Sumario:
The International Journal of Developmental Biology
Linking Development, Stem Cells and Cancer Research
Euskal Herriko Unibertsitateko Argitalpen Zerbitzua / Servicio Editorial de la Universidad del País Vasco / University of the Basque Country Press
Volume 57 - Number 5 (2013) Editor-in-Chief: Juan Aréchaga
MORE INFORMATION [Abstract - FullText / FullText Open Access]
ISSN: 0214-6282 / ISSN-e: 1696-3547 www.intjdevbiol.com
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CONTENTS + ABSTRACTS
Meeting Report
Symposium in honor of Ralph L. Brinster celebrating 50 years of scientific breakthroughs
Richard R. Behringer and Takashi Shinohara
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 333-339
Reviews
Lateral inhibition and neurogenesis: novel aspects in motion
Pau Formosa-Jordan, Marta Ibañes, Saúl Ares and José-María Frade
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 341-350
Sexual dimorphism in estrogen-induced synaptogenesis in the adult hippocampus
Nicola Brandt, Ricardo Vierk and Gabriele M. Rune
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 351-356
Original Articles
SMYD2 is induced during cell differentiation and participates in early development
Borja Sesé, Maria J. Barrero, Maria-Carme Fabregat, Veronika Sander and Juan Carlos Izpisua Belmonte
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 357-364
Trans-2-phenylcyclopropylamine regulates zebrafish lateral line neuromast development mediated by depression of LSD1 activity
Yingzi He, Huiqian Yu, Shan Sun, Yunfeng Wang, Liman Liu, Zhengyi Chenand Huawei Li
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 365-373
The Dictyostelium prestalk inducer DIF-1 directs phosphorylation of a bZIP transcription factor
Yoko Yamada, Yuzuru Kubohara, Haruhisa Kikuchi, Yoshiteru Oshima, Hong-Yu Wang, Susan Ross and Jeffrey G. Williams
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 375-381
Induction of intermediate mesoderm by retinoic acid receptor signaling from differentiating mouse embryonic stem cells
Shiho Oeda, Yohei Hayashi, Techuan Chan, Minoru Takasato, Yuko Aihara,Koji Okabayashi, Kiyoshi Ohnuma and Makoto Asashima
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 383-389
The Parahox gene Pdx1 is required to maintain positional identity in the adult foregut
Andrew M. Holland, Sonia Garcia, Gaetano Naselli, Raymond J. MacDonald and Leonard C. Harrison
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 391-398
Molecular signaling at the fusion stage of the mouse mandibular arch: involvement of insulin-like growth factor family
Kazuya Fujita, Yuji Taya, Yoshihito Shimazu, Takaaki Aoba and Yuuichi Soeno
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 399-406
Hippo signaling components, Mst1 and Mst2, act as a switch between self-renewal and differentiation in Xenopus hematopoietic and endothelial progenitors
Susumu Nejigane, Shuji Takahashi, Yoshikazu Haramoto, Tatsuo Michiue and Makoto Asashima
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 407-414
Unc-5/netrin-mediated axonal projection during larval serotonergic nervous system formation in the sea urchin, Hemicentrotus pulcherrimus
Kouki Abe, Tomoko Katow, Shioh Ooka and Hideki Katow
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 415-425
Calnexin is required for zebrafish posterior lateral line development
I-Chen Hung, Bor-Wei Cherng, Wen-Ming Hsu and Shyh-Jye Lee
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 427-438
Short Communication
Germes is involved in translocation of germ plasm during development of Xenopus primordial germ cells
Takeshi Yamaguchi, Ayaka Taguchi, Kenji Watanabe and Hidefumi Orii
EHU/UPV/UBC - The International Journal of Developmental Biology (2013) 57: 439-443
The International Journal of Developmental Biology
ISSN 1696-3547 (online) and 0214-6282 (print)
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ABSTRACTS:
Meeting Report
