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PubMed2005

Zebrafish alpha-crystallins: protein structure and chaperone-like activity compared to their mammalian orthologs.

PURPOSE: The vertebrate small heat shock proteins alphaA- and alphaB-crystallin contribute to the transparency and refractive power of the lens and may also prevent the aggregation of non-native proteins that would otherwise lead to cataracts. We previously showed that zebrafish (Danio rerio) and human alphaB-crystallin have diverged far more in primary structure and expression pattern than the orthologous alphaA-crystallins. In this current study we further compare the structure and function of zebrafish and mammalian alpha-crystallins. METHODS: Near UV CD spectroscopy was used to analyze the tertiary structure and thermal stability of recombinant zebrafish alpha-crystallins. The chaperone-like activities of zebrafish and human alpha-crystallins were compared by assaying their ability to prevent the chemically induced aggregation of several target proteins at temperatures between 25 degrees C and 40 degrees C. RESULTS: Zebrafish and human alphaA-crystallin showed very similar tertiary structures, while the alphaB-crystallin orthologs showed differences related to the presence of additional aromatic amino acids in the zebrafish protein. The denaturation temperatures of zebrafish crystallins were lower than those of mammals. The chaperone-like activities of the two zebrafish alpha-crystallins were highly divergent, with alphaA-crystallin showing much greater activity than alphaB-crystallin. CONCLUSIONS: alphaA-crystallin serves a similar physiological function in both zebrafish and mammals as a lens specific chaperone-like molecule. The reduced chaperone-like function of zebrafish alphaB-crystallin and its lack of extralenticular expression indicates that it plays a different physiological role from its mammalian ortholog. Future comparative studies of alpha-crystallin from closely related vertebrate species can help identify specific structural changes that lead to alterations in chaperone-like activity.

Animals↗

PubMed2000

Expression of sox11 gene duplicates in zebrafish suggests the reciprocal loss of ancestral gene expression patterns in development.

To investigate the role of sox genes in vertebrate development, we have isolated sox11 from zebrafish (Danio rerio). Two distinct classes of sox11-related cDNAs were identified, sox11a and sox11b. The predicted protein sequences shared 75% identity. In a gene phylogeny, both sox11a and sox11b cluster with human, mouse, chick, and Xenopus Sox11, indicating that zebrafish, like Xenopus, has two orthologues of tetrapod Sox11. The work reported here investigates the evolutionary origin of these two gene duplicates and the consequences of their duplication for development. The sox11a and sox11b genes map to linkage groups 17 and 20, respectively, together with other loci whose orthologues are syntenic with human SOX11, suggesting that during the fish lineage, a large chromosome region sharing conserved syntenies with mammals has become duplicated. Studies in mouse and chick have shown that Sox11 is expressed in the central nervous system during development. Expression patterns of zebrafish sox11a and sox11b confirm that they are expressed in the developing nervous system, including the forebrain, midbrain, hindbrain, eyes, and ears from an early stage. Other sites of expression include the fin buds and somites. The two sox genes, sox11a and sox11b, are expressed in both overlapping and distinct sites. Their expression patterns suggest that sox11a and sox11b may share the developmental domains of the single Sox11 gene present in mouse and chick. For example, zebrafish sox11a is expressed in the anterior somites, and zebrafish sox11b is expressed in the posterior somites, but the single Sox11 gene of mouse is expressed in all the somites. Thus, the zebrafish duplicate genes appear to have reciprocally lost expression domains present in the sox11 gene of the last common ancestor of tetrapods and zebrafish. This splitting of the roles of Sox11 between two paralogues suggests that regulatory elements governing the expression of the sox11 gene in the common ancestor of zebrafish and tetrapods may have been reciprocally mutated in the zebrafish gene duplicates. This is consistent with duplicate gene evolution via a duplication-degeneration-complementation process.

Amino Acid Sequence↗

PubMed2004

Cloning and embryonic expression of zebrafish neuropilin genes.

