Zebrafish models of cardiovascular disease

Troponin C gene mutations on cardiac muscle cell and skeletal Regulation: A comprehensive review

BACKGROUND

The troponin complex plays a crucial role in regulating skeletal and cardiac contraction. Congenital myopathies can occur due to several mutations in genes that encode skeletal troponin. Moreover, there is limited information regarding the composition of skeletal troponin. This review specifically examines a comprehensive review of the TNNC gene mutations on cardiac and skeletal regulations.

MAIN BODY

Troponin C (TNNC) has been linked to a newly discovered inherited muscle disorder. Genetic variations in genes that encode skeletal troponin can impair the function of sarcomeres. Various treatment approaches have been employed to mitigate the impact of variations, including the use of troponin activators, the injection of wild-type protein via AAV gene therapy, and myosin modification to enhance muscle contraction. The processes responsible for the pathophysiological implications of the variations in genes that encode skeletal troponin are not fully understood.

CONCLUSION

This comprehensive review will contribute to the understanding of the relationship between human cardiomyopathy and TNNC mutations and will guide the development of therapy approaches.

Pyraclostrobin induces developmental toxicity and cardiotoxicity through oxidative stress and inflammation in zebrafish embryos

Pyraclostrobin, a typical representative of strobilurin fungicides, is extensively used in agriculture to control fungi and is often detected in water bodies and food. However, the comprehensive toxicological molecular mechanism of pyraclostrobin requires further study. To assess the toxic effects and underlying mechanisms of pyraclostrobin on aquatic organisms, zebrafish embryos were exposed to pyraclostrobin (20, 40, and 60 μg/L) until 96 h post fertilization (hpf). These results indicated that exposure to pyraclostrobin induces morphological alterations, including spinal curvature, shortened body length, and smaller eyes. Furthermore, heart developmental malformations, such as pericardial edema and bradycardia, were observed. This indicated severe cardiotoxicity induced by pyraclostrobin in zebrafish embryos, which was confirmed by the dysregulation of genes related to heart development. Besides, our findings also demonstrated that pyraclostrobin enhanced the contents of reactive oxygen species (ROS) and malondialdehyde (MDA), up-regulated catalase (CAT) activity, but inhibited superoxide dismutase (SOD) activity. Subsequently, the NF-κb signaling pathway was further studied, and the results indicated that the up-regulation of tnf-α, tlr-4, and myd88 activated the NF-κb signaling pathway and up-regulated the relative expression level of pro-inflammatory cytokines, such as cc-chemokine, ifn-γ, and cxcl-clc. Collectively, this study revealed that pyraclostrobin exposure induces developmental toxicity and cardiotoxicity, which may result from a combination of oxidative stress and inflammatory responses. These findings provide a basis for continued evaluation of the effects and ecological risks of pyraclostrobin on the early development of aquatic organisms.

Zebrafish Congenital Heart Disease Models: Opportunities and Challenges

Congenital heart defects (CHDs) are common human birth defects. Genetic mutations potentially cause the exhibition of various pathological phenotypes associated with CHDs, occurring alone or as part of certain syndromes. Zebrafish, a model organism with a strong molecular conservation similar to humans, is commonly used in studies on cardiovascular diseases owing to its advantageous features, such as a similarity to human electrophysiology, transparent embryos and larvae for observation, and suitability for forward and reverse genetics technology, to create various economical and easily controlled zebrafish CHD models. In this review, we outline the pros and cons of zebrafish CHD models created by genetic mutations associated with single defects and syndromes and the underlying pathogenic mechanism of CHDs discovered in these models. The challenges of zebrafish CHD models generated through gene editing are also discussed, since the cardiac phenotypes resulting from a single-candidate pathological gene mutation in zebrafish might not mirror the corresponding human phenotypes. The comprehensive review of these zebrafish CHD models will facilitate the understanding of the pathogenic mechanisms of CHDs and offer new opportunities for their treatments and intervention strategies.

Prediction of Pesticide Interactions with Proteins Involved in Human Reproduction by Using a Virtual Screening Approach: A Case Study of Famoxadone Binding CRBP-III and Izumo

In recent years, the awareness that pesticides can have other effects apart from generic toxicity is growing. In particular, several pieces of evidence highlight their influence on human fertility. In this study, we investigated, by a virtual screening approach, the binding between pesticides and proteins present in human gametes or associated with reproduction, in order to identify new interactions that could affect human fertility. To this aim, we prepared ligand (pesticides) and receptor (proteins) 3D structure datasets from online structural databases (such as PubChem and RCSB), and performed a virtual screening analysis using Autodock Vina. In the comparison of the predicted interactions, we found that famoxadone was predicted to bind Cellular Retinol Binding Protein-III in the retinol-binding site with a better minimum energy value of -10.4 Kcal/mol and an RMSD of 3.77 with respect to retinol (-7.1 Kcal/mol). In addition to a similar network of interactions, famoxadone binding is more stabilized by additional hydrophobic patches including L20, V29, A33, F57, L117, and L118 amino acid residues and hydrogen bonds with Y19 and K40. These results support a possible competitive effect of famoxadone on retinol binding with impacts on the ability of developing the cardiac tissue, in accordance with the literature data on zebrafish embryos. Moreover, famoxadone binds, with a minimum energy value between -8.3 and -8.0 Kcal/mol, to the IZUMO Sperm-Egg Fusion Protein, interacting with a network of polar and hydrophobic amino acid residues in the cavity between the 4HB and Ig-like domains. This binding is more stabilized by a predicted hydrogen bond with the N185 residue of the protein. A hindrance in this position can probably affect the conformational change for JUNO binding, avoiding the gamete membrane fusion to form the zygote. This work opens new interesting perspectives of study on the effects of pesticides on fertility, extending the knowledge to other typologies of interaction which can affect different steps of the reproductive process.

Hexafluoropropylene oxide trimer acid, a perfluorooctanoic acid alternative, induces cardiovascular toxicity in zebrafish embryos

As an increasingly used alternative to perfluorooctanoic acid (PFOA), hexafluoropropylene oxide trimer acid (HFPO-TA) has been widely detected in global water environments. However, little is known regarding its toxic effects on cardiovascular development. Here, zebrafish embryos were treated with egg water containing 0, 60, 120, or 240 mg/L HFPO-TA. Results showed that HFPO-TA treatment led to a significant reduction in both larval survival percentage and heart rate. Furthermore, HFPO-TA exposure caused severe pericardial edema and elongation of the sinus venous to bulbus arteriosus distance (SV-BA) in Tg (myl7: GFP) transgenic larvae, disrupting the expression of genes involved in heart development and thus causing abnormal heart looping. Obvious sprouting angiogenesis was observed in the 120 and 240 mg/L exposed Tg (fli: GFP) transgenic larvae. HFPO-TA treatment also impacted the mRNA levels of genes involved in the vascular endothelial growth factor (VEGF) pathway and embryonic vascular development. HFPO-TA exposure significantly decreased erythrocyte number in Tg (gata1: DsRed) transgenic embryos and influenced gene expression associated with the heme metabolism pathway. HFPO-TA also induced oxidative stress and altered the transcriptional levels of genes related to cell cycle and apoptosis, inhibiting cell proliferation while promoting apoptosis. Therefore, HFPO-TA exposure may induce abnormal development of the cardiovascular and hematopoietic systems in zebrafish embryos, suggesting it may not be a suitable or safe alternative for PFOA.

PERK inhibition in zebrafish mimics human Wolcott-Rallison syndrome phenotypes

Wolcott-Rallison Syndrome (WRS) is the most common cause of permanent neonatal diabetes mellitus among consanguineous families. The diabetes associated with WRS is non-autoimmune, insulin-requiring and associated with skeletal dysplasia and growth retardation. The therapeutic options for WRS patients rely on permanent insulin pumping or on invasive transplants of liver and pancreas. WRS has a well identified genetic cause: loss-of-function mutations in the gene coding for an endoplasmic reticulum kinase named PERK (protein kinase R-like ER kinase). Currently, WRS research is facilitated by cellular and rodent models with PERK ablation. While these models have unique strengths, cellular models incompletely replicate the organ/system-level complexity of WRS, and rodents have limited scalability for efficiently screening potential therapeutics. To address these challenges, we developed a new in vivo model of WRS by pharmacologically inhibiting PERK in zebrafish. This small vertebrate displays high fecundity, rapid development of organ systems and is amenable to highly efficient in vivo drug testing. PERK inhibition in zebrafish produced typical WRS phenotypes such as glucose dysregulation, skeletal defects, and impaired development. PERK inhibition in zebrafish also produced broad-spectrum WRS phenotypes such as impaired neuromuscular function, compromised cardiac function and muscular integrity. These results show that zebrafish holds potential as a versatile model to study WRS mechanisms and contribute to the identification of promising therapeutic options for WRS.

