Assembly and comparative analysis of the complete multichromosomal mitochondrial genome of Cymbidium ensifolium, an orchid of high economic and ornamental value.

BACKGROUND: Orchidaceae is one of the largest groups of angiosperms, and most species have high economic value and scientific research value due to their ornamental and medicinal properties. In China, Chinese Cymbidium is a popular ornamental orchid with high economic value and a long history. However, to date, no detailed information on the mitochondrial genome of any species of Chinese Cymbidium has been published. RESULTS: Here, we present the complete assembly and annotation of the mitochondrial genome of Cymbidium ensifolium (L.) Sw. The mitogenome of C. ensifolium was 560,647 bp in length and consisted of 19 circular subgenomes ranging in size from 21,995 bp to 48,212 bp. The genome encoded 35 protein-coding genes, 36 tRNAs, 3 rRNAs, and 3405 ORFs. Repeat sequence analysis and prediction of RNA editing sites revealed a total of 915 dispersed repeats, 162 simple repeats, 45 tandem repeats, and 530 RNA editing sites. Analysis of codon usage showed a preference for codons ending in A/T. Interorganellar DNA transfer was identified in 13 of the 19 chromosomes, with plastid-derived DNA fragments representing 6.81% of the C. ensifolium mitochondrial genome. The homologous fragments of the mitochondrial genome and nuclear genome were also analysed. Comparative analysis showed that the GC content was conserved, but the size, structure, and gene content of the mitogenomes varied greatly among plants with multichromosomal mitogenome structure. Phylogenetic analysis based on the mitogenomes reflected the evolutionary and taxonomic statuses of C. ensifolium. Interestingly, compared with the mitogenomes of Cymbidium lancifolium Hook. and Cymbidium macrorhizon Lindl., the mitogenome of C. ensifolium lost 8 ribosomal protein-coding genes. CONCLUSION: In this study, we assembled and annotated the mitogenome of C. ensifolium and compared it with the mitogenomes of other Liliidae and plants with multichromosomal mitogenome structures. Our findings enrich the mitochondrial genome database of orchid plants and reveal the rapid structural evolution of Cymbidium mitochondrial genomes, highlighting the potential for mitochondrial genes to help decipher plant evolutionary history.

Mitogenomes do not substantially improve phylogenetic resolution in a young non-model adaptive radiation of freshwater gastropods.

BACKGROUND: Species flocks in ancient lakes, and particularly those arising from adaptive radiation, make up the bulk of overall taxonomic and morphological diversity in these insular ecosystems. For these mostly young species assemblages, classical mitochondrial barcoding markers have so far been key to disentangle interspecific relationships. However, with the rise and further development of next-generation sequencing (NGS) methods and mapping tools, genome-wide data have become an increasingly important source of information even for non-model groups. RESULTS: Here, we provide, for the first time, a comprehensive mitogenome dataset of freshwater gastropods endemic to Sulawesi and thus of an ancient lake invertebrate species flock in general. We applied low-coverage whole-genome sequencing for a total of 78 individuals including 27 out of the 28 Tylomelania morphospecies from the Malili lake system as well as selected representatives from Lake Poso and adjacent catchments. Our aim was to assess whether mitogenomes considerably contribute to the phylogenetic resolution within this young species flock. Interestingly, we identified a high number of variable and parsimony-informative sites across the other 'non-traditional' mitochondrial loci. However, although the overall support was very high, the topology obtained was largely congruent with previously published single-locus phylogenies. Several clades remained unresolved and a large number of species was recovered polyphyletic, indicative of both rapid diversification and mitochondrial introgression. CONCLUSIONS: This once again illustrates that, despite the higher number of characters available, mitogenomes behave like a single locus and thus can only make a limited contribution to resolving species boundaries, particularly when introgression events are involved.

The invasive land flatworm Arthurdendyus triangulatus has repeated sequences in the mitogenome, extra-long cox2 gene and paralogous nuclear rRNA clusters.

