Implanting oxophilic metal in PtRu nanowires for hydrogen oxidation catalysis.

Bimetallic PtRu are promising electrocatalysts for hydrogen oxidation reaction in anion exchange membrane fuel cell, where the activity and stability are still unsatisfying. Here, PtRu nanowires were implanted with a series of oxophilic metal atoms (named as i-M-PR), significantly enhancing alkaline hydrogen oxidation reaction (HOR) activity and stability. With the dual doping of In and Zn atoms, the i-ZnIn-PR/C shows mass activity of 10.2 A mgPt+Ru-1 at 50 mV, largely surpassing that of commercial Pt/C (0.27 A mgPt-1) and PtRu/C (1.24 A mgPt+Ru-1). More importantly, the peak power density and specific power density are as high as 1.84 W cm-2 and 18.4 W mgPt+Ru-1 with a low loading (0.1 mg cm-2) anion exchange membrane fuel cell. Advanced experimental characterizations and theoretical calculations collectively suggest that dual doping with In and Zn atoms optimizes the binding strengths of intermediates and promotes CO oxidation, enhancing the HOR performances. This work deepens the understanding of developing novel alloy catalysts, which will attract immediate interest in materials, chemistry, energy and beyond.

Parenting self-efficacy and parenting stress mediates the effects of the association of perceived social support and readiness for discharge among parents of children with primary nephrotic syndrome.

PURPOSE: To investigate the level of readiness for discharge among parents of children with primary nephrotic syndrome and to explore the mediating role of parenting self-efficacy and parenting stress between perceived social support and readiness for discharge. DESIGN AND METHODS: A cross-sectional study was conducted in five large tertiary general hospitals in Hunan, China. Data related to demographics, perceived social support, parenting self-efficacy, parenting stress, and readiness for discharge were collected from 350 parents of children diagnosed with primary nephrotic syndrome. Path analysis was used to determine the mediating roles of parenting self-efficacy and parenting stress in the relationship between perceived social support and readiness for discharge. RESULTS: Parents of children with nephrotic syndrome in China experienced low perceived social support, low readiness for discharge, and high parenting stress. Factors influencing readiness for discharge include the child's age, duration of illness, first episode or relapse, parental literacy and marital status. Parenting self-efficacy and parenting stress mediated the effects of the association of perceived social support and readiness for discharge. CONCLUSION: Perceived social support influences the readiness of parents of children with nephrotic syndrome. Parenting self-efficacy and parenting stress have a chain mediating effect of the association of perceived social support and readiness for discharge. PRACTICE IMPLICATIONS: This study emphasizes the mediating role of the psychological state of the child's parents. Nurses should take steps to increase perceived social support and parenting self-efficacy of the child's parents and to reduce parenting stress in order to improve readiness for discharge.

Continuous Phase Regulation of a Pd-Te Hexagonal Nanoplate Library.

Phase regulation of noble metal-based nanomaterials provides a promising strategy for boosting the catalytic performance. However, realizing the continuous phase modulation in two-dimensional structures and unveiling the relevant structure-performance relationship remain significant challenges. In this work, we present the first example of continuous phase modulation in a library of Pd-Te hexagonal nanoplates (HNPs) from cubic-phase Pd4Te, rhombohedral-phase Pd20Te7, rhombohedral-phase Pd8Te3, and hexagonal-phase PdTe to hexagonal-phase PdTe2. Notably, the continuous phase regulation of the well-defined Pd-Te HNPs enables the successful modulation of the distance between adjacent Pd active sites, triggering an exciting way for tuning the relevant catalytic reactions intrinsically. The proof-of-concept oxygen reduction reaction (ORR) experiment shows a Pd-Pd distance-dependent ORR performance, where the hexagonal-phase PdTe HNPs present the best electrochemical performance in ORR (mass activity and specific activity of 1.02 A mg-1Pd and 1.83 mA cm-2Pd at 0.9 V vs RHE). Theoretical investigation reveals that the increased Pd-Pd distance relates to the weak *OH adsorption over Pd-Te HNPs, thus contributing to the remarkable ORR activity of PdTe HNPs. This work advances the phase-controlled synthesis of noble metal-based nanostructures, which gives huge impetus to the design of high-efficiency nanomaterials for diverse applications.

