Shunsuke Yaguchi

University of Tsukuba, Tsukuba, Ibaraki, Japan

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Publications (28)135.43 Total impact

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    ABSTRACT: Sea urchins are model non-chordate deuterostomes, and studying the nervous system of their embryos can aid in the understanding of the universal mechanisms of neurogenesis. However, despite the long history of sea urchin embryology research, the molecular mechanisms of their neurogenesis have not been well investigated, in part because neurons appear relatively late during embryogenesis. In this study, we used the species Temnopleurus reevesii as a new sea urchin model and investigated the detail of its development and neurogenesis during early embryogenesis. We found that the embryos of T. reevesii were tolerant of high temperatures and could be cultured successfully at 15-30°C during early embryogenesis. At 30°C, the embryos developed rapidly enough that the neurons appeared at just after 24 h. This is faster than the development of other model urchins, such as Hemicentrotus pulcherrimus or Strongylocentrotus purpuratus. In addition, the body of the embryo was highly transparent, allowing the details of the neural network to be easily captured by ordinary epifluorescent and confocal microscopy without any additional treatments. Because of its rapid development and high transparency during embryogenesis, T. reevesii may be a suitable sea urchin model for studying neurogenesis. Moreover, the males and females are easily distinguishable, and the style of early cleavages is intriguingly unusual, suggesting that this sea urchin might be a good candidate for addressing not only neurology but also cell and developmental biology. © 2015 Japanese Society of Developmental Biologists.
    No preview · Article · Mar 2015 · Development Growth and Regeneration
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    Shunsuke Yaguchi · Junko Yaguchi · Kazuo Inaba
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    ABSTRACT: bicaudal-C (bicC) mRNA encodes a protein containing RNA-binding domains that is reported to be maternally present with deflection in the oocytes/eggs of some species. The translated protein plays a critical role in the regulation of cell fate specification along the body axis during early embryogenesis in flies and frogs. However, it is unclear how it functions in eggs in which bicC mRNA is uniformly distributed, for instance, sea urchin eggs. Here, we show the function of BicC in the formation of neurogenic ectoderm of the sea urchin embryo. Loss-of-function experiments reveal that BicC is required for serotonergic neurogenesis and for expression of ankAT-1 gene, which is essential for the formation of apical tuft cilia in the neurogenic ectoderm of the sea urchin embryo. In contrast, the expression of FoxQ2, the neurogenic ectoderm specification transcription factor, is invariant in BicC morphants. Because FoxQ2 is an upstream factor of serotonergic neurogenesis and ankAT-1 expression, these data indicate that BicC functions in regulating the events that are coordinated by FoxQ2 during sea urchin embryogenesis.
    Preview · Article · Oct 2014 · Scientific Reports
  • Oliver Krupke · Shunsuke Yaguchi · Junko Yaguchi · Robert D Burke
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    ABSTRACT: Imaging is a critical tool in neuroscience, and our understanding of the structure and function of sea urchin nervous systems owes much to this approach. In particular, studies of neural development have been facilitated by methods that enable the accurate identification of specific types of neurons. Here we describe methods that have been successfully employed to study neural development in sea urchin embryos. Altering gene expression in part of an embryo is facilitated by injection of reagents into individual blastomeres, which enables studies of cell autonomous effects and single embryo rescue experiments. The simultaneous localization of an in situ RNA hybridization probe and a cell type specific antigen has enabled studies of gene expression in specific types of neurons. Fixatives and antibodies can be capricious; thus, we provide data on preservation of antigens with commonly used fixatives and buffers.
    No preview · Article · Feb 2014 · Methods in molecular biology (Clifton, N.J.)
