Alterations in the skin of Labeo rohita exposed to an azo dye, Eriochrome black T: a histopathological and enzyme biochemical investigation

Alteration in oxidative stress markers, digestive physiology and gut microbiota of Heteropneustes fossilis and Clarias batrachus exposed to eriochrome black T

Synthetic dyes are the primary cause of water pollution in industrial regions. Azo dyes account for 60-70% of such dyes used in the textile sector due to their numerous beneficial characteristics. Nevertheless, there is a dearth of knowledge regarding the toxicity of Eriochrome Black T (EBT), a widely used azo dye in the textile industry. Therefore, the current study was designed to investigate the effect of EBT exposure on two catfish species, Heteropneustes fossilis and Clarias batrachus. Following 96 h exposure to 1, 10 and 20 mgL-1 of EBT, the MDA content and activities of SOD, CAT and GR exhibited a rising trend. However, as the concentration of EBT increased in both species, GPx showed decreased activity. EBT exposure also altered gut morphometry as well as the three main digestive enzymes activity (increase in lipase and trypsin activity, while decrease in amylase activity). In addition, the exposure of EBT had a significant impact on the gut microbiota of both species. C. batrachus demonstrated the suppression or absence of beneficial gut commensals (Bacillus and Cetobacterium), whereas H. fossilis revealed the proliferation and appearance of beneficial commensal microbes (Bacillus, Bacteroides, Prevotella, and Megashaera). Furthermore, the expansion or absence of these microbial communities indicated that the gut microbiota of both species was involved in dye digestion, immunity and detoxification. Overall, the percent change calculation of all the selected biomarkers, together with gut microbiota analysis, indicates that C. batrachus was more vulnerable to EBT exposure than H. fossilis. The present investigation effectively demonstrated the toxic impact of EBT on fish health by employing oxidative stress markers, digestive enzymes, and the fish gut microbiota as a promising tool for screening the impact of dye exposure on digestive physiology in toxicological research.

Alterations in certain immunological parameters in the skin mucus of the carp, Cirrhinus mrigala, infected with the bacteria, Edwardsiella tarda

The bacterial fish pathogen Edwardsiella tarda causes heavy stock mortality, severely hampering fish production, resulting in great economic loss to the farming industry. The first biological barriers that confer immune protection against pathogen entry are the fish mucosal surfaces. The present study was undertaken to investigate the influence of E. tarda on certain enzymatic and non-enzymatic parameters in the skin mucous secretions of the fish Cirrhinus mrigala using spectrophotometry and zymography. Fish were randomly divided into three groups: control, vehicle control, and infected. A sublethal dose of E. tarda (2.2 × 106 CFU/fish) suspended in 50 μL of PBS was injected intra-peritoneally at 0 day (d). Subsequently, mucus samples were collected at 2 d, 4 d, 6 d and 8 d post-infection. The activities of lysozyme (LYZ), protease (PROT), alkaline phosphatase (ALP), acid phosphatase (ACP), catalase (CAT), peroxidase (PER), superoxide dismutase (SOD), and glutathione S-transferase (GST) decreased significantly in the skin mucus of the challenged fish, indicating the suppressed immune system and decreased antioxidant capacity of C. mrigala to E. tarda infection. Lipid peroxidation (LPO) and total nitrate-nitrite were significantly higher at several time points post-infection, suggesting that physiological functions have been impaired following pathogen challenge. The present findings could be relevant for fish aquaculture and underline the importance of skin mucus not only for assessing fish immune status but also for identifying early warning signals of disease caused by pathogens.

