Comparative genomics of Anopheles gambiae and Drosophila melanogaster

Abstract

A sequence analysis of the genomes of Anopheles gambiae and Drosophila melanogaster reveals that Anopheles DNA is more heterogeneous and GC-richer than Drosophila DNA. The gene concentration across the Anopheles genome is characterized by low levels in the GC-poor part of the genome and a 3-fold increase in the GC-richest part; this gene density gradient is approximately half that of Drosophila. GC levels of introns and flanking sequences are correlated with GC 3 values (GC levels of third codon positions) of the corresponding genes with slopes much lower than unity; in other words, most introns and intergenic sequences are less GC-rich than the corresponding GC 3 values. These findings, which describe a compositional shift within Diptera, is of interest because of their parallels in the well studied major shift in vertebrates.