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The efficiency of translation termination is determined by the nature of the stop codon as well as its context. In eukaryotes, recognition of the A-site stop codon and release of the polypeptide are mediated by release factors eRF1 and eRF3, respectively. Translation termination is modulated by other factors which either directly interact with release factors or bind to the E-site and modulate the activity of the peptidyl transferase center. Previous studies suggested that the Saccharomyces cerevisiae ABCF ATPase New1 is involved in translation termination and/or ribosome recycling, however, the exact function remained unclear. Here, we have applied 5PSeq, single-particle cryo-EM and readthrough reporter assays to provide insight into the biological function of New1. We show that the lack of New1 results in ribosomal stalling at stop codons preceded by a lysine or arginine codon and that the stalling is not defined by the nature of the C-terminal amino acid but rather by the identity of the tRNA isoacceptor in the P-site. Collectively, our results suggest that translation termination is inefficient when ribosomes have specific tRNA isoacceptors in the P-site and that the recruitment of New1 rescues ribosomes at these problematic termination contexts., (© The Author(s) 2024. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Selenocysteine (Sec) is an essential amino acid that distinguishes itself from cysteine by a selenium atom in place of a sulfur atom. This single change imparts distinct chemical properties to Sec which are crucial for selenoprotein (Sec-containing protein) function. These properties include a lower p K a , enhanced nucleophilicity, and reversible oxidation. However, studying Sec incorporation in proteins is a complex process. While we find Sec in all domains of life, each domain has distinct translation mechanisms. These mechanisms are unique to canonical translation and are composed of Sec-specific enzymes and an mRNA hairpin to drive recoding of the UGA stop codon with Sec. In this review, we highlight the obstacles that arise when investigating Sec insertion, and the role that Sec has in proteins. We discuss the strategic methods implemented in this field to address these challenges. Though the Sec translation system is complex, a remarkable amount of information has been obtained and specialized tools have been developed. Continued studies in this area will provide a deeper understanding on the role of Sec in the context of proteins, and the necessity that we have for maintaining this complex translation machinery to make selenoproteins.

Premature termination codons (PTCs) cause ~10-20% of inherited diseases and are a major mechanism of tumor suppressor gene inactivation in cancer. A general strategy to alleviate the effects of PTCs would be to promote translational readthrough. Nonsense suppression by small molecules has proven effective in diverse disease models, but translation into the clinic is hampered by ineffective readthrough of many PTCs. Here we directly tackle the challenge of defining drug efficacy by quantifying the readthrough of ~5,800 human pathogenic stop codons by eight drugs. We find that different drugs promote the readthrough of complementary subsets of PTCs defined by local sequence context. This allows us to build interpretable models that accurately predict drug-induced readthrough genome-wide, and we validate these models by quantifying endogenous stop codon readthrough. Accurate readthrough quantification and prediction will empower clinical trial design and the development of personalized nonsense suppression therapies., (© 2024. The Author(s).)

Chronic alcohol consumption may alter mRNA methylation and expression levels of genes related to addiction and reward in the brain, potentially contributing to alcohol tolerance and dependence. Neuron-like (SH-SY5Y) and non-neuronal (SW620) cells were utilized as models to examine chronic intermittent ethanol (CIE) exposure-induced global m6A RNA methylation changes, as well as m6A mRNA methylation changes around the stop codon of three opioid receptor genes ( OPRM1 , OPRD1 , and OPRK1 ), which are known to regulate pain, reward, and addiction behaviours. CIE exposure for three weeks significantly increased global RNA methylation levels in both SH-SY5Y ( t  = 3.98, P  = 0.007) and SW620 ( t  = 2.24, P  = 0.067) cells. However, a 3-week CIE exposure resulted in hypomethylation around mRNA stop codon regions of OPRM1 and OPRD1 in both cell lines [ OPRM1 (SH-SY5Y) : t  = -5.05, P  = 0.0005; OPRM1 (SW620) : t  = -3.19, P  = 0.013; OPRD1 (SH-SY5Y) : t  = -13.43, P  < 0.00001; OPRD1 (SW620) : t  = -4.00, P  = 0.003]. Additionally, mRNA expression levels of OPRM1 , OPRD1 , and OPRK1 were downregulated (corresponding to mRNA hypomethylation) in both SH-SY5Y and SW620 cells after a 3-week CIE exposure. The present study demonstrated that chronic ethanol exposure altered global RNA methylation levels, as well as mRNA methylation and expression levels of opioid receptor genes in both neuron-like and non-neuronal cells. Our findings suggest a potential epitranscriptomic mechanism by which chronic alcohol consumption remodels the expression of reward-related and alcohol responsive genes in the brain, thus increasing the risk of alcohol use disorder development. Abbreviations : OPRM1 : the μ-opioid receptor; OPRD1 : the δ-opioid receptor; OPRK1 : the κ-opioid receptor; CIE: chronic intermittent ethanol exposure; CIE+WD: chronic intermittent ethanol exposure followed by a 24-hr withdrawal; SH-SY5Y: human neuroblastoma cell Line; SW620: human colon carcinoma cell line; RT-qPCR: reverse transcription followed by quantitative polymerase reaction; MazF-RT-qPCR: MazF digestion followed by RT-qPCR.

