Search Results (44)

This study presents the first complete mitochondrial genome characterization of Elops machnata (Teleostei: Elopiformes: Elopidae), a basal teleost lineage critical for understanding early actinopterygian evolution. The assembled mitogenome, deposited under GenBank accession number PV294982, spans 16,712 bp and exhibits the canonical vertebrate mitochondrial gene organization, comprising 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a control region. Base composition analysis revealed 22.71% A, 17.36% C, 29.82% T, and 30.11% G, with a slight AT bias (A + T = 52.53%). Codon usage analysis of the 13 protein-coding genes identified CUA (L), CGA (R), GCC (A), and GGA (G) as the most frequent codons, with a pronounced preference for adenine at the third codon position. Amino acid composition analysis across 23 Elopomorpha species revealed consistently high leucine contents, and tRNA secondary structure prediction showed 21 tRNAs forming typical cloverleaf structures, except for trnS1(gct), which lacks the dihydrouridine (DHU) arm. Phylogenetic reconstruction using maximum likelihood and Bayesian inference methods, based on concatenated mitochondrial protein-coding genes from 23 Elopomorpha species, placed E. machnata in a well-supported clade with Elops hawaiensis, confirming their close evolutionary relationship. This study not only provides essential genomic resources for E. machnata but also resolves key gaps in the mitochondrial genome and improves phylogenetic understanding of Elopomorpha. Full article

In this study, we sequenced and characterized the complete mitochondrial genome of Acorssocheilus spinifer, an endemic stream-dwelling cyprinid species from South China first described in 2006. The mitogenome is 16,591 bp in length and contains the standard set of 37 genes (13 protein-coding genes, 22 tRNA genes, 2 rRNA genes) plus a control region. The genome exhibits typical cyprinid characteristics, with most genes encoded on the H-strand and a nucleotide composition biased toward A + T (55.9%). All tRNA genes display the typical cloverleaf secondary structure, except for tRNA^Ser (GCU), which lacks the dihydrouridine (DHU) arm. Phylogenetic analysis using complete mitogenomes from 14 Acrossocheilus species revealed that 12 species form a monophyletic assemblage with three distinct clades. Within this framework, A. spinifer clusters closely with A. beijiangensis, supporting previous morphological observations. Our findings provide valuable genetic data for further taxonomic refinement and conservation efforts for Chinese barred species of Cyprinidae. Full article

Background: The mitochondrial genome has been used for understanding higher-level phylogenetic relationships within Coccomorpha. we sequenced and analyzed the first mitochondrial genome of Xylococcus castanopsis Wu & Huang, 2017 to elucidate its genomic features and phylogenetic position. Methods: The complete mitogenome was assembled using NOVOPlasty and annotated with MITOS. We analyzed genome organization, codon usage, and tRNA structures. Phylogenetic relationships were reconstructed using 13 protein-coding genes from 19 scale insect species with Bayesian Inference and Maximum Likelihood methods. Result: The mitochondrial genome is 16,363 bp in size and contains the typical 37 mitochondrial genes, with an A + T content of 89.2%. All protein-coding genes start with the ATN and end with TAA/TAG or a single T- residue. Sixteen tRNAs exhibit the typical cloverleaf structure, while the remaining six lack either the dihydrouridine (DHU) or TΨC (T) arm. Gene rearrangements occur only in individual tRNAs and transpositions between the gene clusters trnS2-ND1 and trnL1-rrnL-trnV-rrnS. Phylogenetic analysis consistently place Xylococcidae as a sister group to all scale insects except Matsucoccidae. Conclusions: This study provides the first complete mitogenome for Xylococcidae, revealing characteristic gene rearrangements. Phylogenetic reconstruction resolves the phylogenetic position of Xylococcidae as a distinct lineage sister to all scale insects except Matsucoccidae, providing critical evolutionary insights. Full article

