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The increasing use of UV filters, such as benzophenone-3 (BP-3) and titanium dioxide nanoparticles (TiO2 NPs), has raised concerns regarding their ecotoxicological effects on the aquatic environment. The aim of the present study was to examine the embryo-larval toxicity attributed to BP-3 or TiO2 NPs, either alone or in a mixture, utilizing zebrafish (Danio rerio) as a model after exposure to environmentally relevant concentrations of these compounds. Zebrafish embryos were exposed to BP-3 (10, 100, or 1000 ng/L) or TiO2 NPs (1000 ng/L) alone or in a mixture (BP-3 10, 100, or 1000 ng/L plus 1000 ng/L of TiO2 NPs) under static conditions for 144 hr. After exposure, BP-3 levels were determined by high-performance liquid chromatography (HPLC). BP-3 levels increased in the presence of TiO2 NPs, indicating that the BP-3 degradation decreased in the presence of the NPs. In addition, in the presence of zebrafish, BP-3 levels in water decreased, indicating that zebrafish embryos and larvae might absorb BP-3. Data demonstrated that, in general, environmentally relevant concentrations of BP-3 and TiO2 NPs, either alone or in a mixture, did not significantly induce changes in heart and spontaneous contractions frequencies, levels of reactive oxygen species (ROS), morphological and morphometric parameters as well as mortality rates during 144 hr exposure. However, the groups exposed to TiO2 NPs alone and in a mixture with BP-3 at 10 ng/L exhibited an earlier significant hatching rate than the controls. Altogether, the data indicates that a potential ecotoxicological impact on the aquatic environment exists. [ABSTRACT FROM AUTHOR]

We aimed to evaluate how different types of toothpaste (TP) for children affected molecular mechanisms of odontogenesis in zebrafish embryos. Commercially available TPs were selected according to their detergent contents as the cocamidopropyl betaine (CAPB) containing TP (TP1) and sodium lauryl sulfate (SLS) containing TP (TP2). TP3 contained no detergent. Effects of SLS, and CAPB alone were also examined. TP and detergent concentrations affecting development were determined as 750 mg/L and 4 mg/L, respectively. Embryos were exposed to TP1, TP2, TP3, SLS, CAPB, and embryo medium (control) for 72 h post fertilization. Acetylcholinesterase (AChE) activity and oxidant–antioxidant parameters were analyzed spectrophotometrically. Expressions of tooth development genes were evaluated by reverse transcription PCR (RT-PCR). Intraocular distance, lower jaw, and ceratohyal cartilage length were displayed using Alcian Blue staining. axin2 and wnt10a expressions increased in SLS and TP2 groups. igf2a and eve1 expressions decreased in all groups except TP3. nrOb1 expression decreased in TP1, SLS, and CAPB groups. Oxidant–antioxidant balance was disturbed in all groups except TP3, evidenced by increased lipid peroxidation, nitric oxide. SLS, and CAPB groups were more affected in terms of AChE, glutathione-S-transferase, and superoxide dismutase; perturbations were observed in cartilage structures. Altered expression of tooth development gene axin2 correlated with wnt10a, and with changes in cartilage structures in SLS and TP2 groups. TP3 group presented no disruptions in oxidant–antioxidant balance. Our study shows the availability of externally developing zebrafish embryos in examining the effects of TP' contents on embryogenesis. [ABSTRACT FROM AUTHOR]

Due to their selective toxicity to insects, nicotinoid compounds have been widely used to control pests in crops and livestock around the world. However, despite the advantages presented, much has been discussed about their harmful effects on exposed organisms, either directly or indirectly, with regards to endocrine disruption. This study aimed to evaluate the lethal and sublethal effects of imidacloprid (IMD) and abamectin (ABA) formulations, separately and combined, on zebrafish (Danio rerio) embryos at different developmental stages. For this, Fish Embryo Toxicity (FET) tests were carried out, exposing two hours post-fertilization (hpf) zebrafish to 96 hours of treatments with five different concentrations of abamectin (0.5–11.7 mg L−1), imidacloprid (0.0001–1.0 mg L−1), and imidacloprid/abamectin mixtures (LC50/2 − LC50/1000). The results showed that IMD and ABA caused toxic effects in zebrafish embryos. Significant effects were observed regarding egg coagulation, pericardial edema, and lack of larvae hatching. However, unlike ABA, the IMD dose-response curve for mortality had a bell curve display, where medium doses caused more mortality than higher and lower doses. These data demonstrate the toxic influence of sublethal IMD and ABA concentrations on zebrafish, suggesting that these compounds should be listed for river and reservoir water-quality monitoring. [ABSTRACT FROM AUTHOR]

The Organization for Economic Co-operation and Development (OECD）Test Guideline (TG) 236 for zebrafish embryo acute toxicity testing was adopted for chemical toxicity assessment in 2013. Due to the increasing demand for prediction and evaluation of the acute toxicity using zebrafish embryos, we developed a method based on OECD 236 test guideline with the aim to improve the testing efficiency. We used 4–128 cell stage zebrafish embryos and performed an exposure assay in a 96-well microtiter plate, observing the lethality endpoints of embryos at 48-h postexposure. A total of 32 chemicals (two batches) were used in the comparison study. Our results indicated that the logarithmic LC50 (half lethal concentration) obtained by the modified method exhibited good correlation with that obtained by the OECD 236 testing method, and the R2 of the linear regression analysis was 0.9717 (0.9621 and 0.9936 for the two batches, respectively). Additionally, the intra- and inter-laboratory coefficient of variation (CVs) for the LC50 from the testing chemicals (17 chemicals in second batch) was less than 30%, except for CuSO4. Therefore, the developed method was less time-consuming and demonstrated a higher throughput for toxicity testing compared to the prior method. We argue the developed method could be used as an additional choice for high-throughput zebrafish embryo acute toxicity test. [ABSTRACT FROM AUTHOR]

Heavy metal toxicity has become a global health burden, exerting various physiological effects on aquatic animals and humans. Zebrafish (Danio rerio) has emerged as a real-time model system for toxicological study. We previously reported the effects of arsenic on the embryonic development of zebrafish. The current study aimed to get deep insights into the toxic effects of another heavy metal, lead, on the early embryonic development of wild-caught zebrafish. We exposed freshly collected zebrafish embryos to different lead concentrations and studied different developmental and morphological changes using an inverted microscope. In a separate experiment, embryos were exposed to a combination of lead and arsenic to evaluate the combined effects of the elements. Lead concentration of as low as 0.25 mM resulted in developmental and morphological abnormalities in the zebrafish embryos. Exposure to different concentrations (0.25 mM, 0.5 mM, and 0.75 mM) caused a higher mortality rate of the embryos. Besides, an increased rate of arrested hatching, irregularities in size and shape of the yolk sac, deformed otic vesicle, and body curvature were observed in a dose-dependent manner. Lead exposure also resulted in reduced heart rate and severe pericardial edema. The combined effect of minimum concentrations of lead and arsenic that causes toxicity individually (0.25 mM and 1.0 mM, respectively) revealed a more severe effect than the individual treatments. This study's findings explain the association of heavy metal exposure with an increased rate of miscarriage/abortion incidences in highly polluted areas assisting in proper management and creating public awareness. [ABSTRACT FROM AUTHOR]

