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At least 73 records · Page 4Linked to original sources
PubMed1997

Cytokeratin 8 is a suitable epidermal marker during zebrafish development.

We have cloned and characterized the zebrafish (Danio rerio) homologous cytokeratin 8 (zf-K8) cDNA. This cytokeratin belongs to the gene family of intermediate filaments and it is a component of the cytoskeleton of epithelial cells. Gene expression analysis during embryonic development and at adult stages presented here revealed that zf-K8 mRNA is inherited maternally and that it is present in the oocyte, the zygote and in the cleavage stage embryo. After mid blastula transition this gene is expressed in all surface cells, notably in those of the enveloping layer (EVL) and of the periderm, as well as in a subpopulation of the deep cells (DEL) presumed to be intestinal progenitors. During later embryonic stage zf-K8 mRNA is strongly expressed in the developing pectoral fin. In adult zebrafish, the zf-K8 gene is not only expressed in simple epithelia such as the colorectal intestine, but also, in contrast to other vertebrates, it is present in stratified skin and differentiated fins. These observations suggest that the zf-K8 gene is an appropriate epidermal marker during zebrafish ontogenesis.

Amino Acid Sequence↗
PubMed2002

Phenylthiourea disrupts thyroid function in developing zebrafish.

Thyroid hormone (T4) can be detected in thyroid follicles in wild-type zebrafish larvae from 3 days of development, when the thyroid has differentiated. In contrast, embryos or larvae treated with goitrogens (substances such as methimazole, potassium percholorate, and 6-n-propyl-2-thiouracil) are devoid of thyroid hormone immunoreactivity. Phenythiourea (PTurea; also commonly known as PTU) is widely used in zebrafish research to suppress pigmentation in developing embryos/fry. PTurea contains a thiocarbamide group that is responsible for goitrogenic activity in methimazole and 6-n-propyl-2-thiouracil. In the present study, we show that commonly used doses of 0.003% PTurea abolish T4 immunoreactivity of the thyroid follicles of zebrafish larvae. As development of the thyroid gland is not affected, these data suggest that PTurea blocks thyroid hormone production. Like other goitrogens, PTurea causes delayed hatching, retardation and malformation of embryos or larvae with increasing doses. At doses of 0.003% PTurea, however, toxic side effects seem to be at a minimum, and the maternal contribution of the hormone might compensate for compromised thyroid function during the first days of development.

Animals↗
PubMed2006

cadherin-6 message expression in the nervous system of developing zebrafish.

Cadherins are cell surface adhesion molecules that play important roles in development of a variety of tissues including the nervous system. In this study, we analyzed expression pattern of cadherin-6, a member of the type II cadherin subfamily, in the embryonic zebrafish nervous system using in situ hybridization methods. cadherin-6 message is first expressed by the neural keel, then by restricted regions in the brain and spinal cord. cadherin-6 expression in the brain transiently delineates specific brain regions. In the peripheral nervous system, cadherin-6 message is expressed by the neurogenic placodes and the dorsal root ganglia. As development proceeds, cadherin-6 expression domain and/or expression levels increased in the embryonic nervous system. Our results show that cadherin-6 expression in the zebrafish developing nervous system is both spatially and temporally regulated, implicating a role for cadherin-6 in the formation of these nervous structures.

Animals↗
PubMed2001

Apoptosis in the developing zebrafish embryo.

Apoptosis is a major part of the normal development of many organ systems and tissues. The zebrafish (Danio rerio) has become a useful model for studying early development, and recent advances in techniques used to label apoptotic cells have made it possible to visualize apoptotic cells in this model system. We have used the in situ terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) to describe the temporal and spatial distribution of apoptotic cells during normal development of the zebrafish embryo from 12 to 96 h postfertilization. By counting labeled apoptotic cells, we have demonstrated transient high rates of cell death in various structures during development, and we have correlated these peaks with previously described developmental changes in these structures. Our analysis has focused on the nervous system and associated sensory organs including the olfactory organ, retina, lens, cornea, otic vesicle, lateral line organs, and Rohon-Beard neurons. Apoptosis is also described in other non-neural structures such as the notochord, somites, muscle, tailbud, and fins.

