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Wilkinson CJ, Carl M, Harris WA. Cep70 and Cep131 contribute to ciliogenesis in zebrafish embryos. BMC Cell Biol 2009; 10:17. [PMID: 19254375 PMCID: PMC2662791 DOI: 10.1186/1471-2121-10-17] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 03/02/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The centrosome is the cell's microtubule organising centre, an organelle with important roles in cell division, migration and polarity. However, cells can divide and flies can, for a large part of development, develop without them. Many centrosome proteins have been identified but the roles of most are still poorly understood. The centrioles of the centrosome are similar to the basal bodies of cilia, hair-like extensions of many cells that have important roles in cell signalling and development. In a number of human diseases, such Bardet-Biedl syndrome, centrosome/cilium proteins are mutated, leading to polycystic kidney disease, situs inversus, and neurological problems, amongst other symptoms. RESULTS We describe zebrafish (Danio rerio) embryos depleted for two uncharacterised, centrosome proteins, Cep70 and Cep131. The phenotype of these embryos resembles that of zebrafish mutants for intraflagellar transport proteins (IFTs), with kidney and ear development affected and left-right asymmetry randomised. These organs and processes are those affected in Bardet-Biedl syndrome and other similar diseases. Like these diseases, the root cause of the phenotype lies, in fact, in dysfunctional cilia, which are shortened but not eliminated in several tissues in the morphants. Centrosomes and basal bodies, on the other hand, are present. Both Cep70 and Cep131 possess a putative HDAC (histone deacetylase) interacting domain. However, we could not detect in yeast two-hybrid assays any interaction with the deacetylase that controls cilium length, HDAC6, or any of the IFTs that we tested. CONCLUSION Cep70 and Cep131 contribute to ciliogenesis in many tissues in the zebrafish embryo: cilia are made in cep70 and cep131 morphant zebrafish embryos but are shortened. We propose that the role of these centrosomal/basal body proteins is in making the cilium and that they are involved in determination of the length of the axoneme.
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Affiliation(s)
- Christopher J Wilkinson
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK.
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52
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Wang H, Kesinger JW, Zhou Q, Wren JD, Martin G, Turner S, Tang Y, Frank MB, Centola M. Identification and characterization of zebrafish ocular formation genes. Genome 2008; 51:222-35. [PMID: 18356958 DOI: 10.1139/g07-098] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To study genes that are specifically expressed in the eyes, we employed microarray and in situ hybridization analyses to identify and characterize differentially expressed ocular genes in eyeless masterblind (mbl-/-) zebrafish (Danio rerio). Among 70 differentially expressed genes in the mbl-/- mutant identified by microarray analysis, 8 down-regulated genes were characterized, including 4 eye-specific genes, opsin 1 short-wave-sensitive 1 (opn1sw1), crystallinbetaa1b (cryba1b), crystallinbetaa2b (cryba2b), and crystallingamma M2d3 (crygm2d3); 2 eye and brain genes, ATPase, H+ transporting, lysosomal, V0 subunit c (atp6v0c) and basic leucine zipper and W2 domains 1a (bzw1a); and 2 constitutive genes, heat shock protein 8 (hspa8) and ribosomal protein L7a (rpl7a). In situ hybridization experiments confirmed down-regulation of these 8 ocular formation genes in mbl-/- zebrafish and showed their ocular and dynamic temporal expression patterns during zebrafish early development. Further, an automated literature analysis of the 70 differentially expressed genes identified a sub-network of genes with known associations, either with each other or with ocular structures or development, and shows how this study contributes to the current body of knowledge.
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Affiliation(s)
- Han Wang
- Department of Zoology and Stephenson Research and Technology Center, University of Oklahoma, 101 David L. Boren Boulevard, Norman, OK 73019, USA.
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53
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Kleinjan DA, Bancewicz RM, Gautier P, Dahm R, Schonthaler HB, Damante G, Seawright A, Hever AM, Yeyati PL, van Heyningen V, Coutinho P. Subfunctionalization of duplicated zebrafish pax6 genes by cis-regulatory divergence. PLoS Genet 2008; 4:e29. [PMID: 18282108 PMCID: PMC2242813 DOI: 10.1371/journal.pgen.0040029] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Accepted: 12/21/2007] [Indexed: 01/22/2023] Open
Abstract
Gene duplication is a major driver of evolutionary divergence. In most vertebrates a single PAX6 gene encodes a transcription factor required for eye, brain, olfactory system, and pancreas development. In zebrafish, following a postulated whole-genome duplication event in an ancestral teleost, duplicates pax6a and pax6b jointly fulfill these roles. Mapping of the homozygously viable eye mutant sunrise identified a homeodomain missense change in pax6b, leading to loss of target binding. The mild phenotype emphasizes role-sharing between the co-orthologues. Meticulous mapping of isolated BACs identified perturbed synteny relationships around the duplicates. This highlights the functional conservation of pax6 downstream (3') control sequences, which in most vertebrates reside within the introns of a ubiquitously expressed neighbour gene, ELP4, whose pax6a-linked exons have been lost in zebrafish. Reporter transgenic studies in both mouse and zebrafish, combined with analysis of vertebrate sequence conservation, reveal loss and retention of specific cis-regulatory elements, correlating strongly with the diverged expression of co-orthologues, and providing clear evidence for evolution by subfunctionalization.
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MESH Headings
- Animals
- Animals, Genetically Modified
- Base Sequence
- Chromosomes, Artificial, Bacterial/genetics
- Computational Biology
- DNA Primers/genetics
- Enhancer Elements, Genetic
- Evolution, Molecular
- Eye Abnormalities/embryology
- Eye Abnormalities/genetics
- Eye Proteins/genetics
- Gene Duplication
- Gene Expression Regulation, Developmental
- Genes, Homeobox
- Genes, Reporter
- Genetic Complementation Test
- Genetic Linkage
- Homeodomain Proteins/genetics
- Mice
- Mice, Transgenic
- Models, Genetic
- Molecular Sequence Data
- Mutation, Missense
- PAX6 Transcription Factor
- Paired Box Transcription Factors/genetics
- Phenotype
- Repressor Proteins/genetics
- Sequence Homology, Nucleic Acid
- Zebrafish/abnormalities
- Zebrafish/embryology
- Zebrafish/genetics
- Zebrafish Proteins/genetics
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Affiliation(s)
- Dirk A Kleinjan
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Ruth M Bancewicz
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Philippe Gautier
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Ralf Dahm
- Department of Genetics, Max-Planck Institute for Developmental Biology, Tübingen, Germany
| | - Helia B Schonthaler
- Department of Genetics, Max-Planck Institute for Developmental Biology, Tübingen, Germany
| | - Giuseppe Damante
- Department of Science and Biomedical Technology, University of Udine, Udine, Italy
| | - Anne Seawright
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Ann M Hever
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Patricia L Yeyati
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Veronica van Heyningen
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
- * To whom correspondence should be addressed. E-mail:
| | - Pedro Coutinho
- Medical Research Council (MRC) Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
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54
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Abstract
The controlled internalization of membrane receptors and lipids is crucial for cells to control signaling pathways and interact with their environment. During clathrin-mediated endocytosis, membrane constituents are transported via endocytic vesicles into early endosomes, from which they are further distributed within the cell. The small guanosine triphosphatase (GTPase) Rab5 is both required and sufficient for the formation of these early endosomes and can be used to experimentally address endocytic processes. Recent evidence shows that endocytic turnover of E-cadherin regulates the migration of mesendodermal cells during zebrafish gastrulation by modulating their adhesive interactions with neighboring cells. This in turn leads to effective and synchronized movement within the embryo. In this review, we discuss techniques to manipulate E-cadherin endocytosis by morpholino-mediated knockdown of rab5 during zebrafish gastrulation. We describe the use of antibodies specifically directed against zebrafish E-cadherin to detect its intracellular localization and of in situ hybridization and primary cell culture to reveal patterns of cell migration and adhesion, respectively.
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55
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Carl M, Bianco IH, Bajoghli B, Aghaallaei N, Czerny T, Wilson SW. Wnt/Axin1/beta-catenin signaling regulates asymmetric nodal activation, elaboration, and concordance of CNS asymmetries. Neuron 2007; 55:393-405. [PMID: 17678853 PMCID: PMC1940036 DOI: 10.1016/j.neuron.2007.07.007] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Revised: 05/30/2007] [Accepted: 07/06/2007] [Indexed: 10/27/2022]
Abstract
Nodal activity in the left lateral plate mesoderm (LPM) is required to activate left-sided Nodal signaling in the epithalamic region of the zebrafish forebrain. Epithalamic Nodal signaling subsequently determines the laterality of neuroanatomical asymmetries. We show that overactivation of Wnt/Axin1/beta-catenin signaling during late gastrulation leads to bilateral epithalamic expression of Nodal pathway genes independently of LPM Nodal signaling. This is consistent with a model whereby epithalamic Nodal signaling is normally bilaterally repressed, with Nodal signaling from the LPM unilaterally alleviating repression. We suggest that Wnt signaling regulates the establishment of the bilateral repression. We identify a second role for the Wnt pathway in the left/right regulation of LPM Nodal pathway gene expression, and finally, we show that at later stages Axin1 is required for the elaboration of concordant neuroanatomical asymmetries.
