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 613 records · Page 34Linked to original sources

PubMed2005

Fog1 is required for cardiac looping in zebrafish.

To further our understanding of FOG gene function during cardiac development, we utilized zebrafish to examine FOG's role in the early steps of heart morphogenesis. We identified fragments of three fog genes in the zebrafish genomic database and isolated full-length coding sequences for each of these genes by using a combination of RT-PCR and 5'-RACE. One gene was similar to murine FOG-1 (fog1), while the remaining two were similar to murine FOG-2 (fog2a and fog2b). All Fog proteins were able to physically interact with GATA4 and function as transcriptional co-repressors. Whole-mount in situ hybridization revealed fog1 expression in the heart, the hematopoietic system, and the brain, while fog2a and fog2b expression was restricted to the brain. Injection of zebrafish embryos with a morpholino directed against fog1 resulted in embryos with a large pericardial effusion and an unlooped heart tube. This looping defect could be rescued by co-injection of mRNA encoding murine FOG-1, but not by mRNA encoding FOG-1 lacking the FOG repression motif. Taken together, these results demonstrate the importance of FOG proteins for zebrafish cardiac development and suggest a previously unappreciated role for FOG proteins in heart looping that is dependent on the FOG repression motif.

Animals↗

PubMed2006

Zebrafish cypher is important for somite formation and heart development.

Mammalian CYPHER (Oracle, KIA0613), a member of the PDZ-LIM family of proteins (Enigma/LMP-1, ENH, ZASP/Cypher, RIL, ALP, and CLP-36), has been associated with cardiac and muscular myopathies. Targeted deletion of Cypher in mice is neonatal lethal possibly caused by myopathies. To further investigate the role of cypher in development, we have cloned the zebrafish orthologue. We present here the gene, domain structure, and expression pattern of zebrafish cypher during development. Cypher was not present as a maternal mRNA and was absent during early development. Cypher mRNA was first detected at the 3-somite stage in adaxial somites, and as somites matured, cypher expression gradually enveloped the whole somite. Later, cypher expression was also found in the heart, in head and jaw musculature, and in the brain. We further identified 13 alternative spliced forms of cypher from zebrafish heart and skeletal muscle tissue, among them a very short form containing the PDZ domain but lacking the ZM (ZASP-like) motif and the LIM domains. Targeted gene knock-down experiments using cypher antisense morpholinos led to severe defects, including truncation of the embryo, deformation of somites, dilatation of the pericardium, and thinning of the ventricular wall. The phenotype could be rescued by a cypher form, which contains the PDZ domain and the ZM motif, but lacks all three LIM domains. These findings indicate that a PDZ domain protein is important for normal somite formation and in normal heart development. Treatment of zebrafish embryos with cyclopamine, which disrupts hedgehog signaling, abolished cypher expression in 9 somite and 15-somite stage embryos. Taken together, our data suggest that cypher may play a role downstream of sonic hedgehog, in a late stage of somite development, when slow muscle fibers differentiate and migrate from the adaxial cells.

Alternative Splicing↗

PubMed2005

Cloning, characterization, and heat stress-induced redistribution of a protein homologous to human hsp27 in the zebrafish Danio rerio.

Hsp27 is a small heat shock protein (shsp) regulating stress tolerance and increasingly thought to play roles in tissue homeostasis and differentiation. The zebrafish Danio rerio is an important model for the study of developmental processes, but little is known regarding shsps in this animal. Here, we report the sequence, expression, regulation, and function of a zebrafish protein (zfHsp27) homologous to human Hsp27. zfHsp27 contains three conserved phosphorylatable serines and a cysteine important for regulation of apoptosis, but it lacks much of a C-terminal tail domain and shows low homology in two putative actin interacting domains that are features of mammalian Hsp27. zfHsp27 mRNA is most abundant in adult skeletal muscle and heart and is upregulated during early embryogenesis. zfHsp27 expressed in mammalian fibroblasts was phosphorylated in response to heat stress and anisomycin, and this phosphorylation was prevented by treatment with SB202190, an inhibitor of p38 MAPK. Expression of zfHsp27 and human Hsp27 in mammalian fibroblasts promoted a similar degree of tolerance to heat stress. zfHsp27 fusion proteins entered the nucleus and associated with the cytoskeleton of heat stressed cells in vitro and in zebrafish embryos. These results reveal conservation in regulation and function of mammalian and teleost Hsp27 proteins and define zebrafish as a new model for the study of Hsp27 function.

