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The evolution of neurosensation provides opportunities and constraints for phenotypic plasticity. Sci Rep 2022; 12:11883. [PMID: 35831328 PMCID: PMC9279360 DOI: 10.1038/s41598-022-15583-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 06/27/2022] [Indexed: 11/08/2022] Open
Abstract
Phenotypic plasticity is widely regarded as important for enabling species resilience to environmental change and for species evolution. However, insight into the complex mechanisms by which phenotypic plasticity evolves in nature is limited by our ability to reconstruct evolutionary histories of plasticity. By using part of the molecular mechanism, we were able to trace the evolution of pre-feeding phenotypic plasticity across the class Echinoidea and identify the origin of plasticity at the base of the regular urchins. The neurosensory foundation for plasticity was ancestral within the echinoids. However, coincident development of the plastic trait and the neurosensory system was not achieved until the regular urchins, likely due to pleiotropic effects and linkages between the two colocalized systems. Plasticity continues to evolve within the urchins with numerous instances of losses associated with loss of sensory abilities and neurons, consistent with a cost of maintaining these capabilities. Thus, evidence was found for the neurosensory system providing opportunities and constraints to the evolution of phenotypic plasticity.
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2
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Molina MD, Gache C, Lepage T. Expression of exogenous mRNAs to study gene function in echinoderm embryos. Methods Cell Biol 2019; 151:239-282. [PMID: 30948011 DOI: 10.1016/bs.mcb.2018.10.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
With the completion of the genome sequencing projects, a new challenge for developmental biologists is to assign a function to the thousands of genes identified. Expression of exogenous mRNAs is a powerful, versatile and rapid technique that can be used to study gene function during development of the sea urchin. This chapter describes how this technique can be used to analyze gene function in echinoderm embryos, how it can be combined with cell transplantation to perform mosaic analysis and how it can be applied to identify downstream targets genes of transcription factors and signaling pathways. We describe specific examples of the use of overexpression of mRNA to analyze gene function, mention the benefits and current limitations of the technique and emphasize the importance of using different controls to assess the specificity of the effects observed. Finally, this chapter details the different steps, vectors and protocols for in vitro production of mRNA and phenotypic analysis.
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Affiliation(s)
| | - Christian Gache
- Université Pierre et Marie Curie, Observatoire Océanologique de Villefranche sur Mer, UMR7009 CNRS, Paris, France
| | - Thierry Lepage
- Université Côte d'Azur, CNRS, INSERM, iBV, Nice, France.
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3
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Slota LA, McClay DR. Identification of neural transcription factors required for the differentiation of three neuronal subtypes in the sea urchin embryo. Dev Biol 2018; 435:138-149. [PMID: 29331498 PMCID: PMC5837949 DOI: 10.1016/j.ydbio.2017.12.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 12/20/2017] [Indexed: 12/30/2022]
Abstract
Correct patterning of the nervous system is essential for an organism's survival and complex behavior. Embryologists have used the sea urchin as a model for decades, but our understanding of sea urchin nervous system patterning is incomplete. Previous histochemical studies identified multiple neurotransmitters in the pluteus larvae of several sea urchin species. However, little is known about how, where and when neural subtypes are differentially specified during development. Here, we examine the molecular mechanisms of neuronal subtype specification in 3 distinct neural subtypes in the Lytechinus variegatus larva. We show that these subtypes are specified through Delta/Notch signaling and identify a different transcription factor required for the development of each neural subtype. Our results show achaete-scute and neurogenin are proneural for the serotonergic neurons of the apical organ and cholinergic neurons of the ciliary band, respectively. We also show that orthopedia is not proneural but is necessary for the differentiation of the cholinergic/catecholaminergic postoral neurons. Interestingly, these transcription factors are used similarly during vertebrate neurogenesis. We believe this study is a starting point for building a neural gene regulatory network in the sea urchin and for finding conserved deuterostome neurogenic mechanisms.
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Affiliation(s)
- Leslie A Slota
- Department of Biology, Duke University, Durham, NC 27708, United States
| | - David R McClay
- Department of Biology, Duke University, Durham, NC 27708, United States.
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4
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Hinman VF, Burke RD. Embryonic neurogenesis in echinoderms. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2018; 7:e316. [PMID: 29470839 DOI: 10.1002/wdev.316] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 12/20/2017] [Accepted: 12/21/2017] [Indexed: 01/09/2023]
Abstract
The phylogenetic position of echinoderms is well suited to revealing shared features of deuterostomes that distinguish them from other bilaterians. Although echinoderm neurobiology remains understudied, genomic resources, molecular methods, and systems approaches have enabled progress in understanding mechanisms of embryonic neurogenesis. Even though the morphology of echinoderm larvae is diverse, larval nervous systems, which arise during gastrulation, have numerous similarities in their organization. Diverse neural subtypes and specialized sensory neurons have been identified and details of neuroanatomy using neuron-specific labels provide hypotheses for neural function. The early patterning of ectoderm and specification of axes has been well studied in several species and underlying gene regulatory networks have been established. The cells giving rise to central and peripheral neural components have been identified in urchins and sea stars. Neurogenesis includes typical metazoan features of asymmetric division of neural progenitors and in some cases limited proliferation of neural precursors. Delta/Notch signaling has been identified as having critical roles in regulating neural patterning and differentiation. Several transcription factors functioning in pro-neural phases of specification, neural differentiation, and sub-type specification have been identified and structural or functional components of neurons are used as differentiation markers. Several methods for altering expression in embryos have revealed aspects of a regulatory hierarchy of transcription factors in neurogenesis. Interfacing neurogenic gene regulatory networks to the networks regulating ectodermal domains and identifying the spatial and temporal inputs that pattern the larval nervous system is a major challenge that will contribute substantially to our understanding of the evolution of metazoan nervous systems. This article is categorized under: Comparative Development and Evolution > Model Systems Comparative Development and Evolution > Body Plan Evolution Early Embryonic Development > Gastrulation and Neurulation.
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Affiliation(s)
- Veronica F Hinman
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Robert D Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, Canada
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5
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Anello L, Cavalieri V, Di Bernardo M. Developmental effects of the protein kinase inhibitor kenpaullone on the sea urchin embryo. Comp Biochem Physiol C Toxicol Pharmacol 2018; 204:36-44. [PMID: 29128602 DOI: 10.1016/j.cbpc.2017.11.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 01/06/2023]
Abstract
The selection and validation of bioactive compounds require multiple approaches, including in-depth analyses of their biological activity in a whole-animal context. We exploited the sea urchin embryo in a rapid, medium-scale range screening to test the effects of the small synthetic kinase inhibitor kenpaullone. We show that sea urchin embryos specifically respond to this molecule depending on both dose and timing of administration. Phenotypic effects of kenpaullone are not immediately visible, since this molecule affects neither the fertilization nor the spatial arrangement of blastomeres at early developmental stages. Nevertheless, kenpaullone exposure from the beginning of embryogenesis profoundly perturbs specification, detachment from the epithelium, and migration of the primary mesenchyme cells, thus affecting the whole embryonic epithelial mesenchymal transition process. Our results reaffirm the sea urchin embryo as an excellent and sensitive in vivo system, which provides straightforward and rapid response to external stimuli.
