environments particularly from heavy metals contaminations.

Metal accumulation and morphofunctional damage in coelomocytes of earthworm collected from industrially contaminated soil of Kolkata, India

The current study is aimed to assess the ecotoxicological effects of toxic metals and seasonal shift of the physicochemical characteristics of soil in an endogeic earthworm Metaphire posthuma of industrially contaminated soil of Calcutta leather complex. The accumulation of cadmium, chromium, lead and mercury was quantitated in whole earthworms and coelomocytes. The accumulation of metals was derived to be high in the coelomocytes than whole earthworms. Morphofunctional shift in coelomocytes indicated a high level of metal toxicity in soil inhabitants. The shift in differential coelomocyte count and cellular damage including intense cytoplasmic vacuolation and membrane blebbing of coelomocytes of M. posthuma of contaminated soil were suggestive to a state of immunocompromisation in the same species. Shift in the generation of nitric oxide and activity of inducible nitric oxide synthase indicated a possible immunosuppression in earthworm. Depletion in the acetylcholinesterase activity of coelomocytes indicated neurotoxicity of metals leached from the dumped wastes in Calcutta leather complex. Integrated biomarker response based analysis was carried out to assess the biomarker potential of experimental endpoints of M. posthuma to monitor metal toxicity in soil.

Contrasting tourism regimes due to the COVID-19 lockdown reveal varied genomic toxicity in a tropical beach in the Southern Atlantic

Tourist occupancy in coastal environments threatens the stability of various coastal ecosystems and is thus a cause for concern for the environmental sector. As such, it is important to perform environmental monitoring in a way that analyses and quantifies the environmental impact of coastal ecosystems. Porto de Galinhas beach (Pernambuco - Brazil) has one of the highest visitation rates in Brazil and suffered from restrictions to human mobility due to the COVID-19 pandemic. These restrictions allowed for the evaluation of the impact of tourism on Porto de Galinhas beach and the effects that the lack of tourist occupancy had during the lockdown period of 2020. Blood samples from the species Abudefduf saxatilis were collected monthly over a period of 1 year and during the lockdown quarter, in order to perform micronucleus (MN) and nuclear morphological alteration (NMA) tests, and data were analyzed at a seasonal level (dry/rainy period) using a comet assay. For the control group, A. saxatilis samples were collected in an environmentally protected area on Tamandaré beach (68 km from Porto de Galinhas). The MN and NMA tests showed a greater frequency of genomic damage when there was greater tourist flow. In relation to rain seasonality, the comet assay showed a greater incidence of genomic damage during the dry period, where there was a higher rate of tourist migration, compared to the rainy period. The lockdown period presented a lower incidence of genotoxic damage compared to the period without restrictions on human mobility and the control. The results show that tourism has been causing a significant environmental impact on Porto de Galinhas beach. The data collected during the lockdown period demonstrated how the absence of human movement results in changes that are favorable to environmental recuperation, as illustrated by the lower frequency of genomic damage.

In vivo genotoxic effects of commercial grade cypermethrin on fish peripheral erythrocytes

The study explicates the genotoxic effects of commercial grade cypermethrin on peripheral erythrocytes of Catla catla, chronically exposed to two environmentally relevant concentrations. The fish was treated with sub-lethal concentrations 0.12 μg/L and 0.41 μg/L (1/10th and /1/3rd of 96 h LC₅₀ ) of cypermethrin for 45 days. DNA damage in the exposed fish was assessed using alkaline comet assay, presence of micronuclei (MN), erythrocyte nuclear and cytoplasmic abnormalities. Exposure to cypermethrin induced a dose-dependent increase in percent DNA damage, micronucleus frequency and erythrocyte abnormalities. Nuclear anomalies such as notched nuclei, lobed nuclei, bridged nuclei, and deformed nuclei; and cytoplasmic anomalies like anisochromasia, vacuolated cytoplasm, lobed cells, and echinocytes were observed. The findings revealed the genotoxic potential of commercial formulations pyrethroid cypermethrin at concentrations found in the environment and their potential deleterious effects on nontarget aquatic organisms.

