STUDIES OF MICRONUCLEI AND OTHER NUCLEAR ABNORMALITIES IN BLOOD OF RAINBOW TROUT (ONCORHYNCHUS MYKISS) TREATED WITH HEAVY METAL MIXTURE AND ROAD MAINTENANCE SALTS

Hyaluronic acid impacts hematological endpoints and spleen histological features in African catfish (Clarias gariepinus)

Since its identification in the vitreous humour of the eye and laboratory biosynthesis, hyaluronic acid (HA) has been a vital component in several pharmaceutical, nutritional, medicinal, and cosmetic uses. However, little is known about its potential toxicological impacts on aquatic inhabitants. Herein, we investigated the hematological response of Clarias gariepinus to nominal doses of HA. To achieve this objective, 72 adult fish were randomly and evenly distributed into four groups: control, low-dose (0.5 mg/l HA), medium-dose (10 mg/l HA), and high-dose (100 mg/l HA) groups for two weeks each during both the exposure and recovery periods. The findings confirmed presence of anemia, neutrophilia, leucopoenia, lymphopenia, and eosinophilia at the end of exposure to HA. In addition, poikilocytosis and a variety of cytomorphological disturbances were observed. Dose-dependent histological alterations in spleen morphology were observed in the exposed groups. After HA removal from the aquarium for 2 weeks, the groups exposed to the two highest doses still exhibited a notable decline in red blood cell count, hemoglobin concentration, mean corpuscular hemoglobin concentration, and an increase in mean corpuscular volume. Additionally, there was a significant rise in neutrophils, eosinophils, cell alterations, and nuclear abnormalities percentages, along with a decrease in monocytes, coupled with a dose-dependent decrease in lymphocytes. Furthermore, only the highest dose of HA in the recovered groups continued to cause a significant increase in white blood cells. White blood cells remained lower, and the proportion of apoptotic RBCs remained higher in the high-dose group. The persistence of most of the haematological and histological disorders even after recovery period indicates a failure of physiological compensatory mechanisms to overcome the HA-associated problems or insufficient duration of recovery. Thus, these findings encourage the inclusion of this new hazardous agent in the biomonitoring program and provide a specific pattern of hematological profile in HA-challenged fish. Further experiments are highly warranted to explore other toxicological hazards of HA using dose/time window protocols.

Genotoxicity, oxidative stress and lysozyme induction in Clarias gariepinus chronically exposed to water-soluble fraction of burnt tire ash

The safety of aquatic ecosystems has been compromised by numerous anthropogenic activities, especially leachates from non-point source toxicants, leaching into aquatic systems. This study evaluated the toxicity of the water-soluble fractions (WSFs) of burnt tire ash (BTA) on Clarias gariepinus via a battery of integrated biomarkers. Juvenile C. gariepinus were exposed to sublethal (0.56, 1.12, and 2.24 g/L) concentrations of BTA, derived from 11.2 g/L median lethal concentration (96 LC₅₀), at duration intervals of 1, 14, and 28 days, followed by a recovery trial that lasted for 14 days. Serum biochemical parameters, antioxidant enzyme activities of the gill and liver, lysozymes activity and erythron profile were assessed. The findings of the present study revealed that BTA-WSF induced prominent alterations on biochemical parameters, lysozymes activity and antioxidant enzymes activities in the exposed fish. Furthermore, toxicant exposure promoted oxidative stress, cellular damage and genotoxicity (erythrocytic nuclear and cellular abnormalities) in the exposed fish. In general, a post-exposure trial showed partial recovery from the exposure effects of the toxicant, following the evident modifications of serum enzymes and erythron pathopathology in the experimental model. Biomonitoring of BTA, using sentinel aquatic species such as C. gariepinus, provides insights into the ecotoxicological potency of this toxicant.

Chromium Exposure Causes Structural Aberrations of Erythrocytes, Gills, Liver, Kidney, and Genetic Damage in Striped Catfish Pangasianodon hypophthalmus

Heavy metal pollution due to anthropogenic activities poses a great threat to aquatic organisms. The present study was conducted to evaluate the cytotoxic and genotoxic effects of hexavalent chromium (potassium dichromate) on hemato-biochemical, histo-pathological, and genetical changes in striped catfish Pangasianodon hypophthalmus. Three sub-lethal doses (0.8, 1.6, and 3.2 mg/L) of chromium (Cr) were selected and fish were exposed in vivo contrasting with a control (0 mg/L) for 30 days. The study revealed that various hemato-biochemical parameters showed a significant decrease in hemoglobin (Hb), red blood cells (RBCs), and blood glucose content, whereas white blood cells (WBCs) significantly increased in Cr exposed fish. Frequencies of all forms of structural abnormalities of erythrocytes (erythrocytic cellular abnormalities; ECA, erythrocytic nuclear abnormalities; ENA and erythroblasts; Ebs) were significantly increased in higher two test concentrations (1.6 and 3.2 mg/L) when compared to control. Differential leucocyte count exhibited significant increase in neutrophil and decrease in lymphocytes in the highest Cr treated group. The severity of various histo-pathological changes in the gills, liver, and kidney were increased considerably with the increase of Cr concentrations. Similarly, the amount of DNA (ng/μl) decreased significantly in blood and tissues of different vital organs where the liver showed the highest decline compared to control in a concentration-dependent manner. Taken altogether, P. hypophthalmus is susceptible to Cr and can be used as a bio-indicator to assess aquatic metal pollution.