The de novo synthesis of genomes has made unprecedented progress and achieved milestones, particularly in bacteria and yeast. However, the process of synthesizing a multicellular plant genome has not progressed at the same pace, due to the complexity of multicellular plant genomes, technical difficulties associated with large genome size and structure, and the intricacies of gene regulation and expression in plants. Here we outline the bottom-up design principles for the de novo synthesis of the Physcomitrium patens (that is, earthmoss) genome. To facilitate international collaboration and accessibility, we have developed and launched a public online design platform called GenoDesigner. This platform offers an intuitive graphical interface enabling users to efficiently manipulate extensive genome sequences, even up to the gigabase level. This tool is poised to greatly expedite the synthesis of the P. patens genome, offering an essential reference and roadmap for the synthesis of plant genomes., (© 2024. Springer Nature Limited.)

In response to environmental changes, cells flexibly and rapidly alter gene expression through translational controls. In plants, the translation of NIP5;1, a boric acid diffusion facilitator, is downregulated in response to an excess amount of boric acid in the environment through upstream open reading frames (uORFs) that consist of only AUG and stop codons. However, the molecular details of how this minimum uORF controls translation of the downstream main ORF in a boric acid-dependent manner have remained unclear. Here, by combining ribosome profiling, translation complex profile sequencing, structural analysis with cryo-electron microscopy and biochemical assays, we show that the 80S ribosome assembled at AUG-stop migrates into the subsequent RNA segment, followed by downstream translation initiation, and that boric acid impedes this process by the stable confinement of eukaryotic release factor 1 on the 80S ribosome on AUG-stop. Our results provide molecular insight into translation regulation by a minimum and environment-responsive uORF., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Rett syndrome (RTT) is a neurodevelopmental disorder resulting from genetic mutations in the methyl CpG binding protein 2 (MeCP2) gene. Specifically, around 35% of RTT patients harbor premature termination codons (PTCs) within the MeCP2 gene due to nonsense mutations. A promising therapeutic avenue for these individuals involves the use of aminoglycosides, which stimulate translational readthrough (TR) by causing stop codons to be interpreted as sense codons. However, the effectiveness of this treatment depends on several factors, including the type of stop codon and the surrounding nucleotides, collectively referred to as the stop codon context (SCC). Here, we develop a high-content reporter system to precisely measure TR efficiency at different SCCs, assess the recovery of the full-length MeCP2 protein, and evaluate its subcellular localization. We have conducted a comprehensive investigation into the intricate relationship between SCC characteristics and TR induction, examining a total of 14 pathogenic MeCP2 nonsense mutations with the aim to advance the prospects of personalized therapy for individuals with RTT. Our results demonstrate that TR induction can successfully restore full-length MeCP2 protein, albeit to varying degrees, contingent upon the SCC and the specific position of the PTC within the MeCP2 mRNA. TR induction can lead to the re-establishment of nuclear localization of MeCP2, indicating the potential restoration of protein functionality. In summary, our findings underscore the significance of SCC-specific approaches in the development of tailored therapies for RTT. By unraveling the relationship between SCC and TR therapy, we pave the way for personalized, individualized treatment strategies that hold promise for improving the lives of individuals affected by this debilitating neurodevelopmental disorder. KEY MESSAGES: The efficiency of readthrough induction at MeCP2 premature termination codons strongly depends on the stop codon context. The position of the premature termination codon on the transcript influences the readthrough inducibility. A new high-content dual reporter assay facilitates the measurement and prediction of readthrough efficiency of specific nucleotide stop contexts. Readthrough induction results in the recovery of full-length MeCP2 and its re-localization to the nucleus. MeCP2 requires only one of its annotated nuclear localization signals., (© 2024. The Author(s).)

