Termination-associated Sequence Research Articles

Complete mitochondrial genome sequence of E. suratensis revealed by next generation sequencing

The complete mitochondrial genome of Etroplus suratensis, the Green chromide cichlid, was determined for the first time through NGS method. The genome is 16,467 bp (Accession no. KU301747) in length and consisted of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and one control region. Organization of genes and their order are in accordance with other vertebrates. The overall base composition on plus strand was A: 28.3%, G: 15.2%, C: 30.9%, T: 25.6%, and the A + T content 53.9%. The control region contains a putative termination-associated sequence and three conserved sequence blocks. This mitogenome sequence data would play an important role in population genetics and phylogenetics of cichlid fish of India.

Phylogenetic analysis of the Mongolian gerbil (Meriones unguiculatus) from China based on mitochondrial genome.

Meriones unguiculatus (Gerbillinae, Rodentia) is widely used as an animal model of human disease. Here, we provide the first report of the complete mitochondrial genome sequence of M. unguiculatus (GenBank accession Nos. KF425526 and NC_023263). The sequence contained the conserved vertebrate pattern of 13 protein-coding genes, 2 ribosomal RNAs, 22 transfer RNAs, and 1 major noncoding region. We identified one extended termination-associated sequence and one conserved sequence block in the non-coding region. The putative origin of replication for the light strand (OL) was 35 bp long. The OL stem and adjacent sequences were highly conserved, but the loop region differed from those of other rodent species. Base composition and codon usage of the 13 protein-coding genes in M. unguiculatus were compared with those of 23 rodent species with previously sequenced mitochondrial genomes. An A+T content of 63.0% was present in M. unguiculatus; this is similar to the Murinae average (62.4 ± 0.8%) and falls between the average for Mus musculus (63.1 ± 0.1%) and Rattus sp (61.7 ± 0.4%). The AT and GC skew values of M. unguiculatus were 0.035 and -0.28, respectively, similar to those of Cricetinae species (0.057 ± 0.05 and -0.31 ± 0.05). The codon families exhibited similar abundance in all 24 species. Analysis of phylogenetic relationships with 23 other rodent species using neighbor-joining and maximum likelihood protocols and the 12 protein-coding regions on the H strand showed that M. unguiculatus should be classified as genus Meriones, sub-family Gerbillinae, family Muridae.

Strictly conserved tri-nucleotide motif “CAT” is associated with TAS DNA protein-binding sites in human mitochondrial DNA control region

The mitochondrial DNA (mtDNA) control region is a highly variable segment that contains functional elements that control mtDNA transcription and replication. By analysis of the polymorphic nucleotide spectrum of that segment, we aimed to identify the most conserved sites that should be associated with these elements. For that aim, we analyzed 50 033 human mtDNA control region sequences (mtDNA positions 16 066–16 374). We identified 10 conserved tri-nucleotides, one conserved tetra-nucleotide, and one conserved penta-nucleotide, containing six repetitions of the motif CAT, and two of its complement motif ATG (p value < 2 × 10 − 4). Three other appearances of the tri-nucleotide CAT were almost perfectly preserved. The positions of the preserved CAT elements are associated with the location of previously identified termination-associated sequences (TAS) which are the binding locations for proteins involved in mtDNA replication. We, therefore, hypothesize that the CAT tri-nucleotide elements within the control region may be the binding sites for TAS proteins and are directly involved in mtDNA transcription and replication.

Complete mitochondrial genome of black-banded trevally (Seriolina nigrofasciata): Genome characterization and phylogenetic considerations

The black-banded trevally (Seriolina nigrofasciata) is a species of the family Carangidae and the only known member of genus Seriolina. To understand the phylogenetic relationship of black-banded trevally in teleost, we first determined the complete mitochondrial genome of black-banded trevally. The entire mitochondrial genome of black-banded trevally is 16 531 bp in length, containing 13 protein-coding genes and 2 ribosomal RNA genes (rRNA), 22 transfer RNA genes (tRNAs), and 2 main non-coding regions. The overall base composition is T 25.8%, C 30.0%, A 26.7%, and G 17.5%. The gene arrangement, base composition, and tRNA structures of black-banded trevally are consistent with those of other teleost. Two of the central conserved sequence blocks (CSB-2 and CSB-3) were identified and the core sequence (TACATGTATGTA) of terminal-associated sequences was recognized in the control region. Meanwhile, the conserved motif 5′-GCCGG-3′ was identified in the origin of light-strand replication of black-banded trevally. The complete mitochondrial genome of black-banded trevally was used to construct phylogenetic tree, which shows that black-banded trevally is clustered with the fishes of the genus Seriola. We expect that the availability of the mitochondrial genome of black-banded trevally will facilitate the further investigations of molecular systematic and phylogenetic analysis of the Carangidae.

