No mutation has been detected in the P{P-Sal} element, but the mutant phenotype in this line (P\TSal-M20 shows loss of silencing of P{lacW}ciDplac compared to its P\TSal progenitor) maps to within 0.27cM from the P{P-Sal}Pak3P-Sal progenitor insertion. There may therefore be a mutation in a nearby enhancer sequence that controls Pak3 and thereby regulates the expression of the P-element repressor coding sequence via the gene-trapped P-element promoter.
P\TSal-M20 does not show P-element dependent silencing (PDS) of the w marker in the P{lacW}ciDplac insertion (in contrast to its progenitor, P\TSal), with flies carrying both P{lacW}ciDplac and P\TSal-M20 in a w[-] background having red eyes.
P\TSal-M20 does not cause P-element dependent silencing of the w marker in the P{hsp26-pt-T}ci2-M1021.R insertion.
Expression of the w marker in the P{hsp26-pt-T}39C-12 insertion line normally shows variegation, but this is partially suppressed by P\TSal-M20.
