From matthewk@XXXX Thu Aug 01  15:52:29  2002
Subject: P{neoFRT}18A
To: flybase-updates@XXXX
Personal communication from: Dominic Ebacher, Panganiban Lab, University of
Wisconsin, Madison
To: Bloomington Drosophila Stock Center
Subject: P{neoFRT}18A
Dated: 31 July 2002
Information communicated:
'While conducting crosses recently, I encountered anomalous results with flies
of genotype FRT(18A); eyFLP. Subsequent test crosses revealed that in the
presence of continuous FLPase, FRT(18A) is >75% lethal and 100% of the escapers
have severe eye and head defects. Test crosses with other FRT(18A) chromosomes
and other FLPase stocks indicate that these phenotypes are due to the FRT(18A)
chromosome. I now have tested eyFLPase stocks with insertions on either the
second or third chromosome. All yield the same results with FRT(18A). None are
lethal with FRT(19A) stocks. The lethality and developmental abnormalities are
observed with both male and female flies carrying an FRT(18A) chromosome, so
the defects are not due to inter-chromosomal recombination. I therefore suspect
that the original FRT(18A) chromosome has an aberration (perhaps another FRT
site near the one at 18A) and that this has been transmitted to recombinant
chromosomes carrying FRT(18A). I further suspect that recombination between the
two FRT sites deletes essential genes, leading to cell lethality and head
defects. Consistent with my results, Seth Blair has been able to disrupt wing
disc development using flies carrying FRT(18A) and ap-GAL4, a continuous source
of FLPase in the wing. Thus FRT(18A) probably is cell lethal in the presence
of continuous FLPase. In light of this, we recommend that people use the
FRT(18A) chromosome only with transient (e.g. heat shock-inducible) FLPase,
and that they use FRT(19A) whenever feasible.'