Satyrinae, one of the most species-rich groups within the Nymphalidae family, has traditionally relied on morphological characteristics for classification. However, this approach encounters challenges due to issues such as cryptic species and paraphyletic groups. Recent molecular phylogenetic studies have revealed the complex evolutionary history of Satyrinae, leading to the reclassification of the originally polyphyletic Satyrini into multiple independent tribes and confirming the monophyletic status of groups such as Amathusiini. Nevertheless, the phylogenetic relationships and divergence times of certain tribes remain contentious. This study focuses on three species of the Amathusiini tribe (Faunis aerope, Stichophthalma howqua, and Aemona lena), constructing a phylogenetic tree by sequencing the complete mitochondrial genome and integrating 13 protein-coding genes, including COI and ND5. The results indicate that the mitogenome lengths for the three satyrid species are 15,512 bp for Faunis aerope, 13,914 bp for Stichophthalma howqua, and 15,288 bp for Aemona lena. The genetic composition and sequencing of the newly obtained mitogenomes exhibit high conservation and are distinctive to this group of butterflies. Each of the three mitogenomes contains a characteristic collection of 37 genes along with an AT-rich region. Notably, the tRNA genes across these mitogenomes display a conventional cloverleaf configuration; however, the tRNA^Ser stem (AGN) lacks the dihydrouridine (DHU) arm. The three species exhibit varying lengths of AT-rich regions, resulting in differences in their mitochondrial genome sizes. Finally, the phylogenetic analysis supports the relationships among the four tribes of Satyrinae as: (Satyrini + (Amathusiini + Elymniini)) + Melanitini. Full article

The mitochondrial genomes of three species of Elmidae were sequenced. The sizes were 16,309 bp (C. jaechi), 16,291 bp (G. longiusculus), and 15,480 bp (S. punctulata). Each genome includes 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and a control region (CR). All three mitogenomes show AT bias. Except for trnS1, lacking the dihydrouridine (DHU) arm, all tRNA genes had a typical cloverleaf structure. The codon usage preferences of the three species showed high similarity. The arrangement of the genes in the three mitogenomes was consistent among them but differed from that in the typical mitogenomes of Coleoptera. The Ka/Ks ratio indicated that COX1 and nad4L had a lower evolutionary rate, being relatively conserved genes among 13 PCGs. The phylogenetic analysis revealed that Elmidae belongs to the superfamily Dryopoidea within the suborder Polyphaga and is monophyletic. The results preliminarily indicate that the taxonomic groups at the subfamily, tribe, and genus levels within Elmidae are ambiguous, and further revisions may be required in the future. Full article

To explore the mitogenome characteristics of Tetratomidae and the phylogenetic position of this family in Tenebrionoidea, the mitogenome of Penthe kochi Mařan, 1940 was sequenced, annotated, and analyzed. The P. kochi mitogenome is consistent with Tenebrionoidea species in gene length, genomic organization, codon usage, and secondary structures of transfer genes (tRNAs). Most protein-coding genes (PCGs) originate with a typical ATN start codon, except nad1 and nad3, which start with TTG. In total, 10 PCGs are terminated with complete stop codon TAA and TAG, while cox1, cox2, and nad 4 contain an incomplete stop codon T-. Among the 13 PCGs, nad2 (Pi = 0.282) has the most diverse nucleotide composition, and cox2 is the most conserved gene with the lowest value (Pi = 0.154). The Ka/Ks ratio of cox1 (0.076) and cox2 (0.124) has a lower value. All the tRNAs can be folded in a typical clover-leaf secondary structure, except trnS1, which lacked a dihydrouridine arm. And phylogenetic analyses were performed based on 13 PCGs using the Bayesian inference (BI) method. The results showed that the clade of Tenebrionoidea was well separated from the outgroups, and Tetratomidae and Mycetophagidae were not well resolved. Phylogenetic analyses with more mitogenome samplings are needed to resolve the phylogeny of Tenebrionoidea. Full article

