Transgenerational effects of BDE-47 to zebrafish based on histomorphometry and toxicogenomic analyses

Endocytosis, endoplasmic reticulum, actin cytoskeleton affected in tilapia liver under polystyrene microplastics and BDE153 acute co-exposure

Studies showed that contaminants adhered to the surface of nano-polystyrene microplastics (NPs) have a toxicological effect. Juveniles tilapia were dispersed into four groups: the control group A, 75 nm NPs exposed group B, 5 ng·L-1 2,2',4,4',5,5'-hexabromodiphenyl ether group C (BDE153), and 5 ng·L-1 BDE153 + 75 nm MPs group D, and acutely exposed for 2, 4 and 8 days. The hepatic histopathological change, enzymatic activities, transcriptomics, and proteomics, have been performed in tilapia. The results showed that the enzymatic activities of anti-oxidative (ROS, SOD, EROD), energy (ATP), lipid metabolism (TC, TG, FAS, LPL, ACC), pro-inflammatory (TNFα, IL-1β) and apoptosis (caspase 3) significantly increased at 2 d in BDE153 and the combined group and together in BDE153 group at 8 d. Histological slice showed displaced nucleus by BDE153 exposure and vacuoles appeared in the combined groups. KEGG results revealed that pathways associated with endocytosis, protein processing in endoplasmic reticulum and regulation of actin cytoskeleton were significantly enriched. The selected genes associated with neurocentral development (ganab, diaph3/baiap2a/ddost decreased and increased), lipid metabolism (ldlrap1a decreased, stt3b increased), energy (agap2 decreased, uggt1 increased) were affected under co-exposure, and fibronectin significantly increased via proteome. Our study indicated that endocytosis, protein processing in endoplasmic reticulum, regulation of actin cytoskeleton were affected in tilapia liver under NPs and BDE153 co-exposure.

Ecotoxicological risk assessment of the novel psychoactive substance Esketamine: Emphasis on fish skeletal, behavioral, and vascular development

Novel psychoactive substances (NPS), such as Esketamine (Esket), often contaminate the aquatic ecosystems following human consumption, raising concerns about the residues and potential ecological hazards to non-target organisms. The study used zebrafish as a model organism to investigate the developmental toxicity and ecotoxicological effects of acute Esket exposure. Our findings demonstrate that exposure to Esket significantly affected the early development and angiogenesis of zebrafish embryos/larvae. The mandible length was significantly decreased, and the angles between the pharyngeal arch cartilages were narrowed compared to the control group (all P < 0.05). Additionally, Esket resulted in a decrease of 47.6-89.8 % in the number of neural crest cells (NCC). Transcriptome analysis indicated altered expression of genes associated with cartilage and osteoblast growth. Moreover, Esket significantly inhibited swimming ability in zebrafish larvae and was accompanied by behavioral abnormalities and molecular alterations in the brain. Potential mechanisms underlying Esket-induced behavioral disorders involve neurotransmitter system impairment, abnormal cartilage development and function, aberrant vascular development, as well as perturbations in oxidative stress and apoptosis signaling pathways. Notably, the dysregulation of skeleton development through the bone morphogenetic protein (BMP) signaling pathway is identified as the primary mechanistic behind Esket-induced behavioral disorder. This study enhances our understanding of Esket's ecotoxicology profile and provides a comprehensive assessment of the environmental risks associated with NPS.

BDE-47-induced damage prevented by melatonin in grass carp hepatocytes (L8824)

Polybrominated diphenyl ethers (PBDEs) are toxic to organisms with melatonin (MT) providing protection for tissues and cells against these. This study investigates the mechanism of damage of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) and the cellular protection of MT on grass carp hepatocytes. Grass carp hepatocytes were exposed to 25 μmol/L BDE-47 and/or 40 μmol/L MT for 24 h before testing. Acridine orange/ethidium bromide (AO/EB) double fluorescence staining results showed that BDE-47 could induce cell apoptosis. The expression levels of the endoplasmic reticulum (ER) stress-related genes ire1, atf4, grp78, perk, and chop were also significantly up-regulated (P < 0.01). The levels of the apoptosis-related genes caspase3, bax, and caspase9 were significantly up-regulated (P < 0.0001), while the level of bcl-2 was significantly down-regulated (P < 0.01). Compared with the BDE-47 group, the BDE-47 + MT group showed reduced levels of ER and apoptosis of hepatocytes, while the expression of the ER stress-related genes ire1, atf4, grp78, perk, and chop and the apoptosis-related genes caspase3, bax, and caspase9 were down-regulated (P < 0.05), and the level of bcl-2 was up-regulated (P < 0.01). In conclusion, BDE-47 can activate ER and apoptosis in grass carp hepatocytes, while MT can reduce these responses.

The uses of zebrafish (Danio rerio) as an in vivo model for toxicological studies: A review based on bibliometrics

An in vivo model is necessary for toxicology. This review analyzed the uses of zebrafish (Danio rerio) in toxicology based on bibliometrics. Totally 56,816 publications about zebrafish from 2002 to 2023 were found in Web of Science Core Collection, with Toxicology as the top 6 among all disciplines. Accordingly, the bibliometric map reveals that "toxicity" has become a hot keyword. It further reveals that the most common exposure types include acute, chronic, and combined exposure. The toxicological effects include behavioral, intestinal, cardiovascular, hepatic, endocrine toxicity, neurotoxicity, immunotoxicity, genotoxicity, and reproductive and transgenerational toxicity. The mechanisms include oxidative stress, inflammation, autophagy, and dysbiosis of gut microbiota. The toxicants commonly evaluated by using zebrafish model include nanomaterials, arsenic, metals, bisphenol, and dioxin. Overall, zebrafish provide a unique and well-accepted model to investigate the toxicological effects and mechanisms. We also discussed the possible ways to address some of the limitations of zebrafish model, such as the combination of human organoids to avoid species differences.