Maternal transfer of florfenicol impacts development and disrupts metabolic pathways in F1 offspring zebrafish by destroying mitochondria

Buprofezin causes early developmental toxicity of zebrafish (Danio rerio) embryos: morphological, physiological and biochemical responses

Buprofezin (BPFN), a pesticide used to control crop pests and diseases, causes potential harm to aquatic animals and the environment by leaching into aquatic ecosystems. However, there are limited studies on the toxicity of BPFN to aquatic organisms. Using zebrafish embryos, we integrated flow cytometry, qRT-PCR, RNA-seq and other techniques to assess BPFN's developmental toxicity. Additionally, IBRv2 index and Mantel test correlation were applied to comprehensively evaluate the developmental toxicity of BPFN. The results showed that BPFN induced cytotoxicity, including increased reactive oxygen species levels, mitochondrial membrane potential depolarization, and apoptosis, which further resulted in developmental toxicity of zebrafish embryos such as delayed hatching, reduced survival rate, and severe morphological deformities. BPFN also affected the number and distribution of immune cells, resulting in immunotoxicity, and disrupted the endogenous antioxidant system by altering the activities of catalase, superoxide dismutase, and glutathione S-transferase and contents of malondialdehyde and glutathione. Gene expression analysis revealed that BPFN induced changes in the expression of genes associated with oxidative stress, apoptosis, inflammation, swim bladder development, and eye development. In the comprehensive evaluation, BPFN showed the strongest developmental toxic effect in the 20 μM BPFN-treated group at 48 hpf, and there was the significant correlation between embryonic development, oxidative stress, apoptosis, and inflammatory response. The rescue experiment confirmed that astaxanthin can alleviate the embryonic developmental toxicity caused by BPFN to a certain extent. In summary, BPFN induced early developmental toxicity in zebrafish embryos, which might be associated with mitochondria-mediated apoptosis pathway induced by oxidative stress.

Mitochondrial mechanism of florfenicol-induced nonalcoholic fatty liver disease in zebrafish using multi-omics technology

Florfenicol (FF), a third-generation chloramphenicol antibiotic widely used in food-producing animals, has become a "pseudopersistent" environmental contaminant, raising concerns about its potential ecological and human health impacts. However, its bioaccumulation behavior and hepatotoxic mechanisms remain poorly understood. This study aims to address these gaps with a 28-day exposure experiment in adult zebrafish at 0.05 and 0.5 mg/L FF. Multiomic analyses (metabolomics, lipidomics, and transcriptomics), combined with histological and mitochondrial function assessments, were employed. Higher bioaccumulation was observed at 0.05 mg/L, potentially due to metabolic saturation at higher concentrations. Histological analysis revealed significant hepatic steatosis (>5 % steatosis area), indicative of moderate nonalcoholic fatty liver disease (NAFLD). Multiomic data demonstrated global dysregulation in energy metabolism, including marked alterations in lipids (accumulation of toxic sphingolipids, excessive fatty acids, and acylglycerol), amino acids, tricarboxylic acid cycle intermediates, and nucleotides. Crucially, mitochondrial dysfunction was identified as a central mechanism, with impaired respiratory chain activities, adenosine triphosphate depletion, elevated reactive oxygen species, and oxidative stress promoting NAFLD progression. These findings highlight mitochondrial impairment and oxidative stress as key drivers of FF-induced hepatotoxicity, providing novel insights into its toxicological mechanisms and emphasizing the ecological risks posed by antibiotic pollution in aquatic systems.

Temperature-dependent toxicity and mechanisms of florfenicol on the embryonic development of marine medaka (Oryzias melastigma)

The extensive use of antibiotics and their persistence in the environment have seriously threatened marine ecosystems in recent years. The frequent occurrence of extreme weather due to climate change has also increased the uncertainty of effective toxicity identification and risk assessment of the chemicals of concern. This study aimed to investigate the toxic effects and potential mechanisms of florfenicol (0.5, 10, 100, 500 and 1000 μg/L) on the embryonic development of marine medaka (Oryzias melastigma) through 21-d experiment under three temperature exposure scenarios (20, 25, and 30 °C). Considering embryo development, the highest level of florfenicol at 1000 μg/L decreased the hatching success at 25 °C, whereas the total inhibition of hatching was observed at 20 °C regardless of florfenicol concentrations of concern. The ATP content was inhibited by the highest florfenicol dose at 20 °C, while stimulated ATP content at 20 °C and 30 °C, compared to 25 °C. Fluctuation of temperatures, especially at 20 ℃, induced oxidative stresses, including increased MDA contents and decreased CYP450 and HSP90 contents. For inflammatory response-related genes (nf-κb, nlrx1, pycard, caspase 1, and il-1β), an increase of florfenicol dose led to gene upregulation at 25 °C. Conversely, gene upregulation was also observed for all treatments at 30 °C, while predominantly downregulation was observed for all treatments at 20 °C. For genes related to DNA damage and apoptosis (pi3k, akt, foxo1, tp53, bcl-2, bax, apaf-1, caspase 9, and 3), alterations in gene expression were evident for all florfenicol treatments at both 20 °C and 30 °C. Therefore, this study suggests that the combined effects of florfenicol and temperature may disrupt the normal function of mitochondria, impacting ATP production, thereby inducing oxidative stress, inflammatory response, DNA damage, and apoptosis, ultimately resulting in decreased hatching rates and increased mortality. Furthermore, the key findings of this study reveal the complex interactions between florfenicol and temperature and emphasize the need to consider temperature when identifying toxicity and mechanisms, as well as the ecological risk assessment of florfenicol in marine environments.

