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Complete mitochondrial genomes of Carcinoscorpius rotundicauda and Tachypleus tridentatus (Xiphosura, Arthropoda) and implications for chelicerate phylogenetic studies.

Baek SY, Choi EH, Jang KH, Ryu SH, Park SM, Suk HY, Chang CY, Hwang UW - Int. J. Biol. Sci. (2014)

Bottom Line: Overall sequences and genome structure of two Asian species were highly similar to that of Limulus polyphemus, though clear differences among three were found in the stem-loop structure of the putative control region.In the phylogenetic analysis with complete mitochondrial genomes of 43 chelicerate species, C. rotundicauda and T. tridentatus were recovered as a monophyly, while L. polyphemus solely formed an independent clade.In conclusion, our analyses may provide more robust and reliable perspective on the study of evolutionary history for chelicerates than earlier analyses with a single Atlantic species.

View Article: PubMed Central - PubMed

Affiliation: 1. School of Life Sciences, Graduate School, Kyungpook National University, Daegu 702-701, South Korea.

ABSTRACT
Horseshoe crabs (order Xiphosura) are often referred to as an ancient order of marine chelicerates and have been considered as keystone taxa for the understanding of chelicerate evolution. However, the mitochondrial genome of this order is only available from a single species, Limulus polyphemus. In the present study, we analyzed the complete mitochondrial genomes from two Asian horseshoe crabs, Carcinoscorpius rotundicauda and Tachypleus tridentatus to offer novel data for the evolutionary relationship within Xiphosura and their position in the chelicerate phylogeny. The mitochondrial genomes of C. rotundicauda (15,033 bp) and T. tridentatus (15,006 bp) encode 13 protein-coding genes, two ribosomal RNA (rRNA) genes, and 22 transfer RNA (tRNA) genes. Overall sequences and genome structure of two Asian species were highly similar to that of Limulus polyphemus, though clear differences among three were found in the stem-loop structure of the putative control region. In the phylogenetic analysis with complete mitochondrial genomes of 43 chelicerate species, C. rotundicauda and T. tridentatus were recovered as a monophyly, while L. polyphemus solely formed an independent clade. Xiphosuran species were placed at the basal root of the tree, and major other chelicerate taxa were clustered in a single monophyly, clearly confirming that horseshoe crabs composed an ancestral taxon among chelicerates. By contrast, the phylogenetic tree without the information of Asian horseshoe crabs did not support monophyletic clustering of other chelicerates. In conclusion, our analyses may provide more robust and reliable perspective on the study of evolutionary history for chelicerates than earlier analyses with a single Atlantic species.

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Related in: MedlinePlus

Putative tRNA secondary structures predicted from the 22 tRNA gene sequences found in the (A) Carcinoscorpius rotundicauda and (B) Tachypleus tridentatus mitochondrial genome.
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Figure 2: Putative tRNA secondary structures predicted from the 22 tRNA gene sequences found in the (A) Carcinoscorpius rotundicauda and (B) Tachypleus tridentatus mitochondrial genome.

Mentions: A total of 22 tRNA genes ranging from 62 to 73 bp in length were identified in mitochondrial genomes of both C. rotundicauda and T. tridentatus. The putative secondary structure for each tRNA gene could be predicted based on the sequences (Fig. 2). The sequences, anticodon nucleotides, and secondary structures of tRNA genes from both C. rotundicauda and T. tridentatus were very similar to those observed in L. polyphemus13. All of the tRNA genes were capable of forming typical cloverleaf secondary structures (dihydrouridine, DHU), with an exception of trnS1; trnS1 lacked DHU arm in T. tridentatus (Fig. 2B) and had a shortened stem (2 bp) in C. rotundicauda (Fig. 2A). Two rRNA genes (rrnS and rrnL) were encoded on the light strand and were separated by a trnV in both mitochondrial genomes analyzed. The sizes of rrnS and rrnL were estimated to be 816 bp (rrnS) and 1,301 bp (rrnL) for C. rotundicauda and 800 bp (rrnS) and 1,294 bp for T. tridentatus.


