Characterization of the complete mitochondrial genomes of Cnaphalocrocis medinalis and Chilo suppressalis (Lepidoptera: Pyralidae)

The complete mitochondrial genomes (mitogenomes) of Cnaphalocrocis medinalis and Chilo suppressalis (Lepidoptera: Pyralidae) were determined and analyzed. The circular genomes were 15,388 bp long for C. medinalis and 15,395 bp long for C. suppressalis. Both mitogenomes contained 37 genes, with gene order similar to that of other lepidopterans. Notably, 12 protein-coding genes (PCGs) utilized the standard ATN, but the cox1 gene used CGA as the initiation codon; the cox1, cox2, and nad4 genes in the two mitogenomes had the truncated termination codons T, T, and TA, respectively, but the nad5 gene was found to use T as the termination codon only in the C. medinalis mitogenome. Additionally, the codon distribution and Relative Synonymous Codon Usage of the 13 PCGs in the C. medinalis mitogenome were very different from those in other pyralid moth mitogenomes. Most of the tRNA genes had typical cloverleaf secondary structures. However, the dihydrouridine (DHU) arm of the trnS1(AGN) gene did not form a stable stem-loop structure. Forty-nine helices in six domains, and 33 helices in three domains were present in the secondary structures of the rrnL and rrnS genes of the two mitogenomes, respectively. There were four major intergenic spacers, except for the A+T-rich region, spanning at least 12 bp in the two mitogenomes. The A+T-rich region contained an 'ATAGT(A)'-like motif followed by a poly-T stretch in the two mitogenomes. In addition, there were a potential stem-loop structure, a duplicated 25-bp repeat element, and a microsatellite '(TA)(13)' observed in the A+T-rich region of the C. medinalis mitogenome. A poly-T motif, a duplicated 31-bp repeat element, and a 19-bp triplication were found in the C. suppressalis mitogenome. However, there are many differences in the A+T-rich regions between the C. suppressalis mitogenome sequence in the present study and previous reports. Finally, the phylogenetic relationships of these insects were reconstructed based on amino acid sequences of mitochondrial 13 PCGs using Bayesian inference and maximum likelihood methods. These molecular-based phylogenies support the traditional morphologically based view of relationships within the Pyralidae.     

Complete mitochondrial genome of the seven-spotted lady beetle, Coccinella septempunctata (Coleoptera: Coccinellidae)

The complete mitochondrial genome (mitogenome) of the seven-spotted lady beetle, Coccinella septempunctata (Coleoptera: Coccinellidae), which is one of the best known insects capable of predation, is described with an emphasis on the noteworthy composition of the A+T-rich region. The C. septempunctata genome consists of 2 rRNAs, 22 tRNAs, 13 protein-coding genes, and 1 control region, designated as the A+T-rich region in insects. Along with an unusually long A+T-rich region (4469 bp), the 18,965-bp long C. septempunctata mitogenome was the largest in Coleoptera. The A+T-rich region is composed of a 2214-bp long non-repeat region composed of 80.17% A/T nucleotides and a 2256-bp long repeat region composed of 65.71% A/T nucleotides. The repeat region harbors 32 identical 70-bp long tandem repeats plus one 15-bp long incomplete first repeat. These repeat sequences may possibly have been caused by slipped-strand mispairing and unequal crossing-over events during DNA replication.     

The complete mitochondrial genome of the wild silkworm moth, Actias selene

The complete mitochondrial genome (mitogenome) of Actias selene (Lepidoptera: Saturniidae) was determined to be 15,236 bp, including 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and a control region. The arrangement of 13 PCGs was similar to that of other sequenced lepidopterans. The AT skew of the mitogenome of A. selene was slightly negative, indicating a higher number of T compared to A nucleotides. The nucleotide composition of the mitogenome of A. selene was also biased toward A+T nucleotides (78.91%). All PCGs were initiated by ATN codons, except for the gene encoding cytochrome c oxidase subunit 1 (cox1), which may be initiated by the TTAG, as observed in other lepidopterans. Three genes, including cox1, cox2, and nad5, had incomplete stop codons consisting of just a T. With an exception for trnS1(AGN), all the other tRNA genes displayed a typical clover-leaf structure of mitochondrial tRNA. The A+T-rich region of the mitogenome of A. selene was 339 bp in length, and contains several features common to the Lepidopteras, including non-repetitive sequences, a conserved structure combining the motif ATAGA and an 18-bp poly-T stretch and a poly-A element upstream of trnM gene. Phylogenetic analysis showed that A. selene was close to Saturniidae.     

