tRNA-Cys gene clusters exhibit high variability in Arabidopsis thaliana.

Although most of the genes encoding tRNAs in plants are dispersed throughout the genome, a fraction of them form tRNA gene clusters. In Arabidopsis thaliana, the smallest of tRNA clusters on chromosome 5 consists of four tRNA-Cys-GCA genes placed within repeating units of 0.4 kbp. A systematic analysis of the genomic sequences of syntenic regions from various ecotypes of A. thaliana showed that the general structure of the cluster, consisting of a tRNA-Cys pseudogene followed by repeating units containing tRNA-Cys genes, is well conserved. However, there is significant heterogeneity in the number of repeating units between different ecotypes. A unique feature of this cluster is the presence of putative transposable elements (Helitron). In addition, two further tRNA-Cys gene mini-clusters (gene pairs) in A. thaliana were identified. RNA-seq-based evaluation of expression of tRNA-Cys-GCA genes showed a positive signal for 11 out of 13 unique transcripts. An analysis of the conservation of the tRNA-Cys clusters from A. thaliana with the corresponding regions from four other Arabidopsis species suggests a sequence of events that led to the divergence of these regions.

Identification of fish species through tRNA-based primer design.

BACKGROUND: The correct establishment of the barcode classification system for fish can facilitate biotaxonomists to distinguish fish species, and it can help the government to verify the authenticity of the ingredients of fish products or identify unknown fish related samples. The Cytochrome c oxidation I (COI) gene sequence in the mitochondria of each species possesses unique characteristics, which has been widely used as barcodes in identifying species in recent years. Instead of using COI gene sequences for primer design, flanking tRNA segments of COI genes from 2618 complete fish mitochondrial genomes were analyzed to discover suitable primers for fish classification at taxonomic family level. The minimal number of primer sets is designed to effectively distinguish various clustered groups of fish species for identification applications. Sequence alignment analysis and cross tRNA segment comparisons were applied to check and ensure the primers for each cluster group are exclusive. RESULTS: Two approaches were applied to improve primer design and re-cluster fish species. The results have shown that exclusive primers for 2618 fish species were successfully discovered through in silico analysis. In addition, we applied sequence alignment analysis to confirm that each pair of primers can successfully identify all collected fish species at the taxonomic family levels. CONCLUSIONS: This study provided a practical strategy to discover unique primers for each fishery species and a comprehensive list of exclusive primers for extracting COI barcode sequences of all known fishery species. Various applications of verification of fish products or identification of unknown fish species could be effectively achieved.

Differential expression of human tRNA genes drives the abundance of tRNA-derived fragments.

The human genome encodes hundreds of transfer RNA (tRNA) genes but their individual contribution to the tRNA pool is not fully understood. Deep sequencing of tRNA transcripts (tRNA-Seq) can estimate tRNA abundance at single gene resolution, but tRNA structures and posttranscriptional modifications impair these analyses. Here we present a bioinformatics strategy to investigate differential tRNA gene expression and use it to compare tRNA-Seq datasets from cultured human cells and human brain. We find that sequencing caveats affect quantitation of only a subset of human tRNA genes. Unexpectedly, we detect several cases where the differences in tRNA expression among samples do not involve variations at the level of isoacceptor tRNA sets (tRNAs charged with the same amino acid but using different anticodons), but rather among tRNA genes within the same isodecoder set (tRNAs having the same anticodon sequence). Because isodecoder tRNAs are functionally equal in terms of genetic translation, their differential expression may be related to noncanonical tRNA functions. We show that several instances of differential tRNA gene expression result in changes in the abundance of tRNA-derived fragments (tRFs) but not of mature tRNAs. Examples of differentially expressed tRFs include PIWI-associated RNAs, tRFs present in tissue samples but not in cells cultured in vitro, and somatic tissue-specific tRFs. Our data support that differential expression of tRNA genes regulate noncanonical tRNA functions performed by tRFs.

