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Yang D, Jian Z, Tang C, Chen Z, Zhou Z, Zheng L, Peng X. Zebrafish Congenital Heart Disease Models: Opportunities and Challenges. Int J Mol Sci 2024; 25:5943. [PMID: 38892128 PMCID: PMC11172925 DOI: 10.3390/ijms25115943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2024] [Revised: 05/18/2024] [Accepted: 05/23/2024] [Indexed: 06/21/2024] Open
Abstract
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.
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2
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McDonnell P, Fornell P, Ponce S, Dyer L. Baseline heart rate in infants with prenatal alcohol exposure: A systematic review and independent analysis. Birth Defects Res 2023; 115:474-487. [PMID: 36515170 DOI: 10.1002/bdr2.2135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/22/2022] [Accepted: 11/23/2022] [Indexed: 12/15/2022]
Abstract
BACKGROUND Infants with fetal alcohol syndrome exhibit a range of developmental anomalies, many related to the heart (e.g., decreased heart rate variability). However, the baseline heart rate in this population remains unclear. We hypothesized that the age at which heart rate was measured or the age during exposure to alcohol affects the baseline heart rate. METHODS First, we conducted a systemic review to determine the published heart rate of infants with prenatal alcohol exposure (PAE). Exclusion criteria included potentially confounding factors, including the commonly associated phenotypes of small for gestational age and premature birth. Risk of bias was evaluated based on case study limitations, and data were compared with established heart rate norms. Then, we evaluated the precise age at heart rate measurement using existing datasets from the Collaborative Initiative on Fetal Alcohol Spectrum Disorders and the Maternal Lifestyle Study. RESULTS Based on the weighted means of six studies, the baseline heart rate was 4.6 bpm higher in infants with PAE (n = 253) than in control infants (n = 152). Using the individual patient data, baseline heart rates were similar between age-matched infants with PAE and control infants who were born full-term and showed no signs of growth restriction (ANOVA, p > .05; n = 49-124 infants per age and exposure). CONCLUSIONS A systematic literature review suggested that heart rate is elevated in infants with PAE, but these findings are limited by the number of studies and how few studies included control infants. The analysis of individual patient data indicates that infants with PAE have normal baseline heart rates. This knowledge may help clinicians detect changes in cardiac function in infants with PAE. (Registered via PROSPERO, #CRD42020191212.).
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Affiliation(s)
- Peyton McDonnell
- Department of Biology, University of Portland, Portland, Oregon, USA
| | - Pia Fornell
- Department of Biology, University of Portland, Portland, Oregon, USA
| | - Sarah Ponce
- Department of Biology, University of Portland, Portland, Oregon, USA
| | - Laura Dyer
- Department of Biology, University of Portland, Portland, Oregon, USA
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3
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Alsakran A, Kudoh T. Zebrafish as a Model for Fetal Alcohol Spectrum Disorders. Front Pharmacol 2022; 12:721924. [PMID: 34975467 PMCID: PMC8714738 DOI: 10.3389/fphar.2021.721924] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 10/25/2021] [Indexed: 11/29/2022] Open
Abstract
In this review, we will discuss zebrafish as a model for studying mechanisms of human fetal alcohol spectrum disorders (FASDs). We will overview the studies on FASDs so far and will discuss with specific focus on the mechanisms by which alcohol alters cell migration during the early embryogenesis including blastula, gastrula, and organogenesis stages which later cause morphological defects in the brain and other tissues. FASDs are caused by an elevated alcohol level in the pregnant mother’s body. The symptoms of FASDs include microcephaly, holoprosencephaly, craniofacial abnormalities, and cardiac defects with birth defect in severe cases, and in milder cases, the symptoms lead to developmental and learning disabilities. The transparent zebrafish embryo offers an ideal model system to investigate the genetic, cellular, and organismal responses to alcohol. In the zebrafish, the effects of alcohol were observed in many places during the embryo development from the stem cell gene expression at the blastula/gastrula stage, gastrulation cell movement, morphogenesis of the central nervous system, and neuronal development. The data revealed that ethanol suppresses convergence, extension, and epiboly cell movement at the gastrula stage and cause the failure of normal neural plate formation. Subsequently, other cell movements including neurulation, eye field morphogenesis, and neural crest migration are also suppressed, leading to the malformation of the brain and spinal cord, including microcephaly, cyclopia, spinal bifida, and craniofacial abnormalities. The testing cell migration in zebrafish would provide convenient biomarkers for the toxicity of alcohol and other related chemicals, and investigate the molecular link between the target signaling pathways, following brain development.
