RAD51 paralogs synergize with RAD51 to protect reversed forks from cellular nucleases.

Fork reversal is a conserved mechanism to prevent stalled replication forks from collapsing. Formation and protection of reversed forks are two crucial steps in ensuring fork integrity and stability. Five RAD51 paralogs, namely, RAD51B, RAD51C, RAD51D, XRCC2 and XRCC3, which share sequence and structural similarity to the recombinase RAD51, play poorly defined mechanistic roles in these processes. Here, using purified BCDX2 (RAD51BCD-XRCC2) and CX3 (RAD51C-XRCC3) complexes and in vitro reconstituted biochemical systems, we mechanistically dissect their functions in forming and protecting reversed forks. We show that both RAD51 paralog complexes lack fork reversal activities. Whereas CX3 exhibits modest fork protection activity, BCDX2 significantly synergizes with RAD51 to protect DNA against attack by the nucleases MRE11 and EXO1. DNA protection is contingent upon the ability of RAD51 to form a functional nucleoprotein filament on DNA. Collectively, our results provide evidence for a hitherto unknown function of RAD51 paralogs in synergizing with RAD51 nucleoprotein filament to prevent degradation of stressed replication forks.

PARP1 recruits DNA translocases to restrain DNA replication and facilitate DNA repair.

Replication fork reversal which restrains DNA replication progression is an important protective mechanism in response to replication stress. PARP1 is recruited to stalled forks to restrain DNA replication. However, PARP1 has no helicase activity, and the mechanism through which PARP1 participates in DNA replication restraint remains unclear. Here, we found novel protein-protein interactions between PARP1 and DNA translocases, including HLTF, SHPRH, ZRANB3, and SMARCAL1, with HLTF showing the strongest interaction among these DNA translocases. Although HLTF and SHPRH share structural and functional similarity, it remains unclear whether SHPRH contains DNA translocase activity. We further identified the ability of SHPRH to restrain DNA replication upon replication stress, indicating that SHPRH itself could be a DNA translocase or a helper to facilitate DNA translocation. Although hydroxyurea (HU) and MMS induce different types of replication stress, they both induce common DNA replication restraint mechanisms independent of intra-S phase activation. Our results suggest that the PARP1 facilitates DNA translocase recruitment to damaged forks, preventing fork collapse and facilitating DNA repair.

K33 only mutant ubiquitin augments bone marrow-derived dendritic cell-mediated CTL priming via PI3K-Akt pathway.

To explore the effect of K33 only mutant ubiquitin (K33O) on bone marrow-derived dendritic cells' (BMDCs') maturity, antigen uptake capability, surface molecule expressions and BMDC-mediated CTL priming, and further investigate the role of PI3K-Akt engaged in K33O-increased BMDC maturation, antigen uptake and presentation, surface molecule expressions and BMDC-based CTL priming. BMDCs were conferred K33O and other ubiquitin mutants (K33R, K48R, K63R-mutant ubiquitin) incubation or LY294002 and wortmannin pretreatment. PI3K-Akt phosphorylation, antigen uptake, antigenic presentation and CD86/MHC class I expression in BMDC were determined by western blot or flow cytometry. BMDC-based CTL proliferation and priming were determined by in vitro mixed lymphocyte reaction (MLR), ex vivo enzyme-linked immunospot assay (Elispot) and flow cytometry with intracellular staining, respectively. The treatment with K33O effectively augmented PI3K-Akt phosphorylation, BMDCs' antigen uptake, antigenic presentation, CD86/MHC class I and CD11c expressions. MLR, Elispot and flow cytometry revealed that K33O treatment obviously enhanced CTL proliferation, CTL priming and perforin/granzyme B expression. The pretreatment with PI3K-Akt inhibitors efficiently abrogated K33O's effects on BMDC. The replenishment of K33 only mutant ubiquitin augments BMDC-mediated CTL priming in bone marrow-derived dendritic cells via PI3K-Akt signalling.

Silver Surface-Assisted Dehydrobrominative Cross-Coupling between Identical Aryl Bromides.

