Integrated Manipulation and Addressing of Spin Defect in Diamond.

Scalable and addressable integrated manipulation of qubits is crucial for practical quantum information applications. Different waveguides have been used to transport the optical and electrical driving pulses, which are usually required for qubit manipulation. However, the separated multifields may limit the compactness and efficiency of manipulation and introduce unwanted perturbation. Here, we develop a tapered fiber-nanowire-electrode hybrid structure to realize integrated optical and microwave manipulation of solid-state spins at nanoscale. Visible light and microwave driving pulses are simultaneously transported and concentrated along an Ag nanowire. Studied with spin defects in diamond, the results show that the different driving fields are aligned with high accuracy. The spatially selective spin manipulation is realized. And the frequency-scanning optically detected magnetic resonance (ODMR) of spin qubits is measured, illustrating the potential for portable quantum sensing. Our work provides a new scheme for developing compact, miniaturized quantum sensors and quantum information processing devices.

Characterization and evaluation of an oral vaccine via nano-carrier for surface immunogenic protein (Sip) delivery against Streptococcus agalactiae infection.

Streptococcus agalactiae causes systemic disease in a variety of wild and farmed fish, resulting in high levels of morbidity and mortality, as well as serious economic losses to the Nile tilapia aquaculture industry. The development of economic and applicable oral vaccines is therefore urgently needed for the sustainable development of Nile tilapia aquaculture. In this study, mesoporous silica nanoparticles (MSNs) were fabricated using sol-gel synthesis technology, and the antigens of surface immunogenic protein (Sip) was loaded into MSNs to develop a nanovaccine MSNs-Sip@HP55. The results showed that the prepared nanovaccine exhibited pH-controlled release, which could survive in the simulated gastric environment (pH 1.5), and release antigens in the simulated intestinal environment at pH 7.4. The nanovaccine could induce innate and adaptive immune responses in Nile tilapia. When the challenge doses were 1.5 × 106, 1.18 × 106, and 0.88 × 106 CFU/mL, the relative protection rates in immunized Nile tilapia were 63.33 %, 64.23 %, and 76.31 %, respectively. Taken together, the nanovaccine exhibited a high antigen utilization rate and was easily administered orally via feeding, which could protect Nile tilapia against challenge with S. agalactiae in large-scale farms. Oral vaccine based on MSNs carriers is a potentially promising strategy for the development of fish vaccines.

Ultrathin quantum light source with van der Waals NbOCl2 crystal.

Interlayer electronic coupling in two-dimensional materials enables tunable and emergent properties by stacking engineering. However, it also results in significant evolution of electronic structures and attenuation of excitonic effects in two-dimensional semiconductors as exemplified by quickly degrading excitonic photoluminescence and optical nonlinearities in transition metal dichalcogenides when monolayers are stacked into van der Waals structures. Here we report a van der Waals crystal, niobium oxide dichloride (NbOCl2), featuring vanishing interlayer electronic coupling and monolayer-like excitonic behaviour in the bulk form, along with a scalable second-harmonic generation intensity of up to three orders higher than that in monolayer WS2. Notably, the strong second-order nonlinearity enables correlated parametric photon pair generation, through a spontaneous parametric down-conversion (SPDC) process, in flakes as thin as about 46 nm. To our knowledge, this is the first SPDC source unambiguously demonstrated in two-dimensional layered materials, and the thinnest SPDC source ever reported. Our work opens an avenue towards developing van der Waals material-based ultracompact on-chip SPDC sources as well as high-performance photon modulators in both classical and quantum optical technologies1-4.

Mechanism of regulation of the Helicobacter pylori Cagß ATPase by CagZ.

