Zebrafish as anIn VivoHigh-Throughput Model for Genotoxicity

Cytotoxic and genotoxic effects induced by associated commercial glyphosate and 2,4-D formulations using the Allium cepa bioassay

Studies assessing the toxicity of glyphosate and 2,4-dichlorophenoxyacetic acid mixture are scarce. The aim of this study was to evaluate the cytotoxicity and genotoxicity of the mixture of these herbicides using Allium cepa. Roots were exposed to glyphosate (1.56 and 11.66 mg mL-1), 2,4-D (0.28 and 17.5 mg mL-1) and mixture for 24 h, based on the average concentration applied in the field and the acute reference dose (ARfD) established in Brazil. Both isolated and associated herbicides induced a significative decrease in mitotic index (MI) (P < 0.0001) in all tested concentrations. Regarding the genotoxicity results, 2,4-D and the mixture showed, at concentrations applied in the field, a significative increase of chromosomal anomalies (CA) index compared to control (P < 0.0001) and glyphosate (P = 0.024 and P = 0.0002, respectively). All tested groups from the ARfD showed a significative difference compared to the control group (P < 0.0001), as well as glyphosate and 2,4-D isolated compared to the mixture (P = 0.0005 and P < 0.0001, respectively). The most observed CA were apoptotic bodies, giant cells, and nuclear erosions. We emphasize the need for further studies assessing the toxicity of these herbicides' mixture due to the distinct effects caused in different organisms.

The zebrafish embryo as an in vivo model for screening nanoparticle-formulated lipophilic anti-tuberculosis compounds

With the increasing emergence of drug-resistant Mycobacterium tuberculosis strains, new and effective antibiotics against tuberculosis (TB) are urgently needed. However, the high frequency of poorly water-soluble compounds among hits in high-throughput drug screening campaigns is a major obstacle in drug discovery. Moreover, in vivo testing using conventional animal TB models, such as mice, is time consuming and costly, and represents a major bottleneck in lead compound discovery and development. Here, we report the use of the zebrafish embryo TB model for evaluating the in vivo toxicity and efficacy of five poorly water-soluble nitronaphthofuran derivatives, which were recently identified as possessing anti-TB activity in vitro. To aid solubilization, compounds were formulated in biocompatible polymeric micelles (PMs). Three of the five PM-formulated nitronaphthofuran derivatives showed low toxicity in vivo, significantly reduced bacterial burden and improved survival in infected zebrafish embryos. We propose the zebrafish embryo TB-model as a quick and sensitive tool for evaluating the in vivo toxicity and efficacy of new anti-TB compounds during early stages of drug development. Thus, this model is well suited for pinpointing promising compounds for further development.

Micronucleus test and nuclear abnormality assay in zebrafish (Danio rerio): Past, present, and future trends

Nuclear abnormality (NA) assay in fish has been widely applied for toxicity risk assessment under field and laboratory conditions. The zebrafish (Danio rerio) has become a suitable model system for assessing the NA induced by pollutants. Thus, the current study aimed to summarize and discuss the literature concerning micronucleus (MN) and other NA in zebrafish and its applications in toxicity screening and environmental risk assessment. The data concerning the publication year, pollutant type, experimental design, and type of NA induced by pollutants were summarized. Also, molecular mechanisms that cause NA in zebrafish were discussed. Revised data showed that the MN test in zebrafish has been applied since 1996. The MN was the most frequently NA, but 15 other nuclear alterations were reported in zebrafish, such as notched nuclei, blebbed nuclei, binucleated cell, buds, lobed nuclei, bridges, and kidney-shaped. Several pollutants can induce NA in zebrafish, mainly effluents (mixture of pollutants), agrochemicals, and microplastics. The pollutant-induced NA in zebrafish depends on experimental design (i.e., exposure time, concentration, and exposure condition), developmental stages, cell/tissue type, and the type of pollutant. Besides, research gaps and recommendations for future studies are indicated. Overall, the current study showed that zebrafish is a suitable model to assess pollutant-induced mutagenicity.

