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Espinasa L, Pavie M, Rétaux S. Protocol for lens removal in embryonic fish and its application on the developmental effects of eye regression. SUBTERRANEAN BIOLOGY 2023. [DOI: 10.3897/subtbiol.45.96963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The lens plays a central role in the development of the optic cup. In fish, regression of the eye early in development affects the development of the craniofacial skeleton, the size of the olfactory pits, the optic nerve, and the tectum. Lens removal further affects olfaction, prey capture, and aggression. The similarity of the fish eye to other vertebrates is the basis for its use as an excellent animal model of human defects. Questions regarding the effects of eye regression are specifically well-suited to be addressed by using fish from the genus Astyanax. The species has two morphs; an eyeless cave morph and an eyed, surface morph. In the cavefish, a lens initially develops in embryos, but then degenerates by apoptosis. The cavefish retina is subsequently disorganized, degenerates, and retinal growth is arrested. The same effect is observed in surface fish when the lens is removed or exchanged for a cavefish lens. While studies can greatly benefit from a control group of surface fish with regressed eyes brought through lensectomies, few studies include them because of technical difficulties and the low survivorship of embryos that undergo this procedure. Here we describe a technique with significant modification for improvement for conducting lensectomy in one-day-old Astyanax and other fish, including zebrafish. Yields of up to 30 live embryos were obtained using this technique from a single spawn, thus enabling studies that require large sample sizes.
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2
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Kujawski S, Crespo C, Luz M, Yuan M, Winkler S, Knust E. Loss of Crb2b-lf leads to anterior segment defects in old zebrafish. Biol Open 2020; 9:bio047555. [PMID: 31988089 PMCID: PMC7044448 DOI: 10.1242/bio.047555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 01/09/2020] [Indexed: 12/02/2022] Open
Abstract
Defects in the retina or the anterior segment of the eye lead to compromised vision and affect millions of people. Understanding how these ocular structures develop and are maintained is therefore of paramount importance. The maintenance of proper vision depends, among other factors, on the function of genes controlling apico-basal polarity. In fact, mutations in polarity genes are linked to retinal degeneration in several species, including human. Here we describe a novel zebrafish crb2b allele (crb2be40 ), which specifically affects the crb2b long isoform. crb2be40 mutants are viable and display normal ocular development. However, old crb2be40 mutant fish develop multiple defects in structures of the anterior segment, which includes the cornea, the iris and the lens. Phenotypes are characterised by smaller pupils due to expansion of the iris and tissues of the iridocorneal angle, an increased number of corneal stromal keratocytes, an abnormal corneal endothelium and an expanded lens capsule. These findings illustrate a novel role for crb2b in the maintenance of the anterior segment and hence add an important function to this polarity regulator, which may be conserved in other vertebrates including humans.
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Affiliation(s)
- Satu Kujawski
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Cátia Crespo
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Marta Luz
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Michaela Yuan
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Sylke Winkler
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Elisabeth Knust
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
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3
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Zhang Y, Wang Z, Zhao G, Liu JX. Silver nanoparticles affect lens rather than retina development in zebrafish embryos. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2018; 163:279-288. [PMID: 30056342 DOI: 10.1016/j.ecoenv.2018.07.079] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 07/17/2018] [Accepted: 07/20/2018] [Indexed: 06/08/2023]
Abstract
Silver nanoparticles (AgNPs) have been reported to inhibit specification and differentiation of erythroid cells, chromatophores, and myofibrils during zebrafish embryogenesis. However, the knowledge of biological effects of AgNPs on eye development, especially on lens development is scarce. In this study, embryos were exposed to or injected with 0.4 mg/L AgNPs, and the results indicate that no obvious morphological changes in eye formation were observed in the stressed embryos compared to the controls. However, clefts and vacuoles were observed in lens of embryos from AgNPs stressed group. Additionally, the down-regulated expressions of different lens crystallin isoform genes and the normal expression of retinal genes were observed in AgNPs stressed embryos, suggesting AgNPs might inhibit the development of lens rather than the development of retina in zebrafish embryos. Moreover, no obvious cell apoptosis was observed, but normal nuclear DNA and RNA export was observed in lens cells. Together, the data in this study reveal that AgNPs damage the development of lens rather than retina resulting in eye abnormalities via some unknown mechanisms rather than via triggering cells apoptosis or blocking nuclear DNA or RNA export.
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Affiliation(s)
- YanJun Zhang
- College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China.
| | - ZiYang Wang
- College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China.
| | - Guang Zhao
- College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China.
| | - Jing-Xia Liu
- College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, China; Collaborative Innovation Center for Efficient and Health Production of Fisheries in Hunan Province, Changde 415000, Hunan, China.
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4
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Zou P, Wu SY, Koteiche HA, Mishra S, Levic DS, Knapik E, Chen W, Mchaourab HS. A conserved role of αA-crystallin in the development of the zebrafish embryonic lens. Exp Eye Res 2015; 138:104-13. [PMID: 26149094 DOI: 10.1016/j.exer.2015.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/17/2015] [Accepted: 07/02/2015] [Indexed: 01/19/2023]
Abstract
αA- and αB-crystallins are small heat shock proteins that bind thermodynamically destabilized proteins thereby inhibiting their aggregation. Highly expressed in the mammalian lens, the α-crystallins have been postulated to play a critical role in the maintenance of lens optical properties by sequestering age-damaged proteins prone to aggregation as well as through a multitude of roles in lens epithelial cells. Here, we have examined the role of α-crystallins in the development of the vertebrate zebrafish lens. For this purpose, we have carried out morpholino-mediated knockdown of αA-, αBa- and αBb-crystallin and characterized the gross morphology of the lens. We observed lens abnormalities, including increased reflectance intensity, as a consequence of the interference with expression of these proteins. These abnormalities were less frequent in transgenic zebrafish embryos expressing rat αA-crystallin suggesting a specific role of α-crystallins in embryonic lens development. To extend and confirm these findings, we generated an αA-crystallin knockout zebrafish line. A more consistent and severe lens phenotype was evident in maternal/zygotic αA-crystallin mutants compared to those observed by morpholino knockdown. The penetrance of the lens phenotype was reduced by transgenic expression of rat αA-crystallin and its severity was attenuated by maternal αA-crystallin expression. These findings demonstrate that the role of α-crystallins in lens development is conserved from mammals to zebrafish and set the stage for using the embryonic lens as a model system to test mechanistic aspects of α-crystallin chaperone activity and to develop strategies to fine-tune protein-protein interactions in aging and cataracts.
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Affiliation(s)
- Ping Zou
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Shu-Yu Wu
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Hanane A Koteiche
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Sanjay Mishra
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Daniel S Levic
- Department of Medicine, Division of Genetic Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Ela Knapik
- Department of Medicine, Division of Genetic Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Wenbiao Chen
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA.
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5
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The phenotype of the good effort mutant zebrafish is retinal degeneration by cell death and is linked to the chromosome assembly factor 1b gene. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:535-41. [PMID: 24664741 DOI: 10.1007/978-1-4614-3209-8_68] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
In a screen to identify zebrafish eye mutants, we isolated the good effort (gef) mutant. The retina of gef embryos is characterized by the successful initiation of the optic primordium and normal retinal development over the first 2 days post fertilization (dpf). The mutant retina, however, fails to continue to grow. Embryos from gef heterozygous incrosses were analyzed for cell death by acridine orange and by TUNEL labeling at 2 dpf. Significantly more TUNEL-positive and acridine orange-labeled dying cells were found in gef mutant embryos at 2 dpf relative to wild-type embryos. Because this time was earlier than any observable gross morphological differences, this cell death was likely the cause of the gross morphological defects. Meiotic mapping localized the mutation interval to a one-megabase interval on zebrafish chromosome 9.
