T7 RNA polymerase (T7 RNAP) is one of the simplest known RNA polymerases. Its unique structural features make it a critical model for studying the mechanisms of RNA synthesis. This review systematically examines the static crystal structure of T7 RNAP, beginning with an in-depth examination of its characteristic “thumb”, “palm”, and “finger” domains, which form the classic “right-hand-like” architecture. By detailing these structural elements, this review establishes a foundation for understanding the overall organization of T7 RNAP. This review systematically maps the functional roles of secondary structural elements and their subdomains in transcriptional catalysis, progressively elucidating the fundamental relationships between structure and function. Further, the intrinsic flexibility of T7 RNAP and its applications in research are also discussed. Additionally, the review presents the structural diagrams of the enzyme at different stages of the transcription process, and through these diagrams, it provides a detailed description of the complete transcription process of T7 RNAP. By integrating structural dynamics and kinetics analyses, the review constructs a comprehensive framework that bridges static structure to dynamic processes. Despite its advantages, T7 RNAP has a notable limitation: it generates double-stranded RNA (dsRNA) as a byproduct. The presence of dsRNA not only compromises the purity of mRNA products but also elicits nonspecific immune responses, which pose significant challenges for biotechnological and therapeutic applications. The review provides a detailed exploration of the mechanisms underlying dsRNA formation during T7 RNAP catalysis, reviews current strategies to mitigate this issue, and highlights recent progress in the field. A key focus is the semi-rational design of T7 RNAP mutants engineered to minimize dsRNA generation and enhance catalytic performance. Beyond its role in transcription, T7 RNAP exhibits rapid development and extensive application in fields, including gene editing, biosensing, and mRNA vaccines. This review systematically examines the structure-function relationships of T7 RNAP, elucidates the mechanisms of dsRNA formation, and discusses engineering strategies to optimize its performance. It further explores the engineering optimization and functional expansion of T7 RNAP. Furthermore, this review also addresses the pressing issues that currently need resolution, discusses the major challenges in the practical application of T7 RNAP, and provides an outlook on potential future research directions. In summary, this review provides a comprehensive analysis of T7 RNAP, ranging from its structural architecture to cutting-edge applications. We systematically examine: (1) the characteristic right-hand domains (thumb, palm, fingers) that define its minimalistic structure; (2) the structure-function relationships underlying transcriptional catalysis; and (3) the dynamic transitions during the complete transcription cycle. While highlighting T7 RNAP’s versatility in gene editing, biosensing, and mRNA vaccine production, we critically address its major limitation—dsRNA byproduct formation—and evaluate engineering solutions including semi-rationally designed mutants. By synthesizing current knowledge and identifying key challenges, this work aims to provide novel insights for the development and application of T7 RNAP and to foster further thought and progress in related fields.

