Marker-free GFP transgenic tobacco plants were constructed based on Cre/lox site-specific recombination system. A GFP gene was introduced into the tobacco genome using the Bar gene as a linked selectable marker flanke...Marker-free GFP transgenic tobacco plants were constructed based on Cre/lox site-specific recombination system. A GFP gene was introduced into the tobacco genome using the Bar gene as a linked selectable marker flanked by recombination sites in a directed orientation. The Bar gene expression box was subsequently excised from the plant genome by a strategy of Cre gene retransformation. After removal of the Cre-NPT Ⅱ locus by genetic segregation through self-cross, plants that incorporated only the GFP transgene were obtained. Transgenic tobacco plants mediated by Agrobacterium tumefaciens were obtained, which resisted herbicide Basta and GFP expressed well, then the Cre gene was subsequently introduced into 5 plants of them, respectively, by retransformation. The leaf disks from Cre transgenic plants were used to test the resistance to Basta on the medium with 8 mg L-1 of PPT. The results showed that few discs were able to regenerate normally, and the excision at 76-100% efficiency depended on individual retransformation events. Evidence for a precise recombination event was confirmed by cloning the nucleotides sequence surrounding the lox sites of the Basta sensitive plants. The result indicated that the excision event in the recombination sites was precise and conservative, without loss or alteration of any submarginal nucleotides of the recombination sites. Bar gene excised plants were selfpollinated to allow segregation of the GFP gene from the Cre-NPT Ⅱ locus. The progenies from self-pollinated plants were scored for Kan senstivity, then the segregation of GFP gene from Cre-NPT Ⅱ locus in the Kan senstive plants were confirmed by PCR analysis subsequently. Hence, constructing marker-free transgenic tobacco plants by Cre/lox sitespecific recombination system was reliable, and the strategy presented here should be applicable to other plants for the construction of marker-free transgenic plants as well.展开更多
The purpose of this study was to demonstrate that actinomyces phage R4 integrase Sre protein efficiently mediate site-specific recombination in Escherichia coll. An intramolecular recombination assay system in E. coli...The purpose of this study was to demonstrate that actinomyces phage R4 integrase Sre protein efficiently mediate site-specific recombination in Escherichia coll. An intramolecular recombination assay system in E. coli was constructed. The plasmid pBZP contains attB and attP sites in direct orientation flanking a lacZ gene. When pBZP was introduced into E. coli cells, in which the plasmid pSREA containing sre gene was resident, Sre protein catalyzed integration of attP into attB site, resulting in excision of the lacZ gene. This integration changed bacteria colonies from blue to white on agar plates containing X-Gal, which showed that the lacZ was removed. The integrant DNAs were identified by enzyme digestion, PCR and DNA sequencing. The minimal sizes of attB and attP were 50 bp and 47 bp for 100% recombination efficiency. The phage recombinase Sre efficiently integrated attP into attB site to create attR and attL in E. coli host environment without Streptomyces specific cofactors. This intrmolecular assay system is a simple and efficient system for Sre-mediated recombination in E. coll.展开更多
Electron–hole(e–h)recombination is a fundamental process that governs energy dissipation and device efficiency in semiconductors.In two-dimensional(2D)materials,the formation of tightly bound excitons makes exciton-...Electron–hole(e–h)recombination is a fundamental process that governs energy dissipation and device efficiency in semiconductors.In two-dimensional(2D)materials,the formation of tightly bound excitons makes exciton-mediated e–h recombination the dominant decay pathway.In this work,nonradiative e–h recombination within excitons in monolayer MoS_(2) is investigated using first-principles simulations that combine nonadiabatic molecular dynamics with GW and real-time Bethe–Salpeter equation(BSE)propagation.A two-step process is identified:rapid intervalley redistribution induced by exchange interaction,followed by slower phonon-assisted recombination facilitated by exciton binding.By selectively removing the screened Coulomb and exchange terms from the BSE Hamiltonian,their respective contributions are disentangled—exchange interaction is found to increase the number of accessible recombination pathways,while binding reduces the excitation energy and enhances nonradiative decay.A reduction in recombination lifetime by over an order of magnitude is observed due to the excitonic many-body effects.These findings provide microscopic insights for understanding and tuning exciton lifetimes in 2D transition-metal dichalcogenides.展开更多
Plastome variation,including single spontaneous nucleotide substitutions and single insertions/deletions,is the major source of leaf variegation in plants.Additionally,one recent study has showed that a simple plastom...Plastome variation,including single spontaneous nucleotide substitutions and single insertions/deletions,is the major source of leaf variegation in plants.Additionally,one recent study has showed that a simple plastome structural variation,which is induced by one pair of small inverted repeats,can also result in leaf variegation.Here we show a complex plastome structural variation caused by intermolecular and intramolecular recombination across three pairs of small inverted repeats accounts for leaf variegation in a widely cultivated shrub Heptapleurum ellipticum(Araliaceae).This plastome structural variation contains two deletions and two duplications,resulting in dramatic expansion of IRs,substantial contraction of LSC and loss of 11 genes that essential for photosynthesis.Plastome heteroplasmy was detected in both green and albino sectors of variegated leaves.Relative to green sectors,albino sectors in the variegated leaves exhibit significantly reduced expression for the 11 genes lost in the mutated plastome as well as 26 other genes,but significantly increased expression for one gene related to translation apparatus.Optical and transmission electron microscopy observations showed that mesophyll cells of albino sectors possess plastids lacking grana lamellae,which likely carry the mutated plastome and contribute to albinism.In both sectors,the first layer of spongy mesophyll cells beneath the lower epidermis contains normal chloroplasts,suggesting periclinal division of the lower epidermis during development.Our study demonstrates that multiple small repeats can collectively mediate intra-and inter-molecular recombination in plastome and offers a new mechanism accounting for leaf variegation in plants.展开更多