Using a combination of short- and long-reads sequencing, we were able to sequence the complete mitochondrial genome of the invasive 'New Zealand flatworm' Arthurdendyus triangulatus (Geoplanidae, Rhynchodeminae, Caenoplanini) and its two complete paralogous nuclear rRNA gene clusters. The mitogenome has a total length of 20,309 bp and contains repetitions that includes two types of tandem-repeats that could not be solved by short-reads sequencing. We also sequenced for the first time the mitogenomes of four species of Caenoplana (Caenoplanini). A maximum likelihood phylogeny associated A. triangulatus with the other Caenoplanini but Parakontikia ventrolineata and Australopacifica atrata were rejected from the Caenoplanini and associated instead with the Rhynchodemini, with Platydemus manokwari. It was found that the mitogenomes of all species of the subfamily Rhynchodeminae share several unusual structural features, including a very long cox2 gene. This is the first time that the complete paralogous rRNA clusters, which differ in length, sequence and seemingly number of copies, were obtained for a Geoplanidae.

The complete mitochondrial genome of Chibiraga houshuaii (Lepidoptera, Limacodidae) and its phylogenetic implications.

Chibiraga is a mall East Asian genus in the family Limacodidae (slug-moths). The latter includes many agricultural pests. Mitochondrial genome analysis is an important tool for studying insect molecular identification and phylogenetics. However, there are very few mitogenome sequences available for Limacodidae species, and none for the genus Chibiraga at all. To explore the mitogenome features of Chibiraga and verify its phylogenetic position, the complete mitogenome of Chibiraga houshuaii was sequenced and annotated. The complete 15,487 bp genome encoded 37 mitochondrial genes, including 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and a control region (CR). Most of the PCGs had typical ATN start codons and terminated with TAA or a single T residue. UUA (Leu2), AUU (Ile), UUU (Phe), AUA (Met) and AAU (Asn) were the five most frequently used codons. All tRNAs were folded into cloverleaf secondary structure, except for trnS1, which lacked the DHU arm. Phylogenetic analyses within the superfamily Zygaenoidea were performed based on multiple datasets from mitochondrial genes. The results showed that the families Phaudidae, Limacodidae and Zygaenidae were respectively recovered as monophyly; C. houshuaii was clustered in a clade with nettle type larvae in Limacodidae.

The Relationship between Mitochondrial Genome Mutations in Monocytes and the Development of Obesity and Coronary Heart Disease.

BACKGROUND: Metabolic disorders, including obesity, are often accompanied by an increased risk of cardiovascular complications. Monocytes are the common link between obesity and cardiovascular diseases (CVDs). The bias of innate cellular immunity towards pro-inflammatory activation stimulates the development of diseases associated with chronic inflammation, in particular metabolic disorders, including obesity, as well as CVDs. Disorders in the functional state of monocytes and activation of inflammation may be associated with mitochondrial dysfunction. Mutations accumulating in mitochondrial DNA with age may lead to mitochondrial dysfunction and may be considered a potential marker for developing chronic inflammatory diseases. METHODS: The present study aimed to study the relationship between mitochondrial heteroplasmy in CD14+ monocytes and cardiovascular risk factors in 22 patients with obesity and coronary heart disease (CHD) by comparing them to 22 healthy subjects. RESULTS: It was found that single-nucleotide variations (SNV) A11467G have a negative correlation with total cholesterol (r = -0.82, p < 0.05), low density lipoproteins (LDL) (r = -0.82, p < 0.05), with age (r = -0.57, p < 0.05) and with mean carotid intima-media thickness (cIMT) (r = -0.43, p < 0.05) and a positive correlation with HDL level (r = 0.71, p < 0.05). SNV 576insC positively correlated with body mass index (BMI) (r = 0.60, p < 0.001) and LDL level (r = 0.43, p < 0.05). SNV A1811G positively correlated with mean cIMT (r = 0.60, p < 0.05). CONCLUSIONS: It was revealed that some variants of mitochondrial DNA (mtDNA) heteroplasmy are associated with CVD risk factors. The results demonstrate the potential for using these molecular genetic markers to develop personalized CVD and metabolic disorder treatments.

The completed mitochondrial genomes of Globodera vulgaris reveals new insights into the genus Globodera phylogeny.

