SEARCH · PubMed Health

Results for “zebrafish”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources

PubMed2002

Atlas of the developing inner ear in zebrafish.

This report provides a description of the normal developing inner ear of the zebrafish, Danio rerio, with special focus on the pars inferior. Zebrafish specimens, ranging in age from 3 to 30 days postfertilization (dpf), were processed for standard histologic sections or with a paint-fill method to show three-dimensional morphogenesis of the membranous labyrinth. Adult zebrafish (age 2 years) were also processed for inner ear paint-fills. Although development of the semicircular canals occurs rapidly (by 3 dpf), the pars inferior develops more gradually during days 5-20 postfertilization. A rudimentary endolymphatic duct emerges by 8 dpf. Differentiated hair cells of the lagenar macula are evident by 15 dpf, in a chamber located lateral and posterior to the saccule. By 20 dpf, the saccule itself is separated from the utricle, but remains connected by means of the utriculosaccular foramen. The maculae neglectae, each with differentiated hair cells, lie on the floor of the utricle near this foramen. A medial connection between the sacculi of right and left ears, the transverse canal, is also complete by 20 dpf. A ridge of mesenchyme, previously undescribed, bisects the saccule in zebrafish fry at 20-30 dpf. The images in the paint-fill atlas should provide a baseline for future studies of mutant zebrafish ears.

Animals↗

PubMed2003

Zebrafish pronephros: a model for understanding cystic kidney disease.

The embryonic kidney of the zebrafish is the pronephros. The ease of genetic analysis and experimentation in zebrafish, coupled with the simplicity of the pronephros, make the zebrafish an ideal model system for studying kidney development and function. Several mutations have been isolated in zebrafish genetic screens that result in cyst formation in the pronephros. Cloning and characterization of these mutations will provide insight into kidney development but may also provide understanding of the molecular basis of cystic kidney diseases. In this review, we focus on the zebrafish as a model for understanding cystic kidney disease and the links between cystic kidney disease and left-right patterning.

Animals↗

PubMed2003

Skin-specific expression of ictacalcin, a homolog of the S100 genes, during zebrafish embryogenesis.

Full-length cDNA coding for the ictacalcin gene, a homolog of the S100 genes, was isolated in zebrafish and mapped on linkage group 16 using the LN54 radiation hybrid panel. The homology and phylogenetic analyses, based on the deduced amino acid sequences, showed the orthologous relationship of ictacalcin genes between zebrafish and other fish species. However, ictacalcin genes constitute an out-group with respect to other members of the S100 gene family. This result supports the findings that fish ictacalcin genes are new members of the S100 gene family and may have evolved after the divergence of teleosts and tetrapods. The zebrafish ictacalcin gene was zygotically transcribed from 12 hours postfertilization onward and was stably expressed throughout adulthood. During zebrafish embryogenesis, the ictacalcin gene was specifically expressed in striated epidermal cells covering the entire embryo. The ictacalcin staining in keratinocytes of striated epithelia was absent in the cytoplasm surrounding the nuclei, but it was highly concentrated in the peripheral margin. Tissues enriched with epithelia folds, such as olfactory epithelium, hatching gland, pectoral fin buds, urogenital opening, and pharynx, showed a robust ictacalcin expression. The strikingly heavy staining of ictacalcin in the pharyngeal region provides us with an early marker to follow the pharynx formation in zebrafish embryos.

Amino Acid Sequence↗

PubMed2001

Cloning and expression of three zebrafish roundabout homologs suggest roles in axon guidance and cell migration.

We report the cloning and expression patterns of three novel zebrafish Roundabout homologs. The Roundabout (robo) gene encodes a transmembrane receptor that is essential for axon guidance in Drosophila and Robo family members have been implicated in cell migration. Analysis of extracellular domains and conserved cytoplasmic motifs shows that zebrafish Robo1 and Robo2 are orthologs of mammalian Robo1 and Robo2, respectively, while zebrafish Robo3 is likely to be an ortholog of mouse Rig-1. The three zebrafish robos are expressed in distinct but overlapping patterns during embryogenesis. They are highly expressed in the developing nervous system, including the olfactory system, visual system, hindbrain, cranial ganglia, spinal cord, and posterior lateral line primordium. They are also expressed in several nonneuronal tissues, including somites and fin buds. The timing and patterns of expression suggest roles for zebrafish robos in axon guidance and cell migration. Wiley-Liss, Inc.