Complete mitochondrial genome of the Loligo beka

In this study, we determined the complete mitochondrial genome of Loligo beka. The genome was 17 483 bp in length and contained 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and three main non-coding regions. The overall base composition of L.beka is A 40.35%, T 32.53%, C 18.53%, and G 8.58%, with a highly A + T bias of 72.89%. All the three control regions (CR) contain termination-associated sequences and conserved sequence blocks. Here we describe a phylogenetic analysis of 11 species cephalopoda based on the complete mitochondrial genome, the result showed that the Loliolus uyii is most closely related to L. beka. This mitogenome sequence data would play an important role in the investigation of phylogenetic relationship, taxonomic resolution and phylogeography of the cephalopoda.

The first complete mitochondrial genome of Serranidae sp. (Percoidea, Serranidae) and phylogenetic analysis based on Bayesian

In the present study, the complete mitochondrial genome of Serranidae sp. was determined first. The entire mitochondrial genome of Serranidae sp. is 16 512 bp in length, containing 13 protein-coding genes and 2 ribosomal RNA genes (rRNA), 22 transfer RNA genes (tRNA) and 2 main non-coding regions (the control region and the origin of the light-strand replication). The gene arrangement, base composition and tRNA structures of Serranidae sp. are similar to most of the bony fishes. The central conserved sequence blocks (CSB-1, CSB-2, and CSB-3) and the core sequence (ACATATATGT) of terminal-associated sequences were recognized in the control region. Meanwhile, the conserved motif 5′-GCCGG-3′ was identified in the origin of light-strand replication of Serranidae sp. Phylogenetic tree, which is constructed based on the complete mitochondrial genome sequences of Serranidae sp., shows that Serranidae sp. is clustered with the fishes of the family Pentacerotidae. We expect that the mitochondrial genome of Serranidae sp. would play a key role in phylogenetic analysis of Serranidae.

Complete mitochondrial genome of banjofish (Banjos banjos): genome characterization and phylogenetic analysis

The banjofish (Banjos banjos) is the only species in the monotypic genus Banjos and in the family Banjosidae. To understand the phylogenetic relationship of banjofish in teleost, we firstly determined the complete mitochondrial genome of banjofish. The entire mitochondrial genome of banjofish is 16 485 bp in length, including 13 protein-coding genes and 2 ribosomal RNA genes (rRNA), 22 transfer RNA genes (tRNA) and a control region (CR). The overall base composition is T, 26.2%; C, 29.2%; A, 28.6% and G, 16.0%. The central conserved sequence blocks (CSB) were identified and the core sequence (ACATATATGT) of terminal-associated sequences was recognized in the control region. The gene arrangement, base composition, and tRNA structures of the complete mitochondrial genome of banjofish is consistent with those of other teleost. The complete mitochondrial genome of banjofish was used to construct phylogenetic tree, which shows that banjofish is clustered with the fishes of the family Histiopteridae. We expect that the availability of mitochondrial genome of banjofish will facilitate the further investigations of the taxonomic resolution, biogeography and molecular systematic.

Complete mitochondrial genome and phylogenic analysis of the mudskipper Scartelaos gigas (Perciformes, Gobiidae)

In this paper, the complete mitochondrial genome sequence of Scartelaos gigas was firstly determined. The circular genome (16 717 bp) comprises 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and 1 control region. The overall base composition of S. gigas is 28.9% for C, 28.3% for A, 26.4% for T, 16.4% for G, with a slight A + T bias of 54.7%. In the control region, the termination-associated sequence and conserved sequence block domains were found, but the tandem repeat structure was not found. It has the typical vertebrate mitochondrial gene arrangement. The phylogenic analysis using the Neighbor-Joining method showed that the fishes belonging to Gobiidae, Odontoburidae, and Eleotridae formed three branches grouped with other fishes into one clade which separated from the mammals. We hope that the results from the present study will provide useful molecular information for the further studies on genetic structure and demographic history of S. gigas.