The transport of the CagA effector into gastric epithelial cells by the Cag Type IV secretion system (Cag T4SS) of Helicobacter pylori (H. pylori) is critical for pathogenesis. CagA is recruited to Cag T4SS by the Cagß ATPase. CagZ, a unique protein in H. pylori, regulates Cagß-mediated CagA transport, but the underlying mechanisms remain unclear. Here we report the crystal structure of the cytosolic region of Cagß, showing a typical ring-like hexameric assembly. The central channel of the ring is narrow, suggesting that CagA must unfold for transport through the channel. Our structure of CagZ in complex with the all-alpha domain (AAD) of Cagß shows that CagZ adopts an overall U-shape and tightly embraces Cagß. This binding mode of CagZ is incompatible with the formation of the Cagß hexamer essential for the ATPase activity. CagZ therefore inhibits Cagß by trapping it in the monomeric state. Based on these findings, we propose a refined model for the transport of CagA by Cagß.

Sevoflurane protects against intracerebral hemorrhage via microRNA-133b/FOXO4/BCL2 axis.

The application of Sevoflurane (Sev) in neurological diseases has been documented. We herein clarified the role of Sev in intracerebral hemorrhage (ICH). Through bioinformatics analysis, ICH-related microRNA (miRNA) was collected with microRNA-133b (miR-133b) chosen for the study subject. Then, the related downstream gene Forkhead box O4 (FOXO4) was identified. For in vivo assays, an ICH mouse model was established by autologous blood injection. For in vitro assays, hippocampal neurons were extracted from mouse brain tissues, and erythrocyte lysates were employed to simulate in vitro hemorrhage. Interaction between miR-133b and FOXO4 as well as between FOXO4 and BCL2 were assayed. We found decreased miR-133b in the brain tissue of ICH mice and erythrocyte lysate-treated hippocampal neurons. Sev treatment attenuated ICH and hippocampal neuronal apoptosis in mice by upregulating miR-133b. miR-133b targeted FOXO4 expression, and inhibition of FOXO4 attenuated hippocampal neuronal apoptosis by increasing BCL2 expression. Sev attenuated ICH in mice by increasing BCL2 expression through regulation of miR-133b-mediated FOXO4 expression. The findings highlighted the protective effect of Sev on ICH mice through the regulation of miR-133b-mediated FOXO4 expression.

Structural Characteristics of Polysaccharide GP2a in Gardenia jasminoides and Its Immunomodulatory Effect on Macrophages.

Here, we elucidated the structural characteristics of a polysaccharide isolated from Gardenia jasminoides Ellis (labeled as GP2a) and its immunomodulatory activity. GP2a is an acidic polysaccharide with a molecular weight of 44.8 kDa, mostly comprising galacturonic acid. Methylation analysis revealed 4-GalpA (74.8%) to be the major sugar residue in GP2a. Nuclear magnetic resonance analysis indicated that its main chain comprised →4)-α-D-GalpA-6-OMe-(1→4)-α-D-GalpA-(1→ and →4)-α-D-GalpA-6-OMe-(1→2)-α-L-Rhap-(1→, with galactan and arabinans linked to the C-4 position of →2)-α-L-Rhap-(1→ residue as branched chains. Furthermore, GP2a showed no obvious toxicity to macrophages (RAW 264.7) while enhancing cell viability in a dose- and time-dependent manner. Compared with untreated cells, nitric oxide production and secretion of cytokines, such as tumor necrosis factor-α, interferon-γ, interleukin (IL)-1ß, IL-6, and granulocyte macrophage colony stimulating factor, in GP2a-treated cells significantly increased after 48 h. At 300 µg/mL GP2a concentration, there was no significant difference in the cytokine levels in GP2a- and lipopolysaccharide-treated cells (the positive control). In summary, GP2a is a pectic polysaccharide with homogalacturonan and rhamnogalacturonan-I structural regions in the main chain. Based on its immunomodulatory effects in vitro, GP2a may have potential uses in functional food and medicine.

Structural insights into the CP312R protein of the African swine fever virus.

African swine fever (ASF) is a lethal hemorrhagic disease that affects domestic pigs and wild boars. There is no medication available for ASF to date. The ability to mount antigen-specific responses to viral vectored CP312R makes it a crucial potential target for designing vaccines or drugs. This study determined the crystal structure of ASFV CP312R at 2.32 Å and found it to be a monomer with a single-stranded DNA binding core domain with a clear five-strands ß-barrel OB-fold architecture. Electrophoretic mobility shift assay and size-exclusion chromatography characterization assay further confirmed the single-stranded DNA (ssDNA)-binding property of ASFV CP312R. This study revealed the structure and preliminary ssDNA interaction mechanisms of ASFV CP312R, providing new clues for developing new antiviral strategies.

