2006 EXPRESSED-SEQUENCE TAGS DERIVED FROM HUMAN-CHROMOSOME-7-ENRICHEDCDNA LIBRARIES

The establishment and mapping of gene-specific DNA sequences greatly c omplement the ongoing efforts to map and sequence all human chromosome s. To facilitate our studies of human chromosome 7, we have generated and analyzed 2006 expressed-sequence tags (ESTs) derived from a collec tion of direct selection cDNA libraries that are highly enriched for h uman chromosome 7 gene sequences. Similarity searches indicate that ap proximately two-thirds of the ESTs are not represented by sequences in the public databases, including those in dbEST. In addition, a large fraction (68%) of the ESTs do not have redundant or overlapping sequen ces within our collection. Human DNA-specific sequence-tagged sites (S TSs) have been developed from 190 of the ESTs. Remarkably, 180 (96%) o f these STSs map to chromosome 7, demonstrating the robustness of chro mosome enrichment in constructing the direct selection cDNA libraries. Thus far, 140 of these EST-specific STSs have been assigned unequivoc ally to YAC contigs that are distributed across the chromosome. Togeth er, these studies provide >2000 ESTs highly enriched for chromosome 7 gene sequences, 180 new chromosome 7 STSs corresponding to ESTs, and a definitive demonstration of the ability to enrich for chromosome-spec ific cDNAs by direct selection. Furthermore, the libraries, sequence d ata, and mapping information will contribute to the construction of a chromosome 7 transcript map.