Zebrafish cardiac repolarization does not functionally depend on the expression of the hERG1b-like transcript

Zebrafish provide a translational model of human cardiac function. Their similar cardiac electrophysiology enables screening of human cardiac repolarization disorders, drug arrhythmogenicity, and novel antiarrhythmic therapeutics. However, while zebrafish cardiac repolarization is driven by delayed rectifier potassium channel current (IKr), the relative role of alternate channel transcripts is uncertain. While human ether-a-go-go-related-gene-1a (hERG1a) is the dominant transcript in humans, expression of the functionally distinct alternate transcript, hERG1b, modifies the electrophysiological and pharmacologic IKr phenotype. Studies of zebrafish IKr are frequently translated without consideration for the presence and impact of hERG1b in humans. Here, we performed phylogenetic analyses of all available KCNH genes from Actinopterygii (ray-finned fishes). Our findings confirmed zebrafish cardiac zkcnh6a as the paralog of human hERG1a (hKCNH2a), but also revealed evidence of a hERG1b (hKCNH2b)-like N-terminally truncated gene, zkcnh6b, in zebrafish. zkcnh6b is a teleost-specific variant that resulted from the 3R genome duplication. qRT-PCR showed dominant expression of zkcnh6a in zebrafish atrial and ventricular tissue, with low levels of zkcnh6b. Functional evaluation of zkcnh6b in a heterologous system showed no discernable function under the conditions tested, and no influence on zkcnh6a function during the zebrafish ventricular action potential. Our findings provide the first descriptions of the zkcnh6b gene, and show that, unlike in humans, zebrafish cardiac repolarization does not rely upon co-assembly of zERG1a/zERG1b. Given that hERG1b modifies IKr function and drug binding in humans, our findings highlight the need for consideration when translating hERG variant effects and toxicological screens in zebrafish, which lack a functional hERG1b-equivalent gene.

Zebrafish (Danio rerio) as a Model for the Study of Developmental and Cardiovascular Toxicity of Electronic Cigarettes

The increasing popularity of electronic cigarettes (e-cigarettes) as an alternative to conventional tobacco products has raised concerns regarding their potential adverse effects. The cardiovascular system undergoes intricate processes forming the heart and blood vessels during fetal development. However, the precise impact of e-cigarette smoke and aerosols on these delicate developmental processes remains elusive. Previous studies have revealed changes in gene expression patterns, disruptions in cellular signaling pathways, and increased oxidative stress resulting from e-cigarette exposure. These findings indicate the potential for e-cigarettes to cause developmental and cardiovascular harm. This comprehensive review article discusses various aspects of electronic cigarette use, emphasizing the relevance of cardiovascular studies in Zebrafish for understanding the risks to human health. It also highlights novel experimental approaches and technologies while addressing their inherent challenges and limitations.

The zebrafish for preclinical psilocybin research

In this review, we discuss the possible utility of zebrafish in research on psilocybin, a psychedelic drug whose recreational use as well as possible clinical application are gaining increasing interest. First, we review behavioral tests with zebrafish, focussing on anxiety and social behavior, which have particular relevance in the context of psilocybin research. Next, we briefly consider methods of genetic manipulations with which psilocybin's phenotypical effects and underlying mechanisms may be investigated in zebrafish. We briefly review the known mechanisms of psilocybin, and also discuss what we know about its safety and toxicity profile. Last, we discuss examples of how psilocybin may be employed for testing treatment efficacy in preclinical research for affective disorders in zebrafish. We conclude that zebrafish has a promising future in preclinical research on psychedelic drugs.

Attitudes to the use of animals in biomedical research: Effects of stigma and selected research project summaries

Three groups of participants (largely recruited from the UK) completed a survey to examine attitudes to the use of animals in biomedical research, after reading the lay (N = 182) or technical (N = 201) summary of a research project, or no summary (N = 215). They then completed a survey comprising the animal attitude (AAS), animal purpose (APQ), belief in animal mind (BAM) and empathy quotient (EQ) scales. The APQ was adapted to assess attitudes towards the use of animals for research into disorders selected to be perceived as controllable and so 'blameworthy' and potentially stigmatised (addiction and obesity) and 'psychological' (schizophrenia and addiction) versus 'physical' (cardiovascular disease and obesity), across selected species (rats, mice, fish pigs and monkeys). Thus, the APQ was used to examine how the effects of perceived controllability and the nature of the disorder affected attitudes to animal use, in different species and in the three summary groups. As expected, attitudes to animal use as measured by the AAS and the APQ (total) correlated positively with BAM and EQ scores, consistent with the assumption that the scales all measured pro-welfare attitudes. Participants in the two research summary groups did not differentiate the use of rats, mice and fish (or fish and pigs in the technical summary group), whereas all species were differentiated in the no summary group. Participants given the lay summary were as concerned about the use of animals for schizophrenia as for addiction research. APQ ratings otherwise indicated more concern for animals used for addiction research (and for obesity compared to cardiovascular disease in all summary groups). Therefore, the information provided by a research project summary influenced attitudes to use of animals in biomedical research. However, there was no overall increase in agreement with animal use in either of the summary groups.

Cfdp1 Is Essential for Cardiac Development and Function

Cardiovascular diseases (CVDs) are the prevalent cause of mortality worldwide. A combination of environmental and genetic effectors modulates the risk of developing them. Thus, it is vital to identify candidate genes and elucidate their role in the manifestation of the disease. Large-scale human studies have revealed the implication of Craniofacial Development Protein 1 (CFDP1) in Coronary Artery Disease (CAD). CFDP1 belongs to the evolutionary conserved Bucentaur (BCNT) family, and to date, its function and mechanism of action in Cardiovascular Development are still unclear. We utilized zebrafish to investigate the role of cfdp1 in the developing heart due to the high genomic homology, similarity in heart physiology, and ease of experimental manipulations. We showed that cfdp1 was expressed during development, and we tested two morpholinos and generated a cfdp1 mutant line. The cfdp1-/- embryos developed arrhythmic hearts and exhibited defective cardiac performance, which led to a lethal phenotype. Findings from both knockdown and knockout experiments showed that abrogation of cfdp1 leads to downregulation of Wnt signaling in embryonic hearts during valve development but without affecting Notch activation in this process. The cfdp1 zebrafish mutant line provides a valuable tool for unveiling the novel mechanism of regulating cardiac physiology and function. cfdp1 is essential for cardiac development, a previously unreported phenotype most likely due to early lethality in mice. The detected phenotype of bradycardia and arrhythmias is an observation with potential clinical relevance for humans carrying heterozygous CFDP1 mutations and their risk of developing CAD.

Developmental and cardiac toxicity assessment of Ethyl 3-(N-butylacetamido) propanoate (EBAAP) in zebrafish embryos

Ethyl 3-(N-butylacetamido) propanoate (EBAAP) is one of the most widely used mosquito repellents worldwide, and is also commonly used to produce cosmetics. Residues have recently been detected in surface and groundwater in many countries, and their potential to harm the environment is unknown. Therefore, more studies are needed to fully assess the toxicity of EBAAP. This is the first investigation into the developmental toxicity and cardiotoxicity of EBAAP on zebrafish embryos. EBAAP was toxic to zebrafish, with a lethal concentration 50 (LC50) of 140 mg/L at 72 hours post fertilization (hpf). EBAAP exposure also reduced body length, slowed the yolk absorption rate, induced spinal curvature and pericardial edema, decreased heart rate, promoted linear lengthening of the heart, and diminished cardiac pumping ability. The expression of heart developmental-related genes (nkx2.5, myh6, tbx5a, vmhc, gata4, tbx2b) was dysregulated, intracellular oxidative stress increased significantly, the activities of catalase (CAT) and superoxide dismutase (SOD) decreased, and malondialdehyde (MDA) content increased significantly. The expression of apoptosis-related genes (bax/bcl2, p53, caspase9, caspase3) was significantly upregulated. In conclusion, EBAAP induced abnormal morphology and heart defects during the early stages of zebrafish embryo development by potentially inducing the generation and accumulation of reactive oxygen species (ROS) in vivo and activating the oxidative stress response. These events dysregulate the expression of several genes and activate endogenous apoptosis pathways, eventually leading to developmental disorders and heart defects.

Standardisation and future of preclinical echocardiography

Echocardiography is a non-invasive imaging technique providing real-time information to assess the structure and function of the heart. Due to advancements in technology, ultra-high-frequency transducers have enabled the translation of ultrasound from humans to small animals due to resolutions down to 30 µm. Most studies are performed using mice and rats, with ages ranging from embryonic, to neonatal, and adult. In addition, alternative models such as zebrafish and chicken embryos are becoming more frequently used. With the achieved high temporal and spatial resolution in real-time, cardiac function can now be monitored throughout the lifespan of these small animals to investigate the origin and treatment of a range of acute and chronic pathological conditions. With the increased relevance of in vivo real-time imaging, there is still an unmet need for the standardisation of small animal echocardiography and the appropriate cardiac measurements that should be reported in preclinical cardiac models. This review focuses on the development of standardisation in preclinical echocardiography and reports appropriate cardiac measurements throughout the lifespan of rodents: embryonic, neonatal, ageing, and acute and chronic pathologies. Lastly, we will discuss the future of cardiac preclinical ultrasound.