The Role of Iron Metabolism in Sepsis-associated Encephalopathy: a Potential Target.

Sepsis-associated encephalopathy (SAE) is an acute cerebral dysfunction secondary to infection, and the severity can range from mild delirium to deep coma. Disorders of iron metabolism have been proven to play an important role in a variety of neurodegenerative diseases by inducing cell damage through iron accumulation in glial cells and neurons. Recent studies have found that iron accumulation is also a potential mechanism of SAE. Systemic inflammation can induce changes in the expression of transporters and receptors on cells, especially high expression of divalent metal transporter1 (DMT1) and low expression of ferroportin (Fpn) 1, which leads to iron accumulation in cells. Excessive free Fe2+ can participate in the Fenton reaction to produce reactive oxygen species (ROS) to directly damage cells or induce ferroptosis. As a result, it may be of great help to improve SAE by treatment of targeting disorders of iron metabolism. Therefore, it is important to review the current research progress on the mechanism of SAE based on iron metabolism disorders. In addition, we also briefly describe the current status of SAE and iron metabolism disorders and emphasize the therapeutic prospect of targeting iron accumulation as a treatment for SAE, especially iron chelator. Moreover, drug delivery and side effects can be improved with the development of nanotechnology. This work suggests that treating SAE based on disorders of iron metabolism will be a thriving field.

Integrated bioinformatics analysis of noncoding RNAs with tumor immune microenvironment in gastric cancer.

In recent years, molecular and genetic research hotspots of gastric cancer have been investigated, including microRNAs, long noncoding RNAs (lncRNAs) and messenger RNA (mRNAs). The study on the role of lncRNAs may help to develop personalized treatment and identify potential prognostic biomarkers in gastric cancer. The RNA-seq and miRNA-seq data of gastric cancer were downloaded from the TCGA database. Differential analysis of RNA expression between gastric cancer samples and normal samples was performed using the edgeR package. The ceRNA regulatory network was visualized using Cytoscape. KEGG pathway analysis of mRNAs in the ceRNA network was performed using the clusterProfiler package. CIBERSORT was used to distinguish 22 immune cell types and the prognosis-related genes and immune cells were determined using Kaplan-Meier and Cox proportional hazard analyses. To estimate these nomograms, we used receiver operating characteristic and calibration curve studies. The ceRNA regulation network of gastric cancer was built in this study, and the genes in the network were analyzed for prognosis. A total of 980 lncRNAs were differentially expressed, of which 774 were upregulated and 206 were downregulated. A survival study identified 15 genes associated with gastric cancer prognosis, including VCAN-AS1, SERPINE1, AL139002.1, LINC00326, AC018781.1, C15orf54, hsa-miR-145. Monocytes and Neutrophils were associated with the survival rate of gastric cancer. Our research uncovers new ceRNA network for the detection, treatment, and monitoring of gastric cancer.

Molecular eidemiology of carbapenem-resistant Enterobacter cloacae complex in a tertiary hospital in Shandong, China.

