発生運命決定機構」プロジェクト（1996-2001） Mechanisms of Fate Determination during Embryogenesis

研究目的

受精卵は細胞分裂を繰り返し、筋肉・神経・表皮などのさまざまなタイプの細胞を作り上げていく。すなわち、初期発生過程において、各々の割球がどの組織を作る細胞になるのか（発生運命）の決定機構を解明するのが本プロジェクトの目的である。

本研究の独創的な点は、発生運命の決定機構に関して、ホヤという実験動物を取り上げ、それをまるごと一匹分、解明しようとするところにある。ホヤのオタマジャクシ幼生は単純な構造を持ち、少数の細胞でできている。このことは、胚発生における発生運命の決定機構を組織ごとに、かつ全ての組織について明らかにできるという可能性を示唆している。運命決定の全体像を明らかにすることにより、一つの種の発生に関してどんなメカニズムが、どのぐらいの頻度で使われているのかが明らかになるだろう。単純ではあるが、脊椎動物の原型をなす動物を用い、一種類の動物についてではあるが、そのほとんどの組織について決定機構を解明することは、発生学の進歩において有意義な一里塚になると考えている。また、ホヤは人間と同じ脊索動物門に属しており、ホヤ胚発生における発生運命決定機構の解明は、より複雑な脊椎動物の発生メカニズムの解明につながることが期待できる。

Fertilized eggs cleave many times to give rise to multicellular organisms. Within a multicellular embryo, some embryonic blastomeres develop into one type of tissue, whereas other blastomeres develop into another type of tissue. Each cell of an early embryo becomes restricted to a particular developmental fate by developing along one of several developmental pathways. We are examining how developmental fates of embryonic cells are specified.

In this project, we study ascidian embryo genesis as a model system at cellular and molecular level. While ascidian tadpole larvae exhibit the basic body plan of a vertebrate, the ascidian larval body plan is relatively simple, consisting of only a few kinds of tissue and of a relatively small number of cells. This less complex body plan allows us to analyze the various mechanisms of cellular specification for each cell type more easily. Indeed, it becomes possible to totally understand the cellular basis of how the tadpole larva is formed during development. The study of ascidian embryo genesis made exciting new contributions toward understanding the development of higher vertebrates as well as helping our understanding of the basic developmental processes that are shared by all chordates.

構成員

註：構成員の所属などは当時のものです。

プロジェクトリーダー

  • 西田 宏記 Hiroki Nishida
  • 　東京工業大学生命理工学部生命理学科　助教授
  • 　〒226-8501　横浜市緑区長津田町4259
  • 　電話：045-924-5722
  • 　FAX：045-924-5777
  • 　e-mail：hnishida at bio.titech.ac.jp

コアメンバー

  • 真壁 和裕 Kazuhiro W. Makabe
  • 　京都大学大学院理学研究科動物学　助手
  • 　〒606-01　京都市左京区北白川追分町
  • 　電話：075-753-4102
  • 　FAX：075-705-1113
  • 　e-mail：kwmakabe at ascidian.zool.kyoto-u.ac.jp
  • 西方 敬人 Nishikata Takahito
  • 　甲南大学理学部生物学科 講師
  • 　〒658-8501　神戸市東灘区岡本8-9-1
  • 　電話：078-435-2511
  • 　FAX：078-435-2539
  • 　e-mail：nisikata at base2.ipc.konan-u.ac.jp

プロジェクトメンバー

  • 西駕 秀俊 Hidetoshi Saiga
  • 　東京都立大学大学院理学研究科生物学専攻 助教授
  • 　〒192-03　東京都八王子市南大沢１ー１
  • 　電話：0426-77-2573
  • 　FAX：0427-77-2559
  • 　e-mail：saiga-hidetoshi at c.metro-u.ac.jp
  • 高村 克美 Katsumi Takamura
  • 　福山大学工学部生物工学科 助手
  • 　〒729-02　広島県福山市東村町字三蔵 985
  • 　電話：0426-77-2573
  • 　FAX：0427-77-2559
  • 　e-mail：takamura at bt.fubt.fukuyama-u.ac.jp
  • William R. Bates
  • 　University of Victoria Bamfield Marine Station Associate Professor
  • 　Bamfield, British Columbia VOR 1BO, Canada
  • 　電話：604-728-301
  • 　FAX：604-728-3452
  • 　e-mail：bbates at bms.bc.ca

