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Lilianna Solnicakrezel - One of the best experts on this subject based on the ideXlab platform.
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essential roles of a zebrafish prdm1 blimp1 homolog in embryo patterning and organogenesis
Development, 2005Co-Authors: Thomas P Wilm, Lilianna SolnicakrezelAbstract:During vertebrate development the dorsal Gastrula or Spemann-Mangold organizer orchestrates axis formation largely by limiting the ventralizing and posteriorizing activity of bone morphogenetic proteins (BMPs). In mouse and Xenopus laevis , genes encoding the zinc finger transcriptional repressor Prdm1/Blimp1 (PR domain containing 1, with ZNF domain; previously named B lymphocyte-induced maturation protein 1) were recently shown to be expressed in the visceral endoderm and anterior endomesoderm, respectively, and the prechordal plate of Gastrula stage embryos. Later in development Prdm1/Blimp1 is expressed in many other tissues, including pharyngeal arches, limb buds, otic vesicles, photoreceptor cell layer, slow muscle and cloaca. Based on misexpression and dominant-negative studies, Prdm1/Blimp1 was proposed to promote anterior endomesoderm and head development in Xenopus laevis . Here we report the isolation and functional characterization of zebrafish prdm1 exhibiting a dynamic and evolutionarily conserved expression pattern. Misexpression of prdm1 inhibits the formation of dorsoanterior structures and reduces expression of chordin , which encodes a BMP antagonist. Conversely, interference with Prdm1 translation using antisense morpholino oligonucleotides, increases chordin expression, while reducing expression of Bmp genes, and consequently dorsalizing the embryo. At the end of the Gastrula period, prdm1 morphant embryos have enlarged animal-vegetal and anteroposterior embryonic axes. This altered embryo morphology is associated with augmented extension movements of dorsal tissues and normal posterior migration of ventral tissues. Additionally, Prdm1 activity is essential for proper development of slow muscle, the photoreceptor cell layer, branchial arches and pectoral fins. Our studies reveal essential roles for prdm1 in limiting the function of the Gastrula organizer and regulating cell fate specification and morphogenetic processes in precise correspondence with its intricate expression pattern.
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role of the zebrafish trilobite locus in Gastrulation movements of convergence and extension
Genesis, 2000Co-Authors: Diane S Sepich, Dina C Myers, Roland Short, Jacek Topczewski, Florence L Marlow, Lilianna SolnicakrezelAbstract:Summary: Convergence and extension are Gastrulation movements that participate in the establishment of the vertebrate body plan. Using new methods for quantifying convergence and extension movements of cell groups, we demonstrate that in wild-type embryos, dorsal convergence of lateral cells is initially slow, but speeds up between the end of the Gastrula period and early segmentation. Convergence and extension movements of lateral cells in trilobite mutants are normal during the Gastrula period but reduced by early segmentation. Morphometric studies revealed that during epiboly wild-type Gastrulae become ovoid, whereas trilobite embryos remain rounder. By segmentation, trilobite embryos exhibit shorter, broader embryonic axes. The timing of these morphological defects correlates well with impaired cell movements, suggesting reduced convergence and extension are the main defects underlying the trilobite phenotype. Our gene expression, genetic, and fate mapping analyses show the trilobite mutation affects movements without altering dorsoventral patterning or cell fates. We propose that trilobite function is required for cell properties that promote increased speed of converging cells and extension movements in the dorsal regions of the zebrafish Gastrula. genesis 27:159–173, 2000. © 2000 Wiley-Liss, Inc.
Thomas P Wilm - One of the best experts on this subject based on the ideXlab platform.