The complete mitogenome of the Chinese bush cricket, Gampsocleis gratiosa （Orthoptera： Tettigonioidea）

The complete mitochondrial genome (mitogenome) of Gampsocleis gratiosa was determined. The 15, 929 bp in the size of G. gratiosa mitogenome contains a typical gene content, base composition, and codon usage found in metazoan. All 13 protein coding genes (PCGs) of the G. gratiosa mitogenome start with a typical ATN codon. The usual termination codons (TAA and TAG) were found from 10 PCGs. However, the atp6, nad4, and nad5 had incomplete termination codon (T). The anticodons of all tRNAs are identical to those observed in Drosophila yakuba and Locusta migratoria, and can be folded in the form of a typical clover leaf structure except for trnS (AGN). The secondary structure of trnS (AGN) was drawn according with the Steinberg-Cedergren tertiary structure. The A T content (67.4%) of the A T-rich region is relatively lower among the mitogenome regions, in contrast, it usually contains the highest A T content for most insects. Two isolated sequence repeat regions (202 bp) were found in the A T-rich region with mapping and secondary structure information.     

斑翅草螽线粒体基因组序列测定与分析

已经测定的昆虫线粒体基因组中, 直翅目草螽亚科的疑钩额螽Ruspolia dubia线粒体控制区长度最短, 仅70 bp。为此, 本研究采用L-PCR结合二次PCR扩增策略对另一种草螽亚科昆虫斑翅草螽Conocephalus maculates线粒体基因组序列进行了测定。序列注释发现: 斑翅草螽线粒体基因组序列全长15 898 bp, A+T含量为72.05%, 基因排列与典型的节肢动物线粒体基因组一致。全部蛋白质编码基因以典型的ATN作为起始密码子, 9个蛋白质编码基因具有完整的终止密码子, 其余4个以不完整的T作为终止信号。除trnS^AGN外, 其余21个tRNAs均可折叠形成典型的三叶草结构, 依照Steinberg等(1997)线粒体特殊tRNA结构类型-9, trnS^AGN的DHU臂形成一个7 nt环, 反密码子臂则长达9 bp, 含1个突起碱基, 而不是正常的5 bp。斑翅草螽与其他直翅目昆虫线粒体基因组的主要区别在于, 在trnS^UCN和nad1, nad1和trnL^CUN基因间各存在一段罕见的、大段的基因间隔序列, 长度分别为78 bp和360 bp。其中, 位于nad1和trnL^CUN之间的基因间隔序列N链可形成一个包含完整起始、终止密码子(ATT/TAA)、编码103个氨基酸的未知开放阅读框。同义密码子使用偏好与线粒体基因组编码的tRNA反密码子匹配情况无关, 但与密码子第3位点的碱基组成紧密相关; 相对密码子使用频率(relative synonymous codon usage, RSCU)大于1的密码子, 其第3位点全部是A或T。在已经测定的直翅目昆虫线粒体基因组tRNAs中, 均存在一定数量的碱基错配, 且以G-U弱配对为主, 表明G-U配对在线粒体基因组中可能是一种正常的碱基配对形式。本研究测定的斑翅草螽线粒体基因组序列, 和先前已经测定的直翅目线粒体基因组序列一起, 可以为重建直翅目的进化历史提供数据资源。     

Mitochondrial genome of the cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae) and comparison with other Lepidopterans