All-inorganic lead-free perovskite solar cells have emerged as environmentally benign candidates;however,their device performance is still constrained by pronounced carrier recombination losses in the bulk and at inte...All-inorganic lead-free perovskite solar cells have emerged as environmentally benign candidates;however,their device performance is still constrained by pronounced carrier recombination losses in the bulk and at interfaces.By combining energy band alignment analysis with detailed modeling of recombination mechanisms,a systematic strategy for optimizing hole transport layers is developed.The results reveal that a negative valence band offset produces a cliff-like interface,which facilitates hole extraction while also accounting for the observed variations in open-circuit voltage.Furthermore,short-circuit current losses are quantitatively attributed to different recombination pathways,modeled by incorporating radiative,Shockley–Read–Hall,Auger,and interface recombination processes.This comprehensive approach not only clarifies the correlation between energy level alignment and recombination dynamics but also highlights the competing roles of band offset and interface defects in determining device performance.The optimized device architecture,based on Ge-based lead-free perovskites,achieves a power conversion efficiency of 25.1%,with an open-circuit voltage of 1.29 V,a short-circuit current density of 22.5 mA·cm^(-2),and a fill factor of 86.3%.These findings provide theoretical guidance for designing stable,high-performance,and environmentally friendly lead-free perovskite solar cells.展开更多
Both FRT-FRT and LoxP-LoxP sites that are the target sepuences of site-specific recombinases have been constructed in a vector, called C4LFY, using the recombinant DNA technigue. C4LFY also contains P elements, 2 exon...Both FRT-FRT and LoxP-LoxP sites that are the target sepuences of site-specific recombinases have been constructed in a vector, called C4LFY, using the recombinant DNA technigue. C4LFY also contains P elements, 2 exons and 1 intron of Drosophila yellow gene, yellow promoter and enhancers, and flanking DNA. Since C4LFY made use of two pairs of FRT and LoxP sites, this vector included two site-specific recombination systems. C4LFY was then integrated into Drosophila genome by P-element-mediated germ line transformation. in the presence of the FLP or Cre recombinase, either FLP/FRT or Cre/LoxP recombination reaction was successfully created at the same position in the genome. Using this system, the molecular basis of yellow gene expression and regulation during development have been investigated. Results indicate that the tissue-specific expression of yellow gene is directly regulated by transcriptional enhancers. in addition, the 5’ and 3’ genomic sequences flanking the yellow gene have been展开更多
For the temporally and spatially regulated expression of the barnase gene in plant, two kinds of plasmids with ere gene and its directly repeat recognition sites lox from bacteriophage P1 were constructed and co-trans...For the temporally and spatially regulated expression of the barnase gene in plant, two kinds of plasmids with ere gene and its directly repeat recognition sites lox from bacteriophage P1 were constructed and co-transformed into tobacco by agrobacterium mediated procedure. The transgenic plants were conformed by PCR analysis. The blocking fragment between the two lox directly repeat sites was excised by Cre protein in the transgenic plant genome. Cloning and seguencing the DNA fragment from the co-transformed plant DNA showed that the precise DNA excision occurred in transgenic tobacco genome directed by Cre//ox site-specif ic recombination .展开更多
Objective:Patients with homologous recombination deficiency(HRD)demonstrate distinct clinicopathological and prognostic features.However,standardised and clinically validated HRD detection methodologies specifically t...Objective:Patients with homologous recombination deficiency(HRD)demonstrate distinct clinicopathological and prognostic features.However,standardised and clinically validated HRD detection methodologies specifically tailored for non-small cell lung cancer(NSCLC)have yet to be established.Further research is needed to clarify the precise role and clinical implications of HRD in NSCLC.Methods:A cohort of 580 treatment-naive NSCLC patients was retrospectively enrolled.Comprehensive genomic profiling(CGP)was performed for all patients,and HRD status was evaluated using two genomic scar score(GSS)-based algorithms:a machine learning-based GSS(ML-GSS)and a continuous linear regression-based GSS(CLR-GSS).To assess the diagnostic performance(sensitivity and specificity)of the ML-GSS and CLR-GSS algorithms for HRD detection,immunohistochemical(IHC)staining was conducted for two HRD-related biomarkers:Schlafen 11(SLFN11)and RAD51.Survival analysis,including progression-free survival(PFS),along with multivariable Cox proportional hazards models,was performed to compare the prognostic value of the two HRD algorithms.Results:Among all patients,146(25.2%)and 46(7.9%)were classified as HRD-positive(HRD+)by ML-GSS and CLR-GSS,respectively.Using SLFN11 IHC expression as the reference standard,comparative analysis demonstrated that ML-GSS exhibited significantly higher sensitivity but lower specificity than CLR-GSS.This trend was consistently observed in RAD51 staining analysis.Compared to HRD-negative(HRD-)patients,MLGSS-defined HRD+cases displayed distinct clinicopathological and genomic features,including a higher prevalence of homologous recombination(HR)-related genes mutations,BRCA1/2 mutations,TP53 mutations,elevated tumor mutation burden(TMB),and increased copy number variations(CNVs).In contrast,CLR-GSSdefined HRD+patients were only enriched for BRCA1/2 mutations,TP53 mutations,and elevated TMB.Furthermore,ML-GSS-defined HRD+status was associated with significantly worse prognosis following first-line therapy compared to HRD-patients.Univariate and multivariable Cox analyses identified ML-GSS-defined HRD+and TP53 mutations as significant predictors and independent risk factors,respectively.No such associations were observed in the CLR-GSS-defined HRD+cohort.Conclusions:ML-GSS demonstrated superior performance to CLR-GSS in assessing chromosomal instability(CIN)and showed greater clinical utility.We recommend the ML-GSS algorithm as a robust and clinically validated tool for HRD/CIN evaluation in NSCLC.Furthermore,ML-GSS-defined HRD+status was identified as both a significant predictor and an independent risk factor.展开更多
