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Arimoto A, Nishitsuji K, Hisata K, Satoh N, Tagawa K. Transcriptomic evidence for Brachyury expression in the caudal tip region of adult Ptychodera flava (Hemichordata). Dev Growth Differ 2023; 65:470-480. [PMID: 37483093 DOI: 10.1111/dgd.12882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 06/27/2023] [Accepted: 07/19/2023] [Indexed: 07/25/2023]
Abstract
Most metazoans have a single copy of the T-box transcription factor gene Brachyury. This gene is expressed in cells of the blastopore of late blastulae and the archenteron invagination region of gastrulae. It appears to be crucial for gastrulation and mesoderm differentiation of embryos. Although this expression pattern is shared by most deuterostomes, Brachyury expression has not been reported in adult stages. Here we show that Brachyury of an indirect developer, the hemichordate acorn worm Ptychodera flava, is expressed not only in embryonic cells, but also in cells of the caudal tip (anus) region of adults. This spatially restricted expression, shown by whole-mount in situ hybridization, was confirmed by Iso-Seq RNA sequencing and single-cell RNA-seq (scRNA-seq) analysis. Iso-Seq analysis showed that gene expression occurs only in the caudal region of adults, but not in anterior regions, including the stomochord. scRNA-seq analysis showed a cluster that contained Brachyury-expressing cells comprising epidermis- and mesoderm-related cells, but which is unlikely to be associated with the nervous system or muscle. Although further investigation is required to examine the roles of Brachyury in adults, this study provides important clues for extending studies on Brachyury expression involved in development of the most posterior region of deuterostomes.
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Affiliation(s)
- Asuka Arimoto
- Marine Biological Laboratory, Blue Innovation Division, Seto Inland Sea Carbon-neutral Research Center, Hiroshima University, Hiroshima, Japan
| | - Koki Nishitsuji
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Kanako Hisata
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Noriyuki Satoh
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Kuni Tagawa
- Marine Biological Laboratory, Blue Innovation Division, Seto Inland Sea Carbon-neutral Research Center, Hiroshima University, Hiroshima, Japan
- Faculty of Science and Technology, Maulana Malik Ibrahim State Islamic University of Malang, Kota Malang, Indonesia
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2
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Horackova A, Pospisilova A, Stundl J, Minarik M, Jandzik D, Cerny R. Pre-mandibular pharyngeal pouches in early non-teleost fish embryos. Proc Biol Sci 2023; 290:20231158. [PMID: 37700650 PMCID: PMC10498051 DOI: 10.1098/rspb.2023.1158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 08/14/2023] [Indexed: 09/14/2023] Open
Abstract
The vertebrate pharynx is a key embryonic structure with crucial importance for the metameric organization of the head and face. The pharynx is primarily built upon progressive formation of paired pharyngeal pouches that typically develop in post-oral (mandibular, hyoid and branchial) domains. However, in the early embryos of non-teleost fishes, we have previously identified pharyngeal pouch-like outpocketings also in the pre-oral domain of the cranial endoderm. This pre-oral gut (POG) forms by early pouching of the primitive gut cavity, followed by the sequential formation of typical (post-oral) pharyngeal pouches. Here, we tested the pharyngeal nature of the POG by analysing expression patterns of selected core pharyngeal regulatory network genes in bichir and sturgeon embryos. Our comparison revealed generally shared expression patterns, including Shh, Pax9, Tbx1, Eya1, Six1, Ripply3 or Fgf8, between early POG and post-oral pharyngeal pouches. POG thus shares pharyngeal pouch-like morphogenesis and a gene expression profile with pharyngeal pouches and can be regarded as a pre-mandibular pharyngeal pouch. We further suggest that pre-mandibular pharyngeal pouches represent a plesiomorphic vertebrate trait inherited from our ancestor's pharyngeal metameric organization, which is incorporated in the early formation of the pre-chordal plate of vertebrate embryos.
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Affiliation(s)
- Agata Horackova
- Department of Zoology, Faculty of Science, Charles University in Prague, 12844 Prague, Czech Republic
| | - Anna Pospisilova
- Department of Zoology, Faculty of Science, Charles University in Prague, 12844 Prague, Czech Republic
| | - Jan Stundl
- Department of Zoology, Faculty of Science, Charles University in Prague, 12844 Prague, Czech Republic
| | - Martin Minarik
- Department of Zoology, Faculty of Science, Charles University in Prague, 12844 Prague, Czech Republic
| | - David Jandzik
- Department of Zoology, Faculty of Science, Charles University in Prague, 12844 Prague, Czech Republic
- Department of Zoology, Comenius University in Bratislava, Bratislava, Slovakia
| | - Robert Cerny
- Department of Zoology, Faculty of Science, Charles University in Prague, 12844 Prague, Czech Republic
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3
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Yue H, Liang J, Song G, Cheng J, Li J, Zhi Y, Bian Z, He M. Mutation analysis in patients with nonsyndromic tooth agenesis using exome sequencing. Mol Genet Genomic Med 2022; 10:e2045. [PMID: 36017684 PMCID: PMC9544223 DOI: 10.1002/mgg3.2045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 08/05/2022] [Accepted: 08/15/2022] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Tooth agenesis (TA) is a congenital abnormality that may present as syndromic or nonsyndromic. Considering its complex genetic aetiology, the aim of this study was to uncover the pathogenic mutants in patients with nonsyndromic TA and analyse the characteristics of these mutants. METHODS Exome sequencing was performed to detect pathogenic variants in 72 patients from 43 unrelated families with nonsyndromic TA. All candidate variants were validated using Sanger sequencing. Bioinformatics and conformational analyses were performed to determine the pathogenic mechanisms of the mutants. RESULTS The following eight mutations (six novel and two known) in six genes were identified in eight families: WNT10A [c.742C > T (p.R248*)], LRP6 [c.1518G > A (p.W506*), c.2791 + 1G > T], AXIN2 [c.133_134insGCCAGG (p.44_45insGQ)], PAX9 [c.439C > T (p.Q147*), c.453_454insCCAGC (p.L154QfsTer60)], MSX1 [c.603_604del (p.A203GfsTer10)] and PITX2 [c.522C > G (p.Y174*)]. Bioinformatics and conformational analyses showed that the protein structures were severely altered in these mutants, and indicated that these structural abnormalities may cause functional disabilities. CONCLUSIONS Our study extends the mutation spectrum in patients with nonsyndromic TA and provides valuable data for genetic counselling. The pathogenic mechanisms of TA in patients/families with unknown causative variants need to be explored further.
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Affiliation(s)
- Haitang Yue
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Jia Liang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Guangtai Song
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Jing Cheng
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Jiahui Li
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Yusheng Zhi
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Zhuan Bian
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Miao He
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China
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4
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Álvarez-Armada N, Cameron CB, Bauer JE, Rahman IA. Heterochrony and parallel evolution of echinoderm, hemichordate and cephalochordate internal bars. Proc Biol Sci 2022; 289:20220258. [PMID: 35538784 PMCID: PMC9091856 DOI: 10.1098/rspb.2022.0258] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Deuterostomes comprise three phyla with radically different body plans. Phylogenetic bracketing of the living deuterostome clades suggests the latest common ancestor of echinoderms, hemichordates and chordates was a bilaterally symmetrical worm with pharyngeal openings, with these characters lost in echinoderms. Early fossil echinoderms with pharyngeal openings have been described, but their interpretation is highly controversial. Here, we critically evaluate the evidence for pharyngeal structures (gill bars) in the extinct stylophoran echinoderms Lagynocystis pyramidalis and Jaekelocarpus oklahomensis using virtual models based on high-resolution X-ray tomography scans of three-dimensionally preserved fossil specimens. Multivariate analyses of the size, spacing and arrangement of the internal bars in these fossils indicate they are substantially more similar to gill bars in modern enteropneust hemichordates and cephalochordates than to other internal bar-like structures in fossil blastozoan echinoderms. The close similarity between the internal bars of the stylophorans L. pyramidalis and J. oklahomensis and the gill bars of extant chordates and hemichordates is strong evidence for their homology. Differences between these internal bars and bar-like elements of the respiratory systems in blastozoans suggest these structures might have arisen through parallel evolution across deuterostomes, perhaps underpinned by a common developmental genetic mechanism.
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Affiliation(s)
| | - Christopher B Cameron
- Département de sciences biologiques, Université de Montréal C.P. 6128, Succursale Centre-ville, Montréal, QC, Canada H3C 3J7
| | - Jennifer E Bauer
- University of Michigan Museum of Paleontology, Ann Arbor, MI 48109-1085, USA
| | - Imran A Rahman
- The Natural History Museum, London SW7 5BD, UK.,Oxford University Museum of Natural History, Oxford OX1 3PW, UK
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5
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Arimoto A, Tagawa K. Studying Hemichordata WBR Using Ptychodera flava. Methods Mol Biol 2022; 2450:293-309. [PMID: 35359314 PMCID: PMC9761517 DOI: 10.1007/978-1-0716-2172-1_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Hemichordates are benthic marine invertebrates closely related to chordates. Several species, including Ptychodera flava in the phylum Hemichordates, can undergo whole body regeneration from a small fragment. P. flava is widely distributed in the warm Indo-Pacific region and is easily collected in the lower tidal zone of a shallow beach with a coral reef. Here, we describe the methods for animal collection and preparation of regenerating tissues. The prepared tissues can be used for various molecular and/or histological experiments. We also demonstrate how to examine gene expression patterns in the tissues using whole mount in situ hybridization.
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Affiliation(s)
- Asuka Arimoto
- Marine Biological Laboratory, Graduate School of Integrated Sciences for Life, Hiroshima University, Onomichi, Hiroshima, Japan
| | - Kuni Tagawa
- Marine Biological Laboratory, Graduate School of Integrated Sciences for Life, Hiroshima University, Onomichi, Hiroshima, Japan.