Amino Acid Sequence↗

PubMed2006

Modern mosaic analysis in the zebrafish.

One of the most powerful tools used to gain insight into complex developmental processes is the analysis of mosaic embryos. A mosaic is defined as an organism that contains cells of more than one genotype, usually wild-type and mutant. It is the interplay between wild-type and mutant cells in the mosaic that reveals information about the normal function of the mutated gene. Mosaic analysis has been utilized extensively in Caenorhabditis elegans, Drosophila, mice, and zebrafish to elucidate when, where, and how a gene acts during development. In the zebrafish, mosaic analysis has been used to dissect a number of different developmental processes, including gastrulation movements, mesoderm and endoderm specification, neuronal patterning and migration, axon pathfinding, angiogenesis, and cardiac, retinal, and neural crest development. Mosaic analysis is a particularly effective method for understanding gene function in the zebrafish, a model organism particularly suited to forward genetic, molecular, and classical embryological approaches. These attributes, when combined with the accessibility and optical clarity of the zebrafish embryo, facilitate the real time observation of individual cell behaviors and interactions within mosaic embryos.

Animals↗

PubMed2003

The pro-opiomelanocortin gene of the zebrafish (Danio rerio).

The cDNA and the gene for pro-opiomelanocortin (POMC) in the zebrafish (Danio rerio) were isolated and analyzed. The gene consists of three exons and two short introns and has a similar overall structural organization as in Homo sapiens. Intron 1 (339 bp) divides the 5(') untranslated region from the coding region while intron 2 (1522 bp) is located between the signal peptide and the sequence encoding ACTH. Transcription starts 26 bp downstream of a TATA box and there is one polyadenylation signal in the 3(') untranslated region. The cDNA comprises of 964 bp with an open reading frame encoding a 222 amino acid hormone prepropeptide that is split into six putative hormones. Sequence comparison of zebrafish POMC to sequences of various other vertebrate species reveals four regions that are highly conserved during the evolution of vertebrates-the N-terminal region, ACTH, beta-MSH, and beta-endorphin, whereas the connecting peptides show a much higher degree of variability. Phylogenetic analysis of the POMC sequences of various vertebrate species resulted in the expected pattern of species evolution. In situ hybridization demonstrated POMC expression in a cluster of cells (corticotrophs) in the pituitary of the zebrafish as early as 23 h after fertilization. These findings will facilitate the use of the zebrafish as a model organism in the study of the physiological role of POMC-derived peptides.

Amino Acid Sequence↗

PubMed2003

PCR-based cloning of an intronless zebrafish no tail gene.

The zebrafish no tail gene (ntl) is indispensable for the formation of the notochord and tail structure. Here, we show the presence of an intronless ntl gene in zebrafish, which we designated cryptail (ctl). ctl could not be found in any zebrafish genomic resources examined and was only just cloned by a PCR-based approach that relied on its lack of introns and homology to ntl. The amplifiable region of ctl was confined to the transcribed region of ntl. ctl thus appeared to have been generated by reverse transcription of ntl mRNA, like a processed pseudogene. ctl was very polymorphic even in individual fish, but had no missense mutations. This may suggest that ctl has a physiological function in zebrafish.

Animals↗

PubMed2003

In vivo studies of liver-type fatty acid binding protein (L-FABP) gene expression in liver of transgenic zebrafish (Danio rerio).