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6
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Morris AC. The genetics of ocular disorders: insights from the zebrafish. ACTA ACUST UNITED AC 2012; 93:215-28. [PMID: 21932431 DOI: 10.1002/bdrc.20211] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Proper formation of the vertebrate eye requires a precisely coordinated sequence of morphogenetic events that integrate the developmental contributions of the skin ectoderm, neuroectoderm, and head mesenchyme. Disruptions in this process result in ocular malformations or retinal degeneration and can cause significant visual impairment. The zebrafish is an excellent vertebrate model for the study of eye development and disease due to the transparency of the embryo, its ex utero development, and its amenability to forward genetic screens. This review will present an overview of the genetic methodologies utilized in the zebrafish, a description of several zebrafish models of congenital ocular diseases, and a discussion of the utility of the zebrafish for assessing the pathogenicity of candidate disease alleles.
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Affiliation(s)
- Ann C Morris
- Department of Biology, University of Kentucky, Lexington, USA.
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7
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Phosphatidylinositol synthase is required for lens structural integrity and photoreceptor cell survival in the zebrafish eye. Exp Eye Res 2011; 93:460-74. [PMID: 21722635 DOI: 10.1016/j.exer.2011.06.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 05/04/2011] [Accepted: 06/14/2011] [Indexed: 01/22/2023]
Abstract
The zebrafish lens opaque (lop) mutant was previously isolated in a genetic screen and shown to lack rod and cone photoreceptors and exhibit lens opacity, or cataract, at 7 days post-fertilization (dpf). In this manuscript, we provide four different lines of evidence demonstrating that the lop phenotype results from a defect in the cdipt (phosphatidylinositol (PI) synthase; CDP-diacylglycerol-inositol 3-phosphatidyltransferase) gene. First, DNA sequence analysis revealed that the lop mutant contained a missense mutation in the lop open reading frame, which yields a nonconservative amino acid substitution (Ser-111-Cys) within the PI synthase catalytic domain. Second, morpholino-mediated knockdown of the cdipt-encoded PI synthase protein phenocopied the cdipt(lop/lop) mutant, with abnormal lens epithelial and secondary fiber cell morphologies and reduced numbers of photoreceptors. Third, microinjection of in vitro transcribed, wild-type cdipt mRNA into 1-4 cell stage cdipt(lop/lop) embryos significantly reduced the percentage of larvae displaying lens opacity at 7 dpf. Fourth, a cdipt retroviral-insertion allele, cdipt(hi559), exhibited similar lens and retinal abnormalities and failed to complement the cdipt(lop) mutant phenotype. To determine the initial cellular defects associated with the cdipt mutant, we examined homozygous cdipt(hi559/hi559) mutants prior to gross lens opacification at 6 dpf. The cdipt(hi559/hi559) mutants first exhibited photoreceptor layer disruption and photoreceptor cell death at 3 and 4 dpf, respectively, followed by lens dismorphogenesis by 5 dpf. RT-PCR revealed that the cdipt gene is maternally expressed and continues to be transcribed throughout development and into adulthood, in a wide variety of tissues. Using an anti-zebrafish PI synthase polyclonal antiserum, we localized the protein throughout the developing eye, including the photoreceptor layer and lens cortical secondary fiber cells. As expected, the polyclonal antiserum revealed that the PI synthase protein was reduced in amount in both the cdipt(lop/lop) and cdipt(hi559/hi559) mutants. Furthermore, we used a heterologous yeast phenotypic complementation assay to confirm that the wild-type zebrafish cdipt allele encodes functional PI synthase activity. Taken together, the cdipt-encoded PI synthase is required for survival of photoreceptor cells and lens epithelial and secondary cortical fiber cells. These zebrafish cdipt alleles represent excellent in vivo genetic tools to study the role of phosphatidylinositol and its phosphorylated derivatives in lens and photoreceptor development and maintenance.
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8
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Bibliowicz J, Tittle RK, Gross JM. Toward a better understanding of human eye disease insights from the zebrafish, Danio rerio. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 100:287-330. [PMID: 21377629 DOI: 10.1016/b978-0-12-384878-9.00007-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Visual impairment and blindness is widespread across the human population, and the development of therapies for ocular pathologies is of high priority. The zebrafish represents a valuable model organism for studying human ocular disease; it is utilized in eye research to understand underlying developmental processes, to identify potential causative genes for human disorders, and to develop therapies. Zebrafish eyes are similar in morphology, physiology, gene expression, and function to human eyes. Furthermore, zebrafish are highly amenable to laboratory research. This review outlines the use of zebrafish as a model for human ocular diseases such as colobomas, glaucoma, cataracts, photoreceptor degeneration, as well as dystrophies of the cornea and retinal pigmented epithelium.
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Affiliation(s)
- Jonathan Bibliowicz
- University of Texas at Austin, Section of Molecular Cell and Developmental Biology, Austin, Texas, USA
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9
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Imai F, Yoshizawa A, Fujimori-Tonou N, Kawakami K, Masai I. The ubiquitin proteasome system is required for cell proliferation of the lens epithelium and for differentiation of lens fiber cells in zebrafish. Development 2010; 137:3257-68. [PMID: 20724448 DOI: 10.1242/dev.053124] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the developing vertebrate lens, epithelial cells differentiate into fiber cells, which are elongated and flat in shape and form a multilayered lens fiber core. In this study, we identified the zebrafish volvox (vov) mutant, which shows defects in lens fiber differentiation. In the vov mutant, lens epithelial cells fail to proliferate properly. Furthermore, differentiating lens fiber cells do not fully elongate, and the shape and position of lens fiber nuclei are affected. We found that the vov mutant gene encodes Psmd6, the subunit of the 26S proteasome. The proteasome regulates diverse cellular functions by degrading polyubiquitylated proteins. Polyubiquitylated proteins accumulate in the vov mutant. Furthermore, polyubiquitylation is active in nuclei of differentiating lens fiber cells, suggesting roles of the proteasome in lens fiber differentiation. We found that an E3 ubiquitin ligase anaphase-promoting complex/cyclosome (APC/C) is involved in lens defects in the vov mutant. These data suggest that the ubiquitin proteasome system is required for cell proliferation of lens epithelium and for the differentiation of lens fiber cells in zebrafish.
