PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Zebrafish development”

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 649 records · Page 36Linked to original sources
PubMed1996

Mutations affecting the development of the embryonic zebrafish brain.

In a large scale mutagenesis screen for embryonic mutants in zebrafish, we have identified 63 mutations in 24 loci affecting the morphogenesis of the zebrafish brain. The expression of marker genes and the integrity of the axonal scaffold have been studied to investigate abnormalities in regionalization, neurogenesis and axonogenesis in the brain. Mutants can be broadly classified into two groups, one affecting regionalization along the anterior-posterior or dorsal-ventral axis, and the other affecting general features of brain morphology. The first group includes one locus that is required to generate the anlage of the midbrain-hindbrain boundary region at the beginning of somitogenesis. Four loci were identified that affect dorsal-ventral patterning of the brain, including the previously described cyclops locus. Mutant embryos of this class show a reduction of ventral neuroectodermal structures and variable fusion of the eyes. The second group includes a large class of mutations affecting the formation of brain ventricles. Analysis of this class reveals the requirement of a functional cardiovascular system for ventricle enlargement during embryogenesis. Mutations in one locus lead to the formation of supernumerary primary neurons, a phenotype reminiscent of neurogenic mutants in Drosophila. Other mutant phenotypes described here range from abnormalities in the fasciculation and outgrowth of axons to defects in the diameter of the neural tube. The identified loci establish the genetic foundation for a further analysis of the development of the zebrafish embryonic brain.

Animals↗
PubMed2006

Fishing for gene function--endocrine modelling in the zebrafish.

The use of zebrafish (Danio rerio) in scientific research is growing rapidly. It initially became popular as a model of vertebrate development because zebrafish embryos develop rapidly and are transparent. In the past 5 years, the sequencing of the zebrafish genome has increased the profile of zebrafish research even further, expanding into other areas such as pharmacology, cancer research and drug discovery. The use of zebrafish in endocrine research has mainly been confined to the study of the development of endocrine organs. However, it is likely to be a useful model in other areas of endocrinology, as there are a wide variety of both forward and reverse genetic techniques that can be employed in the zebrafish to decipher gene function in disease states. In this review, we compare the endocrine system of the zebrafish to mouse and human, demonstrating that the systems are sufficiently similar for zebrafish to be employed as a model for endocrine research. We subsequently review the repertoire of genetic techniques commonly employed in the zebrafish model to understand gene function in vertebrate development and disease. We anticipate that the use of these techniques will make the zebrafish a prominent model in endocrine research in the coming years.

Animals↗
PubMed2006

Microinjecting recombinant rainbow trout Ea4-peptide of pro-IGF-I into zebrafish embryos causes abnormal development in heart, red blood cells, and vasculature.

E-peptides and mature insulin-like growth factors (IGFs) are produced from pre-pro-IGFs during post-translational processing and co-secreted into the circulation. Previously, we reported that introduction of a transgene encoding the secreted form of rainbow trout (rt) Ea4-peptide or human (h) Eb-peptide into newly fertilized eggs of medaka (Oryzias latipes) and zebrafish (Danio rerio) resulted in developmental defects in heart, red blood cells and vasculature. In addition to vasculature and red blood cell developmental defects, multiple phenocopies of heart developmental defects categorized by developmental arrest at cardiomyocyte, heart tube and heart looping stages were also observed. These results raise a question of whether rtEa4- or hEb-peptide exerts pleiotropic inhibitory effects on heart, vasculature and red blood cell development in fish embryos. To answer this question, various amounts of recombinant rtEa4-peptide were microinjected into zebrafish eggs at 1.5, 2.5 and 5.5 h post-fertilization (hpf). Although a dose-dependent developmental defect in heart, vasculature and red blood cells was observed in embryos microinjected with rtEa4-peptide at 1.5 and 2.5 hpf, the heart development in all of the microinjected embryos was arrested at the cardiomyocyte stage. Furthermore, the mRNA levels of Nkx2.5, GATA5, VEGF, GATA1 and GATA2 genes in defective embryos were significantly reduced by rtEa4-peptide. These results confirm our previous findings that rtEa4- or hEb-peptide exhibits pleiotropic effects in inhibiting heart, vasculature and red blood cell development in zebrafish embryos.