Amino Acid Sequence↗

PubMed2001

Morphogenetic domains in the yolk syncytial layer of axiating zebrafish embryos.

The yolk syncytial layer (YSL) of the teleostean yolk cell is known to play important roles in the induction of cellular mesendoderm, as well as the patterning of dorsal tissues. To determine how this extraembryonic endodermal compartment is subdivided and morphologically transformed during early development, we have examined collective movements of vitally stained YSL nuclei in axiating zebrafish embryos by using four-dimensional confocal microscopy. During blastulation, gastrulation, and early segmentation, zebrafish YSL nuclei display several highly patterned movements, which are organized into spatially distinct morphogenetic domains along the anterior-posterior and dorsal-ventral axes. During the late blastula period, with the onset of epiboly, nuclei throughout the YSL initiate longitudinal movements that are directed along the animal-vegetal axis. As epiboly progresses, nuclei progressively recede from the advancing margin of the epibolic YSL. However, a small group of nuclei is retained at the YSL margin to form a constricting blastoporal ring. During mid-gastrulation, YSL nuclei undergo convergent-extension behavior toward the dorsal midline, with a subset of nuclei forming an axial domain that underlies the notochord. These highly patterned movements of YSL nuclei share remarkable similarities to the morphogenetic movements of deep cells in the overlying zebrafish blastoderm. The macroscopic shape changes of the zebrafish yolk cell, as well as the morphogenetic movements of its YSL nuclei, are homologous to several morphogenetic behaviors that are regionally expressed within the vegetal endodermal cell mass of gastrulating Xenopus embryos. In contrast to the cellular endoderm of Xenopus, the dynamics of zebrafish YSL show that a syncytial endodermal germ layer can express a temporal sequence of morphogenetic domains without undergoing progressive steps of cell fate restriction.

Animals↗

PubMed2004

Evolution and expression of D2 and D3 dopamine receptor genes in zebrafish.

We mined the zebrafish genomic sequence database and identified contigs containing segments of several dopamine receptor genes. By using a polymerase chain reaction amplification strategy, we generated full-length cDNAs encoding a single dopamine D3 receptor and three distinct D2 receptor subtypes. Zebrafish dopamine receptor genes were mapped by using the T51 radiation hybrid panel. The D3 receptor gene (drd3) mapped to linkage group (LG) 24. The three D2 receptor genes were localized to LG 15 (drd2a), LG 16, (drd2b), and LG 5 (drd2c). With the exception of the drd2b gene, each of these map positions was syntenic with regions of human chromosomes containing orthologs of the zebrafish dopamine receptor genes. Whole-mount in situ hybridization was used to investigate expression of the D2 and D3 receptor genes. Expression of the drd3 gene was first detected at mid-somitogenesis and was particularly prominent in somites. Thereafter, the drd3 gene was expressed diffusely throughout the brain and spinal cord. The three D2 receptor genes were expressed throughout the central nervous system (CNS) in distinct but overlapping patterns. In early embryos, the drd2a gene was expressed exclusively in the epiphysis, whereas the drd2c gene was localized to the notochord. After 24 hpf, the drd2a, drd2b, and drd2c genes were differentially expressed throughout the CNS. The identification of dopamine receptor genes in zebrafish should allow us to use the power of zebrafish genetics to analyze the functional properties of this important class of neurotransmitter receptors.

Amino Acid Sequence↗

PubMed2004

Functional conserved elements mediate intestinal-type fatty acid binding protein (I-FABP) expression in the gut epithelia of zebrafish larvae.

