Development Genes and Evolution

, Volume 210, Issue 2, pp 64–72

Characterization of an ascidian DEAD-box gene, Ci-DEAD1: specific expression in the germ cells and its mRNA localization in the posterior-most blastomeres in early embryos

  • M. Fujimura
  • K. Takamura
Original Article

DOI: 10.1007/s004270050012

Cite this article as:
Fujimura, M. & Takamura, K. Dev Gene Evol (2000) 210: 64. doi:10.1007/s004270050012


We isolated DEAD-box genes from three ascidian species (Ciona intestinalis, Ciona savignyi, and Halocynthia roretzi) by polymerase chain reaction methods. We obtained two types from each of C. intestinalis and C. savignyi, and four types from H. roretzi. The first type (DEAD1) belonged to the vasa subfamily, the second type (DEAD2) to the PL10 subfamily, the third type (DEAD3) to the p68 subfamily, and the forth type (DEAD4) did not belong to any of the subfamilies. We further analyzed in detail the expression pattern of C. intestinalis vasa-type gene (Ci-DEAD1) by in situ hybridization. In sections of the ovary and testis, the Ci-DEAD1-specific probe reacted intensely to small germ cells, oogonium, and/or oocyte and spermatogonium and/or spermatocyte, respectively. In whole-mount specimens of juveniles this probe specifically reacted to the primordial germ cells in the gonad rudiment. These gonad-specific expressions were confirmed by reverse transcriptase polymerase chain reaction of RNA from various tissues. The transcript was present in unfertilized eggs and in the central cytoplasm of blastomeres until the two-cell stage. During the second cleavage a part of the transcripts moved to the posterior region of embryos and, during early embryogenesis, was localized in the posterior-most blastomeres. In the tailbud, one or two hybridization signals were detected in the caudal endodermal strand. Based on these observations, we propose precursors of primordial germ cells in ascidians.

Key words Ascidian DEAD-box gene vasa homologue Germ cell lineage Germ cell determination 

Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • M. Fujimura
    • 1
  • K. Takamura
    • 2
  1. 1.Department of Biotechnology, Faculty of Engineering, Fukuyama University, Fukuyama 729-0292, JapanJP
  2. 2.Department of Marine Biotechnology, Faculty of Engineering, Fukuyama University, Fukuyama 729-0292, Japan E-mail: Tel.: +81-849-36-2111, Fax: +81-849-36-2459JP

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