Spliceosome component PHD finger 5A is essential for early B lymphopoiesis.

The spliceosome, a multi-megadalton ribonucleoprotein complex, is essential for pre-mRNA splicing in the nucleus and ensuring genomic stability. Its precise and dynamic assembly is pivotal for its function. Spliceosome malfunctions can lead to developmental abnormalities and potentially contribute to tumorigenesis. The specific role of the spliceosome in B cell development is poorly understood. Here, we reveal that the spliceosomal U2 snRNP component PHD finger protein 5A (Phf5a) is vital for early B cell development. Loss of Phf5a results in pronounced defects in B cell development, causing an arrest at the transition from pre-pro-B to early pro-B cell stage in the bone marrow of mutant mice. Phf5a-deficient B cells exhibit impaired immunoglobulin heavy (IgH) chain expression due to defective V-to-DJ gene rearrangement. Mechanistically, our findings suggest that Phf5a facilitates IgH gene rearrangement by regulating the activity of recombination-activating gene endonuclease and influencing chromatin interactions at the Igh locus.

Diamond surface functionalization via visible light-driven C-H activation for nanoscale quantum sensing.

Nitrogen-vacancy (NV) centers in diamond are a promising platform for nanoscale NMR sensing. Despite significant progress toward using NV centers to detect and localize nuclear spins down to the single spin level, NV-based spectroscopy of individual, intact, arbitrary target molecules remains elusive. Such sensing requires that target molecules are immobilized within nanometers of NV centers with long spin coherence. The inert nature of diamond typically requires harsh functionalization techniques such as thermal annealing or plasma processing, limiting the scope of functional groups that can be attached to the surface. Solution-phase chemical methods can be readily generalized to install diverse functional groups, but they have not been widely explored for single-crystal diamond surfaces. Moreover, realizing shallow NV centers with long spin coherence times requires highly ordered single-crystal surfaces, and solution-phase functionalization has not yet been shown with such demanding conditions. In this work, we report a versatile strategy to directly functionalize C-H bonds on single-crystal diamond surfaces under ambient conditions using visible light, forming C-F, C-Cl, C-S, and C-N bonds at the surface. This method is compatible with NV centers within 10 nm of the surface with spin coherence times comparable to the state of the art. As a proof-of-principle demonstration, we use shallow ensembles of NV centers to detect nuclear spins from surface-bound functional groups. Our approach to surface functionalization opens the door to deploying NV centers as a tool for chemical sensing and single-molecule spectroscopy.

Electron doping of a double-perovskite flat-band system.

Electronic structure calculations indicate that the Sr2FeSbO6 double perovskite has a flat-band set just above the Fermi level that includes contributions from ordinary subbands with weak kinetic electron hopping plus a flat subband that can be attributed to the lattice geometry and orbital interference. To place the Fermi energy in that flat band, electron-doped samples with formulas Sr2-xLaxFeSbO6 (0 ≤ x ≤ 0.3) were synthesized, and their magnetism and ambient temperature crystal structures were determined by high-resolution synchrotron X-ray powder diffraction. All materials appear to display an antiferromagnetic-like maximum in the magnetic susceptibility, but the dominant spin coupling evolves from antiferromagnetic to ferromagnetic on electron doping. Which of the three subbands or combinations is responsible for the behavior has not been determined.

Evidence of magnetism-induced topological protection in the axion insulator candidate EuSn2P2.

We unravel the interplay of topological properties and the layered (anti)ferromagnetic ordering in EuSn2P2, using spin and chemical selective electron and X-ray spectroscopies supported by first-principle calculations. We reveal the presence of in-plane long-range ferromagnetic order triggering topological invariants and resulting in the multiple protection of topological Dirac states. We provide clear evidence that layer-dependent spin-momentum locking coexists with ferromagnetism in this material, a cohabitation that promotes EuSn2P2 as a prime candidate axion insulator for topological antiferromagnetic spintronics applications.

ATM-mediated double-strand break repair is required for meiotic genome stability at high temperature.

In eukaryotes, meiotic recombination maintains genome stability and creates genetic diversity. The conserved Ataxia-Telangiectasia Mutated (ATM) kinase regulates multiple processes in meiotic homologous recombination, including DNA double-strand break (DSB) formation and repair, synaptonemal complex organization, and crossover formation and distribution. However, its function in plant meiotic recombination under stressful environmental conditions remains poorly understood. In this study, we demonstrate that ATM is required for the maintenance of meiotic genome stability under heat stress in Arabidopsis thaliana. Using cytogenetic approaches we determined that ATM does not mediate reduced DSB formation but does ensure successful DSB repair, and thus meiotic chromosome integrity, under heat stress. Further genetic analysis suggested that ATM mediates DSB repair at high temperature by acting downstream of the MRE11-RAD50-NBS1 (MRN) complex, and acts in a RAD51-independent but chromosome axis-dependent manner. This study extends our understanding on the role of ATM in DSB repair and the protection of genome stability in plants under high temperature stress.