We present the complete sequence of the mitochondrial genome (mitogenome) of the cotton bollworm Helicoverpa armigera. The 15,347-bp mitogenome of H. armigera was arranged in the same order described for all other sequenced lepidopterans, which differs from the most common type found in insects, due to the movement of trnM to a position 5'-upstream of trnI. The gene overlap in the H. armigera mitogenome is totally 23 bp in six locations. The H. armigera mitogenome has a total of 175 bp of intergenic spacer sequences spread over 14 regions ranging in size from 1 to 45 bp. The nucleotide composition of the whole mitogenome of H. armigera is highly A+T biased, accounting for 80.97%, with a slightly positive AT skewness and negative GC skewness, indicating the occurrence of more A than T, C more than G. The protein-encoding genes have typical mitochondrial start codons, except for cox1, which contains the unusual CGA. The cox1, cox2, and nad4 genes have incomplete stop codons (T). The lrRNA and srRNA genes are 1395 and 794-bp long, respectively. All tRNAs have a typical cloverleaf structure of mitochondrial tRNAs, except for trnS1(AGN), the dihydrouridine arm of which could not form a stable stem-loop structure. The H. armigera A+T-rich region contains a conserved structure combining the motif ATAGA and a 19-bp poly-T stretch, but absence of the 9-bp poly-A element upstream of trnM.     

The complete mitochondrial genome of fall armyworm <Emphasis Type="Italic">Spodoptera frugiperda</Emphasis> (Lepidoptera:Noctuidae)

The mitochondrial genome (mitogenome) can provide important information for understanding molecular evolution and phylogenetic analyses. The complete mitogenome of Spodoptera frugiperda (Lepidoptera:Noctuidae) was determined to be 15,365 bp in length and has the typical gene order found in Noctuidae mitogenomes, it includes 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and a A+T-rich region. The nucleotide composition was biased toward A+T nucleotides (81.09 %) and the AT skew of this mitogenome was slightly positive (0.004). All PCGs were initiated by ATN codons, except for cytochrome c oxidase subunit 1 (cox1) gene which was initiated by CGA. Eight of the 13 PCGs have the incomplete termination codon, T or TA. All the tRNA genes displayed the typical clover-leaf structure of mitochondrial tRNAs, with the exception of trnS1 (AGN). The A+T-rich region was 328 bp in length and consisted of several features common to the Noctuidae insects. Phylogenetic analysis showed that the S. frugiperda was within the Noctuidae.     

The complete nucleotide sequence and gene organization of the mitochondrial genome of the bumblebee, Bombus ignitus (Hymenoptera: Apidae)

The complete 16,434-bp nucleotide sequence of the mitogenome of the bumble bee, Bombus ignitus (Hymenoptera: Apidae), was determined. The genome contains the base composition and codon usage typical of metazoan mitogenomes. An unusual feature of the B. ignitus mitogenome is the presence of five tRNA-like structures: two each of the tRNALeu(UUR)-like and tRNASer(AGN)-like sequences and one tRNAPhe-like sequence. These tRNA-like sequences have proper folding structures and anticodon sequences, but their functionality in their respective amino acid transfers remained uncertain. Among these sequences, the tRNALeu(UUR)-like sequence and the tRNASer(AGN)-like sequence are seemingly located within the A+T-rich region. This tRNASer(AGN)-like sequence is highly unusual in that its sequence homology is very high compared to the tRNAMet of other insects, including Apis mellifera, but it contains the anticodon ACT, which designates it as tRNASer(AGN). All PCG and rRNAs are conserved in positions observed most frequently in insect mitogenome structures, but the positions of the tRNAs are highly variable, presenting a new arrangement for an insect mitogenome. As a whole, the B. ignitus mitogenome contains the highest A+T content (86.9%) found in any of the complete insects mt sequences determined to date. All protein-coding sequences started with a typical ATN codon. Nine of the 13 PCGs have a complete termination codon (all TAA), but the remaining four genes terminate with the incomplete TA or T. All tRNAs have the typical clover-leaf structures of mt tRNAs, except for tRNASer(AGN), in which the DHU arm forms a simple loop. All anticodons of B. ignitus tRNAs are identical to those of A. mellifera. In the A+T-rich region, a highly conserved sequence block that was previously described in Orthoptera and Diptera was also present. The stem-and-loop structures that may play a role in the initiation of mtDNA replication were also found in this region. Phylogenetic analysis among three corbiculate tribes, represented by Melipona bicolor (Meliponini), A. mellifera (Apini), and B. ignitus (Bombini), showed the closest relationship between M. bicolor and B. ignitus.     

