Systematic single-cell analysis reveals dynamic control of transposable element activity orchestrating the endothelial-to-hematopoietic transition.

BACKGROUND: The endothelial-to-hematopoietic transition (EHT) process during definitive hematopoiesis is highly conserved in vertebrates. Stage-specific expression of transposable elements (TEs) has been detected during zebrafish EHT and may promote hematopoietic stem cell (HSC) formation by activating inflammatory signaling. However, little is known about how TEs contribute to the EHT process in human and mouse. RESULTS: We reconstructed the single-cell EHT trajectories of human and mouse and resolved the dynamic expression patterns of TEs during EHT. Most TEs presented a transient co-upregulation pattern along the conserved EHT trajectories, coinciding with the temporal relaxation of epigenetic silencing systems. TE products can be sensed by multiple pattern recognition receptors, triggering inflammatory signaling to facilitate HSC emergence. Interestingly, we observed that hypoxia-related signals were enriched in cells with higher TE expression. Furthermore, we constructed the hematopoietic cis-regulatory network of accessible TEs and identified potential TE-derived enhancers that may boost the expression of specific EHT marker genes. CONCLUSIONS: Our study provides a systematic vision of how TEs are dynamically controlled to promote the hematopoietic fate decisions through transcriptional and cis-regulatory networks, and pre-train the immunity of nascent HSCs.

Enhancing diabetic wound healing with a pH/glucose dual-responsive hydrogel for ROS clearance and antibacterial activity.

Currently, the treatment of diabetic wounds in clinical practice is still unsatisfactory due to the risks of oxidative damage and bacterial infection during the healing process. An optimal wound dressing should exhibit robust capabilities in scavenging reactive oxygen species (ROS) and combatting bacterial growth. In this study, we utilized borax as a crosslinker and prepared a pH/glucose dual-responsive composite hydrogel based on poly(vinyl alcohol) (PVA), sodium alginate (SA), and tannic acid (TA). This hydrogel, loaded with cerium dioxide, serves as an effective ROS scavenger, promoting wound closure by reducing the level of ROS in the wound area. Additionally, the hydrogel can release the antibacterial drug ofloxacin in response to the low pH and high glucose microenvironment in infected wounds. Results from skin defect model in diabetic mice demonstrated this ROS-scavenging and antibacterial hydrogel can suppress inflammation and accelerate wound healing. In summary, our work provides a new perspective on a local and stimulus-responsive drug delivery strategy for treating diabetic wounds.

Whole-transcriptome profiling reveals potential biomarkers for the reversal of thymic epithelial cell senescence by umbilical cord mesenchymal stem cells.

BACKGROUND: Reduced numbers and dysfunction of thymic epithelial cells (TECs) are important factors of thymic degeneration. Previous studies have found that umbilical cord mesenchymal stem cells (UCMSCs) reverse the structure and function of the senescent thymus in vivo. However, the transcriptomic regulation mechanism is unclear. METHODS: TECs were cultured with H2O2 for 72 hours to induce senescence. UCMSCs were cocultured with senescent TECs for 48 hours to detect SA-ß-gal, P16 and Ki67. The cocultured TECs were collected for lncRNA, mRNA and miRNA sequencing to establish a competitive endogenous regulatory network (ceRNA). And RT-qPCR, immunofluorescence staining, and western blot were used to identified key genes. RESULTS: Our results showed that H2O2 induced TEC aging and that UCMSCs reversed these changes. Compared with those in aged TECs, 2260 DE mRNAs, 1033 DE lncRNAs and 67 DE miRNAs were differentially expressed, and these changes were reversed by coculturing the cells with UCMSCs. Differential mRNA enrichment analysis of ceRNA regulation revealed that the PI3K-AKT pathway was a significant signaling pathway. UCMSC coculture upregulated VEGFA, which is the upstream factor of the PI3K-AKT signaling pathway, and the expression of the key proteins PI3K and AKT. Thus, the expression of the cell cycle suppressor P27, which is downstream of the PI3K-AKT signaling pathway, was downregulated, while the expression of the cell cycle regulators CDK2 and CCNE was upregulated. CONCLUSION: UCMSC coculture upregulated the expression of VEGFA, activated the PI3K-AKT signaling pathway, increased the expression of CDK2 and CCNE, decreased the expression of P27, and promoted the proliferation of TECs.

