Search Results (389)

Cleisthenes herzensteini is a commercially important demersal fish in the Northwest Pacific. However, the resource stock of this species has undergone a drastic decline due to overfishing and habitat degradation. As a representative taxon for benthic adaptation in the order Pleuronectiformes, the molecular mechanisms underlying its specialized phenotypic traits remain poorly elucidated. Furthermore, population-level studies focusing on the mitochondrial genome of Cleisthenes herzensteini are currently scarce. Given that the mitochondrial genome serves as an ideal genetic tool for deciphering species evolution and population genetics, sequencing of its mitogenome will help fill critical gaps in genetic resources and provide essential support for species conservation and phylogenetic research. In this study, we sequenced, assembled, and annotated its complete mitochondrial genome. The circular mitogenome is 17,171 bp in length and exhibits a typical A + T bias (54.04%). Repeat sequence analysis identified 35 dispersed repeats. Codon usage analysis revealed that leucine was the most frequently encoded amino acid, with CUU being the preferred codon. Several protein-coding genes possessed incomplete stop codons (T--/TA-), and a nucleotide preference for A and C was observed at the third codon position. Phylogenetic reconstruction based on mitogenomes from 23 species supported the monophyly of the order Pleuronectiformes. C. herzensteini showed the closest relationship with Dexistes rikuzenius, forming a distinct clade alongside Hippoglossoides dubius and Limanda aspera. These results provide essential genetic resources for understanding the evolution and population genetics of C. herzensteini and related flatfishes. According to the investigation, this study represents the first report on the sequencing and analysis of the complete mitochondrial genome of the Cleisthenes herzensteini. This not only fills the gap in mitochondrial genetic information for this species but also provides a reference for subsequent investigations into the phylogenetic relationships and evolutionary processes within the family Pleuronectidae. Full article

Tenthredinidae (Hymenoptera: Tenthredinoidea), the most species-rich sawfly family, features a controversial subfamily classification, particularly regarding Eriocampa Hartig, 1837, Conaspidia Konow, 1898, and their relatives. In this study, we sequenced and characterized 15 complete mitochondrial genomes from Eriocampa, Eriocampopsis Takeuchi, 1952, and Conaspidia, and reconstructed the phylogeny of Tenthredinidae using a mitogenomic dataset including 69 species from 16 subfamilies. The mitochondrial genomes of these genera exhibited genus-specific tRNA rearrangements within the IQM and ARNS1EF clusters. Phylogenetic analyses using both Maximum Likelihood and Bayesian Inference consistently recovered (Eriocampa + Eriocampopsis + Conaspidia) as a monophyletic lineage distinct from other subfamilies of Tenthredinidae. Divergence-time estimates indicate that the Eriocampa lineage diverged from other tenthredinids around the Late Cretaceous–Paleocene boundary (~70 Ma) and diversified during the Eocene. This timing coincides with the radiation of their host plants (Araliaceae, Betulaceae, and Juglandaceae). We also compared the morphology of Eriocampinae with that of other subfamilies of Tenthredinidae and summarized the diagnostic characters of Eriocampinae. Integrating morphological and mitogenomic evidence supports the recognition of Eriocampinae Rohwer, 1911 stat. nov. This study not only clarifies the phylogenetic position of these genera but also provides new insights into the coevolutionary history between sawflies and angiosperms. Full article