Neuropilin (Nrp), a cell surface receptor for class 3 semaphorins and for certain heparin forms of vascular endothelial growth factors, functions in many biological processes including axon guidance, neural cell migration and angiogenesis in the development of the nervous system and the cardiovascular system. To understand the role of neuropilins in zebrafish embryogenesis, we have cloned three zebrafish neuropilin homologues, nrp1b, nrp2a and nrp2b. Based on synteny, zebrafish nrp1b and the previously cloned nrp1a are orthologous to human nrp1, and zebrafish nrp2a and 2b orthologous to human nrp2. We have characterized the expression patterns of these four zebrafish neuropilin genes in wild type embryos from the beginning of somitogenesis to 48 h post-fertilization. Zebrafish nrp1a is expressed in the neural tube including telencephalon, epithalamus, cells along the axonal trajectory of the posterior commissure and the medial longitudinal fascicle, hindbrain neurons, vagus motor neurons and spinal motoneurons. Zebrafish nrp1b is expressed in the nose, the cranial neural crest cell (NCC) derived tissue underlying the hypothalamus, endothelial precursors and the trunk and tail vasculature. Zebrafish nrp2a is expressed in telencephalon, anterior pituitary, oculomotor and trochlear motor neurons, cells along the supra-optic and posterior commissures, hindbrain rhombomere 1, hindbrain neurons, cranial NCCs and sclerotome. Zebrafish nrp2b is expressed in telencephalon, thalamus, hypothalamus, epiphysis, cells along the anterior and posterior commissures, post-optic and supra-optic commissures and the olfactory axonal trajectory, hindbrain neurons, cranial NCCs, somites and spinal cord neurons.

Animals↗

PubMed2004

Spatio-temporal distribution of cellular retinol-binding protein gene transcripts (CRBPI and CRBPII) in the developing and adult zebrafish (Danio rerio).

We have cloned and determined the nucleotide sequence of the cDNA coding for a cellular retinol-binding protein type I (CRBPI) from zebrafish. The deduced amino acid sequence of the zebrafish CRBPI showed highest sequence identity ( approximately 59%) to the mammalian CRBPIs of the intracellular lipid-binding protein (iLBP) multigene family. Phylogenetic analysis clustered the zebrafish CRBPI to the CRBPI clade. The zebrafish CRBPI gene (rbp1) and CRBPII gene (rbp2) both consist of four exons separated by three introns, identical to all other iLBP genes in vertebrates. Two transcription start sites were identified in the rbp1 promoter and a single transcription start site was identified for rbp2. Radiation hybrid mapping assigned the zebrafish rbp1 gene to linkage group 16 and conserved syntenic genes were found by comparative analysis of mammalian orthologous rbp1 genes. RT-PCR detected mRNA transcripts in the adult intestine, liver, brain, ovary and testis for rbp1 gene and in the intestine and liver for rbp2 gene. Whole mount in situ hybridization of zebrafish embryos revealed rbp1 mRNA expression in the developing zebrafish central nervous system at specific sites that are known to have abundant retinoic acid distribution and significant retinoic acid action. Whole mount in situ hybridization also showed that the zebrafish rbp2 mRNA was localized specifically in the embryonic intestinal bulb and the developing intestine during the larval stage, implying a novel function for the rbp2 gene product during organogenesis and development of the zebrafish intestine.

Amino Acid Sequence↗

PubMed2005

Identification of a new pebp2alphaA2 isoform from zebrafish runx2 capable of inducing osteocalcin gene expression in vitro.