Diagnostic significance of combined anti-extractable nuclear antigens antibody, anti-cardiolipin antibody and anti-ß2-glycoprotein 1 in systemic lupus erythematosus patients.

Objective: This study aimed to investigate the diagnostic value of a combination of anti-extractable nuclear antigens (anti-ENA) antibodies, anti-cardiolipin antibodies (ACA), and anti-ß2-glycoprotein 1 (anti-ß2 GPI) antibodies in patients with systemic lupus erythematosus (SLE). Methods: A total of 646 SLE patients diagnosed in our hospital between January 2020 and April 2023 were randomly selected as study subjects, while 2075 non-SLE subjects during the same period were selected as the control group. The levels of anti-extractable nuclear antigen (ENA) antibody, ACA, and anti-ß2 GPI antibodies were measured, and their diagnostic value for SLE was analyzed using binary logistic regression and receiver operating characteristic (ROC) analysis. Results: The rates of positive anti-RNP, anti-Sm, anti-Sjögren's syndrome (SS-A), and anti-SS-B antibodies in the SLE patient group were significantly higher than those in the control group, with all differences being statistically significant (P < 0.01). The rates of positive ACA, as well as the levels of ACA IgA, ACA IgG, and ACA IgM, were significantly higher in the SLE patients group compared to the control group, with statistically differences (P < 0.05). Similarly, the rates of positive anti-ß2 GPI antibodies, anti-ß2 GPI antibody IgA, IgG, and IgM, were significantly higher in the SLE patient group compared to the control group, with all differences being statistically significant (P < 0.01). Gender, age, positive anti-JO1 antibodies, positive anti-RNP antibodies, positive anti-SS-A antibodies, positive ACA, high level ACA IgG and ACA IgM, positive anti-ß2 GPI antibodies, and high level of anti-ß2 GPI antibody IgA were identified as independent risk factors for the development of SLE (P < 0.05). The combined use of age, sex, anti-ENA antibodies, ACA, and anti-ß2 GPI antibodies yielded a sensitivity of 82.12% (80.41%-83.71%) and a specificity of 80.03% (76.77%-82.93%) for the diagnosis of SLE. Conclusion: The combination of age, sex, anti-ENA antibodies, ACA, and anti-ß2 GPI antibodies shows high diagnostic value for SLE and holds potential for clinical application as an auxiliary diagnostic tool for SLE.

Mesenchymal stem cells reverse thymus aging by reprogramming the DNA methylation of thymic epithelial cells.

Background: A decrease in the number and activity of thymic epithelial cells (TECs) is an important factor in thymic degeneration. Mesenchymal stem cells (MSCs) treating thymic ageing is a promising strategy, but the DNA methylation modification mechanism in TECs remains unclear. Methods: Aged rhesus monkeys were treated with MSCs to establish a thymic senescence model, and hematoxylin-eosin (HE) staining, immunofluorescence staining, and ELISA were performed to observe the structure and function of the thymus. TEC aging model and MSCs co-culture system were established to detect DNA methylation modification and transcriptomic changes, correlation analysis between transcription factor methylation and mRNA expression, and q-PCR, immunofluorescence staining, and Western blot were used to identified key genes. Results: MSCs improved the structure and function of thymus in elderly macaque monkeys; reduced the expression levels of ß-Gal, P16, and P21; and increased the activity of aging TECs. There were 501 genes with increased methylation in the promoter region in the treated group compared with the untreated group, among which 23 genes were involved in the negative regulation of cell growth, proliferation and apoptosis, while 591 genes had decreased methylation, among which 37 genes were associated with promoting cell growth and proliferation and inhibiting apoptosis. Furthermore, 66 genes showed a negative correlation between promoter methylation levels and gene transcription; specifically, PDE5A, DUOX2, LAMP1 and SVIL were downregulated with increased methylation, inhibiting growth and development, while POLR3G, PGF, CHTF18, KRT17, FOXJ1, NGF, DYRK3, LRP8, CDT1, PRELID1, F2R, KNTC1 and TRIM3 were upregulated with decreased methylation, promoting cell growth. Conclusion: MSCs improve the structure and function of aged thymus, which involves the regulation of DNA methylation profiles and a decrease in the methylation level of the transcription factor NGF to specifically upregulate KRT17 and FOXJ1 to promote the proliferation of TECs.

