Search Results (2,745)

The increasing use of the zebrafish (Danio rerio) in scientific experiments has made it necessary to implement anesthesia protocols guaranteeing minimum pain and suffering for these animals and ensuring the reliability of the results obtained from their research. Therefore, we aimed to compare the effectiveness of two anesthetics, eugenol and MS-222, in consecutive administrations and evaluate the zebrafish behaviour after repeated anesthesia. Thus, several zebrafish were anaesthetized with eugenol, MS-222, and buffered MS-222 three times repeatedly with a 24-h interval between each exposure. The induction and recovery periods were also timed. Their swimming frequency was determined after each exposure to assess their behaviour after the anesthesia. Anesthesia induction was quicker with eugenol compared to MS-222. However, eugenol presented longer recovery times, which were prolonged after each exposure. Also, the swimming frequency was reduced after each anesthesia with eugenol. The buffered version of MS-222 was more efficacious than the non-buffered one. Both versions of MS-222 did not affect the swimming frequency. Based on these findings, we recommend the utilization of MS-222 buffered rather than eugenol when repeated, brief-duration anesthesia is necessitated for a study. Full article

Activation of Nrf2—the master regulator of antioxidative response—at different stages of embryonic development has been shown to result in changes in gene expression, but the tissue-specific and downstream effects of Nrf2 activation during development remain unclear. This work seeks to elucidate the tissue-specific Nrf2 cellular localization and the downstream changes in protein S-glutathionylation during critical windows of zebrafish (Danio rerio) development. Wild-type and mutant zebrafish embryos with a loss-of-function mutation in Nrf2a were treated with two canonical activators, sulforaphane (SFN; 40 µM) or tert-butylhydroquinone (tBHQ; 1 µM), for 6 h at either pharyngula, hatching, or the protruding-mouth stage. Nrf2a protein and S-glutathionylation were visualized in situ using immunohistochemistry. At the hatching stage, Nrf2a protein levels were decreased with SFN, but not tBHQ, exposure. Exposure to both activators, however, decreased downstream S-glutathionylation. Stage- and tissue-specific differences in Nrf2a protein and S-glutathionylation were identified in the pancreatic islet and liver. Protein S-glutathionylation in Nrf2a mutant fish was increased in the liver by both activators, but not the islets, indicating a tissue-specific and Nrf2a-dependent dysregulation. This work demonstrates that critical windows of exposure and Nrf2a activity may influence redox homeostasis and highlights the importance of considering tissue-specific outcomes and sensitivity in developmental redox biology. Full article

Glabridin is a widely used product in the cosmetics and pharmaceutical industry, which is generally isolated and purified from Licorice (Glycyrrhiza glabra) extract in industrial production. It has wide clinical applications, but significant toxicity has also been reported. The purity of glabridin raw material is generally between 90% and 98%. We have identified a toxic impurity, glabrene, in the industrial product glabridin. Our investigation using an AB wild-type zebrafish toxicity test showed that glabrene has a significant lethal effect with an LC₁₀ of 2.8 μM. Glabrene induced obvious malformation and disrupted cartilage development in zebrafish larvae. Furthermore, the compound significantly reduced larval mobility and caused damage to brain neural tissues. Metabolic pathway analysis and neurotransmitter quantification via ELISA indicated abnormal activation of the phenylalanine metabolic pathway, resulting in elevated dopamine and acetylcholine levels in vivo. These findings provide insights into the potential risks of glabrene contamination and offer a new reference point for enhancing safety measures and quality controls in licorice-derived products. Full article