Nonsense mutations - the underlying cause of approximately 11% of all genetic diseases - prematurely terminate protein synthesis by mutating a sense codon to a premature stop or termination codon (PTC). An emerging therapeutic strategy to suppress nonsense defects is to engineer sense-codon decoding tRNAs to readthrough and restore translation at PTCs. However, the readthrough efficiency of the engineered suppressor tRNAs (sup-tRNAs) largely varies in a tissue- and sequence context-dependent manner and has not yet yielded optimal clinical efficacy for many nonsense mutations. Here, we systematically analyze the suppression efficacy at various pathogenic nonsense mutations. We discover that the translation velocity of the sequence upstream of PTCs modulates the sup-tRNA readthrough efficacy. The PTCs most refractory to suppression are embedded in a sequence context translated with an abrupt reversal of the translation speed leading to ribosomal collisions. Moreover, modeling translation velocity using Ribo-seq data can accurately predict the suppression efficacy at PTCs. These results reveal previously unknown molecular signatures contributing to genotype-phenotype relationships and treatment-response heterogeneity, and provide the framework for the development of personalized tRNA-based gene therapies., (© 2024. The Author(s).)

Genetic variants of human flavin-containing monooxygenase 3 (FMO3) were investigated using an updated Japanese population panel containing 54,000 subjects (the previous panel contained 38,000 subjects). One stop codon mutation and six amino acid-substituted FMO3 variants were newly identified in the updated databank. Of these, two substituted variants (p.Thr329Ala and p.Arg492Trp) were previously identified in compound haplotypes with p.[(Glu158Lys; Glu308Gly)] and were associated with the metabolic disorder trimethylaminuria. Three recombinant FMO3 protein variants (p.Ser137Leu, p.Ala334Val, and p.Ile426Val) expressed in bacterial membranes had similar activities toward trimethylamine N-oxygenation (∼75-125 %) as wild-type FMO3 (117 min -1 ); however, the recombinant novel FMO3 variant Phe313Ile showed moderately decreased FMO3 catalytic activity (∼20 % of wild-type). Because of the known deleterious effects of FMO3 C-terminal stop codons, the novel truncated FMO3 Gly184Ter variant was suspected to be inactive. To easily identify the four impaired FMO3 variants (one stop codon mutation and three amino-acid substitutions) in the clinical setting, simple confirmation methods for these FMO3 variants are proposed using polymerase chain reaction/restriction fragment length polymorphism or allele-specific PCR methods. The updated whole-genome sequence data and kinetic analyses revealed that four of the seven single-nucleotide nonsense or missense FMO3 variants had moderately or severely impaired activity toward trimethylamine N-oxygenation., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (© 2023 Published by Elsevier Ltd on behalf of The Japanese Society for the Study of Xenobiotics.)

Background: 'Taishuu' has a crisp texture, abundant juice, and sweet flavor with hints of cantaloupe. The availability of mitochondrial genome data of Diospyros species is far from the known number of species., Results: The sequencing data were assembled into a closed circular mitochondrial chromosome with a 421,308 bp length and a 45.79% GC content. The mitochondrial genome comprised 40 protein-coding, 24 tRNA, and three rRNA genes. The most common codons for arginine (Arg), proline (Pro), glycine (Gly), tryptophan (Trp), valine (Val), alanine (Ala), and leucine (Leu) were AGA, CCA, GGA, UGG, GUA, GCA, and CUA, respectively. The start codon for cox1 and nad4L protein-coding genes was ACG (ATG), whereas the remaining protein-coding genes started with ATG. There are four types of stop codons: CGA, TAA, TAG, and TGA, with TAA being the most frequently used stop codon (45.24%). In the D. kaki Thunb. 'Taishuu' mitochondrial genome, a total of 645 repeat sequences were identified, including 125 SSRs, 7 tandem repeats, and 513 dispersed repeats. Collinearity analysis revealed a close relationship between D. kaki Thunb. 'Taishuu' and Diospyros oleifera, with conserved homologous gene fragments shared among these species in large regions of the mitochondrial genome. The protein-coding genes ccmB and nad4L were observed to undergo positive selection. Analysis of homologous sequences between chloroplasts and mitochondria identified 28 homologous segments, with a total length of 24,075 bp, accounting for 5.71% of the mitochondrial genome. These homologous segments contain 8 annotated genes, including 6 tRNA genes and 2 protein-coding genes (rrn18 and ccmC). There are 23 homologous genes between chloroplasts and nuclei. Mitochondria, chloroplasts, and nuclei share two homologous genes, which are trnV-GAC and trnW-CCA., Conclusion: In conclusion, a high-quality chromosome-level draft genome for D. kaki was generated in this study, which will contribute to further studies of major economic traits in the genus Diospyros., (© 2024. The Author(s).)

