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Fig. 7. Correct timing of the ath5 wave requires Sonic hedgehog signaling
before, but not during, retinal neurogenesis. (A-D) The position of the
ath5 wave front was quantified in all embryos from the syu
and cyclopamine experiments. Each embryo was scored for the quadrant of the
retina in which the wave front was located: either ventronasal, central or
temporal. If the wave was over, and ath5 expression was confined to
the ciliary marginal zone the embryo was scored as `only CMZ'. The fraction of
embryos at a given age falling into each of these four categories was plotted.
Because we took care to ensure developmental synchrony, in most cases, the
fraction was 100%. Examples of how the ath5 expression domain looked
for each category are shown in Fig.
6A-D. (E) Summary of the results of syu and cyclopamine
experiments. The retinal position of the ath5 wave front as
calculated in A-D was plotted for groups of wild-type, syu mutant and
cyclopamine-treated embryos at different ages. Each data point indicates that
100% of the embryos in the given treatment group fell into the given
wave-position category, unless marked by a different percentage. All values
are taken from the graphs in A-D. In syu mutants (gray), the
ath5 wave was delayed relative to wild type (black), but it did
eventually traverse the entire retina. The delay at 35 hpf showed incomplete
penetrance. Starting cyclopamine treatment at 13 hpf also delayed the
ath5 wave (orange), but when cyclopamine was given at 25 hpf (green)
the rate of wave progression mirrored wild type. CMZ, ciliary marginal zone;
cycl., cyclopamine.
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