Effects of ELF-PEMF exposure on spontaneous alternation, anxiety, motor co-ordination and locomotor activity of adult wistar rats and viability of C6 (Glial) cells in culture

The effects of ELF-PEMF exposure on spontaneous alternation, anxiety, motor coordination, and locomotor activity have been discussed in various pre-clinical and clinical settings. Several epidemiological and experimental studies have demonstrated the potential effects of ELF-PEMF when exposed > ∼1 h/day; however, very few studies have focused on understanding the influence of ELF-PEMF exposure of 1-3 mT with an exposure duration of < 1 h/day on spontaneous alternation, anxiety, motor coordination, and locomotor activity. Hence, we attempted to study the effects of ELF-PEMF exposure of 1-3 mT, 50 Hz with an exposure duration of 20 min each with a 4 h gap (2 times) on the cellular proliferation and morphologies of C6 (Glial) cells and spontaneous alternation, anxiety, motor coordination and locomotor activity of Wistar rats under in vitro and in vivo conditions, respectively. The results showed that ELF-PEMF exposure did not induce any significant levels of cellular fragmentation and changes in the morphology of glial cells. Also, the outcomes revealed no noticeable effects on spontaneous alternation, anxiety, motor coordination, and locomotor activity in PEMF-exposed groups compared with the control. No undesirable side effects were observed at the highest dose (B=3 mT). We also performed histological analysis of the selected brain sections (hippocampus and cortex) following ELF-PEMF exposure. Incidentally, no significant changes were observed in cortical cell counts, tissue structure, and morphology.

Transformation of used aluminium foil food container into AlOOH nanoflakes with high catalytic activity in anionic azo dye reduction

Synthesis of aluminium-based nanomaterials from aluminium-waste has received huge attention in current scientific research. Herein, an attempt was made to convert aluminium foil food container into aluminium oxyhydroxide (AlOOH) nanoparticles by a precipitation method. X-ray diffraction (XRD), spectroscopic and electron microscopic studies were employed to characterize impure AlOOH (containing sodium chloride, NaCl) and pure AlOOH samples. The band gap (E_g) of AlOOH nanoparticles was found to be 4.5 eV. The catalytic potential of AlOOH samples was evaluated using reduction of methyl orange (MO) and Eriochrome black T (EBT) dyes. Impure AlOOH nanoparticles could reduce 99.8% of MO and EBT dye within 4 min and 3 min respectively. Effect of the AlOOH dosage and NaBH₄ concentration on catalytic reduction was determined. Used aluminium foil food container-derived AlOOH nanoparticles will become a low-cost and sustainable catalyst in the catalytic treatment of azo dye contaminated waters.

In-vitro toxicity assessment of a textile dye Eriochrome Black T and its nano-photocatalytic degradation through an innovative approach using Mf-NGr-CNTs-SnO2 heterostructures

The present study aimed to assess the in-vitro toxicity of a popular azodye, Eriochrome Black T (EBT) which may be an environmental hazard causing water pollution if released by textile industries as waste effluents to nearby water ponds. We explored the toxic potential of EBT at 200, 400 and 800 μg/ml concentrations, which were selected based on quantification of EBT present in the pond water near carpet industries. We investigated the permeability of EBT across the organ barriers and found it to be 6.48 ± 0.44% at the highest concentration. EBT also showed up to 26.46 ± 0.533% hemolytic potential on human RBCs. MTT assay revealed toxicity of up to 64.9 ± 10.12%. A dose-dependent increase in intracellular ROS levels and Caspase 3/7 activity was observed and confocal microscopy also demonstrated a similar trend of cellular apoptosis indicating ROS mediated induction of apoptosis as a mechanism of EBT induced cytotoxicity. After establishing the toxicity of EBT, an innovative nano-photocatalytic approach for dye remediation was applied by using as synthesized Mf-NGr-CNTs-SnO₂ heterostructures. This catalyst showed dye degradation potential of up to 82% in 2 h in the presence of sun light. The degraded dye products were tested to have up to 30% reduced cellular toxicity as compared to the parent compound. This work successfully establishes the toxicity of EBT along with devising an innovative approach towards dye degradation where the catalyst is adhered on melamine foam and not being mixed in the effluents directly, thereby, reducing the possibility of catalyst being leached out into the river water.

