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Miyamoto N, Nishikawa T, Namikawa H. Cephalodiscus planitectus sp. nov. (Hemichordata: Pterobranchia) from Sagami Bay, Japan. Zoolog Sci 2020; 37:79-90. [PMID: 32068377 DOI: 10.2108/zs190010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 07/24/2019] [Indexed: 11/17/2022]
Abstract
We describe here a new pterobranch, Cephalodiscus planitectus sp. nov. This pterobranch was collected from rocky slopes, at 100-300 m depth, off Jogashima Island, Sagami Bay, Japan. The tubaria of this new species have unique morphological features that differentiate it from known species. The tubaria are usually isolated from one another and have a completely flat and smooth surface that is devoid of erect features and projecting spines. Each has a simple, non-branched tubular cavity that is usually inhabited by a mature animal and its asexually budding offspring. The zooids have three pairs of tentaculated arms. A single bud is produced on the dorsal side of the stalk in adult zooids. In one instance, a live embryo was observed rotating at the bottom of a tubarium. Molecular phylogenetic analysis showed that C. planitectus is a sister group to all other Cephalodiscus species analyzed to date.
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Affiliation(s)
- Norio Miyamoto
- X-STAR, Japan Agency for Marine-Earth Science and Technology, Yokosuka 237-0061, Japan,
| | - Teruaki Nishikawa
- Faculty of Science, Toho University, Miyama 2-2-1, Funabashi, Chiba 274-8510, Japan.,National Museum of Nature and Science, Amakubo 4-1-1, Tsukuba, Ibaraki 305-0005, Japan
| | - Hiroshi Namikawa
- National Museum of Nature and Science, Amakubo 4-1-1, Tsukuba, Ibaraki 305-0005, Japan,
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Abstract
Phylum Hemichordata, composed of worm-like Enteropneusta and colonial Pterobranchia, has been reported to only contain about 100 species. However, recent studies of hemichordate phylogeny and taxonomy suggest the species number has been largely underestimated. One issue is that species must be described by experts, and historically few taxonomists have studied this group of marine invertebrates. Despite this previous lack of coverage, interest in hemichordates has piqued in the past couple of decades, as they are critical to understanding the evolution of chordates–as acorn worms likely resemble the deuterostome ancestor more closely than any other extant animal. This review provides an overview of our current knowledge of hemichordates, focusing specifically on their global biodiversity, geographic distribution, and taxonomy. Using information available in the World Register of Marine Species and published literature, we assembled a list of 130 described, extant species. The majority (83%) of these species are enteropneusts, and more taxonomic descriptions are forthcoming. Ptychoderidae contained the greatest number of species (41 species), closely followed by Harrimaniidae (40 species), of the recognized hemichordate families. Hemichordates are found throughout the world’s oceans, with the highest reported numbers by regions with marine labs and diligent taxonomic efforts (e.g. North Pacific and North Atlantic). Pterobranchs are abundant in Antarctica, but have also been found at lower latitudes. We consider this a baseline report and expect new species of Hemichordata will continue to be discovered and described as new marine habitats are characterized and explored.
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Affiliation(s)
- Michael G. Tassia
- Department of Biology, University of Washington, Seattle, WA, United States of America
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA, United States of America
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, United States of America
| | - Johanna T. Cannon
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA, United States of America
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, United States of America
- Department of Zoology, Naturhistoriska riksmuseet, Stockholm, SE-104 05, Sweden
| | - Charlotte E. Konikoff
- Department of Biology, University of Washington, Seattle, WA, United States of America
| | - Noa Shenkar
- Department of Biology, University of Washington, Seattle, WA, United States of America
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA, United States of America
- Department of Zoology, George S. Wise Faculty of Life Science, Tel-Aviv University, Tel-Aviv, Israel
| | - Kenneth M. Halanych
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA, United States of America
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, United States of America
| | - Billie J. Swalla
- Department of Biology, University of Washington, Seattle, WA, United States of America
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA, United States of America
- * E-mail:
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Arimoto A, Tagawa K. Hedgehog Expression During Development and Regeneration in the Hemichordate, Ptychodera flava. Zoolog Sci 2016; 32:33-7. [PMID: 25660694 DOI: 10.2108/zs140157] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Hedgehog is a toolkit gene conserved in metazoans. However, its function differs among taxa, and it shows versatile expression patterns in morphogenesis. We analyzed the expression pattern of hedgehog in the indirect development of the hemichordate, Ptychodera flava, during development and regeneration. Pf-Hh showed distinct enteropneust-specific expression at the anterior tip of the larvae, as well as deuterostome-conserved expression in the pharyngeal endoderm. In contrast, the gene is expressed only in the pharyngeal region during anterior regeneration, but not in the anterior tip of the proboscis. These data suggest that anterior regeneration is driven not only by conserved developmental mechanisms, but also by some regeneration-specific mechanism(s).
