Adult heads were collected from an isogenic y; cn bw sp (iso-1) strain.

RNA from adult heads was poly(A)+ selected once. cDNA made using Stratagene ZAP-cDNA synthesis kit; oligo(dT) primed with XhoI site at end of primer for first strand synthesis; EcoRI adapter on 5' ends of clones; size fractionated on Sephacryl S-500--approximately 1-6kb. For clones HL07801 and higher, cDNA directionally cloned into EcoRI/XhoI-digested pOT2 plasmid.

The GH library is separate from the HL library. Since many of the HL clones were not full length and others lacked inserts, a new adult head library was made.