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Extreme weather poses huge challenges for animals that must adapt to wide variations in environmental temperature and, in many cases, it can lead to the local extirpation of populations or even the extinction of an entire species. Previous studies have found that one element of amphibian adaptation to environmental stress involves changes in mitochondrial gene expression at low temperatures. However, to date, comparative studies of gene expression in organisms living at extreme temperatures have focused mainly on nuclear genes. This study sequenced the complete mitochondrial genomes of five Asian hylid frog species: Dryophytes japonicus , D. immaculata , Hyla annectans , H. chinensis and H. zhaopingensis . It compared the phylogenetic relationships within the Hylidae family and explored the association between mitochondrial gene expression and evolutionary adaptations to cold stress. The present results showed that in D. immaculata , transcript levels of 12 out of 13 mitochondria genes were significantly reduced under cold exposure ( p < 0.05); hence, we put forward the conjecture that D . immaculata adapts by entering a hibernation state at low temperature. In H. annectans , the transcripts of 10 genes ( ND1 , ND2 , ND3 , ND4 , ND4L , ND5 , ND6 , COX1 , COX2 and ATP8 ) were significantly reduced in response to cold exposure, and five mitochondrial genes in H. chinensis ( ND1 , ND2 , ND3 , ND4L and ATP6 ) also showed significantly reduced expression and transcript levels under cold conditions. By contrast, transcript levels of ND2 and ATP6 in H . zhaopingensis were significantly increased at low temperatures, possibly related to the narrow distribution of this species primarily at low latitudes. Indeed, H. zhaopingensis has little ability to adapt to low temperature (4 °C), or maybe to enter into hibernation, and it shows metabolic disorder in the cold. The present study demonstrates that the regulatory trend of mitochondrial gene expression in amphibians is correlated with their ability to adapt to variable climates in extreme environments. These results can predict which species are more likely to undergo extirpation or extinction with climate change and, thereby, provide new ideas for the study of species extinction in highly variable winter climates.

Potamanthidae belongs to the superfamily Ephemeroidea but has no complete mt genome released in the NCBI (except for two unchecked and one partial mt genome). Since the sister clade to Potamanthidae has always been controversial, we sequenced seven mt genomes of Potamanthidae (two species from Rhoenanthus and five species from Potamanthus ) in order to rebuild the phylogenetic relationships of Potamanthidae in this study. The divergence time of Potamanthidae was also investigated by utilizing five fossil calibration points because of the indeterminate origin time. In addition, because Rhoenanthus coreanus and Potamanthus luteus are always in low-temperature environments, we aimed to explore whether these two species were under positive selection at the mt genome level. Amongst the 13 PCGs, CGA was used as the start codon in COX1, whereas other genes conformed to initiating with an ATN start codon. From this analysis, UUA (L), AUU (I), and UUU (F) had the highest usage. Furthermore, the DHU arm was absent in the secondary structure of S1 in all species. By combining the 13 PCGs and 2 rRNAs, we reconstructed the phylogenetic relationship of Potamanthidae within Ephemeroptera. The monophyly of Potamanthidae and the monophyly of Rhoenanthus and Potamanthus were supported in the results. The phylogenetic relationship of Potamanthidae + (Ephemeridae + Polymitarcyidae) was also recovered with a high prior probability. The divergence times of Potamanthidae were traced to be 90.44 Mya (95% HPD, 62.80-121.74 Mya), and the divergence times of Rhoenanthus and Potamanthus originated at approximately 64.77 Mya (95% HPD, 43.82-88.68 Mya), thus belonging to the late Pliocene Epoch or early Miocene Epoch. In addition, the data indicated that R. coreanus was under negative selection and that ATP8 and ND2 in Potamanthidae had a high evolutionary rate.

The 3d transition metal-catalyzed enantioconvergent radical cross-coupling provides a powerful tool for chiral molecule synthesis. In the classic mechanism, the bond formation relies on the interaction between nucleophile-sequestered metal complexes and radicals, limiting the nucleophile scope to sterically uncongested ones. The coupling of sterically congested nucleophiles poses a significant challenge due to difficulties in transmetalation, restricting the reaction generality. Here, we describe a probable outer-sphere nucleophilic attack mechanism that circumvents the challenging transmetalation associated with sterically congested nucleophiles. This strategy enables a general copper-catalyzed enantioconvergent radical N -alkylation of aromatic amines with secondary/tertiary alkyl halides and exhibits catalyst-controlled stereoselectivity. It accommodates diverse aromatic amines, especially bulky secondary and primary ones to deliver value-added chiral amines (>110 examples). It is expected to inspire the coupling of more nucleophiles, particularly challenging sterically congested ones, and accelerate reaction generality.

Lamiinae is the largest subfamily of the Cerambycidae (longhorn beetles), with approximately 21,863 described species. Previous phylogenetic studies of Lamiinae showed that this subfamily was monophyletic, but the relationship between the tribes of Lamiinae is still controversial. Partial molecular data and species morphological characteristics are not sufficient to resolve species phylogenetic studies perfectly. At the same time, the full mitochondrial genome contains more comprehensive genetic data. Benefiting from the development of next-generation sequencing (NGS), mitochondrial genomes can be easily acquired and used as reliable molecular markers to investigate phylogenetic relationships within Cerambycidae. Using NGS technology, we obtained 11 mitochondrial genome sequences of Lamiinae species. Based on this newly generated mitochondrial genome dataset matrix, we reconstructed the phylogeny of Lamiinae. The Bayesian Inference and Maximum Likelihood analyses strongly support the monophyly of four tribes (Lamiini, Batocerini, Mesosini, and Saperdini), whereas the tribe Acanthocinini was identified as paraphyletic. Other mitochondrial structural features were also observed: the start codon in the nad1 gene of all 11 mitochondrial genomes is TTG; 17-22 bp intergenic spacers (IGS) with a 'TACTA' motif were found between trnS2 and nad1. Moreover, two long IGS were found in Mesosa myops and Batocera sp. Tandem repeats were found in the IGS of Batocera sp.

Unusual climates can lead to extreme temperatures. Fejervarya kawamurai , one of the most prevalent anurans in the paddy fields of tropical and subtropical regions in Asia, is sensitive to climate change. The present study focuses primarily on a single question: how do the 13 mitochondrial protein-coding genes (PCGs) respond to extreme temperature change compared with 25 °C controls? Thirty-eight genes including an extra tRNA-Met gene were identified and sequenced from the mitochondrial genome of F. kawamurai . Evolutionary relationships were assessed within the Dicroglossidae and showed that Dicroglossinae is monophyletic and F. kawamurai is a sister group to the clade of ( F. multistriata + F. limnocharis ). Transcript levels of mitochondrial genes in liver were also evaluated to assess responses to 24 h exposure to low (2 °C and 4 °C) or high (40 °C) temperatures. Under 2 °C, seven genes showed significant changes in liver transcript levels, among which transcript levels of ATP8 , ND1 , ND2 , ND3 , ND4 , and Cytb increased, respectively, and ND5 decreased. However, exposure to 4 °C for 24 h was very different in that the expressions of ten mitochondrial protein-coding genes, except ND1 , ND3, and Cytb , were significantly downregulated. Among them, the transcript level of ND5 was most significantly downregulated, decreasing by 0.28-fold. Exposure to a hot environment at 40 °C for 24 h resulted in a marked difference in transcript responses with strong upregulation of eight genes, ranging from a 1.52-fold increase in ND4L to a 2.18-fold rise in Cytb transcript levels, although COI and ND5 were reduced to 0.56 and 0.67, respectively, compared with the controls. Overall, these results suggest that at 4 °C, F. kawamurai appears to have entered a hypometabolic state of hibernation, whereas its mitochondrial oxidative phosphorylation was affected at both 2 °C and 40 °C. The majority of mitochondrial PCGs exhibited substantial changes at all three temperatures, indicating that frogs such as F. kawamurai that inhabit tropical or subtropical regions are susceptible to ambient temperature changes and can quickly employ compensating adjustments to proteins involved in the mitochondrial electron transport chain.

In prior research on the mitochondrial genome (mitogenome) of Polypedates megacephalus , the one copy of ND5 gene was translocated to the control region (CR) and the ATP8 gene was not found. Gene loss is uncommon among vertebrates. However, in this study, we resequenced the mitogenomes of P. megacephalus from different regions using a "primer bridging" approach with Sanger sequencing technologies, which revealed the "missing" ATP8 gene in P. megacephalus as well as three other previously published Polypedates . The mitogenome of this species was found to contain two copies of the ND5 genes and three copies of the control regions. Furthermore, multiple tandem repeats were identified in the control regions. Notably, we observed that there was no correlation between genetic divergence and geographic distance. However, using the mitogenome, gene expression analysis was performed via RT-qPCR of liver samples and it was thus determined that COIII , ND2 , ND4 , and ND6 were reduced to 0.64 ± 0.24, 0.55 ± 0.34, 0.44 ± 0.21 and 0.65 ± 0.17, respectively, under low-temperature stress (8 °C) as compared with controls ( p < 0.05). Remarkably, the transcript of long non-coding RNA (lncRNA) between positions 8029 and 8612 decreased significantly with exposure to low-temperature stress (8 °C). Antisense ND6 gene expression showed a downward trend, but this was not significant. These results reveal that modulations of protein-coding mitochondrial genes and lncRNAs of P. megacephalus play a crucial role in the molecular response to cold stress.

The mitochondrial genome (mitogenome) plays an important role in phylogenetic studies of many species. The mitogenomes of many praying mantis groups have been well-studied, but mitogenomes of special mimic praying mantises, especially Acanthopoidea and Galinthiadoidea species, are still sorely lacking in the NCBI database. The present study analyzes five mitogenomes from four species of Acanthopoidea (Angela sp., Callibia diana, Coptopteryx sp., Raptrix fusca) and one of Galinthiadoidea (Galinthias amoena) that were sequenced by the primer-walking method. Among Angela sp. and Coptopteryx sp., three gene rearrangements were detected in ND3-A-R-N-S-E-F and COX1-L2-COX2 gene regions, two of which were novel. In addition, individual tandem repeats were found in control regions of four mitogenomes (Angela sp., C. diana, Coptopteryx sp., G. amoena). For those, plausible explanations were derived from the tandem duplication-random loss (TDRL) model and the slipped-strand mispairing model. One potential motif was found in Acanthopidae that was seen as a synapomorphy. Several conserved block sequences (CBSs) were detected within Acanthopoidea that paved the way for the design of specific primers. Via BI and ML analysis, based on four datasets (PCG12, PCG12R, PCG123, PCG123R), the merged phylogenetic tree within Mantodea was reconstructed. This showed that the monophyly of Acanthopoidea was supported and that the PCG12R dataset was the most suitable for reconstructing the phylogenetic tree within Mantodea., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

The enantioconvergent C(sp 3 )-N cross-coupling of racemic alkyl halides with (hetero)aromatic amines represents an ideal means to afford enantioenriched N -alkyl (hetero)aromatic amines yet has remained unexplored due to the catalyst poisoning specifically for strong-coordinating heteroaromatic amines. Here, we demonstrate a copper-catalyzed enantioconvergent radical C(sp 3 )-N cross-coupling of activated racemic alkyl halides with (hetero)aromatic amines under ambient conditions. The key to success is the judicious selection of appropriate multidentate anionic ligands through readily fine-tuning both electronic and steric properties for the formation of a stable and rigid chelating Cu complex. Thus, this kind of ligand could not only enhance the reducing capability of a copper catalyst to provide an enantioconvergent radical pathway but also avoid the coordination with other coordinating heteroatoms, thereby overcoming catalyst poisoning and/or chiral ligand displacement. This protocol covers a wide range of coupling partners (89 examples for activated racemic secondary/tertiary alkyl bromides/chlorides and (hetero)aromatic amines) with high functional group compatibility. When allied with follow-up transformations, it provides a highly flexible platform to access synthetically useful enantioenriched amine building blocks.

Chiral amines are commonly used in the pharmaceutical and agrochemical industries 1 . The strong demand for unnatural chiral amines has driven the development of catalytic asymmetric methods 1,2 . Although the N-alkylation of aliphatic amines with alkyl halides has been widely adopted for over 100 years, catalyst poisoning and unfettered reactivity have been preventing the development of a catalyst-controlled enantioselective version 3-5 . Here we report the use of chiral tridentate anionic ligands to enable the copper-catalysed chemoselective and enantioconvergent N-alkylation of aliphatic amines with α-carbonyl alkyl chlorides. This method can directly convert feedstock chemicals, including ammonia and pharmaceutically relevant amines, into unnatural chiral α-amino amides under mild and robust conditions. Excellent enantioselectivity and functional-group tolerance were observed. The power of the method is demonstrated in a number of complex settings, including late-stage functionalization and in the expedited synthesis of diverse amine drug molecules. The current method indicates that multidentate anionic ligands are a general solution for overcoming transition-metal-catalyst poisoning., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Hyla sanchiangensis (Anura: Hylidae) is endemic to China and is distributed across Anhui, Zhejiang, Fujian, Guangdong, Guangxi, Hunan, and Guizhou provinces. The mitogenomes of H. sanchiangensis from two different sites (Jinxiu, Guangxi, and Wencheng, Zhejiang) were sequenced. Phylogenetic analyses were conducted, including 38 mitogenomes of Hylidae from the NCBI database, and assessed the phylogenetic relationship of H. sanchiangensis within the analyzed dataset. Two mitogenomes of H. sanchiangensis showed the typical mitochondrial gene arrangement with 13 protein-coding genes (PCGs), two ribosomal RNA genes (12S rRNA and 16S rRNA), 22 transfer RNA (tRNA) genes, and one non-coding control region (D-loop). The lengths of the 12S rRNA and 16S rRNA genes from both samples (Jinxiu and Wencheng) were 933 bp and 1604 bp, respectively. The genetic distance ( p -distance transformed into percent) on the basis of the mitogenomes (excluding the control region) of the two samples was calculated as 4.4%. Hyla sanchiangensis showed a close phylogenetic relationship with the clade of ( H. annectans + H. tsinlingensis ), which was supported by ML and BI analyses. In the branch-site model, five positive selection sites were found in the clade of Hyla and Dryophytes : Cytb protein (at position 316), ND3 protein (at position 85), and ND5 protein (at position 400) have one site, respectively, and two sites in ND4 protein (at positions 47 and 200). Based on the results, we hypothesized that the positive selection of Hyla and Dryophytes was due to their experience of cold stress in historical events, but more evidence is needed to support this conclusion.

In this study, the mitochondrial (mt) genomes of Siphluriscus chinensis (Ephemeroptera: Siphluriscidae) were evaluated in specimens collected from two sites in China: Niutou Mountain, Zhejiang Province ( S. chinensis NTS) and Leigong Mountain, Guizhou Province ( S. chinensis LGS) and were successfully sequenced. The lengths of the mt genomes of S. chinensis NTS and S. chinensis LGS were 15,904 bp (ON729390) and 15,212 bp (ON729391), respectively. However, an in-depth comparison of the two mt genomes showed significant differences between the specimens collected from the two sites. A detailed analysis of the genetic distance between S. chinensis NTS and S. chinensis LGS was undertaken to further achieve an accurate delimitation of S. chinensis . The genetic distance between S. chinensis NTS and the other three species within Siphluriscidae was a high value, above 12.2%. The two mt genomes were used to reconstruct phylogenetic relationships and estimate divergence time. The results demonstrated robust differences between S. chinensis NTS and S. chinensis LGS, which revealed that a kind of cryptic species existed. Maximum likelihood (ML) and Bayesian inference (BI) analyses produced well-supported phylogenetic trees that showed evolutionary relationships between Siphluriscidae ((( S. chinensis HQ875717 + S. chinensis MF352165) + S. chinensis LGS) + S. chinensis NTS). The most recent common ancestor (MRCA) of four species within Siphluriscidae began to diversify during the Neogene [11.80 million years ago (Mya); 95% highest posterior densities (HPD) = 6.17-19.28 Mya], and S. chinensis NTS was first to diverge from the branches of S. chinensis LGS. In short, based on mitochondrial genomes, our results showed that the specimens collected from Leigong Mountain, Guizhou Province ( S. chinensis LGS) belonged to S. chinensis , and the specimens collected from Niutou Mountain, Zhejiang Province ( S. chinensis NTS) were a cryptic species of S. chinensis .

In order to adapt to diverse habitats, organisms often evolve corresponding adaptive mechanisms to cope with their survival needs. The species-rich family of Scincidae contains both limbed and limbless species, which differ fundamentally in their locomotor demands, such as relying on the movement of limbs or only body swing to move. Locomotion requires energy, and different types of locomotion have their own energy requirements. Mitochondria are the energy factories of living things, which provide a lot of energy for various physiological activities of organisms. Therefore, mitochondrial genomes could be tools to explore whether the limb loss of skinks are selected by adaptive evolution. Isopachys gyldenstolpei is a typical limbless skink. Here, we report the complete mitochondrial genomes of I . gyldenstolpei , Sphenomorphus indicus, and Tropidophorus hainanus . The latter two species were included as limbed comparator species to the limbless I. gyldenstolpei . The results showed that the full lengths of the mitochondrial genomes of I . gyldenstolpei , S . indicus , and T. hainanus were 17,210, 16,944, and 17,001 bp, respectively. Three mitochondrial genomes have typical circular double-stranded structures similar to other reptiles, including 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs, and the control region. Three mitochondrial genomes obtained in this study were combined with fifteen mitochondrially complete genomes of Scincidae in the NCBI database; the phylogenetic relationship between limbless I . gyldenstolpei and limbed skinks ( S . indicus and T . hainanus ) is discussed. Through BI and ML trees, Sphenomorphinae and Mabuyinae were monophyletic, while the paraphyly of Scincinae was also recovered. The limbless skink I . gyldenstolpei is closer to the species of Tropidophorus, which has formed a sister group with ( T . hainanus + T . hangman) . In the mitochondrial genome adaptations between limbless I. gyldenstolpei and limbed skinks, one positively selected site was found in the branch-site model analysis, which was located in ND2 (at position 28, BEB value = 0.907). Through analyzing the protein structure and function of the selected site, we found it was distributed in mitochondrial protein complex I. Positive selection of some mitochondrial genes in limbless skinks may be related to the requirement of energy to fit in their locomotion. Further research is still needed to confirm this conclusion though.

Catalytic enantioselective hydroxylation of prochiral dihydrosilanes with water is expected to be a highly efficient way to access Si-chiral silanols, yet has remained unknown up to date. Herein, we describe a strategy for realizing this reaction: using an alkyl bromide as a single-electron transfer (SET) oxidant for invoking Cu II species and chiral multidentate anionic N,N,P-ligands for effective enantiocontrol. The reaction readily provides a broad range of Si-chiral silanols with high enantioselectivity and excellent functional group compatibility. In addition, we manifest the synthetic potential by establishing two synthetic schemes for transforming the obtained products into Si-chiral compounds with high structural diversity. Our preliminary mechanistic studies support a mechanism involving SET for recruiting chiral Cu II species as the active catalyst and its subsequent σ-metathesis with dihydrosilanes., (© 2022 Wiley-VCH GmbH.)

Based on morphological characteristics to make species identification, the cryptic species of the Scutigeromorpha can be greatly underestimated. The mitochondrial genome provides a desirable tool for the biological identifications and the discovery of the cryptic species. The capacity to acquire mitochondrial genome sequences has substantially improved in recent years using next-generation sequencing (NGS) technology. On the basis of the next-generation sequencing, we obtained four complete mitochondrial genomes of Thereuonema tuberculata (Wood, 1862) from Nanyang, Henan Province (NY), Nanchang, Jiangxi Province (NC), Jinan, Shandong Province (JN), and Dali, Yunnan Province (DL) in China with GenBank numbers OK513221, OL449685, ON058988 and ON058989, respectively. The lengths of the four mitochondrial genomes ranged from 14,903 to 14,909 bp. The composition and order of genes of the four mitochondrial genomes were identical to the published mitochondrial genome of Scutigera coleoptrata (Linnaeus, 1758) (Scutigeromorpha: Scutigerdae). It was the first time that the tandem repeats in the control region were detected in Scutigeromorpha. We also calculated the corrected pairwise genetic distance of four complete mitochondrial genomes of T. tuberculata , ranging from 7.7 to 15.2%. The results showed that the T. tuberculata NC belonged to the typical sample of T. tuberculata , and T. tuberculata DL was hypothesized as a cryptic species of T. tuberculata . Meanwhile, T. tuberculata NY and T. tuberculata JN were hypothesized as potential cryptic species of T. tuberculata in this study. In both BI and ML trees, the monophyly of Scutigeromorpha, Scolopendromorpha, Geophilomorpha, and Lithobiomorpha was forcefully advocated. Moreover, Scutigeromorpha was recovered as the sister clade of (Scolopendromorpha + (Lithobiomorpha + Geophilomorpha)). Four specimens of T . tuberculata were clustered into one clade, which was the sister to the clade of S. coleoptrata .

Long non-coding regions (NCRs) and gene rearrangements are commonly seen in mitochondrial genomes of Mantodea and are primarily focused on three regions: CR-I-Q-M-ND2 , COX2-K-D-ATP8, and ND3-A-R-N-S-E-F-ND5 . In this study, eight complete and one nearly complete mitochondrial genomes of praying mantises were acquired for the purpose of discussing mitochondrial gene rearrangements and phylogenetic relationships within Mantodea, primarily in the newly established families Haaniidae and Gonypetidae. Except for Heterochaeta sp. JZ-2017, novel mitochondrial gene arrangements were detected in Cheddikulama straminea , Sinomiopteryx graham , Pseudovates chlorophaea , Spilomantis occipitalis . Of note is the fact that one type of novel arrangement was detected for the first time in the Cyt b-S2-ND1 region. This could be reliably explained by the tandem replication-random loss (TDRL) model. The long NCR between trnT and trnP was generally found in Iridopteryginae and was similar to the ND4L or ND6 gene. Combined with gene rearrangements and intergenic regions, the monophyly of Haaniidae was supported, whereas the paraphyly of Gonypetidae was recovered. Furthermore, several synapomorphies unique to some clades were detected that conserved block sequences between trnI and trnQ and gaps between trnT and trnP in Toxoderidae and Iridopteryginae, respectively.

The phylogenetic relationship of Ephemeridae (Insect: Ephemeroptera) remains hotly debated using mitochondrial (mt) genomes. All previously reported mt genomes of Ephemeridae belong to the genus Ephemera . This study provides the first complete mt genome sequence from the genus Hexagenia with an analysis of the mitogenome of Hexagenia rigida Mc Dunnough, 1924 (Ephemeroptera: Ephemeridae) and providing new information to discuss the phylogenetic relationships within Ephemeroptera. The complete mt genome of H. rigida was a circular molecule of 16,159 bp in length, containing 37 genes (2 rRNA genes, 13 protein-coding genes, 22 tRNA genes), which showed the typical mt gene arrangement of insects. The AT content of the whole genome was 70.0% and the length of the control region was 1091 bp. All protein-coding genes used ATN as the start codon, and most PCGs used TAA/TAG as the stop codons excluding COI, COII, ND5 and Cyt b that used T as the stop codon. BI and ML phylogenetic trees constructed from 27 species of 13 families showed that Ephemeridae is a sister clade to the clade Polymitarcyidae., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