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6
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Abstract
Hemichordates, along with echinoderms and chordates, belong to the lineage of bilaterians called the deuterostomes. Their phylogenetic position as an outgroup to chordates provides an opportunity to investigate the evolutionary origins of the chordate body plan and reconstruct ancestral deuterostome characters. The body plans of the hemichordates and chordates are organizationally divergent making anatomical comparisons very challenging. The developmental underpinnings of animal body plans are often more conservative than the body plans they regulate, and offer a novel data set for making comparisons between morphologically divergent body architectures. Here I review the hemichordate developmental data generated over the past 20 years that further test hypotheses of proposed morphological affinities between the two taxa, but also compare the conserved anteroposterior, dorsoventral axial patterning programs and germ layer specification programs. These data provide an opportunity to determine which developmental programs are ancestral deuterostome or bilaterian innovations, and which ones occurred in stem chordates or vertebrates representing developmental novelties of the chordate body plan.
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7
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Hatleberg WL, Hinman VF. Modularity and hierarchy in biological systems: Using gene regulatory networks to understand evolutionary change. Curr Top Dev Biol 2021; 141:39-73. [DOI: 10.1016/bs.ctdb.2020.11.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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8
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DeLaurier A. Evolution and development of the fish jaw skeleton. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2018; 8:e337. [PMID: 30378758 DOI: 10.1002/wdev.337] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 09/25/2018] [Accepted: 09/27/2018] [Indexed: 12/18/2022]
Abstract
The evolution of the jaw represents a key innovation in driving the diversification of vertebrate body plans and behavior. The pharyngeal apparatus originated as gill bars separated by slits in chordate ancestors to vertebrates. Later, with the acquisition of neural crest, pharyngeal arches gave rise to branchial basket cartilages in jawless vertebrates (agnathans), and later bone and cartilage of the jaw, jaw support, and gills of jawed vertebrates (gnathostomes). Major events in the evolution of jaw structure from agnathans to gnathostomes include axial regionalization of pharyngeal elements and formation of a jaw joint. Hox genes specify the anterior-posterior identity of arches, and edn1, dlx, hand2, Jag1b-Notch2 signaling, and Nr2f factors specify dorsal-ventral identity. The formation of a jaw joint, an important step in the transition from an un-jointed pharynx in agnathans to a hinged jaw in gnathostomes involves interaction between nkx3.2, hand2, and barx1 factors. Major events in jaw patterning between fishes and reptiles include changes to elements of the second pharyngeal arch, including a loss of opercular and branchiostegal ray bones and transformation of the hyomandibula into the stapes. Further changes occurred between reptiles and mammals, including the transformation of the articular and quadrate elements of the jaw joint into the malleus and incus of the middle ear. Fossils of transitional jaw phenotypes can be analyzed from a developmental perspective, and there exists potential to use genetic manipulation techniques in extant taxa to test hypotheses about the evolution of jaw patterning in ancient vertebrates. This article is categorized under: Comparative Development and Evolution > Evolutionary Novelties Early Embryonic Development > Development to the Basic Body Plan Comparative Development and Evolution > Body Plan Evolution.
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Affiliation(s)
- April DeLaurier
- Department of Biology and Geology, University of South Carolina Aiken, Aiken, South Carolina
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9
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Arimoto A, Tagawa K. Regeneration in the enteropneust hemichordate, Ptychodera flava, and its evolutionary implications. Dev Growth Differ 2018; 60:400-408. [PMID: 30009383 DOI: 10.1111/dgd.12557] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 06/03/2018] [Accepted: 06/05/2018] [Indexed: 12/28/2022]
Abstract
Hemichordates are marine invertebrates that are closely related to chordates, but while their body plans are comparable to those of chordates, they possess a remarkable capacity for regeneration, even as adults. A small fragment is sufficient to form a complete individual. Unlike echinoderms, their larvae transform directly into adults; therefore, hemichordate systems offer clear morphological and molecular parallels between regeneration and development. Morphological events in regeneration are generally similar to organogenesis in juveniles. Nonetheless, comparative analysis of gene expression in these two morphological phenomena suggests that hemichordate regeneration is regulated by regeneration-specific mechanisms, as well as by developmental mechanisms. Dependency upon resident pluripotent/multipotent stem cells is a significant difference in metazoan regeneration, and such stem cells are essential for regeneration in many lineages. Based on the present gene expression study, regeneration in acorn worms is more closely related to that in vertebrates, because it employs endogenous stem cell-independent transdifferentiation.
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Affiliation(s)
- Asuka Arimoto
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
| | - Kuni Tagawa
- Marine Biological Laboratory, Graduate School of Science, Hiroshima University, Onomichi, Hiroshima, Japan
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10
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Sasakura Y, Hozumi A. Formation of adult organs through metamorphosis in ascidians. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2017; 7. [PMID: 29105358 DOI: 10.1002/wdev.304] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/28/2017] [Accepted: 09/11/2017] [Indexed: 02/05/2023]
Abstract
The representative characteristic of ascidians is their vertebrate-like, tadpole shape at the larval stage. Ascidians lose the tadpole shape through metamorphosis to become adults with a nonmotile, sessile body and a shape generally considered distinct from that of vertebrates. Solitary ascidians including Ciona species are extensively studied to understand the developmental mechanisms of ascidians, and to compare these mechanisms with their counterparts in vertebrates. In these ascidian species, the digestive and circulatory systems are not well developed in the larval trunk and the larvae do not take food. This is in contrast with the inner conditions of vertebrate tadpoles, which have functional organs comparable to those of adults. The adult organs and tissues of these ascidians become functional during metamorphosis that is completed quickly, suggesting that the ascidian larvae of solitary species are a transient stage of development. We here discuss how the cells and tissues in the ascidian larval body are converted into those of adults. The hearts of ascidians and vertebrates use closely related cellular and molecular mechanisms that suggest their shared origin. Hox genes of ascidians are essential for forming adult endodermal structures. To fully understand the development and evolution of chordates, a complete elucidation of the mechanisms underlying the adult tissue/organ formation of ascidians will be needed. WIREs Dev Biol 2018, 7:e304. doi: 10.1002/wdev.304 This article is categorized under: Comparative Development and Evolution > Body Plan Evolution Early Embryonic Development > Development to the Basic Body Plan.
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Affiliation(s)
- Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan
| | - Akiko Hozumi
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan
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11
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Simakov O, Kawashima T. Independent evolution of genomic characters during major metazoan transitions. Dev Biol 2016; 427:179-192. [PMID: 27890449 DOI: 10.1016/j.ydbio.2016.11.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 11/08/2016] [Accepted: 11/14/2016] [Indexed: 02/03/2023]
Abstract
Metazoan evolution encompasses a vast evolutionary time scale spanning over 600 million years. Our ability to infer ancestral metazoan characters, both morphological and functional, is limited by our understanding of the nature and evolutionary dynamics of the underlying regulatory networks. Increasing coverage of metazoan genomes enables us to identify the evolutionary changes of the relevant genomic characters such as the loss or gain of coding sequences, gene duplications, micro- and macro-synteny, and non-coding element evolution in different lineages. In this review we describe recent advances in our understanding of ancestral metazoan coding and non-coding features, as deduced from genomic comparisons. Some genomic changes such as innovations in gene and linkage content occur at different rates across metazoan clades, suggesting some level of independence among genomic characters. While their contribution to biological innovation remains largely unclear, we review recent literature about certain genomic changes that do correlate with changes to specific developmental pathways and metazoan innovations. In particular, we discuss the origins of the recently described pharyngeal cluster which is conserved across deuterostome genomes, and highlight different genomic features that have contributed to the evolution of this group. We also assess our current capacity to infer ancestral metazoan states from gene models and comparative genomics tools and elaborate on the future directions of metazoan comparative genomics relevant to evo-devo studies.
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Affiliation(s)
- Oleg Simakov
- Okinawa Institute of Science and Technology, Okinawa, Japan.
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12
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The phylogeny, evolutionary developmental biology, and paleobiology of the Deuterostomia: 25 years of new techniques, new discoveries, and new ideas. ORG DIVERS EVOL 2016. [DOI: 10.1007/s13127-016-0270-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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13
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Ordered expression pattern of Hox and ParaHox genes along the alimentary canal in the ascidian juvenile. Cell Tissue Res 2016; 365:65-75. [DOI: 10.1007/s00441-016-2360-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/07/2016] [Indexed: 01/03/2023]
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14
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Okada K, Inohaya K, Mise T, Kudo A, Takada S, Wada H. Reiterative expression of pax1 directs pharyngeal pouch segmentation in medaka (Oryzias latipes). Development 2016; 143:1800-10. [DOI: 10.1242/dev.130039] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 03/21/2016] [Indexed: 12/27/2022]
Abstract
A striking characteristic of vertebrate development is the pharyngeal arches, which are a series of bulges on the lateral surface of the head of vertebrate embryos. Although each pharyngeal arch is segmented by the reiterative formation of endodermal outpocketings called pharyngeal pouches, the molecular network underlying the reiterative pattern remains unclear. Here, we show that pax1 plays critical roles in pouch segmentation in medaka embryos. Importantly, pax1 expression in the endoderm prefigures the location of the next pouch before the cells bud from the epithelium. TALEN-generated pax1 mutants did not form pharyngeal pouches posterior to the second arch. Segmental expression of tbx1 and fgf3, which play critical roles in pouch development, was almost nonexistent in the pharyngeal endoderm of pax1 mutants, with disturbance of the reiterative pattern of pax1 expression. These results suggest that pax1 plays a critical role in generating the primary pattern for segmentation in the pharyngeal endoderm by regulating tbx1 and fgf3 expression. Our findings illustrate the critical roles of pax1 in vertebrate pharyngeal segmentation and provide insights into the evolutionary origin of the deuterostome gill slit.