Cross-coupling reactions represent an indispensable tool in chemical synthesis. An intriguing challenge in this field is to achieve selective cross-coupling between two precursors with similar reactivity or, to the limit, the identical molecules. Here we report an unexpected dehydrobrominative cross-coupling between 1,3,5-tris(2-bromophenyl)benzene molecules on silver surfaces. Using scanning tunneling microscopy, we examine the reaction process at the single-molecular level, quantify the selectivity of the dehydrobrominative cross-coupling, and reveal the modulation of selectivity by substrate lattice-related catalytic activity or molecular assembly effect. Theoretical calculations indicate that the dehydrobrominative cross-coupling proceeds via regioselective C-H bond activation of debrominated TBPB and subsequent highly selective C-C coupling of the radical-based intermediates. The reaction kinetics plays an important role in the selectivity for the cross-coupling. This work not only expands the toolbox for chemical synthesis but also provides important mechanistic insights into the selectivity of coupling reactions on the surface.

Origins of Severe Structural Changes during Alloying-Dealloying Reactions in Black Phosphorus.

Li-alloying reactions facilitate the incorporation of a large number of Li atoms into the crystalline structures of electrodes, such as black phosphorus (BP). However, the reactions inevitably induce multistep phase transitions characterized by drastic atomic rearrangements and lattice collapse. Despite many theoretical and experimental studies on alloying mechanisms, long-term debates persist regarding the structures of the intermediate phases, the accurate pathways of phase transitions, the formation of specific configurations, and alloying/dealloying reversibility. Here, through a combination of operando electron diffraction measurements and ab initio simulations at the atomic and electronic scales, we identify key factors that govern the severe structural changes during alloying-dealloying reactions in BP. P-P bonds of three-bond P atoms are continuously broken during lithiation, generating two-bond P atoms with a high ability to accept inserted electrons and Li ions. Consequently, the pristine layered structure in BP is transformed to P7 cages in Li3P7, which then evolve to chain configurations in LiP and finally to isolated P atoms in Li3P. Specifically, the preferential formation of the P7 cage results from its lowest binding energy with three Li ions compared to other cage isomers. Furthermore, only LiP can be reversibly transformed to the crystalline structure of Li3P7 during charge, but it is thermodynamically favorable for Li3P7 and Li3P intermediates to be delithiated to amorphous structures. Our findings offer unique insights into the alloying mechanisms and deepen the fundamental understanding of alloying anode systems.

Phase 2 study of pegylated liposomal doxorubicin plus cyclophosphamide, vincristine/vindesine, and prednisone in newly diagnosed PTCL: 8-year results.

BACKGROUND: Pegylated liposomal doxorubicin (PLD) is a liposome-encapsulated form of doxorubicin with equivalent efficacy and less cardiotoxicity. This phase 2 study evaluated the efficacy and safety of the PLD-containing CHOP regimen in newly diagnosed patients with aggressive peripheral T-cell lymphomas (PTCL). METHODS: Patients received PLD, cyclophosphamide, vincristine/vindesine, plus prednisone every 3 weeks for up to 6 cycles. The primary endpoint was the objective response rate at the end of treatment (EOT). RESULTS: From September 2015 to January 2017, 40 patients were treated. At the EOT, objective response was achieved by 82.5% of patients, with 62.5% complete response. As of the cutoff date (September 26, 2023), median progression-free survival (mPFS) and overall survival (mOS) were not reached (NR). The 2-year, 5-year, and 8-year PFS rates were 55.1%, 52.0%, and 52.0%. OS rate was 80.0% at 2 years, 62.5% at 5 years, and 54.3% at 8 years. Patients with progression of disease within 24 months (POD24) had worse prognosis than those without POD24, regarding mOS (41.2 months vs NR), 5-year OS (33.3% vs 94.4%), and 8-year OS (13.3% vs 94.4%). Common grade 3-4 adverse events were neutropenia (87.5%), leukopenia (80.0%), anemia (17.5%), and pneumonitis (17.5%). CONCLUSION: This combination had long-term benefits and manageable tolerability, particularly with less cardiotoxicity, for aggressive PTCL, which might provide a favorable benefit-risk balance. CLINICALTRIALS.GOV IDENTIFIER: Chinese Clinical Trial Registry, ChiCTR2100054588; IRB Approved: Ethics committee of Fudan University Shanghai Cancer Center (Date 2015.8.31/No. 1508151-13.

Development of a Methodology Based on Optical Interferometry for Measuring Fibrinolytic Activity.