The complete mitochondrial genome of the sycamore lace bug Corythucha ciliata (Hemiptera: Tingidae)

The complete mitochondrial genome of the sycamore lace bug, Corythucha ciliata, was sequenced in this study. It represents the first sequenced mitogenome of family Tingidae in Heteroptera. The mitogenome of C. ciliata is 15,257 bp and contains 37 genes including 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes and a large non-coding region. Gene arrangement, nucleotide content, codon usage, and amino acid composition and asymmetry indicate a high degree of conservation with six other species of Cimicomorpha. The 13 PCGs initiated with ATN as the start codon and terminated with TAA, TA or T as stop codon. The evolutionary rate of each PCG was different, among which ATP8 showed the highest rate while ATP6 indicated the lowest rate. The 22 tRNAs genes apparently fold into a typical cloverleaf structure; however, the anticodon (TTC) of trnSer (AGN) differs from other Heteropteran insects. Secondary structure modeling of rRNA genes revealed similarity to other insects, except for two incomplete helices (H1648 and H2735) in lrRNA. The predicted secondary structure of lrRNA indicates 45 helices in six domains, whereas srRNA has 27 helices in three domains. Three potential stem–loops and two tandem repeats (–TCTAAT–) were identified in the A+T-rich region. Phylogenetic analysis indicated that C. ciliata is a sister group to other Heteroptera species based on analysis of the 13 PCGs.     

Complete mitochondrial genome of the atlas moth, Attacus atlas (Lepidoptera: Saturniidae) and the phylogenetic relationship of Saturniidae species

Mitochondrial genome (mitogenome) can provide information for genomic structure as well as for phylogenetic analysis and evolutionary biology. In this study, we present the complete mitogenome of the atlas moth, Attacus atlas (Lepidoptera: Saturniidae), a well-known silk-producing and ornamental insect with the largest wing surface area of all moths. The mitogenome of A. atlas is a circular molecule of 15,282 bp long, and its nucleotide composition shows heavily biased towards As and Ts, accounting for 79.30%. This genome comprises 13 protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs), and an A + T-rich region. It is of note that this genome exhibits a slightly positive AT skew, which is different from the other known Saturniidae species. All PCGs are initiated by ATN codons, except for COI with CGA instead. Only six PCGs use a common stop codon of TAA or TAG, whereas the remaining seven use an incomplete termination codon T or TA. All tRNAs have the typical clover-leaf structure, with an exception for tRNA^Ser(AGN). The A. atlas A + T-rich region contains non-repetitive sequences, but harbors several features common to the Bombycoidea insects. The phylogenetic relationships based on Maximum Likelihood method provide a well-supported outline of Saturniidae, which is in accordance with the traditional morphological classification and recent molecular works.     

The mitochondrial genome of the quiet-calling katydids, <Emphasis Type="Italic">Xizicus fascipes</Emphasis> (Orthoptera: Tettigoniidae: Meconematinae)