Crystal Structure of the Disease-Specific Protein of Rice Stripe Virus.

The rice stripe virus (RSV) is responsible for devastating effects in East Asian rice-producing areas. The disease-specific protein (SP) level in rice plants determines the severity of RSV symptoms. Isothermal titration calorimetry (ITC) and bimolecular fluorescence complementation (BiFC) assays confirmed the interaction between an R3H domain-containing host factor, OsR3H3, and RSV SP in vitro and in vivo. This study determined the crystal structure of SP at 1.71 Å. It is a monomer with a clear shallow groove to accommodate host factors. Docking OsR3H3 into the groove generates an SP/OsR3H3 complex, which provides insights into the protein-binding mechanism of SP. Furthermore, SP's protein-binding properties and model-defined recognition residues were assessed using mutagenesis, ITC, and BiFC assays. This study revealed the structure and preliminary protein interaction mechanisms of RSV SP, shedding light on the molecular mechanism underlying the development of RSV infection symptoms.

Near-Field Modulation of Differently Oriented Single Photon Emitters with A Plasmonic Probe.

Single photon emitters (SPEs) are critical components of photon-based quantum technology. Recently, the interaction between surface plasmons and emitters has attracted increasing attention because of its potential to improve the quality of single-photon sources through stronger light-matter interactions. In this work, we use a hybrid plasmonic probe composed of a fiber taper and silver nanowire to controllably modulate the radiation properties of SPEs with differently oriented polarization. For out-of-plane oriented SPEs such as single CdSe quantum dots, the radiation lifetime could be reduced by a factor as large as seven; for in-plane oriented SPEs such as hBN defect SPEs, the average modulation amplitude varied from 0.69 to 1.23, depending on the position of the probe. The experimental results were highly consistent with the simulations and theory. This work provides an efficient approach for optimizing the properties of SPEs for quantum photonic integration.

Structural insight into African swine fever virus I73R protein reveals it as a Z-DNA binding protein.

African Swine Fever (ASF) is a highly contagious viral haemorrhagic disease of swine, leading to enormous economic losses in the swine industry. However, vaccines and drugs to treat ASF have yet to be developed. African swine fever virus (ASFV) encodes more than 150 proteins, but 50% of them have unknown functions. Here, we present the crystal structure of the ASFV I73R protein at a resolution of 2.0 Å. Similar search tools based solely on amino acid sequence shows that it has no relationships to any proteins of known function. Interestingly, the overall structure of the I73R protein shares a winged helix-turn-helix fold, structural similarity with the Z-DNA binding domain (Zα). In accordance with this result, the I73R is capable of binding to a CpG repeats DNA duplex, which has a high propensity for forming Z-DNA during the DNA binding assays. In addition, the I73R protein was shown to be expressed at both early and late stages of ASFV post-infection in PAM cells as an 8.9 kDa protein. Immunofluorescence studies revealed that the I73R protein is expressed in the nucleus at early times post-infection and gradually translocated from the nucleus to the cytoplasm. Taken together, these data indicate that the I73R could be a member of Zα family that is important in host-pathogen interaction, which paves the way for the design of inhibitors to target this severe pathogen. Further exploring the biological role of I73R during ASFV infection in vitro and in vivo will provide new clues for development of new antiviral strategies.

Structure-guided rational design of the Geobacillus thermoglucosidasius feruloyl esterase GthFAE to improve its thermostability.