In this study, RT-PCR was performed on lung tissue samples from sick pigs in a suspected outbreak of porcine reproductive and respiratory syndrome (PRRS) at a pig farm in Mianyang City, Sichuan Province, China. Positi...In this study, RT-PCR was performed on lung tissue samples from sick pigs in a suspected outbreak of porcine reproductive and respiratory syndrome (PRRS) at a pig farm in Mianyang City, Sichuan Province, China. Positive samples were inoculated into Marc-145 cells to observe lesions. The Marc-145 cells with cytopathic lesions were identified by indirect immunofluorescence. The whole genome sequences of the isolated and purified strains were amplified by RT-PCR and analyzed for homology and genetic evolution. A strain of porcine reproductive and respiratory syndrome virus (PRRSV), named SCMY2023 (GenBank No. PQ179742), was successfully isolated. SCMY2023 has a genome length of 15,321 base pairs (without a poly A tail). Nucleotide and amino acid homology analyses suggest that this strain belongs to Lineage 8, a variant of the highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) prevalent in China. Recombination and genetic evolution analyses indicate that this isolate is a PRRSV variant that recombined with HuN-ZZ (Lineage 8, 98.79% homology) on the backbone of the SCSN2020 strain (Lineage 8, 99.35% homology) in the recombination region from 4407 to 13,107 nucleotides (ORF1a to ORF3). In-depth study of the genetic recombination of this isolate can provide a reference for the prevention and control of PRRS.展开更多
Single-stranded DNA-binding proteins(SSBs)play essential roles in the replication,recombination and repair processes of organellar DNA molecules.In Arabidopsis thaliana,SSBs are encoded by a small family of two genes(...Single-stranded DNA-binding proteins(SSBs)play essential roles in the replication,recombination and repair processes of organellar DNA molecules.In Arabidopsis thaliana,SSBs are encoded by a small family of two genes(SSB1 and SSB2).However,the functional divergence of these two SSB copies in plants remains largely unknown,and detailed studies regarding their roles in the replication and recombination of organellar genomes are still incomplete.In this study,phylogenetic,gene structure and protein motif analyses all suggested that SSB1 and SSB2 probably diverged during the early evolution of seed plants.Based on accurate long-read sequencing results,ssb1 and ssb2 mutants had decreased copy numbers for both mitochondrial DNA(mtDNA)and plastid DNA(ptDNA),accompanied by a slight increase in structural rearrangements mediated by intermediate-sized repeats in mt genome and small-scale variants in both genomes.Our findings provide an important foundation for further investigating the effects of DNA dosage in the regulation of mutation frequencies in plant organellar genomes.展开更多
BACKGROUND Patients with colorectal cancer(CRC)exhibiting microsatellite instability(MSI)-high generally demonstrate a favorable response to immunotherapy.In contrast,the efficacy of immunotherapy in microsatellite-st...BACKGROUND Patients with colorectal cancer(CRC)exhibiting microsatellite instability(MSI)-high generally demonstrate a favorable response to immunotherapy.In contrast,the efficacy of immunotherapy in microsatellite-stable(MSS)CRC patients is considerably restricted.This study sought to evaluate the effectiveness of immu-notherapy in MSS patients characterized by homologous recombination defi-ciency(HRD)as opposed to those with homologous recombination proficiency(HRP).AIM To investigate and compare the clinicopathological characteristics,treatment modalities,and outcomes between the HRD and HRP groups in CRC.METHODS Next-generation sequencing was performed on 268 CRC patients to identify tumor-associated genetic alterations and assess their HRD scores and MSI status.Patients with HRD-related gene alterations or an HRD score≥30 were classified into the HRD group,while the remaining patients were assigned to the HRP group.Clinical data,including staging and treatment regimens,were collected for analysis.Cox regression and Kaplan-Meier survival curves were employed to evaluate whether the HRD group demonstrated improved survival outcomes following immunotherapy treatment.RESULTS Among the 268 patients,64 were classified into the HRD group,which had a higher proportion of early-stage CRC diagnoses compared to the HRP group.Kaplan-Meier survival curves indicated significantly better survival rates in the HRD group compared to the HRP group across all cohorts,as well as among MSS patients treated with immunotherapy(P<0.05).CONCLUSION This study demonstrates that CRC patients with HRD have a more favorable prognosis and suggests that HRD status could serve as a predictive marker for immunotherapy response in MSS patients.展开更多
The present work reports on microscopic analyses of recombination at grain boundaries(GBs)in polycrystalline Li-doped(Ag,Cu)_(2)ZnSn(S,Se)_(4)(LiACZTSSe)and Cu_(2)ZnSnS_(4)(CZTS)absorber layers in high-efficiency sola...The present work reports on microscopic analyses of recombination at grain boundaries(GBs)in polycrystalline Li-doped(Ag,Cu)_(2)ZnSn(S,Se)_(4)(LiACZTSSe)and Cu_(2)ZnSnS_(4)(CZTS)absorber layers in high-efficiency solar cells(conversion efficiencies of 14.4%and 10.8%).Recombination velocities sG B were determined at a large number of GBs by evaluating profiles extracted from cathodoluminescence intensity distributions across GBs in these polycrystalline layers.In both Li-ACZTSSe and CZTS absorber layers,the sG B values exhibited wide ranges over several orders of magnitude with a median values of 680 and 1100 cm s^(-1)for the Li-ACZTSSe and CZTS absorbers.展开更多
Metal halide perovskites have rapidly emerged as outstanding semiconductors for laser applications.Surface plasmon resonances of metals offer a platform for improving the perovskite lasing properties of metal halide p...Metal halide perovskites have rapidly emerged as outstanding semiconductors for laser applications.Surface plasmon resonances of metals offer a platform for improving the perovskite lasing properties of metal halide perovskites by accelerating radiative recombination.However,the constraint on degrees of freedom of perovskite-metal interactions in two dimensions keeps us from getting a full picture of plasmon-involved carrier dynamics and reaching the optimum perovskite lasing performance.Here we report a strategy of synthesizing quantitative coassemblies of perovskite and metal nanocrystals for studying the effect of surface plasmons on carrier dynamics in depth and exploring plasmon-enhanced perovskite lasing performance.Within the coassembly,each metal nanocrystal supports localized surface plasmon resonances capable of accelerating radiative recombination of all adjacent perovskite nanocrystals in three dimensions.The quantitative coassemblies disclose the evolution of radiative and nonradiative recombination processes in perovskite nanocrystals with the plasmon modes,identifying an optimal metal nanocrystal content for fulfilling the highest radiative efficiency in perovskite nanocrystals.By virtue of accelerated radiative recombination,the coassemblies of perovskite and metal nanocrystals allowed for the construction of microlaser arrays with enhanced performance including low thresholds and ultrafast outputs.This work fundamentally advances the perovskite-metal systems for plasmonically enhancing perovskite optoelectronic performance.展开更多
Genome rearrangement is an important process that leads to genetic diversity,including mutation-related insertions,deletions,or inversions in the genome[1,2].