Coordination of tRNA transcription with export at nuclear pore complexes in budding yeast.

tRNAs are encoded by RNA polymerase III-transcribed genes that reside at seemingly random intervals along the chromosomes of budding yeast. Existing evidence suggests that the genes congregate together at the nucleolus and/or centromeres. In this study, we re-examined spatial and temporal aspects of tRNA gene (tDNA) expression. We show that tDNA transcription fluctuates during cell cycle progression. In M phase, when tRNA synthesis peaks, tDNAs localize at nuclear pore complexes (NPCs). Docking of a tDNA requires the DNA sequence of the contacted gene, nucleoporins Nup60 and Nup2, and cohesin. Characterization of mutants that block NPC localization revealed that docking is a consequence of elevated tDNA transcription. NPC-tDNA contact falters in the absence of the principal exportin of nascent tRNA, Los1, and genetic assays indicate that gating of tDNAs at NPCs favors cytoplasmic accumulation of functional tRNA. Collectively, the data suggest that tDNAs associate with NPCs to coordinate RNA polymerase III transcription with the nuclear export of pre-tRNA. The M-phase specificity of NPC contact reflects a regulatory mechanism that may have evolved, in part, to avoid collisions between DNA replication forks and transcribing RNA polymerase III machinery at NPCs.

Small-Molecule Antibiotics Inhibiting tRNA-Regulated Gene Expression Is a Viable Strategy for Targeting Gram-Positive Bacteria.

Bacterial infections and the rise of antibiotic resistance, especially multidrug resistance, have generated a clear need for discovery of novel therapeutics. We demonstrated that a small-molecule drug, PKZ18, targets the T-box mechanism and inhibits bacterial growth. The T-box is a structurally conserved riboswitch-like gene regulator in the 5' untranslated region (UTR) of numerous essential genes of Gram-positive bacteria. T-boxes are stabilized by cognate, unacylated tRNA ligands, allowing the formation of an antiterminator hairpin in the mRNA that enables transcription of the gene. In the absence of an unacylated cognate tRNA, transcription is halted due to the formation of a thermodynamically more stable terminator hairpin. PKZ18 targets the site of the codon-anticodon interaction of the conserved stem I and reduces T-box-controlled gene expression. Here, we show that novel analogs of PKZ18 have improved MICs, bactericidal effects against methicillin-resistant Staphylococcus aureus (MRSA), and increased efficacy in nutrient-limiting conditions. The analogs have reduced cytotoxicity against eukaryotic cells compared to PKZ18. The PKZ18 analogs acted synergistically with aminoglycosides to significantly enhance the efficacy of the analogs and aminoglycosides, further increasing their therapeutic windows. RNA sequencing showed that the analog PKZ18-22 affects expression of 8 of 12 T-box controlled genes in a statistically significant manner, but not other 5'-UTR regulated genes in MRSA. Very low levels of resistance further support the existence of multiple T-box targets for PKZ18 analogs in the cell. Together, the multiple targets, low resistance, and synergy make PKZ18 analogs promising drugs for development and future clinical applications.

Hidden cases of tRNA gene duplication and remolding in mitochondrial genomes of amphipods.

The evolution of tRNA genes in mitochondrial (mt) genomes is a complex process that includes duplications, degenerations, and transpositions, as well as a specific process of identity change through mutations in the anticodon (tRNA gene remolding or tRNA gene recruitment). Using amphipod-specific tRNA models for annotation, we show that tRNA duplications are more common in the mt genomes of amphipods than what was revealed by previous annotations. Seventeen cases of tRNA gene duplications were detected in the mt genomes of amphipods, and ten of them were tRNA genes that underwent remolding. The additional tRNA gene findings were verified using phylogenetic analysis and genetic distance analysis. The majority of remolded tRNA genes (seven out of ten cases) were found in the mt genomes of endemic amphipod species from Lake Baikal. All additional mt tRNA genes arose independently in the Baikalian amphipods, indicating the unusual plasticity of tRNA gene evolution in these species assemblages. The possible reasons for the unusual abundance of additional tRNA genes in the mt genomes of Baikalian amphipods are discussed. The amphipod-specific tRNA models developed for MiTFi refine existing predictions of tRNA genes in amphipods and reveal additional cases of duplicated tRNA genes overlooked by using less specific Metazoa-wide models. The application of these models for mt tRNA gene prediction will be useful for the correct annotation of mt genomes of amphipods and probably other crustaceans.

