|
|
|
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
|
Fig. 5. Shh ventralizing activity in the zebrafish forebrain requires the N- or
C-terminal lipid. Zebrafish embryos were injected at the two- to four-cell
stage with 75 pg of in vitro synthesized mRNA encoding different lipid
modifiable forms of Shh. Changes in expression of different Shh responsive
genes were assayed at 20 hours by in situ hybridization. (A,D,G,J)
nk2.1b (blue) and emx1 (red) double labeling, lateral views
of brain, eyes removed. (A,D,G) Expression of different N- and C-terminal
lipid-containing forms of Shh leads to variable expansion of nk2.1b
into the dorsal telencephalon and the simultaneous reduction of dorsal
emx1 expression (arrowheads show the border of nk2.1b and
emx1 expression). The effects of injections were categorized as mild,
moderate or major, based on the degree of nk2.1b expansion and
emx1 reduction (red arrowheads). (J) In uninjected embryos,
nk2.1b is expressed in a small band in the ventral telencephalon (red
arrow), as well as in the underlying diencephalon. Emx1 expression in
the dorsal telencephalon is complementary to that of nk2.1b.
(B,E,H,K) nk2.2 expression, lateral views of brain, eyes removed.
(B,E,H) Examples of variable expansion of nk2.2 expression
(arrowheads indicate the extent of expansion of the nk2.2 expression
domain). (K) In uninjected embryos, nk2.2 is expressed in the dorsal
diencephalon and in the ventral midbrain, hindbrain and spinal cord (data not
shown). (C,F,I,L) pax6 and emx1 expression, dorsal views of
the head. (C,F,I) Examples of reduced pax6 (red arrows) and
emx1 (white arrows) expression. (L) In uninjected embryos,
pax6 is expressed in the eyes, while emx1 expression is seen
in the telencephalon between the eyes. (M) Graph showing the percentage of
embryos with differently affected gene expression patterns after expression of
different Shh N- and C-terminal lipid-containing forms. Gene expression is
shown at the top, numbers of embryos assayed in each experiment is shown in
each bar. Blue, normal gene expression; yellow, mild ventralization; green,
moderate ventralization; red, major ventralization; Shh, wild-type Sonic
Hedgehog; ShhN, Shh lacking the C-terminal lipid; C24SShh, Shh lacking the
N-terminal lipid; C24S-ShhN; Shh lacking both lipids; di, diencephalon; mb,
midbrain; tel, telencephalon.
|