In the context of rare genetic diseases caused by nonsense mutations, the concept of induced stop codon readthrough (SCR) represents an attractive avenue in the ongoing search for improved treatment options. Epidermolysis bullosa (EB)-exemplary for this group of diseases-describes a diverse group of rare, blistering genodermatoses. Characterized by extreme skin fragility upon minor mechanical trauma, the most severe forms often result from nonsense mutations that lead to premature translation termination and loss of function of essential proteins at the dermo-epidermal junction. Since no curative interventions are currently available, medical care is mainly limited to alleviating symptoms and preventing complications. Complementary to attempts of gene, cell and protein therapy in EB, SCR represents a promising medical alternative. While gentamicin has already been examined in several clinical trials involving EB, other potent SCR inducers, such as ataluren, may also show promise in treating the hitherto non-curative disease. In addition to the extensively studied aminoglycosides and their derivatives, several other substance classes-non-aminoglycoside antibiotics and non-aminoglycoside compounds-are currently under investigation. The extensive data gathered in numerous in vitro experiments and the perspectives they reveal in the clinical setting will be discussed in this review., (© 2024 The Authors. Experimental Dermatology published by John Wiley & Sons Ltd.)

Calophyllum soulattri Burm.f. is traditionally used to treat skin infections and reduce rheumatic pain, yet genetic and genomic studies are still limited. Here, we present the first complete mitochondrial genome of C. soulattri. It is 378,262 bp long with 43.97% GC content, containing 55 genes (30 protein-coding, 5 rRNA, and 20 tRNA). Repeat analysis of the mitochondrial genome revealed 194 SSRs, mostly mononucleotides, and 266 pairs of dispersed repeats ( ≥ 30 bp) that were predominantly palindromic. There were 23 homologous fragments found between the mitochondrial and plastome genomes. We also predicted 345 C-to-U RNA editing sites from 30 protein-coding genes (PCGs) of the C. soulatrii mitochondrial genome. These RNA editing events created the start codon of nad1 and the stop codon of ccmFc. Most PCGs of the C. soulattri mitochondrial genome underwent negative selection, but atp4 and ccmB experienced positive selection. Phylogenetic analyses showed C. soulattri is a sister taxon of Garcinia mangostana. This study has shed light on C. soulattri's evolution and Malpighiales' phylogeny. As the first complete mitochondrial genome in Calophyllaceae, it can be used as a reference genome for other medicinal plant species within the family for future genetic studies., (© 2024. The Author(s).)

Background: Almost all extant organisms use the same, so-called canonical, genetic code with departures from it being very rare. Even more exceptional are the instances when a eukaryote with non-canonical code can be easily cultivated and has its whole genome and transcriptome sequenced. This is the case of Blastocrithidia nonstop, a trypanosomatid flagellate that reassigned all three stop codons to encode amino acids., Results: We in silico predicted the metabolism of B. nonstop and compared it with that of the well-studied human parasites Trypanosoma brucei and Leishmania major. The mapped mitochondrial, glycosomal and cytosolic metabolism contains all typical features of these diverse and important parasites. We also provided experimental validation for some of the predicted observations, concerning, specifically presence of glycosomes, cellular respiration, and assembly of the respiratory complexes., Conclusions: In an unusual comparison of metabolism between a parasitic protist with a massively altered genetic code and its close relatives that rely on a canonical code we showed that the dramatic differences on the level of nucleic acids do not seem to be reflected in the metabolisms. Moreover, although the genome of B. nonstop is extremely AT-rich, we could not find any alterations of its pyrimidine synthesis pathway when compared to other trypanosomatids. Hence, we conclude that the dramatic alteration of the genetic code of B. nonstop has no significant repercussions on the metabolism of this flagellate., (© 2024. The Author(s).)