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Affiliation(s)
- Asuka Arimoto
- Marine Biological Laboratory, Graduate School of Science, Hiroshima University, Onomichi, Hiroshima 722-00073, Japan
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Chen SH, Li KL, Lu IH, Wang YB, Tung CH, Ting HC, Lin CY, Lin CY, Su YH, Yu JK. Sequencing and analysis of the transcriptome of the acorn worm Ptychodera flava, an indirect developing hemichordate. Mar Genomics 2014; 15:35-43. [PMID: 24823299 DOI: 10.1016/j.margen.2014.04.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 04/28/2014] [Accepted: 04/28/2014] [Indexed: 12/13/2022]
Abstract
Hemichordates are the sister group of echinoderms, and together they are closely related to chordates within the deuterostome lineage. Therefore, hemichordates represent an important animal group for the understanding of both the evolution of developmental mechanisms in deuterostome animals and the origin of chordates. Recently, the majority of studies investigating hemichordates have focused on the direct-developing enteropneust hemichordate Saccoglossus kowalevskii; few have focused on the indirect-developing hemichordates, partly because of the lack of extensive genomic resources in these animals. In this study, we report the sequencing and analysis of a transcriptome from an indirect-developing enteropneust hemichordate Ptychodera flava. We sequenced a mixed cDNA library from six developmental stages using the Roche GS FLX Titanium System to generate more than 879,000 reads. These reads were assembled into 17,990 contigs with an average length of 1316bp. We found that 60% of the assembled contigs, along with 28% of the unassembled singleton reads, had significant hits to sequences in the NCBI database by a BLASTx search, and we also annotated these sequences and obtained Gene Ontology (GO) terms for 6744 contigs and 5802 singletons. We further identified candidate P. flava transcripts corresponding to genes involved in major developmental signaling pathways, including the Wnt, Notch and TGF-β signaling pathways. Using available genome/transcriptome datasets from the direct-developing hemichordate S. kowalevskii, the echinoderm Strongylocentrotus purpuratus and the chordate Branchiostoma floridae, we found that 90%, 80% and 73% of the annotated protein sequences in these respective species matched our P. flava transcriptome in a homology search. We also constructed a database for the P. flava transcriptome, and researchers can easily access this dataset online. Our dataset significantly increases the amount of available P. flava sequence data and can serve as a reference transcriptome for future studies using this species.
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Affiliation(s)
- Shu-Hwa Chen
- Institute of Information Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan
| | - Kun-Lin Li
- Institute of Information Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan; Institute of Fisheries Science, National Taiwan University, Taipei, Taiwan
| | - I-Hsuan Lu
- Institute of Information Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan
| | - Yu-Bin Wang
- Institute of Information Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan
| | - Che-Huang Tung
- Institute of Cellular and Organismic Biology, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan
| | - Hsiu-Chi Ting
- Institute of Cellular and Organismic Biology, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan
| | - Ching-Yi Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan; Institute of Oceanography, National Taiwan University, Taipei, Taiwan
| | - Chung-Yen Lin
- Institute of Information Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan; Institute of Fisheries Science, National Taiwan University, Taipei, Taiwan; Institute of Population Health Sciences, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli County 35053, Taiwan.
| | - Yi-Hsien Su
- Institute of Cellular and Organismic Biology, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan.
| | - Jr-Kai Yu
- Institute of Cellular and Organismic Biology, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei 11529, Taiwan; Institute of Oceanography, National Taiwan University, Taipei, Taiwan.
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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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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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Robertshaw E, Kiecker C. Phylogenetic origins of brain organisers. SCIENTIFICA 2012; 2012:475017. [PMID: 24278699 PMCID: PMC3820451 DOI: 10.6064/2012/475017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 06/21/2012] [Indexed: 06/02/2023]
Abstract
The regionalisation of the nervous system begins early in embryogenesis, concomitant with the establishment of the anteroposterior (AP) and dorsoventral (DV) body axes. The molecular mechanisms that drive axis induction appear to be conserved throughout the animal kingdom and may be phylogenetically older than the emergence of bilateral symmetry. As a result of this process, groups of patterning genes that are equally well conserved are expressed at specific AP and DV coordinates of the embryo. In the emerging nervous system of vertebrate embryos, this initial pattern is refined by local signalling centres, secondary organisers, that regulate patterning, proliferation, and axonal pathfinding in adjacent neuroepithelium. The main secondary organisers for the AP neuraxis are the midbrain-hindbrain boundary, zona limitans intrathalamica, and anterior neural ridge and for the DV neuraxis the notochord, floor plate, and roof plate. A search for homologous secondary organisers in nonvertebrate lineages has led to controversy over their phylogenetic origins. Based on a recent study in hemichordates, it has been suggested that the AP secondary organisers evolved at the base of the deuterostome superphylum, earlier than previously thought. According to this view, the lack of signalling centres in some deuterostome lineages is likely to reflect a secondary loss due to adaptive processes. We propose that the relative evolutionary flexibility of secondary organisers has contributed to a broader morphological complexity of nervous systems in different clades.
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Affiliation(s)
- Ellen Robertshaw
- MRC Centre for Developmental Neurobiology, King's College London, 4th Floor, New Hunt's House, Guy's Hospital Campus, London SE1 1UL, UK
| | - Clemens Kiecker
- MRC Centre for Developmental Neurobiology, King's College London, 4th Floor, New Hunt's House, Guy's Hospital Campus, London SE1 1UL, UK
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Chordate roots of the vertebrate nervous system: expanding the molecular toolkit. Nat Rev Neurosci 2009; 10:736-46. [PMID: 19738625 DOI: 10.1038/nrn2703] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The vertebrate brain is highly complex with millions to billions of neurons. During development, the neural plate border region gives rise to the neural crest, cranial placodes and, in anamniotes, to Rohon-Beard sensory neurons, whereas the boundary region of the midbrain and hindbrain develops organizer properties. Comparisons of developmental gene expression and neuroanatomy between vertebrates and the basal chordate amphioxus, which has only thousands of neurons and lacks a neural crest, most placodes and a midbrain-hindbrain organizer, indicate that these vertebrate features were built on a foundation already present in the ancestral chordate. Recent advances in genomics have provided insights into the elaboration of the molecular toolkit at the invertebrate-vertebrate transition that may have facilitated the evolution of these vertebrate characteristics.
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