Analyses of the health status, risk assessment and recovery response of the nutritionally important catfish Clarias batrachus reared in coal mine effluent-fed pond water: a biochemical, haematological and histopathological investigation

The present field study evaluates the health status of the catfish Clarias batrachus reared in coal mine effluent (CME)-fed pond water at Rajrappa mining complex using biochemical, haematological and histopathological parameters. Simultaneously, risk assessment along with recovery response of the CME intoxicated fish following their treatment with CME-free freshwater was also studied. The CME-fed pond water fish revealed significant decrease in biomolecules concentrations and considerable increase in activities of several enzymes along with metallothionein level as compared to control. The impaired regulation of metabolic function was also revealed by blood parameters showing significant decrease in haemoglobin content (8.78 ± 0.344 g/100 mL) and red blood cells count (1.77 ± 0.12 × 106 mm3) while substantial elevation in white blood cells (187.13 ± 9.78 × 103 mm3). The histopathological study also confirmed the changes including hypertrophy of club cells of skin, swelling of secondary lamella of gills, extensive fibrosis in liver and glomerular shrinkage with increased Bowman's space in kidney. Potential health risk assessments based on estimated daily intake and target hazard quotient indicated health risks associated with the consumption of such fishes. The CME-contaminated fish when transferred to CME-free freshwater exhibited decreased metal content accompanied by eventual recovery response as evident by retrieval in biochemical and haematological parameters. Withdrawal study also revealed restoration in the activity of different marker enzymes in fish tissues including blood as well as recovery in their cellular architecture. The results of the present study validate the depuration process as an effective practice for detoxification of fish contaminated with effluent.

Neuroprotective effects of quercetin produced by an endophytic fungus Nigrospora oryzae isolated from Tinospora cordifolia

AIMS

Alzheimer's disease is considered one of the most prevalent neurodegenerative disorders and dementia is the core symptom of this disease. This study was aimed to test the bioactive compounds produced by endophytic fungus for the inhibition of acetylcholinesterase (AChE) activity and to identify the compound responsible for this activity.

METHODS AND RESULTS

Endophytic fungi were isolated from the medicinal plant Tinospora cordifolia and screened for AChE inhibition and antioxidant activity. The extract of one of the isolates Nigrospora oryzae (GL15) showed maximum AChE inhibition as well as antioxidant activity. The compound responsible for AChE inhibition (fraction 3) was identified as quercetin based on UV, FTIR spectra, HPLC and ESI-MS analyses. Furthermore, the identification of quercetin in the extract of fraction 3 was confirmed by ¹ H NMR analysis. This extract showed anti-dementia-like activity in scopolamine (SCO) model. The minimal effective dose of the extract of fraction 3 modulated the SCO-provoked cognitive deficits such as impairments in spatial recognition memory and latency period in Y-maze test and passive avoidance test, respectively. The SCO-induced modulation in cholinergic pathway was ameliorated by the extract of N. oryzae in hippocampus, resulting in decrease in AChE activity and restoration of cytoarchitecture of hippocampus.

CONCLUSIONS

The bioactive compound quercetin produced by N. oryzae may cure the learning and memory shortfalls via AChE-mediated mechanism in experimental mice.

SIGNIFICANCE AND IMPACT OF THE STUDY

The endophytic fungus N. oryzae serves as a potential source for the bioactive compound quercetin, which plays an important role in the management of Alzheimer's disease.