The Triplaris gardneriana Wedd. seeds extract has great therapeutic potential due to numerous biological activities such as antioxidant, antibacterial and anti-inflammatory, which are associated with phenolic content. Although this herbal preparation has shown many benefits, recently their toxicity profile has begun to be explored. In this present study, the toxic effects of T. gardneriana seeds ethanolic extract (EETg) on biological systems of different taxonomical groups and levels of complexity (from cell culture to lower vertebrates) were assessed, through a variety of viability and toxicological assays. It was found that EETg did not impair the Saccharomyces cerevisiae growth at the highest tested concentration (200 µg/mL), and no toxicant evidence was observed in Aedes aegypti larvae or in Drosophila melanogaster adult stage. Contrarily, the extract reduced the viability of undifferentiated Caco-2 cells (250 µg/mL, 40% of viable cells), but did not affect differentiated ones. The embryotoxicity in Danio rerio model showed a LC50 of 7.41 mg/L (95% confidence interval, 4.78 − 11.49 mg/L). EETg did not show signs of toxicity in the majority of the models used, but lethality and malformations in zebrafish embryos occurred. Further analyses are needed to better understand the selective toxicity mechanism of EETg on zebrafish, as well as whether the toxic effects happen in higher vertebrates. [ABSTRACT FROM AUTHOR]

1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) is a neurotoxin that damages dopaminergic neurons. Zebrafish has been shown to be a suitable model organism to investigate the molecular pathways in the pathogenesis of Parkinson's disease and also for potential therapeutic agent research. Boron has been shown to play an important role in the neural activity of the brain. Boronic acids are used in combinatorial approaches in drug design and discovery. The effect of 3-pyridinylboronic acid which is an important sub-class of heterocyclic boronic acids has not been evaluated in case of MPTP exposure in zebrafish embryos. Accordingly, this study was designed to investigate the effects of 3-pyridinylboronic acid on MPTP exposed zebrafish embryos focusing on the molecular pathways related to neurodegeneration and apoptosis by RT-PCR. Zebrafish embryos were exposed to MPTP (800 μM); MPTP + Low Dose 3-Pyridinylboronic acid (50 μM) (MPTP + LB) and MPTP + High Dose 3-Pyridinylboronic acid (100 μM) (MPTP + HB) in well plates for 72 hours post fertilization. Results of our study showed that MPTP induced a P53 dependent and Bax mediated apoptosis in zebrafish embryos and 3-pyridinylboronic acid restored the locomotor activity and gene expressions related to mitochondrial dysfunction and oxidative stress due to the deleterious effects of MPTP, in a dose-dependent manner. [ABSTRACT FROM AUTHOR]

Acetyl-11-keto-β-boswellic acid (AKBA), a triterpenoid from Boswellia serrate, is regarded as an angiogenesis inhibitor. However, its toxicity is unknown. The aim of this study was to examine its developmental toxicity and cardiotoxicity. A developmental toxicity assay in zebrafish embryos/larvae from 4 to 96 hours post-fertilization (hpf) was performed and a cardiotoxicity assay was designed from 48 to 72 hpf. Markers of oxidative stress and related genes were selected to access the possible mechanisms. According to the results, AKBA induced pericardium edema, yolk-sac edema, abnormal melanin, spinal curvature, hatching inhibition and shortened body length. Further, increased SV-BA distance, reduced heart rate, increased pericardium area and decreased blood flow velocity were detected in AKBA treated groups. The inhibition of cardiac progenitor gene expression, such as Nkx2.5 and Gata4, may be related to cardiotoxicity. The activities of antioxidant enzymes were decreased and the content of MDA was increased. In addition, AKBA treatment decreased the expression levels of Mn-Sod, Cat, and Gpx. These results suggested that AKBA induced developmental toxicity and cardiotoxicity through oxidative stress. As far as we know, this is the first report on the toxicity of AKBA. It reminds us to pay attention to developmental toxicity and cardiotoxicity of AKBA. [ABSTRACT FROM AUTHOR]

Aquilaria malaccensis has been traditionally used to treat several medical disorders including inflammation. However, the traditional claims of this plant as an anti-inflammatory agent has not been substantially evaluated using modern scientific techniques. The main objective of this study was to evaluate the anti-inflammatory effect of Aquilaria malacensis leaf extract (ALEX-M) and potentiate its activity through nano-encapsulation. The extract-loaded nanocapsules were fabricated using water-in-oil-inwater (w/o/w) emulsion method and characterized via multiple techniques including DLS, TEM, FTIR, and TGA. The toxicity and the anti-inflammatory activity of ALEX-M and the extract-loaded nanocapsules (ALEX-M-PNCs) were evaluated in-vitro on RAW 264.7 macrophages and in-vivo on zebrafish embryos. The nanocapsules demonstrated spherical shape with mean particle diameter of 167.13 ± 1.24 nm, narrow size distribution (PDI = 0.29 ± 0.01), and high encapsulation efficiency (87.36 ± 1.81%). ALEX-M demonstrated high viability at high concentrations in RAW 264.7 cells and zebrafish embryos, however, ALEX-M-PNCs showed relatively higher cytotoxicity. Both free and nanoencapsulated extract expressed anti-inflammatory effects through significant reduction of the proinflammatory mediator nitric oxide (NO) production in LPS/IFNc-stimulated RAW 264.7 macrophages and zebrafish embryos in a concentration-dependent manner. The findings highlight that ALEX-M can be recognized as a potential anti-inflammatory agent, and its anti-inflammatory activity can be potentiated by nano-encapsulation. Further studies are warranted toward investigation of the mechanistic and immunomodulatory roles of ALEX-M. [ABSTRACT FROM AUTHOR]

Processing with vinegar could enhance the efficacy and reduce the toxicity of Curcuma phaeocaulis Valeton. (Zingiberaceae), a Chinese herbal medicine with anti-inflammatory and antitumor activities. This study investigated the vinegar processing effects by evaluating anti-angiogenic effect and toxicity of C. phaeocaulis through zebrafish and rat models. Zebrafish embryos (AB and FLk-GFP strain) were applied to evaluate toxicity, cardiotoxicity and anti-angiogenic activity of volatile oil, and water decoction of the raw and vinegar-processed C. phaeocaulis. Meanwhile, a blood stasis syndrome rat model was applied to study the toxicity by measuring the ovarian and uterine coefficient. Curcuma phaeocaulis volatile oil and its vinegar-processed products in zebrafish had an LC50 of 67.315 and 95.755 μg/mL, respectively. Curcuma phaeocaulis water decoction and its vinegar-processed products had an LC50 of 161.440 and 206.239 μg/mL, respectively. The toxicity of vinegar-processed products was significantly lower than the raw, and the development characteristic of zebrafish embryos at different times confirmed these results. The volatile oil of vinegar-processed products could inhibit the growth of intersegmental blood vessels at the dose of 20 μg/mL, while the raw materials did not exhibit such effect at the same concentration. The rat experiment also confirmed that the volatile oil could reduce toxicity of ovarian and uterine. The study indicated that processing using vinegar could decrease toxicity and increase anti-angiogenic activity of C. phaeocaulis, which could be applied for clinical treatment. Further in-depth study on the synergism and detoxification mechanism of vinegar processing technology is needed. [ABSTRACT FROM AUTHOR]

4-methylimidazole (4-MEI), is received to humans through the foods and other sources. We have investigated neurobehavioral and developmental toxicity of 4-MEI in mother and offspring in mice. Results in vivo, showed that 4-MEI (100, 200 and 300 mg/kg) can induce neurobehavioral toxicity in pregnant mice by abnormalities in the hippocampus and disrupt neurobehavioral functions. Observation on fetuses showed that 4-MEI induces abortion, decrease the weight and length of the fetus and pathological abnormalities. These results suggested 4-MEI induces neurobehavioral and developmental toxicity. It is hoped that these results will be helpful for awareness of humans which are exposed with 4-MEI. [ABSTRACT FROM AUTHOR]

Laterality defects during embryonic development underlie the aetiology of various clinical symptoms of neuropathological and cardiovascular disorders; however, experimental approaches to understand the underlying mechanisms are limited due to the complex organ systems of vertebrate models. Zebrafish have the ability to survive even when the heart stops beating for a while during early embryonic development and those adults with cardiac abnormalities. Therefore, we induced laterality defects and investigated the occurrence of situs solitus, situs inversus, and situs ambiguus in zebrafish development. Histopathological analysis revealed heterotaxy in both embryos and juvenile fish. Additionally, randomization of left-right asymmetry of the brain and heart in individual zebrafish embryos under artificial experimental pressure further demonstrated the advantage of transparent zebrafish embryos as an experimental tool to select or reduce the embryos with laterality defects during early embryonic development for long-term studies, including behavioural and cognitive neuroscience investigations. [ABSTRACT FROM AUTHOR]

