Identification of asymmetrically localized transcripts along the animal–vegetal axis of the Xenopus egg

Authors

  • Kensuke Kataoka,

    Corresponding author
    1. Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Akou 678-1297, Japan and
      *Authors to whom all correspondence should be addressed.
      Email: rl04y005@stkt.u-hyogo.ac.jp
      Email: mmochii@sci.u-hyogo.ac.jp
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  • Akira Tazaki,

    1. Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Akou 678-1297, Japan and
    2. Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
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  • Atsushi Kitayama,

    1. Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
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  • Naoto Ueno,

    1. Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
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  • Kenji Watanabe,

    1. Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Akou 678-1297, Japan and
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  • Makoto Mochii

    Corresponding author
    1. Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Akou 678-1297, Japan and
      *Authors to whom all correspondence should be addressed.
      Email: rl04y005@stkt.u-hyogo.ac.jp
      Email: mmochii@sci.u-hyogo.ac.jp
    Search for more papers by this author

*Authors to whom all correspondence should be addressed.
Email: rl04y005@stkt.u-hyogo.ac.jp
Email: mmochii@sci.u-hyogo.ac.jp

Abstract

In many organisms, proper embryo development depends on the asymmetrical distribution of mRNA in the cytoplasm of the egg. Here we report comprehensive screening of RNA localized in the animal or vegetal hemisphere of the Xenopus egg. Macroarrays including over 40 000 independent embryonic cDNA clones, representing at least 17 000 unigenes, were differentially hybridized with labeled probes synthesized from the mRNA of animal or vegetal blastomeres. After two rounds of screening, we identified 33 clones of transcripts that may be preferentially distributed in the vegetal region of the early stage embryo, but transcripts localized in the animal region were not found. To assess the array results, we performed northern blot and quantitative real-time reverse transcription–polymerase chain reaction analysis. As a result, 21 transcripts of the 33 were confirmed to be localized in the vegetal region of the early stage embryo. Whole-mount in situ hybridization analysis revealed that 11 transcripts, including 7 previously reported genes, were localized in the vegetal hemisphere of the egg. These 11 transcripts were categorized into three groups according to their expression patterns in the egg. The first group, which contained four transcripts, showed uniform expression in the vegetal hemisphere, similar to VegT. The second group, which contained three transcripts, showed gradual expression from the vegetal pole to the equator, similar to Vg1. The last group, which contained three transcripts, was expressed at the germ plasm, similar to Xdazl. One transcript, Xwnt11, showed both the second and the third expression patterns.

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