UNLABELLED: The zebrafish runx2b transcription factor is an ortholog of RUNX2 and is highly conserved at the structural level. The runx2b pebp2alphaA2 isoform induces osteocalcin gene expression by binding to a specific region of the promoter and seems to have been selectively conserved in the teleost lineage. INTRODUCTION: RUNX2 (also known as CBFA1/Osf2/AML3/PEBP2alphaA) is a transcription factor essential for bone formation in mammals, as well as for osteoblast and chondrocyte differentiation, through regulation of expression of several bone- and cartilage-related genes. Since its discovery, Runx2 has been the subject of intense studies, mainly focused in unveiling regulatory targets of this transcription factor in high vertebrates. However, no single study has been published addressing the role of Runx2 in bone metabolism of low vertebrates. While analyzing the zebrafish (Danio rerio) runx2 gene, we identified the presence of two orthologs of RUNX2, which we named runx2a and runx2b and cloned a pebp2alphaA-like transcript of the runx2b gene, which we named pebp2alphaA2. MATERIALS AND METHODS: Zebrafish runx2b gene and cDNA were isolated by RT-PCR and sequence data mining. The 3D structure of runx2b runt domain was modeled using mouse Runx1 runt as template. The regulatory effect of pebp2alphaA2 on osteocalcin expression was analyzed by transient co-transfection experiments using a luciferase reporter gene. Phylogenetic analysis of available Runx sequences was performed with TREE_PUZZLE 5.2. and MrBayes. RESULTS AND CONCLUSIONS: We showed that the runx2b gene structure is highly conserved between mammals and fish. Zebrafish runx2b has two promoter regions separated by a large intron. Sequence analysis suggested that the runx2b gene encodes three distinct isoforms, by a combination of alternative splicing and differential promoter activation, as described for the human gene. We have cloned a pebp2alphaA-like transcript of the runx2b gene, which we named pebp2alphaA2, and showed its high degree of sequence similarity with the mammalian pebp2alphaA. The cloned zebrafish osteocalcin promoter was found to contain three putative runx2-binding elements, and one of them, located at -221 from the ATG, was capable of mediating pebp2alphaA2 transactivation. In addition, cross-species transactivation was also confirmed because the mouse Cbfa1 was able to induce the zebrafish osteocalcin promoter, whereas the zebrafish pebp2alphaA2 activated the murine osteocalcin promoter. These results are consistent with the high degree of evolutionary conservation of these proteins. The 3D structure of the runx2b runt domain was modeled based on the runt domain of mouse Runx1. Results show a high degree of similarity in the 3D configuration of the DNA binding regions from both domains, with significant differences only observed in non-DNA binding regions or in DNA-binding regions known to accommodate considerable structure flexibility. Phylogenetic analysis was used to clarify the relationship between the isoforms of each of the two zebrafish Runx2 orthologs and other Runx proteins. Both zebrafish runx2 genes clustered with other Runx2 sequences. The duplication event seemed, however, to be so old that, whereas Runx2b clearly clusters with the other fish sequences, it is unclear whether Runx2a clusters with Runx2 from higher vertebrates or from other fish.

Amino Acid Sequence↗

PubMed2002

Expression of three spalt (sal) gene homologues in zebrafish embryos.

Three homologues of the Drosophilaregion-specific homeotic gene spalt (sal) have been isolated in zebrafish, sall1a, sall1b and sall3. Phylogenetic analysis of these genes against known salDNA sequences showed zebrafish sall1aand sall1b to be orthologous to other vertebrate sal-1 genes and zebrafish sall3to be orthologous to other vertebrate sal-3 genes, except Xenopus sall3. Phylogenetic reconstruction suggests that zebrafish sall1a and sall1bresulted from a gene duplication event occurring prior to the divergence of the ray-finned and lobe-finned fish lineages. Analysis of the expression pattern of the zebrafish sal genes shows that sall1a and sall3 share expression domains with both orthologous and non-orthologous vertebrate sal genes. Both are expressed in various regions of the CNS, including in primary motor neurons. Outside of the CNS, sall1a expression is observed in the otic vesicle (ear), heart and in a discrete region of the pronephric ducts. These analyses indicate that orthologies between zebrafish sal genes and other vertebrate sal genes do not imply equivalence of expression pattern and, therefore, that biological functions are not entirely conserved. However we suggest that, like other vertebrate sal genes, zebrafish sal genes have a role in neural development. Also, expression of zebrafish sall1a in the otic vesicle, heart sac and the pronephric ducts of zebrafish embryos is possibly consistent with some of the abnormalities seen in Sall1-deficient mice and in Townes-Brocks Syndrome, a human disorder which is caused by mutations in the human spalt gene SALL1.

