Molecular basis for receptor recognition and broad host tropism for merbecovirus MjHKU4r-CoV-1.

A novel pangolin-origin MERS-like coronavirus (CoV), MjHKU4r-CoV-1, was recently identified. It is closely related to bat HKU4-CoV, and is infectious in human organs and transgenic mice. MjHKU4r-CoV-1 uses the dipeptidyl peptidase 4 (DPP4 or CD26) receptor for virus entry and has a broad host tropism. However, the molecular mechanism of its receptor binding and determinants of host range are not yet clear. Herein, we determine the structure of the MjHKU4r-CoV-1 spike (S) protein receptor-binding domain (RBD) complexed with human CD26 (hCD26) to reveal the basis for its receptor binding. Measuring binding capacity toward multiple animal receptors for MjHKU4r-CoV-1, mutagenesis analyses, and homology modeling highlight that residue sites 291, 292, 294, 295, 336, and 344 of CD26 are the crucial host range determinants for MjHKU4r-CoV-1. These results broaden our understanding of this potentially high-risk virus and will help us prepare for possible outbreaks in the future.

Application of sutureless corneal incision for patients with congenital ectopia lentis - Is it feasible, effective and safe?

Purpose: To compare the clinical outcomes, feasibility, and safety between groups with sutured and sutureless wound closure in congenital ectopia lentis (CEL) patients. Methods: Patients with CEL who received phacoemulsification combined with intrascleral fixation of capsular hook (CH) and implantation of capsular tension ring (CTR) and in-the-bag intraocular lens (IOL) were included in this study. Results: A total of 68 eyes of 34 patients aged 18 years or younger were enrolled in this study. Incisions of 21 patients (34 eyes) did not require sutures while sutures were applied in 21 patients (34 eyes). Postoperative uncorrected distance visual acuity, best corrected distance visual acuity and intraocular pressure measurements were comparable on follow-up visits (P > 0.05). The magnitude of surgically induced astigmatism was significantly greater (P = 0.001) in the suture group (Median: 0.47; IQ: 1.63, 2.97) than in the sutureless group (Median: 0.88; IQ: 0.63, 1.35). No cases of endophthalmitis and retinal detachment were found postoperatively in either group, while suture-related complications were observed in the sutured group, including loose suture with discomfort in 5 (14.71%) eyes, loose suture with mucus infiltration in 3 (8.82%) eyes. In total, 22 sutures (64.71%) of 34 eyes required removal. Conclusions: Sutureless clear corneal incision in CEL patients can achieve satisfactory clinical results comparable to sutured wound closure in terms of the efficacy and safety. Advantages of this approach are the reduced risk of suture-related complications, no need for additional surgery under general anesthesia for suture removal, and less cost.

Enhancing Light-Emitting Efficiency of Blue Through-Space Charge Transfer Emitters via Fixing Configuration Induced by Intramolecular Hydrogen Bonding.

Closely aligned configuration of the donor (D) and acceptor (A) is crucial for the light-emitting efficiency of thermally activated delayed fluorescence (TADF) materials with through-space charge transfer (TSCT) characteristics. However, precisely controlling the D-A distance of blue TSCT-TADF emitters is still challenging. Herein, an extra donor (D*) located on the side of the primary donor (D) is introduced to construct the hydrogen bonding with A and thus modulate the distance of D and A units to prepare high-efficiency blue TSCT emitters. The obtained "V"-shaped TSCT emitter presents a minimal D-A distance of 2.890 Å with a highly parallel D-A configuration. As a result, a high rate of radiative decay (>107 s-1) and photoluminescence quantum yield (nearly 90%) are achieved. The corresponding blue organic light-emitting diodes show maximum external quantum efficiencies (EQEmax) of 27.9% with a Commission Internationale de L'Eclairage (CIE) coordinate of (0.16, 0.21), which is the highest device efficiency of fluorene-based blue TSCT-TADF emitters. In addition, the TSCT-TADF emitter-sensitized OLEDs also achieve a high EQEmax of 29.3% with a CIE coordinate of (0.12, 0.16) and a narrow emission.

Key mechanistic features of the trade-off between antibody escape and host cell binding in the SARS-CoV-2 Omicron variant spike proteins.

