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Fig. 7. Svp regulates the pros enhancer. (A) Alignment of
the consensus Su(H)-binding sequence with the S1 site in the
E(spl)m4 gene and the ten putative-binding motifs
found in the core-enhancer. Mismatched residues are colored in red. Two of
these motifs (pros7 and pros10) are also present within the mini-enhancer.
(Right) A mobility-shift gel showing the complex that contains Su(H) protein
and labeled E(spl)m4S1 DNA (m4S1). Each
reaction contained a 100x molar excess of an unlabeled competitor DNA as
indicated, except for the reaction loaded into the leftmost lane, which did
not contain competitor. (B-C'') Transgenic
mini-enhancer-β-gal reporter expression (green) in eye discs
counterstained for Pros protein (purple). (B-B'') β-gal expression
induced by the wild-type mini-enhancer is weakly variegated. (C-C'')
β-gal expression induced by the mutated pros7 mini-enhancer is not
variegated but is still restricted to R7 and cone cells. (D-D'')
Transgenic core-enhancer-β-gal reporter (green) which has 10 mutated
Su(H)-binding sites in a sev-Nact/+ mutant eye disc.
sev-Nact induces ectopic β-gal expression in R1/R6
cells. Endogenous Pros protein (purple) is also induced ectopically in these
cells. (E) Sequence alignment of a Svp-binding site in the
pros mini-enhancer from D. melanogaster and D.
simulans. Response elements correspond to two half-sites (consensus
AGGTCA) spaced one bp apart as a direct repeat
(Zelhof et al., 1995). The
position of the three tandem half-sites in the enhancer is shown with a bar
over each half-site. (F,G) Transgenic mini-enhancer-β-gal
reporter expression (green) in eye discs counterstained for Pros protein
(purple). (F) A wild-type eye disc. (G) An eye disc carrying four copies of
the sev-Svp2 transgene. Although some cells are positive for both
markers, other cells are positive for one marker but not the other.
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