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    Full-text · Dataset · Oct 2013
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    ABSTRACT: An apical tuft, which is observed in a wide range of embryos/larvae of marine invertebrates, is composed of a group of cilia that are longer and less motile than the abundant lateral cilia covering the rest of the embryonic surface. Although the apical tuft has been thought to function as a sensory organ, its molecular composition and roles are poorly understood. Here we identified a glutathione transferase theta (GSTT) as an abundant and specific component of the apical tuft in sea urchin embryos. The expression of GSTT mRNA increases and becomes limited to the animal plate of the mesenchyme blastula, gastrula and prism larva. Electron microscopy and tandem mass spectrometry demonstrated that the apical tuft contains almost every axonemal component for ciliary motility. Low concentrations of an inhibitor of glutathione transferase bromosulphophthalein (BSP) induce bending of apical tuft, suggesting that GSTT regulates motility of apical tuft cilia. Embryos treated with BSP swim with normal velocity and trajectories but show less efficiency of changing direction when they collide with an object. These results suggest that GSTT in the apical tuft plays an important role in the mechanical reception for the motility regulation of lateral motile cilia in sea urchin embryos. © 2013 Wiley Periodicals, Inc.
    Preview · Article · Aug 2013 · Cytoskeleton
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    Shunsuke Yaguchi · Robert D Burke

    Preview · Article · Jun 2013 · Molecular Reproduction and Development
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    Junko Yaguchi · Lynne M Angerer · Kazuo Inaba · Shunsuke Yaguchi
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    ABSTRACT: Serotonergic neurons differentiate in the neurogenic animal plate ectoderm of the sea urchin embryo. The regulatory mechanisms that control the specification or differentiation of these neurons in the sea urchin embryo are not yet understood, although, after the genome was sequenced, many genes encoding transcription factors expressed in this region were identified. Here, we report that zinc finger homeobox (zfhx1/z81) is expressed in serotonergic neural precursor cells, using double in situ hybridization screening with a serotonergic neural marker, tryptophan 5-hydroxylase (tph) encoding a serotonin synthase that is required for the differentiation of serotonergic neurons. zfhx1/z81 begins to be expressed at gastrula stage in individual cells in the anterior neuroectoderm, some of which also express delta. zfhx1/z81 expression gradually disappears as neural differentiation begins with tph expression. When the translation of Zfhx1/Z81 is blocked by morpholino injection, embryos express neither tph nor the neural marker synaptotagminB in cells of the animal plate, and serotonergic neurons do not differentiate. In contrast, Zfhx1/Z81 morphants do express fez, another neural precursor marker, which appears to function in the initial phase of specification/differentiation of serotonergic neurons. In addition, zfhx1/z81 is one of the targets suppressed in the animal plate by anti-neural signals such as Nodal as well as Delta-Notch. We conclude that Zfhx1/Z81 functions during the specification of individual anterior neural precursors and promotes the expression of tph and synaptotagminB, required for the differentiation of serotonergic neurons.
    Preview · Article · Dec 2011 · Developmental Biology
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    Lynne M Angerer · Shunsuke Yaguchi · Robert C Angerer · Robert D Burke
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    ABSTRACT: Recent studies of the sea urchin embryo have elucidated the mechanisms that localize and pattern its nervous system. These studies have revealed the presence of two overlapping regions of neurogenic potential at the beginning of embryogenesis, each of which becomes progressively restricted by separate, yet linked, signals, including Wnt and subsequently Nodal and BMP. These signals act to specify and localize the embryonic neural fields - the anterior neuroectoderm and the more posterior ciliary band neuroectoderm - during development. Here, we review these conserved nervous system patterning signals and consider how the relationships between them might have changed during deuterostome evolution.