リサーチ・アソシエイト

  • 澤田 佳一郎 Kaitiro Sawada
  • 　東京工業大学生命理工学部生命理学科 リサーチ・アソシエイト
  • 　〒226-8501　横浜市緑区長津田町4259
  • 　電話：045-924-5721
  • 　FAX：045-924-5777
  • 　e-mail：kasawada at bio.titech.ac.jp
  • 宮 隆史 Takahito Miya
  • 　東京工業大学生命理工学部生命理学科 リサーチ・アソシエイト
  • 　〒226-8501　横浜市緑区長津田町4259
  • 　電話：045-924-5721
  • 　FAX：045-924-5777
  • 　e-mail：tmiya at bio.titech.ac.jp
  • 諸熊 淳治 Junji Morokuma
  • 　東京工業大学生命理工学部生命理学科 リサーチ・アソシエイト
  • 　〒226-8501　横浜市緑区長津田町4259
  • 　電話：045-924-5721
  • 　FAX：045-924-5777
  • 　e-mail：jimoro at bio.titech.ac.jp
  • 　http://www.hoya.bio.titech.ac.jp/morokuma/

個別の研究課題、研究目的、最近の業績

西田 宏記 Hiroki Nishida

研究課題

  • ホヤ胚発生過程における発生運命決定機構
  • Mechanisms of Fate Determination during Ascidian Embryogenesis

研究目的

動物の初期胚において、発生運命の決定様式を卵細胞質内決定因子と細胞間相互作用に注目して解析する。

Mechanisms of fate determination during animal embryogenesis will be analyzed focusing on cytoplasmic determinants and cellular interactions.