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Affiliation(s)
- Matthias Carl
- Department of Anatomy and Developmental Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Isaac H. Bianco
- Department of Anatomy and Developmental Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Baubak Bajoghli
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Veterinarplatz 1, A-1210 Vienna, Austria
| | - Narges Aghaallaei
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Veterinarplatz 1, A-1210 Vienna, Austria
| | - Thomas Czerny
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Veterinarplatz 1, A-1210 Vienna, Austria
- University of Applied Sciences, FH-Campus Wien, Vienna Biocenter, Viehmarktgasse 2A, A-1030 Wien, Vienna, Austria
| | - Stephen W. Wilson
- Department of Anatomy and Developmental Biology, UCL, Gower Street, London WC1E 6BT, UK
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56
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Zeng XXI, Wilm TP, Sepich DS, Solnica-Krezel L. Apelin and its receptor control heart field formation during zebrafish gastrulation. Dev Cell 2007; 12:391-402. [PMID: 17336905 DOI: 10.1016/j.devcel.2007.01.011] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2006] [Revised: 12/16/2006] [Accepted: 01/17/2007] [Indexed: 12/22/2022]
Abstract
The vertebrate heart arises during gastrulation as cardiac precursors converge from the lateral plate mesoderm territories toward the embryonic midline and extend rostrally to form bilateral heart fields. G protein-coupled receptors (GPCRs) mediate functions of the nervous and immune systems; however, their roles in gastrulation remain largely unexplored. Here, we show that the zebrafish homologs of the Agtrl1b receptor and its ligand, Apelin, implicated in physiology and angiogenesis, control heart field formation. Zebrafish gastrulae express agtrl1b in the lateral plate mesoderm, while apelin expression is confined to the midline. Reduced or excess Agtrl1b or Apelin function caused deficiency of cardiac precursors and, subsequently, the heart. In Apelin-deficient gastrulae, the cardiac precursors converged inefficiently to the heart fields and showed ectopic distribution, whereas cardiac precursors overexpressing Apelin exhibited abnormal morphology and rostral migration. Our results implicate GPCR signaling in movements of discrete cell populations that establish organ rudiments during vertebrate gastrulation.
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Affiliation(s)
- Xin-Xin I Zeng
- Vanderbilt University, Department of Biological Sciences, VU Station B 35-1634, Nashville, TN 37235, USA
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57
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Ermakova GV, Solovieva EA, Martynova NY, Zaraisky AG. The homeodomain factor Xanf represses expression of genes in the presumptive rostral forebrain that specify more caudal brain regions. Dev Biol 2007; 307:483-97. [PMID: 17511981 DOI: 10.1016/j.ydbio.2007.03.524] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Revised: 03/27/2007] [Accepted: 03/30/2007] [Indexed: 01/26/2023]
Abstract
Early development of the rostral forebrain (RF) in vertebrates is accompanied by the inhibition of two homeobox regulators, Otx2 and Pax6 in the rostral sector of the anterior neural plate, further giving rise to the RF. However, the precise molecular mechanism and meaning of this inhibition is still obscure. We now demonstrate that the activity of the Anf homeodomain protein is necessary and sufficient for the anterior inhibition of Otx2 and Pax6. Specifically, we show that knockdown of the Xenopus laevis Anf, Xanf, by antisense morpholino oligonucleotides results in the anterior expansion of Otx2 and Pax6 expression into the presumptive RF territory. Furthermore, by overexpressing hormone-inducible activator- and repressor-fused variants of Xanf in the absence of protein synthesis, we present evidence that Xanf can directly downregulate Otx2 and Pax6 but not the more rostrally expressed Bf1, Bf2, Fgf8 and Nkx2.4. These results explain how the inhibitory activity of Xanf can discriminate RF regulators in favor of posterior forebrain ones. Assuming that the Anf type of homeobox is specific for vertebrates, our data suggest that the emergence of Anf in evolution could be a critical event for RF development in vertebrates through the elimination of homologues of modern posterior forebrain regulators from the rostral sector of the anterior neural plate.
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Affiliation(s)
- Galina V Ermakova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences, Moscow, Russia
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58
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Yeyati PL, Bancewicz RM, Maule J, van Heyningen V. Hsp90 selectively modulates phenotype in vertebrate development. PLoS Genet 2007; 3:e43. [PMID: 17397257 PMCID: PMC1839141 DOI: 10.1371/journal.pgen.0030043] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Accepted: 02/07/2007] [Indexed: 11/18/2022] Open
Abstract
Compromised heat shock protein 90 (Hsp90) function reveals cryptic phenotypes in flies and plants. These observations were interpreted to suggest that this molecular stress-response chaperone has a capacity to buffer underlying genetic variation. Conversely, the protective role of Hsp90 could account for the variable penetrance or severity of some heritable developmental malformations in vertebrates. Using zebrafish as a model, we defined Hsp90 inhibitor levels that did not induce a heat shock response or perturb phenotype in wild-type strains. Under these conditions the severity of the recessive eye phenotype in sunrise, caused by a pax6b mutation, was increased, while in dreumes, caused by a sufu mutation, it was decreased. In another strain, a previously unobserved spectrum of severe structural eye malformations, reminiscent of anophthalmia, microphthalmia, and nanophthalmia complex in humans, was uncovered by this limited inhibition of Hsp90 function. Inbreeding of offspring from selected unaffected carrier parents led to significantly elevated malformation frequencies and revealed the oligogenic nature of this phenotype. Unlike in Drosophila, Hsp90 inhibition can decrease developmental stability in zebrafish, as indicated by increased asymmetric presentation of anophthalmia, microphthalmia, and nanophthalmia and sunrise phenotypes. Analysis of the sunrise pax6b mutation suggests a molecular mechanism for the buffering of mutations by Hsp90. The zebrafish studies imply that mild perturbation of Hsp90 function at critical developmental stages may underpin the variable penetrance and expressivity of many developmental anomalies where the interaction between genotype and environment plays a major role. Genetic variation is not always expressed as a single consistent phenotype even in familial diseases. Unilateral malformations in paired organs, such as the failure of an eye to develop on one side only, also remind us that gene function is often modified by environmental factors. Following observations by others in fruit flies, we explored the underlying mechanisms for such phenotypic fluctuation, using zebrafish as a vertebrate model. Earlier work suggested involvement of chaperone proteins like Hsp90, which assist with normal protein folding during development and also work overtime to keep proteins functional in response to environmental stress. Using specific drugs at defined times in early development for the limited reduction of Hsp90 activity, we showed that different cryptic genetic variants could be revealed consistently in genetically distinct fish strains. Once uncovered, the frequency of these variants was increased by inbreeding, confirming the role of underlying genetic factors. Similarly, we could modify the phenotypic severity of some—but not all—known gene variants, worsening some and improving others. It emerged that the most susceptible variants were those carrying amino acid alterations, in which assisted protein folding may either restore near normal function or facilitate malfunction, thus worsening phenotype. This insight may allow us to prevent recurrent malformations by minimizing or perhaps even counteracting the effects of exposure to environmental stress during development.
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Affiliation(s)
- Patricia L Yeyati
- Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
- * To whom correspondence should be addressed. E-mail: (PLY); (VvH)
| | - Ruth M Bancewicz
- Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - John Maule
- Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Veronica van Heyningen
- Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
- * To whom correspondence should be addressed. E-mail: (PLY); (VvH)
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59
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Rorick AM, Mei W, Liette NL, Phiel C, El-Hodiri HM, Yang J. PP2A:B56ε is required for eye induction and eye field separation. Dev Biol 2007; 302:477-93. [PMID: 17074314 DOI: 10.1016/j.ydbio.2006.10.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Revised: 09/29/2006] [Accepted: 10/05/2006] [Indexed: 12/18/2022]
Abstract
Eye induction and eye field separation are the earliest events during vertebrate eye development. Both of these processes occur much earlier than the formation of optic vesicles. The insulin-like growth factor (IGF) pathway appears to be essential for eye induction, yet it remains unclear how IGF downstream pathways are involved in eye induction. As a consequence of eye induction, a single eye anlage is specified in the anterior neural plate. Subsequently, this single eye anlage is divided into two symmetric eye fields in response to Sonic Hedgehog (Shh) secreted from the prechordal mesoderm. Here, we report that B56epsilon regulatory subunit of protein phosphatase 2A (PP2A) is involved in Xenopus eye induction and subsequent eye field separation. We provide evidence that B56epsilon is required for the IGF/PI3K/Akt pathway and that interfering with the PI3K/Akt pathway inhibits eye induction. In addition, we show that B56epsilon regulates the Hedgehog (Hh) pathway during eye field separation. Thus, B56epsilon is involved in multiple signaling pathways and plays critical roles during early development.