Curcumin attenuates aflatoxin B1-induced ileum injury in ducks by inhibiting NLRP3 inflammasome and regulating TLR4/NF-κB signaling pathway.

Aflatoxin B1 (AFB1) is a widespread toxic contamination in feed for animals. The primary active component of turmeric, curcumin (Cur), is an antioxidant and an anti-inflammatory. However, it is yet unknown how AFB1 affects the intestinal epithelial barrier and whether Cur acts as a protective mechanism when exposed to AFB1. Here, we explored the mechanism of AFB1-induced intestinal injury from intestinal epithelial barrier, inflammation, pyroptosis, and intestinal flora, and evaluated the protective role of Cur. We found that AFB1 caused weight loss and intestinal morphological damage that is mainly characterized by shortened intestinal villi, deepened crypts, and damaged intestinal epithelium. Exposure to AFB1 decreased the expression of Claudin-1, MUC2, ZO-1, and Occludin and increased the expression of pyroptosis-related factors (NLRP3, GSDMD, Caspase-1, IL-1ß, and IL-18) and inflammation-related factors (TLR4, NF-κB, IκB, IFN-γ, and TNF-α). Furthermore, ileal gut microbiota was altered, and simultaneously, the Lactobacillus abundance was decreased. The gut microbiota interacts with a wide range of physiologic functions and disease development in the host through its metabolites, and disturbances in gut microbial metabolism can cause functional impairment of the ileum. Meanwhile, Cur can ameliorate histological ileum injuries and intestinal flora disturbance caused by AFB1. We found that Cur reversed the effects of AFB1 through modulating both NLRP3 inflammasome and the TLR4/NF-κB signaling pathway. In conclusion, AFB1 can induce inflammatory damage and pyroptosis in duck ileum, while Cur has obviously protective effects on all the above damages.

Perception of the Biocontrol Potential and Palmitic Acid Biosynthesis Pathway of Bacillus subtilis H2 through Merging Genome Mining with Chemical Analysis.

Bacillus has been widely studied for its potential to protect plants from pathogens. Here, we report the whole genome sequence of Bacillus subtilis H2, which was isolated from the tea garden soil of Guiyang Forest Park. Strain H2 showed a broad spectrum of antagonistic activities against many plant fungal pathogens and bacteria pathogens, including the rice blast fungus Magnaporthe oryzae, and showed a good field control effect against rice blast. The complete genome of B. subtilis H2 contained a 4,160,635-bp circular chromosome, with an average G + C content of 43.78%. Through the genome mining of strain H2, we identified 7 known antimicrobial compound biosynthetic gene clusters (BGCs) including sporulation killing factor, surfactin, bacillaene, fengycin, bacillibactin, subtilosin A, and bacilysin. Palmitic acid (PA), a secondary metabolite, was detected and identified in the H2 strain through genome mining analysis and gas chromatography-mass spectrometry (GC-MS). Additionally, we propose, for the first time, that the type II fatty acid synthesis (FAS) pathway in Bacillus is responsible for PA biosynthesis. This finding was confirmed by studying the antimicrobial activity of PA and conducting reverse transcription-quantitative polymerase chain reaction (RT-qPCR) experiments. We also identified numerous genes associated with plant-bacteria interactions in the H2 genome, including more than 94 colonization-related genes, more than 34 antimicrobial genes, and more than 13 plant growth-promoting genes. These findings contribute to our understanding of the biocontrol mechanisms of B. subtilis H2 and have potential applications in crop disease control.

An age classification model based on DNA methylation biomarkers of aging in human peripheral blood using random forest and artificial neural network.

