A trial for induction of supernumerary primordial germ cells in Xenopus tadpoles by injecting RNA of Xenopus vasa homologue into germline cells of 32-cell embryos

Abstract

Whether overexpression of Xenopus vasa homologue or Xenopus vasa-like gene 1 (XVLG1) in germline cells of Xenopus embryos can induce supernumerary primordial germ cells (PGC) at tadpole stage was investigated. XVLG1 RNA (0.1-2.0 ng) and β-gal RNA (0.5 ng) were injected into one of, usually, four germ plasm-bearing cells (GPBC) of 32-cell embryos, with the β-gal RNA (2.0 ng) serving as both lineage tracer and control for XVLG1 RNA. The total number of PGC, including X-gal-stained and unstained PGC of injected and uninjected GPBC origins respectively, was examined in the experimental tadpoles developed from the injected embryos. The injected RNA, XVLG1 and β-gal RNA, were translated, resulting in a large amount of corresponding proteins in presumptive PGC (pPGC) as well as in somatic cells derived from the injected GPBC. Nevertheless, the average number of total PGC per tadpole found in the experimental tadpoles from the XVLG1 RNA-injected embryos was not significantly different from that of β-gal RNA-injected ones, irrespective of the injected dose of XVLG1 RNA. This indicates that the extra XVLG1 protein in pPGC is not sufficient to increase the number of PGC in the tadpoles.