Fibrinolytic activity assay is particularly important for the detection, diagnosis, and treatment of cardiovascular disease and the development of fibrinolytic drugs. A novel efficacious strategy for real-time and label-free dynamic detection of fibrinolytic activity based on ordered porous layer interferometry (OPLI) was developed. Fibrin or a mixture of fibrin and plasminogen (Plg) was loaded into the highly ordered silica colloidal crystal (SCC) film scaffold to construct a fibrinolytic response interference layer to measure fibrinolytic activity with different mechanisms of action. Fibrinolytic enzyme-triggered fibrinolysis led to the migration of interference fringes in the interferogram, which could be represented by optical thickness changes (ΔOT) tracked in real time by the OPLI system. The morphology and optical property of the fibrinolytic response interference layer were characterized, and the Plg content in the fibrinolytic response interference layer and experimental parameters of the system were optimized. The method showed adequate sensitivity for the fibrinolytic activity of lumbrokinase and streptokinase, with wide linear ranges of 12-6000 and 10-2000 U/mL, respectively. Compared with the traditional fibrin plate method, it has a lower detection limit and higher linearity. The whole kinetic process of fibrinolysis by these two fibrinolytic drug models was recorded in real time, and the Michaelis constant and apparent kinetic parameters were calculated. Importantly, some other blood proteins were less interfering with this system, and it showed reliability in fibrin activity detection in real whole blood samples. This study established a better and more targeted research method of in vitro fibrinolysis and provided dynamic monitoring data for the analysis of fibrinolytic activity of whole blood.

Metabolic Basis of Pathogenesis and Host Adaptation in Rice Blast.

The blast disease, caused by the ascomycete Magnaporthe oryzae, poses a great threat to rice production worldwide. Increasing use of fungicides and/or blast-resistant varieties of rice (Oryza sativa) has proved to be ineffective in long-term control of blast disease under field conditions. To develop effective and durable resistance to blast, it is important to understand the cellular mechanisms underlying pathogenic development in M. oryzae. In this review, we summarize the latest research in phototropism, autophagy, nutrient and redox signaling, and intrinsic phytohormone mimics in M. oryzae for cellular and metabolic adaptation(s) during its interactions with the host plants.

A latent profile analysis of resilience and their relation to differences in sleep quality in patients with lung cancer.

PURPOSE: Sleep problems are a significant issue in patients with lung cancer, and resilience is a closely related factor. However, few studies have identified subgroups of resilience and their relationship with sleep quality. This study aimed to investigate whether there are different profiles of resilience in patients with lung cancer, to determine the sociodemographic characteristics of each subgroup, and to determine the relationship between resilience and sleep quality in different subgroups. METHODS: A total of 303 patients with lung cancer from four tertiary hospitals in China completed the General Sociodemographic sheet, the Connor-Davidson Resilience Scale, and the Pittsburgh Sleep Quality Index. Latent profile analysis was applied to explore the latent profiles of resilience. Multivariate logistic regression was used to analyze the sociodemographic variables in each profile, and ANOVA was used to explore the relationships between resilience profiles and sleep quality. RESULTS: The following three latent profiles were identified: the "high-resilience group" (30.2%), the "moderate-resilience group" (46.0%), and the "low-resilience group" (23.8%). Gender, place of residence, and average monthly household income significantly influenced the distribution of resilience in patients with lung cancer. CONCLUSION: The resilience patterns of patients with lung cancer varied. It is suggested that health care providers screen out various types of patients with multiple levels of resilience and pay more attention to female, rural, and poor patients. Additionally, individual differences in resilience may provide an actionable means for addressing sleep problems.

Plastome Evolution, Phylogenomics, and DNA Barcoding Investigation of Gastrochilus (Aeridinae, Orchidaceae), with a Focus on the Systematic Position of Haraella retrocalla.

Gastrochilus is an orchid genus containing about 70 species in tropical and subtropical Asia with high morphological diversity. The phylogenetic relationships among this genus have not been fully resolved, and the plastome evolution has not been investigated either. In this study, five plastomes of Gastrochilus were newly reported, and sixteen plastomes of Gastrochilus were used to conduct comparative and phylogenetic analyses. Our results showed that the Gastrochilus plastomes ranged from 146,183 to 148,666 bp, with a GC content of 36.7-36.9%. There were 120 genes annotated, consisting of 74 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. No contraction and expansion of IR borders, gene rearrangements, or inversions were detected. Additionally, the repeat sequences and codon usage bias of Gastrochilus plastomes were highly conserved. Twenty hypervariable regions were selected as potential DNA barcodes. The phylogenetic relationships within Gastrochilus were well resolved based on the whole plastome, especially among main clades. Furthermore, both molecular and morphological data strongly supported Haraella retrocalla as a member of Gastrochilus (G. retrocallus).