To help determine whether the typical arthropod arrangement was a synapomorphy for the whole Tettigoniidae, we sequenced the mitochondrial genome (mitogenome) of the quiet-calling katydids, Xizicus fascipes (Orthoptera: Tettigoniidae: Meconematinae). The 16,166-bp nucleotide sequences of X. fascipes mitogenome contains the typical gene content, gene order, base composition, and codon usage found in arthropod mitogenomes. As a whole, the X. fascipes mitogenome contains a lower A+T content (70.2%) found in the complete orthopteran mitogenomes determined to date. All protein-coding genes started with a typical ATN codon. Ten of the 13 protein-coding genes have a complete termination codon, but the remaining three genes (COIII, ND5 and ND4) terminate with incomplete T. All tRNAs have the typical clover-leaf structure of mitogenome tRNA, except for tRNA(Ser(AGN)), in which lengthened anticodon stem (9 bp) with a bulged nuleotide in the middle, an unusual T-stem (6 bp in constrast to the normal 5 bp), a mini DHU arm (2 bp) and no connector nucleotides. In the A+T-rich region, two (TA)n conserved blocks that were previously described in Ensifera and two 150-bp tandem repeats plus a partial copy of the composed at 61 bp of the beginning were present. Phylogenetic analysis found: i) the monophyly of Conocephalinae was interrupted by Elimaea cheni from Phaneropterinae; and ii) Meconematinae was the most basal group among these five subfamilies.     

The first mitochondrial genome for Brahmin moths (Brahmaeidae) and implications for the higher phylogeny of Bombycoidea

Bombycoidea comprises 10 families and 4723 species, and the phylogenetic relationships among families are still in debate. In this study, we have determined the complete mitochondrial genome (mitogenome) of Brahmaea porphyria. The 15,429-bp mitogenome contains a common set of 37 mitochondrial genes including 13 protein-coding genes, 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs) and an inferred control region, and shares the conserved gene rearrangement (trnM-trnI-trnQ) in most ditrysian mitogenomes. Moreover, we analysed the secondary structure for all the tRNA genes of B. porphyria and the preference of codon usage in the PCGs of B. porphyria. The putative 373-bp control region (CR) possesses three types of conserved elements, including ATAGA, Ploy-T stretch, and microsatellite-like elements. A phylogenetic analysis among available Bombycoidea mitogenomes using the concatenated 37 mitochondrial genes appears to support the hypothesis of (Sphingidae+Bombycidae)+Saturniidae and the relatively basal phylogenetic position of Brahmaeidae within Bombycoidea.     

Characterization of the complete mitochondrial genome of Diaphania pyloalis (Lepidoptera: Pyralididae)

The complete mitochondrial genome (mitogenome) of Diaphania pyloalis (Lepidoptera: Pyralididae) was determined to be 15,298 bp and has the typical gene organization of mitogenomes from lepidopteran insects. It consists of 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and an A + T-rich region. The A + T content of this mitogenome is 80.83% and the AT skew is slightly positive. All PCGs are initiated by ATN codons, except for cytochrome c oxidase subunit 1 (cox1) gene which is initiated by CGA. Only the cox2 gene has an incomplete stop codon consisting of just a T. All the tRNA genes display a typical clover-leaf structure of mitochondrial tRNA. The A + T-rich region of the mitogenome is 332 bp in length, including several common features found in lepidopteran mitogenomes. Phylogenetic analysis showed that the D. pyloalis is close to Pyralididae.     

The complete mitochondrial genome of Pardosa pusiola (Araneae,Lycosidae) and its phylogenetic implications

The mitochondrial genome (mitogenome) is useful for identification and phylogenetic analyses among arthropods, but there are no sufficient mitogenome data for wolf spiders. To enrich the mitogenome database of wolf spiders, the complete mitogenome of Pardosa pusiola was sequenced by high-throughput sequencing. It is 14,284 bp, comprising 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and a control region (CR). It represents a high bias toward A and T nucleotides with an A + T content of 76.49%. The mitogenome exhibited a negative AT skew (−0.13) and a positive GC skew (0.32). Most PCGs started with ATN codons and ended with TAA, TAG, or an incomplete T. In addition, most tRNAs had aberrant secondary structures with the absence of DHU arm or TΨC arm. Analysis performed with CREx software demonstrated that large-scale rearrangements of tRNAs were observed in the mitogenome of P. pusiola as compared with the putative ancestral mitogenome. The Bayesian inference (BI) and maximum likelihood (ML) phylogenetic trees based on the 13 PCGs of 25 spiders had the same topology, which could be presented as (Araneidae + (Agelenidae + (Dictynidae + Desidae)) + (Salticidae + (Thomisidae + (Oxyopidae + (Pisauridae + Lycosidae))))). This study offers a useful genetic resource for the taxonomy and phylogeny of spiders.     