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Affiliation(s)
- Letizia Anello
- Istituto di Biomedicina e Immunologia Molecolare "A. Monroy", Consiglio Nazionale delle Ricerche, Via Ugo La Malfa 153, 90146 Palermo, Italy
| | - Vincenzo Cavalieri
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche (STEBICEF), Università di Palermo, Viale delle Scienze Edificio 16, 90128 Palermo, Italy; Advanced Technologies Network (ATeN) Center, University of Palermo, Viale delle Scienze Edificio 18, 90128 Palermo, Italy
| | - Maria Di Bernardo
- Istituto di Biomedicina e Immunologia Molecolare "A. Monroy", Consiglio Nazionale delle Ricerche, Via Ugo La Malfa 153, 90146 Palermo, Italy.
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6
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Piacentino ML, Chung O, Ramachandran J, Zuch DT, Yu J, Conaway EA, Reyna AE, Bradham CA. Zygotic LvBMP5-8 is required for skeletal patterning and for left–right but not dorsal–ventral specification in the sea urchin embryo. Dev Biol 2016; 412:44-56. [DOI: 10.1016/j.ydbio.2016.02.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 01/31/2016] [Accepted: 02/18/2016] [Indexed: 01/25/2023]
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7
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Morino Y, Koga H, Wada H. The conserved genetic background for pluteus arm development in brittle stars and sea urchin. Evol Dev 2016; 18:89-95. [DOI: 10.1111/ede.12174] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Yoshiaki Morino
- Graduate School of Life and Environmental Sciences; University of Tsukuba; Tsukuba Ibaraki 305-8572 Japan
| | - Hiroyuki Koga
- Graduate School of Life and Environmental Sciences; University of Tsukuba; Tsukuba Ibaraki 305-8572 Japan
| | - Hiroshi Wada
- Graduate School of Life and Environmental Sciences; University of Tsukuba; Tsukuba Ibaraki 305-8572 Japan
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8
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Piacentino ML, Zuch DT, Fishman J, Rose S, Speranza EE, Li C, Yu J, Chung O, Ramachandran J, Ferrell P, Patel V, Reyna A, Hameeduddin H, Chaves J, Hewitt FB, Bardot E, Lee D, Core AB, Hogan JD, Keenan JL, Luo L, Coulombe-Huntington J, Blute TA, Oleinik E, Ibn-Salem J, Poustka AJ, Bradham CA. RNA-Seq identifies SPGs as a ventral skeletal patterning cue in sea urchins. Development 2016; 143:703-14. [PMID: 26755701 DOI: 10.1242/dev.129312] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 01/05/2016] [Indexed: 12/12/2022]
Abstract
The sea urchin larval skeleton offers a simple model for formation of developmental patterns. The calcium carbonate skeleton is secreted by primary mesenchyme cells (PMCs) in response to largely unknown patterning cues expressed by the ectoderm. To discover novel ectodermal cues, we performed an unbiased RNA-Seq-based screen and functionally tested candidates; we thereby identified several novel skeletal patterning cues. Among these, we show that SLC26a2/7 is a ventrally expressed sulfate transporter that promotes a ventral accumulation of sulfated proteoglycans, which is required for ventral PMC positioning and skeletal patterning. We show that the effects of SLC perturbation are mimicked by manipulation of either external sulfate levels or proteoglycan sulfation. These results identify novel skeletal patterning genes and demonstrate that ventral proteoglycan sulfation serves as a positional cue for sea urchin skeletal patterning.
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Affiliation(s)
- Michael L Piacentino
- Department of Biology, Boston University, Boston, MA 02215, USA Program in Molecular Biology, Cell Biology and Biochemistry, Boston University, Boston, MA 02215, USA
| | - Daniel T Zuch
- Department of Biology, Boston University, Boston, MA 02215, USA Program in Molecular Biology, Cell Biology and Biochemistry, Boston University, Boston, MA 02215, USA
| | - Julie Fishman
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Sviatlana Rose
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Emily E Speranza
- Program in Bioinformatics, Boston University, Boston, MA 02215, USA
| | - Christy Li
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Jia Yu
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Oliver Chung
- Department of Biology, Boston University, Boston, MA 02215, USA
| | | | - Patrick Ferrell
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Vijeta Patel
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Arlene Reyna
- Department of Biology, Boston University, Boston, MA 02215, USA
| | | | - James Chaves
- Department of Biology, Boston University, Boston, MA 02215, USA
| | | | - Evan Bardot
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - David Lee
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Amanda B Core
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - John D Hogan
- Program in Bioinformatics, Boston University, Boston, MA 02215, USA
| | - Jessica L Keenan
- Program in Bioinformatics, Boston University, Boston, MA 02215, USA
| | - Lingqi Luo
- Program in Bioinformatics, Boston University, Boston, MA 02215, USA
| | | | - Todd A Blute
- Department of Biology, Boston University, Boston, MA 02215, USA Proteomics and Imaging Core Facility, Boston University, Boston, MA 02215, USA
| | - Ekaterina Oleinik
- Scientific Computing and Visualization Group, Boston University, Boston, MA 02215 USA
| | - Jonas Ibn-Salem
- Max-Planck Institute for Molecular Genetics, Evolution and Development Group, Ihnestrasse 73, Berlin 14195, Germany
| | - Albert J Poustka
- Max-Planck Institute for Molecular Genetics, Evolution and Development Group, Ihnestrasse 73, Berlin 14195, Germany Dahlem Center for Genome Research and Medical Systems Biology, Environmental and Phylogenomics Group, Fabeckstraße 60-62, Berlin 14195, Germany
| | - Cynthia A Bradham
- Department of Biology, Boston University, Boston, MA 02215, USA Program in Molecular Biology, Cell Biology and Biochemistry, Boston University, Boston, MA 02215, USA Program in Bioinformatics, Boston University, Boston, MA 02215, USA
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9
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Cavalieri V, Spinelli G. Ectopic hbox12 Expression Evoked by Histone Deacetylase Inhibition Disrupts Axial Specification of the Sea Urchin Embryo. PLoS One 2015; 10:e0143860. [PMID: 26618749 PMCID: PMC4664418 DOI: 10.1371/journal.pone.0143860] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 11/09/2015] [Indexed: 12/26/2022] Open
Abstract
Dorsal/ventral patterning of the sea urchin embryo depends upon the establishment of a Nodal-expressing ventral organizer. Recently, we showed that spatial positioning of this organizer relies on the dorsal-specific transcription of the Hbox12 repressor. Building on these findings, we determined the influence of the epigenetic milieu on the expression of hbox12 and nodal genes. We find that Trichostatin-A, a potent and selective histone-deacetylases inhibitor, induces histone hyperacetylation in hbox12 chromatin, evoking broad ectopic expression of the gene. Transcription of nodal concomitantly drops, prejudicing dorsal/ventral polarity of the resulting larvae. Remarkably, impairing hbox12 function, either in a spatially-restricted sector or in the whole embryo, specifically rescues nodal transcription in Trichostatin-A-treated larvae. Beyond strengthen the notion that nodal expression is not allowed in the presence of functional Hbox12 in the same cells, these results highlight a critical role of histone deacetylases in regulating the spatial expression of hbox12.