The complete mitochondrial (mt) genome of Leptomantella tonkinae (Hebard, 1920) was 15,527 bp in length and contained 13 protein-coding genes, 22 transfer RNAs, two ribosomal RNAs, and one control region. The gene arrangement of mt genome of L. tonkinae was identical to the primitive mantis. The overall AT content of the mt genome was 74%. In ML and BI phylogenetic analyses, the monophyly of Leptomantellidae was robustly supported and the clade of Leptomantellidae is a sister clade to the group of (Gonypetidae+(Leptomantellidae+(Amorphoscelidae+Nanomantidae)))., Competing Interests: The authors report no conflict of interest. The authors alone are responsible for the content and writing of the article., (© 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Background: Hoplobatrachus rugulosus (Anura: Dicroglossidae) is distributed in China and Thailand and the former can survive substantially lower temperatures than the latter. The mitochondrial genomes of the two subspecies also differ: Chinese tiger frogs (CT frogs) display two identical ND5 genes whereas Thai tiger frogs (TT frogs) have two different ND5 genes. Metabolism of ectotherms is very sensitive to temperature change and different organs have different demands on energy metabolism at low temperatures. Therefore, we conducted studies to understand: (1) the differences in mitochondrial gene expression of tiger frogs from China (CT frogs) versus Thailand (TT frogs); (2) the differences in mitochondrial gene expression of tiger frogs (CT and TT frogs) under short term 24 h hypothermia exposure at 25 °C and 8 °C; (3) the differences in mitochondrial gene expression in three organs (brain, liver and kidney) of CT and TT frogs., Results: Utilizing RT-qPCR and comparing control groups at 25 °C with low temperature groups at 8 °C, we came to the following results. (1) At the same temperature, mitochondrial gene expression was significantly different in two subspecies. The transcript levels of two identical ND5 of CT frogs were observed to decrease significantly at low temperatures (P < 0.05) whereas the two different copies of ND5 in TT frogs were not. (2) Under low temperature stress, most of the genes in the brain, liver and kidney were down-regulated (except for COI and ATP6 measured in brain and COI measured in liver of CT frogs). (3) For both CT and TT frogs, the changes in overall pattern of mitochondrial gene expression in different organs under low temperature and normal temperature was brain > liver > kidney., Conclusions: We mainly drew the following conclusions: (1) The differences in the structure and expression of the ND5 gene between CT and TT frogs could result in the different tolerances to low temperature stress. (2) At low temperatures, the transcript levels of most of mitochondrial protein-encoding genes were down-regulated, which could have a significant effect in reducing metabolic rate and supporting long term survival at low temperatures. (3) The expression pattern of mitochondrial genes in different organs was related to mitochondrial activity and mtDNA replication in different organs., (© 2022. The Author(s).)

Ephemeroptera (Insecta: Pterygota) are widely distributed all over the world with more than 3500 species. During the last decade, the phylogenetic relationships within Ephemeroptera have been a hot topic of research, especially regarding the phylogenetic relationships among Vietnamellidae. In this study, three mitochondrial genomes from three populations of Vienamella sinensis collected from Tonglu ( V. sinensis TL), Chun'an ( V. sinensis CN), and Qingyuan ( V. sinensis QY) in Zhejiang Province, China were compared to discuss the potential existence of cryptic species. We also established their phylogenetic relationship by combining the mt genomes of 69 Ephemeroptera downloaded from NCBI. The mt genomes of V. sinensis TL, V. sinensis CN, and V. sinensis QY showed the same gene arrangement with lengths of 15,674 bp, 15,674 bp, and 15,610 bp, respectively. Comprehensive analyses of these three mt genomes revealed significant differences in mt genome organization, genetic distance, and divergence time. Our results showed that the specimens collected from Chun'an and Tonglu in Zhejiang Province, China belonged to V. sinensis , and the specimens collected from Qingyuan, Zhejiang Province, China were a cryptic species of V. sinensis . In maximum likelihood (ML) and Bayesian inference (BI) phylogenetic trees, the monophyly of the family Vietnamellidae was supported and Vietnamellidae has a close relationship with Ephemerellidae.

Rana johnsi (Smith 2009) firstly considered as the member of genus Pseudorana , has been moved into the genus Rana . In this study, we sequenced the complete mitochondrial (mt) genome of R. johnsi using the Sanger method. The circular mt genome was 17,873 bp in length and contains 13 protein-coding genes (PCGs), 22 transfer RNA ( tRNA ) genes, two ribosome RNA genes, and one control region. The overall nucleotide composition in majority-strand was 28% A, 29% T, 29% C, and 14% G. We discussed the phylogenetic relationship of R. johnsi in genus Rana using ML and BI analyses based on 13 PCGs. Excluding the clade of subgenus Lithobates , Rana draytonii was the basal clade to all other Rana species, which included R. johnsi as the basal clade. The monophyly of genus Rana was supported, whereas Pseudorana was failed to support., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

The availability of next-generation sequencing (NGS) in recent years has facilitated a revolution in the availability of mitochondrial (mt) genome sequences. The mt genome is a powerful tool for comparative studies and resolving the phylogenetic relationships among insect lineages. The mt genomes of phytophagous scarabs of the subfamilies Cetoniinae and Dynastinae were under-represented in GenBank. Previous research found that the subfamily Rutelinae was recovered as a paraphyletic group because the few representatives of the subfamily Dynastinae clustered into Rutelinae, but the subfamily position of Dynastinae was still unclear. In the present study, we sequenced 18 mt genomes from Dynastinae and Cetoniinae using next-generation sequencing (NGS) to re-assess the phylogenetic relationships within Scarabaeidae. All sequenced mt genomes contained 37 sets of genes (13 protein-coding genes, 22 tRNAs, and two ribosomal RNAs), with one long control region, but the gene order was not the same between Cetoniinae and Dynastinae species. All mt genomes of Dynastinae species showed the same gene rearrangement of trnQ-NCR-trnI-trnM, whereas all mt genomes of Cetoniinae species showed the ancestral insect gene order of trnI-trnQ-trnM. Phylogenetic analyses (IQ-tree and MrBayes) were conducted using 13 protein-coding genes based on nucleotide and amino acid datasets. In the ML and BI trees, we recovered the monophyly of Rutelinae, Cetoniinae, Dynastinae, and Sericinae, and the non-monophyly of Melolonthinae. Cetoniinae was shown to be a sister clade to (Dynastinae + Rutelinae).

The present study explored the modulating apoptosis effect of hydrogen sulfide (H 2 S) in subarachnoid hemorrhage (SAH) rats and its exact mechanism. A rat SAH model established by intravascular puncturing was used for the present study. After giving NaHS (donor of H 2 S), an L-type calcium channel opener (Bay K8644), or a calcium channel agonist (nifedipine), the neurological function of the rats, associated pathological changes, and expression of apoptosis-related proteins (Bcl-2, Bax, and caspase-3) and microtubule-associated protein (MAP-2) were examined. The concentration of H 2 S and expression of cystathionine beta synthase in the hippocampus changed upon early brain injury (EBI) after SAH. Compared with the SAH group, the neurological function of the rats and microstructure observed by electron microscopy were better in the SAH + NaHS group and SAH + Bay K8644 group. It was observed that apoptosis was more obvious in the SAH group than in the control group and was alleviated in the SAH + NaHS group. Furthermore, the alleviating effect of NaHS was partially weakened by nifedipine, indicating that the effect of anti-apoptosis in H 2 S might be correlated with the calcium channel. The expression of Bax and caspase-3 was elevated, while the expression of Bcl-2 decreased in the SAH group but improved in the SAH + NaHS and SAH + Bay K8644 group. Compared with the SAH + NaHS group, the expression of pro-apoptotic proteins was higher in the SAH + NaHS + nifedipine group. Therefore, upon EBI following SAH, the H 2 S system plays an important neurological protective effect by modulating the function of the L-type calcium channel and inhibiting apoptosis., (© 2020. Springer Science+Business Media, LLC, part of Springer Nature.)

