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  • 1
    Keywords: EXPRESSION ; CELL ; PATHWAY ; ACTIVATION ; AXIS FORMATION ; JNK ; LAEVIS ; CONVERGENT EXTENSION MOVEMENTS ; gastrulation movements ; MORPHOGEN GRADIENT ; WNT5a ; ROR2 ; Wnt/PCP signaling ; Dishevelled ; Wnt11 ; Frizzled7 ; ATF2 ; PLANAR CELL-POLARITY ; VERTEBRATE GASTRULATION
    Abstract: Non-canonical/planar cell polarity (PCP) Wnt signaling plays important roles in embryonic development and tissue homeostasis, and is implicated in human disease. Monitoring Wnt/PCP signaling relies mostly on semi-quantitative bioassays or biochemical analysis. Here we describe a luciferase reporter assay based on an ATF2 response element, which faithfully monitors non-canonical Wnt signaling in Xenopus embryos. The assay is simple, quantitative, and robust. It can be used to detect non-canonical Wnt signaling changes following gain and loss of function of pathway components, including Wnt, Frizzled, Ror2, Disheveled, Rac1, MKK7, and JNK. Wnt/PCP signaling has recently been implicated in left-right asymmetry and our reporter assay suggests that in gastrula embryos there is a right-ward bias in Wnt/PCP signaling. We also mapped Wnt/PCP signaling in the early Xenopus embryo and find that it peaks in the dorso-vegetal region, paralleling Wnt/beta-catenin signaling. Developmental Dynamics, 2011. copyright 2010 Wiley-Liss, Inc.
    Type of Publication: Journal article published
    PubMed ID: 21128306
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  • 2
    Abstract: During the screening of a zebrafish postsomitogenesis embryo cDNA library, we have identified a cDNA corresponding to a novel type of protein localized to the notochordal sheath-associated extracellular matrix (ECM) of the embryo. The 4.049-kb mRNA encodes a predicted polypeptide of 1,207 amino acids (122 kDa, pI 10.50) with a potential signal peptide of 20 amino acids. After the signal peptide, the mature protein consists of 1,187 amino acids (119 kDa, pI 10.46), for which the name "Calymmin" (from Greek chialphalambdanumumualpha, to envelop, to cover) is proposed. The Calymmin mRNA is highly and transiently expressed by the notochord cells of the embryo from the 10- to 12-somite stage to the pharyngula period (13 and 24 hours postfertilization, respectively), and light and electron microscopical immunolocalization analysis revealed that the protein was specifically localized within a granular and filamentous layer of the ECM compartment surrounding the notochord. In zebrafish no tail mutants (ntl(tc41)), in which the notochord precursor cells are present but fail to differentiate, the Calymmin protein was not detected, confirming the notochord origin of Calymmin. These results indicate that Calymmin is a novel constitutive protein of the ECM compartment associated to the perinotochordal sheath in the zebrafish embryo, which is specifically expressed by the differentiating notochord cells.
    Type of Publication: Journal article published
    PubMed ID: 12112472
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  • 3
    Keywords: brain ; EXPRESSION ; human ; IMAGES ; TOOL ; GENE ; GENE-EXPRESSION ; TIME ; DYNAMICS ; BIOLOGY ; IN-SITU ; PATTERNS ; gene expression ; DATABASE ; REGION ; LOCALIZATION ; XENOPUS ; MORPHOLOGY ; ANNOTATION ; RESOURCE ; UPDATE ; development ; USA ; FLY EMBRYOS ; GEISHA ; gene expression pattern analysis ; GXD ; image annotation ; in situ images ; information storage and retrieval
    Abstract: The precise localization of gene expression within the developing embryo, and how it changes over time, is one of the most important sources of information for elucidating gene function. As a searchable resource, this information has up until now been largely inaccessible to the Xenopus community. Here, we present a new database of Xenopus gene expression patterns, queryable by specific location or region in the embryo. Pattern matching can be driven either from an existing in situ image, or from a user-defined pattern based on development stage schematic diagrams. The data are derived from the work of a group of 21 Xenopus researchers over a period of 4 days. We used a novel, rapid manual annotation tool, XenMARK, which exploits the ability of the human brain to make the necessary distortions in transferring data from the in situ images to the standard schematic geometry. Developmental Dynamics 238:1379-1388, 2009. (C) 2009 Wiley-Liss, Inc
    Type of Publication: Journal article published
    PubMed ID: 19347954
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  • 4
    Keywords: EXPRESSION ; CELL ; GENE-EXPRESSION ; DIFFERENTIATION ; XENOPUS ; NUCLEAR FACTOR ; EMBRYONIC STEM-CELLS ; ANTERIOR-POSTERIOR AXIS ; gastrulation ; MESODERM INDUCTION ; pluripotency ; CAUDAL GENES ; Cdx1 ; CELL FATE SPECIFICATION ; EARLY XENOPUS EMBRYOGENESIS ; FGF signaling ; germ layers ; Oct3/4 ; ORPHAN RECEPTOR ; SPEMANNS-ORGANIZER
