Complete mitochondrial genome sequences of the three pelagic chaetognaths Sagitta nagae, Sagitta decipiens and Sagitta enflata

Miyamoto, Hiroomi; Machida, Ryuji J.; Nishida, Shuhei

doi:10.1016/j.cbd.2009.11.002

Cited by 17 publications

(23 citation statements)

References 33 publications

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“…Variation in the gene content is illustrated by the loss of all but one or two tRNA genes, a feature also found in some demosponges and in all chaetognaths (Helfenbein et al 2004; Papillon et al 2004; Faure and Casanova 2006; Wang and Lavrov 2008; Miyamoto et al 2010). In addition, introns (e.g., Beagley et al, 1998; Chen et al 2008), duplicated genes (Kayal and Lavrov 2008; Voigt et al 2008), and extra protein genes ( mutS in octocorals, polB in Scyphozoa, and unidentified open reading frames (ORFs) in several hexacorals) have been found in several cnidarian classes (Pont-Kingdon et al 1998; Medina et al 2006; Shao et al 2006).…”

Section: Introductionmentioning

confidence: 81%

Evolution of Linear Mitochondrial Genomes in Medusozoan Cnidarians

Kayal

Bentlage

Collins

et al. 2011

Genome Biology and Evolution

133

180

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In nearly all animals, mitochondrial DNA (mtDNA) consists of a single circular molecule that encodes several subunits of the protein complexes involved in oxidative phosphorylation as well as part of the machinery for their expression. By contrast, mtDNA in species belonging to Medusozoa (one of the two major lineages in the phylum Cnidaria) comprises one to several linear molecules. Many questions remain on the ubiquity of linear mtDNA in medusozoans and the mechanisms responsible for its evolution, replication, and transcription. To address some of these questions, we determined the sequences of nearly complete linear mtDNA from 24 species representing all four medusozoan classes: Cubozoa, Hydrozoa, Scyphozoa, and Staurozoa. All newly determined medusozoan mitochondrial genomes harbor the 17 genes typical for cnidarians and map as linear molecules with a high degree of gene order conservation relative to the anthozoans. In addition, two open reading frames (ORFs), polB and ORF314, are identified in cubozoan, schyphozoan, staurozoan, and trachyline hydrozoan mtDNA. polB belongs to the B-type DNA polymerase gene family, while the product of ORF314 may act as a terminal protein that binds telomeres. We posit that these two ORFs are remnants of a linear plasmid that invaded the mitochondrial genomes of the last common ancestor of Medusozoa and are responsible for its linearity. Hydroidolinan hydrozoans have lost the two ORFs and instead have duplicated cox1 at each end of their mitochondrial chromosome(s). Fragmentation of mtDNA occurred independently in Cubozoa and Hydridae (Hydrozoa, Hydroidolina). Our broad sampling allows us to reconstruct the evolutionary history of linear mtDNA in medusozoans.

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Section: Introductionmentioning

confidence: 81%

Evolution of Linear Mitochondrial Genomes in Medusozoan Cnidarians

Kayal

Bentlage

Collins

et al. 2011

Genome Biology and Evolution

133

180

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“…By comparison, chaetognaths lost all but one of their tRNA genes (Faure and Casanova, 2006; Helfenbein et al, 2004; Miyamoto et al, 2010). Interestingly, some unicellular eukaryotes such as apicomplexans and trypanosomatids encode no tRNAs in their mtDNA genomes.…”

Section: Discussionmentioning

confidence: 99%

“…in Mytilus see (Breton et al, 2010); (Smietanka et al, 2010)), secernentean nematodes (Lavrov and Brown, 2001), and platyhelminths (Le et al, 2000)). All 5 species of chaetognaths studied so far have also lost both their atp6 and 8 genes (Faure and Casanova, 2006; Helfenbein et al, 2004; Miyamoto et al, 2010). Interestingly, even a very conservative organization of mtDNA genomes in land vertebrates can be subject to extensive gene loss, as reported for certain amphibians.…”