Metabolomics reveals the toxicity of polystyrene nanoplastics in the gills of Acrossocheilus yunnanensis

Although the ecotoxicity of polystyrene nanoplastics (PS-NP) to fish has been widely reported, their impact on the metabolic processes in fish gills and the underlying mechanisms remains unclear. Here, we investigated the effects of PS-NP on the morphology, oxidative stress, and metabolism of Acrossocheilus yunnanensis gills using conventional physicochemical indicators and metabolomics analysis. The results showed that PS-NP caused oxidative stress, and resulted in gill tissue lesions (e.g., proliferation and sloughing of gill epithelial cells). Metabolomics results showed that PS-NP exposure induced 75-164 differentially expressed metabolites (DEMs) in fish gills, and they were mainly related to lipid metabolism. DEMs induced by high concentration of PS-NP compared with low concentration of PS-NP were not only significantly enriched in glycerophospholipid metabolism, but also in sphingolipid metabolism, nucleic acid metabolism, and a variety of signaling pathways. In conclusion, the results of this work suggest that PS-NP cause disruption of phospholipid metabolism mainly by disrupting the integrity of gill tissue, which provides a new perspective for understanding the impact mechanism of PS-NP on fish gills. Given that fish play essential roles in maintaining ecological balance, the adverse effects of PS-NP on fish gills could ultimately disrupt the stability and health of the aquatic ecosystem.

Florfenicol induces malformations of embryos and causes altered lipid profile, oxidative damage, neurotoxicity, and histological effects on gonads of adult sea urchin, Paracentrotus lividus

The frequent occurrence of antibiotics in the aquatic environment has engendered negative impacts on non-target organisms. The effects of the veterinary antibiotic florfenicol (FLO) during the embryo-larval development of the sea urchin, Paracentrotus lividus was assessed using four increasing concentrations (1, 2, 5 and 10 mg/L). Furthermore, FLO toxicity to adults was investigated through the analysis of oxidative damage, histopathological alterations, lipid metabolism and acetylcholinesterase activity following an exposure period of 96 h. FLO induced embryotoxicity with estimated EC50 values of 5.75, 7.56 and 3.29 mg/L after 12 h, 24 h and 48 h, respectively. It generated oxidative stress assessed as lipid peroxidation in gonads despite the increased antioxidant activity of catalase (CAT). Neurotoxicity was also evident since the AChE activity significantly decreased. Moreover, FLO affected the lipid metabolism by increasing saturated fatty acid (SFA) and monounsaturated fatty acid proportions (MUFA), except in the group exposed to 5 mg/L. The increase in polyunsaturated fatty acid (PUFA) levels and docosahexaenoic acid (DHA, C22:6n-3) proportions were noted with all FLO concentrations. Eicosapentaenoic acid (EPA, C20:5n-3) decreased, while arachidonic acid (ARA, C20:4n-6) increased in sea urchins exposed to 5 and 10 mg/L FLO. Histopathological alterations of gonadal tissues represent an additional confirmation about the toxicity of this antibiotic that might decrease the reproductive performance of this species. Nevertheless, even if reproduction of sea urchins would be partially successful, the embryotoxicity would compromise the normal development of the embryos with consequences on the population.