Animals↗
PubMed2002

Linker histone H1M transcripts mark the developing germ line in zebrafish.

Maternally synthesised factors contribute to the establishment of the germ cell lineage in lower vertebrates. In zebrafish, germ-soma segregation appears to be completed by the late blastula stage of development. To search for new germ cell factors in the zebrafish, we have used subtractive cDNA cloning. Here we report that linker histone H1M transcripts mark the germ line from the early gastrulation up to 18 h post-fertilisation.

Animals↗
PubMed1997

Expression of zebrafish rag genes during early development identifies the thymus.

Recent experiments have demonstrated that zebrafish is a vertebrate in which it is possible to carry out large-scale mutagenic screens to identify genes involved in specific developmental pathways. To follow development of the immune system in zebrafish, we have analyzed the expression of the recombination activating genes, rag1 and rag2, which we have previously isolated and characterized. These genes catalyze the rearrangement of immunoglobulin genes in immature B lymphocytes and of T cell receptor genes in immature T lymphocytes and are therefore appropriate markers to follow the development of organs containing these cells. By whole-mount in situ hybridization, we detected expression of both rag genes in a paired organ in the head, beginning on the fourth day after fertilization. Histological examination of this organ indicated that it corresponds to the thymus, as described for other fish, an organ that has not previously been identified in zebrafish. By histological analysis, the thymus primordium appears at 54 hr but does not enlarge significantly until 30 hr later. The thymus continues to enlarge and reaches its mature histological organization at 1 month. The pronephros, the major hematopoietic organ in the adult fish, begins to develop hematopoietic tissue about 2 weeks after fertilization. By 1 month, mature lymphocytes are distinguishable in the tissue surrounding renal tubules. Lymphocytes appear in the kidney too late for screening by whole-mount in situ hybridization; however, the pattern of rag1 expression in the thymus forms the basis of an assay for mutations affecting development of the thymus or its constituent lymphocytes.

Animals↗
PubMed1999

Early hematopoiesis and developing lymphoid organs in the zebrafish.

In zebrafish, the transparent and rapidly developing embryo and the potential for genetic screening offer a unique opportunity to investigate the early development of the vertebrate immune system. Here we describe the initial appearance of various blood lineages and the nature of accumulating hematopoietic tissue in the thymus and kidney, the main lymphoid organs of adult teleosts. The ultrastructure of the first site of hematopoiesis, the intermediate cell mass (ICM), is described from the 5-somite stage, about 11.5 hours post-fertilization (hpf) until 24 hpf. The ICM gives rise to the primitive erythroid lineage, which accounts for all circulating erythrocytes for the first 4 days pf. From 24 to 72 hpf, a few developing granulocytes are seen close to the yolk sac walls and in the caudal axial vein. The heart, previously proposed as an early blood-forming organ in zebrafish, did not contain hematopoietic cells. The thymic primordium, consisting of two layers of epithelial cells, appears at 60 hpf. By 65 hpf, it is colonized by immature lymphoblasts. The thymus gradually accumulates lymphocytes, and the lymphocytes and epithelial cells progressively differentiate for 3 weeks pf. At 96 hr, the pronephros contains hematopoietic cells, mainly developing erythrocytes and granulocytes. The amount of renal hematopoietic tissue increases rapidly; however, lymphocytes were not detected until 3 weeks pf.

Animals↗
PubMed1997

The development of eye movements in the zebrafish (Danio rerio).