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Affiliation(s)
- Anna M Rorick
- Columbus Children's Research Institute, Department of Pediatrics, The Ohio State University, Columbus, OH 43205, USA
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60
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Rohde LA, Heisenberg CP. Zebrafish Gastrulation: Cell Movements, Signals, and Mechanisms. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 261:159-92. [PMID: 17560282 DOI: 10.1016/s0074-7696(07)61004-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Gastrulation is a morphogenetic process that results in the formation of the embryonic germ layers. Here we detail the major cell movements that occur during zebrafish gastrulation: epiboly, internalization, and convergent extension. Although gastrulation is known to be regulated by signaling pathways such as the Wnt/planar cell polarity pathway, many questions remain about the underlying molecular and cellular mechanisms. Key factors that may play a role in gastrulation cell movements are cell adhesion and cytoskeletal rearrangement. In addition, some of the driving force for gastrulation may derive from tissue interactions such as those described between the enveloping layer and the yolk syncytial layer. Future exploration of gastrulation mechanisms relies on the development of sensitive and quantitative techniques to characterize embryonic germ-layer properties.
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Affiliation(s)
- Laurel A Rohde
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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61
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Kazakova N, Li H, Mora A, Jessen KR, Mirsky R, Richardson WD, Smith HK. A screen for mutations in zebrafish that affect myelin gene expression in Schwann cells and oligodendrocytes. Dev Biol 2006; 297:1-13. [PMID: 16839543 DOI: 10.1016/j.ydbio.2006.03.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Revised: 03/13/2006] [Accepted: 03/15/2006] [Indexed: 10/24/2022]
Abstract
Myelin is the multi-layered glial sheath around axons in the vertebrate nervous system. Myelinating glia develop and function in intimate association with neurons and neuron-glial interactions control much of the life history of these cells. However, many of the factors that regulate key aspects of myelin development and maintenance remain unknown. To discover new molecules that are important for glial development and myelination, we undertook a screen of zebrafish mutants with previously characterized neural defects. We screened for myelin basic protein (mbp) mRNA by in situ hybridization and identified four mutants (neckless, motionless, iguana and doc) that lacked mbp expression in parts of the peripheral and central nervous systems (PNS or CNS), despite the presence of axons. In all four mutants electron microscopy revealed that myelin-forming glia were present and had formed loose wraps around axons but did not form compact myelin. We found that addition of exogenous retinoic acid (RA) rescued mbp expression in neckless mutant embryos, which lack endogenous RA synthesis. Timed application of the RA synthesis inhibitor DEAB to wild type embryos showed that RA signalling is required at least 48 h before the onset of myelin protein synthesis in both CNS and PNS.
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Affiliation(s)
- Natalia Kazakova
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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62
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Kim HJ, Schleiffarth JR, Jessurun J, Sumanas S, Petryk A, Lin S, Ekker SC. Wnt5 signaling in vertebrate pancreas development. BMC Biol 2005; 3:23. [PMID: 16246260 PMCID: PMC1276788 DOI: 10.1186/1741-7007-3-23] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2005] [Accepted: 10/24/2005] [Indexed: 12/27/2022] Open
Abstract
Background Signaling by the Wnt family of secreted glycoproteins through their receptors, the frizzled (Fz) family of seven-pass transmembrane proteins, is critical for numerous cell fate and tissue polarity decisions during development. Results We report a novel role of Wnt signaling in organogenesis using the formation of the islet during pancreatic development as a model tissue. We used the advantages of the zebrafish to visualize and document this process in living embryos and demonstrated that insulin-positive cells actively migrate to form an islet. We used morpholinos (MOs), sequence-specific translational inhibitors, and time-lapse imaging analysis to show that the Wnt-5 ligand and the Fz-2 receptor are required for proper insulin-cell migration in zebrafish. Histological analyses of islets in Wnt5a-/- mouse embryos showed that Wnt5a signaling is also critical for murine pancreatic insulin-cell migration. Conclusion Our results implicate a conserved role of a Wnt5/Fz2 signaling pathway in islet formation during pancreatic development. This study opens the door for further investigation into a role of Wnt signaling in vertebrate organ development and disease.
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Affiliation(s)
- Hyon J Kim
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455 USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095 USA
| | - Jack R Schleiffarth
- Department of Pediatrics, University of Minnesota, Minneapolis, MN 55455 USA
| | - Jose Jessurun
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455 USA
| | - Saulius Sumanas
- Department of Molecular, Cellular, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095 USA
| | - Anna Petryk
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455 USA
- Department of Pediatrics, University of Minnesota, Minneapolis, MN 55455 USA
| | - Shuo Lin
- Department of Molecular, Cellular, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095 USA
| | - Stephen C Ekker
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455 USA
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63
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Jülich D, Hwee Lim C, Round J, Nicolaije C, Schroeder J, Davies A, Geisler R, Lewis J, Jiang YJ, Holley SA. beamter/deltaC and the role of Notch ligands in the zebrafish somite segmentation, hindbrain neurogenesis and hypochord differentiation. Dev Biol 2005; 286:391-404. [PMID: 16125692 DOI: 10.1016/j.ydbio.2005.06.040] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Revised: 05/12/2005] [Accepted: 06/17/2005] [Indexed: 11/16/2022]
Abstract
The Tübingen large-scale zebrafish genetic screen completed in 1996 identified a set of five genes required for orderly somite segmentation. Four of them have been molecularly identified and three were found to code for components of the Notch pathway, which are required for the coordinated oscillation of gene expression, known as the segmentation clock, in the presomitic mesoderm (PSM). Here, we show that the final member of the group, beamter (bea), codes for the Notch ligand DeltaC, and we present and characterize two new alleles, including one allele encoding for a protein truncated in the 7th EGF repeat and an allele deleting only the DSL domain which was previously shown to be necessary for ligand function. Interestingly however, when we over-express any of the mutant deltaC mRNAs, we observe antimorphic effects on both hindbrain neurogenesis and hypochord formation. Expression of bea/deltaC oscillates in the PSM, and a triple fluorescent in situ analysis of its oscillation in relation to that of other oscillating genes in the PSM reveals differences in subcellular localization of the oscillating mRNAs in individual cells in different oscillation phases. Mutations in aei/deltaD and bea/deltaC differ in the way they disrupt the oscillating expression of her1 and deltaC. Furthermore, we find that the double mutants have significantly stronger defects in hypochord formation but not in somitogenesis or hindbrain neurogenesis, indicating genetically that the two delta's may function either semi-redundantly or distinctly, depending upon context.