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Affiliation(s)
- Fumiyasu Imai
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology (OIST), Onna, Okinawa, Japan
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10
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Schonthaler HB, Franz-Odendaal TA, Hodel C, Gehring I, Geisler R, Schwarz H, Neuhauss SCF, Dahm R. The zebrafish mutant bumper shows a hyperproliferation of lens epithelial cells and fibre cell degeneration leading to functional blindness. Mech Dev 2010; 127:203-19. [PMID: 20117205 DOI: 10.1016/j.mod.2010.01.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Revised: 01/25/2010] [Accepted: 01/26/2010] [Indexed: 10/19/2022]
Abstract
The development of the eye lens is one of the classical paradigms of induction during embryonic development in vertebrates. But while there have been numerous studies aimed at discovering the genetic networks controlling early lens development, comparatively little is known about later stages, including the differentiation of secondary lens fibre cells. The analysis of mutant zebrafish isolated in forward genetic screens is an important way to investigate the roles of genes in embryogenesis. In this study we describe the zebrafish mutant bumper (bum), which shows a transient, tumour-like hyperproliferation of the lens epithelium as well as a progressively stronger defect in secondary fibre cell differentiation, which results in a significantly reduced lens size and ectopic location of the lens within the neural retina. Interestingly, the initial hyperproliferation of the lens epithelium in bum spontaneously regresses, suggesting this mutant as a valuable model to study the molecular control of tumour progression/suppression. Behavioural analyses demonstrate that, despite a morphologically normal retina, larval and adult bum(-/-) zebrafish are functionally blind. We further show that these fish have defects in their craniofacial skeleton with normal but delayed formation of the scleral ossicles within the eye, several reduced craniofacial bones resulting in an abnormal skull shape, and asymmetric ectopic bone formation within the mandible. Genetic mapping located the mutation in bum to a 4cM interval on chromosome 7 with the closest markers located at 0.2 and 0cM, respectively.
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Affiliation(s)
- Helia B Schonthaler
- Max Planck Institute for Developmental Biology, Department of Genetics, Spemannstr. 35, D-72076 Tübingen, Germany
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11
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Zhang Y, McCulloch K, Malicki J. Lens transplantation in zebrafish and its application in the analysis of eye mutants. J Vis Exp 2009:1258. [PMID: 19488031 PMCID: PMC2794882 DOI: 10.3791/1258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The lens plays an important role in the development of the optic cup. Using the zebrafish as a model organism, questions regarding lens development can be addressed. The zebrafish is useful for genetic studies due to several advantageous characteristics, including small size, high fecundity, short lifecycle, and ease of care. Lens development occurs rapidly in zebrafish. By 72 hpf, the zebrafish lens is functionally mature. Abundant genetic and molecular resources are available to support research in zebrafish. In addition, the similarity of the zebrafish eye to those of other vertebrates provides basis for its use as an excellent animal model of human defects. Several zebrafish mutants exhibit lens abnormalities, including high levels of cell death, which in some cases leads to a complete degeneration of lens tissues. To determine whether lens abnormalities are due to intrinsic causes or to defective interactions with the surrounding tissues, transplantation of a mutant lens into a wild-type eye is performed. Using fire-polished metal needles, mutant or wild-type lenses are carefully dissected from the donor animal, and transferred into the host. To distinguish wild-type and mutant tissues, a transgenic line is used as the donor. This line expresses membrane-bound GFP in all tissues, including the lens. This transplantation technique is an essential tool in the studies of zebrafish lens mutants.
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Affiliation(s)
- Yan Zhang
- The Second Teaching Hospital of Jilin University
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12
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Gross JM, Perkins BD. Zebrafish mutants as models for congenital ocular disorders in humans. Mol Reprod Dev 2008; 75:547-55. [PMID: 18058918 DOI: 10.1002/mrd.20831] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Jeffrey M Gross
- Section of Molecular Cell and Developmental Biology, Institute for Cell and Molecular Biology, Institute of Neuroscience, The University of Texas at Austin, Austin, Texas 78712, USA.
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13
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Vihtelic TS. Teleost lens development and degeneration. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 269:341-73. [PMID: 18779061 DOI: 10.1016/s1937-6448(08)01006-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The transparent properties of the lens and its ability to focus light onto the retina are critical for normal vision. Optical clarity of the lens is achieved and maintained by a unique, highly regulated integration of lens cell proliferation and differentiation that persists throughout life. Zebrafish is a powerful genetic model for studying vertebrate lens differentiation and growth because the structural organization of the lens and gene functions are largely conserved with mammals, including humans. However, some features of zebrafish lens developmental morphology and gene expression are different from those of mammals and other terrestrial vertebrates. For example, the presumptive zebrafish lens delaminates from the surface ectoderm to form a solid mass of cells, in which the primary fibers differentiate by elongating in circular fashion. Both mutational and candidate gene analyses have identified and characterized developmental gene functions of the lens in zebrafish. This chapter presents the recent morphological analysis of zebrafish lens formation. In addition, the roles of Pitx3, Foxe3, and the lens-specific protein Lengsin (LENS Glutamine SYNthetase-like) in lens development are analyzed. Selected zebrafish lens mutants defective in early developmental processes and the maintenance of lens transparency are also discussed.
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Affiliation(s)
- Thomas S Vihtelic
- Department of Biological Sciences and Center for Zebrafish Research, Galvin Life Sciences Center, University of Notre Dame, Notre Dame, Indiana 46556, USA
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14
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Alvarez Y, Cederlund ML, Cottell DC, Bill BR, Ekker SC, Torres-Vazquez J, Weinstein BM, Hyde DR, Vihtelic TS, Kennedy BN. Genetic determinants of hyaloid and retinal vasculature in zebrafish. BMC DEVELOPMENTAL BIOLOGY 2007; 7:114. [PMID: 17937808 PMCID: PMC2169232 DOI: 10.1186/1471-213x-7-114] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Accepted: 10/15/2007] [Indexed: 11/29/2022]
Abstract
Background The retinal vasculature is a capillary network of blood vessels that nourishes the inner retina of most mammals. Developmental abnormalities or microvascular complications in the retinal vasculature result in severe human eye diseases that lead to blindness. To exploit the advantages of zebrafish for genetic, developmental and pharmacological studies of retinal vasculature, we characterised the intraocular vasculature in zebrafish. Results We show a detailed morphological and developmental analysis of the retinal blood supply in zebrafish. Similar to the transient hyaloid vasculature in mammalian embryos, vessels are first found attached to the zebrafish lens at 2.5 days post fertilisation. These vessels progressively lose contact with the lens and by 30 days post fertilisation adhere to the inner limiting membrane of the juvenile retina. Ultrastructure analysis shows these vessels to exhibit distinctive hallmarks of mammalian retinal vasculature. For example, smooth muscle actin-expressing pericytes are ensheathed by the basal lamina of the blood vessel, and vesicle vacuolar organelles (VVO), subcellular mediators of vessel-retinal nourishment, are present. Finally, we identify 9 genes with cell membrane, extracellular matrix and unknown identity that are necessary for zebrafish hyaloid and retinal vasculature development. Conclusion Zebrafish have a retinal blood supply with a characteristic developmental and adult morphology. Abnormalities of these intraocular vessels are easily observed, enabling application of genetic and chemical approaches in zebrafish to identify molecular regulators of hyaloid and retinal vasculature in development and disease.
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Affiliation(s)
- Yolanda Alvarez
- UCD School of Biomolecular, and Biomedical Sciences, University College Dublin, Dublin 4, Ireland.