Effects of short-term selenium exposure on respiratory activity and proximate body composition of early-life stages of Catla catla, Labeo rohita and Cirrhinus mrigala

Metal exposure impairs respiration, increases metabolic demand, and reduces energy storage/fitness in aquatic species. Respiratory impairment and energy storage was examined in acute selenium-exposed Indian major carps, Catla catla, Labeo rohita and Cirrhinus mrigala fry and were correlated with exposure concentrations. Toxicity effects were determined in a renewal bioassay using 96 h lethal selenium concentrations. Species sensitivity distribution (SSD) was also used to derive predicted no-effect concentrations, toxicity exposure ratios, for selenium exposures to early-life fish stages. Mortality was proportional with increasing concentrations. Oxygen consumption and lipid content compared to moisture and ash and of all protein content in tissues of C. catla and C. mrigala indicates that lowered oxygen consumption is directly predictive of lowered lipid content and selenium-induced hypoxia impacts the energy/nutritional status of the early-life stage of carp. This cross-taxa comparison will have major implications for advancing impact assessment and allow better targeting of species for conservation measures.

Dietary lysine requirements of Colossoma macropomum (Cuvier, 1818) based on growth performance, hepatic and intestinal morphohistology and hematology

This study aimed to determine the dietary lysine requirements of juvenile Colossoma macropomum tambaqui based growth performance, hepatic and intestinal morphohistology and hematology. Tambaqui were fed with levels of 6.60, 9.72, 12.84, 15.96, 19.08, and 22.20 g/kg of total lysine and those who received 15.96 g/kg dietary lysine showed higher final weight (p= 0.001) and optimized feed conversion ratio (p= 0.001). Morphohistological modifications (presence of fat droplets) were present in livers of fish fed with low levels of lysine. In the morphohistology of the intestine, the diets influenced the density of the intestinal, cell layers, height and perimeters of the villi and acid mucin secretion by the goblet cells. In the proximal intestine, mucosa layer density was greater at the level of 15.96 g/kg (p= 0.001). In the middle intestine, height (p= 0.001) and perimeter (p= 0.001) of the villi were greater at low levels of lysine (respectively, 9.72 and 12.84 g/kg dietary lysine). No differences were found for the hemoglobin, hematocrit, erythrocytes, MCV, MCH, MCHC, thrombocytes and leukocytes differentiated of fish fed with experimental diets (p>0.05). The biochemical responses were affected by the diet, both in plasma concentration (protein and cholesterol; p<0.05), and in muscle (ash and moisture; p<0.05). In conclusion, the dietary requirement for lysine for tambaqui juveniles was estimated to be 15.4 - 15.6 g/kg of diet (5.7% -5.8% dietary protein).

Effect of benzophenone-3 on the blood cells of zebrafish (Danio rerio)

Benzophenone-3 (BP-3) is a common component of organic sunscreen widely used that can affect especially aquatic ecosystems health, including fish. To verify the biological effects of low concentrations of BP-3 on blood cells, one hundred and forty zebrafish (D. rerio) were used and then randomly divided into five groups: control group (water), solvent group (alcoholic water), and BP-3 group (BP-3 at 7 µg L^-1, BP-3 at 70 µg L^-1, and BP-3 at 700 µg L^-1). The blood slices were stained with Panoptic stain and with Giemsa solution for the hematological analysis. During the exposure to BP-3, no behavioral changes were observed. Although no significant difference in total leukocytes occurred, an increase in neutrophils and a reduction of lymphocytes at the highest concentration on both 7th and 14th days were detected. The total and cytoplasmic area of erythrocytes on the 7th day at the highest concentration were reduced. In addition, alterations on the erythrocyte nuclear morphology in fish exposed to BP-3 were usually visualized, mainly when considered the occurrence of blebbed nucleus and micronucleus, indicating that BP-3 exhibits cytotoxic and mutagenic effects. The results indicate that BP-3 can interfere with the morphophysiology of aquatic organisms.

Imperative role of electron microscopy in toxicity assessment: A review

Electron microscope (EM) was developed in 1931 and since then microscopical examination of both the biological and non-biological samples has been revolutionized. Modifications in electron microscopy techniques, such as scanning EM and transmission EM, have widened their applicability in the various sectors such as understanding of drug toxicity, development of mechanism, criminal site investigation, and characterization of the nano-molecule. The present review summarizes its role in important aspects such as toxicity assessment and disease diagnosis in special reference to SARS-COV2. In the biological system, EM studies have elucidated the impact of toxicants at the ultra-structural level in various tissue in conformity to physiological alterations. Thus, EM can be concluded as an important tool in toxicity assessment and disease prognosis.

