Efficient Recombination Research Articles

Phospho-TRIM21 orchestrates RPA2 ubiquitination switch to promote homologous recombination and tumor radio/chemo-resistance.

RPA2, a key component of the RPA complex, is essential for single-stranded DNA (ssDNA) binding and DNA repair. However, the regulation of RPA2-ssDNA interaction and the recruitment of repair proteins following DNA damage remain incompletely understood. Our study uncovers a novel mechanism by which phosphorylated TRIM21 (Phospho-TRIM21) regulates RPA2 ubiquitination, thereby modulating homologous recombination and tumor radio/chemo-resistance. In the absence of DNA damage, TRIM21 mediates K63-linked ubiquitination of RPA2, countering K6-linked ubiquitination. Upon DNA damage, ubiquitination-modified RPA2 binds ssDNA, stabilizing the DNA structure and facilitating ATRIP/ATR recruitment. ATR subsequently phosphorylates TRIM21 at Ser41, leading to the dissociation of the TRIM21-RPA2 complex and a shift in RPA2 ubiquitination from K63 to K6 linkage. This shift maintains RPA2 ubiquitination homeostasis and stabilizes the RPA2-ATRIP complex, which is crucial for efficient homologous recombination (HR) repair and enhanced tumor radio/chemo-resistance. We also demonstrate that TRIM21 is frequently upregulated in cancers, and its depletion sensitizes cancer cells to radio/chemotherapy, suggesting its potential as a therapeutic target. This study provides novel insights into TRIM21's role in the DNA damage response and its implications for cancer treatment.

ZnO/CuSe/CdS dual S-scheme heterojunction for superior photo-electrocatalytic applications with efficient charge recombination suppression

ZnO/CuSe/CdS dual S-scheme heterojunction for superior photo-electrocatalytic applications with efficient charge recombination suppression

MD assessment of irradiation resistance of FeMnNiCr under successive bombardment

Abstract The irradiation resistance behavior of Co-free high-entropy alloy FeMnNiCr under successive bombardment is investigated by means of molecular dynamics simulations. There are much less residual defects in FeMnNiCr referring to Ni after prolonged irradiation and large-size defect clusters are observed in FCC Ni but not FeMnNiCr. The formation and growth of dislocations in FeMnNiCr are significantly suppressed. The migration barriers of interstitials are similar to these of vacancies in FeMnNiCr, resulting in a higher efficiency of defect recombination. The defects in Co-free FeMnNiCr show similar trends with NiCoCrFeMn and NiCoCrFe during the irradiation process, suggesting its good potential in nuclear structure materials applications.

InGaN multiquantum wells—problem of carrier injection

This study addresses the issue of effective carrier injection to quantum wells in laser diode structures. The nitride light emitting structures used in this study were fabricated by Metal-Organic Vapor Phase Epitaxy (MOVPE). We developed three distinct sets of samples, with varying quantum barrier thickness, different QWs indium composition and different position relative to the p- and n-sides of the structure. Electroluminescence (EL) and cathodoluminescence (CL) spectra, together with nextnano simulations, were analyzed to investigate the impact of these structural variations on device performance. Our findings revealed that the thickness of the quantum barriers significantly affects the carrier transport and recombination efficiency. Thicker barriers impede hole transport to the quantum wells (QWs). As a result, light emission is predominantly from the QWs located closer to the p-GaN layer. However, in a well-optimized active region the carrier distribution is uniform, leading to both QWs emitting similar amount of light. We also investigated how different indium compositions in the QWs affect the energy levels and recombination dynamics. Our study showed that in structures with two QWs of different indium content, a small (less than 2%) difference in indium concentration leads to uniform light emission across the wells, while a larger difference concentrates recombination in the deeper well.