Complete mitochondrial genomes of Carcinoscorpius rotundicauda and Tachypleus tridentatus (Xiphosura, Arthropoda) and implications for chelicerate phylogenetic studies.

Baek SY, Choi EH, Jang KH, Ryu SH, Park SM, Suk HY, Chang CY, Hwang UW - Int. J. Biol. Sci. (2014)

Putative tRNA secondary structures predicted from the 22 tRNA gene sequences found in the (A) Carcinoscorpius rotundicauda and (B) Tachypleus tridentatus mitochondrial genome.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4007361&req=5

Figure 2: Putative tRNA secondary structures predicted from the 22 tRNA gene sequences found in the (A) Carcinoscorpius rotundicauda and (B) Tachypleus tridentatus mitochondrial genome.
Mentions: A total of 22 tRNA genes ranging from 62 to 73 bp in length were identified in mitochondrial genomes of both C. rotundicauda and T. tridentatus. The putative secondary structure for each tRNA gene could be predicted based on the sequences (Fig. 2). The sequences, anticodon nucleotides, and secondary structures of tRNA genes from both C. rotundicauda and T. tridentatus were very similar to those observed in L. polyphemus13. All of the tRNA genes were capable of forming typical cloverleaf secondary structures (dihydrouridine, DHU), with an exception of trnS1; trnS1 lacked DHU arm in T. tridentatus (Fig. 2B) and had a shortened stem (2 bp) in C. rotundicauda (Fig. 2A). Two rRNA genes (rrnS and rrnL) were encoded on the light strand and were separated by a trnV in both mitochondrial genomes analyzed. The sizes of rrnS and rrnL were estimated to be 816 bp (rrnS) and 1,301 bp (rrnL) for C. rotundicauda and 800 bp (rrnS) and 1,294 bp for T. tridentatus.

Bottom Line: Overall sequences and genome structure of two Asian species were highly similar to that of Limulus polyphemus, though clear differences among three were found in the stem-loop structure of the putative control region.In the phylogenetic analysis with complete mitochondrial genomes of 43 chelicerate species, C. rotundicauda and T. tridentatus were recovered as a monophyly, while L. polyphemus solely formed an independent clade.In conclusion, our analyses may provide more robust and reliable perspective on the study of evolutionary history for chelicerates than earlier analyses with a single Atlantic species.

View Article: PubMed Central - PubMed

Affiliation: 1. School of Life Sciences, Graduate School, Kyungpook National University, Daegu 702-701, South Korea.

ABSTRACT
Horseshoe crabs (order Xiphosura) are often referred to as an ancient order of marine chelicerates and have been considered as keystone taxa for the understanding of chelicerate evolution. However, the mitochondrial genome of this order is only available from a single species, Limulus polyphemus. In the present study, we analyzed the complete mitochondrial genomes from two Asian horseshoe crabs, Carcinoscorpius rotundicauda and Tachypleus tridentatus to offer novel data for the evolutionary relationship within Xiphosura and their position in the chelicerate phylogeny. The mitochondrial genomes of C. rotundicauda (15,033 bp) and T. tridentatus (15,006 bp) encode 13 protein-coding genes, two ribosomal RNA (rRNA) genes, and 22 transfer RNA (tRNA) genes. Overall sequences and genome structure of two Asian species were highly similar to that of Limulus polyphemus, though clear differences among three were found in the stem-loop structure of the putative control region. In the phylogenetic analysis with complete mitochondrial genomes of 43 chelicerate species, C. rotundicauda and T. tridentatus were recovered as a monophyly, while L. polyphemus solely formed an independent clade. Xiphosuran species were placed at the basal root of the tree, and major other chelicerate taxa were clustered in a single monophyly, clearly confirming that horseshoe crabs composed an ancestral taxon among chelicerates. By contrast, the phylogenetic tree without the information of Asian horseshoe crabs did not support monophyletic clustering of other chelicerates. In conclusion, our analyses may provide more robust and reliable perspective on the study of evolutionary history for chelicerates than earlier analyses with a single Atlantic species.

Show MeSH
Related in: MedlinePlus