DISCOVERING DISTINCT GENES REPRESENTED IN 29,570 CLONES FROM INFANT BRAIN CDNA LIBRARIES BY APPLYING SEQUENCING BY HYBRIDIZATION METHODOLOGY

To discover all distinct human genes and to determine their patterns o f expression across different cell types, developmental stages, and ph ysiological conditions, a procedure is needed for fast, mutual compari son of hundreds of thousands (and perhaps millions) of clones from cDN A libraries, a; well as their comparison against data bases of sequenc ed DNA. In a pilot study, 29,570 clones in duplicate from both origina l and normalized, directional, infant brain cDNA libraries were hybrid ized with 107-215 heptamer oligonucleotide probes to obtain oligonucle otide sequence signatures (OSSs). The OSSs were compared and clustered based on mutual similarity into 16,741 clusters, each corresponding t o a distinct cDNA. A number of distinct cDNAs were successfully recogn ized by matching their 107-probe OSSs against GenBank entries, indicat ing the possibility of sequence recognition with only a few hundred ra ndomly chosen oligomers.