Cytopathological and ultrastructural changes in the male reproductive organs of freshwater crab Paratelphusa jacquemontii (Rathbun) exposed to nurocombi

Accumulation of pollutants in the aquatic system has a high impact on the reproductive physiology of crustaceans. The objective of the present study was to assess the possible histopathological effects of combined chlorpyrifos and cypermethrin (nurocombi) exposure on reproductive tissue in male freshwater crab Paratelphusa jacquemontii using light and electron microscopy. The testis of experimental crabs showed disorganization of testicular lobules, increased inters cellular space, necrosis, and cellular damage in both germinal cells and Sertoli cells. The treated vas deferens exhibited epithelial degeneration, misshaped spermatophores, decline in the number of spermatophores, and dehiscence of spermatophore wall. These clinical manifestations expressed in crabs following the exposure of nurocombi significantly reduce the testicular activity and substantially inhibits the seminal secretions, which ultimately lead to impairment of reproduction.

Chronic Effects of Diazinon® Exposures Using Integrated Biomarker Responses in Freshwater Walking Catfish, Clarias batrachus

Diazinon exposures have been linked to the onset of toxic pathways and adverse outcomes in aquatic species, but the ecological implications on model species are not widely emphasized. The objective of this study was to determine how the organophosphate pesticide diazinon affected hematological (hemoglobin, total red blood count, total white blood count, and mean corpuscular hemoglobin), growth (condition factor, hepatosomatic index, specific growth rate), biochemical (total serum glucose, total serum protein), and endocrine (growth hormone, tri-iodothyronine, and thyroxine) parameters in Clarias batrachus after chronic exposure. Diazinon was administered at predefined exposure doses (0.64 and 1.28 mg/L) and monitored at 15, 30, and 45 days into the investigation. Observation for most biomarkers revealed patterns of decreasing values with increasing toxicant concentration and exposure duration. Correlation analysis highlighted a significant inverse relationship between variables (mean corpuscular hemoglobin, condition factor, specific growth rate, tri-iodothyronine, thyroxine, and total serum protein) and elevated chronic diazinon exposure concentrations. The integrated indices (IBR and BRI) indexes were used to provide visual and understandable depictions of toxicity effects and emphasized the relativity of biomarkers in terms of sensitivity and magnitude or severity of responses under graded toxicant exposures. The significant damage reflected by evaluated parameters in diazinon exposure groups compared to control portends risks to the health of local fish populations, including Clarias batrachus in aquatic systems adjacent to agrarian landscapes.

Growth performance, hematological responses and economic indexes of Colossoma macropomum (Cuvier, 1818) fed graded levels of glycerol

The aim of this study was to evaluate the performance, hematological responses and economic indicators of juvenile tambaqui Colossoma macropomum fed different levels of partial replacement of corn by glycerol (0%, 25%, 50%, 75%, and 100%). The experiment was conducted for 90 days in the production of aquatic organisms lab at the Nilton Lins University, Manaus, Brazil, in a completely randomized design, and consisted of four treatments, four repetitions and two sampling times. In total, 240 juveniles were used with initial average weight and standard length of 15.32 ± 1,61 g and 8.03 ± 0.22 cm, respectively. The fish were maintained in twenty 310 L water tanks that had a closed system with no reuse, continuous aeration, siphoning and replacement of water every 48 h. Feeding was twice a day with the experimental diets, which contained 28% crude protein. The following parameters were considered: zootechnical checks (weight gain + survival %), welfare (health) (hepatosomatic index + condition factor + viscerosomatic index), economic (Economic efficiency rate + economic profitability index) and hematology (hematology + metabolites + ions). The results of the study show that diets for juvenile tambaqui can contain up to 50% replacement of corn by glycerol without compromising the fishes' development under the conditions studied.

Exposure to Lead Nitrate Alters Growth and Haematological Parameters of Milkfish (Chanos chanos)

To date, the effects of lead on the growth and haematological parameters of milkfish are still not well understood. For this reason the present study seeks to explain this conundrum. Sub-adult female milkfish were exposed to four concentrations of lead nitrate (0 mg/l, 42.64 mg/l, 63.97 mg/l and 85.29 mg/l) for 40 days. Results revealed that exposure to lead nitrate caused significant changes in growth and haematological parameters of milkfish. Weight gain, length gain, specific growth rate, feed efficiency, and feed conversion ratio of milkfish declined significantly at the highest concentration treatment. Moreover, lead nitrate exposure significantly decreased the value of red blood cells, hemoglobin, hematocrit, and mean corpuscular hemoglobin concentration, along with a marked increase in mean corpuscular volume and mean corpuscular hemoglobin. Several erythrocyte malformations to cells including swelling, deformation, doubling, binucleus, laceration of the membrane, hemolyzation and vacuolation were all observed.