We have reported a gal mutant called galE stop 0 , wherein the galE stop codon was changed to a sense codon. The experiment results demonstrated that preventing galE translation termination inhibited the production of galE 3' ends. This implies that when the galE translation termination was prevented, the galE 3' ends generation was reduced or impaired. We anticipated that the translation of galE would continue to galT, producing a chimeric protein GalE-GalT. This study verified that the chimeric protein was produced, but unexpectedly, we found that the GalT protein was also synthesized in the mutant, and its amount equaled that in the wild-type. In the wild-type, we also found that the GalE-GalT chimeric protein was produced in an amount equal to that of the GalE protein. These results suggest that translation termination of galE and translation initiation of galT occur independently, thus, corroborating our transcription-translation model: At the cistron junction, transcription, decoupled from translation due to the translation termination of galE, needs translation initiation of galT to continue downstream; otherwise, transcription would be terminated by Rho. RNase E-mediated transcript cleavage also produces the 3' ends of pre-galE mRNA. These findings indicated that RNase E produces the 3' end of mRNA and establishes gene expression polarity., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Recurrent miscarriage (RM) affects 1% to 5% of couples trying to conceive. Despite extensive clinical and laboratory testing, half of the RM cases remain unexplained. We report the genetic analysis of a couple with eight miscarriages and the search for their potential genetic etiology., Methods: Short tandem repeat (STR) markers, single nucleotide polymorphic (SNP) microarray, and human DNA methylation microarray were used to analyze the genotypes of two miscarriages. Exomes sequencing was performed on DNA from the two partners and identified variants were validated by Sanger sequencing., Results: STR marker genotyping demonstrated that the two available miscarriages are triploid digynic and resulted from the failure of Meiosis II. SNP microarray analysis revealed an additional Meiosis I abnormality that is the segregation of the two maternal homologous chromosomes in one triploid miscarriage. Whole-exome sequencing on DNA from the two partners identified candidate variants only in the female partner in two genes with roles in female reproduction, a missense in EIF4ENIF1 (OMIM 607445) and a stop gain in HORMAD2 (OMIM 618842). EIF4ENIF1 is a eukaryotic translation initiation factor 4E nuclear import factor required for the oocyte germinal vesicle breakdown, and HORMAD2 is part of the synaptonemal complex that was hypothesized to act as a checkpoint mechanism to eliminate oocytes with asynapsis during meiotic prophase I in mice., Conclusion: While both genes may contribute to the phenotype, the Meiosis I abnormalities in the conceptions favor the causal role of HORMAD2 in the etiology of RM in this couple. This report illustrates the importance of comprehensively analyzing the products of conception to guide the search for the genetic causation of RM., (© 2024 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals LLC.)

Anaerobes have emerged in several major lineages of ciliates, but the number of independent transitions to anaerobiosis among ciliates is unknown. The APM clade (Armophorea, Muranotrichea, Parablepharismea) represents the largest clade of obligate anaerobes among ciliates and contains free-living marine and freshwater representatives as well as gut endobionts of animals. The evolution of APM group has only recently started getting attention, and our knowledge on its phylogeny and genetics is still limited to a fraction of taxa. While ciliates portray a wide array of alternatives to the standard genetic code across numerous classes, the APM ciliates were considered to be the largest group using exclusively standard nuclear genetic code. In this study, we present a pan-ciliate phylogenomic analysis with emphasis on the APM clade, bringing the first phylogenomic analysis of the family Tropidoatractidae (Armophorea) and confirming the position of Armophorida within Armophorea. We include five newly sequenced single cell transcriptomes from marine, freshwater, and endobiotic APM ciliates - Palmarella salina, Anteclevelandella constricta, Nyctotherus sp., Caenomorpha medusula, and Thigmothrix strigosa. We report the first discovery of an alternative nuclear genetic code among APM ciliates, used by Palmarella salina (Tropidoatractidae, Armophorea), but not by its close relative, Tropidoatractus sp., and provide a comparative analysis of stop codon identity and frequency indicating the precedency to the UAG codon loss/reassignment over the UAA codon reassignment in the specific ancestor of Palmarella. Comparative genomic and proteomic studies of this group may help explain the constraints that underlie UAR stop-to-sense reassignment, the most frequent type of alternative nuclear genetic code, not only in ciliates, but eukaryotes in general., 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 Elsevier Inc. All rights reserved.)

A recent report described a nonsense variant simultaneously creating a donor splice site, resulting in a truncated but functional protein. To explore the generalizability of this unique mechanism, we annotated >115,000 nonsense variants using SpliceAI. Between 0.61% (donor gain delta score >0.8, for high precision) and 2.57% (>0.2, for high sensitivity) of nonsense variants were predicted to create new donor splice sites at or upstream of the stop codon. These variants were less likely than other nonsense variants in the same genes to be classified as pathogenic/likely pathogenic in ClinVar (p < 0.001). Up to 1 in 175 nonsense variants were predicted to result in small in-frame deletions and loss-of-function evasion through this "manufactured splice rescue" mechanism. We urge caution when interpreting nonsense variants where manufactured splice rescue is a strong possibility and correlation with phenotype is challenging, as will often be the case with secondary findings and newborn genomic screening programs., (© 2023. The Author(s).)

