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Viswanathan PK, Chessel A, Molina MD, Haillot E, Lepage T. Maternal TGF-β ligand Panda breaks the radial symmetry of the sea urchin embryo by antagonizing the Nodal type II receptor ACVRII. PLoS Biol 2024; 22:e3002701. [PMID: 38913712 PMCID: PMC11239237 DOI: 10.1371/journal.pbio.3002701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 07/11/2024] [Accepted: 06/07/2024] [Indexed: 06/26/2024] Open
Abstract
In the highly regulative embryo of the sea urchin Paracentrotus lividus, establishment of the dorsal-ventral (D/V) axis critically depends on the zygotic expression of the TGF-β nodal in the ventral ectoderm. nodal expression is first induced ubiquitously in the 32-cell embryo and becomes progressively restricted to the presumptive ventral ectoderm by the early blastula stage. This early spatial restriction of nodal expression is independent of Lefty, and instead relies on the activity of Panda, a maternally expressed TGF-β ligand related to Lefty and Inhibins, which is required maternally for D/V axis specification. However, the mechanism by which Panda restricts the early nodal expression has remained enigmatic and it is not known if Panda works like a BMP ligand by opposing Nodal and antagonizing Smad2/3 signaling, or if it works like Lefty by sequestering an essential component of the Nodal signaling pathway. In this study, we report that Panda functions as an antagonist of the TGF-β type II receptor ACVRII (Activin receptor type II), which is the only type II receptor for Nodal signaling in the sea urchin and is also a type II receptor for BMP ligands. Inhibiting translation of acvrII mRNA disrupted D/V patterning across all 3 germ layers and caused acvrII morphants to develop with a typical Nodal loss-of-function phenotype. In contrast, embryos overexpressing acvrII displayed strong ectopic Smad1/5/8 signaling at blastula stages and developed as dorsalized larvae, a phenotype very similar to that caused by over activation of BMP signaling. Remarkably, embryos co-injected with acvrII mRNA and panda mRNA did not show ectopic Smad1/5/8 signaling and developed with a largely normal dorsal-ventral polarity. Furthermore, using an axis induction assay, we found that Panda blocks the ability of ACVRII to orient the D/V axis when overexpressed locally. Using co-immunoprecipitation, we showed that Panda physically interacts with ACVRII, as well as with the Nodal co-receptor Cripto, and with TBR3 (Betaglycan), which is a non-signaling receptor for Inhibins in mammals. At the molecular level, we have traced back the antagonistic activity of Panda to the presence of a single proline residue, conserved with all the Lefty factors, in the ACVRII binding motif of Panda, instead of a serine as in most of TGF-β ligands. Conversion of this proline to a serine converted Panda from an antagonist that opposed Nodal signaling and promoted dorsalization to an agonist that promoted Nodal signaling and triggered ventralization when overexpressed. Finally, using phylogenomics, we analyzed the emergence of the agonist and antagonist form of Panda in the course of evolution. Our data are consistent with the idea that the presence of a serine at that position, like in most TGF-β, was the ancestral condition and that the initial function of Panda was possibly in promoting and not in antagonizing Nodal signaling. These results highlight the existence of key functional and structural elements conserved between Panda and Lefty, allow to draw an intriguing parallel between sea urchin Panda and mammalian Inhibin α and raise the unexpected possibility that the original function of Panda may have been in activation of the Nodal pathway rather than in its inhibition.
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Affiliation(s)
| | - Aline Chessel
- Université Côte d’Azur, CNRS, Inserm, iBV, Nice, France
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Chessel A, De Crozé N, Molina MD, Taberner L, Dru P, Martin L, Lepage T. RAS-independent ERK activation by constitutively active KSR3 in non-chordate metazoa. Nat Commun 2023; 14:3970. [PMID: 37407549 DOI: 10.1038/s41467-023-39606-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 06/21/2023] [Indexed: 07/07/2023] Open
Abstract
During early development of the sea urchin embryo, activation of ERK signalling in mesodermal precursors is not triggered by extracellular RTK ligands but by a cell-autonomous, RAS-independent mechanism that was not understood. We discovered that in these cells, ERK signalling is activated through the transcriptional activation of a gene encoding a protein related to Kinase Suppressor of Ras, that we named KSR3. KSR3 belongs to a family of catalytically inactive allosteric activators of RAF. Phylogenetic analysis revealed that genes encoding kinase defective KSR3 proteins are present in most non-chordate metazoa but have been lost in flies and nematodes. We show that the structure of KSR3 factors resembles that of several oncogenic human RAF mutants and that KSR3 from echinoderms, cnidarians and hemichordates activate ERK signalling independently of RAS when overexpressed in cultured cells. Finally, we used the sequence of KSR3 factors to identify activating mutations of human B-RAF. These findings reveal key functions for this family of factors as activators of RAF in RAS-independent ERK signalling in invertebrates. They have implications on the evolution of the ERK signalling pathway and suggest a mechanism for its co-option in the course of evolution.
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Affiliation(s)
- Aline Chessel
- Institut de Biologie Valrose CNRS, Université Côte d'Azur, Nice, France
| | - Noémie De Crozé
- Institut de Biologie Valrose CNRS, Université Côte d'Azur, Nice, France
| | - Maria Dolores Molina
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Catalonia, Spain
| | - Laura Taberner
- Institut de Biologie Valrose CNRS, Université Côte d'Azur, Nice, France
| | - Philippe Dru
- CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-Mer (LBDV), Institut de la Mer de Villefranche, 181 Chemin du Lazaret, 06230, Villefranche-sur-Mer, France
| | - Luc Martin
- Institut de Biologie Valrose CNRS, Université Côte d'Azur, Nice, France
| | - Thierry Lepage
- Institut de Biologie Valrose CNRS, Université Côte d'Azur, Nice, France.
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3
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Dynamics of maternal gene expression in Rhodnius prolixus. Sci Rep 2022; 12:6538. [PMID: 35449214 PMCID: PMC9023505 DOI: 10.1038/s41598-022-09874-7] [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: 06/09/2021] [Accepted: 03/14/2022] [Indexed: 11/08/2022] Open
Abstract
The study of developmental processes in Rhodnius prolixus has recently advanced with the sequencing of the genome. In this work, we analyze the maternal gene expression driving oogenesis and early embryogenesis in R. prolixus. We examined the transcriptional profile of mRNAs to establish the genes expressed across the ovary, unfertilized eggs and different embryonic stages of R. prolixus until the formation of the germ band anlage (0, 12, 24, and 48 h post egg laying). We identified 81 putative maternal and ovary-related genes and validated their expression by qRT-PCR. We validate the function of the ortholog gene Bicaudal-D (Rp-BicD) by in situ hybridization and parental RNAi. Consistent with a role in oogenesis and early development of R. prolixus, we show that lack of Rp-BicD does not significantly affect oogenesis but impairs the formation of the blastoderm. Based on our findings, we propose three times of action for maternal genes during oogenesis and embryogenesis in R. prolixus.
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4
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Czarkwiani A, Dylus DV, Carballo L, Oliveri P. FGF signalling plays similar roles in development and regeneration of the skeleton in the brittle star Amphiura filiformis. Development 2021; 148:dev180760. [PMID: 34042967 PMCID: PMC8180256 DOI: 10.1242/dev.180760] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 04/13/2021] [Indexed: 12/16/2022]
Abstract
Regeneration as an adult developmental process is in many aspects similar to embryonic development. Although many studies point out similarities and differences, no large-scale, direct and functional comparative analyses between development and regeneration of a specific cell type or structure in one animal exist. Here, we use the brittle star Amphiura filiformis to characterise the role of the FGF signalling pathway during skeletal development in embryos and arm regeneration. In both processes, we find ligands expressed in ectodermal cells that flank underlying skeletal mesenchymal cells, which express the receptors. Perturbation of FGF signalling showed inhibited skeleton formation in both embryogenesis and regeneration, without affecting other key developmental processes. Differential transcriptome analysis finds mostly differentiation genes rather than transcription factors to be downregulated in both contexts. Moreover, comparative gene analysis allowed us to discover brittle star-specific differentiation genes. In conclusion, our results show that the FGF pathway is crucial for skeletogenesis in the brittle star, as in other deuterostomes, and provide evidence for the re-deployment of a developmental gene regulatory module during regeneration.
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Affiliation(s)
- Anna Czarkwiani
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - David V. Dylus
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
- Centre for Mathematics, Physics and Engineering in the Life Sciences and Experimental Biology, University College London, London WC1E 6BT, UK
| | - Luisana Carballo
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - Paola Oliveri
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
- Centre for Life's Origin and Evolution (CLOE), University College London, London WC1E 6BT, UK
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5
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Yaguchi J, Yaguchi S. Sea urchin larvae utilize light for regulating the pyloric opening. BMC Biol 2021; 19:64. [PMID: 33820528 PMCID: PMC8022552 DOI: 10.1186/s12915-021-00999-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 03/05/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Light is essential for various biological activities. In particular, visual information through eyes or eyespots is very important for most of animals, and thus, the functions and developmental mechanisms of visual systems have been well studied to date. In addition, light-dependent non-visual systems expressing photoreceptor Opsins have been used to study the effects of light on diverse animal behaviors. However, it remains unclear how light-dependent systems were acquired and diversified during deuterostome evolution due to an almost complete lack of knowledge on the light-response signaling pathway in Ambulacraria, one of the major groups of deuterostomes and a sister group of chordates. RESULTS Here, we show that sea urchin larvae utilize light for digestive tract activity. We found that photoirradiation of larvae induces pyloric opening even without addition of food stimuli. Micro-surgical and knockdown experiments revealed that this stimulating light is received and mediated by Go(/RGR)-Opsin (Opsin3.2 in sea urchin genomes) cells around the anterior neuroectoderm. Furthermore, we found that the anterior neuroectodermal serotoninergic neurons near Go-Opsin-expressing cells are essential for mediating light stimuli-induced nitric oxide (NO) release at the pylorus. Our results demonstrate that the light>Go-Opsin>serotonin>NO pathway functions in pyloric opening during larval stages. CONCLUSIONS The results shown here will lead us to understand how light-dependent systems of pyloric opening functioning via neurotransmitters were acquired and established during animal evolution. Based on the similarity of nervous system patterns and the gut proportions among Ambulacraria, we suggest the light>pyloric opening pathway may be conserved in the clade, although the light signaling pathway has so far not been reported in other members of the group. In light of brain-gut interactions previously found in vertebrates, we speculate that one primitive function of anterior neuroectodermal neurons (brain neurons) may have been to regulate the function of the digestive tract in the common ancestor of deuterostomes. Given that food consumption and nutrient absorption are essential for animals, the acquirement and development of brain-based sophisticated gut regulatory system might have been important for deuterostome evolution.