Animals↗

PubMed2005

kitb, a second zebrafish ortholog of mouse Kit.

The large numbers of duplicated pairs of genes in zebrafish compared to their mammalian counterparts has lead to the notion that expression of zebrafish co-orthologous pairs in some cases can together describe the expression of their mammalian counterpart. Here, we explore this notion by identification and analysis of a second zebrafish ortholog of the mammalian Kit receptor tyrosine kinase (kitb). We show that in embryos, kitb is expressed in a non-overlapping pattern to that of kita, in the anterior ventral mesoderm, Rohon-beardRohon-Beard neurons, the otic vesicle, and trigeminal ganglia. The expression pattern of kita and kitb in zebrafish together approximates that of Kit in mouse, with the exception that neither zebrafish kit gene is expressed in primordial germ cells, a site of kit expression in the mouse embryo. In addition, zebrafish kita is expressed in a site of zebrafish primitive hematopoiesis but not required for blood development, and we fail to detect kitb expression in sites of zebrafish hematopoiesis. Thus, the expression and function of zebrafish kit genes cannot be described as a simple partition of the expression and function of mouse Kit. We discuss the possibility that these unaccounted for expression domains and functions are derived from more ancestral gene duplications and partitioning instead of the relatively recent teleost teleost-specific duplication.

Animals↗

PubMed2006

Modeling human muscle disease in zebrafish.

Zebrafish reproduce in large quantities, grow rapidly, and are transparent early in development. For these reasons, zebrafish have been used extensively to model vertebrate development and disease. Like mammals, zebrafish express dystrophin and many of its associated proteins early in development and these proteins have been shown to be vital for zebrafish muscle stability. In dystrophin-null zebrafish, muscle degeneration becomes apparent as early as 3 days post-fertilization (dpf) making the zebrafish an excellent organism for large-scale screens to identify other genes involved in the disease process or drugs capable of correcting the disease phenotype. Being transparent, developing zebrafish are also an ideal experimental model for monitoring the fate of labeled transplanted cells. Although zebrafish dystrophy models are not meant to replace existing mammalian models of disease, experiments requiring large numbers of animals may be best performed in zebrafish. Results garnered from using this model could lead to a better understanding of the pathogenesis of the muscular dystrophies and the development of future therapies.

Animals↗

PubMed2004

Zebrafish heparin-binding neurotrophic factor enhances neurite outgrowth during its development.

Heparin-binding neurotrophic factor (HBNF) is a secreted heparin-binding protein containing highly basic and cysteine-rich amino acid residues. In this study, we cloned the full-length HBNF cDNA from zebrafish and determined its genomic structure by bioinformatics analysis. Zebrafish HBNF gene is composed of five exons and four introns spanning approximately 82kb. RT-PCR analysis revealed that zebrafish HBNF transcript was highly expressed in adult brain and intestine tissues while less in other tissues. During embryogenesis, zebrafish HBNF transcript was observed to be moderately expressed at earlier stages with a gradual decline. Higher expression level was observed after hatching and maintaining this level into adulthood. The overall amino acid sequence of zebrafish HBNF shows 60% identity to human HBNF, but with approximately 40% identity to other midkine proteins. Like mammalian homolog, zebrafish HBNF could induce significant neurite outgrowth in PC12 cells without NGF stimulation. In addition, zebrafish HBNF was able to enhance extensive neurite outgrowth in zebrafish embryos during embryogenesis. In summary, a feasible in vivo assay for neurite outgrowth was established in zebrafish.

Amino Acid Sequence↗

PubMed2004

A computer image processing system for quantification of zebrafish behavior.