Bacteriophages are key components of gut microbiomes, yet the phage colonization process in the infant gut remains uncertain. Here, we establish a large phage sequence database and use strain-resolved analyses to investigate DNA phage succession in infants throughout the first 3 years of life. Analysis of 819 fecal metagenomes collected from 28 full-term and 24 preterm infants and their mothers revealed that early-life phageome richness increases over time and reaches adult-like complexity by age 3. Approximately 9% of early phage colonizers, which are mostly maternally transmitted and infect Bacteroides, persist for 3 years and are more prevalent in full-term than in preterm infants. Although rare, phages with stop codon reassignment are more likely to persist than non-recoded phages and generally display an increase in in-frame reassigned stop codons over 3 years. Overall, maternal seeding, stop codon reassignment, host CRISPR-Cas locus prevalence, and diverse phage populations contribute to stable viral colonization., Competing Interests: Declaration of interests J.F.B. is a cofounder of Metagenomi., (Published by Elsevier Inc.)

Background: The order Lepidoptera has an abundance of species, including both agriculturally beneficial and detrimental insects. Molecular data has been used to investigate the phylogenetic relationships of major subdivisions in Lepidoptera, which has enhanced our understanding of the evolutionary relationships at the family and superfamily levels. However, the phylogenetic placement of many superfamilies and/or families in this order is still unknown. In this study, we determine the systematic status of the family Argyresthiidae within Lepidoptera and explore its phylogenetic affinities and implications for the evolution of the order. We describe the first mitochondrial (mt) genome from a member of Argyresthiidae, the apple fruit moth Argyresthia conjugella. The insect is an important pest on apples in Fennoscandia, as it switches hosts when the main host fails to produce crops., Results: The mt genome of A. conjugella contains 16,044 bp and encodes all 37 genes commonly found in insect mt genomes, including 13 protein-coding genes (PCGs), two ribosomal RNAs, 22 transfer RNAs, and a large control region (1101 bp). The nucleotide composition was extremely AT-rich (82%). All detected PCGs (13) began with an ATN codon and terminated with a TAA stop codon, except the start codon in cox1 is ATT. All 22 tRNAs had cloverleaf secondary structures, except trnS1, where one of the dihydrouridine (DHU) arms is missing, reflecting potential differences in gene expression. When compared to the mt genomes of 507 other Lepidoptera representing 18 superfamilies and 42 families, phylogenomic analyses found that A. conjugella had the closest relationship with the Plutellidae family (Yponomeutoidea-super family). We also detected a sister relationship between Yponomeutoidea and the superfamily Tineidae., Conclusions: Our results underline the potential importance of mt genomes in comparative genomic analyses of Lepidoptera species and provide valuable evolutionary insight across the tree of Lepidoptera species., (© 2023. The Author(s).)

Knowledge of the frequencies of synonymous triplets in protein-coding and non-coding DNA stretches can be used in gene finding. These frequencies depend on the GC content of the genome or parts of it. An example of interest is provided by stop codons. This is relevant for the definition of Open Reading Frames. A generic case is provided by pseudo-random sequences, especially when they code for complex proteins or when they are non-coding and not subject to selection pressure. Here, we calculate, for such sequences and for all 25 known genetic codes, the frequency of each amino acid and stop codon based on their set of codons and as a function of GC content. The amino acids can be classified into five groups according to the GC content where their expected frequency reaches its maximum. We determine the overall Shannon information based on groups of synonymous codons and show that it becomes maximum at a percent GC of 43.3% (for the standard code). This is in line with the observation that in most fungi, plants, and animals, this genomic parameter is in the range from 35 to 50%. By analysing natural sequences, we show that there is a clear bias for triplets corresponding to stop codons near the 5'- and 3'-splice sites in the introns of various clades., (© 2023. The Author(s).)