Research Progress on the Construction and Application of a Diabetic Zebrafish Model

Diabetes is a metabolic disease characterized by high blood glucose levels. With economic development and lifestyle changes, the prevalence of diabetes is increasing yearly. Thus, it has become an increasingly serious public health problem in countries around the world. The etiology of diabetes is complex, and its pathogenic mechanisms are not completely clear. The use of diabetic animal models is helpful in the study of the pathogenesis of diabetes and the development of drugs. The emerging vertebrate model of zebrafish has many advantages, such as its small size, large number of eggs, short growth cycle, simple cultivation of adult fish, and effective improvement of experimental efficiency. Thus, this model is highly suitable for research as an animal model of diabetes. This review not only summarizes the advantages of zebrafish as a diabetes model, but also summarizes the construction methods and challenges of zebrafish models of type 1 diabetes, type 2 diabetes, and diabetes complications. This study provides valuable reference information for further study of the pathological mechanisms of diabetes and the research and development of new related therapeutic drugs.

Benomyl-induced development and cardiac toxicity in zebrafish embryos

Benomyl is a highly effective broad-spectrum fungicide widely used worldwide to control vegetable, fruit, and oil crop diseases. However, the mechanism of its toxicity to aquatic organisms and humans remains unknown. In this study, zebrafish were used to determine the toxicity of benomyl. It was found to be highly toxic, with a 72-h post-fertilization (hpf) lethal concentration 50 (LC₅₀) of 1.454 mg/L. Benomyl induced severe developmental toxicity, including shorter body length, slower heart rate, and a reduced yolk absorption rate. Benomyl also increased oxidative stress in zebrafish, especially in the heart and head, as well as increasing malondialdehyde (MDA) content and decreasing catalase (CAT) and superoxide dismutase (SOD) activities. This indicates that benomyl induced reactive oxygen species (ROS) production and cell membrane peroxidation in vivo. Acridine orange (AO) staining and apoptosis factor detection further indicated that benomyl induced apoptosis in zebrafish. Overall, these findings demonstrate that benomyl disrupts cellular homeostasis by activating oxidative stress in zebrafish, resulting in an imbalance of cardiac development-related gene expression and apoptosis, which causes severe developmental toxicity and cardiac dysfunction. This study evaluated the in vivo toxicity of benomyl, which is a potential threat to aquatic organisms and humans. Possible toxicity mechanisms are explored, providing a valuable reference for the safe use of benomyl.

Developmental toxicity induced by brodifacoum in zebrafish (Danio rerio) early life stages

OBJECTIVES

The present study mainly focused on the assessment of developmental toxicity induced by exposure to brodifacoum (BDF) in zebrafish at early life stages.

MATERIAL AND METHODS

Zebrafish embryos were exposed to 0.2, 0.4, and 0.8 mg/L of BDF from 6 to 96 hr post-fertilization (hpf), and the toxic effects of BDF on early embryonic development were investigated in terms of morphological changes, oxidative stress, and alterations in heart development-related genes.

RESULTS

The experimental results showed that BDF significantly decreased the heart rate, survival rate, body length, and spontaneous movements of zebrafish embryos at 0.8 mg/L, and the morphological developmental abnormalities were also observed at 96 hpf. In addition, exposure to BDF significantly increased oxidative stress levels in zebrafish embryos by increasing the enzymatic activities of catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA) levels, and decreased glutathione (GSH) levels. Furthermore, BDF treatment-induced alterations in the expression levels of the heart development-related genes (gata4, sox9b, tbx2b, and nppa).

CONCLUSION

Results from this study indicated that exposure to BDF could lead to marked growth inhibition and significantly alter the activities of antioxidant enzymes in zebrafish embryos. Moreover, BDF exposure exhibited severe cardiotoxicity and significantly disrupted heart development-related genes. The results indicated that BDF could induce developmental and cardiac toxicity in zebrafish embryos.

Neurotoxicity of sanguinarine via inhibiting mitophagy and activating apoptosis in zebrafish and PC12 cells

Sanguinarine, a plant-derived phytoalexin, displays various biological activities, such as insecticidal, antimicrobial, anti-inflammatory, anti-angiogenesis and antitumor effects. But its potential neurotoxicity and the underlying mechanisms has rarely been investigated. Therefore, we aimed to assess the neurotoxicity of sanguinarine using zebrafish model and PC12 cells in this study. The results showed that sanguinarine induced the reduction of the length of dopamine neurons and inhibited the blood vessel in the head area of the zebrafish. Further studies demonstrated that the behavioral phenotype of the larval zebrafish was changed by sanguinarine. In addition, there were more apoptotic cells in the larval zebrafish head area. The mRNA expression levels of β-syn, th, pink1 and parkin, closely related to the nervous function, were changed after sanguinarine treatment. The in vitro studies show that notably increases of ROS and apoptosis levels in PC12 cells were observed after sanguinarine treatment. Moreover, the protein expression of Caspase3, Parp, Bax, Bcl2, α-Syn, Th, PINK1 and Parkin were also altered by sanguinarine. Our data indicated that the inhibition of mitophagy, ROS elevation and apoptosis were involved in the neurotoxicity of sanguinarine. These findings will be useful to understand the toxicity induced by sanguinarine.

Screening of anti-heart failure active compounds from fangjihuangqi decoction in verapamil-induced zebrafish model by anti-heart failure index approach

Heart failure is the end stage of various cardiovascular diseases. Fangjihuangqi Decoction (FJHQD) is a famous traditional Chinese medicine (TCM) formula, which is clinically effective in the treatment of chronic heart failure. However, the anti-heart failure ingredients of FJHQD have not been clarified, and the related mechanisms of action are rarely studied. In the present study, through quantification analysis of heart rate and ventricular area changes, a heart failure model and cardiac function evaluation system in cardiomyocytes-labelled Tg (cmlc2: eGFP) transgenic zebrafish larvae were constructed, and the anti-heart failure index (AHFI) that can comprehensively evaluate the cardiac function of zebrafish was proposed. Based on this model, FJHQD, its mainly botanical drugs, components and ingredients were evaluated for the anti-heart failure effects. The results showed that FJHQD and its botanical drugs exhibited potent anti-heart failure activity. Furthermore, total alkaloids from Stephania tetrandra S. Moore, total flavonoids from Astragalus mongholicus Bunge and total flavonoids from Glycyrrhiza uralensis Fisch. ex DC. were identified to be the main components exerting the anti-heart failure activity of FJHQD. Then, we screened the main ingredients of these components, and glycyrrhizic acid, licochalcone A and calycosin were found to exhibit excellent cardioprotective effects. Finally, we found that FJHQD, glycyrrhizic acid, licochalcone A and calycosin may improve cardiac function in zebrafish by regulating oxidative stress, inflammatory response and apoptosis-related pathways. Taken together, our findings offer biological evidences toward the anti-heart failure effect of FJHQD, and provide guidance for the clinical application of FJHQD.

Effects of glyphosate on zebrafish: a systematic review and meta-analysis

Glyphosate herbicide is widely used in worldwide crop production. Consequently, its active ingredient, surfactants, and adjuvants commonly reach the aquatic ecosystem, thereby harming the biota. An investigation into how this herbicide affects aquatic species is important, especially in fish, as they have the ability to absorb and concentrate toxins. We aimed to evaluate the effects of glyphosate on the embryonic, larval and adult stages of zebrafish (Danio rerio), an appreciable organismal model. In this sense, we performed a meta-analysis using published articles from online databases (PubMed and ScienceDirect), which covered studies published until 2022. From a massive compilation of studies evaluating the effects of active substance glyphosate and Glyphosate-Based Herbicides (GBH) on zebrafish, we selected 36 studies used in downstream analyses. Overall, we report that glyphosate affects developmental stages and demonstrates toxicity and damage in zebrafish. We observed that embryos exposed to glyphosate exhibit increased mortality. There was also an increase in the number of morphological abnormalities related to yolk sac oedema, pericardial oedema, spinal curvature and body malformations, and a decrease in body size was observed. Furthermore, there was a decrease in the number of beats. The biochemical results demonstrated an increase in reactive oxygen species and antioxidant capacity against peroxyl radicals in the gills. The literature shows that glyphosate decreased the distance covered and the mean speed of the animals and increased the number of rotations. We concluded that glyphosate causes damage in the embryonic, larval and adult stages of this species. These results are valid for zebrafish and can be applied to other freshwater fish species. Graphical abstract.