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Affiliation(s)
- Vincenzo Cavalieri
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Italy
- Mediterranean Center for Human Health Advanced Biotechnologies (CHAB), University of Palermo, Italy
- * E-mail: (VC); (GS)
| | - Giovanni Spinelli
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Italy
- * E-mail: (VC); (GS)
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10
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Piacentino ML, Ramachandran J, Bradham CA. Late Alk4/5/7 signaling is required for anterior skeletal patterning in sea urchin embryos. Development 2015; 142:943-52. [PMID: 25633352 DOI: 10.1242/dev.114322] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Skeletal patterning in the sea urchin embryo requires a conversation between the skeletogenic primary mesenchyme cells (PMCs) and the overlying pattern-dictating ectoderm; however, our understanding of the molecular basis for this process remains incomplete. Here, we show that TGF-β-receptor signaling is required during gastrulation to pattern the anterior skeleton. To block TGF-β signaling, we used SB431542 (SB43), a specific inhibitor of the TGF-β type I receptor Alk4/5/7. Treatment with SB43 during gastrulation blocks anterior PMC positioning and the formation of the anterior skeleton, but does not perturb general ectoderm specification or development. This is the first example of a signaling event required for patterning of a specific part of the skeleton. Alk4/5/7 inhibition does not prevent the formation of a mouth, although SB43-treated plutei display reduced feeding ability, presumably due to the loss of the structural support for the mouth conferred by the anterior skeleton. Both Univin and Nodal are potential ligands for Alk4/5/7; however, Nodal is unilaterally expressed on only the right side, whereas Univin is bilaterally expressed in the ectoderm adjacent to the anterior skeleton during the relevant time period. Our results demonstrate that Univin is both necessary and sufficient for secondary skeletal development in a control background, consistent with the hypothesis that Univin is a relevant Alk4/5/7 ligand for anterior skeletal patterning. Taken together, our data demonstrate that Alk4/5/7 signaling during gastrulation is required to direct PMCs to the oral hood, and suggest that Univin is a relevant ligand for this signaling event.
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Affiliation(s)
- Michael L Piacentino
- Department of Biology, Boston University, Boston, MA 02215, USA Program in Molecular Biology, Cell Biology and Biochemistry, Boston University, Boston, MA 02215, USA
| | | | - Cynthia A Bradham
- Department of Biology, Boston University, Boston, MA 02215, USA Program in Molecular Biology, Cell Biology and Biochemistry, Boston University, Boston, MA 02215, USA Program in Bioinformatics, Boston University, Boston, MA 02215, USA
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11
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Cavalieri V, Spinelli G. Early asymmetric cues triggering the dorsal/ventral gene regulatory network of the sea urchin embryo. eLife 2014; 3:e04664. [PMID: 25457050 PMCID: PMC4273433 DOI: 10.7554/elife.04664] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 12/01/2014] [Indexed: 12/16/2022] Open
Abstract
Dorsal/ventral (DV) patterning of the sea urchin embryo relies on a ventrally-localized organizer expressing Nodal, a pivotal regulator of the DV gene regulatory network. However, the inceptive mechanisms imposing the symmetry-breaking are incompletely understood. In Paracentrotus lividus, the Hbox12 homeodomain-containing repressor is expressed by prospective dorsal cells, spatially facing and preceding the onset of nodal transcription. We report that Hbox12 misexpression provokes DV abnormalities, attenuating nodal and nodal-dependent transcription. Reciprocally, impairing hbox12 function disrupts DV polarity by allowing ectopic expression of nodal. Clonal loss-of-function, inflicted by blastomere transplantation or gene-transfer assays, highlights that DV polarization requires Hbox12 action in dorsal cells. Remarkably, the localized knock-down of nodal restores DV polarity of embryos lacking hbox12 function. Finally, we show that hbox12 is a dorsal-specific negative modulator of the p38-MAPK activity, which is required for nodal expression. Altogether, our results suggest that Hbox12 function is essential for proper positioning of the DV organizer.
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Affiliation(s)
- Vincenzo Cavalieri
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Palermo, Italy
| | - Giovanni Spinelli
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, Palermo, Italy
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12
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Adomako-Ankomah A, Ettensohn CA. Growth factors and early mesoderm morphogenesis: insights from the sea urchin embryo. Genesis 2014; 52:158-72. [PMID: 24515750 DOI: 10.1002/dvg.22746] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 01/24/2014] [Accepted: 02/05/2014] [Indexed: 12/16/2022]
Abstract
The early morphogenesis of the mesoderm is critically important in establishing the body plan of the embryo. Recent research has led to a better understanding of the mechanisms that underlie this process, and growth factor signaling pathways have emerged as key regulators of the directional movements of mesoderm cells during gastrulation. In this review, we undertake a comparative analysis of the various essential functions of growth factor signaling pathways in regulating early mesoderm morphogenesis, with an emphasis on recent advances in the sea urchin embryo. We focus on the roles of the vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) pathways in the migration of primary mesenchyme cells and the formation of the embryonic endoskeleton. We compare the functions of VEGF and FGF in sea urchins with the roles that these and other growth factors play in regulating mesoderm migration during gastrulation in Drosophila and vertebrates.
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13
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McIntyre DC, Lyons DC, Martik M, McClay DR. Branching out: origins of the sea urchin larval skeleton in development and evolution. Genesis 2014; 52:173-85. [PMID: 24549853 PMCID: PMC3990003 DOI: 10.1002/dvg.22756] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 02/14/2014] [Accepted: 02/14/2014] [Indexed: 11/08/2022]
Abstract
It is a challenge to understand how the information encoded in DNA is used to build a three-dimensional structure. To explore how this works the assembly of a relatively simple skeleton has been examined at multiple control levels. The skeleton of the sea urchin embryo consists of a number of calcite rods produced by 64 skeletogenic cells. The ectoderm supplies spatial cues for patterning, essentially telling the skeletogenic cells where to position themselves and providing the factors for skeletal growth. Here, we describe the information known about how this works. First the ectoderm must be patterned so that the signaling cues are released from precise positions. The skeletogenic cells respond by initiating skeletogenesis immediately beneath two regions (one on the right and the other on the left side). Growth of the skeletal rods requires additional signaling from defined ectodermal locations, and the skeletogenic cells respond to produce a membrane-bound template in which the calcite crystal grows. Important in this process are three signals, fibroblast growth factor, vascular endothelial growth factor, and Wnt5. Each is necessary for explicit tasks in skeleton production.