Understanding and managing charge carrier recombination dynamics is crucial for optimizing the performance of metal halide perovskite optoelectronic devices.In this work,we introduce a machine learning-assisted intens...Understanding and managing charge carrier recombination dynamics is crucial for optimizing the performance of metal halide perovskite optoelectronic devices.In this work,we introduce a machine learning-assisted intensity-modulated two-photon photoluminescence microscopy approach for quantitatively mapping recombination processes in MAPbBr_(3) perovskite microcrystalline films at micrometer-scale resolution.To enhance model accuracy,a balanced classification sampling strategy was applied during the machine learning optimization stage.展开更多
The published article titled“Truncated Bid Overexpression Induced by Recombinant Adenovirus Cre/LoxP System Suppresses the Tumorigenic Potential of CD133+Ovarian Cancer Stem Cells”has been retracted from Oncology Re...The published article titled“Truncated Bid Overexpression Induced by Recombinant Adenovirus Cre/LoxP System Suppresses the Tumorigenic Potential of CD133+Ovarian Cancer Stem Cells”has been retracted from Oncology Research,Vol.25,No.4,2017,pp.595–603.展开更多
Magnetic resonance imaging(MRI)is a powerful tool for diagnosing and monitoring brain diseases,but its low sensitivity can hinder early detection.To address this challenge,we utilized chemical exchange saturation tran...Magnetic resonance imaging(MRI)is a powerful tool for diagnosing and monitoring brain diseases,but its low sensitivity can hinder early detection.To address this challenge,we utilized chemical exchange saturation transfer(CEST)MRI,which greatly enhances sensitivity for detecting low-concentration compounds.In this study,we developed a CEST contrast agent based on a recombinant adeno-associated viruses(rAAVs)encoding the protamine-1(PRM1)MRI reporter gene.CEST MRI revealed that PRM1 contrast agent effectively highlighted caudate putamen region after injection of the rAAVs into the mouse brain,clearly distinguishing it from the surrounding tissue,with no observable damage.This method provides a sensitive,metal-free CEST contrast agent for in vivo brain cell detection,demonstrating potential for both diagnostic and therapeutic applications in brain diseases.展开更多
Recombinant tissue plasminogen activator is commonly used for hematoma evacuation in minimally invasive surgery following intracerebral hemorrhage.However,during minimally invasive surgery,recombinant tissue plasminog...Recombinant tissue plasminogen activator is commonly used for hematoma evacuation in minimally invasive surgery following intracerebral hemorrhage.However,during minimally invasive surgery,recombinant tissue plasminogen activator may come into contact with brain tissue.Therefore,a thorough assessment of its safety is required.In this study,we established a mouse model of intracerebral hemorrhage induced by type VII collagenase.We observed that the administration of recombinant tissue plasminogen activator without hematoma aspiration significantly improved the neurological function of mice with intracerebral hemorrhage,reduced pathological damage,and lowered the levels of apoptosis and autophagy in the tissue surrounding the hematoma.In an in vitro model of intracerebral hemorrhage using primary cortical neurons induced by hemin,the administration of recombinant tissue plasminogen activator suppressed neuronal apoptosis,autophagy,and endoplasmic reticulum stress.Transcriptome sequencing analysis revealed that recombinant tissue plasminogen activator upregulated the phosphoinositide 3-kinase/RAC-alpha serine/threonine-protein kinase/mammalian target of rapamycin pathway in neurons.Moreover,the phosphoinositide 3-kinase inhibitor LY294002 abrogated the neuroprotective effects of recombinant tissue plasminogen activator in inhibiting excessive apoptosis,autophagy,and endoplasmic reticulum stress.Furthermore,to specify the domain of recombinant tissue plasminogen activator responsible for its neuroprotective effects,various inhibitors were used to target distinct domains.It has been revealed that the epidermal growth factor receptor inhibitor AG-1478 reversed the effect of recombinant tissue plasminogen activator on the phosphoinositide 3-kinase/RAC-alpha serine/threonineprotein kinase/mammalian target of rapamycin pathway.These findings suggest that recombinant tissue plasminogen activator exerts a direct neuroprotective effect on neurons following intracerebral hemorrhage,possibly through activation of the phosphoinositide 3-kinase/RAC-alpha serine/threonine-protein kinase/mammalian target of rapamycin pathway.展开更多
Many eukaryotic genes are members of multi-gene families due to gene duplications, which generate new copies that allow functional divergence. However, the relationship between
基金the National Natural Science Foundation of China (30200185)the Science Foundation of Committee of Education of Chongqing Municipality,China (030208)
文摘Marker-free GFP transgenic tobacco plants were constructed based on Cre/lox site-specific recombination system. A GFP gene was introduced into the tobacco genome using the Bar gene as a linked selectable marker flanked by recombination sites in a directed orientation. The Bar gene expression box was subsequently excised from the plant genome by a strategy of Cre gene retransformation. After removal of the Cre-NPT Ⅱ locus by genetic segregation through self-cross, plants that incorporated only the GFP transgene were obtained. Transgenic tobacco plants mediated by Agrobacterium tumefaciens were obtained, which resisted herbicide Basta and GFP expressed well, then the Cre gene was subsequently introduced into 5 plants of them, respectively, by retransformation. The leaf disks from Cre transgenic plants were used to test the resistance to Basta on the medium with 8 mg L-1 of PPT. The results showed that few discs were able to regenerate normally, and the excision at 76-100% efficiency depended on individual retransformation events. Evidence for a precise recombination event was confirmed by cloning the nucleotides sequence surrounding the lox sites of the Basta sensitive plants. The result indicated that the excision event in the recombination sites was precise and conservative, without loss or alteration of any submarginal nucleotides of the recombination sites. Bar gene excised plants were selfpollinated to allow segregation of the GFP gene from the Cre-NPT Ⅱ locus. The progenies from self-pollinated plants were scored for Kan senstivity, then the segregation of GFP gene from Cre-NPT Ⅱ locus in the Kan senstive plants were confirmed by PCR analysis subsequently. Hence, constructing marker-free transgenic tobacco plants by Cre/lox sitespecific recombination system was reliable, and the strategy presented here should be applicable to other plants for the construction of marker-free transgenic plants as well.
