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FIG. 4. Activated MAPK expression is affected in the posterior mesoderm of XFD-injected embryos, but not in the posterior neural tissue.
(Aâ D) Dorsal is up. A and B show activated MAPK around the blastopore in stage 11.5/12 uninjected embryos in whole mount and section,
respectively. The arrowhead in A points to the approximate region pictured in B. The arrow in B points to activated MAPK present in
posterior neural (pn) tissue. C and D show expression of activated MAPK in XFD-expressing stage 11.5/12 embryos in whole mount and
section, respectively. The arrowhead in C shows the approximate region of section in D. The arrows in D indicate the approximate position
of the pn and the absence of activated MAPK. (Eâ L) Anterior is to the right and dorsal is up unless otherwise noted. E shows the normal
expression of activated MAPK in a stage 15/16 embryo from a dorsal view. The arrowheads denote the anteriorâ posterior extent of the
expression of activated MAPK. F shows a sagittal section of a stage 15/16 embryo stained for activated MAPK. Note the presence of
activated MAPK in the posterior mesoderm (m) and neural (n) tissues. G shows a dorsal view of a stage 15/16 embryo expressing XFD. The
arrowhead denotes the presence of activated MAPK in a â tail-likeâ protrusion. The arrow shows the absence of activated MAPK in the
posterior which does not form a tail. H shows a sagittal section of the posterior of a stage 15/16 embryo expressing XFD and b-gal, displaying
the expression of activated MAPK in a tail-like protrusion. Note the expression of activated MAPK in the mesoderm is decreased or absent
while the levels of activated MAPK in neural tissue is less affected. Mosaic expression of b-gal was also observed in both the mesoderm and
the neural tissue. Colocalization of activated MAPK and b-gal is magnified in the inset (arrowhead). n is less affected. I shows a dorsal view
of the normal in situ hybridization pattern for Xbra in an uncleared stage 15/16 embryo. The arrowheads denote the anteriorâ posterior
extent of Xbra staining (not including the notochord which is not shown). J shows a sagittal section of Xbra expression in the posterior
blastopore region (arrows). K shows a dorsal view of Xbra expression in a stage 15/16 embryo expressing XFD. The arrowhead shows the
expression of Xbra in a tail-like protrusion, while the arrow denotes the lack of Xbra expression in the posterior of the embryo not forming
a tail. L shows a sagittal section of a tail-like protrusion expressing Xbra in the posterior mesoderm (arrow). Scale bar, 150 mm. |