Animals↗
PubMed2004

Differential requirement for ptf1a in endocrine and exocrine lineages of developing zebrafish pancreas.

Mammalian studies have implicated important roles for the basic helix-loop-helix transcription factor Ptf1a-p48 in the development of both exocrine and endocrine pancreas. We have cloned the Ptf1a-p48 ortholog in Danio rerio. Early zebrafish ptf1a expression is observed in developing hindbrain and in endodermal pancreatic precursors. Analysis of ptf1a and insulin expression reveals a population of exocrine precursors that, throughout early development, are temporally and spatially segregated from endocrine elements. Morpholino-mediated knockdown of ptf1a confirms early divergence of these endocrine and exocrine lineages. Ptf1a morphants lack differentiated exocrine pancreas, but maintain normal differentiation and organization of the principal islet. In addition to the exocrine phenotype, ptf1a knockdown also reduces the prevalence of a small population of anterior endocrine cells normally found outside the principal islet. Together, these findings suggest the presence of distinct ptf1a-dependent and ptf1a-independent precursor populations in developing zebrafish pancreas.

Amino Acid Sequence↗
PubMed2004

Differential requirement for ptf1a in endocrine and exocrine lineages of developing zebrafish pancreas.

Mammalian studies have implicated important roles for the basic helix-loop-helix transcription factor Ptf1a-p48 in the development of both exocrine and endocrine pancreas. We have cloned the Ptf1a-p48 ortholog in Danio rerio. Early zebrafish ptf1a expression is observed in developing hindbrain and in endodermal pancreatic precursors. Analysis of ptf1a and insulin expression reveals a population of exocrine precursors that, throughout early development, are temporally and spatially segregated from endocrine elements. Morpholino-mediated knockdown of ptf1a confirms early divergence of these endocrine and exocrine lineages. Ptf1a morphants lack differentiated exocrine pancreas, but maintain normal differentiation and organization of the principal islet. In addition to the exocrine phenotype, ptf1a knockdown also reduces the prevalence of a small population of anterior endocrine cells normally found outside the principal islet. Together, these findings suggest the presence of distinct ptf1a-dependent and ptf1a-independent precursor populations in developing zebrafish pancreas.

Amino Acid Sequence↗
PubMed2004

In vivo biofluid dynamic imaging in the developing zebrafish.

Flow-structure interactions are ubiquitous in nature, and are important factors in the proper development of form and function in living organisms. In order to uncover the mechanisms by which flow-structure interactions affect vertebrate development, we first need to establish the techniques necessary to quantitatively describe the fluid flow environment within the embryo. To do this, we must bring dynamic, in vivo imaging methods to bear on living systems. Traditional avian and mammalian model systems can be problematic in this regard. The zebrafish (Danio rerio) is widely accepted as an excellent model organism for the study of vertebrate biology, as it shows substantial anatomical and genetic conservation with higher vertebrates, including humans. Their small size, optical transparency, and external development make zebrafish the ideal model system for dynamic imaging. This article reviews the current state of research in imaging biofluid flow within and around developing zebrafish embryos, with an emphasis on dynamic imaging modalities.

Animals↗
PubMed2003

Apoptosis in zebrafish development.

Apoptosis (programmed cell death) is important in normal biological processes and in pathogenesis in vertebrates. This review focuses on some of the prominent features of apoptosis during fish development. Caspases and other apoptosis-regulating genes have been cloned from zebrafish (Danio rerio) and other fish species. Elucidation of in vivo functions of apoptosis is focused on development, morphogenesis and sex differentiation. In an attempt to elucidate cause and effect relationships between caspase and development, transgenic zebrafish overexpressing procaspase-3 were generated. Stress-induced apoptosis in zebrafish embryos can be monitored by whole mount TUNEL staining and caspase assay. Thus, zebrafish is a useful experimental model animal for investigation of apoptosis in vivo.

Animals↗
PubMed2002

Cloning of two tryptophan hydroxylase genes expressed in the diencephalon of the developing zebrafish brain.

