251
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Oxtoby E, Jowett T. Cloning of the zebrafish krox-20 gene (krx-20) and its expression during hindbrain development. Nucleic Acids Res 1993; 21:1087-95. [PMID: 8464695 PMCID: PMC309267 DOI: 10.1093/nar/21.5.1087] [Citation(s) in RCA: 620] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
To begin to examine the function of genes that control early development in the hindbrain, we have screened an embryonic zebrafish cDNA library with a murine krox-20 gene probe that contained the conserved zinc finger regions. We have isolated two overlapping cDNAs, zf187 and zf201 which are homologues of the murine krox-20 gene. The N-terminal of the longest cDNA (zf201) contains two acidic regions identical to those of the murine krox-20. This indicates that the functional organisation of these proteins is probably conserved. Northern Blot analysis identified a single transcript of 2.0 kb. Wholemount in situ hybridisation established that expression of the zebrafish gene (krx-20) first appears at 100% epiboly as a single anterior domain of the prospective neuroepithelium, followed very soon after by a second more posterior domain. The alternating pattern of expression of this gene in rhombomeres(r) r3 and r5 is apparent by 12 hr post-fertilisation, that is prior to the morphological appearance of the rhombomeres. Around 14 hr neural crest migration begins from the dorsal surface of r5, moving caudally into r6 and then ventrally towards the pharyngeal arches. Crest migration is not apparent at or after 16 hr. No neural crest migration was observed from r3. Expression of krx-20 is down regulated firstly in r3 around 26 hr and later in r5 around 30 hr.
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Affiliation(s)
- E Oxtoby
- Department of Biochemistry and Genetics, Medical School, University of Newcastle upon Tyne, UK
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252
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Involvement of fibronectin during epiboly and gastrulation in embryos of the common carp, Cyprinus carpio. ACTA ACUST UNITED AC 1993; 202:152-158. [DOI: 10.1007/bf00365305] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/1992] [Accepted: 10/28/1992] [Indexed: 10/26/2022]
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253
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Schulte-Merker S, Ho RK, Herrmann BG, Nüsslein-Volhard C. The protein product of the zebrafish homologue of the mouse T gene is expressed in nuclei of the germ ring and the notochord of the early embryo. Development 1992; 116:1021-32. [PMID: 1295726 DOI: 10.1242/dev.116.4.1021] [Citation(s) in RCA: 491] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Embryos mutant for the T gene, in mice, make insufficient mesoderm and fail to develop a notochord. We report the cloning and sequencing of the T gene in the zebrafish (Brachydanio rerio) and show the nuclear localization of the protein product. Both RNA and protein are found in cells of the germ ring, including enveloping layer cells, prior to and during gastrulation of zebrafish embryos. Nuclei of the yolk syncytial layer do not express Zf-T. High levels of expression are maintained throughout early development in the notochord, while in paraxial mesoderm cells the gene is turned off during gastrulation. Exposure of animal cap cells to activinA induces Zf-T expression, as does transplantation into the germ ring.
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Affiliation(s)
- S Schulte-Merker
- Abteilung Genetik, Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany
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254
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Differential susceptibility of early steps in carp (Cyrinus carpio) development to ?-amanitin. ACTA ACUST UNITED AC 1992; 202:61-65. [DOI: 10.1007/bf00364597] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/1992] [Accepted: 08/24/1992] [Indexed: 11/26/2022]
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255
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Goff DJ, Galvin K, Katz H, Westerfield M, Lander ES, Tabin CJ. Identification of polymorphic simple sequence repeats in the genome of the zebrafish. Genomics 1992; 14:200-2. [PMID: 1427829 DOI: 10.1016/s0888-7543(05)80309-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The zebrafish has drawn a great deal of attention as a developmental system because it offers the ability to combine excellent embryology and genetics. Here, we report that simple sequence repeats are abundant in the zebrafish genome and are highly polymorphic between two outbred lines, making them useful markers for the construction of a genetic map of this organism.