Recent epigenetic studies have revealed a strong association between DNA methylation and aging and lifespan, which changes (increases or decreases) with age. Based on these, the construction of age prediction models associated with DNA methylation levels can be used to infer biological ages closer to the functional state of the organism. We downloaded methylation data from the Gene Expression Omnibus (GEO) public database for normal peripheral blood samples from people of different ages. We grouped the samples according to age (18-35 years and >50 years), screened the methylation sites that differed between the two groups, identified 44 differentially methylated sites, and subsequently obtained 11 age-related characteristic methylation sites using the random forest method. Then, we constructed an age classification model with these 11 characteristic methylation sites using an artificial neural network and evaluated its efficacy. The age classification model was constructed by an artificial neural network and its efficacy was evaluated. The model predicted an area under the curve (AUC) of 0.97 in the validation set and accurately distinguished between those aged 18-35 and >50 years. Furthermore, the levels of these 11 characteristic methylation sites also differed significantly between the two sets of samples in the validation set, including six newly identified age-related methylation sites (P<0.001). Finally, we constructed a multifactor regulatory network based on the corresponding genes of age-related methylation sites to reveal the transcriptional and post-transcriptional regulation patterns. As a result of the increasing problem of aging, the age classification model we constructed allows us to accurately distinguish different age groups at the molecular level, which will be more predictive than chronological age for assessing individual aging and future health status.

Angiotensin-(1-7) Modulates the Warburg Effect to Alleviate Inflammation in LPS-Induced Macrophages and Septic Mice.

Purpose: Inflammation triggers a metabolic shift in macrophages from oxidative phosphorylation to glycolysis, a phenomenon known as the Warburg effect. This metabolic reprogramming worsens inflammation and cascades into organ damage. Angiotensin-(1-7) [Ang-(1-7)], a small molecule, has demonstrated anti-inflammatory properties. This study investigates whether Ang-(1-7) mitigates inflammation in LPS-induced macrophages and septic mice by regulating the Warburg effect in immune metabolism. Methods: The study induced macrophages with LPS in vitro and measured inflammatory factors using ELISA and Western blot. Key enzymes in glycolysis, mitochondrial respiratory complexes, and citrate pathway key molecules were assessed using Western blot and qRT-PCR. Mitochondrial membrane potential (MMP), lactate, and ATP were measured using assay kits. In vivo, a mouse model of sepsis induced by LPS was used. Kidney tissues were examined for pathological and mitochondrial ultrastructural alterations. The levels of inflammatory factors in mouse serum, glycolysis and citrate pathway-related molecules in the kidney were assessed using qRT-PCR, Western blot, and immunofluorescence techniques. Additionally, MMP, lactate, and ATP in the kidney were measured using assay kits. Results: In vitro experiments demonstrated that Ang-(1-7) inhibited the levels of inflammatory factors in LPS-treated RAW264.7 cells. It also reduced the expression of key glycolytic enzymes HK2, PFKFB3, and PKM2, as well as lactate levels. Additionally, it decreased intracellular citrate accumulation, enhanced mitochondrial respiratory complexes I and III, and ATP levels. Ang-(1-7) alleviated MMP damage, modulated citrate pathway-related molecules, including SLC25A1, ACLY, and HIF-1α. In vivo experiments showed that Ang-(1-7) lowered glycolysis levels in septic mice, improved mitochondrial ultrastructure and function, mitigated inflammation and renal tissues damage in septic mice, and suppressed the expression of key molecules in the citrate pathway. Conclusion: In conclusion, Ang-(1-7) can regulate the Warburg effect through the citrate pathway, thereby alleviating inflammation in LPS-induced macrophages and septic mice.

Biocontrol potential of endophytic bacterium Bacillus altitudinis GS-16 against tea anthracnose caused by Colletotrichum gloeosporioides.