Mitochondrial genomes play a central role in fungal physiology and adaptation, yet their evolutionary dynamics during domestication remain poorly understood. Here, we performed a comparative mitogenomic and gene-expression analysis of three Pleurotus ostreatus dikaryotic strains differing in origin and degree of adaptation to laboratory conditions: the long-term commercial strain dkN001, the laboratory-maintained wild isolate dkF515, and the recently collected wild strain dkN009. High-throughput Illumina sequencing enabled complete assembly of circular mitochondrial genomes, revealing substantial size variation among strains, where the dkN001 strain exhibited the second smallest mitogenome reported for the genus Pleurotus. Comparative analyses showed >99% sequence identity between wild isolates and ~95% identity relative to the commercial strain. Variations in genome size among strains were associated with intron dynamics in the cox1 and rnl genes, as well as intron loss predominantly in the commercial strain dkN001, consistent with mitochondrial genome streamlining during domestication. Expression profiling of mitochondrial protein-coding genes (PCGs) under multiple culture conditions revealed conserved transcriptional responses in dkN001 and dkF515 that contrasted sharply with those of dkN009. The differences observed, which affected components of the electron transport chain, suggested shifts in energy metabolism associated with long-term laboratory maintenance. Therefore, our results demonstrate that domestication in P. ostreatus involves both structural remodelling of the mitogenome and changes in regulation of mitochondrial PCGs, highlighting the importance of mitonuclear interactions in fungal adaptation to controlled environments. Full article

Background. Eriobotrya seguinii (Lév.) Cardot ex Guillaumin (Rosaceae, Maleae) is native to China and inhabits various altitudes within the subtropical biome of the Yunnan-Guizhou Plateau. The complexity of the plant mitogenome has impeded a systematic description of this species, leading to a limited understanding of its evolutionary position. Methods. In this study, we constructed, annotated, characterized, and compared the complete E. seguinii mitogenome with previously reported Eriobotrya japonica. Results. The E. seguinii mitogenome exhibited a typical circular architecture, spanning 372,899 bp in length, with a GC content of 46%, making it the smallest and highest GC content of any known Eriobotrya species. It encodes 71 unique genes, comprising 47 protein-coding genes, 20 transfer RNA (tRNA) genes, and 4 ribosomal RNA (rRNA) genes. The genome contains rich repetitive sequences, with mononucleotides, A/T bias, and forward and palindromic repeats being the most prevalent. The predominant codons were GCU (Ala) and UAU (Tyr), with frequencies of 1.54 and 1.53, respectively. Thirteen genes (atp9, atp6, atp1, rps14, sdh4, sdh3, rps12, rnaseH, nad1, nad6, nad7, rpl16, and mttB) demonstrated high Pi values, ranging from 0.84 to 1. The evolutionary lineage of E. seguinii was explored using mitogenome data from 19 genera within the Rosaceae family, revealing that Eriobotrya species are monophyletic and closely related to E. japonica (MN481990). Conclusions. Understanding the mitogenome characteristics of E. seguinii enhances our understanding of its genesis and classification based on mitochondrial genome data. This study provides additional evidence for future research on the evolutionary relationships among species in the Rosaceae family. Full article

Sphaerodactylidae play a crucial role in ecosystems, possessing significant ecological, scientific, and conservation value. They contribute to pest control and the maintenance of ecological balance, and also provide abundant materials for research in evolutionary biology and biodiversity. To refine the phylogenetic position of Teratoscincus scincus within the Sphaerodactylidae using mitogenomic data, this study sequenced the complete mitochondrial genome of T. scincus using the Illumina NovaSeq Xplus platform, and subsequently performed assembly, annotation, and analysis. The phylogenetic relationships of T. scincus within the Sphaerodactylidae were analyzed using 13 protein-coding genes (PCGs) from the mitochondrial genome via Bayesian inference (BI) and maximum likelihood (ML) methods. The complete mitochondrial genome of T. scincus is 16,943 bp in length and consists of 13 PCGs, 22 tRNA genes, 2 rRNA genes, and 1 control region (D-loop). The base composition shows a distinct AT preference, with the highest A + T content (56.3%) found in the PCGs region. A phylogenetic tree was constructed based on the amino acid sequences of 13 PCGs from the mitochondrial genomes of nine Sphaerodactylidae species retrieved from GenBank and the newly sequenced T. scincus generated in this study. The results confirm that T. scincus belongs to the genus Teratoscincus within the family Sphaerodactylidae. Phylogenetic analysis reveals that T. scincus and Teratoscincus keyserlingii cluster into a monophyletic group, suggesting a close phylogenetic relationship. Additionally, the phylogenetic tree provides new molecular evidence for understanding the formation mechanism of Sphaerodactylidae diversity. This study not only enriches the mitochondrial genome database of Sphaerodactylidae but also lays an important foundation for subsequent research on the adaptive evolution and conservation biology of T. scincus. Full article