Anti-noise UWFBG-array enhanced DAS system using double-pulse-based time-domain adaptive delay interference: publisher's note.

This publisher's note contains a correction to Opt. Lett.48, 1814 (2023)10.1364/OL.486149.

Elucidating the Electronic Nature of Rh-based Paddlewheel Catalysts from 103 Rh NMR Chemical Shifts: Insights from Quantum Mechanical Calculations.

The tremendous importance of dirhodium paddlewheel complexes for asymmetric catalysis is largely the result of an empirical optimization of the chiral ligand sphere about the bimetallic core. It was only recently that a H(C)Rh triple resonance 103 Rh NMR experiment provided the long-awaited opportunity to examine - with previously inconceivable accuracy - how variation of the ligands impacts on the electronic structure of such catalysts. The recorded effects are dramatic: formal replacement of only one out of eight O-atoms surrounding the metal centers in a dirhodium tetracarboxylate by an N-atom results in a shielding of the corresponding Rh-site of no less than 1000 ppm. The current paper provides the theoretical framework that allows this and related experimental observations made with a set of 19 representative rhodium complexes to be interpreted. In line with symmetry considerations, it is shown that the shielding tensor responds only to the donor ability of the equatorial ligands along the perpendicular principal axis. Axial ligands, in contrast, have no direct effect on shielding but may come into play via the electronic c i s ${cis}$ -effect that they exert onto the neighboring equatorial sites. On top of these fundamental interactions, charge redistribution within the core as well as the electronic t r a n s ${trans}$ -effect of ligands of different donor strengths is reflected in the recorded 103 Rh NMR shifts.

Dual Role of a Novel Heteroleptic Cu(I) Complex in Visible-Light-Driven CO2 Reduction.

A novel mononuclear Cu(I) complex was synthesized via coordination with a benzoquinoxalin-2'-one-1,2,3-triazole chelating diimine and the bis[(2-diphenylphosphino)phenyl] ether (DPEPhos), to target a new and efficient photosensitizer for photocatalytic CO2 reduction. The Cu(I) complex absorbs in the blue-green region of the visible spectrum, with a broad band having a maximum at 475 nm (ϵ =4500 M-1 cm-1), which is assigned to the metal-to-ligand charge transfer (MLCT) transition from the Cu(I) to the benzoquinoxalin-2'-one moiety of the diimine. Surprisingly, photo-driven experiments for the CO2 reduction showed that this complex can undergo a photoinduced electron transfer with a sacrificial electron donor and accumulate electrons on the diimine backbone. Photo-driven experiments in a CO2 atmosphere revealed that this complex can not only act as a photosensitizer, when combined with an Fe(III)-porphyrin, but can also selectively produce CO from CO2. Thus, owing to its charge-accumulation properties, the non-innocent benzoquinoxalin-2-one based ligand enabled the development of the first copper(I)-based photocatalyst for CO2 reduction.

Crystallographic Disorder and Strong Magnetic Anisotropy in Dy3Pt2Sb4.48.

We report the crystal growth and characterization of a rare-earth-containing material, Dy3.00(1)Pt2Sb4.48(2). This compound possesses a similar structure to the previously reported Y3Pt4Ge6, but it lacks two layers of Pt atoms. Crystallographic disorder was found in Dy3.00(1)Pt2Sb4.48(2). Additionally, the Dy-Dy framework was found to have both square net and triangular lattices. Dy3.00(1)Pt2Sb4.48(2)8 was determined to be antiferromagnetically ordered around ∼15 K while a competing antiferromagnetic sublattice also exists at lower temperature. Strong magnetic anisotropy was observed, and several metamagnetic transitions were seen in the hysteresis loops. Furthermore, the Curie-Weiss fitting revealed an unusually small effective moment of Dy, which is far below the expected value of Dy3+ (10.65 µB). This material might provide a new platform to study the relationship between crystallographic disorder and magnetism.

Unlocking the potential of N-acetylcysteine: Improving hepatopancreas inflammation, antioxidant capacity and health in common carp (Cyprinus carpio) via the MAPK/NF-κB/Nrf2 signalling pathway.