The tropical zebrafish (Danio rerio) has frequently been used for investigating developmental biology. Here, we developed a computer image processing system for quantifying zebrafish behavior. We could acquire an image of zebrafish freely moving in an aquarium using a CCD camera through a graphic I/O board. To acquire the image of moving zebrafish in real time, we required high spatial (256 x 256 pixels) and temporal (10 frames/s) resolution. Such a high speed of data analysis was accomplished using a skipping search method. By using a small aquarium, trackings of newborn zebrafish could be traced. The velocity of adult zebrafish (7.2 cm/s) was far faster than that of newborn zebrafish (1.8 cm/s). Furthermore, by separation of occluded images of two fish, we could acquire images of the two zebrafish. They behaved as in a school in which one fish chased the other. The chasing was defined by the distance, angle and approach of the two fishes. The chasing ratio of pairs of zebrafish was 37%, whereas those of pairs of different fish were significantly reduced to less than 20%. The present image processing system is a very useful tool for quantitatively scoring the schooling behavior of multiple fish.

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PubMedDate not supplied

Nicotinic involvement in memory function in zebrafish.

Zebrafish are an emerging model for the study of the molecular mechanisms of brain function. To conduct studies of the neural bases of behavior in zebrafish, we must understand the behavioral function of zebrafish and how it is altered by perturbations of brain function. This study determined nicotine actions on memory function in zebrafish. With the methods that we have developed to assess memory in zebrafish using delayed spatial alternation (DSA), we determined the dose effect function of acute nicotine on memory function in zebrafish. As in rodents and primates, low nicotine doses improve memory in zebrafish, while high nicotine doses have diminished effect and can impair memory. This study shows that nicotine affects memory function in zebrafish much like in rats, mice, monkeys and humans. Now, zebrafish can be used to help understand the molecular mechanisms crucial to nicotine effects on memory.

Acetylcholine↗

PubMed2003

Molecular characterization of the GnRH system in zebrafish (Danio rerio): cloning of chicken GnRH-II, adult brain expression patterns and pituitary content of salmon GnRH and chicken GnRH-II.

The zebrafish has proven to be a model system with unparalleled utility in vertebrate genetic and developmental studies. Substantially less attention has been paid to the potential role that zebrafish can play in answering important questions of vertebrate reproductive endocrinology. As an initial step towards exploiting the advantages that the zebrafish model offers, we have characterized their gonadotropin-releasing hormone (GnRH) system at the molecular level. GnRHs comprise a family of highly conserved decapeptide neurohormones widely recognized to orchestrate the hormonal control of reproduction in all vertebrates. We have isolated the gene and cDNA encoding chicken GnRH-II (cGnRH-II) from zebrafish, as well as several kilobases of upstream promoter sequence for this gene. As the gene encoding salmon GnRH (sGnRH) has been previously isolated (Torgersen et al, 2002), this is the second GnRH gene isolated from zebrafish to date. We have localized expression of these two genes in the brains of reproductively mature zebrafish using in situ hybridization. sGnRH is localized to the olfactory bulb-terminal nerve region (OB-TN), the ventral telencephalon-preoptic area (VT-POA) and, as we report here for the first time in any teleost species, the hindbrain. cGnRH-II is expressed exclusively in the midbrain, as has been found in all other jawed vertebrate species examined. Finally, the levels of both GnRH peptides in pituitaries of reproductively mature zebrafish were quantified using specific ELISAs. sGnRH pituitary peptide levels were shown to be 3- to 4-fold higher than cGnRH-II pituitary peptide. The cumulative results of these experiments allow us to conclude that zebrafish express just two forms of GnRH in a site-specific manner within the brain, and that sGnRH is the hypophysiotropic GnRH form. This work lays the foundation for further research into the control of reproduction in zebrafish, such as the functional significance of multiple GnRHs in vertebrates, and the molecular mechanisms controlling tissue-specific GnRH expression.

Animals↗

PubMed2003

Inhibition of zebrafish epidermal growth factor receptor activity results in cardiovascular defects.