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Affiliation(s)
| | | | - Megan Martik
- Department of Biology, Duke University, Durham, NC
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14
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Cavalieri V, Melfi R, Spinelli G. The Compass-like locus, exclusive to the Ambulacrarians, encodes a chromatin insulator binding protein in the sea urchin embryo. PLoS Genet 2013; 9:e1003847. [PMID: 24086165 PMCID: PMC3784565 DOI: 10.1371/journal.pgen.1003847] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 08/16/2013] [Indexed: 11/18/2022] Open
Abstract
Chromatin insulators are eukaryotic genome elements that upon binding of specific proteins display barrier and/or enhancer-blocking activity. Although several insulators have been described throughout various metazoans, much less is known about proteins that mediate their functions. This article deals with the identification and functional characterization in Paracentrotus lividus of COMPASS-like (CMPl), a novel echinoderm insulator binding protein. Phylogenetic analysis shows that the CMPl factor, encoded by the alternative spliced Cmp/Cmpl transcript, is the founder of a novel ambulacrarian-specific family of Homeodomain proteins containing the Compass domain. Specific association of CMPl with the boxB cis-element of the sns5 chromatin insulator is demonstrated by using a yeast one-hybrid system, and further corroborated by ChIP-qPCR and trans-activation assays in developing sea urchin embryos. The sns5 insulator lies within the early histone gene cluster, basically between the H2A enhancer and H1 promoter. To assess the functional role of CMPl within this locus, we challenged the activity of CMPl by two distinct experimental strategies. First we expressed in the developing embryo a chimeric protein, containing the DNA-binding domain of CMPl, which efficiently compete with the endogenous CMPl for the binding to the boxB sequence. Second, to titrate the embryonic CMPl protein, we microinjected an affinity-purified CMPl antibody. In both the experimental assays we congruently observed the loss of the enhancer-blocking function of sns5, as indicated by the specific increase of the H1 expression level. Furthermore, microinjection of the CMPl antiserum in combination with a synthetic mRNA encoding a forced repressor of the H2A enhancer-bound MBF1 factor restores the normal H1 mRNA abundance. Altogether, these results strongly support the conclusion that the recruitment of CMPl on sns5 is required for buffering the H1 promoter from the H2A enhancer activity, and this, in turn, accounts for the different level of accumulation of early linker and nucleosomal transcripts. Mounting evidence in several model organisms collectively demonstrates a role for the DNA-protein complexes known as chromatin insulators in orchestrating the functional domain organization of the eukaryotic genome. Several DNA elements displaying features of insulators, viz barrier and/or directional enhancer-blocking activity, have been identified in yeast, Drosophila, sea urchin, vertebrates and plants; however, proteins that bind these DNA sequences eliciting insulator activities are far less known. Here we identify a novel protein, COMPASS-like (CMPl), which is expressed exclusively by the ambulacrarian group of metazoans and interacts directly with the sea urchin sns5 insulator. Sns5 lies within the early histone gene cluster, basically between the H2A enhancer and H1 promoter, where it acts buffering the H1 promoter from the H2A enhancer influence. Intriguingly, we find that CMPl role is absolutely required for the sns5 activity, therefore imposing the different level of accumulation of the linker and nucleosomal transcripts. Overall, our findings add an interesting and novel facet to the chromatin insulator field, highlighting the surprisingly low evolutionary conservation of trans-acting factors binding to chromatin insulators. This opens the possibility that multiple lineage-specific factors modulate chromatin organization in different metazoans.
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Affiliation(s)
- Vincenzo Cavalieri
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche, Università di Palermo, Palermo, Italy
- * E-mail: (VC); (GS)
| | - Raffaella Melfi
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche, Università di Palermo, Palermo, Italy
| | - Giovanni Spinelli
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche, Università di Palermo, Palermo, Italy
- * E-mail: (VC); (GS)
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15
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Adomako-Ankomah A, Ettensohn CA. Growth factor-mediated mesodermal cell guidance and skeletogenesis during sea urchin gastrulation. Development 2013; 140:4214-25. [PMID: 24026121 DOI: 10.1242/dev.100479] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Growth factor signaling pathways provide essential cues to mesoderm cells during gastrulation in many metazoans. Recent studies have implicated the VEGF and FGF pathways in providing guidance and differentiation cues to primary mesenchyme cells (PMCs) during sea urchin gastrulation, although the relative contributions of these pathways and the cell behaviors they regulate are not fully understood. Here, we show that FGF and VEGF ligands are expressed in distinct domains in the embryonic ectoderm of Lytechinus variegatus. We find that PMC guidance is specifically disrupted in Lv-vegf3 morphants and these embryos fail to form skeletal elements. By contrast, PMC migration is unaffected in Lv-fgfa morphants, and well-patterned but shortened skeletal elements form. We use a VEGFR inhibitor, axitinib, to show that VEGF signaling is essential not only for the initial phase of PMC migration (subequatorial ring formation), but also for the second phase (migration towards the animal pole). VEGF signaling is not required, however, for PMC fusion. Inhibition of VEGF signaling after the completion of PMC migration causes significant defects in skeletogenesis, selectively blocking the elongation of skeletal rods that support the larval arms, but not rods that form in the dorsal region of the embryo. Nanostring nCounter analysis of ∼100 genes in the PMC gene regulatory network shows a decrease in the expression of many genes with proven or predicted roles in biomineralization in vegf3 morphants. Our studies lead to a better understanding of the roles played by growth factors in sea urchin gastrulation and skeletogenesis.
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Morino Y, Koga H, Tachibana K, Shoguchi E, Kiyomoto M, Wada H. Heterochronic activation of VEGF signaling and the evolution of the skeleton in echinoderm pluteus larvae. Evol Dev 2012; 14:428-36. [PMID: 22947316 DOI: 10.1111/j.1525-142x.2012.00563.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The evolution of the echinoderm larval skeleton was examined from the aspect of interactions between skeletogenic mesenchyme cells and surrounding epithelium. We focused on vascular endothelial growth factor (VEGF) signaling, which was reported to be essential for skeletogenesis in sea urchin larvae. Here, we examined the expression patterns of vegf and vegfr in starfish and brittle stars. During starfish embryogenesis, no expression of either vegfr or vegf was detected, which contrast with previous reports on the expression of starfish homologs of sea urchin skeletogenic genes, including Ets, Tbr, and Dri. In later stages, when adult skeletogenesis commenced, vegfr and vegf expression were upregulated in skeletogenic cells and in the adjacent epidermis, respectively. These expression patterns suggest that heterochronic activation of VEGF signaling is one of the key molecular evolutionary steps in the evolution of the larval skeleton. The absence of vegf or vegfr expression during early embryogenesis in starfish suggests that the evolution of the larval skeleton requires distinct evolutionary changes, both in mesoderm cells (activation of vegfr expression) and in epidermal cells (activation of vegf expression). In brittle stars, which have well-organized skeletons like the sea urchin, vegfr and vegf were expressed in the skeletogenic mesenchyme and the overlying epidermis, respectively, in the same manner as in sea urchins. Therefore, the distinct activation of vegfr and vegf may have occurred in two lineages, sea urchins and brittle stars.
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Affiliation(s)
- Yoshiaki Morino
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 305-8572, Japan.
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Cavalieri V, Guarcello R, Spinelli G. Specific expression of a TRIM-containing factor in ectoderm cells affects the skeletal morphogenetic program of the sea urchin embryo. Development 2011; 138:4279-90. [PMID: 21896632 DOI: 10.1242/dev.066480] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the indirect developing sea urchin embryo, the primary mesenchyme cells (PMCs) acquire most of the positional and temporal information from the overlying ectoderm for skeletal initiation and growth. In this study, we characterize the function of the novel gene strim1, which encodes a tripartite motif-containing (TRIM) protein, that adds to the list of genes constituting the epithelial-mesenchymal signaling network. We report that strim1 is expressed in ectoderm regions adjacent to the bilateral clusters of PMCs and that its misexpression leads to severe skeletal abnormalities. Reciprocally, knock down of strim1 function abrogates PMC positioning and blocks skeletogenesis. Blastomere transplantation experiments establish that the defects in PMC patterning, number and skeletal growth depend upon strim1 misexpression in ectoderm cells. Furthermore, clonal expression of strim1 into knocked down embryos locally restores skeletogenesis. We also provide evidence that the Otp and Pax2/5/8 regulators, as well as FGFA, but not VEGF, ligand act downstream to strim1 in ectoderm cells, and that strim1 triggers the expression of the PMC marker sm30, an ectoderm-signaling dependent gene. We conclude that the strim1 function elicits specific gene expression both in ectoderm cells and PMCs to guide the skeletal biomineralization during morphogenesis.