The mitochondrial genome of Schizothorax esocinus (Cypriniformes: Cyprinidae) from Northern Pakistan

The mitochondrial DNA sequence represents a mainstay of phylogenetics. It allows biologists to elucidate the evolutionary relationships among species. It also permits an examination of the relatedness of populations, hence got importance in the field of biology. The current study was designed to know the mitochondrial sequence of Schizothorax esocinus, a delicious fish belonging to family Cyprinidae. In this study, the complete mitochondrial genome of S. esocinus from Northern Pakistan was determined. The mitogenome of S. esocinus was found to be 16 591 bp in length and consisted of 13 protein coding genes, 22 tRNA genes, two rRNA genes, and one control region. All genes were encoded on heavy strain except ND6 and few tRNA genes. The overall base composition was T 25.5%, C 27.0%, A 29.8% and G 17.7%, A + T content 55.3% and G + C content 47.7%. The length of control region (CR) was 938 bp and contained putative termination-associated sequence (TAS) and several conserved sequence blocks (CSB) and control region also contained a microsatellite region (TA). This is the very first study reported from a reservoir of large cold water bodies in Pakistan which have a great potential for conservation of cold water fish species. This mitogenome sequence would be useful to know the phylogenetic status of the fish.

Live sharksucker Echeneis naucrates (Linnaeus 1758) mitochondrial genome: the first report of Echeneidae complete mitochondrial genome

The complete mitochondrial genome of Echeneis naucrates is 16,611 bp in length. It comprises a control region, 13 protein-coding genes, 2 ribosomal RNAs (rRNAs) and 22 transfer RNAs (tRNAs), with an arrangement typical of vertebrate mitochondrial genomes. Base composition on the heavy strand is 30.24% A, 25.45% C, 15.02% G and 29.29% T. The control region is 940 bp in length, containing putative termination associated sequences (TASs) and conserved sequence blocks (CSBs). Two copies of a tandem repeat (AATATTAT) were found in all six individuals investigated. The hypothesis of selection for an optimal number of repeats as well as the evolutionary dynamics of tandem repeats in E. naucrates control regions await further investigations.

Concerted Evolution of Duplicate Control Regions in the Mitochondria of Species of the Flatfish Family Bothidae (Teleostei: Pleuronectiformes).

Mitogenomes of flatfishes (Pleuronectiformes) exhibit the greatest diversity of gene rear-rangements in teleostean fishes. Duplicate control regions (CRs) have been found in the mito-genomes of two flatfishes, Samariscus latus (Samaridae) and Laeops lanceolata (Bothidae), which is rare in teleosts. It has been reported that duplicate CRs have evolved in a concerted fashion in fishes and other animals, however, whether concerted evo-lution exists in flatfishes remains unknown. In this study, based on five newly sequenced and six previously reported mitogenomes of lefteye flounders in the Bothidae, we explored whether duplicate CRs and concerted evolution exist in these species. Results based on the present study and previous reports show that four out of eleven bothid species examined have duplicate CRs of their mitogenomes. The core regions of the duplicate CRs of mitogenomes in the same species have identical, or nearly identical, sequences when compared to each other. This pattern fits the typical characteristics of concerted evolution. Additionally, phylogenetic and ancestral state reconstruction analysis also provided evidence to support the hypothesis that duplicate CRs evolved concertedly. The core region of concerted evolution is situated at the conserved domains of the CR of the mitogenome from the termination associated sequences (TASs) to the conserved sequence blocks (CSBs). Commonly, this region is con-sidered to regulate mitochondrial replication and transcription. Thus, we hypothesize that the cause of concerted evolution of the duplicate CRs in the mtDNAs of these four bothids may be related to some function of the conserved sequences of the CRs during mitochondrial rep-lication and transcription. We hope our results will provide fresh insight into the molecular mechanisms related to replication and evolution of mitogenomes.