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Affiliation(s)
- Amena Alsakran
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Tetsuhiro Kudoh
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom.,University of Exeter, Exeter, United Kingdom
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4
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Fernandes Y, Lovely CB. Zebrafish models of fetal alcohol spectrum disorders. Genesis 2021; 59:e23460. [PMID: 34739740 DOI: 10.1002/dvg.23460] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 12/14/2022]
Abstract
Fetal alcohol spectrum disorder (FASD) describes a wide range of structural deficits and cognitive impairments. FASD impacts up to 5% of children born in the United States each year, making ethanol one of the most common teratogens. Due to limitations and ethical concerns, studies in humans are limited in their ability to study FASD. Animal models have proven critical in identifying and characterizing the mechanisms underlying FASD. In this review, we will focus on the attributes of zebrafish that make it a strong model in which to study ethanol-induced developmental defects. Zebrafish have several attributes that make it an ideal model in which to study FASD. Zebrafish produced large numbers of externally fertilized, translucent embryos. With a high degree of genetic amenability, zebrafish are at the forefront of identifying and characterizing the gene-ethanol interactions that underlie FASD. Work from multiple labs has shown that embryonic ethanol exposures result in defects in craniofacial, cardiac, ocular, and neural development. In addition to structural defects, ethanol-induced cognitive and behavioral impairments have been studied in zebrafish. Building upon these studies, work has identified ethanol-sensitive loci that underlie the developmental defects. However, analyses show there is still much to be learned of these gene-ethanol interactions. The zebrafish is ideally suited to expand our understanding of gene-ethanol interactions and their impact on FASD. Because of the conservation of gene function between zebrafish and humans, these studies will directly translate to studies of candidate genes in human populations and allow for better diagnosis and treatment of FASD.
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Affiliation(s)
- Yohaan Fernandes
- Department of Biology, University of South Dakota, Vermillion, South Dakota, USA
| | - C Ben Lovely
- Department of Biochemistry and Molecular Genetics, Alcohol Research Center, University of Louisville, Louisville, Kentucky, USA
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5
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Pinheiro‐da‐Silva J, Luchiari AC. Embryonic ethanol exposure on zebrafish early development. Brain Behav 2021; 11:e02062. [PMID: 33939334 PMCID: PMC8213935 DOI: 10.1002/brb3.2062] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/01/2020] [Accepted: 01/11/2021] [Indexed: 12/20/2022] Open
Abstract
INTRODUCTION Embryonic exposure to ethanol leads to a condition of physical, behavioral, and cognitive deficiencies named fetal alcohol spectrum disorders (FASD). The most severe variations are in fetal alcohol syndrome (FAS), which is easier to diagnose and not studied in animal models. On the other side, the pFAS (partial fetal alcohol syndrome) includes cases of alcohol-related congenital disabilities and neurodevelopmental disorder with an inconclusive diagnosis. In recent years, the zebrafish has become a valuable model to study FASD and its variations. METHODS This study characterizes the zebrafish embryonic and larval development after low and moderate ethanol concentration exposure. Fish eggs were exposed to 0.0%, 0.25%, 0.5%, and 1.0% ethanol at 24 hr postfertilization, and embryonic development was observed every 8 hr up to 120 hpf. It evaluated movements, phenotypic abnormalities, hatching, cardiac function and heartbeat frequency, larvae length at 120 hpf, and the apoptotic cells' fluorescence stained with acridine orange. RESULTS Embryonic exposure to 0.5% and 1% ethanol presented reduced body size, decreased heartbeat rate, higher numbers of apoptotic cells, and hatching time differences. CONCLUSIONS Our results suggest any ethanol exposure during embryogenesis can be harmful and reinforces zebrafish as a suitable model for fetal alcohol spectrum disorders (FASD).
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Affiliation(s)
| | - Ana Carolina Luchiari
- Physiology and Behavior DepartmentFederal University of Rio Grande do NorteNatalBrazil
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6
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Fang Y, Sun Y, Luo C, Gu J, Shi Z, Lu G, Silvestre JS, Chen Z. Evaluation of cardiac dysfunction in adult zebrafish using high frequency echocardiography. Life Sci 2020; 253:117732. [PMID: 32360570 DOI: 10.1016/j.lfs.2020.117732] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/18/2020] [Accepted: 04/25/2020] [Indexed: 11/20/2022]
Abstract
AIMS Recently, the zebrafish has gained attention as an innovative experimental model to decipher molecular and cellular mechanisms involved in cardiovascular development and diseases. Nevertheless, the use of zebrafish models has been challenged because the transparency of these fish, which allows for accurate cardiac evaluation, disappears in adulthood. In this study, the epicardial outline method was performed to investigate the feasibility of echocardiography in assessing cardiac function in pathological adult zebrafish. MATERIALS AND METHODS We attempted to estimate heart failure in adult zebrafish treated with three distinct regulators of cardiac function: phenylhydrazine hydrochloride (PHZ), doxorubicin (DOX), and ethanol. B-mode and Doppler images were evaluated at frequencies of up to 50 MHz and 40 MHz, respectively. The correlation between alterations in cardiac function, haemoglobin concentration, and myocardial histopathology were assessed. KEY FINDINGS Cardiac output (CO) in PHZ-treated zebrafish was significantly higher than that in control zebrafish (151 ± 67 vs. 84 ± 37 μl/min, P = 0.004), whereas ejection fraction (EF) was lower (36.3 ± 10.9 vs. 50.9 ± 8.7%, P < 0.001), indicating typical high output heart failure derived from anaemia. Additionally, ventricular dysfunction in DOX-treated zebrafish was characterised by low CO (57 ± 38 μl/min) and EF (28.8 ± 10.4%), accompanied by an enlarged ventricle in diastole and systole, representing low output heart failure. For ethanol-treated zebrafish, EF was markedly reduced (39.6 ± 7.2%) indicating a dilated heart, while CO remained unchanged (90 ± 40 μl/min). SIGNIFICANCE The epicardial outline method is an effective way of using echocardiography to assess cardiac dysfunction in pathological adult zebrafish, unlocking a major bottleneck in this research field with limited cardiac functional assays.
