Dear Rachel,
The sevenless-GAL4 transgene I made is constructed as follows. (I
named it sevEP-GAL4 to distinguish it from the Dickson construct called
sE-GAL4). A single copy of the sevenless enhancer, defined as a 1.2 kb XhoI
fragment, was placed 5' to a 1.05 kb EcoRI/EcoRV fragment containing the
endogenous sevenless promoter. A GAL4 cDNA (XbaI/HindIII) was placed
immediately downstream. A poly A signal is provided by a 170 bp BamHI
fragment. The transformation vector used is pw8, a Pw+ vector.
UAS-lacZ experiments confirm that this driver is much more cell
type-specific than the sE-GAL4 construct. That is, it does not appear to
exhibit the enhancer-independent, leaky activity of the Hsp promoter in the
sE-GAL4 construct. Since sE-GAL4 tends to yield more robust phenotypes
than sevEP-GAL4 I think that it is usually favored unless someone has a
particular concern about the basal, sev-independent activity of the
construct.
.
Sincerely,
Adina