2,4-Dinitrotoluene (DNT) Perturbs Yolk Absorption, Liver Development and Lipid Metabolism/Oxygen Transport Gene Expression in Zebrafish Embryos and Larvae

Toxic Effects of 4-Bromodiphenyl Ether (BDE-3) on Antioxidant Enzymes, Cell Viability, Histology and Biomolecules in Zebrafish Embryo-Larvae

Polybrominated diphenyl ethers (PBDEs) are a class of flame retardants that are being used widely in industrial and consumers products such as plastics, electronics, furniture, textiles and so forth. They can undergo debromination process to form less brominated diphenyl ethers, which are bioaccumulative, more volatile and more toxic in nature. The current study was conducted to reveal the biochemical, apoptotic, histopathological, ultrastructural and biomolecular (ATR-FTIR) toxicity of 4-bromodiphenyl ether (BDE-3) in zebrafish larvae. After the 96-h LC50 determination, the zebrafish embryos were exposed to sublethal concentrations of BDE-3, that is, 0.79 and 1.59 mg/L. The MDA content was found to be significantly increased in BDE-3 exposed larvae whereas the FRAP activity was found to be decreased. The catalase (CAT), glutathione-S-transferase (GST) and acetylcholinesterase (AChE) activity were observed to be significantly increased, and a decreased superoxide dismutase (SOD) activity was reported after the BDE-3 exposure in zebrafish larvae. The cell viability was reported to be decreased in zebrafish larvae after BDE-3 exposure. Histopathological and ultrastructural alterations were also observed in the BDE-3 exposed zebrafish larvae. The changes in the biomolecules such as DNA and protein were also revealed via ATR-FTIR analysis. The present investigation will help to understand the toxic nature of less brominated diphenyl ethers and could be utilised to assess environmental risk.

Effect of dietary Glycyrrhiza polysaccharides on growth performance, hepatic antioxidant capacity and anti-inflammatory capacity of broiler chickens

The primary aim of this study was to investigate the impact of varying levels of dietary Glycyrrhiza polysaccharides (GPS) on the health status of broiler chickens. A total of 288 1-day-old Arbor Acres broilers were randomly assigned to four groups with six replicates, consisting of 12 chickens in each replicate. The control group (CON) was provided with the basal diet, while the experimental groups were administered 300, 600, and 900 mg/kg of GPS in the basal diet for 42 days. The results demonstrated a significant enhancement in average daily gain (ADG) as a result of GPS supplementation (P < 0.05). The dietary GPS significantly elevated total antioxidation capability (T-AOC) and the activity of antioxidant enzymes (P < 0.05), while effectively reducing the levels of malondialdehyde (MDA) in the serum and liver (P < 0.05). Administration of GPS notably inhibited the toll-like receptor 4 (TLR4) signaling pathway (P < 0.05), decreased interleukin (IL)-6 and tumor necrosis factor-α (TNF-α) levels (P < 0.05), and increased IL-4 and IL-10 levels (P < 0.05). Additionally, the expression of crucial regulators involved in liver lipid metabolism, including sterol regulatory element binding protein 1 (SREBP-1), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC) were significantly reduced (P < 0.05). In contrast, the expression of peroxisome proliferator-activated receptor alpha (PPAR-α) was significantly enhanced in the GPS-supplemented groups (P < 0.05). In conclusion, the supplementation of GPS positively influenced the growth performance, the anti-inflammatory and antioxidant capacity of the liver, as well as liver lipid metabolism in broilers.

Apatinib induces zebrafish hepatotoxicity by inhibiting Wnt signaling and accumulation of oxidative stress

Apatinib, a small-molecule VEGFR2-tyrosine kinase inhibitor, has shown potent anticancer activity in various clinical cancer treatments, but also different adverse reactions. Therefore, it is necessary to study its potential toxicity and working mechanism. We used zebrafish to investigate the effects of apatinib on the development of embryos. Zebrafish exposed to 2.5, 5, and 10 μM apatinib showed adverse effects such as decreased liver area, pericardial oedema, slow yolk absorption, bladder atrophy, and body length shortening. At the same time, it leads to abnormal liver tissue structure, liver function and related gene expression. Furthermore, after exposure to apatinib, oxidative stress levels were significantly elevated but liver developmental toxicity was effectively ameliorated with oxidative stress inhibitor treatment. Apatinib induces down-regulation of key target genes of Wnt signaling pathway in zebrafish, and it is found that Wnt activator can significantly rescue liver developmental defects. These results suggest that apatinib may induce zebrafish hepatotoxicity by inhibiting the Wnt signaling pathway and up-regulating oxidative stress, helping to strengthen our understanding of rational clinical application of apatinib.

Creation of Environmentally Friendly Super "Dinitrotoluene Scavenger" Plants

Pervasive environmental contamination due to the uncontrolled dispersal of 2,4-dinitrotoluene (2,4-DNT) represents a substantial global health risk, demanding urgent intervention for the removal of this detrimental compound from affected sites and the promotion of ecological restoration. Conventional methodologies, however, are energy-intensive, susceptible to secondary pollution, and may inadvertently increase carbon emissions. In this study, a 2,4-DNT degradation module is designed, assembled, and validated in rice plants. Consequently, the modified rice plants acquire the ability to counteract the phytotoxicity of 2,4-DNT. The most significant finding of this study is that these modified rice plants can completely degrade 2,4-DNT into innocuous substances and subsequently introduce them into the tricarboxylic acid cycle. Further, research reveals that the modified rice plants enable the rapid phytoremediation of 2,4-DNT-contaminated soil. This innovative, eco-friendly phytoremediation approach for dinitrotoluene-contaminated soil and water demonstrates significant potential across diverse regions, substantially contributing to carbon neutrality and sustainable development objectives by repurposing carbon and energy from organic contaminants.