N-acetylcysteine (NAC) positively contributes to enhancing animal health, regulating inflammation and reducing stress by participating in the synthesis of cysteine, glutathione, and taurine in the body. The present study aims to investigate the effects of dietary different levels of NAC on the morphology, function and physiological state of hepatopancreas in juvenile common carp (Cyprinus carpio). 450 common carps were randomly divided into 5 groups: N1 (basal diet), N2 (1.5 g/kg NAC diet), N3 (3.0 g/kg NAC diet), N4 (4.5 g/kg NAC diet) and N5 (6.0 g/kg NAC diet), and fed for 8 weeks. The results indicated that dietary 3.0-6.0 g/kg NAC reduced hepatopancreas lipid vacuoles and nuclear translocation, and inhibited apoptosis in common carp. Simultaneously, the activities of hepatopancreas alanine aminotransferase and aspartate aminotransferase progressively increased with rising dietary NAC levels. Dietary NAC enhanced the non-specific immune function of common carp, and exerted anti-inflammatory effects by inhibiting the MAPK/NF-κB signaling pathway. Additionally, dietary 3.0-6.0 g/kg NAC significantly improved the antioxidant capacity of common carp, which was associated with enhanced glutathione metabolism, clearance of ROS and the activation of Nrf2 signaling pathway. In summary, NAC has the potential to alleviate inflammation, mitigate oxidative stress and inhibit apoptosis via the MAPK/NF-κB/Nrf2 signaling pathway, thereby improving hepatopancreas function and health of common carp. The current findings provide a theoretical basis for promoting the application of NAC in aquaculture and ecological cultivation of aquatic animals.

Selective α-oxidation of amides via visible-light-driven iron catalysis.

Hydroxyl radicals (˙OH) as one of the highly reactive species can react unselectively with a wide range of chemicals. The ˙OH radicals are typically generated under harsh conditions. Herein, we report hydroxyl radical-induced selective N-α C(sp3)-H bond oxidation of amides under greener and mild conditions via an Fe(NO3)3·9H2O catalyst inner sphere pathway upon irradiation with a 30 W blue LED light strip (λ = 455 nm) using NaBrO3 as the oxidant. This protocol exhibited high chemoselectivity and excellent functional group tolerance. A preliminary mechanism investigation demonstrated that the iron catalyst afforded hydroxyl radicals via the visible-light-induced homolysis (VLIH) of iron complexes followed by a hydrogen atom transfer (HAT) process to realize this transformation.

Mettl14-Mediated m6A Modification Is Essential for Germinal Center B Cell Response.

The germinal center (GC) response is essential for generating memory B and long-lived Ab-secreting plasma cells during the T cell-dependent immune response. In the GC, signals via the BCR and CD40 collaboratively promote the proliferation and positive selection of GC B cells expressing BCRs with high affinities for specific Ags. Although a complex gene transcriptional regulatory network is known to control the GC response, it remains elusive how the positive selection of GC B cells is modulated posttranscriptionally. In this study, we show that methyltransferase like 14 (Mettl14)-mediated methylation of adenosines at the position N 6 of mRNA (N 6-methyladenosine [m6A]) is essential for the GC B cell response in mice. Ablation of Mettl14 in B cells leads to compromised GC B cell proliferation and a defective Ab response. Interestingly, we unravel that Mettl14-mediated m6A regulates the expression of genes critical for positive selection and cell cycle regulation of GC B cells in a Ythdf2-dependent but Myc-independent manner. Furthermore, our study reveals that Mettl14-mediated m6A modification promotes mRNA decay of negative immune regulators, such as Lax1 and Tipe2, to upregulate genes requisite for GC B cell positive selection and proliferation. Thus, our findings suggest that Mettl14-mediated m6A modification plays an essential role in the GC B cell response.

RNA-Editing Enzyme ADAR1 p150 Isoform Is Critical for Germinal Center B Cell Response.

