Differential hybridization screening. Differentially expressed clones in a 8-10 h AEL embryonic suppression subtraction hybridization (SSH) / mirror orientation selection (MOS) library. 410 randomly selected clones were spotted onto 5 nylon membranes in four replicates (A to E) and hybridized with labelled probe from: subtracted XX/XY vs XX-only SSH/MOS cDNAs (forward); subtracted XX-only vs XX/XY SSH/MOS cDNAs (reverse); unsubtracted XX/XY cDNAs (unsub test); unsubtracted XX-only cDNAs (unsub driv). Hybridization signals were scored visually. Red circles indicate the selected 26 clones.