Diterpene alkaloids (DAs) have a broad spectrum of pharmacological activities, but exhibiting extremely serious cardiotoxicity to induce arrhythmia, heart arrest, even death. This study aimed to evaluate the cardiotoxicity of three diester diterpene alkaloids (DDAs) including aconitine (AC), mesaconitine (MAC), hypaconitine (HAC) and three monoester diterpene alkaloids (MDAs) including 14-α-benzoylaconine (BAC), 14-α-benzoylmesaconine (BMAC), 14-α-benzoylhypaconine (BHAC) on zebrafish. Firstly, the zebrafish embryos after a 72-hour post fertilization were treated with different doses of AC, MAC, HAC, and BAC, BMAC and BHAC for 2, 10 and 24 h, respectively. The heart rates of the treated embryos were calculated and the morphological images of body, together with heart fluorescence were obtained. Results demonstrated that AC, MAC, and HAC at low doses (15.6 and 31.3 μM) decreased the heart rates and increased them at high doses (62.5, 125, and 250 μM), while BAC, BMAC, and BHAC decreased the heart rates in the dose range of 31.3–250 μM, but the highest dose (500 μM) of BAC and BMAC increased the heart rates. In addition, AC, MAC, and HAC exhibited serious organic and functional toxicities, while BAC, BMAC, and BHAC did not. It could be induced that DDAs expressed stronger cardiotoxicities than MDAs, which might be due to that they were known as the Na+ channel activators and K+ channel inhibitors, respectively. The β-acetate at C-8 position, along with the protonated nitrogen on ring A of their chemical structures contributed more for their different cardiotoxicities. This is the first study on cardiotoxicity comparison of DAs, providing references for the rational and safe application of these compounds and some plant species containing them to reduce side effects while retaining therapeutic efficacy. [ABSTRACT FROM AUTHOR]

The possibility of employing computational approaches like nano-QSAR or nano-read-across to predict nanomaterial hazard is attractive from both a financial, and most importantly, where in vivo tests are required, ethical perspective. In the present work, we have employed advanced Machine Learning techniques, including stacked model ensembles, to create nano-QSAR tools for modeling the toxicity of metallic and metal oxide nanomaterials, both coated and uncoated and with a variety of different core compositions, tested at different dosage concentrations on embryonic zebrafish. Using both computed and experimental descriptors, we have identified a set of properties most relevant for the assessment of nanomaterial toxicity and successfully correlated these properties with the associated biological responses observed in zebrafish. Our findings suggest that for the group of metal and metal oxide nanomaterials, the core chemical composition, concentration and properties dependent upon nanomaterial surface and medium composition (such as zeta potential and agglomerate size) are significant factors influencing toxicity, albeit the ranking of different variables is sensitive to the exact analysis method and data modeled. Our generalized nano-QSAR ensemble models provide a promising framework for anticipating the toxicity potential of new nanomaterials and may contribute to the transition out of the animal testing paradigm. However, future experimental studies are required to generate comparable, similarly high quality data, using consistent protocols, for well characterized nanomaterials, as per the dataset modeled herein. This would enable the predictive power of our promising ensemble modeling approaches to be robustly assessed on large, diverse and truly external datasets. [ABSTRACT FROM AUTHOR]

α-Mangostin is a primary active compound found in mangosteen pericarp that has been used as a traditional medicine in Thailand and other countries in Southeast Asia. Since toxicological information is limited, developmental toxicity and transcriptional effects of α-mangostin during embryogenesis of zebrafish were studied. Zebrafish embryos were exposed to α-mangostin (up to 15 µmol/L) from 4 hours up to 72 the 50% lethal concentration was estimated as 6.9 ± 1.9 µmol/L. The compound induced developmental defects in zebrafish embryos/larvae, mainly consisting of truncated bodies, bent tails, blood clots, and pericardial and yolk edemas. α-Mangostin increased malformation in body shape and tail morphology. Additionally, the compound altered the transcriptional expression levels of genes correlated with oxidative stress, inflammation, apoptosis, and hematopoiesis. Further research will be necessary to evaluate if α-mangostin may cause developmental toxicity in other animals. [ABSTRACT FROM AUTHOR]

Perfluoroalkyl acids (PFAAs) are persistent environmental contaminants that are associated with various adverse health outcomes. Perfluorooctanoic acid (PFOA) is one of the most prominently detected PFAAs in the environment, which is now replaced with shorter chain carbon compounds including perfluorohexanoic acid (PFHxA) and perfluorobutyric acid (PFBA). The aim of this study was to compare the toxicity of four PFAAs as a function of chain length and head group (carboxylate versus sulfonate) with in vitro and in vivo zebrafish assessments, which were subsequently compared to other cell and aquatic models. Mortality rate increased with chain length (PFOA > PFHxA ≫ PFBA) in both whole embryo/larvae and embryonic cell models. The sulfonate group enhanced toxicity with perfluorobutane sulfonate (PFBS) showing higher toxicity than PFBA and PFHxA in both larvae and cells. Toxicity trends were similar among different aquatic models, but sensitivities varied. Discrepancies with other zebrafish studies were confirmed to be associated with a lack of neutralization of acidic pH of dosing solutions in these other investigations, demonstrating the need for rigor in reporting pH of exposure solutions in all experiments. The zebrafish embryonic cell line was also found to be similar to most other cell lines regardless of exposure length. Overall, results agree with findings in other cell lines and organisms where longer chain length and sulfonate group increase toxicity, except in investigations not neutralizing the exposure solutions for these acidic compounds. [ABSTRACT FROM AUTHOR]

The influence of the UV–Vis radiation on the toxicity of agomelatine, loxapine, clozapine and tiapride was studied. The phototransformation procedure was conducted with the use of simulated solar radiation. In the case of each compound irradiation time necessary to decompose half of the initial concentration was chosen. The embryotoxicity and acute toxicity were evaluated using zebrafish (Danio rerio) embryos and larvae. The mutagenicity assay was done with the use of a micro-plate Ames test. Generally, the embryotoxicity decreased after the irradiation procedure. The obtained results showed that tiapride is the least toxic compound to zebrafish, however, its toxicity toward larvae increases after the irradiation. Similarly, the mutagenic potential of the mixture of tiapride photoproducts is higher than in the case of parent compound. The phototransformation of loxapine resulted in the change of the acute toxicity profile and increased the rate of reverse mutations in the Ames test. Oppositely, the irradiation of agomelatine caused the decrease of mutagenic potential and acute toxicity was also lower in the postirradiated mixture. The phototransformation of clozapine did not alter the mutagenicity and decreased the acute toxicity to the zebrafish larvae. In silico calculations showed a satisfactory prediction ability in some instances, especially in the case of mutagenic potential of the tiapride phototransformation products. [ABSTRACT FROM AUTHOR]

We investigated a panel of 14 compounds belonging to the monothiocarbamate (MTC) and dithiocarbamate (DTC) series against the β-carbonic anhydrase 3 (β-CA3) of Mycobacterium tuberculosis (Mtb). We also evaluated all compounds for toxicity using 1–5-day post fertilisation zebrafish embryos. 11 out of the 14 investigated derivatives showed effective nanomolar or submicromolar in vitro inhibition against the β-CA3 (KIs 2.4–812.0 nM), and among them four DTCs of the series (8–10 and 12) showed very significant inhibition potencies with KIs between 2.4 and 43 nM. Out of 14 compounds screened for toxicity and safety 9 compounds showed no adverse phenotypic effects on the developing zebrafish larvae at five days of exposure. The results of in vitro inhibition and the toxicological evaluation of our study suggest that 5 compounds are suitable for further in vivo preclinical characterisation in zebrafish model. [ABSTRACT FROM AUTHOR]

