Controlled expression of tagged proteins in Drosophila using a new modularP-element vector system

We have developed a new modular vector system that facilitates the combinat ion of various DNA fragments as functional modules for P element-mediated t ransformation of Drosophila melanogaster. The basic vector pP{GS} contains unique sites for 17 restriction enzymes, including three 8-bp cutters, that allow one to combine various promoter elements, cDNAs and genomic DNA frag ments,as well as protein lags and selectable marker genes, for a wide spect rum of transgene analyses. With this new vector system we analysed the chro mosomal distribution of the Drosophila SU(VAR)3-9 protein tagged with EGFP, using hsp70-cDNA and genomic Su(var)3-9 constructs. We found preferential association of the tagged SU(VAR)3-9 with centric heterochromatin.