BACKGROUND: The increasing incidence and prevalence of carbapenem-resistant Enterobacter cloacae complex (CREC) poses great challenges to infection prevention and disease treatment. However, much remains unknown about the clinical characteristics of CREC isolates. Our objective was to characterize antimicrobial resistance and, carbapenemase production in CREC with 36 CREC isolates collected from a tertiary hospital in Shandong, China. RESULTS: Three types of carbapenemases (NDM, IMP and VIM) were detected in these isolates. Among them, NDM carbapenemases were most prevalent, with a 61.2% (22/36) detection rate for NDM-1, 27.8% (10/36) for NDM-5 and 2.8% (1/36) for NDM-7. IMP-4 was found in two isolates and VIM-1 in only one isolate. The MLST analysis identified 12 different sequence types (STs), of which ST171 (27.8%) was the most prevalent, followed by ST418 (25.0%). ST171 isolates had significantly higher rates of resistance than other STs to gentamicin and tobramycin (Ps < 0.05), and lower rates of resistance to aztreonam than ST418 and other STs (Ps < 0.05). Among 17 carbapenemase-encoding genes, the blaNDM-5 gene was more frequently detected in ST171 than in ST418 and other isolates (Ps < 0.05). In contrast, the blaNDM-1 gene was more frequently seen in ST418 than in ST171 isolates. One novel ST (ST1965) was identified, which carried the blaNDM-1 gene. CONCLUSION: NDM-5 produced by ST171 and NDM-1 carbapenemase produced by ST418 were the leading cause of CREC in this hospital. This study enhances the understanding of CREC strains and helps improve infection control and treatment in hospitals.

Nutritive value of active volatile components of Anacardiaceae mango and their effects on carrier proteins function.

The effects of mango active volatile components (VOCs) on protein function were investigated from the perspective of nutrient transport. The active volatile components of five varieties of mango were analyzed by headspace solid phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS). The interaction mechanism between active volatile components and three carrier proteins was discussed by fluorescence spectroscopy, molecular docking and dynamic simulation. The results showed that there were 7 active components in the five mango varieties. The aroma components represented by 1-caryophyllene and ß-pinene were selected for further study. The interaction between VOCs small molecules and proteins is a static binding process, and its main force is hydrophobic interaction. The results of molecular simulation and spectral experiments showed that the binding ability of 1-caryophyllene and ß-pinene to ß-Lg was strong, so mango VOCs could possess a certain nutritional value in dairy products, expanding its application in dairy products in the food industry.

Feasibility and effect of emotional freedom therapy on sleep quality in patients with end-stage renal disease receiving maintenance hemodialysis: A pilot study.

OBJECTIVE: To explore the feasibility and efficacy of emotional freedom therapy (EFT) in improving sleep quality and managing negative emotions in end-stage renal disease patients on maintenance hemodialysis. METHODS: Between May 2021 and February 2022, 66 maintenance hemodialysis patients with sleep problems were recruited and randomized into an intervention and control group. The intervention group underwent a 12-week intervention of EFT. Two groups' hospital anxiety depression scale (HADS) scores, Pittsburgh sleep quality index (PSQI), and interdialysis weight gain (IDWG) before and one week after the formal intervention were collected and compared. Feasibility analysis was performed using a feasibility questionnaire and in-depth interviews with patients. RESULTS: Before the intervention, there was no statistical difference in the anxiety, depression, PSQI scores and IDWG between the two groups. After balancing the effects of gender and pre-intervention scores, two-way ANCOVA results showed that there were statistically significant differences between the two groups after the intervention in terms of anxiety, depression, sleep quality, sleep duration, daytime dysfunction and PSQI total score. However, interactions effect for IDWG was statistically significant. Simple effects analysis revealed a difference in post-intervention IDWG between the intervention and control groups for patients over 65 (p < 0.05). Most patients agreed or strongly agreed that the EFT was easy to schedule and they did not experience difficulties during learning the EFT process (respectively 75% and 71.88%). And 75% of the participants were willing to continue practicing EFT. Qualitative content analysis identified five prominent categories related to feasibility and acceptability: affirmation, benefits, communication, support and trust. CONCLUSION: EFT can relieve anxiety and depression, enhance sleep quality, and improve the physical condition of patients with end-stage renal disease receiving maintenance hemodialysis. As well, the EFT intervention is practicable, acceptable, and perceived as being beneficial to the patient.

A Novel Photoluminescent Ag/Cu Cluster Exhibits a Chromic Photoluminescence Response towards Volatile Organic Vapors.

