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Open Access Research article

The nuclear OXPHOS genes in insecta: a common evolutionary origin, a common cis-regulatory motif, a common destiny for gene duplicates

Damiano Porcelli1, Paolo Barsanti1, Graziano Pesole2 and Corrado Caggese1*

Author Affiliations

1 Dipartimento di Genetica e Microbiologia (DIGEMI), Università di Bari, Italy

2 Dipartimento di Biochimica e Biologia Molecolare, Università di Bari, Italy

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BMC Evolutionary Biology 2007, 7:215  doi:10.1186/1471-2148-7-215

Published: 8 November 2007

Abstract

Background

When orthologous sequences from species distributed throughout an optimal range of divergence times are available, comparative genomics is a powerful tool to address problems such as the identification of the forces that shape gene structure during evolution, although the functional constraints involved may vary in different genes and lineages.

Results

We identified and annotated in the MitoComp2 dataset the orthologs of 68 nuclear genes controlling oxidative phosphorylation in 11 Drosophilidae species and in five non-Drosophilidae insects, and compared them with each other and with their counterparts in three vertebrates (Fugu rubripes, Danio rerio and Homo sapiens) and in the cnidarian Nematostella vectensis, taking into account conservation of gene structure and regulatory motifs, and preservation of gene paralogs in the genome. Comparative analysis indicates that the ancestral insect OXPHOS genes were intron rich and that extensive intron loss and lineage-specific intron gain occurred during evolution. Comparison with vertebrates and cnidarians also shows that many OXPHOS gene introns predate the cnidarian/Bilateria evolutionary split. The nuclear respiratory gene element (NRG) has played a key role in the evolution of the insect OXPHOS genes; it is constantly conserved in the OXPHOS orthologs of all the insect species examined, while their duplicates either completely lack the element or possess only relics of the motif.

Conclusion

Our observations reinforce the notion that the common ancestor of most animal phyla had intron-rich gene, and suggest that changes in the pattern of expression of the gene facilitate the fixation of duplications in the genome and the development of novel genetic functions.