| |
Figure 3. Mutant p53 blocks differentiation. (a) Dorsal
view of an embryo injected with p53Tthr280
mRNA plus beta-galactosidase mRNA into
blastomere B1 of a 32-cell embryo, reared to
tailbud stage, and stained with the anti-neural
antibody XAN3/6F11 (dark blue/purple [48]).
Anterior is to the left. Note that the beta-
galactosidase-positive tumor (light blue) does
not stain with the neural marker, and that the
large tumor distorts the brain into which it is
embedded. (b)Transverse section through a
sample similar to that shown in (a). Neural
staining (dark purple) with antibody 2G9
(XenopusMolecular Marker Resource, URL
http://vize222.zo.utexas.edu) and beta-
galactosidase (light blue). beta-galactosidase-
positive cells do not stain with the neural
marker, and vice versa. (c) Control side of a
tailbud stage embryo stained (dark blue/purple)
with the somite differentiation marker
12/101[49]. Note that the differentiated
somites extend anteriorly to the head of the
embryo. (d)The opposite side of the embryo
shown in (c), illustrating a tumor derived from
blastomere C2 injected with p53thr280mRNA
plus beta-galactosidase mRNA. Note that the
region in which anterior somites should have
formed does not stain with 12/101, but is beta-
galactosidase positive (light blue). (e)The
control side of a tailbud stage embryo stained
with antibody 3G8 [50] to detect pronephric
tubules (dark purple substrate, arrow).(f)The
opposite side of the embryo shown in (e),
illustrating a tumor derived from the blastomere
C3 injected with p53thr280mRNA plus beta-
galactosidase mRNA. The region in which the
embryonic kidney, the pronephros, should have
formed does not stain with antibody 3G8. The
beta-galactosidase-positive tumor (light blue) is
displaced dorsally from the region in which the
pronephros normally develops, but such
displacement is common for mutant p53-
induced tumors (see Figures 1 and 5). |
