Global regulation of promoter melting in naive lymphocytes.

Lymphocyte activation is initiated by a global increase in messenger RNA synthesis. However, the mechanisms driving transcriptome amplification during the immune response are unknown. By monitoring single-stranded DNA genome wide, we show that the genome of naive cells is poised for rapid activation. In G0, ∼90% of promoters from genes to be expressed in cycling lymphocytes are polymerase loaded but unmelted and support only basal transcription. Furthermore, the transition from abortive to productive elongation is kinetically limiting, causing polymerases to accumulate nearer to transcription start sites. Resting lymphocytes also limit the expression of the transcription factor IIH complex, including XPB and XPD helicases involved in promoter melting and open complex extension. To date, two rate-limiting steps have been shown to control global gene expression in eukaryotes: preinitiation complex assembly and polymerase pausing. Our studies identify promoter melting as a third key regulatory step and propose that this mechanism ensures a prompt lymphocyte response to invading pathogens.

Enzyme-catalysed [6+4] cycloadditions in the biosynthesis of natural products.

Pericyclic reactions are powerful transformations for the construction of carbon-carbon and carbon-heteroatom bonds in organic synthesis. Their role in biosynthesis is increasingly apparent, and mechanisms by which pericyclases can catalyse reactions are of major interest1. [4+2] cycloadditions (Diels-Alder reactions) have been widely used in organic synthesis2 for the formation of six-membered rings and are now well-established in biosynthesis3-6. [6+4] and other 'higher-order' cycloadditions were predicted7 in 1965, and are now increasingly common in the laboratory despite challenges arising from the generation of a highly strained ten-membered ring system8,9. However, although enzyme-catalysed [6+4] cycloadditions have been proposed10-12, they have not been proven to occur. Here we demonstrate a group of enzymes that catalyse a pericyclic [6+4] cycloaddition, which is a crucial step in the biosynthesis of streptoseomycin-type natural products. This type of pericyclase catalyses [6+4] and [4+2] cycloadditions through a single ambimodal transition state, which is consistent with previous proposals11,12. The [6+4] product is transformed to a less stable [4+2] adduct via a facile Cope rearrangement, and the [4+2] adduct is converted into the natural product enzymatically. Crystal structures of three pericyclases, computational simulations of potential energies and molecular dynamics, and site-directed mutagenesis establish the mechanism of this transformation. This work shows how enzymes are able to catalyse concerted pericyclic reactions involving ambimodal transition states.

Secretory breast carcinoma: clinicopathological features and prognosis of 52 patients.

PURPOSE: Secretory breast carcinoma is a rare histological subtype of invasive breast cancer and considered with an indolent clinical behavior. This study was conducted to analyze the clinicopathological features of patients with secretory breast carcinoma (SBC), explore the outcome, and compare the prognostic difference with invasive ductal breast carcinoma (IDC). METHODS AND MATERIALS: Patients with SBC diagnosed between 2006 and 2017 from Fudan University Shanghai Cancer Center were included in the study, excluding patients with previous malignant tumor history and incomplete clinical data or follow-up records. Peculiar clinicopathological and immunohistochemical features of the cases were fully described. Clinical data of 4979 cases of IDC were also evaluated during this period. After propensity score matching, prognostic analysis of SBCs and IDCs was calculated by Kaplan-Meier method and landmark analysis method. RESULTS: The data of 52 patients diagnosed with SBC were identified from the pathological files. Among them, 47 patients were women, and 5 were men. The median age of the 52 SBCs was 46 years (mean, 48.1 years; range, 10-80 years). The tumor sizes ranged from 0.3 to 6.8 cm, with a mean of 3.5 cm. Eight patients (15.4%) had positive axillary lymph node involvement. The molecular classification was mostly triple-negative breast cancer (65.4%). Fluorescence in situ hybridization confirmed the presence of ETV6::NTRK3 rearrangement in 16 of 18 cases (88.9%). Furthermore, Kaplan-Meier survival analysis and landmark analysis demonstrated that there were no statistically significant differences in DFS and OS between SBC and IDC patients. CONCLUSION: Although SBCs are generally associated with a favorable prognosis, our work exhibited that the clinicopathological features of SBC were partly different from former understandings, indicating that therapeutic procedure should be prudent. Further studies are necessary to fully identify the clinical behavior and predictive markers to improve diagnosis and management in this unique subtype of breast cancer.