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Affiliation(s)
- Junko Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka, 415-0025, Japan
| | - Shunsuke Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka, 415-0025, Japan.
- PRESTO, JST, 4-1-8 Honcho, Kawaguchi, 332-0012, Japan.
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6
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Maternal factors regulating symmetry breaking and dorsal–ventral axis formation in the sea urchin embryo. Curr Top Dev Biol 2020; 140:283-316. [DOI: 10.1016/bs.ctdb.2019.10.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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7
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Fernandez-Nicolas A, Xu D, Yajima M. A tumor suppressor Retinoblastoma1 is essential for embryonic development in the sea urchin. Dev Dyn 2019; 248:1273-1285. [PMID: 31515896 DOI: 10.1002/dvdy.113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/19/2019] [Accepted: 09/06/2019] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Embryonic cells and cancer cells share various cellular characteristics important for their functions. It has been thus proposed that similar mechanisms of regulation may be present in these otherwise disparate cell types. RESULTS To explore how regulative embryonic cells are fundamentally different from cancerous cells, we report here that a fine balance of a tumor suppressor protein Retinoblastoma1 (Rb1) and a germline factor Vasa are important for proper cell proliferation and differentiation of the somatic cells during embryogenesis of the sea urchin. Rb1 knockdown blocked embryonic development and induced Vasa accumulation in the entire embryo, while its overexpression resulted in a smaller-sized embryo with differentiated body structures. These results suggest that a titrated level of Rb1 protein may be essential for a proper balance of cell proliferation and differentiation during development. Vasa knockdown or overexpression, on the other hand, reduced or increased Rb1 protein expression, respectively. CONCLUSIONS Taken together, it appears that Vasa protein positively regulates Rb1 protein while Rb1 protein negatively regulates Vasa protein, balancing the act of these two antagonistic molecules in somatic cells. This mechanism may provide a fine control of cell proliferation and differentiation, which is essential for regulative embryonic development.
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Affiliation(s)
| | - Derek Xu
- MCB Department, Brown University, Providence, Rhode Island
| | - Mamiko Yajima
- MCB Department, Brown University, Providence, Rhode Island
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Wong JM, Gaitán-Espitia JD, Hofmann GE. Transcriptional profiles of early stage red sea urchins (Mesocentrotus franciscanus) reveal differential regulation of gene expression across development. Mar Genomics 2019; 48:100692. [PMID: 31227413 DOI: 10.1016/j.margen.2019.05.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 05/28/2019] [Accepted: 05/29/2019] [Indexed: 12/17/2022]
Abstract
The red sea urchin, Mesocentrotus franciscanus, is an ecologically important kelp forest species that also serves as a valuable fisheries resource. In this study, we have assembled and annotated a developmental transcriptome for M. franciscanus that represents eggs and six stages of early development (8- to 16-cell, morula, hatched blastula, early gastrula, prism and early pluteus). Characterization of the transcriptome revealed distinct patterns of gene expression that corresponded to major developmental and morphological processes. In addition, the period during which maternally-controlled transcription was terminated and the zygotic genome was activated, the maternal-to-zygotic transition (MZT), was found to begin during early cleavage and persist through the hatched blastula stage, an observation that is similar to the timing of the MZT in other sea urchin species. The presented developmental transcriptome will serve as a useful resource for investigating, in both an ecological and fisheries context, how the early developmental stages of this species respond to environmental stressors.
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Affiliation(s)
- Juliet M Wong
- Department of Ecology, Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Juan D Gaitán-Espitia
- The Swire Institute of Marine Science, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
| | - Gretchen E Hofmann
- Department of Ecology, Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
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9
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Vastenhouw NL, Cao WX, Lipshitz HD. The maternal-to-zygotic transition revisited. Development 2019; 146:146/11/dev161471. [PMID: 31189646 DOI: 10.1242/dev.161471] [Citation(s) in RCA: 205] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The development of animal embryos is initially directed by maternal gene products. Then, during the maternal-to-zygotic transition (MZT), developmental control is handed to the zygotic genome. Extensive research in both vertebrate and invertebrate model organisms has revealed that the MZT can be subdivided into two phases, during which very different modes of gene regulation are implemented: initially, regulation is exclusively post-transcriptional and post-translational, following which gradual activation of the zygotic genome leads to predominance of transcriptional regulation. These changes in the gene expression program of embryos are precisely controlled and highly interconnected. Here, we review current understanding of the mechanisms that underlie handover of developmental control during the MZT.
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Affiliation(s)
- Nadine L Vastenhouw
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, 01307 Dresden, Germany
| | - Wen Xi Cao
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, Ontario M5G 1M1, Canada
| | - Howard D Lipshitz
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, Ontario M5G 1M1, Canada
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Yamazaki A, Yamamoto A, Yaguchi J, Yaguchi S. cis-Regulatory analysis for later phase of anterior neuroectoderm-specific foxQ2 expression in sea urchin embryos. Genesis 2019; 57:e23302. [PMID: 31025827 DOI: 10.1002/dvg.23302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 04/09/2019] [Accepted: 04/10/2019] [Indexed: 01/31/2023]
Abstract
The specification of anterior neuroectoderm is controlled by a highly conserved molecular mechanism in bilaterians. A forkhead family gene, foxQ2, is known to be one of the pivotal regulators, which is zygotically expressed in this region during embryogenesis of a broad range of bilaterians. However, what controls the expression of this essential factor has remained unclear to date. To reveal the regulatory mechanism of foxQ2, we performed cis-regulatory analysis of two foxQ2 genes, foxQ2a and foxQ2b, in a sea urchin Hemicentrotus pulcherrimus. In sea urchin embryos, foxQ2 is initially expressed in the entire animal hemisphere and subsequently shows narrower expression restricted to the anterior pole region. In this study, as a first step to understand the foxQ2 regulation, we focused on the later restricted expression and analyzed the upstream cis-regulatory sequences of foxQ2a and foxQ2b by using the constructs fused to short half-life green fluorescent protein. Based on deletion and mutation analyses of both foxQ2, we identified each of the five regulatory sequences, which were 4-9 bp long. Neither of the regulatory sequences contains any motifs for ectopic activation or spatial repression, suggesting that later mRNA localization is regulated in situ. We also suggest that the three amino acid loop extension-class homeobox gene Meis is involved in the maintenance of foxQ2b, the expression of which is dominant during embryogenesis.
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Affiliation(s)
- Atsuko Yamazaki
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan
| | - Akane Yamamoto
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan
| | - Junko Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan
| | - Shunsuke Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan
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Comparative transcriptome analysis explores maternal to zygotic transition during Eriocheir sinensis early embryogenesis. Gene 2019; 685:12-20. [PMID: 30321661 DOI: 10.1016/j.gene.2018.10.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Revised: 09/27/2018] [Accepted: 10/11/2018] [Indexed: 11/21/2022]
Abstract
The maternal genome directs almost all aspects of early animal development. As development proceeds, the elimination of maternal gene products and zygotic genome activation (ZGA) occur during the maternal to zygotic transition (MZT). To study the molecular mechanisms regulating this developmental event in Eriocheir sinensis, RNA-Seq technology was applied to generate comprehensive information on transcriptome dynamics during early embryonic stages. In total, 32,088 annotated unigenes were obtained from the transcriptomes of fertilized eggs and embryos at the cleavage (2-4 cell) and blastula stage. A total of 566 maternal genes and 1165 zygotic genes were isolated, among which 103 and 266 genes were predicted conserved maternal transcripts (COMATs) and conserved zygotic transcripts (COZYTs), respectively. The COMATs performed housekeeping gene functions and may be essential for initiating early embryogenesis of the Bilateria. Furthermore, 87, 76 and 117 differentially expressed genes associated with the MZT, morphogenesis and immunity were identified when compared the three transcriptomic datasets. We also unmask that the MZT takes place around the cleavage stage, when the genes involved in the clearance of maternal gene products and the ZGA were significantly up-regulated. Taken together, these datasets provide a valuable resource for understanding the mechanisms of early developmental events in E. sinensis, and facilitate further studies on molecular mechanisms of asynchronous development in crabs.
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Kudtarkar P, Cameron RA. Echinobase: an expanding resource for echinoderm genomic information. DATABASE-THE JOURNAL OF BIOLOGICAL DATABASES AND CURATION 2018; 2017:4157993. [PMID: 29220460 PMCID: PMC5737241 DOI: 10.1093/database/bax074] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 08/23/2017] [Indexed: 11/21/2022]
Abstract
Echinobase, a web accessible information system of diverse genomics and biological data for the echinoderm clade, grew out of SpBase, the first echinoderm genome project for sea urchin, Strongylocentrotus purpuratus. Sea urchins and their relatives are utilitarian research models in fields ranging from marine biology to developmental biology and gene regulatory systems. Echinobase is a user-friendly web interface that links an array of biological data that would otherwise have been tedious and frustrating for researchers to extract and organize. The system hosts a powerful gene search engine, genomics browser and other bioinformatics tools to investigate genomics and high throughput data. The Echinobase information system now serves genomic information for eight echinoderm species: S. purpuratus, Strongylocentrotus fransciscanus, Allocentrotus fragilis, Lytechinus variegatus, Patiria miniata, Parastichopus parvimensis and Ophiothrix spiculata, Eucidaris tribuloides. Herein lies a description of the web information system, genomics data types and content hosted by Echinobase.org. The goal of Echinobase is to connect genomic information to various experimental data and accelerate the research in field of molecular biology, developmental process, gene regulatory networks and more recently engineering biological systems0. Database URL:http://www.echinobase.org
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Affiliation(s)
- Parul Kudtarkar
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - R. Andrew Cameron
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
- Corresponding author: Tel: 626 395 8421;
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Armstrong AF, Grosberg RK. The developmental transcriptomes of two sea biscuit species with differing larval types. BMC Genomics 2018; 19:368. [PMID: 29776340 PMCID: PMC5960215 DOI: 10.1186/s12864-018-4768-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 05/09/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Larval developmental patterns are extremely varied both between and within phyla, however the genetic mechanisms leading to this diversification are poorly understood. We assembled and compared the developmental transcriptomes for two sea biscuit species (Echinodermata: Echinoidea) with differing patterns of larval development, to provide a resource for investigating the evolution of alternate life cycles. One species (Clypeaster subdepressus) develops via an obligately feeding larva which metamorphoses 3-4 weeks after fertilization; the other (Clypeaster rosaceus) develops via a rare, intermediate larval type-facultative feeding- and can develop through metamorphosis entirely based on egg provisioning in under one week. RESULTS Overall, the two transcriptomes are highly similar, containing largely orthologous contigs with similar functional annotation. However, we found distinct differences in gene expression patterns between the two species. Larvae from C. rosaceus, the facultative planktotroph, turned genes on at earlier stages and had less differentiation in gene expression between larval stages, whereas, C. subdepressus showed a higher degree of stage-specific gene expression. CONCLUSION This study is the first genetic analysis of a species with facultatively feeding larvae. Our results are consistent with known developmental differences between the larval types and raise the question of whether earlier onset of developmental genes is a key step in the evolution of a reduced larval period. By publishing a transcriptome for this rare, intermediate, larval type, this study adds developmental breadth to the current genetic resources, which will provide a valuable tool for future research on echinoderm development as well as studies on the evolution of development in general.