Due to the highly conserved structure, animal mitochondrial genome (mtDNA) is widely used in classification, evolution, phylogeny, population genetic structure and other fields. We reported on the five circle multipartite mtDNAs of a newly described species of Globodera, Globodera vulgaris (Gv) from potatoes in China. The results showed that the mtDNA of Gv was obtained through second- and third-generation sequencing, with a total length of 42,995 bp. It contained 12 protein-coding genes, two rRNA genes and 17 tRNA genes, which were distributed in different subgenomic circles. Comparison of the differences in mtDNA among Gv, G. rostochiensis, G. pallida and G. ellingtonae showed that the size and arrangement of the genes in the mtDNA of the genus Globodera were variable and not conserved. The codon usage bias of the mitochondrial protein-coding gene of Gv showed that Gv might have originated from locally and more primitive group of existing Globodera. Based on the cytochrome c oxidase subunits I genes (COX1) and the nicotinamide adenine dinucleotide dehydrogenase subunits I genes (ND1), and the results showed that Gv was clustered with Globodera spp. according to the COX1 and ND1 in scmtDNA-V, while Gv was clustered with Meloidogyne spp. according to ND1 in scmtDNA-III. The results of this study provided a new basis for understanding the multipartite structure of mtDNA as a phylogenetic and taxonomic feature of the genus Globodera. The number of subgenomic circles is a diagnostic feature of species and the arrangement order and size of mitochondrial protein-coding genes also have important application value in species identification within the genus.

High-Quality Assembly and Analysis of the Complete Mitogenomes of German Chamomile (Matricaria recutita) and Roman Chamomile (Chamaemelum nobile).

German chamomile (Matricaria chamomilla L.) and Roman chamomile (Chamaemelum nobile) are the two well-known chamomile species from the Asteraceae family. Owing to their essential oils and higher medicinal value, these have been cultivated widely across Europe, Northwest Asia, North America, and Africa. Regarding medicinal applications, German chamomile is the most commonly utilized variety and is frequently recognized as the "star among medicinal species". The insufficient availability of genomic resources may negatively impact the progression of chamomile industrialization. Chamomile's mitochondrial genome is lacking in extensive empirical research. In this study, we achieved the successful sequencing and assembly of the complete mitochondrial genome of M. chamomilla and C. nobile for the first time. An analysis was conducted on codon usage, sequence repeats within the mitochondrial genome of M. chamomilla and C. nobile. The phylogenetic analysis revealed a consistent positioning of M. chamomilla and C. nobile branches within both mitochondrial and plastid-sequence-based phylogenetic trees. Furthermore, the phylogenetic analysis also showed a close relationship between M. chamomilla and C. nobile within the clade comprising species from the Asteraceae family. The results of our analyses provide valuable resources for evolutionary research and molecular barcoding in chamomile.

The first two whole mitochondrial genomes for the genus Dactylis species: assembly and comparative genomics analysis.

BACKGROUND: Orchardgrass (Dactylis glomerata L.), a perennial forage, has the advantages of rich leaves, high yield, and good quality and is one of the most significant forage for grassland animal husbandry and ecological management in southwest China. Mitochondrial (mt) genome is one of the major genetic systems in plants. Studying the mt genome of the genus Dactylis could provide more genetic information in addition to the nuclear genome project of the genus. RESULTS: In this study, we sequenced and assembled two mitochondrial genomes of Dactylis species of D. glomerata (597, 281 bp) and D. aschersoniana (613, 769 bp), based on a combination of PacBio and Illumina. The gene content in the mitochondrial genome of D. aschersoniana is almost identical to the mitochondrial genome of D. glomerata, which contains 22-23 protein-coding genes (PCGs), 8 ribosomal RNAs (rRNAs) and 30 transfer RNAs (tRNAs), while D. glomerata lacks the gene encoding the Ribosomal protein (rps1) and D. aschersoniana contains one pseudo gene (atp8). Twenty-three introns were found among eight of the 30 protein-coding genes, and introns of three genes (nad 1, nad2, and nad5) were trans-spliced in Dactylis aschersoniana. Further, our mitochondrial genome characteristics investigation of the genus Dactylis included codon usage, sequences repeats, RNA editing and selective pressure. The results showed that a large number of short repetitive sequences existed in the mitochondrial genome of D. aschersoniana, the size variation of two mitochondrial genomes is due largely to the presence of a large number of short repetitive sequences. We also identified 52-53 large fragments that were transferred from the chloroplast genome to the mitochondrial genome, and found that the similarity was more than 70%. ML and BI methods used in phylogenetic analysis revealed that the evolutionary status of the genus Dactylis. CONCLUSIONS: Thus, this study reveals the significant rearrangements in the mt genomes of Pooideae species. The sequenced Dactylis mt genome can provide more genetic information and improve our evolutionary understanding of the mt genomes of gramineous plants.

Characterization of the complete mitochondrial genome of Paecilomyces variotii and comparative evolutionary mitochondriomics of 36 fungi.

BACKGROUD: Paecilomyces variotii has important economic value in stimulating crop growth, biodegradation, and other aspects. Up to now, there are no research reports on its mitochondrial genome. METHODS AND RESULTS: The mitochondrial genome of Paecilomyces variotii was determined with the next-generation sequencing method (Illumina, NovaSeq), and its characteristics were analyzed using various bioinformatics approaches. The length of complete mitochondrial genome sequence of P. variotii is 40,965 bp and consists of 14 protein-coding genes, 2 ribosomal RNA genes, 1 ribosomal protein S3 gene, 26 transport RNA genes. The results of phylogenetics analysis using Bayesian inference and Maximum likelihood methods showed that P. variotii belongs to the Eurotiales order in the Thermoascaceae family, and 9 genera within the Eurotiomycetes class were effectively distinguished with high support rates (bootstrap value > 92% and posterior probabilities > 99%). The analysis of synonymous substitution rates and nonsynonymous substitution rates indicated that the Ka/Ks values of the 14 PCGs in the mitochondrial genomes of the two orders in the Eurotiomycetes class ranged from 0 to 0.4333. CONCLUSIONS: This study revealed the structural and sequence information characteristics of the mitochondrial genome of P. variotii, and the phylogenetic results strongly support its classification within the family Thermoascaceae, consistent with traditional morphological taxonomy studies. The 14 PCGs in the mitochondrial genomes of the two orders in the Eurotiomycetes class are subject to strong purifying (negative) selection. The results of this research provides an important molecular basis for the development of genomics, evolutionary genetics and molecular markers of P. variotii in the future.

The first mitochondrial genome of Calophyllum soulattri Burm.f.

Calophyllum soulattri Burm.f. is traditionally used to treat skin infections and reduce rheumatic pain, yet genetic and genomic studies are still limited. Here, we present the first complete mitochondrial genome of C. soulattri. It is 378,262 bp long with 43.97% GC content, containing 55 genes (30 protein-coding, 5 rRNA, and 20 tRNA). Repeat analysis of the mitochondrial genome revealed 194 SSRs, mostly mononucleotides, and 266 pairs of dispersed repeats ( ≥ 30 bp) that were predominantly palindromic. There were 23 homologous fragments found between the mitochondrial and plastome genomes. We also predicted 345 C-to-U RNA editing sites from 30 protein-coding genes (PCGs) of the C. soulatrii mitochondrial genome. These RNA editing events created the start codon of nad1 and the stop codon of ccmFc. Most PCGs of the C. soulattri mitochondrial genome underwent negative selection, but atp4 and ccmB experienced positive selection. Phylogenetic analyses showed C. soulattri is a sister taxon of Garcinia mangostana. This study has shed light on C. soulattri's evolution and Malpighiales' phylogeny. As the first complete mitochondrial genome in Calophyllaceae, it can be used as a reference genome for other medicinal plant species within the family for future genetic studies.

Approaches and challenges in identifying, quantifying, and manipulating dynamic mitochondrial genome variations.

Mitochondria, the cellular powerhouses, possess their own unique genetic system, including replication, transcription, and translation. Studying these processes is crucial for comprehending mitochondrial disorders, energy production, and their related diseases. Over the past decades, various approaches have been applied in detecting and quantifying mitochondrial genome variations with also the purpose of manipulation of mitochondria or mitochondrial genome for therapeutics. Understanding the scope and limitations of above strategies is not only fundamental to the understanding of basic biology but also critical for exploring disease-related novel target(s), as well to develop innovative therapies. Here, this review provides an overview of different tools and techniques for accurate mitochondrial genome variations identification, quantification, and discuss novel strategies for the manipulation of mitochondria to develop innovative therapeutic interventions, through combining the insights gained from the study of mitochondrial genetics with ongoing single cell omics combined with advanced single molecular tools.