最近の業績

  • Hiroki Nishida
  • Determination at the last cell cycle before fate restriction.
  • Zoological Science (1996) Vol.13. pp.15-20.
  • Hiroki Nishida
  • Vegetal egg cytoplasm promotes gastrulation and is responsible for specification of vegetal blastomeres in embryos of the ascidian Halocynthia roretzi.
  • Development (1996) Vol. 122. pp.1271-1279.
  • Yuki Nakatani, Hitoyoshi Yasuo, Noriyuki Satoh, and Hiroki Nishida
  • Basic fibroblast growth factor induces notochord formation and the expression of As-T, a brachyury homolog, during ascidian embryogenesis.
  • Development (1996) 122, 2023-2031.
  • Gaku Kumano, Hideyoshi Yokosawa and Hiroki Nishida
  • Biochemical evidence for membrane-bound endoderm-specific alkaline phosphatase in larvae of the ascidian, Halocynthia roretzi.
  • Eur. J. Biochem. (1996) 240, 485-489.
  • Atsuko Yamada and Hiroki Nishida
  • Distribution of cytoplasmic determinants in unfertilized eggs of the ascidian Halocynthia roretzi.
  • Development, Genes and Evolution (1996) 206, 297-304.
  • Satoshi Kawaminami and Hiroki Nishida
  • Induction of trunk lateral cells, the blood cell precursors, during ascidian embryogenesis.
  • Developmental Biology (1997) 181, 14-20.
  • Hiroki Nishida and Gaku Kumano
  • Analysis of temporal expression of the endoderm-specific alkaline phosphatase during development of the ascidian, Halocynthia roretzi.
  • Development Growth and Differentiation (1997) 39, 199-203.
  • Hiroki Nishida
  • Cell-fate specification by localized cytoplasmic determinants and cell interactions in ascidian embryos
  • International Review of Cytology (1997) 176, 245-306.
  • Hiroki Nishida
  • Cell lineage and timing of fate restriction, determination and gene expression in ascidian embryos
  • Seminars in Cell and Developmental Biology (1997) 8, 359-365.
  • Sawako Hori, Takashi Saitoh, Midori Matsumoto, Kazuhiro W. Makabe and Hiroki Nishida
  • A Notch homologue from Halocynthia roretzi is preferentially expressed in the central nervous system during ascidian embryogenesis
  • Development, Genes and Evolution (1997) 207, 371-380.
  • Yuki Nakatani and Hiroki Nishida
  • Ras is an essential component for notochord formation during ascidian embryogenesis
  • Mechanisms of Development (1997) 68, 81-89.
  • Toshio Hirano and Hiroki Nishida
  • Developmental fates of larval tissues after metamorphosis in ascidian, Halocynthia roretzi. I. Origin of mesodermal tissues of the juvenile.
  • Developmental Biology (1997) 192, 199-210.
  • Taku Hibino, Takahito Nishikata and Hiroki Nishida
  • CAB (Centrosome-attracting body): A novel structure closely related to unequal cleavages in the ascidian embryo.
  • Development Growth and Differentiation (1998) 40, 85-95.
  • William R. Bates and Hiroki Nishida
  • Developmental roles of nuclear complex factors released during oocyte maturation in the ascidians Halocynthia roretzi and Boltenia villosa.
  • Zoological Science (1998) 15, 69-76.
  • Gaku Kumano and Hiroki Nishida
  • Maternal and zygotic expression of the endoderm-specific alkaline phosphatase gene in embryos of the ascidian, Halocynthia roretzi.
  • Developmental Biology (1998) 198, 245-252.
  • Gil Jung Kim and Hiroki Nishida
  • Monoclonal antibodies against differentiating mesenchyme cells in larvae of the ascidian, Halocynthia roretzi.
  • Zoological Science (1998) 15, 553-559.
  • Takuya Oka, Reiko Amikura, Satoru Kobayashi and Hiroki Nishida
  • Localization of mitochondrial large ribosomal RNA in myoplasm of the early ascidian embryos.
  • Development Growth and Differentiation (1998) 41, 1-8.
  • Hiroki Nishida and Kazuhiro W. Makabe
  • Maternal information and localized maternal mRNA in eggs and early embryos of the ascidian Halocynthia roretzi.
  • Invertebrate Reproduction and Development (1999) 36, 41-49.
  • Hiroki Nishida, Junji Morokuma, and Takahito Nishikata
  • Maternal cytoplasmic factors for generation of unique cleavage patterns in animal embryos.
  • Current Topics in Developmental Biology (1999) 46, 1-37.
  • Takahito Nishikata, Taku Hibino and Hiroki Nishida
  • The centrosome-attracting body, microtubule system, and posterior egg cytoplasm are involved in positioning of cleavage planes in the ascidian embryos.
  • Developmental Biology (1999) 209, 72-85.
  • Atsuko Yamada and Hiroki Nishida
  • Distinct parameters are involved in controlling the round of cell division in each tissue during ascidian embryogenesis.
  • Journal of Experimental Zoology (1999) 284, 379-391.
  • Yuki Nakatani and Hiroki Nishida
  • Duration of competence and inducing capacity of blastomeres in notochord induction during ascidian embryogenesis.
  • Development Growth and Differentiation (1999) 41, 449-453.
  • Tohru Iseto and Hiroki Nishida
  • Ultrastructual studies on the centrosome-attracting body: Specific electron-dense matrix and implications of it's role in unequal cleavage.
  • Development Growth and Differentiation (1999) 41, 601-609.
  • Gil Jung Kim and Hiroki Nishida
  • Suppression of muscle fate by cellular interaction is required for mesenchyme formation during ascidian embryogenesis.
  • Developmental Biology (1999) 214, 9-22.
  • Toshio Hirano and Hiroki Nishida
  • Developmental fates of larval tissues after metamorphosis in the ascidian, Halocynthia roretzi. II. Origin of endodermal tissues of the juvenile.
  • Development, Genes and Evolution (2000) 210, 55-63.
  • Takeshi Kawashima, Shuichi Kawashima, Minoru Kanehisa, Hiroki Nishida, and Kazuhiro W. Makabe
  • MAGEST: Maboya gene expression patterns and expression sequence tags.
  • Nucleic Acid Research (2000) 28, 133-135.
  • Gil Jung Kim, Atsuko Yamada and Hiroki Nishida
  • An FGF signal from endoderm and localized factors in the posterior-vegetal egg cytoplasm pattern the mesodermal tisuues in the ascidian embryo.
  • Development (2000) 127, 2853-2862.

真壁 和裕 Kazuhiro W. Makabe

研究課題

  • 組織特異的に発現する遺伝子の発現制御機構、及び卵内に局在するmRNAの同定
  • Gene regulation mechanisms of tissue-specific genes, and identification of mRNAs localized in an egg.