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Affiliation(s)
- Anne Frances Armstrong
- Center for Population Biology, University of California, Davis, 1 Shields Avenue, Davis, CA, 95616, USA. .,California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA, 94118, USA.
| | - Richard K Grosberg
- Coastal and Marine Sciences Institute, University of California, Davis, 1 Shields Avenue, Davis, CA, 95616, USA
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Wong JM, Johnson KM, Kelly MW, Hofmann G. Transcriptomics reveal transgenerational effects in purple sea urchin embryos: Adult acclimation to upwelling conditions alters the response of their progeny to differential
p
CO
2
levels. Mol Ecol 2018; 27:1120-1137. [DOI: 10.1111/mec.14503] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Revised: 12/19/2017] [Accepted: 01/08/2018] [Indexed: 01/01/2023]
Affiliation(s)
- Juliet M. Wong
- Department of Ecology, Evolution and Marine Biology University of California, Santa Barbara Santa Barbara CA USA
| | - Kevin M. Johnson
- Department of Ecology, Evolution and Marine Biology University of California, Santa Barbara Santa Barbara CA USA
- Department of Biological Sciences Louisiana State University Baton Rouge LA USA
| | - Morgan W. Kelly
- Department of Biological Sciences Louisiana State University Baton Rouge LA USA
| | - Gretchen E. Hofmann
- Department of Ecology, Evolution and Marine Biology University of California, Santa Barbara Santa Barbara CA USA
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15
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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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Abstract
The echinoderms are a phylum of invertebrate deuterostome animals that constitute important research models for a number of biological disciplines. EchinoBase ( www.echinobase.org ) is an echinoderm-specific genome database and web information system that provides a platform for the interrogation and exploration of echinoderm genomic data. This chapter outlines the datasets available on EchinoBase; from assembled genomes and genome annotations, to spatial and quantitative expression data, as well as functional genomics datasets. We also highlight the bioinformatic tools available on the website to facilitate rapid inquiries using these data (genome browsers, precompiled BLAST databases, etc.), and suggest optimized strategies for performing these inquiries. We conclude with a perspective on how one could integrate various genomic resources to predict putative noncoding regulatory regions. The available datasets and analyses they permit provide the basic components required for developing an understanding of how echinoderm genomes are regulated, especially during early development, and provides a platform for comparative genomic inquiries among species in this phylum.
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Molina MD, Quirin M, Haillot E, Jimenez F, Chessel A, Lepage T. p38 MAPK as an essential regulator of dorsal-ventral axis specification and skeletogenesis during sea urchin development: a re-evaluation. Development 2017; 144:2270-2281. [PMID: 28507001 DOI: 10.1242/dev.152330] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 05/08/2017] [Indexed: 12/15/2022]
Abstract
Dorsal-ventral axis formation in the sea urchin embryo relies on the asymmetrical expression of the TGFβ Nodal. The p38-MAPK pathway has been proposed to be essential for dorsal-ventral axis formation by acting upstream of nodal expression. Here, we report that, in contrast to previous studies that used pharmacological inhibitors of p38, manipulating the activity of p38 by genetic means has no obvious impact on morphogenesis. Instead, we discovered that p38 inhibitors strongly disrupt specification of all germ layers by blocking signalling from the Nodal receptor and by interfering with the ERK pathway. Strikingly, while expression of a mutant p38 that is resistant to SB203580 did not rescue dorsal-ventral axis formation or skeletogenesis in embryos treated with this inhibitor, expression of mutant Nodal receptors that are resistant to SB203580 fully restored nodal expression in SB203580-treated embryos. Taken together, these results establish that p38 activity is not required for dorsal-ventral axis formation through nodal expression nor for skeletogenesis. Our results prompt a re-evaluation of the conclusions of several recent studies that linked p38 activity to dorsal-ventral axis formation and to patterning of the skeleton.
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Affiliation(s)
| | - Magali Quirin
- Université Côte d'Azur, CNRS, INSERM iBV, 06108 Nice cedex 2, France
| | - Emmanuel Haillot
- Université Côte d'Azur, CNRS, INSERM iBV, 06108 Nice cedex 2, France
| | - Felipe Jimenez
- Université Côte d'Azur, CNRS, INSERM iBV, 06108 Nice cedex 2, France
| | - Aline Chessel
- Université Côte d'Azur, CNRS, INSERM iBV, 06108 Nice cedex 2, France
| | - Thierry Lepage
- Université Côte d'Azur, CNRS, INSERM iBV, 06108 Nice cedex 2, France
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18
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Miccoli A, Dalla Valle L, Carnevali O. The maternal control in the embryonic development of zebrafish. Gen Comp Endocrinol 2017; 245:55-68. [PMID: 27013380 DOI: 10.1016/j.ygcen.2016.03.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 03/16/2016] [Accepted: 03/19/2016] [Indexed: 12/13/2022]
Abstract
The maternal control directing the very first hours of life is of pivotal importance for ensuring proper development to the growing embryo. Thanks to the finely regulated inheritance of maternal factors including mRNAs and proteins produced during oogenesis and stored into the mature oocyte, the embryo is sustained throughout the so-called maternal-to-zygotic transition, a period in development characterized by a species-specific length in time, during which critical biological changes regarding cell cycle and zygotic transcriptional activation occur. In order not to provoke any kind of persistent damage, the process must be delicately balanced. Surprisingly, our knowledge as to the possible effects of beneficial bacteria regarding the modulation of the quality and/or quantity of both maternally-supplied and zygotically-transcribed mRNAs, is very limited. To date, only one group has investigated the consequences of the parentally-supplied Lactobacillus rhamnosus on the storage of mRNAs into mature oocytes, leading to an altered maternal control process in the F1 generation. Particular attention was called on the monitoring of several biomarkers involved in autophagy, apoptosis and axis patterning, while data on miRNA generation and pluripotency maintenance are herein presented for the first time, and can assist in laying the ground for further investigations in this field. In this review, the reader is supplied with the current knowledge on the above-mentioned biological process, first by drawing the general background and then by emphasizing the most important findings that have highlighted their focal role in normal animal development.
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Affiliation(s)
- Andrea Miccoli
- Department of Life and Environmental Sciences, Università Politecnica delle Marche, Ancona, Italy
| | | | - Oliana Carnevali
- Department of Life and Environmental Sciences, Università Politecnica delle Marche, Ancona, Italy.
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19
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Gaitán-Espitia JD, Hofmann GE. Gene expression profiling during the embryo-to-larva transition in the giant red sea urchin Mesocentrotus franciscanus. Ecol Evol 2017; 7:2798-2811. [PMID: 28428870 PMCID: PMC5395446 DOI: 10.1002/ece3.2850] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 01/20/2017] [Accepted: 02/01/2017] [Indexed: 01/24/2023] Open
Abstract
In echinoderms, major morphological transitions during early development are attributed to different genetic interactions and changes in global expression patterns that shape the regulatory program for the specification of embryonic territories. In order more thoroughly to understand these biological and molecular processes, we examined the transcriptome structure and expression profiles during the embryo‐to‐larva transition of a keystone species, the giant red sea urchin Mesocentrotus franciscanus. Using a de novo assembly approach, we obtained 176,885 transcripts from which 60,439 (34%) had significant alignments to known proteins. From these transcripts, ~80% were functionally annotated allowing the identification of ~2,600 functional, structural, and regulatory genes involved in developmental process. Analysis of expression profiles between gastrula and pluteus stages of M. franciscanus revealed 791 differentially expressed genes with 251 GO overrepresented terms. For gastrula, up‐regulated GO terms were mainly linked to cell differentiation and signal transduction involved in cell cycle checkpoints. In the pluteus stage, major GO terms were associated with phosphoprotein phosphatase activity, muscle contraction, and olfactory behavior, among others. Our evolutionary comparative analysis revealed that several of these genes and functional pathways are highly conserved among echinoids, holothuroids, and ophiuroids.
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Affiliation(s)
| | - Gretchen E Hofmann
- Department of Ecology, Evolution and Marine Biology University of California Santa Barbara CA USA
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20
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Yaguchi S, Yaguchi J, Tanaka H. Troponin-I is present as an essential component of muscles in echinoderm larvae. Sci Rep 2017; 7:43563. [PMID: 28272398 PMCID: PMC5341096 DOI: 10.1038/srep43563] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 01/25/2017] [Indexed: 12/16/2022] Open
Abstract
The troponin complex, composed of Troponin-I, Troponin-T and Troponin-C, is an essential mediator of the contraction of striated muscle downstream of calcium signaling in almost all bilaterians. However, in echinoderms and hemichordates, collectively termed Ambulacraria, the components of the troponin complex have never been isolated, thus suggesting that these organisms lost the troponin system during evolution. Here, by analyzing genomic information from sea urchins, we identify the troponin-I gene and isolate its complete mRNA sequence. Using this information, we reveal that the larval muscles express this gene and its translated product and that the protein is definitely a functional molecule expressed in sea urchin larvae by showing that Troponin-I morphants are unable to swallow algae. We conclude that muscular contraction in all bilaterians universally depends on a regulatory system mediated by Troponin-I, which emerged in the common ancestor of bilaterians.
