Patterns of base composition within the genes of Drosophila melanogaster

J Mol Evol. 1998 May;46(5):534-41. doi: 10.1007/pl00006334.


Base composition is not uniform across the genome of Drosophila melanogaster. Earlier analyses have suggested that there is variation in composition in D. melanogaster on both a large scale and a much smaller, within-gene, scale. Here we present analyses on 117 genes which have reliable intron/exon boundaries and no known alternative splicing. We detect significant heterogeneity in G+C content among intron segments from the same gene, as well as a significant positive correlation between the intron and the third codon position G+C content within genes. Both of these observations appear to be due, in part, to an overall decline in intron and third codon position G+C content along Drosophila genes with introns. However, there is also evidence of an increase in third codon position G+C content at the start of genes; this is particularly evident in genes without introns. This is consistent with selection acting against preferred codons at the start of genes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Composition
  • Drosophila melanogaster / genetics*
  • Exons
  • Genes, Insect*
  • Genetic Variation
  • Introns