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15
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Catalano AE, Raymond PA, Goldman D, Wei X. Zebrafish dou yan mutation causes patterning defects and extensive cell death in the retina. Dev Dyn 2007; 236:1295-306. [PMID: 17436278 PMCID: PMC2922982 DOI: 10.1002/dvdy.21148] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The size of an organ is largely determined by the number of cells it contains, which in turn is regulated by two opposing processes, cell proliferation and cell death, however, it is generally not clear how cell proliferation and cell death are coordinated during development. Here, we characterize the zebrafish dou yan(mi234) mutation that results in a dramatic reduction of retinal size and a disruption of retinal differentiation and lamination. The retinal size reduction is caused by increased retinal cell death in a non-cell-autonomous manner during early development. The phenotypic defect in dou yan(mi234) arises coincident with the onset of retinal neurogenesis and differentiation. Interestingly, unlike many other small eye mutations, the mutation does not increase the level of cell death in the brain, suggesting that the brain and retina use different mechanisms to maintain cell survival. Identification and further study of the dou yan gene will enhance our understanding of the molecular mechanisms regulating retinal cellular homeostasis, i.e., the balance between cell proliferation and cell death.
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Affiliation(s)
- Anne E. Catalano
- Department of Ophthalmology, University of Pittsburgh School of Medicine, 203 Lothrop Street, Pittsburgh, PA 15213
| | - Pamela A. Raymond
- Department of Molecular, Cellular & Developmental Biology, University of Michigan, 3003 Kraus Natural Science Building, 830 North University Avenue, Ann Arbor, MI 48109-1048
| | - Daniel Goldman
- Molecular and Behavioral Neuroscience Institute and Department of Biological Chemistry, University of Michigan, 5045 Biomedical Sciences Research Building, 109 Zina Pitcher Place, Ann Arbor, MI 48109
| | - Xiangyun Wei
- Department of Ophthalmology, University of Pittsburgh School of Medicine, 203 Lothrop Street, Pittsburgh, PA 15213
- Corresponding author: Tel: 412-383-5845, Fax: 412-647-5880,
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16
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Dahm R, Schonthaler HB, Soehn AS, van Marle J, Vrensen GFJM. Development and adult morphology of the eye lens in the zebrafish. Exp Eye Res 2007; 85:74-89. [PMID: 17467692 DOI: 10.1016/j.exer.2007.02.015] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 02/19/2007] [Accepted: 02/21/2007] [Indexed: 11/23/2022]
Abstract
The zebrafish has become an important vertebrate model organism to study the development of the visual system. Mutagenesis projects have resulted in the identification of hundreds of eye mutants. Analysis of the phenotypes of these mutants relies on in depth knowledge of the embryogenesis in wild-type animals. While the morphological events leading to the formation of the retina and its connections to the central nervous system have been described in great detail, the characterization of the development of the eye lens is still incomplete. In the present study, we provide a morphological description of embryonic and larval lens development as well as adult lens morphology in the zebrafish. Our analyses show that, in contrast to other vertebrate species, the zebrafish lens delaminates from the surface ectoderm as a solid cluster of cells. Detachment of the prospective lens from the surface ectoderm is facilitated by apoptosis. Primary fibre cell elongation occurs in a circular fashion resulting in an embryonic lens nucleus with concentric shells of fibres. After formation of a monolayer of lens epithelial cells, differentiation and elongation of secondary lens fibres result in a final lens morphology similar to that of other vertebrate species. As in other vertebrates, secondary fibre cell differentiation includes the programmed degradation of nuclei, the interconnection of adjacent fibres via protrusions at the fibre cells' edges and the establishment of gap junctions between lens fibre cells. The very close spacing of the nuclei of the differentiating secondary fibres in a narrow zone close to the equatorial epithelium, however, suggests that secondary fibre cell differentiation deviates from that described for mammalian or avian lenses. In summary, while there are similarities in the development and final morphology of the zebrafish lens with mammalian and avian lenses, there are also significant differences, suggesting caution when extrapolating findings on the zebrafish to, for example, human lens development or function.
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MESH Headings
- Animals
- Apoptosis/physiology
- Cell Differentiation/physiology
- Cell Nucleus/ultrastructure
- Embryo, Nonmammalian/anatomy & histology
- Embryo, Nonmammalian/cytology
- Embryo, Nonmammalian/ultrastructure
- Embryonic Development/physiology
- Epithelial Cells/cytology
- Epithelial Cells/ultrastructure
- Gap Junctions/ultrastructure
- In Situ Nick-End Labeling/methods
- Iris/anatomy & histology
- Lens, Crystalline/cytology
- Lens, Crystalline/embryology
- Lens, Crystalline/ultrastructure
- Microscopy, Electron/methods
- Microscopy, Electron, Scanning/methods
- Microscopy, Interference/methods
- Models, Animal
- Zebrafish/anatomy & histology
- Zebrafish/embryology
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Affiliation(s)
- Ralf Dahm
- Max-Planck-Institute for Developmental Biology, Spemannstrasse 35, D-72076 Tübingen, Germany.
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17
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Franz-Odendaal TA, Ryan K, Hall BK. Developmental and morphological variation in the teleost craniofacial skeleton reveals an unusual mode of ossification. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2007; 308:709-21. [PMID: 17577202 DOI: 10.1002/jez.b.21185] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We investigated the morphology and development of the scleral ossicles within the eyes of three species from three basal teleost orders, namely, the alewife (Alosa pseudoharengus; Clupeiformes), the surface morph of the Mexican tetra (Astyanax mexicanus; Characiformes) and zebrafish (Danio rerio; Cypriniformes). Two morphologies, circular and elongated, and one variation, fused elements, were identified. Zebrafish have small circular ossicles, whereas the alewife and the Mexican tetra have elongated ossicles. Surprisingly in the Mexican tetra these elements fuse at one end forming a continuous element with an antero-ventral opening; this may be typical for the Order Characiformes. Regardless of morphology, the ossicles develop via unilateral perichondral ossification of the scleral cartilage from two centers opposite one another in the eye. This unilateral type of ossification, in which only the perichondrium furthest from the retina contributes to the ossicles, has not previously been reported in any vertebrate. Because either the perichondrium and/or an extension of the perichondrium can transform into the scleral ossicle, we refer to the transitional tissue as periskeletal. Although the functional significance of the different shaped ossicles is unclear, skeletal muscle attaches directly to these bones, implying voluntary control. The morphological and developmental variation of teleost scleral ossicles makes them an ideal system for determining the genetic basis underlying phenotypic variation as well as for studying mechanisms underlying osteogenic and chondrogenic processes in teleosts. These data support our previous finding that scleral ossicles in teleosts may not be homologous to those in other vertebrates, such as reptiles.
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18
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Franz-Odendaal TA, Vickaryous MK. Skeletal elements in the vertebrate eye and adnexa: morphological and developmental perspectives. Dev Dyn 2006; 235:1244-55. [PMID: 16496288 DOI: 10.1002/dvdy.20718] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Although poorly appreciated, the vertebrate eye and adnexa are relatively common sites for skeletogenesis. In many taxa, the skeleton contributes to internal reinforcement in addition to the external housing of the eye (e.g., the circumorbital bones and eyelids). Eyeball elements such as scleral cartilage and scleral ossicles are present within a broad diversity of vertebrates, albeit not therian mammals, and have been used as important models for the study of condensations and epithelial-mesenchymal interactions. In contrast, other elements invested within the eye or its close surroundings remain largely unexplored. The onset and mode of development of these skeletal elements are often variable (early versus late; involving chondrogenesis, osteogenesis, or both), and most (if not all) of these elements appear to share a common neural crest origin. This review discusses the development and distribution of the skeletal elements within and associated with the developing eye and comments on homology of the elements where these are questionable.