The monoamine serotonin (5-HT) exerts key neuromodulatory activities in all animal phyla, but the development and function of the serotonergic system is still incompletely understood. The zebrafish Danio rerio is an excellent model to approach this question since it is amenable to a combination of genetic, molecular and embryological studies. In order to characterize the organization of serotonergic neurons in the zebrafish we cloned two cDNAs encoding distinct forms of tryptophan hydroxylase (Tph), the rate-limiting enzyme in serotonin synthesis. We report here the pattern of expression of these two genes in relation with immunoreactive TH and 5-HT nuclei in the developing zebrafish embryo and early larva. tphD1 expression starts at 22 h post-fertilization (hpf) in the epiphysis and in basal spinal cells. Expression persists in the epiphysis until at least 4 days (dpf). Between 48 hpf and 3 dpf, tphD1 expression is initiated in retinal amacrine cells and in restricted preoptic and posterior tubercular nuclei within the basal diencephalon. At 3 and 4 dpf, tphD1 expression is newly initiated in the caudal hypothalamus and in branchial arches-associated neurons. tphD2 mRNA is detected transiently (between 30 somites and 32 hpf) in a restricted preoptic nucleus. All sites of tphD1 or D2 expression within the anterior central nervous system are also immunoreactive for 5-HT, but are not positive for TH. However, neither tphD gene is expressed in raphe nuclei, suggesting that additional tph gene(s) exist in zebrafish to account for 5-HT synthesis in that location. The co-expression of tphD1, tphD2 and 5-HT in the zebrafish diencephalon appears in striking contrast to the situation in mammals, where diencephalic serotonin results from re-uptake rather than from local production.

Animals↗
PubMed2002

Cloning of two tryptophan hydroxylase genes expressed in the diencephalon of the developing zebrafish brain.

The monoamine serotonin (5-HT) exerts key neuromodulatory activities in all animal phyla, but the development and function of the serotonergic system is still incompletely understood. The zebrafish Danio rerio is an excellent model to approach this question since it is amenable to a combination of genetic, molecular and embryological studies. In order to characterize the organization of serotonergic neurons in the zebrafish we cloned two cDNAs encoding distinct forms of tryptophan hydroxylase (Tph), the rate-limiting enzyme in serotonin synthesis. We report here the pattern of expression of these two genes in relation with immunoreactive TH and 5-HT nuclei in the developing zebrafish embryo and early larva. tphD1 expression starts at 22 h post-fertilization (hpf) in the epiphysis and in basal spinal cells. Expression persists in the epiphysis until at least 4 days (dpf). Between 48 hpf and 3 dpf, tphD1 expression is initiated in retinal amacrine cells and in restricted preoptic and posterior tubercular nuclei within the basal diencephalon. At 3 and 4 dpf, tphD1 expression is newly initiated in the caudal hypothalamus and in branchial arches-associated neurons. tphD2 mRNA is detected transiently (between 30 somites and 32 hpf) in a restricted preoptic nucleus. All sites of tphD1 or D2 expression within the anterior central nervous system are also immunoreactive for 5-HT, but are not positive for TH. However, neither tphD gene is expressed in raphe nuclei, suggesting that additional tph gene(s) exist in zebrafish to account for 5-HT synthesis in that location. The co-expression of tphD1, tphD2 and 5-HT in the zebrafish diencephalon appears in striking contrast to the situation in mammals, where diencephalic serotonin results from re-uptake rather than from local production.

Amino Acid Sequence↗
PubMed2006

A novel endothelial-specific heat shock protein HspA12B is required in both zebrafish development and endothelial functions in vitro.

A zebrafish transcript dubbed GA2692 was initially identified via a whole-mount in situ hybridization screen for vessel specific transcripts. Its mRNA expression during embryonic development was detected in ventral hematopoietic and vasculogenic mesoderm and later throughout the vasculature up to 48 hours post fertilization. Morpholino-mediated knockdown of GA2692 in embryos resulted in multiple defects in vasculature, particularly, at sites undergoing active capillary sprouting: the intersegmental vessels, sub-intestinal vessels and the capillary sprouts of the pectoral fin vessel. During the course of these studies, a homology search indicated that GA2692 is the zebrafish orthologue of mammalian HspA12B, a distant member of the heat shock protein 70 (Hsp70) family. By a combination of northern blot and real-time PCR analysis, we showed that HspA12B is highly expressed in human endothelial cells in vitro. Knockdown of HspA12B by small interfering RNAs (siRNAs) in human umbilical vein endothelial cells blocked wound healing, migration and tube formation, whereas overexpression of HspA12B enhanced migration and accelerated wound healing - data that are consistent with the in vivo fish phenotype obtained in the morpholino-knockdown studies. Phosphorylation of Akt was consistently reduced by siRNAs against HspA12B. Overexpression of a constitutively active form of Akt rescued the inhibitory effects of knockdown of HspA12B on migration of human umbilical vein endothelial cells. Collectively, our data suggests that HspA12B is a highly endothelial-cell-specific distant member of the Hsp70 family and plays a significant role in endothelial cells during development and angiogenesis in vitro, partially attributable to modulation of Akt phosphorylation.

