title: Ectopic formation of primordial germ cells by transplantation of the germ plasm: direct evidence for germ cell determinant in Xenopus.
abstract: In many animals, the germ line is specified by a distinct cytoplasmic structure called germ plasm (GP). GP is necessary for primordial germ cell (PGC) formation in anuran amphibians including Xenopus. However, it is unclear whether GP is a direct germ cell determinant in vertebrates. Here we demonstrate that GP acts autonomously for germ cell formation in Xenopus. EGFP-labeled GP from the vegetal pole was transplanted into animal hemisphere of recipient embryos. Cells carrying transplanted GP (T-GP) at the ectopic position showed characteristics similar to the endogenous normal PGCs in subcellular distribution of GP and presence of germ plasm specific molecules. However, T-GP-carrying-cells in the ectopic tissue did not migrate towards the genital ridge. T-GP-carrying cells from gastrula or tailbud embryos were transferred into the endoderm of wild-type hosts. From there, they migrated into the developing gonad. To clarify whether ectopic T-GP-carrying cells can produce functional germ cells, they were identified by changing the recipients, from the wild-type Xenopus to transgenic Xenopus expressing DsRed2. After transferring T-GP carrying cells labeled genetically with DsRed2 into wild-type hosts, we could find chimeric gonads in mature hosts. Furthermore, the spermatozoa and eggs derived from T-GP-carrying cells were fertile. Thus, we have demonstrated that Xenopus germ plasm is sufficient for germ cell determination.
authors.affiliation: Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori, Akou-gun, Hyogo 678-1297, Japan.
authors.forename: Haru
authors.initials: H
authors.lastname: Tada
authors.forename: Makoto
authors.initials: M
authors.lastname: Mochii
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Orii
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002465:Cell Movement / Q000502:physiology; D002828:Choristoma / Q000196:embryology*; D022083:Cytoplasmic Structures / Q000235:genetics / Q000502:physiology / Q000637:transplantation*; D017931:DNA Primers / Q000235:genetics; D005260:Female; D005854:Germ Cells / Q000166:cytology*; D049452:Green Fluorescent Proteins; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D016133:Polymerase Chain Reaction; D014981:Xenopus / Q000196:embryology*
chemical_list: D017931:DNA Primers; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins