Invertebrate mitochondrial genome contains 13 protein-coding genes and major start codons for them are ATA (Met) and ATG (Met). However, alternative start codons such as ATT (Ile), ATC (Ile), TTG (Leu), and GTG (Val) also have been suggested from a diverse organism. Approximately 120 complete mitochondrial genome reported showed that the start codon for COI gene evidences an array of diverse designation of COI start codon such as typical ATN, tetranucleotide TTAG and ATAA, newly proposed AAT and AAC and so on. In the case of Lepidoptera, many completely sequenced species showed no typical start codon at the start context of COI and even within the neighboring tRNATyr. In order to clarify, we newly sequenced the beginning context of COI gene, encompassing the neighboring tRNATyr and start region of COI gene from 39 species belonging to eight lepidopteran families. We found the newly sequenced 39 species and 14 available complete lepidopteran mitochondrial genomes all possessed CGA (arginine), which is the first non-overlapping in-frame codon in COI gene. Furthermore, this CGA is highly well aligned in terms of both nucleotide and amin o acid sequences with neighboring region. Thus, the CGA (arginine) may be synapomorphic character for Lepidoptera, functionally constrained. We, therefore, propose the CGA sequence as the start codon for COI gene in lepidopteran insects.

Transferrin and ferritin are iron-binding proteins involved in transport and storage of iron as part of iron metabolism. Here, we describe the cDNA cloning and characterization of transferrin (Bi-Tf) and the ferritin heavy chain subunit (Bi-FerHCH), from the bumblebee Bombus ignitus. Bi-Tf cDNA spans 2,340 bp and encodes a protein of 706 amino acids and Bi-FerHCH cDNA spans 1,393 bp and encodes a protein of 217 amino acids. Comparative analysis revealed that Bi-Tf appears to have residues comprising iron-binding sites in the N-terminal lobe, and Bi-FerHCH contains a 5’UTR iron-responsive element and seven conserved amino acid residues associated with a ferroxidase center. The Bi-Tf and Bi-FerHCH cDNAs were expressed as 79 kDa and 27 kDa polypeptides, respectively, in baculovirus-infected insect Sf9 cells. Northern blot analysis revealed that Bi-Tf exhibits fat body-specific expression and Bi-FerHCH shows ubiquitous expression. The expression profiles of the Bi-Tf and Bi-FerHCH in the fat body of B. ignitus worker bees revealed that Bi-Tf and Bi-FerHCH are differentially induced in a time-dependent manner in a single insect by wounding, bacterial challenge, and iron overload.

Metamorphosis is a development process involving the programmed cell death of obsolete larval organs. Aspartic proteinase cathepsin D (BmCatD) is involved in the silkworm Bombyx mori metamorphosis. Here we show a novel functional role of cysteine proteinase cathepsin B during B. mori metamorphosis. The B. mori cathepsin B (BmCatB) was expressed in the fat body, epidermis, ovary, testis, and hemocyte of the larval and pupal stages. The BmCatB was ecdysoneinduced, expressed in the fat body of the molting, the final larval instar and pupal stages, and its expression led to programmed cell death. RNA interference (RNAi)-mediated BmCatB knock-down inhibited the programmed cell death of larval and pupal fat body, resulting in the arrest of larval-pupal transformation. BmCatB RNAi is up-regulated the expression of BmCatD. Based on these results we concluded that BmCatB is critically involved in the histolysis of the larval and pupal fat body, indicating that BmCatB and BmCatD are mutally regulated during silkworm metamorphosis.

We analyzed a portion of mitochondrial COI gene sequences (658 bp) to investigate the genetic diversity and geographic variation of the swallowtail butterfly, Papilioxuthus L., and the cabbage butterfly, Pieris rapae (Lepidoptera: Papilionidae). P. xuthus showed a moderate level of sequence divergence (0.91% at maximum) in 15 haplotypes, whereas P. rapae showed a moderate to high level of sequence divergence (1.67% at maximum) in 30 haplotypes, compared with other relevant studies. Analyses of population genetic structure showed that most populations are not genetically differentiated in both species. The distribution pattern of both species appears to be consistent with category IV of the phylogeographic pattern sensu Avise (Avise et al. 1987): a phylogenetic continuity, an absence of regional isolation of mtDNA clones, and extensive distribution of close clones. The observed pattern of genetic diversity and geographic variation of the two butterfly species seems to reflect the abundant habitats, abundant host plants, and flying abilities in connection with the lack of historical biogeographic barriers.

