Structural features of the mitogenome of the leafhopper genus Cladolidia (Hemiptera: Cicadellidae: Coelidiinae) and phylogenetic implications in Cicadellidae

The first two complete mitogenomes of the leafhopper genus Cladolidia (C. biungulata and C. robusta) were sequenced and annotated to further explore the phylogeny of Cladolidia. Both the newly sequenced mitogenomes have a typical circular structure, with lengths of 15,247 and 15,376 bp and A + T contents of 78.2% and 78%, respectively. We identified a highly conserved genome organization in the two Cladolidia spp. through comparative analysis that included the following assessments: genome content, gene order, nucleotide composition, codon usage, amino acid composition, and tRNA secondary structure. Moreover, we detected the base heterogeneity of Cicadellidae mitogenomic data and constructed phylogenetic trees using the nucleotide alignments of 12 subfamilies of 58 leafhopper species. We noted a weak heterogeneity in the base composition among the Cicadellidae mitogenomes. Phylogenetic analyses showed that the monophyly of each subfamily was generally well supported in the family Cicadellidae; the main topology was as follows: (Deltocephalinae + (Treehoppers + ((Megophthalminae + (Macropsinae + (Hylicinae + (Coelidiinae +Iassinae)) + (Idiocerinae + (Cicadellinae + (Typhlocybinae + (Mileewinae + (Evacanthinae +Ledrinae)))))))))). Within Coelidiinae, phylogenetic analyses revealed that C. biungulata and C. robusta belong to Coelidiinae and the monophyly of Cladolidia is well supported. In addition, on the basis of complete mitogenome phylogenetic analysis and the comparison of morphological characteristics, we further confirm the genus Olidiana as a paraphyletic group, suggesting that the genus may need taxonomic revisions.     

The mitogenomes of three beetles (Coleoptera: Polyphaga: Cucujiformia): New gene rearrangement and phylogeny

The mitochondrial genome (mitogenome) has been extensively used for studying phylogenetic relationships at different taxonomic levels. Several molecular analyses have been performed, but the phylogenetic relationships among infraorders in Polyphaga have not been well resolved. In this work, three nearly complete mitogenomes of Coleoptera, Sitophilus oryzae, Oryzaephilus surinamensis and Callosobruchus chinensis, were determined. The O. surinamensis and S. oryzae mitogenomes harbor gene content typical of other Polyphaga mitogenomes, while a gene rearrangement (trnQ) was found in the C. chinensis mitogenome. The mitogenomes of these three Coleoptera species each consist of approximately 13 protein-coding genes, 22 tRNA genes, two rRNA genes and one A + T-rich region. Phylogenetic analysis within Polyphaga was carried out based on mitochondrial data. The phylogenetic results within Polyphaga support the basal position of Cyphon sp., which belonged to Scirtoidea, Elateriformia. Within Cucujiformia, monophyletic Curculionoidea, Chrysomeloidea and Tenebrionoidea were confirmed.     

Comparative Analysis of Mitochondrial Genomes of Five Aphid Species (Hemiptera: Aphididae) and Phylogenetic Implications

Insect mitochondrial genomes (mitogenomes) are of great interest in exploring molecular evolution, phylogenetics and population genetics. Only two mitogenomes have been previously released in the insect group Aphididae, which consists of about 5,000 known species including some agricultural, forestry and horticultural pests. Here we report the complete 16,317 bp mitogenome of Cavariella salicicola and two nearly complete mitogenomes of Aphis glycines and Pterocomma pilosum. We also present a first comparative analysis of mitochondrial genomes of aphids. Results showed that aphid mitogenomes share conserved genomic organization, nucleotide and amino acid composition, and codon usage features. All 37 genes usually present in animal mitogenomes were sequenced and annotated. The analysis of gene evolutionary rate revealed the lowest and highest rates for COI and ATP8, respectively. A unique repeat region exclusively in aphid mitogenomes, which included variable numbers of tandem repeats in a lineage-specific manner, was highlighted for the first time. This region may have a function as another origin of replication. Phylogenetic reconstructions based on protein-coding genes and the stem-loop structures of control regions confirmed a sister relationship between Cavariella and pterocommatines. Current evidence suggest that pterocommatines could be formally transferred into Macrosiphini. Our paper also offers methodological instructions for obtaining other Aphididae mitochondrial genomes.     