Background: As one of the main pathogens causing tea anthracnose disease, Colletotrichum gloeosporioides has brought immeasurable impact on the sustainable development of agriculture. Given the adverse effects of chemical pesticides to the environment and human health, biological control has been a focus of the research on this pathogen. Bacillus altitudinis GS-16, which was isolated from healthy tea leaves, had exhibited strong antagonistic activity against tea anthracnose disease. Methods: The antifungal mechanism of the endophytic bacterium GS-16 against C. gloeosporioides 1-F was determined by dual-culture assays, pot experiments, cell membrane permeability, cellular contents, cell metabolism, and the activities of the key defense enzymes. Results: We investigated the possible mechanism of strain GS-16 inhibiting 1-F. In vitro, the dual-culture assays revealed that strain GS-16 had significant antagonistic activity (92.03%) against 1-F and broad-spectrum antifungal activity in all tested plant pathogens. In pot experiments, the disease index decreased to 6.12 after treatment with GS-16, indicating that strain GS-16 had a good biocontrol effect against tea anthracnose disease (89.06%). When the PE extract of GS-16 treated mycelial of 1-F, the mycelial appeared deformities, distortions, and swelling by SEM observations. Besides that, compared with the negative control, the contents of nucleic acids, protein, and total soluble sugar of GS-16 group were increased significantly, indicating that the PE extract of GS-16 could cause damage to integrity of 1-F. We also found that GS-16 obviously destroyed cellular metabolism and the normal synthesis of cellular contents. Additionally, treatment with GS-16 induced plant resistance by increasing the activities of the key defense enzymes PPO, SOD, CAT, PAL, and POD. Conclusions: We concluded that GS-16 could damage cell permeability and integrity, destroy the normal synthesis of cellular contents, and induce plant resistance, which contributed to its antagonistic activity. These findings indicated that strain GS-16 could be used as an efficient microorganism for tea anthracnose disease caused by C. gloeosporioides.

Ang-(1-7)/Mas axis ameliorates bleomycin-induced pulmonary fibrosis in mice via restoration of Nox4-Nrf2 redox homeostasis.

Pulmonary fibrosis (PF) is a chronic, progressive interstitial lung disease characterized by diffuse alveolar inflammation, fibroblast differentiation, and the excessive deposition of extracellular matrix. During the progression of PF, redox imbalance caused by excessive reactive oxygen species (ROS) production can result in further destruction of lung tissue. At present, data on the role of NADPH oxidase-4 (Nox4)-nuclear factor erythroid 2-related factor 2 (Nrf2) redox imbalance in PF are limited. The angiotensin (1-7) [Ang-(1-7)]/Mas axis is a protective axis in the renin-angiotensin system (RAS) that exerts antifibrotic effects. Therefore, this study aimed to investigate the role of the Ang-(1-7)/Mas axis in PF and to explore its mechanism in depth. The results revealed that the Ang-(1-7)/Mas axis inhibited TGF-ß1-induced lung fibroblast differentiation, inflammation and fibrosis in bleomycin (BLM)-treated lung tissue. A mechanistic study suggested that the Ang-(1-7)/Mas axis may restore Nox4-Nrf2 redox homeostasis by upregulating the level of p62, reducing oxidative stress and the inflammatory response and thus delaying the progression of lung fibrosis. This study provides a theoretical basis for exploring the mechanisms of PF and therapeutic targets for PF.

Arsenic-Induced Ferroptosis in Chicken Hepatocytes via the Mitochondrial ROS Pathway.

Arsenic has been shown to be highly toxic and can cause liver damage. Previous studies have shown that arsenic causes severe liver damage and induces accumulation of reactive oxygen species (ROS). This study aimed to investigate the effects of ferroptosis on the liver in arsenic trioxide (ATO) and to explore the underlying mechanisms. We confirmed the hepatotoxic effects of arsenic by in vivo and in vitro experiments. After 28 days of administration of arsenic trioxide (4-mg/kg, 8-mg/kg) by gavage, chickens exhibited body weight loss and liver damage in a dose-dependent manner. In addition, in vivo and in vitro western blot and real-time fluorescence quantitative PCR analyses simultaneously indicated that ferroptosis might be the main pathway of arsenic-induced liver injury. Finally, Mito-TEMPO effectively eliminated the ROS accumulation in mitochondria, significantly attenuating the process of cellular ferroptosis. In summary, the hepatotoxic effects of arsenic are related to ferroptosis, and the hepatic ferroptosis process of arsenic is regulated by mitochondrial ROS (MtROS). Our study reveals new mechanisms of arsenic toxicity to the liver, which may deepen our understanding of arsenic toxicology.

Hematopoietic aging: cellular, molecular, and related mechanisms.