The 15,338-bp long complete mitochondrial genome (mitogenome) of the Japanese oak silkmoth, Antheraeayamamai (Lepidoptera: Saturniidae) was determined. This genome has a gene arrangement identical to those of all other sequenced lepidopteran insects, but differs from the most common type, as the result of the movement of tRNAMet to a position 5’-upstream of tRNAIle. No typical start codon of the A. yamamai COI gene is available. Instead, a tetranucleotide, TTAG, which is found at the beginning context of all sequenced lepidopteran insects was tentatively designated as the start codon for A. yamamai COI gene. Three of the 13 protein-coding genes (PCGs) harbor the incomplete termination codon, T or TA. All tRNAs formed stable stem-and-loop structures, with the exception of tRNASer(AGN), the DHU arm of which formed a simple loop as has been observed in many other metazoan mt tRNASer(AGN). The 334-bp long A+T-rich region is noteworthy in that it harbors tRNA-likestructures, as has also been seen in the A+T-rich regions of other insect mitogenomes. Phylogenetic analyses of the available species of Bombycoidea, Pyraloidea, and Tortricidea bolstered the current morphology-based hypothesis that Bombycoidea and Pyraloidea are monophyletic (Obtectomera). As has been previously suggested, Bombycidae (Bombyxmori and B.mandarina) and Saturniidae (A.yamamai and Caligula boisduvalii) formed a reciprocal monophyletic group.

We determined the complete mitochondrial genome of the yellow-spotted long horned beetle, Psacothea hilaris (Coleoptera: Cerambycidae) that is an endangered insect species in Korea. The genome was sequenced from four overlapping fragments: two short fragments and two long fragments. The 15,857-bp long P. hilaris mitochondrial genome has the gene content typical of animal mitochondrial genome: 13 protein-coding genes, 22 tRNA genes, 2 ribosomal genes, and one non-coding A+T-rich region. The gene arrangement of the molecule is identical to the most common type found among insect mitochondrial gene arrangement that is regarded as ancestral for insects. Like several other coleopteran species the P. hilaris COI gene has typical mitochondrial start codon ATT. The 1,190-bp long A+T-rich region contains 57-bp long seven identical repeat sequences and at least seven stem-and-loop structures, composed of stems with perfect matches and loops with variable size. All P. hilaris tRNAs can be folded into the typical clover-leaf structure, with the exception of tRNASer(AGN), the dihydrouridine (DHU) arm of which forms a simple loop. After more genomic and phylogenetic analyses are performed, further detailed information will be available.

In this study, we determined the complete mitochondrial genome of the jewel beetle, Chrysochroa fulgidissima (Coleoptera: Buprestidae), from four overlapping fragments. The 15,592-bp long C. fulgidissima mitogenome exhibits a gene arrangement and content identical to the most common type in insects. The start codon of the C. fulgidissima COI gene is unusual, in that no typical ATN codon is available. The 875-bp A+T-rich region is the shortest among the coleopteran mitogenomes that have thus far been sequenced in their entirety. The most unusual feature of the genome is the presence of three tRNA-like sequences within the A+T-rich region: two tRNALeu(UUR)-like sequences and one tRNAAsnlike sequence. These sequence stretches evidence the proper anticodon sequence and the potential to form secondary structures, but also harbor many mismatches in the stems. Phylogenetic analysis using a concatenation of 13 amino acid sequences of protein-coding genes among the available sequenced species of coleopteran superfamilies (Buprestoidea and Elateroidea belonging to the infraorder Elateriformnia, and Chrysomeloidea and Tenebrioroidea belonging to the infraorder Cucujoiformia) by Bayesian inference, maximum-parsimony analyses, and maximum-likelihood analysis unexpectedly revealed a lack of support for monophyletic Elateriformia.

We determined the complete mitochondrial genome (mitogenome) of the Japanese Oak Silkmoth, Antheraea yamamai (Lepidoptera: Saturniidae) from two overlapping fragments and subsequent shotgun sequencing. The 15,601-bp long A. yamamai mitogenome contains gene arrangement and content identical to the most common arrangement found in lepidopteran insects. Most individual A. yamamai mitochondrial (mt) genes were well within the range found in the respective genes of other insects, except for small ribosomal RNA (1,037 bp). The 336-bp A+T-rich region is relatively smaller than that of other lepidopteran insects. The region is interesting in that it contains tRNA-like structures as found in the A+T-rich regions of other insect mitogenomes. The start codon of A. yamamai COI gene is unusual in that no typical one (ATN) is available. Three of the 13 protein-coding genes have incomplete termination codon T or TA. All tRNA formed stable stem-and-loop structure, except for tRNASer(AGN), the DHU arm of which formed a simple loop as seen in many other metazoan mt tRNASer(AGN).