Antioxidant and antigenotoxic potential of Morinda tinctoria Roxb. leaf extract succeeding cadmium exposure in Asian catfish, Pangasius sutchi

The present study investigated the protective effect of methanolic leaf extract of Morinda tinctoria. Roxb (MEMT) (200 mg/kg) via feed in supplementation with standard compound silymarin (400 mg/kg). M. tinctoria (Roxb.) belonging to Rubiaceae, is an evergreen shrub indigenous to unfarmed lands of tropical countries. It is considered as an essential traditional medicine attributing for the potential antioxidant and anti-inflammatory properties. The enhancements of antioxidant and antigenotoxic status in different tissues of cadmium (Cd) intoxicated Pangasius sutchi were evaluated by using various antioxidant assays (superoxide dismutase (SOD) and catalase (CAT) and lipid peroxidation) in addition to micronuclei (MN), binuclei (BN) and comet assay. The cadmium toxicated fish showed a significant (p < 0.001) increase in lipid peroxidation (LPO) activities in liver, gills, muscle and kidney whereas significant (p < 0.001) decline were observed in superoxide dismutase (SOD) and catalase (CAT) contents in all fish tissues. The results also revealed that, Cd exposure induced the formation of genotoxic endpoints like MN, BN, notched nuclei, kidney shaped nuclei and DNA damage in the fish erythrocytes. Maximum of 26.8% MN frequencies and maximum of 66.74% tail DNA damage were observed on the 7th day of Cd exposure. A time-dependent significant increase (p < 0.001) in the frequencies of MN, BN and tail DNA damage were observed in all treated groups against the control which started to decline from 14th day onwards. There was a decline in the LPO content, frequencies of MN, BN and percentage of tail DNA in contrast to significant elevation in SOD and CAT content in all tissues due to the combined treatment of M. tinctoria feed and water borne Cd exposure. It can be concluded from our observations that, supplementation of M. tinctoria leaf extract through feed alone produced enhanced antioxidant and antigenotoxic status in cadmium treated fish by diminishing oxidative stress and genotoxicity effects in a time dependent manner.

Microplastics-Induced Eryptosis and Poikilocytosis in Early-Juvenile Nile Tilapia (Oreochromis niloticus)

This study aims to assess the impact of microplastics (MPs) on erythrocytes using eryptosis (apoptosis) and an erythron profile (poikilocytosis and nuclear abnormalities), considered to be novel biomarkers in Nile tilapia (Oreochromis niloticus). In this study, four groups of fish were used: The first was the control group. In the second group, 1 mg/L of MPs was introduced to the samples. The third group was exposed to 10 mg/L of MPs. Finally, the fourth group was exposed to 100 mg/L of MPs for 15 days, following 15 days of recovery. The fish treated with MPs experienced an immense rise in the eryptosis percentage, poikilocytosis, and nuclear abnormalities of red blood cells (RBCs) compared with the control group in a concentration-dependent manner. Poikilocytosis of MP-exposed groups included sickle cell shape, schistocyte, elliptocyte, acanthocyte, and other shapes. Nuclear abnormalities of the MPs-exposed groups included micronuclei, binucleated erythrocytes, notched, lobed, blebbed, and hemolyzed nuclei. After the recovery period, a greater percentage of eryptosis, poikilocytotic cells, and nuclear abnormalities in RBCs were still evident in the groups exposed to MPs when crosschecked with the control group. The results show concerning facts regarding the toxicity of MPs in tilapia.

Haematological changes in rabbits (Oryctolagus cuniculus f. domesticus) in the course of pregnancy