Fulgoraria rupestris is a predatory marine gastropod belonging to Neogastropoda and possessing considerable taxonomic significance. However, research on this species remains limited. We acquired the complete mitochondrial genome of F. rupestris through second-generation sequencing and conducted an analysis of its genome structural features. The mitochondrial genome of F. rupestris spans a total length of 16,223 bp and encompasses 37 genes (13 protein-coding genes (PCGs), 22 transfer RNAs, and 2 ribosomal RNAs). Notably, most tRNAs exhibit the typical cloverleaf structure, but there is an absence of the Dihydrouridine (DHU) arm in the trnS1 and trnS2 genes. The A + T content is 68.67%, indicating a pronounced AT bias. Additionally, we conducted a selection pressure analysis on the mitochondrial genomes of four species within Volutidae, revealing that all PCGs are subjected to purifying selection. In comparison to other species within Neogastropoda, F. rupestris shares an identical gene arrangement. Additionally, based on mitochondrial genome sequences of the 13 PCGs from 50 species within Neogastropoda, we constructed a phylogenetic tree. The phylogenetic tree indicates F. rupestris forms a clade with species within the family Volutidae (Cymbium olla, Neptuneopsis gilchristi, and Melo melo). This study serves as a valuable reference for future research on F. rupestris, offering insights for the upcoming phylogenetic and taxonomic classification within Neogastropoda. Furthermore, the findings provide valuable information for the development of genetic resources in this context. Full article

Transfer RNA (tRNA) modifications are essential for the temperature adaptation of thermophilic and psychrophilic organisms as they control the rigidity and flexibility of transcripts. To further understand how specific tRNA modifications are adjusted to maintain functionality in response to temperature fluctuations, we investigated whether tRNA modifications represent an adaptation of bacteria to different growth temperatures (minimal, optimal, and maximal), focusing on closely related psychrophilic (P. halocryophilus and E. sibiricum), mesophilic (B. subtilis), and thermophilic (G. stearothermophilus) Bacillales. Utilizing an RNA sequencing approach combined with chemical pre-treatment of tRNA samples, we systematically profiled dihydrouridine (D), 4-thiouridine (s⁴U), 7-methyl-guanosine (m⁷G), and pseudouridine (Ψ) modifications at single-nucleotide resolution. Despite their close relationship, each bacterium exhibited a unique tRNA modification profile. Our findings revealed increased tRNA modifications in the thermophilic bacterium at its optimal growth temperature, particularly showing elevated levels of s⁴U8 and Ψ55 modifications compared to non-thermophilic bacteria, indicating a temperature-dependent regulation that may contribute to thermotolerance. Furthermore, we observed higher levels of D modifications in psychrophilic and mesophilic bacteria, indicating an adaptive strategy for cold environments by enhancing local flexibility in tRNAs. Our method demonstrated high effectiveness in identifying tRNA modifications compared to an established tool, highlighting its potential for precise tRNA profiling studies. Full article

Ants are the standout group among eusocial insects in terms of their exceptional species richness and ecological dominance. The phylogenetic relationships among the group remain elusive. Mitochondrial genome sequences, as a kind of molecular marker, have been widely utilized in the phylogenetic analysis of insects. However, the number of ant mitogenomes published is still very limited. In this study, we utilized next-generation sequencing to determine the complete mitogenome of Pachycondyla annamita (Formicidae, Ponerinae). This is the first mitogenome from the genus Pachycondyla. Two gene rearrangements were identified in the mitogenome, the transposition of trnQ and trnM and the transposition of trnV and rrnS. The secondary structures of tRNAs were predicted. The tRNA genes trnR and trnS1 lacked the dihydrouridine (DHU) arm, and the trnE lacked the TΨC (T) arm. Phylogenetic analyses of the mitochondrial protein-coding genes under maximum likelihood (ML) and Bayesian inference (BI) criteria resulted in conflicting hypotheses. BI analysis using amino acid data with the site-heterogeneous mixture model produced a tree topology congruent with previous studies. The Formicidae was subdivided into two main clades, namely the “poneroid” clade and the “formicoid” clade. A sister group relationship between Myrmicinae and Formicinae was recovered within the “formicoid” clade. Full article