EHU/UPV/UBC - The International Journal of Developmental Biology 57: 333-339 (2013)
doi: 10.1387/ijdb.120248rb / © UBC Press (www.a360grados.net)
Symposium in honor of Ralph L. Brinster celebrating 50 years of scientific breakthroughs
Richard R. Behringer 1 and Takashi Shinohara 2
1 Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
2 Department of Molecular Gentics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Abstract: The Symposium speakers comprised a distinguished group of scientists from North America, Europe and Asia. The Keynote address was presented by Michael Brown, Nobel Laureate in Physiology or Medicine (1985), and a plenary lecture was presented by John Gurdon, who within the next months would receive the Nobel Prize in Physiology or Medicine (2012). The first lecture in the series was presented by Richard Palmiter, Ralph’s collaborator for more than 15 years, and he provided an overview of their work together followed by Richard’s subsequent exciting contributions in the area of neurobiology. Seventeen lectures were presented over the two-day Symposium by distinguished scientists, including several of Ralph’s former colleagues and students. The topics covered studies on germ cells, the germline, early embryos and their differentiation, as well as exciting and unpublished studies on stem cells and reprogramming. Many of the topics presented arose from foundation experiments in which Ralph participated, and these new developments indicate the dramatic progression of studies in this area. The Symposium program and the complete lectures can be found at the following link: www.vet.upenn.edu/BrinsterSymposium
Keywords: Cell Reprogramming, Animal Transgenesis, Germ Cell Research, Pluripotent Stem Cells
Reviews ----------------------------------------------------
EHU/UPV/UBC - The International Journal of Developmental Biology 57: 341-350 (2013)
doi: 10.1387/ijdb.120259jf / © UBC Press (www.a360grados.net)
Lateral inhibition and neurogenesis: novel aspects in motion
Pau Formosa-Jordan 1, Marta Ibañes 1, Saúl Ares 2,3 and José-María Frade 4
1 Department of Estructura i Constituents de la Matèria, Facultat de Física, Universitat de Barcelona, Barcelona
2 Logic of Genomic Systems Laboratory
3 Grupo Interdisciplinar de Sistemas Complejos (GISC), Spanish National Biotechnology Centre CNB-CSIC, Madrid
4 Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute, IC-CSIC, Madrid, Spain.
Abstract: Neuronal production in metazoans is tightly controlled by Delta/Notch-dependent signals regulating lateral inhibition. It is currently thought that lateral inhibition takes place in clusters of precursors with equal capacity to trigger and receive Notch-dependent inhibitory signals. However, this view neglects crucial dynamical aspects of the process. In this review, we discuss two of these dynamic factors, whose alterations yield dysfunctions in neurogenesis. First, precursors show variable neurogenic capacity as they go through the cell cycle. Second, differentiating precursors are in direct contact with non-neurogenic cells at the wavefront of expanding neurogenic domains. We discuss the mechanisms adopted by Metazoa to prevent these dysfunctions in the lateral inhibitory process, which include cell cycle synchronization occurring in the invertebrate neural epithelium and during primary neurogenesis in anamniotes, interkinetic nuclear movement in the vertebrate neuroepithelium and generalized Delta expression ahead of the neurogenic wavefront. The emerging concept is that lateral inhibition during neurogenesis occurs in dynamic clusters of precursors and requires specific mechanisms to avoid distortions resulting from the interaction between neurogenic and non-neurogenic precursors. The advance in visualizing Notch dynamics with real-time imaging at cellular and subcellular levels will notably contribute to our understanding of these novel “aspects of motion” in neurogenesis.