研究目的

動物の発生において卵の細胞質に局在する母性の卵内遺伝情報が後の発生過程の様々な局面で大きな役割を果たすことが知られている．卵のcDNAライブラリーを網羅的に解析することによって，ホヤ胚の発生運命の決定機構を明らかにする．

The development of an organism requires a series of complex processes initiated by maternal genetic information confined to a particular region of the egg. To obtain molecular probes with which the mechanisms underlying the processes can be revealed, we have started a mass screening of cDNAs in the ascidian egg for prelocalized messages.

最近の業績

  • Yagi, K. and K. W. Makabe (2001).
  • Isolation of an early neural maker gene abundantly expressed in the nervous system of the ascidian, Halocynthia roretzi.
  • Dev. Genes Evol. (in press)
  • Makabe, K. W., T. Kawashima, S. Kawashima, Y. Sasakura, H. Ishikawa, H. Kawamura, M. Kanehisa, T. Nishikata and H. Nishida (2001).
  • Maternal genetic information stored in fertilized eggs of the ascidian, Halocynthia roretzi. in "Biology of Ascidian"
  • Springer-Verlag (in press)
  • Sasakura, Y. and K. W. Makabe (2001).
  • Ascidian Wnt-7 gene is expressed exclusively in the tail neural tube of tailbud embryos.
  • Dev. Genes Evol. (in press)
  • Kamei S, I. Yajima, H. Yamamoto, A. Kobayashi, K. W. Makabe, H. Yamazaki, S. I. Hayashi and T. Kunisada (2000).
  • Characterization of a novel member of the FGFR family, HrFGFR, in Halocynthia roretzi.
  • Biochem. Biophys. Res. Commun. 275: 503-508.
  • Sasakura, Y., M. Ogasawara and K. W. Makabe (2000).
  • Two pathways of maternal RNA localization at the posterior-vegetal cytoplasm in early ascidian embryos.
  • Dev. Biol. 220: 365-378.
  • Kawashima, T., A. R. Murakami, M. Ogasawara, K. J. Tanaka, R. Isoda, Y. Sasakura, T. Nishikata, H. Okano and K. W. Makabe (2000).
  • Expression of musashi homologs of the ascidian, Halocynthia roretzi and Ciona intestinalis.
  • Dev. Genes Evol. 210: 162-165.
  • Kawashima, T., S. Kawashima, M. Kanehisa, H. Nishida and K. W. Makabe (2000).
  • MAGEST: MAboya Gene Expression patterns and Sequence Tags.
  • Nuc. Acids Res. 28: 133-135.
  • Kobayashi, A., Y. Sasakura, M. Ogasawara and K. W. Makabe (1999).
  • A maternal RNA encoding smad1/5 is segregated to the animal blastomeres during ascidian development.
  • Dev. Growth Differ. 41: 419-427.
  • Nishida, H. and K. W. Makabe (1999).
  • Maternal information in egg cytoplasm and localized maternal mRNAs in early embryos of the ascidian Halocynthia roretzi.
  • Inverte. Repro. Dev. 36: 41-49.
  • Sasakura, Y., M. Ogasawara, and K. W. Makabe (1998b).
  • Maternally localized RNA encoding a serine/threonine protein kinase in the ascidian, Halocynthia roretzi.
  • Mech. Dev. 76: 161-163.
  • Sasakura, Y., M. Ogasawara, and K. W. Makabe (1998a).
  • HrWnt-5: a maternally expressed ascidian Wnt gene with posterior localization in early embryos.
  • Int. J. Dev. Biol. 42: 573-580.
  • Hiroki Takahashi, Koichi Ishida, Kazuhiro W. Makabe and Noriyuki Satoh (1997).
  • Isolation of cDNA clones for genes that are expressed in the tail region of the ascidian tailbud embryo.
  • International Journal of Developmant Biology 41, 691-698.
  • Noriyuki Satoh, Kazuhiro W. Makabe, You Katsuyama, Shuichi Wada and Hidetoshi Saiga (1996).
  • The ascidian: An experimental system for studying genetic circuitry for embryonic cell specification and morphogenesis.
  • Development Growth and Differentiation 38, 325-340.