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Affiliation(s)
- Shunsuke Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
| | - Junko Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
| | - Hiroyuki Tanaka
- Faculty of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan
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21
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Range RC, Wei Z. An anterior signaling center patterns and sizes the anterior neuroectoderm of the sea urchin embryo. Development 2016; 143:1523-33. [PMID: 26952978 PMCID: PMC4909856 DOI: 10.1242/dev.128165] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 02/23/2016] [Indexed: 01/17/2023]
Abstract
Anterior signaling centers help specify and pattern the early anterior neuroectoderm (ANE) in many deuterostomes. In sea urchin the ANE is restricted to the anterior of the late blastula stage embryo, where it forms a simple neural territory comprising several types of neurons as well as the apical tuft. Here, we show that during early development, the sea urchin ANE territory separates into inner and outer regulatory domains that express the cardinal ANE transcriptional regulators FoxQ2 and Six3, respectively. FoxQ2 drives this patterning process, which is required to eliminate six3 expression from the inner domain and activate the expression of Dkk3 and sFRP1/5, two secreted Wnt modulators. Dkk3 and low expression levels of sFRP1/5 act additively to potentiate the Wnt/JNK signaling pathway governing the positioning of the ANE territory around the anterior pole, whereas high expression levels of sFRP1/5 antagonize Wnt/JNK signaling. sFRP1/5 and Dkk3 levels are rigidly maintained via autorepressive and cross-repressive interactions with Wnt signaling components and additional ANE transcription factors. Together, these data support a model in which FoxQ2 initiates an anterior patterning center that implements correct size and positions of ANE structures. Comparisons of functional and expression studies in sea urchin, hemichordate and chordate embryos reveal striking similarities among deuterostome ANE regulatory networks and the molecular mechanism that positions and defines ANE borders. These data strongly support the idea that the sea urchin embryo uses an ancient anterior patterning system that was present in the common ambulacrarian/chordate ancestor.
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Affiliation(s)
- Ryan C Range
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zheng Wei
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
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22
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Yaguchi J, Takeda N, Inaba K, Yaguchi S. Cooperative Wnt-Nodal Signals Regulate the Patterning of Anterior Neuroectoderm. PLoS Genet 2016; 12:e1006001. [PMID: 27101101 PMCID: PMC4839626 DOI: 10.1371/journal.pgen.1006001] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 03/30/2016] [Indexed: 11/18/2022] Open
Abstract
When early canonical Wnt is experimentally inhibited, sea urchin embryos embody the concept of a Default Model in vivo because most of the ectodermal cell fates are specified as anterior neuroectoderm. Using this model, we describe here how the combination of orthogonally functioning anteroposterior Wnt and dorsoventral Nodal signals and their targeting transcription factors, FoxQ2 and Homeobrain, regulates the precise patterning of normal neuroectoderm, of which serotonergic neurons are differentiated only at the dorsal/lateral edge. Loss-of-function experiments revealed that ventral Nodal is required for suppressing the serotonergic neural fate in the ventral side of the neuroectoderm through the maintenance of foxQ2 and the repression of homeobrain expression. In addition, non-canonical Wnt suppressed homeobrain in the anterior end of the neuroectoderm, where serotonergic neurons are not differentiated. Canonical Wnt, however, suppresses foxQ2 to promote neural differentiation. Therefore, the three-dimensionally complex patterning of the neuroectoderm is created by cooperative signals, which are essential for the formation of primary and secondary body axes during embryogenesis.
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Affiliation(s)
- Junko Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
| | - Noriyo Takeda
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
| | - Kazuo Inaba
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
| | - Shunsuke Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
- * E-mail:
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23
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Wei Z, Angerer LM, Angerer RC. Neurogenic gene regulatory pathways in the sea urchin embryo. Development 2016; 143:298-305. [PMID: 26657764 PMCID: PMC4725339 DOI: 10.1242/dev.125989] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 11/26/2015] [Indexed: 01/18/2023]
Abstract
During embryogenesis the sea urchin early pluteus larva differentiates 40-50 neurons marked by expression of the pan-neural marker synaptotagmin B (SynB) that are distributed along the ciliary band, in the apical plate and pharyngeal endoderm, and 4-6 serotonergic neurons that are confined to the apical plate. Development of all neurons has been shown to depend on the function of Six3. Using a combination of molecular screens and tests of gene function by morpholino-mediated knockdown, we identified SoxC and Brn1/2/4, which function sequentially in the neurogenic regulatory pathway and are also required for the differentiation of all neurons. Misexpression of Brn1/2/4 at low dose caused an increase in the number of serotonin-expressing cells and at higher dose converted most of the embryo to a neurogenic epithelial sphere expressing the Hnf6 ciliary band marker. A third factor, Z167, was shown to work downstream of the Six3 and SoxC core factors and to define a branch specific for the differentiation of serotonergic neurons. These results provide a framework for building a gene regulatory network for neurogenesis in the sea urchin embryo.
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Affiliation(s)
- Zheng Wei
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lynne M Angerer
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Robert C Angerer
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
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24
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Shipp LE, Hill RZ, Moy GW, Gökırmak T, Hamdoun A. ABCC5 is required for cAMP-mediated hindgut invagination in sea urchin embryos. Development 2015; 142:3537-48. [PMID: 26395488 DOI: 10.1242/dev.126144] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 08/14/2015] [Indexed: 12/31/2022]
Abstract
ATP-binding cassette (ABC) transporters are evolutionarily conserved proteins that pump diverse substrates across membranes. Many are known to efflux signaling molecules and are extensively expressed during development. However, the role of transporters in moving extracellular signals that regulate embryogenesis is largely unexplored. Here, we show that a mesodermal ABCC (MRP) transporter is necessary for endodermal gut morphogenesis in sea urchin embryos. This transporter, Sp-ABCC5a (C5a), is expressed in pigment cells and their precursors, which are a subset of the non-skeletogenic mesoderm (NSM) cells. C5a expression depends on Delta/Notch signaling from skeletogenic mesoderm and is downstream of Gcm in the aboral NSM gene regulatory network. Long-term imaging of development reveals that C5a knockdown embryos gastrulate, but ∼90% develop a prolapse of the hindgut by the late prism stage (∼8 h after C5a protein expression normally peaks). Since C5a orthologs efflux cyclic nucleotides, and cAMP-dependent protein kinase (Sp-CAPK/PKA) is expressed in pigment cells, we examined whether C5a could be involved in gastrulation through cAMP transport. Consistent with this hypothesis, membrane-permeable pCPT-cAMP rescues the prolapse phenotype in C5a knockdown embryos, and causes archenteron hyper-invagination in control embryos. In addition, the cAMP-producing enzyme soluble adenylyl cyclase (sAC) is expressed in pigment cells, and its inhibition impairs gastrulation. Together, our data support a model in which C5a transports sAC-derived cAMP from pigment cells to control late invagination of the hindgut. Little is known about the ancestral functions of ABCC5/MRP5 transporters, and this study reveals a novel role for these proteins in mesoderm-endoderm signaling during embryogenesis.
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Affiliation(s)
- Lauren E Shipp
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0202, USA
| | - Rose Z Hill
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0202, USA
| | - Gary W Moy
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0202, USA
| | - Tufan Gökırmak
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0202, USA
| | - Amro Hamdoun
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0202, USA
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25
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Haillot E, Molina MD, Lapraz F, Lepage T. The Maternal Maverick/GDF15-like TGF-β Ligand Panda Directs Dorsal-Ventral Axis Formation by Restricting Nodal Expression in the Sea Urchin Embryo. PLoS Biol 2015; 13:e1002247. [PMID: 26352141 PMCID: PMC4564238 DOI: 10.1371/journal.pbio.1002247] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 08/05/2015] [Indexed: 01/26/2023] Open
Abstract
Specification of the dorsal-ventral axis in the highly regulative sea urchin embryo critically relies on the zygotic expression of nodal, but whether maternal factors provide the initial spatial cue to orient this axis is not known. Although redox gradients have been proposed to entrain the dorsal-ventral axis by acting upstream of nodal, manipulating the activity of redox gradients only has modest consequences, suggesting that other factors are responsible for orienting nodal expression and defining the dorsal-ventral axis. Here we uncover the function of Panda, a maternally provided transforming growth factor beta (TGF-β) ligand that requires the activin receptor-like kinases (Alk) Alk3/6 and Alk1/2 receptors to break the radial symmetry of the embryo and orient the dorsal-ventral axis by restricting nodal expression. We found that the double inhibition of the bone morphogenetic protein (BMP) type I receptors Alk3/6 and Alk1/2 causes a phenotype dramatically more severe than the BMP2/4 loss-of-function phenotype, leading to extreme ventralization of the embryo through massive ectopic expression of nodal, suggesting that an unidentified signal acting through BMP type I receptors cooperates with BMP2/4 to restrict nodal expression. We identified this ligand as the product of maternal Panda mRNA. Double inactivation of panda and bmp2/4 led to extreme ventralization, mimicking the phenotype caused by inactivation of the two BMP receptors. Inhibition of maternal panda mRNA translation disrupted the early spatial restriction of nodal, leading to persistent massive ectopic expression of nodal on the dorsal side despite the presence of Lefty. Phylogenetic analysis indicates that Panda is not a prototypical BMP ligand but a member of a subfamily of TGF-β distantly related to Inhibins, Lefty, and TGF-β that includes Maverick from Drosophila and GDF15 from vertebrates. Indeed, overexpression of Panda does not appear to directly or strongly activate phosphoSmad1/5/8 signaling, suggesting that although this TGF-β may require Alk1/2 and/or Alk3/6 to antagonize nodal expression, it may do so by sequestering a factor essential for Nodal signaling, by activating a non-Smad pathway downstream of the type I receptors, or by activating extremely low levels of pSmad1/5/8. We provide evidence that, although panda mRNA is broadly distributed in the early embryo, local expression of panda mRNA efficiently orients the dorsal-ventral axis and that Panda activity is required locally in the early embryo to specify this axis. Taken together, these findings demonstrate that maternal panda mRNA is both necessary and sufficient to orient the dorsal-ventral axis. These results therefore provide evidence that in the highly regulative sea urchin embryo, the activity of spatially restricted maternal factors regulates patterning along the dorsal-ventral axis.