This study explores the effect and mechanism of Banxia Xiexin Decoction(BXD) in inhibiting colon cancer progression by reshaping tryptophan metabolism. Balb/c mice were assigned into control, model, low-dose BXD(BXD-L), and high-dose BXD(BXD-H) groups. Except the control group, the other groups were subcutaneously injected with CT26-Luc cells for the modeling of colon cancer, which was followed by the intervention with BXD. Small animal live imaging was employed to monitor tumor growth, and the tumor volume and weight were measured. Hematoxylin-eosin(HE) staining was used to observe the pathological changes in mouse tumors. Immunohistochemistry was used to detect Ki67 expression in tumors. Immunofluorescence and flow cytometry were used to detect the infiltration and number changes of CD3~+/CD8~+ T cells in the tumor tissue. Enzyme-linked immunosorbent assay(ELISA) was employed to measure the levels of interferon-gamma(IFN-γ) and interleukin-2(IL-2) in tumors. Targeted metabolomics was employed to measure the level of tryptophan(Trp) in the serum, and the Trp content in the tumor tissue was measured. Western blot and RT-qPCR were employed to determine the protein and mRNA levels, respectively, of indoleamine 2,3-dioxygenase 1(IDO1), MYC proto-oncogene, and solute carrier family 7 member 5(SLC7A5) in the tumor tissue. Additionally, a co-culture model with CT26 cells and CD8~+ T cells was established in vitro and treated with the BXD-containing serum. The cell counting kit-8(CCK-8) assay was used to examine the viability of CT26 cells. The content of Trp in CT26 cells and CD8~+ T cells, as well as the secretion of IFN-γ and IL-2 by CD8~+ T cells, was measured. RT-qPCR was used to determine the mRNA levels of MYC and SLC7A5 in CT26 cells. The results showed that BXD significantly inhibited the tumor growth, reduced the tumor weight, and decreased the tumor volume in the model mice. In addition, the model mice showed sparse arrangement of tumor cells, varying degrees of patchy necrosis, and downregulated expression of Ki67 in the tumor tissue. BXD elevated the levels of IFN-γ and IL-2 in the tumor tissue, while upregulating the ratio of CD3~+/CD8~+ T cells and lowering the levels of Trp, IDO1, MYC, and SLC7A5. The co-culture experiment showed that BXD-containing serum reduced Trp uptake by CT26 cells, increased Trp content in CD8~+T cells, enhanced IL-2 and IFN-γ secretion of CD8~+T cells, and down-regulated the mRNA levels of MYC and SLC7A5 in CT26 cells. In summary, BXD can inhibit the MYC/SLC7A5 pathway to reshape Trp metabolism and adjust Trp uptake by CD8~+ T cells to enhance the cytotoxicity, thereby inhibiting the development of colon cancer.
Animals ; Tryptophan/metabolism* ; Colonic Neoplasms/pathology* ; Mice ; Drugs, Chinese Herbal/administration & dosage* ; Mice, Inbred BALB C ; Humans ; Cell Line, Tumor ; Indoleamine-Pyrrole 2,3,-Dioxygenase/metabolism* ; Female ; Disease Progression ; Cell Proliferation/drug effects* ; Proto-Oncogene Mas ; Male

Objective To observe the value of spectral CT material separation technology for diagnosing traumatic bone marrow edema in limbs.Methods Totally 51 patients with limb traumatic bone marrow edema were retrospectively enrolled and divided into young group(n=26,18-43 years)and middle-aged group(n=25,46-74 years).Taken MRI as reference standard,the efficacy of spectral CT Water-hydroxyapatite(HAP)image for diagnosing bone marrow edema in trauma area was analyzed,and the Water-HAP density values were compared between groups.Results No significant difference of diagnosing bone marrow edema was found between spectral CT and MRI(x2=0.201,P=0.654),and the consistency was high(Kappa=0.774).Water-HAP density value in bone marrow edema area was higher than that in non bone marrow edema area(t=24.634,P＜0.05),and no significant difference of Water-HAP density values in bone marrow edema area nor non bone marrow edema area was found between young group and middle-aged group(both P＞0.05).Conclusion Spectral CT material separation technology was helpful for diagnosing traumatic bone marrow edema in limbs.

Objective:To explore the value of contrast-enhaoced echocardiography for measuring pulmonary transit time（PTT）in assessing heart failure after percutaneous coronary intervention（PCI）in acute ST-segment elevation myocardial infarction（STEMI）patients.Methods:From September 2023 to September 2024，120 patients with STEMI undergoing PCI at Hunan Provincial People's Hospital were prospectively selected and divided into a heart failure group（ n=42）and a non-heart failure group（ n=78）according to the guidelines. The differences in general clinical data，laboratory parameters，and echocardiographic parameters between the two groups were compared. The diagnostic efficacies of PTT，normalized PTT（nPTT），and N-terminal pro-B-type natriuretic peptide（NT-proBNP）were analyzed. Consistency between them and New York Heart Association（NYHA）heart function classification was tested. Results:Compared to the non-heart failure group，the NT-proBNP，PTT，and nPTT values in the heart failure group were significantly increased（all P<0.05）. The area under the curve（AUC）of nPTT was 0.944，better than that of PTT and NT-proBNP（AUC=0.871，0.887）. After K-means clustering reclassified patients into four levels based on nPTT values，nPTT classification showed moderate consistency with NYHA classification（Kappa=0.580， P<0.001），and nPTT differed significantly across NYHA classifications（ P<0.05）. Conclusions:PTT，as an echocardiographic index for assessing cardiac function，has similar diagnostic efficacy to NT-proBNP，the nPTT is even better. It shows moderate consistency with the NYHA classification and holds potential for differentiating overlapping NYHA grades. Importantly，it offers a fresh objective way to evaluate cardiac dysfunction after PCI in STEMI patients.