Background: The mitochondrial genome is a powerful tool for exploring and confirming species identity and understanding evolutionary trajectories. The genus Cambaroides , which consists of freshwater crayfish, is recognized for its evolutionary and morphological complexities. However, comprehensive genetic and mitogenomic data on species within this genus, such as C. wladiwostokiensis , remain scarce, thereby necessitating an in-depth mitogenomic exploration to decipher its evolutionary position and validate its species identity., Methods: The mitochondrial genome of C. wladiwostokiensis was obtained through shallow Illumina paired-end sequencing of total DNA, followed by hybrid assembly using both de novo and reference-based techniques. Comparative analysis was performed using available Cambaroides mitochondrial genomes obtained from National Center for Biotechnology Information (NCBI). Additionally, phylogenetic analyses of 23 representatives from three families within the Astacidea infraorder were employed using the PhyloSuite platform for sequence management and phylogenetic preparation, to elucidate phylogenetic relationships via Bayesian Inference (BI), based on concatenated mitochondrial fragments., Results: The resulting genome, which spans 16,391 base pairs was investigated, revealing 13 protein-coding genes, rRNAs ( 12S and 16S ), 19 tRNAs, and a putative control region. Comparative analysis together with five other Cambaroides mitogenomes retrieved from GenBank unveiled regions that remained unread due to challenges associated with the genome skimming technique. Protein-coding genes varied in size and typically exhibited common start (ATG) and stop (TAA) codons. However, exceptions were noted in ND5 (start codon: GTG) and ND1 (stop codon: TAG). Landscape analysis was used to explore sequence variation across the five available mitochondrial genomes of Cambaroides ., Conclusions: Collectively, these findings reveal variable sites and contribute to a deeper understanding of the genetic diversity in this genus alongside the further development of species-specific primers for noninvasive monitoring techniques. The partitioned phylogenetic analysis of Astacidea revealed a paraphyletic origin of Asian cambarids, which confirms the data in recent studies based on both multilocus analyses and integrative approaches., Competing Interests: The authors declare no conflict of interest., (© 2023 The Author(s). Published by IMR Press.)

The levels of the SELENOF selenoprotein are dramatically reduced in prostate cancer compared to adjacent benign tissue and reducing SELENOF in prostate epithelial cells results in the acquisition of features of the transformed phenotype. It was hypothesized that the aberrant increase in the eiF4a3 translation factor, which has an established role in RNA splicing and the regulation of selenoprotein translation, contributes to the lower levels of SELENOF. Using the available databases, eIF4a3 messenger RNA (mRNA) levels are elevated in prostate cancer compared to normal tissue as is the hypomethylation of the corresponding gene. Using a prostate cancer tissue microarray, we established that eiF4a3 levels are higher in prostate cancer tissue. Ectopic expression of eIF4a3 in prostate cancer cells reduced SELENOF levels and attenuated the readthrough of the UGA codon using a specialized reporter construct designed to examine UGA decoding, with the opposite effects observed using eIF4a3 knock-down constructs. Direct binding of eIF4a3 to the regulatory regions of SELENOF mRNA was established with pull-down experiments. Lastly, we show that an eIF4a3 inhibitor, eIF4a3-IN-2, increases SELENOF levels, UGA readthrough, and reduces binding of eIF4a3 to the SELENOF mRNA 3'-UTR in exposed cells. These data establish eIF4a3 as a likely prostate cancer oncogene and a regulator of SELENOF translation., (© 2023 The Authors. Molecular Carcinogenesis published by Wiley Periodicals LLC.)

Hemiculterella wui is an endemic small freshwater fish, distributed in the Pearl River system and Qiantang River, China. In this study, we identified and annotated the complete mitochondrial genome sequence of H. wui . The mitochondrial genome was 16,619 bp in length and contained 13 protein coding genes (PCGs), two rRNA genes, 22 tRNA genes, and one control region. The nucleotide composition of the mitochondrial genome was 29.9% A, 25.3% T, 27.4% C, and 17.5% G, respectively. Most PCGs used the ATG start codon, except COI and ATPase 8 started with the GTG start codon. Five PCGs used the TAA termination codon and ATPase 8 ended with the TAG stop codon, and the remaining seven genes used two incomplete stop codons (T and TA). Most of the tRNA genes showed classical cloverleaf secondary structures, except that tRNA Ser(AGY) lacked the dihydrouracil loop. The average Ka/Ks value of the ATPase 8 gene was the highest, while the average Ka/Ks value of the COI gene was the lowest. Phylogenetic analyses showed that H. wui has a very close relationship with Pseudohemiculter dispar and H . sauvagei . This study will provide a valuable basis for further studies of taxonomy and phylogenetic analyses in H. wui and Xenocyprididae.

We identified a novel abnormal hemoglobin variant caused by a frameshift mutation at nucleotide position 396 in exon 3 of the β-globin gene ( HBB ): NM&#95;000518:c.396delG. This variant causes an emergence of alternative amino acid sequence starting at codon 133 and a new stop codon formed in the 3' untranslated region (3'UTR) of the HBB gene at amino acid position 158. This β-globin gene variant was identified in a woman with a long history of hemolytic anemia. We named this variant Hb Ryazan after the proband's city of origin.