Mitochondrial genomes of five Hyphessobrycon tetras and their phylogenetic implications

To date, the taxonomic status and phylogenetic affinities within Hyphessobrycon, even among other genera in Characidae, remain unclear. Here, we determined five new mitochondrial genomes (mitogenomes) of Hyphessobrycon species (H. elachys, H. flammeus, H. pulchripinnis, H. roseus, and H. sweglesi). The mitogenomes were all classical circular structures, with lengths ranging from 16,008 to 17,224 bp. The type of constitutive genes and direction of the coding strand that appeared in the mitogenomes were identical to those of other species in Characidae. The highest value of the Ka/Ks ratio within 13 protein‐coding genes (PCGs) was found in ND2 with 0.83, suggesting that they were subject to purifying selection in the Hyphessobrycon genus. Comparison of the control region sequences among seven Hyphessobrycon fish revealed that repeat units differ in length and copy number across different species, which led to sharp differences in mitogenome sizes. Phylogenetic trees based on the 13 PCGs did not support taxonomic relationships, as the Hyphessobrycon fish mixed with those from other genera. These data were combined to explore higher level relationships within Characidae and could aid in the understanding of the evolution of this group.     

Comparative analysis of mitochondrial genomes of Nirvanini and Evacanthini (Hemiptera: Cicadellidae) reveals an explicit evolutionary relationship

Mitogenomes of five leafhopper species, Chudania hellerina and Concaveplana rufolineata in Nirvanini, Carinata rufipenna, Evacanthus danmainus and E. heimianus representing Evacanthini, were sequenced. The lengths of these five mitogenomes range from 15,044 (C. hellerina) to 15,680 bp (E. heimianus). All five mitogenomes exhibit similar base composition, gene size and codon usage of protein-coding genes. All 22 tRNA genes have typical cloverleaf secondary structures, except for trnS1 (AGN) which appears to lack the dihydrouridine arm. The two included Nirvanini species employ the anticodon TCT instead of the commonly used GCT in trnS1 (AGN). Genes nad2, atp8 and nad6 were highly variable while cox1 and cob showed the lowest nucleotide diversity. Phylogenetic analyses of two concatenated nucleotide datasets, incorporating the newly sequenced taxa and other available membracoid mitogenomes, recovered each included leafhopper subfamily as monophyletic with evacanthine tribes Nirvanini and Evacanthini forming monophyletic sister clades. A relationship among Evacanthinae, Cicadellinae and Typhlocybinae received moderate branch support.     

Characterization of the complete mitogenome of Trachylophus sinensis (Coleoptera: Cerambycidae: Cerambycinae), the type species of Trachylophus and its phylogenetic implications

Complete mitochondrial genomes (mitogenomes) have long been proved as reliable markers for phylogenetic reconstruction among diverse animal groups, especially benefited from recent rapid development of sequencing techniques. However, the mitogenomes of many important clades remain poorly represented, which restricted the understanding of macroscale evolutionary history of these groups. Here, we sequenced and characterized the complete mitogenome of Trachylophus sinensis, a type species of the Trachylophus genus, which also represents the first sequenced mitogenome in this genus. The complete circular mitogenome was 15,746 bp in length, containing 37 typical genes and one noncoding AT-rich control region. The nucleotide composition of the mitogenome was highly A + T biased, accounting for 70.07 % of the whole mitogenome with a slightly positive AT skewness (0.106). The 13 Protein coding genes (PCGs) used ATN as their start codons, except nad1 which used TTG. All tRNA genes were predicted with a characteristic cloverleaf secondary structure except trnS1^(AGN), whose dihydrouridine (DHU) arm was replaced by a simple loop. Phylogenetic analyses recovered Cerambycinae as a monophyletic group with high node supports and the sister relationship between T. sinensis and Nadezhdiella cantori. However, we found that deeper nodes showed not strong support, which may be caused by limited taxa sampling in our study. More mitogenomes should be sequenced representing various taxonomic levels, especially closely related species, which will enhance our understanding of phylogenetic relationships among Cerambycinae.     