Elucidation of the binding mechanism of astragaloside IV derivative with human serum albumin and its cardiotoxicity in zebrafish embryos

LS-102 is a new derivative of astragaloside IV (AGS IV) that has been shown to possess potentially significant cardioprotective effects. However, there are no reports concerning its interaction with human serum albumin (HSA) and toxicology in vertebrates. The present investigation was undertaken to characterize the interaction of AGS IV and LS-102 with HSA using equilibrium dialysis and UHPLC-MS/MS methods, along with computational methods. Notably, the effects of AGS IV and LS-102 were studied in vivo using the zebrafish embryo model. Markers related to embryonic cardiotoxicity and thrombosis were evaluated. We showed that the plasma protein binding rate of AGS IV (94.04%–97.42%) was significantly higher than that of LS-102 (66.90%–69.35%). Through site marker competitive experiments and molecular docking, we found that AGS IV and LS-102 were located at the interface of subdomains IIA and IIIA, but the site I might be the primary binding site. Molecular dynamics revealed that AGS IV showed a higher binding free energy mainly due to the stronger hydrophobic and hydrogen bonding interactions. Moreover, the secondary structure implied no obvious effect on the protein structure and conformation during the binding of LS-102. LS-102 significantly ameliorated the astramizole-induced heart rate slowing, increased SV-BA spacing, and prevented arachidonic acid-induced thrombosis in zebrafish. To our knowledge, we are the first to reveal that LS-102 binds to HSA with reversible and moderate affinity, indicating its easy diffusion from the circulatory system to the target tissue, thereby providing significant insights into its pharmacokinetic and pharmacodynamic properties when spread in the human body. Our results also provide a reference for the rational clinical application of LS-102 in the cardiovascular field.

Effects and mechanisms of 6-hydroxykaempferol 3,6-di-O-glucoside-7-O-glucuronide from Safflower on endothelial injury in vitro and on thrombosis in vivo

Background: The florets of Carthamus tinctorius L. (Safflower) is an important traditional medicine for promoting blood circulation and removing blood stasis. However, its bioactive compounds and mechanism of action need further clarification.

Objective: This study aims to investigate the effect and possible mechanism of 6-hydroxykaempferol 3,6-di-O-glucoside-7-O-glucuronide (HGG) from Safflower on endothelial injury in vitro, and to verify its anti-thrombotic activity in vivo.

Methods: The endothelial injury on human umbilical vein endothelial cells (HUVECs) was induced by oxygen-glucose deprivation followed by reoxygenation (OGD/R). The effect of HGG on the proliferation of HUVECs under OGD/R was evaluated by MTT, LDH release, Hoechst-33342 staining, and Annexin V-FITC apoptosis assay. RNA-seq, RT-qPCR, Enzyme-linked immunosorbent assay and Western blot experiments were performed to uncover the molecular mechanism. The anti-thrombotic effect of HGG in vivo was evaluated using phenylhydrazine (PHZ)-induced zebrafish thrombosis model.

Results: HGG significantly protected OGD/R induced endothelial injury, and decreased HUVECs apoptosis by regulating expressions of hypoxia inducible factor-1 alpha (HIF-1α) and nuclear factor kappa B (NF-κB) at both transcriptome and protein levels. Moreover, HGG reversed the mRNA expression of pro-inflammatory cytokines including IL-1β, IL-6, and TNF-α, and reduced the release of IL-6 after OGD/R. In addition, HGG exhibited protective effects against PHZ-induced zebrafish thrombosis and improved blood circulation.

Conclusion: HGG regulates the expression of HIF-1α and NF-κB, protects OGD/R induced endothelial dysfunction in vitro and has anti-thrombotic activity in PHZ-induced thrombosis in vivo.

Embryonic exposure to butylparaben and propylparaben induced developmental toxicity and triggered anxiety-like neurobehavioral response associated with oxidative stress and apoptosis in the head of zebrafish larvae

Parabens are synthetic antimicrobial compounds used as a preservative for extending the shelf life of food, pharmaceutical and cosmetic products. The alkyl chain length of the paraben esters positively correlates with their antimicrobial property. Hence, long-chain paraben esters, namely butylparaben and propylparaben, are used in combination as they have better solubility and antimicrobial efficacy. Extensive use of parabens has now resulted in the ubiquitous presence of these compounds in various human and environmental matrices. During early life, exposure to environmental contaminants is known to cause oxidative-stress mediated apoptosis in developing organs. The brain being one of the high oxygen-consuming, metabolically active and lipid-rich organ, it is primarily susceptible to reactive oxygen species (ROS) and lipid peroxidation (LP) induced neuronal cell death. The primary cause for the impairment in cognitive and emotional neurobehvioural outcomes in neurodegenerative disease was found to be associated with neuronal apoptosis. The present study aimed to study butylparaben and propylparaben's effect on zebrafish during early embryonic stages. Besides this, the association between alteration in anxiety-like neurobehavioral response with oxidative stress and antioxidant status in head region was also studied. The study results showed variation in the toxic signature left by butylparaben and propylparaben on developmental parameters such as hatching rate, survival and non-lethal malformations in a time-dependent manner. Data from the light-dark preference test showed embryonic exposure to butylparaben and propylparaben to trigger anxiety-like behavior in zebrafish larvae. In addition, a significant increase in intracellular ROS and LP levels correlated with suppressed antioxidant enzymes: superoxide dismutases (SOD), catalases (CAT), Glutathione peroxidase (GPx), glutathione S-transferase (GST), and Glutathione (GSH) activity in the head region of the zebrafish larvae. Acetylcholinesterase (AChE) activity was also suppressed in the exposed groups, along with increased nitric oxide production. The overall observations show increased oxidative stress indices correlating with upregulated expression of apoptotic cells in a dose-dependent manner. Collectively, our findings reveal butylparaben and propylparaben as an anxiogenic neuroactive compound capable of inducing anxiety-like behavior through a mechanism involving oxidative-stress-induced apoptosis in the head of zebrafish larvae, which suggests a potential hazard to the early life of zebrafish and this can be extrapolated to human health as well.

Analysis of incidental findings in Qatar genome participants reveals novel functional variants in LMNA and DSP

In order to report clinically actionable incidental findings in genetic testing, the American College of Medical Genetics and Genomics (ACMG) recommended the evaluation of variants in 59 genes associated with highly penetrant mutations. However, there is a lack of epidemiological data on medically actionable rare variants in these genes in Arab populations. We used whole genome sequencing data from 6045 participants from the Qatar Genome Programme and integrated it with phenotypic data collected by the Qatar Biobank. We identified novel putative pathogenic variants in the 59 ACMG genes by filtering previously unrecorded variants based on computational prediction of pathogenicity, variant rarity and segregation evidence. We assessed the phenotypic associations of candidate variants in genes linked to cardiovascular diseases. Finally, we used a zebrafish knockdown and synthetic human mRNA co-injection assay to functionally characterize two of these novel variants. We assessed the zebrafish cardiac function in terms of heart rate, rhythm and hemodynamics, as well as the heart structure. We identified 52 492 novel variants, which have not been reported in global and disease-specific databases. A total of 74 novel variants were selected with potentially pathogenic effect. We prioritized two novel cardiovascular variants, DSP c.1841A > G (p.Asp614Gly) and LMNA c.326 T > G (p.Val109Gly) for functional characterization. Our results showed that both variants resulted in abnormal zebrafish heart rate, rhythm and structure. This study highlights medically actionable variants that are specific to the Middle Eastern Qatari population.

The metabolism of valerylfentanyl using human liver microsomes and zebrafish larvae

Valerylfentanyl, a novel synthetic opioid less potent than fentanyl, has been reported in biological samples, but there are limited studies on its pharmacokinetic properties. The goal of this study was to elucidate the metabolism of valerylfentanyl using an in vitro human liver microsome (HLM) model compared with an in vivo zebrafish model. Nineteen metabolites were detected with N-dealkylation-valeryl norfentanyl and hydroxylation as the major metabolic pathways. The major metabolites in HLMs were also detected in 30 day postfertilization zebrafish. An authentic liver specimen that tested positive for valerylfentanyl, among other opioids and stimulants, revealed the presence of a metabolite that shared transitions and retention time as the hydroxylated metabolite of valerylfentanyl but could not be confirmed without an authentic standard. 4-Anilino-N-phenethylpiperidine (4-ANPP), a common metabolite to other fentanyl analogs, was also detected. In this study, we elucidated the metabolic pathway of valerylfentanyl, confirmed two metabolites using standards, and demonstrated that the zebrafish model produced similar metabolites to the HLM model for opioids.