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Affiliation(s)
- Dörthe Jülich
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA
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64
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Koudijs MJ, den Broeder MJ, Keijser A, Wienholds E, Houwing S, van Rooijen EMHC, Geisler R, van Eeden FJM. The zebrafish mutants dre, uki, and lep encode negative regulators of the hedgehog signaling pathway. PLoS Genet 2005; 1:e19. [PMID: 16121254 PMCID: PMC1189072 DOI: 10.1371/journal.pgen.0010019] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Accepted: 06/23/2005] [Indexed: 11/19/2022] Open
Abstract
Proliferation is one of the basic processes that control embryogenesis. To identify factors involved in the regulation of proliferation, we performed a zebrafish genetic screen in which we used proliferating cell nuclear antigen (PCNA) expression as a readout. Two mutants, hu418B and hu540A, show increased PCNA expression. Morphologically both mutants resembled the dre (dreumes), uki (ukkie), and lep (leprechaun) mutant class and both are shown to be additional uki alleles. Surprisingly, although an increased size is detected of multiple structures in these mutant embryos, adults become dwarfs. We show that these mutations disrupt repressors of the Hedgehog (Hh) signaling pathway. The dre, uki, and lep loci encode Su(fu) (suppressor of fused), Hip (Hedgehog interacting protein), and Ptc2 (Patched2) proteins, respectively. This class of mutants is therefore unique compared to previously described Hh mutants from zebrafish genetic screens, which mainly show loss of Hh signaling. Furthermore, su(fu) and ptc2 mutants have not been described in vertebrate model systems before. Inhibiting Hh activity by cyclopamine rescues uki and lep mutants and confirms the overactivation of the Hh signaling pathway in these mutants. Triple uki/dre/lep mutants show neither an additive increase in PCNA expression nor enhanced embryonic phenotypes, suggesting that other negative regulators, possibly Ptc1, prevent further activation of the Hh signaling pathway. The effects of increased Hh signaling resulting from the genetic alterations in the uki, dre, and lep mutants differ from phenotypes described as a result of Hh overexpression and therefore provide additional insight into the role of Hh signaling during vertebrate development. In a screen aimed at finding genes that control proliferation in the zebrafish embryo, three mutants were identified. Mutants showed an increase in size of several structures including the brain, the retina, and the fins. Surprisingly, although size was increased in the embryos, adults remained small. Cloning of these genes revealed that increased Hedgehog signaling was at the basis of the phenotype, because all three genes encoded known repressors of the Hedgehog signaling pathway: Ptc2, Su(Fu), and Hip. Hedgehog is known to play a role in proliferation. For instance, ectopic Hedgehog signaling can lead to several tumors including basal cell carcinoma and medulloblastoma. However, the phenotypes were still a surprise, because earlier experiments in zebrafish embryos suggested that activation should lead to patterning rather than proliferation defects. Current models of the pathway predict that these genes act independently to inhibit the signal but curiously, redundancy amongst these genes was not found, because triple mutants looked like the single mutants. The conclusion is that weak activation of Hedgehog signaling can already lead to stimulation of growth in the absence of patterning defects, and that the Hedgehog signal is probably kept in check by the last inhibitor: Ptc1. A mutant for the ptc1 gene has recently been created and will put the model to the test.
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Affiliation(s)
- Marco J Koudijs
- Hubrecht Laboratory, The Netherlands Institute for Developmental Biology, Utrecht, The Netherlands
| | - Marjo J. den Broeder
- Hubrecht Laboratory, The Netherlands Institute for Developmental Biology, Utrecht, The Netherlands
| | - Astrid Keijser
- Hubrecht Laboratory, The Netherlands Institute for Developmental Biology, Utrecht, The Netherlands
| | - Erno Wienholds
- Hubrecht Laboratory, The Netherlands Institute for Developmental Biology, Utrecht, The Netherlands
| | - Saskia Houwing
- Hubrecht Laboratory, The Netherlands Institute for Developmental Biology, Utrecht, The Netherlands
| | | | - Robert Geisler
- Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany
| | - Fredericus J. M. van Eeden
- Hubrecht Laboratory, The Netherlands Institute for Developmental Biology, Utrecht, The Netherlands
- *To whom correspondence should be addressed. E-mail:
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65
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Jopling C, den Hertog J. Fyn/Yes and non-canonical Wnt signalling converge on RhoA in vertebrate gastrulation cell movements. EMBO Rep 2005; 6:426-31. [PMID: 15815683 PMCID: PMC1299299 DOI: 10.1038/sj.embor.7400386] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2004] [Revised: 02/08/2005] [Accepted: 03/02/2005] [Indexed: 11/09/2022] Open
Abstract
Convergent extension (CE) cell movements during gastrulation mediate extension of the anterior-posterior body axis of vertebrate embryos. Non-canonical Wnt5 and Wnt11 signalling is essential for normal CE movements in vertebrate gastrulation. Here, we show that morpholino (MO)-mediated double knock-down of the Fyn and Yes tyrosine kinases in zebrafish embryos impaired normal CE cell movements, resembling the silberblick and pipetail mutants, caused by mutations in wnt11 and wnt5, respectively. Co-injection of Fyn/Yes- and Wnt11- or Wnt5-MO was synergistic, but wnt11 or wnt5 RNA did not rescue the Fyn/Yes knockdown or vice versa. Remarkably, active RhoA rescued the Fyn/Yes knockdown as well as the Wnt11 knockdown, indicating that Fyn/Yes and Wnt11 signalling converged on RhoA. Our results show that Fyn and Yes act together with non-canonical Wnt signalling via RhoA in CE cell movements during gastrulation.
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Affiliation(s)
- Chris Jopling
- Hubrecht Laboratory, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Jeroen den Hertog
- Hubrecht Laboratory, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
- Tel: +31 30 2121800; Fax: +31 30 2516464; E-mail:
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66
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Furutani-Seiki M, Sasado T, Morinaga C, Suwa H, Niwa K, Yoda H, Deguchi T, Hirose Y, Yasuoka A, Henrich T, Watanabe T, Iwanami N, Kitagawa D, Saito K, Asaka S, Osakada M, Kunimatsu S, Momoi A, Elmasri H, Winkler C, Ramialison M, Loosli F, Quiring R, Carl M, Grabher C, Winkler S, Del Bene F, Shinomiya A, Kota Y, Yamanaka T, Okamoto Y, Takahashi K, Todo T, Abe K, Takahama Y, Tanaka M, Mitani H, Katada T, Nishina H, Nakajima N, Wittbrodt J, Kondoh H. A systematic genome-wide screen for mutations affecting organogenesis in Medaka, Oryzias latipes. Mech Dev 2005; 121:647-58. [PMID: 15210174 DOI: 10.1016/j.mod.2004.04.016] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2004] [Revised: 03/22/2004] [Accepted: 04/21/2004] [Indexed: 01/24/2023]
Abstract
A large-scale mutagenesis screen was performed in Medaka to identify genes acting in diverse developmental processes. Mutations were identified in homozygous F3 progeny derived from ENU-treated founder males. In addition to the morphological inspection of live embryos, other approaches were used to detect abnormalities in organogenesis and in specific cellular processes, including germ cell migration, nerve tract formation, sensory organ differentiation and DNA repair. Among 2031 embryonic lethal mutations identified, 312 causing defects in organogenesis were selected for further analyses. From these, 126 mutations were characterized genetically and assigned to 105 genes. The similarity of the development of Medaka and zebrafish facilitated the comparison of mutant phenotypes, which indicated that many mutations in Medaka cause unique phenotypes so far unrecorded in zebrafish. Even when mutations of the two fish species cause a similar phenotype such as one-eyed-pinhead or parachute, more genes were found in Medaka than in zebrafish that produced the same phenotype when mutated. These observations suggest that many Medaka mutants represent new genes and, therefore, are important complements to the collection of zebrafish mutants that have proven so valuable for exploring genomic function in development.
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Affiliation(s)
- Makoto Furutani-Seiki
- Japan Science and Technology Corporation, Kondoh Differentiation Signaling Project, Kawaaracho 14, Yoshida, Sakyoku, Kyoto 606-8305, Japan.
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67
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Kitagawa D, Watanabe T, Saito K, Asaka S, Sasado T, Morinaga C, Suwa H, Niwa K, Yasuoka A, Deguchi T, Yoda H, Hirose Y, Henrich T, Iwanami N, Kunimatsu S, Osakada M, Winkler C, Elmasri H, Wittbrodt J, Loosli F, Quiring R, Carl M, Grabher C, Winkler S, Del Bene F, Momoi A, Katada T, Nishina H, Kondoh H, Furutani-Seiki M. Genetic dissection of the formation of the forebrain in Medaka, Oryzias latipes. Mech Dev 2005; 121:673-85. [PMID: 15210176 DOI: 10.1016/j.mod.2004.03.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2004] [Revised: 03/16/2004] [Accepted: 03/18/2004] [Indexed: 01/12/2023]
Abstract
The forebrain, consisting of the telencephalon and diencephalon, is essential for processing sensory information. To genetically dissect formation of the forebrain in vertebrates, we carried out a systematic screen for mutations affecting morphogenesis of the forebrain in Medaka. Thirty-three mutations defining 25 genes affecting the morphological development of the forebrain were grouped into two classes. Class 1 mutants commonly showing a decrease in forebrain size, were further divided into subclasses 1A to 1D. Class 1A mutation (1 gene) caused an early defect evidenced by the lack of bf1 expression, Class 1B mutations (6 genes) patterning defects revealed by the aberrant expression of regional marker genes, Class 1C mutation (1 gene) a defect in a later stage, and Class 1D (3 genes) a midline defect analogous to the zebrafish one-eyed pinhead mutation. Class 2 mutations caused morphological abnormalities in the forebrain without considerably affecting its size, Class 2A mutations (6 genes) caused abnormalities in the development of the ventricle, Class 2B mutations (2 genes) severely affected the anterior commissure, and Class 2C (6 genes) mutations resulted in a unique forebrain morphology. Many of these mutants showed the compromised sonic hedgehog expression in the zona-limitans-intrathalamica (zli), arguing for the importance of this structure as a secondary signaling center. These mutants should provide important clues to the elucidation of the molecular mechanisms underlying forebrain development, and shed new light on phylogenically conserved and divergent functions in the developmental process.
