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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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Circular map of the mitochondrial genome of C. fletcheri.tRNAs are denoted as one-letter symbols consistent with the IUPAC/IUB single letter codes for amino acids, with L  =  trnL(CUN); L*  =  trnL(UUR); S  =  trnS(AGN); S*  =  trnS(UCN). TRU indicates the tandem repeat unit. Gene names that are not underlined indicate a clockwise transcriptional direction, whereas underlines indicate a counter-clockwise transcriptional direction. Numbers show the sizes of intergenic spacers (positive values) and overlapping region between genes (negative values). The C. fletcheri mitochondrial genome was sequenced by 2 overlapping short (SF1 and SF2) and long (LF1 and LF2) fragments, as shown in a single line within the circle.
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pone-0042056-g001: Circular map of the mitochondrial genome of C. fletcheri.tRNAs are denoted as one-letter symbols consistent with the IUPAC/IUB single letter codes for amino acids, with L  =  trnL(CUN); L*  =  trnL(UUR); S  =  trnS(AGN); S*  =  trnS(UCN). TRU indicates the tandem repeat unit. Gene names that are not underlined indicate a clockwise transcriptional direction, whereas underlines indicate a counter-clockwise transcriptional direction. Numbers show the sizes of intergenic spacers (positive values) and overlapping region between genes (negative values). The C. fletcheri mitochondrial genome was sequenced by 2 overlapping short (SF1 and SF2) and long (LF1 and LF2) fragments, as shown in a single line within the circle.

Mentions: The complete mitochondrial genome of C. fletcheri (GenBank: JN651407) is 20,456-bp in size (Figure 1; Table 1). This is the largest size among the insect mitochondrial genomes sequenced so far, although a bark weevil mitochondrial genome has been estimated to be 30–36 kb [4]. Such a long mitochondrial genome is mainly attributed to the expansions of large non-coding regions and the A+T-rich region. The C. fletcheri contains the ancestral 37 genes, 9 PCGs and 17 tRNAs encoded in the major strand, and 4 PCGs, 5 tRNAs, and 2 rRNAs encoded in the minor strand (Figure 1).


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)

Circular map of the mitochondrial genome of C. fletcheri.tRNAs are denoted as one-letter symbols consistent with the IUPAC/IUB single letter codes for amino acids, with L  =  trnL(CUN); L*  =  trnL(UUR); S  =  trnS(AGN); S*  =  trnS(UCN). TRU indicates the tandem repeat unit. Gene names that are not underlined indicate a clockwise transcriptional direction, whereas underlines indicate a counter-clockwise transcriptional direction. Numbers show the sizes of intergenic spacers (positive values) and overlapping region between genes (negative values). The C. fletcheri mitochondrial genome was sequenced by 2 overlapping short (SF1 and SF2) and long (LF1 and LF2) fragments, as shown in a single line within the circle.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0042056-g001: Circular map of the mitochondrial genome of C. fletcheri.tRNAs are denoted as one-letter symbols consistent with the IUPAC/IUB single letter codes for amino acids, with L  =  trnL(CUN); L*  =  trnL(UUR); S  =  trnS(AGN); S*  =  trnS(UCN). TRU indicates the tandem repeat unit. Gene names that are not underlined indicate a clockwise transcriptional direction, whereas underlines indicate a counter-clockwise transcriptional direction. Numbers show the sizes of intergenic spacers (positive values) and overlapping region between genes (negative values). The C. fletcheri mitochondrial genome was sequenced by 2 overlapping short (SF1 and SF2) and long (LF1 and LF2) fragments, as shown in a single line within the circle.
Mentions: The complete mitochondrial genome of C. fletcheri (GenBank: JN651407) is 20,456-bp in size (Figure 1; Table 1). This is the largest size among the insect mitochondrial genomes sequenced so far, although a bark weevil mitochondrial genome has been estimated to be 30–36 kb [4]. Such a long mitochondrial genome is mainly attributed to the expansions of large non-coding regions and the A+T-rich region. The C. fletcheri contains the ancestral 37 genes, 9 PCGs and 17 tRNAs encoded in the major strand, and 4 PCGs, 5 tRNAs, and 2 rRNAs encoded in the minor strand (Figure 1).

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