The dung beetle family Geotrupidae (Scarabaeoidea) plays a vital ecological role in nutrient cycling and soil health, yet the scarcity of complete mitochondrial genome (mitogenome) data has hindered phylogenetic and comparative studies within this family. Here, we sequenced, assembled, and annotated the first complete mitogenomes of Geotrupes stercorarius and Phelotrupes auratus, collected from the Qinghai–Tibetan Plateau. Comparative analysis of these two novel mitogenomes with eight existing mitogenomes revealed conserved architectural features across Geotrupidae, such as gene arrangement, tRNA secondary structures, and small intergenic spacers. Nucleotide composition was largely conserved, though marked divergence occurred at the third codon positions. Substantial structural variation was observed in non-coding regions, particularly in the control region and the nad2-trnW spacer. Evolutionary analyses indicated strong purifying selection across all protein-coding genes, with no evidence of widespread positive selection linked to high-altitude adaptation. Phylogenetic reconstruction consistently recovered the relationships (Bolboceratinae, (Lethrinae, Geotrupinae)), with Anoplotrupes and Geotrupes forming sister genera within Geotrupinae. This study provides additional mitogenomic resources and a well-supported phylogenetic framework for Geotrupidae, resolving key taxonomic uncertainties and establishing a basis for future evolutionary and ecological research. Full article

The genus Pseudobagrus represents a group of economically and ecologically significant freshwater bagrid catfishes in East Asia, yet its taxonomy remains contentious. This study employed the complete mitochondrial genomes of 15 Pseudobagrus species to clarify their phylogenetic relationships. The mitogenomes ranged from 16,526 to 16,647 bp, exhibiting a conserved gene order and significant AT bias (average A + T = 57.85%). All genomes contained 13 protein-coding genes (PCGs), 22 tRNAs, two rRNAs, and a control region. Start codons were predominantly ATG, except for COI (GTG), while stop codons varied among TAA, TAG, and incomplete T--. Codon usage bias favored NNU and NNA codons, and 12 optimal codons were identified in P. albomarginatus. The phylogenetic trees based on concatenated PCGs revealed two major clades. Clade I contained 14 species. Within this clade, P. albomarginatus, P. tenuis, and P. brevicorpus clustered together first, and then this trio grouped with P. ussuriensis. Pseudobagrus trilineatus formed the separate Clade II. These results provide a molecular foundation for species delimitation and systematic revision within Pseudobagrus, supporting the monophyly of the genus while highlighting cryptic diversity and taxonomic complexity. Full article

The family Capitellidae performs critical roles in bioturbation and sediment remediation within global marine benthic ecosystems. However, they are a taxonomically challenging group due to their simple morphology and a ‘morphological mosaic’, where traditional classificatory traits, such as thoracic chaetiger counts, appear convergently across genera. Previous multi-locus studies (using 18S, 28S, H3, and COI) first highlighted this conflict, revealing the polyphyly of major genera like Notomastus and even Leiochrides itself (based on unidentified specimens). More recently, mitogenomic studies uncovered massive gene order rearrangements and a conflicting topology but did not include Leiochrides. Critically, with no complete mitogenome reported for a formally identified Leiochrides species, its true phylogenetic position and the validity of its polyphyly remain unresolved. To address this critical gap, we sequenced and characterized the first complete mitochondrial genome from a formally identified species, Leiochrides yokjidoensis, recently described from Korean waters. The complete mitogenome was 17,933 bp in length and included the typical 13 protein-coding genes (PCGs), 2 ribosomal RNAs (rRNAs), and 22 transfer RNAs (tRNAs). Gene order (GO) analysis revealed the occurrence of gene rearrangements in Capitellidae and in its sister clade, Opheliidae. A phylogenomic analysis using the amino acid sequences of 13 PCGs from 30 species established the first robust systematic position for the genus Leiochrides (based on this formally identified species). Phylogenetic results recovered Leiochrides as a sister group to the clade comprising Mediomastus, Barantolla, Heteromastus, and Notomastus hemipodus (BS 99%). This distinct placement confirms that Leiochrides represents an independent evolutionary lineage, phylogenetically separate from the polyphyletic Notomastus complex, despite their morphological similarities. Furthermore, our analysis confirmed the polyphyly of Notomastus, with N. hemipodus clustering distinctly from other Notomastus species. Additionally, signatures of positive selection were detected in ND4, and ND5 genes, suggesting potential adaptive evolution to the subtidal environment. This placement provides a critical, high-confidence anchor point for the genus Leiochrides. It provides a reliable reference to investigate the unresolved polyphyly suggested by previous multi-locus studies and provides compelling evidence for the hypothesis that thoracic chaetiger counts are of limited value for inferring phylogenetic relationships. This study provides the foundational genomic cornerstone for Leiochrides, representing an essential first step toward resolving the systematics of this taxonomically challenging family. Full article