Since SARS-CoV-2 Omicron variant emerged, it is constantly evolving into multiple sub-variants, including BF.7, BQ.1, BQ.1.1, XBB, XBB.1.5 and the recently emerged BA.2.86 and JN.1. Receptor binding and immune evasion are recognized as two major drivers for evolution of the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) protein. However, the underlying mechanism of interplay between two factors remains incompletely understood. Herein, we determined the structures of human ACE2 complexed with BF.7, BQ.1, BQ.1.1, XBB and XBB.1.5 RBDs. Based on the ACE2/RBD structures of these sub-variants and a comparison with the known complex structures, we found that R346T substitution in the RBD enhanced ACE2 binding upon an interaction with the residue R493, but not Q493, via a mechanism involving long-range conformation changes. Furthermore, we found that R493Q and F486V exert a balanced impact, through which immune evasion capability was somewhat compromised to achieve an optimal receptor binding. We propose a "two-steps-forward and one-step-backward" model to describe such a compromise between receptor binding affinity and immune evasion during RBD evolution of Omicron sub-variants.

Structural basis and analysis of hamster ACE2 binding to different SARS-CoV-2 spike RBDs.

Pet golden hamsters were first identified being infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) delta variant of concern (VOC) and transmitted the virus back to humans in Hong Kong in January 2022. Here, we studied the binding of two hamster (golden hamster and Chinese hamster) angiotensin-converting enzyme 2 (ACE2) proteins to the spike protein receptor-binding domains (RBDs) of SARS-CoV-2 prototype and eight variants, including alpha, beta, gamma, delta, and four omicron sub-variants (BA.1, BA.2, BA.3, and BA.4/BA.5). We found that the two hamster ACE2s present slightly lower affinity for the RBDs of all nine SARS-CoV-2 viruses tested than human ACE2 (hACE2). Furthermore, the similar infectivity to host cells expressing hamster ACE2s and hACE2 was confirmed with the nine pseudotyped SARS-CoV-2 viruses. Additionally, we determined two cryo-electron microscopy (EM) complex structures of golden hamster ACE2 (ghACE2)/delta RBD and ghACE2/omicron BA.3 RBD. The residues Q34 and N82, which exist in many rodent ACE2s, are responsible for the lower binding affinity of ghACE2 compared to hACE2. These findings suggest that all SARS-CoV-2 VOCs may infect hamsters, highlighting the necessity of further surveillance of SARS-CoV-2 in these animals.IMPORTANCESARS-CoV-2 can infect many domestic animals, including hamsters. There is an urgent need to understand the binding mechanism of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants to hamster receptors. Herein, we showed that two hamster angiotensin-converting enzyme 2s (ACE2s) (golden hamster ACE2 and Chinese hamster ACE2) can bind to the spike protein receptor-binding domains (RBDs) of SARS-CoV-2 prototype and eight variants and that pseudotyped SARS-CoV-2 viruses can infect hamster ACE2-expressing cells. The binding pattern of golden hamster ACE2 to SARS-CoV-2 RBDs is similar to that of Chinese hamster ACE2. The two hamster ACE2s present slightly lower affinity for the RBDs of all nine SARS-CoV-2 viruses tested than human ACE2. We solved the cryo-electron microscopy (EM) structures of golden hamster ACE2 in complex with delta RBD and omicron BA.3 RBD and found that residues Q34 and N82 are responsible for the lower binding affinity of ghACE2 compared to hACE2. Our work provides valuable information for understanding the cross-species transmission mechanism of SARS-CoV-2.

The E156K mutation in the CRYAA gene affects the epithelial-mesenchymal transition and migration of human lens epithelial cells.