The complete mitochondrial genome of Mahanta tanyae compared with other zygaenoid moths (Lepidoptera: Zygaenoidea)

The complete mitochondrial genome (mitogenome) of Mahanta tanyae was sequenced and extensively compared with all seven additionally reported zygaenoid mitogenomes. The M. tanyae mitogenome is circular, double-stranded, and 15,323 bp long. Gene content, gene order, and orientation are all typical of Lepidoptera, despite the existence of gene rearrangements for some other zygaenoid mitogenomes. Comparative analyses further showed that the incomplete termination codon T is consistently recognized in the mitochondrial cox1, cox2 and nad4 genes of all zygaenoid species, as well as in the nad5 gene in two limacodid species. Among 13 protein-coding genes, nad6 exhibits the highest evolutionary rate. The structure for each tRNA is highly conserved, including loss of the dihydorouidine (DHU) arm in trnS1 (AGN), but remarkable nucleotide variation exists, primarily in the pseudouridine (TψC) loops. Interestingly, in four species of Zygaenidae, the anticodons for trnS1 (AGN) are consistently UCU, instead of the routinely used codon GCU, in all three species of Limacodidae. In the intergenic region between trnS2 and nad1, a short sequence before the motif “ATACTAA” is present in the M. tanyae mitogenome that is unique among reported zygaenoid mitogenomes. In the A + T-rich region between the motif “ATTTA” and the microsatellite (AT)_n element, some nucleotides were present for most zygaenoid mitogenomes, which is, to our knowledge, rare even in reported lepidopteran mitogenomes. Phylogenetic analyses based on the combined 37 mitochondrial genes confirmed the position of M. tanyae in Limacodidae of the Zygaenoidea.     

Evolutionary relatedness of mackerels of the genus Scomber based on complete mitochondrial genomes: Strong support to the recognition of Atlantic Scomber colias and Pacific Scomber japonicus as distinct species

Mackerels of the genus Scomber are commercially important species, but their taxonomic status is still controversial. Although previous phylogenetic data support the recognition of Atlantic Scomber colias and Pacific Scomber japonicus as separate species, it is only based on the analysis of partial mitochondrial and nuclear DNA sequences. In an attempt to shed light on this relevant issue, we have determined the complete mitochondrial DNA sequence of S. colias, S. japonicus, and Scomber australasicus. The total length of the mitogenomes was 16,568 bp for S. colias and 16,570 bp for both S. japonicus and S. australasicus. All mitogenomes had a gene content (13 protein-coding, 2 rRNAs, and 22 tRNAs) and organization similar to that observed in Scomber scombrus and most other vertebrates. The major noncoding region (control region) ranged between 865 and 866 bp in length and showed the typical conserved blocks. Phylogenetic analyses revealed a monophyletic origin of Scomber species with regard to other scombrid fish. The major finding of this study is that S. colias and S. japonicus were significantly grouped in distinct lineages within Scomber cluster, which phylogenetically constitutes evidence that they may be considered as separate species. Additionally, molecular data here presented provide a useful tool for evolutionary as well as population genetic studies.     

