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macho-1 encodes a localized mRNA in ascidian eggs that specifies muscle fate during embryogenesis


Maternal information stored in particular regions of the egg cytoplasm has an important function in the determination of developmental fate during early animal development1,2. Ascidians show mosaic development3,4; such autonomous development has been taken as evidence that prelocalized ooplasmic factors specify tissue precursor cells during embryogenesis. Interest has been concentrated on the mechanisms underlying the formation of muscle cells in the tail, as yellow-coloured myoplasm in eggs is preferentially segregated into muscle-lineage blastomeres5. Here we show that maternal messenger RNA of the macho-1 gene is a determinant of muscle fate in the ascidian Halocynthia roretzi. The macho-1 mRNA encodes a zinc-finger protein, and the mRNA is localized to the myoplasm of eggs. Depletion of the mRNA specifically resulted in the loss of primary muscle cells in the tail, as shown by the expression of muscle-specific molecular markers. The myoplasm of macho-1-deficient eggs lost its ability to promote muscle formation. Injection of synthesized macho-1 mRNA caused ectopic muscle formation in non-muscle-lineage cells. Our results indicate that macho-1 may be both required and sufficient for specification of muscle fate, and that the mRNA is a genuine, localized muscle determinant.

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Figure 1: Structure and localization of macho-1 transcript. a, Alignment of zinc-finger domain of predicted amino-acid sequence of macho-1, mouse Zic4 , Zic3, Zic2, Zic1, Drosophila odd-paired (opa), cubitus interruptus (ciD) and chick Gli3 (accession numbers Q61467, Q62521, Q62520, P46684, P39768, P19538 and P55879, respectively).
Figure 2: Depletion of maternal mRNA by antisense oligonucleotide.
Figure 3: Depletion of macho-1 mRNA results in loss of primary muscle cells, and its overexpression causes ectopic muscle formation.
Figure 5: Overexpression of macho-1 mRNA results in ectopic formation of muscle cells.
Figure 4: Effect on muscle and endoderm formation after injection of various oligodeoxynucleotides and synthesized mRNA.


  1. Wilson, E. B. The Cell in Development and Heredity 3rd edn (Macmillan, New York, 1925).

    Google Scholar 

  2. Davidson, E. H. Gene Activity in Early Development 3rd edn (Academic, New York, 1986).

    Google Scholar 

  3. Reverberi, G. & Minganti, A. Fenomeni di evocazione nello sviluppo dell’uovo di ascidie: Risultati dell’indagine sperimentale sull’uovo di Ascidiella aspersa e di Ascidia malaca allo stadio di otto blastomeri. Pubbl. Staz. Zool. Napoli 20, 199–252 (1946).

    Google Scholar 

  4. Nishida, H. Developmental potential for tissue differentiation of fully dissociated cells of the ascidian embryo. Roux's Arch. Dev. Biol. 201, 81–87 (1992).

    Article  Google Scholar 

  5. Conklin, E. G. The organization and cell lineage of the ascidian egg. J. Acad. Nat. Sci. 13, 1–119 (1905).

    Google Scholar 

  6. Satoh, N. Developmental Biology of Ascidians (Cambridge Univ. Press, Cambridge, 1994).

    Google Scholar 

  7. Nishida, H. Regionality of egg cytoplasm that promotes muscle differentiation in embryo of the ascidian, Halocynthia roretzi. Development 116, 521–529 (1992).

    Google Scholar 

  8. Aruga, J. et al. The mouse Zic Gene family. J. Biol. Chem. 271, 1043–1047 (1996).

    CAS  Article  Google Scholar 

  9. Whittaker, J. R. Segregation during ascidian embryogenesis of egg cytoplasmic information for tissue-specific enzyme development. Proc. Natl Acad. Sci. USA 70, 2096–2100 (1973).

    ADS  CAS  Article  Google Scholar 

  10. Satou, Y., Kusakabe, T., Araki, I. & Satoh, N. Timing of initiation of muscle-specific gene expression in the ascidian embryo precedes that of developmental fate restriction in lineage cells. Dev. Growth Differ. 37, 319–327 (1995).

    Article  Google Scholar 

  11. Nishikata, T., Mita-Miyazawa, I., Deno, T. & Satoh, N. Muscle cell differentiation in ascidian embryos analyzed with a tissue-specific monoclonal antibody. Development 99, 163–171 (1987).

    CAS  PubMed  Google Scholar 

  12. Whittaker, J. R. Determination of alkaline phosphatase expression in endodermal cell lineages of an ascidian embryo. Biol. Bull. 178, 222–230 (1990).

    CAS  Article  Google Scholar 

  13. Nishida, H. Cell lineage analysis in ascidian embryos by intracellular injection of a tracer enzyme. III. Up to the tissue restricted stage. Dev. Biol. 121, 526–541 (1987).

    CAS  Article  Google Scholar 

  14. Nishida, H. Determinative mechanisms in secondary muscle lineages of ascidian embryos: development of muscle-specific features in isolated muscle progenitor cells. Development 108, 559–568 (1990).