Assembly and comparative analysis of the complete mitochondrial genome of Pinellia ternata.

Pinellia ternata is an important natural medicinal herb in China. However, it is susceptible to withering when exposed to high temperatures during growth, which limits its tuber production. Mitochondria usually function in stress response. The P . ternata mitochondrial (mt) genome has yet to be explored. Therefore, we integrated PacBio and Illumina sequencing reads to assemble and annotate the mt genome of P . ternata . The circular mt genome of P . ternata is 876 608bp in length and contains 38 protein-coding genes (PCGs), 20 tRNA genes and three rRNA genes. Codon usage, sequence repeats, RNA editing and gene migration from chloroplast (cp) to mt were also examined. Phylogenetic analysis based on the mt genomes of P . ternata and 36 other taxa revealed the taxonomic and evolutionary status of P . ternata . Furthermore, we investigated the mt genome size and GC content by comparing P . ternata with the other 35 species. An evaluation of non-synonymous substitutions and synonymous substitutions indicated that most PCGs in the mt genome underwent negative selection. Our results provide comprehensive information on the P . ternata mt genome, which may facilitate future research on the high-temperature response of P . ternata and provide new molecular insights on the Araceae family.

Comparative analysis of chloroplast and mitochondrial genomes of sweet potato provides evidence of gene transfer.

The increasing number of plant mitochondrial DNA genomes (mtDNA) sequenced reveals the extent of transfer from both chloroplast DNA genomes (cpDNA) and nuclear DNA genomes (nDNA). This study created a library and assembled the chloroplast and mitochondrial genomes of the leafy sweet potato better to understand the extent of mitochondrial and chloroplast gene transfer. The full-length chloroplast genome of the leafy sweet potato (OM808940) is 161,387 bp, with 132 genes annotated, including 87 protein-coding genes, 8 rRNA genes, and 37 tRNA genes. The mitochondrial genome (OM808941) was 269,578 bp in length and contained 69 functional genes, including 39 protein-coding genes, 6 rRNA genes, and 24 tRNA genes. 68 SSR loci were found in the leafy sweet potato organelle genome, including 54 in the chloroplast genome and 14 in the mitochondria genome. In the sweet potato mitochondrial genome, most genes have RNA editing sites, and the conversion ratio from hydrophilic amino acids to hydrophobic amino acids is the highest, reaching 47.12%. Horizontal transfer occurs in the sweet potato organelle genome and nuclear genome. 40 mitochondrial genome segments share high homology with 14 chloroplast genome segments, 33 of which may be derived from chloroplast genome horizontal transfer. 171 mitochondrial genome sequences come from the horizontal transfer of nuclear genome. The phylogenetic analysis of organelle genes revealed that the leafy sweet potato was closely related to the tetraploid wild species Ipomoea tabascana and the wild diploid species Ipomoea trifida.

Comparative Mitogenome Analyses of Fifteen Ramshorn Snails and Insights into the Phylogeny of Planorbidae (Gastropoda: Hygrophila).

Ramshorn snails from the family Planorbidae are important freshwater snails due to their low trophic level, and some of them act as intermediate hosts for zoonotic trematodes. There are about 250 species from 40 genera of Planorbidae, but only 14 species from 5 genera (Anisus, Biomphalaria, Bulinus, Gyraulus, and Planorbella) have sequenced complete mitochondrial genomes (mitogenomes). In this study, we sequenced and assembled a high-quality mitogenome of a ramshorn snail, Polypylis sp. TS-2018, which represented the first mitogenome of the genus. The mitogenome of Polypylis sp. TS-2018 is 13,749 bp in length, which is shorter than that of most gastropods. It contains 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, and 2 ribosomal RNA (rRNA). We compared mitogenome characteristics, selection pressure, and gene rearrangement among all of the available mitogenomes of ramshorn snails. We found that the nonsynonymous and synonymous substitution rates (Ka/Ks) of most PCGs indicated purifying and negative selection, except for atp8 of Anisus, Biomphalaria, and Gyraulus, which indicated positive selection. We observed that transpositions and reverse transpositions occurred on 10 tRNAs and rrnS, which resulted in six gene arrangement types. We reconstructed the phylogenetic trees using the sequences of PCGs and rRNAs and strongly supported the monophyly of each genus, as well as three tribes in Planorbidae. Both the gene rearrangement and phylogenetic results suggested that Polypylis had a close relationship with Anisus and Gyraulus, while Bulinus was the sister group to all of the other genera. Our results provide useful data for further investigation of species identification, population genetics, and phylogenetics among ramshorn snails.