    Preview · Article · Sep 2011 · Development
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    ABSTRACT: Partitioning ectoderm precisely into neurogenic and non-neurogenic regions is an essential step for neurogenesis of almost all bilaterian embryos. Although it is widely accepted that antagonism between BMP and its inhibitors primarily sets up the border between these two types of ectoderm, it is unclear how such extracellular, diffusible molecules create a sharp and precise border at the single-cell level. Here, we show that Fez, a zinc finger protein, functions as an intracellular factor attenuating BMP signaling specifically within the neurogenic region at the anterior end of sea urchin embryos, termed the animal plate. When Fez function is blocked, the size of this neurogenic ectoderm becomes smaller than normal. However, this reduction is rescued in Fez morphants simply by blocking BMP2/4 translation, indicating that Fez maintains the size of the animal plate by attenuating BMP2/4 function. Consistent with this, the gradient of BMP activity along the aboral side of the animal plate, as measured by pSmad1/5/8 levels, drops significantly in cells expressing Fez and this steep decline requires Fez function. Our data reveal that this neurogenic ectoderm produces an intrinsic system that attenuates BMP signaling to ensure the establishment of a stable, well-defined neural territory, the animal plate.
    Preview · Article · Aug 2011 · Development
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    ABSTRACT: Steroid hormones play essential roles in a wide variety of biological processes in multicellular organisms. The principal steroid hormones in nematodes and arthropods are dafachronic acids and ecdysteroids, respectively, both of which are synthesized from cholesterol as an indispensable precursor. The first critical catalytic step in the biosynthesis of these ecdysozoan steroids is the conversion of cholesterol to 7-dehydrocholesterol. However, the enzymes responsible for cholesterol 7,8-dehydrogenation remain unclear at the molecular level. Here we report that the Rieske oxygenase DAF-36/Neverland (Nvd) is a cholesterol 7,8-dehydrogenase. The daf-36/nvd genes are evolutionarily conserved, not only in nematodes and insects but also in deuterostome species that do not produce dafachronic acids or ecdysteroids, including the sea urchin Hemicentrotus pulcherrimus, the sea squirt Ciona intestinalis, the fish Danio rerio, and the frog Xenopus laevis. An in vitro enzymatic assay system reveals that all DAF-36/Nvd proteins cloned so far have the ability to convert cholesterol to 7-dehydrocholesterol. Moreover, the lethality of loss of nvd function in the fruit fly Drosophila melanogaster is rescued by the expression of daf-36/nvd genes from the nematode Caenorhabditis elegans, the insect Bombyx mori, or the vertebrates D. rerio and X. laevis. These data suggest that daf-36/nvd genes are functionally orthologous across the bilaterian phylogeny. We propose that the daf-36/nvd family of proteins is a novel conserved player in cholesterol metabolism across the animal phyla.
    Full-text · Article · Jun 2011 · Journal of Biological Chemistry
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    ABSTRACT: The ciliary band is a distinct region of embryonic ectoderm that is specified between oral and aboral ectoderm. Flask-shaped ciliary cells and neurons differentiate in this region and they are patterned to form an integrated tissue that functions as the principal swimming and feeding organ of the larva. TGFβ signaling, which is known to mediate oral and aboral patterning of the ectoderm, has been implicated in ciliary band formation. We have used morpholino knockdown and ectopic expression of RNA to alter TGFβ signaling at the level of ligands, receptors, and signal transduction components and assessed the differentiation and patterning of the ciliary band cells and associated neurons. We propose that the primary effects of these signals are to position the ciliary cells, which in turn support neural differentiation. We show that Nodal signaling, which is known to be localized by Lefty, positions the oral margin of the ciliary band. Signaling from BMP through Alk3/6, affects the position of the oral and aboral margins of the ciliary band. Since both Nodal and BMP signaling produce ectoderm that does not support neurogenesis, we propose that formation of a ciliary band requires protection from these signals. Expression of BMP2/4 and Nodal suppress neural differentiation. However, the response to receptor knockdown or dominant-negative forms of signal transduction components indicate signaling is not acting directly on unspecified ectoderm cells to prevent their differentiation as neurons. Instead, it produces a restricted field of ciliary band cells that supports neurogenesis. We propose a model that incorporates spatially regulated control of Nodal and BMP signaling to determine the position and differentiation of the ciliary band, and subsequent neural patterning.