Manufactured nanoparticles (NPs) can potentially cause negative effects on molecular (proteins and nucleic acids), subcellular, cellular, tissue, organ, and organism due to their unusual physicochemical characteristics. Ionizable NPs in water (e.g., Al2O3-NPs) may create toxic effects on aquatic animals. The present research determined the influences of Al2O3-NPs and appropriate concentrations of ionizing Al(III) using water-soluble AlCl3 in zebrafish larvae (72 h post-fertilization, Danio rerio) by analyzing transcriptional alterations of stress-associated genes (rad51, p53, mt2) with quantitative real-time PCR (qRT-PCR). In addition, genotoxic effects of Al(III) and Al2O3-NPs were evaluated. The lethal concentrations that cause death of 50% (LC50) of zebrafish larvae when exposed to 0–50 mg/l Al(III) and 0-500 mg/l Al2O3-NPs were 3.26 ± 0.38 and 130.19 ± 5.59 mg/l, respectively, for 96 h. A concentration-dependent increase was observed in the genotoxicity in cells of larvae exposed to Al(III) and Al2O3-NPs for 96 h. DNA damage was more severe in larvae exposed to Al(III) (41.0% tail) than that of Al2O3-NPs (21.8% tail). A complex induction of stress-associated genes was observed in fish and this induction was not directly related to the concentrations of Al(III) and Al2O3-NPs, although a significant induction was detected in mt2 gene of larvae exposed to Al(III) and Al2O3-NPs relative to control group. The induction levels of mt2 were 4.13 ± 0.1 and 2.13 ± 0.1-fold change (mean ± S.E.M.) in larvae at 15 mg/l of Al(III) and 100 mg/l of Al2O3-NP concentrations, respectively. [ABSTRACT FROM AUTHOR]

Okadaic acid-group (OA-group) is a set of lipophilic toxins produced only in seawater by species of the Dinophysis and Prorocentrum genera, and characterized globally by being associated with harmful algal blooms (HABs). The diarrhetic shellfish poisoning toxins okadaic acid (OA) and dinophysistoxin-1 (DTX-1) are the most prevalent toxic analogues making up the OA-group, which jeopardize environmental safety and human health through consumption of hydrobiological organisms contaminated with these toxins that produce diarrhetic shellfish poisoning (DSP) syndrome in humans. Consequently, a regulatory limit of 160 μg of OA-group/kg was established for marine resources (bivalves). The aim of this study was to investigate effects varying concentrations of 1–15 μg/ml OA or DTX-1 on toxicity, development, and oxidative damage in zebrafish larvae (Danio rerio). After determining the lethal concentration 50 (LC50) in zebrafish larvae of 10 and 7 μg/ml (24 h) and effective concentration 50 (EC50) of 8 and 6 μg/ml (24 h), different concentrations (5, 6.5, or 8 μg/ml of OA and 4, 4.5, or 6 μg/ml of DTX-1) were used to examine the effects of these toxins on oxidative damage to larvae at different time points between 24 and 120 hpf. Macroscopic evaluation during the exposure period showed alterations in zebrafish including pericardial edema, cyclopia, shortening in the anteroposterior axis, and developmental delay. The activity levels of biochemical biomarkers superoxide dismutase (SOD) and catalase (CAT) demonstrated a concentration-dependent decrease while glutathione peroxidase (GPx) and glutathione reductase (GR) were markedly elevated. In addition, increased levels of oxidative damage (malondialdehyde and carbonyl content) were detected following toxin exposure. Data demonstrate that high concentrations of OA and DTX-1produced pathological damage in the early stages of development <48 h post-fertilization (hpf) associated with oxidative damage. [ABSTRACT FROM AUTHOR]

Due to its fully sequenced genome, high genetic homology to humans, external fertilization, fast development, transparency of embryos, low cost and active reproduction, the zebrafish (Danio rerio) has become a novel promising model organism in biomedicine. Zebrafish are a useful tool in genetic and neuroscience research, including linking various genetic mutations to brain mechanisms using forward and reverse genetics. These approaches have produced novel models of rare genetic CNS disorders and common brain illnesses, such as addiction, aggression, anxiety and depression. Genetically modified zebrafish also foster neuroanatomical studies, manipulating neural circuits and linking them to different behaviors. Here, we discuss recent advances in neurogenetics of zebrafish, and evaluate their unique strengths, inherent limitations and the rapidly growing potential for elucidating the conserved roles of genes in neuropsychiatric disorders. [ABSTRACT FROM AUTHOR]

Pyraoxystrobin is a novel strobilurin fungicide that is widely used on many crops. The high log Kow of pyraoxystrobin implies that it tends to accumulate in aquatic organisms. This study optimized the sorbents of QuEChERS (quick, easy, cheap, effective, rugged, and safe) using 13C-labelled pyraoxystrobin as the internal standard (IS). It has been established a QuEChERS-LC-MS/MS IS method to study the bioconcentration and elimination of pyraoxystrobin in zebrafish (Danio rerio). The results indicated that the method had satisfactory linearity between 0.234 and 15 μg L−1 (R2 = 0.9996). The limits of detection (LOD) and quantification (LOQ) for pyraoxystrobin were 0.01 and 0.03 μg L−1, respectively. The LOQs of the method for water and zebrafish were 0.05 μg L−1 and 0.01 mg/kg, respectively. The mean recovery of pyraoxystrobin in zebrafish and water at fortification levels of 0.01–0.3 mg kg−1 and 0.05–1.5 μg L−1 ranged from 98.31 to 105.61% and 101.87 to 108.48%, respectively, with a % RSD (relative standard deviation) of 0.94–3.57%. The bioconcentration has been evaluated. The bioconcentration factors for pyraoxystrobin in zebrafish were 1,792 and 3,505 after exposure to 0.5 μg L−1 for 168 h and 0.05 μg L−1 for 216 h, respectively. The half-life of pyraoxystrobin in zebrafish was 9.0–9.5 d. [ABSTRACT FROM AUTHOR]

Ractopamine, a β-adrenergic receptor agonist, is commonly used as a repartitioning agent and growth promotor in animal agriculture. There is evidence that ractopamine can enter natural water sources from livestock wastes, at concentrations in the low ng/L range. Currently, aquatic toxicity data for ractopamine is scarce. Therefore, in two separate experiments Xenopus laevis tadpoles were exposed to ractopamine in tank water at concentrations ranging from 2 ng/L to 2.2 mg/L for up to 14 d utilizing FETAX methodology. No overt signs of toxicity were identified in measured endpoints including survival, growth, malformation, and developmental stage. Oral ractopamine exposure in mammals and fish is associated with cardiotoxicity, increased mortality, and physiological alterations; however, this study suggests that aqueous ractopamine is not a developmental toxicant or overtly toxic to amphibians at environmentally relevant concentrations. [ABSTRACT FROM AUTHOR]