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Affiliation(s)
- Yuehua Fang
- Department of Cardiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Yanyi Sun
- Department of Cardiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Chen Luo
- Department of Cardiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Jianing Gu
- Department of Cardiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Zhongwei Shi
- Department of Cardiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Guoping Lu
- Department of Cardiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | | | - Zhenyue Chen
- Department of Cardiology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
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7
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Shrestha R, Lieberth J, Tillman S, Natalizio J, Bloomekatz J. Using Zebrafish to Analyze the Genetic and Environmental Etiologies of Congenital Heart Defects. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1236:189-223. [PMID: 32304074 DOI: 10.1007/978-981-15-2389-2_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Congenital heart defects (CHDs) are among the most common human birth defects. However, the etiology of a large proportion of CHDs remains undefined. Studies identifying the molecular and cellular mechanisms that underlie cardiac development have been critical to elucidating the origin of CHDs. Building upon this knowledge to understand the pathogenesis of CHDs requires examining how genetic or environmental stress changes normal cardiac development. Due to strong molecular conservation to humans and unique technical advantages, studies using zebrafish have elucidated both fundamental principles of cardiac development and have been used to create cardiac disease models. In this chapter we examine the unique toolset available to zebrafish researchers and how those tools are used to interrogate the genetic and environmental contributions to CHDs.
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Affiliation(s)
- Rabina Shrestha
- Department of Biology, University of Mississippi, Oxford, MS, USA
| | - Jaret Lieberth
- Department of Biology, University of Mississippi, Oxford, MS, USA
| | - Savanna Tillman
- Department of Biology, University of Mississippi, Oxford, MS, USA
| | - Joseph Natalizio
- Department of Biology, University of Mississippi, Oxford, MS, USA
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8
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Lovely CB. Animal models of gene-alcohol interactions. Birth Defects Res 2019; 112:367-379. [PMID: 31774246 DOI: 10.1002/bdr2.1623] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 11/09/2019] [Indexed: 12/16/2022]
Abstract
Most birth defects arise from complex interactions between multiple genetic and environmental factors. However, our current understanding of how these interactions and their contributions affect birth defects remains incomplete. Human studies are limited in their ability to identify the fundamental causes of birth defects due to ethical and practical limitations. Animal models provide a great number of resources not available to human studies and they have been critical in advancing our understanding of birth defects and the complex interactions that underlie them. In this review, we discuss the use of animal models in the context of gene-environment interactions that underlie birth defects. We focus on alcohol which is the most common environmental factor associated with birth defects. Prenatal alcohol exposure leads to a wide range of cognitive impairments and structural deficits broadly termed fetal alcohol spectrum disorders (FASD). We discuss the broad impact of prenatal alcohol exposure on the developing embryo and elaborate on the current state of gene-alcohol interactions. Additionally, we discuss how animal models have informed our understanding of the genetics of FASD. Ultimately, these topics will provide insight into the use of animal models in understanding gene-environment interactions and their subsequent impact on birth defects.
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Affiliation(s)
- Charles Benjamin Lovely
- Department of Biochemistry and Molecular Genetics, Alcohol Research Center, University of Louisville, Louisville, Kentucky
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9
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Deniz E, Jonas S, Khokha MK, Choma MA. Quantitative Phenotyping of Xenopus Embryonic Heart Pathophysiology Using Hemoglobin Contrast Subtraction Angiography to Screen Human Cardiomyopathies. Front Physiol 2019; 10:1197. [PMID: 31620018 PMCID: PMC6763566 DOI: 10.3389/fphys.2019.01197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 09/03/2019] [Indexed: 01/09/2023] Open
Abstract
Congenital heart disease (CHD) is a significant cause of mortality in infants and adults. Currently human genomic analysis has identified a number of candidate genes in these patients. These genes span diverse categories of gene function suggesting that despite the similarity in cardiac lesion, the underlying pathophysiology may be different. In fact, patients with similar CHDs can have drastically different outcomes, including a dramatic decrease in myocardial function. To test these human candidate genes for their impact on myocardial function, we need efficient animals models of disease. For this purpose, we paired Xenopus tropicalis with our microangiography technique, hemoglobin contrast subtraction angiography (HCSA). To demonstrate the gene-teratogen-physiology relationship, we modeled human cardiomyopathy in tadpoles. First we depleted the sarcomeric protein myosin heavy chain 6 (myh6) expression using morpholino oligos. Next, we exposed developing embryos to the teratogen ethanol and in both conditions showed varying degrees of cardiac dysfunction. Our results demonstrate that HCSA can distinguish biomechanical phenotypes in the context of gene dysfunction or teratogen. This approach can be used to screen numerous candidate CHD genes or suspected teratogens for their effect on cardiac function.