A new Ag/Cu bimetallic cluster [Ag10Cu6(bdppthi)2(C≡CPh)12(EtOH)2](ClO4)4 (1, bdppthi = N,N'-bis(diphenylphosphanylmethyl)-tetrahydroimidazole) exhibited strong phosphorescent (PL) emission at 644 nm upon excitation at 400 nm. Removal of the coordinated EtOH molecules in 1 resulted in derivative 1a, which exhibited significant red-shifted emission at 678 nm. The structure and PL of 1 was restored on exposure to EtOH vapor. Cluster 1a also exhibited a vapor-chromic PL response towards other common organic solvent vapors including acetone, MeOH and MeCN. A PMMA film of 1a was developed as a reusable visible sensor for MeCN.

Gastric cancer-derived exosomes facilitate pulmonary metastasis by activating ERK-mediated immunosuppressive macrophage polarization.

Gastric cancer (GC) with pulmonary metastasis is one of the deadliest diseases in the world; however, the underlying pathological mechanisms and potential therapeutic targets remain to be elucidated. As exosomes play indispensable roles in the formation of premetastatic niches (PMN) and cancer metastasis. Therefore, investigating the underlying mechanisms of exosome-mediated pulmonary metastasis of GC may shed new light on identifying novel therapeutic targets for GC treatment. GC-derived exosomes were isolated from the conditioned medium of mouse forestomach carcinoma (MFC) cell line. The effects of MFC-derived exosomes on pulmonary macrophage polarization were analyzed by reverse- transcription polymerase chain reaction and flow cytometry. Expression of PD-L1 and other proteins was evaluated by Western blot. Exosomal microRNAs (miRNAs) were analyzed by microarray. GC-derived exosomes (GC-exo) accumulated in high numbers in the lungs and were ingested by macrophages. The extracellular-signal-regulated kinase (ERK) signaling pathway was activated by GC-exo, inducing macrophage immunosuppressive-phenotype differentiation and increased PD-L1 expression. miRNA-sequencing identified 130 enriched miRNAs in GC-exo. Among the enriched miRNAs, miR-92a-3p plays a major role in activating ERK signaling via inhibition of PTEN expression. In addition, inhibiting ERK signaling with PD98059 significantly reduced the expression of PD-L1 in macrophages and, therefore, reversed the immunosuppressive PMN and inhibited the colonization of GC cells in the lungs. This study identified a novel mechanism of GC-exo mediated PD-L1 expression in lung macrophages that facilitates lung PMN formation and GC pulmonary metastasis, which also provided a potential therapeutic target for GC with pulmonary metastasis treatment.

Comparative genomic analysis provides insight into the phylogeny and potential mechanisms of adaptive evolution of Sphingobacterium sp. CZ-2.

Sphingobacterium is a class of Gram-negative, non-fermentative bacilli that have received widespread attention due to their broad ecological distribution and oil degradation ability, but are rarely involved in infections. In this manuscript, a novel Sphingobacterium strain isolated from wildfire-infected tobacco leaves was named Sphingobacterium sp. CZ-2. NGS and TGS sequencing results showed a whole genome of 3.92 Mb with 40.68 mol% GC content and containing 3,462 protein-coding genes, 9 rRNA-coding genes and 50 tRNA-coding genes. Phylogenetic analysis, ANI and dDDH calculations all supported that Sphingobacterium sp. CZ-2 represented a novel species of the genus Sphingobacterium. Analysis of the specific genes of Sphingobacterium sp. CZ-2 by comparative genomics revealed that metal transport proteins encoded by the troD and cusA genes could maintain the balance of heavy metal ion concentrations in the internal environment of bacteria and avoid heavy metal toxicity while meeting the needs of growth and reproduction, and transport proteins encoded by the malG gene could keep nutrients required for the survival of bacteria. Synteny and genome evolutionary analyses of Sphingobacterium strains implicated that the gene family contraction as a major process in genome evolution, with insertional sequences leading to mutations, deletions and reversals of genes that help bacteria to withstand complex environmental changes. Complete genome sequencing and systematic comparative genomic analysis will contribute new insights into the adaptive evolution of this novel species and the genus Sphingobacterium.