Purpose: To investigated the biological effects of E156K-mutated αA-crystallin (CRYAA) in human lens epithelial cells (HLECs). Methods: FLAG-tagged, human, full-length, wild-type (WT), or E156K-mutated CRYAA was expressed in HLECs under CRYAA knockdown. CRYAA expression was determined by quantitative reverse transcription polymerase chain reaction and western blotting (WB). Rhodamine cytoskeleton staining was used to observe the changes in cell morphology following transfection with WT or E156K-mutated CRYAA plasmids. WB was performed to assess the expression of markers related to epithelial-mesenchymal transition (EMT) and migration. Results: Rhodamine cytoskeleton staining revealed changes in the morphology of cells transfected with E156K-mutated CRYAA and opposite responses occurred after treatment with a ß-catenin inhibitor. Cells transfected with E156K-mutated CRYAA expressed remarkably higher levels of the mesenchymal biomarkers N-cadherin and vimentin but decreased levels of the epithelial biomarker E-cadherin, whereas opposite trends were observed in cells treated with the ß-catenin inhibitor, ICG001. The migratory capability of E156K-mutated CRYAA cells was significantly greater than that of WT cells (P < 0.001). This effect was accompanied by significantly increased expression levels of phosphorylated (p)-focal adhesion kinase (FAK) and p-Src. These changes were decreased significantly by treatment with FAK and Src inhibitors. Conclusion: E156K-mutated CRYAA induced EMT, in which the HLECs lost cell polarity, and acquired a mesenchymal phenotype with greater migratory capability. These biological effects may be associated with activation of the Wnt/ß-Catenin and FAK/Src signaling pathways.

High Mobility Emissive Excimer Organic Semiconductor Towards Color-Tunable Light-Emitting Transistors.

Organic light-emitting transistors (OLETs) are highly integrated and minimized optoelectronic devices with significant potential superiority in smart displays and optical communications. To realize these various applications, it is urgently needed for color-tunable emission in OLETs, but remains a great challenge as a result of the difficulty for designing organic semiconductors simultaneously integrating high carrier mobility, strong solid-state emission, and the ability for potential tunable colors. Herein, a high mobility emissive excimer organic semiconductor, 2,7-di(2-anthryl)-9H-fluorene (2,7-DAF) was reasonably designed by introducing a rotatable carbon-carbon single bond connecting two anthracene groups at the 2,7-sites of fluorene, and the small torsion angles simultaneously guarantee effective conjugation and suppress fluorescence quenching. Indeed, the unique stable dimer arrangement and herringbone packing mode of 2,7-DAF single crystal enables its superior integrated optoelectronic properties with high carrier mobility of 2.16 cm2 ⋅ V-1 ⋅ s-1 , and strong excimer emission with absolute photoluminescence quantum yield (PLQY) of 47.4 %. Furthermore, the voltage-dependent electrically induced color-tunable emission from orange to blue was also demonstrated for an individual 2,7-DAF single crystal based OLETs for the first time. This work opens the door for a new class of high mobility emissive excimer organic semiconductors, and provides a good platform for the study of color-tunable OLETs.

Adjusting the Electron-Withdrawing Ability of Acceptors in Thermally Activated Delayed Fluorescence Conjugated Polymers for High-Performance OLEDs.

Constructing high-performance solution-processed organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) conjugated polymers remains a challenging issue. The electron-withdrawing ability of acceptors in TADF units significantly affects the TADF properties of the conjugated polymers. Herein, we have designed three TADF conjugated polymers, in which phenoxazine donors and anthracen-9(10H)-one acceptors are incorporated into the polymeric backbones and side chains, respectively, and the carbazole derivative is copolymerized as the host. By incorporating different heteroatoms, such as nitrogen, oxygen, or sulfur, with slightly different electronegativities into anthracen-9(10H)-one, the effect of the electron-withdrawing ability of the acceptor on the performance of conjugated TADF polymer-based OLEDs is thus systematically studied. It is found that the introduction of a nitrogen atom can enhance the spin-orbital coupling and RISC process due to the modulated energy levels and nature of the excited states. As a result, the solution-processed OLEDs based on the prepared polymer p-PXZ-XN display an excellent comprehensive performance with an EQEmax of 17.6%, a low turn-on voltage of 2.8 V, and a maximum brightness of 14750 cd m-2. Notably, the efficiency roll-off is quite low, maintaining 15.1% at 1000 cd m-2, 12.1% at 3000 cd m-2, and 6.1% at 10000 cd m-2, which ranks in the first tier among the reported TADF conjugated polymers. This work provides a guideline for constructing high-efficiency TADF polymers.

Thermally Activated Delayed Fluorescence Emitters Based on a Special Tetrahedral Silane Core.

