Naringenin (NGN), a flavonoid widely utilized in agricultural and pharmaceutical applications, has increasingly become a source of environmental concern. This study systematically evaluated the develo Show more
Naringenin (NGN), a flavonoid widely utilized in agricultural and pharmaceutical applications, has increasingly become a source of environmental concern. This study systematically evaluated the developmental toxicity of NGN in zebrafish embryos. Our results showed that NGN exposure caused dose-dependent increases in embryonic mortality and induced a range of developmental malformations, including reduced body length, impaired eye and ear development, and cardiac dysfunction. Behavioral analyses revealed significant deficits in locomotor activity and sensory responses at concentrations of 5 and 10 mg/L. Molecular assessments via RT-qPCR demonstrated that NGN disrupted the expression of multiple genes critical for cardiac (kcnh2a, kcnh2b, hand2, has2, myh7, tnnt2a), otic (col2a1a, sox9a, sox9b), liver (hhex, leg1.1), visual (gnat1, gnat2), apoptotic (bax, casp9, casp3), and neurodevelopmental (pomca, bdnf, gfap, mbpa, s100b) pathways. Notably, NGN at 10 mg/L inhibited apoptosis and altered liver function, whereas a concentration of 15 mg/L promoted apoptosis, and these results suggest that NGN may interfere with the developmental processes of zebrafish embryos through different mechanisms at low and high concentrations, exhibiting a non-monotonic dose-response relationship. These findings highlight the potential ecological hazards of NGN contamination in aquatic environments, emphasizing the need for stricter management and further research into its long-term and combined effects with other pollutants. Our research offers new perspectives into the molecular and phenotypic mechanisms of NGN toxicity and underscores the importance of comprehensive risk assessment for emerging environmental contaminants. Show less
Microcystin-LR (MC-LR) is the most prevalent and toxic microcystin congeners, posing a significant threat to aquatic organisms as well as humans; however, its underlying toxic mechanisms remain incomp Show more
Microcystin-LR (MC-LR) is the most prevalent and toxic microcystin congeners, posing a significant threat to aquatic organisms as well as humans; however, its underlying toxic mechanisms remain incompletely elucidated. In this study, the negative impacts of MC-LR and the underlying mechanisms in zebrafish larvae were investigated. The results demonstrated that MC-LR could penetrate zebrafish larvae and induce developmental toxicity, characterized by reduced heart rate, decreased body length, and smaller eye area. H&E staining revealed that MC-LR exposure significantly reduced the thickness of retinal layers. qPCR analysis showed altered expression levels of phototransduction and retinoic acid metabolism related genes (rho, gnat1, gnat2, opn1sw1, opn1lw1, opn1mw1, rdh1, rbp4, cyp26a1, and aldh1a2). These findings suggest that MC-LR may disrupt retinal structure and impair normal visual function in larvae. Behavioral analyses indicated that MC-LR exposure weakened spontaneous movements in embryos and impaired swimming ability in larvae, potentially due to significant alterations in the levels of glutamate, γ-aminobutyric acid, and brain-derived neurotrophic factor. Additionally, MC-LR exposure reduced visuomotor responses, delayed reactions to external stimuli, and disrupted circadian rhythms, which may be attributed to altered expression levels of circadian rhythm-related genes (clock1a, bmal1a, per1b, cry1a, and per2), as well as changes in melatonin and arylalkylamine N-acetyltransferase 2 levels. Overall, these findings indicate that MC-LR exposure induces developmental neurotoxicity in zebrafish, and that impaired visual function and disrupted circadian rhythm may serve as key contributing factors to MC-LR-induced behavioral abnormalities, which warrant further emphasis in future ecological and health risk assessments. Show less