Alkaline Phosphatase↗
PubMed2000

Nitric oxide and vascular reactivity in developing zebrafish, Danio rerio.

We used a newly developed digital motion analysis video technique to study the effects of nitric oxide (NO) and epinephrine on the early larval arterial and venous vasculature of zebrafish. Application of the NO donor sodium nitroprusside resulted in a significant increase in both the venous and arterial vessel diameters, whereas N(G)-nitro-L-arginine methyl ester caused a significant decrease in the same diameters. Thus our results show that both the venous and arterial vasculature of the 5- and 6-day-old zebrafish larvae are influenced by endogenously produced NO. By use of immunohistochemistry, NO synthase immunoreactivity was demonstrated in endothelial cells of the dorsal vein. Local application of epinephrine onto the dorsal artery had no effect on vessel diameter. However, if the embryos were preincubated with N(omega)-nitro-L-arginine methyl ester, addition of epinephrine resulted in a significant reduction in both arterial and venous vessel diameters. Thus this study provides increasing evidence that before a functional autonomic innervation of the peripheral vascular system, vascular tone in larval tissue is regulated by a complex interaction of vasoactive substances that are produced locally by vascular endothelial cells.

Animals↗
PubMed1999

Expression of the Ets transcription factors erm and pea3 in early zebrafish development.

Here we report the cloning of zebrafish erm and pea3 cDNAs, which are members of the PEA3 subgroup of Ets transcription factors. The expression patterns of these two genes were examined during zebrafish embryogenesis. Maternal mRNAs of both genes are detectable and transcripts are found ubiquitously until the late blastula, in the marginal zone of gastrula stages and in the presumptive fore- and hindbrain and in the trunk region of early somite stages. Later, erm expression is observed in distinct regions of the forebrain, the mid-/hindbrain boundary, the differentiating rhombomeres, branchial arches, otic vesicles, the pectoral fins, the somites and the tailbud in a dynamic fashion. In contrast, pea3 is not expressed in the rhombomeres but in the Rohon-Beard neurons, the sensory lateral line placodes and the heart.

Animals↗
PubMed1997

Novel Eph-family receptor tyrosine kinase is widely expressed in the developing zebrafish nervous system.

In a search for novel tyrosine kinases involved in vertebrate development, we have isolated cDNAs corresponding to three distinct members of the Eph-family of receptor tyrosine kinases. Whole mount RNA in situ hybridization analysis showed all three genes were most abundantly expressed in the developing nervous system. zek1 (zebrafish Eph-like kinase1) encodes a 981 amino acid polypeptide closely related to the murine Sek1 and Bsk receptors. Cos-1 cells transfected with zek1 produce a 141 kilodalton tyrosine phosphorylated protein which is recognized by antibodies raised against two predicted Zek1 peptides. These antibodies also recognized a protein of the same apparent molecular weight in lysates from zebrafish embryos and adults. Widespread expression of zek1 in the developing brain and neural tube suggested a generalized function of the Zek1 receptor in neuronal cell ontogeny.

Amino Acid Sequence↗
PubMed2005

Coordinate control of cell cycle regulatory genes in zebrafish development tested by cyclin D1 knockdown with morpholino phosphorodiamidates and hydroxyprolyl-phosphono peptide nucleic acids.