Interleukin-6 trans-signaling regulates monocyte chemoattractant protein-1 production in immune-mediated necrotizing myopathy.

OBJECTIVE: Immune-mediated necrotizing myopathy (IMNM) is pathologically characterized by diffuse myofiber necrosis and regeneration, myophagocytosis, and a sparse inflammatory infiltrate. The monocyte chemoattractant protein-1 (MCP-1) is a key chemokine that regulates monocyte/macrophage infiltration into injured tissues. The interleukin-6 (IL-6) signalling in the induction of MCP-1 expression has not been investigated in IMNM. METHODS: MCP-1 expression in muscle specimens was assessed using immunohistochemistry and real-time quantitative polymerase chain reaction (RT-qPCR). Levels of multiple serological cytokines were evaluated using the Meso Scale Discovery electrochemiluminescence system. Flow cytometry, RT-qPCR, enzyme-linked immunosorbent assay, western blot, dual-luciferase reporter assays, and chromatin immunoprecipitation-qPCR were performed to explore the effects of IL-6 signalling on MCP-1 production in human myoblasts. RESULTS: MCP-1 was scattered and was positively expressed within myofibers and a few inflammatory cells in the muscles of patients with IMNM. Sarcoplasmic MCP-1 expression significantly correlated with myonecrosis, myoregeneration, and inflammatory infiltration. Serum MCP-1, IL-6, and the soluble form of the IL-6 receptor (sIL-6R) were elevated in patients with IMNM compared with controls. Serological MCP-1 levels were significantly associated with serum IL-6 expression and clinical disease severity in IMNM patients. The IL-6/sIL-6R complex induced MCP-1 expression via the signal transducer and activator of transcription 3 (STAT3) pathway in human myoblasts. Mechanistically, phospho-STAT3 was enriched in the MCP-1 promoter region and promoted the transcription. CONCLUSION: IL-6 trans-signalling may contribute to the immunopathogenesis of IMNM by augmenting inflammation through regulation of MCP-1 expression in IMNM.

Toll-interacting protein is activated by the transcription factor GATA1 and Sp1 to negatively regulate NF-κB and MAPK pathways in the Japanese eel (Anguilla japonica).

Toll-interacting protein (Tollip) serves as a crucial inhibitory factor in the modulation of Toll-like receptor (TLR)-mediated innate immunological responses. The structure and function of Tollip have been well documented in mammals, yet the information in teleost remained limited. This work employed in vitro overexpression and RNA interference in vivo and in vitro to comprehensively examine the regulatory effects of AjTollip on NF-κB and MAPK signaling pathways. The levels of p65, c-Fos, c-Jun, IL-1, IL-6, and TNF-α were dramatically reduced following overexpression of AjTollip, whereas knocking down AjTollip in vivo and in vitro enhanced those genes' expression. Protein molecular docking simulations showed AjTollip interacts with AjTLR2, AjIRAK4a, and AjIRAK4b. A better understanding of the transcriptional regulation of AjTollip is crucial to elucidating the role of Tollip in fish antibacterial response. Herein, we cloned and characterized a 2.2 kb AjTollip gene promoter sequence. The transcription factors GATA1 and Sp1 were determined to be associated with the activation of AjTollip expression by using promoter truncation and targeted mutagenesis techniques. Collectively, our results indicate that AjTollip suppresses the NF-κB and MAPK signaling pathways, leading to the decreased expression of the downstream inflammatory factors, and GATA1 and Sp1 play a vital role in regulating AjTollip expression.