Identification of variants in the mitochondrial lysine-tRNA (MT-TK) gene in myoclonic epilepsy-pathogenicity evaluation and structural characterization by in silico approach.

Variations in mitochondrial genes have an established link with myoclonic epilepsy. In the present study we evaluated the nucleotide sequence of MT-TK gene of 52 individuals from 12 unrelated families and reported three variations in 2 of the 13 epileptic patients. The DNA sequences coding for MT-TK gene were sequenced and mutations were detected in all participants. The mutations were further analyzed by the in silico analysis and their structural and pathogenic effects were determined. All the investigated patients had symptoms of myoclonus, 61.5% were positive for ataxia, 23.07% were suffering from hearing loss, 15.38% were having mild to severe dementia, 69.23% were males, and 61.53% had cousin marriage in their family history. DNA extracted from saliva was used for the PCR amplification of a 440 bp DNA fragment encompassing complete MT-TK gene. The nucleotide sequence analysis revealed three mutations, m.8306T>C, m.8313G>C, and m.8362T>G that are divergent from available reports. The identified mutations designate the heteroplasmic condition. Furthermore, pathogenicity of the identified variants was predicted by in silico tools viz., PON-mt-tRNA and MitoTIP. Secondary structure of altered MT-TK was predicted by RNAStructure web server. Studies by MitoTIP and PON-mt-tRNA tools have provided strong evidences of pathogenic effects of these mutations. Single nucleotide variations resulted in disruptive secondary structure of mutant MT-TK models, as predicted by RNAStructure. In vivo confirmation of structural and pathogenic effects of identified mutations in the animal models can be prolonged on the basis of these findings.

Ty1 Integrase Interacts with RNA Polymerase III-specific Subcomplexes to Promote Insertion of Ty1 Elements Upstream of Polymerase (Pol) III-transcribed Genes.

Retrotransposons are eukaryotic mobile genetic elements that transpose by reverse transcription of an RNA intermediate and are derived from retroviruses. The Ty1 retrotransposon of Saccharomyces cerevisiae belongs to the Ty1/Copia superfamily, which is present in every eukaryotic genome. Insertion of Ty1 elements into the S. cerevisiae genome, which occurs upstream of genes transcribed by RNA Pol III, requires the Ty1 element-encoded integrase (IN) protein. Here, we report that Ty1-IN interacts in vivo and in vitro with RNA Pol III-specific subunits to mediate insertion of Ty1 elements upstream of Pol III-transcribed genes. Purification of Ty1-IN from yeast cells followed by mass spectrometry (MS) analysis identified an enrichment of peptides corresponding to the Rpc82/34/31 and Rpc53/37 Pol III-specific subcomplexes. GFP-Trap purification of multiple GFP-tagged RNA Pol III subunits from yeast extracts revealed that the majority of Pol III subunits co-purify with Ty1-IN but not two other complexes required for Pol III transcription, transcription initiation factors (TF) IIIB and IIIC. In vitro binding studies with bacterially purified RNA Pol III proteins demonstrate that Rpc31, Rpc34, and Rpc53 interact directly with Ty1-IN. Deletion of the N-terminal 280 amino acids of Rpc53 abrogates insertion of Ty1 elements upstream of the hot spot SUF16 tRNA locus and abolishes the interaction of Ty1-IN with Rpc37. The Rpc53/37 complex therefore has an important role in targeting Ty1-IN to insert Ty1 elements upstream of Pol III-transcribed genes.

Duplication and Remolding of tRNA Genes in the Mitochondrial Genome of Reduvius tenebrosus (Hemiptera: Reduviidae).

