Fig. 5. Expression of neural markers in embryos treated with MEK inhibitor from the
eight-cell stage onwards. Arrows indicate gene expression in palps.
(A,A') Ci-HB9/Mnx. Late gastrula stage embryo; dorsal view,
anterior upwards. Expression is lost in PD184352-treated embryos (+PD) in
neural plate cells (n=174). (B-K) Control embryo; lateral view,
dorsal upwards. (B'-K') PD184352-treated embryos. (B,B')
Cihox5 (+PD, 0% expression, n=116). (C,C')
Cilv38e16 (+PD, 0% expression, n=139). (D,D')
Citb8a22 (+PD, 0% expression, n=36). (E,E')
Ci-islet (+PD, 0% expression, n=20). Arrowhead indicates the
visceral ganglion expression. (F,F') Ci-otx (+PD, 100%
expression, n=80). (G,G') Ci-ETR-1 (+PD, 100%
expression, n=108). Expression in tail epidermal sensory neurones was
not affected (arrowheads). (H,H') Ci-gsx (control, 72%
expression; +PD,46% expression, n=278). (I,I') 08C09
(+PD, 91% expression, n=103). (J,J') 24H09 (+PD, 0%
expression, n=103). (K,K') Ci-TRP (+PD, 0% expression,
n=30). In all cases where gene expression was lost, this was not
simply a delay of expression, as the onset of gene expression was either much
earlier than the stage shown, or loss of expression was verified at a later
developmental stage. Similar results were obtained with U0126. (L-O) Dorsal
views of embryos showing expression of Ci-ETR-1, 08C09, 24H09 and
Ci-TRP to indicate relative expression domains along the
anteroposterior axis. A bar indicates the posterior limit of the sensory
vesicle. (P) DiI labelling of A7.4 at the 64-cell stage. At tailbud stages,
label is seen in the posterior sensory vesicle (posterior to the pigment
cells) and in the ventral tail nerve cord (not seen in this focal plane). (Q)
DiI labelling of A7.8 at the 64-cell stage. At tailbud stages, label is seen
in the visceral ganglion, lateral tail nerve cord and a few muscle cells (not
visible in picture). (R) A schematic summary of the data shown in this figure.
The central nervous system consists of a sensory vesicle, visceral ganglion
and tail nerve cord. In black are the pigment cells. A-line cells are coloured
grey. The relative expression domains along the anteroposterior axis of genes
used in this figure is indicated. + and - indicate the expression status of
the genes in PD184352-treated embryos.