Soluble Oligomers of PolyQ-Expanded Huntingtin Target a Multiplicity of Key Cellular Factors.

Huntington's disease is one of several neurodegenerative disorders characterized by the aggregation of polyglutamine (polyQ)-expanded mutant protein. How polyQ aggregation leads to cellular dysfunction is not well understood. Here, we analyzed aberrant protein interactions of soluble oligomers and insoluble inclusions of mutant huntingtin using in-cell single molecule fluorescence spectroscopy and quantitative proteomics. We find that the interactome of soluble oligomers is highly complex, with an enrichment of RNA-binding proteins as well as proteins functioning in ribosome biogenesis, translation, transcription, and vesicle transport. The oligomers frequently target proteins containing extended low-complexity sequences, potentially interfering with key cellular pathways. In contrast, the insoluble inclusions are less interactive and associate strongly with protein quality control components, such as Hsp40 chaperones and factors of the ubiquitin-proteasome system. Our results suggest a "multiple hit" model for the pathogenic effects of mutant huntingtin, with soluble forms engaging more extensively in detrimental interactions than insoluble aggregates.

Factors affecting the compliance of hepatocellular carcinoma screening among high-risk populations: A systematic review and meta-analysis.

BACKGROUND: Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide and the third leading cause of cancer mortality. HCC has high morbidity, high mortality, and low survival rates. Screening is one of the most significant methods of lowering incidence and death while also increasing survival. OBJECTIVES: The aim of this study was to identify the facilitators and barriers to participation in HCC screening among high-risk populations. METHODS: A comprehensive and systematic search was undertaken in PubMed, Web of Science, MEDLINE, EMBACE, EBSCOhost and the Cochrane Library. A combination of synonyms of the keywords including HCC, screening, factors and adherence were used for searching. Studies addressing the facilitators and barriers to HCC screening compliance in at-risk individuals were included. Data were synthesized using Review Manager version 5.4. A random/fixed effects model meta-analysis was performed to estimate the pooled data and expressed with odds ratio (OR) and 95% confidence interval (CI). RESULTS: A total of seven articles met the inclusion criteria. Qualitative (n = 1) and quantitative (n = 6) studies using various types of surgery were conducted. The most commonly mentioned barriers were insufficient knowledge and awareness of HCC screening, unawareness of the necessity for early detection of HCC and lack of physician recommendation. A meta-analysis of seven studies showed that individuals with a family history of HCC increased screening uptake by nearly three times (OR: 2.69, 95% CI: 1.93, 3.75). Other most frequently reported facilitators include age, education level, and perceived risk et al. CONCLUSIONS: Many barriers to HCC screening were found. Meanwhile, this review points out that improving the awareness of high-risk populations toward HCC screening is expected to enhance compliance, thereby promoting early diagnosis of liver cancer, reducing mortality, and alleviating the burden of HCC.

Health characteristics and factors associated with transition shock in newly graduated registered nurses: a latent class analysis.

BACKGROUND: Transition shock occurs at a vulnerable time in newly graduated registered nurses' careers and has a clear impact on both newly graduated registered nurses' productivity and patient recovery outcomes. Identifying classification features of transition shock and targeting interventions to support newly graduated registered nurses is imperative. The study aimed to explore potential transition shock subgroups of newly graduated registered nurses and further explore the impact of population characteristics and two indices of health on transition shock. METHODS: A descriptive, cross-sectional design was conducted. An online questionnaire was sent via WeChat to newly graduated registered nurses who started work in 2021 at seven hospitals between August and November 2021, and 331 nurses filled out the questionnaire. Latent class analysis was used to identify the potential class of the transition shock of newly graduated registered nurses, and multinomial logistic regression analyses were used to determine the factors of potential classification. RESULTS: The study identified four classes of transition shock in newly graduated registered nurses, namely, "high transition shock", "physical fatigue-lack of knowledge", "development adaptation" and "low transition shock-worry" groups. Newly graduated registered nurses who urinated less than 4 times per day (OR = 0.051, 95% CI = 0.005-0.502) were likely to be in the "high transition shock" group. Newly graduated registered nurses who did not delay urination (OR = 4.267, 95% CI = 1.162-11.236) were more likely to belong to the "low transition shock-worry" group. Newly graduated registered nurses without sleep disturbance were more likely to be in the "physical fatigue - lack of knowledge" (OR = 3.109, 95% CI = 1.283-7.532), "development adaptation" (OR = 8.183, 95% CI = 2.447-27.066), and "low transition shock-worry" (OR = 8.749, 95% CI = 1.619-47.288) groups than in the 'high transition shock' group. CONCLUSIONS: This study highlights potential patterns of transition shock among newly graduated registered nurses. Two indices of health, namely, delayed urination and sleep disturbance, can predict the subgroups of newly graduated registered nurses with transition shock.