Deep-sea hydrothermal vent fauna is often regarded as highly endemic, although exceptions have been reported. We examined genetic connectivity across broad spatial scales within the alvinocaridid genus Rimicaris, which has undergone substantial adaptive radiation worldwide. We analyzed six Rimicaris species using three genetic markers, cytochrome c oxidase subunit I (COI), 16S ribosomal rRNA gene (16S), and histone h3 (H3), and complete mitogenomes, employing newly generated sequences combined with publicly available sequence data. A genetic tree and haplotype networks were constructed, and divergence analyses were performed. Three clades of paired Rimicaris species were identified, each made up of taxa from different oceanic regions but showing relatively low COI divergence (0.35–1.90%). In Clade I, Rimicaris chacei and Rimicaris hybisae are morphologically similar and exhibit bidirectional gene flow, implying a dispersal route between the Mid-Atlantic Ridge (MAR) and the Mid-Cayman Spreading Center (MCSC). In Clade II, Rimicaris exoculata and Rimicaris kairei are morphologically, genetically, and ecologically distinct, reflecting restricted connectivity between the MAR and the Carlsberg Ridge (CR)–Central Indian Ridge (CIR). In Clade III, Rimicaris variabilis and Rimicaris cf. variabilis differ in nutritional strategies, showing a unidirectional dispersal route from the CIR to the southwestern Pacific (SWP), but morphological data to distinguish them are currently lacking. Some Rimicaris lineages maintain connectivity across distinct oceanic regions while others still form unique regional populations. This finding highlights the need for conservation strategies that incorporate both global-scale connectivity and regional endemism, rather than treating individual vent ecosystems as a single homogeneous management unit. Full article

Butidae is a family of teleost fishes with diverse morphological and ecological adaptations, including the marbled goby (Oxyeleotris marmorata), a large species of high economic value in Southeast and East Asia. The previous mitogenomic studies on cultured populations of O. marmorata from non-native habitats have provided limited insights into genetic divergence, structural variation, and evolutionary relationships. Hence, this study presented the complete mitochondrial genome of O. marmorata from its native habitat in Indonesia, providing structural characterization, assessment of genetic diversity, and matrilineal phylogenetic analysis. The circular mitogenome was 16,525 bp, comprising 37 genes and a non-coding control region (CR). The gene organization and strand distribution were conserved among Oxyeleotris species, with 28 genes on the heavy strand and nine on the light strand, and a pronounced A+T compositional bias. The comparative analyses of O. marmorata (from both native and cultured habitats) and Oxyeleotris lineolata mitogenomes revealed minor variations in intergenic spacers, gene overlaps, protein-coding gene (PCGs) lengths, and codon usage patterns. Conversely, the nonsynonymous and synonymous substitution ratios observed in species of the family Butidae and its closest related family (Eleotridae) indicate strong purifying selection in the present dataset. Notably, the ATG was the predominant start codon, whereas the COI gene utilized GTG, and amino acid composition analysis demonstrated high frequencies of arginine, leucine, and serine. Most transfer RNAs retained the canonical cloverleaf secondary structure except for trnS1, which lacked a functional dihydrouridine arm, whereas the CR contained four conserved sequence blocks with variable nucleotide motifs and no detectable tandem repeats. The haplotype analysis of native (Indonesia) and introduced populations (China) highlighted three haplotypes with high diversity (Hd = 1.0000) and substantial nucleotide variation (π = 0.6667). The genetic divergence across 13 PCGs was gene-specific, with COI and ND5 showing the highest variation, while ND4L and ATP8 were highly conserved. The phylogenetic analyses based on concatenated 13 PCGs using both Bayesian Inference and Maximum Likelihood methods revealed that Oxyeleotris forms a monophyletic clade and is closely related to Bostrychus sinensis. In addition, the broader phylogenetic framework inferred the matrilineal relationships within the family Butidae and its closest related family, Eleotridae. This study also recommends expanding analyses to include the mitogenomes of the remaining 17 Oxyeleotris species, together with comprehensive genomic data, to further elucidate their genetic architecture, evolutionary history, and ecological adaptability across diverse aquatic ecosystems. Full article