Complete mitochondrial genome of the hemp borer,Grapholita delineana (Lepidoptera: Tortricidae): Gene variability and phylogeny among Grapholita

The mitochondrial genome (mitogenome) has been extensively used in phylogenetics and species-level evolutionary investigations. The lepidopteran family Tortricidae (leaf-roller moths), including the genus Grapholita, contains numerous species of economic importance, but for the majority of Grapholita species, their mitogenomes remain poorly studied. Here, we sequence and annotate the full mitogenome of Grapholita delineana, an important pest of hemp worldwide and compare it with the mitogenomes of two congeneric species available from GenBank. The G. delineana mitogenome is 15,599 bp long, including 37 typical mitochondrial genes and an A + T-rich region. Gene content, order and orientation are identical to other reported tortricid mitogenomes. Analyses of nucleotide diversity, Ka/Ks, genetic distance and number of variable sites together suggest that nad6 is the fastest-evolving gene among the mitochondrial PCGs of Grapholita. Our analyses indicate that Grapholita, as presently defined, is not monophyletic, confirming previous morphological and multiple-gene studies, using mitogenomic evidence. Our study provides information on comparative mitogenomics of Tortricidae especially Grapholita.     

Sequence comparison of the mitochondrial genomes of five brackish water species of the family Neritidae: Phylogenetic implications and divergence time estimation

Neritids are ancient gastropod species which can live in marine, brackish water, and freshwater environments. In this study, we sequenced and annotated the mitochondrial genomes of five brackish water neritids (i.e., Clithon corona, Clithon lentiginosum, Clithon squarrosum, Neritina iris, and Septaria lineata). The mitogenomes ranged from 15,618 to 15,975 bp, and all contain 13 protein‐coding genes (PCGs), 22 tRNA genes, and two rRNA genes, with a closed ring structure. We calculated the Ka/Ks values of all 13 PCGs of Neritidae species, all ratios are less than 1, under purification selection. Phylogenetic analysis of the 13 PCGs showed that Neritimorpha is a sister group with Vetigastropoda and Caenogastopoda, genus Clithon is a sister group with Neritina and Septaria. Estimation of divergence time for all species of Neritidae showed that the main differentiation of Neritidae occurred in Cenozoic period (65 Mya), C. corona and C. lentiginosum were differentiated in the Cenozoic Neogene, the other three species diverged in the Cenozoic Paleogene. These results will help to better understand the evolutionary position of Neritidae and provide reference for further phylogenetic research on Neritidae species.     

The complete mitochondrial genome of cricket Sclerogryllus punctatus (Orthoptera: Gryllidae) and phylogenetic analysis

The crickets of genus Sclerogryllus Gorochov, 1985 belongs to subfamily Sclerogryllinae of family Gryllidae. In this study, we report the first complete mitogenome sequences of the genus Sclerogryllus, and analyze the features of mitogenomes of S. punctatus. The mitogenome of S. punctatus was 15,438 bp and consisted of 37 genes, coding for 13 proteins, 2 ribosomal RNA (rRNA) and 22 transfer RNA (tRNA), and a control region. S. punctatus shares the arrangement of trnE-trnS-trnN with most mitogenomes of Grylloidea. Besides, the tRNAs possess the typical cloverleaf secondary structure except for the trnS1 (AGN) gene. The phylogenetic analysis using 13 protein-coding genes and 2 rRNA represents that genus Sclerogryllus is included in subfamily Gryllinae. Our results uncover the phylogenetic position of genus Sclerogryllus by mitogenome data within the family Gryllidae.     

Characterization of the complete mitochondrial genome of Drawida gisti (Metagynophora,Moniligastridae) and comparison with other Metagynophora species

Here, the complete mitochondrial genome (mitogenome) of Drawida gisti was sequenced and compared with the mitogenomes of other Metagynophora species. The circular mitogenome was 14,648 bp in length and contained two ribosomal RNA genes (rRNAs), 13 protein-coding genes (PCGs), and 22 transfer RNA genes (tRNAs). The types of constitutive genes and the direction of the coding strand that appeared in Drawida mitogenome were identical to those observed in other Metagynophora species, except for a missing lengthy non-coding region. The conservative relationships between Drawida species were supported by the overall analyses of 13 PCGs, two rRNAs, and 22 tRNAs. A comparison of the Metagynophora mitogenomes revealed that the ATP8 gene possessed the highest polymorphism among the 13 PCGs and two rRNAs. Phylogenetic analysis suggested that the Moniligastridae contained Drawida, which is a primitive Metagynophora group. Our study provides a step forward toward elucidating the evolutionary linkages within Drawida and even Metagynophora.     