The analysis of haematological parameters is an important element of the assessment of the physiological condition of animals. Haematological parameters may change both under the influence of various external factors, and in the course of normal pregnancy, which has been found in various species of mammals, including rabbits. Our study showed statistically significant (p<0.05) changes in basic haematological parameters: RBC (decrease; 5.87±0.48 at day 15 vs. 5.42±0.32 T/L at day 26), MCH (increase; 1.35±0.04 before matching vs. 1.41±0.03 fmol at day 26), RDW (decrease; 15.77±1.80 at day 15 vs. 14.27±1.57% at day 26) MPV (increase; 5.17±0.31 at day 15 vs. 5.92±0.70 fL at day 26), WBC (decrease; 8.60±2.57 at day 15 vs. 4.94±0.88 G/L at day 26) and PLT (decrease; 398.17±91.67 before matching vs. 271.67±61.72 G/L at day 26) in Termond White rabbits and RBC (decrease; 6.18±0.68 before matching vs. 5.68±0.54 T/L at day 26), Hb (decrease; 8.00±0.90 before matching vs. 7.32±0.71 mmol/L at day 26), MCH (decrease; 1.32±0.05 at day 15 vs. 1.29±0.04 fmol at day 26) and WBC (decrease; 9.62±1.81 before matching vs. 5.85±2.23 G/L at day 26 as well as 9.58±2.35 at day 15 vs. 5.85±2.23 G/L at day 26) in Popielno White rabbits. Moreover, in the Popielno White rabbits we recorded a significant (p<0.05) decrease in the percentage of irregular erythrocytes at the end of pregnancy (11.00±10.02 at day 15 vs. 3.00±4.94 at day 26). The changes appear to be physiological but should be considered in studies using rabbits as model organisms.

Physiological and metabolic approach of plastic additive effects: Immune cells responses

Human and wildlife are continually exposed to a wide range of compounds and substances, which reach the body through the air, water, food, or personal care products. Plasticizers are compounds added to plastics and can be released to the environment under certain conditions. Toxicological studies have concluded that plasticizers, phthalates, and bisphenols are endocrine disruptors, alter the endocrine system and functioning of the immune system and metabolic process. A functional immune response indicates favourable living conditions for an organism; conversely, a weak immune response could reveal a degraded environment that requires organisms to adapt. There is growing concern about the presence of plastic debris in the environment. In this review, the current knowledge of the action of plasticizers on leukocyte cells will be itemized. We also point out critically the role of some nuclear and membrane receptors as key players in the action of plasticizers on cells possess immune function. We discuss the role of erythrocytes within the immune responses and the alteration caused by plasticizers. Finally, we highlight data evidencing mitochondrial dysfunctions triggered by plasticizing toxic action, which can lead to immunosuppression.

Toxicity and bioaccumulation of manganese and chromium in different organs of common carp (Cyprinus carpio) fish

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Heavy metals effects fishes when its concentration arises from its normal.

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Bioaccumulation of manganese and chromium was studied in Cyprinus carpio on hematological and biochemical parameters.

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In organ, bioaccumulation is highest in the gills followed by intestine > muscles > skin > bones.

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It is concluded that heavy metal can readily bio accumulate in the organs of fish.

The present research work was carried out to determine the bioaccumulation of manganese and chromium in the gills, intestine, muscles, skin and bones, as well as its acute toxicity and effects on hematological and biochemical parameters in Common carp (Cyprinus carpio). Adult carps were exposed for 96 h to manganese sulphate and chromium chloride solution, a sub lethal concentration was used in the experiment. Bioaccumulation was highest in the gills followed by intestine > muscles > skin > bones. The concentration of hematocrit (HCT) (37.3 ± 0.36), hemoglobin (HGB) (9.0 ± 0.04), Red Blood Cells (RBCs) (3.7 ± 0.025), mean corpuscular volume (MCV) (121.2 ± 0.36), mean corpuscular hemoglobin (MCH) (41.3 ± 0.3) and mean corpuscular hemoglobin concentration (MCHC) (41.06 ± 0.072) was significantly higher at 96 h (P < 0.01) after exposure to manganese and chromium, while the concentration of platelets (PLT) (16.8 ± 0.12) and white blood cells (WBCs) (62.7 ± 0.11) was lower at 96 h of exposure. Serum glutamic pyruvic transaminase (SGPT) (40.6 ± 0.4), Blood Urea (13 ± 0.1), serum triglycerides (231.21 ± 0.04), high-density lipoprotein (HDL) (39 ± 0.07), serum Alkaline PO₄ (242 ± 0.2), lactate dehydrogenase (LDH) (1239 ± 13.21), and serum Uric Acid (4.81 ± 0.33) were significantly higher (P < 0.01) at 96 h of exposure. The highest concentration of serum cholesterol (339 ± 0.09), serum reatinine (0.9 ± 0.01), low density lipid (240 ± 0.2) was observed at 24 h. Serum glutamic-oxaloacetic transaminase (SGOT) (19 ± 0.13), and serum albumin were at the highest level at 72 h (3.19 ± 0.07) (P < 0.01) post exposure.