The physiological role of any of the epidermal growth factor (EGF) receptor tyrosine kinases has yet to be determined in zebrafish. We isolated a zebrafish homologue of EGFR (egfr) that shows a 63% amino acid overall identity to human EGFR but with 90% amino acid identity in the kinase domain. Whole mount in situ hybridization showed ubiquitous distribution of egfr transcripts during gastrulation, somitogenesis and later stages. When expressed in Chinese hamster ovary cells, zebrafish Egfr was a functional receptor that responded to EGF by receptor tyrosine phosphorylation and activation of MAP kinase. The function of zebrafish Egfr in vivo was determined by inhibiting its activity using EGFR kinase inhibitors and antisense morpholinos (MO), which inhibited Egfr kinase activity and translation of egfr messenger RNA into protein, respectively. The zebrafish is a particularly excellent model for studying cardiovascular development because zebrafish are transparent allowing direct visualization of the heart and circulation in the blood vessels. Inhibition of zebrafish Egfr activity in vivo impeded blood flow via the outflow tract into the aorta and impeded circulation in the axial and intersegmental vessels by 80 h post-fertilization. Analysis of the heart showed that the heart chambers and pericardial sacs were dilated and the outflow tracts were narrowed. Together these results suggested that zebrafish Egfr has a cardiovascular function in the developing zebrafish that is required for normal circulation.

Amino Acid Sequence↗

PubMed2004

Hematopoietic gene expression profile in zebrafish kidney marrow.

The zebrafish kidney marrow is considered to be the organ of definitive hematopoiesis, analogous to the mammalian bone marrow. We have sequenced 26,143 ESTs and isolated 304 cDNAs with putative full-length ORF from a zebrafish kidney marrow cDNA library. The ESTs formed 7,742 assemblies, representing both previously identified zebrafish ESTs (56%) and recently discovered zebrafish ESTs (44%). About 30% of these EST assemblies have orthologues in humans, including 1,282 disease-associated genes in the Online Mendelian Inheritance in Man (OMIM) database. Comparison of the effective and regulatory molecules related to erythroid functions across species suggests a good conservation from zebrafish to human. Interestingly, both embryonic and adult zebrafish globin genes showed higher homology to the human embryonic globin genes than to the human fetal/adult ones, consistent with evo-devo correlation hypothesis. In addition, conservation of a whole set of transcription factors involved in globin gene switch suggests the regulatory network for such remodeling mechanism existed before the divergence of the teleost and the ancestor of mammals. We also carried out whole-mount mRNA in situ hybridization assays for 493 cDNAs and identified 80 genes (16%) with tissue-specific expression during the first five days of zebrafish development. Twenty-six of these genes were specifically expressed in hematopoietic or vascular tissues, including three previously unidentified zebrafish genes: coro1a, nephrosin, and dab2. Our results indicate that conserved genetic programs regulate vertebrate hematopoiesis and vasculogenesis, and support the role of the zebrafish as an important animal model for studying both normal development and the molecular pathogenesis of human blood diseases.

Animals↗

PubMed1994

The zebrafish egr1 gene encodes a highly conserved, zinc-finger transcriptional regulator.

The Egr family of transcriptional regulators comprises a group of genes which encode members of the Cys2-His2 class of zinc-finger proteins. We have isolated a zebrafish egr1 homologue by screening a zebrafish genomic library with a mouse Egr1 zinc finger probe. Southern blotting indicated the existence of a single zebrafish egr1 gene and, as in higher vertebrates, the presence of related members of a larger gene family. Sequence analysis of the zebrafish egr1 coding region revealed a high level of homology to the mouse, rat, and human Egr1 genes with the notable exception of a polymorphic, triplet nucleotide repeat sequence in the region coding for the amino terminus of the Egr1 protein. The predicted DNA-binding, zinc-finger domain protein sequence was strictly conserved. The 5' region of the zebrafish egr1 gene contained a variety of transcription factor binding sites, also present in the mouse gene, for serum response factor, CREB and c-Ets. The zebrafish egr1 transcript was approximately 3.4 kb in size and was expressed in adult zebrafish brain and muscle RNA, a pattern of expression similar to that observed in mice. The potential for zebrafish egr1 to function as a transcriptional regulator was tested by constructing an expression vector containing zebrafish egr1 coding sequences under the control of a cytomegalovirus promoter. This construct was found to activate transcription of a reporter plasmid bearing multiple Egr1 binding sites when transiently cotransfected into mouse 3T3 cells. Our results indicate that the structure, regulation, and function of the Egr1 gene have been highly conserved during vertebrate evolution and suggest an important role for this gene in growth and development.