Zebrafish (Danio rerio) using as model for genotoxicity and DNA repair assessments: Historical review, current status and trends

Genotoxic pollutants lead to both DNA damage and changes in cell repair mechanisms. Selecting suitable biomonitors is a fundamental step in genotoxicity studies. Thus, zebrafish have become a popular model used to assess the genotoxicity of different pollutants in recent years. They have orthologous genes with humans and hold almost all genes involved in different repair pathways. Therefore, the aim of the current study is to summarize the existing literature on zebrafish using as model system to assess the genotoxicity of different pollutants. Revised data have shown that comet assay is the main technique adopted in these studies. However, it is necessary standardizing the technique applied to zebrafish in order to enable better result interpretation and comparisons. Overall, pollutants lead to single-strand breaks (SSB), double-strand breaks (DSB), adduct formation, as well as to changes in the expression of genes involved in repair mechanisms. Although analyzing repair mechanisms is essential to better understand the genotoxic effects caused by pollutants, few studies have analyzed repair capacity. The current review reinforces the need of conducting further studies on the role played by repair pathways in zebrafish subjected to DNA damage. Revised data have shown that zebrafish are a suitable model to assess pollutant-induced genotoxicity.

PARP inhibition suppresses topoisomerase 1 poisoning induced Caspase-3 dependent cell death in zebrafish embryos

In the present study the role of poly(ADP)ribosylation on rubitecan induced caspase dependent cell death was evaluated. We show that Top1 poisoning by rubitecan induces caspase mediated apoptosis which was reduced by PARP inhibitor olaparib in zebrafish embryo. Collectively our data introduces zebrafish as a valuable model for PARP related biomedical research.

Applications of the SR4G Transgenic Zebrafish Line for Biomonitoring of Stress-Disrupting Compounds: A Proof-of-Concept Study

Transgenic zebrafish models have been successfully used in biomonitoring and risk assessment studies of environmental pollutants, including xenoestrogens, pesticides, and heavy metals. We employed zebrafish larva (transgenic SR4G line) with a cortisol-inducible green fluorescence protein reporter (eGFP) as a model to detect stress responses upon exposure to compounds with environmental impact, including bisphenol A (BPA), vinclozolin (VIN), and fluoxetine (FLX). Cortisol, fluorescence signal, and mRNA levels of eGFP and 11 targeted genes were measured in a homogenized pool of zebrafish larvae, with six experimental replicates for each endpoint. Eleven targeted genes were selected according to their association with stress-axis and immediate early response class of genes. Hydrocortisone (CORT)and dexamethasone (DEX) were used as positive and negative controls, respectively. All measurements were done in two unstressed and stressed condition using standardized net handling as the stressor. A significant positive linear correlation between cortisol levels and eGFP mRNA levels was observed (r> 0.9). Based on eGFP mRNA levels in unstressed and stressed larvae two predictive models were trained (Random Forest and Logistic Regression). Both these models could correctly predict the blunted stress response upon exposure to BPA, VIN, FLX and the negative control, DEX. The negative predictive value (NPV) of these models were 100%. Similar NPV was observed when the predictive models trained based on the mRNA levels of the eleven assessed genes. Measurement of whole-body fluorescence intensity signal was not significant to detect blunted stress response. Our findings support the use of SR4G transgenic larvae as an in vivo biomonitoring model to screen chemicals for their stress-disrupting potentials. This is important because there is increasing evidence that brief exposures to environmental pollutants modify the stress response and critical coping behaviors for several generations.

Detection of anti-cancer drugs and metabolites in the effluents from a large Brazilian cancer hospital and an evaluation of ecotoxicology