2,4-Dinitrotoluene (2,4-DNT) exposure induces liver developmental damage and perturbs lipid metabolism and oxygen transport gene expression in zebrafish (Danio rerio)

2,4-Dinitrotoluene (2, 4-DNT) is a common environmental pollutant. The toxic effect on mammals of 2,4-DNT has been well studied, but its toxicity on aquatic organisms is little known. In this study, 126 healthy female zebrafish (Danio rerio) were exposed to different concentrations of 2,4-DNT (0, 2, 4, 8, 12 and 16 mg/L) to determine 96-h semi-lethal concentrations (LC₅₀). And then, 90 female zebrafish were exposed to 0, 2, 4 and 8 mg/L 2,4-DNT for 5 days to study liver toxicity. Exposed zebrafish developed hypoxia features, such as floating head and breathing rapidly, and then died. 96-h LC₅₀ of 2,4-DNT in zebrafish was 9.36 mg/L. Histological data revealed that 2,4-DNT severely damaged the liver tissues, following with the round nucleus, dense interstitial tissue, dense arranged hepatocyte cords and more inflammatory cells. Additionally, the further result showed that the lower levels of lipid transport and metabolism (apoα2, mtp, ppar-α and acox) were noticed. But, exposed to 2,4-DNT for 5 days significantly upregulated the expression levels of genes involved in respiration (hif1a, tfa and ho1, p < 0.05). These results indicated that 2,4-DNT exposure disturbed lipid transport and metabolism and oxygen supply in zebrafish, which could contribute to severe damage in liver and death.

InP/ZnS quantum dots cause liver damage in rare minnow (Gobiocypris rarus) larvae

InP/ZnS quantum dots (QDs) are widely used in biomedical imaging and light-emitting component manufacturing industries, but there are few studies on their biological toxicity. In this study, we conducted experiments with rare minnow larvae and found that InP/ZnS QDs can cause liver damage. InP/ZnS QDs appeared only in the intestine of larvae and were not enriched in other parts of the larvae. The activity of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (AKP) increased, while the decrease in bile acid. InP/ZnS QDs caused hepatic cell nuclear lysis, abnormal cytoplasmic staining, and mitochondrial cristae reduction, swelling, and fragmentation. RNA-sequencing results revealed that InP/ZnS QDs exposure treatment affected the expression of genes involved in lipid metabolism, sterol synthesis, bile acid synthesis and other pathways. The excessive production of reactive oxygen species (ROS) induced by InP/ZnS QDs may be the main source of toxicity.

Microplastics alter development, behavior, and innate immunity responses following bacterial infection during zebrafish embryo-larval development

Although the hazards of microplastics (MPs) have been explored, no complete data exists on the effect of MPs on the egg chorion. This study aims to evaluate the modification of immune responses, metabolism, and behavior of zebrafish larvae (Danio rerio) depending on the moment of exposure. Larvae were exposed to 5 μm polystyrene microbeads at a concentration of 0, 100, or 1000 μg/l, according to a specified times of exposure (0-4, 4-8, 0-8 days postfertilization (dpf)), followed by a bacterial challenge at 8 dpf. After every 4 and 8 dpf, swimming activity, gene expression related to oxidative stress and immune system responses were assessed. During embryonic development, larvae exposed to a concentration of 1000 μg/l MPs already showed a significantly reduced tail coiling frequency, yolk sac resorption and heartbeat. At 8 dpf, swimming activity was altered, even without ingestion and a few days after the end of MP exposure. Our results indicated a difference in immune system (nfkb, il1β) and apoptosis (casp3a, bcl2) related gene expression depending on the timing of MP exposure, which highlighted a contrasting sensitivity according to the exposure time in MP studies. This study brings new insight into how MPs might affect zebrafish larvae health and development even without ingestion.

Bromuconazole exposure induces cardiotoxicity and lipid transport disorder in larval zebrafish

Bromuconazole (BRO), as one of the typical triazole fungicides, has not been reported on its effects on aquatic organisms. In this study, zebrafish embryos were used as experimental objects to evaluate the toxicity of BRO. In the acute embryo toxicity test, it was observed that the heart rate and growing development were affected by BRO in a concentration-dependent manner, and the half-lethal concentration (LC50) of BRO at 96 h post-fertilization (hpf) was about 11.83 mg/L. Then, low concentrations of BRO (50 ng/L, 0.075 mg/L, 0.3 mg/L, 1.2 mg/L), which were set according to the LC50 and environmental related concentrations, were used to analyze the toxic effects on the different endpoints in larval zebrafish. Interestingly, the transcriptomic analysis found that most different expressed genes (DEGs) could be focused on the pathways of lipid metabolism, myocardial function, glycometabolism, indicating that heart function and lipid metabolism in larval zebrafish were disrupted by BRO. For supporting this idea, we re-exposed the transgenic zebrafish and WT zebrafish embryos, proved that BRO caused damage to heart development and lipid transport on morphological and genetic level, which was consistent with transcriptomic results. In addition, BRO exposure caused oxidative damage in the larvae. Taken together, BRO exposure could affect the myocardial contraction function and lipid transport in larval zebrafish, accompanied by disturbances in the level of oxidative stress, which was of great significance for improving the biotoxicological information of BRO.