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Affiliation(s)
- Kazunori Okada
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 111 Tennoudai, Tsukuba, 305-8572, Japan
- Okazaki Institute for Integrative Bioscience and National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, 444-8787, Japan
| | - Keiji Inohaya
- Department of Biological Information, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8501, Japan
| | - Takeshi Mise
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 111 Tennoudai, Tsukuba, 305-8572, Japan
| | - Akira Kudo
- Department of Biological Information, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8501, Japan
| | - Shinji Takada
- Okazaki Institute for Integrative Bioscience and National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji-cho, Okazaki, 444-8787, Japan
- Department for Basic Biology, SOKENDAI (The Graduate University for Advanced Studies), 5-1 Higashiyama, Myodaiji-cho, Okazaki, 444-8787, Japan
| | - Hiroshi Wada
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 111 Tennoudai, Tsukuba, 305-8572, Japan
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15
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Simakov O, Kawashima T, Marlétaz F, Jenkins J, Koyanagi R, Mitros T, Hisata K, Bredeson J, Shoguchi E, Gyoja F, Yue JX, Chen YC, Freeman RM, Sasaki A, Hikosaka-Katayama T, Sato A, Fujie M, Baughman KW, Levine J, Gonzalez P, Cameron C, Fritzenwanker JH, Pani AM, Goto H, Kanda M, Arakaki N, Yamasaki S, Qu J, Cree A, Ding Y, Dinh HH, Dugan S, Holder M, Jhangiani SN, Kovar CL, Lee SL, Lewis LR, Morton D, Nazareth LV, Okwuonu G, Santibanez J, Chen R, Richards S, Muzny DM, Gillis A, Peshkin L, Wu M, Humphreys T, Su YH, Putnam NH, Schmutz J, Fujiyama A, Yu JK, Tagawa K, Worley KC, Gibbs RA, Kirschner MW, Lowe CJ, Satoh N, Rokhsar DS, Gerhart J. Hemichordate genomes and deuterostome origins. Nature 2015; 527:459-65. [PMID: 26580012 PMCID: PMC4729200 DOI: 10.1038/nature16150] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/13/2015] [Indexed: 12/12/2022]
Abstract
Acorn worms, also known as enteropneust (literally, 'gut-breathing') hemichordates, are marine invertebrates that share features with echinoderms and chordates. Together, these three phyla comprise the deuterostomes. Here we report the draft genome sequences of two acorn worms, Saccoglossus kowalevskii and Ptychodera flava. By comparing them with diverse bilaterian genomes, we identify shared traits that were probably inherited from the last common deuterostome ancestor, and then explore evolutionary trajectories leading from this ancestor to hemichordates, echinoderms and chordates. The hemichordate genomes exhibit extensive conserved synteny with amphioxus and other bilaterians, and deeply conserved non-coding sequences that are candidates for conserved gene-regulatory elements. Notably, hemichordates possess a deuterostome-specific genomic cluster of four ordered transcription factor genes, the expression of which is associated with the development of pharyngeal 'gill' slits, the foremost morphological innovation of early deuterostomes, and is probably central to their filter-feeding lifestyle. Comparative analysis reveals numerous deuterostome-specific gene novelties, including genes found in deuterostomes and marine microbes, but not other animals. The putative functions of these genes can be linked to physiological, metabolic and developmental specializations of the filter-feeding ancestor.
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Affiliation(s)
- Oleg Simakov
- Molecular Genetics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan.,Department of Molecular Evolution, Centre for Organismal Studies, University of Heidelberg, 69115 Heidelberg, Germany
| | - Takeshi Kawashima
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | | | - Jerry Jenkins
- HudsonAlpha Institute of Biotechnology, Huntsville, Alabama 35806, USA
| | - Ryo Koyanagi
- DNA Sequencing Section, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Therese Mitros
- Department of Molecular and Cell Biology, University of California, Berkeley California 94720-3200, USA
| | - Kanako Hisata
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Jessen Bredeson
- Department of Molecular and Cell Biology, University of California, Berkeley California 94720-3200, USA
| | - Eiichi Shoguchi
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Fuki Gyoja
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Jia-Xing Yue
- Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas 77005, USA
| | - Yi-Chih Chen
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Robert M Freeman
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Akane Sasaki
- Marine Biological Laboratory, Graduate School of Science, Hiroshima University, Onomichi, Hiroshima 722-0073, Japan
| | - Tomoe Hikosaka-Katayama
- Natural Science Center for Basic Research and Development, Gene Science Division, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8527, Japan
| | - Atsuko Sato
- Marine Biological Association of the UK, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
| | - Manabu Fujie
- DNA Sequencing Section, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Kenneth W Baughman
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Judith Levine
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, California 93950, USA
| | - Paul Gonzalez
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, California 93950, USA
| | - Christopher Cameron
- Départment de sciences biologiques, University of Montreal, Quebec H3C 3J7, Canada
| | - Jens H Fritzenwanker
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, California 93950, USA
| | - Ariel M Pani
- University of North Caroline at Chapel Hill, North Carolina 27599, USA
| | - Hiroki Goto
- DNA Sequencing Section, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Miyuki Kanda
- DNA Sequencing Section, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Nana Arakaki
- DNA Sequencing Section, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Shinichi Yamasaki
- DNA Sequencing Section, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Jiaxin Qu
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Andrew Cree
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Yan Ding
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Huyen H Dinh
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Shannon Dugan
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Michael Holder
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Shalini N Jhangiani
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Christie L Kovar
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Sandra L Lee
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Lora R Lewis
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Donna Morton
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Lynne V Nazareth
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Geoffrey Okwuonu
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Jireh Santibanez
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Rui Chen
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Stephen Richards
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Donna M Muzny
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Andrew Gillis
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Leonid Peshkin
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Michael Wu
- Department of Molecular and Cell Biology, University of California, Berkeley California 94720-3200, USA
| | - Tom Humphreys
- Institute for Biogenesis Research, University of Hawaii, Hawaii 96822, USA
| | - Yi-Hsien Su
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Nicholas H Putnam
- Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas 77005, USA
| | - Jeremy Schmutz
- HudsonAlpha Institute of Biotechnology, Huntsville, Alabama 35806, USA
| | - Asao Fujiyama
- National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Jr-Kai Yu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Kunifumi Tagawa
- Marine Biological Laboratory, Graduate School of Science, Hiroshima University, Onomichi, Hiroshima 722-0073, Japan
| | - Kim C Worley
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Richard A Gibbs
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, MS BCM226, Houston, Texas 77030, USA
| | - Marc W Kirschner
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Christopher J Lowe
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, California 93950, USA
| | - Noriyuki Satoh
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Daniel S Rokhsar
- Molecular Genetics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan.,Department of Molecular and Cell Biology, University of California, Berkeley California 94720-3200, USA.,US Department of Energy Joint Genome Institute, Walnut Creek, California 94598, USA
| | - John Gerhart
- Department of Molecular and Cell Biology, University of California, Berkeley California 94720-3200, USA
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16
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Liu X, Li G, Liu X, Wang YQ. The role of the Pax1/9 gene in the early development of amphioxus pharyngeal gill slits. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2015; 324:30-40. [PMID: 25504927 DOI: 10.1002/jez.b.22596] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The pharynx is a major characteristic of chordates. Compared with vertebrates, amphioxus has an advantage for the study of pharynx development, as embryos lack neural crest, and the pharynx is mainly derived from endoderm cells. The Pax1/9 subfamily genes have essential roles in vertebrate pharyngeal patterning, but it is not known if the Pax1/9 gene has similar functions in amphioxus pharynx development. To answer this question, we examined the Pax1/9 gene expression pattern in amphioxus embryos at different developmental stages, and observed morphological changes following Pax1/9 knockdown. RT-qPCR analysis indicated that Pax1/9 expression was initiated during early neurula stage and rapidly peaked during mid-neurula stage. Furthermore, in situ hybridization analysis showed that Pax1/9 transcripts were localized exclusively in the most endodermal region of the developing pharynx in early neurula stage embryos; however, Pax1/9 expression was strikingly down-regulated in the region where gill slits would form from the fusion of endoderm and ectoderm in subsequent developmental stages and was maintained in the border regions between adjacent gill slits. Knockdown of Pax1/9 function using both morpholino and siRNA approaches led to embryonic defects in the first three gill slits, and fusion of the first two gill slits. Moreover, the expression levels of the pharyngeal marker genes Six1/2 and Tbx1/10 were reduced in Pax1/9 knockdown embryos. From these observations, we concluded that the Pax1/9 gene has an important role in the initial differentiation of amphioxus pharyngeal endoderm and in the formation of gill slits, most likely via modulation of Six1/2 and Tbx1/10 expression.
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Affiliation(s)
- Xin Liu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
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17
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Abstract
Traditional metazoan phylogeny classifies the Vertebrata as a subphylum of the phylum Chordata, together with two other subphyla, the Urochordata (Tunicata) and the Cephalochordata. The Chordata, together with the phyla Echinodermata and Hemichordata, comprise a major group, the Deuterostomia. Chordates invariably possess a notochord and a dorsal neural tube. Although the origin and evolution of chordates has been studied for more than a century, few authors have intimately discussed taxonomic ranking of the three chordate groups themselves. Accumulating evidence shows that echinoderms and hemichordates form a clade (the Ambulacraria), and that within the Chordata, cephalochordates diverged first, with tunicates and vertebrates forming a sister group. Chordates share tadpole-type larvae containing a notochord and hollow nerve cord, whereas ambulacrarians have dipleurula-type larvae containing a hydrocoel. We propose that an evolutionary occurrence of tadpole-type larvae is fundamental to understanding mechanisms of chordate origin. Protostomes have now been reclassified into two major taxa, the Ecdysozoa and Lophotrochozoa, whose developmental pathways are characterized by ecdysis and trochophore larvae, respectively. Consistent with this classification, the profound dipleurula versus tadpole larval differences merit a category higher than the phylum. Thus, it is recommended that the Ecdysozoa, Lophotrochozoa, Ambulacraria and Chordata be classified at the superphylum level, with the Chordata further subdivided into three phyla, on the basis of their distinctive characteristics.