Measuring the quality of transitional care based on elderly patients' experiences with the partners at care transitions measure: a cross-sectional survey.

BACKGROUND: The quality of transitional care is closely related to the health outcomes of patients, and understanding the status of transitional care for patients is crucial to improving the health outcomes of patients. Therefore, this study aims to investigate the quality of transitional care in elderly patients with chronic diseases and analyze its influencing factors, to provide a basis for improving transitional care services. METHODS: This is a cross-sectional study. We used the Chinese version of the Partners at Care Transitions Measure (PACT-M) to survey patients with chronic diseases aged 60 years and older who were about to be discharged from five tertiary hospitals in Henan and Shanxi provinces. We used the mean ± standard deviation to describe the quality of transitional care, t-test or one-way ANOVA, and regression analysis to explore the factors affecting the quality of transitional care for patients. RESULTS: 182 elderly patients with chronic diseases aged ≥ 60 years completed the PACT-M survey. The scores of PACT-M1 and PACT-M2 were (30.69 ± 7.87) and (25.59 ± 7.14) points, respectively. The results of the t-test or one-way ANOVA showed that the patient's marital status, ethnicity, religion, educational level, preretirement occupation, residence, household income per month, and living situation had an impact on the quality of transitional care for elderly patients with chronic diseases (P < 0.05). The results of regression analyses showed that patients' preretirement occupation, social support, and health status were the main influences on the quality of transitional care for elderly patients with chronic diseases (P < 0.05), and they explained 63.1% of the total variance. CONCLUSIONS: The quality of transitional care for older patients with chronic illnesses during the transition from hospital to home needs further improvement. Factors affecting the quality of transitional care included patients' pre-retirement occupation, social support, and health status. We can improve the hospital-community-family tertiary linkage service to provide coordinated and continuous transitional care for patients based on their occupation, health status, and social support to enhance the quality of transitional care and the patient's health.

Use of a mobile application to monitor drain sites and surgical wounds after discharge from acute care - A feasibility study in Singapore.

PURPOSE: This study aimed to demonstrate the compliance, feasibility, and acceptability of telehealth monitoring among surgical patients discharged with wounds or drains. METHODOLOGY: This is a cross-sectional feasibility study. Post-surgical breast, plastic, and hepatobiliary patients with wounds and/or surgical drains were recruited using convenience sampling. The control group received conventional care which consisted of daily telephone follow-up. The intervention group used a mobile wound application to take wound and drain images, report drainage amount and symptoms. Compliance was assessed by measuring the percentage of actual to expected patient entries, feasibility was assessed by comparing detection of abnormalities and unexpected hospital visits, and acceptability was assessed by subjective feedback from nurses and patients from the intervention group. RESULTS: 59 patients were recruited, with 30 patients in the control group and 29 patients in the intervention group. 9 specialty nurses were involved in the patients' post-discharge care. The mean compliance rate for the hepatobiliary, breast and plastic patients were 89.9 %, 89.5 % and 75.9 % respectively. 4 patients from the intervention group (13.8 %) and 6 patients from the control group (20.1 %) were flagged as having potential abnormalities. As for unexpected hospital visits, there were 2 (6.9 %) in the intervention group and 1 (3.4 %) in the control group. 25 patients and 9 specialty nurses responded to the feedback survey. 22 patients (88 %) did not face any application issues. 18 patients (72 %) preferred to self-report symptoms via the application rather than to call the nurses and reported feeling safe knowing that they are remotely monitored. Most nurses found the app convenient and timesaving (n = 7, 78 %), with monitoring through pictures as more accurate than phone conversation (n = 8, 89 %). CONCLUSION: The results suggest that use of a mobile application by surgical patients discharged with wounds or drains is feasible and serves as a viable monitoring tool.

Correlation Between the Expression of DNA Damage Repair Protein OGG1 and Ubiquitination Pathway Protein STUB1 in Pediatric Neuroblastoma.