文摘The purpose of this study was to demonstrate that actinomyces phage R4 integrase Sre protein efficiently mediate site-specific recombination in Escherichia coll. An intramolecular recombination assay system in E. coli was constructed. The plasmid pBZP contains attB and attP sites in direct orientation flanking a lacZ gene. When pBZP was introduced into E. coli cells, in which the plasmid pSREA containing sre gene was resident, Sre protein catalyzed integration of attP into attB site, resulting in excision of the lacZ gene. This integration changed bacteria colonies from blue to white on agar plates containing X-Gal, which showed that the lacZ was removed. The integrant DNAs were identified by enzyme digestion, PCR and DNA sequencing. The minimal sizes of attB and attP were 50 bp and 47 bp for 100% recombination efficiency. The phage recombinase Sre efficiently integrated attP into attB site to create attR and attL in E. coli host environment without Streptomyces specific cofactors. This intrmolecular assay system is a simple and efficient system for Sre-mediated recombination in E. coll.
基金supported by the National Key Research and Development Program of China (Grant Nos.2024YFA1409800 for J.Z.and2024YFA1408603 for Q.Z.)the National Natural Science Foundation of China (Grant Nos.12125408,12334004for J.Z.,and 12174363 for Q.Z.)+1 种基金the Innovation Program for Quantum Science and Technology (Grant No.2021ZD0303306 for J.Z.)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0450101 for J.Z.)。
文摘Electron–hole(e–h)recombination is a fundamental process that governs energy dissipation and device efficiency in semiconductors.In two-dimensional(2D)materials,the formation of tightly bound excitons makes exciton-mediated e–h recombination the dominant decay pathway.In this work,nonradiative e–h recombination within excitons in monolayer MoS_(2) is investigated using first-principles simulations that combine nonadiabatic molecular dynamics with GW and real-time Bethe–Salpeter equation(BSE)propagation.A two-step process is identified:rapid intervalley redistribution induced by exchange interaction,followed by slower phonon-assisted recombination facilitated by exciton binding.By selectively removing the screened Coulomb and exchange terms from the BSE Hamiltonian,their respective contributions are disentangled—exchange interaction is found to increase the number of accessible recombination pathways,while binding reduces the excitation energy and enhances nonradiative decay.A reduction in recombination lifetime by over an order of magnitude is observed due to the excitonic many-body effects.These findings provide microscopic insights for understanding and tuning exciton lifetimes in 2D transition-metal dichalcogenides.
基金supported financially by the National Natural Science Foundation of China(31811530297 and 32170217).
文摘Plastome variation,including single spontaneous nucleotide substitutions and single insertions/deletions,is the major source of leaf variegation in plants.Additionally,one recent study has showed that a simple plastome structural variation,which is induced by one pair of small inverted repeats,can also result in leaf variegation.Here we show a complex plastome structural variation caused by intermolecular and intramolecular recombination across three pairs of small inverted repeats accounts for leaf variegation in a widely cultivated shrub Heptapleurum ellipticum(Araliaceae).This plastome structural variation contains two deletions and two duplications,resulting in dramatic expansion of IRs,substantial contraction of LSC and loss of 11 genes that essential for photosynthesis.Plastome heteroplasmy was detected in both green and albino sectors of variegated leaves.Relative to green sectors,albino sectors in the variegated leaves exhibit significantly reduced expression for the 11 genes lost in the mutated plastome as well as 26 other genes,but significantly increased expression for one gene related to translation apparatus.Optical and transmission electron microscopy observations showed that mesophyll cells of albino sectors possess plastids lacking grana lamellae,which likely carry the mutated plastome and contribute to albinism.In both sectors,the first layer of spongy mesophyll cells beneath the lower epidermis contains normal chloroplasts,suggesting periclinal division of the lower epidermis during development.Our study demonstrates that multiple small repeats can collectively mediate intra-and inter-molecular recombination in plastome and offers a new mechanism accounting for leaf variegation in plants.