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Affiliation(s)
- Emmanuel Haillot
- Institut de Biologie Valrose, iBV, UMR 7277 CNRS, Inserm U1091, UNS, University of Nice Sophia Antipolis, Nice, France
| | - Maria Dolores Molina
- Institut de Biologie Valrose, iBV, UMR 7277 CNRS, Inserm U1091, UNS, University of Nice Sophia Antipolis, Nice, France
| | - François Lapraz
- Institut de Biologie Valrose, iBV, UMR 7277 CNRS, Inserm U1091, UNS, University of Nice Sophia Antipolis, Nice, France
| | - Thierry Lepage
- Institut de Biologie Valrose, iBV, UMR 7277 CNRS, Inserm U1091, UNS, University of Nice Sophia Antipolis, Nice, France
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26
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Abstract
With few exceptions, all animals acquire the ability to produce eggs or sperm at some point in their life cycle. Despite this near-universal requirement for sexual reproduction, there exists an incredible diversity in germ line development. For example, animals exhibit a vast range of differences in the timing at which the germ line, which retains reproductive potential, separates from the soma, or terminally differentiated, nonreproductive cells. This separation may occur during embryonic development, after gastrulation, or even in adults, depending on the organism. The molecular mechanisms of germ line segregation are also highly diverse, and intimately intertwined with the overall transition from a fertilized egg to an embryo. The earliest embryonic stages of many species are largely controlled by maternally supplied factors. Later in development, patterning control shifts to the embryonic genome and, concomitantly with this transition, the maternally supplied factors are broadly degraded. This chapter attempts to integrate these processes--germ line segregation, and how the divergence of germ line and soma may utilize the egg to embryo transitions differently. In some embryos, this difference is subtle or maybe lacking altogether, whereas in other embryos, this difference in utilization may be a key step in the divergence of the two lineages. Here, we will focus our discussion on the echinoderms, and in particular the sea urchins, in which recent studies have provided mechanistic understanding in germ line determination. We propose that the germ line in sea urchins requires an acquisition of maternal factors from the egg and, when compared to other members of the taxon, this appears to be a derived mechanism. The acquisition is early--at the 32-cell stage--and involves active protection of maternal mRNAs, which are instead degraded in somatic cells with the maternal-to-embryonic transition. We collectively refer to this model as the Time Capsule method for germ line determination.
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Affiliation(s)
- S Zachary Swartz
- Department of Molecular and Cellular Biology, Brown University, Providence, Rhode Island, USA
| | - Gary M Wessel
- Department of Molecular and Cellular Biology, Brown University, Providence, Rhode Island, USA.
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27
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Abstract
In mature gametes and during the oocyte-to-embryo transition, transcription is generally silenced and gene expression is post-transcriptionally regulated. However, we recently discovered that major transcription can occur immediately after fertilization, prior to pronuclear fusion, and in the first cell division of the oocyte-to-embryo transition in the nematode Ascaris suum. We postulate that the balance between transcriptional and post-transcriptional regulation during the oocyte-to-embryo transition may largely be determined by cell cycle length and thus the time available for the genome to be transcribed.
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Affiliation(s)
- Jianbin Wang
- a Department of Biochemistry and Molecular Genetics ; University of Colorado School of Medicine ; Aurora , CO USA
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28
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Burke RD, Moller DJ, Krupke OA, Taylor VJ. Sea urchin neural development and the metazoan paradigm of neurogenesis. Genesis 2014; 52:208-21. [PMID: 25368883 DOI: 10.1002/dvg.22750] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Summary:Urchin embryos continue to prove useful as a means of studying embryonic signaling and gene regulatory networks, which together control early development. Recent progress in understanding the molecular mechanisms underlying the patterning of ectoderm has renewed interest in urchin neurogenesis. We have employed an emerging model of neurogenesis that appears to be broadly shared by metazoans as a framework for this review. We use the model to provide context and summarize what is known about neurogenesis in urchin embryos. We review morphological features of the differentiation phase of neurogenesis and summarize current understanding of neural specification and regulation of proneural networks. Delta-Notch signaling is a common feature of metazoan neurogenesis that produces committed progenitors and it appears to be a critical phase of neurogenesis in urchin embryos. Descriptions of the differentiation phase of neurogenesis indicate a stereotypic sequence of neural differentiation and patterns of axonal growth. Features of neural differentiation are consistent with localized signals guiding growth cones with trophic, adhesive, and tropic cues. Urchins are a facile, postgenomic model with the potential of revealing many shared and derived features of deuterostome neurogenesis.
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Affiliation(s)
- Robert D Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC Canada
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29
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Yaguchi S, Yaguchi J, Inaba K. bicaudal-C is required for the formation of anterior neurogenic ectoderm in the sea urchin embryo. Sci Rep 2014; 4:6852. [PMID: 25358387 PMCID: PMC4215294 DOI: 10.1038/srep06852] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/10/2014] [Indexed: 02/07/2023] Open
Abstract
bicaudal-C (bicC) mRNA encodes a protein containing RNA-binding domains that is reported to be maternally present with deflection in the oocytes/eggs of some species. The translated protein plays a critical role in the regulation of cell fate specification along the body axis during early embryogenesis in flies and frogs. However, it is unclear how it functions in eggs in which bicC mRNA is uniformly distributed, for instance, sea urchin eggs. Here, we show the function of BicC in the formation of neurogenic ectoderm of the sea urchin embryo. Loss-of-function experiments reveal that BicC is required for serotonergic neurogenesis and for expression of ankAT-1 gene, which is essential for the formation of apical tuft cilia in the neurogenic ectoderm of the sea urchin embryo. In contrast, the expression of FoxQ2, the neurogenic ectoderm specification transcription factor, is invariant in BicC morphants. Because FoxQ2 is an upstream factor of serotonergic neurogenesis and ankAT-1 expression, these data indicate that BicC functions in regulating the events that are coordinated by FoxQ2 during sea urchin embryogenesis.
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Affiliation(s)
- Shunsuke Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
- Japanese Association for Marine Biology (JAMBIO)
| | - Junko Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
- JSPS
| | - Kazuo Inaba
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
- Japanese Association for Marine Biology (JAMBIO)
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Lee MT, Bonneau AR, Giraldez AJ. Zygotic genome activation during the maternal-to-zygotic transition. Annu Rev Cell Dev Biol 2014; 30:581-613. [PMID: 25150012 DOI: 10.1146/annurev-cellbio-100913-013027] [Citation(s) in RCA: 384] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Embryogenesis depends on a highly coordinated cascade of genetically encoded events. In animals, maternal factors contributed by the egg cytoplasm initially control development, whereas the zygotic nuclear genome is quiescent. Subsequently, the genome is activated, embryonic gene products are mobilized, and maternal factors are cleared. This transfer of developmental control is called the maternal-to-zygotic transition (MZT). In this review, we discuss recent advances toward understanding the scope, timing, and mechanisms that underlie zygotic genome activation at the MZT in animals. We describe high-throughput techniques to measure the embryonic transcriptome and explore how regulation of the cell cycle, chromatin, and transcription factors together elicits specific patterns of embryonic gene expression. Finally, we illustrate the interplay between zygotic transcription and maternal clearance and show how these two activities combine to reprogram two terminally differentiated gametes into a totipotent embryo.
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Affiliation(s)
- Miler T Lee
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06520; ,
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Swartz SZ, Reich AM, Oulhen N, Raz T, Milos PM, Campanale JP, Hamdoun A, Wessel GM. Deadenylase depletion protects inherited mRNAs in primordial germ cells. Development 2014; 141:3134-42. [PMID: 25100654 PMCID: PMC4197533 DOI: 10.1242/dev.110395] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 06/22/2014] [Indexed: 12/12/2022]
Abstract
A crucial event in animal development is the specification of primordial germ cells (PGCs), which become the stem cells that create sperm and eggs. How PGCs are created provides a valuable paradigm for understanding stem cells in general. We find that the PGCs of the sea urchin Strongylocentrotus purpuratus exhibit broad transcriptional repression, yet enrichment for a set of inherited mRNAs. Enrichment of several germline determinants in the PGCs requires the RNA-binding protein Nanos to target the transcript that encodes CNOT6, a deadenylase, for degradation in the PGCs, thereby creating a stable environment for RNA. Misexpression of CNOT6 in the PGCs results in their failure to retain Seawi transcripts and Vasa protein. Conversely, broad knockdown of CNOT6 expands the domain of Seawi RNA as well as exogenous reporters. Thus, Nanos-dependent spatially restricted CNOT6 differential expression is used to selectively localize germline RNAs to the PGCs. Our findings support a 'time capsule' model of germline determination, whereby the PGCs are insulated from differentiation by retaining the molecular characteristics of the totipotent egg and early embryo.
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Affiliation(s)
- S Zachary Swartz
- Department of Molecular, Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Adrian M Reich
- Department of Molecular, Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Nathalie Oulhen
- Department of Molecular, Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Tal Raz
- Helicos BioSciences Corporation, One Kendall Square, Building 700, Cambridge, MA 02139, USA
| | - Patrice M Milos
- Helicos BioSciences Corporation, One Kendall Square, Building 700, Cambridge, MA 02139, USA
| | - Joseph P Campanale
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California at San Diego, 8750 Biological Grade Road, La Jolla, CA 92037, USA
| | - Amro Hamdoun
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California at San Diego, 8750 Biological Grade Road, La Jolla, CA 92037, USA
| | - Gary M Wessel
- Department of Molecular, Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA
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Zazueta-Novoa V, Wessel GM. Protein degradation machinery is present broadly during early development in the sea urchin. Gene Expr Patterns 2014; 15:135-41. [PMID: 24963879 DOI: 10.1016/j.gep.2014.06.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 06/03/2014] [Accepted: 06/05/2014] [Indexed: 11/29/2022]
Abstract
Ubiquitin-dependent proteosome-mediated proteolysis is an important pathway of degradation that controls the timed destruction of cellular proteins in all tissues. All intracellular proteins and many extracellular proteins are continually being hydrolyzed to their constituent amino acids as a result of their recognition by E3 ligases for specific targeting of ubiquitination. Gustavus is a member of an ECS-type E3 ligase which interacts with Vasa, a DEAD-box RNA helicase, to regulate its localization during sea urchin embryonic development, and Gustavus mRNA accumulation is highly localized and dynamic during development. We tested if the core complex for Gustavus function was present in the embryo and if other SOCS box proteins also had restricted expression profiles that would inform future research. Expression patterns of the key members of the proteasomal function, such as the E3 core complex which interacts with Gustavus, and other E3-SOCS box proteins, are widely spread and dynamic in early development of the embryo suggesting broad core complex availability in the proteasome degradation pathway and temporal/spatial enrichments of various E3 ligase dependent targeting mechanisms.