BACKGROUND: Neuroblastoma, a pediatric malignancy, is significantly influenced by genetic factors. Prior research indicates that the OGG1 rs1052133 G > C polymorphism correlates with a decreased risk of neuroblastoma. METHODS: We analyzed 57 neuroblastoma and 21 adrenal samples, using immunohistochemistry to measure OGG1 and STUB1 expression levels. We conducted a survival analysis to explore relationship between the expressions and neuroblastoma prognosis. RESULTS: Notably higher OGG1 expression and significantly lower STUB1 expression in neuroblastoma. OGG1 levels were significantly correlated with patient age, tumor location, histological grade, Shimada classification, INSS stage, and risk category. A negative association was observed between OGG1 and STUB1 expressions. Higher OGG1 expression was linked to reduced PFS and OS. Lower STUB1 expression was associated with unfavorable PFS. Additionally, OGG1 expression and risk category emerged as independent predictors of prognosis. CONCLUSION: OGG1 potentially functions as an oncogene in NB, with its activity possibly modulated by STUB1 through the ubiquitination pathway.

[Expressions of zinc homeostasis proteins, GPR39 and ANO1 mRNA in the sperm of asthenozoospermia patients and their clinical significance].

OBJECTIVE: To explore the expressions of zinc homeostasis-related proteins, G protein-coupled receptor 39 (GPR39) and ANO1 mRNA in the sperm of patients with asthenozoospermia (AS), and analyze their correlation with sperm motility. METHODS: We collected semen samples from 82 male subjects with PR+NP < 40%, PR < 32% and sperm concentration > 15×106/ml (the AS group, n = 40) or PR+NP ≥ 40%, PR ≥ 32% and sperm concentration > 15×106/ml (the normal control group, n = 42). We analyzed the routine semen parameters and measured the zinc content in the seminal plasma using the computer-assisted sperm analysis system, detected the expressions of zinc transporters (ZIP13, ZIP8 and ZNT10), metallothioneins (MT1G, MT1 and MTF), GPR39, and calcium-dependent chloride channel protein (ANO1) in the sperm by real-time quantitative PCR (RT qPCR), examined free zinc distribution in the sperm by laser confocal microscopy, and determined the expressions of GPR39 and MT1 proteins in the sperm by immunofluorescence staining, followed by Spearman rank correlation analysis of their correlation with semen parameters. RESULTS: There was no statistically significant difference in the zinc concentration in the seminal plasma between the AS and normal control groups (P>0.05). Compared with the controls, the AS patients showed a significantly reduced free zinc level (P<0.05), relative expressions of MT1G, MTF, ZIP13, GPR39 and ANO1 mRNA (P<0.05), and that of the GPR39 protein in the AS group (P<0.05). No statistically significant differences were observed in the relative expression levels of ZIP8, ZNT10 and MT1 mRNA between the two groups (P>0.05). The relative expression levels of GPR39, ANO1, MT1G and MTF mRNA were positively correlated with sperm motility and the percentage of progressively motile sperm (P<0.05). CONCLUSION: The expressions of zinc homeostasis proteins (MT1G, MTF and ZIP13), GPR39 and ANO1 mRNA are downregulated in the sperm of asthenozoospermia patients, and positively correlated with sperm motility.

Molecular Evidence for the Axial Coordination Effect of Atomic Iodine on Fe-N4 Sites in Oxygen Reduction Reaction.

We present a molecular-scale investigation of the axial coordination effect of atomic iodine on Fe-N4 sites in the oxygen reduction reaction (ORR) by electrochemical scanning tunneling microscopy (ECSTM). A well-defined model catalytic system with explicit and uniform iodine-coordinated Fe-N4 sites was constructed facilely by the self-assembly of iron(II) phthalocyanine (FePc) on an I-modified Au(111) surface. The electrocatalytic activity of FePc for the ORR shows a tremendous enhancement with axial iodine ligands. The ingenious modulation of the electronic structure of Fe sites to evoke a higher spin configuration by axial iodine was evidenced. In addition, the interaction strength between reactive oxygen species and active centers becomes weaker due to the presence of iodine ligands, and the reaction is thermodynamically preferable. Moreover, the facilitated reaction dynamics of FePc on I/Au(111) were explicitly determined via in-situ ECSTM potential pulse experiments. Noteworthily, axial atomic iodine was found inefficacious for improving the activity of Co-N4 sites, and electron rearrangement was not detected, demonstrating that adequate interactions between axial ligands and metal sites for optimizing electronic structures and catalytic behaviors are prerequisites for the impactful role of axial ligands.