球孢白僵菌种内比较线粒体基因组学分析

【目的】明确球孢白僵菌种内线粒体基因组的分化程度。【方法】从GenBank下载已知的球孢白僵菌6个菌株线粒体基因组序列,详细分析基因组的组成结构,比较外显子区、内含子区和基因间区的碱基变异情况,分析菌株间的系统发育关系。【结果】球孢白僵菌不同菌株的线粒体基因组大小为28.8–32.3 kb,都有14个常见的核心蛋白编码基因、2个rRNA基因和25个tRNA基因,具有很强的共线性关系。但是,不同菌株含有的线粒体内含子数目存在差异(2–5个/菌株),在cox1、cox2和nad1基因中表现出内含子插入/缺失多态性,这是导致线粒体基因组大小变化的主要因素。对外显子、内含子和基因间区的碱基变异情况进行分析,发现内含子和基因间区相对变异较大,而外显子区相对变异较小。系统发育分析发现,这些球孢白僵菌菌株以很高的支持度聚在一起,具有相同内含子分布规律的菌株也具有较近的聚类关系。【结论】本研究首次报道球孢白僵菌因内含子数目不同、插入缺失突变和单核苷酸变异等在线粒体基因组上表现出较大程度的遗传分化,为认识真菌种内线粒体基因组分化提供了新的证据。     

Mitochondrial DNA Genomes Organization and Phylogenetic Relationships Analysis of Eight Anemonefishes (Pomacentridae: Amphiprioninae)

Anemonefishes (Pomacentridae Amphiprioninae) are a group of 30 valid coral reef fish species with their phylogenetic relationships still under debate. The eight available mitogenomes of anemonefishes were used to reconstruct the molecular phylogenetic tree; six were obtained from this study (Amphiprion clarkii, A. frenatus, A. percula, A. perideraion, A. polymnus and Premnas biaculeatus) and two from GenBank (A. bicinctus and A. ocellaris). The seven Amphiprion species represent all four subgenera and P. biaculeatus is the only species from Premnas. The eight mitogenomes of anemonefishes encoded 13 protein-coding genes, two rRNA genes, 22 tRNA genes and two main non-coding regions, with the gene arrangement and translation direction basically identical to other typical vertebrate mitogenomes. Among the 13 protein-coding genes, A. ocellaris (AP006017) and A. percula (KJ174497) had the same length in ND5 with 1,866 bp, which were three nucleotides less than the other six anemonefishes. Both structures of ND5, however, could translate to amino acid successfully. Only four mitogenomes had the tandem repeats in D-loop; the tandem repeats were located in downstream after Conserved Sequence Block rather than the upstream and repeated in a simply way. The phylogenetic utility was tested with Bayesian and Maximum Likelihood methods using all 13 protein-coding genes. The results strongly supported that the subfamily Amphiprioninae was monophyletic and P. biaculeatus should be assigned to the genus Amphiprion. Premnas biaculeatus with the percula complex were revealed to be the ancient anemonefish species. The tree forms of ND1, COIII, ND4, Cytb, Cytb+12S rRNA, Cytb+COI and Cytb+COI+12S rRNA were similar to that 13 protein-coding genes, therefore, we suggested that the suitable single mitochondrial gene for phylogenetic analysis of anemonefishes maybe Cytb. Additional mitogenomes of anemonefishes with a combination of nuclear markers will be useful to substantiate these conclusions in future studies.     