Adenosine deaminase acting on RNA (ADAR)1 is the principal enzyme for adenosine-to-inosine editing, an RNA modification-avoiding cytosolic nucleic acid sensor's activation triggered by endogenous dsRNAs. Two ADAR1 isoforms exist in mammals, a longer IFN-inducible and mainly cytoplasm-localized p150 isoform and a shorter constitutively expressed and primarily nucleus-localized p110 isoform. Studies of ADAR1 mutant mice have demonstrated that ADAR1 is essential for multiple physiological processes, including embryonic development, innate immune response, and B and T lymphocyte development. However, it remained unknown whether ADAR1 plays a role in the humoral immune response. In this study, we conditionally delete Adar1 in activated B cells and show that ADAR1-deficient mice have a defective T cell-dependent Ab response and diminished germinal center (GC) B cells. Using various double mutant mice concurrently deficient in ADAR1 and different downstream dsRNA sensors, we demonstrate that ADAR1 regulates the GC response by preventing hyperactivation of the melanoma differentiation-associated protein 5 (MDA5) but not the protein kinase R or RNase L pathway. We also show that p150 is exclusively responsible for ADAR1's function in the GC response, and the p110 isoform cannot substitute for the p150's role, even when p110 is constitutively expressed in the cytoplasm. We further demonstrated that the dsRNA-binding but not the RNA-editing activity is required for ADAR1's function in the GC response. Thus, our data suggest that the ADAR1 p150 isoform plays a crucial role in regulating the GC B cell response.

RNA granule-clustered mitochondrial aminoacyl-tRNA synthetases form multiple complexes with the potential to fine-tune tRNA aminoacylation.

Mitochondrial RNA metabolism is suggested to occur in identified compartmentalized foci, i.e. mitochondrial RNA granules (MRGs). Mitochondrial aminoacyl-tRNA synthetases (mito aaRSs) catalyze tRNA charging and are key components in mitochondrial gene expression. Mutations of mito aaRSs are associated with various human disorders. However, the suborganelle distribution, interaction network and regulatory mechanism of mito aaRSs remain largely unknown. Here, we found that all mito aaRSs partly colocalize with MRG, and this colocalization is likely facilitated by tRNA-binding capacity. A fraction of human mitochondrial AlaRS (hmtAlaRS) and hmtSerRS formed a direct complex via interaction between catalytic domains in vivo. Aminoacylation activities of both hmtAlaRS and hmtSerRS were fine-tuned upon complex formation in vitro. We further established a full spectrum of interaction networks via immunoprecipitation and mass spectrometry for all mito aaRSs and discovered interactions between hmtSerRS and hmtAsnRS, between hmtSerRS and hmtTyrRS and between hmtThrRS and hmtArgRS. The activity of hmtTyrRS was also influenced by the presence of hmtSerRS. Notably, hmtSerRS utilized the same catalytic domain in mediating several interactions. Altogether, our results systematically analyzed the suborganelle localization and interaction network of mito aaRSs and discovered several mito aaRS-containing complexes, deepening our understanding of the functional and regulatory mechanisms of mito aaRSs.

Molecular basis for human mitochondrial tRNA m3C modification by alternatively spliced METTL8.

METTL8 has recently been identified as the methyltransferase catalyzing 3-methylcytidine biogenesis at position 32 (m3C32) of mitochondrial tRNAs. METTL8 also potentially participates in mRNA methylation and R-loop biogenesis. How METTL8 plays multiple roles in distinct cell compartments and catalyzes mitochondrial tRNA m3C formation remain unclear. Here, we discovered that alternative mRNA splicing generated several isoforms of METTL8. One isoform (METTL8-Iso1) was targeted to mitochondria via an N-terminal pre-sequence, while another one (METTL8-Iso4) mainly localized to the nucleolus. METTL8-Iso1-mediated m3C32 modification of human mitochondrial tRNAThr (hmtRNAThr) was not reliant on t6A modification at A37 (t6A37), while that of hmtRNASer(UCN) critically depended on i6A modification at A37 (i6A37). We clarified the hmtRNAThr substrate recognition mechanism, which was obviously different from that of hmtRNASer(UCN), in terms of requiring a G35 determinant. Moreover, SARS2 (mitochondrial seryl-tRNA synthetase) interacted with METTL8-Iso1 in an RNA-independent manner and modestly accelerated m3C modification activity. We further elucidated how nonsubstrate tRNAs in human mitochondria were efficiently discriminated by METTL8-Iso1. In summary, our results established the expression pattern of METTL8, clarified the molecular basis for m3C32 modification by METTL8-Iso1 and provided the rationale for the involvement of METTL8 in tRNA modification, mRNA methylation or R-loop biogenesis.

Three New Steroids from the Roots of Marsdenia tenacissima.

