Deletion that removes the histone complex.

The Df(2L)HisC-cadillac chromosome is a precise deletion of the histone gene array, with a multifunctional cassette that permits site-specific insertion of either one or two synthetic gene arrays inserted in place of the deleted sequence. Df(2L)HisC-cadillac was generated by replacing the P{3'.RS5+3.3'}His-C insertion in Df(2L)His^C with a multifunctional cassette that encodes a Disc\RFP^{DsRed(T1).Act5C} marker. In addition, Lamp1 gene sequence was inserted, restoring an intact Lamp1 gene. The Disc\RFP^{DsRed(T1).Act5C} marker in the multifunctional cassette is flanked on each side by a pair of attP sites (the two sites are in the same orientation). This allows for integration of one or two transgenic histone gene arrays (using a donor plasmid containing a single attB site). A single loxP site is present between the upstream attP site and the promoter of the Disc\RFP^{DsRed(T1).Act5C} marker; this can be used to remove vector sequences after integration (provided the inserted sequence itself contains a loxP site). The two attP sites can also be used for recombinase-mediated cassette exchange (where the sequence between the two attP sites is replaced with sequence from a donor plasmid containing a pair of attB sites that flank the sequence to be integrated). A B2RT site and a B3RT site are present upstream of the distal attP site upstream of the Disc\RFP^{DsRed(T1).Act5C} marker, a B3RT site is present in between the 3' end of the Disc\RFP^{DsRed(T1).Act5C} marker and the proximal attP site downstream of the marker, and a B2RT site is present downstream of the proximal attP site. This arrangement allows for excision of sequences that are subsequently integrated at either of the attP sites in Df(2L)HisC-cadillac. Recombination using B2RT recombinase removes both attP sites and any sequence integrated into them. Recombination using B3RT recombinase removes only the distal attP site (and any sequence integrated into it). The Df(2L)HisC-cadillac chromosome also carries the centromere proximal P{neoFRT}40A insertion to facilitate mitotic recombination.