The use of chemotherapy agents has been growing worldwide, due to the increase number of cancer cases. In several countries, mainly in Europe countries, these drugs have been detected in hospitals and municipal wastewaters. In Brazil this issue is poorly explored. The main goal of this study was to assess the presence of three anti-cancer drugs, 5-fluorouracil (5-FU), gemcitabine (GEM) and cyclophosphamide (CP), and two metabolites, alpha-fluoro-beta-alanine (3-NH₂-F) and 2'-deoxy-2',2'-difluorouridine (2-DOH-DiF), in effluents from a large cancer hospital, in the municipal wastewater treatment plant (WWTP) influent and effluent, and also to evaluate toxicity of the mixtures of these compounds by ecotoxicological testing in zebrafish. The sample collections were performed in Barretos Cancer Hospital of the large cancer center in Brazil. After each collection, the samples were filtered for subsequent Liquid Chromatography Mass Spectrometry analysis. The presence of CP, GEM, and both metabolites (3-NH₂-F and 2-DOH-DiF) were detected in the hospital wastewater and the WWTP influent. Three drugs, GEM, 2-DOH-DiF and CP, were detected in the WWTP effluent. Two drugs were detected below the limit of quantification, 2-DOH-DiF: <LOQ (above 1400 ng L^-1) and CP: <LOQ (above 300 ng L^-1), and GEM was quantified at 420 ng L^-1. Furthermore, 2-DOH-DiF (116,000 ng L^-1) was detected at the highest level in the hospital wastewater. There were no zebrafish deaths at any of the concentrations of the compounds used. However, we observed histological changes, including aneurysms and edema in the gills and areas of necrosis of the liver. In summary, we found higher concentrations of CP, GEM and both metabolites (3-NH₂-F and 2-DOH-DiF) were detected for the first time. There is currently no legislation regarding the discharge of anti-cancer drugs in effluents in Brazil. This study is first to focus on effluents from specific treatments from a large cancer hospital located in small city in Brazil.

Application of zebrafish to safety evaluation in drug discovery

Traditionally, safety evaluation at the early stage of drug discovery research has been done using in silico, in vitro, and in vivo systems in this order because of limitations on the amount of compounds available and the throughput ability of the assay systems. While these in vitro assays are very effective tools for detecting particular tissue-specific toxicity phenotypes, it is difficult to detect toxicity based on complex mechanisms involving multiple organs and tissues. Therefore, the development of novel high throughput in vivo evaluation systems has been expected for a long time. The zebrafish (Danio rerio) is a vertebrate with many attractive characteristics for use in drug discovery, such as a small size, transparency, gene and protein similarity with mammals (80% or more), and ease of genetic modification to establish human disease models. Actually, in recent years, the zebrafish has attracted interest as a novel experimental animal. In this article, the author summarized the features of zebrafish that make it a suitable laboratory animal, and introduced and discussed the applications of zebrafish to preclinical toxicity testing, including evaluations of teratogenicity, hepatotoxicity, and nephrotoxicity based on morphological findings, evaluation of cardiotoxicity using functional endpoints, and assessment of seizure and drug abuse liability.

Metallic nanoparticle production and exposure/deposition system for toxicological research applications using zebrafish

Metallic nanoparticles (NPs) have been accepted for various applications ranging from cosmetics to medicine. However, no method has been established in the scientific community that is capable of analyzing various metals, sizes, and levels of exposures without the concern of background chemical contaminations. We present here a system utilizing soft-landing ion mobility (SLIM) exposures of laser ablated metallic clusters capable of operating pressures of reduced vacuum (1 Torr) up to ambient (760 Torr) in the presence of a buffer gas. Clusters experience kinetic energies of less than 1 eV upon exiting the SLIM, allowing for the exposure of NPs to take place in a passive manner. While there is no mass-selection of cluster sizes in this work, it does show for the first time the creation and soft-landing of nanoclusters at ambient pressures. Factors such as area coverage and percentage distribution were studied, as well as the different effects that varying surfaces may cause in the agglomeration of the clusters. Furthermore, the system was successfully used to study the effects of silver nanoparticle exposure and determine the specific organs the NPs accumulate in using zebrafish (Danio rerio) as a model organism. This method provides a novel way to synthesize NPs and expose biological organisms for various toxicological analysis.

Zebrafish patient avatars in cancer biology and precision cancer therapy

In precision oncology, two major strategies are being pursued for predicting clinically relevant tumour behaviours, such as treatment response and emergence of drug resistance: inference based on genomic, transcriptomic, epigenomic and/or proteomic analysis of patient samples, and phenotypic assays in personalized cancer avatars. The latter approach has historically relied on in vivo mouse xenografts and in vitro organoids or 2D cell cultures. Recent progress in rapid combinatorial genetic modelling, the development of a genetically immunocompromised strain for xenotransplantation of human patient samples in adult zebrafish and the first clinical trial using xenotransplantation in zebrafish larvae for phenotypic testing of drug response bring this tiny vertebrate to the forefront of the precision medicine arena. In this Review, we discuss advances in transgenic and transplantation-based zebrafish cancer avatars, and how these models compare with and complement mouse xenografts and human organoids. We also outline the unique opportunities that these different models present for prediction studies and current challenges they face for future clinical deployment.