Ampere-level current density ammonia electrochemical synthesis using CuCo nanosheets simulating nitrite reductase bifunctional nature.

The development of electrocatalysts capable of efficient reduction of nitrate (NO3-) to ammonia (NH3) is drawing increasing interest for the sake of low carbon emission and environmental protection. Herein, we present a CuCo bimetallic catalyst able to imitate the bifunctional nature of copper-type nitrite reductase, which could easily remove NO2- via the collaboration of two active centers. Indeed, Co acts as an electron/proton donating center, while Cu facilitates NOx- adsorption/association. The bio-inspired CuCo nanosheet electrocatalyst delivers a 100 ± 1% Faradaic efficiency at an ampere-level current density of 1035 mA cm-2 at -0.2 V vs. Reversible Hydrogen Electrode. The NH3 production rate reaches a high activity of 4.8 mmol cm-2 h-1 (960 mmol gcat-1 h-1). A mechanistic study, using electrochemical in situ Fourier transform infrared spectroscopy and shell-isolated nanoparticle enhanced Raman spectroscopy, reveals a strong synergy between Cu and Co, with Co sites promoting the hydrogenation of NO3- to NH3 via adsorbed *H species. The well-modulated coverage of adsorbed *H and *NO3 led simultaneously to high NH3 selectivity and yield.

A Novel Framework for Automation Technology Based on Machine Vision and Robotics in Electrical Power Inspection Processing.

As a well-known support, computer vision is a powerful factor to improve the application and development of the electronic system. Whether the power system can operate safely and stably can greatly influence the deduction of providence. All types of electric swinging devices are easily disturbed by various factors during the assistance operation. The ubiquitous power system that operates everywhere becomes extremely small once the electrical equipment is abandoned. For the current complexity system, if the old-fashioned hand-written visual monitoring system is still used, not only will their ability fails to meet the requirements but also the number of cumbersome, important, and financial context will be unsatisfactory. It is natural to reason about some problems. Serious problems are due to incompetent human investigation. Issues are not optimally handled during this period. The application of Coach Ken technology can fully utilize machine vision technology to analyze the salient data and identify dominant devices that support shape vision. Meanwhile, it can truly realize the supervision system of perception and machine control. In view of this, we in this work mainly expound the artifact recognition technology supported by machine vision reproduction. Besides, we disassemble the composition method of the electric power supply recognition system supported by machine vision parallel, in order to enhance the future work.

iPReditor-CMG: Improving a predictive RNA editor for crop mitochondrial genomes using genomic sequence features and an optimal support vector machine.

In crops, RNA editing is one of the most important post-transcriptional processes in which specific cytidines (C) in virtually all mitochondrial protein-coding genes are converted to uridines (U). Despite extensive recent research in RNA editing, exploring all of the C-to-U editing events efficiently on the genomic scale remains challengeable. Developing accurate prediction methods for the detection of RNA editing sites would dramatically reduce experimental determination. Therefore, we propose a novel method, iPReditor-CMG (improved predictive RNA editor for crop mitochondrial genomes), to predict crop mitochondrial editing sites using genome sequence and an optimised support vector machine (SVM). We first selected three mitochondrial genomes with known RNA editing sites from Arabidopsis thaliana, Brassica napus and Oryza sativa, released by NCBI, as the training and test sets. The genes and their transcripts from self-sequenced tobacco mitochondrial ATPase were selected as the validation set. The iPReditor-CMG first coded the genome sequences as numerical vectors and then performed an efficient feature selection on the high-dimensional feature space, where the SVM was employed in feature selection and following modelling. The average independent prediction accuracy of intraspecific editing sites across three species was 0.85, and up to 0.91 in A. thaliana, which outperformed the reference models. For the interspecific independent prediction, the prediction accuracy between dicotyledons was 0.78 and the accuracy between dicotyledons and monocotyledons was 0.56, which implies that there might be similarity in the C-to-U editing mechanism in close relatives. Finally, the best model was identified with an independent test accuracy of 0.91 and an AUC of 0.88, which suggested that five unreported feature sequences, i.e. TGACA, ACAAC, GTAGA, CCGTT and TAACA, are closely associated with the editing phenomenon. Multiple tests supported that the iPReditor-CMG could be effectively applied to predict editing sites in crop mitochondria, which may further contribute to understanding the mechanisms of site editing and post-transcriptional events in crop mitochondria.