基金supported by the National Natural Science Foundation of China(Grant Nos.52102165 and 62474056)the Natural Science Foundation of Nanjing University of Posts and Telecommunications(Grant Nos.NY221029 and NY222165)。
文摘All-inorganic lead-free perovskite solar cells have emerged as environmentally benign candidates;however,their device performance is still constrained by pronounced carrier recombination losses in the bulk and at interfaces.By combining energy band alignment analysis with detailed modeling of recombination mechanisms,a systematic strategy for optimizing hole transport layers is developed.The results reveal that a negative valence band offset produces a cliff-like interface,which facilitates hole extraction while also accounting for the observed variations in open-circuit voltage.Furthermore,short-circuit current losses are quantitatively attributed to different recombination pathways,modeled by incorporating radiative,Shockley–Read–Hall,Auger,and interface recombination processes.This comprehensive approach not only clarifies the correlation between energy level alignment and recombination dynamics but also highlights the competing roles of band offset and interface defects in determining device performance.The optimized device architecture,based on Ge-based lead-free perovskites,achieves a power conversion efficiency of 25.1%,with an open-circuit voltage of 1.29 V,a short-circuit current density of 22.5 mA·cm^(-2),and a fill factor of 86.3%.These findings provide theoretical guidance for designing stable,high-performance,and environmentally friendly lead-free perovskite solar cells.
文摘Both FRT-FRT and LoxP-LoxP sites that are the target sepuences of site-specific recombinases have been constructed in a vector, called C4LFY, using the recombinant DNA technigue. C4LFY also contains P elements, 2 exons and 1 intron of Drosophila yellow gene, yellow promoter and enhancers, and flanking DNA. Since C4LFY made use of two pairs of FRT and LoxP sites, this vector included two site-specific recombination systems. C4LFY was then integrated into Drosophila genome by P-element-mediated germ line transformation. in the presence of the FLP or Cre recombinase, either FLP/FRT or Cre/LoxP recombination reaction was successfully created at the same position in the genome. Using this system, the molecular basis of yellow gene expression and regulation during development have been investigated. Results indicate that the tissue-specific expression of yellow gene is directly regulated by transcriptional enhancers. in addition, the 5’ and 3’ genomic sequences flanking the yellow gene have been
文摘For the temporally and spatially regulated expression of the barnase gene in plant, two kinds of plasmids with ere gene and its directly repeat recognition sites lox from bacteriophage P1 were constructed and co-transformed into tobacco by agrobacterium mediated procedure. The transgenic plants were conformed by PCR analysis. The blocking fragment between the two lox directly repeat sites was excised by Cre protein in the transgenic plant genome. Cloning and seguencing the DNA fragment from the co-transformed plant DNA showed that the precise DNA excision occurred in transgenic tobacco genome directed by Cre//ox site-specif ic recombination .
基金supported by the National High Level Hospital Clinical Research Funding(No.BJ-2019-195)the National High Level Hospital Clinical Research Funding(No.BJ-2023-090)。
文摘Objective:Patients with homologous recombination deficiency(HRD)demonstrate distinct clinicopathological and prognostic features.However,standardised and clinically validated HRD detection methodologies specifically tailored for non-small cell lung cancer(NSCLC)have yet to be established.Further research is needed to clarify the precise role and clinical implications of HRD in NSCLC.Methods:A cohort of 580 treatment-naive NSCLC patients was retrospectively enrolled.Comprehensive genomic profiling(CGP)was performed for all patients,and HRD status was evaluated using two genomic scar score(GSS)-based algorithms:a machine learning-based GSS(ML-GSS)and a continuous linear regression-based GSS(CLR-GSS).To assess the diagnostic performance(sensitivity and specificity)of the ML-GSS and CLR-GSS algorithms for HRD detection,immunohistochemical(IHC)staining was conducted for two HRD-related biomarkers:Schlafen 11(SLFN11)and RAD51.Survival analysis,including progression-free survival(PFS),along with multivariable Cox proportional hazards models,was performed to compare the prognostic value of the two HRD algorithms.Results:Among all patients,146(25.2%)and 46(7.9%)were classified as HRD-positive(HRD+)by ML-GSS and CLR-GSS,respectively.Using SLFN11 IHC expression as the reference standard,comparative analysis demonstrated that ML-GSS exhibited significantly higher sensitivity but lower specificity than CLR-GSS.This trend was consistently observed in RAD51 staining analysis.Compared to HRD-negative(HRD-)patients,MLGSS-defined HRD+cases displayed distinct clinicopathological and genomic features,including a higher prevalence of homologous recombination(HR)-related genes mutations,BRCA1/2 mutations,TP53 mutations,elevated tumor mutation burden(TMB),and increased copy number variations(CNVs).In contrast,CLR-GSSdefined HRD+patients were only enriched for BRCA1/2 mutations,TP53 mutations,and elevated TMB.Furthermore,ML-GSS-defined HRD+status was associated with significantly worse prognosis following first-line therapy compared to HRD-patients.Univariate and multivariable Cox analyses identified ML-GSS-defined HRD+and TP53 mutations as significant predictors and independent risk factors,respectively.No such associations were observed in the CLR-GSS-defined HRD+cohort.Conclusions:ML-GSS demonstrated superior performance to CLR-GSS in assessing chromosomal instability(CIN)and showed greater clinical utility.We recommend the ML-GSS algorithm as a robust and clinically validated tool for HRD/CIN evaluation in NSCLC.Furthermore,ML-GSS-defined HRD+status was identified as both a significant predictor and an independent risk factor.
文摘In this study, RT-PCR was performed on lung tissue samples from sick pigs in a suspected outbreak of porcine reproductive and respiratory syndrome (PRRS) at a pig farm in Mianyang City, Sichuan Province, China. Positive samples were inoculated into Marc-145 cells to observe lesions. The Marc-145 cells with cytopathic lesions were identified by indirect immunofluorescence. The whole genome sequences of the isolated and purified strains were amplified by RT-PCR and analyzed for homology and genetic evolution. A strain of porcine reproductive and respiratory syndrome virus (PRRSV), named SCMY2023 (GenBank No. PQ179742), was successfully isolated. SCMY2023 has a genome length of 15,321 base pairs (without a poly A tail). Nucleotide and amino acid homology analyses suggest that this strain belongs to Lineage 8, a variant of the highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) prevalent in China. Recombination and genetic evolution analyses indicate that this isolate is a PRRSV variant that recombined with HuN-ZZ (Lineage 8, 98.79% homology) on the backbone of the SCSN2020 strain (Lineage 8, 99.35% homology) in the recombination region from 4407 to 13,107 nucleotides (ORF1a to ORF3). In-depth study of the genetic recombination of this isolate can provide a reference for the prevention and control of PRRS.