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Affiliation(s)
- D J Goff
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
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256
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Ekker M, Fritz A, Westerfield M. Identification of two families of satellite-like repetitive DNA sequences from the zebrafish (Brachydanio rerio). Genomics 1992; 13:1169-73. [PMID: 1339388 DOI: 10.1016/0888-7543(92)90033-o] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
To further our understanding of the structure and organization of the zebrafish genome, we have undertaken the analysis of highly and middle-repetitive DNA sequences. We have cloned and sequenced two families of tandemly repeated DNA fragments. The monomer units of the Type I satellite-like sequence are 186 bp long, A+T-rich (65%), and exhibit a high degree of sequence conservation. The Type I satellite-like sequence constitutes 8% of the zebrafish genome, or approximately 8 x 10(5) copies per haploid genome. Southern analysis of genomic DNA, digested with several restriction endonucleases, shows a ladder of hybridizing bands, consistent with a tandem array, and suggests longer range periodic variations in the sequence of the tandem repeats. The Type II satellite has a monomer length of 165 bp, is also A+T-rich (68%), and constitutes 0.2% of the zebrafish genome (22,000 copies per haploid genome). Southern analysis reveals a complex pattern rather than a ladder of regularly spaced hybridizing bands.
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Affiliation(s)
- M Ekker
- Institute of Neuroscience, University of Oregon, Eugene 97403
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257
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Joly JS, Maury M, Joly C, Duprey P, Boulekbache H, Condamine H. Expression of a zebrafish caudal homeobox gene correlates with the establishment of posterior cell lineages at gastrulation. Differentiation 1992; 50:75-87. [PMID: 1354191 DOI: 10.1111/j.1432-0436.1992.tb00488.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper deals with the first identification of a caudal cDNA containing a homeobox of the Drosophila caudal family in the zebrafish. A cDNA library from late gastrula stage embryos was constructed and screened with a mouse Cdx 1 homeobox probe. A 1.6 kb cDNA clone containing a homeobox related to other caudal homeoboxes was isolated and called cdx[Zf-cad1]. Analysis of the predicted 301 amino acid translation product reveals additional regions of homology outside the homeodomain with other members of the caudal family. Particularly, the cdx[Zf-cad1] putative protein shares a conserved N-terminal region with its chicken homolog CHox-cad. Transcripts are first detected just before the onset of gastrulation. At the beginning of gastrulation, a single 1.8 kb cdx[Zf-cad1] transcript is located near the blastoderm margin with a high level of expression restricted to the epiblast. At this stage, the hypoblast is clearly negative. At the end of gastrulation, cdx[Zf-cad1] is widely expressed in vegetal (i.e. prospective posterior) epiblast and hypoblast, with a somewhat weaker expression in the dorsal hypoblast. During somitogenesis, cdx[Zf-cad1] exhibits a posterior regionalization in the neurectoderm. In contrast, no expression is detected in the mesoderm of 22 h embryos (late somitogenesis). Posterior endoderm is also positive at this stage. cdx[Zf-cad1] transcripts cease to be detected about 48 h after fertilization. They are undetectable in the adult, particularly in female gonads. The pattern of cdx[Zf-cad1] expression during and after gastrulation is consistent with its possible involvement in the regionalization of the embryo at these stages.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J S Joly
- Unité de Génétique Cellulaire, Institut Pasteur, Paris, France
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258
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Lin S, Long W, Chen J, Hopkins N. Production of germ-line chimeras in zebrafish by cell transplants from genetically pigmented to albino embryos. Proc Natl Acad Sci U S A 1992; 89:4519-23. [PMID: 1584786 PMCID: PMC49114 DOI: 10.1073/pnas.89.10.4519] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
To determine whether embryonic cells transplanted from one zebrafish embryo to another can contribute to the germ line of the recipient, and to determine whether pigmentation can be used as a dominant visible marker to monitor cell transplants, we introduced cells from genetically pigmented (donor) embryos to albino recipients at midblastula stage. By 48 hr many of the resulting chimeras expressed dark pigment in their eyes and bodies, characteristics of donor but not albino embryos. By 4-6 weeks of age pigmentation was observed on the body of 23 of 70 chimeras. In contrast to fully pigmented wild-type fish, pigmentation in chimeras appeared within transverse bands running from dorsal to ventral. Pigmentation patterns differed from one fish to another and in almost every case were different on each side of a single fish. At 2-3 months of age chimeras were mated to albino fish to determine whether pigmented donor cells had contributed to the germ line. Of 28 chimeric fish that have yielded at least 50 offspring each, 5 have given rise to pigmented progeny at frequencies of 1-40%. The donor cells for some chimeras were derived from embryos that, in addition to being pigmented, were transgenic for a lacZ plasmid. Pigmented offspring of some germ-line chimeras inherited the transgene, confirming that they descended from transplanted donor cells. Our ability to make germ-line chimeras suggests that it is possible to introduce genetically engineered cells into zebrafish embryos and to identify the offspring of these cells by pigmentation at 2 days of age.