Background: Gynostemma pentaphyllum (Thunb.) Makino is an important medicinal plant within the Cucurbitaceae family. Despite its economic and pharmacological importance, genomic resources for this species remain limited. Methods: We sequenced and assembled the complete mitochondrial genome of G. pentaphyllum. Comparative analyses were conducted to investigate the genomic structure, gene content, RNA editing events, and intracellular gene transfer (IGT) from chloroplasts. Additionally, phylogenomic relationships, synteny, and the selective pressure on mitochondrial genes were evaluated against related species within Cucurbitaceae. Results: The ~324 kb mitogenome has a multipartite architecture of six circular-mapping molecules. It encodes the typical complement of mitochondrial protein-coding genes, tRNAs, and rRNAs found in angiosperms. Extensive C-to-U RNA editing, including events that generate functional start and stop codons, points to substantial post-transcriptional regulation. We also detected multiple chloroplast-derived fragments, including several intact genes, indicating active intracellular gene transfer. Phylogenomic analyses of conserved mitochondrial genes place G. pentaphyllum firmly within Cucurbitaceae, clustering it with Thladiantha cordifolia and Momordica charantia, whereas synteny comparisons reveal pronounced structural rearrangements with respect to these close relatives. While most genes evolve under strong purifying selection, rps1, sdh3, and sdh4 show signatures of accelerated evolution; furthermore, haplotype networks based on conserved loci further corroborate the close affinity with T. cordifolia. Conclusions: This study provides the first high-resolution mitogenome resource for G. pentaphyllum and candidate mitochondrial markers for species authentication, evolutionary studies, and breeding in Gynostemma and related cucurbits. Full article

Musk deer (Moschidae), a primitive lineage within Ruminantia, are distributed across East Asia and have long been of interest in molecular phylogenetic research. The spotted forest musk deer from Huanglong (HL) Mountain in Shaanxi, China, has long been morphologically classified as Moschus moschiferus (Siberian musk deer). However, its true taxonomic status has remained uncertain due to the lack of comprehensive molecular evidence. Moreover, studies on mitochondrial genome (mitogenome) variation within Moschidae, particularly at the intraspecific level, remain limited. To date, few phylogenetic analyses of Moschidae have incorporated all available complete mitochondrial genomes from public databases. In this study, we sequenced and assembled the complete mitogenomes of two spotted musk deer individuals from Huanglong Mountain, Shaanxi, China, and identified them as M. berezovskii (forest musk deer) by phylogenetic analysis. All available complete mitochondrial genomes of Moschidae were also included in the phylogenetic reconstruction. The average complete mitogenome length of M. berezovskii distributed in HL was 16,355 bp, and comprises 13 protein-coding genes (PCGs), two ribosomal RNA genes, and 22 transfer RNA genes. Phylogenetic analysis and genetic distance indicate that the taxonomic identity of the HL Mountain population as M. berezovskii supports the monophyly of M. berezovskii and provides a robust phylogenetic framework for clarifying evolutionary relationships within the family. Full article