Most assassin bugs are predators that act as important natural enemies of insect pests. Mitochondrial (mt) genomes of these insects are double-strand circular DNAs that encode 37 genes. In the present study, we explore the duplication and rearrangement of tRNA genes in the mt genome of Reduvius tenebrosus, the first mt genome from the subfamily Reduviinae. The gene order rearranges from CR (control region)-trnI-trnQ-trnM-ND2 to CR-trnQ-trnI2-trnI1-trnM-ND2. We identified 23 tRNA genes, including 22 tRNAs commonly found in insects and an additional trnI (trnI2), which has high sequence similarity to trnM. We found several pseudo genes, such as pseudo-trnI, pseudo-CR, and pseudo-ND2, in the hotspot region of gene rearrangement (between the control region and ND2). These features provided evidence that this novel gene order could be explained by the tandem duplication/random loss (TDRL) model. The tRNA duplication/anticodon mutation mechanism further explains the presence of trnI2, which is remolded from a duplicated trnM in the TDRL process (through an anticodon mutation of CAT to GAT). Our study also raises new questions as to whether the two events proceed simultaneously and if the remolded tRNA gene is fully functional. Significantly, the duplicated tRNA gene in the mitochondrial genome has evolved independently at least two times within assassin bugs.

Distribution of ADAT-Dependent Codons in the Human Transcriptome.

Nucleotide modifications in the anticodons of transfer RNAs (tRNA) play a central role in translation efficiency, fidelity, and regulation of translation, but, for most of these modifications, the details of their function remain unknown. The heterodimeric adenosine deaminases acting on tRNAs (ADAT2-ADAT3, or ADAT) are enzymes present in eukaryotes that convert adenine (A) to inosine (I) in the first anticodon base (position 34) by hydrolytic deamination. To explore the influence of ADAT activity on mammalian translation, we have characterized the human transcriptome and proteome in terms of frequency and distribution of ADAT-related codons. Eight different tRNAs can be modified by ADAT and, once modified, these tRNAs will recognize NNC, NNU and NNA codons, but not NNG codons. We find that transcripts coding for proteins highly enriched in these eight amino acids (ADAT-aa) are specifically enriched in NNC, NNU and NNA codons. We also show that the proteins most enriched in ADAT-aa are composed preferentially of threonine, alanine, proline, and serine (TAPS). We propose that the enrichment in ADAT-codons in these proteins is due to the similarities in the codons that correspond to TAPS.

Comparative mitogenomes reveal diverse and novel gene rearrangements in the genus Meteorus (Hymenoptera: Braconidae).

Meteorus Haliday, 1835 is a cosmopolitan genus within Braconidae (Hymenoptera). They are koinobiont endoparasitoids of Coleoptera or Lepidoptera larvae. Only one mitogenome of this genus was available. Here, we sequenced and annotated three mitogenomes of Meteorus species, and found that the tRNA gene rearrangements in these mitogenomes were rich and diverse. Compared with the ancestral organization, only seven tRNAs (trnW, trnY, trnL2, trnH, trnT, trnP and trnV) were conserved and trnG had its own unique location in the four mitogenomes. This dramatic tRNA rearrangement was not observed in mitogenomes of other insect groups before. In addition, the tRNA cluster (trnA-trnR-trnN-trnS1-trnE-trnF) between nad3 and nad5 was rearranged into two patterns, i.e., trnE-trnA-trnR-trnN-trnS1 and trnA-trnR-trnS1-trnE-trnF-trnN. The phylogenetic results showed that the Meteorus species formed a clade within the subfamily Euphorinae, and were close to Zele (Hymenoptera, Braconidae, Euphorinae). In the Meteorus, two clades were reconstructed: M. sp. USNM and Meteorus pulchricornis forming one clade while the remaining two species forming another clade. This phylogenetic relationship also matched the tRNA rearrangement patterns. The diverse and phylogenetic signal of tRNA rearrangements within one genus provided insights into tRNA rearrangements of the mitochondrial genome at genus/species levels in insects.