Multi-gene precision editing tool using CRISPR-Cas12a/Cpf1 system in Ogataea polymorpha

BackgroundOgataea polymorpha, a non-conventional methylotrophic yeast, has demonstrated significant potential for heterologous protein expression and the production of high-value chemicals and biopharmaceuticals. However, the lack of precise and efficient genome editing tools severely hinders the construction of cell factories. Although the CARISP-Cas9 system has been established in Ogataea polymorpha, the gene editing efficiency, especially for multiple genes edition, needs to be further improved.ResultsIn this study, we developed an efficient CRISPR-Cpf1-mediated genome editing system in O. polymorpha that exhibited high editing efficiency for single gene (98.1 ± 1.7%), duplex genes (93.9 ± 2.4%), and triplex genes (94.0 ± 6.0%). Additionally, by knocking out non-homologous end joining (NHEJ) related genes, homologous recombination (HR) efficiency was increased from less than 30% to 90 ~ 100%, significantly enhancing precise genome editing capabilities. The increased HR rates enabled over 90% integration efficiency of triplex genes, as well as over 90% deletion rates of large DNA fragments up to 20 kb. Furthermore, using this developed CRISPR-Cpf1 system, triple genes were precisely integrated into the genome by one-step, enabling lycopene production in O. polymorpha.ConclusionsThis novel multiplexed genome-editing tool mediated by CRISPR-Cpf1 can realize the deletion and integration of multiple genes, which holds great promise for accelerating engineering efforts on this non-conventional methylotrophic yeast for metabolic engineering and genomic evolution towards its application as an industrial cell factory.

Tailored large-particle quantum dots with high color purity and excellent electroluminescent efficiency.

High-quality quantum dots (QDs) possess superior electroluminescent efficiencies and ultra-narrow emission linewidths are essential for realizing ultra-high definition QD light-emitting diodes (QLEDs). However, the synthesis of such QDs remains challenging. In this study, we present a facile high-temperature successive ion layer adsorption and reaction (HT-SILAR) strategy for the growth of precisely tailored Zn1-xCdxSe/ZnSe shells, and the consequent production of high-quality, large-particle, alloyed red CdZnSe/Zn1-xCdxSe/ZnSe/ZnS/CdZnS QDs. The transitional Zn1-xCdxSe/ZnSe shells serve to effectively suppress heavy hole energy level splitting and weaken the exciton-longitudinal optical phonon coupling of QDs, thus facilitating the formation of highly luminescent QDs with a near-unity photoluminescence quantum yield of 97.8% and narrow emission with a full width at half maximum of 17.1nm. In addition, the introduction of transitional shells can extend the particle size of QDs to 19.0nm, which is beneficial for efficient carrier recombination and reduced Joule heating in QD-based LEDs. As a result, the fabricated QLEDs can achieve a record external quantum efficiency of 38.2%, luminance over 120,000cdm-2, and exceptional operational stability T95 (tested at 1,000cdm-2) of 24,100h. These findings provide new avenues for synthesizing high-quality QDs with high color purity.

Uncovering the Performance Enhancing Mechanism of Methanesulfonate Ligands in Perovskite Quantum Dots for Light-Emitting Devices.

Perovskite quantum dots (PQDs) have attracted more and more attention in light-emitting diode (LED) devices due to their outstanding photoelectric properties. Surface ligands not only enable size control of quantum dots but also enhance their optoelectronic performance. However, the efficiency of exciton recombination in PQDs is often hindered by the desorption dynamics of surface ligands, leading to suboptimal electrical performance. In this study, sodium methanesulfonate (NaMeS) was successfully introduced during PQD synthesis and ligand exchange, where the S═O groups effectively interacted with the perovskite components. The NaMeS-modified PQD films exhibited significantly improved surface morphology, radiative recombination efficiency, and carrier mobility. Consequently, Pe-LEDs derived from NaMeS-capped PQDs achieved a remarkable enhancement in performance with a maximum external quantum efficiency of 9.41%. This work thus provides a novel and effective strategy for the development of high-performance PQDs and their applications in LEDs.

SRPKs Homolog Dsk1 Regulates Homologous Recombination Repair in Schizosaccharomyces pombe.

Serine-arginine protein kinases (SRPKs) play important roles in diverse biological processes such as alternative splicing and cell cycle. However, the functions of SRPKs in DNA damage response remain unclear. Here we characterized the function of SRPKs homolog Dsk1 in regulating DNA repair in the fission yeast Schizosaccharomyces pombe. We demonstrated that Dsk1 defective mutants of loss of the gene, spacer domain, and kinase activity as well as its overexpression mutant exhibited sensitivities of replication stress. Genetic analysis revealed that the loss of dsk1+ compromised the efficiency of homologous recombination (HR) repair, and Dsk1 was probably involved in the Rad52- and Rad51-dependent HR repair pathways. Interestingly, Dsk1 translocated into the nucleus upon replication stress and directly interacted with Rad51-mediator Rad52 and phosphorylated Rad52-Ser365 residue. The Rad52-Ser365 phosphorylation-defective mutant was slightly sensitive to replication stress, and the phosphorylation-mimicking mutants exhibited more sensitivities, which were partially correlated with phenotypes of the loss- and gain-of-function of dsk1+. This study uncovers a potential HR repair regulator Dsk1 in response to replication stress and implies that its homolog SRPKs may have the conserved targets and functions in higher eukaryotes.