The use of nanotechnology to enhance pesticide formulations holds the promise of reduced pesticide use, reduced mobility in soils, and overall improvements in agricultural practices while simultaneously maintaining yields. However, the toxicity of nano-enabled pesticides, including azoxystrobin (Az), has not been well studied compared with their conventional form. This study investigates both lethal and sub-lethal endpoints in zebrafish embryos up to 120 h post-fertilization (hpf) under either laboratory light or simulated UV light. The median lethal concentration (LC50) value of nano-enabled Az (nAz) was significantly lower than the conventional form (Az). Interestingly, artificial UV light significantly increased toxicity (decreased LC50) of both Az and nAz. Malformations were not observed but the remaining yolk sac volume was significantly increased in both types of Az at both light conditions. This decreased yolk consumption is in agreement with reduced oxygen consumption and heart rate. Catalase enzyme activity was only reduced to UV light while superoxide dismutase activity was significantly reduced by co-exposure of UV light, and either type of Az at a nominal concentration of 100 μg L−1. The co-exposure of Az at 100 μg L−1 and UV light significantly upregulated sod1, sod2, and gpx1b expression and both types of Az significantly reduced gpx1a expression. Lipid peroxidation was significantly increased in nAz and Az at 100 μg L−1 under laboratory light, while UV light induced even higher level of lipid peroxidation. The results will provide important information on the toxicity of nAz under ecologically realistic conditions. [ABSTRACT FROM AUTHOR]

Anxiety is a fear-like response to stimuli perceived to be threatening. Excessive or uncontrollable anxiety is a debilitating psychiatric disorder which affects many people throughout their lifetime. In unravelling the complex genetic and environmental regulations of anxiety-like phenotypes, models measuring the natural dark avoidance of larval zebrafish have shed light on the individual variation and heritability of this anxiety-related trait. Using the light/dark choice paradigm and selective breeding, this study aims to validate previous findings of the variable (VDA) and strong dark aversion (SDA) heritability in AB-WT larval zebrafish using the outbred zebrafish strain EK, which offers more genetic diversity to aid in future molecular mapping efforts. 190 larvae (6 days post fertilization [dpf] and 7 dpf) were tested across four trials and divided into variable (VDA), medium (MDA) and strong (SDA) dark aversion for further in-crosses. VDA and MDA larvae became more explorative with time, whereas SDA larvae rarely left the preferred light zone. The SDA and VDA in-crosses significantly increased the respective phenotypes in the second generation of larvae, whereas VDA × MDA inter-crosses did not. For the second-generation SDA cohort, dark aversion correlated with increased thigmotaxis, which reinforces SDA as an anxiety-like phenotype. Our finding that the dark aversion trait and SDA and VDA phenotypes are heritable in an outbred zebrafish population lays an important foundation for future studies of genetic underpinnings using whole-genome mapping methods. This conserved fear/anxiety-like response in a highly accessible model organism also allows for further pharmacological and behavioral studies to elucidate the etiology of anxiety and the search for novel therapeutics for anxiety disorders. [ABSTRACT FROM AUTHOR]

Context: Oridonin, isolated from the leaves of Isodon rubescens (Hemsl.) H.Hara (Lamiaceae), has good antitumor activity. However, its safety in vivo is still unclear. Objective: To investigate the preliminary safety of oridonin in zebrafish. Materials and methods: Embryo, larvae and adult zebrafish (n = 40) were used. Low, medium and high oridonin concentrations (100, 200 and 400 mg/L for embryo; 150, 300 and 600 mg/L for larvae; 200, 400 and 800 mg/L for adult zebrafish) and blank samples were administered. At specific stages of zebrafish development, spontaneous movement, heartbeat, hatching rate, etc., were recorded to assess the developmental effects of oridonin. VEGFA, VEGFR2 and VEGFR3 gene expression were also examined. Results: Low-dose oridonin increased spontaneous movement and hatching rate with median effective doses (ED50) of 115.17 mg/L at 24 h post-fertilization (hpf) and 188.59 mg/L at 54 hpf, but these values decreased at high doses with half maximal inhibitory concentrations (IC50) of 209.11 and 607.84 mg/L. Oridonin decreased heartbeat with IC50 of 285.76 mg/L at 48 hpf, and induced malformation at 120 hpf with half maximal effective concentration (EC50) of 411.94 mg/L. Oridonin also decreased body length with IC50 of 324.78 mg/L at 144 hpf, and increased swimming speed with ED50 of 190.98 mg/L at 120 hpf. The effects of oridonin on zebrafish embryo development may be attributed to the downregulation of VEGFR3 gene expression. Discussions and conclusions: Oridonin showed adverse effects at early stages of zebrafish development. We will perform additional studies on mechanism of oridonin based on VEGFR3. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the antioxidant and anti-inflammatory potential of liposomal formulations enriched with Hypericum hookerianum (Hyp) aqueous extracts. Cotyledon segments derived from protocorms of H. hookerianum were cultured on Murashige and Skoog (MS) media supplemented with Kinetin (KN, 1 mgl−1) and Naphthalene acetic acid (NAA, 0.1 mgl−1) to induce hypericin-rich red shoots (HypR, 0.87 mg/G DW). Highly stable liposomes (−29.4 mV) were successfully developed which encapsulated 63 ± 0.8% Hyp extracts, respectively. MTT assay subsequently confirmed the biocompatibility of liposome compositions using fibroblast cell lines. This work also evaluated acute toxicity of L-HypR and L-HypG formulations using Danio rerio (Zebrafish) embryos for 96 hpf. The expression of antioxidant and anti-inflammatory genes were found to be upregulated for L-HypR than L-HypG (green shoots without hypericin) formulations. These properties of L-HypR may be extremely useful for incorporating lipophilic substances into the food or pharmaceutical industry. [ABSTRACT FROM AUTHOR]

The human cancer cell xenograft in zebrafish embryos has become a very useful preclinical tool in oncology research. While many anticancer drugs have been assayed with this model, few studies regarding the toxicity limits of these drugs for the host have been addressed. Here, we evaluated the acute toxicity of five approved and routinely used human anticancer drugs embracing different mechanism action types: Carboplatin (CarboPt), Irinotecan (IT), Doxorubicin (DOX), Paclitaxel (PT) and Chloroquine (CQ). They were tested in zebrafish embryos using the Fish Embryo Acute Toxicity (FET) test at 0 and 72 hours per fertilization (hpf). Additionally, we compared those results with in vitro toxicity assays and could find notable differences between both models. Our results indicate that the toxicity data of a compound evaluated in vitro and in a FET test at 0 hpf do not guarantee a reliable toxicity determination for performing xenografts in zebrafish, being necessary additional toxicity studies using 72 hpf embryos, the starting point of drug treatment in this kind of preclinical assays. [ABSTRACT FROM AUTHOR]

Important questions raised in (nano)ecotoxicology are whether biodistribution of nanoparticles (NPs) is affected by particle shape and to what extent local adverse responses are subsequently initiated. For nanomedicine, these same questions become important when the labeled NPs lose the labeling. In this study, we investigated the biodistribution patterns of gold nanoparticles (AuNPs) as well as immune-related local and systemic sublethal markers of exposure and behavioral assessment. Hatched zebrafish embryos were exposed to four differently shaped non-coated AuNPs with comparable sizes: nanospheres, nanorods, nano-urchins, and nano-bipyramids. Shape-dependent trafficking of the particles resulted in a different distribution of the particles over the target organs. The differences across the distribution patterns indicate that the particles behave slightly different, although they eventually reach the same target organs – yet in different ratios. Mainly local induction of the immune system was observed, whereas systemic immune responses were not clearly visible. Macrophages were found to take AuNPs from the body fluid, be transferred into the veins and transported to digestive organs for clearance. No significant behavioral toxicological responses in zebrafish embryos were observed after exposure. The trafficking of the particles in the macrophages indicates that the particles are removed via the mononuclear phagocytic system. The different ratios in which the particles are distributed over the target organs indicate that the shape influences their behavior and eventually possibly the toxicity of the particles. The observed shape-dependent biodistribution patterns might be beneficial for shape-specific targeting in nanomedicine and stress the importance of incorporating shape-features in nanosafety assessment. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) are a class of industrial chemicals that cause endocrine changes, since they are able to bind to estrogen receptors and interfere with estrogen-regulated processes, such as fish vitellogenesis. Therefore, the present work aimed to assess potential endocrine effects of PCB-77 exposure during zebrafish (Danio rerio) gonadal differentiation. To achieve that, zebrafish juveniles were exposed to increasing concentrations of PCB-77 for 14 days during a critical window of gonad differentiation (30–44 days post-fertilization). Vitellogenin (Vtg) levels and several endpoints such as survival, growth, gonadosomatic index (GSI) and hepatosomatic index were recorded at the end of exposure and/or after 3 months in clean medium. The results obtained showed a reduction of Vtg-like proteins in juveniles, just after exposure to PCB-77 accompanied, after 3 months, by a decrease in gonadal Vtg levels and GSI of females. These results suggest that exposure to PCB-77 during the critical window of gonadal differentiation decreased vitellogenesis in juvenile zebrafish which lasted until adulthood affecting the normal development of female gonad, which might have further implications in reproduction success. [ABSTRACT FROM AUTHOR]