The complete mitochondrial genome of Sillago sihama (Perciformes: Sillaginidae)

In this study, the complete mitochondrial genome (mitogenome) sequence of Sillago sihama has been determined by long polymerase chain reaction and primer walking methods. The complete mitochondrial genome is a circular molecule of 17 003 bp in length and contains 37 mitochondrial genes and a control region. Within the control region, we identified the variable number tandem repeats, as well as the termination-associated sequence domain (TAS), the central conserved sequence block domains (CSB-F∼CSB-A) and the conserved sequence block domains (CSB-1, CSB-2, and CSB-3).

Mitochondrial DNA control region of three mackerels, genus Rastrelliger: structure, molecular diversity and phylogenetic relationship

The complete mitochondrial control regions (CR) of three mackerels (Rastrelliger spp.) were examined and analyzed. The CR contained three domains, in which three termination-associated sequences (TAS-I, TAS-II and TAS-III), two central conserved sequence blocks (CSB-E, CSB-D), three conserved sequence blocks (CSB-I, CSB-II, and CSB-III) and a putative promoter were detected. Molecular indices analyses of the aligned complete CR sequences showed high level of haplotype diversities and genetic divergences among the three species. The intraspecific divergence among species of this genus ranked from 0.25% to 1.62% and interspecific divergence from 1.90% to 4.30%. The phylogenetic tree shows monophyly with R. brachysoma as a basal species of Rastrelliger. Applying the average divergence rate for fish control regions, the results suggest that the time of separation among Rastrelligers could have occurred in the middle Pleistocene era.

Complete mitochondrial genome of the Loligo duvaucelii

In this study, we determined the complete mitochondrial genome of the little squid (Loligo duvaucelii). The genome is 17,413 bp in length, containing 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and 3 main non-coding regions. The overall base composition of L. duvaucelii is 40.01% A, 32.33% T, 19.14% C and 8.52% G, with a high A + T bias of 72.34%. All of the three control regions (CR) contain termination-associated sequences and conserved sequence blocks. Here, we describe a phylogenetic analysis of 10 species of Cephalopoda based on the complete mitochondrial genome, the result showed that the Loliolus uyii is most closely related to L. duvaucelii. This mitogenome sequence data would play an important role in the investigation of phylogenetic relationship, taxonomic resolution and phylogeography of the Cephalopoda.

Sequencing and analysis of the complete mitochondrial genome of Amur minnow from China

The complete mitogenome sequence of Amur minnow (Rhynchocypris lagowskii) was determined using long PCR. The genome was 16,594 bp in length and contained 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and one control region. The overall base composition of the heavy strand is A (28.60%), C (26.32%), T (27.40%), and G (17.68%). The control region was 927 bp in length and the A + T content of the region was 63.32%. The extended termination-associated sequence domain, the central conserved domain, and the conserved sequence block domain are defined in the mitochondrial genome control region of Amur minnow. Mitochondrial genomes analyses based on maximum parsimony (MP), neighbor-joining (NJ), and Bayesian analyses yielded identical phylogenetic trees, indicating a close phylogenetic affinity of the 15 Cyprinidae species. It appeared that no less than two major phyletic lineages were present in Leuciscinae. The main clades within the Leuciscinae supported are: A clade is the Tribolodon. A clade (Rhynchocypris) with the Oreoleuciscus as the sister taxon to Tribolodon was supported by bootstrap values of 49%. The five different geographical populations of the R. lagowskii formed a paraphyletic group with the high bootstrap value (45%) in all examinations.

The complete mitochondrial genome of Cherskii’s sculpin (Cottus czerskii) (Scorpaeniformes: Cottidae)

The complete mitogenome sequence of Cherskii’s sculpin (Cottus czerskii) is determined using long PCR. The genome is 16,534 bp in length and contains 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and a control region. The overall base composition of the heavy strand is A (26.4%), C (30.1%), T (26.1%) and G (17.5%). The control region is 857 bp in length and the A + T content of the region is 61.5%. The extended termination-associated sequence domain, the central conserved domain and the conserved sequence block domain are defined in the mitochondrial genome control region of Cherskii’s sculpin. Mitochondrial genome analyses based on MP, NJ and Bayesian analyses yielded identical phylogenetic trees, indicating a close phylogenetic affinity of the 21 Actinopterygii species. It appears that no less than two major phyletic lineages were present in Actinopterygii. The main clades within the Perciformes and Scorpaeniformes supported are: a clade including the Scombridae, Kyphosidae and Percichthyidae; a clade (Cottidae) with the Trichodontidae as the sister taxon to Pholidae, Anarhichadidae and Zoarcidae, which was supported by bootstrap values of 92%. The five Cottus species formed a paraphyletic group with the high bootstrap value (100%) in all examinations.

