Analysis of 14 BAC sequences from the Aedes aegypti genome: a benchmark for genome annotation and assembly

BACKGROUND: Aedes aegypti is the principal vector of yellow fever and dengue viruses throughout the tropical world. To provide a set of manually curated and annotated sequences from the Ae. aegypti genome, 14 mapped bacterial artificial chromosome (BAC) clones encompassing 1.57 Mb were sequenced, assembled and manually annotated using a combination of computational gene-finding, expressed sequence tag (EST) matches and comparative protein homology. PCR and sequencing were used to experimentally confirm expression and sequence of a subset of these transcripts. RESULTS: Of the 51 manual annotations, 50 and 43 demonstrated a high level of similarity to Anopheles gambiae and Drosophila melanogaster genes, respectively. Ten of the 12 BAC sequences with more than one annotated gene exhibited synteny with the A. gambiae genome. Putative transcripts from eight BAC clones were found in multiple copies (two copies in most cases) in the Aedes genome assembly, which point to the probable presence of haplotype polymorphisms and/or misassemblies. CONCLUSION: This study not only provides a benchmark set of manually annotated transcripts for this genome that can be used to assess the quality of the auto-annotation pipeline and the assembly, but it also looks at the effect of a high repeat content on the genome assembly and annotation pipeline.