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Affiliation(s)
- Vanesa Zazueta-Novoa
- Department of Molecular and Cellular Biology & Biochemistry, Brown University, Providence, RI 02912, USA
| | - Gary M Wessel
- Department of Molecular and Cellular Biology & Biochemistry, Brown University, Providence, RI 02912, USA.
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Evans TG, Watson-Wynn P. Effects of seawater acidification on gene expression: resolving broader-scale trends in sea urchins. THE BIOLOGICAL BULLETIN 2014; 226:237-254. [PMID: 25070868 DOI: 10.1086/bblv226n3p237] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Sea urchins are ecologically and economically important calcifying organisms threatened by acidification of the global ocean caused by anthropogenic CO2 emissions. Propelled by the sequencing of the purple sea urchin (Strongylocentrotus purpuratus) genome, profiling changes in gene expression during exposure to high pCO2 seawater has emerged as a powerful and increasingly common method to infer the response of urchins to ocean change. However, analyses of gene expression are sensitive to experimental methodology, and comparisons between studies of genes regulated by ocean acidification are most often made in the context of major caveats. Here we perform meta-analyses as a means of minimizing experimental discrepancies and resolving broader-scale trends regarding the effects of ocean acidification on gene expression in urchins. Analyses across eight studies and four urchin species largely support prevailing hypotheses about the impact of ocean acidification on marine calcifiers. The predominant expression pattern involved the down-regulation of genes within energy-producing pathways, a clear indication of metabolic depression. Genes with functions in ion transport were significantly over-represented and are most plausibly contributing to intracellular pH regulation. Expression profiles provided extensive evidence for an impact on biomineralization, epitomized by the down-regulation of seven spicule matrix proteins. In contrast, expression profiles provided limited evidence for CO2-mediated developmental delay or induction of a cellular stress response. Congruence between studies of gene expression and the ocean acidification literature in general validates the accuracy of gene expression in predicting the consequences of ocean change and justifies its continued use in future studies.
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Affiliation(s)
- Tyler G Evans
- Department of Biological Sciences, California State University East Bay, Hayward, California 94542
| | - Priscilla Watson-Wynn
- Department of Biological Sciences, California State University East Bay, Hayward, California 94542
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Transcriptome information of the Arctic green sea urchin and its use in environmental monitoring. Polar Biol 2014. [DOI: 10.1007/s00300-014-1507-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Fischer AHL, Pang K, Henry JQ, Martindale MQ. A cleavage clock regulates features of lineage-specific differentiation in the development of a basal branching metazoan, the ctenophore Mnemiopsis leidyi. EvoDevo 2014; 5:4. [PMID: 24485336 PMCID: PMC3909359 DOI: 10.1186/2041-9139-5-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 11/20/2013] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND An important question in experimental embryology is to understand how the developmental potential responsible for the generation of distinct cell types is spatially segregated over developmental time. Classical embryological work showed that ctenophores, a group of gelatinous marine invertebrates that arose early in animal evolution, display a highly stereotyped pattern of early development and a precocious specification of blastomere fates. Here we investigate the role of autonomous cell specification and the developmental timing of two distinct ctenophore cell types (motile compound comb-plate-like cilia and light-emitting photocytes) in embryos of the lobate ctenophore, Mnemiopsis leidyi. RESULTS In Mnemiopsis, 9 h after fertilization, comb plate cilia differentiate into derivatives of the E lineage, while the bioluminescent capability begins in derivatives of the M lineage. Arresting cleavage with cytochalasin B at the 1-, 2- or 4-cell stage does not result in blastomere death; however, no visible differentiation of the comb-plate-like cilia or bioluminescence was observed. Cleavage arrest at the 8- or 16-cell stage, in contrast, results in the expression of both differentiation products. Fate-mapping experiments indicate that only the lineages of cells that normally express these markers in an autonomous fashion during normal development express these traits in cleavage-arrested 8- and 16-cell stage embryos. Lineages that form comb plates in a non-autonomous fashion (derivatives of the M lineage) do not. Timed actinomycin D and puromycin treatments show that transcription and translation are required for comb formation and suggest that the segregated material might be necessary for activation of the appropriate genes. Interestingly, even in the absence of cytokinesis, differentiation markers appear to be activated at the correct times. Treatments with a DNA synthesis inhibitor, aphidicolin, show that the number of nuclear divisions, and perhaps the DNA to cytoplasmic ratio, are critical for the appearance of lineage-specific differentiation. CONCLUSION Our work corroborates previous studies demonstrating that the cleavage program is causally involved in the spatial segregation and/or activation of factors that give rise to distinct cell types in ctenophore development. These factors are segregated independently to the appropriate lineage at the 8- and the 16-cell stages and have features of a clock, such that comb-plate-like cilia and light-emitting photoproteins appear at roughly the same developmental time in cleavage-arrested embryos as they do in untreated embryos. Nuclear division, which possibly affects DNA-cytoplasmic ratios, appears to be important in the timing of differentiation markers. Evidence suggests that the 60-cell stage, just prior to gastrulation, is the time of zygotic gene activation. Such cleavage-clock-regulated phenomena appear to be widespread amongst the Metazoa and these cellular and molecular developmental mechanisms probably evolved early in metazoan evolution.
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Affiliation(s)
- Antje HL Fischer
- Developmental Biology Unit, European Molecular Biology Laboratory Heidelberg, Meyerhof Strasse 1, Heidelberg 69117, Germany
- current address: Molecular and Cell Biology Department, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Kevin Pang
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawaii at Manoa, Honolulu, HI, USA
- current address: Sars International Centre for Marine Molecular Biology, Thormøhlensgt. 55, Bergen N-5008, Norway
| | - Jonathan Q Henry
- Department of Cell and Structural Biology, University of Illinois, 601 S. Goodwin Ave, Urbana, IL 61801, USA
| | - Mark Q Martindale
- Whitney Lab for Marine Bioscience, Univ. Florida, 9505 Oceanshore Blvd, St, Augustine, FL 32080, USA
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Abstract
The Sea Urchin Genome Project Web site, SpBase ( http://SpBase.org ), in association with a suite of publicly available sequence comparison tools provides a platform from which to analyze genes and genomic sequences of sea urchin. This information system is specifically designed to support laboratory bench studies in cell and molecular biology. In particular these tools and datasets have supported the description of the gene regulatory networks of the purple sea urchin S. purpuratus. This chapter details methods to undertake in the first steps to find genes and noncoding regulatory sequences for further analysis.
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Affiliation(s)
- R Andrew Cameron
- Center for Computational Regulatory Genomics, Beckman Institute, Caltech, Pasadena, CA, USA
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Matsuoka T, Ikeda T, Fujimaki K, Satou Y. Transcriptome dynamics in early embryos of the ascidian, Ciona intestinalis. Dev Biol 2013; 384:375-85. [PMID: 24120375 DOI: 10.1016/j.ydbio.2013.10.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 09/20/2013] [Accepted: 10/03/2013] [Indexed: 11/25/2022]
Abstract
Maternally provided mRNAs and proteins direct early development and activate the zygotic genome. Using microarrays, we examined the dynamics of transcriptomes during the early development of a basal chordate, Ciona intestinalis. Microarray analysis of unfertilized eggs, as well as 8-, and 16- and 32-cell embryos revealed that nearly half of the genes encoded in the genome were expressed maternally, and that approximately only one-fourth of these genes were expressed at similar levels among eggs obtained from different individuals. Genes encoding proteins involved in protein phosphorylation were enriched in this latter group. More than 90% of maternal RNAs were not reduced before the 16-cell stage when the zygotic developmental program begins. Additionally we obtained gene expression profiles of individual blastomeres from the 8- and 16-cell embryos. On the basis of these profiles, we concluded that the posterior-most localization, which has been reported for over 20 different transcripts, is the only major localization pattern of maternal transcripts. Our data also showed that maternal factors establish only nine distinct patterns of zygotic gene expression at the 16-cell stage. Therefore, one of the main developmental functions of maternally supplied information is to establish these nine distinct expression patterns in the 16-cell embryo. The dynamics of transcriptomes in early-stage embryos provides a foundation for studying how maternal information starts the zygotic program.
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Affiliation(s)
- Terumi Matsuoka
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
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Genome-wide patterns of codon bias are shaped by natural selection in the purple sea urchin, Strongylocentrotus purpuratus. G3-GENES GENOMES GENETICS 2013; 3:1069-83. [PMID: 23637123 PMCID: PMC3704236 DOI: 10.1534/g3.113.005769] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Codon usage bias has been documented in a wide diversity of species, but the relative contributions of mutational bias and various forms of natural selection remain unclear. Here, we describe for the first time genome-wide patterns of codon bias at 4623 genes in the purple sea urchin, Strongylocentrotus purpuratus. Preferred codons were identified at 18 amino acids that exclusively used G or C at third positions, which contrasted with the strong AT bias of the genome (overall GC content is 36.9%). The GC content of third positions and coding regions exhibited significant correlations with the magnitude of codon bias. In contrast, the GC content of introns and flanking regions was indistinguishable from the genome-wide background, which suggested a limited contribution of mutational bias to synonymous codon usage. Five distinct clusters of genes were identified that had significantly different synonymous codon usage patterns. A significant correlation was observed between codon bias and mRNA expression supporting translational selection, but this relationship was driven by only one highly biased cluster that represented only 8.6% of all genes. In all five clusters preferred codons were evolutionarily conserved to a similar degree despite differences in their synonymous codon usage distributions and magnitude of codon bias. The third positions of preferred codons in two codon usage groups also paired significantly more often in stems than in loops of mRNA secondary structure predictions, which suggested that codon bias might also affect mRNA stability. Our results suggest that mutational bias has played a minor role in determining codon bias in S. purpuratus and that preferred codon usage may be heterogeneous across different genes and subject to different forms of natural selection.