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Affiliation(s)
- Daiju Kitagawa
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
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68
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Gross JM, Perkins BD, Amsterdam A, Egaña A, Darland T, Matsui JI, Sciascia S, Hopkins N, Dowling JE. Identification of zebrafish insertional mutants with defects in visual system development and function. Genetics 2005; 170:245-61. [PMID: 15716491 PMCID: PMC1444939 DOI: 10.1534/genetics.104.039727] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genetic analysis in zebrafish has been instrumental in identifying genes necessary for visual system development and function. Recently, a large-scale retroviral insertional mutagenesis screen, in which 315 different genes were mutated, that resulted in obvious phenotypic defects by 5 days postfertilization was completed. That the disrupted gene has been identified in each of these mutants provides unique resource through which the formation, function, or physiology of individual organ systems can be studied. To that end, a screen for visual system mutants was performed on 250 of the mutants in this collection, examining each of them histologically for morphological defects in the eye and behaviorally for overall visual system function. Forty loci whose disruption resulted in defects in eye development and/or visual function were identified. The mutants have been divided into the following phenotypic classes that show defects in: (1) morphogenesis, (2) growth and central retinal development, (3) the peripheral marginal zone, (4) retinal lamination, (5) the photoreceptor cell layer, (6) the retinal pigment epithelium, (7) the lens, (8) retinal containment, and (9) behavior. The affected genes in these mutants highlight a diverse set of proteins necessary for the development, maintenance, and function of the vertebrate visual system.
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Affiliation(s)
- Jeffrey M Gross
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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69
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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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70
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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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71
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Ekström P, Meissl H. Evolution of photosensory pineal organs in new light: the fate of neuroendocrine photoreceptors. Philos Trans R Soc Lond B Biol Sci 2004; 358:1679-700. [PMID: 14561326 PMCID: PMC1693265 DOI: 10.1098/rstb.2003.1303] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Pineal evolution is envisaged as a gradual transformation of pinealocytes (a gradual regression of pinealocyte sensory capacity within a particular cell line), the so-called sensory cell line of the pineal organ. In most non-mammals the pineal organ is a directly photosensory organ, while the pineal organ of mammals (epiphysis cerebri) is a non-sensory neuroendocrine organ under photoperiod control. The phylogenetic transformation of the pineal organ is reflected in the morphology and physiology of the main parenchymal cell type, the pinealocyte. In anamniotes, pinealocytes with retinal cone photoreceptor-like characteristics predominate, whereas in sauropsids so-called rudimentary photoreceptors predominate. These have well-developed secretory characteristics, and have been interpreted as intermediaries between the anamniote pineal photoreceptors and the mammalian non-sensory pinealocytes. We have re-examined the original studies on which the gradual transformation hypothesis of pineal evolution is based, and found that the evidence for this model of pineal evolution is ambiguous. In the light of recent advances in the understanding of neural development mechanisms, we propose a new hypothesis of pineal evolution, in which the old notion 'gradual regression within the sensory cell line' should be replaced with 'changes in fate restriction within the neural lineage of the pineal field'.
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Affiliation(s)
- Peter Ekström
- Institute of Cell and Organism Biology, Zoology Building, Lund University, Helgonavägen 3, S-223 62 Lund, Sweden.
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72
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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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73
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Westfall TA, Brimeyer R, Twedt J, Gladon J, Olberding A, Furutani-Seiki M, Slusarski DC. Wnt-5/pipetail functions in vertebrate axis formation as a negative regulator of Wnt/beta-catenin activity. J Cell Biol 2003; 162:889-98. [PMID: 12952939 PMCID: PMC2172822 DOI: 10.1083/jcb.200303107] [Citation(s) in RCA: 205] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2003] [Accepted: 07/02/2003] [Indexed: 11/22/2022] Open
Abstract
We provide genetic evidence defining a role for noncanonical Wnt function in vertebrate axis formation. In zebrafish, misexpression of Wnt-4, -5, and -11 stimulates calcium (Ca2+) release, defining the Wnt/Ca2+ class. We describe genetic interaction between two Wnt/Ca2+ members, Wnt-5 (pipetail) and Wnt-11 (silberblick), and a reduction of Ca2+ release in Wnt-5/pipetail. Embryos genetically depleted of both maternal and zygotic Wnt-5 product exhibit cell movement defects as well as hyperdorsalization and axis-duplication phenotypes. The dorsalized phenotypes result from increased beta-catenin accumulation and activation of downstream genes. The Wnt-5 loss-of-function defect is consistent with Ca2+ modulation having an antagonistic interaction with Wnt/beta-catenin signaling.
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Affiliation(s)
- Trudi A Westfall
- Department of Biological Sciences, University of Iowa, Iowa City, IA 52242, USA
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74
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Jang WS, Kim EJ, Ro H, Kim KE, Huh TL, Kim CH, Rhee M. Expression of a novel type I keratin, DAPK-1 in the dorsal aorta and pronephric duct of the zebrafish embryos. Gene 2003; 312:145-50. [PMID: 12909350 DOI: 10.1016/s0378-1119(03)00611-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We isolated a novel cytokeratin gene of zebrafish (Danio rerio), DAPK-1 closely related to other vertebrate type I cytokeratin genes. Zygotic transcription starts at the sphere stage. After the mid-blastula stage, DAPK-1 is expressed in all surface cells, notably in those of the outer enveloping layer. DAPK-1 messages are also present specifically during the segmentation, pharyngula, and hatching periods. In particular, after 24 h post-fertilization, its expression is restricted to the developing eye region, otic vesicle, pectoral fin, dorsal aorta, and pronephric duct. In the mindbomb mutant embryo that has defects in the dorsal aorta development, DAPK-1 transcripts are not detected in the dorsal aorta and pronephric duct. The characteristic expression pattern of DAPK-1 may facilitate more detailed studies related to the morphogenesis of dorsal aorta and pronephric duct.
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Affiliation(s)
- Woo S Jang
- Department of Biology, College of Natural Sciences Chungnam National University, Daejeon 305-764, South Korea
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75
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Sanders LH, Whitlock KE. Phenotype of the zebrafish masterblind (mbl) mutant is dependent on genetic background. Dev Dyn 2003; 227:291-300. [PMID: 12761856 DOI: 10.1002/dvdy.10308] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The zebrafish masterblind (mbl) mutant is characterized by the lack of olfactory placodes and optic vesicles, reduced telencephalon, an expanded epiphysis (Heisenberg et al. [1996] Development 123:191-203), and enlarged jaw. To understand the cellular events giving rise to the olfactory placode defect of this mutant, we examined the expression pattern of the distal-less-3 (dlx3) gene in mbl. In the mutant, dlx3, which is normally expressed in the developing nose and ear, showed reduced expression in the olfactory placode field, but normal expression in the developing ear. To determine whether the loss of dlx3 expression was due to cell loss, we assayed cell death by using TUNEL labeling. Although cell death in the mutant was not concentrated in the region of dlx3 expression, there was increased cell death in the forebrain, epiphysis, and jaw region, as compared with that in wild-type controls. This cell death phenotype was cyclical in nature, showing an increase and decrease in cell death on a roughly 24-hr cycle. Further analysis showed that this cyclical phenotype was specific to the genetic background. The severity of the mbl phenotype, including cell death, expanded epiphysis, and enlarged jaw, decreased when the mutation was moved from the original "TL" background to the "AB" background. Thus, the severity of developmental defects in the mbl mutant is strongly dependent on genetic background. We examined the contribution of cell death to the morphologic defects of mbl by blocking cell death by using zVADfmk, a known caspase inhibitor. We found that this treatment partially rescued the expanded jaw defect and that this rescue was dependent on the genetic background. Therefore, the mbl mutant phenotypes result, in part, from genetic background effects that alter the pattern of programmed cell death early in development.
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Affiliation(s)
- L H Sanders
- Field of Genetics and Development/Neurobiology and Behavior, Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, USA
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76
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Kilian B, Mansukoski H, Barbosa FC, Ulrich F, Tada M, Heisenberg CP. The role of Ppt/Wnt5 in regulating cell shape and movement during zebrafish gastrulation. Mech Dev 2003; 120:467-76. [PMID: 12676324 DOI: 10.1016/s0925-4773(03)00004-2] [Citation(s) in RCA: 251] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Wnt genes play important roles in regulating patterning and morphogenesis during vertebrate gastrulation. In zebrafish, slb/wnt11 is required for convergence and extension movements, but not cell fate specification during gastrulation. To determine if other Wnt genes functionally interact with slb/wnt11, we analysed the role of ppt/wnt5 during zebrafish gastrulation. ppt/wnt5 is maternally provided and zygotically expressed at all stages during gastrulation. The analysis of ppt mutant embryos reveals that Ppt/Wnt5 regulates cell elongation and convergent extension movements in posterior regions of the gastrula, while its function in more anterior regions is largely redundant to that of Slb/Wnt11. Frizzled-2 functions downstream of ppt/wnt5, indicating that it might act as a receptor for Ppt/Wnt5 in this process. The characterisation of the role of Ppt/Wnt5 provides insight into the functional diversity of Wnt genes in regulating vertebrate gastrulation movements.