Cardiotoxicity of sanguinarine via regulating apoptosis and MAPK pathways in zebrafish and HL1 cardiomyocytes

Sanguinarine, a plant phytoalexin, possesses extensive biological activities including antimicrobial, insecticidal, antitumor, anti-inflammatory and anti-angiogenesis effect. But its cardiotoxicity has rarely been studied. Here, we assess the cardiotoxicity of sanguinarine in vivo using larval zebrafish from 48 hpf to 96 hpf. The results show that sanguinarine caused severe malformation and the dysfunction of the heart including reductions of heart rate, red blood cell number, blood flow dynamics, stroke volume and increase of SV-BA distance, subintestinal venous congestion. Further studies showed that apoptosis in the zebrafish heart region was observed after sanguinarine exposure using TUNEL assay and AO staining method. In addition, the genes, such as sox9b, myl7, nkx2.5 and bmp10, which play crucial parts in the development and the function of the heart, were changed after sanguinarine treatment. caspase3, caspase9, bax and bcl2, apoptosis-related genes, were also altered by sanguinarine. Further studies were performed to study the cardiotoxicity in vitro using cardiomyocytes HL1 cell line. The results showed that remarkable increase of apoptosis and ROS level in HL1 cells were induced by sanguinarine. Moreover, the MAPK pathway (JNK and P38) were notably enhanced and involved in the cardiotoxicity induced by sanguinarine. Our findings will provide better understanding of sanguinarine in the toxic effect on heart.

Lipid Profiles of the Heads of Four Shrimp Species by UPLC-Q-Exactive Orbitrap/MS and Their Cardiovascular Activities

Lipids are key factors in nutrition, structural function, metabolic features, and other biological functions. In this study, the lipids from the heads of four species of shrimp (Fenneropenaeus chinensis (FC), Penaeus japonicus (PJ), Penaeus vannamei (PV), and Procambarus clarkia (PCC)) were compared and characterized based on UPLC-Q-Exactive Orbitrap/MS. We compared the differences in lipid composition of four kinds of shrimp head using multivariate analysis. In addition, a zebrafish model was used to evaluate pro-angiogenic, anti-inflammatory, anti-thrombotic, and cardioprotective activities of the shrimp head lipids. The lipids from the four kinds of shrimp head had different degrees of pro-angiogenic activities, and the activities of PCC and PJ shrimp lipids were more significant than those of the other two species. Four lipid groups displayed strong anti-inflammatory activities. For antithrombotic activity, only PCC (25 μg/mL) and PV (100 μg/mL) groups showed obvious activity. In terms of cardioprotective activity, the four kinds of lipid groups significantly increased the zebrafish heart rhythms. The heart distances were shortened, except for those of the FC (100 μg/mL) and PJ (25 μg/mL) groups. Our comprehensive lipidomics analysis and bioactivity study of lipids from different sources could provide a basis for the better utilization of shrimp.

Acute toxicity of methomyl commercial formulation induces morphological and behavioral changes in larval zebrafish (Danio rerio)

The use of pesticides has continue grown over recent years, leading to several environmental and health concerns, such as the contamination of surface and groundwater resources and associated biota, potentially affecting populations that are not primary targets of these complex chemical mixtures. In this work, we investigate lethal and sublethal effects of acute exposure of methomyl commercial formulation in zebrafish embryo and larvae. Methomyl is a broad-spectrum carbamate insecticide and acaricide that acts primarily in acetylcholinesterase inhibition (AChE). Methomyl formulation 96 h-LC₅₀ was determined through the Fish Embryo Acute Toxicity Test (FET) and resulted in 1.2 g/L ± 0.04. Sublethal 6-day exposure was performed in six methomyl formulation concentrations (0.5; 1.0; 2.2; 4.8; 10.6; 23.3 mg/L) to evaluate developmental, physiological, morphological, behavioral, biochemical, and molecular endpoints of zebrafish early-development. Methomyl affected embryo hatching and larva morphology and behavior, especially in higher concentrations; resulting in smaller body and eyes size, failure in swimming bladder inflation, hypolocomotor activity, and concentration-dependent reduction of AChE activity; demonstrating methomyl strong acute toxicity and neurotoxic effect.

Ethoprophos induces cardiac toxicity in zebrafish embryos

Ethoprophos is an effective and widely pesticide that used in controlling nemathelminth and soil insect. However, ethoprophos has been frequently detected in environment and freshwater. The potential toxicity to aquatic organisms is still not be explored. In this study, zebrafish embryo model was used to evaluated the toxicity of ethoprophos during cardiovascular developmental process of zebrafish. Zebrafish embryos were separately exposed to 10 mg/L, 20 mg/L, 30 mg/L, 40 mg/L and 50 mg/L of ethoprophos exposure at 96 h post-fertilization (hpf), which induced cardiac defects, such as low heart rate, pericardium edema and long SV-BA distance, but had no influence to vascular development. Mechanistically, the expression of cardiac-related genes were abnormal. Moreover, ethoprophos exposure significantly increased oxidative stress in zebrafish embryos by inhibiting the production of antioxidant enzyme (SOD) and activating reactive oxygen species. Expectedly, some apoptosis genes were induced and the apoptotic cardiomyocytes were detected by acridine orange staining. In addition, ethoprophos exposure also inhibited the expression of genes in wnt signaling pathway, such as β-catenin, Axin2, GSK3β and Sox9b. BML284, an activator of wnt signaling pathway, can rescue the cardiotoxic effect of embryos. These results indicated that oxidative stress and blocking wnt signaling pathway were molecular basis of ethoprophos-induced injure in zebrafish. Generally, our study showed that ethoprophos exposure led to severe cardiotoxicity to zebrafish embryo.

Quantitative measurements of zebrafish heartrate and heart rate variability: A survey between 1990-2020

Zebrafish is an essential model organism for studying cardiovascular diseases, given its advantages of fast proliferation and high gene homology with humans. Zebrafish embryos/larvae are valuable experimental models used in toxicology studies to analyze drug toxicity, including hepatoxicity, nephrotoxicity and cardiotoxicity, as well as for drug discovery and drug safety screening in the preclinical stage. Heart rate (HR) serves as a functional endpoint in studies of cardiotoxicity, while heart rate variability (HRV) serves as an indicator of cardiac arrhythmia. Cardiotoxicity is a major cause of early and late termination of drug trials, so a more comprehensive understanding of zebrafish HR and HRV is important. This review summarized HR and HRV in a specific range of applications and fields, focusing on zebrafish heartbeat detection procedures, signal analysis technology and well-established commercial software, such as LabVIEW, Rvlpulse, and ZebraLab. We also compared HR detection algorithms and electrocardiography (ECG)-based methods of heart signal extraction. The relationship between HR and HRV was also systematically analyzed; HR was shown to have an inverse correlation with HRV. Applications to drug testing are also highlighted in this review. Furthermore, HR and HRV were shown to be regulated by the automatic nervous system; their connections with ECG measurements are also summarized herein.

Label-free quantitative measurement of cardiovascular dynamics in a zebrafish embryo using frequency-comb-referenced-quantitative phase imaging

SIGNIFICANCE

Real-time monitoring of the heart rate and blood flow is crucial for studying cardiovascular dysfunction, which leads to cardiovascular diseases.

AIM

This study aims at in-depth understanding of high-speed cardiovascular dynamics in a zebrafish embryo model for various biomedical applications via frequency-comb-referenced quantitative phase imaging (FCR-QPI).

APPROACH

Quantitative phase imaging (QPI) has emerged as a powerful technique in the field of biomedicine but has not been actively applied to the monitoring of circulatory/cardiovascular parameters, due to dynamic speckles and low frame rates. We demonstrate FCR-QPI to measure heart rate and blood flow in a zebrafish embryo. FCR-QPI utilizes a high-speed photodetector instead of a conventional camera, so it enables real-time monitoring of individual red blood cell (RBC) flow.

RESULTS

The average velocity of zebrafish's RBCs was measured from 192.5 to 608.8  μm  /  s at 24 to 28 hour-post-fertilization (hpf). In addition, the number of RBCs in a pulsatile blood flow was revealed to 16 cells/pulse at 48 hpf. The heart rates corresponded to 94 and 142 beats-per-minute at 24 and 48 hpf.

CONCLUSIONS

This approach will newly enable in-depth understanding of the cardiovascular dynamics in the zebrafish model and possible usage for drug discovery applications in biomedicine.