The Conserved Chromatin Remodeler SMARCAD1 Interacts with TFIIIC and Architectural Proteins in Human and Mouse.

In vertebrates, SMARCAD1 participates in transcriptional regulation, heterochromatin maintenance, DNA repair, and replication. The molecular basis underlying its involvement in these processes is not well understood. We identified the RNA polymerase III general transcription factor TFIIIC as an interaction partner of native SMARCAD1 in mouse and human models using endogenous co-immunoprecipitations. TFIIIC has dual functionality, acting as a general transcription factor and as a genome organizer separating chromatin domains. We found that its partnership with SMARCAD1 is conserved across different mammalian cell types, from somatic to pluripotent cells. Using purified proteins, we confirmed that their interaction is direct. A gene expression analysis suggested that SMARCAD1 is dispensable for TFIIIC function as an RNA polymerase III transcription factor in mouse ESCs. The distribution of TFIIIC and SMARCAD1 in the ESC genome is distinct, and unlike in yeast, SMARCAD1 is not enriched at active tRNA genes. Further analysis of SMARCAD1-binding partners in pluripotent and differentiated mammalian cells reveals that SMARCAD1 associates with several factors that have key regulatory roles in chromatin organization, such as cohesin, laminB, and DDX5. Together, our work suggests for the first time that the SMARCAD1 enzyme participates in genome organization in mammalian nuclei through interactions with architectural proteins.

A novel gene order and remolded tRNAs revealed in the mitogenome of Asian gecarcinucid freshwater crabs (Brachyura, Gecarcinucidae).

Here we report the first mitochondrial genomes (mitogenomes) of four species of gecarcinucid freshwater crabs (FWCs) in two genera, two from China (Somanniathelphusa hainanensis and S. yangshanensis), one from Laos (Esanthelphusa dugasti), and one from Myanmar (Esanthelphusa keyini). A novel gecarcinucid mitochondrial gene order (GMGO2) that was only found in E. dugasti that contains a total of 42 genes, including one pseudogene, two remolded tRNAs and two duplicated tRNAs. The GMGO2 of E. dugasti was compared with the brachyuran ground-pattern mitochondrial gene order (BMGO), revealing the rearrangements of the positions of 10 tRNAs, two PCGs, and one mNCR. The three other gecarcinucids in this study were all found to possess a previously reported gecarcinucid mitochondrial gene order (GMGO1). The phylogenetic tree reconstructed using the secondary structures of 22 tRNAs of the mitogenomes of 41 species of FWCs provides insights into the evolution of the mitogenome of E. dugasti (GMGO2) which includes remolded and duplicated tRNAs.

TFIIIC-based chromatin insulators through eukaryotic evolution.

Eukaryotic chromosomes are divided into domains with distinct structural and functional properties, such as differing levels of chromatin compaction and gene transcription. Domains of relatively compact chromatin and minimal transcription are termed heterochromatic, whereas euchromatin is more open and actively transcribed. Insulators separate these domains and maintain their distinct features. Disruption of insulators can cause diseases such as cancer. Many insulators contain tRNA genes (tDNAs), examples of which have been shown to block the spread of activating or silencing activities. This characteristic of specific tDNAs is conserved through evolution, such that human tDNAs can serve as barriers to the spread of silencing in fission yeast. Here we demonstrate that tDNAs from the methylotrophic fungus Pichia pastoris can function effectively as insulators in distantly-related budding yeast. Key to the function of tDNAs as insulators is TFIIIC, a transcription factor that is also required for their expression. TFIIIC binds additional loci besides tDNAs, some of which have insulator activity. Although the mechanistic basis of TFIIIC-based insulation has been studied extensively in yeast, it is largely uncharacterized in metazoa. Utilising publicly-available genome-wide ChIP-seq data, we consider the extent to which mechanisms conserved from yeast to man may suffice to allow efficient insulation by TFIIIC in the more challenging chromatin environments of metazoa and suggest features that may have been acquired during evolution to cope with new challenges. We demonstrate the widespread presence at human tDNAs of USF1, a transcription factor with well-established barrier activity in vertebrates. We predict that tDNA-based insulators in higher organisms have evolved through incorporation of modules, such as binding sites for factors like USF1 and CTCF that are absent from yeasts, thereby strengthening function and providing opportunities for regulation between cell types.