We investigated the development of oculomotor activity in zebrafish embryos and larvae of ages 48-96 hrs postfertilization (hpf). The optokinetic response (OKR: smooth tracking movements evoked by a rotating striped drum) improved steadily after its onset at 73 hpf, and by 96 hpf had a achieved a gain (eye velocity/drum velocity) of 0.9, comparable to adult performance. Reset movements (the fast phase of optokinetic nystagmus) developed over 75-81 hpf. The vestibuloocular reflex (VOR: compensatory eye movements evoked by passive rotation of the head) developed over 74-81 hpf, and the associated reset movements, over 76-81 hpf. The VOR was qualitatively normal in dark-reared fish, which excludes an essential role for visual experience in its early development. Spontaneous saccadic movements (the fast shift of eye position) appeared between 81 and 96 hpf, and at 96 hpf had maximum velocities that were comparable to adults. These results are compared to, and found to be incompatible with, two earlier ideas of motor development: behavioral "differentiation" and "encephalization."

Animals↗
PubMed2000

The zebrafish colourless gene regulates development of non-ectomesenchymal neural crest derivatives.

Neural crest forms four major categories of derivatives: pigment cells, peripheral neurons, peripheral glia, and ectomesenchymal cells. Some early neural crest cells generate progeny of several fates. How specific cell fates become specified is still poorly understood. Here we show that zebrafish embryos with mutations in the colourless gene have severe defects in most crest-derived cell types, including pigment cells, neurons and specific glia. In contrast, craniofacial skeleton and medial fin mesenchyme are normal. These observations suggest that colourless has a key role in development of non-ectomesenchymal neural crest fates, but not in development of ectomesenchymal fates. Thus, the cls mutant phenotype reveals a segregation of ectomesenchymal and non-ectomesenchymal fates during zebrafish neural crest development. The combination of pigmentation and enteric nervous system defects makes colourless mutations a model for two human neurocristopathies, Waardenburg-Shah syndrome and Hirschsprung's disease.

Animals↗
PubMed2006

Role of the hindbrain in patterning the otic vesicle: a study of the zebrafish vhnf1 mutant.

The vertebrate inner ear develops from an ectodermal placode adjacent to rhombomeres 4 to 6 of the segmented hindbrain. The placode then transforms into a vesicle and becomes regionalised along its anteroposterior, dorsoventral and mediolateral axes. To investigate the role of hindbrain signals in instructing otic vesicle regionalisation, we analysed ear development in zebrafish mutants for vhnf1, a gene expressed in the caudal hindbrain during otic induction and regionalisation. We show that, in vhnf1 homozygous embryos, the patterning of the otic vesicle is affected along both the anteroposterior and dorsoventral axes. First, anterior gene expression domains are either expanded along the whole anteroposterior axis of the vesicle or duplicated in the posterior region. Second, the dorsal domain is severely reduced, and cell groups normally located ventrally are shifted dorsally, sometimes forming a single dorsal patch along the whole AP extent of the otic vesicle. Third, and probably as a consequence, the size and organization of the sensory and neurogenic epithelia are disturbed. These results demonstrate that, in zebrafish, signals from the hindbrain control the patterning of the otic vesicle, not only along the anteroposterior axis, but also, as in amniotes, along the dorsoventral axis. They suggest that, despite the evolution of inner ear structure and function, some of the mechanisms underlying the regionalisation of the otic vesicle in fish and amniotes have been conserved.

Animals↗
PubMedDate not supplied

The zebrafish as a model organism for eye development.

In recent years, the zebrafish has become a favourite model organism for biologists studying developmental processes in vertebrates. Its rapid embryonic development, the transparency of its embryos, the large number of offspring together with several other advantages make it ideal for discovering and understanding the genes that regulate embryonic development as well as the physiology of the adult organism. Zebrafish are very visually orientated, and their retina and lens show much the same morphology as other vertebrates including humans. For this reason, they are well suited for examining ocular development, function and disease. This review describes the advantages of the zebrafish as a model organism as well as giving an overview of eye development in this species. It has a particular focus on morphological as well as molecular aspects of the development of the lens.

Animals↗
PubMed1997

Expression of c-ret in the zebrafish embryo: potential roles in motoneuronal development.