Organophosphorus nerve agents are the most threatening chemical warfare agents and terrorist agents.The number of nerve agents and their related chemicals involved in the verification of Chemical Weapon Convention(CWC)exceeds ten million,with the majority being isomers.Accurate structural identification of these chemicals has always been one of the challenges in CWC related verification analysis.In this work,a total of 17 kinds of alkyl phosphonate isomers and structural analogs from 5 groups were designed and synthesized,and then analyzed by gas chromatography-mass spectrometry(GC-MS)and gas chromatography-infrared spectroscopy(GC-FTIR).The spectra of isomers or structural analogs obtained from two techniques as well as the structural information provided therein were compared and analyzed.The results showed that for isomers or structural analogs with similar MS spectra,FTIR spectra could provided more structural fingerprint information of compounds and had advantages in confirming structures.Combined with the excellent separation ability of GC,GC-FTIR can be used to assist GC-MS in the structural confirmation of alkyl phosphates,achieving rapid and accurate identification of isomers or structural analogues.

Current ambient mass spectrometry ionization often requires external auxiliary equipment such as high-voltage power supply,gas cylinder,and syringe pump.Moreover,the process of sample preparation is cumbersome,and the experimental operations are complex,which makes it difficult to adapt to real-time on-site detection.In this work,a novel method was proposed,in which direct sampling of raw samples,online extraction of interest analytes,and ionization of target molecules were integrated into a single unit.With the developed method,the in-situ extraction and nano-electrospray ionization for both liquid and solid raw samples were achieved.Also,a handheld ion source and its pose adjustment device were developed,and the position and angle parameters were subsequently optimized.The performance of the ionization device was tested using standard solutions of caffeine and reserpine.The limits of detection(LODs)were 0.08 μg/L and 0.14 μg/L,with relative standard deviations(RSDs)≤3.7% and≤5.6%,respectively,indicating that the device possessed high sensitivity and stability.Using this device,three different concentrations of reserpine standard solutions were continuously tested for five days.The intra-day RSDs were consistently≤4.7% and the inter-day RSDs were all≤10.3%,showing the good working stability of the device.Without any pretreatment,a rapid qualitative detection of medicinal components including astragaloside II and cycloastragenol in five traditional Chinese medicines was carried out,with RSDs≤8.0% and≤7.1%,respectively.Additionally,rapid qualitative detection of gallic acid,a medicinal component,in white peony roots,and hypaphorine as well as quercetin in cowherb seeds were carried out,with RSDs≤7.0%,≤6.4% and≤6.1%,respectively.These results demonstrated that the ionization technology and device exhibited good stability during qualitative detection of raw samples.

Objective To elucidate the correlation between specific nucleocapsid(N)protein mutant of the SARS-CoV-2 B.1.1.7 variant and clinical stratification in COVID-19 patients,revealing their impact on N protein liquid-liquid phase separation(LLPS)and host innate immune response.Methods Based on whole-genome sequencing data of the SARS-CoV-2 B.1.1.7 lineage from the GISAID database,non-synonymous mutation sites significantly associated with mild/severe clinical phenotypes were screened.For high-frequency N protein mutant,IFN-β promoter transcriptional activity was quantitatively measured using a dual-luciferase reporter system.qPCR was used to detect the mRNA expression levels of interferon(IFN)-β,interleukin(IL)-6 and tumor necrosis factor(TNF)-α.LLPS characteristics were observed by confocal microscopy.The ubiquitination status of host MAVS was detected by Western blot assay.Results A total of 17 640 non-synonymous mutation sites were identified,among which 65 were associated with mild cases and 20 were related to severe cases,with a mutation frequency>1%.The N protein mutation sites associated with severe cases were D3L,M234I and R203K-G204R-T205I.N protein and the mutants NM234I,NR203K-G204R-T205I inhibited the promoter activity of IFN-β(P＜0.05).Compared to the wild type N protein,NR203K-G204R-T205I mutation significantly reduced the mRNA levels of IFN-β,IL-6 and TNF-α(P＜0.05),and altered the phase separation state by dispersing the formation of LLPS condensates.However,N mutant did not affect the ubiquitination modification of host MAVS.Conclusion N protein mutants of the SARS-CoV-2 B.1.1.7 variant can influence the clinical prognosis of COVID-19 patients by altering LLPS status and suppressing the innate immune responses.These finding provides a theoretical basis for the design of antiviral drugs targeting the N protein.