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Affiliation(s)
- Beate Kilian
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerasse 108, 01307 Dresden, Germany
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77
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Heisenberg CP, Tada M. Zebrafish gastrulation movements: bridging cell and developmental biology. Semin Cell Dev Biol 2002; 13:471-9. [PMID: 12468250 DOI: 10.1016/s1084952102001003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
During vertebrate gastrulation, large cellular rearrangements lead to the formation of the three germ layers, ectoderm, mesoderm and endoderm. Zebrafish offer many genetic and experimental advantages for studying vertebrate gastrulation movements. For instance, several mutants, including silberblick, knypek and trilobite, exhibit defects in morphogenesis during gastrulation. The identification of the genes mutated in these lines together with the analysis of the mutant phenotypes has provided new insights into the molecular and cellular mechanisms that underlie vertebrate gastrulation movements.
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Affiliation(s)
- Carl Philipp Heisenberg
- Max-Planck-Institute for Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307, Dresden, Germany.
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78
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Abstract
Genetic screens in zebrafish have identified a large number of mutations that affect neural connectivity in the developing visual system. These mutants define genes essential for accurate retinal axon guidance in the eye and brain and the characterization of these mutants is helping to define the cellular and molecular mechanisms that guide axons in the vertebrate embryo. The combination of zebrafish genetic and embryological approaches promises to greatly increase our understanding of how multiple guidance mechanisms establish the complex neural interconnectivity of the vertebrate brain.
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Affiliation(s)
- James Culverwell
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
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79
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Abstract
Experimental manipulation and other lines of evidence indicate that the lens plays a prominent role in the growth and differentiation of the vertebrate eye. Here we describe a lens transplantation method for studying the role of the lens in teleost eye development. The method involves three steps: (1) preparing embryos for the operations by embedding them in agar, (2) microsurgery with tungsten needles to remove the lens from a donor embryo and insert it into the optic cup of a host embryo lacking its own lens, and (3) a recovery period allowing surface ectoderm to close over the wound left by insertion of the lens into the host embryo. A movie illustrating the method can be found at http://www.life.umd.edu/labs/jeffery. A troubleshooting guide and summary of assays for evaluating the development of the transplanted lens and its effects on other eye parts, including the retina, are presented. Finally, some current applications of the lens transplantation method are briefly described: (1) determination of the autonomy of zebrafish lens mutants and (2) investigation of the role of the lens in eye degeneration in the cavefish Astyanax. The transplantation method will help characterize the mechanisms through which vertebrate eye development is regulated by the lens.
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80
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Asaoka Y, Mano H, Kojima D, Fukada Y. Pineal expression-promoting element (PIPE), a cis-acting element, directs pineal-specific gene expression in zebrafish. Proc Natl Acad Sci U S A 2002; 99:15456-61. [PMID: 12438694 PMCID: PMC137738 DOI: 10.1073/pnas.232444199] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2002] [Indexed: 11/18/2022] Open
Abstract
The pineal gland, sharing morphological and biochemical similarities with the retina, plays a unique and central role in the photoneuroendocrine system. The unique development of the pineal gland is directed by a specific combination of the expressed genes, but little is known about the regulatory mechanism underlying the pineal-specific gene expression. We isolated a 1.1-kbp fragment upstream of the zebrafish exo-rhodopsin (exorh) gene, which is expressed specifically in the pineal gland. Transgenic analysis using an enhanced green fluorescent protein reporter gene demonstrated that the proximal 147-bp region of the exorh promoter is sufficient to direct pineal-specific expression. This region contains three copies of a putative cone rod homeobox (Crx)Otx-binding site, which is known to be required for expression of both retina- and pineal-specific genes. Deletion and mutational analyses of the exorh promoter revealed that a previously uncharacterized sequence TGACCCCAATCT termed pineal expression-promoting element (PIPE) is required for pineal-specific promoter activity in addition to the CrxOtx-binding sites. By using the zebrafish rhodopsin (rh) promoter that drives retina-specific expression, we created a reporter construct having ectopic PIPE in the rh promoter at a position equivalent to that in the exorh promoter by introducing five nucleotide changes. Such a slight modification in the rh promoter induced ectopic enhanced green fluorescent protein expression in the pineal gland without affecting its retinal expression. These results identify PIPE as a critical cis-element contributing to the pineal-specific gene expression, in combination with the CrxOtx-binding site(s).
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Affiliation(s)
- Yoichi Asaoka
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Japan
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81
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Lacbawan FL, Muenke M. Central nervous system embryogenesis and its failures. Pediatr Dev Pathol 2002; 5:425-47. [PMID: 12202995 DOI: 10.1007/s10024-002-0003-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2001] [Accepted: 12/01/2001] [Indexed: 11/29/2022]
Abstract
The well-orchestrated development of the central nervous system (CNS) requires highly integrated regulatory processes to ensure its precise spatial organization that provides the foundation for proper function. As emphasized in this review, the type, timing, and location of regulatory molecules influence the different stages of development from neuronal induction, regional specification, neuronal specification, and neuronal migration to axonal growth and guidance, neuronal survival, and synapse formation. The known molecular mechanisms are summarized from studies of invertebrates and lower vertebrates, in which we have learned more about the different ligands, receptors, transcription factors, and the intracellular signaling pathways that play specific roles in the different stages of development. Despite known molecular mechanisms of some disturbances, most of the clinical entities that arise from failures of CNS embryogenesis remain unexplained. As more novel genes and their functions are discovered, existing mechanisms will be refined and tenable explanations will be made. With these limitations, two specific clinical entities that have been relatively well studied, holoprosencephaly and neuronal migration defects, are discussed in more detail to illustrate the complexity of regulatory mechanisms that govern well-defined stages of CNS development.
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Affiliation(s)
- Felicitas L Lacbawan
- Department of Medical Genetics, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010, USA
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82
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Hurd MW, Cahill GM. Entraining signals initiate behavioral circadian rhythmicity in larval zebrafish. J Biol Rhythms 2002; 17:307-14. [PMID: 12164247 DOI: 10.1177/074873002129002618] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The authors show that a circadian clock that regulates locomotor activity in larval zebrafish develops gradually over the first 4 days of life and that exposure to entraining signals late in embryonic development is necessary for initiation of robust behavioral rhythmicity. When zebrafish larvae were transferred from a light-dark (LD) cycle to constant darkness (DD) on the third or fourth day postfertilization, the locomotor activity of almost all fish was rhythmic on days 5 to 9 postfertilization, with peak activity occurring during the subjective day. Rhythm amplitude was higher after four LD cycles than after three LD cycles. When embryos were transferred from LD to DD on the second day postfertilization, only about half of the animals later displayed statistically significant activity rhythms. These rhythms were noisier and of lower amplitude, but phased normally. When zebrafish were raised in DD beginning at 14 h postfertilization, only 22% of them expressed significant circadian rhythmicity as larvae. These rhythms were of low amplitude and phase-locked to the time of handling on the third day rather than to the maternal LD cycle. These results show that behavioral rhythmicity in zebrafish is regulated by a pacemaking system that is sensitive to light by the second day of embryogenesis but continues to develop into the fourth day. This pacemaking system requires environmental signals to initiate or synchronize circadian rhythmicity.
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Affiliation(s)
- Mark W Hurd
- Department of Psychology, College of Charleston, SC 29424, USA
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83
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Houart C, Caneparo L, Heisenberg C, Barth K, Take-Uchi M, Wilson S. Establishment of the telencephalon during gastrulation by local antagonism of Wnt signaling. Neuron 2002; 35:255-65. [PMID: 12160744 DOI: 10.1016/s0896-6273(02)00751-1] [Citation(s) in RCA: 231] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Cells at the anterior boundary of the neural plate (ANB) can induce telencephalic gene expression when transplanted to more posterior regions. Here, we identify a secreted Frizzled-related Wnt antagonist, Tlc, that is expressed in ANB cells and can cell nonautonomously promote telencephalic gene expression in a concentration-dependent manner. Moreover, abrogation of Tlc function compromises telencephalic development. We also identify Wnt8b as a locally acting modulator of regional fate in the anterior neural plate and a likely target for antagonism by Tlc. Finally, we show that tlc expression is regulated by signals that establish early antero-posterior and dorso-ventral ectodermal pattern. From these studies, we propose that local antagonism of Wnt activity within the anterior ectoderm is required to establish the telencephalon.