Over the years, the potential toxicity of anesthetics has raised serious concerns about its safe use during pregnancy. As evidence emerged from research in animal models, showing that some anesthetic drugs are potential teratogenic, the determination of the risk of exposures to anesthetic drugs at early life stages became mandatory. However, due to inaccessibility and ethical constrains related to experimental conditions, the use of early life stages in mammalian models is limited. In this regard, some animal and nonanimal models have been suggested to surpass mammalian use in experimentation. Among them, the zebrafish embryo test has been recognized as a promising alternative in toxicology research, as well as an inexpensive and practical test. Substantial information collected from developmental research following compounds exposure, has contributed to the application of zebrafish assays in research, although only a few studies have focused on the use of early life stages of zebrafish to evaluate the developmental effects of anesthetics. Based on the recent advances of science and technology, there is a clear potential for zebrafish early life stages to provide new insights into anesthetics teratogenicity. This review provides an overview of recent anesthesia research using zebrafish embryos, demonstrating its usefulness to the anesthesia field, discussing the recent findings on various aspects related to the effects of anesthetics during early life development and the strengths and limitations of this model system. [ABSTRACT FROM AUTHOR]

Addition of capping agents like surfactants and polymers during the synthesis of nanoparticles may affect the stability and toxicity of dispersions of nanoparticles. This study revealed the impact of anionic, cationic, and amphoteric surfactants and a cationic polymer on the physical and chemical properties, stability and behavior of silver nanomaterials, as well as on the toxicity of nanosized silver particles with respect to zebrafish embryos. Some of the stabilizers applied were shown to significantly affect embryos of Danio rerio. Colloidal dispersions of stabilized silver nanoparticles were demonstrated to induce a complex mechanism of toxicity with respect to embryos of D. rerio, which is mainly explained by the toxicity of the organic ligand, while other parameters are somewhat inferior. The newly generated data on the toxicity of nanoparticles and their stabilizers with respect to D. rerio embryos reveal the complexity of the toxicity mechanism of nanoparticles impacting living systems. [ABSTRACT FROM AUTHOR]

Carbonic anhydrase (CA) IX is a hypoxia inducible enzyme that is highly expressed in solid tumours. Therefore, it has been considered as an anticancer target using specific chemical inhibitors. The nitroimidazoles DTP338 and DTP348 have been shown to inhibit CA IX in nanomolar range in vitro and reduce extracellular acidification in hypoxia, and impair tumour growth. We screened these compounds for toxicity using zebrafish embryos and measured their in vivo effects on human CA IX in Xenopus oocytes. In the toxicity screening, the LD50 for both compounds was 3.5 mM. Neither compound showed apparent toxicity below 300 µM concentration. Above this concentration, both compounds altered the movement of zebrafish larvae. The IC50 was 0.14 ± 0.02 µM for DTP338 and 19.26 ± 1.97 µM for DTP348, suggesting that these compounds efficiently inhibit CA IX in vivo. Our results suggest that these compounds can be developed as drugs for cancer therapy. [ABSTRACT FROM AUTHOR]

Zebrafish early life stages were found to be sensitive to several synthetic dyes widely used in industries. However, as environmental concentrations of such contaminants are often at sublethal levels, more sensitive methods are required to determine early-warning adverse consequences. The aim of this study was to utilize a multibiomarker approach to examine underlying oxidative stress mechanisms triggered by sublethal concentrations of synthetic azo dye Basic Red 51 (BR51), the natural dye erythrostominone (ERY), and its light-degraded product using zebrafish embryos. Biochemical biomarkers included parameters of detoxification and markers of antioxidant system, as well as oxidative damage. Results showed pro-oxidant mechanisms attributed to BR51 and ERY as evidenced by increased glutathione S-transferase (GST) activity, a phase II detoxification enzyme related to reactive oxygen species detoxification. BR51 also elevated total glutathione (GSH+GSSG) levels and catalase activity. However, both dyes induced oxidative damage as evidenced by elevated lipid peroxidation content. In contrast, when the natural dye was photodegraded, no marked effects were observed for all biomarkers assessed. Data indicate that such dyes are pro-oxidants at sublethal concentrations, predominantly involving GSH and/or related enzymes pathway. [ABSTRACT FROM PUBLISHER]

The toxic effects of two recently discovered inhibitors (VD12-09andVD11-4-2) that selectively and with extraordinary strong, picomolar binding affinity to human carbonic anhydrase (CA) isoform IX were investigated on zebrafish embryonic development. CA IX has been recently introduced as an anticancer target since it is highly overexpressed in numerous human cancers but nearly absent in normal tissues. Morphological changes in zebrafish treated by the compounds were studied by light-field microscopy and histological analysis. Homology models of zebrafish CA II and CA IX were built to identify the conserved amino acid residues in the active site of zebrafish CAs. The toxicity studies here showed that the LC50values at 120 hours post-fertilization (hpf) were 13  μM forVD12-09, 120  μM forVD11-4-2,and 9  μM for ethoxzolamide (EZA), a non-selective CA inhibitor commonly used as a drug in clinics. Thus,EZAwas the most toxic of the three compounds. The zebrafish embryos exposed to LC50doses ofVD12-09andVD11-4-2showed fewer phenotypic abnormalities compared with the embryos exposed to the corresponding dose ofEZA. Histochemical studies did not show any gross morphological changes in the embryos treated withVD12-09andVD11-4-2unlikeEZA. The results of our study indicate that the compounds exhibited 10-fold lower toxicity and induced fewer side effects in zebrafish thanEZA. Therefore, the exposure toVD11-4-2andVD12-09at concentrations below LC50did not lead to deleterious effects on the zebrafish embryonic development and thus both inhibitors may be further developed as drugs. [ABSTRACT FROM PUBLISHER]

Fish lineage-specific gene,sinup[Siaz-interacting nuclear protein], modulates neural plate formation in embryogenesis and shares homology with human TPX2 protein, a member of the vertebrate mitogen-activating protein family. In spite of the presence of the TPX2 domain in Sinup, its cellular function has been unknown. As an initial approach to this question, we expressed Sinup by injectingsinup-EGFPmRNAs into zebrafish embryos at the one- to two-cell stage. First of all, Sinup-EGFP was associated with centrosomes and mitotic spindles. In particular, Sinup was localized to the spindle poles and midbody microtubules during the period between anaphase and cytokinesis. Second, various deleted mutants of Sinup-EGFP failed to be associated with the centrosomes and mitotic spindles. Third, a Sinup mutant, where the 144th Serine residue was converted to alanine, not only disturbed the mitotic spindle organization, such as multipolar spindles, fragmented spindle poles, and flattened spindles, but also arrested the cell cycle at metaphase and cell movement. Finally, Sinup is phosphorylated by Aurora A and the 144th Serine mutant of Sinup is partially phosphorylated by Aurora A kinase. We thus propose that Sinup is an essential element for the integrity of centrosomes and mitotic spindle fibers as well as for the normal process of cell cycle and cellular movement in vertebrate embryos. [ABSTRACT FROM PUBLISHER]