Effects of nanosilver on hematologic, histologic and molecular parameters of rainbow trout (Oncorhynchus mykiss)

Efficient antibacterial and antifungal properties of silver nanoparticles (AgNPs) sparked its commercial application in several industrial and household products. Drastic increase of AgNPs production raised concerns over aquatic organisms' exposure. The toxic dose, mechanism of toxicity, physiological damages, gene expression alteration, hematological and blood parameter distortion by AgNP needs to be investigated to explore inevitable risk in aquatic animals. In this study, rainbow trout (Oncorhynchus mykiss) (122.4 ± 1.4 g, 23.8 ± 0.7 cm) were exposed to colloidal AgNPs (28.3 ± 12.6 um) to determine the lethal concentration (LC50)(8.9 mg/l). Sub-lethal concentrations (10 %LC50, 25 %LC50, plus LC50 value) impact on hematologic, histological and molecular responses were evaluated. Results showed sever damage to blood cells morphology, and hematologic parameters change including RBC, WBC, Hct and Hb in all AgNP-treated groups. Histological damage in gill and liver of exposed fish were observed. Significant up-regulating of HSP70 and P53 genes were detected in response to AgNPs, whereas, it was found that in comparison to HSP70 gene, P53 induction occurred in lower AgNPs concentrations and lower exposure time. These results indicate adversely effects of AgNPs exposure to aquatic environments.

Evaluation of genotoxic potential throughout the upper and middle stretches of Adige river basin

In this study a comprehensive genotoxicological survey throughout the upper and middle stretches of Adige river basin is presented. The study was carried out at 7 sites located along the Adige main course and one the most significant tributaries, the Noce creek, both presenting different levels of pollution pressure. To give an insight into the nature of the genotoxic activity we employed the battery of prokaryotic and eukaryotic assays. Mutagenicity in water samples was evaluated by SOS/umuC test in Salmonella typhimurium TA1535/pSK1002. The level of DNA damage as a biomarker of exposure (comet assay) and biomarker of effect (micronucleus assay) and the level of oxidative stress as well (Fpg - modified comet assay) were studied in blood cells of Salmo cenerinus Nardo, 1847 and Salmo marmoratus Cuvier, 1829. Within the applied bioassays, comet assay showed the highest potential for discriminating the sampling sites which are under lesser extent of pressure (sampling sites 1-Barnes at Bresimo and 4-Noce downstream S. Giustina) from the sites under high pressure (sampling sites 5-Noce at Mezzolombardo and 6/7-Adige upstream and downstream municipality of Trento). Significant correlation between the standard and Fpg - modified comet assay indicated that oxidative stress could be a major contributor to observed DNA damage in collected specimens.

Microscopy and microanalysis of hematological parameters in common carp, Cyprinus carpio, inhabiting a polluted lake in North East India

Optical and scanning electron microscopy (SEM) of red blood cells (RBCs) of common carp, Cyprinus carpio, inhabiting a polluted lake in Northeast India revealed a number of abnormalities. About 7% of the RBC showed the presence of a micronucleus, besides the presence of some bi-nucleated and abnormally shaped nuclei. RBCs, white blood cells, and hemoglobin content were found to be reduced significantly as compared to the control. SEM showed the presence of spherocytes, early stages of echinocytes, cytoplasmic blebbing, erythrocytes with contraction from one side, abnormal shape of erythrocytes (hexagonal/pentagonal/tetragonal), development of lobopodial projections, cell rupture, membrane internalization, and formation of ring-shaped RBC. Energy dispersive X-ray spectroscopy (EDS) showed the presence of a considerable percentage of silicon and lead in erythrocytes of the fish collected from the polluted lake, in contrast to a negligible concentration of the two elements in control fish. Significance of the study in relation to fish health in a polluted body of water and the importance of SEM, EDS, and light microscopy in utilizing hematological parameters as pollution indicators are discussed.

Micronuclei and other nuclear abnormalities in mussels (Mytilus galloprovincialis) as biomarkers of cyto-genotoxic pollution in mediterranean waters

Environmental genotoxicity and cytotoxicity along the Spanish Mediterranean coast was investigated through the determination of levels of micronuclei (MN) and other nuclear abnormalities (NAs) such as nuclear buds (NB) and binucleated cells (BN) in gills of wild mussels, Mytilus galloprovincialis, from 17 study sites. The results obtained were studied in relation to the exposure to main pollutants (metals, PAHs, PCBs and DDTs), gill antioxidant enzyme activities and environmental variables (temperature and salinity). The highest MN and NB levels were found in mussels from metal-polluted sites, such as Cartagena (MN: 11.6‰, NB: 4.6‰) and Portman (MN: 8.0‰, NB: 3.5‰), where genotoxicity seemed to be related to the oxidative stress generated by exposure to metals. High frequencies of MN and NB in mussels from Algeciras 1 (MN: 8.6‰, NB: 4‰) and of MN (7.2‰) in mussels from Manilva also indicated genotoxicity, though not attributable to the pollutants analysed. In contrast, MN levels at sites highly polluted by organic contaminants such as Barcelona, Vallcarca, Tarragona and Valencia, were lower than expected (ranging from 3.8 to 5.8‰). On the other hand, evidences of cytotoxicity indicated by the high frequencies of BN found in mussels from Vallcarca, Barcelona, and Cartagena (3.9, 3.4, and 2.3‰, respectively) appeared to be specifically related to the accumulation of organic pollutants. Positive correlations found between MN and NB frequencies, and also between both NAs and water temperature, suggested that they were related genotoxic events, and that this environmental factor is able to influence their levels and has to be taken into account in the application of these biomarkers in field studies.