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Affiliation(s)
- S Lin
- Biology Department, Massachusetts Institute of Technology, Cambridge 02139
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259
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Bernhardt RR, Nguyen N, Kuwada JY. Growth cone guidance by floor plate cells in the spinal cord of zebrafish embryos. Neuron 1992; 8:869-82. [PMID: 1586486 DOI: 10.1016/0896-6273(92)90201-n] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The spinal cord of early zebrafish embryos contains a small number of neuronal classes whose growth cones all follow stereotyped, cell-specific pathways to their targets. Two classes of spinal neurons make cell-specific turns at or near the ventral midline of the spinal cord, which is occupied by a single row of midline floor plate cells. We tested whether these cells guide the growth cones by examining embryos missing the midline floor plate cells due either to laser ablation of the cells or to a mutation (cyc-1). In these embryos the growth cones followed both normal and aberrant pathways once near the ventral midline. This suggests that normally the midline floor plate cells do provide guidance cues, but that these cues are not obligatory.
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Affiliation(s)
- R R Bernhardt
- Department of Biology, University of Michigan, Ann Arbor 48109-1048
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260
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Affiliation(s)
- U Strähle
- ICRF Developmental Biology Unit, Department of Zoology, Oxford OX1 3PS, UK
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261
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Affiliation(s)
- J Rossant
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Canada
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262
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Affiliation(s)
- E S Weinberg
- Department of Biology, University of Pennsylvania, Philadelphia 19104
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263
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Liu ZJ, Moav B, Faras AJ, Guise KS, Kapuscinski AR, Hackett PB. Development of expression vectors for transgenic fish. Nat Biotechnol 1991; 8:1268-72. [PMID: 1366961 DOI: 10.1038/nbt1290-1268] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Genetic alteration of fish is important for aquatic biotechnology as well as for investigating molecular interactions that occur during vertebrate development. The numerous, large, transparent, and externally fertilized eggs of many fish species make them ideally suitable for genetic manipulation, especially for production of transgenic animals. Genetic engineering of fish requires suitable expression vectors. Accordingly, we developed two fish expression vectors, FV-1 and FV-2, which contain the proximal promoter and enhancer regulatory elements of the carp beta-actin gene and the polyadenylation signal from the salmon growth hormone gene. The two fish expression vectors were tested in microinjected fish eggs and in tissue cultured fish and mammalian cells. These two "all-fish" expression vectors should be useful for genetic engineering of fish and have been used with growth-enhancing genes in transgenic fish.
