Time-lapse analysis reveals different modes of primordial germ cell migration in the medaka Oryzias latipes

Authors

  • Hiromi Kurokawa,

    1. Laboratory of Molecular Genetics for Reproduction, National Institute for Basic Biology, Okazaki 444-8787,
    2. Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810,
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  • Yumiko Aoki,

    1. Laboratory of Molecular Genetics for Reproduction, National Institute for Basic Biology, Okazaki 444-8787,
    2. Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810,
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  • Shuhei Nakamura,

    1. Laboratory of Molecular Genetics for Reproduction, National Institute for Basic Biology, Okazaki 444-8787,
    2. Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810,
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  • Youko Ebe,

    1. Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810,
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  • Daisuke Kobayashi,

    1. Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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  • Minoru Tanaka

    Corresponding author
    1. Laboratory of Molecular Genetics for Reproduction, National Institute for Basic Biology, Okazaki 444-8787,
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*Author to whom all correspondence should be addressed. Email: mtanaka@nibb.ac.jp

Abstract

Previous studies have shown that medaka primordial germ cells (PGC) are first distinguishable by olvas expression during late gastrulation, and that they migrate to the gonadal region through the lateral plate mesoderm. Here, we demonstrate that medaka nanos expression marks the germ line at early gastrulation stage. By marking the germ line with green fluorescent protein (GFP) fused to the nanos 3′ untranslated region, we were able to visualize the behavior of PGC using time-lapse imaging. We show that there are three distinct modes of PGC migration that function at different stages of development. At early gastrulation stage, PGC actively migrate towards the marginal zone, a process that requires the function of a chemokine receptor, CXCR4. However, at late gastrulation stage, PGC change the mode and direction of their movement, as they are carried towards the midline along with somatic cells undergoing convergent movements. After aligning bilaterally, PGC actively migrate to the posterior end of the lateral plate mesoderm. This posterior movement depends on the activity of both HMGCoAR and a ligand of CXCR4, SDF-1a. These results demonstrate that PGC undergo different modes of migration to reach the prospective gonadal region of the embryo.

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