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Affiliation(s)
- Corinne Houart
- MRC Centre for Developmental Neurobiology, New Hunt's House, King's College London, SE1 9RT, London, United Kingdom.
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84
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Devos N, Deflorian G, Biemar F, Bortolussi M, Martial JA, Peers B, Argenton F. Differential expression of two somatostatin genes during zebrafish embryonic development. Mech Dev 2002; 115:133-7. [PMID: 12049777 DOI: 10.1016/s0925-4773(02)00082-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have identified the cDNAs of two new zebrafish preprosomatostatins, PPSS1 and PPSS3, in addition to the previously cloned PPSS2 (Argenton et al., 1999). PPSS1 is the orthologue of mammalian PPSSs, with a conserved C-terminal SS-14 sequence, PPSS2 is a divergent SS precursor and PPSS3 is a cortistatin-like prohormone. Using whole-mount in situ hybridisation, we have analysed the expression of PPSS1 and PPSS2 in zebrafish embryos up to 5 days post fertilisation. PPSS1 was expressed in the developing pancreas and central nervous system (CNS), whereas PPSS2 expression was exclusively pancreatic. In the CNS, PPSS1 was detected in several areas, in particular in the vagal motor nucleus and in cells that pioneer the tract of the postoptic commissure. PPSS1 was also expressed transiently in the telencephalon and spinal motor neurons. In all areas but the telencephalon PPSS1 was coexpressed with islet-1.
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Affiliation(s)
- Nathalie Devos
- Laboratoire de Biologie Moléculaire et de Génie Génétique, Institut de Chimie, Bâtiment B6, Université de Liège, Belgium
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85
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Tada M, Concha ML, Heisenberg CP. Non-canonical Wnt signalling and regulation of gastrulation movements. Semin Cell Dev Biol 2002; 13:251-60. [PMID: 12137734 DOI: 10.1016/s1084-9521(02)00052-6] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Members of the Wnt family have been implicated in a variety of developmental processes including axis formation, patterning of the central nervous system and tissue morphogenesis. Recent studies have shown that a Wnt signalling pathway similar to that involved in the establishment of planar cell polarity in Drosophila regulates convergent extension movements during zebrafish and Xenopus gastrulation. This finding provides a good starting point to dissect the complex cell biology and genetic regulation of vertebrate gastrulation movements.
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Affiliation(s)
- Masazumi Tada
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.
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86
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Pando MP, Sassone-Corsi P. Unraveling the mechanisms of the vertebrate circadian clock: zebrafish may light the way. Bioessays 2002; 24:419-26. [PMID: 12001265 DOI: 10.1002/bies.10091] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Most organisms display oscillations of approximately 24 hours in their physiology. In higher organisms, these circadian oscillations in biochemical and physiological processes ultimately control complex behavioral rhythms that allow an organism to thrive in its natural habitat. Daily and seasonal light cycles are mainly responsible for keeping the circadian system properly aligned with the environment. The molecular mechanisms responsible for the control of the circadian clock have been explored in a number of systems. Interestingly, the circadian oscillations that are responsive to environmental stimuli are present very early during development. This review focuses on the advantages of using the zebrafish to study the development of the vertebrate circadian system and light-dependent signaling to the clock.
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Affiliation(s)
- Matthew P Pando
- Institute de Génétique et de Biologie Moléculaire et Cellulaire, CNRS-INSERM-ULP, Strasbourg, France
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87
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Yamashita S, Miyagi C, Carmany-Rampey A, Shimizu T, Fujii R, Schier AF, Hirano T. Stat3 Controls Cell Movements during Zebrafish Gastrulation. Dev Cell 2002; 2:363-75. [PMID: 11879641 DOI: 10.1016/s1534-5807(02)00126-0] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Vertebrate axis formation requires both the correct specification of cell fates and the coordination of gastrulation movements. We report that the zebrafish signal transducer and activator of transcription 3 (Stat3) is activated on the dorsal side by the maternal Wnt/beta-catenin pathway. Zebrafish embryos lacking Stat3 activity display abnormal cell movements during gastrulation, resulting in a mispositioned head and a shortened anterior-posterior axis, but show no defects in early cell fate specification. Time course analysis, cell tracing, and transplantation experiments revealed that Stat3 activity is required cell autonomously for the anterior migration of dorsal mesendodermal cells and non-cell autonomously for the convergence of neighboring paraxial cells. These results reveal a role for Stat3 in controlling cell movements during gastrulation.
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Affiliation(s)
- Susumu Yamashita
- Department of Molecular Oncology (C-7), Osaka University Graduate School of Medicine, 2-2 Yamada-oka, 565-0871, Suita Osaka, Japan
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88
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Vihtelic TS, Hyde DR. Zebrafish mutagenesis yields eye morphological mutants with retinal and lens defects. Vision Res 2002; 42:535-40. [PMID: 11853770 DOI: 10.1016/s0042-6989(01)00261-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A chemical mutagenesis to identify zebrafish eye morphological mutants was performed by screening F(3) larvae at 5 and 7 days post-fertilization (dpf) for changes in eye or pupil size. Based on histological analysis, four different phenotypic classes were obtained. The two Class I and three Class II mutants are all characterized by small eyes and exhibit defects in early retinal development or unregulated cell death, respectively. The single Class III mutant has reduced ocular pigmentation. The three Class IV mutants display defects in the ocular lens, including one mutant line with normal sized eyes and pupils that develops lens opacity at 7 dpf.
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Affiliation(s)
- Thomas S Vihtelic
- Department of Biological Sciences, Galvin Life Sciences Center, University of Notre Dame, IN 46556, USA.
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89
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Abstract
This review provides a synthesis that combines data from classical experimentation and recent advances in our understanding of early eye development. Emphasis is placed on the events that underlie and direct neural retina formation and lens induction. Understanding these events represents a longstanding problem in developmental biology. Early interest can be attributed to the curiosity generated by the relatively frequent occurrence of disorders such as cyclopia and anophthalmia, in which dramatic changes in eye development are readily observed. However, it was the advent of experimental embryology at the turn of the century that transformed curiosity into active investigation. Pioneered by investigators such as Spemann and Adelmann, these embryological manipulations have left a profound legacy. Questions about early eye development first addressed using tissue manipulations remain topical as we try to understand the molecular basis of this process.
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Affiliation(s)
- R L Chow
- Program in Developmental Biology, The Research Institute, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada.
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90
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van de Water S, van de Wetering M, Joore J, Esseling J, Bink R, Clevers H, Zivkovic D. Ectopic Wnt signal determines the eyeless phenotype of zebrafishmasterblindmutant. Development 2001; 128:3877-88. [PMID: 11641213 DOI: 10.1242/dev.128.20.3877] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
masterblind (mbl) is a zebrafish mutation characterised by the absence or reduction in size of the telencephalon, optic vesicles and olfactory placodes. We show that inhibition of Gsk3β in zebrafish embryos either by overexpression of dominant negative dn gsk3β mRNA or by lithium treatment after the midblastula transition phenocopies mbl. The loss of anterior neural tissue in mbl and lithium-treated embryos is preceded by posteriorization of presumptive anterior neuroectoderm during gastrulation, which is evident from the anterior shift of marker genes Otx2 and Wnt1. Heterozygous mbl embryos showed increased sensitivity to inhibition of GSK3β by lithium or dn Xgsk3β that led to the loss of eyes. Overexpression of gsk3β mRNA rescued eyes and the wild-type fgf8 expression of homozygous mbl embryos. emx1 that delineates the telencephalon is expanded and shifted ventroanteriorly in mbl embryos. In contrast to fgf8, the emx1 expression domain was not restored upon overexpression of gsk3β mRNA. These experiments place mbl as an antagonist of the Wnt pathway in parallel or upstream of the complex consisting of Axin, APC and Gsk3β that binds and phosphorylates β-catenin, thereby destabilising it. mbl maps on LG 3 close to a candidate gene axin1. In mbl we detected a point mutation in the conserved minimal Gsk3β-binding domain of axin1 leading to a leucine to glutamine substitution at position 399. Overexpression of wild-type axin1 mRNA rescued mbl completely, demonstrating that mutant axin1 is responsible for the mutant phenotype. Overexpression of mutant L399Q axin1 in wild-type embryos resulted in a dose-dependent dominant negative activity as demonstrated by the loss of telencephalon and eyes. We suggest that the function of Axin1/Mbl protein is to antagonise the Wnt signal and in doing so to establish and maintain the most anterior CNS. Our findings provide new insights into the mechanisms by which the Wnt pathway generates anteroposterior polarity of the neural plate.