P450-Modified Multicyclic Cyclophane-Containing Ribosomally Synthesized and Post-Translationally Modified Peptides.

Cyclic peptides with cyclophane linkers are an attractive compound type owing to the fine-tuned rigid three-dimensional structures and unusual biophysical features. Cytochrome P450 enzymes are capable of catalyzing not only the C-C and C-O oxidative coupling reactions found in vancomycin and other nonribosomal peptides (NRPs), but they also exhibit novel catalytic activities to generate cyclic ribosomally synthesized and post-translationally modified peptides (RiPPs) through cyclophane linkage. To discover more P450-modified multicyclic RiPPs, we set out to find cryptic and unknown P450-modified RiPP biosynthetic gene clusters (BGCs) through genome mining. Synergized bioinformatic analysis reveals that P450-modified RiPP BGCs are broadly distributed in bacteria and can be classified into 11 classes. Focusing on two classes of P450-modified RiPP BGCs where precursor peptides contain multiple conserved aromatic amino acid residues, we characterized 11 novel P450-modified multicyclic RiPPs with different cyclophane linkers through heterologous expression. Further mutation of the key ring-forming residues and combinatorial biosynthesis study revealed the order of bond formation and the specificity of P450s. This study reveals the functional diversity of P450 enzymes involved in the cyclophane-containing RiPPs and indicates that P450 enzymes are promising tools for rapidly obtaining structurally diverse cyclic peptide derivatives.

P450-Modified Ribosomally Synthesized Peptides with Aromatic Cross-Links.

Cyclization of linear peptides is an effective strategy to convert flexible molecules into rigid compounds, which is of great significance for enhancing the peptide stability and bioactivity. Despite significant advances in the past few decades, Nature and chemists' ability to macrocyclize linear peptides is still quite limited. P450 enzymes have been reported to catalyze macrocyclization of peptides through cross-linkers between aromatic amino acids with only three examples. Herein, we developed an efficient workflow for the identification of P450-modified RiPPs in bacterial genomes, resulting in the discovery of a large number of P450-modified RiPP gene clusters. Combined with subsequent expression and structural characterization of the products, we have identified 11 novel P450-modified RiPPs with different cross-linking patterns from four distinct classes. Our results greatly expand the structural diversity of P450-modified RiPPs and provide new insights and enzymatic tools for the production of cyclic peptides.

Hypoxia-induced AFAP1L1 regulates pathological neovascularization via the YAP-DLL4-NOTCH axis.