Inhibition of novel biological pathways inMycobacterium tuberculosis(Mtb) creates the potential for alternative approaches for treating drug-resistant tuberculosis.In vitrostudies have shown that dithiocarbamate-derived β-carbonic anhydrase (β-CA) inhibitors Fc14–594 A and Fc14–584B effectively inhibit the activity of Mtb β-CA enzymes. We screened the dithiocarbamates for toxicity, and studied thein vivoinhibitory effect of the least toxic inhibitor onM. marinumin a zebrafish model. In our toxicity screening, Fc14–584B emerged as the least toxic and showed minimal toxicity in 5-day-old larvae at 300 µM concentration.In vitroinhibition ofM. marinumshowed that both compounds inhibited growth at a concentration of 75 µM.In vivoinhibition studies using 300 µM Fc14–584B showed significant (p > .05) impairment of bacterial growth in zebrafish larvae at 6 days post infection. Our studies highlight the therapeutic potential of Fc14–584B as a β-CA inhibitor against Mtb, and that dithiocarbamate compounds may be developed into potent anti-tuberculosis drugs. [ABSTRACT FROM PUBLISHER]

G-quadruplexes are non-canonical DNA secondary structures involved in several genomic and molecular processes. Here, we summarize the main G-quadruplex features and evidences proving thein vivorole on the transcriptional regulation of genes required for zebrafish embryonic development. We also discuss alternative strategies for specifically interfering G-quadruplexin vivo. [ABSTRACT FROM AUTHOR]

Our work aimed to elucidate the ultrastructural changes associated with brain neurons in wild-type zebrafish embryos exposed to different concentrations of methylmercury. Zebrafish embryos were exposed to one of five concentrations of methylmercury (0 [negative control], 5, 10, 50, and 80 parts per billion) starting at six hours post fertilization (hpf). At 96 hpf, cells in the zebrafish embryo brains were examined using transmission electron microscopy. The developing neurons of the control embryos sowed normal cellular ultrastructure. Few alterations were observed among the neurons of zebrafish embryos exposed to 5 ppb methylmercury. The cells of the embryos exposed to 10 ppb methylmercury showed slight cellular degeneration as demonstrated by the accumulation of electron dens bodies which were presumably lysosomes in different stages of formation. In embryos exposed to 50 ppb methylmercury, the neuronal cytoplasm conained large electron dense lysosomes and the rough endoplasmic reticulum appeared to be reduced and irregular in shape. Furthermore, the embryonic brain neurons exposed to 80 ppb methylmercury showed the most severe ultrastructural changes, including some that were consistent with different stages of the cell death process. Obvious cellular changes were observed in this highest exposure group included: disrupted or degenerating nuclei; fragmentation or vacuolization of mitochondrial cristae; and loss of mitochondrial matrix density. Based on these observations, we conclude that these different morphological patterns of cellular changes may reflect either different stages of the cell death process or different types of cell death due to 24 hours of exposure to 80 ppb methylmercury. [ABSTRACT FROM PUBLISHER]

The purpose of this study was to investigate the efficacy of UV-C direct photolysis of bisphenol A (BPA) as a remediation method of BPA contamination. We used zebrafish embryos as a model organism to test the toxicity and residual biological activity by measuring cytochrome P4501A1 (CYP1A), aromatase B (Aro B) and heat shock proteins (HSP-70) transcript levels. The mRNA levels of CYP1A gene increased about two fold while exposure of zebrafish embryos at 72 hpf resulted in significant induction (P= 0.048) of Aro B at 100 µg/L of BPA. Exposure of zebrafish embryos at 72 hpf to increasing concentrations of BPA resulted in significant induction (P= 0.0031) of HSP-70 transcript level. UV treatment of BPA resulted in a significant reduction in toxicity by reducing mortality of zebrafish embryos. The results suggest that UV-C direct photolysis may be an effective method for remediation of BPA contamination. Further studies will be necessary for better understanding of the identity and relative activity of the UV degradation by-products. [ABSTRACT FROM AUTHOR]

Apoptosis is an integral element of development that may also be initiated by environmental contaminants. The aim of the present study was to assess potential changes in the regulation of apoptotic genes in zebrafish embryos following parental exposure to two natural mixtures of persistent organic pollutants (POP). The mixture from Lake Mjøsa contained exceptionally high concentrations of polybrominated diphenyl ethers (PBDE), as well as relatively high levels of polychlorinated biphenyls (PCB) and dichlorodiphenyltrichloroethane (DDT). The mixture from Lake Losna contained background concentrations of POP. Genes involved in the apoptotic machinery were screened for their expression profile at four time points during embryonic development. Thirteen and 15 genes involved in apoptosis were found to be significantly upregulated in the high-exposure and background exposure groups, respectively, compared with controls. Modulation of apoptotic genes was restricted only to the first time point, which corresponds with the blastula stage. Although there were substantial differences in POP concentrations between mixtures, genes underlying the apoptosis process showed almost similar responses to the two mixtures. In both exposure groups the main executors of apoptosis p53, casp 2, casp 6, cassp 8, and BAX displayed upregulation compared to controls, suggesting that these POP induce apoptosis via a p53-dependent mechanism. Upregulation of genes that play a critical role in apoptosis suggests that disturbance of normal apoptotic signaling during gametogenesis and embryogenesis may be one of the central mechanisms involved in adverse reproductive effects produced by POP in zebrafish. [ABSTRACT FROM PUBLISHER]

Selenium acts as an important element in the prevention and treatment of cardiovascular diseases but their health-related effects have not been fully explored. As a novel attempt, zebrafish embryos were treated separately with SeNPs (5–25 μg/ml) and sodium selenite (5–25 μg/ml) starting at early blastula stage. Abnormalities were also observed in the morphology of the zebrafish embryos. The SeNPs-treated embryos exhibited concentration-dependent increased in mortality, pericardial edema, and cardiac arrhythmia. In contrast, sodium selenite showed no significant malformation effect in developing zebrafish embryos. The results of the present study conclude that the SeNPs were more toxic than sodium selenite. The results also suggest that lower concentrations of SeNPs and sodium selenite can be used as possible therapeutic agents for cardiovascular-related problems. [ABSTRACT FROM AUTHOR]

Very long chain fatty acids are required for sphingolipid synthesis, lipid homeostasis, myelin formation, epidermal permeability, and retinal function. Seven different enzymes are known to be involved in the elongation cycle of fatty acids, with different chain-length specificities. Elovl1 is one of those enzymes whose function has been linked mainly to the synthesis of sphingolipids and the epidermal barrier. However, the role of Elovl1 in organogenesis is not clear. In zebrafish, 2 Elovl1 genes, elovl1a and elovl1b, are highly expressed in the swim bladder, and elovl1b is also expressed in the kidney. We found that both elovl1 knockdown embryos contain increased levels of long chain fatty acids from carbon number 14 to 20 as compared to control embryos. Oil-Red-O staining shows that yolk lipid consumption is greatly reduced, whereas lipid droplets accumulate within the swim bladder. Notably, knockdown of either elovl1a or elovl1b affects the expression of genes involved in swim bladder development and impairs inflation of the swim bladder. Consistent with its expression in the pronephros, knockdown of elovl1b alone affects the expression of genes required for kidney development and reduces renal clearance. Our findings strongly suggest that both elovl1 genes are a key determinant of swim bladder and kidney development in zebrafish, which may be comparatively applicable to lung and kidney development in humans. [ABSTRACT FROM AUTHOR]