    Full-text · Article · Nov 2010 · Developmental Biology
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    ABSTRACT: In sea urchin embryos, the apical tuft forms within the neurogenic animal plate. When FoxQ2, one of the earliest factors expressed specifically in the animal plate by early blastula stage, is knocked down, the structure of the apical tuft is altered. To determine the basis of this phenotype, we identified FoxQ2-dependent genes using microarray analysis. The most strongly down-regulated gene in FoxQ2 morphants encodes a protein with ankyrin repeats region in its N-terminal domain. We named this gene ankAT-1, Ankyrin-containing gene specific for Apical Tuft. Initially its expression in the animal pole region of very early blastula stage embryos is FoxQ2-independent but becomes FoxQ2-dependent beginning at mesenchyme blastula stage and continuing in the animal plate of 3-day larvae. Furthermore, like FoxQ2, this gene is expressed throughout the expanded apical tuft region that forms in embryos lacking nuclear β-catenin. When AnkAT-1 is knocked-down by injecting a morpholino, the cilia at the animal plate in the resulting embryos are much shorter and their motility is less than that of motile cilia in other ectoderm cells, and remains similar to that of long apical tuft cilia. We conclude that AnkAT-1 is involved in regulating the length of apical tuft cilia.
    Preview · Article · Sep 2010 · Developmental Biology
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    ABSTRACT: The mechanisms that regulate the organized swimming movements of sea urchin blastulae are largely unknown. Using immunohistochemistry, we found that dopamine (DA) and the Hemicentrotus pulcherrimus homolog of the dopamine receptor D1 (Hp-DRD1) were strongly co-localized in 1-2 microm diameter granules (DA/DRD1 granules). Furthermore, these granules were arranged across the entire surface of blastulae as they developed locomotory cilia before hatching, and remained evident until metamorphosis. DA/DRD1 granules were associated with the basal bodies of cilia, and were densely packed in the ciliary band by the eight-arm pluteus stage. The transcription of Hp-DRD1 was detected from the unfertilized egg stage throughout the period of larval development. Treatment with S-(-)-carbidopa, an inhibitor of aromatic-l-amino acid decarboxylase, for 20-24 h (i) from soon after insemination until the 20 h post-fertilization (20 hpf) early gastrula stage and (ii) from the 24 hpf prism larva stage until the 48 hpf pluteus stage, inhibited the formation of DA granules and decreased the swimming activity of blastulae and larvae in a dose-dependent manner. Exogenous DA rescued these deprivations. The formation of DRD1 granules was not affected. However, in 48 hpf plutei, the serotonergic nervous system (5HT-NS) developed normally. Morpholino antisense oligonucleotides directed against Hp-DRD1 inhibited the formation of DRD1 granules and the swimming of larvae, but did not disturb the formation of DA granules. Thus, the formation of DRD1 granules and DA granules occurs chronologically closely but mechanically independently and the swimming of blastulae is regulated by the dopaminergic system. In plutei, the 5HT-NS closely surrounded the ciliary bands, suggesting the functional collaboration with the dopaminergic system in larvae.
    Full-text · Article · Aug 2010 · Journal of Experimental Biology
  • Yasunori Sasakura · Junko Yaguchi · Shunsuke Yaguchi · Mamiko Yajima
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    ABSTRACT: Tc1/mariner superfamily transposons are used as transformation vectors in various model organisms. The utility of this transposon family is evidenced by the fact that Tc1/mariner transposons have loose host specificity. However, the activity of these transposons has been observed in only a few organisms, and a recent study in the ascidian Ciona intestinalis suggests that not all Tc1/ mariner transposons show loose host specificity. To understand host specificity, we used sea urchins, since they have a long history as materials of embryology and developmental biology. Transposon techniques have not been reported in this organism, despite the likelihood that these techniques would open up many experimental possibilities. Here we tested the activity of three Tc1/ mariner transposons (Minos, Sleeping Beauty, and Frog Prince) in the sea urchin Hemicentrotus pulcherrimus. Minos has both excision and transposition activity in H. pulcherrimus embryos, whereas no excision activity was detected for Sleeping Beauty or Frog Prince. This study suggests that Minos is active in a broad range of non-host organisms and can be used as a transformation tool in sea urchin embryos.