Section: Discussionmentioning

confidence: 99%

Rapid evolution of the compact and unusual mitochondrial genome in the ctenophore, Pleurobrachia bachei

Kohn

Citarella

Kocot

et al. 2012

Molecular Phylogenetics and Evolution

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Ctenophores are one of the most basally branching lineages of metazoans with the largest mitochondrial organelles in the animal kingdom. We sequenced the mitochondrial (mtDNA) genome from the Pacific cidipid ctenophore, Pleurobrachia bachei. The circular mitochondrial genome is 11,016 nts, with only 12 genes, and one of the smallest metazoan mtDNA genomes recorded. The protein coding genes are intronless cox1-3, cob, nad1, 3, 4, 4L and 5. The nad2 and 6 genes are represented as short fragments whereas the atp6 gene was found in the nuclear genome. Only the large ribosomal RNA subunit and 2 tRNAs were present with possibly the small subunit unidentifiable due to extensive fragmentation. The observed unique features of this mitochondrial genome suggest that nuclear and mitochondrial genomes have evolved at very different rates. This reduced mtDNA genome sharply contrasts with the very large sizes of mtDNA found in other basal metazoans including Porifera (sponges), and Placozoa (Trichoplax).

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“…In addition, a transient linear genome has been reported in the isopod Armadillidium vulgare (Marcadé et al 2007). Second, the size of bilaterian mtDNA was shown to be more variable than originally thought, ranging from just over 11 kb in chaetognaths (Helfenbein et al 2004; Papillon et al 2004; Faure and Casanova 2006; Miyamoto et al 2010) to over 50 kb in the ark shell Scapharca broughtonii (Liu et al 2013). Third, several changes in gene content have been reported, including losses of atp8 in most nematodes (Okimoto et al 1992; Sultana et al 2013; but see Lavrov and Brown 2001) and flatworms (Le et al 2000; Von Nickisch-Rosenegk et al 2001; Sola et al 2015), the loss of atp6 , atp8 and most tRNA genes in Chaetognatha (Helfenbein et al 2004; Papillon et al 2004; but see Barthelemy and Seligmann 2016), and the gain of a putative novel gene in bivalve molluscs with doubly uniparental inheritance (Breton et al 2011; Zouros 2013).…”

Section: Typical Animal Mitochondrial Dna: the Birth Of A Mythmentioning

confidence: 94%

Animal Mitochondrial DNA as We Do Not Know It: mt-Genome Organization and Evolution in Nonbilaterian Lineages

2016

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Animal mitochondrial DNA (mtDNA) is commonly described as a small, circular molecule that is conserved in size, gene content, and organization. Data collected in the last decade have challenged this view by revealing considerable diversity in animal mitochondrial genome organization. Much of this diversity has been found in nonbilaterian animals (phyla Cnidaria, Ctenophora, Placozoa, and Porifera), which, from a phylogenetic perspective, form the main branches of the animal tree along with Bilateria. Within these groups, mt-genomes are characterized by varying numbers of both linear and circular chromosomes, extra genes (e.g. atp9, polB, tatC), large variation in the number of encoded mitochondrial transfer RNAs (tRNAs) (0–25), at least seven different genetic codes, presence/absence of introns, tRNA and mRNA editing, fragmented ribosomal RNA genes, translational frameshifting, highly variable substitution rates, and a large range of genome sizes. This newly discovered diversity allows a better understanding of the evolutionary plasticity and conservation of animal mtDNA and provides insights into the molecular and evolutionary mechanisms shaping mitochondrial genomes.

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Complete mitochondrial genome sequences of the three pelagic chaetognaths Sagitta nagae, Sagitta decipiens and Sagitta enflata

Cited by 17 publications

References 33 publications

Evolution of Linear Mitochondrial Genomes in Medusozoan Cnidarians

Evolution of Linear Mitochondrial Genomes in Medusozoan Cnidarians

Rapid evolution of the compact and unusual mitochondrial genome in the ctenophore, Pleurobrachia bachei

Animal Mitochondrial DNA as We Do Not Know It: mt-Genome Organization and Evolution in Nonbilaterian Lineages

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