Unique Duplication of trnN in Odontoptilum angulatum (Lepidoptera: Pyrginae) and Phylogeny within Hesperiidae.

To explore the variation and relationship between gene rearrangement and phylogenetic effectiveness of mitogenomes among lineages of the diversification of the tribe Tagiadini in the subfamily Pyrginae, we sequenced the complete mitogenome of Odontoptilum angulatum. The genome is 15,361 bp with the typical 37 genes, a large AT-rich region and an additional trnN (trnN2), which is completely identical to trnN (sequence similarity: 100%). The gene order differs from the typical Lepidoptera-specific arrangement and is unique to Hesperiidae. The presence of a "pseudo-trnS1" in the non-coding region between trnN1 and trnN2 supports the hypothesis that the presence of an extra trnN can be explained by the tandem duplication-random loss (TDRL) model. Regarding the phylogenetic analyses, we found that the dataset comprising all 37 genes produced the highest node support, as well as a monophyly of Pyrginae, indicating that the inclusion of RNAs improves the phylogenetic signal. Relationships among the subfamilies in Hesperiidae were also in general agreement with the results of previous studies. The monophyly of Tagiadini is strongly supported. Our study provides a new orientation for application of compositional and mutational biases of mitogenomes in phylogenetic analysis of Tagiadini and even all Hesperiidae based on larger taxon sampling in the future.

Genome Size Reduction and Transposon Activity Impact tRNA Gene Diversity While Ensuring Translational Stability in Birds.

As a highly diverse vertebrate class, bird species have adapted to various ecological systems. How this phenotypic diversity can be explained genetically is intensively debated and is likely grounded in differences in the genome content. Larger and more complex genomes could allow for greater genetic regulation that results in more phenotypic variety. Surprisingly, avian genomes are much smaller compared to other vertebrates but contain as many protein-coding genes as other vertebrates. This supports the notion that the phenotypic diversity is largely determined by selection on non-coding gene sequences. Transfer RNAs (tRNAs) represent a group of non-coding genes. However, the characteristics of tRNA genes across bird genomes have remained largely unexplored. Here, we exhaustively investigated the evolution and functional consequences of these crucial translational regulators within bird species and across vertebrates. Our dense sampling of 55 avian genomes representing each bird order revealed an average of 169 tRNA genes with at least 31% being actively used. Unlike other vertebrates, avian tRNA genes are reduced in number and complexity but are still in line with vertebrate wobble pairing strategies and mutation-driven codon usage. Our detailed phylogenetic analyses further uncovered that new tRNA genes can emerge through multiplication by transposable elements. Together, this study provides the first comprehensive avian and cross-vertebrate tRNA gene analyses and demonstrates that tRNA gene evolution is flexible albeit constrained within functional boundaries of general mechanisms in protein translation.

Evolution of tRNA gene rearrangement in the mitochondrial genome of ichneumonoid wasps (Hymenoptera: Ichneumonoidea).

Gene rearrangements in the mitochondrial genome (mt genome) are common in certain insect groups and can be an informative character for phylogenetic reconstruction. However, knowledge of the mechanism and biases of gene rearrangement in insect mt genomes is still limited. With an accelerated rate of gene rearrangements, Hymenoptera is an important group for mt genome rearrangements diversity and for understanding the gene rearrangement evolution in mt genomes. Here, we sequenced the complete mt genome of Aphidius gifuensis and analyzed the evolution of tRNA gene rearrangements in the mt genomes of ichneumonoid wasps. Two control regions were detected in A. gifuensis and most of the tRNA rearrangement events occurred around these control regions. tRNA gene rearrangements occurred in almost all of the sequenced mt genomes of Ichneumonoidea and the gene block CR-trnI-trnQ-trnM-ND2-trnW-trnC-trnY was the main hot spot of gene rearrangement. Mapped over the backbone phylogeny of Ichneumonoidea, we found that the inversion and translocation of both trnI and trnM is likely a synapomorphic rearrangement in Braconidae. Our study also demonstrated that the gene block CR-trnI-trnQ-trnM-ND2-trnW-trnC-trnY was important for inferring the gene rearrangement dynamics in Ichneumonoidea.