Characterization and Engineering of Two Highly Paralogous Sesquiterpene Synthases Reveal a Regioselective Reprotonation Switch.

Sesquiterpene synthases (STPSs) catalyze carbocation-driven cyclization reactions that can generate structurally diverse hydrocarbons. The deprotonation-reprotonation process is widely used in STPSs to promote structural diversity, largely attributable to the distinct regio/stereoselective reprotonations. However, the molecular basis for reprotonation regioselectivity remains largely understudied. Herein, we analyzed two highly paralogous STPSs, Artabotrys hexapetalus (-)-cyperene synthase (AhCS) and ishwarane synthase (AhIS), which catalyze reactions that are distinct from the regioselective protonation of germacrene A (GA), resulting in distinct skeletons of 5/5/6 tricyclic (-)-cyperene and 6/6/5/3 tetracyclic ishwarane, respectively. Isotopic labeling experiments demonstrated that these protonations occur at C3 and C6 of GA in AhCS and AhIS, respectively. The cryo-electron microscopy-derived AhCS complex structure provided the structural basis for identifying different key active site residues that may govern their functional disparity. The structure-guided mutagenesis of these residues resulted in successful functional interconversion between AhCS and AhIS, thus targeting the three active site residues [L311-S419-C458]/[M311-V419-A458] that may act as a C3/C6 reprotonation switch for GA. These findings facilitate the rational design or directed evolution of STPSs with structurally diverse skeletons.

Tafenoquine and its derivatives as inhibitors for the severe acute respiratory syndrome coronavirus 2.

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has severely affected human lives around the world as well as the global economy. Therefore, effective treatments against COVID-19 are urgently needed. Here, we screened a library containing Food and Drug Administration (FDA)-approved compounds to identify drugs that could target the SARS-CoV-2 main protease (Mpro), which is indispensable for viral protein maturation and regard as an important therapeutic target. We identified antimalarial drug tafenoquine (TFQ), which is approved for radical cure of Plasmodium vivax and malaria prophylaxis, as a top candidate to inhibit Mpro protease activity. The crystal structure of SARS-CoV-2 Mpro in complex with TFQ revealed that TFQ noncovalently bound to and reshaped the substrate-binding pocket of Mpro by altering the loop region (residues 139-144) near the catalytic Cys145, which could block the catalysis of its peptide substrates. We also found that TFQ inhibited human transmembrane protease serine 2 (TMPRSS2). Furthermore, one TFQ derivative, compound 7, showed a better therapeutic index than TFQ on TMPRSS2 and may therefore inhibit the infectibility of SARS-CoV-2, including that of several mutant variants. These results suggest new potential strategies to block infection of SARS-CoV-2 and rising variants.

Inhibition of endogenous hydrogen sulfide production suppresses the growth of nasopharyngeal carcinoma cells.

Hydrogen sulfide (H2 S) has been widely recognized as one of gasotransmitters. Endogenous H2 S plays a crucial role in the progression of cancer. However, the effect of endogenous H2 S on the development of nasopharyngeal carcinoma (NPC) is still unknown. In this study, aminooxyacetic acid (AOAA, an inhibitor of cystathionine-ß-synthase), dl-propargylglycine (PAG, an inhibitor of cystathionine-γ-lyase), and l-aspartic acid (l-Asp, an inhibitor of 3-mercaptopyruvate sulfurtransferase) were adopted to detect the role of endogenous H2 S in NPC growth. The results indicated that the combine (PAG + AOAA + l-Asp) group had higher inhibitory effect on the growth of NPC cells than the PAG, AOAA, and l-Asp groups. There were similar trends in the levels of apoptosis and reactive oxygen species (ROS). In addition, the combine group exhibited lower levels of phospho (p)-extracellular signal-regulated protein kinase but higher expressions of p-p38 and p-c-Jun N-terminal kinase than those in the AOAA, PAG, and l-Asp groups. Furthermore, the combine group exerted more potent inhibitory effect on NPC xenograft tumor growth without obvious toxicity. In summary, suppression of endogenous H2 S generation could dramatically inhibit NPC growth via the ROS/mitogen-activated protein kinase pathway. Endogenous H2 S may be a novel therapeutic target in human NPC cells. Effective inhibitors for H2 S-producing enzymes could be designed and developed for NPC treatment.

