Patterns of Base Composition Within the Genes of Drosophila melanogaster |
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Authors: | Richard M Kliman Adam Eyre-Walker |
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Institution: | (1) Department of Biology, Radford University, Radford, VA 24142, USA, US;(2) Centre for the Study of Evolution and Department of Biological Sciences, University of Sussex, Brighton BN1 9QG, UK, GB |
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Abstract: | 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.
Received: 24 February 1997 / Accepted: 10 November 1997 |
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Keywords: | : G+C content — Isochores — Synonymous codon use |
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