Keywords: notch, delta, cell cycle, interkinetic nuclear movement, neurogenic wavefront
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EHU/UPV/UBC - The International Journal of Developmental Biology 57: 351-356 (2013)
doi: 10.1387/ijdb.120217gr / © UBC Press (www.a360grados.net)
Sexual dimorphism in estrogen-induced synaptogenesis in the adult hippocampus
Nicola Brandt, Ricardo Vierk and Gabriele M. Rune
Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
Abstract: It has long been known that estradiol influences synaptic plasticity in the female hippocampus. The density of dendritic spines varies during the estrous cycle and correlates positively with varying levels of estradiol in serum. In accordance, ovariectomy results in a loss of spines that can be rescued by estradiol treatment in animals, suggesting that estradiol originating from the ovaries induces spine formation in the hippocampus. More recent studies point to a role of hippocampus-derived estradiol in synaptogenesis in the female hippocampus, rather than of estradiol of ovarian origin. In our studies, we have shown that inhibition of hippocampal estrogen synthesis results in spine synapse loss in female animals and, more importantly, also in ovariectomized animals. Surprisingly, inhibition of local estradiol synthesis had no effect on synapse formation in males, in spite of a similar capacity to synthesize estradiol in male and female hippocampal neurons. In females, neuro-sexual steroid production is promoted by hypothalamic, cyclic GnRH release and likely underlies the estrus cyclicity of spine synapse density in the hippocampus. As a result, peripheral serum concentrations of estradiol determine the amount of estradiol synthesis in the hippocampus. This paradigm may also be true in males. In support of this hypothesis, we found that the content of estradiol in hippocampal tissue is higher in female compared to that in male animals, with low levels of estradiol in serum and tonic and acyclical GnRH release. In summary, our data point to important sex-specific differences in sexual steroid-induced synaptogenesis.
Keywords: aromatase, estrogen, synaptogenesis, hippocampus, sexual dimorphism
Original Articles --------------------------------------------
EHU/UPV/UBC - The International Journal of Developmental Biology 57: 357-364 (2013)
doi: 10.1387/ijdb.130051ji / © UBC Press (www.a360grados.net)
SMYD2 is induced during cell differentiation and participates in early development
Borja Sesé 1, Maria J. Barrero 1, Maria-Carme Fabregat 1, Veronika Sander 1 and Juan Carlos Izpisua Belmonte 1,2
1 Center for Regenerative Medicine in Barcelona, Barcelona, Spain
2 Salk Institute for Biological Studies, La Jolla, CA, USA
Abstract: Histone modifying enzymes play critical roles in cell differentiation and development. In this study, we report that SMYD2 (SET and MYND domain containing protein 2), a histone lysine methyltransferase, is induced during human embryonic stem (ES) cell differentiation and it is preferentially expressed in somatic cells versus pluripotent cells. Knockdown of SMYD2 in human ES cells promotes the induction of endodermal markers during differentiation, while overexpression has opposite effects. In vivo experiments in zebrafish revealed that knockdown of smyd2a (a homologue gene of human SMYD2) causes developmental delay and aberrant tail formation, which is coincident with low expression of ntl and over induction Nodal-related genes during gastrulation. Taken together, these findings suggest that SMYD2 plays a critical role at early stages of development and in human ES cell differentiation.
Keywords: SMYD2, differentiation, development, stem cell, methyltransferase
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EHU/UPV/UBC - The International Journal of Developmental Biology 57: 365-373 (2013)
doi: 10.1387/ijdb.120227hl / © UBC Press (www.a360grados.net)
Trans-2-phenylcyclopropylamine regulates zebrafish lateral line neuromast development mediated by depression of LSD1 activity
Yingzi He 1,2, Huiqian Yu 2, Shan Sun 2, Yunfeng Wang 1, Liman Liu 1, Zhengyi Chen 3 and Huawei Li 1,2
1 Institutes of Biomedical Sciences of Fudan University, Shanghai, China
2 Department of Otolaryngology, Affiliated Eye and ENT hospital of Fudan University, Shanghai, China
3 Department of Otolaryngology and Program in Neuroscience, Harvard Medical School and Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA, USA
Abstract: The zebrafish mechanosensory lateral line (LL) is a model system for the study of hair cell development, survival and regeneration. Recently, histone modifications have attracted a considerable amount of interest because of their indispensable roles in various kinds of cellular processes including differentiation, proliferation, apoptosis and function. Lysine specific demethylase 1 (LSD1) is an important enzyme that regulates histone methylation. As a transcriptional regulator, this enzyme has broad functional activities and is involved in many biological processes. However, the effects of LSD1 on the early development of zebrafish sensory system have not been fully elucidated. Here, we have found that pharmacological inhibition of LSD1 with the monoamine oxidase (MAO) inhibitor trans-2-phenylcyclopropylamine (referred to as 2-PCPA) reduced the numbers of both sensory hair cells and supporting cells of neuromasts during zebrafish development. Our results showed that the treatment of zebrafish larvae with 2-PCPA caused accumulation of histone methylation and suppressed proliferation of neuromast cells. Finally, acridine orange staining assay demonstrated that 2-PCPA treatment at high concentrations induced an enhancement of cellular apoptosis within neuromasts. Taken together, these results indicate that LSD1 demethylase activity is required for neuromast development in zebrafish larvae.