Colloidal semiconductor quantum shells for solution-processed laser applications.

Laser diodes based on solution-processed semiconductor quantum dots (QDs) present an economical and color-tunable alternative to traditional epitaxial lasers. However, their efficiency is significantly limited by non-radiative Auger recombination, a process that increases lasing thresholds and diminishes device longevity through excessive heat generation. Recent advancements indicate that these limitations can be mitigated by employing spherical quantum wells, or quantum shells (QSs), in place of conventional QDs. The unique QS geometry is designed to suppress multi-exciton Auger decay through exciton-exciton repulsion, thereby extending multi-exciton lifetimes and enhancing their radiative recombination efficiency. In this review, we examine optoelectronic characteristics of QSs and discuss their integration into photonic laser cavities. We further present experimental data demonstrating QS performance in femtosecond, quasi-continuous-wave (quasi-CW), and two-photon upconverted laser configurations, underscoring QS capability to achieve efficient lasing with reduced thresholds and lower energy losses.

Enhanced Optical Gain Through Efficient Polaron Pairs Recombination in F8xBTy

AbstractOrganic semiconductors combine excellent optoelectronic properties with simple fabrication to obtain the desired features by tuning their chemical structures. Förster resonant energy transfer (FRET) is in designing blended gain media, but it does not enhance efficient optical gain in most cases. This is due to the competition between polaron pairs and stimulated emission (SE), leading to quenching of SE. Thus a challenge to design efficient optical gain systems via FRET. Here, a series of copolymers, F8xBTy, through uniformly inserting benzothiadiazole (BT) units into the 9,9‐dioctylfluorene (F8) chain, were synthesized. They consist of both charge transfer (CT) and FRET is synthesized. These copolymers can prevent the local F8 aggregation and lead to efficient polaron pair recombination into singlet excitons. The F8 excitons are thus spatially confined, increasing efficient SE. Efficient light amplification has low amplified spontaneous emission (ASE) thresholds (as low as 5.3 µJ cm−2) and significantly enhanced optical gain with gain coefficients up to 37 cm−1. The distributed feedback (DFB) lasers has low lasing thresholds down to 5.4 nJ per pulse. The results suggest that these copolymers provide a organic gain media design strategy with efficient optical gain, introducing a new approach to developing laser materials for electrically pumped lasers.

Construction of Shoot Apical Meristem cDNA Yeast Library of Brassica napus L. and Screening of Proteins That Interact with the Inflorescence Regulatory Factors BnTFL1s.

The determinate inflorescence trait of Brassica napus L. is associated with various desirable agricultural characteristics. BnTFL1s (BnaA10.TFL1 and BnaC09.TFL1), which encode the transcription factor TERMINAL FLOWER 1 (TFL1), have previously been identified as candidate genes controlling this trait through map-based cloning. However, the mechanism underlying the effects of the BnTFL1 proteins remains unclear. Further, proteins generally interact with each other to fulfill their biological functions. The objective of this study was to construct a cDNA library of the shoot apical meristem (SAM) of B. napus and screen for proteins that interact with BnTFL1s, to better understand its mechanism of action. The recombination efficiency of the yeast two-hybrid (Y2H) library that we constructed was 100%, with insertion fragment lengths ranging from 750 to 2000 bp and a capacity of approximately 1.44 × 107 CFUs (colony-forming units), sufficient for screening protein interactions. Additionally, the bait vector pGBKT7-BnTFL1s was transformed into yeast cells alongside positive and negative controls, demonstrating no toxicity to the yeast cells and no self-activation. This bait was used to screen the SAM cDNA library of B. napus, ultimately identifying two BnTFL1s-interacting proteins: 14-3-3-like protein GF14 omega GRF2. These interactions were verified through one-to-one interaction experiments. This study provides a foundation for further research on the biological functions of the BnTFL1s genes and their regulatory role in inflorescence formation in B. napus, while providing a reference for studying similar mechanisms in other plants.

