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Complete mitochondrial genome of the free-living earwig, Challia fletcheri (Dermaptera: Pygidicranidae) and phylogeny of Polyneoptera.

Wan X, Kim MI, Kim MJ, Kim I - PLoS ONE (2012)

Bottom Line: We sequenced the complete mitochondrial genome of the free-living earwig, Challia fletcheri, compared its genomic features to other available mitochondrial sequences from polyneopterous insects.The reversal pattern of skewness is explained in terms of inversion of replication origin.All phylogenetic analyses consistently placed Dermaptera as the sister to Plecoptera, leaving them as the most basal lineage of Polyneoptera or sister to Ephemeroptera, and placed Odonata consistently as the most basal lineage of the Pterygota.

View Article: PubMed Central - PubMed

Affiliation: College of Agriculture & Life Sciences, Chonnam National University, Gwangju, Republic of Korea.

ABSTRACT
The insect order Dermaptera, belonging to Polyneoptera, includes ∼2,000 extant species, but no dermapteran mitochondrial genome has been sequenced. We sequenced the complete mitochondrial genome of the free-living earwig, Challia fletcheri, compared its genomic features to other available mitochondrial sequences from polyneopterous insects. In addition, the Dermaptera, together with the other known polyneopteran mitochondrial genome sequences (protein coding, ribosomal RNA, and transfer RNA genes), were employed to understand the phylogeny of Polyneoptera, one of the least resolved insect phylogenies, with emphasis on the placement of Dermaptera. The complete mitochondrial genome of C. fletcheri presents the following several unusual features: the longest size in insects is 20,456 bp; it harbors the largest tandem repeat units (TRU) among insects; it displays T- and G-skewness on the major strand and A- and C-skewness on the minor strand, which is a reversal of the general pattern found in most insect mitochondrial genomes, and it possesses a unique gene arrangement characterized by a series of gene translocations and/or inversions. The reversal pattern of skewness is explained in terms of inversion of replication origin. All phylogenetic analyses consistently placed Dermaptera as the sister to Plecoptera, leaving them as the most basal lineage of Polyneoptera or sister to Ephemeroptera, and placed Odonata consistently as the most basal lineage of the Pterygota.

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Related in: MedlinePlus

Predicted secondary structures for the 22 tRNA genes of C. fletcheri.Dashes (–) indicate Watson-Crick base-pairing and centered dots (•) indicate G-U base-pairing. Arms of tRNAs (clockwise from top) are the amino acid acceptor (AA) arm, TψC (T) arm, the anticodon (AC) arm, and the dihydrouridine (DHU) arm.
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pone-0042056-g002: Predicted secondary structures for the 22 tRNA genes of C. fletcheri.Dashes (–) indicate Watson-Crick base-pairing and centered dots (•) indicate G-U base-pairing. Arms of tRNAs (clockwise from top) are the amino acid acceptor (AA) arm, TψC (T) arm, the anticodon (AC) arm, and the dihydrouridine (DHU) arm.

Mentions: The complete set of 22 tRNAs (one specific for each amino acid, and 2 each for leucine and serine) found in metazoan mitochondrial genomes were identified in C. fletcheri, and they are interspersed throughout the genome (Table 1; Figure 2). Of the 22 tRNAs, 21 can be folded into a typical cloverleaf structure with a 7-bp amino-acyl stem, 5-bp anticodon arm, 7-bp anticodon loop, a variable loop, DHU arm, and a TψC arm. Unlike others, the trnS(AGN) lacks the DHU stem, and instead, has a 12-bp long DHU loop, as is commonly found in metazoan mitochondrial genomes [3]. A somewhat unusual feature found in trnE and trnP is the presence of much larger variable loops (20 and 19-bp long, respectively; Figure 2) than in other insects. The anticodons of C. fletcheri tRNAs (Table 1) are all identical to those of the respective tRNAs found in the other Polyneoptera (data not shown).