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19
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Abstract
The ocular lens is a distinct system to study cell death for the following reasons. First, during animal development, the ocular lens is crafted into its unique shape. The crafting processes include cell proliferation, cell migration, and apoptosis. Moreover, the lens epithelial cells differentiate into lens fiber cells through a process, which utilizes the same regulators as those in apoptosis at multiple signaling steps. In addition, introduction of exogenous wild-type or mutant genes or knock-out of the endogenous genes leads to apoptosis of the lens epithelial cells followed by absence of the ocular lens or formation of abnormal lens. Finally, both in vitro and in vivo studies have shown that treatment of adult lens with stress factors induces apoptosis of lens epithelial cells, which is followed by cataractogenesis. The present review summarizes the current knowledge on apoptosis in the ocular lens with emphasis on its role in lens development and pathology.
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Affiliation(s)
- Qin Yan
- College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
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20
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Ruttum MS, Reis LM, Semina EV. Application of genetic approaches to ocular disease. Pediatr Clin North Am 2006; 53:751-65. [PMID: 16873003 DOI: 10.1016/j.pcl.2006.05.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The human eye is a complex organ whose development requires extraordinary coordination of developmental processes. Multiple genes responsible for the proper development and maintenance of the vertebrate eye have been identified and shown to be involved in a variety of debilitating ocular conditions. Genetic diseases involving the eye represent a leading cause of blindness in children and adults. This article summarizes current genetic approaches and their application to studies of ocular disease.
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Affiliation(s)
- Mark S Ruttum
- Medical College of Wisconsin, 925 North 87th Street, Milwaukee, WI 53226, USA.
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21
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Shi X, Luo Y, Howley S, Dzialo A, Foley S, Hyde DR, Vihtelic TS. Zebrafish foxe3: roles in ocular lens morphogenesis through interaction with pitx3. Mech Dev 2006; 123:761-82. [PMID: 16963235 DOI: 10.1016/j.mod.2006.07.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Revised: 07/06/2006] [Accepted: 07/13/2006] [Indexed: 10/24/2022]
Abstract
Foxe3 is a winged helix/forkhead domain transcription factor necessary for mammalian and amphibian lens development. Human FOXE3 mutations cause anterior segment dysgenesis and cataracts. The zebrafish foxe3 cDNA was PCR amplified from 24 h post-fertilization (hpf) embryo cDNA. The zebrafish foxe3 gene consists of a single exon on chromosome 8 and encodes a 422 amino acid protein. This protein possesses 44% and 67% amino acid identity with the human FOXE3 and Xenopus FoxE4 proteins, respectively. A polyclonal antiserum was generated against a bacterial fusion protein containing the Foxe3 carboxyl terminus. The purified antiserum detects zebrafish Foxe3 on immunoblots, in embryo wholemounts, and frozen tissue sections. The zebrafish Foxe3 protein is first detected in the lens at 31hpf and is restricted to the nucleated cell population, including the epithelial and elongating fiber cells. Knockdown of Foxe3 protein using an antisense morpholino results in small lenses with multilayered epithelial cells and fiber cell dysmorphogenesis. The morphants posses normal retinas, although retinal cell proteins, including rhodopsin, are abnormally expressed in the morphant lens tissue. Functional interactions between foxe3 and pitx3 during lens development were assessed by RT-PCR and comparison of Foxe3 and Pitx3 protein expression in both foxe3 and pitx3 morphants. Immunoblots and immunohistochemistry reveal Pitx3 is expressed in the foxe3 morphant lens, while Pitx3 knockdown results in the elimination of Foxe3 expression. These data demonstrate that Foxe3 is necessary for lens development in zebrafish and that foxe3 lies genetically downstream of pitx3 in a zebrafish lens development pathway.
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Affiliation(s)
- Xiaohai Shi
- Department of Biological Sciences and Center for Zebrafish Research, University of Notre Dame, Notre Dame, IN 46556, USA
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22
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Semina EV, Bosenko DV, Zinkevich NC, Soules KA, Hyde DR, Vihtelic TS, Willer GB, Gregg RG, Link BA. Mutations in laminin alpha 1 result in complex, lens-independent ocular phenotypes in zebrafish. Dev Biol 2006; 299:63-77. [PMID: 16973147 DOI: 10.1016/j.ydbio.2006.07.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Revised: 07/04/2006] [Accepted: 07/07/2006] [Indexed: 10/24/2022]
Abstract
We report phenotypic and genetic analyses of a recessive, larval lethal zebrafish mutant, bal(a69), characterized by severe eye defects and shortened body axis. The bal(a69) mutation was mapped to chromosome 24 near the laminin alpha 1 (lama1) gene. We analyzed the lama1 gene sequence within bal(a69) embryos and two allelic mutants, bal(arl) and bal(uw1). Missense (bal(a69)), nonsense (bal(arl)), and frameshift (bal(uw1)) alterations in lama1 were found to underlie the phenotypes. Extended analysis of bal(a69) ocular features revealed disrupted lens development with subsequent lens degeneration, focal cornea dysplasia, and hyaloid vasculature defects. Within the neural retina, the ganglion cells showed axonal projection defects and ectopic photoreceptor cells were noted at inner retinal locations. To address whether ocular anomalies were secondary to defects in lens differentiation, bal(a69) mutants were compared to embryos in which the lens vesicle was surgically removed. Our analysis suggests that many of the anterior and posterior ocular defects in bal(a69) are independent of the lens degeneration. Analysis of components of focal adhesion signaling complexes suggests that reduced focal adhesion kinase activation underlies the anterior segment dysgenesis in lama1 mutants. To assess adult ocular phenotypes associated with lama1 mutations, genetic mosaics were generated by transplanting labeled bal cells into ocular-fated regions of wild-type blastulas. Adult chimeric eyes displayed a range of defects including anterior segment dysgenesis and cataracts. Our analysis provides mechanistic insights into the developmental defects and ocular pathogenesis caused by mutations in laminin subunits.