Feruloyl esterases are indispensable biocatalysts catalyzing the cleavage of ester bonds between polysaccharides and their hydroxycinnamoyl cross-links. GthFAE from Geobacillus thermoglucosidasius was identified as a thermophilic alkaline feruloyl esterase with potential applications in paper manufacturing. To improve the enzymatic properties rationally and efficiently, the structure of GthFAE was solved at 1.9 Å, revealing a core domain of classical α/ß hydrolase fold and an inserted α/ß cap domain. In silico analysis based on it helped us to investigate whether the residues at the active center have positive effects on the stability, and how. Several site-directed mutations were conducted, of which substitutions at residues T41 and T150 apparently improved the thermostability. The combination mutant T41N/T150R exhibited an optimal temperature of 65 °C, a 6.4 °C higher Tm compared to wild type by 80 °C, and a 35-fold longer in half-life (201 min) at 70 °C. Molecular dynamics simulations further illustrated that the structure of T41N/T150R was more stable than the wild type and T150R stabilized the cap domain by introducing salt bridges to the region with E154 and D164. This study not only highlighted residues within the active center on their thermostability improving effects, but also contributed to the prospective industrial application of GthFAE.

The 14-3-3 protein GF14c positively regulates immunity by modulating the protein homoeostasis of the GRAS protein OsSCL7 in rice.

Various types of transcription factors have been reported to be involved in plant-pathogen interactions by regulating defence-related genes. GRAS proteins, plant- specific transcription factors, have been shown to play essential roles in plant growth, development and stress responses. By performing a transcriptome study on rice early defence responses to Magnaporthe oryzae, we identified a GRAS protein, OsSCL7, which was induced by M. oryzae infection. We characterized the function of OsSCL7 in rice disease resistance. OsSCL7 was upregulated upon exposure to M. oryzae and pathogen-associated molecular pattern treatments, and knocking out OsSCL7 resulted in decreased disease resistance of rice to M. oryzae. In contrast, overexpression of OsSCL7 could improve rice disease resistance to M. oryzae. OsSCL7 was mainly localized in the nucleus and showed transcriptional activity. OsSCL7 can interact with GF14c, a 14-3-3 protein, and loss-of-function GF14c leads to enhanced susceptibility to M. oryzae. Additionally, OsSCL7 protein levels were reduced in the gf14c mutant and knocking out OsSCL7 affected the expression of a series of defence-related genes. Taken together, these findings uncover the important roles of OsSCL7 and GF14c in plant immunity and a potential mechanism by which plants fine-tune immunity by regulating the protein stability of a GRAS protein via a 14-3-3 protein.

Strongly Enhanced Second Harmonic Generation in a Thin Film Lithium Niobate Heterostructure Cavity.

Boosting second-order optical nonlinear frequency conversion over subwavelength thickness has long been pursued through optical resonance in micro- and nanophotonics. However, the availability of thin film materials with high second-order nonlinearity is limited to III-V semiconductors, which have low transparency in the visible. Here, we experimentally demonstrated strongly enhanced second harmonic generation in one-dimensional heterostructure cavities on thin film lithium niobate. A guided-mode resonance resonator and distributed Bragg reflectors are combined for both efficient coupling and electromagnetic field localization. Over 1200 times second harmonic generation enhancement is experimentally realized compared with flat thin film lithium niobate through optimizing the trade-off between quality factor and mode volume, leading to a record high normalized conversion efficiency of 2.03×10^{-5} cm^{2}/GW under 1.92 MW/cm^{2} pump intensity. Our approach could inspire the miniaturization and integration of compact resonant nonlinear photonic devices on thin film lithium niobate.

pH-Controlled Release of Antigens Using Mesoporous Silica Nanoparticles Delivery System for Developing a Fish Oral Vaccine.

