SPATIOTEMPORAL DISTRIBUTION OF THE PROTEIN OF XENOPUS-VASA HOMOLOG (XENOPUS-VASA-LIKE GENE 1, XVLG1) IN EMBRYOS

In order to know when the protein of Xenopus vasa homolog (Xenopus vas a-like gene 1, XVLG1) first appears in germ line cells and whether the protein is also present in somatic cells as is vasa protein in Drosop hila, the spatio-temporal distribution of the protein in Xenopus embry os was carefully investigated by fluorescent microscopy. Part of the o bservation was performed by whole-mount immunocytochemistry and immuno blotting. A distinct fluorescence of XVLG1 protein was first recognize d in a juxta-nuclear location of germ line cells or presumptive primor dial germ cells (pPGC) at stage 12 (late gastrula) and remained associ ated with the pPGC or primordial germ cells (PGC) throughout the follo wing stages until stage 46 (feeding tadpole). In contrast, weak fluore scence was seen in the animal hemisphere rather than in the vegetal he misphere of cleaving embryos and in the perinuclear region of somatic cells at stages 10-42 (early gastrula to young tadpole), respectively. Nearly the same pattern as revealed by fluorescence was seen by whole -mount immunocytochemistry, except that a small amount of XVLG1 protei n seemed to be present in the germ plasm and pPGC of embryos earlier t han stage 12. The presence of the protein in the somatic cells and the PGC was also shown by immunoblotting.