Intestinal-type fatty acid binding protein (I-FABP) plays an important role in the intracellular binding and trafficking of long chain fatty acids in the intestine. The aim of this study, therefore, was to elucidate the regulation and spatiotemporal expression of the I-FABP gene during zebrafish larval development. We performed in vivo reporter-gene analysis in zebrafish by using a transient and transgenic approach. Green fluorescent protein-reporter analyses revealed that the proximal 192-bp region of the I-FABP promoter is sufficient to direct intestine-specific expression during zebrafish larval development. Functional dissection of a 41-bp region within this 192-bp promoter revealed that one C/EBP and two GATA-like binding sites, along with a novel 15-bp element within it are required for I-FABP gene expression in vivo. In addition, the six consensus sites (CCACATCAGCATGAA) in the 15-bp element are critical for I-FABP gene regulation in the zebrafish gut epithelia. Comparison analyses of the orthologous 15-bp element from mammalian I-FABP genes suggests that these mammalian elements are functionally equivalent to the zebrafish 15 element. These results provide the first in vivo evidence that these binding sites (C/EBP and GATA) and the novel 15-bp element contribute to intestine-specific gene expression and that they are functionally conserved across vertebrate evolution.

Animals↗

PubMed2004

Expression of VE-cadherin in zebrafish embryos: a new tool to evaluate vascular development.

We have identified the zebrafish homologue of VE-cadherin and documented its expression in the developing vascular system. The zebrafish VE-cadherin gene is specifically expressed in the vascular endothelial cell lineage beginning with the differentiation and migration of angioblasts and persists throughout vasculogenesis, angiogenesis, and endocardium development. Staining zebrafish embryos by whole-mount in situ hybridization with the VE-cadherin probe provides a method to screen embryos for vascular defects. To illustrate this utility, we used VE-cadherin expression to demonstrate a conservation of vascular endothelial growth factor-A (VEGF-A) function. The morpholino antisense oligonucleotide knockdown of VEGF-A function in zebrafish embryos results in a loss of angiogenic blood vessels, as indicated by the lack of VE-cadherin expression in the intersegmental vasculature. This loss can be restored in embryos supplemented with either zebrafish or human VEGF-A, the latter indicating that genes crucial to angiogenesis have highly conserved functional activities in vertebrates.

Amino Acid Sequence↗

PubMed2005

Conditional expression of a myocardium-specific transgene in zebrafish transgenic lines.

To develop the first heart-specific tetracycline (Tet)-On system in zebrafish, we constructed plasmids in which the cardiac myosin light chain 2 promoter of zebrafish was used to drive the reverse Tet-controlled transactivator (rtTA) and the green fluorescent protein (GFP) reporter gene was preceded by an rtTA-responsive element. In the zebrafish fibroblast cell-line, rtTA-M2, one of rtTA's derivatives, demonstrated the highest increase in luciferase activity upon doxycycline (Dox) induction. We then generated two germ lines of transgenic zebrafish: line T03 was derived from microinjection of a plasmid containing rtTA-M2 and a plasmid containing a responsive reporter gene, whereas line T21 was derived from microinjection of a single dual plasmid. Results showed that line T21 was superior to line T03 in terms of greater GFP intensity after induction and with of minimal leakiness before induction. The photographic images of induced GFP in the heart of F2 larvae showed that the fluorescent level of GFP was dose-responsive. The level of GFP expressed in the F3 3 days postfertilization larvae that were treated with Dox for 1 hr decreased gradually after the withdrawal of the inducer; and the fluorescent signal disappeared after 5 days. The GFP induction and reduction were also tightly controlled by Dox in the F3 adult fish from line T21. This Tet-On system developed in zebrafish shows much promise for the study of the gene function in a specific tissue at the later developmental stage.

Animals↗

PubMed2005

Transposon tools and methods in zebrafish.

Zebrafish is an excellent model animal to study vertebrate development by genetic approaches. Hundreds of mutations affecting various processes of development have been isolated by chemical mutagenesis and insertional mutagenesis using a pseudotyped retrovirus. However, useful transposon tools and methods had not been available in zebrafish. This is mainly because no active transposable element has been found from the zebrafish genome. Recently, efficient transgenesis, gene trap, and enhancer trap methods have been developed in zebrafish by using the Tol2 and the Sleeping Beauty transposon systems. These methods should increase the usefulness of zebrafish as a model vertebrate and facilitate the study of developmental biology, genetics, and genomics.