ABSTRACT: Aging is accompanied by significant inhibition of hematopoietic and immune system function and disruption of bone marrow structure. Aging-related alterations in the inflammatory response, immunity, and stem cell niches are at the root of hematopoietic aging. Understanding the molecular mechanisms underlying hematopoietic and bone marrow aging can aid the clinical treatment of aging-related diseases. In particular, it is unknown how the niche reprograms hematopoietic stem cells (HSCs) in an age-dependent manner to maintain normal hematopoiesis in elderly individuals. Recently, specific inhibitors and blood exchange methods have been shown to reshape the hematopoietic niche and reverse hematopoietic aging. Here, we present the latest scientific discoveries related to hematopoietic aging and hematopoietic system rejuvenation, discuss the relationships between hematopoietic niche aging and HSC aging, and describe related studies on stem cell-mediated regulation of hematopoietic aging, aiming to provide new ideas for further study.

An integrated nationwide genomics study reveals transmission modes of typhoid fever in China.

IMPORTANCE: Typhoid fever is a life-threatening disease caused by Salmonella enterica serovar Typhi, resulting in a significant disease burden across developing countries. Historically, China was very much close to the global epicenter of typhoid, but the role of typhoid transmission within China and among epicenter remains overlooked in previous investigations. By using newly produced genomics on a national scale, we clarify the complex local and global transmission history of such a notorious disease agent in China spanning the most recent five decades, which largely undermines the global public health network.

Multimodal Attention Dynamic Fusion Network for Facial Micro-Expression Recognition.

The emotional changes in facial micro-expressions are combinations of action units. The researchers have revealed that action units can be used as additional auxiliary data to improve facial micro-expression recognition. Most of the researchers attempt to fuse image features and action unit information. However, these works ignore the impact of action units on the facial image feature extraction process. Therefore, this paper proposes a local detail feature enhancement model based on a multimodal dynamic attention fusion network (MADFN) method for micro-expression recognition. This method uses a masked autoencoder based on learnable class tokens to remove local areas with low emotional expression ability in micro-expression images. Then, we utilize the action unit dynamic fusion module to fuse action unit representation to improve the potential representation ability of image features. The state-of-the-art performance of our proposed model is evaluated and verified on SMIC, CASME II, SAMM, and their combined 3DB-Combined datasets. The experimental results demonstrated that the proposed model achieved competitive performance with accuracy rates of 81.71%, 82.11%, and 77.21% on SMIC, CASME II, and SAMM datasets, respectively, that show the MADFN model can help to improve the discrimination of facial image emotional features.

Multi-scale fusion visual attention network for facial micro-expression recognition.

Introduction: Micro-expressions are facial muscle movements that hide genuine emotions. In response to the challenge of micro-expression low-intensity, recent studies have attempted to locate localized areas of facial muscle movement. However, this ignores the feature redundancy caused by the inaccurate locating of the regions of interest. Methods: This paper proposes a novel multi-scale fusion visual attention network (MFVAN), which learns multi-scale local attention weights to mask regions of redundancy features. Specifically, this model extracts the multi-scale features of the apex frame in the micro-expression video clips by convolutional neural networks. The attention mechanism focuses on the weights of local region features in the multi-scale feature maps. Then, we mask operate redundancy regions in multi-scale features and fuse local features with high attention weights for micro-expression recognition. The self-supervision and transfer learning reduce the influence of individual identity attributes and increase the robustness of multi-scale feature maps. Finally, the multi-scale classification loss, mask loss, and removing individual identity attributes loss joint to optimize the model. Results: The proposed MFVAN method is evaluated on SMIC, CASME II, SAMM, and 3DB-Combined datasets that achieve state-of-the-art performance. The experimental results show that focusing on local at the multi-scale contributes to micro-expression recognition. Discussion: This paper proposed MFVAN model is the first to combine image generation with visual attention mechanisms to solve the combination challenge problem of individual identity attribute interference and low-intensity facial muscle movements. Meanwhile, the MFVAN model reveal the impact of individual attributes on the localization of local ROIs. The experimental results show that a multi-scale fusion visual attention network contributes to micro-expression recognition.

Toxicity of inorganic arsenic to animals and its treatment strategies.