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Affiliation(s)
- Vincenzo Cavalieri
- Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari STEMBIO, Università di Palermo, Viale delle Scienze Edificio 16, 90128 Palermo, Italy.
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Mazza ME, Pang K, Reitzel AM, Martindale MQ, Finnerty JR. A conserved cluster of three PRD-class homeobox genes (homeobrain, rx and orthopedia) in the Cnidaria and Protostomia. EvoDevo 2010; 1:3. [PMID: 20849646 PMCID: PMC2938728 DOI: 10.1186/2041-9139-1-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 07/05/2010] [Indexed: 01/25/2023] Open
Abstract
Background Homeobox genes are a superclass of transcription factors with diverse developmental regulatory functions, which are found in plants, fungi and animals. In animals, several Antennapedia (ANTP)-class homeobox genes reside in extremely ancient gene clusters (for example, the Hox, ParaHox, and NKL clusters) and the evolution of these clusters has been implicated in the morphological diversification of animal bodyplans. By contrast, similarly ancient gene clusters have not been reported among the other classes of homeobox genes (that is, the LIM, POU, PRD and SIX classes). Results Using a combination of in silico queries and phylogenetic analyses, we found that a cluster of three PRD-class homeobox genes (Homeobrain (hbn), Rax (rx) and Orthopedia (otp)) is present in cnidarians, insects and mollusks (a partial cluster comprising hbn and rx is present in the placozoan Trichoplax adhaerens). We failed to identify this 'HRO' cluster in deuterostomes; in fact, the Homeobrain gene appears to be missing from the chordate genomes we examined, although it is present in hemichordates and echinoderms. To illuminate the ancestral organization and function of this ancient cluster, we mapped the constituent genes against the assembled genome of a model cnidarian, the sea anemone Nematostella vectensis, and characterized their spatiotemporal expression using in situ hybridization. In N. vectensis, these genes reside in a span of 33 kb with the same gene order as previously reported in insects. Comparisons of genomic sequences and expressed sequence tags revealed the presence of alternative transcripts of Nv-otp and two highly unusual protein-coding polymorphisms in the terminal helix of the Nv-rx homeodomain. A population genetic survey revealed the Rx polymorphisms to be widespread in natural populations. During larval development, all three genes are expressed in the ectoderm, in non-overlapping territories along the oral-aboral axis, with distinct temporal expression. Conclusion We report the first evidence for a PRD-class homeobox cluster that appears to have been conserved since the time of the cnidarian-bilaterian ancestor, and possibly even earlier, given the presence of a partial cluster in the placozoan Trichoplax. Very similar clusters comprising these three genes exist in Nematostella and diverse protostomes. Interestingly, in chordates, one member of the ancestral cluster (homeobrain) has apparently been lost, and there is no linkage between rx and orthopedia in any of the vertebrates. In Nematostella, the spatial expression of these three genes along the body column is not colinear with their physical order in the cluster but the temporal expression is, therefore, using the terminology that has been applied to the Hox cluster genes, the HRO cluster would appear to exhibit temporal but not spatial colinearity. It remains to be seen whether the mechanisms responsible for the evolutionary conservation of the HRO cluster are the same mechanisms responsible for cohesion of the Hox cluster and other ANTP-class homeobox clusters that have been widely conserved throughout animal evolution.
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Affiliation(s)
- Maureen E Mazza
- Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA
| | - Kevin Pang
- Kewalo Marine Lab, Pacific Biosciences Research Center, University of Hawaii, 41 Ahui St., Honolulu, HI 96813, USA
| | - Adam M Reitzel
- Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA.,Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Mark Q Martindale
- Kewalo Marine Lab, Pacific Biosciences Research Center, University of Hawaii, 41 Ahui St., Honolulu, HI 96813, USA
| | - John R Finnerty
- Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA
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Cavalieri V, Melfi R, Spinelli G. Promoter activity of the sea urchin (Paracentrotus lividus) nucleosomal H3 and H2A and linker H1 {alpha}-histone genes is modulated by enhancer and chromatin insulator. Nucleic Acids Res 2010; 37:7407-15. [PMID: 19843609 PMCID: PMC2794192 DOI: 10.1093/nar/gkp859] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Core promoters and chromatin insulators are key regulatory elements that may direct a transcriptional enhancer to prefer a specific promoter in complex genetic loci. Enhancer and insulator flank the sea urchin (Paracentrotus lividus) α-histone H2A transcription unit in a tandem repeated cluster containing the five histone genes. This article deals with the specificity of interaction between the H2A enhancer-bound MBF-1 activator and histone gene promoters, and with the mechanism that leads the H1 transcripts to peak at about one-third of the value for nucleosomal H3 and H2A mRNAs. To this end, in vivo competition assays of enhancer and insulator functions were performed. Our evidence suggests that the MBF-1 transcription factor participates also in the expression of the H3 gene and that the sns5 insulator buffers the downstream H1 promoter from the H2A enhancer. Altogether, these results provide a clear demonstration of the enhancer-blocking function of a chromatin insulator in a natural gene context. In addition, they suggest that both the H2A enhancer and the sns5 insulator may account for the diverse accumulation of the linker H1 versus the core nucleosomal histones during early development of the sea urchin embryo.
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Affiliation(s)
- Vincenzo Cavalieri
- Dipartimento di Biologia Cellulare e dello Sviluppo (Alberto Monroy), Università di Palermo, Parco d'O;rleans II, 90128 Palermo, Italy
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Su YH, Li E, Geiss GK, Longabaugh WJR, Krämer A, Davidson EH. A perturbation model of the gene regulatory network for oral and aboral ectoderm specification in the sea urchin embryo. Dev Biol 2009; 329:410-21. [PMID: 19268450 DOI: 10.1016/j.ydbio.2009.02.029] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 01/27/2009] [Accepted: 02/25/2009] [Indexed: 11/17/2022]
Abstract
The current gene regulatory network (GRN) for the sea urchin embryo pertains to pregastrular specification functions in the endomesodermal territories. Here we extend gene regulatory network analysis to the adjacent oral and aboral ectoderm territories over the same period. A large fraction of the regulatory genes predicted by the sea urchin genome project and shown in ancillary studies to be expressed in either oral or aboral ectoderm by 24 h are included, though universally expressed and pan-ectodermal regulatory genes are in general not. The loci of expression of these genes have been determined by whole mount in situ hybridization. We have carried out a global perturbation analysis in which expression of each gene was interrupted by introduction of morpholino antisense oligonucleotide, and the effects on all other genes were measured quantitatively, both by QPCR and by a new instrumental technology (NanoString Technologies nCounter Analysis System). At its current stage the network model, built in BioTapestry, includes 22 genes encoding transcription factors, 4 genes encoding known signaling ligands, and 3 genes that are yet unknown but are predicted to perform specific roles. Evidence emerged from the analysis pointing to distinctive subcircuit features observed earlier in other parts of the GRN, including a double negative transcriptional regulatory gate, and dynamic state lockdowns by feedback interactions. While much of the regulatory apparatus is downstream of Nodal signaling, as expected from previous observations, there are also cohorts of independently activated oral and aboral ectoderm regulatory genes, and we predict yet unidentified signaling interactions between oral and aboral territories.