The equilibrium state of hydrogen sulfide (H₂S), a gaseous signaling molecule produced by lysosomal metabolites, in vivo is crucial for cellular function. Abnormal fluctuations in H₂S concentration can interfere with the normal function of lysosomes, which has been closely linked to the pathogenesis of a variety of diseases. In view of this, a novel fluorescent probe Lyso-DPP based on 1,3,5-triarylpyrazolines was developed for the precise detection of H₂S in lysosomes by using the hydrophilic morpholine moiety as a lysosomal targeting unit, and 2,4-dinitroanisole as a fluorescence-quenching and H₂S-responsive unit. The probe cleverly combines the advantages of simple synthesis, sensitive blue fluorescence turn-on with a limit of detection, LOD, of 97.3 nM, good stability, and fast response time (10 min), which makes Lyso-DPP successful in portable monitoring of meat freshness in the form of test strips. Moreover, the excellent biocompatibility and precise targeting capability of the probe Lyso-DPP make it perform well in the monitoring of H₂S in lysosomes, living cells, and zebrafish. This work not only provides new technical tools for food quality control but also paves up new ideas for early diagnosis and treatment of H₂S-related diseases. Full article

The attachment of sugar to proteins and lipids is a basic modification needed for organismal survival, and perturbations in glycosylation cause severe developmental and neurological difficulties. Here, we investigated the neurological consequences of N-glycan populations in the spinal cord of Wt AB and mgat1b mutant zebrafish. Mutant fish have reduced N-acetylglucosaminyltransferase-I (GnT-I) activity as mgat1a remains intact. GnT-I converts oligomannose N-glycans to hybrid N-glycans, which is needed for complex N-glycan production. MALDI-TOF MS profiles identified N-glycans in the spinal cord for the first time and revealed reduced amounts of complex N-glycans in mutant fish, supporting a lesion in mgat1b. Further lectin blotting showed that oligomannose N-glycans were more prevalent in the spinal cord, skeletal muscle, heart, swim bladder, skin, and testis in mutant fish relative to WT AB, supporting lowered GnT- I activity in a global manner. Developmental delays were noted in hatching and in the swim bladder. Microscopic images of caudal primary (CaP) motor neurons of the spinal cord transiently expressing EGFP in mutant fish were abnormal with significant reductions in collateral branches. Further motor coordination skills were impaired in mutant fish. We conclude that identifying the neurological consequences of aberrant N-glycan processing will enhance our understanding of the role of complex N-glycans in development and nervous system health. Full article

Sensorineural hearing loss (SNHL), characterized by damage to the inner ear or auditory nerve, is a prevalent auditory disorder. This study explores the potential of Castanopsis echinocarpa (CAE) as a therapeutic agent for SNHL. In vivo experiments were conducted using zebrafish and mouse models. Zebrafish with neomycin-induced ototoxicity were treated with CAE, resulting in otic hair cell protection with an EC₅₀ of 0.49 µg/mL and a therapeutic index of 1020. CAE treatment improved auditory function and protected cochlear sensory cells in a mouse model after noise-induced hearing loss (NIHL). RNA sequencing of NIHL mouse cochleae revealed that CAE up-regulates genes involved in neurotransmitter synthesis, secretion, transport, and neuronal survival. Real-time qPCR validation showed that NIHL decreased the mRNA expression of genes related to neuronal function, such as Gabra1, Gad1, Slc32a1, CaMK2b, CaMKIV, and Slc17a7, while the CAE treatment significantly elevated these levels. In conclusion, our findings provide strong evidence that CAE protects against hearing loss by promoting sensory cell protection and enhancing the expression of genes critical for neuronal function and survival. Full article

Gastric cancer is the fourth leading cause of cancer deaths worldwide. The presence of chemoresistant cells has been used to explain this high mortality rate. These higher tumorigenic and chemoresistant cells involve cancer stem cells (CSCs), which have the potential for self-renewal, a cell differentiation capacity, and a greater tumorigenic capacity. Our research group identified gastric cancer stem cells (GCSCs) with the CD24+CD44+CD326+ICAM1+ immunophenotype isolated from gastric cancer patients. Interestingly, this GCSC immunophenotype was absent in cells isolated from healthy people, who presented a cell population with a CD24+CD44+CD326+ immunophenotype, lacking ICAM1. We aimed to explore the role of ICAM1 in these GCSCs; for this purpose, we isolated GCSCs from the AGS cell line and generated a GCSC line knockout for ICAM1 using CRISPR/iCas9, which we named GCSC-ICAM1^KO. To assess the role of ICAM1 in the GCSCs, we analyzed the migration, invasion, and chemoresistance capabilities of the GCSCs using in vitro assays and evaluated the migratory, invasive, and tumorigenic properties in a zebrafish model. The in vitro analysis showed that ICAM1 regulated STAT3 activation (pSTAT3-ser727) in the GCSCs, which could contribute to the ability of GCSCs to migrate, invade, and metastasize. Interestingly, we demonstrated that the GCSC-ICAM1^KO cells lost their capacity to migrate, invade, and metastasize, but they exhibited an increased resistance to a cisplatin treatment compared to their parental GCSCs; the GCSC-ICAM1^KO cells also exhibited an increased tumorigenic capability in vivo. Full article