Keywords: hair cell, LSD1, neuromast, trans-2-phenylcyclopropylamine, zebrafish
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EHU/UPV/UBC - The International Journal of Developmental Biology 57: 375-381 (2013)
doi: 10.1387/ijdb.130046jw / © UBC Press (www.a360grados.net)
The Dictyostelium prestalk inducer DIF-1 directs phosphorylation of a bZIP transcription factor
Yoko Yamada, Yuzuru Kubohara 1, Haruhisa Kikuchi 2, Yoshiteru Oshima 2, Hong-Yu Wang, Susan Ross and Jeffrey G. Williams
1 College of Life Sciences, Welcome Trust Biocentre, University of Dundee, UK
2 Department of Molecular and Cellular Biology, Institute for Molecular and Cellular Regulation, Gunma University, Japan
3 Laboratory of Natural Product Chemistry, Tohoku University Graduate School of Pharmaceutical Sciences, Aoba-yama, Aoba-ku, Sendai, Japan
Abstract: DIF-1, a chlorinated hexaphenone produced by developing Dictyostelium cells, induces prestalk differentiation. DimB is a bZIP transcription factor that accumulates in the nucleus upon exposure to DIF-1, where it directly activates transcription of DIF-responsive genes. The signaling steps upstream of DimB and downstream of DIF-1 are entirely unknown. Analysis by mass spectrometry shows that incubation with DIF-1 rapidly stimulates phosphorylation at several sites in DimB. We characterize the most highly responsive site, S590, which is located very close to the C terminus. A point mutation in this site, S590A, does not inhibit DimB nuclear accumulation in response to DIF. However, this seems likely to reflect functional redundancy with other sites; because a panel of chemical variants on the structure of DIF-1 show a correlation between their potencies as inducers of DimB nuclear accumulation and their potencies as inducers of phosphorylation at S590. Furthermore, the S590A mutant is fully active in mutant rescue of a dimB null strain, arguing against an alternative role in transcriptional activation of target genes. We conclude that i) DIF-1 directs phosphorylation at S590, ii) although it is not essential for nuclear accumulation in response to DIF-1 correlative evidence, based upon a panel of DIF-1 related molecules, suggests that this modification may play a redundant role in the process. iii) We also present evidence that the kinase activity, which phosphorylates S590, is non-nuclear and that this signalling pathway is, in part at least, independent of the DIF-regulated STATc activation pathway.
Keywords: Dictyostelium, DimB: DIF-1, activation, kinase
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EHU/UPV/UBC - The International Journal of Developmental Biology 57: 383-389 (2013)
doi: 10.1387/ijdb.130058ma / © UBC Press (www.a360grados.net)
Induction of intermediate mesoderm by retinoic acid receptor signaling from differentiating mouse embryonic stem cells
Shiho Oeda 1, Yohei Hayashi 1, Techuan Chan 1, Minoru Takasato 1, Yuko Aihara 1, Koji Okabayashi 1, Kiyoshi Ohnuma 1 and Makoto Asashima 1,2