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Affiliation(s)
- Engin Deniz
- Department of Pediatrics, Yale University, New Haven, CT, United States
| | - Stephan Jonas
- Department of Informatics, Technical University of Munich, Munich, Germany
| | - Mustafa K Khokha
- Department of Pediatrics, Yale University, New Haven, CT, United States.,Department of Genetics, Yale University, New Haven, CT, United States
| | - Michael A Choma
- Department of Pediatrics, Yale University, New Haven, CT, United States.,Department of Diagnostic Radiology, Yale University, New Haven, CT, United States.,Department of Biomedical Engineering, Yale University, New Haven, CT, United States.,Department of Applied Physics, Yale University, New Haven, CT, United States
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10
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Using Zebrafish for Investigating the Molecular Mechanisms of Drug-Induced Cardiotoxicity. BIOMED RESEARCH INTERNATIONAL 2018; 2018:1642684. [PMID: 30363733 PMCID: PMC6180974 DOI: 10.1155/2018/1642684] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Revised: 07/31/2018] [Accepted: 08/18/2018] [Indexed: 01/09/2023]
Abstract
Over the last decade, the zebrafish (Danio rerio) has emerged as a model organism for cardiovascular research. Zebrafish have several advantages over mammalian models. For instance, the experimental cost of using zebrafish is comparatively low; the embryos are transparent, develop externally, and have high fecundity making them suitable for large-scale genetic screening. More recently, zebrafish embryos have been used for the screening of a variety of toxic agents, particularly for cardiotoxicity testing. Zebrafish has been shown to exhibit physiological responses that are similar to mammals after exposure to medicinal drugs including xenobiotics, hormones, cancer drugs, and also environmental pollutants, including pesticides and heavy metals. In this review, we provided a summary for recent studies that have used zebrafish to investigate the molecular mechanisms of drug-induced cardiotoxicity. More specifically, we focused on the techniques that were exploited by us and others for cardiovascular toxicity assessment and described several microscopic imaging and analysis protocols that are being used for the estimation of a variety of cardiac hemodynamic parameters.
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11
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Ultracytochemical visualization of calcium distribution in heart cells and erythrocytes of zebrafish Danio rerio. Micron 2018; 111:19-27. [DOI: 10.1016/j.micron.2018.05.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 05/23/2018] [Accepted: 05/23/2018] [Indexed: 01/06/2023]
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12
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Burkhard SB, Bakkers J. Spatially resolved RNA-sequencing of the embryonic heart identifies a role for Wnt/β-catenin signaling in autonomic control of heart rate. eLife 2018; 7:31515. [PMID: 29400650 PMCID: PMC5815850 DOI: 10.7554/elife.31515] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 02/03/2018] [Indexed: 11/13/2022] Open
Abstract
Development of specialized cells and structures in the heart is regulated by spatially -restricted molecular pathways. Disruptions in these pathways can cause severe congenital cardiac malformations or functional defects. To better understand these pathways and how they regulate cardiac development we used tomo-seq, combining high-throughput RNA-sequencing with tissue-sectioning, to establish a genome-wide expression dataset with high spatial resolution for the developing zebrafish heart. Analysis of the dataset revealed over 1100 genes differentially expressed in sub-compartments. Pacemaker cells in the sinoatrial region induce heart contractions, but little is known about the mechanisms underlying their development. Using our transcriptome map, we identified spatially restricted Wnt/β-catenin signaling activity in pacemaker cells, which was controlled by Islet-1 activity. Moreover, Wnt/β-catenin signaling controls heart rate by regulating pacemaker cellular response to parasympathetic stimuli. Thus, this high-resolution transcriptome map incorporating all cell types in the embryonic heart can expose spatially restricted molecular pathways critical for specific cardiac functions.
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Affiliation(s)
- Silja Barbara Burkhard
- Hubrecht Institute-KNAW, Utrecht, Netherlands.,University Medical Center Utrecht, Utrecht, Netherlands
| | - Jeroen Bakkers
- Hubrecht Institute-KNAW, Utrecht, Netherlands.,University Medical Center Utrecht, Utrecht, Netherlands.,Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
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13
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Fernandes Y, Buckley DM, Eberhart JK. Diving into the world of alcohol teratogenesis: a review of zebrafish models of fetal alcohol spectrum disorder. Biochem Cell Biol 2017; 96:88-97. [PMID: 28817785 DOI: 10.1139/bcb-2017-0122] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The term fetal alcohol spectrum disorder (FASD) refers to the entire suite of deleterious outcomes resulting from embryonic exposure to alcohol. Along with other reviews in this special issue, we provide insight into how animal models, specifically the zebrafish, have informed our understanding of FASD. We first provide a brief introduction to FASD. We discuss the zebrafish as a model organism and its strengths for alcohol research. We detail how zebrafish has been used to model some of the major defects present in FASD. These include behavioral defects, such as social behavior as well as learning and memory, and structural defects, disrupting organs such as the brain, sensory organs, heart, and craniofacial skeleton. We provide insights into how zebrafish research has aided in our understanding of the mechanisms of ethanol teratogenesis. We end by providing some relatively recent advances that zebrafish has provided in characterizing gene-ethanol interactions that may underlie FASD.