We have isolated and characterized the zebrafish ortholog of c-ret, a gene essential for renal organogenesis and enteric nervous system development in mammals. During zebrafish embryogenesis c-ret transcripts are expressed in a number of tissues including spinal motoneurons, pronephric ducts, cranial ganglia, pharyngeal arches, and the enteric nervous system. We have examined in detail the expression of c-ret during the development of identified spinal primary motoneurons. c-ret expression is regulated in a cell type-specific manner among the three primary motoneurons. c-ret is expressed at its highest levels in caudal primary (CaP) motoneurons and transcripts can be detected shortly before the expression of the CaP-specific gene, islet2. We suggest that c-ret may play a role in specifying CaP cell identity. c-ret is expressed at low levels in the other primary motoneurons and also in a subset of secondary motoneurons, suggesting that it may also play a broader role in motoneuronal survival or maintenance.

Amino Acid Sequence↗
PubMed1983

The development of the spinal motor column in relation to the myotomal muscle fibers in the zebrafish (Brachydanio rerio). I. Posthatching development.

The neuromuscular system in the trunk of larval and adult zebrafishes was studied by means of light and electronmicroscopical methods. Spinal motoneurons were identified with the horseradish peroxidase retrograde transport method. We correlated the differentiation and growth of the myotomal muscle with the number of motoneurons per spinal cord segment and the size of the motoneuron somata. The adult number of motoneurons is reached in an early larval stage, before the muscle fiber type differentiation in the myotomes is completed. The mean motoneuron size does not bear a clear correlation with the size of the myotomal muscle. In adult zebrafishes we could distinguish the motoneurons which innervate the superficial slow red and the deep fast white muscle fibers on the basis of soma size and position in the motor column. The motoneurons of the red muscle part are small; they are located in the ventrolateral part of the motor column. The motoneurons of the deep fast white fibers are large; they lie near the central canal.

Animals↗
PubMed2003

Changes in zinc, copper and metallothionein contents during oocyte growth and early development of the teleost Danio rerio (zebrafish).

In the present report, we investigated zinc, copper and metallothionein (MT) contents in zebrafish oocytes and embryos. Our results demonstrate that the metal content increases during oocytes maturation. Zinc increases from 30 ng/oocyte (stage-1 oocytes) to 100 ng/oocyte (stage-3 oocytes); copper varied from 1 ng/oocyte (stage-1 oocytes) to 3.5 ng/oocyte (stage-3 oocytes). During embryogenesis, zinc and copper contents dramatically increase after fertilisation around the 512-cells stage, then slowly decrease until the mid-gastrula stage. During oocyte growth, the changes in the MT level are proportional to metal content, whereas during embryogenesis the pattern of MT accumulation does not parallel that of the two metals. Indeed, the maternal pool of MT decreases steadily during the early stages of the development until the gastrula stage. We have examined the effect of cadmium on the expression of MT during zebrafish development. After cadmium exposure, MT content increases in embryos at the blastula stage, whereas no induction occurs in embryos at the gastrula stage. However, pre-treatment of embryos at the gastrula stage with 5-aza-2'-deoxycytidine induces MT synthesis following exposure to cadmium. These observations show that changes in metal levels are not correlated to MT content in the embryo, whereas DNA methylation is one of the factors regulating MT expression.

Animals↗
PubMed2000

Intestinal fatty acid binding protein gene expression reveals the cephalocaudal patterning during zebrafish gut morphogenesis.

