XB-IMG-158942
Xenbase Image ID: 158942
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Figure 10. Activin, but Not Noggin, Induces
the Expression of Xenopus Follistatin
(A) Animal cap exolants were isolated from
btastulae (stage 8) and incubated in the presence
or absence of activin. When sibling controls
reached the gastrula stage (stage 10.5)
total RNA was assayed by RT-PCR for XFS-
expression. Explants incubated in the
presence of activin induce the expression of
follistatin. The embryo lane contains RNA from
sibling controls (stage 10.5). The control lane
contains all the ingredients of the embryo lane
except for RT. The EF-1 o signal demonstrates
that a comparable amount of RNA was assayed
in each lane.
(6) Left panel, 2-41 stage embryos were injected
in the animal pole of both blastomeres
with 1 ng of noggin RNAor control globin RNA.
The explants were cut, harvested, cultured,
and scored for XFS-319 RNA under the same
conditions described for (A). Noggin does not
induce the expression of follistatin RNA. Noggin
in these experiments is active, since it was
able directly to neuralize animal cap explants
from the same experiment harvested at tailbud
stage.
(C) Activin induces the expression of follistatin
in the context of the whole embryo. Embryos
were injected at the &to 16-cell stage in a single
vegetal blastomere with 2 pg of either Xenopus
activin Bb or globin control RNA. Embryos
were allowed to develop until early neurula
stage (stage 21) and ware then assayed by
whole-mount in situ hybridization for the expression
of follistatin. While the control injected
embryo at the right demonstrates a single primary
axis (I), the embryo on the left injected
with activin contains an ectopic axis (II) that
stains positively for follistatin transcript. The in
situ probe used in this study and the sense
control probe (not shown) are the same as
those in Figure 3. Image published in: Hemmati-Brivanlou A et al. (1994) Copyright © 1994. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View |