We determined the complete mitogenome of the oriental mayfly, Ephemera orientalis (Ephemeroptera: Ephemeridae) and the dragonfly Davidius lunatus (Odonata: Gomphidae). The 16,463-bp long E. orientalis and the 15,912 bp long D. lunatus mitogenome contains gene arrangement and content identical to the most common type found in a diverse insect order. Most individual E. orientalis and D. lunatus mt genes were well within the size found in the respective genes of other insects. The initiation codon for the D. lunatus COI gene was typical as ATA, whereas no typical start codon was found in the start region of E. orientalis COI gene. The A+T-rich regions of both mitogenomes have a few unusual feature. The A+T-rich region of E. orientalis contains a tandem repeat composed of two identical copies of 55 bp long, whereas that of D. lunatus contains a tandem repeat composed of duplicated identical 261-bp copies and one partial copy of the repeat. Also, the A+T-rich region of E. orientalis contains a single sequence and that of D. lunatus contains nine sequences, along with the tandem triplicate sequences, that has the potential to form stem-and-loop structures, flanked by the conserved sequences, “TA(A)TA” at the 5’ end and “G(A)nT’ at the 3’ end. Furthermore, the A+T-rich region of D. lunatus contains two tRNA-like structures, tRNALeu(UUR)-like sequence and tRNATyr-like sequence that have proper anticodon TAA and clover-leaf structure that were previously found in the hymenopteran insects.

We determined the complete mitochondrial genome (mitogenome) of the jewel beetle, Chrysochroa fulgidissima (Coleoptera: Buprestidae) from two overlapping fragments and subsequent sub fragments. The 15,592-bp long C. fulgidissima mitogenome contains gene arrangement and content identical to the most common arrangement found in insects. Most individual C. fulgidissima mitochondrial (mt) genes were well within the range found in the respective genes of other insects. The 875-bp A+T-rich region is shortest among the coleopteran mitogenomes sequenced in their entirety. The region is interesting in that it contains several stem-and-loop structures and tRNA-like structure found in the A+T-rich regions of other insect mitogenomes. As seen in other insect motogenomes the start codon of C. fulgidissima COI gene also is unusual because no typical start codon is available. Three of the 13 protein-coding genes have incomplete termination codon T or TA. All tRNA formed stable stem-and-loop structure, except for tRNASer(AGN), the DHU arm of which formed a simple loop as seen in many other metazoan mt tRNASer(AGN).

Insect nicotinic acetylcholine receptors (nAChRs) are targets for insecticides. Despite the importance of the nAChR as a major target for insecticide action, modulators of nAChRs in insects remain unidentified. Here we describe the cloning and identification of a nAChR modulator gene in an insect. This gene was isolated by searching the firefly Pyrocoelia rufa cDNA library, and the geneitself encodes a protein 120 amino acids in length, named Pr-lynx1. Pr-lynx1 shares all the features, including a cysteine-rich consensus motif and common gene structure, of the Ly-6/neurotoxin superfamily. The recombinant Pr-lynx1, which is expressed as a 12-kDa polypeptide in baculovirus-infected insect Sf9 cells, is normally present at the cell surface asa GPI-anchored protein. Northern and Western blot analyses revealed that Pr-lynx1 is expressed in various tissues, such as the ganglion, brain, mandibular muscle, proventriculus, leg muscle, and epidermis. This expression pattern is similar to the distribution of nAChRs as assayed by α3 nAChR immunoreactivity. Co-expression of Pr-lynx1 in Xenopus oocytes expressing α3β4 nAChRs results in an increase in acetylcholine-evoked macroscopic currents, indicating a functional role of Pr-lynx1 as a protein modulator for nAChRs. This study on Pr-lynx1 is the first report of a modulator of nAChRs in an insect species.

The mason bee (Osmia cornifrons Radoszkowsky) is an excellent pollinator of apple. To understand geographic genetic variation of the species and relationships among populations sequenced a portion of mitochondrial COI gene, which corresponds to “DNA Barcode” region (658 bp) from 81 individuals collected over eight localities in Korea. The sequence data were used to investigate genetic diversity within populations and species, geographic variation within species, phylogeographic relationship among populations, and phylogenetic relationship among haplotypes. Summarized, overall moderate to low genetic diversity within populations and species was characteristic, concordant with the high potential to disperse of O. cornifrons in Korea. Although two populations were genetically subdivided from the remaining localities, no clear regional bias was observed. Overall, high rate of gene flow among localities and low FST was characteristic considering other relevant studies that investigated population genetic structure of other insects occurring in Korean peninsula.