Characteristics and Comparative Analysis of the Special-Structure (Non-Single-Circle) Mitochondrial Genome of Capsicum pubescens Ruiz & Pav.

Chilean peppers, cultivated from Capsicum pubescens, are globally renowned as popular vegetable and spice crops. C. pubescens belongs to the Capsicum L. (pepper) family and is one of the five pepper cultivars grown in China. In this study, we assembled and annotated the complete mt genome of C. pubescens. We investigated several aspects of its genome, including characteristics, codon usage, RNA editing sites, repeat sequences, selective pressure, gene clusters, and phylogenetic relationships. Furthermore, we compared it with other plant mt genomes. The data we obtained will provide valuable information for studying evolutionary processes in the Capsicum genus and will assist in the functional analysis of Capsicum mitogenomes.

The Complete Mitochondrial Genome of Paeonia lactiflora Pall. (Saxifragales: Paeoniaceae): Evidence of Gene Transfer from Chloroplast to Mitochondrial Genome.

Paeonia lactiflora (P. lactiflora), a perennial plant renowned for its medicinal roots, provides a unique case for studying the phylogenetic relationships of species based on organelle genomes, as well as the transference of DNA across organelle genomes. In order to investigate this matter, we sequenced and characterized the mitochondrial genome (mitogenome) of P. lactiflora. Similar to the chloroplast genome (cpgenome), the mitogenome of P. lactiflora extends across 181,688 base pairs (bp). Its unique quadripartite structure results from a pair of extensive inverted repeats, each measuring 25,680 bp in length. The annotated mitogenome includes 27 protein-coding genes, 37 tRNAs, 8 rRNAs, and two pseudogenes (rpl5, rpl16). Phylogenetic analysis was performed to identify phylogenetic trees consistent with Paeonia species phylogeny in the APG Ⅳ system. Moreover, a total of 12 MTPT events were identified and 32 RNA editing sites were detected during mitogenome analysis of P. lactiflora. Our research successfully compiled and annotated the mitogenome of P. lactiflora. The study provides valuable insights regarding the taxonomic classification and molecular evolution within the Paeoniaceae family.

The First Complete Mitochondrial Genome of the Genus Litostrophus: Insights into the Rearrangement and Evolution of Mitochondrial Genomes in Diplopoda.

This study presents the complete mitochondrial genome (mitogenome) of Litostrophus scaber, which is the first mitogenome of the genus Litostrophus. The mitogenome is a circular molecule with a length of 15,081 bp. The proportion of adenine and thymine (A + T) was 69.25%. The gene ND4L used TGA as the initiation codon, while the other PCGs utilized ATN (A, T, G, C) as the initiation codons. More than half of the PCGs used T as an incomplete termination codon. The transcription direction of the L. scaber mitogenome matched Spirobolus bungii, in contrast to most millipedes. Novel rearrangements were found in the L. scaber mitogenome: trnQ -trnC and trnL1- trnP underwent short-distance translocations and the gene block rrnS-rrnL-ND1 moved to a position between ND4 and ND5, resulting in the formation of a novel gene order. The phylogenetic analysis showed that L. scaber is most closely related to S. bungii, followed by Narceus magnum. These findings enhance our understanding of the rearrangement and evolution of Diplopoda mitogenomes.

De novo assembly of the complete mitochondrial genome of Mycetophylax simplex Emery, 1888 through organelle targeting revels no substantial expansion of gene spacers, but rather some slightly shorter genes.