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essential roles of a zebrafish prdm1 blimp1 homolog in embryo patterning and organogenesis
Development, 2005Co-Authors: Thomas P Wilm, Lilianna SolnicakrezelAbstract:During vertebrate development the dorsal Gastrula or Spemann-Mangold organizer orchestrates axis formation largely by limiting the ventralizing and posteriorizing activity of bone morphogenetic proteins (BMPs). In mouse and Xenopus laevis , genes encoding the zinc finger transcriptional repressor Prdm1/Blimp1 (PR domain containing 1, with ZNF domain; previously named B lymphocyte-induced maturation protein 1) were recently shown to be expressed in the visceral endoderm and anterior endomesoderm, respectively, and the prechordal plate of Gastrula stage embryos. Later in development Prdm1/Blimp1 is expressed in many other tissues, including pharyngeal arches, limb buds, otic vesicles, photoreceptor cell layer, slow muscle and cloaca. Based on misexpression and dominant-negative studies, Prdm1/Blimp1 was proposed to promote anterior endomesoderm and head development in Xenopus laevis . Here we report the isolation and functional characterization of zebrafish prdm1 exhibiting a dynamic and evolutionarily conserved expression pattern. Misexpression of prdm1 inhibits the formation of dorsoanterior structures and reduces expression of chordin , which encodes a BMP antagonist. Conversely, interference with Prdm1 translation using antisense morpholino oligonucleotides, increases chordin expression, while reducing expression of Bmp genes, and consequently dorsalizing the embryo. At the end of the Gastrula period, prdm1 morphant embryos have enlarged animal-vegetal and anteroposterior embryonic axes. This altered embryo morphology is associated with augmented extension movements of dorsal tissues and normal posterior migration of ventral tissues. Additionally, Prdm1 activity is essential for proper development of slow muscle, the photoreceptor cell layer, branchial arches and pectoral fins. Our studies reveal essential roles for prdm1 in limiting the function of the Gastrula organizer and regulating cell fate specification and morphogenetic processes in precise correspondence with its intricate expression pattern.
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Essential roles of a zebrafish prdm1/blimp1 homolog in embryo patterning and organogenesis
Development, 2005Co-Authors: Thomas P Wilm, Lilianna Solnica-krezelAbstract:During vertebrate development the dorsal Gastrula or Spemann-Mangold organizer orchestrates axis formation largely by limiting the ventralizing and posteriorizing activity of bone morphogenetic proteins (BMPs). In mouse and Xenopus laevis , genes encoding the zinc finger transcriptional repressor Prdm1/Blimp1 (PR domain containing 1, with ZNF domain; previously named B lymphocyte-induced maturation protein 1) were recently shown to be expressed in the visceral endoderm and anterior endomesoderm, respectively, and the prechordal plate of Gastrula stage embryos. Later in development Prdm1/Blimp1 is expressed in many other tissues, including pharyngeal arches, limb buds, otic vesicles, photoreceptor cell layer, slow muscle and cloaca. Based on misexpression and dominant-negative studies, Prdm1/Blimp1 was proposed to promote anterior endomesoderm and head development in Xenopus laevis . Here we report the isolation and functional characterization of zebrafish prdm1 exhibiting a dynamic and evolutionarily conserved expression pattern. Misexpression of prdm1 inhibits the formation of dorsoanterior structures and reduces expression of chordin , which encodes a BMP antagonist. Conversely, interference with Prdm1 translation using antisense morpholino oligonucleotides, increases chordin expression, while reducing expression of Bmp genes, and consequently dorsalizing the embryo. At the end of the Gastrula period, prdm1 morphant embryos have enlarged animal-vegetal and anteroposterior embryonic axes. This altered embryo morphology is associated with augmented extension movements of dorsal tissues and normal posterior migration of ventral tissues. Additionally, Prdm1 activity is essential for proper development of slow muscle, the photoreceptor cell layer, branchial arches and pectoral fins. Our studies reveal essential roles for prdm1 in limiting the function of the Gastrula organizer and regulating cell fate specification and morphogenetic processes in precise correspondence with its intricate expression pattern.
Lilianna Solnica-krezel - One of the best experts on this subject based on the ideXlab platform.