Three undescribed pregnane steroids, 12ß-O-4-hydroxybenzoyl tenacigenin D (1), 12ß-O-4-hydroxybenzoyl tenacigenin A (2), and 11α-nicotinoyl-17ß-marsdenin (3), along with two known analogues (4 and 5), were isolated from the roots of Marsdenia tenacissima. Their structures were elucidated using one- and two-dimensional NMR, high-resolution electron ionization-mass spectrometry, single-crystal X-ray diffraction data, and experimental and density-functional-theory-calculated electronic circular dichroism measurements. All isolated compounds were evaluated for their cytotoxic activities against human lung cancer cells (A549), ovarian carcinoma cells (SKOV-3), gastric cancer cells (MGC 803) and breast cancer cells (MCF-7). Notably, 3 exhibited significant cytotoxic activity against both A549 (median inhibitory concentration (IC50) = 16.79 µM) and SKOV-3 (IC50 = 12.30 µM) cells while exhibiting moderate cytotoxicity on MGC803 and MCF-7 cells.

Multistatic Integrated Sensing and Communication System Based on Macro-Micro Cooperation.

A novel multistatic integrated sensing and communication (ISAC) system based on macro-micro cooperation for the sixth-generation (6G) mobile network is proposed. Instead of using macrosites at both the transmitter and receiver sides, microsites are considered as receivers in cooperative sensing. This system is important since microsites can be deployed more flexibly to reduce their distances to the sensing objects, providing better coverage for sensing service. In this work, we first analyze the deployment problem of microsites, which can be deployed along the radius and azimuth angle to cover macrosite cells. The coverage area of each microsite is derived in terms of its position in the cell. Then, we describe an efficient estimating approach for obtaining the position and velocity of sensing objects in the macrosite cell. By choosing multiple microsites around the targeted sensing area, joint data processing with an efficient optimization method is also provided. Simulation results show that the multistatic ISAC system employing macro-micro cooperation can improve the position and velocity estimation accuracy of objects compared to systems employing macrosite cooperation alone, demonstrating the effectiveness and potential for implementing the proposed system in the 6G mobile network.

Multiple mobile excitons manifested as sidebands in quasi-one-dimensional metallic TaSe3.

Charge neutrality and their expected itinerant nature makes excitons potential transmitters of information. However, exciton mobility remains inaccessible to traditional optical experiments that only create and detect excitons with negligible momentum. Here, using angle-resolved photoemission spectroscopy, we detect dispersing excitons in the quasi-one-dimensional metallic trichalcogenide, TaSe3. The low density of conduction electrons and the low dimensionality in TaSe3 combined with a polaronic renormalization of the conduction band and the poorly screened interaction between these polarons and photo-induced valence holes leads to various excitonic bound states that we interpret as intrachain and interchain excitons, and possibly trions. The thresholds for the formation of a photo-hole together with an exciton appear as side valence bands with dispersions nearly parallel to the main valence band, but shifted to lower excitation energies. The energy separation between side and main valence bands can be controlled by surface doping, enabling the tuning of certain exciton properties.

Variational mode decomposition-based abnormal wheel-rail relationship detection in distributed acoustic sensing.

The distributed acoustic sensing system can obtain the vibration signal caused by the vibration of the train. By analyzing these wheel-rail vibration signals, an abnormal wheel-rail relationship identification scheme is proposed. The variational mode decomposition is employed for signal decomposition, thereby obtaining intrinsic mode functions with prominent abnormal fluctuations. The kurtosis value of each intrinsic mode function is calculated, which is compared with the threshold value for the identification of trains with abnormal wheel-rail relationship. And the extreme point of the abnormal intrinsic mode function is used to locate the bogie with an abnormal wheel-rail relationship. Experimental demonstration verifies that the proposed scheme can identify the train and locate the bogie with an abnormal wheel-rail relationship.

Anti-noise UWFBG-array enhanced DAS system using double-pulse-based time-domain adaptive delay interference.

An anti-noise interrogation technique for ultra-weak fiber Bragg grating (UWFBG)-based distributed acoustic sensing (DAS) systems is proposed and demonstrated using double-pulse-based time-domain adaptive delay interference. This technique breaks the limitation that the optical path difference (OPD) between the two arms of the interferometer should be completely matched with the entire OPD between the adjacent gratings in the traditional single-pulse system. The length of the delay fiber in the interferometer can be reduced, and the double-pulse interval can adapt flexibly to the UWFBG array with different grating spacing. The acoustic signal is restored accurately when the grating spacing is 15 m or 20 m by the time-domain adjustable delay interference. Moreover, the noise induced by the interferometer can be suppressed significantly as compared to using a single pulse, and above 8-dB signal-to-noise ratio (SNR) enhancement can be obtained without any extra optical devices when the noise frequency and the vibration acceleration are below 100 Hz and 0.1 m/s2, respectively.