Effect of Chronic Exposure to Textile Wastewater Treatment Plant Effluents on Growth Performance, Oxidative Stress, and Intestinal Microbiota in Adult Zebrafish (Danio rerio)

Zebrafish: A trending model for gut-brain axis investigation

Zebrafish (Danio rerio) has ascended as a pivotal model organism in the realm of gut-brain axis research, principally owing to its high-throughput experimental capabilities and evolutionary alignment with mammals. The inherent transparency of zebrafish embryos facilitates unprecedented real-time imaging, affording unparalleled insights into the intricate dynamics of bidirectional communication between the gut and the brain. Noteworthy are the structural and functional parallels shared between the zebrafish and mammalian gut-brain axis components, rendering zebrafish an invaluable model for probing the molecular and cellular intricacies inherent in this critical physiological interaction. Recent investigations in zebrafish have systematically explored the impact of gut microbiota on neurodevelopment, behaviour, and disease susceptibility, underscoring the model's prowess in unravelling the multifaceted influence of microbial communities in shaping gut-brain interactions. Leveraging the genetic manipulability inherent in zebrafish, researchers have embarked on targeted explorations of specific pathways and molecular mechanisms, providing nuanced insights into the fundamental functioning of the gut-brain axis. This comprehensive review synthesizes pivotal findings and methodological advancements derived from zebrafish-based gut-brain axis research, accentuating the model's potential to significantly advance our understanding of this complex interplay. Furthermore, it underscores the translational significance of these insights, offering promising avenues for the identification of therapeutic targets in neuro-gastroenterological disorders and psychiatric conditions intricately linked with gut-brain interactions.

Hues of risk: investigating genotoxicity and environmental impacts of azo textile dyes

The textile industry, with its extensive use of dyes and chemicals, stands out as a significant source of water pollution. Exposure to certain textile dyes, such as azo dyes and their breakdown products like aromatic amines, has been associated with health concerns like skin sensitization, allergic reactions, and even cancer in humans. Annually, the worldwide production of synthetic dyes approximates 7 × 107 tons, of which the textile industry accounts for over 10,000 tons. Inefficient dyeing procedures result in the discharge of 15-50% of azo dyes, which do not adequately bind to fibers, into wastewater. This review delves into the genotoxic impact of azo dyes, prevalent in the textile industry, on aquatic ecosystems and human health. Examining different families of textile dye which contain azo group in their structure such as Sudan I and Sudan III Sudan IV, Basic Red 51, Basic Violet 14, Disperse Yellow 7, Congo Red, Acid Red 26, and Acid Blue 113 reveals their carcinogenic potential, which may affect both industrial workers and aquatic life. Genotoxic and carcinogenic characteristics, chromosomal abnormalities, induced physiological and neurobehavioral changes, and disruptions to spermatogenesis are evident, underscoring the harmful effects of these dyes. The review calls for comprehensive investigations into the toxic profile of azo dyes, providing essential insights to safeguard the aquatic ecosystem and human well-being. The importance of effective effluent treatment systems is underscored to mitigate adverse impacts on agricultural lands, water resources, and the environment, particularly in regions heavily reliant on wastewater irrigation for food production.

Heavy metal toxicity arising from the industrial effluents repercussions on oxidative stress, liver enzymes and antioxidant activity in brain homogenates of Oreochromis niloticus

Industrial effluents reaching to the aquatic ecosystem is one of the major causes of environmental pollution and exposure to industrial effluents containing harmful substances may be a serious threat to human health. Therefore, the present study aimed to determine the sub-lethal (1/5th of predetermined LC50) impact of industrial effluents from Sundar Industrial Estate on Oreochromis niloticus with proper negative control. The physicochemical analysis of industrial effluents showed enormous loads of inorganic pollutants and exhibited high mean levels of heavy metals, Mn, Fe, Pb, Ni, Cr, Hg, As, Zn and Fe with statistically significant differences at p < 0.05. Highest level of Mn and Fe was detected in effluent's samples as 147.36 ± 80.91 mg/L and 90.52 ± 32.08 mg/L, respectively. Exposure led to increase in serum biochemical parameters alanine aminotransferase + 25%, aspartate aminotransferase + 20% and alkaline phosphatase + 7% over control although superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione significantly increased as 3.42, 2.44, 4.8 and 8 folds, respectively in metabolically active tissue brain which indicated stress caused by industrial effluents. The results concluded that industrial effluent has potent oxidative stress inducers on one hand whereas histoarchitectural and physiological toxicity causing contaminants on the other. This condition may adversely affect the health of aquatic organisms, the fish and ultimately the human beings.