In nature, arsenic is mostly found in the form of inorganic compounds. Inorganic arsenic compounds have a variety of uses and are currently used in the manufacture of pesticides, preservatives, pharmaceuticals, etc. While inorganic arsenic is widely used, arsenic pollution is increasing worldwide. Public hazards caused by arsenic contamination of drinking water and soil are becoming increasingly evident. Epidemiological and experimental studies have linked inorganic arsenic exposure to the development of many diseases, including cognitive impairment, cardiovascular failure, cancer, etc. Several mechanisms have been proposed to explain the effects caused by arsenic, such as oxidative damage, DNA methylation, and protein misfolding. Understanding the toxicology and potential molecular mechanisms of arsenic can help mitigate its harmful effects. Therefore, this paper reviews the multiple organ toxicity of inorganic arsenic in animals, focusing on the various toxicity mechanisms of arsenic-induced diseases in animals. In addition, we have summarized several drugs that can have therapeutic effects on arsenic poisoning in pursuit of reducing the harm of arsenic contamination from different pathways.

First Report of Leaf Spot Caused by Clonostachys rosea on Tea (Camellia sinensis) in China.

Tea (Camellia sinensis), which originated in southwest of China 60 - 70 million years ago, is widely consumed as a beverage for its potential enhancing effect on human health with rich polyphenol content (Pan et al. 2022). From October to December in 2021, a disease with symptoms similar to leaf spot affected the quality and yield of tea Puer (102°73 'E, 25°07' N), Yunnan province, China. Based on the survey, leaf spot symptoms were observed on approximately 60% of tea plants in a 5,700 m2 field. The symptoms initially appeared as shrinking, yellowing, and later became circular or irregular brown spots. To isolate the pathogen, 10 symptomatic leaves were collected from 10 trees, and portions of the diseased tissue (0.5×0.5 cm) were cut at the junction of infected and healthy tissues. After surface sterilization (0.5 min with 75% ethanol and 2 min with 3% NaOCl, washed three times with sterilized distilled water), the disinfected pieces were dried and plated onto potato dextrose agar (PDA) and incubated at 25°C in the dark for 5 days. Four single-spore isolates, FH-1, FH-5, FH-6 and FH-7, were obtained, these isolates were identical in morphology and in the sequences of internal transcribed spacer region [ITS] and translation elongation factor 1-alpha [TEF] genes. Therefore, the representative isolate FH-5 was used for further study. Fungal colonies were white or light yellow on PDA after 7 days incubated at 28ºC. Conidia were hyaline, round or oval, aseptate, occur singly or in clusters on hyphae or conidia stalks, and measured as 2.94 ± 1.79 × 1.82 ± 0.2 µm (n = 50). Primary conidiophores is Verticillium-like (Fig1.K,L), which generally formed first, 1-3-level verticillate, mostly with divergent branches and phialides, and measured as 16.67 ± 4.39 µm (n = 50). Secondary conidiophores is penicillate (Fig1.I,J), which generally appearing after one week, sometimes even more often branched, and with a length of 16.02 ± 3.83 µm (n = 50). The morphological features were consistent with the descriptions of Clonostachys rosea Schroers H.J. (Schroers et al. 1999). The pathogen was confirmed to be C. rosea by amplification and sequencing of the internal transcribed spacer region (ITS) and translation elongation factor 1-alpha (TEF) genes using primers ITS1/ITS4 and EF1-728F/EF1-986R, respectively (Fu Rongtao 2019). The sequences of PCR products were deposited in GenBank with accession numbers ON332533 (ITS) and OP080234 (TEF). BLAST searches of the obtained sequences revealed 99.22% (510/514 nucleotides) and 98.37% (241/245 nucleotides) homology with those of C. rosea HQ-9-1 form GenBank (MZ433177 and MZ451399, respectively). Phylogenetic analysis (MEGA 7.0) using the maximum likelihood method placed the isolate FH-5 in a well-supported cluster with C. rosea. The pathogenicity of FH-5 was tested through a pot assay. Ten healthy tea plants were scratched with a sterilized needle on the leaves. Plants were inoculated by spraying a spore suspension (105 spores·mL-1) of FH-5 onto leaves until runoff, and the control leaves sprayed with sterile water. Inoculated plants were put in an artificial climate box at 25℃, 70% relative humidity. The pathogenicity test was replicated three times. Symptoms developed on all inoculated leaves but not on the control leaves. Lesions around the wound edge became pale yellow, and brown spots were first observed at 72 h after inoculation, and typical lesions similar to those observed on field plants appeared after two weeks. The same fungus was reisolated and identified based on the morphological characterization and molecular analyses (ITS and TEF) from the infected leaves but not from the noninoculated leaves. In addition, C. rosea has also been reported to cause diseases to broad bean (N. Afshari et al. 2017 ), garlic (Diaz et al. 2022), beet (Haque M.E et al. 2020) and other plants. To our knowledge, this is the first report of leaf spot on tea caused by C. rosea in China. This study provides valuable information for the identification and control of the leaf spot on tea.