As one of the most common benthic invertebrates in freshwater, mayflies are very sensitive to changes in water quality and have high requirements for the water environment to allow their nymphs to successfully live and grow. Neonicotinoids, such as imidacloprid, can enter fresh water and pollute the aquatic environment. The present study had two goals: (1) investigate imidacloprid effects on mayfly larvae Choroterpes (Euthralus) yixingensis, and (2) contribute to the phylogenetic status of Ephemeroptera that has always been controversial. Nymphs were collected from Jinhua, China and exposed to different concentrations imidacloprid (5, 10, 20, and 40 μg/L) in the laboratory. Survival of C. yixingensis nymphs decreased as a function of time and imidacloprid concentration with only ~ 55% survival after 72 h exposure to 40 μg/L imidacloprid. After culture under 40 μg/L imidacloprid for 24 h, the steady state transcript levels of mitochondrial COX3, ND4 and ND4L genes were reduced to just 0.07 ± 0.11, 0.30 ± 0.16, and 0.28 ± 0.13 as compared with respective control values (P < 0.01). Steady state transcript levels of ND4 and ND4L were also significantly reduced in a dose-dependent manner (P < 0.05), suggesting that the steady state transcript pattern of these genes in mayfly nymphs can change in response to different levels of environmental contamination. Hence, the mitochondrial protein-coding genes of mayflies could potentially be developed as biomarkers for water ecotoxicity monitoring in the future. In addition, we used the mitochondrial genome sequence of C. yixingensis for an assessment of the phylogenetic tree of Ephemeroptera. The monophyly of Leptophlebiidae was supported and showed that Leptophlebiidae was a sister group to the clade (Baetidae + Caenidae)., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The Lonchodinae (Phasmatodea: Phasmatidae) is rich in insect species with more than 330 species of 40 genera. The phylogenetic relationships within Lonchodinae have been under debate. We successfully sequenced the complete mitogenome of Eurycantha calcarata Lucas, 1869 (Phasmatodea: Lonchodinae) with a length of 16,280 bp, which had the same genes and gene arrangements as those of various published papers on stick insects. The whole mitogenome and control region of E. calcarata had a high AT content of 78.2 and 85.9%, respectively. All PCGs used ATN as the start codon, and most PCGs used TAA/TAG as the stop codons excluding COX2 (T), COX3 (TA), and ND5 (TA). To discuss the phylogeny of Lonchodinae, we reconstructed the phylogenetic relationships of 27 species of Phasmatodea including E. calcarata and two species of Embioptera used as outgroups. In BI and ML trees, the monophyly of Lonchodinae and Necrosciinae was well supported, whereas the monophyly of Clitumninae was not recovered. These results indicated that Lonchodinae was a sister clade to Phylliinae and E. calcarata was a sister clade to Phraortes genus., Competing Interests: No potential conflict of interest was reported by the authors., (© 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

The order Microcoryphia, commonly known as bristletails, is considered as the most primitive one among living insects. Within this order, two species, Coreamachilis coreanus and C. songi (Machilidae: Machilinae), display the following contrasting reproductive strategies: parthenogenesis occurs in C. coreanus , whereas sexual reproduction is found in C. songi . In the present study, the complete mitogenomes of C. coreanus and C. songi were sequenced to compare their mitogenome structure, analyze relationships within the Microcoryphia, and assess adaptive evolution. The length of the mitogenomes of C. coreanus and C. songi were 15,578 bp and 15,570 bp, respectively, and the gene orders were those of typical insects. A long hairpin structure was found between the ND1 and 16S rRNA genes of both species that seem to be characteristic of Machilinae and Petrobiinae species. Phylogenetic assessment of Coreamachilis was conducted using BI and ML analyses with concatenated nucleotide sequences of the 13 protein-coding genes. The results showed that the monophyly of Machilidae, Machilinae, and Petrobiinae was not supported. The genus Coreamachilis ( C. coreanus and C. songi ) was a sister clade to Allopsontus helanensis , and then the clade of (( C. coreanus + C. songi ) + A. helanensis ) was a sister clade to A. baii , which suggests that the monophyly of Allopsontus was not supported. Positive selection analysis of the 13 protein-coding genes failed to reveal any positive selection in C. coreanus or C. songi . The long hairpin structures found in Machilinae and Petrobiinae were highly consistent with the phylogenetic results and could potentially be used as an additional molecular characteristic to further discuss relationships within the Microcoryphia.

Insects of the order Phasmatodea are mainly distributed in the tropics and subtropics and are best known for their remarkable camouflage as plants. In this study, we sequenced three complete mitochondrial genomes from three different families: Orestes guangxiensis, Peruphasma schultei, and Phryganistria guangxiensis . The lengths of the three mitochondrial genomes were 15,896 bp, 16,869 bp, and 17,005 bp, respectively, and the gene composition and structure of the three stick insects were identical to those of the most recent common ancestor of insects. The phylogenetic relationships among stick insects have been chaotic for a long time. In order to discuss the intra- and inter-ordinal relationship of Phasmatodea, we used the 13 protein-coding genes (PCGs) of 85 species for maximum likelihood (ML) and Bayesian inference (BI) analyses. Results showed that the internal topological structure of Phasmatodea had a few differences in both ML and BI trees and long-branch attraction (LBA) appeared between Embioptera and Zoraptera, which led to a non-monophyletic Phasmatodea. Consequently, after removal of the Embioptera and Zoraptera species, we re-performed ML and BI analyses with the remaining 81 species, which showed identical topology except for the position of Tectarchus ovobessus (Phasmatodea). We recovered the monophyly of Phasmatodea and the sister-group relationship between Phasmatodea and Mantophasmatodea. Our analyses also recovered the monophyly of Heteropterygidae and the paraphyly of Diapheromeridae, Phasmatidae, Lonchodidae, Lonchodinae, and Clitumninae. In this study, Peruphasma schultei (Pseudophasmatidae), Phraortes sp. YW-2014 (Lonchodidae), and species of Diapheromeridae clustered into the clade of Phasmatidae. Within Heteropterygidae, O. guangxiensis was the sister clade to O. mouhotii belonging to Dataminae, and the relationship of (Heteropteryginae + (Dataminae + Obriminae)) was recovered.

Gene rearrangements have been found in several mitochondrial genomes of Mantodea, located in the gene blocks CR-I-Q-M-ND2, COX1-K-D-ATP8 and ND3-A-R-N-S-E-F-ND5. We have sequenced one mitogenome of Amelidae (Yersinia mexicana) and six mitogenomes of Mantidae to discuss the mitochondrial gene rearrangement and the phylogenetic relationship within Mantidae. These mitogenomes showed rearrangements of tRNA genes except for Asiadodis yunnanensis and Hierodula zhangi. These novel gene rearrangements of Mantidae were primarily concentrated in the region of CR-I-Q-M-ND2, including gene translocation, duplication and pseudogenization. For the occurrences of these rearrangements, the tandem duplication-random loss (TDRL) model and slipped-strand mispairing model were suitable to explain. Large non-coding regions (LNCRs) located in the region of CR-I-Q-M-ND2 were detected in most Mantidae species, whereas some LNCRs had high similarity to the control region (CR). Both BI and ML phylogenetic analyses supported the monophyly of Mantidae and the paraphyly of Mantinae. The phylogenetic results with the gene order and the location of NCRs acted as forceful evidence that specific gene rearrangements and special LNCRs may be synapomorphies for several groups of mantises., (Copyright © 2021 Elsevier B.V. All rights reserved.)

We determined 15 complete and two nearly complete mitogenomes of Heptageniidae belonging to three subfamilies (Heptageniinae, Rhithrogeninae, and Ecdyonurinae) and six genera ( Afronurus , Epeorus , Leucrocuta , Maccaffertium , Stenacron , and Stenonema ). Species of Rhithrogeninae and Ecdyonurinae had the same gene rearrangement of CR -I-M-Q-M-ND2 , whereas a novel gene rearrangement of CR- I-M-Q -NCR- ND2 was found in Heptageniinae. Non-coding regions (NCRs) of 25-47 bp located between trnA and trnR were observed in all mayflies of Heptageniidae, which may be a synapomorphy for Heptageniidae. Both the BI and ML phylogenetic analyses supported the monophyly of Heptageniidae and its subfamilies (Heptageniinae, Rhithrogeninae, and Ecdyonurinae). The phylogenetic results combined with gene rearrangements and NCR locations confirmed the relationship of the subfamilies as (Heptageniinae + (Rhithrogeninae + Ecdyonurinae)). To assess the effects of low-temperature stress on Heptageniidae species from Ottawa, Canada, we found 27 positive selection sites in eight protein-coding genes (PCGs) using the branch-site model. The selection pressure analyses suggested that mitochondrial PCGs underwent positive selection to meet the energy requirements under low-temperature stress.