In this study, we sequenced and characterized the complete mitochondrial genome (mitogenome) of Onychostoma ovale. The mitogenome of O. ovale was 16,602 bp in length with 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and a control region. The nucleotide composition of the O. ovale mitogenome was 31.47% A, 24.07% T, 15.92% G, and 28.54% C, with a higher A + T content (55.54%) than G + C content (44.46%). All PCGs began with the standard ATG codon, except for the cytochrome c oxidase subunit 1 (COX1) gene and the NADH dehydrogenase 3 (ND3) gene with GTG, while six PCGs ended with incomplete termination codons (TA or T). The Ka/Ks ratios of 13 PCGs were all less than one, indicating that they were under purifying selection. All tRNA genes were folded into the typical cloverleaf secondary structures with the exception of tRNA^Ser(AGY), whose dihydrouridine (DHU) arm was absent. The phylogenetic trees showed that Onychostoma and Acrossocheilus were classified into three clades. There was a mosaic relationship between Onychostoma and Acrossocheilus. Moreover, the phylogenetic tree analysis showed that O. rarum was the closest species to O. ovale. This study can provide a useful resource for further phylogeny and population genetic analyses of Onychostoma and Acrossocheilus. Full article

Capniidae are a family of stoneflies, also known as snow flies, who emerge in winter. The phylogeny of Capniidae is widely accepted to be based on morphological analysis. Until now, only five Capniidae mitochondrial genomes have been sequenced so far. In addition, sampling is required to determine an accurate phylogenetic association because the generic classification of this family is still controversial and needs to be investigated further. In this study, the first mitogenome of genus Isocapnia was sequenced with a length of 16,200 bp and contained 37 genes, including a control region, two rRNAs, 22 tRNAs, and 13 PCGs, respectively. Twelve PCGs originated with the common start codon ATN (ATG, ATA, or ATT), while nad5 used GTG. Eleven PCGs had TAN (TAA or TAG) as their last codon; however, cox1 and nad5 had T as their final codon due to a shortened termination codon. All tRNA genes demonstrated the cloverleaf structure, which is distinctive for metazoans excluding the tRNASer1 (AGN) that missed the dihydrouridine arm. A Phylogenetic analysis of the superfamily Nemouroidea was constructed using thirteen PCGs from 32 formerly sequenced Plecoptera species. The Bayesian inference and maximum likelihood phylogeny tree structures derived similar results across the thirteen PCGs. Our findings strongly supported Leuctridae + ((Capniidae + Taeniopterygidae) + (Nemouridae + Notonemouridae)). Ultimately, the best well-supported generic phylogenetic relationship within Capniidae is as follows; (Isocapnia + (Capnia + Zwicknia) + (Apteroperla + Mesocapnia)). These findings will enable us to better understand the evolutionary relationships within the superfamily Nemouroidea and the generic classification and mitogenome structure of the family Capniidae. Full article

The complete mitogenome of Doleschallia bisaltide was sequenced with a size of 16,389 bp. Gene orientation and arrangement in the newly sequenced mitogenome are the same as other mitogenomes in Lepidoptera. Except for trnS1(AGN), which lacks the dihydrouridine (DHC) arm, the other 21 tRNA genes all contain a typical cloverleaf structure. Ka/Ks ratio analysis of 13 protein-coding genes (PCGs) from 23 Nymphalinae species indicates that the evolutionary rate of COX1 was slowest, while that of ATP8, ND5, and ND6 was substantially high. Phylogenetic analysis revealed that Nymphalinae and Kallimini were nonmonophyletic. Trees constructed only from the nuclear DNA (nDNA) dataset had lower support than mitochondrial or combined datasets. The addition of RNA genes did not improve the phylogenetic signal, and nodal support decreased. These data provide important information for future studies into the phylogeny of Nymphalinae. Full article