Evaluation of fentanyl toxicity and metabolism using a zebrafish model

The increased abuse of novel drugs has created a critical need for cheap and rapid in vivo models to understand whole organism drug-induced toxicity and metabolic impacts. One such model is zebrafish, which share many similarities to human. Assays have been developed for behavioral, toxicity, and metabolism elucidation following chemical exposure. The zebrafish model provides the advantage of assessing these parameters within a single study. Previous zebrafish studies have evaluated the behavioral effects of fentanyl, but not developmental toxicity and its relation to metabolism. In this study, we evaluate the effects of fentanyl on the development of wild-type (TL strain) zebrafish and its metabolism over 4 days. Fertilized eggs were exposed to six concentrations of fentanyl (0.01, 0.1, 1, 10, 50, and 100 μM) through embryo media incubated at 28-29°C. Observations included egg coagulation, somite formation, heartbeat, tail and yolk morphology, pericardial formation, and swim bladder inflation. The incubation media was analyzed for the presence of metabolites using a targeted metabolomics approach. Fentanyl concentration caused significant effects on survival and development, with notable defects to the tail, yolk, and pericardium at 50 and 100 μM. Despropionyl fentanyl (4-ANPP), β-hydroxy fentanyl, and norfentanyl were detected in zebrafish larvae. We present a single in vivo model to assess toxicity and metabolism of fentanyl exposure in a vertebrate model system. Our findings provide a foundation for further investigations into fentanyl's mechanism of action and translation to human drug exposure.

Advances in Cardiac Development and Regeneration Using Zebrafish as a Model System for High-Throughput Research

Heart disease is the leading cause of death in the United States and worldwide. Understanding the molecular mechanisms of cardiac development and regeneration will improve diagnostic and therapeutic interventions against heart disease. In this direction, zebrafish is an excellent model because several processes of zebrafish heart development are largely conserved in humans, and zebrafish has several advantages as a model organism. Zebrafish transcriptomic profiles undergo alterations during different stages of cardiac development and regeneration which are revealed by RNA-sequencing. ChIP-sequencing has detected genome-wide occupancy of histone post-translational modifications that epigenetically regulate gene expression and identified a locus with enhancer-like characteristics. ATAC-sequencing has identified active enhancers in cardiac progenitor cells during early developmental stages which overlap with occupancy of histone modifications of active transcription as determined by ChIP-sequencing. CRISPR-mediated editing of the zebrafish genome shows how chromatin modifiers and DNA-binding proteins regulate heart development, in association with crucial signaling pathways. Hence, more studies in this direction are essential to improve human health because they answer fundamental questions on cardiac development and regeneration, their differences, and why zebrafish hearts regenerate upon injury, unlike humans. This review focuses on some of the latest studies using state-of-the-art technology enabled by the elegant yet simple zebrafish.

Research('s) Sweet Hearts: Experimental Biomedical Models of Diabetic Cardiomyopathy

Diabetes and the often accompanying cardiovascular diseases including cardiomyopathy represent a complex disease, that is reluctant to reveal the molecular mechanisms and underlying cellular responses. Current research projects on diabetic cardiomyopathy are predominantly based on animal models, in which there are not only obvious advantages, such as genetics that can be traced over generations and the directly measurable influence of dietary types, but also not despisable disadvantages. Thus, many studies are built up on transgenic rodent models, which are partly comparable to symptoms in humans due to their genetic alterations, but on the other hand are also under discussion regarding their clinical relevance in the translation of biomedical therapeutic approaches. Furthermore, a focus on transgenic rodent models ignores spontaneously occurring diabetes in larger mammals (such as dogs or pigs), which represent with their anatomical similarity to humans regarding their cardiovascular situation appealing models for testing translational approaches. With this in mind, we aim to shed light on the currently most popular animal models for diabetic cardiomyopathy and, by weighing the advantages and disadvantages, provide decision support for future animal experimental work in the field, hence advancing the biomedical translation of promising approaches into clinical application.

Three-Dimensional Imaging of Whole-Body Zebrafish Revealed Lipid Disorders Associated with Niemann-Pick Disease Type C1

Imaging of lipids of whole-body specimens in two-dimensional (2D) analysis provides a global picture of the lipid changes in lipid-disturbed diseases, enabling a better understanding of lipid functions and lipid-modulation processes in different organs. However, 2D imaging of a single cross section can hardly characterize the whole-body lipid alterations. In this work, a three-dimensional matrix-assisted laser desorption/ionization mass spectrometry imaging (3D MALDI-MSI) approach was developed for analysis of whole-body zebrafish, for the first time, and applied to identify altered lipids and map their spatial distributions by using a zebrafish model of Niemann-Pick disease type C1 (NPC1), a neurovisceral lipid storage disorder causing both neurodegenerative disorder and visceral organ damage. The constructed 3D fish model provided comprehensive information on the 3D distribution of lipids of interest and allowed direct correlations between these lipids and organs of the fish. Obtained results revealed that several sphingolipids and phospholipids showed significant alterations and exhibited different localization patterns in various organs such as the brain, spinal cord, intestines, and liver-spleen region in the npc1 gene mutant fish compared to those of the wild type. The whole-body 3D MALDI-MSI approach revealed unique lipid signatures for different NPC1-affected organs, which might offer insights into the link between the impaired lipid storage and subsequent clinical symptoms, such as neurodegeneration and hepatosplenomegaly.

Di-2-ethylhexyl phthalate induces heart looping disorders during zebrafish development

Di-2-ethylhexyl phthalate (DEHP) is a type of plasticizer widely used in industry. It is well-known for its toxic effects to endocrine and reproductive systems and has been detected in amniotic fluid and placenta. In the present study, we explored the effects of DEHP on heart development by using zebrafish as a model organism. DEHP (0.02 pg) was injected into the yolk sac of zebrafish embryos at the one-cell stage. No significant difference was found in embryonic lethality between control and DEHP groups at 1-day postfertilization (dpf), but mortality significantly increased in DEHP groups at 2 and 3 dpf. The average heart rate was significantly reduced in the surviving DEHP-treated zebrafish larvae at 3 and 4 dpf. In addition, massive pericardial edema was found in DEHP-treated zebrafish (12.6 ± 1.5%), which was significantly higher than that of the control group. Serious heart looping disorder was also observed in DEHP-treated larvae, mainly manifested with an elongated atrial-ventricular distance. Moreover, the expression of heart development transcription factors was affected by DEHP injection. Real-time polymerase chain reaction confirmed that five transcription factors (hand2, tp53, mef2c, esr1, and tbx18) were significantly downregulated in the DEHP group at 2 dpf, and three transcription factors (zic3, tcf21, and gata4) were significantly upregulated. Our results emphasize the need for the development of a nontoxic plasticizer to prevent possible deleterious effects on humans and other life-forms.

A Heterozygous Mutation in Cardiac Troponin T Promotes Ca2+ Dysregulation and Adult Cardiomyopathy in Zebrafish

Cardiomyopathies are a group of heterogeneous diseases that affect the muscles of the heart, leading to early morbidity and mortality in young and adults. Genetic forms of cardiomyopathy are caused predominantly by mutations in structural components of the cardiomyocyte sarcomeres, the contractile units of the heart, which includes cardiac Troponin T (TnT). Here, we generated mutations with CRISPR/Cas9 technology in the zebrafish tnnt2a gene, encoding cardiac TnT, at a mutational “hotspot” site to establish a zebrafish model for genetic cardiomyopathies. We found that a heterozygous tnnt2a mutation deleting Arginine at position 94 and Lysine at position 95 of TnT causes progressive cardiac structural changes resulting in heart failure. The cardiac remodeling is presented by an enlarged atrium, decreased ventricle size, increased myocardial stress as well as increased fibrosis. As early as five days post fertilization, larvae carrying the TnT RK94del mutation display diastolic dysfunction and impaired calcium dynamics related to increased Ca²⁺ sensitivity. In conclusion, adult zebrafish with a heterozygous TnT-RK94del mutation develop cardiomyopathy as seen in patients with TnT mutations and therefore represent a promising model to study disease mechanisms and to screen for putative therapeutic compounds.

The toxicity mechanism of toxic compounds from Euphorbiae pekinensis Radix on zebrafish embryos

Euphorbiae pekinensis Radix (EP) is effective in treating various diseases, but it's toxicity is a major obstacle in use in clinical. Although EP was processed with vinegar to reduce it's toxicity, the detailed mechanism of toxicity in EP have not been clearly delineated. This study investigate the toxicity attenuation-mechanism of Euphorbiae pekinensis after being processed with vinegar (VEP) and the toxic mechanism of four compounds from EP on zebrafish embryos. The contents of four compounds decreased obviously in VEP. Correspondingly, slower development on embryos can be seen as some symptoms like reduction of heart rate, liver area and gastrointestinal peristalsis after exposed to the compounds. Some obvious pathological signals such as pericardial edema and yolk sac edema were observed. Furthermore, the compounds could increase the contents of MDA and GSH-PX and induce oxidative damage by inhibiting the activity of SOD. Also, four compounds could provoke apoptosis by up-regulating the expression level of p53, MDM2, Bax, Bcl-2 and activating the activity of caspase-3, caspase-9. In conclusion, the four compounds play an important role in the toxicity attenuation effects of VEP, which may be related to the apoptosis induction and oxidative damage. This would contribute to the clinical application and further toxicity-reduction mechanism research.