Background: The phylogenetic relationships of Odonata (dragonflies and damselflies) and Ephemeroptera (mayflies) remain unresolved. Different researchers have supported one of three hypotheses (Palaeoptera, Chiastomyaria or Metapterygota) based on data from different morphological characters and molecular markers, sometimes even re-assessing the same transcriptomes or mitochondrial genomes. The appropriate choice of outgroups and more taxon sampling is thought to eliminate artificial phylogenetic relationships and obtain an accurate phylogeny. Hence, in the current study, we sequenced 28 mt genomes from Ephemeroptera, Odonata and Plecoptera to further investigate phylogenetic relationships, the probability of each of the three hypotheses, and to examine mt gene arrangements in these species. We selected three different combinations of outgroups to analyze how outgroup choice affected the phylogenetic relationships of Odonata and Ephemeroptera., Methods: Mitochondrial genomes from 28 species of mayflies, dragonflies, damselflies and stoneflies were sequenced. We used Bayesian inference (BI) and Maximum likelihood (ML) analyses for each dataset to reconstruct an accurate phylogeny of these winged insect orders. The effect of outgroup choice was assessed by separate analyses using three outgroups combinations: (a) four bristletails and three silverfish as outgroups, (b) five bristletails and three silverfish as outgroups, or (c) five diplurans as outgroups., Results: Among these sequenced mitogenomes we found the gene arrangement IMQM in Heptageniidae (Ephemeroptera), and an inverted and translocated tRNA-Ile between the 12S RNA gene and the control region in Ephemerellidae (Ephemeroptera). The IMQM gene arrangement in Heptageniidae (Ephemeroptera) can be explained via the tandem-duplication and random loss model, and the transposition and inversion of tRNA-Ile genes in Ephemerellidae can be explained through the recombination and tandem duplication-random loss (TDRL) model. Our phylogenetic analysis strongly supported the Chiastomyaria hypothesis in three different outgroup combinations in BI analyses. The results also show that suitable outgroups are very important to determining phylogenetic relationships in the rapid evolution of insects especially among Ephemeroptera and Odonata. The mt genome is a suitable marker to investigate the phylogeny of inter-order and inter-family relationships of insects but outgroup choice is very important for deriving these relationships among winged insects. Hence, we must carefully choose the correct outgroup in order to discuss the relationships of Ephemeroptera and Odonata., Competing Interests: Kenneth B. Storey and Jia-Yong Zhang are Academic Editors for PeerJ., (©2021 Yu et al.)

The first complete mitochondrial genome of Euroleon coreanus (Okamoto, 1926) was 15,797 bp in length, and contained 13 protein-coding genes, 22 transfer RNAs, two ribosomal RNAs, and the control region. Compared to the classic insect mitochondrial genome, E. coreanus showed a gene rearrangement of ND2-C-W-Y-COX1 . The overall AT content of the mitochondrial genome was 75.5%. The monophyly of Ascalaphidae, Myrmeleontidae, Nemopteridae, Nymphidae, and Psychopsidae was supported in both BI and ML trees. And E. coreanus was a sister clade to the clade of genus Myrmeleon ., Competing Interests: No potential conflict of interest was reported by the authors., (© 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Zoodes fulguratus is a common species of Cerambycidae, reported from Vietnam, Nepal, Laos, Burma, and China. To date, no mitochondrial genomes of the genus Zoodes have been reported. In this study, we sequenced and analyzed the first mitochondrial genome of Z. fulguratus to discuss its phylogenetic relationship within the subfamily Cerambycinae. This mitochondrial genome showed the typical insect gene arrangement: a circular molecule of 15,885 bp long with 13 protein-coding genes, two ribosomal RNA genes (rRNAs), and 22 transfer RNA genes (tRNAs). The AT content of the whole mitogenome was 74.2% with a high asymmetric nucleotide presentation revealed by a positive AT-skew (0.067) and a negative GC-skew (-0.178), whereas the AT content of the A + T rich region was 80%. The Maximum likelihood (ML) and Bayesian inference (BI) phylogenetic analyses showed that Z. fulguratus is a sister clade of Gnatholea eburifera., Competing Interests: No potential conflict of interest was reported by the authors., (© 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

We determined the mitochondrial gene sequence of Monochamus alternatus and three other mitogenomes of Lamiinae (Insect: Coleoptera: Cerambycidae) belonging to three genera ( Aulaconotus , Apriona and Paraglenea ) to enrich the mitochondrial genome database of Lamiinae and further explore the phylogenetic relationships within the subfamily. Phylogenetic trees of the Lamiinae were built using the Bayesian inference (BI) and maximum likelihood (ML) methods and the monophyly of Monochamus , Anoplophora , and Batocera genera was supported. Anoplophora chinensis , An. glabripennis and Aristobia reticulator were closely related, suggesting they may also be potential vectors for the transmission of the pine wood pathogenic nematode ( Bursaphelenchus xylophilus ) in addition to M. alternatus , a well-known vector of pine wilt disease. There is a special symbiotic relationship between M. alternatus and Bursaphelenchus xylophilus . As the native sympatric sibling species of B. xylophilus , B. mucronatus also has a specific relationship that is often overlooked. The analysis of mitochondrial gene expression aimed to explore the effect of B. mucronatus on the energy metabolism of the respiratory chain of M. alternatus adults. Using RT-qPCR, we determined and analyzed the expression of eight mitochondrial protein-coding genes ( COI , COII , COIII , ND1 , ND4 , ND5 , ATP6 , and Cty b ) between M. alternatus infected by B. mucronatus and M. alternatus without the nematode. Expression of all the eight mitochondrial genes were up-regulated, particularly the ND4 and ND5 gene, which were up-regulated by 4-5-fold ( p < 0.01). Since longicorn beetles have immune responses to nematodes, we believe that their relationship should not be viewed as symbiotic, but classed as parasitic.

As a small order of Pterygota (Insecta), Ephemeroptera has almost 3,500 species around the world. Ephemerellidae is a widely distributed common group of Ephemeroptera. However, the relationship among Ephemerellidae, Vietnamellidae and Teloganellidae is still in dispute. In this study, we sequenced six complete mitogenomes of three genera from Ephemerellidae (Insecta: Ephemeroptera): Ephemerella sp. Yunnan-2018, Serratella zapekinae , Serratella sp. Yunnan-2018, Serratella sp. Liaoning-2019, Torleya grandipennis and T. tumiforceps . These mitogenomes were employed to reveal controversial phylogenetic relationships among the Ephemeroptera, with emphasis on the phylogenetic relationships among Ephemerellidae. The lengths of the six mayfly mitogenomes ranged from 15,134 bp to 15,703 bp. Four mitogenomes of Ephemerella sp. Yunnan-2018, Serratella zapekinae , Serratella sp. Yunnan-2018 and Serratella sp. Liaoning-2019 had 22 tRNAs including an inversion and translocation of trnI . By contrast, the mitogenomes of T. tumiforceps and T. grandipennis had 24 tRNAs due to an extra two copies of inversion and translocation of trnI . Within the family Ephemerellidae, disparate gene rearrangement occurred in the mitogenomes of different genera: one copy of inversion and translocation trnI in the genera Ephemerella and Serratella , and three repeat copies of inversion and translocation of trnI in the genus Torleya . A large non-coding region (≥200 bp) between trnS1 (AGN) and trnE was detected in T. grandipennis and T. tumiforceps . Among the phylogenetic relationship of the Ephemeroptera, the monophyly of almost all families except Siphlonuridae was supported by BI and ML analyses. The phylogenetic results indicated that Ephemerellidae was the sister clade to Vietnamellidae whereas Teloganellidae was not a sister clade of Ephemerellidae and Vietnamellidae., Competing Interests: Kenneth B. Storey and Jia-Yong Zhang are Academic Editors for PeerJ., (©2020 Xu et al.)

The complete mitochondrial genome of Pedetontus zhejiangensis (Microcoryphia: Machilidae) was successfully sequenced. The mitochondrial genome of P. zhejiangensis was a circular molecule of 15,602 bp in length, containing 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and the control region, which showed the typical insect mitochondrial genome arrangement. The AT content of the whole genome was 73.8% and the length of the control region was 671 bp with 82.5% AT content. In BI and ML phylogenetic trees, P. zhejiangensis was a sister group to Pedetontus silvestrii , and the monophyly of Pedetontus was strongly supported. The genus Pedetontinus was a sister group to Pedetontus ., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