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Range RC, Angerer RC, Angerer LM. Integration of canonical and noncanonical Wnt signaling pathways patterns the neuroectoderm along the anterior-posterior axis of sea urchin embryos. PLoS Biol 2013; 11:e1001467. [PMID: 23335859 PMCID: PMC3545869 DOI: 10.1371/journal.pbio.1001467] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 11/29/2012] [Indexed: 11/29/2022] Open
Abstract
Three different Wnt signaling pathways function to restrict the anterior neuroectoderm state to the anterior end of the sea urchin embryo, a mechanism of anterior fate restriction that could be conserved among deuterostomes. Patterning the neuroectoderm along the anterior–posterior (AP) axis is a critical event in the early development of deuterostome embryos. However, the mechanisms that regulate the specification and patterning of the neuroectoderm are incompletely understood. Remarkably, the anterior neuroectoderm (ANE) of the deuterostome sea urchin embryo expresses many of the same transcription factors and secreted modulators of Wnt signaling, as does the early vertebrate ANE (forebrain/eye field). Moreover, as is the case in vertebrate embryos, confining the ANE to the anterior end of the embryo requires a Wnt/β-catenin-dependent signaling mechanism. Here we use morpholino- or dominant negative-mediated interference to demonstrate that the early sea urchin embryo integrates information not only from Wnt/β-catenin but also from Wnt/Fzl5/8-JNK and Fzl1/2/7-PKC pathways to provide precise spatiotemporal control of neuroectoderm patterning along its AP axis. Together, through the Wnt1 and Wnt8 ligands, they orchestrate a progressive posterior-to-anterior wave of re-specification that restricts the initial, ubiquitous, maternally specified, ANE regulatory state to the most anterior blastomeres. There, the Wnt receptor antagonist, Dkk1, protects this state through a negative feedback mechanism. Because these different Wnt pathways converge on the same cell fate specification process, our data suggest they may function as integrated components of an interactive Wnt signaling network. Our findings provide strong support for the idea that the sea urchin ANE regulatory state and the mechanisms that position and define its borders represent an ancient regulatory patterning system that was present in the common echinoderm/vertebrate ancestor. The initial regulatory state of most cells in many deuterostome embryos, including those of vertebrates and sea urchins, supports anterior neural fate specification. It is important to restrict this neurogenic potential to the anterior end of the embryo during early embryogenesis, but the molecular mechanisms by which this re-specification of posterior fate occurs are incompletely understood in any embryo. The sea urchin embryo is ideally suited to study this process because, in contrast to vertebrates, anterior–posterior neuroectoderm patterning occurs independently of dorsal-ventral axis patterning and takes place before the complex cell movements of gastrulation. In this study, we show that a linked, three-step process involving at least three different Wnt signaling pathways provides precise spatiotemporal restriction of the anterior neuroectoderm regulatory state to the anterior end of the sea urchin embryo. Because these three pathways impinge on the same developmental process, they could be functioning as an integrated Wnt signaling network. Moreover, striking parallels among gene expression patterns and functional studies suggest that this mechanism of anterior fate restriction could be highly conserved among deuterostomes.
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Affiliation(s)
- Ryan C. Range
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Robert C. Angerer
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lynne M. Angerer
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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Yajima M, Fairbrother WG, Wessel GM. ISWI contributes to ArsI insulator function in development of the sea urchin. Development 2012; 139:3613-22. [PMID: 22949616 DOI: 10.1242/dev.081828] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Insulators are genomic elements that regulate transcriptional activity by forming chromatin boundaries. Various DNA insulators have been identified or are postulated in many organisms, and the paradigmatic CTCF-dependent insulators are perhaps the best understood and most widespread in function. The diversity of DNA insulators is, however, understudied, especially in the context of embryonic development, when many new gene territories undergo transitions in functionality. Here we report the functional analysis of the arylsulfatase insulator (ArsI) derived from the sea urchin, which has conserved insulator activity throughout the many metazoans tested, but for which the molecular mechanism of function is unknown. Using a rapid in vivo assay system and a high-throughput mega-shift assay, we identified a minimal region in ArsI that is responsible for its insulator function. We discovered a small set of proteins specifically bound to the minimal ArsI region, including ISWI, a known chromatin-remodeling protein. During embryogenesis, ISWI was found to interact with select ArsI sites throughout the genome, and when inactivated led to misregulation of select gene expression, loss of insulator activity and aberrant morphogenesis. These studies reveal a mechanistic basis for ArsI function in the gene regulatory network of early development.
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Affiliation(s)
- Mamiko Yajima
- MCB Department, Brown University, 185 Meeting Street, BOX-GL173, Providence, RI 02912, USA.
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Hammond LM, Hofmann GE. Early developmental gene regulation in Strongylocentrotus purpuratus embryos in response to elevated CO₂ seawater conditions. ACTA ACUST UNITED AC 2012; 215:2445-54. [PMID: 22723484 DOI: 10.1242/jeb.058008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ocean acidification, or the increased uptake of CO(2) by the ocean due to elevated atmospheric CO(2) concentrations, may variably impact marine early life history stages, as they may be especially susceptible to changes in ocean chemistry. Investigating the regulatory mechanisms of early development in an environmental context, or ecological development, will contribute to increased understanding of potential organismal responses to such rapid, large-scale environmental changes. We examined transcript-level responses to elevated seawater CO(2) during gastrulation and the initiation of spiculogenesis, two crucial developmental processes in the purple sea urchin, Strongylocentrotus purpuratus. Embryos were reared at the current, accepted oceanic CO(2) concentration of 380 microatmospheres (μatm), and at the elevated levels of 1000 and 1350 μatm, simulating predictions for oceans and upwelling regions, respectively. The seven genes of interest comprised a subset of pathways in the primary mesenchyme cell gene regulatory network (PMC GRN) shown to be necessary for the regulation and execution of gastrulation and spiculogenesis. Of the seven genes, qPCR analysis indicated that elevated CO(2) concentrations only had a significant but subtle effect on two genes, one important for early embryo patterning, Wnt8, and the other an integral component in spiculogenesis and biomineralization, SM30b. Protein levels of another spicule matrix component, SM50, demonstrated significant variable responses to elevated CO(2). These data link the regulation of crucial early developmental processes with the environment that these embryos would be developing within, situating the study of organismal responses to ocean acidification in a developmental context.
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Affiliation(s)
- LaTisha M Hammond
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106-9620, USA.
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42
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Paps J, Holland PWH, Shimeld SM. A genome-wide view of transcription factor gene diversity in chordate evolution: less gene loss in amphioxus? Brief Funct Genomics 2012; 11:177-86. [PMID: 22441554 DOI: 10.1093/bfgp/els012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Previous studies of gene diversity in the homeobox superclass have shown that the Florida amphioxus Branchiostoma floridae has undergone remarkably little gene family loss. Here we use a combined BLAST and HMM search strategy to assess the family level diversity of four other transcription factor superclasses: the Paired/Pax genes, Tbx genes, Fox genes and Sox genes. We apply this across genomes from five chordate taxa, including B. floridae and Ciona intestinalis, plus two outgroup taxa. Our results show scattered gene family loss. However, as also found for homeobox genes, B. floridae has retained all ancient Pax, Tbx, Fox and Sox gene families that were present in the common ancestor of living chordates. We conclude that, at least in terms of transcription factor gene complexity, the genome of amphioxus has experienced remarkable stasis compared to the genomes of other chordates.
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Affiliation(s)
- Jordi Paps
- Department of Zoology, University of Oxford, UK
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Vaughn R, Garnhart N, Garey JR, Thomas WK, Livingston BT. Sequencing and analysis of the gastrula transcriptome of the brittle star Ophiocoma wendtii. EvoDevo 2012; 3:19. [PMID: 22938175 PMCID: PMC3492025 DOI: 10.1186/2041-9139-3-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 07/13/2012] [Indexed: 01/22/2023] Open
Abstract
UNLABELLED BACKGROUND The gastrula stage represents the point in development at which the three primary germ layers diverge. At this point the gene regulatory networks that specify the germ layers are established and the genes that define the differentiated states of the tissues have begun to be activated. These networks have been well-characterized in sea urchins, but not in other echinoderms. Embryos of the brittle star Ophiocoma wendtii share a number of developmental features with sea urchin embryos, including the ingression of mesenchyme cells that give rise to an embryonic skeleton. Notable differences are that no micromeres are formed during cleavage divisions and no pigment cells are formed during development to the pluteus larval stage. More subtle changes in timing of developmental events also occur. To explore the molecular basis for the similarities and differences between these two echinoderms, we have sequenced and characterized the gastrula transcriptome of O. wendtii. METHODS Development of Ophiocoma wendtii embryos was characterized and RNA was isolated from the gastrula stage. A transcriptome data base was generated from this RNA and was analyzed using a variety of methods to identify transcripts expressed and to compare those transcripts to those expressed at the gastrula stage in other organisms. RESULTS Using existing databases, we identified brittle star transcripts that correspond to 3,385 genes, including 1,863 genes shared with the sea urchin Strongylocentrotus purpuratus gastrula transcriptome. We characterized the functional classes of genes present in the transcriptome and compared them to those found in this sea urchin. We then examined those members of the germ-layer specific gene regulatory networks (GRNs) of S. purpuratus that are expressed in the O. wendtii gastrula. Our results indicate that there is a shared 'genetic toolkit' central to the echinoderm gastrula, a key stage in embryonic development, though there are also differences that reflect changes in developmental processes. CONCLUSIONS The brittle star expresses genes representing all functional classes at the gastrula stage. Brittle stars and sea urchins have comparable numbers of each class of genes and share many of the genes expressed at gastrulation. Examination of the brittle star genes in which sea urchin orthologs are utilized in germ layer specification reveals a relatively higher level of conservation of key regulatory components compared to the overall transcriptome. We also identify genes that were either lost or whose temporal expression has diverged from that of sea urchins.