1 Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo
2 Research Center for Stem Cell Engineering, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan.
Abstract: Renal lineages including kidney are derived from intermediate mesoderm, which are differentiated from a subset of caudal undifferentiated mesoderm. The inductive mechanisms of mammalian intermediate mesoderm and renal lineages are still poorly understood. Mouse embryonic stem cells (mESCs) can be a good in vitro model to reconstitute the developmental pathway of renal lineages and to analyze the mechanisms of the sequential differentiation. We examined the effects of Activin A and retinoic acid (RA) on the induction of intermediate mesoderm from mESCs under defined, serum-free, adherent, monolayer culture conditions. We measured the expression level of intermediate mesodermal marker genes and examined the developmental potential of the differentiated cells into kidney using an ex vivo transplantation assay. Adding Activin A followed by RA to mESC cultures induced the expression of marker genes and proteins for intermediate mesoderm, odd-skipped related 1 (Osr1) and Wilm’s Tumor 1 (Wt1). These differentiated cells integrated into laminin-positive tubular cells and Pax2-positive renal cells in cultured embryonic kidney explants. We demonstrated that intermediate mesodermal marker expression was also induced by RA receptor (RAR) agonist, but not by retinoid X receptor (RXR) agonists. Furthermore, the expression of these markers was decreased by RAR antagonists. We directed the differentiation of mESCs into intermediate mesoderm using Activin A and RA and revealed the role of RAR signaling in this differentiation. These methods and findings will improve our understanding of renal lineage development and could contribute to the regenerative medicine of kidney.
Keywords: kidney, Activin A, odd-skipped related 1, Pax 2, Wilm’s tumor 1
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EHU/UPV/UBC - The International Journal of Developmental Biology 57: 391-398 (2013)
doi: 10.1387/ijdb.120048ah / © UBC Press (www.a360grados.net)
The Parahox gene Pdx1 is required to maintain positional identity in the adult foregut
Andrew M. Holland 1, Sonia Garcia 1, Gaetano Naselli 2, Raymond J. MacDonald 3 and Leonard C. Harrison 2
1 Monash Immunology and Stem Cell Laboratories, Monash University, Clayton, Victoria, Australia
2 Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
3 University of Texas Southwestern Medical Center, Dallas, TX, USA
Abstract: The homeobox gene Pdx1 is a key regulator of pancreas and foregut development. Loss of Pdx1 expression results in pancreas agenesis and impaired development of the gastro-duodenal domain including Brunner’s glands. We previously demonstrated a key role for Pdx1 in maintaining the integrity and function of insulin-secreting beta cells in the adult pancreas. In the present study, we aimed to determine if expression of Pdx1 is required to maintain the cellular identity of the gastro-duodenal domain in adult mice. Immunohistological studies were performed in a mouse model in which expression of Pdx1 was conditionally repressed with the doxycycline-responsive tetracycline transactivator system. Mice in which Pdx1 was chronically repressed developed hamartomas in the gastro-duodenal domain. These lesions appeared to arise from ectopic foci of anteriorized cells, consistent with a localised anterior homeotic shift. They emerge with the intercalation of tissue between the anteriorized and normal domains and appear strikingly similar to lesions in the colon of mice heterozygous for another Parahox gene, Cdx2. Continuing expression of Pdx1 into adult life is required to maintain regional cellular identity in the adult foregut, specifically at the gastro-duodenal boundary. Loss of Pdx1 expression leads to anterior transformation and intercalary regeneration of ectopic tissue. We propose a model in which the posterior dominance of classical Hox genes is mirrored by the Parahox genes, providing further evidence of the functional conservation of the Parahox genes. These findings may have implications for further understanding the molecular basis of gastro-duodenal metaplasia and gastro-intestinal transformations such as Barrett’s esophagus.
Keywords: Pdx1, Cdx2, parahox, Brunner’s gland, tTA
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EHU/UPV/UBC - The International Journal of Developmental Biology 57: 399-406 (2013)
doi: 10.1387/ijdb.120110ys / © UBC Press (www.a360grados.net)
Molecular signaling at the fusion stage of the mouse mandibular arch: involvement of insulin-like growth factor family
Kazuya Fujita, Yuji Taya, Yoshihito Shimazu, Takaaki Aoba and Yuuichi Soeno
Department of Pathology, School of Life Dentistry at Tokyo, The Nippon Dental University, Tokyo, Japan
Abstract: Fusion of the branchial arch derivatives is a crucial event in the development of the craniofacial architecture. Here, we surveyed the gene expression profile, focusing on the fusion process of the mouse mandibular arch at embryonic day 10.5. In order to identify the genes that are relevant to the midline fusion process, we subdivided the mandibular arch medially and laterally, and determined gene expression using microarray and real-time quantitative PCR. By comparing the transcriptomes of the medial and lateral regions, 362 genes were identified as medial region-specific genes, while 346 genes were designated lateral region-specific. Taken with Gene Ontology analysis, KEGG pathways and Ingenuity Pathway Analysis (IPA), a survey of the medial region-specific gene dataset revealed significant expression of the insulin-like growth factor (Igf) family as well as other growth factor families (Hh, Wnt, Tgf-Bmp, Mapk-Fgf and Notch). To determine the discrete expression pattern of Igf family genes in the medial region, we microdissected the medial part of the mandibular arch into epithelial and mesenchymal components, and found that Igf1 was highly expressed in the mesenchyme, Igf2 and Igf1r were expressed in both the midline epithelium and surrounding mesenchyme, and Igfbp5 was highly expressed in the epithelium. Immunohistochemical findings validated the regional Igf gene expression profiles. Our observations suggest that in the “merging” fusion of the mandibular arch, the Igf cascade may contribute to generation of proliferation pressure from the mesenchyme and preservation of epithelial phenotypes and architecture during mesenchymal confluence.