BACKGROUND: Pathological neovascularization plays a pivotal role in the onset and progression of tumors and neovascular eye diseases. Despite notable advancements in the development of anti-angiogenic medications that target vascular endothelial growth factor (VEGF) and its receptors (VEGFRs), the occurrence of adverse reactions and drug resistance has somewhat impeded the widespread application of these drugs. Therefore, additional investigations are warranted to explore alternative therapeutic targets. In recent years, owing to the swift advancement of high-throughput sequencing technology, pan-cancer analysis and single-cell sequencing analysis have emerged as pivotal methodologies and focal areas within the domain of omics research, which is of great significance for us to find potential targets related to the regulation of pathological neovascularization. METHODS: Pan-cancer analysis and scRNA-seq data analysis were employed to forecast the association between Actin filament-associated protein 1 like 1 (AFAP1L1) and the development of tumors and endothelial cells. Tumor xenograft model and ocular pathological neovascularization model were constructed as well as Isolectin B4 (IsoB4) staining and immunofluorescence staining were used to assess the effects of AFAP1L1 on the progression of neoplasms and neovascular eye diseases in vivo. Transwell assay, wound scratch assay, tube forming assay, three-dimensional germination assay, and rhodamine-phalloidin staining were used to evaluate the impact of AFAP1L1 on human umbilical vein endothelial cells (HUVECs) function in vitro; Dual luciferase reporting, qRT-PCR and western blot were used to investigate the upstream and downstream mechanisms of pathological neovascularization mediated by AFAP1L1. RESULTS: Our investigation revealed that AFAP1L1 plays a crucial role in promoting the development of various tumors and demonstrates a strong correlation with endothelial cells. Targeted suppression of AFAP1L1 specifically in endothelial cells in vivo proves effective in inhibiting tumor formation and ocular pathological neovascularization. Mechanistically, AFAP1L1 functions as a hypoxia-related regulatory protein that can be activated by HIF-1α. In vitro experiments demonstrated that reducing AFAP1L1 levels can reverse hypoxia-induced excessive angiogenic capacity in HUVECs. The principal mechanism of angiogenesis inhibition entails the regulation of tip cell behavior through the YAP-DLL4-NOTCH axis. CONCLUSION: In conclusion, AFAP1L1, a newly identified hypoxia-related regulatory protein, can be activated by HIF-1α. Inhibiting AFAP1L1 results in the inhibition of angiogenesis by suppressing the germination of endothelial tip cells through the YAP-DLL4-NOTCH axis. This presents a promising therapeutic target to halt the progression of tumors and neovascular eye disease.

TRPM8 knockdown relieved inflammatory response and cell apoptosis in pneumonia model induced by Streptococcus pneumoniae in vitro.

Streptococcus pneumoniae infection remains a leading cause of pneumonia-related deaths. Transient receptor potential melastatin 8 (TRPM8) exerts crucial roles in lung diseases. We first dissected the role of TRPM8 in pneumococcal pneumonia and the mechanism related to TRPM8 effects. TRPM8 expression and inflammation cytokines level were determined in 15 paired patients and controls. A549 cells were pretreated with si-TRPM8, followed by infection with S. pneumoniae D39 strain (D39). TRPM8 expressions in D39-treated cells were detected and the effect of TRPM8 inhibition on the viability, apoptosis, and inflammation induced by D39 was evaluated. To explore the mechanism underlying TRPM8 effects, cells in D39+si-TRPM8 group were further treated with MAPK activator (Anisomycin, ANIS). TRPM8 was highly expressed in patients and cell models at mRNA or/and protein levels. Cytokines of TNF-α, IL-1ß and IL-6 were intensely upregulated in the serum samples of patients and cells infected with D39 (p<0.05). TRPM8 knockdown attenuated the reduced cell viability and increased cell apoptosis (reflected by the upregulation of Bax and downregulation of Bcl-2) in D39 group (p<0.05). The expression level of inflammation cytokines was lower in D39+si-TRPM8 group than D39 group (p<0.05). The protein levels of NF-κB p-p65 and p-p38 MAPK were intensely accumulated in D39 treated cells, while reduced by TRPM8 inhibition (p<0.05). ANIS addition significantly attenuated the altered cell viability, cell apoptosis and inflammation response in D39+si-TRPM8 group (p<0.05). TRPM8 knockdown relieved D39 infection-caused inflammation and cell apoptosis via NF-κB/MAPK signaling.

Pyridoxal-5'-phosphate-dependent bifunctional enzyme catalyzed biosynthesis of indolizidine alkaloids in fungi.

