Toxicological evaluation of TBBPA by common carp (Cyprinus carpio) about the in vivo/vitro disturbance of the AHR pathway

Prediction and mechanism of combined toxicity of surfactants and antibiotics in aquatic environment based on in silico method

The coexistence of surfactants and antibiotics in aquatic environments can potentially trigger combined toxic effects on aquatic organisms. Unfortunately, the effects of these joint toxins and the corresponding mechanism remain unclear. In this study, we performed individual and combined toxicity experiments involving surfactants and antibiotics. Six quantitative structure-activity relationship (QSAR) models and two traditional mixture models were developed. Moreover, the toxic mechanisms were explored with molecular dynamics (MD) simulations and density functional theory (DFT) calculations. The results shown that synergistic toxicity effects were observed in the binary mixture of levofloxacin (LEV) and octylphenol ethoxylate (Triton X-100). In addition, the best QSAR model (RF-PLS), which included four mixture descriptors (RDF155i#3, MATS3e#2, ETA_BetaP_ns#6, MLFER_E#6) exhibited excellent performance (R2 = 0.921, R2adj = 0.875, Q2LOO = 0.820, Q2ext = 0.889, and CCC = 0.954). Further analysis revealed that the electrostatic potential of different target chemicals and their binding ability with enzymes affected the activity of AChE of Daphnia magna, resulting in different toxicity. Specifically, in the AChE + Triton X-100 + LEV system, the second pollutant enhances the ability of the overall system to bind pollutants, which exhibit a synergistic effect during the binding process.

Macrostomum lignano Complements the Portfolio of Simple Animal Models Used for Marine Toxicological Studies

Macrostomum lignano is gaining increasing recognition as a model organism for toxicological studies in marine ecosystems and expands the range of simple animal models currently used. Water pollution caused by human activities not only endangers environmental integrity but also affects human health, underlining the need to monitor water pollution effectively. This review describes the distinctive characteristics of M. lignano, including its rapid reproductive cycle, increased sensitivity to environmental variability, and remarkable regenerative abilities. Over the last thirty years, M. lignano has been used in various research areas, particularly molecular biology and toxicology. This endeavor has benefited from significant advances in genome and transcriptome technologies. Recent investigations have revealed its sensitivity to various pollutants and highlighted its potential for assessing toxicological effects at the physiological and molecular levels. Furthermore, the ecological versatility and stable microbiome of M. lignano make it an exemplary model for research into pollutant interactions in marine ecosystems. Despite challenges associated with its complex genomic architecture, ongoing genomic efforts are promising to significantly enhance its utility in toxicological research. This review underscores the pivotal role of M. lignano in advancing environmental health studies and outlines future research directions to maximize its potential as a model organism.

Molecular mechanisms of tetrabromobisphenol A (TBBPA) toxicity: Insights from various biological systems

Tetrabromobisphenol A (TBBPA) is a ubiquitous brominated flame retardant extensively incorporated into a wide range of products. As its utilization has escalated, its environmental exposure risks have concomitantly increased. The molecular properties of TBBPA allow it to persist in the environment and within organisms. In this review, we comprehensively examine the toxicity of TBBPA across different organ systems and elucidate the underlying molecular mechanisms. We particularly emphasize TBBPA's impact on biological signaling pathways, protein functionality, cellular architecture, and epigenetic regulation, which collectively lead to disruptions in endocrine, hepatic, neurological, reproductive, and other biological systems. The analysis of these toxicological phenomena and their fundamental molecular mechanisms has substantially enhanced our understanding of TBBPA's hazardous characteristics. This review also examines potential avenues for future research, with a focus on uncovering novel molecular mechanisms and assessing the toxicological impacts of TBBPA exposure, particularly in relation to interactions with other environmental contaminants. We propose a greater focus on examining the toxic effects and molecular mechanisms of long-term TBBPA exposure at environmentally relevant concentrations to facilitate more accurate assessments of human health risks.

Characterization of medaka (Oryzias latipes) AHRs and the comparison of two model fishes-Medaka vs. zebrafish: The subform-specific sensitivity to dioxin

Dioxins and the emerging dioxin-like compounds (DLCs) have recruited increasing concerns about their environmental contamination, toxicity, health impacts, and mechanisms. Based on the structural similarity of dioxins and many DLCs, their toxicity was predominantly mediated by the dioxin receptor (aryl hydrocarbon receptor, AHR) in animals (including human), which can be different in expression and function among species and then possibly produce the species-specific risk or toxicity. To date, characterizing the AHR of additional species other than human and rodents can increase the accuracy of toxicity/risk evaluation and increase knowledge about AHR biology. As a key model, the medaka AHR has not been clearly characterized. Through genome survey and phylogenetic analysis, we identified four AHRs (olaAHR1a, olaAHR1b, olaAHR2a, and olaAHR2b) and two ARNTs (olaARNT1 and olaARNT2). The medaka AHR pathway was conserved in expression in nine tested tissues, of which olaAHR2a represented the predominant subform with greater abundance. Medaka AHRs and ARNTs were functional and could be efficiently transactivated by the classical dioxin congener 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), although olaAHR1a did not seem to cooperate with olaARNT2. In terms of function/sensitivity, the EC50 values of medaka olaAHR1a (9.01 ± 1.43 nM), olaAHR1b (4.00 ± 1.10 nM), olaAHR2a (8.75 ± 3.34 nM), and olaAHR2b (3.06 ± 0.81 nM) showed slight differences; however, they were all at the nM level. The sensitivity of four medaka AHRs to TCDD was similar to that of zebrafish dreAHR2 (the dominant form, EC50 = 3.14 ± 4.19 nM), but these medaka AHRs were more sensitive than zebrafish dreAHR1b (EC50 = 27.05 ± 18.51 nM). The additional comparison also indicated that the EC50 values in various species were usually within the nM range, but AHRs of certain subforms/species can vary by one or two orders of magnitude. In summary, the present study will enhance the understanding of AHR and help improve research on the ecotoxicity of dioxins/DLCs.

Tea polyphenols alleviate TBBPA-induced inflammation, ferroptosis and apoptosis via TLR4/NF-κB pathway in carp gills

The extensive application of Tetrabromobisphenol A (TBBPA) leads to the pollution of part of the water environment and brings great safety risks to aquatic animals. As a natural extract, tea polyphenols (TPs) have antioxidant and anti-inflammatory effects. Gills are one of the immune organs of fish and constitute the first line of defense of the immune system. However, it was unclear whether TPs could mitigate TBBPA-induced gills injury. Therefore, an animal model was established to investigate the effect of TPs on TBBPA-induced gills. The results indicated that TBBPA changed the coefficient and tissue morphology of carp gills. In addition, TBBPA induced oxidative stress and inflammation, leading to ferroptosis and apoptosis in carp gills. Dietary addition of TPs significantly improved the antioxidant capacity of carp, effectively inhibited the overexpression of TLR4/NF-κB and its mediated inflammatory response. Moreover, TPs restored iron metabolism, reduced the expression of pro-apoptotic factors thereby alleviating ferroptosis and apoptosis in carp gills. This study enriched the protective effect of TPs and provided a new way to improve the innate immunity of carp.