Mammalian liver fatty acid binding protein (L-FABP) is a small cytosolic protein in various tissues including liver, small intestine and kidney and is thought to play a crucial role in intracellular fatty acid trafficking and metabolism. To better understand its tissue-specific regulation during zebrafish hepatogenesis, we isolated 5'-flanking sequences of the zebrafish L-FABP gene and used a green fluorescent protein (GFP) transgenic strategy to generate liver-specific transgenic zebrafish. The 2.8-kb 5'-flanking sequence of zebrafish L-FABP gene was sufficient to direct GFP expression in liver primordia, first observed in 2 dpf embryos and then continuously to the adult stage. This pattern of transgenic expression is consistent with the expression pattern of the endogenous gene. F2 inheritance rates of 42-51% in all the seven transgenic lines were consistent with the ratio of Mendelian segregation. Further, hhex and zXbp-1 morphants displayed a visible liver defect, which suggests that it is possible to establish an in vivo system for screening genes required for liver development.

Animals↗

PubMed2003

Characterization of zebrafish proenkephalin reveals novel opioid sequences.

Cloning and molecular characterization of an homologous gene to proenkephalin in a teleost, the zebrafish Danio rerio is presented in this paper. The new zebrafish proenkephalin (zfPENK) encodes a 249 amino acid polypeptide that displays an identity of 40% to mammalian PENKs and which contains the consensus sequences for four Met-enkephalins, one Leu-enkephalin and one Met-enkephalin-Gly-Tyr, described for the first time in teleosts. Expression studies indicate that zfPENK is selectively expressed in zebrafish brain. Our findings support the concept that PENK genes might have been highly conserved throughout evolution and that its origins might be placed more than 400 million years ago. Moreover, we present evidence that the heptapeptide Met-enkephalin-Gly-Tyr present in fish might be anterior in evolution to the heptapeptide Met-enkephalin-Arg-Phe present in tetrapods. Also another homologous sequence to proenkephalin in zebrafish genome is presented. This sequence might stand for the third exon of a possible duplicate gene of zfPENK. Our findings not only present new data in relation to the evolution of opioid peptides in vertebrates, but also we present a new heptapeptide with putative differential activity than the other peptides derived from the mammalian proenkephalins. Future research will define the functional role of this new heptapeptide in the mechanism that describes opioid activity.

Amino Acid Sequence↗

PubMed2001

Molecular cloning, genetic mapping, and expression analysis of four zebrafish c/ebp genes.

The CCAAT/enhancer binding protein family (C/EBP) are transcription factors that play integral roles in the development and function of many organ systems, including hematopoietic cells, adipose tissues, and liver. We have identified and characterized putative zebrafish orthologs of mammalian C/EBP alpha, beta, gamma, and delta using low-stringency hybridization screening and computer searches of the GenBank EST database. c/ebpa and g were mapped within 1 cM of each other on linkage group (LG) 7, syntenic with human CEBPA and G genes on chromosome 19. c/ebpb was mapped to LG8, and c/ebpd was mapped to LG24, on the same LG as a recently identified unique c/ebp in zebrafish, c/ebp1. The mapping of these genes established new syntenic relationships between LG8 and human chromosome 20, extended existing synteny between LG7 and human chromosome 19, and confirmed the synteny between LG24 and human chromosome 8. In addition, these syntenies between zebrafish and human chromosomes are also conserved in the mouse genome. To characterize the expression of these genes, RNA in situ hybridization in embryos of wild type and a hematopoietic mutant, cloche, was performed. The results showed that zebrafish c/ebpa, b, g, and d were expressed in many embryonic tissues. c/ebpa and b were expressed in a subset of hematopoietic cells in a region consistent with myeloid expression. In addition, there was expression of c/ebpa and b in the liver and c/ebpa, b, and d in regions of the gastrointestinal tract. The expression of the c/ebps may serve as important markers for analysis of myelopoiesis, hepatic development, and other developmental processes in the future.

