Finishing a whole-genome shotgun: release 3 of the Drosophila melanogaster euchromatic genome sequence

Susan E Celniker, David A Wheeler, Brent Kronmiller, Joseph W Carlson, Aaron Halpern, Sandeep Patel, Mark Adams, Mark Champe, Shannon P Dugan, Erwin Frise, Ann Hodgson, Reed A George (+20 others)
2002 Genome Biology  
The Drosophila melanogaster genome was the first metazoan genome to have been sequenced by the whole-genome shotgun (WGS) method. Two issues relating to this achievement were widely debated in the genomics community: how correct is the sequence with respect to base-pair (bp) accuracy and frequency of assembly errors? And, how difficult is it to bring a WGS sequence to the accepted standard for finished sequence? We are now in a position to answer these questions. Our finishing process was
more » ... ed to close gaps, improve sequence quality and validate the assembly. Sequence traces derived from the WGS and draft sequencing of individual bacterial artificial chromosomes (BACs) were assembled into BAC-sized segments. These segments were brought to high quality, and then joined to constitute the sequence of each chromosome arm. Overall assembly was verified by comparison to a physical map of fingerprinted BAC clones. In the current version of the 116.9 Mb euchromatic genome, called Release 3, the six euchromatic chromosome arms are represented by 13 scaffolds with a total of 37 sequence gaps. We compared Release 3 to Release 2; in autosomal regions of unique sequence, the error rate of Release 2 was one in 20,000 bp. The WGS strategy can efficiently produce a high-quality sequence of a metazoan genome while generating the reagents required for sequence finishing. However, the initial method of repeat assembly was flawed. The sequence we report here, Release 3, is a reliable resource for molecular genetic experimentation and computational analysis.
pmid:12537568 pmcid:PMC151181 fatcat:m6myjq5q25fupckcnzz56bvcny