Protective effects of sulforaphane on inflammation, oxidative stress and intestinal dysbacteriosis induced by triphenyltin in Cyprinus carpio haematopterus

The purpose of this experiment was to study the mitigation effect of sulforaphane (SFN) on fish toxicological damage caused by triphenyltin (TPT) pollution. A total of 320 healthy fish (56.9 ± 0.4g) were randomly placed into four groups, each with four duplicates. The control group was fed the basal diet, the TPT group was exposed to 10 ng/L TPT on the basis of the control group, the SFN group was fed a diet supplemented with 10 mg/kg SFN, the SFN + TPT group was exposed to 10 ng/L TPT on the basis of the SFN group. Each tank had 20 fish and the breeding lasted for 8 weeks. The present study found that the antioxidant enzyme activity in the TPT group was significantly lower than that of the control group (P < 0.05). In addition, compared with the control group, the mRNA expression of pro-inflammatory factors (IL-6, TNF-α) were significantly induced, and the anti-inflammatory factor genes (IL-10, TGF) were significantly inhibited (P < 0.05) in TPT group. SFN relieved the changes of inflammatory factors caused by TPT, ameliorated oxidative stress, improved antioxidant enzyme (include SOD, CAT, GSH, GPx) activities (P < 0.05). 16s RNA analysis indicated that exposure to TPT caused changes in intestinal microflora. The results of the study showed that after exposure to TPT, some beneficial genera of bacteria in the gut of Rhizobiaceae, Bdellovibrio and Candidatus Alysiosphaera were decreased. The bacteria associated with intestinal inflammation including Propionibacterium, Rubrobacter, Anaerorhabdus_furcosa_group, Rikenellaceae and Eubacterium_brachy were upregulated. However, the SFN treatment group significantly down-regulated the above five inflammation-related bacteria. The above results indicated that TPT caused oxidative stress and inflammation in fish intestines, changed the intestinal microflora, and dietary SFN could improve antioxidant status, regulate inflammation and intestinal health. Therefore, SFN is a promising diet additive for improving fish damage caused by TPT contamination.

Transgenic zebrafish (Danio rerio) as an emerging model system in ecotoxicology and toxicology: Historical review, recent advances, and trends

Zebrafish (Danio rerio) is an alternative model system for drug screening, developing new products, and assessing ecotoxic effects of pollutants and biomonitor species in environmental risk assessment. However, the history and current use of transgenic zebrafish lines in ecotoxicology and toxicology studies remain poorly explored. Thus, the present study aimed to summarize and discuss the existing data in the literature about the applications of transgenic zebrafish lines in ecotoxicology and toxicology. The articles were analyzed according to publication year, journal, geographic distribution, and collaborations. Also, the bioassays were evaluated according to the tested chemical, transgenic lines, development stage, biomarkers, and exposure conditions (i.e., concentration, time, type, and route of exposure). Revised data showed that constitutive transgenic lines are the main type of transgenic used in the studies, besides most of uses embryos and larvae under static conditions. Tg(fli1: EGFP) was the main transgenic line, while the GFP and EGFP were the main reporter proteins. Transgenic zebrafish stands out in assessing vasotoxicity, neurotoxicity, systemic toxicity, hepatoxicity, endocrine disruption, cardiotoxicity, immunotoxicity, hematotoxicity, ototoxicity, and pancreotoxicity. This review showed that transgenic zebrafish lines are emerging as a suitable in vivo model system for assessing the mechanism of action and toxicity of chemicals and new biotechnology products, and the effects of traditional and emerging pollutants.