Based on the tetraphenylsilane skeleton, a new class of thermally activated delayed fluorescence (TADF) molecules have been designed and synthesized. Benefiting from the unique tetrahedron architecture of tetraphenylsilane, the intermolecular distance between TADF units can be enlarged and thus weakened the aggregation-induced quenching of triplet excitons. By adjusting the numbers of TADF subunits, the spin-orbit coupling processes can be controlled, leading to efficient up-conversion processes. The related OLEDs are fabricated through the solution processing technology, and pure-blue and green electroluminescence were observed with maximum external quantum efficiencies (EQEmax) of 6.6 and 13.8% as well as Commission Internationale de l'Eclairage coordinates of (0.14, 0.15) and (0.25, 0.45), respectively. This study provides a new idea for designing color-tunable TADF emitters through spatial structure regulation.

Design, Synthesis and Second-Order Nonlinear Optical Properties of Azobenzene-Based Polysiloxanes.

To study the effect of polymeric structures on second-order nonlinear optical properties, polysiloxanes materials based on azobenzene as chromophore have been designed and synthesized successfully. Herein, the siloxane monomer is directly bonded to azobenzene units by palladium catalysis, which avoids the influence of flexible chains on the photoelectric properties of azobenzene. According to the different positions of azobenzene units in the polymers, it is divided into side-chain, main-chain, and alternative-type polymers. The chemical structures of obtained polysiloxanes are confirmed by nuclear magnetic resonance spectra and mass spectra. Three polymers present high thermal decomposition temperatures and the medium glass transition temperatures. The effects of polymeric structures on the second-order nonlinear properties are compared. The main-chain polysiloxane possesses the highest thermal stability because of its rigid architecture. The side-chain polysiloxane shows the fastest isomerization transformation rate due to the large free volume. Besides, the alternative polysiloxane displays the best second-order nonlinear performance with second harmonic generation coefficient (d33 ) value of 47.6 pm V-1 , which is 3 times higher than the side-chain one.

Structural basis of white-tailed deer, Odocoileus virginianus, ACE2 recognizing all the SARS-CoV-2 variants of concern with high affinity.

SARS-CoV-2 has been expanding its host range, among which the white-tailed deer (WTD), Odocoileus virginianus, became the first wildlife species infected on a large scale and might serve as a host reservoir for variants of concern (VOCs) in case no longer circulating in humans. In this study, we comprehensively assessed the binding of the WTD angiotensin-converting enzyme 2 (ACE2) receptor to the spike (S) receptor-binding domains (RBDs) from the SARS-CoV-2 prototype (PT) strain and multiple variants. We found that WTD ACE2 could be broadly recognized by all of the tested RBDs. We further determined the complex structures of WTD ACE2 with PT, Omicron BA.1, and BA.4/5 S trimer. Detailed structural comparison revealed the important roles of RBD residues on 486, 498, and 501 sites for WTD ACE2 binding. This study deepens our understanding of the interspecies transmission mechanisms of SARS-CoV-2 and further addresses the importance of constant monitoring on SARS-CoV-2 infections in wild animals. IMPORTANCE Even if we manage to eliminate the virus among humans, it will still circulate among wildlife and continuously be transmitted back to humans. A recent study indicated that WTD may serve as reservoir for nearly extinct SARS-CoV-2 strains. Therefore, it is critical to evaluate the binding abilities of SARS-CoV-2 variants to the WTD ACE2 receptor and elucidate the molecular mechanisms of binding of the RBDs to assess the risk of spillback events.

Engineered Bacteria Labeled with Iridium(III) Photosensitizers for Enhanced Photodynamic Immunotherapy of Solid Tumors.

Despite metal-based photosensitizers showing great potential in photodynamic therapy for tumor treatment, the application of the photosensitizers is intrinsically limited by their poor cancer-targeting properties. Herein, we reported a metal-based photosensitizer-bacteria hybrid, Ir-HEcN, via covalent labeling of an iridium(III) photosensitizer to the surface of genetically engineered bacteria. Due to its intrinsic self-propelled motility and hypoxia tropism, Ir-HEcN selectively targets and penetrates deeply into tumor tissues. Importantly, Ir-HEcN is capable of inducing pyroptosis and immunogenic cell death of tumor cells under irradiation, thereby remarkably evoking anti-tumor innate and adaptive immune responses in vivo and leading to the regression of solid tumors via combinational photodynamic therapy and immunotherapy. To the best of our knowledge, Ir-HEcN is the first metal complex decorated bacteria for enhanced photodynamic immunotherapy.