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Affiliation(s)
- Yohaan Fernandes
- Molecular Biosciences, University of Texas at Austin, Austin, TX 78713, USA.,Molecular Biosciences, University of Texas at Austin, Austin, TX 78713, USA
| | - Desire M Buckley
- Molecular Biosciences, University of Texas at Austin, Austin, TX 78713, USA.,Molecular Biosciences, University of Texas at Austin, Austin, TX 78713, USA
| | - Johann K Eberhart
- Molecular Biosciences, University of Texas at Austin, Austin, TX 78713, USA.,Molecular Biosciences, University of Texas at Austin, Austin, TX 78713, USA
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14
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Vargas RA. Effects of GABA, Neural Regulation, and Intrinsic Cardiac Factors on Heart Rate Variability in Zebrafish Larvae. Zebrafish 2017; 14:106-117. [DOI: 10.1089/zeb.2016.1365] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Rafael Antonio Vargas
- Departamento de Ciencias Fisiológicas, Facultad de Medicina, Pontificia Universidad Javeriana, Bogotá, Colombia
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15
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Sarmah S, Marrs JA. Zebrafish as a Vertebrate Model System to Evaluate Effects of Environmental Toxicants on Cardiac Development and Function. Int J Mol Sci 2016; 17:ijms17122123. [PMID: 27999267 PMCID: PMC5187923 DOI: 10.3390/ijms17122123] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 12/04/2016] [Accepted: 12/12/2016] [Indexed: 12/16/2022] Open
Abstract
Environmental pollution is a serious problem of the modern world that possesses a major threat to public health. Exposure to environmental pollutants during embryonic development is particularly risky. Although many pollutants have been verified as potential toxicants, there are new chemicals in the environment that need assessment. Heart development is an extremely sensitive process, which can be affected by environmentally toxic molecule exposure during embryonic development. Congenital heart defects are the most common life-threatening global health problems, and the etiology is mostly unknown. The zebrafish has emerged as an invaluable model to examine substance toxicity on vertebrate development, particularly on cardiac development. The zebrafish offers numerous advantages for toxicology research not found in other model systems. Many laboratories have used the zebrafish to study the effects of widespread chemicals in the environment on heart development, including pesticides, nanoparticles, and various organic pollutants. Here, we review the uses of the zebrafish in examining effects of exposure to external molecules during embryonic development in causing cardiac defects, including chemicals ubiquitous in the environment and illicit drugs. Known or potential mechanisms of toxicity and how zebrafish research can be used to provide mechanistic understanding of cardiac defects are discussed.
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Affiliation(s)
- Swapnalee Sarmah
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA.
| | - James A Marrs
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA.
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16
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Lovely CB, Fernandes Y, Eberhart JK. Fishing for Fetal Alcohol Spectrum Disorders: Zebrafish as a Model for Ethanol Teratogenesis. Zebrafish 2016; 13:391-8. [PMID: 27186793 PMCID: PMC5035362 DOI: 10.1089/zeb.2016.1270] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Fetal Alcohol Spectrum Disorders (FASD) describes a wide array of ethanol-induced developmental defects, including craniofacial dysmorphology and cognitive impairments. It affects ∼1 in 100 children born in the United States each year. Due to the pleiotropic effects of ethanol, animal models have proven critical in characterizing the mechanisms of ethanol teratogenesis. In this review, we focus on the utility of zebrafish in characterizing ethanol-induced developmental defects. A growing number of laboratories have focused on using zebrafish to examine ethanol-induced defects in craniofacial, cardiac, ocular, and neural development, as well as cognitive and behavioral impairments. Growing evidence supports that genetic predisposition plays a role in these ethanol-induced defects, yet little is understood about these gene-ethanol interactions. With a high degree of genetic amenability, zebrafish is at the forefront of identifying and characterizing the gene-ethanol interactions that underlie FASD. Because of the conservation of gene function between zebrafish and humans, these studies will directly translate to studies of candidate genes in human populations and allow for better diagnosis and treatment of FASD.
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Affiliation(s)
| | - Yohaan Fernandes
- Molecular Biosciences, University of Texas at Austin , Austin, Texas
| | - Johann K Eberhart
- Molecular Biosciences, University of Texas at Austin , Austin, Texas
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17
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Li X, Gao A, Wang Y, Chen M, Peng J, Yan H, Zhao X, Feng X, Chen D. Alcohol exposure leads to unrecoverable cardiovascular defects along with edema and motor function changes in developing zebrafish larvae. Biol Open 2016; 5:1128-33. [PMID: 27422904 PMCID: PMC5004616 DOI: 10.1242/bio.019497] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Maternal alcohol consumption during pregnancy can cause a series of developmental disorders in the fetus called FAS (fetal alcohol syndrome). In the present study we exposed zebrafish embryos to 1% and 2% alcohol and observed the morphology of heart and blood vessels during and after exposure to investigate motor function alterations, and damage and recovery to the cardiovascular system. The results showed that alcohol exposure could induce heart deformation, slower heart rate, and incomplete blood vessels and pericardium. After stopping exposure, larvae exposed to 1% alcohol could recover only in heart morphology, but larvae in 2% alcohol could not recover either morphology or function of cardiovascular system. The edema-like characteristics in the 2% alcohol group became more conspicuous afterwards, with destruction in the dorsal aorta, coarctation in segmental arteries and a decrease in motor function, implying more serious unrecoverable cardiovascular defects in the 2% group. The damaged blood vessels in the 2% alcohol group resulted in an alteration in permeability and a decrease of blood volume, which were the causes of edema in pathology. These findings contribute towards a better understanding of ethanol-induced cardiovascular abnormalities and co-syndrome in patients with FAS, and warns against excessive maternal alcohol consumption during pregnancy.