Global In-Silico Scenario of tRNA Genes and Their Organization in Virus Genomes.

Viruses are known to be highly dependent on the host translation machinery for their protein synthesis. However, tRNA genes are occasionally identified in such organisms, and in addition, few of them harbor tRNA gene clusters comprising dozens of genes. Recently, tRNA gene clusters have been shown to occur among the three domains of life. In such a scenario, the viruses could play a role in the dispersion of such structures among these organisms. Thus, in order to reveal the prevalence of tRNA genes as well as tRNA gene clusters in viruses, we performed an unbiased large-scale genome survey. Interestingly, tRNA genes were predicted in ssDNA (single-stranded DNA) and ssRNA (single-stranded RNA) viruses as well in many other dsDNA viruses of families from Caudovirales order. In the latter group, tRNA gene clusters composed of 15 to 37 tRNA genes were characterized, mainly in bacteriophages, enlarging the occurrence of such structures within viruses. These bacteriophages were from hosts that encompass five phyla and 34 genera. This in-silico study presents the current global scenario of tRNA genes and their organization in virus genomes, contributing and opening questions to be explored in further studies concerning the role of the translation apparatus in these organisms.

Mitochondrial genome of Phalantus geniculatus (Hemiptera: Reduviidae): trnT duplication and phylogenetic implications.

Reduviidae is the second largest family of Heteroptera and most of them are important natural enemies of agricultural and forest pests. Most of the sequenced mitochondrial (mt) genomes in this family have the typical gene arrangement of insects and encode 37 coding genes (13 protein-coding genes, 22 tRNA genes and two rRNA genes). In the present study, we sequenced the mt genome of Phalantus geniculatus from the subfamily Peiratinae through high-throughput sequencing and encountered the duplication of tRNA genes for the first time in this subfamily. We identified 23 tRNA genes, including 22 tRNAs commonly found in insect mt genomes and an extra trnT (trnT2), which has high sequence similarity (96.9%) to trnT1. The presence of a "pseudo-trnP" in the non-coding region between trnT1 and trnT2 supports the hypothesis that the presence of an extra trnT can be explained by the tandem duplication-random loss (TDRL) model. Phylogenetic results inferred from mt genome sequences supported a sister relationship between Phymatinae and the remaining sampled subfamilies, as well as a paraphyletic Reduviinae. The present study highlights the utility of mt genomes in the phylogenetic study of Reduviidae based on the large scale taxon sampling in the future.

Loss of the tRNALysCUU encoding gene, Chr-11 tRNA-Lys-CUU, is not associated with Type 2 diabetes mellitus.

AIM: To investigate the presence/absence of the Chr-11 tRNA-Lys-CUU gene as a marker for genetic predisposition to Type 2 diabetes mellitus (T2DM). METHODS: We enrolled 122 patients diagnosed with T2DM and 77 non-diabetic individuals. We evaluated clinical and biochemical parameters (body mass index, hypertension, cholesterol levels, glycosylated hemoglobin, triglycerides, etc.), and performed a genotypic profiling of Chr-11 tRNA-Lys-CUU by polymerase chain reaction analyses. RESULTS: Approximately one third of the population lacked Chr-11 tRNA-Lys-CUU. We did not observe a statistically significant association between the presence/absence of Chr-11 tRNA-Lys-CUU and T2DM. CONCLUSION: The genotypic distribution of Chr-11 tRNA-Lys-CUU in our population was consistent to that reported by others. This gene failed as a marker for T2DM predisposition.