During early zebrafish (Danio rerio) development zygotic transcription does not begin until the mid-blastula transition (MBT) 3 h after fertilization. MBT demarcates transition from synchronous short cell cycles of S and M phases exclusively to full cycles encompassing G1 and G2 phases. Transcriptional profiling and RT-PCR analyses during these phases enabled us to determine that this shift corresponds to decreased transcript levels of S/M phase cell cycle control genes (e.g. ccna2, ccnb1, ccnb2 and ccne) and increased transcript levels of ccnd1, encoding cyclin D1, and orthologs of p21 (p21-like) and retinoblastoma (Rb-like 1). To investigate the regulation of this process further, the translation of ccnd1 mRNA, a G1/S checkpoint control element, was impaired by microinjection of ccnd1-specific morpholino phosphorodiamidate (MO) 20mer or hydroxyprolyl-phosphono peptide nucleic acid (HypNA-pPNA) 16mer antisense oligonucleotides. The resulting downregulation of cyclin D1 protein resulted in microophthalmia and microcephaly, but not lethality. The phenotypes were not seen with 3-mismatch MO 20mers or 1-mismatch HypNA-pPNA 16mers, and were rescued by an exogenous ccnd1 mRNA construct with five mismatches. Collectively, these results indicate that transcription of key molecular determinants of asynchronous cell cycle control in zebrafish embryos commences at MBT and that the reduction of cyclin D1 expression compromises zebrafish eye and head development.

Animals↗
PubMed2002

Platelet-derived growth factor A (pdgf-a) expression during zebrafish embryonic development.

Zebrafish pdgf-a gene was cloned and its expression pattern studied during zebrafish embryogenesis. Zebrafish pdgf-a mRNA was present at high levels in fertilized eggs as well as in all embryonic cells up to the end of gastrulation. Spatially restricted expression started after the onset of segmentation and was mainly localized in the developing pharyngeal arches. Transient expression was also detected in Kupffer's vesicle, a teleost-specific structure, and in lateral trunk and tail regions surrounding the neural keel, as well as areas of the developing pronephros.

Amino Acid Sequence↗
PubMed2006

Expression of two insm1-like genes in the developing zebrafish nervous system.

Insulinoma associated-1 (INSM1, formerly IA-1) is a Cys(2)-His(2) zinc finger transcription factor sharing conserved regions with Caenorhabditis elegans EGL-46 and Drosophila Nerfin-1. INSM, EGL-46, and Nerfin proteins comprise the EIN family of zinc finger transcription factors. egl-46 and nerfin-1 have been implicated in various aspects of neuronal differentiation including cell fate specification, axon guidance decisions and cell migration. Murine Insm1 has a restricted expression pattern in the developing CNS. We have characterized two zebrafish (Danio rerio) Insm1-like genes, insm1a and insm1b, and analyzed their expression patterns during embryonic development. Zebrafish insm1a and insm1b share an embryonic expression pattern comparable to the proneural deltaA as well as overlapping the neuronal marker elavl3. The expression pattern observed for zebrafish insm1a and insm1b is similar to other EIN homologues. Both zebrafish insm1-like transcripts are also present in a region of the embryo where pancreatic progenitors originate. The expression data along with functional characterization of invertebrate homologues suggest a conserved pathway involving the EIN transcription factors in early neurogenesis.

Amino Acid Sequence↗
PubMed2006

Expression of FoxP2 during zebrafish development and in the adult brain.

Fox (forkhead) genes encode transcription factors that play important roles in the regulation of embryonic patterning as well as in tissue specific gene expression. Mutations in the human FOXP2 gene cause abnormal speech development. Here we report the structure and expression pattern of zebrafish FoxP2. In zebrafish, this gene is first expressed at the 20-somite stage in the presumptive telencephalon. At this stage there is a significant overlap of FoxP2 expression with the expression of the emx homeobox genes. However, in contrast to emx1, FoxP2 is not expressed in the pineal gland or in the pronephric duct. After 72 hours of development, the expression of zebrafish FoxP2 becomes more complex in the brain. The developing optic tectum becomes the major area of FoxP2 expression. In the adult brain, the highest concentrations of the FoxP2 transcript can be observed in the optic tectum. In the cerebellum, only the caudal lobes show high levels of Foxp2 expression. These regions correspond to the vestibulocerebellum of mammals. Several other regions of the brain also show high levels of Foxp2 expression.

Amino Acid Sequence↗