Figure 1.

Summary of our screening scheme. cDNA subtraction was performed with cDNA from three mRNA sources as shown, to generate forward- (F) and reverse-subtracted (R) cDNA pools. These subtracted cDNA pools were used as probes for differential hybridization on high-density grid filters, on which 7,584 EST clones had been spotted. Expression pattern of several clones that gave differential signals was determined by in situ hybridization. One hundred and sixty-eight clones were subjected to RNAi, of which 15 gave a sterile phenotype.