A Nanobody-Bioorthogonal Catalyst Conjugate Triggers Spatially Confined Prodrug Activation for Combinational Chemo-immunotherapy.

Checkpoint inhibitors have been used with chemotherapy to improve antitumor efficacy. However, overcoming the immunosuppressive effect of chemotherapeutics remains a challenge. We report a nanobody-catalyst conjugate Ru-PD-L1 by fusing a ruthenium catalyst to an anti-PD-L1 nanobody. After administration of Ru-PD-L1 and a doxorubicin (DOX) prodrug, Ru-PD-L1 disrupts the PD-L1/PD-1 interaction and catalyzes the uncaging of the DOX prodrug. The spatially confined release of DOX reduces its systemic toxicity and leads to immunogenic cell death (ICD). The induced ICD triggers antitumor immune responses, which are further amplified by PD-L1 blockade to elicit synergistic chemo-immunotherapy, substantially increasing the number of tumor-infiltrating T-cells by 49.7% compared with the controls, thereby exhibiting high antitumor activity and low cytotoxicity in murine models. The combinational treatment could inhibit the growth of mice tumors by 67.7% compared to the control group. This combinational approach circumvents the negative immunogenic effects of chemotherapeutics and provides a potential chemo-immunotherapy strategy for human cancer treatment.

Structural basis for receptor binding and broader interspecies receptor recognition of currently circulating Omicron sub-variants.

Multiple SARS-CoV-2 Omicron sub-variants, such as BA.2, BA.2.12.1, BA.4, and BA.5, emerge one after another. BA.5 has become the dominant strain worldwide. Additionally, BA.2.75 is significantly increasing in some countries. Exploring their receptor binding and interspecies transmission risk is urgently needed. Herein, we examine the binding capacities of human and other 28 animal ACE2 orthologs covering nine orders towards S proteins of these sub-variants. The binding affinities between hACE2 and these sub-variants remain in the range as that of previous variants of concerns (VOCs) or interests (VOIs). Notably, R493Q reverse mutation enhances the bindings towards ACE2s from humans and many animals closely related to human life, suggesting an increased risk of cross-species transmission. Structures of S/hACE2 or RBD/hACE2 complexes for these sub-variants and BA.2 S binding to ACE2 of mouse, rat or golden hamster are determined to reveal the molecular basis for receptor binding and broader interspecies recognition.

A Genome-Wide Association Study for Susceptibility to Axial Length in Highly Myopic Eyes.

High myopia has long been highly prevalent worldwide with a largely yet unexplained genetic contribution. To identify novel susceptibility genes for axial length (AL) in highly myopic eyes, a genome-wide association study (GWAS) was performed using the genomic dataset of 350 deep whole-genome sequencing data from highly myopic patients. Top single nucleotide polymorphisms (SNPs) were functionally annotated. Immunofluorescence staining, quantitative polymerase chain reaction, and western blot were performed using neural retina of form-deprived myopic mice. Enrichment analyses were further performed. We identified the four top SNPs and found that ADAM Metallopeptidase With Thrombospondin Type 1 Motif 16 (ADAMTS16) and Phosphatidylinositol Glycan Anchor Biosynthesis Class Z (PIGZ) had the potential of clinical significance. Animal experiments confirmed that PIGZ expression could be observed and showed higher expression level in form-deprived mice, especially in the ganglion cell layer. The messenger RNA (mRNA) levels of both ADAMTS16 and PIGZ were significantly higher in the neural retina of form-deprived eyes (p = 0.005 and 0.007 respectively), and both proteins showed significantly upregulated expression in the neural retina of deprived eyes (p = 0.004 and 0.042, respectively). Enrichment analysis revealed a significant role of cellular adhesion and signal transduction in AL, and also several AL-related pathways including circadian entrainment and inflammatory mediator regulation of transient receptor potential channels were proposed. In conclusion, the current study identified four novel SNPs associated with AL in highly myopic eyes and confirmed that the expression of ADAMTS16 and PIGZ was significantly upregulated in neural retina of deprived eyes. Enrichment analyses provided novel insight into the etiology of high myopia and opened avenues for future research interest. Supplementary Information: The online version contains supplementary material available at 10.1007/s43657-022-00082-x.