Three-season rotation of chicory-tobacco-peanut with high biomass and bioconcentration factors effectively remediates cadmium-contaminated farmland.

Traditional phytoremediation is one approach to remediate heavy metal pollution. In developing countries, the key factor in promoting practical application of phytoremediation in polluted soils is selecting suitable plants that are tolerant to heavy metals and also produce products with economic value. Therefore, a field experiment was conducted with a three-season chicory-tobacco-peanut rotation to determine effects on remediation of cadmium (Cd)-contaminated farmland in China. All crops had strong Cd accumulation capacity, with bioconcentration factors of 6.61 to 11.97 in chicory, 3.85 to 21.61 in tobacco, and 1.36 to 7.0 in peanut. Yield of total dry biomass reached 32.4 t ha-1, and the Cd phytoextraction efficiency was 10.3% per year. Aboveground tissues of the three crops accounted for 83.9 to 91.2% of total biomass in the rotation experiment. Cd content in peanut grain and oil met the National Food Safety Standard of China (0.5 mg kg-1, GB 2762-2017) and the Food Contaminant Limit of the European Union (0.1 mg kg-1, 18,812,006). Therefore, in addition to phytoremediation of Cd-contaminated soils, the chicory-tobacco-peanut rotation system can also produce economic benefits for local farmers.

Capturing 3D Chromatin Maps of Human Primary Monocytes: Insights From High-Resolution Hi-C.

Although the variation in chromatin architecture during adaptive immune responses has been thoroughly investigated, the 3D landscape of innate immunity is still unknown. Herein, chromatin regulation and heterogeneity among human primary monocytes were investigated. Peripheral blood was collected from two healthy persons and two patients with systemic lupus erythematosus (SLE), and CD14+ monocytes were selected to perform Hi-C, RNA-seq, ATAC-seq and ChIP-seq analyses. Raw data from the THP1 cell line Hi-C library were used for comparison. For each sample, we constructed three Hi-C libraries and obtained approximately 3 billion paired-end reads in total. Resolution analysis showed that more than 80% of bins presented depths greater than 1000 at a 5 kb resolution. The constructed high-resolution chromatin interaction maps presented similar landscapes in the four individuals, which showed significant divergence from the THP1 cell line chromatin structure. The variability in chromatin interactions around HLA-D genes in the HLA complex region was notable within individuals. We further found that the CD16-encoding gene (FCGR3A) is located at a variable topologically associating domain (TAD) boundary and that chromatin loop dynamics might modulate CD16 expression. Our results indicate both the stability and variability of high-resolution chromatin interaction maps among human primary monocytes. This work sheds light on the potential mechanisms by which the complex interplay of epigenetics and spatial 3D architecture regulates chromatin in innate immunity.

A Photoluminescent Ag10 Cu6 Cluster Stablized by a PNNP Ligand and Phenylacetylides Selectively and Reversibly Senses Ammonia in Air and Water.

A photoluminescent bimetallic cluster [Ag10 Cu6 (bdppthi)2 (C≡CPh)12 (MeOH)2 (H2 O)](ClO4 )4 (1, bdppthi=N,N'-bis(diphenylphosphanylmethyl)-tetrahydroimidazole} was synthesized from the PNNP type ligand bdppthi generated in-situ. Upon excitation at 365 nm, 1 exhibited strong phosphorescent emission at 630 nm, which was selectively quenched by NH3 in air or water. The sensing of NH3 was rapid and recoverable, with detection limits of 53 ppm (v/v) in N2 and 21 µmol/L (0.36 ppm, w/w) for NH3 ⋅ H2 O in water. Cluster 1 could potentially serve as a bifunctional chemical sensor for the efficient detection of ammonia in waste-gas and waste-water.