Hydrothermal Synthesis of Graphitic Carbon Nitride Nanocluster and Study of its Photoluminescence Properties

In the present scenario of modern urbanization there is an increasing demand of different opto-electronic devices that includes light emitting diodes, photo conductors or many others. From this point of view finding a cheap material with high luminescence efficiency is of extreme important. Along with possessing high radiative recombination efficiency the optoelectronic material should be cost effective as well and at the same time it should be synthesized with high yield. Keeping this in mind, this study presents the synthesis of fractal-like graphitic carbon nitride (GCN) nanostructures via a, low-temperature hydrothermal method. The synthesized material was characterized using various techniques where X-ray diffraction (XRD) confirmed proper phase formation, while field emission scanning electron microscopy (FESEM) revealed its fractal like morphology. UV-Vis reflectance spectra, along with the Kubelka-Munk plot, confirmed that the band gap of the material is around 3 eV and thus comes within the violet-blue range. Fourier-transform infrared (FTIR) spectroscopy provided insights into the different vibrational energy levels present in the sample. Photoluminescence (PL) analysis shows strong PL signal at 431 nm and thus corresponds to band to band transition. The findings indicate this fractal-like GCN has the potential to be used as optoelectronic device.

High-Performance and Stable Perovskite/Organic Tandem Solar Cells Enabled by Interconnecting Layer Engineering.

Perovskite/organic tandem solar cells (PO-TSCs) have recently attracted increasing attention due to their high efficiency and excellent stability. The interconnecting layer (ICL) is of great importance for the performance of PO-TSCs. The charge transport layer (CTL) and the charge recombination layer (CRL) that form the ICL should be carefully designed to enhance charge carrier extraction and promote charge carrier recombination balance from the two subcells. Here, we propose an effective strategy to optimize the ICL by using [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) to modify the poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) as the hole transport layer (HTL) in the ICL. It is found that the coverage state of 2PACz on the PEDOT:PSS significantly affects the performance of PO-TSCs and can be regulated by adjusting the concentration of the 2PACz solution. The PEDOT:PSS/2PACz structure facilitates effective charge carrier extraction from the organic solar cells to the CRL. Herein, for the PO-TSCs, this strategy results in an efficient and balanced charge carrier recombination in the ICL and also allows a thinner PEDOT:PSS with reduced parasitic absorption. As a result, the PO-TSC achieves a power conversion efficiency (PCE) of 25.26%, much higher than the control device (PCE of 23.57%), and better stability. This work demonstrates an effective approach to achieving high-performance PO-TSCs through ICL engineering.

High-Brightness Color-Tunable AC-Driven Quantum Dot Light-Emitting Diodes for Integrated Passive High-Electric-Field Contactless Detection.

This work explores the carrier recombination dynamics of AC-driven quantum dot (QD) light-emitting diodes (AC-QLEDs) and proposes their application in the field of electric field contactless detection. Different sequences of green QD (GQD)/red QD (RQD) bilayer thin films as the emission layer of AC-QLEDs were fabricated via film transfer printing to ensure the complete morphology of each layer. AC-QLEDs with the emission layer as the sequence of GQD + RQD (GR-QLEDs) show a significantly enhanced carrier recombination efficiency due to its stable energy level structure, achieving the highest peak brightness ever recorded for vertically emitting brightness of 1648.2 cd/m2 depending on the carriers generated inside the device under AC bias. Owing to an imbalance in the carrier concentration generated by two sides of the emission layer, the proportion of emitted green light changes with the electric field strength, resulting in a macroscopic color shift of GR-QLEDs. The results indicate that although no carriers are injected directly from two electrodes, the equilibrium-induced carrier concentration under the AC electric field remains important. We utilized this unique device structure and color shift of GR-QLEDs for on-site inspection of large-scale communications power consumption. The patterned detector displays a significant color change from 9 × 106 to 6 × 107 V/m. True noncontact direct visualization detection was conducted under variable electric fields from 1 × 107 to 2 × 107 V/m in the vicinity of the running cable by emitting bright light. The proposed passive electric field detector is well-suited for investigating air gap discharge and monitoring spatial electric fields, featuring high integration, transparency, lightweight characteristics, high sensitivity, and broad bandwidth.

