ZFIN ID: ZDB-PUB-051012-22
Xenopus Xpat protein is a major component of germ plasm and may function in its organisation and positioning
Machado, R.J., Moore, W., Hames, R., Houliston, E., Chang, P., King, M.L., and Woodland, H.R.
Date: 2005
Source: Developmental Biology   287(2): 289-300 (Journal)
Registered Authors: Chang, Patty
Keywords: Xenopus, Oocyte, Germ plasm, Germ line, Xpat, Microtubules, Mitochondrial cloud
MeSH Terms:
  • Actin Cytoskeleton/physiology
  • Animals
  • Cell Nucleus/metabolism
  • Cytoplasm/metabolism*
  • Microtubules/physiology
  • Mitochondria/metabolism
  • Oocytes/metabolism*
  • Oogenesis/physiology
  • Protein Transport
  • RNA, Messenger/biosynthesis
  • Transcription Factors/biosynthesis
  • Transcription Factors/genetics
  • Transcription Factors/physiology*
  • Xenopus/metabolism
  • Xenopus/physiology*
  • Xenopus Proteins/biosynthesis
  • Xenopus Proteins/genetics
  • Xenopus Proteins/physiology*
PubMed: 16216237 Full text @ Dev. Biol.
In many animals, including Drosophila, C. elegans, zebrafish and Xenopus, the germ line is specified by maternal determinants localised in a distinct cytoplasmic structure called the germ plasm. This is consists of dense granules, mitochondria, and specific localised RNAs. We have characterised the expression and properties of the protein encoded by Xpat, an RNA localised to the germ plasm of Xenopus. Immunofluorescence and immunoblotting showed that this novel protein is itself a major constituent of germ plasm throughout oogenesis and early development, although it is also present in other regions of oocytes and embryos, including their nuclei. We found that an Xpat-GFP fusion protein can localise correctly in cultured oocytes, in early oocytes to the 'mitochondrial cloud', from which germ plasm originates, and in later oocytes to the vegetal cortex. The localisation process was microtubule-dependent, while cortical anchoring required microfilaments. Xpat-GFP expressed in late stage oocytes assembled into circular fields of multi-particulate structures resembling endogenous fields of germ plasm islands. Furthermore these structures could be induced to form at ectopic sites by manipulation of culture conditions. Ectopic Xpat-GFP islands were able to recruit mitochondria, a major germ plasm component. These data suggest that Xpat protein has an important role in Xenopus germ plasm formation, positioning and maintenance.