Objective To elucidate the correlation between specific nucleocapsid(N)protein mutant of the SARS-CoV-2 B.1.1.7 variant and clinical stratification in COVID-19 patients,revealing their impact on N protein liquid-liquid phase separation(LLPS)and host innate immune response.Methods Based on whole-genome sequencing data of the SARS-CoV-2 B.1.1.7 lineage from the GISAID database,non-synonymous mutation sites significantly associated with mild/severe clinical phenotypes were screened.For high-frequency N protein mutant,IFN-β promoter transcriptional activity was quantitatively measured using a dual-luciferase reporter system.qPCR was used to detect the mRNA expression levels of interferon(IFN)-β,interleukin(IL)-6 and tumor necrosis factor(TNF)-α.LLPS characteristics were observed by confocal microscopy.The ubiquitination status of host MAVS was detected by Western blot assay.Results A total of 17 640 non-synonymous mutation sites were identified,among which 65 were associated with mild cases and 20 were related to severe cases,with a mutation frequency>1%.The N protein mutation sites associated with severe cases were D3L,M234I and R203K-G204R-T205I.N protein and the mutants NM234I,NR203K-G204R-T205I inhibited the promoter activity of IFN-β(P＜0.05).Compared to the wild type N protein,NR203K-G204R-T205I mutation significantly reduced the mRNA levels of IFN-β,IL-6 and TNF-α(P＜0.05),and altered the phase separation state by dispersing the formation of LLPS condensates.However,N mutant did not affect the ubiquitination modification of host MAVS.Conclusion N protein mutants of the SARS-CoV-2 B.1.1.7 variant can influence the clinical prognosis of COVID-19 patients by altering LLPS status and suppressing the innate immune responses.These finding provides a theoretical basis for the design of antiviral drugs targeting the N protein.

Objective To observe the value of spectral CT material separation technology for diagnosing traumatic bone marrow edema in limbs.Methods Totally 51 patients with limb traumatic bone marrow edema were retrospectively enrolled and divided into young group(n=26,18-43 years)and middle-aged group(n=25,46-74 years).Taken MRI as reference standard,the efficacy of spectral CT Water-hydroxyapatite(HAP)image for diagnosing bone marrow edema in trauma area was analyzed,and the Water-HAP density values were compared between groups.Results No significant difference of diagnosing bone marrow edema was found between spectral CT and MRI(x2=0.201,P=0.654),and the consistency was high(Kappa=0.774).Water-HAP density value in bone marrow edema area was higher than that in non bone marrow edema area(t=24.634,P＜0.05),and no significant difference of Water-HAP density values in bone marrow edema area nor non bone marrow edema area was found between young group and middle-aged group(both P＞0.05).Conclusion Spectral CT material separation technology was helpful for diagnosing traumatic bone marrow edema in limbs.

Objective:To explore the value of contrast-enhaoced echocardiography for measuring pulmonary transit time（PTT）in assessing heart failure after percutaneous coronary intervention（PCI）in acute ST-segment elevation myocardial infarction（STEMI）patients.Methods:From September 2023 to September 2024，120 patients with STEMI undergoing PCI at Hunan Provincial People's Hospital were prospectively selected and divided into a heart failure group（ n=42）and a non-heart failure group（ n=78）according to the guidelines. The differences in general clinical data，laboratory parameters，and echocardiographic parameters between the two groups were compared. The diagnostic efficacies of PTT，normalized PTT（nPTT），and N-terminal pro-B-type natriuretic peptide（NT-proBNP）were analyzed. Consistency between them and New York Heart Association（NYHA）heart function classification was tested. Results:Compared to the non-heart failure group，the NT-proBNP，PTT，and nPTT values in the heart failure group were significantly increased（all P<0.05）. The area under the curve（AUC）of nPTT was 0.944，better than that of PTT and NT-proBNP（AUC=0.871，0.887）. After K-means clustering reclassified patients into four levels based on nPTT values，nPTT classification showed moderate consistency with NYHA classification（Kappa=0.580， P<0.001），and nPTT differed significantly across NYHA classifications（ P<0.05）. Conclusions:PTT，as an echocardiographic index for assessing cardiac function，has similar diagnostic efficacy to NT-proBNP，the nPTT is even better. It shows moderate consistency with the NYHA classification and holds potential for differentiating overlapping NYHA grades. Importantly，it offers a fresh objective way to evaluate cardiac dysfunction after PCI in STEMI patients.