Keywords: mandibular fusion, transcriptome, protein localization, midline epithelium, mesenchyme
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EHU/UPV/UBC - The International Journal of Developmental Biology 57: 407-414 (2013)
doi: 10.1387/ijdb.130010st / © UBC Press (www.a360grados.net)
Hippo signaling components, Mst1 and Mst2, act as a switch between self-renewal and differentiation in Xenopus hematopoietic and endothelial progenitors
Susumu Nejigane 1, Shuji Takahashi 2, Yoshikazu Haramoto 3, Tatsuo Michiue 1 and Makoto Asashima 3
1 Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, Japan
2 Komaba Organization for Educational Excellence, College of Arts and Sciences, The University of Tokyo, Japan
3 Research Center for Stem Cell Engineering (SCRC), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan
Abstract: Hippo signaling is a conserved pathway that regulates cell proliferation and organ size control. Mst1 and Mst2 were identified as homologs of hippo and as core kinases of the Hippo pathway in mammals. Here, we have characterized the role of Mst1 and Mst2 during Xenopus primitive hematopoiesis. We showed that Mst1 and Mst2 were strongly expressed in the Xenopus ventral blood island, where primitive hematopoiesis is initiated. Loss-of-function analysis of Mst1/2 revealed morphogenetic defects, including short axis, smaller eyes and abnormal epidermis, and decreased phosphorylation of Yap. Mst1/2 morphants did not exhibit any change in the expression of hematopoietic and endothelial progenitor markers in early hematopoietic development. In addition, we have shown that such progenitor markers were continuously expressed through to the late hematopoietic development stage. As a result, the expression of erythroid, myeloid and endothelial differentiation markers were decreased in Mst1/2 morphants. Our results indicate that Mst1/2 act as a differentiation switch in Xenopus hematopoietc and endothelial progenitors.
Keywords: Hippo signaling, Mst, Yap, primitive hematopoiesis, Xenopus tropicalis
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EHU/UPV/UBC - The International Journal of Developmental Biology 57: 415-425 (2013)
doi: 10.1387/ijdb.120256hk / © UBC Press (www.a360grados.net)
Unc-5/netrin-mediated axonal projection during larval serotonergic nervous system formation in the sea urchin, Hemicentrotus pulcherrimus
Kouki Abe, Tomoko Katow, Shioh Ooka and Hideki Katow
Research Center for Marine Biology, Tohoku University, Asamushi, Aomori, Japan
Abstract: The molecular structure and role of two splice-isoforms of Unc-5 (Hp-Unc-5v1 and v2) in Unc-5/netrin interaction during serotonergic axonal projection were elucidated in this study. Hp-Unc-5v1 was found to be comprised of two immunoglobulin-like domains, two thrombospondin domains in the extracellular region, and ZU-5, DB, and Death domains in the cytoplasmic region, whereas Hp-Unc-5v2 lacked one thrombospondin domain, the transmembrane domain, and all cytoplasmic domains. Hp-Unc-5v1 was transcribed in unfertilized eggs, which continued until the 3-day post-fertilization (-dpf) 2-arm pluteus stage, but was suspended at the mesenchyme blastula stage (mB1), whereas Hp-Unc-5v2 was not transcribed in unfertilized eggs, but was from after fertilization to the same developmental stage of mB1 as Hp-Unc-5v1. Relative accumulation of transcripts of both splice-isoforms peaked at the prism stage and declined thereafter, and they were localized at the vegetal pole region of early gastrulae, around the blastopore in mid- to late gastrulae, at fore- and mid-gut regions and on the basal side of dorsal ectoderm in 28-hour post-fertilization prism larvae, and within axons at and after the 2-dpf pluteus stage. Hp-Unc-5v2:GFP was detected in the entire serotonergic cell body and extracellularly on the basal surface of oral ectoderm in 2-dpf plutei and exclusively within axons in 4-dpf plutei. Overexpression of Hp-Unc-5v2 resulted in decreased axonal projection in plutei. Knockdown of Hp-Unc-5v1 by morpholino antisense oligonucleotide resulted in severe deficiency of axonal projection. Interference of Unc-5/netrin interaction using an exogenous synthetic SQDFGKTW peptide from the VI domain in Hp-netrin inhibited axonal projection and larval swimming.