Probiotic antigenotoxic activity as a DNA bioprotective tool: a minireview with focus on endocrine disruptors

Nowadays, the interest in the role of dietary components able to influence the composition and the activity of the intestinal microbiota and, consequently, to modulate the risk of genotoxicity and colon cancer is increasing in the scientific community. Within this topic, the microbial ability to have a protective role at gastrointestinal level by counteracting the biological activity of genotoxic compounds, and thus preventing the DNA damage, is deemed important in reducing gut pathologies and is considered a new tool for probiotics and functional foods. A variety of genotoxic compounds can be found in the gut and, besides food-related mutagens and other DNA-reacting compounds, there is a group of pollutants commonly used in food packaging and/or in thousands of everyday products called endocrine disruptors (EDs). EDs are exogenous substances that alter the functions of the endocrine system through estrogenic and anti-estrogenic activity, which interfere with normal hormonal function in human and wildlife. Thus, this paper summarizes the main applications of probiotics, mainly lactobacilli, as a bio-protective tool to counteract genotoxic and mutagenic agents, by biologically inhibiting the related DNA damage in the gut and highlights the emerging perspectives to enlarge and further investigate the microbial bio-protective role at intestinal level.

Hazard Assessment of Polymeric Nanobiomaterials for Drug Delivery: What Can We Learn From Literature So Far

The physicochemical properties of nanobiomaterials, such as their small size and high surface area ratio, make them attractive, novel drug-carriers, with increased cellular interaction and increased permeation through several biological barriers. However, these same properties hinder any extrapolation of knowledge from the toxicity of their raw material. Though, as suggested by the Safe-by-Design (SbD) concept, the hazard assessment should be the starting point for the formulation development. This may enable us to select the most promising candidates of polymeric nanobiomaterials for safe drug-delivery in an early phase of innovation. Nowadays the majority of reports on polymeric nanomaterials are focused in optimizing the nanocarrier features, such as size, physical stability and drug loading efficacy, and in performing preliminary cytocompatibility testing and proving effectiveness of the drug loaded formulation, using the most diverse cell lines. Toxicological studies exploring the biological effects of the polymeric nanomaterials, particularly regarding immune system interaction are often disregarded. The objective of this review is to illustrate what is known about the biological effects of polymeric nanomaterials and to see if trends in toxicity and general links between physicochemical properties of nanobiomaterials and their effects may be derived. For that, data on chitosan, polylactic acid (PLA), polyhydroxyalkanoate (PHA), poly(lactic-co-glycolic acid) (PLGA) and policaprolactone (PCL) nanomaterials will be evaluated regarding acute and repeated dose toxicity, inflammation, oxidative stress, genotoxicity, toxicity on reproduction and hemocompatibility. We further intend to identify the analytical and biological tests described in the literature used to assess polymeric nanomaterials toxicity, to evaluate and interpret the available results and to expose the obstacles and challenges related to the nanomaterial testing. At the present time, considering all the information collected, the hazard assessment and thus also the SbD of polymeric nanomaterials is still dependent on a case-by-case evaluation. The identified obstacles prevent the identification of toxicity trends and the generation of an assertive toxicity database. In the future, in vitro and in vivo harmonized toxicity studies using unloaded polymeric nanomaterials, extensively characterized regarding their intrinsic and extrinsic properties should allow to generate such database. Such a database would enable us to apply the SbD approach more efficiently.