Animals↗

PubMed2007

The utility of zebrafish for studies of the comparative biology of motor systems.

Although zebrafish are best known as a model for studies of development, there is now a growing role for the model in studies of the functional organization of the nervous system, including studies of a variety of sensory systems, central processing, and motor output. The zebrafish has much to offer for such work because of the unique combination of genetics, optical methods, and physiology it allows. Here I illustrate, using three examples, the broad range of avenues along which zebrafish can inform us about motor systems. The examples include efforts to understand the functional organization and evolution of spinal interneurons, the role of mutants in informing us about motor dysfunction and human disease, and the ability to use the special features of zebrafish to explore strategies to restore function after injury. The most important aspects of these studies are evident only when they are placed in a comparative context, so they serve to highlight the power of zebrafish in studies of the comparative biology of motor control.

Animals↗

PubMed2003

cDNA nucleotide sequence coding for stearoyl-CoA desaturase and its expression in the zebrafish (Danio rerio) embryo.

A cDNA sequence of stearoyl-CoA desaturase (SCD) was determined from zebrafish (Danio rerio) and compared to the corresponding genes in several teleosts. Zebrafish SCD cDNA has a size of 1,061 bp, encodes a polypeptide of 325 amino acids, and shares 88, 85, 84, and 83% similarities with tilapia (Oreochromis mossambicus), grass carp (Ctenopharyngodon idella), common carp (Cyprinus carpio), and milkfish (Chanos chanos), respectively. This 1,061 bp sequence specifies a protein that, in common with other fatty acid desaturases, contains three histidine boxes, believed to be involved in catalysis. These observations suggested that SCD genes are highly conserved. In addition, an oligonucleotide probe complementary to zebrafish SCD mRNA was hybridized to mRNA of approximately 396 bases with Northern blot analysis. The Northern blot and RT-PCR analyses showed that the SCD mRNA was expressed predominantly in the liver, intestine, gill, and muscle, while a lower level was found in the brain. Furthermore, we utilized whole-mount in situ hybridization and real-time quantitative RT-PCR to identify expression of the zebrafish SCD gene at five different stages of development. This revealed that very high levels of transcripts were found in zebrafish at all stages during embryogenesis and early development.

Amino Acid Sequence↗

PubMed2003

Synaptic plasticity and functionality at the cone terminal of the developing zebrafish retina.

Previous studies have analyzed photoreceptor development, some inner retina cell types, and specific neurotransmitters in the zebrafish retina. However, only minor attention has been paid to the morphology of the synaptic connection between photoreceptors and second order neurons even though it represents the transition from the light sensitive receptor to the neuronal network of the visual system. Here, we describe the appearance and differentiation of pre- and postsynaptic elements at cone synapses in the developing zebrafish retina together with the maturation of the directly connecting second order neurons and a dopaminergic third order feedback-neuron from the inner retina. Zebrafish larvae were examined at developmental stages from 2 to 7dpf (days postfertilization) and in the adult. Synaptic maturation at the photoreceptor terminals was examined with antibodies against synapse associated proteins. The appearance of synaptic plasticity at the so-called spinule-type synapses between cones and horizontal cells was assessed by electron microscopy, and the maturation of photoreceptor downstream connection was identified by immunocytochemistry for GluR4 (AMPA-type glutamate receptor subunit), protein kinase beta(1) (mixed rod-cone bipolar cells), and tyrosine hydroxylase (dopaminergic interplexiform cells). We found that developing zebrafish retinas possess first synaptic structures at the cone terminal as early as 3.5dpf. Morphological maturation of these synapses at 3.5-4dpf, together with the presence of synapse associated proteins at 2.5dpf and the maturation of second order neurons by 5dpf, indicate functional synaptic connectivity and plasticity between the cones and their second order neurons already at 5dpf. However, the mere number of spinules and ribbons at 7dpf still remains below the adult values, indicating that synaptic functionality of the zebrafish retina is not entirely completed at this stage of development.