Duchenne muscular dystrophy (DMD) is a monogenic muscle-wasting disorder and a priority candidate for molecular and cellular therapeutics. Although rare, it is the most common inherited myopathy affecting children and so has been the focus of intense research activity. It is caused by mutations that disrupt production of the dystrophin protein, and a plethora of drug development approaches are under way that aim to restore dystrophin function, including exon skipping, stop codon readthrough, gene replacement, cell therapy and gene editing. These efforts have led to the clinical approval of four exon skipping antisense oligonucleotides, one stop codon readthrough drug and one gene therapy product, with other approvals likely soon. Here, we discuss the latest therapeutic strategies that are under development and being deployed to treat DMD. Lessons from these drug development programmes are likely to have a major impact on the DMD field, but also on molecular and cellular medicine more generally. Thus, DMD is a pioneer disease at the forefront of future drug discovery efforts, with these experimental treatments paving the way for therapies using similar mechanisms of action being developed for other genetic diseases., (© 2023. Springer Nature Limited.)

This study presents the first complete mitogenome of the Brazilian Atlantic bushmaster Lachesis with insights into snake evolution. The total length was 17,177 bp, consisting of 13 PCGs, 22 tRNAs, two rRNAs and a duplicate control region (CRs). Almost all genes were encoded by the heavy-strand, except for the ND6 gene and eight tRNAs (tRNA-Gln, Ala, Asn, Cys, Tyr, Ser[TGA anticodon], Glu, Pro). Only ATG, ATA, and ATC were starting codons for protein-coding sequences. Stop codons mainly were TAA, AGA, AGG, and TAG; whereas ND1, ND3, and CYTB terminated with incomplete stop codons. Phylogeny retrieved Lachesis within the Crotalinae as the sister group of Agkistrodon; and the Lachesis+Agkistrodon clade as the sister group of (Sistrurus+Crotalus)+Bothrops. The tree supports Crotalinae, Viperinae, and Azemiopinae in the Viperidae family, being sister taxa of Colubridae+(Elapidae+Psammophiidae). The mean genetic distance across 15 snake families and 57 nucleotide sequences was 0.37. The overall mean value of genetic distance across the Crotalinae was 0.23, with Lachesis muta exhibiting the shortest distance of 0.2 with Agkistrodon piscivorus, Protobothrops dabieshanensis and P. flavoviridis and the greatest 0.25 with Gloydius blomhoffii, Trimeresurus albolabris, S. miliarius, and Deinagkistrodon acutus. The complete Atlantic L. muta mitogenome presented herein is only the third annotated mitogenome from more than 430 described Brazilian snake species.

Translational readthrough of UGA stop codons by selenocysteine-specific tRNA (tRNASec) enables the synthesis of selenoproteins. Seryl-tRNA synthetase (SerRS) charges tRNASec with serine, which is modified into selenocysteine and delivered to the ribosome by a designated elongation factor (eEFSec in eukaryotes). Here we found that components of the human selenocysteine incorporation machinery (SerRS, tRNASec, and eEFSec) also increased translational readthrough of non-selenocysteine genes, including VEGFA, to create C-terminally extended isoforms. SerRS recognizes target mRNAs through a stem-loop structure that resembles the variable loop of its cognate tRNAs. This function of SerRS depends on both its enzymatic activity and a vertebrate-specific domain. Through eCLIP-seq, we identified additional SerRS-interacting mRNAs as potential readthrough genes. Moreover, SerRS overexpression was sufficient to reverse premature termination caused by a pathogenic nonsense mutation. Our findings expand the repertoire of selenoprotein biosynthesis machinery and suggest an avenue for therapeutic targeting of nonsense mutations using endogenous factors., (© The Author(s) 2023. Published by Oxford University Press on behalf of Nucleic Acids Research.)

Nonsense mutations cause several genetic diseases such as cystic fibrosis, Duchenne muscular dystrophy, β-thalassemia, and Shwachman-Diamond syndrome. These mutations induce the formation of a premature termination codon (PTC) inside the mRNA sequence, resulting in the synthesis of truncated polypeptides. Nonsense suppression therapy mediated by translational readthrough-inducing drugs (TRIDs) is a promising approach to correct these genetic defects. TRIDs generate a ribosome miscoding of the PTC named "translational readthrough" and restore the synthesis of full-length and potentially functional proteins. The new oxadiazole-core TRIDs NV848, NV914, and NV930 (NV) showed translational readthrough activity in nonsense-related in vitro systems. In this work, the possible off-target effect of NV molecules on natural termination codons (NTCs) was investigated. Two different in vitro approaches were used to assess if the NV molecule treatment induces NTC readthrough: (1) a study of the translational-induced p53 molecular weight and functionality; (2) the evaluation of two housekeeping proteins' (Cys-C and β2M) molecular weights. Our results showed that the treatment with NV848, NV914, or NV930 did not induce any translation alterations in both experimental systems. The data suggested that NV molecules have a specific action for the PTCs and an undetectable effect on the NTCs.