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Essential roles of a zebrafish prdm1/blimp1 homolog in embryo patterning and organogenesis
Development, 2005Co-Authors: Thomas P Wilm, Lilianna Solnica-krezelAbstract:During vertebrate development the dorsal Gastrula or Spemann-Mangold organizer orchestrates axis formation largely by limiting the ventralizing and posteriorizing activity of bone morphogenetic proteins (BMPs). In mouse and Xenopus laevis , genes encoding the zinc finger transcriptional repressor Prdm1/Blimp1 (PR domain containing 1, with ZNF domain; previously named B lymphocyte-induced maturation protein 1) were recently shown to be expressed in the visceral endoderm and anterior endomesoderm, respectively, and the prechordal plate of Gastrula stage embryos. Later in development Prdm1/Blimp1 is expressed in many other tissues, including pharyngeal arches, limb buds, otic vesicles, photoreceptor cell layer, slow muscle and cloaca. Based on misexpression and dominant-negative studies, Prdm1/Blimp1 was proposed to promote anterior endomesoderm and head development in Xenopus laevis . Here we report the isolation and functional characterization of zebrafish prdm1 exhibiting a dynamic and evolutionarily conserved expression pattern. Misexpression of prdm1 inhibits the formation of dorsoanterior structures and reduces expression of chordin , which encodes a BMP antagonist. Conversely, interference with Prdm1 translation using antisense morpholino oligonucleotides, increases chordin expression, while reducing expression of Bmp genes, and consequently dorsalizing the embryo. At the end of the Gastrula period, prdm1 morphant embryos have enlarged animal-vegetal and anteroposterior embryonic axes. This altered embryo morphology is associated with augmented extension movements of dorsal tissues and normal posterior migration of ventral tissues. Additionally, Prdm1 activity is essential for proper development of slow muscle, the photoreceptor cell layer, branchial arches and pectoral fins. Our studies reveal essential roles for prdm1 in limiting the function of the Gastrula organizer and regulating cell fate specification and morphogenetic processes in precise correspondence with its intricate expression pattern.
Koichiro Shiokawa - One of the best experts on this subject based on the ideXlab platform.
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Overexpression of S-adenosylmethionine decarboxylase (SAMDC) in Xeno-pus embryos activates maternal program of apoptosis as a “fail-safe” mechanism of early embryogenesis
Cell Research, 2003Co-Authors: Chikara Kaito, Hiroshi Fukamachi, Takayasu Higo, Eiji Ta-kayama, Hiroshi Hara, Yoshikazu Ohya, Kazuei Igarashi, Koichiro ShiokawaAbstract:In Xenopus, injection of S-adenosylmethionine decarboxylase (SAMDC) mRNA into fertilized eggs or 2-cell stage embryos induces massive cell dissociation and embryo-lysis at the early Gastrula stage due to activation of the maternal program of apoptosis. We injected SAMDC mRNA into only one of the animal side blastomeres of embryos at different stages of cleavage, and examined the timing of the onset of the apoptotic reaction. In the injection at 4- and 8-cell stages, a considerable number of embryos developed into tadpoles and in the injection at 16- and 32-cell stages, all the embryos became tadpoles, although tadpoles obtained were sometimes abnormal. However, using GFP as a lineage tracer, we found that descendant cells of the blastomere injected with SAMDC mRNA at 8- to 32-cell stages are confined within the blastocoel at the early Gastrula stage and undergo apoptotic cell death within the blastocoel, in spite of the continued development of the injected embryos. These results indicate that cells overexpressed with SAMDC undergo apoptotic cell death consistently at the early Gastrula stage, irrespective of the timing of the mRNA injection. We assume that apoptosis is executed in Xenopus early Gastrulae as a “fail-safe” mechanism to eliminate physiologically-severely damaged cells to save the rest of the embryo.
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overexpression of s adenosylmethionine decarboxylase samdc in xeno pus embryos activates maternal program of apoptosis as a fail safe mechanism of early embryogenesis
Cell Research, 2003Co-Authors: Chikara Kaito, Hiroshi Fukamachi, Takayasu Higo, Hiroshi Hara, Yoshikazu Ohya, Kazuei Igarashi, Eiji Takayama, Koichiro ShiokawaAbstract:In Xenopus, injection of S-adenosylmethionine decarboxylase (SAMDC) mRNA into fertilized eggs or 2-cell stage embryos induces massive cell dissociation and embryo-lysis at the early Gastrula stage due to activation of the maternal program of apoptosis. We injected SAMDC mRNA into only one of the animal side blastomeres of embryos at different stages of cleavage, and examined the timing of the onset of the apoptotic reaction. In the injection at 4- and 8-cell stages, a considerable number of embryos developed into tadpoles and in the injection at 16- and 32-cell stages, all the embryos became tadpoles, although tadpoles obtained were sometimes abnormal. However, using GFP as a lineage tracer, we found that descendant cells of the blastomere injected with SAMDC mRNA at 8- to 32-cell stages are confined within the blastocoel at the early Gastrula stage and undergo apoptotic cell death within the blastocoel, in spite of the continued development of the injected embryos. These results indicate that cells overexpressed with SAMDC undergo apoptotic cell death consistently at the early Gastrula stage, irrespective of the timing of the mRNA injection. We assume that apoptosis is executed in Xenopus early Gastrulae as a "fail-safe" mechanism to eliminate physiologically-severely damaged cells to save the rest of the embryo.