Genetic and biochemical changes in liver and kidney of Channa punctatus after treatment with 2-naphthalene sulfonate

2-Naphthalene sulfonate (2NS) is a sulfonated aromatic compound and a momentous intermediate involved in the synthesis of dyes and surfactants. Thus, the present experiment was undertaken to evaluate the variation in biochemical constituents in liver and kidney of fresh water fish, Channa punctatus, after 2NS intoxication. After determination of lethal dose (LD) two sublethal doses, i.e. 0.33 mg/15 g body weight (one-half of LD₅₀) and 0.16 mg/15 g b.w. (one-fourth of LD₅₀) were selected for analyzing oxidative stress, genotoxicity and bioaccumulative potential of 2NS. Highest significant increase in oxidative stress and DNA damage in the exposed groups as compared with control group (P ≤ 0.05) was observed at 96 h. However, decreased values of all the studied parameters after 30 days indicate repair capacity of fish. In order to study the alterations observed in biomolecules including lipids, proteins and nucleic acids, histopathology along with spectroscopic analysis using attenuated total reflection-Fourier transform infrared was also performed for 96 h exposed group. In addition, protein secondary structure analysis was focused in this study, which reveals alterations in α-helix and β-sheet structure after 2NS intoxication. Furthermore, the bioaccumulative potential of 2NS was revealed using high-performance liquid chromatography showing 1.83 and 45.54 μg/ml concentration of 2NS in liver and kidney homogenate, respectively. As the study revealed 2NS as the potential health hazard to aquatic organisms, it entails the augmentation and adoption of pertinent policies regarding the management of such toxic compounds.

Epidermal Club Cells in Fishes: A Case for Ecoimmunological Analysis

Epidermal club cells (ECCs), along with mucus cells, are present in the skin of many fishes, particularly in the well-studied Ostariophysan family Cyprinidae. Most ECC-associated literature has focused on the potential role of ECCs as a component of chemical alarm cues released passively when a predator damages the skin of its prey, alerting nearby prey to the presence of an active predator. Because this warning system is maintained by receiver-side selection (senders are eaten), there is want of a mechanism to confer fitness benefits to the individual that invests in ECCs to explain their evolutionary origin and maintenance in this speciose group of fishes. In an attempt to understand the fitness benefits that accrue from investment in ECCs, we reviewed the phylogenetic distribution of ECCs and their histochemical properties. ECCs are found in various forms in all teleost superorders and in the chondrostei inferring either early or multiple independent origins over evolutionary time. We noted that ECCs respond to several environmental stressors/immunomodulators including parasites and pathogens, are suppressed by immunomodulators such as testosterone and cortisol, and their density covaries with food ration, demonstrating a dynamic metabolic cost to maintaining these cells. ECC density varies widely among and within fish populations, suggesting that ECCs may be a convenient tool with which to assay ecoimmunological tradeoffs between immune stress and foraging activity, reproductive state, and predator-prey interactions. Here, we review the case for ECC immune function, immune functions in fishes generally, and encourage future work describing the precise role of ECCs in the immune system and life history evolution in fishes.

Alterations in the epidermis of the carp, Labeo rohita (Cyprinidae: Cypriniformes), infected by the bacteria, Aeromonas hydrophila: A scanning electron microscopic, histopathological and immunohistochemical investigation

This study was carried out to comprehend the pathogenicity of the bacteria in the epidermis of Labeo rohita inoculated with Aeromonas hydrophila. Alterations in the histopathology of the epidermis were examined using scanning electron microscopy, light microscopy and the localization of iNOS and caspase 3 + ve cells by means of immunohistochemical methods. Skin samples obtained from infected fish at different intervals 2, 4, 6, 8 and 10 days showed significant changes in the cellular components of the epidermis. Epithelial cells often appeared hypertrophied with fragmented and loosely arranged microridges, and in the process of exfoliation. Mucous goblet cells increased significantly in density. Club cells showed degenerative changes, often with simultaneous confluence of adjacent cells and release of their contents. Increase in density of iNOS and caspase 3 + ve cells indicates inflammatory response and apoptosis. This study could provide valuable information on the pathogenesis of the disease, and disease outbreaks in farmed fish. Further, it could provide useful guidelines for fish farmers to take preventive measures for the control of the disease.