Localization of mitochondrial large ribosomal RNA in germ plasm of Xenopus embryos

Curr Biol. 1998 Oct 8;8(20):1117-20. doi: 10.1016/s0960-9822(98)70466-x.


In Xenopus, factors with the ability to establish the germ line are localized in the vegetal pole cytoplasm, or germ plasm, of the early embryo [1-3]. The germ plasm of Xenopus, and of many other animal species including Drosophila, contains electron-dense germinal granules which may be essential for germ-line formation [4-5]. Several components of the germinal granules have so far been identified in Drosophila [6-10]. One of these is mitochondrial large ribosomal RNA (mtlrRNA), which is present in the germinal granules (polar granules) during the cleavage stage until the formation of the germ-line progenitors or pole cells [8-9]. MtlrRNA has been identified as a factor that induces pole cells in embryos that have been sterilized by ultraviolet radiation [11]. The reduction of mtlrRNA in germ plasm by injecting anti-mtlrRNA ribozymes into embryos leads to the inability of these embryos to form pole cells [12]. These observations clearly show that mtlrRNA is essential for pole cell formation in Drosophila. Here, we report that mtlrRNA is enriched in germ plasm of Xenopus embryos from the four-cell stage to the blastula. Furthermore, our electron microscopic studies show that this mtlrRNA is present in the germinal granules during these stages. Thus, mtlrRNA is a common component of germinal granules in Drosophila and Xenopus, suggesting that the mtlrRNA has a role in germ-line development across phylogenetic boundaries.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Polarity
  • Cytoplasm / metabolism
  • Germ Cells
  • Mitochondria / genetics*
  • RNA / metabolism*
  • RNA, Mitochondrial
  • RNA, Ribosomal / metabolism*
  • Xenopus laevis


  • RNA, Mitochondrial
  • RNA, Ribosomal
  • RNA