Intracellular fatty acid-binding proteins (FABPs) are small and highly conserved cytoplasmic proteins that bind long-chain fatty acids and other hydrophobic ligands. We have examined, as a model for studying intestinal epithelial cell differentiation, the cell-specific and spatio-temporal expression of intestinal fatty acid-binding protein (i-fabp) gene during zebrafish larval development. After molecular cloning of zebrafish I-FABP cDNA, whole-mount in situ hybridization analysis revealed that i-fabp is expressed in the intestinal tube around day 3 postfertilization. By day 4, highest level of i-fabp transcript is encountered in the proximal columnar epithelium. From day 5 onwards, i-fabp is strongly expressed in the anterior intestine and its rostral expansion, slightly expressed in the esophagus mucosa and rectum, while no mRNA could be detected in the posterior intestine. Therefore, the regional differentiation of the intestine precedes first feeding and complete yolk resorption. I-fabp expression in the anterior intestine of the fed larvae is correlated with an intracellular storage of lipid droplets in the enterocytes and the massive synthesis of very low-density lipoprotein particles. In conclusion, the cephalocaudal expression pattern of i-fabp demarcates early during zebrafish gut morphogenesis the anterior fat absorbing to posterior cells of the intestine. This gene could be used as a marker for screening for mutations that affect the events of intestinal epithelial differentiation, cephalocaudal patterning, and asymmetric gut looping morphogenesis.

Amino Acid Sequence↗
PubMed1999

Gefiltin in zebrafish embryos: sequential gene expression of two neurofilament proteins in retinal ganglion cells.

Neurogenesis is correlated with the progressive synthesis of diverse neuronal intermediate filaments (IF) proteins. This apparent developmental regulation of IF protein gene expression suggests that specific neurofilament proteins impart unique structural attributes that support the staged growth of the neuron. In the teleost visual pathway, the sequential expression of two IF genes, plasticin and gefiltin, is linked to the age of retinal ganglion cells (RGCs) and to the regeneration of optic axons after nerve injury. Given this pattern of plasticin and gefiltin expression, we hypothesized that the two proteins would be sequentially expressed in zebrafish retina during development. We analyzed the pattern of gefiltin expression during zebrafish development and compared it to our previous determination of plasticin expression (Canger et al. 1998). Gefiltin is expressed after plasticin, during the later stages of retinal development when axons grow past the optic chiasm and innervate their targets. Thus, during RGC development, expression of plasticin and gefiltin resembles that with optic nerve regeneration. Outside of the visual pathway, gefiltin is predominantly expressed in the central nervous system whereas plasticin is primarily expressed in the peripheral nervous system. These results suggest that the expression of these genes is regulated in a neuron-specific manner. In addition, since plasticin and gefiltin are co-expressed during RGC development, these findings suggest a more complex mechanism of transcriptional regulation which orchestrates the sequential expression of these genes.

Animals↗
PubMed1996

Mutations affecting development of the notochord in zebrafish.

The notochord is critical for the normal development of vertebrate embryos. It serves both as the major skeletal element of the embryo and as a signaling source for the establishment of pattern within the neurectoderm, the paraxial mesoderm and other tissues. In a large-scale systematic screen of mutations affecting embryogenesis in zebrafish we identified 65 mutations that fall into 29 complementation groups, each leading to a defect in the formation and/or maintenance of the notochord. These mutations produce phenotypic abnormalities at numerous stages of notochord development, thereby establishing a phenotypic pathway, which in turn suggests a genetic pathway for the development of the notochord. Perturbations within adjacent tissues in mutant embryos further indicate the importance of notochord-derived signals for patterning within the embryo and suggest that these mutations will yield additional insight into the cues that regulate these patterning processes.

Animals↗
PubMed2004

Maternal control of vertebrate development before the midblastula transition: mutants from the zebrafish I.

Maternal factors control development prior to the activation of the embryonic genome. In vertebrates, little is known about the molecular mechanisms by which maternal factors regulate embryonic development. To understand the processes controlled by maternal factors and identify key genes involved, we embarked on a maternal-effect mutant screen in the zebrafish. We identified 68 maternal-effect mutants. Here we describe 15 mutations in genes controlling processes prior to the midblastula transition, including egg development, blastodisc formation, embryonic polarity, initiation of cell cleavage, and cell division. These mutants exhibit phenotypes not previously observed in zygotic mutant screens. This collection of maternal-effect mutants provides the basis for a molecular genetic analysis of the maternal control of embryogenesis in vertebrates.

Animals↗