Persistent and transgenerational effects of risperidone in zebrafish

Since behavior is the connection between the internal physiological processes of an animal and its interaction with the environment, a complete behavioral repertoire is crucial for fish survival and fitness, at both the individual and population levels. Thus, unintended exposure of non-target organisms to antipsychotic residues in the environment can impact their normal behavior, and some of these behavioral changes can be seen during the entire life of the animal and passed to subsequent generations. Although there are some reports related to transgenerational toxicology, little is known of the long-term consequences of exposure to pharmaceutical compounds such as risperidone. Here, we show that zebrafish exposed to risperidone (RISP) during embryonic and larval stages presented impaired anti-predatory behavior during adulthood, characterizing a persistent effect. We also show that some of these behavioral changes are present in the following generation, characterizing a transgenerational effect. This suggests that even short exposures to environmentally relevant concentrations, at essential stages of development, can persist throughout the whole life of the zebrafish, including its offspring. From an environmental perspective, our results suggested possible risks and long-term consequences associated with drug residues in water, which can affect aquatic life and endanger species that depend on appropriate behavioral responses for survival.

Nanomaterials meet zebrafish: Toxicity evaluation and drug delivery applications

With the rapid development of engineered nanomaterials for various applications, in vivo toxicological studies for evaluating the potential hazardous effects of nanomaterials on environmental and human safety are in urgent need. Zebrafish has long been considered as the "gold standard" for biosafety assessments of chemicals and pollutants due to its high fecundity, cost-effectiveness, well-characterized developmental stages, optical transparency, and so forth. Thus, zebrafish holds great potential for high-throughput nanotoxicity screening. In this review, we summarize the in vivo toxicological profiles of different nanomaterials, including Ag nanoparticles (NPs), CuO NPs, silica NPs, polymeric NPs, quantum dots, nanoscale metal-organic frameworks, etc, in zebrafish and focus on how the physicochemical properties (e.g., size, surface charge, and surface chemistry) of these nanomaterials influence their biosafety. In addition, we also report the recent advances of the in vivo delivery of nanopharmaceuticals using zebrafish as the model organism for therapeutic assessment, biodistribution tracking, and the controlled release of loaded drugs. Limitations and special considerations of zebrafish model are also discussed. Overall, zebrafish is expected to serve as a high-throughput screening platform for nanotoxicity and drug delivery assessment, which may instruct the design of safe nanomaterials and more effective nanomedicines.

Efficient cell surface labelling of live zebrafish embryos: wash-free fluorescence imaging for cellular dynamics tracking and nanotoxicity evaluation

Imaging the dynamics and behaviors of plasma membranes is at the leading edge of life science research. We report here the development of a universal red-fluorescent probe Chol-PEG-Cy5 for wash-free plasma membrane labelling both in vitro and in vivo. In aqueous solutions, the fluorescence of Chol-PEG-Cy5 is significantly quenched due to the intermolecular resonance energy transfer (RET) between neighbouring Cy5 moieties; however, upon membrane anchoring, the probes undergo lateral diffusion in lipid bilayers, resulting in weakened RET and turn-on fluorescence emission. We demonstrate that Chol-PEG-Cy5 enables rapid, stable and high-quality in vitro cell surface imaging in a variety of mammalian cells. Additionally, with the assistance of three-dimensional (3D) image reconstruction, we achieve for the first time the whole-mount in situ fluorescence imaging of the epidermal cell surfaces of live zebrafish embryos, which cannot be realized by conventional plasma membrane probes due to the presence of the surface-covering mucus barrier. This novel technique encourages us to track the cellular dynamics of the epidermis during embryonic development with 3D visualization. Moreover, we also develop a new method to evaluate the epidermal toxicity of nanomaterials (e.g., gold nanoparticles and graphene oxide nanosheets) toward zebrafish embryos using this fluorescent probe.

