MBE Advance Access originally published online on June 22, 2005
Molecular Biology and Evolution 2005 22(10):2063-2072; doi:10.1093/molbev/msi197
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Research Article |
Entropy and GC Content in the ß-esterase Gene Cluster of the Drosophila melanogaster Subgroup
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* Department of Ecology and Evolutionary Biology, University of California, Irvine;
Academy of Ecology, Marine Biology, and Biotechnology, Far Eastern State University, Vladivostok, Russia;
Institute of Marine Biology, Vladivostok, Russia; and
Troitsk Institute of Innovation and Thermonuclear Investigations (TRINITI), Theoretical Department of Division for Perspective Investigations, Moscow Region, Russia
E-mail: fjayala{at}uci.edu.
We perform spectral entropy and GC content analyses in the ß-esterase gene cluster, including the Est-6 gene and the
Est-6 putative pseudogene, in seven species of the Drosophila melanogaster species subgroup.
Est-6 combines features of functional and nonfunctional genes. The spectral entropies show distinctly lower structural ordering for
Est-6 than for Est-6 in all species studied. Our observations agree with previous results for D. melanogaster and provide additional support to our hypothesis that after the duplication event Est-6 retained the esterase-coding function and its role during copulation, while
Est-6 lost that function but now operates in conjunction with Est-6 as an intergene. Entropy accumulation is not a completely random process for either gene. Structural entropy is nucleotide dependent. The relative normalized deviations for structural entropy are higher for G than for C nucleotides. The entropy values are similar for Est-6 and
Est-6 in the case of A and T but are lower for Est-6 in the case of G and C. The GC content in synonymous positions is uniformly higher in Est-6 than in
Est-6, which agrees with the reduced GC content generally observed in pseudogenes and nonfunctional sequences. The observed differences in entropy and GC content reflect an evolutionary shift associated with the process of pseudogenization and subsequent functional divergence of
Est-6 and Est-6 after the duplication event.
Key Words: Drosophila melanogaster subgroup ß-esterase gene cluster Est-6
Est-6 entropy GC content