Synthesis and Properties of Bipolar Ladder-Like Polysiloxane with Carbazole and Triphenylphosphine Oxygen Groups.

In this study, a series of ladder-like polysiloxanes are synthesized by introducing double-chain Si-O-Si polymer as the backbone and the carbazole and triphenylphosphine oxide with high triplet energy as side groups. The ladder-like structures of polysiloxanes are achieved through a controlled polymerization method that involves the monomer self-assembly and subsequent surface-restricted solid-phase in situ condensation through freeze-drying. The introduction of siloxane improves thermal stability of the polymers and inhibits the conjugation of the polymers between the side groups, leading to an increase in the triplet energy level. Therefore, all these polymers perform higher triplet energy levels than phosphorescent emitter (FIrpic). The cyclic voltammetry measurements demonstrate that the bipolar polymer exhibits a high highest occupied molecular orbital (HOMO) value of -5.32 eV, which is consistent with the work function of ITO/PEDOT:PSS, consequently facilitating hole injection. Furthermore, the incorporation of triphenylphosphine oxide promotes electron injection. Molecular simulations reveal that the frontier orbital distributions of the bipolar polymer are located on the carbazole and triphenylphosphine groups, respectively, which facilitate the transport of electrons and holes.

Regulating the Nature of Triplet Excited States of Thermally Activated Delayed Fluorescence Emitters.

ConspectusCharacterized by the reverse intersystem crossing (RISC) process from the triplet state (T1) to the singlet state (S1), thermally activated delayed fluorescence (TADF) emitters, which produce light by harvesting both triplet and singlet excitons without noble metals, are considered to be third-generation organic electroluminescent materials. Rapid advances in molecular design criteria, understanding the photophysics underlying TADF, and applications of TADF materials as emitters in organic light-emitting diodes (OLEDs) have been achieved. Theoretically, enhanced spin-orbit coupling (SOC) between singlet and triplet states can result in a fast RISC process and thus a high light-emitting efficiency according to Fermi's golden rule. Therefore, regulating the nature of triplet excited states by elaborate molecular design to improve SOC is an effective approach to high-efficiency TADF-based OLEDs. Generally, on one hand, the increased local excited (LE) populations of the excited triplet state can significantly improve the nature flips between S1 and T1. On other hand, the reduced energy gap between S1 and the lowest triplet with a charge transfer (CT) characteristic can also enhance their vibronic coupling. Consequently, it is vital to determine how to regulate the nature of triplet excited states by molecular design to guide the material synthesis, especially for polymeric emitters.In this Account, we focus on modulating the strategy of triplet excited states for TADF emitters and an in-depth understanding of the photophysical processes, leading to optimized OLED device performance. We include several kinds of strategies to control the nature of triplet excited states to guide the synthesis of small-molecule and polymer TADF emitters: (1) Modulating the electronic distribution of conjugated polymeric backbones by copolymerizing the electron-donating host: accordingly, the nature of excited states can be changed, especially for triplets. Meanwhile, the utilization of excitons can be systematically improved by adjusting the electronic structure of triplet states with long-range distribution in the conjugated polymeric backbones. (2) Halogenating acceptors of TADF units: the introduced halogen atoms would reestablish the electronic distribution of the triplet and relocate the hole orbits, resulting in a CT and LE hybrid nature of a triplet transformed into a LE-predominant state, which favors the RISC process. (3) Stereostructure regulation: by constructing a diverse arrangement of three-dimensional spatial configurations or conjugated architectures, the nature of the triplet can also be finely tuned, such as hyperbranched structures with multiple triplet-singlet vibration couplings, half-dendronized-half-encapsulated asymmetric systems, trinaphtho[3,3,3] propeller-based three-dimensional spatial interspersed structures, intramolecular close-packed donor-acceptor systems, and so on. We hope that this Account will provide insights into new structures and mechanisms for achieving high-performance OLEDs based on regulating the nature of triplet excited states.

Dissecting the features of TGA gene family in Saccharum and the functions of ScTGA1 under biotic stresses.