西方 敬人 Takahito Nishikata

研究課題

  • 卵細胞質内決定因子の分配機構
  • Segregation mechanisms of egg cytoplasmic determinants

研究目的

ホヤ卵では、特徴的な色の付いた細胞質が卵内に局在し、特定の割球へと運ばれ、特定の組織へと受け継がれることから、各組織分化の引き金を引く決定因子が局在する細胞質内に含まれていると考えられてきた。一方、最新の顕微手術の実験から、ホヤ卵内には積極的に分化を推し進める何らかの因子が存在し、それらが卵内で局在し、必要な細胞へと分配されていくことが明確に示された。また、マイオプラズミンC１などの決定因子に関わる新規の分子の解析から、決定因子は母性mRNAを含む様々な分子の複合体であり、その複合体が細胞骨格のダイナミックな動きにより運ばれていることも次第に明らかになってきた。そこで本研究では、ホヤ卵内部で決定因子がどのような仕組で局在し、分配されるかを明らかにすることで、決定因子の分子的実体をも明らかにすることを目的とする。

1）決定因子複合体の局在メカニズム：以下の3つの視点から、それぞれの分子の機能を明確にし、局在化メカニズムを分子的に明らかにするとともに、決定因子複合体の実体を明確にする。

  1. 1）-1；母性mRNAの保護と蓄積に関わるRNA結合タンパク質
  2. 1）-2；細胞骨格を構成するアクチンとチューブリン
  3. 1）-3；決定因子複合体の中核となるマイオプラズミンC１

2）決定因子の分配メカニズム：卵割パターンを支配する新規の構造体CAB (Centrosome-Attracting Body) を分子的に解析することで、決定因子分配機構を明らかにする。

In the ascidian eggs, as the characteristic colored cytoplasm was localized and segregated into a certain tissue, cytoplasmic determinants were suggested to be contained in such colored cytoplasm. Modern microsurgical techniques proved the existence, localization and segregation of the cytoplasmic determinants. Recently, the cytoplasmic determinants seemed to assemble into a molecular complex which mediated by the myoplasmin-C1. In this project, in order to reveal the molecular nature of the cytoplasmic determinants, we are analyzing the molecular mechanisms of the localization and segregation of the determinant complexes.

1) Localization mechanisms of the determinant complexes: By means of analyzing the molecular mechanisms which responsible for the localization of the following three types of molecules, the molecular nature of the determinant complex will be revealed.

  1. 1)-1: RNA-binding proteins which responsible for the masking of maternal mRNAs
  2. 1)-2: Actin and tubulin which consist of cytoskeletal filament network.
  3. 1)-3: Myoplasmin-C1 which is important for the molecular association.

2) Segregation mechanisms of the determinant complexes: Molecular analysis of the novel structure, CAB (Centrosome-Attracting Body), which is essential for the invariant cleavage pattern of the ascidian embryo will reveal the segregation mechanisms of the determinant complex.