Amino Acid Sequence↗

PubMed1994

The zebrafish egr1 gene encodes a highly conserved, zinc-finger transcriptional regulator.

The Egr family of transcriptional regulators comprises a group of genes that encode members of the Cys2-His2 class of zinc finger proteins. We have isolated a zebrafish egr1 homolog by screening a zebrafish genomic library with a mouse Egr1 zinc finger probe. Southern blotting indicated the existence of single zebrafish egr1 gene and, as in higher vertebrates, the presence of related members of a larger gene family. Sequence analysis of the zebrafish egr1 coding region revealed a high level of homology to the mouse, rat, and human egr1 genes with the notable exception of a polymorphic, triplet nucleotide repeat sequence in the region coding for the amino terminus of the Egr1 protein. The predicted DNA-binding, zinc finger domain protein sequence was strictly conserved. The 5' region of the zebrafish egr1 gene contained a variety of transcription factor binding sites, also present in the mouse gene, for serum response factor, CREB, and c-ets. The zebrafish egr1 transcript was approximately 3.4 kb in size and was expressed in adult zebrafish brain and muscle RNA, a pattern of expression similar to that observed in mice. The potential for zebrafish egr1 to function as a transcriptional regulator was tested by constructing an expression vector containing zebrafish egr1 coding sequences under the control of a cytomegalovirus promoter. This construct was found to activate transcription of a reporter plasmid bearing multiple Egr1 binding sites when transiently cotransfected into mouse 3T3 cells. Our results indicate that the structure, regulation, and function of the Egr1 gene have been highly conserved during vertebrate evolution and suggest an important role for this gene in growth and development.

Amino Acid Sequence↗

PubMed2005

Zebrafish: a tool to study hemostasis and thrombosis.

PURPOSE OF REVIEW: In the past eight years our laboratory has developed the zebrafish model to study hemostasis and thrombosis. The purpose of this review is to explore current developments involving the zebrafish model in the study of hemostasis and thrombosis because the time is now ripe to apply this model to identify novel players that participate in hemostasis and thrombosis. RECENT FINDINGS: In the past twelve months, three papers appeared in the hemostasis and thrombosis area using the zebrafish model. The first one is a review article that summarizes establishment of the zebrafish model to study hemostasis and thrombosis. The second study is a methodological paper describing assays for measuring hemostasis and thrombosis by inducing vascular occlusion in zebrafish larvae. The third paper describes a knockdown of prothrombin in zebrafish, which recapitulates knockout studies in mouse, and marks the beginning of studies in the hemostasis and thrombosis area by this new knockdown technology. In addition to the above papers, there is one abstract that describes kinetics of thrombocyte and thrombocyte-microparticle recruitment in laser-induced arterial thrombus formation in zebrafish. SUMMARY: With the above advances, the zebrafish model has now matured to the point that it can address more important questions in the hemostasis and thrombosis area using genetic approaches. This review therefore summarizes the issues described in the above papers along with thoughts about future progress of the zebrafish model as a tool to study hemostasis and thrombosis.

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PubMed2000

The syntenic relationship of the zebrafish and human genomes.

The zebrafish is an important vertebrate model for the mutational analysis of genes effecting developmental processes. Understanding the relationship between zebrafish genes and mutations with those of humans will require understanding the syntenic correspondence between the zebrafish and human genomes. High throughput gene and EST mapping projects in zebrafish are now facilitating this goal. Map positions for 523 zebrafish genes and ESTs with predicted human orthologs reveal extensive contiguous blocks of synteny between the zebrafish and human genomes. Eighty percent of genes and ESTs analyzed belong to conserved synteny groups (two or more genes linked in both zebrafish and human) and 56% of all genes analyzed fall in 118 homology segments (uninterrupted segments containing two or more contiguous genes or ESTs with conserved map order between the zebrafish and human genomes). This work now provides a syntenic relationship to the human genome for the majority of the zebrafish genome.

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