The complete mitochondrial genome of Eurasian water shrew (Neomys fodiens)

The complete mitogenome sequence of Eurasian water shrew (Neomys fodiens) was determined using long PCR. The genome was 17,260 bp in length and contained 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes and 1 control region. The overall base composition of the heavy strand is A (33.0%), C (23.2%), T (30.9%) and G (12.9%). The base compositions present clearly the A–T skew, which is most obviously in the control region and protein-coding genes. The extended termination-associated sequence domain, the central conserved domain and the conserved sequence block domain are defined in the mitochondrial genome control region of Eurasian water shrew. Mitochondrial genomes analyses based on MP, ML, NJ and Bayesian analyses yielded identical phylogenetic trees. Neomys elegans, Soriculus fumidus, and N. fodiens formed a monophyletic group with the high bootstrap value (100%) in all examinations. This clade with the Anourosorex squamipes as the sister taxon to Sorex.

The complete mitochondrial genome of Gloydius intermedius (Squamata: Viperidae: Crotalinae) from China

The mitochondrial genome sequence of Gloydius intermedius is analyzed and presented for the first time. The genome was 17, 226 bp in length and contained 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes and 2 control region. The overall base composition was A (32.4%), C (28.8%), T (25.9%), and G (12.9%). The base compositions clearly presented the A–C skew, which was most obvious in the protein-coding genes. The extended termination-associated sequence domain, the central conserved domain and the conserved sequence block domain are defined in the mitochondrial genome control region of G. intermedius. Mitochondrial genome analyses based on MP, ML, NJ and Bayesian analyses yielded identical phylogenetic trees, indicating a close phylogenetic affinity of the 13 Crotalinae species. It appeared that no less than two major phyletic lineages were present in Crotalinae. The main clades within the Crotalinae supported are: A clade including the Protobothrops. A clade (G. brevicaudus, G. ussuriensis, G. intermedius, G. saxatilis) with the Ovophis appeared as the sister taxon to Protobothrops and was supported by bootstrap values of 88%. The four Gloydius species formed a paraphyletic group with the high bootstrap value (100 %) in all examinations.

The complete mitochondrial genome of Amur bitterling (Rhodeus sericeus) from China

The complete mitogenome sequence of Amur bitterling (Rhodeus sericeus) was determined using long PCR. The genome was 16,581 bp in length and contained 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, 1 origin of L strand replication and 1 control region. The overall base composition of the heavy strand was A (28.9%), C (27.2%), T (26.6%), and G (17.3%). The control region was 925 bp in length and the A + T content of the region was 63.5%. The extended termination-associated sequence domain, the central conserved domain and the conserved sequence block domain are defined in the mitochondrial genome control region of Amur bitterling. Mitochondrial genome analyses based on MP, ML, NJ and Bayesian analyses yielded identical phylogenetic trees, indicating a close phylogenetic affinity to the 13 Cyprinidae species. It appeared that no less than three major phyletic lineages were present in Cyprinidae. A clade (Rhodeus and Tanakia) with the R. lighti and R. Sinensis as the sister taxon to Acheilognathus was supported by bootstrap values of 100%. The close relationship of Amur bitterling to other Rhodeus species, especially R. pseudosericeus, is consistent with the results confirmed using morphology analysis.

Characterization of the mitochondrial genome of Bufo gargarizans minshanicus (Anura: Bufonidae)

The complete mitogenome of Bufo gargarizans minshanicus is 17,719 bp in size, and shares a conserved gene arrangement, gene content and base composition with other Bufonidae species. The base composition of the H-strand is biased toward A + T content at 56.97% (T 28.14%, C 27.67%, A 28.83% and G 15.36%). Most protein-coding genes (PCGs) begin with ATG, while COX1 and ND2 initiate with ATA and ND1 starts at ATT. Seven PCGs have the complete stop codons AGA and TAA, whereas the remaining four PCGs end with TA or T. The putative control region possesses two repeat motifs, and four termination-associated sequences and six conserved sequence blocks at the 5′ and 3′ ends.