The development of effective vaccines and delivery systems in aquaculture is a long-term challenge for controlling emerging and reemerging infections. Cost-efficient and advanced nanoparticle vaccines are of tremendous applicability in prevention of infectious diseases of fish. In this study, dihydrolipoamide dehydrogenase (DLDH) antigens of Vibrio alginolyticus were loaded into mesoporous silica nanoparticles (MSN) to compose the vaccine delivery system. Hydroxypropyl methylcellulose phthalate (HP55) was coated to provide protection of immunogen. The morphology, loading capacity, acid-base triggered release were characterized and the toxicity of nanoparticle vaccine was determined in vitro. Further, the vaccine immune effects were evaluated in large yellow croaker via oral administration. In vitro studies confirmed that the antigen could be stable in enzymes-rich artificial gastric fluid and released under artificial intestinal fluid environment. In vitro cytotoxicity assessment demonstrated the vaccines within 120 µg/ml have good biocompatibility for large yellow croaker kidney cells. Our data confirmed that the nanoparticle vaccine in vivo could elicit innate and adaptive immune response, and provide good protection against Vibrio alginolyticus challenge. The MSN delivery system prepared may be a potential candidate carrier for fish vaccine via oral administration feeding. Further, we provide theoretical basis for developing convenient, high-performance, and cost-efficient vaccine against infectious diseases in aquaculture.

Early immune response in large yellow croaker (Larimichthys crocea) after immunization with oral vaccine.

Mesoporous silica nanoparticles (MSNs) have been used in the field of biomedicine as antigen carriers and adjuvants for protective antigens. In the present study, an oral nanovaccine against Vibrio alginolyticus was prepared employing MSNs as carriers. The uptake of the dihydrolipoamide dehydrogenase (DLDH) antigens in the intestine of large yellow croaker was evaluated using an immunohistochemistry assay. Additionally, the effects of the nanovaccine on the early immune response in large yellow croaker were investigated via oral vaccination. The presence of the antigens was detected in the mucosa and lamina propria of the foregut, midgut, and hindgut of large yellow croaker at 3 h following oral immunization. The expression levels of cytokines (i.e., lysozyme, IFN-γ, IFITM, TNF-α, IL-1ß, IL-2, IL-4, IL-10, and IL-13) in the intestine, spleen, and head kidney tissues of large yellow croaker before and after the immune challenge were determined via RT-qPCR assay. The obtained results revealed that the expression levels of lysozyme, IFN-γ, IFITM, TNF-α, IL-1ß, IL-2, IL-4, IL-10, and IL-13 in the intestine and head kidney of the vaccinated large yellow croaker, as well as the expression of lysozyme, IL-1ß, and IL-10 in the spleen, exhibited time-dependent oscillation regulation patterns. Notably, the nanovaccine immunization could induce early (6 h) and high expression of IFN-γ in the spleen and kidney tissues after the bacterial infection. The current study supplements the available data on the early immune response to fish nanovaccines. It also provides a valuable theoretical basis for the future development of large yellow croaker oral vaccines.

Structural Insights into a Novel Esterase from the East Pacific Rise and Its Improved Thermostability by a Semirational Design.

Lipolytic enzymes are essential biocatalysts in food processing as well as pharmaceutical and pesticide industries, catalyzing the cleavage of ester bonds in a variety of acyl chain substrates. Here, we report the crystal structure of an esterase from the deep-sea hydrothermal vent of the East Pacific Rise (EprEst). The X-ray structure of EprEst in complex with the ligand, acetate, has been determined at 2.03 Å resolution. The structure reveals a unique spatial arrangement and orientation of the helix cap domain and α/ß hydrolase domain, which form a substrate pocket with preference for short-chain acyl groups. Molecular docking analysis further demonstrated that the active site pocket could accommodate p-nitrophenyl (pNP) carboxyl ligands of varying lengths (≤6 C atoms), with pNP-butyrate ester predicted to have the highest binding affinity. Additionally, the semirational design was conducted to improve the thermostability of EprEst by enzyme engineering based on the established structure and multiple sequence alignment. A mutation, K114P, introduced in the hinge region of the esterase, which displayed increased thermostability and enzyme activity. Collectively, the structural and functional data obtained herein could be used as basis for further protein engineering to ultimately expand the scope of industrial applications of marine-derived lipolytic enzymes.

The crystal structure of Arabidopsis BON1 provides insights into the copine protein family.