A photoluminescent Au(I)/Ag(I)/PNN coordination complex for relatively rapid and reversible alcohol sensing.

Trinuclear complex [Au2Ag(dppmaphen)2(CN)2]PF6 photoluminesces on exposure to low molecular weight alcohols. This emission is likely due to C-Hπ interactions between the analyte and -PPh2 group, that inhibits non-radiative relaxation of the photoexcited state. Photoluminescene was quenched by removing the analyte under a stream of N2 or replacing it with H2O. This on/off switching was clearly visible, relatively rapid and recyclable.

Effect of ABCG1 gene DNA methylations on the lipid-lowering efficacy of simvastatin.

Aim: We investigated the effect of ABCG1 gene DNA methylation in the lipid-lowering efficacy of simvastatin. Materials & methods: An extreme sampling approach was used to select 211 individuals from the top and bottom 15% of adjusted lipid-lowering response residuals to simvastatin after eight consecutive weeks. DNA methylation was measured before treatment by the MethylTarget bisulfite sequencing method. Results:ABCG1_A DNA methylations were negatively associated with baseline high-density lipoprotein cholesterol (HDL-C) and the change in HDL-C after treatment. ABCG1_C methylations were also related to the change in triglyceride and HDL-C. Moreover, mean ABCG1_A and ABCG1_C methylations explain 7.2% of the ΔTC (total cholesterol) and 17.5% of the ΔHDL-C level variability, respectively. Conclusion: DNA methylations at the ABCG1 gene play significant inhibitory effects in the lipid-lowering therapy of simvastatin.

Comparative Analysis of the Mitochondrial Genomes of Nicotiana tabacum: Hints Toward the Key Factors Closely Related to the Cytoplasmic Male Sterility Mechanism.

BACKGROUND: Cytoplasmic male sterility (CMS) is a complex phenomenon of plant sterility that can produce non-functional pollen. It is caused by mutation, rearrangement or recombination in the mitochondrial genome. So far, the systematic structural characteristics of the changes in the mitochondrial genome from the maintainer lines to the CMS lines have not been reported in tobacco. RESULTS: The mitochondrial genomes of the flower buds from both CMS lines and maintainer lines of two Nicotiana tabacum cultivars (YY85, sYY85, ZY90, and sZY90) were sequenced using the PacBio and Illumina Hiseq technology, and several findings were produced by comparative analysis based on the de novo sequencing. (1) The genomes of the CMS lines were larger, and the different areas were mostly non-coding regions. (2) A large number of rearrangement regions were detected in the CMS lines, with many translocation regions. (3) Thirteen gene clusters were shared by the four mitochondrial genomes, among which two of the gene clusters, nad2-sdh3 and nad6-rps4, were far from each other in the CMS lines. (4) Thirty-three protein-coding genes were conserved in four mitochondrial genomes. However, nad3 was detected one additional copy in the maintainer lines, and sequence differences were revealed in the four candidate genes (atp6, cox2, nad2, and sdh3). Importantly, the evolutionary tree based on the four genes could be used to distinguish the CMS lines and the maintainer lines well for the sequenced mitochondrial genomes of the tobacco. (5) Sixteen CMS-specific open reading frames (ORFs) were found, three of which (orf91, orf115b, and orf100) were previously reported. (6) The differences in intensity of the protein-protein (PPI) interaction in ATP6 were further verified using the yeast two-hybrid analysis. CONCLUSION: Although the majority of the sequences, genes and gene clusters were shared by the mitochondrial genomes of the maintainer and the CMS lines in tobacco, extensive structural variations identified with comprehensive analysis based on the mitochondrial genomes, including rearrangement, gene order, the mitochondrial genome expansion and shrinkage events, might be related to CMS. Additionally, the candidate protein-coding genes and CMS-specific ORFs were closely associated with the CMS mechanism. Verification experiments of one of the candidate genes were performed, and the validity of our research results was supported.