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Affiliation(s)
- Yi-Hsien Su
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA
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21
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Abstract
Sea urchin embryos are characterized by an extremely simple mode of development, rapid cleavage, high transparency, and well-defined cell lineage. Although they are not suitable for genetic studies, other approaches are successfully used to unravel mechanisms and molecules involved in cell fate specification and morphogenesis. Microinjection is the elective method to study gene function in sea urchin embryos. It is used to deliver precise amounts of DNA, RNA, oligonucleotides, peptides, or antibodies into the eggs or even into blastomeres. Here we describe microinjection as it is currently applied in our laboratory and show how it has been used in gene perturbation analyses and dissection of cis-regulatory DNA elements.
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Raff RA, Snoke Smith M. Chapter 7. Axis formation and the rapid evolutionary transformation of larval form. Curr Top Dev Biol 2009; 86:163-90. [PMID: 19361693 DOI: 10.1016/s0070-2153(09)01007-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Marine invertebrate embryos and larvae are diverse and can evolve rapidly, providing a link between early developmental and evolutionary mechanisms. We here discuss the role of evolutionary changes in axis formation, which is a crucial part of the patterning of marine embryos and larvae. We focus on sea urchin embryos, where axial features are well defined and subject to active current investigation. The genetic control of processes of formation of the three axial systems, animal-vegetal, dorsal-ventral, and left-right, is becoming established for species that undergo development via the feeding pluteus larva. These species represent the primitive condition among living sea urchins. We compare their developmental processes to the highly modified development of a species that has evolved a nonfeeding larva. This derived form has accelerated some elements of axis formation, and eliminated or modified others. Three features of embryonic/larval evolution stand out (1) evolution of developmental features occurs rapidly over geological time; (2) upstream gene regulatory systems of axis formation are conserved, whereas downstream features evolve rapidly; and (3) heterochronies play an important role.
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Affiliation(s)
- Rudolf A Raff
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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Del Giacco L, Pistocchi A, Cotelli F, Fortunato AE, Sordino P. A peek inside the neurosecretory brain throughOrthopedialenses. Dev Dyn 2008; 237:2295-303. [DOI: 10.1002/dvdy.21668] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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Cavalieri V, Di Bernardo M, Anello L, Spinelli G. cis-Regulatory sequences driving the expression of the Hbox12 homeobox-containing gene in the presumptive aboral ectoderm territory of the Paracentrotus lividus sea urchin embryo. Dev Biol 2008; 321:455-69. [PMID: 18585371 DOI: 10.1016/j.ydbio.2008.06.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Revised: 05/23/2008] [Accepted: 06/03/2008] [Indexed: 11/17/2022]
Abstract
Embryonic development is coordinated by networks of evolutionary conserved regulatory genes encoding transcription factors and components of cell signalling pathways. In the sea urchin embryo, a number of genes encoding transcription factors display territorial restricted expression. Among these, the zygotic Hbox12 homeobox gene is transiently transcribed in a limited number of cells of the animal-lateral half of the early Paracentrotus lividus embryo, whose descendants will constitute part of the ectoderm territory. To obtain insights on the regulation of Hbox12 expression, we have explored the cis-regulatory apparatus of the gene. In this paper, we show that the intergenic region of the tandem Hbox12 repeats drives GFP expression in the presumptive aboral ectoderm and that a 234 bp fragment, defined aboral ectoderm (AE) module, accounts for the restricted expression of the transgene. Within this module, a consensus sequence for a Sox factor and the binding of the Otx activator are both required for correct Hbox12 gene expression. Spatial restriction to the aboral ectoderm is achieved by a combination of different repressive sequence elements. Negative sequence elements necessary for repression in the endomesoderm map within the most upstream 60 bp region and nearby the Sox binding site. Strikingly, a Myb-like consensus is necessary for repression in the oral ectoderm, while down-regulation at the gastrula stage depends on a GA-rich region. These results suggest a role for Hbox12 in aboral ectoderm specification and represent our first attempt in the identification of the gene regulatory circuits involved in this process.
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Affiliation(s)
- Vincenzo Cavalieri
- Dipartimento di Biologia Cellulare e dello Sviluppo A. Monroy, Università di Palermo, Viale delle Scienze Edificio 16, 90128 Palermo, Italy
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Röttinger E, Saudemont A, Duboc V, Besnardeau L, McClay D, Lepage T. FGF signals guide migration of mesenchymal cells, control skeletal morphogenesis and regulate gastrulation during sea urchin development. Development 2008; 135:353-65. [DOI: 10.1242/dev.014282] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The sea urchin embryo is emerging as an attractive model to study morphogenetic processes such as directed migration of mesenchyme cells and cell sheet invagination, but surprisingly, few of the genes regulating these processes have yet been characterized. We present evidence that FGFA, the first FGF family member characterized in the sea urchin, regulates directed migration of mesenchyme cells, morphogenesis of the skeleton and gastrulation during early development. We found that at blastula stages, FGFA and a novel putative FGF receptor are expressed in a pattern that prefigures morphogenesis of the skeletogenic mesoderm and that suggests that FGFA is one of the elusive signals that guide migration of primary mesenchyme cells (PMCs). We first show that fgfA expression is correlated with abnormal migration and patterning of the PMCs following treatments that perturb specification of the ectoderm along the oral-aboral and animal-vegetal axes. Specification of the ectoderm initiated by Nodal is required to restrict fgfA to the lateral ectoderm, and in the absence of Nodal, fgfA is expressed ectopically throughout most of the ectoderm. Inhibition of either FGFA, FGFR1 or FGFR2 function severely affects morphogenesis of the skeleton. Furthermore,inhibition of FGFA and FGFR1 signaling dramatically delays invagination of the archenteron, prevents regionalization of the gut and abrogates formation of the stomodeum. We identified several genes acting downstream of fgfAin these processes, including the transcription factors pea3 and pax2/5/8 and the signaling molecule sprouty in the lateral ectoderm and SM30 and SM50 in the primary mesenchyme cells. This study identifies the FGF signaling pathway as an essential regulator of gastrulation and directed cell migration in the sea urchin embryo and as a key player in the gene regulatory network directing morphogenesis of the skeleton.
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Affiliation(s)
- Eric Röttinger
- UMR 7009 CNRS, Université Pierre et Marie Curie (Paris 6) Observatoire Océanologique, 06230 Villefranche sur mer, France
| | - Alexandra Saudemont
- UMR 7009 CNRS, Université Pierre et Marie Curie (Paris 6) Observatoire Océanologique, 06230 Villefranche sur mer, France
| | - Véronique Duboc
- UMR 7009 CNRS, Université Pierre et Marie Curie (Paris 6) Observatoire Océanologique, 06230 Villefranche sur mer, France
| | - Lydia Besnardeau
- UMR 7009 CNRS, Université Pierre et Marie Curie (Paris 6) Observatoire Océanologique, 06230 Villefranche sur mer, France
| | - David McClay
- Department of Biology, French Family Science Center, Duke University Durham,NC 27708, USA
| | - Thierry Lepage
- UMR 7009 CNRS, Université Pierre et Marie Curie (Paris 6) Observatoire Océanologique, 06230 Villefranche sur mer, France
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Duloquin L, Lhomond G, Gache C. Localized VEGF signaling from ectoderm to mesenchyme cells controls morphogenesis of the sea urchin embryo skeleton. Development 2007; 134:2293-302. [PMID: 17507391 DOI: 10.1242/dev.005108] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During development, cell migration plays an important role in morphogenetic processes. The construction of the skeleton of the sea urchin embryo by a small number of cells, the primary mesenchyme cells (PMCs), offers a remarkable model to study cell migration and its involvement in morphogenesis. During gastrulation, PMCs migrate and become positioned along the ectodermal wall following a stereotypical pattern that determines skeleton morphology. Previous studies have shown that interactions between ectoderm and PMCs regulate several aspects of skeletal morphogenesis, but little is known at the molecular level. Here we show that VEGF signaling between ectoderm and PMCs is crucial in this process. The VEGF receptor (VEGFR) is expressed exclusively in PMCs, whereas VEGF expression is restricted to two small areas of the ectoderm, in front of the positions where the ventrolateral PMC clusters that initiate skeletogenesis will form. Overexpression of VEGF leads to skeletal abnormalities, whereas inhibition of VEGF/VEGFR signaling results in incorrect positioning of the PMCs, downregulation of PMC-specific genes and loss of skeleton. We present evidence that localized VEGF acts as both a guidance cue and a differentiation signal, providing a crucial link between the positioning and differentiation of the migrating PMCs and leading to morphogenesis of the embryonic skeleton.