The mitochondrial genome sequence of Xanthomantis bimaculata (Mantodea: Iridopterygidae) from Yunnan, China is a circular molecule with the typical insect mitochondrial gene arrangement, which is 15,941 bp in length and contains 22 tRNAs, two rRNAs, 13 protein-coding genes, and one control region. The overall AT content of the mitogenome is 73.12% (A = 37.58%, T = 35.54%, C = 16.54%, G = 10.34%). In BI and ML phylogenetic analyses, X. bimaculata was a sister clade to Sceptuchus simpl ex. The monophyly of the families Iridopterygidae, Thespidae and Liturgusidae were supported., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Mitogenomes are useful in analyzing phylogenetic relationships and also appear to influence energy metabolism, thermoregulation and osmoregulation. Much evidence has accumulated for positive selection acting on mitochondrial genes associated with environmental adaptation. Hence, the mitogenome is a likely target for environmental selection. The family Bufonidae (true toads) has only nine complete and four partial mitogenomes published compared to the 610 known species of this family. More mitogenomes are needed in order to obtain a clearer understanding of the phylogenetic relationships within Bufonidae that are currently controversial. To date, no mitogenomes have been reported from the genera Anaxyrus and Bufotes . Anaxyrus americanus can live in low temperature environments and Bufotes pewzowi can live in high salinity environments. We sequenced the mitogenomes of these two species to discuss the phylogenetic relationships within Bufonidae and the selection pressures experienced by specimens living in low temperature or saline environments. Like other toads, the circular mitogenomes of both species contained the typical 37 genes. Anaxyrus americanus had the highest A+T content of the complete mitogenome among the Bufonidae. In addition, A. americanus showed a negative AT-skew in the control region, whereas Bufotes pewzowi showed a positive AT-skew. Additionally, both toad species had unique molecular features in common: an ND1 gene that uses TTG as the start codon, an extra unpaired adenine (A) in the anticodon arm of trnS (AGY), and the loss of the DHU loop in trnC . The monophyly of Bufonidae was corroborated by both BI and ML trees. An analysis of selective pressure based on the 13 protein coding genes was conducted using the EasyCodeML program. In the branch model analysis, we found two branches of A. americanus and Bufotes pewzowi that were under negative selection. Additionally, we found two positively selected sites (at positions 115 and 119, BEB value > 0.90) in the ND6 protein in the site model analysis. The residue D (119) was located only in A. americanus and may be related to adaptive evolution in low temperature environments. However, there was no evidence of a positively selected site in Bufotes pewzowi in this study., Competing Interests: Jia-Yong Zhang is an Academic Editor for PeerJ. Kenneth B. Storey is an Academic Editor for PeerJ., (©2020 Cai et al.)

The complete mitochondrial genome of the Annamanum lunulatum is 15,610 bp in length, which contains 13 protein-coding genes, 22 transfer RNAs, two ribosomal RNAs, and the A + T-rich region. The arrangement of genes is identical to all know longhorn beetles mitochondrial genomes. The overall AT content of the mitochondrial genome is 75.3%, whereas the AT content of A + T-rich region is 84.3%. In ML and BI phylogenetic analyses, A. lunulatum is a sister clade to Blepephaeus succinctor , and the monophyly of Lamiinae is supported., Competing Interests: No potential conflict of interest was reported by the authors., (© 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

The phylogenetic relationship of Caenidae remains hotly debated within the Ephemeroptera. We sequenced the complete mitochondrial genome of Caenis sp. (Ephemeroptera: Caenidae) to discuss the phylogenetic relationships among the Caenidae. The mitochondrial genome of Caenis sp. collected from Jian'ou, Fujian province, China is a circular molecule of 15,392 bp in length containing 37 genes (13 protein-coding genes, 22 tRNAs, and two rRNAs), which showed the typical insect mitochondrial gene arrangement. In BI and ML phylogenetic trees using 23 species from 13 families, the monophyly of the families Caenidae, Heptageniidae, Isonychiidae, and Vietnamellidae was strongly supported. The clade of Caenidae is a sister clade to the clade of Teloganodidae and Baetidae., Competing Interests: No potential conflict of interest was reported by the authors., (© 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

The complete mitochondrial genome of Mantis religiosa (Mantodea: Mantidae) from Canada was successfully sequenced. The mitochondrial genome was a circular molecule of 15,521 bp in length, containing 13 protein-coding genes, two rRNA genes, 23 tRNA genes (including an extra tRNA Arg gene), and the control region. The AT content of the whole genome was 76.9% and the length of the control region was 636 bp with 81.9% AT content. The structure of the M. religiosa mitochondrial genome from Canada was almost identical to M. religiosa from China and their genetic distance was just 0.017. In Bayesian inference (BI) and maximum likelihood (ML) analyses, we found that M. religiosa was a sister clade to Statilia sp. and the monophyly of the genera Hierodula and Rhombodera was not supported., Competing Interests: No potential conflict of interest was reported by the authors., (© 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Cerambycidae is one of the most diversified groups within Coleoptera and includes nearly 35,000 known species. The relationships at the subfamily level within Cerambycidae have not been convincingly demonstrated and the gene rearrangement of mitochondrial genomes in Cerambycidae remains unclear due to the low numbers of sequenced mitogenomes. In the present study, we determined five complete mitogenomes of Cerambycidae and investigated the phylogenetic relationship among the subfamilies of Cerambycidae based on mitogenomes. The mitogenomic arrangement of all five species was identical to the ancestral Cerambycidae type without gene rearrangement. Remarkably, however, two large intergenic spacers were detected in the mitogenome of Pterolophia sp. ZJY-2019. The origins of these intergenic spacers could be explained by the slipped-strand mispairing and duplication/random loss models. A conserved motif was found between trnS2 and nad1 gene, which was proposed to be a binding site of a transcription termination peptide. Also, tandem repeat units were identified in the A + T-rich region of all five mitogenomes. The monophyly of Lamiinae and Prioninae was strongly supported by both MrBayes and RAxML analyses based on nucleotide datasets, whereas the Cerambycinae and Lepturinae were recovered as non-monophyletic., Competing Interests: Kenneth B. Storey and Jia-Yong Zhang are Academic Editors for PeerJ.

The family Pyxicephalidae including two subfamilies (Cacosterninae and Pyxicephalinae) is an ecologically important group of frogs distributed in sub-Saharan Africa. However, its phylogenetic position among the Anura has remained uncertain. The present study determined the complete mitochondrial genome sequence of Pyxicephalus adspersus , the first representative mitochondrial genome from the Pyxicephalinae, and reconstructed the phylogenetic relationships within Ranoidae using 10 mitochondrial protein-coding genes of 59 frog species. The P. adspersus mitochondrial genome showed major gene rearrangement and an exceptionally long length that is not shared with other Ranoidae species. The genome is 24,317 bp in length, and contains 15 protein-coding genes (including extra COX3 and Cyt b genes), four rRNA genes (including extra 12S rRNA and 16S rRNA genes), 29 tRNA genes (including extra tRNA Leu ( UAG ) , tRNA Leu ( UUR ) , tRNA Thr , tRNA Pro , tRNA Phe , tRNA Val , tRNA Gln genes) and two control regions (CRs). The Dimer-Mitogenome and Tandem duplication and random loss models were used to explain these gene arrangements. Finally, both Bayesian inference and maximum likelihood analyses supported the conclusion that Pyxicephalidae was monophyletic and that Pyxicephalidae was the sister clade of (Petropedetidae + Ptychadenidae)., Competing Interests: Kenneth B. Storey is an Academic Editor for PeerJ. Jia-Yong Zhang is an Academic Editor for PeerJ.

Dryophytes versicolor is one of the most extreme freeze-tolerant frogs from eastern North America. In this study, the mitochondrial genome of D. versicolor was sequenced to analyze the phylogenetic relationships among Hylidae and investigate mitochondrial gene expression in response to freezing and anoxia. The total length of the D. versicolor mitogenome is the longest known to date among the available family members of Hylidae. Both maximum likelihood (ML) and Bayesian inference (BI) analyses strongly supported D. versicolor as a sister clade to (D. japonica + D. ussuriensis) + (D. suweonensis + D. immaculata (KP212702)), and indicated that Dryophytes is monophyletic. Using the mitochondrial genome, gene expression analysis was performed using RT-qPCR in skeletal muscle samples, and determined that relative levels of D. versicolor COX2 increased by 2.40 ± 0.23 fold in response to anoxia, but did not change with exposure to freezing. In addition, ND3 transcript levels decreased in response to anoxia but remained constant during freezing. By contrast, COX1 transcript levels decreased with exposure to freezing, but did not change under anoxic conditions. These results suggest that modulations of protein-coding mitochondrial genes of D. versicolor may play a role in the molecular response to freezing and anoxia tolerance., (Copyright © 2019. Published by Elsevier B.V.)