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MESH Headings
- Amino Acid Sequence
- Animals
- Anterior Eye Segment/abnormalities
- Anterior Eye Segment/cytology
- Anterior Eye Segment/embryology
- Base Sequence
- Cataract/pathology
- Chromosomes/genetics
- Cloning, Molecular
- DNA Mutational Analysis
- Embryo, Nonmammalian/cytology
- Embryo, Nonmammalian/embryology
- Focal Adhesions
- Gene Expression Regulation, Developmental
- Laminin/chemistry
- Laminin/deficiency
- Laminin/genetics
- Lens, Crystalline/abnormalities
- Lens, Crystalline/cytology
- Lens, Crystalline/embryology
- Lens, Crystalline/surgery
- Molecular Sequence Data
- Mosaicism
- Mutation/genetics
- Phenotype
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Retinal Ganglion Cells/cytology
- Retinal Vessels/abnormalities
- Retinal Vessels/embryology
- Zebrafish/abnormalities
- Zebrafish/embryology
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Affiliation(s)
- Elena V Semina
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
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23
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Maaswinkel H, Riesbeck LE, Riley ME, Carr AL, Mullin JP, Nakamoto AT, Li L. Behavioral screening for nightblindness mutants in zebrafish reveals three new loci that cause dominant photoreceptor cell degeneration. Mech Ageing Dev 2006; 126:1079-89. [PMID: 15922406 DOI: 10.1016/j.mad.2005.03.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Revised: 03/21/2005] [Accepted: 03/22/2005] [Indexed: 11/19/2022]
Abstract
Here we report three dominant nightblindness mutations in zebrafish: nightblindness e (nbe), nightblindness f (nbf) and nightblindness g (nbg). The mutants were isolated in the F1 generation of N-ethyl-N-nitrosourea (ENU) mutagenized zebrafish using a behavioral assay based on visually mediated escape responses. Subsequently, electroretinographic (ERG) recordings were made, and histological sections were screened for degenerative processes. For each mutant line, correlation analysis between behavioral, ERG and histological parameters was performed, and their relationships were determined by either calculating the Pearson correlation coefficient or by ANOVA. nbe is characterized by severe rod outer segments (ROS) degeneration. The degeneration correlates weakly with behavioral threshold and ERG b-wave amplitude, however, behavioral threshold correlates strongly with ERG b-wave. nbf is characterized by a dual histological pathology: patchy ROS-degeneration and 'gaps' homogeneously distributed over the outer nuclei layer (ONL) and between cone outer segments (COS). The correlations between histological pathology and behavioral threshold, and between behavioral threshold and ERG b-wave amplitude are obvious, but the correlation between histology and b-wave amplitude is less prominent. nbg is characterized by moderate ROS degeneration and moderate correlation between histology and behavioral threshold. Interestingly, behavioral threshold correlated inversely with ERG b-wave amplitude and threshold. Thus, contrary to what is normally seen in other nightblindness mutants, in nbg, the fish with the lowest behavioral threshold had the smallest b-waves amplitudes and the highest b-wave threshold. In our interpretation, the major impairment in nbe is photoreceptor-specific. In nbf, both photoreceptor degeneration and altered post-photoreceptor signaling are responsible for the behavioral deficit. In nbg, we find hypersensitivity at a post-photoreceptoral level concurrently with behavioral impairment.
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Affiliation(s)
- Hans Maaswinkel
- Department of Biological Sciences, University of Notre Dame, 107 Galvin Life Science Center, Notre Dame, IN 46556, USA
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24
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Vihtelic TS, Yamamoto Y, Springer SS, Jeffery WR, Hyde DR. Lens opacity and photoreceptor degeneration in the zebrafish lens opaque mutant. Dev Dyn 2005; 233:52-65. [PMID: 15765514 DOI: 10.1002/dvdy.20294] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The zebrafish lens opaque (lop) mutant was identified in a chemical mutagenesis screen. The lop mutant, which develops normally through 4 days postfertilization (dpf), exhibits several signs of lens and retinal degeneration at 7 dpf. Histology revealed disrupted lens fibers and increased numbers of nucleated cells within the mutant lens and anterior chamber. The mutant lens also exhibited aberrant epithelial cell morphologies and lacked a definitive transition zone, which suggests that secondary fiber differentiation was interrupted. In addition, the mutant exhibits severely reduced photoreceptors and a reduction in the number of horizontal cells at 7 dpf. Other retinal cell classes appeared unaffected in the mutant. Transmission electron microscopy and opsin immunohistochemistry showed that the different photoreceptor types were generated at the retinal margin, but the rods and cones failed to mature and disappeared. The mutant lens and retina also displayed increased cell proliferation based on proliferating cell nuclear antigen immunolabeling, suggesting that the lens opacity was due to unregulated cell proliferation and undifferentiated cell accumulation within the mutant lens. The lop mutant phenotype supports recent studies showing the lens has a role in regulating teleost retinal development.
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Affiliation(s)
- Thomas S Vihtelic
- Center for Zebrafish Research, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
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25
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Wehman AM, Staub W, Meyers JR, Raymond PA, Baier H. Genetic dissection of the zebrafish retinal stem-cell compartment. Dev Biol 2005; 281:53-65. [PMID: 15848388 DOI: 10.1016/j.ydbio.2005.02.010] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2004] [Revised: 02/02/2005] [Accepted: 02/09/2005] [Indexed: 01/18/2023]
Abstract
In a large-scale forward-genetic screen, we discovered that a limited number of genes are required for the regulation of retinal stem cells after embryogenesis in zebrafish. In 18 mutants out of almost 2000 F2 families screened, the eye undergoes normal embryonic development, but fails to continue growth from the ciliary marginal zone (CMZ), the post-embryonic stem-cell niche. Class I-A mutants (5 loci) display lower amounts of proliferation in the CMZ, while nearly all cells in the retina appear differentiated. Class I-B mutants (2 loci) have a reduced CMZ with a concomitant expansion in the retinal pigmented epithelium (RPE), suggesting a common post-embryonic stem cell is the source for these neighboring cell types. Class II encompasses three distinct types of mutants (11 loci) with expanded CMZ, in which the progenitor population is arrested in the cell cycle. We also show that in at least one combination, the reduced CMZ phenotype is genetically epistatic to the expanded CMZ phenotype, suggesting that Class I genes are more likely to affect the stem cells and Class II the progenitor cells. Finally, a comparative mapping analysis demonstrates that the new genes isolated do not correspond to genes previously implicated in stem-cell regulation. Our study suggests that embryonic and post-embryonic stem cells utilize separable genetic programs in the zebrafish retina.
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Affiliation(s)
- Ann M Wehman
- Program in Genetics, University of California, San Francisco, 1550 4th Street, San Francisco, CA 94158, USA
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26
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Evans TG, Yamamoto Y, Jeffery WR, Krone PH. Zebrafish Hsp70 is required for embryonic lens formation. Cell Stress Chaperones 2005; 10:66-78. [PMID: 15832949 PMCID: PMC1074573 DOI: 10.1379/csc-79r.1] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Revised: 11/08/2004] [Accepted: 11/15/2004] [Indexed: 02/01/2023] Open
Abstract
Heat shock proteins (Hsps) were originally identified as proteins expressed after exposure of cells to environmental stress. Several Hsps were subsequently shown to play roles as molecular chaperones in normal intracellular protein folding and targeting events and to be expressed during discrete periods in the development of several embryonic tissues. However, only recently have studies begun to address the specific developmental consequences of inhibiting Hsp expression to determine whether these molecular chaperones are required for specific developmental events. We have previously shown that the heat-inducible zebrafish hsp70 gene is expressed during a distinct temporal window of embryonic lens formation at normal growth temperatures. In addition, a 1.5-kb fragment of the zebrafish hsp70 gene promoter is sufficient to direct expression of a gfp reporter gene to the lens, suggesting that the hsp70 gene is expressed as part of the normal lens development program. Here, we used microinjection of morpholino-modified antisense oligonucleotides (MOs) to reduce Hsp70 levels during zebrafish development and to show that Hsp70 is required for normal lens formation. Hsp70-MO-injected embryos exhibited a small-eye phenotype relative to wild-type and control-injected animals, with the phenotype discernable during the second day of development. Histological and immunological analysis revealed a small, underdeveloped lens. Numerous terminal deoxynucleotidyl transferase-mediated dUTP-fluoroscein nick-end labeling (TUNEL)-positive nuclei appeared in the lens of small-eye embryos after 48 hours postfertilization (hpf), whereas they were no longer apparent in untreated embryos by this age. Lenses transplanted from hsp70-MO-injected embryos into wild-type hosts failed to recover and retained the immature morphology characteristic of the small-eye phenotype, indicating that the lens phenotype is lens autonomous. Our data suggest that the lens defect in hsp70-MO-injected embryos is predominantly at the level of postmitotic lens fiber differentiation, a result supported by the appearance of mature lens organization in these embryos by 5 days postfertilization, once morpholino degradation or dilution has occurred.