Amino Acid Sequence↗

PubMed2000

Phenotypic effects in Xenopus and zebrafish suggest that one-eyed pinhead functions as antagonist of BMP signalling.

Zebrafish one-eyed pinhead (oep) is essential for embryonic axis and dorsal midline formation by promoting Nodal signalling and is thought to act as a permissive factor. Here we describe that oep elicits profound phenotypic effects when overexpressed in Xenopus and zebrafish. In Xenopus, wild-type oep inhibits mesoderm induction, disrupts axis formation and neuralizes animal caps. A secreted Oep dorsoanteriorizes and neuralizes Xenopus embryos indicative of BMP inhibition. In zebrafish, misexpression of smad1 in oep mutant embryos also reveals an interaction of oep with BMP signalling. Furthermore, the phenotypic effect of nodal overexpression can be rescued by coexpression of oep both in Xenopus and zebrafish. Taken together, our results support an interaction between oep and nodal but they suggest also (1) that the role of oep in Nodal signalling may include negative as well as positive regulation, (2) that oep is able to function in an active fashion and (3) that oep exerts a regulatory effect on the BMP signalling pathway.

Animals↗

PubMed2000

Conservation of sequence and expression of Xenopus and zebrafish dHAND during cardiac, branchial arch and lateral mesoderm development.

dHAND and eHAND are related basic helix-loop-helix transcription factors that are expressed in the cardiac mesoderm and in numerous neural crest-derived cell types in chick and mouse. To better understand the evolutionary development of overlapping expression and function of the HAND genes during embryogenesis, we cloned the zebrafish and Xenopus orthologues. Comparison of dHAND sequences in zebrafish, Xenopus, chick, mouse and human demonstrated conservation throughout the protein. Expression of dHAND in zebrafish was seen in the earliest precursors of all lateral mesoderm at early gastrulation stages. At neurula and later stages, dHAND expression was observed in lateral precardiac mesoderm, branchial arch neural crest derivatives and posterior lateral mesoderm. At looping heart stages, cardiac dHAND expression remained generalized with no apparent regionalization. Interestingly, no eHAND orthologue was found in zebrafish. In Xenopus, dHAND and eHAND were co-expressed in the cardiac mesoderm without the segmental restriction seen in mice. Xenopus dHAND and eHAND were also expressed bilaterally in the lateral mesoderm without any left-right asymmetry. Within the branchial arches, XdHAND was expressed in a broader domain than XeHAND, similar to their mouse counterparts. Together, these data demonstrate conservation of HAND structure and expression across species.

Amino Acid Sequence↗

PubMed2002

Cadherin-17 is required to maintain pronephric duct integrity during zebrafish development.

We have isolated a zebrafish cadherin that is orthologous to human LI-cadherin (CDH17). Zebrafish cdh17 is expressed exclusively in the pronephric ducts during embryogenesis, and in the mesonephros during larval development and adulthood. Like its mammalian ortholog, cdh17 is also expressed in liver and intestine in adult zebrafish. We show that cdh17-positive mesodermal cells do not contribute to the hematopoietic system. Consistent with a cell adhesion role for Cdh17, depletion of Cdh17 function using antisense morpholino oligonucleotides compromised cell cohesion during pronephric duct formation. Our results indicate that Cdh17 is necessary for maintaining the integrity of the pronephric ducts during zebrafish embryogenesis. This finding contrasts with the role of mammalian CDH17, which does not appear to be involved in nephric development.

Amino Acid Sequence↗

PubMed2002

A zebrafish orthologue (whnb) of the mouse nude gene is expressed in the epithelial compartment of the embryonic thymic rudiment.