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Affiliation(s)
- Noriyuki Satoh
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Daniel Rokhsar
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3200, USA
| | - Teruaki Nishikawa
- Department of Biology, Faculty of Science, Toho University, Funabashi, Chiba 274-8510, Japan
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18
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The deuterostome context of chordate origins. Nature 2015; 520:456-65. [PMID: 25903627 DOI: 10.1038/nature14434] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 02/03/2015] [Indexed: 01/08/2023]
Abstract
Our understanding of vertebrate origins is powerfully informed by comparative morphology, embryology and genomics of chordates, hemichordates and echinoderms, which together make up the deuterostome clade. Striking body-plan differences among these phyla have historically hindered the identification of ancestral morphological features, but recent progress in molecular genetics and embryology has revealed deep similarities in body-axis formation and organization across deuterostomes, at stages before morphological differences develop. These developmental genetic features, along with robust support of pharyngeal gill slits as a shared deuterostome character, provide the foundation for the emergence of chordates.
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19
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Scenarios for the making of vertebrates. Nature 2015; 520:450-5. [PMID: 25903626 DOI: 10.1038/nature14433] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 11/24/2014] [Indexed: 01/17/2023]
Abstract
Over the past 200 years, almost every invertebrate phylum has been proposed as a starting point for evolving vertebrates. Most of these scenarios are outdated, but several are still seriously considered. The short-range transition from ancestral invertebrate chordates (similar to amphioxus and tunicates) to vertebrates is well accepted. However, longer-range transitions leading up to the invertebrate chordates themselves are more controversial. Opinion is divided between the annelid and the enteropneust scenarios, predicting, respectively, a complex or a simple ancestor for bilaterian animals. Deciding between these ideas will be facilitated by further comparative studies of multicellular animals, including enigmatic taxa such as xenacoelomorphs.
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20
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Passamaneck YJ, Hejnol A, Martindale MQ. Mesodermal gene expression during the embryonic and larval development of the articulate brachiopod Terebratalia transversa. EvoDevo 2015; 6:10. [PMID: 25897375 PMCID: PMC4404124 DOI: 10.1186/s13227-015-0004-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Accepted: 03/19/2015] [Indexed: 12/21/2022] Open
Abstract
Background Brachiopods undergo radial cleavage, which is distinct from the stereotyped development of closely related spiralian taxa. The mesoderm has been inferred to derive from the archenteron walls following gastrulation, and the primary mesoderm derivative in the larva is a complex musculature. To investigate the specification and differentiation of the mesoderm in the articulate brachiopod Terebratalia transversa, we have identified orthologs of genes involved in mesoderm development in other taxa and investigated their spatial and temporal expression during the embryonic and larval development of T. transversa. Results Orthologs of 17 developmental regulatory genes with roles in the development of the mesoderm in other bilaterian animals were found to be expressed in the developing mesoderm of T. transversa. Five genes, Tt.twist, Tt.GATA456, Tt.dachshund, Tt.mPrx, and Tt.NK1, were found to have expression throughout the archenteron wall at the radial gastrula stage, shortly after the initiation of gastrulation. Three additional genes, Tt.Pax1/9, Tt.MyoD, and Tt.Six1/2, showed expression at this stage in only a portion of the archenteron wall. Tt.eya, Tt.FoxC, Tt.FoxF, Tt.Mox, Tt.paraxis, Tt.Limpet, and Tt.Mef2 all showed initial mesodermal expression during later gastrula or early larval stages. At the late larval stage, Tt.dachshund, Tt.Limpet, and Tt.Mef2 showed expression in nearly all mesoderm cells, while all other genes were localized to specific regions of the mesoderm. Tt.FoxD and Tt.noggin both showed expression in the ventral mesoderm at the larval stages, with gastrula expression patterns in the archenteron roof and blastopore lip, respectively. Conclusions Expression analyses support conserved roles for developmental regulators in the specification and differentiation of the mesoderm during the development of T. transversa. Expression of multiple mesodermal factors in the archenteron wall during gastrulation supports previous morphological observations that this region gives rise to larval mesoderm. Localized expression domains during gastrulation and larval development evidence early regionalization of the mesoderm and provide a basis for hypotheses regarding the molecular regulation underlying the complex system of musculature observed in the larva. Electronic supplementary material The online version of this article (doi:10.1186/s13227-015-0004-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yale J Passamaneck
- Kewalo Marine Laboratory, PBRC, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813 USA ; The Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL 32080 USA
| | - Andreas Hejnol
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate, 55, 5008 Bergen, Norway
| | - Mark Q Martindale
- The Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL 32080 USA
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21
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Satoh N, Tagawa K, Lowe CJ, Yu JK, Kawashima T, Takahashi H, Ogasawara M, Kirschner M, Hisata K, Su YH, Gerhart J. On a possible evolutionary link of the stomochord of hemichordates to pharyngeal organs of chordates. Genesis 2014; 52:925-34. [PMID: 25303744 PMCID: PMC5673098 DOI: 10.1002/dvg.22831] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 10/02/2014] [Accepted: 10/07/2014] [Indexed: 01/24/2023]
Abstract
As a group closely related to chordates, hemichordate acorn worms are in a key phylogenic position for addressing hypotheses of chordate origins. The stomochord of acorn worms is an anterior outgrowth of the pharynx endoderm into the proboscis. In 1886 Bateson proposed homology of this organ to the chordate notochord, crowning this animal group "hemichordates." Although this proposal has been debated for over a century, the question still remains unresolved. Here we review recent progress related to this question. First, the developmental mode of the stomochord completely differs from that of the notochord. Second, comparison of expression profiles of genes including Brachyury, a key regulator of notochord formation in chordates, does not support the stomochord/notochord homology. Third, FoxE that is expressed in the stomochord-forming region in acorn worm juveniles is expressed in the club-shaped gland and in the endostyle of amphioxus, in the endostyle of ascidians, and in the thyroid gland of vertebrates. Based on these findings, together with the anterior endodermal location of the stomochord, we propose that the stomochord has evolutionary relatedness to chordate organs deriving from the anterior pharynx rather than to the notochord.
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Affiliation(s)
- Noriyuki Satoh
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
| | - Kunifumi Tagawa
- Marine Biological Laboratory, Graduate School of Science, Hiroshima University, Onomichi, Hiroshima, Japan
| | - Christopher J. Lowe
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, California
| | - Jr-Kai Yu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Takeshi Kawashima
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
| | - Hiroki Takahashi
- Division of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi, Japan
| | - Michio Ogasawara
- Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, Chiba, Japan
| | - Marc Kirschner
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts
| | - Kanako Hisata
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
| | - Yi-Hsien Su
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - John Gerhart
- Department of Molecular and Cell Biology, University of California, Berkeley, California
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22
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Karaiskou A, Swalla BJ, Sasakura Y, Chambon JP. Metamorphosis in solitary ascidians. Genesis 2014; 53:34-47. [PMID: 25250532 DOI: 10.1002/dvg.22824] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/15/2014] [Accepted: 09/19/2014] [Indexed: 12/19/2022]
Abstract
Embryonic and postembryonic development in ascidians have been studied for over a century, but it is only in the last 10 years that the complex molecular network involved in coordinating postlarval development and metamorphosis has started to emerge. In most ascidians, the transition from the larval to the sessile juvenile/adult stage, or metamorphosis, requires a combination of environmental and endogenous signals and is characterized by coordinated global morphogenetic changes that are initiated by the adhesion of the larvae. Cloney was the first to describe cellular events of ascidians' metamorphosis in 1978 and only recently elements of the molecular regulation of this crucial developmental step have been revealed. This review aims to present a thorough view of this crucial developmental step by combining recent molecular data to the already established cellular events.