Keywords: axonal projection, Unc-5 variant, netrin, serotonergic axon, sea urchin larvae
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EHU/UPV/UBC - The International Journal of Developmental Biology 57: 427-438 (2013)
doi: 10.1387/ijdb.120166sl / © UBC Press (www.a360grados.net)
Calnexin is required for zebrafish posterior lateral line development
I-Chen Hung 1, Bor-Wei Cherng 1, Wen-Ming Hsu 6,4, and Shyh-Jye Lee 1,2,3,4,5
1 Institute of Zoology , 2 Department of Life Science, 3 Center for Biotechnology, 4 Center for Systems Biology, 5 Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei
and 6Department of Surgery, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan, R.O.C.
Abstract: The lateral line is a mechanosensory system in fish and amphibians to detect local water flow and pressure. Development of the posterior lateral line (PLL) originates from the migrating PLL primordium (PLLP). The PLLP deposits neuromasts on the trunk during migration to the tail. Molecular dissection revealed that PLL development is associated with genes mediating cell adhesion, morphogenesis, neurogenesis and development, but the regulatory signaling network is far from completion. To further investigate candidate regulatory genes for lateral line development, we found using whole-mount in situ hybridization that calnexin, an endoplasmic reticular (ER) calcium-binding protein gene, is expressed in PLL neuromasts. Knockdown of calnexin using antisense morpholino oligonucleotides resulted in a dose-dependent reduction in neuromasts and hair cells of the PLL. Using a transgenic claudin b:gfp line, we observed a notably reduced PLLP size, but no significant migration defect in calnexin morphants. Finally, we discovered that the reduced PLLP is associated with a reduction in cell proliferation and an increase in ER stress-dependent apoptosis. These results suggest that calnexin is essential for neuromast formation during lateral line development in the zebrafish.
Keywords: zebrafish, calnexin, lateral line, neuromast, ER stress
Short Communication -------------------------------------
EHU/UPV/UBC - The International Journal of Developmental Biology 57: 439-443 (2013)
doi: 10.1387/ijdb.120215ty / © UBC Press (www.a360grados.net)
Germes is involved in translocation of germ plasm during development of Xenopus primordial germ cells
Takeshi Yamaguchi, Ayaka Taguchi, Kenji Watanabe and Hidefumi Orii
Department of Life Science, University of Hyogo, Kamigori, Akou-gun, Hyogo, Japan
Abstract: Germes mRNA and protein are components of the germ plasm in Xenopus laevis. Previously, based on phenotypic observations of tailbud embryos expressing intact and mutant Germes, it was suggested that Germes is involved in the organization of germ plasm (Berekelya et al., 2007). Recently, to observe the germ plasm in a living embryo, we generated transgenic Xenopus expressing EGFP fused with a mitochondrial targeting signal, because germ plasm is enriched with mitochondria (Taguchi et al., 2012). Using this transgenic Xenopus, we demonstrate that Germes plays an essential role in the translocation of germ plasm from the cortex to the perinuclear region in primordial germ cells during early gastrulation.
Keywords: PGC, germline, DEADSouth, mitochondrial cloud, chromatoid body
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