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Affiliation(s)
- Louise Duloquin
- Developmental Biology Unit, University Pierre et Marie Curie, Paris 6 and CNRS, Observatoire Océanologique, 06230 Villefranche-sur-Mer, France
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Love AC, Andrews ME, Raff RA. Gene expression patterns in a novel animal appendage: the sea urchin pluteus arm. Evol Dev 2007; 9:51-68. [PMID: 17227366 DOI: 10.1111/j.1525-142x.2006.00137.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The larval arms of echinoid plutei are used for locomotion and feeding. They are composed of internal calcite skeletal rods covered by an ectoderm layer bearing a ciliary band. Skeletogenesis includes an autonomous molecular differentiation program in primary mesenchyme cells (PMCs), initiated when PMCs leave the vegetal plate for the blastocoel, and a patterning of the differentiated skeletal units that requires molecular cues from the overlaying ectoderm. The arms represent a larval feature that arose in the echinoid lineage during the Paleozoic and offers a subject for the study of gene co-option in the evolution of novel larval features. We isolated new molecular markers in two closely related but differently developing species, Heliocidaris tuberculata and Heliocidaris erythrogramma. We report the expression of a larval arm-associated ectoderm gene tetraspanin, as well as two new PMC markers, advillin and carbonic anhydrase. Tetraspanin localizes to the animal half of blastula stage H. tuberculata and then undergoes a restriction into the putative oral ectoderm and future location of the postoral arms, where it continues to be expressed at the leading edge of both the postoral and anterolateral arms. In H. erythrogramma, its expression initiates in the animal half of blastulae and expands over the entire ectoderm from gastrulation onward. Advillin and carbonic anhydrase are upregulated in the PMCs postgastrulation and localized to the leading edge of the growing larval arms of H. tuberculata but do not exhibit coordinated expression in H. erythrogramma larvae. The tight spatiotemporal regulation of these genes in H. tuberculata along with other ontogenetic and phylogenetic evidence suggest that pluteus arms are novel larval organs, distinguishable from the processes of skeletogenesis per se. The dissociation of expression control in H. erythrogramma suggest that coordinate gene expression in H. tuberculata evolved as part of the evolution of pluteus arms, and is not required for larval or adult development.
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Affiliation(s)
- Alan C Love
- Department of Biology, Indiana Molecular Biology Institute, Indiana University, Bloomington, IN 47405, USA
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Cavalieri V, Bernardo MD, Spinelli G. Regulatory sequences driving expression of the sea urchin Otp homeobox gene in oral ectoderm cells. Gene Expr Patterns 2007; 7:124-30. [PMID: 16843737 DOI: 10.1016/j.modgep.2006.06.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Revised: 06/06/2006] [Accepted: 06/07/2006] [Indexed: 11/19/2022]
Abstract
PlOtp (Orthopedia), a homeodomain-containing transcription factor, has been recently characterized as a key regulator of the morphogenesis of the skeletal system in the embryo of the sea urchin Paracentrotus lividus. Otp acts as a positive regulator in a subset of oral ectodermal cells which transmit short-range signals to the underlying primary mesenchyme cells where skeletal synthesis is initiated. To shed some light on the molecular mechanisms involved in such a process, we begun a functional analysis of the cis-regulatory sequences of the Otp gene. Congruent with the spatial expression profile of the endogenous Otp gene, we found that while a DNA region from -494 to +358 is shown to drive in vivo GFP reporter expression in the oral ectoderm, but also in the foregut, a larger region spanning from -2044 to +358 is needed to give firmly established tissue specificity. Microinjection of PCR-amplified DNA constructs, truncated in the 5' regulatory region, and determination of GFP mRNA level in injected embryos allowed the identification of a 5'-flanking fragment of 184bp in length, essential for expression of the transgene in the oral ectoderm of pluteus stage embryos. Finally, we conducted DNAse I-footprinting assays in nuclear extracts for the 184bp region and detected two protected sequences. Data bank search indicates that these sites contain consensus binding sites for transcription factors.
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Affiliation(s)
- Vincenzo Cavalieri
- Dipartimento di Biologia Cellulare e dello Sviluppo A. Monroy, Università di Palermo, Viale delle Scienze Parco d'Orleans II, 90128 Palermo, Italy
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Del Giacco L, Sordino P, Pistocchi A, Andreakis N, Tarallo R, Di Benedetto B, Cotelli F. Differential regulation of the zebrafish orthopedia 1 gene during fate determination of diencephalic neurons. BMC DEVELOPMENTAL BIOLOGY 2006; 6:50. [PMID: 17074092 PMCID: PMC1635040 DOI: 10.1186/1471-213x-6-50] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Accepted: 10/30/2006] [Indexed: 11/10/2022]
Abstract
BACKGROUND The homeodomain transcription factor Orthopedia (Otp) is essential in restricting the fate of multiple classes of secreting neurons in the neuroendocrine hypothalamus of vertebrates. However, there is little information on the intercellular factors that regulate Otp expression during development. RESULTS Here, we identified two otp orthologues in zebrafish (otp1 and otp2) and explored otp1 in the context of the morphogenetic pathways that specify neuroectodermal regions. During forebrain development, otp1 is expressed in anterior groups of diencephalic cells, positioned in the preoptic area (PO) (anterior alar plate) and the posterior tuberculum (PT) (posterior basal plate). The latter structure is characterized by Tyrosine Hydroxylase (TH)-positive cells, suggesting a role for otp1 in the lineage restriction of catecholaminergic (CA) neurons. Disruptions of Hedgehog (HH) and Fibroblast Growth Factor (FGF) pathways point to the ability of SHH protein to trigger otp1 expression in PO presumptive neuroblasts, with the attenuating effect of Dzip1 and FGF8. In addition, our data disclose otp1 as a determinant of CA neurons in the PT, where otp1 activity is strictly dependent on Nodal signaling and it is not responsive to SHH and FGF. CONCLUSION In this study, we pinpoint the evolutionary importance of otp1 transcription factor in cell states of the diencephalon anlage and early neuronal progenitors. Furthermore, our data indicate that morphogenetic mechanisms differentially regulate otp1 expression in alar and basal plates.