    No preview · Article · Mar 2010 · ZOOLOGICAL SCIENCE
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    Shioh Ooka · Tomoko Katow · Shunsuke Yaguchi · Junko Yaguchi · Hideki Katow
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    ABSTRACT: We have cloned and studied Hp-ECPN, an encephalopsin orthologue of the sea urchin Hemicentrotus pulcherrimus. Hp-ecpn cDNA was produced and found to contain a 1461-bp open reading frame that encodes 486 amino acids. Accumulation of Hp-ecpn mRNA and protein expression occurred at the 14 h postfertilization (hpf) swimming blastula stage and thereafter. The Hp-ECPN protein was N-glycosylated, and the amino acid sequence was similar to that of vertebrate encephalopsins. Whole-mount immunohistochemistry revealed the presence of Hp-ECPN in cells (ECPN cells) that appeared initially around the tip of the archenteron in 20 hpf early gastrulae. By the 54 hpf pluteus stage, ECPN cells had spread through the aboral ectoderm, and, by the eight-arm pluteus stage, were restricted to the tips of the larval arms and the posterior end of the body. The number of ECPN cells increased under conditions of continuous light, but decreased under continuous dark. Knockdown of Hp-ecpn mRNA using morpholino antisense oligonucleotides decreased the number of ECPN cells considerably, and inhibited the vertical swimming of the larvae. This suggested that Hp-ECPN plays a role in photosensitive larval swimming vertical migration. In adult tissues, the ECPN cells were detected exclusively in tube feet.
    Full-text · Article · Feb 2010 · Development Growth and Regeneration
  • Z. Wei · J. Yaguchi · S. Yaguchi · R.C. Angerer · L.M. Angerer

    No preview · Article · May 2009
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    ABSTRACT: Two major signaling centers have been shown to control patterning of sea urchin embryos. Canonical Wnt signaling in vegetal blastomeres and Nodal signaling in presumptive oral ectoderm are necessary and sufficient to initiate patterning along the primary and secondary axes, respectively. Here we define and characterize a third patterning center, the animal pole domain (APD), which contains neurogenic ectoderm, and can oppose Wnt and Nodal signaling. The regulatory influence of the APD is normally restricted to the animal pole region, but can operate in most cells of the embryo because, in the absence of Wnt and Nodal, the APD expands throughout the embryo. We have identified many constituent APD regulatory genes expressed in the early blastula and have shown that expression of most of them requires Six3 function. Furthermore, Six3 is necessary for the differentiation of diverse cell types in the APD, including the neurogenic animal plate and immediately flanking ectoderm, indicating that it functions at or near the top of several APD gene regulatory networks. Remarkably, it is also sufficient to respecify the fates of cells in the rest of the embryo, generating an embryo consisting of a greatly expanded, but correctly patterned, APD. A fraction of the large group of Six3-dependent regulatory proteins are orthologous to those expressed in the vertebrate forebrain, suggesting that they controlled formation of the early neurogenic domain in the common deuterostome ancestor of echinoderms and vertebrates.
    Full-text · Article · May 2009 · Development
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    Shunsuke Yaguchi · Junko Yaguchi · Robert C Angerer · Lynne M Angerer
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    ABSTRACT: The primary (animal-vegetal) (AV) and secondary (oral-aboral) (OA) axes of sea urchin embryos are established by distinct regulatory pathways. However, because experimental perturbations of AV patterning also invariably disrupt OA patterning and radialize the embryo, these two axes must be mechanistically linked. Here we show that FoxQ2, which is progressively restricted to the animal plate during cleavage stages, provides this linkage. When AV patterning is prevented by blocking the nuclear function of beta-catenin, the animal plate where FoxQ2 is expressed expands throughout the future ectoderm, and expression of nodal, which initiates OA polarity, is blocked. Surprisingly, nodal transcription and OA differentiation are rescued simply by inhibiting FoxQ2 translation. Therefore, restriction of FoxQ2 to the animal plate is a crucial element of canonical Wnt signaling that coordinates patterning along the AV axis with the initiation of OA specification.