Complete mitochondrial genome of the stonefly Cryptoperla stilifera Sivec (Plecoptera: Peltoperlidae) and the phylogeny of Polyneopteran insects

We present the complete mitogenome of a stonefly, Cryptoperla stilifera Sivec (Plecoptera; Peltoperlidae). The mitogenome was a circular molecule consisting of 15,633 nucleotides, 37 genes and a A + T-rich region. C. stilifera mitogenome was similar to Pteronarcys princeps mitogenome (Plecoptera; Pteronarcyidae). All transfer RNA genes (tRNAs) had typical cloverleaf secondary structures except for trnSer (AGN), where the stem-loop structure of the dihydrouridine (DHU) arm was missing. The A + T-rich region of C. stilifera had two stem-loops and each had two interlink. Three conserved sequence blocks (CSBs) were present in the A + T-rich regions of C. stilifera, Peltoperla tarteri and Peltoperla arcuata. Moreover, many polynucleotide stretches (Poly N, N = A, T and C) in the A + T-rich region of C. stilifera Phylogenetic relationships of Polyneopteran species were constructed based on the nucleotide sequences of 13 protein coding genes (PCGs). Both maximum likelihood (ML) and Bayesian inference (BI) analyses supported Grylloblattodea as the sister group to Plecoptera + Dermaptera and Embiidina and Phasmatodea as sister groups.     

Complete nucleotide sequence and organization of the mitogenome of the red-spotted apollo butterfly, Parnassius bremeri (Lepidoptera: Papilionidae) and comparison with other lepidopteran insects

The 15,389-bp long complete mitogenome of the endangered red-spotted apollo butterfly, Parnassius bremeri (Lepidoptera: Papilionidae) was determined in this study. The start codon for the COI gene in insects has been extensively discussed, and has long remained a matter of some controversy. Herein, we propose that the CGA (arginine) sequence functions as the start codon for the COI gene in lepidopteran insects, on the basis of complete mitogenome sequences of lepidopteran insects, including P. bremeri, as well as additional sequences of the COI start region from a diverse taxonomic range of lepidopteran species (a total of 53 species from 15 families). In our extensive search for a tRNA-like structure in the A+T-rich region, one tRNA^Trp-like sequence and one tRNA^Leu (UUR)-like sequence were detected in the P. bremeri A+T-rich region, and one or more tRNA-like structures were detected in the A+T-rich region of the majority of other sequenced lepidopteran insects, thereby indicating that such features occur frequently in the lepidopteran mitogenomes. Phylogenetic analysis using the concatenated 13 amino acid sequences and nucleotide sequences of PCGs of the four macrolepidopteran superfamilies together with the Tortricoidea and Pyraloidea resulted in the successful recovery of a monophyly of Papilionoidea and a monophyly of Bombycoidea. However, the Geometroidea were unexpectedly identified as a sister group of the Bombycoidea, rather than the Papilionoidea.     

Complete mitochondrial genome of Dacus conopsoides (Insecta: Tephritidae) with tRNA gene duplication and molecular phylogeny of Dacini tribe

To date there is only a single report on the complete mitochondrial genome of the Dacus fruit flies. We report here the whole mitogenome of Dacus conopsoides with first report of tRNA gene duplication in tephritid fruit flies determined using next-generation sequencing and discuss the molecular phylogeny of Dacini tribe. It had a total length of 15,852 bp, comprising 13 protein coding genes, 2 rRNA genes, 23 tRNA genes, and a non-coding region (A + T-rich control region). The 65-bp trnF gene was duplicated, and the 68-bp trnE gene was partially duplicated resulting in a 31-bp pseudogene. The cloverleaf structure for trnN, trnH, and trnF lacked the TΨC-loop, while trnS lacked the D-stem. The start codons for the protein coding genes included 6 ATG, 3 ATC, 2 ATA, and 1 each of ATT and TCG. Seven PCGs had TAA stop codon, two had TAG and four had incomplete T stop codon. Molecular phylogeny based on 15 mt-genes (13 PCGs +2 rRNA genes) and 30 taxa of Tephritidae indicated D. conopsoides forming a monophyletic sister group with D. longicornis supported by high bootstrap value. The lineage containing also the monophyletic genus Zeugodacus. The Dacini and Ceratitidini tribes of the subfamily Dacinae were monophyletic but the subfamilies Dacinae and Trypetinae were paraphyletic. A broader taxa sampling of the Tephritidae is needed to better elucidate the phylogenetics and systematics of the tribes and subfamilies of tephritid fruit flies.     