基金supported by grants from the National Natural Science Foundation of China(32170238,32400191)Guangdong Basic and Applied Basic Research Foundation(2023A1515111029)+2 种基金the Science,Technology and Innovation Commission of Shenzhen Municipality(RCYX20200714114538196)the Chinese Academy of Agricultural Sciences Elite Youth Program(grant 110243160001007)the Guangdong Pearl River Talent Program(2021QN02N792)。
文摘Single-stranded DNA-binding proteins(SSBs)play essential roles in the replication,recombination and repair processes of organellar DNA molecules.In Arabidopsis thaliana,SSBs are encoded by a small family of two genes(SSB1 and SSB2).However,the functional divergence of these two SSB copies in plants remains largely unknown,and detailed studies regarding their roles in the replication and recombination of organellar genomes are still incomplete.In this study,phylogenetic,gene structure and protein motif analyses all suggested that SSB1 and SSB2 probably diverged during the early evolution of seed plants.Based on accurate long-read sequencing results,ssb1 and ssb2 mutants had decreased copy numbers for both mitochondrial DNA(mtDNA)and plastid DNA(ptDNA),accompanied by a slight increase in structural rearrangements mediated by intermediate-sized repeats in mt genome and small-scale variants in both genomes.Our findings provide an important foundation for further investigating the effects of DNA dosage in the regulation of mutation frequencies in plant organellar genomes.
基金Supported by Natural Science Foundation of Guangdong Province,No.2021A1515011146 and No.2023A1515010785Key Areas Research and Development Programs of Guangdong Province,No.2023B1111050009.
文摘BACKGROUND Patients with colorectal cancer(CRC)exhibiting microsatellite instability(MSI)-high generally demonstrate a favorable response to immunotherapy.In contrast,the efficacy of immunotherapy in microsatellite-stable(MSS)CRC patients is considerably restricted.This study sought to evaluate the effectiveness of immu-notherapy in MSS patients characterized by homologous recombination defi-ciency(HRD)as opposed to those with homologous recombination proficiency(HRP).AIM To investigate and compare the clinicopathological characteristics,treatment modalities,and outcomes between the HRD and HRP groups in CRC.METHODS Next-generation sequencing was performed on 268 CRC patients to identify tumor-associated genetic alterations and assess their HRD scores and MSI status.Patients with HRD-related gene alterations or an HRD score≥30 were classified into the HRD group,while the remaining patients were assigned to the HRP group.Clinical data,including staging and treatment regimens,were collected for analysis.Cox regression and Kaplan-Meier survival curves were employed to evaluate whether the HRD group demonstrated improved survival outcomes following immunotherapy treatment.RESULTS Among the 268 patients,64 were classified into the HRD group,which had a higher proportion of early-stage CRC diagnoses compared to the HRP group.Kaplan-Meier survival curves indicated significantly better survival rates in the HRD group compared to the HRP group across all cohorts,as well as among MSS patients treated with immunotherapy(P<0.05).CONCLUSION This study demonstrates that CRC patients with HRD have a more favorable prognosis and suggests that HRD status could serve as a predictive marker for immunotherapy response in MSS patients.
基金support by the German-Israeli Helmholtz International Research School HI-SCORE(HIRS-0008)by the project“EFFCISⅡ”funded by the Federal Ministry for Economic Affairs and Climate Action(BMWK)under contract numbers 03EE1059B+9 种基金the Australian Renewable Energy Agency(ARENA)as part of ARENA’s Transformative Research Accelerating Commercialization(TRAC)Programthe Australian Research Council(ARC)Discovery Project(DP230102463)Linkage Project(LP200301593)Baosteel-Australia Joint Research and Development Center(BA19010)support from the Australian Center of Advanced Photovoltaics(ACAP)as a recipient of the ACAP Fel owship(RG172864-B)financial support of the Australian Research Council(ARC)Future Fel owship(FT190100756)funding from the European Union’s H2020 ERC-Consolidator program under grant agreement number no.866018(SENSATE)by the Science and Innovation Ministry of Spain projects number PID2023-148976OB-C41(CURIO-CITY)and PCI2023-145971-2(ACT-FAST,CET-Partnership 2023 program)the European Union’s Horizon research and innovation program under the Marie Skøodowska-Curie grant agreement no.10115148(LEK-PV)part of Maria de Maeztu Units of Excel ence Program CEX2023-001300-M/funded by MICIU/AEI/10.13039/501100011033
文摘The present work reports on microscopic analyses of recombination at grain boundaries(GBs)in polycrystalline Li-doped(Ag,Cu)_(2)ZnSn(S,Se)_(4)(LiACZTSSe)and Cu_(2)ZnSnS_(4)(CZTS)absorber layers in high-efficiency solar cells(conversion efficiencies of 14.4%and 10.8%).Recombination velocities sG B were determined at a large number of GBs by evaluating profiles extracted from cathodoluminescence intensity distributions across GBs in these polycrystalline layers.In both Li-ACZTSSe and CZTS absorber layers,the sG B values exhibited wide ranges over several orders of magnitude with a median values of 680 and 1100 cm s^(-1)for the Li-ACZTSSe and CZTS absorbers.