Autism spectrum disorder (ASD) is a multifactorial neurodevelopmental condition with several identified risk factors, both genetic and non-genetic. Among these, prenatal exposure to valproic acid (VPA) has been extensively associated with the development of the disorder. The zebrafish, a cost- and time-effective model, is useful for studying ASD features. Using validated VPA-induced ASD zebrafish models, we aimed to provide new insights into VPA exposure effects during embryonic development and to identify new potential biomarkers associated with ASD-like features. Dose–response analyses were performed in vivo to study larval phenotypes and mechanisms underlying neuroinflammation, mitochondrial dysfunction, oxidative stress, microglial cell status, and motor behaviour. Wild-type and transgenic Tg(mpeg1:EGFP) zebrafish were water-exposed to VPA doses (5 to 500 µM) from 6 to 120 h post-fertilisation (hpf). Embryos and larvae were monitored daily to assess survival and hatching rates, and numerous analyses and tests were conducted from 24 to 120 hpf. VPA doses higher than 50 µM worsened survival and hatching rates, while doses of 25 µM or more altered morphology, microglial status, and larval behaviours. VPA 50 µM also affected mRNA expression of inflammatory cytokines and neurogenesis-related genes, mitochondrial respiration, and reactive oxygen species accumulation. The study confirmed that VPA alters brain homeostasis, synaptic interconnections, and neurogenesis-related signalling pathways, contributing to ASD aetiopathogenesis. Further studies are essential to identify novel ASD biomarkers for developing new drug targets and tailored therapeutic interventions for ASD. Full article

Chronic exposure to heavy metals has been widely demonstrated to induce pathological features in different tissues and, in particular, in the central nervous system. Specific neurons, including dopaminergic neurons, were observed to be more susceptible to toxic agents. Several previous studies performed on zebrafish (Danio rerio) models observed that exposure to nickel (one of the most abundant heavy metals) induces impairment of memory and anxious-like behaviors. Nevertheless, this phenotypical evidence has not been associated with dopaminergic system damage, and no reports showing the effects of nickel on dopaminergic neurons are available. In this study, we aim to analyze the precise distribution and variation in dopaminergic neurons in adult zebrafish after chronic (96 h) exposure to nickel ions dissolved in water at different sub-lethal doses (0.4 mg L⁻¹; 2 mg L⁻¹ and 4 mg L⁻¹). The effects of treatment on dopaminergic neurons were evaluated by measuring transcript and protein levels of tyrosine hydroxylase (TH), described as a dopaminergic neuron marker. As shown, the expression of the th1 and th2 genes was reduced in the entire brain of zebrafish treated with nickel. Immunostaining analysis allowed us to localize TH-expressing neurons mainly in the posterior tuberculum, where they were observed to be reduced after nickel treatment in a dose-dependent fashion. Consistently, the TUNEL assay revealed a significant increase in apoptosis of TH-expressing cells after treatment with 2 mg L⁻¹ and 4 mg L⁻¹ of nickel. Our findings represent the first evidence of the effect of nickel on the dopaminergic system. Full article