The mitochondrial genome of Gatzara jezoensis (Neuroptera: Myrmeleontidae) and phylogenetic analysis of Neuroptera

Phylogenetic relationship within Neuroptera is controversial, particularly for the various hypotheses based on both morphological and molecular evidence. In the present study, we determined the complete mitochondrial genome (mitogenome) of Gatzara jezoensis, which is the second representative of the tribe Dendroleontini. The G. jezoensis mitogenome contained the conserved set of 37 mitochondrial genes and a putative control region, with a conserved gene arrangement which was similar to that of most sequenced neuropteran mitogenomes. All transfer RNAs exhibited the canonical cloverleaf secondary structure, except for trnS^(AGN). The control region contained two conserved elements (ploy-T stretch and ATGGTTCAAYAAAATAAYYCYCTC motif) and abundant microsatellite-like elements. The phylogenetic analysis of sequenced neuropteran mitogenomes using the concatenated protein-coding genes (PCGs) and ribosomal genes recovered the monophyly of Myrmeleontidae, which revealed this dataset could generate the more robust phylogeny of Neuroptera than that of 13 PCGs dataset.     

Next-generation sequencing,phylogenetic signal and comparative mitogenomic analyses in Metacrangonyctidae (Amphipoda: Crustacea)

Background

Comparative mitochondrial genomic analyses are rare among crustaceans below the family or genus level. The obliged subterranean crustacean amphipods of the family Metacrangonyctidae, found from the Hispaniola (Antilles) to the Middle East, including the Canary Islands and the peri-Mediterranean region, have an evolutionary history and peculiar biogeography that can respond to Tethyan vicariance. Indeed, recent phylogenetic analysis using all protein-coding mitochondrial sequences and one nuclear ribosomal gene have lent support to this hypothesis (Bauzà-Ribot et al. 2012).

Results

We present the analyses of mitochondrial genome sequences of 21 metacrangonyctids in the genera Metacrangonyx and Longipodacrangonyx, covering the entire geographical range of the family. Most mitogenomes were attained by next-generation sequencing techniques using long-PCR fragments sequenced by Roche FLX/454 or GS Junior pyro-sequencing, obtaining a coverage depth per nucleotide of up to 281×. All mitogenomes were AT-rich and included the usual 37 genes of the metazoan mitochondrial genome, but showed a unique derived gene order not matched in any other amphipod mitogenome. We compare and discuss features such as strand bias, phylogenetic informativeness, non-synonymous/synonymous substitution rates and other mitogenomic characteristics, including ribosomal and transfer RNAs annotation and structure.

Conclusions

Next-generation sequencing of pooled long-PCR amplicons can help to rapidly generate mitogenomic information of a high number of related species to be used in phylogenetic and genomic evolutionary studies. The mitogenomes of the Metacrangonyctidae have the usual characteristics of the metazoan mitogenomes (circular molecules of 15,000-16,000 bp, coding for 13 protein genes, 22 tRNAs and two ribosomal genes) and show a conserved gene order with several rearrangements with respect to the presumed Pancrustacean ground pattern. Strand nucleotide bias appears to be reversed with respect to the condition displayed in the majority of crustacean mitogenomes since metacrangonyctids show a GC-skew at the (+) and (-) strands; this feature has been reported also in the few mitogenomes of Isopoda (Peracarida) known thus far. The features of the rRNAs, tRNAs and sequence motifs of the control region of the Metacrangonyctidae are similar to those of the few crustaceans studied at present.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-566) contains supplementary material, which is available to authorized users.     

The complete mitochondrial genome of Diaphorina citri (Hemiptera: Psyllidae) and phylogenetic analysis

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is the most serious pest of citrus as the vector of Huanglongbing (HLB), the citrus greening disease. In this study, the complete mitochondrial genome (mitogenome) of D. citri has been sequenced and annotated, and a comparative analysis is provided with known Psylloidea species. The mitogenome of D. citri is a typical circular molecular of 15,038 bp in length with an A + T content of 74.56%, contains the typical 37 genes and the gene order is identical to the other Psylloidea mitogenomes. The nucleotide composition and codon usage of D. citri are similar to the four Psylloidea species. All protein-coding genes (PCGs) use standard initiation codons (TAN), stop with TAA and TAG except ND2 and ND5 which stop with incomplete termination codon T. All tRNAs have the typical clover-leaf structure, with the exception of trnS1 lacking the dihydrouridine (DHU) arm. The control region is located between rrnL and the trnI gene with the highest A + T content among the five Psylloidea species. Phylogenetic analysis is conducted based on the 13 PCGs or/and 2 rRNAs of 23 Sternorrhycha mitogenomes. Both maximum likelihood (ML) and Bayesian inference (BI) analysis suggest a clear relationship of Psylloidea, Aleyrodoidea and Aphidoidea within Sternorrhycha, which support the traditional morphological classification.     