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Affiliation(s)
- Roy Vaughn
- Department of Biological, Sciences, California State University Long Beach, 1250 Bellflower Blvd, Long Beach, CA 90815, USA.
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44
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Loram J, Bodnar A. Age-related changes in gene expression in tissues of the sea urchin Strongylocentrotus purpuratus. Mech Ageing Dev 2012; 133:338-47. [PMID: 22475988 DOI: 10.1016/j.mad.2012.03.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 03/09/2012] [Accepted: 03/19/2012] [Indexed: 10/28/2022]
Abstract
The life history of sea urchins is fundamentally different from that of traditional models of aging and therefore they provide the opportunity to gain new insight into this complex process. Sea urchins grow indeterminately, reproduce throughout their life span and some species exhibit negligible senescence. Using a microarray and qRT-PCR, age-related changes in gene expression were examined in three tissues (muscle, esophagus and nerve) of the sea urchin species Strongylocentrotus purpuratus. The results indicate age-related changes in gene expression involving many key cellular functions such as the ubiquitin-proteasome pathway, DNA metabolism, signaling pathways and apoptosis. Although there are tissue-specific differences in the gene expression profiles, there are some characteristics that are shared between tissues providing insight into potential mechanisms that promote lack of senescence in these animals. As an example, there is an increase in expression of genes encoding components of the Notch signaling pathway with age in all three tissues and a decrease in expression of the Wnt1 gene in both muscle and nerve. The interplay between the Notch and Wnt pathways may be one mechanism that ensures continued regeneration of tissues with advancing age contributing to the general lack of age-related decline in these animals.
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Affiliation(s)
- Jeannette Loram
- Bermuda Institute of Ocean Sciences, St. George's GE 01, Bermuda
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45
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Pantropic retroviruses as a transduction tool for sea urchin embryos. Proc Natl Acad Sci U S A 2012; 109:5334-9. [PMID: 22431628 DOI: 10.1073/pnas.1117846109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Sea urchins are an important model for experiments at the intersection of development and systems biology, and technical innovations that enhance the utility of this model are of great value. This study explores pantropic retroviruses as a transduction tool for sea urchin embryos, and demonstrates that pantropic retroviruses infect sea urchin embryos with high efficiency and genomically integrate at a copy number of one per cell. We successfully used a self-inactivation strategy to both insert a sea urchin-specific enhancer and disrupt the endogenous viral enhancer. The resulting self-inactivating viruses drive global and persistent gene expression, consistent with genomic integration during the first cell cycle. Together, these data provide substantial proof of principle for transduction technology in sea urchin embryos.
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46
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Yaguchi J, Angerer LM, Inaba K, Yaguchi S. Zinc finger homeobox is required for the differentiation of serotonergic neurons in the sea urchin embryo. Dev Biol 2012; 363:74-83. [PMID: 22210002 PMCID: PMC3288183 DOI: 10.1016/j.ydbio.2011.12.024] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 12/07/2011] [Accepted: 12/13/2011] [Indexed: 12/18/2022]
Abstract
Serotonergic neurons differentiate in the neurogenic animal plate ectoderm of the sea urchin embryo. The regulatory mechanisms that control the specification or differentiation of these neurons in the sea urchin embryo are not yet understood, although, after the genome was sequenced, many genes encoding transcription factors expressed in this region were identified. Here, we report that zinc finger homeobox (zfhx1/z81) is expressed in serotonergic neural precursor cells, using double in situ hybridization screening with a serotonergic neural marker, tryptophan 5-hydroxylase (tph) encoding a serotonin synthase that is required for the differentiation of serotonergic neurons. zfhx1/z81 begins to be expressed at gastrula stage in individual cells in the anterior neuroectoderm, some of which also express delta. zfhx1/z81 expression gradually disappears as neural differentiation begins with tph expression. When the translation of Zfhx1/Z81 is blocked by morpholino injection, embryos express neither tph nor the neural marker synaptotagminB in cells of the animal plate, and serotonergic neurons do not differentiate. In contrast, Zfhx1/Z81 morphants do express fez, another neural precursor marker, which appears to function in the initial phase of specification/differentiation of serotonergic neurons. In addition, zfhx1/z81 is one of the targets suppressed in the animal plate by anti-neural signals such as Nodal as well as Delta-Notch. We conclude that Zfhx1/Z81 functions during the specification of individual anterior neural precursors and promotes the expression of tph and synaptotagminB, required for the differentiation of serotonergic neurons.
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Affiliation(s)
- Junko Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
- Initiative for the Promotion of Young Scientists’ Independent Research, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
| | - Lynne M. Angerer
- Developmental Mechanisms Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, 30 Convent Dr. MSC 4326, Bethesda, MD 20892, USA
| | - Kazuo Inaba
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
| | - Shunsuke Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
- Initiative for the Promotion of Young Scientists’ Independent Research, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
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47
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Veldhoen N, Ikonomou MG, Helbing CC. Molecular profiling of marine fauna: integration of omics with environmental assessment of the world's oceans. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2012; 76:23-38. [PMID: 22036265 DOI: 10.1016/j.ecoenv.2011.10.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 09/16/2011] [Accepted: 10/06/2011] [Indexed: 05/31/2023]
Abstract
Many species that contribute to the commercial and ecological richness of our marine ecosystems are harbingers of environmental change. The ability of organisms to rapidly detect and respond to changes in the surrounding environment represents the foundation for application of molecular profiling technologies towards marine sentinel species in an attempt to identify signature profiles that may reside within the transcriptome, proteome, or metabolome and that are indicative of a particular environmental exposure event. The current review highlights recent examples of the biological information obtained for marine sentinel teleosts, mammals, and invertebrates. While in its infancy, such basal information can provide a systems biology framework in the detection and evaluation of environmental chemical contaminant effects on marine fauna. Repeated evaluation across different seasons and local marine environs will lead to discrimination between signature profiles representing normal variation within the complex milieu of environmental factors that trigger biological response in a given sentinel species and permit a greater understanding of normal versus anthropogenic-associated modulation of biological pathways, which prove detrimental to marine fauna. It is anticipated that incorporation of contaminant-specific molecular signatures into current risk assessment paradigms will lead to enhanced wildlife management strategies that minimize the impacts of our industrialized society on marine ecosystems.
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Affiliation(s)
- Nik Veldhoen
- Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 3055 Stn CSC, Victoria, B.C., Canada
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48
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Pespeni MH, Garfield DA, Manier MK, Palumbi SR. Genome-wide polymorphisms show unexpected targets of natural selection. Proc Biol Sci 2011; 279:1412-20. [PMID: 21993504 DOI: 10.1098/rspb.2011.1823] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Natural selection can act on all the expressed genes of an individual, leaving signatures of genetic differentiation or diversity at many loci across the genome. New power to assay these genome-wide effects of selection comes from associating multi-locus patterns of polymorphism with gene expression and function. Here, we performed one of the first genome-wide surveys in a marine species, comparing purple sea urchins, Strongylocentrotus purpuratus, from two distant locations along the species' wide latitudinal range. We examined 9112 polymorphic loci from upstream non-coding and coding regions of genes for signatures of selection with respect to gene function and tissue- and ontogenetic gene expression. We found that genetic differentiation (F(ST)) varied significantly across functional gene classes. The strongest enrichment occurred in the upstream regions of E3 ligase genes, enzymes known to regulate protein abundance during development and environmental stress. We found enrichment for high heterozygosity in genes directly involved in immune response, particularly NALP genes, which mediate pro-inflammatory signals during bacterial infection. We also found higher heterozygosity in immune genes in the southern population, where disease incidence and pathogen diversity are greater. Similar to the major histocompatibility complex in mammals, balancing selection may enhance genetic diversity in the innate immune system genes of this invertebrate. Overall, our results show that how genome-wide polymorphism data coupled with growing databases on gene function and expression can combine to detect otherwise hidden signals of selection in natural populations.
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Affiliation(s)
- Melissa H Pespeni
- Department of Biology, Hopkins Marine Station, Stanford University, Oceanview Boulevard, Pacific Grove, CA 93950, USA.
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Angerer LM, Yaguchi S, Angerer RC, Burke RD. The evolution of nervous system patterning: insights from sea urchin development. Development 2011; 138:3613-23. [PMID: 21828090 PMCID: PMC3152920 DOI: 10.1242/dev.058172] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recent studies of the sea urchin embryo have elucidated the mechanisms that localize and pattern its nervous system. These studies have revealed the presence of two overlapping regions of neurogenic potential at the beginning of embryogenesis, each of which becomes progressively restricted by separate, yet linked, signals, including Wnt and subsequently Nodal and BMP. These signals act to specify and localize the embryonic neural fields - the anterior neuroectoderm and the more posterior ciliary band neuroectoderm - during development. Here, we review these conserved nervous system patterning signals and consider how the relationships between them might have changed during deuterostome evolution.
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Affiliation(s)
- Lynne M Angerer
- National Institute for Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.
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50
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Yaguchi S, Yaguchi J, Wei Z, Jin Y, Angerer LM, Inaba K. Fez function is required to maintain the size of the animal plate in the sea urchin embryo. Development 2011; 138:4233-43. [PMID: 21852402 DOI: 10.1242/dev.069856] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Partitioning ectoderm precisely into neurogenic and non-neurogenic regions is an essential step for neurogenesis of almost all bilaterian embryos. Although it is widely accepted that antagonism between BMP and its inhibitors primarily sets up the border between these two types of ectoderm, it is unclear how such extracellular, diffusible molecules create a sharp and precise border at the single-cell level. Here, we show that Fez, a zinc finger protein, functions as an intracellular factor attenuating BMP signaling specifically within the neurogenic region at the anterior end of sea urchin embryos, termed the animal plate. When Fez function is blocked, the size of this neurogenic ectoderm becomes smaller than normal. However, this reduction is rescued in Fez morphants simply by blocking BMP2/4 translation, indicating that Fez maintains the size of the animal plate by attenuating BMP2/4 function. Consistent with this, the gradient of BMP activity along the aboral side of the animal plate, as measured by pSmad1/5/8 levels, drops significantly in cells expressing Fez and this steep decline requires Fez function. Our data reveal that this neurogenic ectoderm produces an intrinsic system that attenuates BMP signaling to ensure the establishment of a stable, well-defined neural territory, the animal plate.
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Affiliation(s)
- Shunsuke Yaguchi
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan.
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