Indolizidine alkaloids such as anticancer drugs vinblastine and vincristine are exceptionally attractive due to their widespread occurrence, prominent bioactivity, complex structure, and sophisticated involvement in the chemical defense for the producing organisms. However, the versatility of the indolizidine alkaloid biosynthesis remains incompletely addressed since the knowledge about such biosynthetic machineries is only limited to several representatives. Herein, we describe the biosynthetic gene cluster (BGC) for the biosynthesis of curvulamine, a skeletally unprecedented antibacterial indolizidine alkaloid from Curvularia sp. IFB-Z10. The molecular architecture of curvulamine results from the functional collaboration of a highly reducing polyketide synthase (CuaA), a pyridoxal-5'-phosphate (PLP)-dependent aminotransferase (CuaB), an NADPH-dependent dehydrogenase (CuaC), and a FAD-dependent monooxygenase (CuaD), with its transportation and abundance regulated by a major facilitator superfamily permease (CuaE) and a Zn(II)Cys6 transcription factor (CuaF), respectively. In contrast to expectations, CuaB is bifunctional and capable of catalyzing the Claisen condensation to form a new C-C bond and the α-hydroxylation of the alanine moiety in exposure to dioxygen. Inspired and guided by the distinct function of CuaB, our genome mining effort discovers bipolamines A-I (bipolamine G is more antibacterial than curvulamine), which represent a collection of previously undescribed polyketide alkaloids from a silent BGC in Bipolaris maydis ATCC48331. The work provides insight into nature's arsenal for the indolizidine-coined skeletal formation and adds evidence in support of the functional versatility of PLP-dependent enzymes in fungi.

Survival experience of patients undergoing oesophagectomy during the recovery period: A meta-synthesis of qualitative studies.

AIMS AND OBJECTIVE: To systematically review and synthesise existing qualitative research evidence describing the survival experience of patients undergoing oesophagectomy during recovery. BACKGROUND: Patients with oesophageal cancer undergoing surgical treatment have severe physical and psychological burdens during the recovery period. Qualitative studies on the survival experience of patients undergoing oesophagectomy are increasing annually, but there is no integration of qualitative evidence. DESIGN: A systematic review and synthesis of qualitative studies were conducted following the ENTREQ. METHODS: Five English (CINAHL, Embase, PubMed, Web of Science and Cochrane Library) and three Chinese (Wanfang, CNKI and VIP) databases were searched for literature on the survival of patients undergoing oesophagectomy during the recovery period from its establishment in April 2022. The quality of the literature was evaluated by the 'Qualitative Research Quality Evaluation Criteria for the JBI Evidence-Based Health Care Centre in Australia', and the data were synthesised by the thematic synthesis method of Thomas and Harden. RESULTS: A total of 18 studies were included, and four themes were identified: physical and mental dual challenges, impaired social functioning, efforts to return to normal life, lack of knowledge and skills in post-discharge care, and thirst for external support. CONCLUSIONS: Future research should focus on the problem of reduced social interaction during the recovery of patients with oesophageal cancer, formulating individualised exercise intervention programs and establishing a sound social support system. RELEVANCE TO CLINICAL PRACTICE: The results of this study provide evidence-based support for nurses to carry out targeted interventions and reference methods for patients with oesophageal cancer to rebuild their lives. NO PATIENT OR PUBLIC CONTRIBUTION: The report was a systematic review and did not involve a population study.

A randomised controlled trial to improve the resilience of oesophageal cancer survivors in rural China: A study protocol.