In this study, the mitochondrial genome of Luperomorpha xanthodera was assembled and annotated, which is a circular DNA molecule including 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA genes (12S rRNA and 16S rRNA), and 1388 bp non-coding regions (A + T rich region), measuring 16,021 bp in length. The nucleotide composition of the mitochondrial genome is 41.3% adenine (A), 38.7% thymine (T), 8.4% guanine (G), and 11.6% cytosine (C). Most of the protein-coding genes presented a typical ATN start codon (ATA, ATT, ATC, ATG), except for ND1, which showed the start codon TTG. Three-quarters of the protein-coding genes showed the complete stop codon TAR (TAA, TAG), except the genes COI, COII, ND4, and ND5, which showed incomplete stop codons (T- or TA-). All the tRNA genes have the typical clover-leaf structure, except tRNA^Ser1 (AGN), which has a missing dihydrouridine arm (DHU). The phylogenetic results determined by both maximum likelihood and Bayesian inference methods consistently supported the monophyly of the subfamily Galerucinae and revealed that the subtribe Luperina and genus Monolepta are polyphyletic groups. Meanwhile, the classification status of the genus Luperomorpha is controversial. Full article

Torix tukubana is a poorly understood proboscidate leech species, generally an ectoparasite on amphibian species. In this study, the complete mitochondrial genome (mitogenome) of T. tukubana was sequenced using next-generation sequencing (NGS), and the essential characteristics, gene arrangement, and phylogenetic relationship were analyzed. The results showed that the T. tukubana mitogenome was 14,814 bp in length, consisting of 13 protein-coding genes (PCGs), 22 tRNAs, 2 rRNAs, and 1 control region (CR). The mitogenome composition presented a strong A + T bias (73.6%). All tRNAs had the typical clover structure except the trnS1 (TCT), whose dihydrouridine (DHU) arm was short, having only one complementary base pair. Additionally, 8 gene order patterns were identified among 25 known Hirudinea species, and T. tukubana was identical to the Hirudinea ground pattern. A phylogenetic analysis based on 13 PCGs indicated that all the studied species clustered into three main clades. The relationships among Hirudinea species were basically consistent with their gene arrangement results, but different from their morphological taxonomy. T. tukubana was in the monophyletic group of Glossiphoniidae, a finding consistent with previous research. Our results provided the essential characteristics of the T. tukubana mitogenome. As the first complete mitogenome of Torix, it could offer valuable information for a systematic understanding of the Hirudinea species. Full article

The complete mitochondrial genomes (mitogenomes) of beetles in the tribe Scolytoplatypodini (genus Scolytoplatypus) were sequenced and annotated. These included Scolytoplatypus raja (15,324 bp), Scolytoplatypus sinensis (15,394 bp), Scolytoplatypus skyliuae (15,167 bp), and Scolytoplatypus wugongshanensis (15,267 bp). The four mitogenomes contained 37 typical genes, including 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and 2 ribosomal RNA genes (rRNAs). The gene orientation and arrangement of the four mitogenomes were similar to other Coleoptera mitogenomes. PCGs mostly started with ATN and terminated with TAA. The Ka/Ks ratio of 13 PCGs in the four species revealed that cox1 had the slowest evolutionary rate and atp8 and nad6 had a higher evolutionary rate. All tRNAs had typical cloverleaf secondary structures, but trnS1 lacked dihydrouridine arm. Partial tRNAs lost the discriminator nucleotide. The trnY did not possess the discriminator nucleotide and also lost three bases, showing a special amino-acyl arm. Bayesian inference (BI) and maximum likelihood (ML) methods were conducted for phylogenetic analyses using 13 PCGs. Scolytoplatypodini was clustered with Hylurgini and Hylastini, and the monophyly of Scolytoplatypodini was supported. The four newly sequenced mitogenomes increase understanding of the evolutionary relationships of Scolytoplatypodini and other Scolytinae species. Full article