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Affiliation(s)
- Anthi Karaiskou
- Sorbonne Universités, UPMC Univ Paris 06, UMR7622-Biologie du Développement, Paris, France
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23
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Koop D, Chen J, Theodosiou M, Carvalho JE, Alvarez S, de Lera AR, Holland LZ, Schubert M. Roles of retinoic acid and Tbx1/10 in pharyngeal segmentation: amphioxus and the ancestral chordate condition. EvoDevo 2014; 5:36. [PMID: 25664163 PMCID: PMC4320481 DOI: 10.1186/2041-9139-5-36] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 08/27/2014] [Indexed: 12/16/2022] Open
Abstract
Background Although chordates descend from a segmented ancestor, the evolution of head segmentation has been very controversial for over 150 years. Chordates generally possess a segmented pharynx, but even though anatomical evidence and gene expression analyses suggest homologies between the pharyngeal apparatus of invertebrate chordates, such as the cephalochordate amphioxus, and vertebrates, these homologies remain contested. We, therefore, decided to study the evolution of the chordate head by examining the molecular mechanisms underlying pharyngeal morphogenesis in amphioxus, an animal lacking definitive neural crest. Results Focusing on the role of retinoic acid (RA) in post-gastrulation pharyngeal morphogenesis, we found that during gastrulation, RA signaling in the endoderm is required for defining pharyngeal and non-pharyngeal domains and that this process involves active degradation of RA anteriorly in the embryo. Subsequent extension of the pharyngeal territory depends on the creation of a low RA environment and is coupled to body elongation. RA further functions in pharyngeal segmentation in a regulatory network involving the mutual inhibition of RA- and Tbx1/10-dependent signaling. Conclusions These results indicate that the involvement of RA signaling and its interactions with Tbx1/10 in head segmentation preceded the evolution of neural crest and were thus likely present in the ancestral chordate. Furthermore, developmental comparisons between different deuterostome models suggest that the genetic mechanisms for pharyngeal segmentation are evolutionary ancient and very likely predate the origin of chordates. Electronic supplementary material The online version of this article (doi:10.1186/2041-9139-5-36) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Demian Koop
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0202 USA
| | - Jie Chen
- Institut de Génomique Fonctionnelle de Lyon (CNRS UMR 5242, UCBL, ENS, INRA 1288), Ecole Normale Supérieure de Lyon, 69364 Lyon, Cedex 07, France
| | - Maria Theodosiou
- Institut de Génomique Fonctionnelle de Lyon (CNRS UMR 5242, UCBL, ENS, INRA 1288), Ecole Normale Supérieure de Lyon, 69364 Lyon, Cedex 07, France
| | - João E Carvalho
- Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7009, Laboratoire de Biologie du Développement de Villefranche-sur-Mer, Observatoire Océanologique de Villefranche-sur-Mer, 06230 Villefranche-sur-Mer, France ; CNRS, UMR 7009, Laboratoire de Biologie du Développement de Villefranche-sur-Mer, Observatoire Océanologique de Villefranche-sur-Mer, 06230 Villefranche-sur-Mer, France
| | - Susana Alvarez
- Departamento de Química Orgánica, Universidade de Vigo, 33610 Vigo, Spain
| | - Angel R de Lera
- Departamento de Química Orgánica, Universidade de Vigo, 33610 Vigo, Spain
| | - Linda Z Holland
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0202 USA
| | - Michael Schubert
- Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7009, Laboratoire de Biologie du Développement de Villefranche-sur-Mer, Observatoire Océanologique de Villefranche-sur-Mer, 06230 Villefranche-sur-Mer, France ; CNRS, UMR 7009, Laboratoire de Biologie du Développement de Villefranche-sur-Mer, Observatoire Océanologique de Villefranche-sur-Mer, 06230 Villefranche-sur-Mer, France
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24
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Kist R, Watson M, Crosier M, Robinson M, Fuchs J, Reichelt J, Peters H. The formation of endoderm-derived taste sensory organs requires a Pax9-dependent expansion of embryonic taste bud progenitor cells. PLoS Genet 2014; 10:e1004709. [PMID: 25299669 PMCID: PMC4191947 DOI: 10.1371/journal.pgen.1004709] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 08/26/2014] [Indexed: 11/18/2022] Open
Abstract
In mammals, taste buds develop in different regions of the oral cavity. Small epithelial protrusions form fungiform papillae on the ectoderm-derived dorsum of the tongue and contain one or few taste buds, while taste buds in the soft palate develop without distinct papilla structures. In contrast, the endoderm-derived circumvallate and foliate papillae located at the back of the tongue contain a large number of taste buds. These taste buds cluster in deep epithelial trenches, which are generated by intercalating a period of epithelial growth between initial placode formation and conversion of epithelial cells into sensory cells. How epithelial trench formation is genetically regulated during development is largely unknown. Here we show that Pax9 acts upstream of Pax1 and Sox9 in the expanding taste progenitor field of the mouse circumvallate papilla. While a reduced number of taste buds develop in a growth-retarded circumvallate papilla of Pax1 mutant mice, its development arrests completely in Pax9-deficient mice. In addition, the Pax9 mutant circumvallate papilla trenches lack expression of K8 and Prox1 in the taste bud progenitor cells, and gradually differentiate into an epidermal-like epithelium. We also demonstrate that taste placodes of the soft palate develop through a Pax9-dependent induction. Unexpectedly, Pax9 is dispensable for patterning, morphogenesis and maintenance of taste buds that develop in ectoderm-derived fungiform papillae. Collectively, our data reveal an endoderm-specific developmental program for the formation of taste buds and their associated papilla structures. In this pathway, Pax9 is essential to generate a pool of taste bud progenitors and to maintain their competence towards prosensory cell fate induction.
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Affiliation(s)
- Ralf Kist
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle upon Tyne, United Kingdom
- Centre for Oral Health Research, School of Dental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Michelle Watson
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle upon Tyne, United Kingdom
| | - Moira Crosier
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle upon Tyne, United Kingdom
| | - Max Robinson
- Centre for Oral Health Research, School of Dental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Jennifer Fuchs
- Department of Craniofacial Development and Stem Cell Biology, King's College London, Guy's Hospital, London, United Kingdom
| | - Julia Reichelt
- Institute of Cellular Medicine, Dermatological Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Heiko Peters
- Institute of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle upon Tyne, United Kingdom
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Tagawa K, Arimoto A, Arimito A, Sasaki A, Izumi M, Fujita S, Humphreys T, Fujiyama A, Kagoshima H, Shin-I T, Kohara Y, Satoh N, Kawashima T. A cDNA resource for gene expression studies of a hemichordate, Ptychodera flava. Zoolog Sci 2014; 31:414-20. [PMID: 25001912 DOI: 10.2108/zs130262] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Recent investigations into the evolution of deuterostomes and the origin of chordates have paid considerable attention to hemichordates (acorn worms), as hemichordates and echinoderms are the closest chordate relatives. The present study prepared cDNA libraries from Ptychodera flava, to study expression and function of genes involved in development of the hemichordate body plan. Expressed sequence tag (EST) analyses of nine cDNA libraries yielded 18,832 cloned genes expressed in eggs, 18,739 in blastulae, 18,539 in gastrulae, 18,811 in larvae, 18,978 in juveniles, 11,802 in adult proboscis, 17,259 in stomochord, 11,886 in gills, and 11,580 in liver, respectively. A set of 34,159 uni-gene clones of P. flava was obtained. This cDNA resource will be valuable for studying temporal and spatial expression of acorn worm genes during development.
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Affiliation(s)
- Kuni Tagawa
- 1 Marine Biological Laboratory, Graduate School of Science, Hiroshima University, Onomichi, Hiroshima 722-0073, Japan
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Feiner N, Meyer A, Kuraku S. Evolution of the vertebrate Pax4/6 class of genes with focus on its novel member, the Pax10 gene. Genome Biol Evol 2014; 6:1635-51. [PMID: 24951566 PMCID: PMC4122933 DOI: 10.1093/gbe/evu135] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The members of the paired box (Pax) family regulate key developmental pathways in many metazoans as tissue-specific transcription factors. Vertebrate genomes typically possess nine Pax genes (Pax1-9), which are derived from four proto-Pax genes in the vertebrate ancestor that were later expanded through the so-called two-round (2R) whole-genome duplication. A recent study proposed that pax6a genes of a subset of teleost fishes (namely, acanthopterygians) are remnants of a paralog generated in the 2R genome duplication, to be renamed pax6.3, and reported one more group of vertebrate Pax genes (Pax6.2), most closely related to the Pax4/6 class. We propose to designate this new member Pax10 instead and reconstruct the evolutionary history of the Pax4/6/10 class with solid phylogenetic evidence. Our synteny analysis showed that Pax4, -6, and -10 originated in the 2R genome duplications early in vertebrate evolution. The phylogenetic analyses of relationships between teleost pax6a and other Pax4, -6, and -10 genes, however, do not support the proposed hypothesis of an ancient origin of the acanthopterygian pax6a genes in the 2R genome duplication. Instead, we confirmed the traditional scenario that the acanthopterygian pax6a is derived from the more recent teleost-specific genome duplication. Notably, Pax6 is present in all vertebrates surveyed to date, whereas Pax4 and -10 were lost multiple times in independent vertebrate lineages, likely because of their restricted expression patterns: Among Pax6-positive domains, Pax10 has retained expression in the adult retina alone, which we documented through in situ hybridization and quantitative reverse transcription polymerase chain reaction experiments on zebrafish, Xenopus, and anole lizard.
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Affiliation(s)
- Nathalie Feiner
- Department of Biology, University of Konstanz, GermanyInternational Max-Planck Research School (IMPRS) for Organismal Biology, University of Konstanz, GermanyPresent address: Department of Zoology, University of Oxford, United Kingdom
| | - Axel Meyer
- Department of Biology, University of Konstanz, GermanyInternational Max-Planck Research School (IMPRS) for Organismal Biology, University of Konstanz, Germany
| | - Shigehiro Kuraku
- Department of Biology, University of Konstanz, GermanyInternational Max-Planck Research School (IMPRS) for Organismal Biology, University of Konstanz, GermanyPresent address: Genome Resource and Analysis Unit, RIKEN Center for Developmental Biology, Chuo-ku, Kobe, Hyogo, Japan
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Fritzenwanker JH, Gerhart J, Freeman RM, Lowe CJ. The Fox/Forkhead transcription factor family of the hemichordate Saccoglossus kowalevskii. EvoDevo 2014; 5:17. [PMID: 24987514 PMCID: PMC4077281 DOI: 10.1186/2041-9139-5-17] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 04/03/2014] [Indexed: 12/31/2022] Open
Abstract
Background The Fox gene family is a large family of transcription factors that arose early in organismal evolution dating back to at least the common ancestor of metazoans and fungi. They are key components of many gene regulatory networks essential for embryonic development. Although much is known about the role of Fox genes during vertebrate development, comprehensive comparative studies outside vertebrates are sparse. We have characterized the Fox transcription factor gene family from the genome of the enteropneust hemichordate Saccoglossus kowalevskii, including phylogenetic analysis, genomic organization, and expression analysis during early development. Hemichordates are a sister group to echinoderms, closely related to chordates and are a key group for tracing the evolution of gene regulatory mechanisms likely to have been important in the diversification of the deuterostome phyla. Results Of the 22 Fox gene families that were likely present in the last common ancestor of all deuterostomes, S. kowalevskii has a single ortholog of each group except FoxH, which we were unable to detect, and FoxQ2, which has three paralogs. A phylogenetic analysis of the FoxQ2 family identified an ancestral duplication in the FoxQ2 lineage at the base of the bilaterians. The expression analyses of all 23 Fox genes of S. kowalevskii provide insights into the evolution of components of the regulatory networks for the development of pharyngeal gill slits (foxC, foxL1, and foxI), mesoderm patterning (foxD, foxF, foxG), hindgut development (foxD, foxI), cilia formation (foxJ1), and patterning of the embryonic apical territory (foxQ2). Conclusions Comparisons of our results with data from echinoderms, chordates, and other bilaterians help to develop hypotheses about the developmental roles of Fox genes that likely characterized ancestral deuterostomes and bilaterians, and more recent clade-specific innovations.