AIM: To design a protocol based on the experiences of long-term survivors to facilitate resilience for oesophageal cancer patients in rural China. BACKGROUND: According to the latest Global Cancer Statistics Report, 604,000 new cases of oesophageal cancer were reported, of which over 60% of the disease burden is distributed in China. The incidence of oesophageal cancer in rural China (15.95/100,000) is twice as high as those in urban areas (7.59/100,000). To be sure, resilience can help patients better adapt to post-cancer life. But universal interventions involving improving the resilience of oesophageal cancer patients have much less been explored, especially for rural patients. METHODS: The two-arm, parallel design, non-blinded, randomised controlled trial will be implemented in 86 adults diagnosed with oesophageal cancer and will be randomly assigned to the control group or the intervention group via the blocked randomisation. The intervention group will undergo an intervention with one-on-one guidance from a nurse while viewing a CD of the experiences of long-term survivors with oesophageal cancer in rural areas. Every 2 weeks, a theme session will be introduced, and the entire intervention will continue for 12 weeks. Psychosocial variables (resilience, self-efficacy, coping mode and family support) will be surveyed at baseline, post-intervention and 3 months after the intervention. The paper complies with the Standard Protocol Items: Recommendations for Intervention Trials 2013 and Consolidated Standards of Reporting Trials guidelines for study protocols adapted for designing and reporting parallel group randomised trials. CONCLUSION: The intervention programme transitions from hospitalisation to discharge, which includes one-on-one interventions by medical personnel and a portable CD describing the experiences of long-term survivors with rural oesophageal cancer. Once the intervention's effectiveness is proven, this protocol will provide psychological support for massive oesophageal cancer patients. RELEVANCE TO CLINICAL PRACTICE: The intervention programme may be used as an auxiliary therapy to promote patients' postoperative psychological rehabilitation. This programme has the advantages of being cost-effective, flexible, accessible, and convenient and can be implemented without the limitation of time, place and clinical medical staff. TRIAL REGISTRATION: The Chinese Clinical Trial Registration number is ChiCTR2100050047. Registered on 16 August 2021.

Phase-Controlled Cobalt Catalyst Boosting Hydrogenation of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran.

The search for non-noble metal catalysts for chemical transformations is of paramount importance. In this study, an efficient non-noble metal catalyst for hydrogenation, hexagonal close-packed cobalt (HCP-Co), was synthesized through a simple one-step reduction of ß-Co(OH)2 nanosheets via a temperature-induced phase transition. The obtained HCP-Co exhibited several-times-higher catalytic efficiency than its face-centered cubic cobalt (FCC-Co) counterpart in the hydrogenation of the C=C/C=O group, especially for the 5-hydroxymethylfurfural (HMF) hydrogenation (8.5-fold enhancement). Density functional theory calculations demonstrated that HMF molecules were adsorbed more firmly on the (112_0) facet of HCP-Co than that on the (111) facet of FCC-Co, favoring the activation of the C=O group in the HMF molecule. The stronger adsorption on the (112_0) facet of HCP-Co also led to lower activation energy than that on the (111) facet of FCC-Co, thereby resulting in high activity and selectivity. Moreover, HCP-Co exhibited outstanding catalytic stability during the hydrogenation of HMF. These results highlight the possibility of fabricating hydrogenation catalysts with satisfactory catalytic properties by precisely tuning their active crystal phase.

Phosphodiesterase 5 and Arginase Inhibitory Activities of the Extracts from Some Members of Nelumbonaceae and Nymphaeaceae Families.

The objectives of this study were (1) to investigate the effect of extracts from some plants in the families Nelumbonaceae and Nymphaeaceae on phosphodiesterase 5 (PDE5) and arginase, which have been used in erectile dysfunction treatment, and (2) to isolate and identify the compounds responsible for such activities. The characterization and quantitative analysis of flavonoid constituents in the active extracts were performed by HPLC. Thirty-seven ethanolic extracts from different parts of plants in the genus Nymphaea and Victoria of Nymphaeaceae and genus Nelumbo of Nelumbonaceae were screened for PDE5 and arginase inhibitory activities. The ethanolic extracts of the receptacles and pollens of Nelumbo nucifera Gaertn., petals of Nymphaea cyanea Roxb. ex G.Don, Nymphaea stellata Willd., and Victoria amazonica (Poepp.) Sowerby and the petals and receptacles of Nymphaea pubescens Willd. showed IC50 values on PDE5 of less than 25 µg/mL while none of the extracts showed effects on arginase. The most active extract, N. pubescens petal extract, was fractionated to isolate and identify the PDE5 inhibitors. The results showed that six flavonoid constituents including quercetin 3'-O-ß-xylopyranoside (1), quercetin 3-methyl ether 3'-O-ß-xylopyranoside (2), quercetin (3), 3-O-methylquercetin (4), kaempferol (5) and 3-O-methylkaempferol (6) inhibited PDE5 with IC50 values at the micromolar level.