Sugarcane is an important sugar and energy crop and smut disease caused by Sporisorium scitamineum is a major fungal disease which can seriously reduce the yield and quality of sugarcane. In plants, TGACG motif binding (TGA) transcription factors are involved in the regulation of salicylic acid (SA) and methyl jasmonate (MeJA) signaling pathways, as well as in response to various biotic and abiotic stresses. However, no TGA-related transcription factor has been reported in Saccharum. In the present study, 44 SsTGA genes were identified from Saccharum spontaneum, and were assorted into three clades (I, II, III). Cis-regulatory elements (CREs) analysis revealed that SsTGA genes may be involved in hormone and stress response. RNA-seq data and RT-qPCR analysis indicated that SsTGAs were constitutively expressed in different tissues and induced by S. scitamineum stress. In addition, a ScTGA1 gene (GenBank accession number ON416997) was cloned from the sugarcane cultivar ROC22, which was homologous to SsTGA1e in S. spontaneum and encoded a nucleus protein. It was constitutively expressed in sugarcane tissues and up-regulated by SA, MeJA and S. scitamineum stresses. Furthermore, transient overexpression of ScTGA1 in Nicotiana benthamiana could enhance its resistance to the infection of Ralstonia solanacearum and Fusarium solani var. coeruleum, by regulating the expression of immune genes related to hypersensitive response (HR), ethylene (ET), SA and jasmonic acid (JA) pathways. This study should contribute to our understanding on the evolution and function of the SsTGA gene family in Saccharum, and provide a basis for the functional identification of ScTGA1 under biotic stresses.

Near-atomic architecture of Singapore grouper iridovirus and implications for giant virus assembly.

Singapore grouper iridovirus (SGIV), one of the nucleocytoviricota viruses (NCVs), is a highly pathogenic iridovirid. SGIV infection results in massive economic losses to the aquaculture industry and significantly threatens global biodiversity. In recent years, high morbidity and mortality in aquatic animals have been caused by iridovirid infections worldwide. Effective control and prevention strategies are urgently needed. Here, we present a near-atomic architecture of the SGIV capsid and identify eight types of capsid proteins. The viral inner membrane-integrated anchor protein colocalizes with the endoplasmic reticulum (ER), supporting the hypothesis that the biogenesis of the inner membrane is associated with the ER. Additionally, immunofluorescence assays indicate minor capsid proteins (mCPs) could form various building blocks with major capsid proteins (MCPs) before the formation of a viral factory (VF). These results expand our understanding of the capsid assembly of NCVs and provide more targets for vaccine and drug design to fight iridovirid infections.

Hyperbranched Conjugated Polymer with Multiple Charge Transfer Enables High-Efficiency Nondoped Red Electroluminescence with Low Driving Voltage.

Conjugated polymers featuring thermally activated delayed fluorescence (TADF) attract tremendous attention in both academic and industry communities due to their easy solution processing for fabricating large-area and low-cost high-performance polymer light-emitting diodes (PLEDs). However, current nondoped solution-processed PLEDs frequently encounter significant efficiency roll-offs and unreasonably high operating voltages at high brightness, especially for red-emitting polymers. Herein, we design hyperbranched conjugated polymers (HCPs) with D-A-D type TADF characteristics for high-performance red-emitting PLEDs. Multiple intramolecular charge transfer (ICT) channels induced by quasi-equivalent donors of the TADF core strongly boost the reverse intersystem crossing (RISC) process and singlet excitons radiative transition. Coupling with the efficient energy transfer process generated by structure advantages of HCPs, the strongly electron-withdrawing oxygen atoms located on the TADF cores further accelerate hole transportation from the host chains to the TADF cores. Under a rational regulation of the TADF core ratio, the related nondoped red-emitting device performs an outstanding performance with an EQEmax of 8.39% and exhibits no roll-off while the luminance is less than 100 cd/m2 and only 3.3% decrease at 500 cd/m2. Simultaneously, the EQE can maintain 7.4% under 1000 cd/m2. Furthermore, the corresponding nondoped device exhibits a low turn-on voltage of around 2.5 V and achieves a luminance of 500 cd/m2 at 3.5 V and even 1000 cd/m2 at 3.9 V. To our knowledge, this is the best performance among all nondoped red PLEDs with high brightness obtained at low operating voltage.