Isolation and characterization of Df(3R)BSC805 Stacey Christensen, Kim Cook and Kevin Cook Bloomington Stock Center Indiana University Df(3R)BSC805 was isolated as a FLP recombinase-induced recombination event involving PBac{WH}Gr93af01688 and P{XP}PyKd05959. The deletion was isolated as a chromosome lacking miniwhite markers in progeny of w1118; P{hs-hid}3, Dr1/TM6C, Sb1 cu1 females crossed to P{hsFLP}1, y1 w1118; PBac{WH}Gr93af01688/P{XP}PyKd05959 males. The 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.WH5}BSC805 from the segment of PBac{WH}Gr93af01688 to the left of its FRT site and the segment of P{XP}PyKd05959 to the right of its FRT site. Its presence was verified using the PCR methods and primers described in Parks et al. The breakpoints of Df(3R)BSC805 predicted from the Release 5 genomic coordinates of the transposable element insertion sites are 3R:17659537 ;18193695..18193698 and the cytological breakpoints predicted from these coordinates are 93F13;94A6. Df(3R)BSC805 failed to complement howstru-3R-3 and Df(3R)ED6076.