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Affiliation(s)
- Tyler G Evans
- Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5E5
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27
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Shi X, Bosenko DV, Zinkevich NS, Foley S, Hyde DR, Semina EV, Vihtelic TS. Zebrafish pitx3 is necessary for normal lens and retinal development. Mech Dev 2004; 122:513-27. [PMID: 15804565 DOI: 10.1016/j.mod.2004.11.012] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Revised: 11/11/2004] [Accepted: 11/19/2004] [Indexed: 01/23/2023]
Abstract
The human PITX3 gene encodes a bicoid-like homeodomain transcription factor associated with a variety of congenital ocular conditions, including anterior segment dysgenesis, Peter's anomaly, and cataracts. We identified a zebrafish pitx3 gene encoding a protein (Pitx3) that possesses 63% amino acid identity with human PITX3. The zebrafish pitx3 gene encompasses approximately 16.5kb on chromosome 13 and consists of four exons, which is similar to the genomic organization of other pitx genes. Expression of the zebrafish pitx3 gene was studied by in situ mRNA hybridization and RT-PCR. The pitx3 transcripts were detected throughout development with the greatest level of expression occurring in the developing lens and brain at 24hpf. In adults, the highest expression was detected in the eye. Morpholinos were used to knockdown expression of the Pitx3 protein and a control morpholino that contains five mismatched bases was used to confirm the specificity of the phenotypes. The morphants had small eyes, misshapen heads and reduced jaws and fins relative to controls. The morphants exhibited abnormalities in lens development and their retinas contained pyknotic nuclei accompanied by a reduction in the number of cells in different neuronal classes. This suggests the lens is required for retinal development or Pitx3 has an unexpected role in retinal cell differentiation or survival. These results demonstrate zebrafish pitx3 represents a true ortholog of the human PITX3 gene and the general function of the Pitx3 protein in lens development is conserved between mammals and the teleost fish.
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Affiliation(s)
- Xiaohai Shi
- Department of Biological Sciences, Center for Zebrafish Research, Galvin Life Sciences Center, University of Notre Dame, Notre Dame, IN 46556, USA
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28
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Cheng S, Christie T, Valdimarsson G. Expression of connexin48.5, connexin44.1, and connexin43 during zebrafish (Danio rerio) lens development. Dev Dyn 2004; 228:709-15. [PMID: 14648847 DOI: 10.1002/dvdy.10436] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Connexins (Cx), the protein units of gap junctions, play important roles in lens development and homeostasis. Here, we report the mRNA expression patterns of zebrafish Cx48.5, Cx44.1, Cx43 during lens development. The expression of all three connexins in the adult lens was first confirmed by reverse transcriptase-polymerase chain reaction. By whole-mount in situ hybridization, we detected Cx48.5 expression throughout the lens, except the lateral lens epithelium, at 36 hours postfertilization (hpf). The pattern remained the same at 2 days postfertilization (dpf). By 3 and 4 dpf, Cx48.5 expression was restricted to the differentiating lens fibers in the equatorial and medial regions. Cx44.1 was expressed in a similar manner as Cx48.5 from 36 hpf to 4 dpf. However, Cx44.1 expression was also detected in the lens at 24 hpf. Cx43 expression was detected throughout the lens at 24 and 36 hpf but became restricted to the lateral epithelium at later stages.
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Affiliation(s)
- Shaohong Cheng
- Department of Zoology, University of Manitoba, Winnipeg, Manitoba, Canada
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29
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Glass AS, Dahm R. The Zebrafish as a Model Organism for Eye Development. Ophthalmic Res 2004; 36:4-24. [PMID: 15007235 DOI: 10.1159/000076105] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2003] [Accepted: 12/09/2003] [Indexed: 11/19/2022]
Abstract
In recent years, the zebrafish has become a favourite model organism for biologists studying developmental processes in vertebrates. Its rapid embryonic development, the transparency of its embryos, the large number of offspring together with several other advantages make it ideal for discovering and understanding the genes that regulate embryonic development as well as the physiology of the adult organism. Zebrafish are very visually orientated, and their retina and lens show much the same morphology as other vertebrates including humans. For this reason, they are well suited for examining ocular development, function and disease. This review describes the advantages of the zebrafish as a model organism as well as giving an overview of eye development in this species. It has a particular focus on morphological as well as molecular aspects of the development of the lens.
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Affiliation(s)
- Anne S Glass
- Medizinische Genetik, Eberhard-Karls-Universität Tübingen, Germany
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30
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Goldsmith P, Baier H, Harris WA. Two zebrafish mutants, ebony and ivory, uncover benefits of neighborhood on photoreceptor survival. ACTA ACUST UNITED AC 2004; 57:235-45. [PMID: 14608660 DOI: 10.1002/neu.10274] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Zebrafish offer a tractable system for the study of retinal development and degeneration, to provide insights into human retinal degeneration. We have begun to dissect the question of neighborhood effects on photoreceptor differentiation and survival through the isolation and characterization of mutants with retinal degeneration. We describe two mutants, ebony and ivory, isolated through a behavioral screen for blind mutants induced by ethyl nitrosourea mutagenesis. Chimeric analysis was conducted to attempt to rescue the photoreceptor degeneration. In ebony, the photoreceptor cell death was both cell autonomous and nonautonomous in nature, whilst the photoreceptor cell death was strikingly nonautonomous in ivory. The rescue at a distance is in keeping with a putative diffusible survival factor. We propose a density-dependent nonautonomous neighborhood effect to explain these findings.
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Affiliation(s)
- Paul Goldsmith
- Department of Anatomy, University of Cambridge, Downing Site, Cambridge, CB2 3DY, United Kingdom
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31
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Abstract
Similar to other vertebrate species, the zebrafish retina is simpler than other regions of the central nervous system (CNS). Relative simplicity, rapid development, and accessibility to genetic analysis make the zebrafish retina an excellent model system for the studies of neurogenesis in the vertebrate CNS. Numerous genetic screens have led to isolation of an impressive collection of mutations affecting the retina and the retinotectal projection in zebrafish. Mutant phenotypes are being studied using a rich variety of markers: antibodies, RNA probes, retrograde and anterograde tracers, as well as transgenic lines. Particularly impressive progress has been made in the characterization of the zebrafish genome. Consequently, positional and candidate cloning of mutant genes are now fairly easy to accomplish in zebrafish. Many mutant genes have, in fact, already been cloned and their analysis has provided important insights into the gene circuitry that regulates retinal neurogenesis. Genetic screens for visual system defects will continue in the future and progressively more sophisticated screening approaches will make it possible to detect a variety of subtle mutant phenotypes in retinal development. The remarkable evolutionary conservation of the vertebrate eye provides the basis for the use of the zebrafish retina as a model of human disorders. Some of the genetic defects of the zebrafish retina indeed resemble human retinopathies. As new techniques are being introduced and improved at a rapid pace, the zebrafish will continue to be an important organism for the studies of the vertebrate visual system.