    CAS  PubMed  Google Scholar 

  15. Erives, A., Corbo, J. & Levine, M. Lineage-specific regulation of the Ciona snail gene in the embryonic mesoderm and neuroectoderm. Dev. Biol. 194, 213–225 (1998).

    CAS  Article  Google Scholar 

  16. Wada, S. & Saiga, H. Cloning and embryonic expression of Hrsna, a snail family gene of the ascidian Halocynthia roretzi: implication in the origin of mechanisms for mesoderm specification and body axis formation in chordates. Dev. Growth Differ. 41, 9–18 (1998).

    Article  Google Scholar 

  17. Satoh, N., Araki, I. & Satou, Y. An intrinsic genetic program for autonomous differentiation of muscle cells in the ascidian embryo. Proc. Natl Acad. Sci. USA 93, 9315–9321 (1996).

    ADS  CAS  Article  Google Scholar 

  18. Mitani, Y., Takahashi, H. & Satoh, N. An ascidian T-box gene As-T2 is related to the Tbx6 subfamily and is associated with embryonic muscle cell differentiation. Dev. Dynam. 215, 62–68 (1999).

    CAS  Article  Google Scholar 

  19. Marikawa, Y. & Elinson, R. P. Relationship of vegetal cortical dorsal factors in the Xenopus egg with the Wnt/beta-catenin signaling pathway. Mech. Dev. 89, 93–102 (1999).

    CAS  Article  Google Scholar 

  20. Yoshida, S., Marikawa, Y. & Satoh, N. posterior end mark, a novel maternal gene encoding a localized factor in the ascidian embryo. Development 122, 2005–2012 (1996).

    CAS  PubMed  Google Scholar 

  21. Satou, Y. & Satoh, N. posterior end mark 2 (pem-2), pem-4, pem-5, and pem-6: maternal genes with localized mRNA in the ascidian embryo. Dev. Biol. 192, 467–481 (1997).

    CAS  Article  Google Scholar 

  22. Nishida, H. & Makabe, K. W. Maternal information and localized maternal mRNAs in eggs and early embryos of the ascidian Halocynthia roretzi. Invert. Reprod. Dev. 36, 41–49 (1999).

    CAS  Article  Google Scholar 

  23. Sasakura, Y., Ogasawara, M. & Makabe, K. W. Two pathways of maternal RNA localization at the posterior-vegetal cytoplasm in early ascidian embryos. Dev. Biol. 220, 365–378 (2000).

    CAS  Article  Google Scholar 

  24. Kawashima, T., Kawashima, S., Kanehisa, M., Nishida, H. & Makabe, K. W. MAGEST: MAboya Gene Expression patterns and Sequence Tags. Nucleic Acids Res. 28, 133–135 (2000).

    CAS  Article  Google Scholar 

  25. Nishikata, T., Hibino, T. & Nishida, H. The centrosome-attracting body, microtubule system, and posterior egg cytoplasm are involved in positioning of cleavage planes in the ascidian embryo. Dev. Biol. 209, 72–85.

  26. Kaneko-Ishino, T. et al. Peg1/Mest imprinted gene on chromosome 6 identified by cDNA subtraction hybridization. Nature Genet. 11, 52–59 (1995).

    CAS  Article  Google Scholar 

  27. Heasman, J. et al. Overexpression of cadherins and underexpression of β-catenin inhibit dorsal mesoderm induction in early Xenopus embryos. Cell 79, 791–803 (1994).

    CAS  Article  Google Scholar 

  28. Mita-Miyazawa, I., Ikegami, S. & Satoh, N. Histospecific acetylcholinesterase development in the presumptive muscle cells isolated from 16-cell-stage ascidian embryos with respect to number of DNA replications. J. Embryol. Exp. Morphol. 87, 1–12 (1985).

    CAS  PubMed  Google Scholar 

  29. Hoshi, M., Numakunai, T. & Sawada, H. Evidence for participation of sperm proteinases in fertilization of the solitary ascidian, Halocynthia roretzi: effects of protease inhibitors. Dev. Biol. 86, 117–121 (1981).

    CAS  Article  Google Scholar 

  30. Nishida, H. & Satoh, N. Cell lineage analysis in ascidian embryos by intracellular injection of a tracer enzyme II. The 16- and 32-cell stages. Dev. Biol. 110, 440–454 (1985).

    CAS  Article  Google Scholar 

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We thank T. Nishikata for providing myosin antibody; N. Satoh for providing muscle actin cDNA; K. Kobayashi for help in the cytoplasmic transfer experiments; and M. L. King for critical reading of our manuscript. We also thank members of the Asamushi Marine Biological Station and the Otsuchi Marine Research Center for their help in collecting live ascidian adults, and members of the Misaki Marine Biological Laboratory for their help in maintaining these ascidians. This work was supported by the Research for the Future Program of the Japanese Society for the Promotion of Science, and a grant from the Human Frontier Science Program organization.

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Correspondence to Hiroki Nishida.

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Nishida, H., Sawada, K. macho-1 encodes a localized mRNA in ascidian eggs that specifies muscle fate during embryogenesis. Nature 409, 724–729 (2001).

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