基金supported by the National Natural Science Foundation of China(Nos.52272186,22090023 and 22375207)Beijing Institute of Technology Research Fund Program for Young Scholars(No.XSQD-6120220081)
文摘Metal halide perovskites have rapidly emerged as outstanding semiconductors for laser applications.Surface plasmon resonances of metals offer a platform for improving the perovskite lasing properties of metal halide perovskites by accelerating radiative recombination.However,the constraint on degrees of freedom of perovskite-metal interactions in two dimensions keeps us from getting a full picture of plasmon-involved carrier dynamics and reaching the optimum perovskite lasing performance.Here we report a strategy of synthesizing quantitative coassemblies of perovskite and metal nanocrystals for studying the effect of surface plasmons on carrier dynamics in depth and exploring plasmon-enhanced perovskite lasing performance.Within the coassembly,each metal nanocrystal supports localized surface plasmon resonances capable of accelerating radiative recombination of all adjacent perovskite nanocrystals in three dimensions.The quantitative coassemblies disclose the evolution of radiative and nonradiative recombination processes in perovskite nanocrystals with the plasmon modes,identifying an optimal metal nanocrystal content for fulfilling the highest radiative efficiency in perovskite nanocrystals.By virtue of accelerated radiative recombination,the coassemblies of perovskite and metal nanocrystals allowed for the construction of microlaser arrays with enhanced performance including low thresholds and ultrafast outputs.This work fundamentally advances the perovskite-metal systems for plasmonically enhancing perovskite optoelectronic performance.
基金supported by grants(92168103,32171417,2019CXJQ01)from the National Nature Science Foundation of China,Shanghai Municipal GovernmentPeak Disciplines(Type IV)of Institutions of Higher Learning in Shanghai.
文摘Genome rearrangement is an important process that leads to genetic diversity,including mutation-related insertions,deletions,or inversions in the genome[1,2].
基金financial support from Swedish Energy Agency grant 50709-1Swedish Research Council grant 2021-05207+2 种基金KAW WISE/WASP grant 01-22Olle Engkvist foundation grant 235-0422Light and Materials profile area at Lund University(Young Investigator Synergy Award,2023)。
文摘Understanding and managing charge carrier recombination dynamics is crucial for optimizing the performance of metal halide perovskite optoelectronic devices.In this work,we introduce a machine learning-assisted intensity-modulated two-photon photoluminescence microscopy approach for quantitatively mapping recombination processes in MAPbBr_(3) perovskite microcrystalline films at micrometer-scale resolution.To enhance model accuracy,a balanced classification sampling strategy was applied during the machine learning optimization stage.
文摘The published article titled“Truncated Bid Overexpression Induced by Recombinant Adenovirus Cre/LoxP System Suppresses the Tumorigenic Potential of CD133+Ovarian Cancer Stem Cells”has been retracted from Oncology Research,Vol.25,No.4,2017,pp.595–603.
基金financially supported by the National Natural Science Foundation of China(82127802,22374157)Strategic Priority Research Program,CAS(XDB0540000,XDC0170000)CAS Youth Interdisciplinary Team(JCTD-2022-13).In addition,Xin Zhou acknowledges the support from the Tencent Foundation through the XPLORER PRIZE.
文摘Magnetic resonance imaging(MRI)is a powerful tool for diagnosing and monitoring brain diseases,but its low sensitivity can hinder early detection.To address this challenge,we utilized chemical exchange saturation transfer(CEST)MRI,which greatly enhances sensitivity for detecting low-concentration compounds.In this study,we developed a CEST contrast agent based on a recombinant adeno-associated viruses(rAAVs)encoding the protamine-1(PRM1)MRI reporter gene.CEST MRI revealed that PRM1 contrast agent effectively highlighted caudate putamen region after injection of the rAAVs into the mouse brain,clearly distinguishing it from the surrounding tissue,with no observable damage.This method provides a sensitive,metal-free CEST contrast agent for in vivo brain cell detection,demonstrating potential for both diagnostic and therapeutic applications in brain diseases.
基金supported by the National Natural Science Foundation of China,Nos.92148206,82071330(both to ZT)a grant from the Major Program of Hubei Province,No.2023BAA005(to ZT)+1 种基金a grant from the Key Research and Discovery Program of Hubei Province,No.2021BCA109(to ZT)the Research Foundation of Tongji Hospital,No.2022B37(to PZ)。
文摘Recombinant tissue plasminogen activator is commonly used for hematoma evacuation in minimally invasive surgery following intracerebral hemorrhage.However,during minimally invasive surgery,recombinant tissue plasminogen activator may come into contact with brain tissue.Therefore,a thorough assessment of its safety is required.In this study,we established a mouse model of intracerebral hemorrhage induced by type VII collagenase.We observed that the administration of recombinant tissue plasminogen activator without hematoma aspiration significantly improved the neurological function of mice with intracerebral hemorrhage,reduced pathological damage,and lowered the levels of apoptosis and autophagy in the tissue surrounding the hematoma.In an in vitro model of intracerebral hemorrhage using primary cortical neurons induced by hemin,the administration of recombinant tissue plasminogen activator suppressed neuronal apoptosis,autophagy,and endoplasmic reticulum stress.Transcriptome sequencing analysis revealed that recombinant tissue plasminogen activator upregulated the phosphoinositide 3-kinase/RAC-alpha serine/threonine-protein kinase/mammalian target of rapamycin pathway in neurons.Moreover,the phosphoinositide 3-kinase inhibitor LY294002 abrogated the neuroprotective effects of recombinant tissue plasminogen activator in inhibiting excessive apoptosis,autophagy,and endoplasmic reticulum stress.Furthermore,to specify the domain of recombinant tissue plasminogen activator responsible for its neuroprotective effects,various inhibitors were used to target distinct domains.It has been revealed that the epidermal growth factor receptor inhibitor AG-1478 reversed the effect of recombinant tissue plasminogen activator on the phosphoinositide 3-kinase/RAC-alpha serine/threonineprotein kinase/mammalian target of rapamycin pathway.These findings suggest that recombinant tissue plasminogen activator exerts a direct neuroprotective effect on neurons following intracerebral hemorrhage,possibly through activation of the phosphoinositide 3-kinase/RAC-alpha serine/threonine-protein kinase/mammalian target of rapamycin pathway.
文摘Many eukaryotic genes are members of multi-gene families due to gene duplications, which generate new copies that allow functional divergence. However, the relationship between