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Affiliation(s)
- Z J Liu
- Department of Genetics and Cell Biology, University of Minnesota, St. Paul 55108
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264
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Eisen JS, Pike SH. The spt-1 mutation alters segmental arrangement and axonal development of identified neurons in the spinal cord of the embryonic zebrafish. Neuron 1991; 6:767-76. [PMID: 2025428 DOI: 10.1016/0896-6273(91)90173-w] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We examined the arrangement and development of identified neurons in zebrafish embryos homozygous for the mutation spt-1, which acts autonomously and specifically to alter the development of precursors of trunk segmented mesoderm, resulting in muscle-deficient myotomes. We found that the mutation alters the morphology, number, and arrangement of identified motoneurons. By transplanting identified motoneurons between wild-type and mutant embryos, we found that the effect of the mutation was nonautonomous. We suggest that the segmental arrangement and proper axonal development of motoneurons may result from interactions with segmented mesoderm.
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Affiliation(s)
- J S Eisen
- Institute of Neuroscience, University of Oregon, Eugene 97403
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265
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Hatta K, Kimmel CB, Ho RK, Walker C. The cyclops mutation blocks specification of the floor plate of the zebrafish central nervous system. Nature 1991; 350:339-41. [PMID: 2008211 DOI: 10.1038/350339a0] [Citation(s) in RCA: 354] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The floor plate is a set of epithelial cells present in the ventral midline of the neural tube in vertebrates that seems to have an important role in the developmental patterning of central nervous system fibre pathways, and arrangements of specific neurons. The floor plate arises from dorsal ectodermal cells closely associated with the mesoderm that forms notochord, and it may depend on interactions from the notochord for its specification. To learn the nature of these interactions we have analysed mutations in zebrafish (Brachydanio rerio). We report here that in wild-type embryos the floor plate develops as a simply organized single cell row, but that its development fails in embryos bearing the newly discovered zygotic lethal 'cyclops' mutation, cyc-1(b16). Mosaic analysis establishes that cyc-1 blocks floor plate development autonomously and reveals the presence of homeogenetic induction between floor plate cells.
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Affiliation(s)
- K Hatta
- Institute of Neuroscience, University of Oregon, Eugene 97403
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266
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Affiliation(s)
- C B Kimmel
- Institute of Neuroscience, University of Oregon, Eugene 97403
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267
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Abstract
To learn how neural segments are structured in a simple vertebrate, we have characterized the embryonic zebrafish hindbrain with a library of monoclonal antibodies. Two regions repeat in an alternating pattern along a series of seven segments. One, the neuromere centers, contains the first basal plate neurons to develop and the first neuropil. The other region, surrounding the segment boundaries, contains the first neurons to develop in the alar plate. The projection patterns of these neurons differ: those in the segment centers have descending axons, while those in the border regions form ventral commissures. A row of glial fiber bundles forms a curtain-like structure between each center and border region. Specific features of the individual hindbrain segments in the series arise within this general framework. We suggest that a cryptic simplicity underlies the eventual complex structure that develops from this region of the CNS.
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Affiliation(s)
- B Trevarrow
- Institute of Neuroscience, University of Oregon, Eugene 97403
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268
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Sterrer S, Königstorfer A, Hoffmann W. Biosynthesis and expression of ependymin homologous sequences in zebrafish brain. Neuroscience 1990; 37:277-84. [PMID: 2243597 DOI: 10.1016/0306-4522(90)90214-o] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Ependymins are unique, brain specific glycoproteins, which are major constituents of the cerebrospinal fluid. Originally, they were discovered in goldfish and are thought to be involved in synaptic plasticity. In the present study two transcripts were characterized in Brachydanio rerio originating from a single gene possibly by alternative splicing. These transcripts differ only in the length of their 3'-non-coding-regions and the encoded protein shares 90 and 88% homology with the two corresponding goldfish proteins, respectively. In situ hybridization revealed the expression of ependymins exclusively in the leptomeninx including its invaginations but not at all in the ependymal layer surrounding the ventricles. An initial developmental profile showed that ependymins first appear before hatching, i.e. between 48 and 72 h postfertilization.
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Affiliation(s)
- S Sterrer
- Max-Planck-Institut für Psychiatrie, Abteilung Neurochemie, Martinsried, F.R.G
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