Stacking-enabled Si/GaN tunnel junction light-emitting diodes with improved radiative recombination efficiency

Stacking-enabled Si/GaN tunnel junction light-emitting diodes with improved radiative recombination efficiency

The recombination efficiency of the bacterial integron depends on the mechanical stability of the synaptic complex.

Multiple antibiotic resistances are a major global health threat. The predominant tool for adaptation in Gram-negative bacteria is the integron. Under stress, it rearranges gene cassettes to offer an escape using the tyrosine recombinase IntI, recognizing folded DNA hairpins, the attC sites. Four recombinases and two attC sites form the synaptic complex. Yet, for unclear reasons, the recombination efficiency varies greatly. Here, we established an optical tweezers force spectroscopy assay to probe the synaptic complex stability and revealed, for seven combinations of attC sites, significant variability in the mechanical stability. We found a strong correlation between mechanical stability and recombination efficiency of attC sites in vivo, indicating a regulatory mechanism from the DNA structure to the macromolecular complex stability. Taking into account known forces during DNA metabolism, we propose that the variation of the integron in vivo recombination efficiency is mediated by the synaptic complex stability. We anticipate that further recombination processes are also affected by their corresponding mechanical stability.

Rapid and highly efficient recombination of crosslinking points in hydrogels generated via the template polymerization of dynamic covalent three-dimensional nanoparticle crosslinkers

Rapid and highly efficient recombination of crosslinking points in hydrogels generated via the template polymerization of dynamic covalent three-dimensional nanoparticle crosslinkers

Vinylene-Linked Covalent Organic Frameworks for Visible-Light-Promoted Selective Oxidation of Styrene in Water.

Vinylene-linked COFs, as an emerging class of crystalline porous polymers, have been regarded as ideal heterogenous photocatalysts due to their ordered structure, tailored pore size, outstanding stability and fully π-conjugated structure. Unfortunately, their photocatalytic performances are usually impeded by high exciton binding energy and unsatisfactory exciton dissociation efficiency. Herein, the authorsbroke through this dilemma by arrangement of complementary donor-acceptor (D-A) pairs within the COF skeleton to improve charge transfer/separation. Two vinylene-linked COFs (TMT-BT-COF and TMT-TT-COF) are synthesized by Aldol condensation using highly photoactive thienothiophene and benzothiazole groups as donor and electron-deficient triazine units as acceptor. Photochemical/electrochemical studies as well as DFT calculation suggest that these D-A type vinylene-linked COFs endow high charge transfer efficiency and low charge recombination. As a result, both of them demonstrate remarkably catalytic activity in the oxidation of styrene to benzaldehyde with molecular oxygen, with an exceptionally high conversion rate (≥92%) and selectivity (≥90%). Intriguingly, in the presence of NaHCO3, the above COFs could photocatalyze epoxidation styrene in water, and the styrene oxide selectivity reached 53%. This work elucidates the prominent capability of vinylene-linked COFs in the photocatalytic transformation of organic compounds in aqueous media, which may pave a new avenue for their future development.

The sparse driver system for in vivo single-cell labeling and manipulation in Drosophila.

In this protocol, we introduce a sparse driver system for cell-type specific single-cell labeling and manipulation in Drosophila, enabling complete and simultaneous expression of multiple transgenes in the same cells. The system precisely controls expression probability and sparsity via mutant FRT sites with reduced recombination efficiency and tunable FLP levels adjusted by heat-shock durations. We demonstrate that this generalizable toolkit enables tunable sparsity, multi-color staining, single-cell trans-synaptic tracing, single-cell manipulation, and in vivo analysis of cell-autonomous gene function. For details on the use and execution of this protocol, please refer to Xu et al. 2024.

Efficient intraband radiative recombination in Bi-doped Si nanocrystals

It is shown theoretically that sufficiently strong short-range potential of a donor in combination with the effect of quantum confinement is capable of creating great splitting of the energy levels in the conduction band of small Si nanocrystals with a Bi atom. Consequently, radiative transitions between the split levels can generate photons of the near-infrared and, even, visible ranges. Typical rates of these intraband transitions are of the order of 107 s−1, which allows one to hope for high efficiency of possible luminescence in the system.