The antibacterial mechanism of phenylacetic acid isolated from Bacillus megaterium L2 against Agrobacterium tumefaciens.

Background: Agrobacterium tumefaciens T-37 can infect grapes and other fruit trees and cause root cancer. Given the pollution and damage of chemical agents to the environment, the use of biological control has become an important area of focus. Bacillus megaterium L2 is a beneficial biocontrol strain isolated and identified in the laboratory, which has a good antibacterial effect on a variety of plant pathogens. The antibacterial metabolites of L2 were separated and purified to obtain a bioactive compound phenylacetic acid (PAA). Methods: The potential antibacterial mechanism of PAA against A. tumefaciens T-37 strain was determined by relative conductivity, leakage of nucleic acids, proteins, and soluble total sugars, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and reactive oxygen species (ROS). Results: PAA showed good antibacterial activity against strain A. tumefaciens T-37 with IC50 of 0.8038 mg/mL. Our data suggested that after treatment with PAA, the relative conductivity, nucleic acid, protein, and total soluble sugar of T-37 were increased significantly compared with the chloramphenicol treatment group and the negative treatment group. The total protein synthesis of T-37 cells was inhibited, the consumption of phosphorus decreased with the increase of incubation time, and the content of ROS was significantly higher than that in the negative treatment group. Meanwhile, the activity of two key enzymes (MDH and SDH) involved in the tricarboxylic acid cycle (TCA cycle) decreased. In addition, T-37 cells were found to be damaged by scanning electron microscopy observation. Our results showed that PAA can destroy cell membrane integrity, damage cell structures, affect cell metabolism, and inhibit protein synthesis to exert an antibacterial effect. Conclusions: We concluded that the mechanism of action of the PAA against strain T-37 might be described as PAA exerting antibacterial activity by affecting cell metabolism, inhibiting protein synthesis, and destroying cell membrane integrity and cell ultrastructure. Therefore, PAA has a promising application prospect in the prevention and treatment of root cancer disease caused by A. tumefaciens.

Plant Virome Analysis by the Deep Sequencing of Small RNAs of Fritillaria thunbergii var. chekiangensis and the Rapid Identification of Viruses.

Thunberg fritillary (Fritillaria thunbergii), a perennial used in traditional Chinese herbal medicine, is a members of the family Liliaceae. The degeneration of germplasm is a severe problem in the production of Fritillaria thunbergii var. chekiangensis. However, no information about viral infections of F. thunbergii var. chekiangensis has been reported. In this study, we sequenced the small RNAs of F. thunbergii var. chekiangensis from leaves and bulbs, and viruses were identified using a phylogenetic analysis and BLAST search for sequence. In addition, multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) was used to rapidly detect viruses in this variety. Our study first reported that five viruses infected F. thunbergii var. chekiangensis. Among them, fritillary virus Y (FVY), lily mottle virus (LMoV), Thunberg fritillary mosaic virus (TFMV), and hop yellow virus (HYV) had been reported in F. thunbergii, while apple stem grooving virus was first reported in the genus Fritillaria. A multiplex RT-PCR method was developed to rapidly test the four viruses FVY, LMoV, TFMV, and HYV in F. thunbergii var. chekiangensis. Our results provide a better understanding of the infection of F. thunbergii var. chekiangensis by viruses and a basic reference for the better design of suitable control measures.