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Affiliation(s)
- Xu Li
- Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Department of Histology and Embryology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Aiai Gao
- Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Department of Histology and Embryology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Yanan Wang
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Science, Nankai University, Tianjin 300071, China
| | - Man Chen
- Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Department of Histology and Embryology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Jun Peng
- Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Department of Histology and Embryology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Huaying Yan
- Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Department of Histology and Embryology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Xin Zhao
- The Institute of Robotics and Automatic Information Systems, Nankai University, Tianjin 300071, China
| | - Xizeng Feng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Science, Nankai University, Tianjin 300071, China
| | - Dongyan Chen
- Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, Department of Histology and Embryology, School of Medicine, Nankai University, Tianjin 300071, China
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Lin X, Li VWT, Chen S, Chan CY, Cheng SH, Shi P. Autonomous system for cross-organ investigation of ethanol-induced acute response in behaving larval zebrafish. BIOMICROFLUIDICS 2016; 10:024123. [PMID: 27158291 PMCID: PMC4833730 DOI: 10.1063/1.4946013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/30/2016] [Indexed: 06/05/2023]
Abstract
Ethanol is widely consumed and has been associated with various diseases in different organs. It is therefore important to study ethanol-induced responses in living organisms with the capability to address specific organs in an integrative manner. Here, we developed an autonomous system based on a series of microfluidic chips for cross-organ investigation of ethanol-induced acute response in behaving larval zebrafish. This system enabled high-throughput, gel-free, and anesthetic-free manipulation of larvae, and thus allowed real-time observation of behavioral responses, and associated physiological changes at cellular resolution within specific organs in response to acute ethanol stimuli, which would otherwise be impossible by using traditional methods for larva immobilization and orientation. Specifically, three types of chips ("motion," "lateral," and "dorsal"), based on a simple hydrodynamic design, were used to perform analysis in animal behavior, cardiac, and brain physiology, respectively. We found that ethanol affected larval zebrafish in a dose-dependent manner. The motor function of different body parts was significantly modulated by ethanol treatment, especially at a high dose of 3%. These behavioral changes were temporally associated with a slow-down of heart-beating and a stereotyped activation of certain brain regions. As we demonstrated in this proof-of-concept study, this versatile Fish-on-Chip platform could potentially be adopted for systematic cross-organ investigations involving chemical or genetic manipulations in zebrafish model.
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Affiliation(s)
- Xudong Lin
- Department of Mechanical and Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Ave., Kowloon 999077, Hong Kong, China
| | - Vincent W T Li
- Department of Biomedical Science, City University of Hong Kong, 83 Tat Chee Ave., Kowloon 999077, Hong Kong, China
| | - Siya Chen
- Department of Mechanical and Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Ave., Kowloon 999077, Hong Kong, China
| | - Chung-Yuen Chan
- Department of Mechanical and Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Ave., Kowloon 999077, Hong Kong, China
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Karunamuni GH, Ma P, Gu S, Rollins AM, Jenkins MW, Watanabe M. Connecting teratogen-induced congenital heart defects to neural crest cells and their effect on cardiac function. BIRTH DEFECTS RESEARCH. PART C, EMBRYO TODAY : REVIEWS 2014; 102:227-50. [PMID: 25220155 PMCID: PMC4238913 DOI: 10.1002/bdrc.21082] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 08/26/2014] [Indexed: 12/26/2022]
Abstract
Neural crest cells play many key roles in embryonic development, as demonstrated by the abnormalities that result from their specific absence or dysfunction. Unfortunately, these key cells are particularly sensitive to abnormalities in various intrinsic and extrinsic factors, such as genetic deletions or ethanol-exposure that lead to morbidity and mortality for organisms. This review discusses the role identified for a segment of neural crest in regulating the morphogenesis of the heart and associated great vessels. The paradox is that their derivatives constitute a small proportion of cells to the cardiovascular system. Findings supporting that these cells impact early cardiac function raises the interesting possibility that they indirectly control cardiovascular development at least partially through regulating function. Making connections between insults to the neural crest, cardiac function, and morphogenesis is more approachable with technological advances. Expanding our understanding of early functional consequences could be useful in improving diagnosis and testing therapies.
