Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
???displayArticle.abstract???
In order to understand the role of the protein of Xenopus vasa homolog (Xenopus vasa-like gene 1, XVLG1) in germ line cells, an attempt was made to perturb the function of the protein with the anti-vasa antibody 2L-13. The 2L-13 or the control antibody was microinjected with a lineage tracer (FITC-dextran-lysine, FDL) into single vegetal blastomeres containing the germ plasm of Xenopus 32-cell embryos, the descendants of which were destined to differentiate into a small number of primordial germ cells (PGC) and a large number of somatic cells, mostly of endodermal tissues at the tadpole stage. No significant effect of the injection of the antibodies on FDL-labeled, presumptive PGC (pPGC) was observed in embryos until stage 37/38. However, FDL-labeled PGC were not observed in almost all the 2L-13 antibody-injected tadpoles, although a similar number of labeled somatic cells were always present. As 2L-13 antibody specifically reacts with XVLG1 protein in the embryos by immunoblotting, the present results suggest that the antibody perturbed the function of XVLG1 protein in the pPGC, resulting in failure of PGC differentiation at the tadpole stage.
Fig. 1. A schematic representation of a perturbation experiment
with an antibody. 2L-13 antibody specific to XVLGI protein, or
the control, antibody or modified Steinberg's saline was microinjected
with FITC-dextran-lysine (FOL) into single vegetal blastomeres
with a 'dark area' (lkenishi & Nakazato 1986) or those
containing the germ plasm of 32-cell embryos. FDL-Iabeled,
pPGC and PGC derived from the blastomeres were examined in
experimental embryos and tadpoles. See text for details.
Fig. 2. A transverse, paraplast section of a stage-45 tadpole developed from a 32-cell embryo with an injection of FDL. About 2 nL
of FDL (at a concentration of 100 mg/ml in Steinberg's saline) was injected into the vegetal blastomere containing the germ plasm of
the embryo. (A) A fluorescent micrograph showing that FDL-Iabeled cells are mainly observed in the endodermal tissues such as
intestine (i), stomach (st) and lung (I) of the tadpole. The labeled PGC (arrowheads) are also recognized in the genital ridges. Top is
dorsal and bottom, ventral. e, epidermis. Bar, 100 ~m. (B) A phase-contrast micrograph of a higher magnification of the genital ridge
region in A. Four PGC (arrowheads) are situated in the genital ridges. dm, dorsal mesentery; m, mesonephrogenic blastema; w, Wolffian
duct. Bar, 20 ~m. (C) A fluorescent micrograph of B with FITC. Two of the four PGC (arrowheads), and some cells in the lung and the
mesonephrogenic blastema are labeled with FDL. The other two, unlabeled PGC are thought to be originated from uninjected blastomeres
containing the germ plasm. Bar, 20 ~m.
Fig. 3. A transverse. polyester
wax section of a 2L-13 tadpole at
stage 45. Top is dorsal and
bottom, ventral. Bar 100 ~m. (A) A
fluorescent micrograph with FITC.
FDL-Iabeled cells derived from
the injected blastomere are seen
in the midgut (m). h, hindgut.
(B) A fluorescent micrograph
with Cy3. FDL-Iabeled cells in A
are certainly stained with Cy3-
conjugated anti-mouse lgG, recognizing
the injected antibody.
This means that the descendant,
somatic cells from the injected
blastomere have differentiated into
intestinal cells, without suffering
from any influence by the injected
antibody. e, epidermis; s, somite;
w, Wolffian duct.
Fig. 4. lmmunoblotting to Xenopus embryonic proteins with
2L-13 (lane 1) and the commercially purchased, control antibodies
(lanes 2-5). Proteins from one quarter of an embryo were
loaded onto each lane. 2L-13 antibody specifically reacts with
ca 80 kDa band (lane 1, arrowhead) or XVLG1 protein, while the
control antibody does not at all. Lanes 1 and 2, stage 6; lane 3,
stage 12; lane 4, stage 28; lane 5, stage 37/38.
Fig. 5. A frontal, paraplast section just below the archenteron floor of a 2L-13 antibody-injected embryo at stage 18. Only a somewhat
centro-lateral part of the endodermal cell mass is shown. Top is anterior and bottom, posterior. Bar, 50 !Jm. (A) A phase-contrast
micrograph. Three cells (arrows), the pPGC, having a granular cytoplasm or the germ plasm adjacent to the nucleus (n), are seen in
the endodermal cell mass, forming a cluster. In this photo, the nucleus is seen only in two of the three pPGC but the nucleus of the
rest was in the vicinity of the granular cytoplasm in the adjacent sections. (B) A fluorescent micrograph with FITC. The nucleus and
granular cytoplasm of the pPGC in A (arrows) are heavily stained with FDL. The somatic cells next to the pPGC on the right side are
also stained.