Micronuclei in Fish Erythrocytes as Genotoxic Biomarkers of Water Pollution: An Overview

Freshwater and marine water bodies receive chemical contaminants from industrial, agricultural, urban, and domestic wastes. Eco-genotoxicity assays are useful tools to assess the cumulative genotoxicity of these pollutants. Fish are suitable indicators for biomonitoring of mutagenic and carcinogenic pollution.In this review, we present a complete overview of the studies performed so far using the micronucleus test in peripheral erythrocytes of fish exposed to polluted water. We have listed all the species of fish used and the geographical distribution of the investigations. We have analyzed and discussed all technical aspects of using this test in fish, as well as the advantages and disadvantages of the different experimental protocols. We have reported the results of all studies. This assay has become, for years, one of the simplest, fastest, and most cost-effective for assessing genotoxic risk in aquatic environments. However, there are still several factors influencing the variability of the results. Therefore, we have given indications and suggestions to achieve a standardization of experimental procedures and ensure uniformity of future investigations.

Combined effects of moderate hypoxia, pesticides and PCBs upon crucian carp fish, Carassius carassius, from a freshwater lake- in situ ecophysiological approach

Nowadays, depletion of oxygen or hypoxia has become a real concerning problem worldwide in freshwater, marine, and estuarine ecosystems and very often co-occurs with xenobiotics. Even though the acute and severe hypoxia is heavily studied in environment and laboratory studies, the in situ combined effects of these stressors on freshwater lake organisms are poorly understood. The current study sought to understand how the combined effects of moderate hypoxia, pesticides and PCBs affect the biochemistry, physiology and organ morphology of Carassius carassius, residing in the Lake Seferani, Dumrea region (Elbasan, Albania), a natural karst freshwater system declared as Nature Monument situated in central Albania. Crucian carp is used as a model organism, because of its residency and ecological relevance to the Lake, as well as for its amenability for the environmental toxicology studies. For this purpose, blood, liver and kidney samples of fish were processed for hematological, biochemical and histopathological analysis. We found a significant increase of blood glucose (GLU), cortisol levels, hematocrit (PCV) and hemoglobin (Hb) which clearly indicate the presence of stress in fish. Based on the histopathological evaluation and organ index results, liver and kidney organs displayed moderate-to-heavy histological-architecture changes. Our results provide a strong evidence that both, hypoxia and the presence of pesticides and PCB congeners found in Seferani Lake, put a heavy load on C. carassius energy metabolism and endocrine system, leading to an elevation of the biochemical and physiological parameters (hemoglobin level, hematocrit, glucose and cortisol), as well as the histopathological alterations. Additionally, in the presence of moderate hypoxia, the toxic effects of pesticides and PCBs on C. carassius are exacerbated. Further studies are needed to evaluate possible effects of pesticide and PCBs toxicity in human health, since crucian carp has an economic value for the population of the zone and it is used often as food sustenance. Elucidation of these kinds of responses can better improve our understanding of response of highly tolerant species, like Carassius carassius, to multiple stressors interactions, helping us to better predict and manage the consequences of the exposure of the freshwater biota to complex stressors in an environment that changes rapidly.

Comparative evaluation of two anticoagulants used for the analysis of haematological, biochemical parameters and blood cell morphology of himalayan snow trout, Schizopyge plagiostomus

The aim of the present study is to evaluate the effect of lithium heparin and K₂EDTA on haematology, biochemical parameters and blood cell morphology of snow trout Schizopyge plagiostomus inhabiting in Kashmir Himalayan region. The haematological parameters such as hemoglobin (Hb), red blood cellcount (RBC), white blood cell (WBC), haematocrit (Hct), erythrocyte indices; mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV), produced certain significant differences in their values with respect to both anticoagulants. Higher values of Hct, MCH and MCV while lower RBC count and MCHC values were recorded with a sample treated with K₂EDTA compared to sample treated with lithium heparin. However, no significant change in Hb and WBC count was observed in the values of samples treated with both the anticoagulants. In the present study, the effect of two anticoagulant in biochemical parameters revealed that the alkaline phosphatase (ALP) and aspartate transaminase (AST) produced significant (P < 0.05) differences. Higher AST and lower ALP activity were recorded in the sample treated with K₂EDTA compared to overall values in serum. Morphometric analysis showed an increase in the RBC perimeter area in samples treated with K₂EDTA as compared to samples treated with lithium heparin. On the basis of above findings, it is recommended that in fish blood analysis heparin as anticoagulant could be useful as compared to K₂ EDTA.