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Affiliation(s)
- Ganga H. Karunamuni
- Department of Pediatrics, Case Western Reserve University School of Medicine, Case Medical Center Division of Pediatric Cardiology, Rainbow Babies and Children’s Hospital, Cleveland OH 44106
| | - Pei Ma
- Department of Biomedical Engineering, Case Western Reserve University School of Engineering, Cleveland OH 44106
| | - Shi Gu
- Department of Biomedical Engineering, Case Western Reserve University School of Engineering, Cleveland OH 44106
| | - Andrew M. Rollins
- Department of Biomedical Engineering, Case Western Reserve University School of Engineering, Cleveland OH 44106
| | - Michael W. Jenkins
- Department of Pediatrics, Case Western Reserve University School of Medicine, Case Medical Center Division of Pediatric Cardiology, Rainbow Babies and Children’s Hospital, Cleveland OH 44106
- Department of Biomedical Engineering, Case Western Reserve University School of Engineering, Cleveland OH 44106
| | - Michiko Watanabe
- Department of Pediatrics, Case Western Reserve University School of Medicine, Case Medical Center Division of Pediatric Cardiology, Rainbow Babies and Children’s Hospital, Cleveland OH 44106
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Karunamuni G, Gu S, Doughman YQ, Peterson LM, Mai K, McHale Q, Jenkins MW, Linask KK, Rollins AM, Watanabe M. Ethanol exposure alters early cardiac function in the looping heart: a mechanism for congenital heart defects? Am J Physiol Heart Circ Physiol 2013; 306:H414-21. [PMID: 24271490 DOI: 10.1152/ajpheart.00600.2013] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Alcohol-induced congenital heart defects are frequently among the most life threatening and require surgical correction in newborns. The etiology of these defects, collectively known as fetal alcohol syndrome, has been the focus of much study, particularly involving cellular and molecular mechanisms. Few studies have addressed the influential role of altered cardiac function in early embryogenesis because of a lack of tools with the capability to assay tiny beating hearts. To overcome this gap in our understanding, we used optical coherence tomography (OCT), a nondestructive imaging modality capable of micrometer-scale resolution imaging, to rapidly and accurately map cardiovascular structure and hemodynamics in real time under physiological conditions. In this study, we exposed avian embryos to a single dose of alcohol/ethanol at gastrulation when the embryo is sensitive to the induction of birth defects. Late-stage hearts were analyzed using standard histological analysis with a focus on the atrio-ventricular valves. Early cardiac function was assayed using Doppler OCT, and structural analysis of the cardiac cushions was performed using OCT imaging. Our results indicated that ethanol-exposed embryos developed late-stage valvuloseptal defects. At early stages, they exhibited increased regurgitant flow and developed smaller atrio-ventricular cardiac cushions, compared with controls (uninjected and saline-injected embryos). The embryos also exhibited abnormal flexion/torsion of the body. Our evidence suggests that ethanol-induced alterations in early cardiac function have the potential to contribute to late-stage valve and septal defects, thus demonstrating that functional parameters may serve as early and sensitive gauges of cardiac normalcy and abnormalities.
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Sarmah S, Marrs JA. Complex cardiac defects after ethanol exposure during discrete cardiogenic events in zebrafish: prevention with folic acid. Dev Dyn 2013; 242:1184-201. [PMID: 23832875 DOI: 10.1002/dvdy.24015] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/13/2013] [Accepted: 07/01/2013] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Fetal alcohol spectrum disorder (FASD) describes a range of birth defects including various congenital heart defects (CHDs). Mechanisms of FASD-associated CHDs are not understood. Whether alcohol interferes with a single critical event or with multiple events in heart formation is not known. RESULTS Our zebrafish embryo experiments showed that ethanol interrupts different cardiac regulatory networks and perturbs multiple steps of cardiogenesis (specification, myocardial migration, looping, chamber morphogenesis, and endocardial cushion formation). Ethanol exposure during gastrulation until cardiac specification or during myocardial midline migration did not produce severe or persistent heart development defects. However, exposure comprising gastrulation until myocardial precursor midline fusion or during heart patterning stages produced aberrant heart looping and defective endocardial cushions. Continuous exposure during entire cardiogenesis produced complex cardiac defects leading to severely defective myocardium, endocardium, and endocardial cushions. Supplementation of retinoic acid with ethanol partially rescued early heart developmental defects, but the endocardial cushions did not form correctly. In contrast, supplementation of folic acid rescued normal heart development, including the endocardial cushions. CONCLUSIONS Our results indicate that ethanol exposure interrupted divergent cardiac morphogenetic events causing heart defects. Folic acid supplementation was effective in preventing a wide spectrum of ethanol-induced heart developmental defects.
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Affiliation(s)
- Swapnalee Sarmah
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana
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Sarmah S, Muralidharan P, Curtis CL, McClintick JN, Buente BB, Holdgrafer DJ, Ogbeifun O, Olorungbounmi OC, Patino L, Lucas R, Gilbert S, Groninger ES, Arciero J, Edenberg HJ, Marrs JA. Ethanol exposure disrupts extraembryonic microtubule cytoskeleton and embryonic blastomere cell adhesion, producing epiboly and gastrulation defects. Biol Open 2013; 2:1013-21. [PMID: 24167711 PMCID: PMC3798184 DOI: 10.1242/bio.20135546] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 07/07/2013] [Indexed: 11/20/2022] Open
Abstract
Fetal alcohol spectrum disorder (FASD) occurs when pregnant mothers consume alcohol, causing embryonic ethanol exposure and characteristic birth defects that include craniofacial, neural and cardiac defects. Gastrulation is a particularly sensitive developmental stage for teratogen exposure, and zebrafish is an outstanding model to study gastrulation and FASD. Epiboly (spreading blastomere cells over the yolk cell), prechordal plate migration and convergence/extension cell movements are sensitive to early ethanol exposure. Here, experiments are presented that characterize mechanisms of ethanol toxicity on epiboly and gastrulation. Epiboly mechanisms include blastomere radial intercalation cell movements and yolk cell microtubule cytoskeleton pulling the embryo to the vegetal pole. Both of these processes were disrupted by ethanol exposure. Ethanol effects on cell migration also indicated that cell adhesion was affected, which was confirmed by cell aggregation assays. E-cadherin cell adhesion molecule expression was not affected by ethanol exposure, but E-cadherin distribution, which controls epiboly and gastrulation, was changed. E-cadherin was redistributed into cytoplasmic aggregates in blastomeres and dramatically redistributed in the extraembryonic yolk cell. Gene expression microarray analysis was used to identify potential causative factors for early development defects, and expression of the cell adhesion molecule protocadherin-18a (pcdh18a), which controls epiboly, was significantly reduced in ethanol exposed embryos. Injecting pcdh18a synthetic mRNA in ethanol treated embryos partially rescued epiboly cell movements, including enveloping layer cell shape changes. Together, data show that epiboly and gastrulation defects induced by ethanol are multifactorial, and include yolk cell (extraembryonic tissue) microtubule cytoskeleton disruption and blastomere adhesion defects, in part caused by reduced pcdh18a expression.