Bifenazate exposure induces cardiotoxicity in zebrafish embryos

Bifenazate is a novel acaricide for selective foliar spraying and is widely used to control mites in agricultural production. However, its toxicity to aquatic organisms is unknown. Here, a zebrafish model was used to study bifenazate toxicity to aquatic organisms. Exposure to bifenazate was found to cause severe cardiotoxicity in zebrafish embryos, along with disorders in the gene expression related to heart development. Bifenazate also caused oxidative stress. Cardiotoxicity caused by bifenazate was partially rescued by astaxanthin (an antioxidant), accompanied by cardiac genes and oxidative stress-related indicators becoming normalized. Our results showed that exposure to bifenazate can significantly change the ATPase activity and gene expression levels of the calcium signaling pathway. These led to heart failure, in which the blood accumulated outside the heart without entering it, eventually leading to death. The results indicated that bifenazate exposure caused cardiotoxicity in zebrafish embryos through the induction of oxidative stress and inhibition of the calcium signaling pathway.

The SARS-CoV-2 receptor and other key components of the Renin-Angiotensin-Aldosterone System related to COVID-19 are expressed in enterocytes in larval zebrafish

People with underlying conditions, including hypertension, obesity, and diabetes, are especially susceptible to negative outcomes after infection with coronavirus SARS-CoV-2, which causes COVID-19. Hypertension and respiratory inflammation are exacerbated by the Renin-Angiotensin-Aldosterone System (RAAS), which normally protects from rapidly dropping blood pressure via Angiotensin II (Ang II) produced by the enzyme Ace. The Ace paralog Ace2 degrades Ang II, counteracting its chronic effects, and serves as the SARS-CoV-2 receptor. Ace, the coronavirus, and COVID-19 comorbidities all regulate Ace2, but we do not yet understand how. To exploit zebrafish (Danio rerio) to help understand the relationship of the RAAS to COVID-19, we must identify zebrafish orthologs and co-orthologs of human RAAS genes and understand their expression patterns. To achieve these goals, we conducted genomic and phylogenetic analyses and investigated single cell transcriptomes. Results showed that most human RAAS genes have one or more zebrafish orthologs or co-orthologs. Results identified a specific type of enterocyte as the specific site of expression of zebrafish orthologs of key RAAS components, including Ace, Ace2, Slc6a19 (SARS-CoV-2 co-receptor), and the Angiotensin-related peptide cleaving enzymes Anpep (receptor for the common cold coronavirus HCoV-229E), and Dpp4 (receptor for the Middle East Respiratory Syndrome virus, MERS-CoV). Results identified specific vascular cell subtypes expressing Ang II receptors, apelin, and apelin receptor genes. These results identify genes and cell types to exploit zebrafish as a disease model for understanding mechanisms of COVID-19.

A zebrafish forward genetic screen identifies an indispensable threonine residue in the kinase domain of PRKD2

Protein kinase D2 belongs to a family of evolutionarily conserved enzymes regulating several biological processes. In a forward genetic screen for zebrafish cardiovascular mutants, we identified a mutation in the prkd2 gene. Homozygous mutant embryos develop as wild type up to 36 h post-fertilization and initiate blood flow, but fail to maintain it, resulting in a complete outflow tract stenosis. We identified a mutation in the prkd2 gene that results in a T757A substitution at a conserved residue in the kinase domain activation loop (T714A in human PRKD2) that disrupts catalytic activity and drives this phenotype. Homozygous mutants survive without circulation for several days, allowing us to study the extreme phenotype of no intracardiac flow, in the background of a functional heart. We show dysregulation of atrioventricular and outflow tract markers in the mutants and higher sensitivity to the Calcineurin inhibitor, Cyclosporin A. Finally we identify TBX5 as a potential regulator of PRKD2. Our results implicate PRKD2 catalytic activity in outflow tract development in zebrafish.

This article has an associated First Person interview with the first author of the paper.

Summary: We identified, through a zebrafish forward screen, an evolutionarily conserved residue in the catalytic domain of protein kinase D2 and its homologues.

Alternative strategies in cardiac preclinical research and new clinical trial formats

An efficient and safe drug development process is crucial for the establishment of new drugs on the market aiming to increase quality of life and life-span of our patients. Despite technological advances in the past decade, successful launches of drug candidates per year remain low. We here give an overview about some of these advances and suggest improvements for implementation to boost preclinical and clinical drug development with a focus on the cardiovascular field. We highlight advantages and disadvantages of animal experimentation and thoroughly review alternatives in the field of three-dimensional cell culture as well as preclinical use of spheroids and organoids. Microfluidic devices and their potential as organ-on-a-chip systems, as well as the use of living animal and human cardiac tissues are additionally introduced. In the second part, we examine recent gold standard randomized clinical trials and present possible modifications to increase lead candidate throughput: adaptive designs, master protocols, and drug repurposing. In silico and N-of-1 trials have the potential to redefine clinical drug candidate evaluation. Finally, we briefly discuss clinical trial designs during pandemic times.

Zebrafish (Danio rerio) as an excellent vertebrate model for the development, reproductive, cardiovascular, and neural and ocular development toxicity study of hazardous chemicals

In the past decades, the type of chemicals has gradually increased all over the world, and many of these chemicals may have a potentially toxic effect on human health. The zebrafish, as an excellent vertebrate model, is increasingly used for assessing chemical toxicity and safety. This review summarizes the efficacy of zebrafish as a model for the study of developmental toxicity, reproductive toxicity, cardiovascular toxicity, neurodevelopmental toxicity, and ocular developmental toxicity of hazardous chemicals, and the transgenic zebrafish as biosensors are used to detect the environmental pollutants.

Heart Development and Regeneration in Non-mammalian Model Organisms

Cardiovascular disease is a serious threat to human health and a leading cause of mortality worldwide. Recent years have witnessed exciting progress in the understanding of heart formation and development, enabling cardiac biologists to make significant advance in the field of therapeutic heart regeneration. Most of our understanding of heart development and regeneration, including the genes and signaling pathways, are driven by pioneering works in non-mammalian model organisms, such as fruit fly, fish, frog, and chicken. Compared to mammalian animal models, non-mammalian model organisms have special advantages in high-throughput applications such as disease modeling, drug discovery, and cardiotoxicity screening. Genetically engineered animals of cardiovascular diseases provide valuable tools to investigate the molecular and cellular mechanisms of pathogenesis and to evaluate therapeutic strategies. A large number of congenital heart diseases (CHDs) non-mammalian models have been established and tested for the genes and signaling pathways involved in the diseases. Here, we reviewed the mechanisms of heart development and regeneration revealed by these models, highlighting the advantages of non-mammalian models as tools for cardiac research. The knowledge from these animal models will facilitate therapeutic discoveries and ultimately serve to accelerate translational medicine.

Famoxadone-cymoxanil induced cardiotoxicity in zebrafish embryos

Famoxadone-cymoxanil is a new protective and therapeutic fungicide, but little research has been done on it or its toxicity in aquatic organisms. In this study, we used zebrafish to investigate the cardiotoxicity of famoxadone-cymoxanil and the potential mechanisms involved. Zebrafish embryos were exposed to different concentrations of famoxadone-cymoxanil until 72 h post-fertilization (hpf), then changes of heart morphology in zebrafish embryos were observed. We also detected the levels of oxidative stress, myocardial-cell proliferation and apoptosis, ATPase activity, and the expression of genes related to the cardiac development and calcium-signaling pathway. After famoxadone-cymoxanil exposure, pericardial edema, cardiac linearization, and reductions in the heart rate and cardiac output positively correlated with concentration. Although myocardial-cell apoptosis was not detected, proliferation of the cells was severely reduced and ATPase activity significantly decreased, resulting in a severe deficiency in heart function. In addition, indicators of oxidative stress changed significantly after exposure of the embryos to the fungicide. To better understand the possible molecular mechanisms of cardiovascular toxicity in zebrafish, we studied the transcriptional levels of cardiac development, calcium-signaling pathways, and genes associated with myocardial contractility. The mRNA expression levels of key genes in heart development were significantly down-regulated, while the expression of genes related to the calcium-signaling pathway (ATPase [atp2a1], cardiac troponin C [tnnc1a], and calcium channel [cacna1a]) was significantly inhibited. Expression of klf2a, a major endocardial flow-responsive gene, was also significantly inhibited. Mechanistically, famoxadone-cymoxanil toxicity might be due to the downregulation of genes associated with the calcium-signaling pathway and cardiac muscle contraction. Our results found that famoxadone-cymoxanil exposure causes cardiac developmental toxicity and severe energy deficiency in zebrafish.