Animals↗

PubMed2000

Effects of infectious hematopoietic necrosis virus and infectious pancreatic necrosis virus infection on hematopoietic precursors of the zebrafish.

The zebrafish Danio rerio is a new model system for studying the genetics of hematopoiesis. To define naturally occurring viruses which could infect and replicate within hematopoietic precursors of the zebrafish, infectious hematopoietic necrosis virus (IHNV) and infectious pancreatic necrosis virus (IPNV) were studied. Infection of whole fish with viral supernatants demonstrated infectious replicants for both viruses, indicating that the virus host range includes the zebrafish. In other species, infection with these viruses leads to prominent hematopoietic necrosis of the head kidney, the major site of adult hematopoiesis. We detected a transient toxicity of the virus to hematopoietic precursors and terminally differentiated red cells after viral infections. The kinetics of hematopoietic defects between IHNV and IPNV infection differed; fish infected with either virus, however, recovered by 6 days postinfection. In contrast to other fish infected with the virus, hematocrit did not change appreciably during this time. These studies are the first to demonstrate IHNV and IPNV infection of the zebrafish and reveal the potential for use of such viruses for gene transfer experiments to infect zebrafish hematopoietic cells.

Animals↗

PubMed1997

Chill sensitivity and cryoprotectant permeability of dechorionated zebrafish embryos, Brachydanio rerio.

The zebrafish (Brachydanio rerio) was used as a model for basic studies of the chilling sensitivity, permeability and toxicity of cryoprotectants. In both intact and dechorionated embryos, early-stage embryos (1.25, 1.5, 1.75, and 2 h) were more susceptible (P < 0.05) to chilling injury at 0 degrees C than late-stage embryos (50, 75, and 100% epiboly and three-somite stage). Moreover, enzymatic removal of the chorion did not alter (P > 0.05) this pattern of sensitivity to chilling. Eight-hour zebrafish embryos tolerated short-term exposures to temperatures ranging from 4 to 23 degrees C for 3.5 h with no detrimental developmental effects. The permeability of dechorionated embryos to cryoprotectants was examined by measuring the kinetics of volumetric change at various developmental stages (16 cells to six somites or ca. 1.25 to 14 h postfertilization) at 28.5 degrees C. The dechorionated zebrafish embryo is composed of two complex cellular compartments (i.e., a large yolk and the developing blastoderm). From 40 to 100% epiboly, the volumes of yolk and blastoderm remained constant, ca. 82 and 18%, respectively. However, these volumes changed rapidly after epiboly. For example, at the six-somite stage, the yolk composed 61% of the total volume, whereas the blastoderm composed 39%. When three- and six-somite embryos were placed in 1.5 and 2.0 M cryoprotectants (dimethyl sulfoxide and propylene glycol), osmometric measurement of volume changes indicated no permeation of the cryoprotectants. However, some permeation was observed for six-somite embryos immersed in a 2.0 M methanol solution, but not for 3-somite embryos. For up to 30 min at room temperature, these cryoprotectant solutions were toxic to zebrafish embryos; however, 1.5 M glycerol and ethylene glycol solutions were. We conclude that the complex nature of the zebrafish embryo reduces the effectiveness and predictive value of light microscopical measurements for cryoprotectant permeability studies.

Animals↗

PubMed1999

Gastrulation in zebrafish: what mutants teach us.