Engineered Sucrose Metabolism Improves the Smut Disease Suppression Potency of Pseudomonas sp. ST4.

Sporisorium scitamineum and Ustilago maydis are two fungal pathogens causing severe sugarcane and maize diseases, respectively. Sexual mating of compatible sporidia is essential for these pathogens to form infections dikaryotic mycelia and cause smut diseases. We showed recently that in the presence of exogenous glucose, the Pseudomonas sp. strain ST4 could block the fungal mating and display a strong disease suppression potency on S. scitamineum. With the aim of conferring strain ST4 the ability to metabolize sucrose in plants for glucose production, we identified a strong native promoter pSsrA in strain ST4 and additional promoter elements to facilitate translation and peptide translocation for the construction of a fusion gene encoding sucrose metabolism. The cscA gene encoding sucrose hydrolase from Pseudomonas protegens Pf-5 was fused to the promoter pSsrA, a translational coupler bicistronic design and a Tat signal peptide, which was then cloned into mini-Tn7 transposon. This synthetic gene cassette was integrated into the chromosome of strain ST4, and the resultant engineered strain ST4E was able to hydrolyze sucrose with high efficiency and displayed elevated inhibitory activity on the mating and virulence of S. scitamineum and U. maydis. The findings from this study provide a valuable device and useful clues for the engineering of sucrose metabolism in non- or weak-sucrose-utilizing bacterial strains and present an improved biocontrol agent against plant smut pathogens. IMPORTANCE Sporisorium scitamineum and Ustilago maydis are typical dimorphic fungi causing severe sugarcane and maize smut diseases, respectively. Sexual mating of compatible sporidia is essential for these pathogens to form infections dikaryotic mycelia and cause smut diseases. We previously demonstrated that the biocontrol strain Pseudomonas sp. ST4 could block the fungal mating and displays a strong suppression potency on smut diseases, while it was unable to utilize the host-sourced sucrose for glucose production critical for antifungus efficiency. In this study, we constructed a high-expression gene cassette for minitransposon-mediated genome integration and sucrose hydrolysis in the bacterial periplasmic space. The resultant engineered strain ST4E was able to hydrolyze sucrose and inhibit the mating and hyphal growth of S. scitamineum and U. maydis. These findings provide a valuable tool and useful clues for the engineering of sucrose metabolism in non- or weak-sucrose-utilizing bacterial strains and present an improved biocontrol agent against plant smut pathogens.

Species richness disparity in tropical terrestrial herbaceous floras: Evolutionary insight from Collabieae (Orchidaceae).

Species richness is spatially heterogeneous even in the hyperdiverse tropical floras. The main cause of uneven species richness among the four tropical regions are hot debated. To date, higher net diversification rates and/or longer colonization time have been usually proposed to contribute to this pattern. However, there are few studies to clarify the species richness patterns in tropical terrestrial floras. The terrestrial tribe Collabieae (Orchidaceae) unevenly distributes in the tropical regions with a diverse and endemic center in Asia. Twenty-one genera 127 species of Collabieae and 26 DNA regions were used to reconstruct the phylogeny and infer the biogeographical processes. We compared the topologies, diversification rates and niche evolutionary rates of Collabieae and regional lineages on empirical samplings and different simulated samplings fractions respectively. Our results suggested that the Collabieae originated in Asia at the earliest Oligocene, and then independently spread to Africa, Central America, and Oceania since the Miocene via long-distance dispersal. These results based on empirical data and simulated data were similar. BAMM, GeoSSE and niche analyses inferred that the Asian lineages had higher net diversification and niche evolutionary rates than those of Oceanian and African lineages on the empirical and simulated analyses. Precipitation is the most important factor for Collabieae, and the Asian lineage has experienced more stable and humid climate, which may promote the higher net diversification rate. Besides, the longer colonization time may also be associated with the Asian lineages' diversity. These findings provided a better understanding of the regional diversity heterogeneity in tropical terrestrial herbaceous floras.