Plants are an immense source of drugs, and 50% of modern pharmacopeia has a plant origin. With increasing life expectancy in humans, many age-related degenerative diseases converge on oxidative cellular stress pathways. This provides an opportunity to develop broad treatments by targeting the cause of common pathologic cell degeneration. Toxicological effects can be readily assessed in a live animal model system to establish potential fauna for clinical use. Here, we characterized and evaluated the antioxidant potential and toxicological effects of anise myrtle (Syzygium anisatum) and lemon myrtle (Backhousia citriodora) leaves. Using zebrafish larvae, a model for high-throughput pre-clinical in vivo toxicology screening, we identified safe levels of extract exposures for development of future therapeutics. The antioxidant capacity and toxicity were very similar in these two myrtles. The LC₅₀-96h for anise myrtle was 284 mg/L, and for lemon myrtle, it was 270 mg/L. These measurements are comparable to ongoing studies we are performing using the same criteria in zebrafish, which allow for robust testing and prioritization of natural fauna for drug development. Full article

In the present study, the toxicity of nicosulfuron to Danio rerio embryos was evaluated in three experiments through standardized toxicity tests according to OECD TG236 guidelines. In the first experiment, six concentrations of nicosulfuron (0, 0.1, 1, 10, 100, 1000 mg/L) were tested under optimal conditions (26 °C, pH 7.0) to assess the general sensitivity of zebrafish embryos to nicosulfuron. The second and third experiment examined the effects of different pH levels (5.0 and 9.0) and temperatures (21 °C and 31 °C) on the toxicity at four nicosulfuron concentrations (0, 10, 100, 1000 mg/L). Additionally, the sub-organismic effects of nicosulfuron on stress protein levels (Hsp70) of fish embryos were analyzed. Throughout the embryo experiments, no malformations were observed in all experiments. The survival rate exceeded 80% in all groups except for the 21 °C (pH 7.0) treatment groups. No significant effect of nicosulfuron on the survival rate was found at the same temperature or pH (p > 0.05). No significant difference in the heart rate was found among all nicosulfuron groups (p > 0.05) at 21 °C. The heart rate of fish embryos at 31 °C, pH 5.0 and pH 9.0 increased with nicosulfuron concentrations. Except for the pH 5.0 (26 °C) and 21 °C (pH 7.0) treatment groups, nicosulfuron was found to increase the hatching rate of embryos in other treatments; however, the corresponding times of action were different. At 21 °C (pH 7.0), the embryos did not hatch until 144 h post-fertilization. In terms of proteotoxicity, nicosulfuron was found to be more toxic to zebrafish embryos in the 21 °C, pH 5.0 and pH 9.0 treatment groups. However, at 31 °C, no significant difference in Hsp70 levels was found among all the different nicosulfuron concentrations (p > 0.05). Our results show that nicosulfuron exerts a weak toxicity to zebrafish embryos; however, this toxicity is amplified by inappropriate pH or temperature conditions. Full article

Owing to the presence of drugs targeting adrenergic receptors in aquatic ecosystems, considerable attention has been directed towards their environmental distribution and fate in recent decades. However, their potential impacts on non-target aquatic organisms, particularly fish, have received relatively limited investigation. In this study, moxisylyte (MOX) and propranolol (PRO) were selected as representatives of α- or β-adrenergic receptor antagonist, respectively, and we assessed their effects on the early life stages of zebrafish, especially on the nervous and cardiovascular systems. Although both compounds exhibited marginal effects on zebrafish survival, hatching and gross abnormality following exposure to concentrations ranging from 1 to 625 μg/L, they adversely affected the development of cardiovascular and nervous systems, but through different mechanisms of action, as evidenced by variations in gene transcriptional responses and enzyme activities. Notably, cardiovascular responses appear promising for use as potential biomarkers for exposure to drugs targeting adrenergic receptors. This study enhances our understanding of the ecotoxicological risks posed by α- and β-blockers in fish. Nonetheless, further investigation is needed to elucidate the precise mechanisms underlying the impacts of drugs targeting adrenergic receptors due to our limited knowledge of the physiological functions of the adrenergic system in fish. Full article