Electrochemical oxidation of Florfenicol in aqueous solution with mixed metal oxide electrode: Operational factors, reaction by-products and toxicity evaluation

Veterinary antibiotics have become an emerging pollutant in water and wastewater sources due to excess usage, toxicity and resistance to traditional water and wastewater treatment. The present study explored the degradation of a model antibiotic- Florfenicol (FF) using electrochemical oxidation (EO) with Ti-RuO2/IrO2 anode. The anode material was characterized using SEM-EDS studies expressing stable structure and optimal interaction of the neighboring metal oxides with each other. The EDS results showed the presence of Ru, Ir, Ti, O and C elements with 6.44%, 2.57%, 9.61%, 52.74% and 28.64% atomic weight percentages, respectively. Optimization studies revealed pH 5, 30 mA cm-2 current density and 0.05 M Na2SO4 for 5 mg L-1 FF achieved 90% TOC removal within 360 min treatment time. The degradation followed pseudo-first order kinetics. LC-Q-TOF-MS studies revealed six predominant byproducts illustrating hydroxylation, deflourination, and dechlorination to be the major degradation mechanisms during the electrochemical oxidation of FF. Ion chromatography studies revealed an increase in Cl-, F- and NO3- ions as treatment time progressed with Cl- decreasing after the initial phase of the treatment. Toxicity studies using Zebrafish (Danio rerio) embryo showed the treated sample to be toxic inducing developmental disorders such as pericardial edema, yolk sac edema, spinal curvature and tail malformation at 96 h post fertilization (hpf). Compared to control, delayed hatching and coagulation were observed in treated embryos. Overall, this study sets the stage for understanding the effect of mixed metal oxide (MMO) anodes on the degradation of veterinary antibiotic-polluted water and wastewater sources using electrochemical oxidation.

Developmental effects and lipid disturbances of zebrafish embryos exposed to three newly recognized bisphenol A analogues

Bisphenol G (BPG), bisphenol M (BPM) and bisphenol TMC (BPTMC), are newly recognized analogues of bisphenol A (BPA), which have been detected in multiple environmental media. However, the understanding of their negative impacts on environmental health is limited. In this study, zebrafish embryos were exposed to BPA and the three analogues (0.1, 10, and 1000 μg/L) to identify their developmental toxic effects. According to our results, all of the three analogues induced significant developmental disorders on zebrafish embryos including inhibited yolk sac absorption, altered heart rate, and teratogenic effects. Oil Red O staining indicated lipid accumulation in the yolk sac region of zebrafish after bisphenol analogues exposure, which was consistent with the delayed yolk uptake. Untargeted lipidomic analysis indicated the abundance of triacylglycerols, ceramides and fatty acids was significantly altered by the three analogues. The combined analysis of lipidomics and transcriptomics results indicated BPG and BPM affected lipid metabolism by disrupting peroxisome proliferator-activated receptor pathway and interfering with lipid homeostasis and transport. This partly explained the morphological changes of embryos after bisphenol exposure. In conclusion, our study reveals that BPG, BPM and BPTMC possess acute and developmental toxicity toward zebrafish, and the developmental abnormalities are associated with the disturbances in lipid metabolism.

Rhodamine B, an organic environmental pollutant induces reproductive toxicity in parental and teratogenicity in F1 generation in vivo

This study investigated the reproductive toxicity of rhodamine B in zebrafish and its transgenerational effects on the F1 generation. In silico toxicity predictions revealed high toxicity of rhodamine B, mainly targeting pathways associated with the reproductive and endocrine systems. In vivo experiments on zebrafish demonstrated that rhodamine B exposure at a concentration of 1.5 mg/L led to significant impairments in fecundity parameters, particularly affecting females. Histopathological analysis revealed distinct changes in reproductive organs, further confirming the reproductive toxicity of rhodamine B, with females being more susceptible than males. Gene expression studies indicated significant suppression of genes crucial for ovulation in rhodamine B-treated female fish, highlighting hormonal imbalance as a potential mechanism of reproductive toxicity. Furthermore, bioaccumulation studies showed the presence of rhodamine B in both adult fish gonads and F1 generation samples, suggesting transgenerational transfer of the dye. Embryotoxicity studies on F1 generation larvae demonstrated reduced survival rates, lower hatching rates, and increased malformations in groups exposed to rhodamine B. Moreover, rhodamine B induced oxidative stress in F1 generation larvae, as evidenced by elevated levels of reactive oxygen species and altered antioxidant enzyme activity. Neurotoxicity assessments revealed reduced acetylcholinesterase activity, indicating potential neurological impairments in F1 generation larvae. Additionally, locomotory defects and skeletal abnormalities were observed in F1 generation larvae exposed to rhodamine B. This study provides comprehensive evidence of the reproductive toxicity of rhodamine B in adult zebrafish and its transgenerational effects on the F1 generation.