Identification of Potentially Relevant Genes for Excessive Exercise-Induced Pathological Cardiac Hypertrophy in Zebrafish

Exercise-induced cardiac remodeling has aroused public concern for some time, as sudden cardiac death is known to occur in athletes; however, little is known about the underlying mechanism of exercise-induced cardiac injury. In the present study, we established an excessive exercise-induced pathologic cardiac hypertrophy model in zebrafish with increased myocardial fibrosis, myofibril disassembly, mitochondrial degradation, upregulated expression of the pathological hypertrophy marker genes in the heart, contractile impairment, and cardiopulmonary function impairment. High-throughput RNA-seq analysis revealed that the differentially expressed genes were enriched in the regulation of autophagy, protein folding, and degradation, myofibril development, angiogenesis, metabolic reprogramming, and insulin and FoxO signaling pathways. FOXO proteins may be the core mediator of the regulatory network needed to promote the pathological response. Further, PPI network analysis showed that pik3c3, gapdh, fbox32, fzr1, ubox5, lmo7a, kctd7, fbxo9, lonrf1l, fbxl4, nhpb2l1b, nhp2, fbl, hsp90aa1.1, snrpd3l, dhx15, mrto4, ruvbl1, hspa8b, and faub are the hub genes that correlate with the pathogenesis of pathological cardiac hypertrophy. The underlying regulatory pathways and cardiac pressure-responsive molecules identified in the present study will provide valuable insights for the supervision and clinical treatment of pathological cardiac hypertrophy induced by excessive exercise.

Modeling Inherited Cardiomyopathies in Adult Zebrafish for Precision Medicine

Cardiomyopathies are a highly heterogeneous group of heart muscle disorders. More than 100 causative genes have been linked to various cardiomyopathies, which explain about half of familial cardiomyopathy cases. More than a dozen candidate therapeutic signaling pathways have been identified; however, precision medicine is not being used to treat the various types of cardiomyopathy because knowledge is lacking for how to tailor treatment plans for different genetic causes. Adult zebrafish (Danio rerio) have a higher throughout than rodents and are an emerging vertebrate model for studying cardiomyopathy. Herein, we review progress in the past decade that has proven the feasibility of this simple vertebrate for modeling inherited cardiomyopathies of distinct etiology, identifying effective therapeutic strategies for a particular type of cardiomyopathy, and discovering new cardiomyopathy genes or new therapeutic strategies via a forward genetic approach. On the basis of this progress, we discuss future research that would benefit from integrating this emerging model, including discovery of remaining causative genes and development of genotype-based therapies. Studies using this efficient vertebrate model are anticipated to significantly accelerate the implementation of precision medicine for inherited cardiomyopathies.

An Overview of Methods for Cardiac Rhythm Detection in Zebrafish

The heart is the most important muscular organ of the cardiovascular system, which pumps blood and circulates, supplying oxygen and nutrients to peripheral tissues. Zebrafish have been widely explored in cardiotoxicity research. For example, the zebrafish embryo has been used as a human heart model due to its body transparency, surviving several days without circulation, and facilitating mutant identification to recapitulate human diseases. On the other hand, adult zebrafish can exhibit the amazing regenerative heart muscle capacity, while adult mammalian hearts lack this potential. This review paper offers a brief description of the major methodologies used to detect zebrafish cardiac rhythm at both embryonic and adult stages. The dynamic pixel change method was mostly performed for the embryonic stage. Other techniques, such as kymography, laser confocal microscopy, artificial intelligence, and electrocardiography (ECG) have also been applied to study heartbeat in zebrafish embryos. Nevertheless, ECG is widely used for heartbeat detection in adult zebrafish since ECG waveforms' similarity between zebrafish and humans is prominent. High-frequency ultrasound imaging (echocardiography) and modern electronic sensor tag also have been proposed. Despite the fact that each method has its benefits and limitations, it is proved that zebrafish have become a promising animal model for human cardiovascular disease, drug pharmaceutical, and toxicological research. Using those tools, we conclude that zebrafish behaviors as an excellent small animal model to perform real-time monitoring for the developmental heart process with transparent body appearance, to conduct the in vivo cardiovascular performance and gene function assays, as well as to perform high-throughput/high content drug screening.

An intestinal cell type in zebrafish is the nexus for the SARS-CoV-2 receptor and the Renin-Angiotensin-Aldosterone System that contributes to COVID-19 comorbidities

People with underlying conditions, including hypertension, obesity, and diabetes, are especially susceptible to negative outcomes after infection with the coronavirus SARS-CoV-2. These COVID-19 comorbidities are exacerbated by the Renin-Angiotensin-Aldosterone System (RAAS), which normally protects from rapidly dropping blood pressure or dehydration via the peptide Angiotensin II (Ang II) produced by the enzyme Ace. The Ace paralog Ace2 degrades Ang II, thus counteracting its chronic effects. Ace2 is also the SARS-CoV-2 receptor. Ace , the coronavirus, and COVID-19 comorbidities all regulate Ace2 , but we don't yet understand how. To exploit zebrafish ( Danio rerio ) as a disease model to understand mechanisms regulating the RAAS and its relationship to COVID-19 comorbidities, we must first identify zebrafish orthologs and co-orthologs of human RAAS genes, and second, understand where and when these genes are expressed in specific cells in zebrafish development. To achieve these goals, we conducted genomic analyses and investigated single cell transcriptomes. Results showed that most human RAAS genes have an ortholog in zebrafish and some have two or more co-orthologs. Results further identified a specific intestinal cell type in zebrafish larvae as the site of expression for key RAAS components, including Ace, Ace2, the coronavirus co-receptor Slc6a19, and the Angiotensin-related peptide cleaving enzymes Anpep and Enpep. Results also identified specific vascular cell subtypes as expressing Ang II receptors, apelin , and apelin receptor genes. These results identify specific genes and cell types to exploit zebrafish as a disease model for understanding the mechanisms leading to COVID-19 comorbidities.

SUMMARY STATEMENT

Genomic analyses identify zebrafish orthologs of the Renin-Angiotensin-Aldosterone System that contribute to COVID-19 comorbidities and single-cell transcriptomics show that they act in a specialized intestinal cell type.

MicroRNA-375 overexpression disrupts cardiac development of Zebrafish (Danio rerio) by targeting notch2

MicroRNAs are small noncoding RNAs that are important for proper cardiac development. In our previous study of fetuses with ventricular septal defects, we discovered that microRNA-375 (miR-375) is obviously upregulated compared with that in healthy controls. Our study also confirmed that miR-375 is crucial for cardiomyocyte differentiation. This research mainly focused on the biological significance and mechanism of miR-375 using a zebrafish model. We injected zebrafish embryos with 1-2 nl of a miR-375 mimic at various concentrations (0/2/4/8 μM) or with negative control. The deformation and mortality rates were separately assessed. The different expression levels of miR-375 and related genes were examined by qRT-PCR, and luciferase assays and in situ hybridization were used to clarify the mechanism of miR-375 during embryonic development. Overexpression of miR-375 disrupted the cardiac development of zebrafish embryos. Disruption of miR-375 led to a decreased heart rate, pericardial edema, and abnormal cardiac looping. Various genes involved in cardiac development were downregulated due to the overexpression of miR-375. Moreover, the NOTCH signaling pathway was affected, and the luciferase reporter gene assays confirmed notch2, which was predicted by bioinformatics analysis, as the target gene of miR-375. Our findings demonstrated that the overexpression of miR-375 is detrimental to embryonic development, including cardiac development, and can partially simulate a multisystemic disorder. MiR-375 has an important role during cardiac morphogenesis of zebrafish embryos by targeting notch2, indicating its potential as a diagnostic marker.

BVES downregulation in non-syndromic tetralogy of fallot is associated with ventricular outflow tract stenosis

BVES is a transmembrane protein, our previous work demonstrated that single nucleotide mutations of BVES in tetralogy of fallot (TOF) patients cause a downregulation of BVES transcription. However, the relationship between BVES and the pathogenesis of TOF has not been determined. Here we reported our research results about the relationship between BVES and the right ventricular outflow tract (RVOT) stenosis. BVES expression was significantly downregulated in most TOF samples compared with controls. The expression of the second heart field (SHF) regulatory network genes, including NKX2.5, GATA4 and HAND2, was also decreased in the TOF samples. In zebrafish, bves knockdown resulted in looping defects and ventricular outflow tract (VOT) stenosis, which was mostly rescued by injecting bves mRNA. bves knockdown in zebrafish also decreased the expression of SHF genes, such as nkx2.5, gata4 and hand2, consistent with the TOF samples` results. The dual-fluorescence reporter system analysis showed that BVES positively regulated the transcriptional activity of GATA4, NKX2.5 and HAND2 promoters. In zebrafish, nkx2.5 mRNA partially rescued VOT stenosis caused by bves knockdown. These results indicate that BVES downregulation may be associated with RVOT stenosis of non-syndromic TOF, and bves is probably involved in the development of VOT in zebrafish.