The mitochondrial genome of Pocillopora (Cnidaria: Scleractinia) contains two variable regions: The putative D-loop and a novel ORF of unknown function

Evolution of the mitochondrial genome of Metazoa as exemplified by comparison of congeneric species

“…Although some of these genes are open reading frames (ORFs) with no similarity to known proteins, it has been observed that the additional proteins of Cnidaria are mostly involved in DNA interaction, whereas those of Porifera have metabolic roles (Flot and Tillier, 2007) and are also usually encoded by the mtDNA of closest relatives of metazoans. In fact, among the additional proteins, the atp9 and tatC genes identified in Porifera are also encoded by the mtDNA of protists and unicellular relatives of metazoans (Yen et al, 2002;Burger et al, 2003;Dellaporta et al, 2006), indicating that this is one of the several primitive non-metazoan features retained by Porifera (Haen et al, 2007).…”

“…Recently, the comparative mitogenomics approach has been applied to clarify the taxonomic status of some species, as in the case of members of the coral species complex Montastraea annularis (Cnidaria;Fukami and Knowlton, 2005), coral morphospecies of the genus Pocillopora (Cnidaria;Flot and Tillier, 2007), distinct genotypes of the cestode Echinococcus granulosus (Platyhelminthes; Le et al, 2002), and putative cryptic species of the cosmopolitan ascidian Ciona intestinalis (Tunicata; Iannelli et al, 2007b). These studies demonstrate that the capacity of mtDNA to solve taxonomic controversies at species-level depends on the overall mt evolutionary dynamics, that is on the existence of a fast rate in the nucleotide substitutions and/or in the changes of genome AR.…”

“…These studies demonstrate that the capacity of mtDNA to solve taxonomic controversies at species-level depends on the overall mt evolutionary dynamics, that is on the existence of a fast rate in the nucleotide substitutions and/or in the changes of genome AR. Thus, the low variability of cnidarian mtDNA, characterized by slow substitution rate and rare genomic rearrangements Medina et al, 2006;Wang and Lavrov, 2007), has made the mtDNA useless for species definition in both Montastraea and Pocillopora genera (Fukami and Knowlton, 2005;Flot and Tillier, 2007). In fact, the gene order is identical within both genera, whereas the sequence divergence ranges from 0 to 0.12% between six Montastraea annularis individuals (Fukami and Knowlton, 2005) and is 0.18% between two Pocillopora species (Flot and Tillier, 2007).…”

Comparative Mitochondrial Genomics of Freshwater Mussels (Bivalvia: Unionoida) With Doubly Uniparental Inheritance of mtDNA: Gender-Specific Open Reading Frames and Putative Origins of Replication

“…For example, ORFs that exhibit no significant sequence similarity to known proteins have been recently discovered in the Cnidaria and Porifera (e.g., Shao et al 2006;Flot and Tillier 2007;Wang and Lavrov 2008). Such metazoan ORFs could be (i) homologous to ancestral bacterial protein-coding genes, (ii) the product of mitochondrial gene duplication events, or (iii) the result of DNA transferred from nuclear genomes.…”

Marginal coral populations: the densest known aggregation of Pocillopora in the Galápagos Archipelago is of asexual origin

“…The mitochondrial open reading frame of unknown function (ORF) was amplified with the FATP6.1 and the RORF primers (Flot and Tillier, 2007;Flot et al, 2008). This was done for a subset of samples; 4 from inside the volcanic pools and all 40 from the islands of Darwin, Wolf, and Marchena.…”