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Affiliation(s)
- S van de Water
- Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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91
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Sumanas S, Kim HJ, Hermanson S, Ekker SC. Zebrafish frizzled-2 morphant displays defects in body axis elongation. Genesis 2001; 30:114-8. [PMID: 11477686 DOI: 10.1002/gene.1043] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- S Sumanas
- Department of Genetics, Cell Biology and Development, University of Minnesota Arnold and Mabel Beckman Center for Transposon Research, Minneapolis, Minnesota, USA
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92
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Heisenberg CP, Houart C, Take-Uchi M, Rauch GJ, Young N, Coutinho P, Masai I, Caneparo L, Concha ML, Geisler R, Dale TC, Wilson SW, Stemple DL. A mutation in the Gsk3-binding domain of zebrafish Masterblind/Axin1 leads to a fate transformation of telencephalon and eyes to diencephalon. Genes Dev 2001; 15:1427-34. [PMID: 11390362 PMCID: PMC312705 DOI: 10.1101/gad.194301] [Citation(s) in RCA: 214] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Zebrafish embryos homozygous for the masterblind (mbl) mutation exhibit a striking phenotype in which the eyes and telencephalon are reduced or absent and diencephalic fates expand to the front of the brain. Here we show that mbl(-/-) embryos carry an amino-acid change at a conserved site in the Wnt pathway scaffolding protein, Axin1. The amino-acid substitution present in the mbl allele abolishes the binding of Axin to Gsk3 and affects Tcf-dependent transcription. Therefore, Gsk3 activity may be decreased in mbl(-/-) embryos and in support of this possibility, overexpression of either wild-type Axin1 or Gsk3beta can restore eye and telencephalic fates to mbl(-/-) embryos. Our data reveal a crucial role for Axin1-dependent inhibition of the Wnt pathway in the early regional subdivision of the anterior neural plate into telencephalic, diencephalic, and eye-forming territories.
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Affiliation(s)
- C P Heisenberg
- Department of Anatomy and Developmental Biology, University College London, London WC1E 6BT, UK
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93
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Affiliation(s)
- J Malicki
- Dept. of Ophthalmology, Harvard Medical School/MEEI, Boston, Massachusetts 02114, USA
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94
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Biemar F, Argenton F, Schmidtke R, Epperlein S, Peers B, Driever W. Pancreas development in zebrafish: early dispersed appearance of endocrine hormone expressing cells and their convergence to form the definitive islet. Dev Biol 2001; 230:189-203. [PMID: 11161572 DOI: 10.1006/dbio.2000.0103] [Citation(s) in RCA: 187] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To begin to understand pancreas development and the control of endocrine lineage formation in zebrafish, we have examined the expression pattern of several genes shown to act in vertebrate pancreatic development: pdx-1, insulin (W. M. Milewski et al., 1998, Endocrinology 139, 1440-1449), glucagon, somatostatin (F. Argenton et al., 1999, Mech. Dev. 87, 217-221), islet-1 (Korzh et al., 1993, Development 118, 417-425), nkx2.2 (Barth and Wilson, 1995, Development 121, 1755-1768), and pax6.2 (Nornes et al., 1998, Mech. Dev. 77, 185-196). To determine the spatial relationship between the exocrine and the endocrine compartments, we have cloned the zebrafish trypsin gene, a digestive enzyme expressed in differentiated pancreatic exocrine cells. We found expression of all these genes in the developing pancreas throughout organogenesis. Endocrine cells first appear in a scattered fashion in two bilateral rows close to the midline during mid-somitogenesis and converge during late-somitogenesis to form a single islet dorsal to the nascent duodenum. We have examined development of the endocrine lineage in a number of previously described zebrafish mutations. Deletion of chordamesoderm in floating head (Xnot homolog) mutants reduces islet formation to small remnants, but does not delete the pancreas, indicating that notochord is involved in proper pancreas development, but not required for differentiation of pancreatic cell fates. In the absence of knypek gene function, which is involved in convergence movements, the bilateral endocrine primordia do not merge. Presence of trunk paraxial mesoderm also appears to be instrumental for convergence since the bilateral endocrine primordia do not merge in spadetail mutants. We discuss our findings on zebrafish pancreatogenesis in the light of evolution of the pancreas in chordates.
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Affiliation(s)
- F Biemar
- Institut für Biologie I, Abt. Entwicklungsbiologie, Universität Freiburg, Hauptstrasse 1, Freiburg, D-79104, Germany
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95
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Affiliation(s)
- S W Wilson
- Department of Anatomy and Developmental, Biology, University College London, Gower Street, WC1E 6BT, London, United Kingdom.
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96
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Malicki J. Harnessing the power of forward genetics--analysis of neuronal diversity and patterning in the zebrafish retina. Trends Neurosci 2000; 23:531-41. [PMID: 11074262 DOI: 10.1016/s0166-2236(00)01655-6] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The seven major cell classes of the vertebrate retina are organized with remarkable precision into distinct layers. The appearance of this architecture during embryogenesis raises two questions of general importance. How do individual cell classes acquire their specialized structures and functions if they all originate from a morphologically uniform cell population? What mechanisms are responsible for the formation of such a complex and exact pattern? Recent advances present an opportunity to apply the tools of forward genetic analysis to identify mutations that affect these mechanisms in zebrafish. Molecular characterization will follow, providing insight into the basis of neuronal patterning in the vertebrate CNS.
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Affiliation(s)
- J Malicki
- Dept of Ophthalmology, Harvard Medical School, Boston, MA 02134, USA. www.howelaboratory.harvard.edu/malicki/htm
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97
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Affiliation(s)
- D G McEwen
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, 27599-3280, USA.
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98
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Heisenberg CP, Tada M, Rauch GJ, Saúde L, Concha ML, Geisler R, Stemple DL, Smith JC, Wilson SW. Silberblick/Wnt11 mediates convergent extension movements during zebrafish gastrulation. Nature 2000; 405:76-81. [PMID: 10811221 DOI: 10.1038/35011068] [Citation(s) in RCA: 796] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Vertebrate gastrulation involves the specification and coordinated movement of large populations of cells that give rise to the ectodermal, mesodermal and endodermal germ layers. Although many of the genes involved in the specification of cell identity during this process have been identified, little is known of the genes that coordinate cell movement. Here we show that the zebrafish silberblick (slb) locus encodes Wnt11 and that Slb/Wnt11 activity is required for cells to undergo correct convergent extension movements during gastrulation. In the absence of Slb/Wnt11 function, abnormal extension of axial tissue results in cyclopia and other midline defects in the head. The requirement for Slb/Wnt11 is cell non-autonomous, and our results indicate that the correct extension of axial tissue is at least partly dependent on medio-lateral cell intercalation in paraxial tissue. We also show that the slb phenotype is rescued by a truncated form of Dishevelled that does not signal through the canonical Wnt pathway, suggesting that, as in flies, Wnt signalling might mediate morphogenetic events through a divergent signal transduction cascade. Our results provide genetic and experimental evidence that Wnt activity in lateral tissues has a crucial role in driving the convergent extension movements underlying vertebrate gastrulation.
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Affiliation(s)
- C P Heisenberg
- Department of Anatomy and Developmental Biology, University College, London, UK.
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99
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Winkler S, Loosli F, Henrich T, Wakamatsu Y, Wittbrodt J. The conditional medaka mutation eyeless uncouples patterning and morphogenesis of the eye. Development 2000; 127:1911-9. [PMID: 10751179 DOI: 10.1242/dev.127.9.1911] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In early vertebrate eye development, the retinal anlage is specified in the anterior neuroectoderm. During neurulation, the optic vesicles evaginate from the lateral wall of the prosencephalon. Here we describe the temperature-sensitive mutation eyeless in the Japanese medakafish. Marker gene analysis indicates that, whereas, specification of two retinal primordia and proximodistal patterning takes place in the mutant embryo, optic vesicle evagination does not occur and subsequent differentiation of the retinal primordia is not observed. The mutation eyeless thus uncouples patterning and morphogenesis at early steps of retinal development. Temperature-shift experiments indicate a requirement for eyeless activity prior to optic vesicle evagination. Cell transplantation shows that eyeless acts cell autonomously.
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Affiliation(s)
- S Winkler
- Developmental Biology Programme, European Molecular Biology Laboratory, Meyerhofstrasse 1, PO Box 10.2209, Germany.
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100
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Affiliation(s)
- G Heinrich
- VA Northern California Health Care System and EBIRE, 150 Muir Road, Martinez, CA 94553, USA.
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