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Affiliation(s)
- Andrei Avanesov
- Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA
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32
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Neuhauss SCF, Seeliger MW, Schepp CP, Biehlmaier O. Retinal defects in the zebrafish bleached mutant. Doc Ophthalmol 2003; 107:71-8. [PMID: 12906124 DOI: 10.1023/a:1024492029629] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The recessive zebrafish mutant bleached has, apart from its defects in pigmentation, a heritable defect leading to larval blindness. Here, we analyze the retina of homozygous bleached larvae, employing morphological and electrophysiological methods. Electroretinography revealed a complete lack of electrical signals in response to light. Histological analysis of mutant retinae showed a severely affected outer retina with a hypopigmented pigment epithelium and a disorganized outer nuclear layer containing few or no intact photoreceptors. Using the TUNEL assay for cell death detection, we noticed a strong increase of apoptotic cells in all retinal cell layers, starting in young larvae even before retinal support of visual function. At later stages cell death is most pronounced at the marginal zone, where new cells are constantly added to the retina. At early stages increased apoptosis is mainly confined to the retina, while at later stages elevated cell death is al so apparent in extra-retinal tissues, particularly in the brain. Hence, the lack of visual responses in homozygous bleached larvae can be attributed to a severe defect of the outer retina, preceded by increased levels of apoptotic cell death in all retinal cell layers.
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Affiliation(s)
- Stephan C F Neuhauss
- Brain Research Institute, University of Zurich and Department of Biology, Swiss Federal Institute of Technology Zurich, Winterthurerstr. 190, CH-8057 Zurich, Switzerland.
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33
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Luo C, Li B. Diploid-dependent regulation of gene expression: a genetic cause of abnormal development in fish haploid embryos. Heredity (Edinb) 2003; 90:405-9. [PMID: 12714987 DOI: 10.1038/sj.hdy.6800263] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
A diploid-dependent regulatory mechanism of gene expression for spatial patterning of the eye in vertebrates has been determined by analyzing the phenotypes of haploid goldfish embryos. There are two gene loci in charge of eye spatial patterning during embryonic morphogenesis. The expressional probability for each copy of the two genes in a set of chromosomes is 50%. A pair of genes in two sets of homologous or heterologous chromosomes is 100% and essential for normal gene expression. The haploid condition itself would result in the obstruction of gene expression and abnormal development because the diploid-dependent regulatory apparatus will regulate gene expression in a haploid embryo according to the same rule as in the diploid embryo.
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Affiliation(s)
- C Luo
- Institute of Biology, Hunan Normal University, Changsha, Hunan 410006, People's Republic of China.
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Russell C. The roles of Hedgehogs and Fibroblast Growth Factors in eye development and retinal cell rescue. Vision Res 2003; 43:899-912. [PMID: 12668059 DOI: 10.1016/s0042-6989(02)00416-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Knowledge of normal eye development is crucial for the development of retinal rescue strategies. I shall focus on two signalling pathways that affect retinal development. Fibroblast growth factors function in retinal cell proliferation, retinal ganglion cell axon guidance and target recognition, craniofacial patterning and lens induction. Hedgehog proteins are required for progression of the neurogenic wave, cell proliferation, photoreceptor differentiation, retinal ganglion cell axon growth and craniofacial patterning. These signalling pathways have pleiotropic effects, can interact and have the potential to be used therapeutically. The zebrafish model organism may be well suited to studying how signalling pathways interact.
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Affiliation(s)
- Claire Russell
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK.
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Goldsmith P, Harris WA. The zebrafish as a tool for understanding the biology of visual disorders. Semin Cell Dev Biol 2003; 14:11-8. [PMID: 12524002 DOI: 10.1016/s1084-9521(02)00167-2] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Retinal degenerations are the commonest cause of blindness in the Western world, affecting 5% of the population, yet remain largely untreatable. A better understanding of the mechanisms of disease is needed. Zebrafish fill a gap in the current repertoire of models, offering genetic tractability in a vertebrate. Their retina has many similarities with a human retina. Importantly, unlike rodents, they have rich colour vision, offering the potential to model the macular degenerations. A variety of physiological assays, genetic manipulations and histological tools have been developed and useful models of human disease created.
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Affiliation(s)
- P Goldsmith
- Department of Anatomy, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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Spitsbergen JM, Kent ML. The state of the art of the zebrafish model for toxicology and toxicologic pathology research--advantages and current limitations. Toxicol Pathol 2003; 31 Suppl:62-87. [PMID: 12597434 PMCID: PMC1909756 DOI: 10.1080/01926230390174959] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The zebrafish (Danio rerio) is now the pre-eminent vertebrate model system for clarification of the roles of specific genes and signaling pathways in development. The zebrafish genome will be completely sequenced within the next 1-2 years. Together with the substantial historical database regarding basic developmental biology, toxicology, and gene transfer, the rich foundation of molecular genetic and genomic data makes zebrafish a powerful model system for clarifying mechanisms in toxicity. In contrast to the highly advanced knowledge base on molecular developmental genetics in zebrafish, our database regarding infectious and noninfectious diseases and pathologic lesions in zebrafish lags far behind the information available on most other domestic mammalian and avian species, particularly rodents. Currently, minimal data are available regarding spontaneous neoplasm rates or spontaneous aging lesions in any of the commonly used wild-type or mutant lines of zebrafish. Therefore, to fully utilize the potential of zebrafish as an animal model for understanding human development, disease, and toxicology we must greatly advance our knowledge on zebrafish diseases and pathology.
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Affiliation(s)
- Jan M Spitsbergen
- Department of Environmental and Molecular Toxicology and Marine/Freshwater Biomedical Sciences Center, Oregon State University, Corvallis, Oregon 97333, USA.
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Garrity DM, Childs S, Fishman MC. Theheartstringsmutation in zebrafish causes heart/fin Tbx5 deficiency syndrome. Development 2002; 129:4635-45. [PMID: 12223419 DOI: 10.1242/dev.129.19.4635] [Citation(s) in RCA: 198] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Holt-Oram syndrome is one of the autosomal dominant human ‘heart-hand’ disorders, with a combination of upper limb malformations and cardiac defects. Holt-Oram syndrome is caused by mutations in the TBX5 gene, a member of a large family of T-box transcription factors that play important roles in cell-type specification and morphogenesis. In a screen for mutations affecting zebrafish cardiac function, we isolated the recessive lethal mutant heartstrings, which lacks pectoral fins and exhibits severe cardiac dysfunction, beginning with a slow heart rate and progressing to a stretched, non-functional heart.We mapped and cloned the heartstrings mutation and find it to encode the zebrafish ortholog of the TBX5 gene. The heartstrings mutation causes premature termination at amino acid 316. Homozygous mutant embryos never develop pectoral fin buds and do not express several markers of early fin differentiation. The total absence of any fin bud differentiation distinguishes heartstrings from most other mutations that affect zebrafish fin development, suggesting that Tbx5 functions very early in the pectoral fin induction pathway. Moderate reduction of Tbx5 by morpholino causes fin malformations, revealing an additional early requirement for Tbx5 in coordinating the axes of fin outgrowth. The heart of heartstrings mutant embryos appears to form and function normally through the early heart tube stage, manifesting only a slight bradycardia compared with wild-type siblings. However, the heart fails to loop and then progressively deteriorates, a process affecting the ventricle as well as the atrium.Relative to mammals, fish require lower levels of Tbx5 to produce malformed appendages and display whole-heart rather than atrial-predominant cardiac defects. However, the syndromic deficiencies of tbx5 mutation are remarkably well retained between fish and mammals.
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Affiliation(s)
- Deborah M Garrity
- Cardiovascular Research Center, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, USA
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