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Affiliation(s)
- Jens H Fritzenwanker
- Hopkins Marine Station of Stanford University, 120 Oceanview Boulevard, Pacific Grove, CA 93950, USA
| | - John Gerhart
- Department of Molecular and Cell Biology, University of California, 142 Life Sciences Addition #3200, Berkeley, CA 94720, USA
| | - Robert M Freeman
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Warren Alpert 536, Boston, MA 02115, USA
| | - Christopher J Lowe
- Hopkins Marine Station of Stanford University, 120 Oceanview Boulevard, Pacific Grove, CA 93950, USA
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Remarkable similarities between the hemichordate (Saccoglossus kowalevskii) and vertebrate GPCR repertoire. Gene 2013; 526:122-33. [DOI: 10.1016/j.gene.2013.05.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 05/02/2013] [Accepted: 05/06/2013] [Indexed: 12/26/2022]
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Sánchez RS, Sánchez SS. Characterization of pax1, pax9, and uncx sclerotomal genes during Xenopus laevis embryogenesis. Dev Dyn 2013; 242:572-9. [PMID: 23401059 DOI: 10.1002/dvdy.23945] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 11/29/2012] [Accepted: 01/31/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The axial skeleton develops from the sclerotome, a mesenchymal cell population derived from somites. Sclerotomal cells migrate from somites to the perinotochordal and perineural space where they differentiate into chondrocytes to form cartilage and bone. In anurans, little is known about the way how the sclerotome changes as development proceeds and how these events are regulated at the molecular level. Pax1, Pax9, and Uncx4.1 genes play a central role in the morphogenesis of the axial skeleton in vertebrates, regulating cell proliferation and chondrogenic specification of the sclerotome. RESULTS In this work, we cloned and examined through whole-mount in situ hybridization and reverse transcriptase-polymerase chain reaction the expression patterns of pax1, pax9, and uncx transcription factors in the anuran Xenopus laevis. CONCLUSIONS We found that these genes are similarly expressed in the sclerotome and in the pharyngeal pouch. A detailed analysis of the location of these transcripts showed that they are expressed in different subdomains of the sclerotomal compartment and differ from that observed in other vertebrates.
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Adachi N, Takechi M, Hirai T, Kuratani S. Development of the head and trunk mesoderm in the dogfish, Scyliorhinus torazame: II. Comparison of gene expression between the head mesoderm and somites with reference to the origin of the vertebrate head. Evol Dev 2013; 14:257-76. [PMID: 23017074 DOI: 10.1111/j.1525-142x.2012.00543.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The vertebrate mesoderm differs distinctly between the head and trunk, and the evolutionary origin of the head mesoderm remains enigmatic. Although the presence of somite-like segmentation in the head mesoderm of model animals is generally denied at molecular developmental levels, the appearance of head cavities in elasmobranch embryos has not been explained, and the possibility that they may represent vestigial head somites once present in an amphioxus-like ancestor has not been ruled out entirely. To examine whether the head cavities in the shark embryo exhibit any molecular signatures reminiscent of trunk somites, we isolated several developmentally key genes, including Pax1, Pax3, Pax7, Pax9, Myf5, Sonic hedgehog, and Patched2, which are involved in myogenic and chondrogenic differentiation in somites, and Pitx2, Tbx1, and Engrailed2, which are related to the patterning of the head mesoderm, from an elasmobranch species, Scyliorhinus torazame. Observation of the expression patterns of these genes revealed that most were expressed in patterns that resembled those found in amniote embryos. In addition, the head cavities did not exhibit an overt similarity to somites; that is, the similarity was no greater than that of the unsegmented head mesoderm in other vertebrates. Moreover, the shark head mesoderm showed an amniote-like somatic/visceral distinction according to the expression of Pitx2, Tbx1, and Engrailed2. We conclude that the head cavities do not represent a manifestation of ancestral head somites; rather, they are more likely to represent a derived trait obtained in the lineage of gnathostomes.
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Affiliation(s)
- Noritaka Adachi
- Laboratory for Evolutionary Morphology, RIKEN Center for Developmental Biology, Kobe, Japan
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31
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Manousaki T, Feiner N, Begemann G, Meyer A, Kuraku S. Co-orthology of Pax4 and Pax6 to the fly eyeless gene: molecular phylogenetic, comparative genomic, and embryological analyses. Evol Dev 2013; 13:448-59. [PMID: 23016906 DOI: 10.1111/j.1525-142x.2011.00502.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The functional equivalence of Pax6/eyeless genes across distantly related animal phyla has been one of central findings on which evo-devo studies is based. In this study, we show that Pax4, in addition to Pax6, is a vertebrate ortholog of the fly eyeless gene (and its duplicate, twin of eyeless [toy] gene, unique to Insecta). Molecular phylogenetic trees published to date placed the Pax4 gene outside the Pax6/eyeless subgroup as if the Pax4 gene originated from a gene duplication before the origin of bilaterians. However, Pax4 genes had only been reported for mammals. Our molecular phylogenetic analysis, including previously unidentified teleost fish pax4 genes, equally supported two scenarios: one with the Pax4-Pax6 duplication early in vertebrate evolution and the other with this duplication before the bilaterian radiation. We then investigated gene compositions in the genomic regions containing Pax4 and Pax6, and identified (1) conserved synteny between these two regions, suggesting that the Pax4-Pax6 split was caused by a large-scale duplication and (2) its timing within early vertebrate evolution based on the duplication timing of the members of neighboring gene families. Our results are consistent with the so-called two-round genome duplications in early vertebrates. Overall, the Pax6/eyeless ortholog is merely part of a 2:2 orthology relationship between vertebrates (with Pax4 and Pax6) and the fly (with eyeless and toy). In this context, evolution of transcriptional regulation associated with the Pax4-Pax6 split is also discussed in light of the zebrafish pax4 expression pattern that is analyzed here for the first time.
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Affiliation(s)
- Tereza Manousaki
- Laboratory for Zoology and Evolutionary Biology, Department of Biology, University of Konstanz, Universitätsstrasse 10, 78464, Konstanz, Germany
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32
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Röttinger E, Lowe CJ. Evolutionary crossroads in developmental biology: hemichordates. Development 2012; 139:2463-75. [PMID: 22736243 DOI: 10.1242/dev.066712] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Hemichordates are a deuterostome phylum, the sister group to echinoderms, and closely related to chordates. They have thus been used to gain insights into the origins of deuterostome and chordate body plans. Developmental studies of this group have a long and distinguished history. Recent improvements in animal husbandry, functional tool development and genomic resources have resulted in novel developmental data from several species in this group. In this Primer, we introduce representative hemichordate species with contrasting modes of development and summarize recent findings that are beginning to yield important insights into deuterostome developmental mechanisms.
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Affiliation(s)
- Eric Röttinger
- Kewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawaii, Honolulu, HI 96734, USA
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33
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Urata M, Iwasaki S, Ohtsuka S. Biology of the swimming acorn worm Glandiceps hacksi from the Seto Inland Sea of Japan. Zoolog Sci 2012; 29:305-10. [PMID: 22559964 DOI: 10.2108/zsj.29.305] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The enteropneust hemichordate Glandiceps hacksi inhabits the muddy bottoms of the intertidal to subtidal zones of Koguno-shima Island, located in the central part of the Seto Inland Sea of Japan. Monthly collections from October 2005 to September 2007 revealed that their spawning occurs once a year, in the latter half of May. Parameters such as density and sex ratio, as well as the type of sediment, were also examined. Worm behavior and type of burrows revealed that G. hacksi are infaunal burrowers. Autotomy and regeneration of their posterior regions, and swimming behavior were also observed in an aquarium environment. This is the first comprehensive study on the biology of G. hacksi, the swimming acorn worm.
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Affiliation(s)
- Makoto Urata
- Marine Biological Laboratory, Graduate School of Science, Hiroshima University, 2445 Mukaishima-cho, Onomichi, Hiroshima 722-0073, Japan.
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34
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Yoshida R, Sasakura Y. Establishment of enhancer detection lines expressing GFP in the gut of the ascidian Ciona intestinalis. Zoolog Sci 2012; 29:11-20. [PMID: 22233491 DOI: 10.2108/zsj.29.11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The gut is a tubular, endodermal organ for digesting food and absorbing nutrients. In this study, we characterized eight enhancer detection lines that express green fluorescent protein (GFP) in the whole or part of the digestive tube of the ascidian Ciona intestinalis. Three enhancer detection lines for the pyloric gland, a structure associated with the digestive tube, were also analyzed. These lines are valuable markers for analyzing the mechanisms of development of the gut. Based on the GFP expression of the enhancer detection lines together with morphological characteristics, the digestive tube of Ciona can be subdivided into at least 10 compartments in which different genetic cascades operate. Causal insertion sites of the enhancer detection lines were identified, and the expression pattern of the genes near the insertion sites were characterized by means of whole-mount in situ hybridization. We have characterized four and two genes that were specifically or strongly expressed in the digestive tube and pyloric gland, respectively. The present data provide the basic information and useful resources for studying gut formation in Ciona.