A major approach to the study of development is to compare the phenotypes of normal and mutant individuals for a given genetic locus. Understanding the development of a complex metazoan therefore requires examination of many mutants. Relatively few organisms are being studied this way, and zebrafish is currently the best example of a vertebrate for which large-scale mutagenesis screens have successfully been carried out. The number of genes mutated in zebrafish that have been cloned expands rapidly, bringing new insights into a number of developmental pathways operating in vertebrates. Here, we discuss work on zebrafish mutants affecting gastrulation and patterning of the early embryo. Gastrulation is orchestrated by the dorsal organizer, which forms in a region where maternally derived beta-catenin signaling is active. Mutation in the zygotic homeobox gene bozozok disrupts the organizer genetic program and leads to severe axial deficiencies, indicating that this gene is a functional target of beta-catenin signaling. Once established, the organizer releases inhibitors of ventralizing signals, such as BMPs, and promotes dorsoanterior fates within all germ layers. In zebrafish, several mutations affecting dorsal-ventral (D/V) patterning inactivate genes functioning in the BMP pathway, stressing the central role of this pathway in the gastrula embryo. Cells derived from the organizer differentiate into several axial structures, such as notochord and prechordal mesoderm, which are thought to induce various fates in adjacent tissues, such as the floor plate, after the completion of gastrulation. Studies with mutants in nodal-related genes, in one-eyed pinhead, which is required for nodal signaling, and in the Notch pathway reveal that midline cell fate specification is, in fact, initiated during gastrulation. Furthermore, the organizer coordinates morphogenetic movements, and zebrafish mutants in T-box mesoderm-specific genes help clarify the mechanism of convergence movements required for the formation of axial and paraxial mesoderm.

Animals↗

PubMed2001

The vascular anatomy of the developing zebrafish: an atlas of embryonic and early larval development.

We have used confocal microangiography to examine and describe the vascular anatomy of the developing zebrafish, Danio rerio. This method and the profound optical clarity of zebrafish embryos make it possible to view the entire developing vasculature with unprecedented resolution. A staged series of three-dimensional images of the vascular system were collected beginning shortly after the onset of circulation at 1 day postfertilization through early- to midlarval stages at approximately 7 days postfertilization. Blood vessels in every region of the animal were imaged at each stage, and detailed "wiring patterns" were derived describing the interconnections between every major vessel. We present an overview of these data here in this paper and in an accompanying Web site "The interactive atlas of zebrafish vascular anatomy" online at (http://eclipse.nichd.nih.gov/nichd/lmg/redirect.html). We find a highly dynamic but also highly stereotypic pattern of vascular connections, with different sets of primitive embryonic vessels severing connections and rewiring in new configurations according to a reproducible plan. We also find that despite variation in the details of the vascular anatomy, the basic vascular plan of the developing zebrafish shows strong similarity to that of other vertebrates. This atlas will provide an invaluable foundation for future genetic and experimental studies of vascular development in the zebrafish.

Angiography↗

PubMed2001

Visualizing normal and defective bone development in zebrafish embryos using the fluorescent chromophore calcein.

Zebrafish have recently become a model of choice among developmental biologists. This unique model enables both modern molecular and genetic studies to be carried out to identify genes involved in a wide variety of developmental processes. The success of the genetic approach depends largely on the application of an easy and effective screening method to identify interesting mutants. In order to develop a method for visualizing skeletal structures in zebrafish embryos that would be suitable for screening skeletal mutants, we investigated the use of the fluorescent chromophore calcein, which binds specifically to calcified skeletal structures. By using this method, we followed the development of the skeletal structures in zebrafish embryos from day 1 to day 21 postfertilization, and analyzed the effect of bone morphogenetic protein-2 (BMP2) on axial skeleton development. We found the development of the calcified skeletal structure to appear in a progressive fashion from head to tail. Calcified structures in the head (i.e., the jaw) developed first, which were then followed by the axial skeleton in the trunk. Interesting to note was that there appeared to be two domains in the calcification of vertebrae within the axial skeleton. The first three vertebrae were in the first domain; the rest being in the second domain. Compared with Alcian blue staining, we found that calcein staining indeed labels calcified skeletal structures, and, moreover, it is a more sensitive and inclusive method for visualizing skeletal structures. To determine whether calcein staining could also be used to detect abnormal bone development, we ectopically expressed BMP2 in zebrafish notochord cells. We demonstrated that ectopic expression of BMP2 in notochord cells inhibited the development of the axial skeleton. Together, these results clearly demonstrated the sensitivity of calcein staining for visualizing bone structures in developing zebrafish embryos and its effectiveness for screening for mutants that have bone structure defects.

Alcian Blue↗