    Abstract: Gastrulation marks the onset of germ layer formation from undifferentiated precursor cells maintained by a network including the Pou5f1 gene, Oct3/4. Negative regulation of the undifferentiated state is a prerequisite for germ layer formation and subsequent development. A novel cross-regulatory network was characterized including the Pou5f1 and Cdx1 genes as part of the signals controlling the onset of gastrulation. Of particular interest was the observation that, preceding gastrulation, the Xenopus Oct3/4 factors, Oct60, Oct25, and Oct91, positively regulate Cdx1 expression through FGF signaling, and during gastrulation the Oct3/4 factors become repressors of Cdx1. Cdx1 negatively regulates the Pou5f1 genes during gastrulation, thus contributing to the repression of the network maintaining the undifferentiated state and promoting the onset of gastrulation. These regulatory interactions suggest that Oct3/4 initiates its own negative autoregulation through Cdx1 up-regulation to begin the repression of pluripotency in preparation for the onset of gastrulation and germ layer differentiation.
    Type of Publication: Journal article published
    PubMed ID: 21360791
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  • 5
    Keywords: GROWTH ; proliferation ; GENE-EXPRESSION ; ACTIVATION ; VEINS ; MORPHOGEN GRADIENT ; FACTOR-BINDING SITES ; ADULT DROSOPHILA ; DORSAL CLOSURE ; GAGA FACTOR
    Abstract: Background: The Decapentaplegic (Dpp) signaling pathway is used in many developmental and homeostatic contexts, each time resulting in cellular responses particular to that biological niche. The flexibility of Dpp signaling is clearly evident in epithelial cells of the Drosophila wing imaginal disc. During larval stages of development, Dpp functions as a morphogen, patterning the wing developmental field and stimulating tissue growth. A short time later, however, as wing-epithelial cells exit the cell cycle and begin to differentiate, Dpp is a critical determinant of vein-cell fate. It is likely that the Dpp signaling pathway regulates different sets of target genes at these two developmental time points. Results: To identify mechanisms that temporally control the transcriptional output of Dpp signaling in this system, we have taken a gene expression profiling approach. We identified genes affected by Dpp signaling at late larval or early pupal developmental time points, thereby identifying patterning- and differentiation-specific downstream targets, respectively. Conclusions: Analysis of target genes and transcription factor binding sites associated with these groups of genes revealed potential mechanisms by which target-gene specificity of the Dpp signaling pathway is temporally regulated. In addition, this approach revealed novel mechanisms by which Dpp affects the cellular differentiation of wing-veins.
    Type of Publication: Journal article published
    PubMed ID: 24591046
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  • 6
    ISSN: 1058-8388
    Keywords: Chick embryo extract-derived factors ; Catecholaminergic phenotypic expression ; Neural crest-derived cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The differentiation of neural crest cells into catecholaminergic neurons is dependent upon both intrinsic properties and signals from the embryonic microenvironment. In tissue culture, the development of catecholaminergic traits is dependent upon factors present in chick embryo extract (CEE). This dependency suggests that soluble growth factors affect catecholaminergic differentiation in vivo. We have studied the role of CEE-derived factors and the potentially related influence of characterized growth factors on catecholaminergic phenotypic expression in avian neural crest cells. In this report, we show that CEE-derived factors and transforming growth factor beta1 (TGF-β1) differentially influence catecholaminergic phenotypic expression as well as melanogenesis. TGF-β1 substituted for CEE-derived factors and supported the in vitro differentiation of tyrosine hydroxylase (TH) and dopamine-β-hydroxylase (DBH) immunoreactivities, as well as catecholamine biosynthesis and storage. Differentiation of catecholaminergic cells was dependent on factors present in 10% CEE during the first 1-4 days in culture suggesting an initial critical period for exposure. One day of initial exposure to either CEE-derived factors or TGF-β1 was sufficient to support the subsequent expression of catecholaminergic phenotypic characteristics. The time course of responsiveness to TGF-β1 was different than for CEE-derived factors. Neural crest cells remain responsive to TGF-β1 for at least 5 days, which is past the critical period for CEE-derived factors. Bioassay of CEE shows that endogenous levels of TGF-β are less than or equal to 0.5 ng/ml. Immunoprecipitation of TGF-β from CEE or blockade by neutralizing antibodies did not result in a loss of catecholaminergic differentiation by neural crest cells. Although CEE supports melanogenesis under all of the growth conditions tested, TGF-β1 was found to be inhibitory. © 1993 wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 196 (1993) 
    ISSN: 1058-8388
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1058-8388