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Affiliation(s)
- Reiko Yoshida
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan
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35
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Gillis JA, Fritzenwanker JH, Lowe CJ. A stem-deuterostome origin of the vertebrate pharyngeal transcriptional network. Proc Biol Sci 2011; 279:237-46. [PMID: 21676974 DOI: 10.1098/rspb.2011.0599] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Hemichordate worms possess ciliated gills on their trunk, and the homology of these structures with the pharyngeal gill slits of chordates has long been a topic of debate in the fields of evolutionary biology and comparative anatomy. Here, we show conservation of transcription factor expression between the developing pharyngeal gill pores of the hemichordate Saccoglossus kowalevskii and the pharyngeal gill slit precursors (i.e. pharyngeal endodermal outpockets) of vertebrates. Transcription factors that are expressed in the pharyngeal endoderm, ectoderm and mesenchyme of vertebrates are expressed exclusively in the pharyngeal endoderm of S. kowalevskii. The pharyngeal arches and tongue bars of S. kowalevskii lack Tbx1-expressing mesoderm, and are supported solely by an acellular collagenous endoskeleton and by compartments of the trunk coelom. Our findings suggest that hemichordate and vertebrate gills are homologous as simple endodermal outpockets from the foregut, and that much vertebrate pharyngeal complexity arose coincident with the incorporation of cranial paraxial mesoderm and neural crest-derived mesenchyme within pharyngeal arches along the chordate and vertebrate stems, respectively.
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Affiliation(s)
- J Andrew Gillis
- Department of Organismal Biology and Anatomy, University of Chicago, 1027 East 57th Street, Chicago, IL 60637, USA.
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36
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Spatiotemporal expression of Pax genes in amphioxus: insights into Pax-related organogenesis and evolution. SCIENCE CHINA-LIFE SCIENCES 2010; 53:1031-40. [PMID: 20821303 DOI: 10.1007/s11427-010-4040-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Accepted: 02/05/2010] [Indexed: 12/28/2022]
Abstract
The expression of four AmphiPax genes in 16 developmental stages and different organs in amphioxus (Branchiostoma belcheri) was investigated, finding those genes expressed throughout amphioxus life with temporal-specific (especially during embryogenesis and metamorphosis) and spatial-specific patterns. This study suggests that duplicated Pax genes in vertebrates might maintain most of their ancestral functions and also expand their expression patterns after the divergence of protochordates and vertebrates.
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37
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Islam AFMT, Moly PK, Miyamoto Y, Kusakabe TG. Distinctive expression patterns of Hedgehog pathway genes in the Ciona intestinalis larva: implications for a role of Hedgehog signaling in postembryonic development and chordate evolution. Zoolog Sci 2010; 27:84-90. [PMID: 20141412 DOI: 10.2108/zsj.27.84] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Members of the Hedgehog (Hh) family are soluble ligands that orchestrate a wide spectrum of developmental processes ranging from left-right axis determination of the embryo to tissue patterning and organogenesis. Tunicates, including ascidians, are the closest relatives of vertebrates, and elucidation of Hh signaling in ascidians should provide an important clue towards better understanding the role of this pathway in development. In previous studies, expression patterns of genes encoding Hh and its downstream factor Gli have been examined up to the tailbud stage in the ascidian embryo, but their expression in the larva has not been reported. Here we show the spatial expression patterns of hedgehog (Ci-hh1, Ci-hh2), patched (Ci-ptc), smoothened (Ci-smo), and Gli (Ci-Gli) orthologs in larvae of the ascidian Ciona intestinalis. The expression patterns of Ci-hh2 and Ci-Gli dramatically change during the period between the late tailbud embryo and the swimming larva. At the larval stage, expression of Ci-Gli was found in a central part of the endoderm and in the visceral ganglion, while Ci-hh2 was expressed in two discrete endodermal regions, anteriorly and posteriorly adjacent to the cells expressing Gli. The expression patterns of these genes suggest that the Hh ligand controls postembryonic development of the endoderm and the central nervous system. Expression of a gene encoding Hh in the anterior and/or pharyngeal endoderm is probably an ancient chordate character; diversification of regulation and targets of the Hh signaling in this region may have played a major role in the evolution of chordate body structures.
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GONZALEZ PAUL, CAMERON CHRISTOPHERB. The gill slits and pre-oral ciliary organ of Protoglossus (Hemichordata: Enteropneusta) are filter-feeding structures. Biol J Linn Soc Lond 2009. [DOI: 10.1111/j.1095-8312.2009.01332.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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39
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Molecular phylogeny of hemichordata, with updated status of deep-sea enteropneusts. Mol Phylogenet Evol 2009; 52:17-24. [DOI: 10.1016/j.ympev.2009.03.027] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 12/18/2008] [Accepted: 03/25/2009] [Indexed: 11/20/2022]
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40
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Campo-Paysaa F, Marlétaz F, Laudet V, Schubert M. Retinoic acid signaling in development: Tissue-specific functions and evolutionary origins. Genesis 2008; 46:640-56. [PMID: 19003929 DOI: 10.1002/dvg.20444] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Florent Campo-Paysaa
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242-INRA 1288-ENS-UCBL, IFR128 BioSciences Lyon-Gerland, Ecole Normale Supérieure de Lyon, Lyon, France
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41
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Lowe CJ. Molecular genetic insights into deuterostome evolution from the direct-developing hemichordate Saccoglossus kowalevskii. Philos Trans R Soc Lond B Biol Sci 2008; 363:1569-78. [PMID: 18192177 DOI: 10.1098/rstb.2007.2247] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Progress in developmental biology, phylogenomics and palaeontology over the past five years are all making major contributions to a long-enduring problem in comparative biology: the early origins of the deuterostome phyla. Recent advances in the developmental biology of hemichordates have given a unique insight into developmental similarities between this phylum and chordates. Transcriptional and signalling gene expression patterns between the two groups during the early development of the anteroposterior and dorsoventral axes reveal close similarities, despite large morphological disparity between the body plans. These genetic networks have been proposed to play conserved roles in patterning centralized nervous systems in metazoans, yet seem to play a conserved role in patterning the diffusely organized basiepithelial nerve net of the hemichordates. Developmental genetic data are providing a unique insight into early deuterostome evolution, revealing a complexity of genetic regulation previously attributed only to vertebrates. While these data allow for key insights into the development of early deuterostomes, their utility for reconstructing ancestral morphologies is less certain, and morphological, palaeontological and molecular datasets should all be considered carefully when speculating about ancestral deuterostome features.
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Affiliation(s)
- Christopher J Lowe
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA.
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42
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Graham A. Deconstructing the pharyngeal metamere. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2008; 310:336-44. [PMID: 17583579 DOI: 10.1002/jez.b.21182] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A prominent feature of all vertebrate embryos is the presence of a series of bulges on the lateral surface of the head, the pharyngeal arches. These structures constitute a metameric series, with each arch forming a similar set of derivatives. Significantly, the development of the pharyngeal arches is complex as it involves interactions between disparate embryonic cell types: ectoderm, endoderm, mesoderm and neural crest. It is becoming increasingly apparent that the development of the pharyngeal metamere revolves around the pharyngeal endoderm. The segmentation of this tissue is central to the generation of the arches. The pharyngeal endoderm also provides positional cues for the neural crest, and is involved in the induction of a number of components of the pharyngeal metamere. The segmentation of the pharyngeal endoderm has also been key to the evolution of pharyngeal metamerism. It is likely that endodermal segmentation is a deuterostome characteristic and that this basic pattern was sequentially modified and over time the more complex pharyngeal metamere of vertebrates emerged.
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Affiliation(s)
- Anthony Graham
- MRC Centre for Developmental Neurobiology, Guys Campus, King's College London, London, United Kingdom.
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43
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Freeman RM, Wu M, Cordonnier-Pratt MM, Pratt LH, Gruber CE, Smith M, Lander ES, Stange-Thomann N, Lowe CJ, Gerhart J, Kirschner M. cDNA sequences for transcription factors and signaling proteins of the hemichordate Saccoglossus kowalevskii: efficacy of the expressed sequence tag (EST) approach for evolutionary and developmental studies of a new organism. THE BIOLOGICAL BULLETIN 2008; 214:284-302. [PMID: 18574105 DOI: 10.2307/25470670] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We describe a collection of expressed sequence tags (ESTs) for Saccoglossus kowalevskii, a direct-developing hemichordate valuable for evolutionary comparisons with chordates. The 202,175 ESTs represent 163,633 arrayed clones carrying cDNAs prepared from embryonic libraries, and they assemble into 13,677 continuous sequences (contigs), leaving 10,896 singletons (excluding mitochondrial sequences). Of the contigs, 53% had significant matches when BLAST was used to query the NCBI databases (< or = 10(-10)), as did 51% of the singletons. Contigs most frequently matched sequences from amphioxus (29%), chordates (67%), and deuterostomes (87%). From the clone array, we isolated 400 full-length sequences for transcription factors and signaling proteins of use for evolutionary and developmental studies. The set includes sequences for fox, pax, tbx, hox, and other homeobox-containing factors, and for ligands and receptors of the TGFbeta, Wnt, Hh, Delta/Notch, and RTK pathways. At least 80% of key sequences have been obtained, when judged against gene lists of model organisms. The median length of these cDNAs is 2.3 kb, including 1.05 kb of 3' untranslated region (UTR). Only 30% are entirely matched by single contigs assembled from ESTs. We conclude that an EST collection based on 150,000 clones is a rich source of sequences for molecular developmental work, and that the EST approach is an efficient way to initiate comparative studies of a new organism.