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Different spatial distribution of mRNAs for activin receptors (type IIA and IIB) and follistatin in developing embryos of Xenopus laevis
Roux's archives of developmental biology : the official organ of the EDBO, 1995Co-Authors: Chie Koga, Kosuke Tashiro, Koichiro ShiokawaAbstract:Spatial distribution of mRNAs for activin receptors and follistatin was studied by Northern blot hybridization using RNAs from different parts of dissected Xenopus embryos. mRNAs of two activin receptors (type IIA and IIB) occurred uniformly in pre-Gastrular embryos, but occurred in larger amounts in ectoderm (in Gastrulae), neural plate (in neurulae) and anterior (head) regions (in tailbud embryos) than in other embryonic regions. By contrast, follistatin mRNA appeared almost exclusively in the dorsal mesoderm including invaginating organizer region at the Gastrula stage, in notochord and in dorsal ectoderm at the neurula stage, then in anterior part at the tailbud stage. The localized patterns of the distribution of these mRNAs may be due to the regionally different zygotic expression of genes in embryos at later stages. From the relatively widespread pattern of distribution of their mRNAs, we assume that both type IIA and type IIB activin receptors have broad functions in ectodermal and neural differentiation. On the other hand, follistatin mRNA showed quite a restricted pattern of expression, and therefore, we assume that follistatin may have functions more specifically related to the sites of expression of its mRNA. Thus, follistatin may be involved in the differentiation of notochord itself and/or directly be responsible for organizer functions such as neural induction and subsequent differentiation of induced neural tissues at the Gastrula and later stages.
E Arakawa - One of the best experts on this subject based on the ideXlab platform.
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Variation of cleavage pattern permitting normal development in a sand dollar, Peronella japonica: comparison with other sand dollars.
Development Genes and Evolution, 1996Co-Authors: Shonan Amemiya, E ArakawaAbstract:Peronella japonica, a sand dollar, forms an abbreviated pluteus larva and metamorphoses within 3 days without feeding. In the present study, the cleavage pattern of Peronella embryos was found to be quite irregular in the vegetal blastomeres at the fourth cleavage. Less than half of the embryos examined formed four typical micromeres. The majority formed zero, one, two or three typical micromeres of regular size, and the blastomere(s) remaining in the vegetal-most region was atypical in size and/or its direction of division. Most embryos were able to form pluteus larvae and a considerable proportion of these metamorphosed into juvenile sea urchins, regardless of whether or not they had formed four typical micromeres of regular size, although embryos which formed no typical micromeres developed into pluteus larvae less frequently. The micromere progeny in Peronella embryos form skeletogenic mesenchyme cells. The average numbers of skeletogenic mesenchyme cells in the three sand dollar species, Clypeaster japonicus, Astriclypeus manni and P. japonica were 62, 122 and 219, respectively. In these species, the skeletogenic mesenchyme cell-specific glycoprotein (msp130) was first detected immediately after ingression of the primary mesenchyme cells, spicules appeared at the early Gastrula stage and triradiate spicules were found in late Gastrulae. Appearance of these characteristics was markedly accelerated in the embryos of A. manni and P. japonica in comparison with those of C. japonicus. Each step in the formation of larval spicules was equally accelerated in A. manni and P. japonica, although the appearance of the adult skeleton was further accelerated in P. japonica in comparison with A. manni, possibly because of omission of the four- to eight-armed pluteus stages.