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Affiliation(s)
- Luca Del Giacco
- Department of Biology, Università degli Studi di Milano, Via Celoria 26, Milano, 20133, Italy
| | - Paolo Sordino
- Laboratory of Biochemistry and Molecular Biology, Stazione Zoologica "A. Dohrn", Villa Comunale, Napoli, 80121, Italy
| | - Anna Pistocchi
- Department of Biology, Università degli Studi di Milano, Via Celoria 26, Milano, 20133, Italy
| | - Nikos Andreakis
- Laboratory of Biochemistry and Molecular Biology, Stazione Zoologica "A. Dohrn", Villa Comunale, Napoli, 80121, Italy
| | - Raffaella Tarallo
- Laboratory of Biochemistry and Molecular Biology, Stazione Zoologica "A. Dohrn", Villa Comunale, Napoli, 80121, Italy
| | - Barbara Di Benedetto
- Department of Biology, Università degli Studi di Milano, Via Celoria 26, Milano, 20133, Italy
- GSF National Research Center for Environment and Health, Institute of Developmental Genetics, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
| | - Franco Cotelli
- Department of Biology, Università degli Studi di Milano, Via Celoria 26, Milano, 20133, Italy
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Cheers MS, Ettensohn CA. P16 is an essential regulator of skeletogenesis in the sea urchin embryo. Dev Biol 2005; 283:384-96. [PMID: 15935341 DOI: 10.1016/j.ydbio.2005.02.037] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2005] [Revised: 02/16/2005] [Accepted: 02/23/2005] [Indexed: 11/27/2022]
Abstract
The primary mesenchyme cells (PMCs) of the sea urchin embryo undergo a dramatic sequence of morphogenetic behaviors that culminates in the formation of the larval endoskeleton. Recent studies have identified components of a gene regulatory network that underlies PMC specification and differentiation. In previous work, we identified novel gene products expressed specifically by PMCs (Illies, M.R., Peeler, M.T., Dechtiaruk, A.M., Ettensohn, C.A., 2002. Identification and developmental expression of new biomineralization proteins in the sea urchin, Strongylocentrotus purpuratus. Dev. Genes Evol. 212, 419-431). Here, we show that one of these gene products, P16, plays an essential role in skeletogenesis. P16 is not required for PMC specification, ingression, migration, or fusion, but is essential for skeletal rod elongation. We have compared the predicted sequences of P16 from two species and show that this small, acidic protein is highly conserved in both structure and function. The predicted amino acid sequence of P16 and the subcellular localization of a GFP-tagged form of the protein suggest that P16 is enriched in the plasma membrane. It may function to receive signals required for skeletogenesis or may play a more direct role in the deposition of biomineral. Finally, we place P16 downstream of Alx1 in the PMC gene network, thereby linking the network to a specific "effector" protein involved in biomineralization.
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Affiliation(s)
- Melani S Cheers
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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Coffman JA, Dickey-Sims C, Haug JS, McCarthy JJ, Robertson AJ. Evaluation of developmental phenotypes produced by morpholino antisense targeting of a sea urchin Runx gene. BMC Biol 2004; 2:6. [PMID: 15132741 PMCID: PMC419381 DOI: 10.1186/1741-7007-2-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2004] [Accepted: 05/07/2004] [Indexed: 12/04/2022] Open
Abstract
Background Runx transcription factors are important regulators of metazoan development. The sea urchin Runx gene SpRunt was previously identified as a trans-activator of the CyIIIa actin gene, a differentiation marker of larval aboral ectoderm. Here we extend the functional analysis of SpRunt, using morpholino antisense oligonucleotides (morpholinos) to interfere with SpRunt expression in the embryo. Results The developmental effects of four different SpRunt-specific morpholinos were evaluated. The two morpholinos most effective at knocking down SpRunt produce an identical mitotic catastrophe phenotype at late cleavage stage that is an artifact of coincidental mis-targeting to histone mRNA, providing a cautionary example of the insufficiency of two different morpholinos as a control for specificity. The other two morpholinos produce gastrula stage proliferation and differentiation defects that are rescued by exogenous SpRunt mRNA. The expression of 22 genes involved in cell proliferation and differentiation was analyzed in the latter embryos by quantitative polymerase chain reaction. Knockdown of SpRunt was found to perturb the expression of differentiation markers in all of the major tissue territories as well as the expression of cell cycle control genes, including cyclin B and cyclin D. Conclusions SpRunt is essential for embryonic development, and is required globally to coordinate cell proliferation and differentiation.
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Affiliation(s)
- James A Coffman
- Stowers Institute for Medical Research, 1000 E. 50Street, Kansas City, MO 64110, USA
| | - Carrie Dickey-Sims
- Stowers Institute for Medical Research, 1000 E. 50Street, Kansas City, MO 64110, USA
| | - Jeffrey S Haug
- Stowers Institute for Medical Research, 1000 E. 50Street, Kansas City, MO 64110, USA
| | - John J McCarthy
- Stowers Institute for Medical Research, 1000 E. 50Street, Kansas City, MO 64110, USA
| | - Anthony J Robertson
- Stowers Institute for Medical Research, 1000 E. 50Street, Kansas City, MO 64110, USA
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Abstract
It may safely be predicted that GRN analysis will become increasingly important. It will come to underlie the causal study of development, the major effort underway to understand the regulatory code built into animal genomes and also the evolution of these genomes. Partly by serendipity, sea urchin embryos turn out to be a superb experimental material for GRN analysis. Their natural properties have, in turn, influenced the predilections of those who work on them, and between them and us, so to speak, this is now a developmental system of which we are rapidly gaining an unusually complete understanding. The causal linkages that control development of the whole embryo will be revealed, leading all the way from the heritable genomic regulatory code to the events of embryology. The fundamental experimental operation is the perturbation analysis: Here is where causality permeates the exploration. We have in this chapter summarized in some detail the requirements for perturbation GRN analysis in sea urchin embryos. But that is not all, nor is it enough to enable the assembly of a GRN: What is required is the combined application of elegant computational methods, of gene regulation molecular biology, of genomic sequence data, and of experimental embryology. As the results crystallize together, we can begin to see how far this powerful combination of methods and ideas is going to carry us.
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Affiliation(s)
- Paola Oliveri
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
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Lepage T, Gache C. Expression of exogenous mRNAs to study gene function in the sea urchin embryo. Methods Cell Biol 2004; 74:677-97. [PMID: 15575626 DOI: 10.1016/s0091-679x(04)74027-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Expression of exogenous mRNAs has become part of the standard approach to studying gene function during development of the sea urchin. The method is simple and reliable, protocols for the preparation of synthetic mRNAs are well described, and the technique to transfer them into eggs is efficient. The protein encoded by these mRNAs can be designed to address a variety of biological questions and their DNA matrices are easily constructed by standard molecular biology techniques. The method aims to simulate gain or loss of gene function, and the phenotypes obtained are characterized using an increasing number of molecular markers. With the completion of the S. purpuratus genome project, the complete set of genes from the sea urchin will become available. Expression of mRNA will be an invaluable tool to study the function of newly identified genes and their protein products and to determine their positions within the networks of gene and protein interactions that control development.
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Affiliation(s)
- Thierry Lepage
- Laboratory of Developmental Biology, CNRS-Université Pierre et Marie Curie (Paris VI), Observatoire Océanologique, 06230 Villefranche-sur-Mer, France
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