The Arabidopsis thaliana BON1 gene product is a member of the evolutionary conserved eukaryotic calcium-dependent membrane-binding protein family. The copine protein is composed of two C2 domains (C2A and C2B) followed by a vWA domain. The BON1 protein is localized on the plasma membrane, and is known to suppress the expression of immune receptor genes and to positively regulate stomatal closure. The first structure of this protein family has been determined to 2.5-Å resolution and shows the structural features of the three conserved domains C2A, C2B and vWA. The structure reveals the third Ca2+ -binding region in C2A domain is longer than classical C2 domains and a novel Ca2+ binding site in the vWA domain. The structure of BON1 bound to Mn2+ is also presented. The binding of the C2 domains to phospholipid (PSF) has been modeled and provides an insight into the lipid-binding mechanism of the copine proteins. Furthermore, the selectivity of the separate C2A and C2B domains and intact BON1 to bind to different phospholipids has been investigated, and we demonstrated that BON1 could mediate aggregation of liposomes in response to Ca2+ . These studies have formed the basis of further investigations into the important role that the copine proteins play in vivo.

Ca2+-based allosteric switches and shape shifting in RGLG1 VWA domain.

RGLG1 is an E3 ubiquitin ligase in Arabidopsis thaliana that participates in ABA signaling and regulates apical dominance. Here, we present crystal structures of RGLG1 VWA domain, revealing two novel calcium ions binding sites (NCBS1 and NCBS2). Furthermore, the structures with guided mutagenesis in NCBS1 prove that Ca2+ ions play important roles in controlling conformational change of VWA, which is stabilized in open state with Ca2+ bound and converted to closed state after Ca2+ removal. This allosteric regulation mechanism is distinct from the ever reported one involving the C-terminal helix in integrin α and ß I domains. The mutation of a key residue in NCBS2 do not abolish its Ca2+-binding potential, with no conformational change. MD simulations reveals that open state of RGLG1 VWA has higher ligand affinity than its closed state, consisting with integrin. Structural comparison of ion-free-MIDAS with Mg2+-MIDAS reveals that Mg2+ binding to MIDAS does not induce conformational change. With acquisition of first structure of plant VWA domain in both open state and closed state, we carefully analyze the conformational change and propose a totally new paradigm for its transition of open-closed states, which will be of great value for guiding future researches on VWA proteins and their important biological significance.

The crystal structure of the TCP domain of PCF6 in Oryza sativa L. reveals an RHH-like fold.

The Teosinte branched 1/Cycloidea/Proliferating cell factor (TCP) domain is an evolutionarily conserved DNA binding domain unique to the plant kingdom. To date, the functions of TCPs have been well studied, but the three-dimensional structure of the TCP domain is lacking. Here, we have determined the crystal structure of the TCP domain from OsPCF6. The structure reveals that the TCP domain adopts three short ß-strands followed by a helix-loop-helix structure, distinct from the canonical basic helix-loop-helix structure. This folded domain shows high structural similarity to the ribbon-helix-helix (RHH) transcriptional repressors, a family of DNA binding proteins with a conserved 3D structural motif (RHH fold), indicating that TCPs could be reclassified as RHH proteins. Our work will provide insight toward a better understanding of the mechanisms underlying TCP protein function.

Label-free multiphoton imaging of ß-amyloid plaques in Alzheimer's disease mouse models.

ß -Amyloid ( A ß ) plaque, representing the progressive accumulation of the protein that mainly consists of A ß , is one of the prominent pathological hallmarks of Alzheimer's disease (AD). Label-free imaging of A ß plaques holds the potential to be a histological examination tool for diagnosing AD. We applied label-free multiphoton microscopy to identify extracellular A ß plaque as well as intracellular A ß accumulation for the first time from AD mouse models. We showed that a two-photon-excited fluorescence signal is a sensitive optical marker for revealing the spatial-temporal progression and the surrounding morphological changes of A ß deposition, which demonstrated that both extracellular and intracellular A ß accumulations play an important role in the progression of AD. Moreover, combined with a custom-developed image-processing program, we established a rapid method to visualize different degrees of A ß deposition by color coding. These results provide an approach for investigating pathophysiology of AD that can complement traditional biomedical procedures.