    Keywords: Induction of dorsal mesoderm ; Induction of ventral mesoderm ; Xenopus laevis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In the early Xenopus embryo, a quadrant of endodermal cells that have descended from the vegetal dorsal localization in the zygote produces signals that pass into the animal hemisphere and induce dorsal mesoderm from the marginal zone. From the remaining three quadrants of the bordering endoderm, signals pass into the animal hemisphere and induce ventral mesoderm in the marginal region. There is evidence that suggests that these same mesoderm-inducing signals continue through the plane of the tissue of the animal hemisphere where they may at least begin the processes of neural and epidermal induction by changing the competence of the prospective ectodermal cells, and possibly influencing the early regional biasing of later expression of at least some gene products, such as Epi-1 whose expression in the future epidermal domain seems specified before gastrulation. We hypothesized that the interaction of the ventral and dorsal signals within the plane of the tissue of the animal hemisphere may position the border of the neural plate. If this is so, then transplantation into the animal pole of cells that signal induction of ventral mesoderm should drive the neural plate boundary back toward the blastopore and shorten the anterior-posterior axis. Removal of cells that induce ventral mesoderm should result in an axis that is longer than normal. Results of our experiments support these predictions. Also, by late pregastrula stage 9, increasing the ventral signals has no effect. Thus the evidence suggests that the position of the anterior neural plate boundary is established before gastrulation begins by the interaction of the signals that induce the ventral and dorsal mesoderm. © 1993 wiley-Liss, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1058-8388
    Keywords: Lens ; Argininosuccinate lyase (ASL)/δ-crystallin ; Chicken development ; Gene expression ; Messenger RNA ; Polymerase chain reaction ; Isoenzyme ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Chicken argininosuccinate lyase (ASL)/δ-crystallin, a lens enzyme-crystallin, is encoded in two linked genes (δ1 and δ2); only the δ2 polypeptide contains ASL activity. Here we have quantified δ1- and δ2-crystallin mRNA in the lens, cornea, neural retina, heart, and brain at different stages of embryonic development and in 1-wk-old and 1-yr-old chickens by the polymerase chain reaction using internal δ1 and δ2 RNA standards. The δ1/δ2 mRNA ratio differed for every tissue and was regulated during development. In the embryo there was more δ1 than δ2 mRNA in the lens (50-100 times), cornea (3-4 times), and neural retina (2-20 times), about equal amounts of δ1 and δ2 mRNA in the heart, and more δ2 mRNA in the brain (15 times). δ1-Crystallin mRNA differentially decreased in every tissue after hatching; by contrast, the δ2 mRNA remained about the same except for the lens, where it decreased 50-fold between 1 wk and 1 yr after hatching. In the 1-yr-old chicken, the δ2/δ1 mRNA ratios were 7 in the lens, 175 in the cornea, 22 in the neural retina, 107 in the heart, and 136 in the brain, indicating that δ2-crystallin is strongly favored in all adult tissues of the chicken. The excess of δ1 to δ2 mRNA in the embryonic lens, cornea, and neural retina is intriguing, and suggests some connection with developing transparent eye tissues. Finally, we raise the possibility that expression of both δ-crystallin genes may create tetrameric ASL isoenzymes (perhaps with different specific activities). The unexpected predominance of δ2 mRNA in the 1-yr-old lens suggests that both the enzymatic and refractive functions of ASL/δ-crystallin are operative and spatially separated, with the enzymatic role present in the cortical fibers and the refractive role in the center of the lens. © 1993 wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1058-8388
    Keywords: Crystallin gene ; Lens specificity ; Transcriptional regulation ; Transgenic mice ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The mouse γF-crystallin gene, one of six differentially regulated members of the γ-crystallin gene family, is expressed exclusively in central nuclear fiber cells of the adult lens. The expression of this gene is controlled through regulatory elements contained in two upstream enhancers and the proximal promoter. Here we show that while the upstream enhancers and the proximal promoter could each direct gene expression in fiber cells formed at early stages of lens growth and development, cooperation between these elements is required to achieve expression in fiber cells formed at later stages. Evidence is provided that cooperative interaction between these elements modulates gene expression by increasing promoter strength. We also show that sequences within the proximal promoter region that bind lens cell nuclear factor γF-1 are sufficient to elicit gene expression in central nuclear fiber cells of the adult lens. © 1993 wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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