The cloning and characterization of the zebrafish orthologue of the mouse nude (Whn/Foxn1) gene, whnb are reported. A previously described Whn-like gene from zebrafish, now designated as whna, is shown to be the orthologue of the mouse Foxn4 gene. The whnb gene is specifically expressed in the thymic rudiment of zebrafish embryos at day 3 after fertilization, whereas the whna gene is expressed in eye and brain structures. Whnb expression is maintained in cloche mutants, where endothelial and haematopoietic cell differentiation is defective, but absent in casanova mutants where endoderm formation is impaired. In adult thymi, whnb is expressed throughout cortical and medullary areas, whereas whna expression is observed in rare cell clusters only. Our results provide the first specific marker for the epithelial compartment of the zebrafish thymus.

Amino Acid Sequence↗

PubMed1998

Comparison of sequence and function of the Oct-6 genes in zebrafish, chicken and mouse.

To examine the role of the Oct-6 gene in Schwann cell differentiation we have cloned and characterized the chicken and zebrafish homologues of the mouse Oct-6 gene. While highly homologous in the Pit1-Oct1/2-Unc86 (POU) domain, sequence similarities are limited outside this domain. Both genes are intronless and both proteins lack the amino acid repeats that are a characteristic feature of the mammalian Oct-6 proteins. However as in mammals, the aminoterminal parts of the chicken and zebrafish Oct-6 proteins are essential for transactivation of octamer containing promoters. By immunohistochemistry we have found that the chicken Oct-6 protein is expressed in late embryonic ensheathing Schwann cells of the sciatic nerve and is rapidly downregulated when myelination proceeds. This expression profile in glial cells is identical to that in the mouse and rat. Furthermore the zebrafish Oct-6 homolog is expressed in the posterior lateral nerve at a time when it contains actively myelinating Schwann cells. Thus despite extensive primary sequence divergence among the vertebrate Oct-6 proteins, the expression of the chicken and zebrafish Oct-6 proteins is consistent with the notion that Oct-6 functions as a 'competence factor' in promyelin cells to execute the myelination program.

Amino Acid Sequence↗

PubMed2000

Insights into early vasculogenesis revealed by expression of the ETS-domain transcription factor Fli-1 in wild-type and mutant zebrafish embryos.

Fli-1 is an ETS-domain transcription factor whose locus is disrupted in Ewing's Sarcoma and F-MuLV induced erythroleukaemia. To gain a better understanding of its normal function, we have isolated the zebrafish homologue. Similarities with other vertebrates, in the amino acid sequence and DNA binding properties of Fli-1 from zebrafish, suggest that its function has been conserved during vertebrate evolution. The initial expression of zebrafish fli-1 in the posterior lateral mesoderm overlaps with that of gata2 in a potential haemangioblast population which likely contains precursors of blood and endothelium. Subsequently, fli-1 and gata2 expression patterns diverge, with separate fli-1 and gata2 expression domains arising in the developing vasculature and in sites of blood formation respectively. Elsewhere in the embryo, fli-1 is expressed in sites of vasculogenesis. The expression of fli-1 was investigated in a number of zebrafish mutants, which affect the circulatory system. In cloche, endothelium is absent and blood is drastically reduced. In contrast to the blood and endothelial markers that have been studied previously, fli-1 expression was initiated normally in cloche embryos, indicating that induction of fli-1 is one of the earliest indicators of haemangioblast formation. Furthermore, although fli-1 expression in the trunk was not maintained, the normal expression pattern in the anterior half of the embryo was retained. These anterior cells did not, however, condense to form blood vessels. These data indicate that cloche has previously unsuspected roles at multiple stages in the formation of the vasculature. Analysis of fli-1 expression in midline patterning mutants floating head and squint, confirms a requirement for the notochord in the formation of the dorsal-aorta. The formation of endothelium in one-eyed pinhead, cyclops and squint embryos indicates a novel role for the endoderm in the formation of the axial vein. The phenotype of sonic-you mutants implies a likely role for Sonic Hedgehog in mediating these processes.

Amino Acid Sequence↗

PubMed2000

Nodal-related signals establish mesendodermal fate and trunk neural identity in zebrafish.