Endosulfan has been listed as a persistent organic pollutant, and is frequently found in agricultural environments during monitoring processes owing to its heavy use and persistent characteristics. This study was conducted to understand the effects of endosulfan on the development of zebrafish (Danio rerio) embryos by exposing them to a specific range of endosulfan concentrations. Exposing zebrafish embryos to endosulfan for 96 h yielded no acute toxicity until the concentration reached 1500 µg L-1, whereas malformed zebrafish larvae developed severely curved spines and shortened tails. About 50% of zebrafish larvae were malformed when exposed to 600 µg L-1 of endosulfan. Comparative gene expression using realtime quantitative polymerase chain reaction was assessed using endosulfan-exposed zebrafish embryos. CYP1A and CYP3A were significantly enhanced in response to endosulfan treatment. Two genes, acacb and fasn, encoding acetyl-CoA carboxylase b and fatty acid synthase proteins, respectively, were also up-regulated after treating zebrafish embryos with endosulfan. These genes are also involved in fatty acid biosynthesis. The genes encoding vitellogenin and Hsp70 increased in a concentration-dependent manner in embryos. Finally, biochemical studies showed that acetylcholinesterase activity was reduced, whereas glutathione S-transferase and carboxylesterase activities were enhanced in zebrafish embryos after endosulfan treatment. These biochemical and molecular biological differences might be used for tools to determine contamination of endosulfan in the aquatic environment. [ABSTRACT FROM AUTHOR]

The production of titanium dioxide nanoparticles (TiO2 NPs) for commercial applications has greatly increased over the last years and consequently the potential risk for human health. There is a growing awareness of the need to understand the behavior and influence these nanoparticles exert on the environment. Bioaccumulation serves as a good integrator to assess chemical exposure in aquatic systems and is dependent on factors, such as the exposure routes, diet and the aqueous medium. We analyzed the experimental bioaccumulation capability of ionic titanium and TiO2 NPs by zebrafish (Danio rerio) eleutheroembryos through bioconcentration factors (BCFs), after 48 or 72 h of exposure. The stability of both chemical forms in an aquatic medium was fully characterized for further bioaccumulation studies. Several stabilizing agents (humic acids, soluble starch, polyethylene glycol, Na4P2O7 and Na2HPO4) for anatase and rutile, the two allotrophs of TiO2 NPs, were evaluated to check the evolution of the aggregation process. Around 60% of TiO2 NPs remained disaggregated under simulated environmental conditions with the addition of 50 mg L−1 of humic acids. However, the presence of eleutheroembryos in the exposure medium increased TiO2 NPs aggregation in the experimental tests. The BCFs values obtained in all cases were <100, which classifies ionic titanium and TiO2 NPs as non-bioaccumulative substances, under the REACH regulations. [ABSTRACT FROM AUTHOR]

Nucleoporin p62 (Nup62) localizes in the central channel of nuclear pore complexes (NPCs) and regulates nuclear pore permeability and nucleocytoplasmic transport. However, the developmental roles of Nup62 in vertebrates remain largely unclear. Zebrafish Nup62-like protein (Nup62l) is a homolog of mammalian Nup62. The nup62l gene is maternally expressed, but its transcripts are ubiquitously distributed during early embryogenesis and enriched in the head, pharynx, and intestine of developing embryos. Activation of the Wnt/β-catenin pathway positively modulates nup62l transcription, while Bmp signaling acts downstream of Wnt/β-catenin signaling to negatively regulate nup62l expression. Overexpression of nup62l dorsalized embryos and enhanced gastrula convergence and extension (CE) movements. In contrast, knockdown of Nup62l led to ventralized embryos, an impediment to CE movements, and defects in specification of midline organ progenitors. Mechanistically, Nup62l acts as an activator of Wnt/β-catenin signaling through interaction with and facilitation of nuclear import of β-catenin-1/2 in zebrafish. Thus, Nup62l regulates dorsoventral patterning, gastrula CE movements, and proper specification of midline organ precursors through mediating the nuclear import of β-catenins in zebrafish. [ABSTRACT FROM AUTHOR]

The ten-eleven translocation 2 gene (TET2) encodes a member of the TET family of DNA methylcytosine oxidases that converts 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) to initiate the demethylation of DNA within genomic CpG islands. Somatic loss-of-function mutations of TET2 are frequently observed in human myelodysplastic syndrome (MDS), which is a clonal malignancy characterized by dysplastic changes of developing blood cell progenitors, leading to ineffective hematopoiesis. We used genome-editing technology to disrupt the zebrafish Tet2 catalytic domain. tet2m/m (homozygous for the mutation) zebrafish exhibited normal embryonic and larval hematopoiesis but developed progressive clonal myelodysplasia as they aged, culminating in myelodysplastic syndromes (MDS) at 24 months of age, with dysplasia of myeloid progenitor cells and anemia with abnormal circulating erythrocytes. The resultant tet2m/m mutant zebrafish lines show decreased levels of 5hmC in hematopoietic cells of the kidney marrow but not in other cell types, most likely reflecting the ability of other Tet family members to provide this enzymatic activity in nonhematopoietic tissues but not in hematopoietic cells. tet2m/m zebrafish are viable and fertile, providing an ideal model to dissect altered pathways in hematopoietic cells and, for small-molecule screens in embryos, to identify compounds with specific activity against tet2 mutant cells. [ABSTRACT FROM AUTHOR]

In many animals, factors deposited by the mother into the egg control the earliest events in development of the zygote. These maternal RNAs and proteins play critical roles in oocyte development and the earliest steps of embryogenesis such as fertilization, cell division and embryonic patterning. Here, this article summarizes recent discoveries made on the maternal control of germline specification in zebrafish. Moreover, this review will discuss the major gaps remaining in our understanding of this process and highlight recent technical innovations in zebrafish, which allow tackling some of these questions in the near future. [ABSTRACT FROM AUTHOR]

Purpose: The in vivo radiation-induced bystander effect (RIBE) and radiation-induced rescue effect (RIRE) induced between embryos of the zebrafish ( Danio rerio) by alpha-particle irradiation were studied through the number of apoptotic signals revealed at 24 h post fertilization (hpf) through vital dye acridine orange staining. Materials and methods: RIBE and RIRE were verified through the significant increase and decrease in apoptotic signals in the partnered bystander and irradiated embryos, respectively. Results: The medium transfer experiment where irradiated zebrafish embryos were rescued through immersion in the medium previously conditioned by a larger number of irradiated zebrafish embryos showed (a) the involvement of a released stress signal in the induction of RIRE, and (b) RIBE and RIRE signals had the same function. With the help of 500 μM of the specific nitric oxide (NO) scavenger cPTIO (2-(4carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide), NO was confirmed as an essential signaling molecule for inducing both the RIBE and RIRE. On the other hand, the treatment with 20 μM of the carbon monoxide (CO) releasing chemical CORM-3 (tricarbonylchloro(glycinato)ruthenium (II)) suppressed the manifestations of RIBE but did not suppress RIRE. Conclusions: In conclusion, unirradiated zebrafish embryos need NO but not NO-induced damages to rescue α-particle irradiated zebrafish embryos. [ABSTRACT FROM AUTHOR]

Septins are conserved filament-forming GTP-binding proteins that act as cellular scaffolds or diffusion barriers in a number of cellular processes. However, the role of septins in vertebrate development remains relatively obscure. Here, we show that zebrafish septin 6 (sept6) is first expressed in the notochord and then in nearly all of the ciliary organs, including Kupffer's vesicle (KV), the pronephros, eye, olfactory bulb, and neural tube. Knockdown of sept6 in zebrafish embryos results in reduced numbers and length of cilia in KV. Consequently, cilium-related functions, such as the left-right patterning of internal organs and nodal/spaw signaling, are compromised. Knockdown of sept6 also results in aberrant cilium formation in the pronephros and neural tube, leading to cilium-related defects in pronephros development and Sonic hedgehog (Shh) signaling. We further demonstrate that SEPT6 associates with acetylated α-tubulin in vivo and localizes along the axoneme in the cilia of zebrafish pronephric duct cells as well as cultured ZF4 cells. Our study reveals a novel role of sept6 in ciliogenesis during early embryonic development in zebrafish. [ABSTRACT FROM AUTHOR]