Characterization of the complete mitochondrial genome of Cryptotermes domesticus (Blattodea: Kalotermitidae): Genome description and phylogenetic implications

The complete mitochondrial genome of Cryptotermes domesticus (Haviland) was sequenced and annotated to study its characteristics and the phylogenetic relationship of C. domesticus to other termite species. The mitogenome of C. domesticus is a circular, close, and double-stranded molecule with a length of 15,655 bp. The sequenced mitogenome contains 37 typical genes, which are highly conserved in gene size, organization, and codon usage. Transfer RNA genes (tRNAs) also have typical secondary structures. All of the 13 protein-coding genes (PCGs) start with an ATN codon, except for nad4, which starts with GTG and terminates with the terminal codon TAA and TAG or the incomplete form T-- (cox2 and nad5). Most tRNAs have a typical cloverleaf structure, except for trnS1, in which this form is replaced by a simple loop and lacks the dihydrouridine (DHU) arm. The nucleotide diversity (Pi) and nonsynonymous (Ka)/synonymous (Ks) mutation rate ratios indicate that nad1, cox1, and cox3 are the most conserved genes, and that cox1 has the lowest rate of evolution. In addition, an 89 bp repeated sequence was found in the A + T-rich region. Phylogenetic analysis was performed using Bayesian inference (BI) and maximum likelihood (ML) methods based on 13 PCGs, and the monophyly of Kalotermitidae was supported.     

Complete nucleotide sequence and organization of the mitogenome of the silk moth Caligula boisduvalii (Lepidoptera: Saturniidae) and comparison with other lepidopteran insects

The 15,360-bp long complete mitogenome of Caligula boisduvalii possesses a gene arrangement and content identical to other completely sequenced lepidopteran mitogenomes, but different from the common arrangement found in most insect order, as the result of the movement of tRNA(Met) to a position 5'-upstream of tRNA Ile. The 330-bp A+T-rich region is apparently capable of forming a stem-and-loop structure, which harbors the conserved flanking sequences at both ends. Dissimilar to what has been seen in other sequenced lepidopteran insects, the initiation codon for C. boisduvalii COI appears to be TTG, which is a rare, but apparently possible initiation codon. The ATP8, ATP6, ND4L, and ND6 genes, which neighbor another PCG at their 3' end, all harbored potential sequences for the formation of a hairpin structure. This is suggestive of the importance of such structures for the precise cleavage of the mRNA of mature PCGs. Phylogenetic analyses of available sequenced species of Bombycoidea, Pyraloidea, and Tortricidea supported the morphology-based current hypothesis that Bombycoidea and Pyraloidea are monophyletic (Obtectomera). As previously suggested, Bombycidae (Bombyx mori and B. mandarina) and Saturniidae (Antheraea pernyi and C. boisduvalii) formed a reciprocal monophyletic group.     

The complete mitochondrial genome of grouse locust Tetrix japonica (Insecta: Orthoptera: Tetrigoidea)

We have determined the complete mitochondrial genome of a species of grouse locust, Tetrix japonica. The total length of the T. japonica mitogenome is 15,128 bp with 75.57% A+T content. It consists of 13 protein-coding, 22 transfer RNA (tRNA), and 2 ribosomal RNA (rRNA) genes, and an A+T-rich region. The A+T-rich region was located between the small rRNA and tRNA-Ile genes and is 531 bp in length.