Cyhexatin causes developmental toxic effects by disrupting endocrine system and inducing behavioral inhibition, apoptosis and DNA hypomethylation in zebrafish (Danio rerio) larvae

Role and Relationship Between Homocysteine and H2S in Ischemic Stroke

Homocysteine (Hcy), a sulfur-containing amino acid, is an important intermediate product of methionine metabolism. Hcy can be either metabolized to cysteine, a precursor for glutathione synthesis and hydrogen sulfide (H2S) production, or regenerated back to methionine. Besides, the Hcy metabolism is central to supply methyl groups, which are essential for DNA methylation. In the transsulfuration pathway of Hcy metabolism, Hcy is metabolized to form cysteine and H2S by catalytic enzymes, containing cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE). Hcy metabolism-related enzymes and coenzymes, such as vitamin B6, vitamin B12, and folic acid, are closely related to hyperhomocysteinemia (HHcy), which is frequently accompanied by reduced H2S content. An accumulating study has revealed that HHcy is a risk factor for ischemic stroke, while H2S, served as a gaseous mediator at the physiological level, has protective effects against ischemic stroke. This review outlined the literature data from recent research related to Hcy metabolism and H2S production and described the roles and relationship among Hcy metabolism and H2S in ischemic stroke.

Exploring the epigenetic impacts of atrazine in zebrafish: Unveiling mechanisms of neurotoxicity, reproductive toxicity, and implications for human health

Atrazine (ATZ), a widely utilized herbicide, is notable for its long environmental half-life and high solubility, raising significant concerns regarding its ecological and health impacts. While debates continue over its role as an endocrine disruptor, increasing attention has been directed toward its potential epigenetic effects. Utilizing the zebrafish model, a vertebrate with considerable genetic similarity to humans, provides valuable insights into how ATZ exposure may translate into human health risks. This review systematically examines the differential DNA methylation induced by ATZ's non-competitive inhibition of DNA methyltransferases, miRNA dysregulation resulting from mutations in miRNA processing enzymes, and the complex epigenetic interactions affecting histone modifications. Additionally, potential epigenetic biomarkers for ATZ exposure are proposed, which could advance targeted treatment strategies and improve health risk assessments. This synthesis of current understanding identifies knowledge gaps and guides future research towards a more comprehensive understanding of ATZ's epigenetic mechanisms.

Toxic endpoints or ubiquitous expression?

This opinion article questions the underlying causes of malformations observed in early developmental stages of zebrafish exposed to a range of chemicals. The research focuses on determining whether these developmental abnormalities arise due to the inherent sensitivity of zebrafish to chemical exposure or if they are related to the ubiquitous expression of certain genes within the zebrafish genome. By analysing different studies on zebrafish embryos to various chemical agents and analysing the resulting malformations, the study aims to differentiate between the effects of chemical sensitivity and the role of gene expression in developmental disruptions. Findings from this investigation will contribute to a deeper understanding of the mechanisms driving developmental toxicity in zebrafish, with implications for broader environmental and genetic research.

Transcriptome analysis unveils the mechanisms of oxidative stress, immunotoxicity and neurotoxicity induced by benzotriazole UV stabilizer-328 in zebrafish embryos

As an emerging pollutant, ultraviolet stabilizer-328 (UV-328) has been frequently detected in aquatic environments and attracted great attention. Nevertheless, the toxicity and mechanisms of UV-328 to aquatic organisms are still not fully understood. In particular, the immunotoxicity and neurotoxicity of UV-328 to aquatic organisms and their mechanisms have not been reported yet. In this experiment, the developmental toxicity, oxidative stress, apoptosis, immunotoxicity and neurotoxicity in zebrafish embryos exposed to UV-328 with concentrations of 0.01, 0.1, 1, 10 and 100 µg/L for 120 h were studied. By measuring the growth and developmental indices, production of ROS, enzyme activities, MDA content and expression of genes related to oxidative, immune and nerve, and histopathological analysis, it was found that UV-328 had developmental toxicity to zebrafish larvae, and could induce oxidative stress, immunotoxicity and neurotoxicity to zebrafish larvae even at environmental concentrations with concentration-dependent effects. Moreover, the results of transcriptome analysis and qRT-PCR validation suggested that immune and nerve disorders were caused by UV-328 in zebrafish larvae through regulating the RIG-I-like receptor signaling pathway and neuroactive ligand-receptor interaction, respectively. In addition, transcriptome analysis further revealed that UV-328 could mediate the RIG-I to induce oxidative stress through p38-MAPK/p53 signaling pathway, leading to apoptosis and oxidative damage. In addition, the p38-MAPK signaling pathway enhanced ROS production and activated inflammatory cytokines to induce immunotoxicity. The results of the present work provided important information for understanding the toxicity of UV-328 to aquatic organisms and evaluating its ecological risk in aquatic environment.

Insights into spirotetramat-induced thyroid disruption during zebrafish (Danio rerio) larval development: An integrated approach with in vivo, in vitro, and in silico analyses

Spirotetramat (SPT), a tetronic acid-derived insecticide, is implicated in reproductive and lipid metabolism disorders, as well as developmental toxicity in fish. While these effects are documented, the precise mechanisms underlying its developmental toxicity are not fully elucidated. In this study, zebrafish embryos (2 h post-fertilization, hpf) were exposed to four concentrations of SPT (0, 60, 120, and 240 μg/L) until 21 dpf (days post-fertilization). We delved into the mechanisms by examining its potential disruption of the thyroid endocrine system, employing in vivo, in vitro, and in silico assays. The findings showed notable developmental disturbances, including reduced hatching rates, shortened body lengths, and decelerated heart rates. Additionally, there was an increase in malformations and a decline in locomotor activity. Detailed analyses revealed that SPT exposure led to elevated thyroid hormone levels, perturbed the hypothalamic-pituitary-thyroid (HPT) axis transcript levels, amplified deiodinase type I (Dio1) and deiodinase type II (Dio2) activities, and both transcriptionally and proteomically upregulated thyroid receptor beta (TRβ) in larvae. Techniques like molecular docking and surface plasmon resonance (SPR) confirmed SPT's affinity for TRβ, consistent with in vitro findings suggesting its antagonistic effect on the T3-TR complex. These insights emphasize the need for caution in using tetronic acid-derived insecticides.