Complete mitochondrial genome of the free-living earwig, Challia fletcheri (Dermaptera: Pygidicranidae) and phylogeny of Polyneoptera.

Wan X, Kim MI, Kim MJ, Kim I - PLoS ONE (2012)

Predicted secondary structures for the 22 tRNA genes of C. fletcheri.Dashes (–) indicate Watson-Crick base-pairing and centered dots (•) indicate G-U base-pairing. Arms of tRNAs (clockwise from top) are the amino acid acceptor (AA) arm, TψC (T) arm, the anticodon (AC) arm, and the dihydrouridine (DHU) arm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3412835&req=5

pone-0042056-g002: Predicted secondary structures for the 22 tRNA genes of C. fletcheri.Dashes (–) indicate Watson-Crick base-pairing and centered dots (•) indicate G-U base-pairing. Arms of tRNAs (clockwise from top) are the amino acid acceptor (AA) arm, TψC (T) arm, the anticodon (AC) arm, and the dihydrouridine (DHU) arm.
Mentions: The complete set of 22 tRNAs (one specific for each amino acid, and 2 each for leucine and serine) found in metazoan mitochondrial genomes were identified in C. fletcheri, and they are interspersed throughout the genome (Table 1; Figure 2). Of the 22 tRNAs, 21 can be folded into a typical cloverleaf structure with a 7-bp amino-acyl stem, 5-bp anticodon arm, 7-bp anticodon loop, a variable loop, DHU arm, and a TψC arm. Unlike others, the trnS(AGN) lacks the DHU stem, and instead, has a 12-bp long DHU loop, as is commonly found in metazoan mitochondrial genomes [3]. A somewhat unusual feature found in trnE and trnP is the presence of much larger variable loops (20 and 19-bp long, respectively; Figure 2) than in other insects. The anticodons of C. fletcheri tRNAs (Table 1) are all identical to those of the respective tRNAs found in the other Polyneoptera (data not shown).

Bottom Line: We sequenced the complete mitochondrial genome of the free-living earwig, Challia fletcheri, compared its genomic features to other available mitochondrial sequences from polyneopterous insects.The reversal pattern of skewness is explained in terms of inversion of replication origin.All phylogenetic analyses consistently placed Dermaptera as the sister to Plecoptera, leaving them as the most basal lineage of Polyneoptera or sister to Ephemeroptera, and placed Odonata consistently as the most basal lineage of the Pterygota.

View Article: PubMed Central - PubMed

Affiliation: College of Agriculture & Life Sciences, Chonnam National University, Gwangju, Republic of Korea.

ABSTRACT
The insect order Dermaptera, belonging to Polyneoptera, includes ∼2,000 extant species, but no dermapteran mitochondrial genome has been sequenced. We sequenced the complete mitochondrial genome of the free-living earwig, Challia fletcheri, compared its genomic features to other available mitochondrial sequences from polyneopterous insects. In addition, the Dermaptera, together with the other known polyneopteran mitochondrial genome sequences (protein coding, ribosomal RNA, and transfer RNA genes), were employed to understand the phylogeny of Polyneoptera, one of the least resolved insect phylogenies, with emphasis on the placement of Dermaptera. The complete mitochondrial genome of C. fletcheri presents the following several unusual features: the longest size in insects is 20,456 bp; it harbors the largest tandem repeat units (TRU) among insects; it displays T- and G-skewness on the major strand and A- and C-skewness on the minor strand, which is a reversal of the general pattern found in most insect mitochondrial genomes, and it possesses a unique gene arrangement characterized by a series of gene translocations and/or inversions. The reversal pattern of skewness is explained in terms of inversion of replication origin. All phylogenetic analyses consistently placed Dermaptera as the sister to Plecoptera, leaving them as the most basal lineage of Polyneoptera or sister to Ephemeroptera, and placed Odonata consistently as the most basal lineage of the Pterygota.

Show MeSH
Related in: MedlinePlus