Assessing the ecotoxicity of florfenicol exposure at environmental levels: A case study of histology, apoptosis and microbiota in hepatopancreas of Eriocheir sinensis

The intensification of production practices in the aquaculture industry has led to the indiscriminate use of antibiotics to combat diseases and reduce costs, which has resulted in environmental pollution, posing serious threats to aquaculture sustainability and food safety. However, the toxic effect of florfenicol (FF) exposure on the hepatopancreas of crustaceans remains unclear. Herein, by employing Chinese mitten crab (Eriocheir sinensis) as subjects to investigate the toxic effects on histopathology, oxidative stress, apoptosis and microbiota of hepatopancreas under environment-relevant (0.5 and 5 μg/L), and extreme concentrations (50 μg/L) of FF. Our results revealed that the damage of hepatopancreas tissue structure caused by FF exposure in a dose-and time-dependent manner. Combined with the increased expression of apoptosis-related genes (Caspase 3, Caspase 8, p53, Bax and Bcl-2) at mRNA and protein levels, activation of catalase (CAT) and superoxide dismutase (SOD), and malondialdehyde (MDA) accumulation, FF exposure also induced oxidative stress, and apoptosis in hepatopancreas. Interestingly, 7 days exposure triggered more pronounced toxic effect in crabs than 14 days under environment-relevant FF concentration. Integrated biomarker response version 2 (IBRv2) index indicated that 14 days FF exposure under extreme concentration has serious toxicity effect on crabs. Furthermore, 14 days exposure to FF changed the diversity and composition of hepatopancreas microbiota leading remarkable increase of pathogenic microorganism Spirochaetes following exposure to 50 μg/L of FF. Taken together, our study explained potential mechanism of FF toxicity on hepatopancreas of crustaceans, and provided a reference for the concentration of FF to be used in culture of Chinese mitten crab.

A review on the antibiotic florfenicol: Occurrence, environmental fate, effects, and health risks

Florfenicol, as a replacement for chloramphenicol, can tightly bind to the A site of the 23S rRNA in the 50S subunit of the 70S ribosome, thereby inhibiting protein synthesis and bacterial proliferation. Due to the widespread use in aquaculture and veterinary medicine, florfenicol has been detected in the aquatic environment worldwide. Concerns over the effects and health risks of florfenicol on target and non-target organisms have been raised in recent years. Although the ecotoxicity of florfenicol has been widely reported in different species, no attempt has been made to review the current research progress of florfenicol toxicity, hormesis, and its health risks posed to biota. In this study, a comprehensive literature review was conducted to summarize the effects of florfenicol on various organisms including bacteria, algae, invertebrates, fishes, birds, and mammals. The generation of antibiotic resistant bacteria and spread antibiotic resistant genes, closely associated with hormesis, are pressing environmental health issues stemming from overuse or misuse of antibiotics including florfenicol. Exposure to florfenicol at μg/L-mg/L induced hormetic effects in several algal species, and chromoplasts might serve as a target for florfenicol-induced effects; however, the underlying molecular mechanisms are completely lacking. Exposure to high levels (mg/L) of florfenicol modified the xenobiotic metabolism, antioxidant systems, and energy metabolism, resulting in hepatotoxicity, renal toxicity, immunotoxicity, developmental toxicity, reproductive toxicity, obesogenic effects, and hormesis in different animal species. Mitochondria and the associated energy metabolism are suggested to be the primary targets for florfenicol toxicity in animals, albeit further in-depth investigations are warranted for revealing the long-term effects (e.g., whole-life-cycle impacts, multigenerational effects) of florfenicol, especially at environmental levels, and the underlying mechanisms. This will facilitate the evaluation of potential hormetic effects and construction of adverse outcome pathways for environmental risk assessment and regulation of florfenicol.

Proteomic Analysis of the Mitochondrial Responses in P19 Embryonic Stem Cells Exposed to Florfenicol

Florfenicol (FLO) has been shown to elicit diverse toxic effects in plants, insects, and mammals. Previously, our investigations revealed that FLO induced abnormal cardiac development and early embryonic mortality in chicken embryos. However, the effect of FLO on mitochondrial responses in stem cells remains unclear. In this study, we show that FLO significantly diminishes proliferation viability and obstructs the directed differentiation of P19 stem cells (P19SCs) into cardiomyocytes. Proteomic analysis revealed 148 differentially expressed proteins in response to FLO. Functional analysis has pinpointed FLO interference with biological processes associated with oxidative phosphorylation within the mitochondria. In alignment with the results of proteomic analysis, we confirmed that FLO inhibits the expression of both nuclear DNA-encoded and mitochondrial DNA-encoded subunits of the electron transport chain. Subsequent experiments demonstrated that FLO disrupts mitochondrial dynamics and induces the mitochondrial unfolded protein response to maintain mitochondrial homeostasis. These findings collectively highlight the significance of mitochondrial dynamics and the mitochondrial unfolded protein response to mediate the decreased proliferation viability and directed differentiation potential in P19SCs treated with FLO. In conclusion, this study provides a comprehensive overview of mitochondrial responses to FLO-induced cytotoxicity and enhances our understandings of the molecular mechanisms underlying FLO-induced embryonic toxicity.