In vitro and in vivo genotoxicity of oxygenated polycyclic aromatic hydrocarbons

Oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are a group of environmental pollutants found in complex mixtures together with PAHs. In contrast to the extensively studied PAHs, which have been established to have mutagenic and carcinogenic properties, much less is known about the effects of oxy-PAHs. The present work aimed to investigate the genotoxic potency of a set of environmentally relevant oxy-PAHs along with environmental soil samples in human bronchial epithelial cells (HBEC). We found that all oxy-PAHs tested induced DNA strand breaks in a dose-dependent manner and some of the oxy-PAHs further induced micronuclei formation. Our results showed weak effects in response to the oxy-PAH containing subfraction of the soil sample. The genotoxic potency was confirmed in both HBEC and HepG2 cells following exposure to oxy-PAHs by an increased level of phospho-Chk1, a biomarker used to estimate the carcinogenic potency of PAHs in vitro. We further exposed zebrafish embryos to single oxy-PAHs or a binary mixture with PAH benzo[a]pyrene (B[a]P) and found the mixture to induce comparable or greater effects on the induction of DNA strand breaks compared to the sum of that induced by B[a]P and oxy-PAHs alone. In conclusion, oxy-PAHs were found to elicit genotoxic effects at similar or higher levels to that of B[a]P which indicates that oxy-PAHs may contribute significantly to the total carcinogenic potency of environmental PAH mixtures. This emphasizes further investigations of these compounds as well as the need to include oxy-PAHs in environmental monitoring programs in order to improve health risk assessment.

Differential Toxicity of mDia Formin-Directed Functional Agonists and Antagonists in Developing Zebrafish

The mammalian Diaphanous-related (mDia) formins are cytoskeletal regulators that assemble and, in some cases, bundle filamentous actin (F-actin), as well as stabilize microtubules. The development of small molecule antagonists and agonists that interrogate mDia formin function has allowed us to investigate the roles of formins in disease states. A small molecule inhibitor of FH2 domain (SMIFH2) inhibits mDia-dependent actin dynamics and abrogates tumor cell migration and cell division in vitro and ex vivo tissue explants. mDia formin activation with small molecule intramimics IMM01/02 and mDia2-DAD peptides inhibited glioblastoma motility and invasion in vitro and ex vivo rat brain slices. However, SMIFH2, IMMs, and mDia2 DAD efficacy in vivo remains largely unexplored and potential toxicity across a range of developmental phenotypes has not been thoroughly characterized. In this study, we performed an in vivo screen of early life-stage toxicity in Danio rerio zebrafish embryos 2 days post-fertilization (dpf) in response to SMIFH2, IMM01/02, and mDia2 DAD. SMIFH2 at concentrations ≥5–10 μM induced significant defects in developing zebrafish, including shorter body lengths, tail curvature and defective tail cellularity, craniofacial malformations, pericardial edema, absent and/or compromised vasculature function and flow, depressed heart rates and increased mortality. Conversely, IMM and mDia2 DAD peptides were minimally toxic at concentrations up to 10–20 and 50 μM, respectively. SMIFH2's therapeutic potential may therefore be limited by its substantial in vivo toxicity at functional concentrations. mDia formin agonism with IMMs and mDia2 DADs may therefore be a more effective and less toxic anti-invasive therapeutic approach.

Biological and Pharmacological Characterization of Benzothiazole-Based CK-1δ Inhibitors in Models of Parkinson's Disease

Parkinson's disease (PD), an age-related neurodegenerative disorder that results from a progressive loss of dopaminergic neurons has an enormous economical and human cost. Unfortunately, only symptomatic treatment such as dopamine replacement therapy is available. Therefore, drugs with new mechanisms of action able to protect against neuronal cell death are an urgent need. We here report the in vivo efficacy on dopaminergic neuronal protection in a PD mouse model and the lack of toxicity in zebrafish and Ames test of benzothiazole-based casein kinase-1δ (CK-1δ) nanomolar inhibitors. On the basis of these results, we propose protein kinase CK-1δ inhibitors as the possible disease-modifying drugs for PD, benzothiazole 4 being a promising drug candidate for further development as a new therapy of this neurodegenerative disease.

PEG-b-PCL polymeric nano-micelle inhibits vascular angiogenesis by activating p53-dependent apoptosis in zebrafish