Description of five novel thermophilic species of the genus Thermus: Thermus hydrothermalis sp. nov., Thermus neutrinimicus sp. nov., Thermus thalpophilus sp. nov., Thermus albus sp. nov., and Thermus altitudinis sp. nov., isolated from hot spring sediments

Biological denitrification is a significant process in nitrogen biogeochemical cycle of terrestrial geothermal environments, and Thermus species have been shown to be crucial heterotrophic denitrifier in hydrothermal system. Five Gram-stain negative, aerobic and rod-shaped thermophilic bacterial strains were isolated from hot spring sediments in Tibet, China. Phylogenetic analysis based on 16S rRNA gene and whole genome sequences indicated that these isolates should be assigned to the genus Thermus and were most closely related to Thermus caldifontis YIM 73026^T, and Thermus brockianus YS38^T. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the five strains and the type strains of the genus Thermus were lower than the threshold values (95% and 70%, respectively) recommended for bacterial species, which clearly distinguished the five isolates from other species of the genus Thermus and indicated that they represent independent species. Colonies are circular, convex, non-transparent. Cell growth occurred at 37–80 °C (optimum, 60–65 °C), pH 6.0–8.0 (optimum, pH 7.0) and with 0–2.0% (w/v) NaCl (optimum, 0–0.5%). Denitrification genes (narG, nirK, nirS, and norB genes) detected in their genomes indicated their potential function in nitrogen metabolism. The obtained results combined with those of morphological, physiological, and chemotaxonomic characteristics, including the menaquinones, polar lipids, and cellular fatty acids showed that the isolates are proposed as representing five novel species of the genus Thermus, which are proposed as Thermus hydrothermalis sp. nov. SYSU G00291^T, Thermus neutrinimicus sp. nov. SYSU G00388^T, Thermus thalpophilus sp. nov. SYSU G00506^T, Thermus albus sp. nov. SYSU G00608^T, Thermus altitudinis sp. nov. SYSU G00630^T.     

The Complete Mitochondrial Genome of two Tetragnatha Spiders (Araneae: Tetragnathidae): Severe Truncation of tRNAs and Novel Gene Rearrangements in Araneae

Mitogenomes can provide information for phylogenetic analysis and evolutionary biology. The Araneae is one of the largest orders of Arachnida with great economic importance. In order to develop mitogenome data for this significant group, we determined the complete mitogenomes of two long jawed spiders Tetragnatha maxillosa and T. nitens and performed the comparative analysis with previously published spider mitogenomes. The circular mitogenomes are 14578 bp long with A+T content of 74.5% in T. maxillosa and 14639 bp long with A+T content of 74.3% in T. nitens, respectively. Both the mitogenomes contain a standard set of 37 genes and an A+T-rich region with the same gene orientation as the other spider mitogenomes, with the exception of the different gene order by the rearrangement of two tRNAs (trnW and trnG). Most of the tRNAs lose TΨC arm stems and have unpaired amino acid acceptor arms. As interesting features, both trnS^AGN and trnS^UCN lack the dihydrouracil (DHU) arm and long tandem repeat units are presented in the A+T-rich region of both the spider mitogenomes. The phylogenetic relationships of 23 spider mitogenomes based on the concatenated nucleotides sequences of 13 protein-coding genes indicated that the mitogenome sequences could be useful in resolving higher-level relationship of Araneae. The molecular information acquired from the results of this study should be very useful for future researches on mitogenomic evolution and genetic diversities in spiders.