Mitochondria play a key role in cell biology and have their own genome, residing in a highly oxidative environment that induces faster changes than the nuclear genome. Because of this, mitochondrial markers have been exploited to reconstruct phylogenetic and phylogeographic relationships in studies of adaptation and molecular evolution. In this study, we determined the complete mitogenome of the fungus-farming ant Mycetophylax simplex (Hymenoptera, Formicidae) and conducted a comparative analysis among 29 myrmicine ant mitogenomes. Mycetophylax simplex is an endemic ant that inhabits sand dunes along the southern Atlantic coast. Specifically, the species occur in the ecosystem known as "restinga", within the Atlantic Forest biome. Due to habitat degradation, land use and decline of restinga habitats, the species is considered locally extinct in extremely urban beaches and is listed as vulnerable on the Brazilian Red List (ICMBio). We employed a mitochondrion-targeting approach to obtain the complete mitogenome through high-throughput DNA sequencing technology. This method allowed us to determine the mitogenome with high performance, coverage and low cost. The circular mitogenome has a length of 16,367 base pairs enclosing 37 genes (13 protein-coding genes, 22 tRNAs and 2 rRNAs) along with one control region (CR). All the protein-coding genes begin with a typical ATN codon and end with the canonical stop codons. All tRNAs formed the fully paired acceptor stems and fold into the typical cloverleaf-shaped secondary structures. The gene order is consistent with the shared Myrmicinae structure, and the A + T content of the majority strand is 81.51%. Long intergenic spacers were not found but some gene are slightly shorter. The phylogenetic relationships based on concatenated nucleotide and amino acid sequences of the 13 protein-coding genes, using Maximum Likelihood and Bayesian Inference methods, indicated that mitogenome sequences were useful in resolving higher-level relationship within Formicidae.

Analysis of the Rhodomyrtus tomentosa mitochondrial genome: Insights into repeat-mediated recombination and intra-cellular DNA transfer.

Plant mitochondrial genomes participate in encoding proteins crucial to the major producers of ATP in the cell and replication and heredity of their own DNA. The sequences and structure of the plant mitochondrial genomes profoundly impact these fundamental processes, and studies of plant mitochondrial genomes are needed. We reported the complete sequences of the Rhodomyrtus tomentosa mitochondrial genome here, totaling 400,482 bp. Nanopore ONT reads and PCR amplification provided evidence for recombination mediated by the eight repeat pairs for the R. tomentosa mitochondrial genome. Thirty-eight genes were identified in the R. tomentosa mitochondrial genome. Comparative analyses of the mitochondrial genome and plastome and PCR amplification suggest that five fragments of mitochondrial plastid DNA were unfunctional sequences resulting from intracellular gene transfer. Phylogenetic analysis based on each and all of the 27 mitochondrial protein-coding genes of nine Myrtales species revealed that R. tomentosa always clustered with other species of Myrtaceae. This study uncovered the enormous complexity of the R. tomentosa mitochondrial genome, the active repeat-mediated recombinations, the presence of mitochondrial plastid DNAs, and the topological incongruence of Myrtales among the single-gene trees.

Comparative mitogenomics of Brachiopods reveals conservatism in articulate species and unusualness in inarticulate species.

BACKGROUND: Brachiopods are a phylum of marine invertebrates with over 10,000 fossil species. Today, there are fewer than 500 extant species assigned to the class Articulata or Inarticulata and for which knowledge of evolutionary genetics and genomics is still poor. Until now, complete mitogenome sequences of two inarticulate species and four articulate species were available. METHODS AND RESULTS: The complete mitogenome of the inarticulate brachiopod species Lingula reevii (20,778 bp) was obtained by using next generation sequencing. It contains 12 protein-coding genes (the annotation of atp8 is unsure), two ribosomal RNA genes, 26 transfer RNA genes, and one supernumerary ORF that is also conserved in the inarticulate species Lingula anatina. It is hypothesized that this ORF could represent a Lingula-specific mtORFan gene (without obvious homology to other genes). Comparative mitogenomics indicate the mitochondrial gene order of L. reevii is unique among brachiopods, and that compared to articulate species, inarticulate species exhibit massive mitogenome rearrangements, deviant ATP8 protein sequences and supernumerary ORFs, possibly representing species- or lineage-specific mtORFan genes. CONCLUSION: The results of this study enrich genetics knowledge of extant brachiopods, which may eventually help to test hypotheses about their decline.