最近の業績

  • Tanaka, J. K., Chiba, S. and Nishikata, T. (1996).
  • Two distinct cell types identified in the asidian notochord.
  • Zool. Sci. 13, 725-730.
  • Nishikata, T. and Wada, M. (1996).
  • Molecular characterization of myoplasmin-C1: a cytoskeletal component localized in the myoplasm of ascidian eggs.
  • Dev. Genes Evol. 206, 72-79.
  • Michiko R. Wada, Hiroki Nakayama and Takahito Nishikata (1997).
  • Cloning of the ascidian Y-box protein gene with a convenient and reliable amplification protocol of 3' ends of mRNAs.
  • Memoirs of Konan University, Science Series 44, 45-51.
  • Shota Chiba, Yutaka Saou, Takahito Nishikata and Noriyuki Satoh (1998).
  • Isolation and characterization of cDNA clones for epidermis-specific and muscle-specific genes in Ciona savignyi embryos.
  • Zoological Science 15, 239-246.
  • Michiko R. Wada, Yoshiaki Ohtani, Yumiko Shibata, Naomi Tanimoto, Kimio J. Tanaka and Takahito Nishikata (1998).
  • An alternatively spliced gene encoding a Y-box protein showing maternal expression and tissue-specific zygotic expression in the ascidian embryo.
  • Development Growth and Differentiation 40, 631-640.
  • Shota Chiba and Takahito Nishikata (1998).
  • Genes of the ascidian: An annotated list as of 1997.
  • Zoological Science 15, 625-643.
  • Taku Hibino, Takahito Nishikata and Hiroki Nishida (1998).
  • Centrosome-attracting body: A novel structure closely related to unequal cleavages in the ascidian embryo.
  • Development Growth and Differentiation 40, 85-95.
  • Hiroki Nishida, Junji Morokuma and Takahito Nishikata (1999).
  • Maternal cytoplasmic factors for generation of unique cleavage patterns in animal embryos.
  • Current Topics in Developmental Biology 34, 1-37.
  • Michiko R. Wada, Akikazu R. Murakami, Hiroshi Kawamura, Rinna Nakamori, Kimio J. Tanaka, Hiroki Nakayama and Takahito Nishikata (1999).
  • The expression of the protochordate homologue of the proteasome regulatory subunit Rpn12 is transcriptionally and post-translationally regulated during cleavage stage.
  • Zoological Science 16, 125-129.
  • Shota Chiba, Yuko Miki, Kazunori Ashida, Michiko R. Wada, Kimio J. Tanaka, Yumiko Shibata, Rinna Nakamori and Takahito Nishikata (1999).
  • Interactions between cytoskeletal components during ooplasmic segregation in the myoplasm of ascidian eggs.
  • Development Growth and Differentiation 41, 265-272.
  • Okubo Masa-Aki, Shota Chiba, Takahito Nishikata, Akira Matsuno and Hiroshi Hosoya (1999).
  • Generation and characterization of a monoclonal antibody, mH1, raised against mitotic HeLa cells.
  • Development Growth and Differentiation 41, 381-389.
  • Takahito Nishikata, Taku Hibino and Hiroki Nishida (1999).
  • The CAB (Centrosome-Attracting Body), microtubule system, and posterior egg cytoplasm are involved in positioning of cleavage planes in the ascidian embryo.
  • Developmental Biology 209, 72-85.
  • Rinna Nakamori, Akikazu Murakami and Takahito Nishikata (1999).
  • Characterization of MTR1: A novel protein correlated with the myoplasmic movement during ascidian ooplasmic segregation.
  • Memoirs of Konan University, Science Series 46, 25-33.
  • Kimio J. Tanaka and Takahito Nishikata (1999).
  • A non-radioactive gel shift protocol enables recovery of RNA-binding proteins.
  • Technical Tips Online http://www.elsevier.com/locate/tto, T01794.
  • Takeshi Kawashima, Akikazu R. Murakami, Michio Ogasawara, Kimio J. Tanaka, Ryuji Isoda, Yasunori Sasakura, Takahito Nishikata, Hideyuki Okano and Kazuhiro W. Makabe (2000).
  • Expression patterns of musashi homologus of the ascidians, Halocynthia roretzi and Ciona intestinalis.
  • Development Genes and Evolution 210, 162-165.
  • Kimio J. Tanaka, Hiroshi Kawamura, Hiroshi Matsugu and Takahito Nishikata (2000).
  • An ascidian glycine-rich RNA-binding protein is not induced by temperature-stress but is expressed under a genetic program during embryogenesis.
  • Gene 243, 207-214.
  • Hiroshi Matsugu and Takahito Nishikata (2000).
  • Improved antigen detection on Western-blots.
  • Technical Tips Online http://www.elsevier.com/locate/tto, T02043.
  • Kimio J. Tanaka, Hiroshi Kawamura and Takahito Nishikata (2000).
  • The transcript coding for an RNA-binding protein is localized in the anterior side of the ascidian 2-cell stage embryo.
  • Development Genes and Evolution in press.

西駕 秀俊 Hidetoshi Saiga

研究課題

  • ホヤ胚発生におけるホメオボックス遺伝子の発現と機能の解析
  • Analysis of expression and function of homeobox genes in the ascidian embryogenesis

研究目的

ホヤ胚発生におけるホメオボックス遺伝子の発現の解析を手がかりとして、それらの発生運命決定における役割、軸形成における機能の解析を行い、発生運命決定機構、軸形成機構の分子的基盤を明らかにする。

The aim of this research is to obtain insights into the molecular mechanisms of determination of cell fate and the axis formation by analyzing expression patterns of homeobox genes and elucidating their functions in the ascidian embryogenesis.

最近の業績

  • Katsuyama, Y., Wada, S., and Saiga, H. (1996)
  • Homeobox genes exhibit evolutionary conserved regionalization in the central nervous system of an ascidian larva.
  • Zool. Sci. 13, 479-482
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