Isolation and characterization of Df(2L)BSC183 Stacey Christensen and Kevin Cook Bloomington Stock Center Indiana University Df(2L)BSC183 was isolated as a FLP recombinase-induced recombination event involving P{XP}CG9016d08241 and PBac{RB}Ucp4Ce03988. The deletion was isolated as a chromosome lacking miniwhite markers in progeny of P{hsFLP}1, y1 w1118; P{XP}CG9016d08241/PBac{RB}Ucp4Ce03988 males crossed to w1118; P{hs-hid}2, wgSp-1/CyO females. These males were heat shocked as larvae as described in Parks et al., Nature Genetics 36: 288-292, 2004 (FBrf0175003). This cross and crosses in preceding and succeeding generations maintained the original genetic background of the Exelixis insertion stocks (Thibault et al., Nature Genetics 36: 283-287, 2004; FBrf0175002). The recombination event generated the genetic element P+PBac{XP5.RB3}BSC183 from the segment of P{XP}CG9016d08241 to the left of its FRT site and the segment of PBac{RB}Ucp4Ce03988 to the right of its FRT site. Its presence was verified using the PCR methods and primers described in Parks et al. with the substitution of the primer 5'-CCAATGCGTTTATTTCAGGTCACG-3' for the RB3' plus or RB3' minus primer in the Hybrid PCR protocol in the Supplementary Methods. The cytological breakpoints of Df(2L)BSC183 predicted from the Release 4 genomic coordinates of the transposable element insertion sites are 26A1;26A5. It failed to complement Vm26AbQJ42.