Different mitochondrial gene copies or gene rearrangements are observed in some interspecific mitochondrial genomes (mitogenomes), but few in intraspecific mitogenomes. In this study, we sequenced the complete mitogenomes of Statilia maculata and Statilia nemoralis (Mantinae: Mantini). The genetic distance of the whole genomes between these two species was just 0.5%, suggesting that S. maculata and S. nemoralis might be the same species. The mitogenome of S. maculata had five copies of trnR genes (three copies were identical and the other two had some base substitutions), whereas the mitogenome of S. nemoralis had six trnR genes. Five, six or seven tandem copies of trnR genes in S. maculata were found in different localities, respectively. We further sequenced the ND3-ND5 region of fifty individuals hatched from one ootheca (Tianjin) and we found that all individuals had five identical tandem copies of trnR genes and same sequences. Hence, we concluded that different copies of trnR genes can occur in the same species. The mitogenomes of S. maculata and S. nemoralis with other mitogenomes of Mantinae species published were used to construct BI and ML phylogenetic trees. In this study, both BI and ML phylogenetic trees showed that Mantini and Statilia were monophyletic whereas Paramantini was paraphyletic., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The owlflies (Family Ascalaphidae) belong to the Neuroptera but are often mistaken as dragonflies because of morphological characters. To date, only three mitochondrial genomes of Ascalaphidae, namely Libelloides macaronius ; Ascaloptynx appendiculatus ; Ascalohybris subjacens , are published in GenBank, meaning that they are greatly under-represented in comparison with the 430 described species reported in this family. In this study, we sequenced and described the complete mitochondrial genome of Suhpalacsa longialata (Neuroptera, Ascalaphidae). The total length of the S. longialata mitogenome was 15,911 bp, which is the longest known to date among the available family members of Ascalaphidae. However, the size of each gene was similar to the other three Ascalaphidae species. The S. longialata mitogenome included a transposition of tRNA Cys and tRNA Trp genes and formed an unusual gene arrangement tRNA Cys -tRNA Trp -tRNA Tyr (CWY). It is likely that the transposition occurred by a duplication of both genes followed by random loss of partial duplicated genes. The nucleotide composition of the S. longialata mitogenome was as follows: A = 41.0%, T = 33.8%, C = 15.5%, G = 9.7%. Both Bayesian inference and ML analyses strongly supported S. longialata as a sister clade to ( Ascalohybris subjacens + L. macaronius ), and indicated that Ascalaphidae is not monophyletic., Competing Interests: Kenneth B. Storey is an Academic Editor for PeerJ.

In this data article, we provide five datasets of mantis mitochondrial genomes: (1) PCG123: nucleotide sequences of 13 protein-coding genes including all codon positions; (2) PCG123R: nucleotide sequences of two rRNAs and 13 protein-coding genes including all codon positions; (3) PCG12: nucleotide sequences of 13 protein-coding genes without third codon positions; (4) PCG12R: nucleotide sequences of two rRNAs and 13 protein-coding genes without third codon positions, and (5) PCGAA: amino acid sequences of 13 protein-coding genes. These were used to construct phylogenetic relationships within Mantodea and the phylogenetic trees inferred from Bayesian analysis using two data sets (PCG12R, PCGAA) and Maximum Likelihood analysis using four data sets (PCG123, PCG12, PCG12R and PCGAA). We also provide initiation codon, termination codon, amino acid length and nucleotide diversity (Pi) of protein-coding genes among 27 mantises. The whole mitochondrial genomes of 27 praying mantises were submitted to GenBank with the accession numbers KY689112-KY689138.

The phylogenetic relationship between Ephemeroptera (mayflies) and Odonata (dragonflies and damselflies) remains hotly debated in the insect evolution community. We sequenced the complete mitochondrial genome of Caenis sp. (Ephemeroptera: Caenidae) to discuss the phylogenetic relationship of Palaeoptera. The mitochondrial genome of Caenis sp. is a circular molecule of 15,254 bp in length containing 37 genes (13 protein-coding genes, 22 tRNAs, and 2 rRNAs), which showed the typical insect mitochondrial gene arrangement. In BI and ML phylogenetic trees using 71 species of 12 orders, our results support the Ephemeroptera as the basal group of winged insects., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

We acquired 21 complete mitogenomes and 6 nearly complete mitogenomes of mantises belonging to 8 families (Hymenopodidae, Iridopterygidae, Mantidae, Metallyticidae, Sibyllidae, Tarachodidae, Thespidae, Toxoderidae) using 14 pairs of mantid specific primer sets and found that 5 species of mantises have duplicate copies (2-4) of trnR: Ambivia undata, Creobroter jiangxiensis, Creobroter urbanus, Phyllothelys sp1. and Theopropus elegans while two novel gene arrangements CR-I-NCR-I-NCR-I-NCR-I-NCR-I-NCR*-Q-M and COII-K*-D*-K-D*-K-D*-K-D were found in Schizocephala bicornis and Stenotoxodera porioni, respectively. The multiple copies of trnR are caused by independent duplications. The gene arrangements in Stenotoxodera porioni with three identical copies of trnK can be explained as mid-way through the TDRL process while the form of gene arrangement in Schizocephala bicornis is unclear. In the phylogeny at the family level, the monophyly of Liturgusidae and Iridopterygidae was supported, whereas the monophyly of Hymenopodidae, Mantidae and Tarachodidae wasn't. The features of mantis mitochondrial genomes including high duplication rates of trnR, trnK and trnI indicate that Mantodea mitochondrial genomes maybe a useful model system for studying gene duplication. However, derived gene arrangements may not be appropriate for phylogenetic inference in Mantodea as they aren't synapomorphy and aren't shared by close relatives., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The mitochondrial genome of Fejervarya kawamurai is a circular molecule of 17,650 bp in length, containing 13 protein-coding genes, two rRNA genes, 23 tRNA genes (including an extra tRNA-Met), and the control region. The AT content of the whole genome is 56.9%. In Bayesian inference (BI) and Maximum likelihood (ML) analyses, we found that F. kawamurai is a sister clade to F. multistriata and F. limnocharis . The monophyly of Fejervarya , Quasipaa , Nanorana was well supported (1.00 in BI and 100% in ML)., Competing Interests: The authors declare no conflict of interest., (© 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

The complete mitochondrial genome of Isonychia kiangsinensis is a circular molecule of 15,456 bp in length, containing 2 rRNA genes, 13 protein-coding genes, 22 tRNA genes, and a control region. The AT content of the overall base composition is 62.9%. The length of the control region for I. kiangsinensis is 745 bp with 68.6% AT content. In BI and ML phylogenetic trees, Isonychia kiangsinensis was a sister clade to I. ignota and Isonychiidae was shown to be the basal clade of Ephemeroptera excluding Siphluriscidae. The monophyly of the families Isonychiidae, Heptageniidae, Viemamellidae, and Baetidae and the genus Isonychia were well supported., Competing Interests: The author reports no conflicts of interest. The author alone is responsible for the content and writing of the article., (© 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

The family Toxoderidae (Mantodea) contains an ecologically diverse group of praying mantis species that have in common greatly elongated bodies. In this study, we sequenced and compared the complete mitochondrial genomes of two Toxoderidae species, Paratoxodera polyacantha and Toxodera hauseri , and compared their mitochondrial genome characteristics with another member of the Toxoderidae, Stenotoxodera porioni (KY689118) . The lengths of the mitogenomes of T. hauseri and P. polyacantha were 15,616 bp and 15,999 bp, respectively, which is similar to that of S. porioni (15,846 bp). The size of each gene as well as the A+T-rich region and the A+T content of the whole genome were also very similar among the three species as were the protein-coding genes, the A+T content and the codon usages. The mitogenome of T. hauseri had the typical 22 tRNAs, whereas that of P. polyacantha had 26 tRNAs including an extra two copies of trnA - trnR . Intergenic regions of 67 bp and 76 bp were found in T. hauseri and P. polyacantha , respectively, between COX2 and trnK ; these can be explained as residues of a tandem duplication/random loss of trnK and trnD. This non-coding region may be synapomorphic for Toxoderidae. In BI and ML analyses, the monophyly of Toxoderidae was supported and P. polyacantha was the sister clade to T. hauseri and S. porioni ., Competing Interests: Kenneth B. Storey is an Academic Editor for PeerJ.