    Full-text · Article · Feb 2008 · Developmental Cell
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    Hideki Katow · Shunsuke Yaguchi · Keiichiro Kyozuka
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    ABSTRACT: A full-length serotonin receptor mRNA from the 5Hthpr gene was sequenced from larvae of the sea urchin, Hemicentrotus pulcherrimus. The DNA sequence was most similar to 5HT-1A of the sea urchin Strongylocentrotus purpuratus found by The Sea Urchin Genome Project, and the protein sequence predicted the presence of seven transmembrane domains. Immunohistochemistry with anti-5HThpr antibodies indicated that the protein was expressed on blastocoelar cells that comprised the major blastocoelar network (serotonin receptor cell network). These network cells inserted their processes into the ectoderm in various regions, including the ciliary band region. Serotonin injected into the blastocoel stimulated a transient elevation of cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) in the ectoderm, as detected by Oregon-Green dextran, injected earlier in development. The calcium transient propagated as a wave at about 175 microm s(-1), but was not detectable in the serotonin receptor-positive cell network. In larvae treated with p-chlorophenylalanine, a potent and irreversible serotonin synthesis inhibitor, serotonin application did not stimulate [Ca(2+)](i), the serotonin receptor cell network did not develop properly, and the swimming behavior of the larvae was abnormal. However, formation of a different nervous system comprising synaptotagmin-possessed neurites was not affected by p-chlorophenylalanine treatment. These results imply that serotonin secreted from the apical ganglion into the blastocoel stimulates the elevation of [Ca(2+)](i) in the larval ectodermal cells through the serotonin receptor cell network.
    Full-text · Article · Mar 2007 · Journal of Experimental Biology
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    Shunsuke Yaguchi · Junko Yaguchi · Robert D Burke
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    ABSTRACT: Nodal functions in axis and tissue specification during embryogenesis. In sea urchin embryos, Nodal is crucial for specification of oral ectoderm and is thought to pattern neurogenesis in the animal plate. To determine if Nodal functions directly in suppressing neuron differentiation we have prepared mutant forms of Sp-Smad2/3. Expressing an activated form produces embryos similar to embryos overexpressing Nodal, but with fewer neurons. In chimeras in which Nodal is suppressed, cells expressing activated Sp-Smad2/3 form oral ectoderm, but not neurons. In embryos with vegetal signaling blocked, neurons do not form if activated Smad2/3 is co-expressed. Expression of dominant negative mutants produces embryos identical to those resulting from blocking Nodal expression. In chimeras overexpressing Nodal, cells expressing dominant negative Sp-Smad2/3 form aboral ectoderm and give rise to neurons. In permanent blastula chimeras dominant negative Sp-Smad2/3 is able to suppress the effects of Nodal permitting neuron differentiation. In these chimeras Nodal expression in one half suppresses neural differentiation across the interface. Anti-phospho-Smad3 reveals that the cells adjacent to cells expressing Nodal have nuclear immunoreactivity. We conclude Sp-Smad2/3 is a component of the Nodal signaling pathway in sea urchins and that Nodal diffuses short distances to suppress neural differentiation.
    Full-text · Article · Mar 2007 · Developmental Biology

Publication Stats

1k Citations
135.43 Total Impact Points


  • 2010-2015
    • University of Tsukuba
      Tsukuba, Ibaraki, Japan
  • 2008
    • National Institutes of Health
      • Section of Developmental Mechanisms
      Maryland, United States
  • 2006-2007
    • University of Victoria
      • • Department of Biology
      • • Department of Biochemistry and Microbiology
      Victoria, British Columbia, Canada
  • 2000-2004
    • Tohoku University
      • • Graduate School of Science
      • • Graduate School of Life Sciences
      Sendai, Kagoshima, Japan