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Affiliation(s)
- R M Freeman
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Mise T, Iijima M, Inohaya K, Kudo A, Wada H. Function of Pax1 and Pax9 in the sclerotome of medaka fish. Genesis 2008; 46:185-92. [PMID: 18395830 DOI: 10.1002/dvg.20381] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We examined the expression and functions of Pax1 and Pax9 in a teleost fish, the medaka Oryzias latipes. While Pax1 and Pax9 show distinct expression in the sclerotome in amniotes, we could not detect the differential expression of Pax1 and Pax9 in the developing sclerotome of the medaka. Furthermore, unlike the mouse, in which Pax1 is essential for development of the vertebral body, and where the neural arch is formed independent of either Pax1 or Pax9, our morpholino knockdown experiments revealed that both Pax1 and Pax9 are indispensable for the development of the vertebral body and neural arch. Therefore, we conclude that after gene duplication, Pax1 and Pax9 subfunctionalize their roles in the sclerotome independently in teleosts and amniotes. In Stage-30 embryo, Pax9 was strongly expressed in the posterior mesoderm, as was also observed for mouse Pax9. Since this expression was not detected for Pax1 in the mouse or fish, this new expression in the posterior mesoderm likely evolved in Pax9 of ancestral vertebrates after gene duplication. Two-month-old fish injected with Pax9 morpholino oligonucleotide showed abnormal morphology in the tail hypural skeletal element, which may have been related to this expression.
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Affiliation(s)
- Takeshi Mise
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
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The Evolution of Alternative Splicing in the Pax Family: The View from the Basal Chordate Amphioxus. J Mol Evol 2008; 66:605-20. [DOI: 10.1007/s00239-008-9113-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Revised: 04/16/2008] [Accepted: 04/22/2008] [Indexed: 10/22/2022]
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Rychel AL, Swalla BJ. Development and evolution of chordate cartilage. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2008; 308:325-35. [PMID: 17358002 DOI: 10.1002/jez.b.21157] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Deuterostomes are a monophyletic group of animals containing vertebrates, lancelets, tunicates, hemichordates, echinoderms, and xenoturbellids. Four out of these six extant groups-vertebrates, lancelets, tunicates, and hemichordates-have pharyngeal gill slits. All groups of deuterostome animals that have pharyngeal gill slits also have a pharyngeal skeleton supporting the pharyngeal openings, except tunicates. We previously found that pharyngeal cartilage in hemichordates and cephalochordates contains a fibrillar collagen protein similar to vertebrate type II collagen, but unlike vertebrate cartilage, the invertebrate deuterostome cartilages are acellular. We found SoxE and fibrillar collagen expression in the pharyngeal endodermal cells adjacent to where the cartilages form. These same endodermal epithelial cells also express Pax1/9, a marker of pharyngeal endoderm in vertebrates, lancelets, tunicates, and hemichordates. In situ experiments with a cephalochordate fibrillar collagen also showed expression in pharyngeal endoderm, as well as the ectoderm and the mesodermal coelomic pouches lining the gill bars. These results indicate that the pharyngeal endodermal cells are responsible for secretion of the cartilage in hemichordates, whereas in lancelets, all the pharyngeal cells surrounding the gill bars, ectodermal, endodermal, and mesodermal may be responsible for cartilage formation. We propose that endoderm secretion was primarily the ancestral mode of making pharyngeal cartilages in deuterostomes. Later the evolutionary origin of neural crest allowed co-option of the gene network for the secretion of pharyngeal cartilage matrix in the new migratory neural crest cell populations found in vertebrates.
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Affiliation(s)
- Amanda L Rychel
- Biology Department and Center for Developmental Biology, University of Washington, Seattle, WA 98195, USA
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Jeffery WR. Chordate ancestry of the neural crest: New insights from ascidians. Semin Cell Dev Biol 2007; 18:481-91. [PMID: 17509911 DOI: 10.1016/j.semcdb.2007.04.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Revised: 01/31/2007] [Accepted: 04/10/2007] [Indexed: 11/29/2022]
Abstract
This article reviews new insights from ascidians on the ancestry of vertebrate neural crest (NC) cells. Ascidians have neural crest-like cells (NCLC), which migrate from the dorsal midline, express some of the typical NC markers, and develop into body pigment cells. These characters suggest that primordial NC cells were already present in the common ancestor of the vertebrates and urochordates, which have been recently inferred as sister groups. The primitive role of NCLC may have been in pigment cell dispersal and development. Later, additional functions may have appeared in the vertebrate lineage, resulting in the evolution of definitive NC cells.
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Affiliation(s)
- William R Jeffery
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
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Kozmik Z, Holland ND, Kreslova J, Oliveri D, Schubert M, Jonasova K, Holland LZ, Pestarino M, Benes V, Candiani S. Pax-Six-Eya-Dach network during amphioxus development: conservation in vitro but context specificity in vivo. Dev Biol 2007; 306:143-59. [PMID: 17477914 DOI: 10.1016/j.ydbio.2007.03.009] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Revised: 02/18/2007] [Accepted: 03/07/2007] [Indexed: 12/23/2022]
Abstract
The Drosophila retinal determination gene network occurs in animals generally as a Pax-Six-Eyes absent-Dachshund network (PSEDN). For amphioxus, we describe the complete network of nine PSEDN genes, four of which-AmphiSix1/2, AmphiSix4/5, AmphSix3/6, and AmphiEya-are characterized here for the first time. For amphioxus, in vitro interactions among the genes and proteins of the network resemble those of other animals, except for the absence of Dach-Eya binding. Amphioxus PSEDN genes are expressed in highly stage- and tissue-specific patterns (sometimes conspicuously correlated with the local intensity of cell proliferation) in the gastrular organizer, notochord, somites, anterior central nervous system, peripheral nervous system, pharyngeal endoderm, and the likely homolog of the vertebrate adenohypophysis. In this last tissue, the anterior region expresses all three amphioxus Six genes and is a zone of active cell proliferation, while the posterior region expresses only AmphiPax6 and is non-proliferative. In summary, the topologies of animal PSEDNs, although considerably more variable than originally proposed, are conserved enough to be recognizable among species and among developing tissues; this conservation may reflect indispensable involvement of PSEDNs during the critically important early phases of embryology (e.g. in the control of mitosis, apoptosis, and cell/tissue motility).
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Affiliation(s)
- Zbynek Kozmik
- Institute of Molecular Genetics, Videnska 1083, 14220 Prague 4, Czech Republic
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Bourlat SJ, Juliusdottir T, Lowe CJ, Freeman R, Aronowicz J, Kirschner M, Lander ES, Thorndyke M, Nakano H, Kohn AB, Heyland A, Moroz LL, Copley RR, Telford MJ. Deuterostome phylogeny reveals monophyletic chordates and the new phylum Xenoturbellida. Nature 2006; 444:85-8. [PMID: 17051155 DOI: 10.1038/nature05241] [Citation(s) in RCA: 349] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Accepted: 09/11/2006] [Indexed: 11/09/2022]
Abstract
Deuterostomes comprise vertebrates, the related invertebrate chordates (tunicates and cephalochordates) and three other invertebrate taxa: hemichordates, echinoderms and Xenoturbella. The relationships between invertebrate and vertebrate deuterostomes are clearly important for understanding our own distant origins. Recent phylogenetic studies of chordate classes and a sea urchin have indicated that urochordates might be the closest invertebrate sister group of vertebrates, rather than cephalochordates, as traditionally believed. More remarkable is the suggestion that cephalochordates are closer to echinoderms than to vertebrates and urochordates, meaning that chordates are paraphyletic. To study the relationships among all deuterostome groups, we have assembled an alignment of more than 35,000 homologous amino acids, including new data from a hemichordate, starfish and Xenoturbella. We have also sequenced the mitochondrial genome of Xenoturbella. We support the clades Olfactores (urochordates and vertebrates) and Ambulacraria (hemichordates and echinoderms). Analyses using our new data, however, do not support a cephalochordate and echinoderm grouping and we conclude that chordates are monophyletic. Finally, nuclear and mitochondrial data place Xenoturbella as the sister group of the two ambulacrarian phyla. As such, Xenoturbella is shown to be an independent phylum, Xenoturbellida, bringing the number of living deuterostome phyla to four.
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Affiliation(s)
- Sarah J Bourlat
- Department of Biology, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
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Shimazaki A, Sakai A, Ogasawara M. Gene expression profiles inCiona intestinalis stigmatal cells: Insight into formation of the ascidian branchial fissures. Dev Dyn 2006; 235:562-9. [PMID: 16342199 DOI: 10.1002/dvdy.20657] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gill slits, a series of openings in the pharyngeal epithelium, are characteristic features of the hemichordate and chordate body plans. In ascidians, these openings, called stigmata, are formed in the branchial sac during juvenile development. Multiple whole-mount in situ hybridization analyses based on approximately 1,500 genes expressed in Ciona intestinalis juveniles, identified 28 genes expressed predominantly in the stigmatal cells. Expression patterns of these stigmatal genes were classified into four different categories. On the basis of these findings, we have been able to show that the peripheral region of a stigma consists of at least three different regions. The expression of a Dlk1-like gene was detected in nonciliated cells during the stigma perforation and division and was maintained in the basal region of the elliptical stigma. Expression of meichroacidin, tektin A1, and tektin B1 orthologs during the differentiation of the ciliated stigmatal cells suggests that some of the molecular mechanisms involved in sperm differentiation might be recruited for the stigma development, or vice versa. Components of the cilia such as alpha-tubulin and rootletin were also expressed in the stigmatal cells. These genes might facilitate further analyses regarding the evolution of the branchial fissures and the development of the ascidian stigmata.
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Affiliation(s)
- Aki Shimazaki
- Department of Biology, Faculty of Science, Chiba University, Chiba, Japan
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