The subfamily Rasborinae is a species-rich group of freshwater fish related to zebrafish; however, its taxonomy remains unclear. We present the complete mitogenome and corresponding polyadenylated mitotranscriptome of Rasbora rasbora (Hamilton 1822) based on long-read and high-coverage Oxford Nanopore Technology sequencing. The mitogenome size, gene content, and gene organization correspond to the typical vertebrate composition, and the mitogenome generates 10 polyadenylated mRNAs. Two alternative polyadenylation sites of ND5 mRNA were detected, one with a 596 nt 3′untranslated region corresponding to the antisense ND6 gene. Polyadenylation also generates seven of the mRNA UAA stop codons. Complete mitogenome sequences, excluding the control region, were carefully aligned for RNA-coding and protein-coding features using 54 available species of the subfamily Rasborinae. The phylogenetic analyses based on maximum likelihood, Bayesian inference, and neighbor-joining tree building methods confirm the transfer of R. rasbora into the Sumatrana species group. The overall phylogeny of the subfamily Rasborinae supports with high confidence some previously observed changes within this subfamily, as well as contradicts some conclusions set by previous studies. Full article

Background: Postoperative atrial fibrillation (POAF) and acute kidney injury (AKI) are common yet significant complications after cardiac surgery, with incidences of up to 40% for each. Here, we assessed plasma nitrite and serum interleukin-6 (IL-6) levels before and after cardiac surgery to quantify the extent to which oxidative stress and inflammation contribute to POAF and AKI occurrence. Methods: We prospectively enrolled 206 cardiac surgical patients. Plasma nitrite and serum IL-6 levels were determined preoperatively and at 24 h, 48 h and 72 h postoperatively. The patients had continuous EKG monitoring for occurrence of POAF, while daily serum creatinine was measured for determination of stage 1 + AKI. Results: Postoperatively, 78 (38%) patients experienced AF, and 47 (23%) patients experienced stage 1 + AKI. POAF analysis: Age, ACE-inhibitor use, valve surgery and percent change in baseline plasma nitrite at 24 h postoperatively were associated with POAF in multiple logistic regression analysis. The inclusion of this new biomarker significantly improved the POAF prediction model (AUC 0.77 for clinical risk factors alone, to AUC 0.81). AKI analysis: A history of diabetes mellitus was associated with AKI in multiple logistic regression analysis, and the addition of preoperative IL-6 levels improved the prediction model for AKI occurrence (AUC 0.69 to AUC 0.74). Conclusions: We previously observed selective upregulation of NADPH oxidase isoform 4 (NOX4) in patients with AF, a critical causal role of NOX4 for AF in zebrafish and a robust inhibitory effect of nitric oxide (NO) on NOX4. Our data innovatively demonstrate that a reduction in circulating nitrite levels, likely implicative of elevated NOX4-mediated oxidative stress, independently associates with POAF and improves POAF prediction, whereas the inclusion of circulating IL-6 levels improves the prediction model for AKI. Therefore, therapeutic strategies to mitigate these pathophysiological sequalae of surgical stress may reduce the incidence of severe postoperative complications of POAF and AKI. Full article

Gamma-oryzanol (ORY), found in rice (Oryza sativa L.), is a mixture of ferulic acid esters with triterpene alcohols, well-known for its antioxidant and anti-inflammatory properties. Our past research demonstrated its positive impact on cognitive function in adult mice, influencing synaptic plasticity and neuroprotection. In this study, we explored whether ORY can exert neuro-differentiating effects by using different experimental models. For this purpose, chemical characterization identified four components that are most abundant in ORY. In human neuroblastoma cells, we showed ORY’s ability to stimulate neurite outgrowth, upregulating the expression of GAP43, BDNF, and TrkB genes. In addition, ORY was found to guide adult mouse hippocampal neural progenitor cells (NPCs) toward a neuronal commitment. Microinjection of ORY in zebrafish Tg (-3.1 neurog1:GFP) amplified neurog1-GFP signal, islet1, and bdnf mRNA levels. Zebrafish nrf2a and nrf2b morphants (MOs) were utilized to assess ORY effects in the presence or absence of Nrf2. Notably, ORY’s ability to activate bdnf was nullified in nrf2a-MO and nrf2b-MO. Furthermore, computational analysis suggested ORY’s single components have different affinities for the Keap1-Kelch domain. In conclusion, although more in-depth studies are needed, our findings position ORY as a potential source of bioactive molecules with neuro-differentiating potential involving the Nrf2 pathway. Full article