Background: Snipe eels (family Nemichthyidae) are a group of pelagic fishes with unique specializations; yet, species within this study are not well-studied due to a lack of molecular data. As typical mesopelagic-to-bathypelagic fishes, snipe eels exhibit extreme body elongation, reduced skeletal ossification, and highly specialized beak-like jaws that facilitate survival in deep-sea midwater environments. Methods: The complete mitochondrial genome of the deep-sea eel Nemichthys curvirostris (Anguilliformes: Nemichthyidae) was sequenced and annotated, representing the first mitogenomic resource for this species. The phylogenetic position of N. curvirostris was also explored. Results: The circular genome of N. curvirostris was determined to be 16,911 bp in length and contained 37 genes, including 13 protein-coding genes, 22 tRNAs, 2 rRNAs, and a single control region, with an overall A + T bias of 56.67%. The maximum-likelihood phylogeny inferred from concatenated mitochondrial protein-coding genes recovered a well-supported monophyletic Nemichthys clade, with N. curvirostris positioned as the sister taxon to N. scolopaceus. The genera Avocettina and Labichthys were recovered as sister taxa, and Nemichthys clustered within a broader clade alongside them. The COX1 haplotype phylogeny showed that the two public database sequences (HQ563894.1 and MN123435.1) appeared as long, isolated branches outside the main N. curvirostris lineage, with COX1 genetic distances from typical N. curvirostris haplotypes reaching 12–13%, far exceeding the expected range of intraspecific variation. Conclusions: This mitogenome provides a valuable molecular resource for phylogenetic, evolutionary, and population genetic studies of deep-sea Anguilliformes. Full article

Gymnodiptychus integrigymnatus is a small endemic fish species found in southwest China. This study aimed to investigate the phylogenetic relationships and mitogenomic characteristics of G. integrigymnatus. The complete mitochondrial genome of one individual of G. integrigymnatus was sequenced using the Illumina HiSeq X Ten sequencing platform and comprehensively characterized. The mitochondrial genome was 16,714 bp in length, including 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and a typical control region. The genome composition showed a positive A + T skew (0.029) and a negative G + C skew (−0.198). All tRNAs were predicted to form typical cloverleaf secondary structures, except for tRNA-Ser (GCT), which lacked the DHU stem. Phylogenetic reconstruction based on 13 PCGs revealed that the subfamily Schizothoracinae was not a monophyletic group. Two major clades were identified within this subfamily: one comprising primitive taxa (Percocypris, Aspiorhynchus, and Schizothorax) and the other consisting of specialized and highly specialized groups. Gymnodiptychus integrigymnatus was distinct from both its congeners and the specialized clade and was instead recovered within a highly specialized group of the Schizothoracinae subfamily. This study offers novel perspectives on the taxonomy and phylogenetic relationships within the Schizothoracinae subfamily, with a specific focus on G. integrigymnatus, thereby enhancing the understanding of the systematics and phylogeny of the Schizothoracinae subfamily. Full article

This study presents the complete assembly and analysis of the mitochondrial genome (mitogenome) of Medicago lupulina L. var. vulgaris Koch, cultivar-population VIK32, line MlS-1, which forms an effective symbiosis not only with arbuscular mycorrhiza but also with the root nodule bacteria Sinorhizobium meliloti. The assembly, generated using a hybrid sequencing approach, revealed sequences of putative horizontal origin. These include a highly conserved open reading frame (ORF), orf279, encoding a protein structurally homologous to maturase K, yet bearing remote similarity to bacterial reverse transcriptases and CRISPR-associated proteins. We also identified sequences homologous to mitovirus RNA-dependent RNA polymerases and a fragment of the chloroplast 23S ribosomal RNA (rRNA), suggesting historical gene transfers from viruses and plastids. This work establishes a foundation for investigating the role of mitochondrial genome variation in key plant’s phenotypic traits, such as the enhanced responsiveness to arbuscular mycorrhiza observed in this agronomically valuable line. Full article