Micro/nanoparticles could cause adverse effects on cardiovascular system and increase the risk for cardiovascular disease-related events. Nanoparticles prepared from poly(ethylene glycol) (PEG)-b-poly(ε-caprolactone) (PCL), namely PEG-b-PCL, a widely studied biodegradable copolymer, are promising carriers for the drug delivery systems. However, it is unknown whether polymeric PEG-b-PCL nano-micelles give rise to potential complications of the cardiovascular system. Zebrafish were used as an in vivo model to evaluate the effects of PEG-b-PCL nano-micelle on cardiovascular development. The results showed that PEG-b-PCL nano-micelle caused embryo mortality as well as embryonic and larval malformations in a dose-dependent manner. To determine PEG-b-PCL nano-micelle effects on embryonic angiogenesis, a critical process in zebrafish cardiovascular development, growth of intersegmental vessels (ISVs) and caudal vessels (CVs) in flk1-GFP transgenic zebrafish embryos using fluorescent stereomicroscopy were examined. The expression of fetal liver kinase 1 (flk1), an angiogenic factor, by real-time quantitative polymerase chain reaction (qPCR) and in situ whole-mount hybridization were also analyzed. PEG-b-PCL nano-micelle decreased growth of ISVs and CVs, as well as reduced flk1 expression in a concentration-dependent manner. Parallel to the inhibitory effects on angiogenesis, PEG-b-PCL nano-micelle exposure upregulated p53 pro-apoptotic pathway and induced cellular apoptosis in angiogenic regions by qPCR and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis assay. This study further showed that inhibiting p53 activity, either by pharmacological inhibitor or RNA interference, could abrogate the apoptosis and angiogenic defects caused by PEG-b-PCL nano-micelles, indicating that PEG-b-PCL nano-micelle inhibits angiogenesis by activating p53-mediated apoptosis. This study indicates that polymeric PEG-b-PCL nano-micelle could pose potential hazards to cardiovascular development.

Effect of 17α-methyltestosterone (MT) on oxidation stress in the liver of juvenile GIFT tilapia, Oreochromis niloticus

The normal dose of 17α-methyltestosterone (MT) used in fish farming was 60 mg/L, and now the analysis of residual androgens was carried out in waste water obtained from the Beijing area, which could be detected in levels ranging from 4.1 to 7.0 ng/L. For the purpose of aquatic early warning, the present study clearly demonstrated that chronic exposure by higher concentration of MT than environmental relevant concentrations could trigger oxidative stress response to juvenile tilapia by modulating hepatic antioxidant enzyme activities and gene transcription. Some antioxidative parameters (T-GSH, GSH/GSSG and MDA) were significant decreased under 0.5 mg/L MT exposure at 7 and 14 days. Some antioxidant enzymes (SOD, CAT and GST) and transcriptional changes (sod and cat) were revealed significant decreases for MT treated groups at 7 days. Total antioxidant capacity was significant increased only in 5 mg/L MT exposure groups, but GR activities were not affected all through the whole exposure period. Almost all of the antioxidant enzymatic genes detected in the present study were showed significant increments for MT exposure both at 14 and 21 days, and the genotoxicity profile of antioxidant enzymatic genes were revealed dose-dependent manner. This study presented evidence that MT could result in oxidative stress response in the early stages of GIFT tilapia.

2-Octadecynoic acid as a dual life stage inhibitor of Plasmodium infections and plasmodial FAS-II enzymes

The malaria parasite Plasmodium goes through two life stages in the human host, a non-symptomatic liver stage (LS) followed by a blood stage with all clinical manifestation of the disease. In this study, we investigated a series of 2-alkynoic fatty acids (2-AFAs) with chain lengths between 14 and 18 carbon atoms for dual in vitro activity against both life stages. 2-Octadecynoic acid (2-ODA) was identified as the best inhibitor of Plasmodium berghei parasites with ten times higher potency (IC50=0.34 μg/ml) than the control drug. In target determination studies, the same compound inhibited three Plasmodium falciparum FAS-II (PfFAS-II) elongation enzymes PfFabI, PfFabZ, and PfFabG with the lowest IC50 values (0.28-0.80 μg/ml, respectively). Molecular modeling studies provided insights into the molecular aspects underlying the inhibitory activity of this series of 2-AFAs and a likely explanation for the considerably different inhibition potentials. Blood stages of P. falciparum followed a similar trend where 2-ODA emerged as the most active compound, with 20 times less potency. The general toxicity and hepatotoxicity of 2-AFAs were evaluated by in vitro and in vivo methods in mammalian cell lines and zebrafish models, respectively. This study identifies 2-ODA as the most promising antiparasitic 2-AFA, particularly towards P. berghei parasites.