The vertebrate body plan arises during gastrulation, when morphogenetic movements form the ectoderm, mesoderm, and endoderm. In zebrafish, mesoderm and endoderm derive from the marginal region of the late blastula, and cells located nearer the animal pole form the ectoderm [1]. Analysis in mouse, Xenopus, and zebrafish has demonstrated that Nodal-related proteins, a subclass of the TGF-beta superfamily, are essential for mesendoderm development [2], but previous mutational studies have not established whether Nodal-related signals control fate specification, morphogenetic movements, or survival of mesendodermal precursors. Here, we report that Nodal-related signals are required to allocate marginal cells to mesendodermal fates in the zebrafish embryo. In double mutants for the zebrafish nodal-related genes squint (sqt) and cyclops (cyc) [3] [4] [5], dorsal marginal cells adopt neural fates, whereas in wild-type embryos, cells at this position form endoderm and axial mesoderm. Involution movements characteristic of developing mesendoderm are also blocked in the absence of Nodal signaling. Because it has been proposed [6] that inhibition of Nodal-related signals promotes the development of anterior neural fates, we also examined anteroposterior organization of the neural tube in sqt;cyc mutants. Anterior trunk spinal cord is absent in sqt;cyc mutants, despite the presence of more anterior and posterior neural fates. These results demonstrate that nodal-related genes are required for the allocation of dorsal marginal cells to mesendodermal fates and for anteroposterior patterning of the neural tube.

Animals↗

PubMed2003

Molecular cloning and functional analysis of zebrafish high-density lipoprotein-binding protein.

High-density lipoprotein-binding protein (HBP) plays a pivotal role in the endocrine regulation of both lipids and cholesterol. This first study of the zebrafish (Danio rerio) HBP gene in a piscine provides information on the complex molecular events that regulates lipid and cholesterol functions in fish, and allows a comparison with starvation and hormonal regulation. One identical zebrafish HBP cDNA clone was obtained from a 24-h-old zebrafish cDNA library. Zebrafish HBP is composed of 1273 amino acids as residues. The 1273-aa of HBP has 87.8% and 87.0% similarities to human and chicken HBP, respectively. Real-time reverse transcription polymerase chain reaction (RT-PCR) analysis showed that HBP is highly expressed in the 36 h of the developmental stage after fertilization as compared to other stages. As to tissue-specific expression, the HBP is highly expressed in the fin, liver and ovary. In the starvation experiment, results show significant differences between the control group and the group after 3-week starvation. After injecting GH, IGF-I, IGF-II or insulin, no significant differences were shown between the control and the experimental groups. These results suggest that in vivo HBP expression is not regulated by the insulin family or by growth hormone, but other factors present during the starvation may down- or up-regulate the HBP. Although the exact function of the HBP is unknown, its high expression in the liver and ovary suggests a role for this molecule in the cumulative efficiency of fish intake of food or lipid transfer; these results can possibly be applied to aquaculture in the near future.

Animals↗

PubMed1994

Implications for dorsoventral axis determination from the zebrafish mutation janus.

THE mechanisms underlying the formation of dorsoventral polarity in the zebrafish Danio rerio are unknown. Here we describe the zebrafish recessive maternal-effect mutation janusm55. The mutant phenotype is a division of the blastoderm along the first cleavage plane into two detached half-sized blastoderms. Partial-axis bifurcation occurs in a subset of mutants. Analysis of goosecoid expression in the mutant embryos indicates that only one organizer region is present in each embryo. Furthermore, the position of this organizer region is random with respect to the first cleavage plane bisecting the two blastoderms. Finally, cell tracing in wild-type embryos demonstrates that there is no strict correlation of the dorsoventral axis with early cleavage planes in zebrafish. These findings support the notion that the establishment of the dorsoventral axis and the first cleavage planes are determined by separate mechanisms in the zebrafish embryo.

Animals↗