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Affiliation(s)
- Swapnalee Sarmah
- Department of Biology, Indiana University-Purdue University Indianapolis , 723 West Michigan Street, Indianapolis, IN 46202-5130 , USA
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Loucks E, Ahlgren S. Assessing teratogenic changes in a zebrafish model of fetal alcohol exposure. J Vis Exp 2012. [PMID: 22453686 PMCID: PMC3460571 DOI: 10.3791/3704] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Fetal alcohol syndrome (FAS) is a severe manifestation of embryonic exposure to ethanol. It presents with characteristic defects to the face and organs, including mental retardation due to disordered and damaged brain development. Fetal alcohol spectrum disorder (FASD) is a term used to cover a continuum of birth defects that occur due to maternal alcohol consumption, and occurs in approximately 4% of children born in the United States. With 50% of child-bearing age women reporting consumption of alcohol, and half of all pregnancies being unplanned, unintentional exposure is a continuing issue. In order to best understand the damage produced by ethanol, plus produce a model with which to test potential interventions, we developed a model of developmental ethanol exposure using the zebrafish embryo. Zebrafish are ideal for this kind of teratogen study. Each pair lays hundreds of eggs, which can then be collected without harming the adult fish. The zebrafish embryo is transparent and can be readily imaged with any number of stains. Analysis of these embryos after exposure to ethanol at different doses and times of duration and application shows that the gross developmental defects produced by ethanol are consistent with the human birth defect. Described here are the basic techniques used to study and manipulate the zebrafish FAS model.
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Affiliation(s)
- Evyn Loucks
- Program in Developmental Biology, Children's Memorial Research Center, Northwestern University, USA
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Bosco C, Diaz E. Placental Hypoxia and Foetal Development Versus Alcohol Exposure in Pregnancy. Alcohol Alcohol 2012; 47:109-17. [DOI: 10.1093/alcalc/agr166] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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Feasibility of Medaka (Oryzias latipes) as an Animal Model to Study Fetal Alcohol Spectrum Disorder. ADVANCES IN MOLECULAR TOXICOLOGY VOLUME 6 2012. [DOI: 10.1016/b978-0-444-59389-4.00003-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Howarth DL, Vacaru AM, Tsedensodnom O, Mormone E, Nieto N, Costantini LM, Snapp EL, Sadler KC. Alcohol disrupts endoplasmic reticulum function and protein secretion in hepatocytes. Alcohol Clin Exp Res 2011; 36:14-23. [PMID: 21790674 DOI: 10.1111/j.1530-0277.2011.01602.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Many alcoholic patients have serum protein deficiency that contributes to their systemic problems. The unfolded protein response (UPR) is induced in response to disequilibrium in the protein folding capability of the endoplasmic reticulum (ER) and is implicated in hepatocyte lipid accumulation and apoptosis, which are associated with alcoholic liver disease (ALD). We investigated whether alcohol affects ER structure, function, and UPR activation in hepatocytes in vitro and in vivo. METHODS HepG2 cells expressing human cytochrome P450 2E1 and mouse alcohol dehydrogenase (VL-17A) were treated for up to 48 hours with 50 and 100 mM ethanol. Zebrafish larvae at 4 days postfertilization were exposed to 350 mM ethanol for 32 hours. ER morphology was visualized by fluorescence in cells and transmission electron microscopy in zebrafish. UPR target gene activation was assessed using quantitative PCR, in situ hybridization, and Western blotting. Mobility of the major ER chaperone, BIP, was monitored in cells by fluorescence recovery after photobleaching (FRAP). RESULTS VL-17A cells metabolized alcohol yet only had slight activation of some UPR target genes following ethanol treatment. However, ER fragmentation, crowding, and accumulation of unfolded proteins as detected by immunofluorescence and FRAP demonstrate that alcohol induced some ER dysfunction despite the lack of UPR activation. Zebrafish treated with alcohol, however, showed modest ER dilation, and several UPR targets were significantly induced. CONCLUSIONS Ethanol metabolism directly impairs ER structure and function in hepatocytes. Zebrafish are a novel in vivo system for studying ALD.
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Affiliation(s)
- Deanna L Howarth
- Division of Liver Diseases, Department of Medicine, Mount Sinai School of Medicine, New York, New York, USA
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