Assessment of heavy metal contamination of an electrolytic manganese metal industrial estate in northern China from an integrated chemical and magnetic investigation.

Heavy metal concentrations (Al, V, Mn, Fe, Co, Ni, Cu, Zn, and Pb) and the magnetic properties of soil and sediment samples in/around an electrolytic manganese metal (EMM) industrial estate in northern China were investigated. Potential enrichment of Mn, Zn, and Pb was found in/around the core area of the EMM industrial estate; however, the pollution load index (PLI) values did not indicate severely polluted levels. For adults, all hazard index (HI) values of noncarcinogenic risks in the soil samples were below the safe level of 1.00. For children, none of the HI values exceeded the safe level, except Mn (HI = 1.23) in one industrial estate sample. The particle size of magnetic materials was mostly in the range of stable single-domain, and coarser ferrimagnetic phases enhanced the magnetic parameters in the industrial estate soils. Highly positive correlations were found between magnetic parameters, heavy metal concentrations, and PLI values, demonstrating that the magnetic parameters are an efficient proxy for assessing heavy metal contamination. Enrichment of Mn, Zn, and Pb was mainly derived from the EMM industry. The data showed that the EMM industrial estate under cleaner production had limited adverse impacts on the adjacent environment from the perspective of heavy metal contamination.

Biosynthesis of Phomactin Platelet Activating Factor Antagonist Requires a Two-Enzyme Cascade.

Phomactin diterpenoids possess a unique bicyclo[9.3.1]pentadecane skeleton with multiple oxidative modifications, and are good platelet-activating factor (PAF) antagonists that can inhibit PAF-induced platelet aggregation. In this study, we identified the gene cluster (phm) responsible for the biosynthesis of phomactins from a marine fungus, Phoma sp. ATCC 74077. Despite the complexity of their structures, phomactin biosynthesis only requires two enzymes: a type I diterpene cyclase PhmA and a P450 monooxygenase PhmC. PhmA was found to catalyze the formation of the phomactatriene, while PhmC sequentially catalyzes the oxidation of multiple sites, leading to the generation of structurally diverse phomactins. The rearrangement mechanism of the diterpene scaffold was investigated through isotope labeling experiments. Additionally, we obtained the crystal complex of PhmA with its substrate analogue FGGPP and elucidated the novel metal-ion-binding mode and enzymatic mechanism of PhmA through site-directed mutagenesis. This study provides the first insight into the biosynthesis of phomactins, laying the foundation for the efficient production of phomactin natural products using synthetic biology approaches.

Total Biosynthesis of Mutaxanthene Unveils a Flavoprotein Monooxygenase Catalyzing Xanthene Ring Formation.

Flavoprotein monooxygenases (FPMOs) play important roles in generating structural complexity and diversity in natural products biosynthesized by type II polyketide synthases (PKSs). In this study, we used genome mining to discover novel mutaxanthene analogues and investigated the biosynthesis of these aromatic polyketides and their unusual xanthene framework. We determined the complete biosynthetic pathway of mutaxathene through in vivo gene deletion and in vitro biochemical experiments. We show that a multifunctional FPMO, MtxO4, catalyzes ring rearrangement and generates the required xanthene ring through a multistep transformation. In addition, we successfully obtained all necessary enzymes for in vitro reconstitution and completed the total biosynthesis of mutaxanthene in a stepwise manner. Our results revealed the formation of a rare xanthene ring in type II polyketide biosynthesis, and demonstrate the potential of using total biosynthesis for the discovery of natural products synthesized by type II PKSs.