Distinct Complexes Research Articles

Selective Metal‐Coordinated Nanodrugs Based on Thiazine Moiety for Anticancer Therapeutics: Spectroscopic, Theoretical, and Molecular Docking Studies

ABSTRACTThe current study involved production, comprehensive structural analysis, and physicochemical characterizing of two distinctive complexes namely, Cu(TBH) and Zn(TBH); TBH donor ligand: N′‐(1‐(3,6‐dihydro‐4‐hydroxy‐2,6‐dioxo‐2H‐1,3‐thiazin‐5‐yl)ethylidene)‐2‐hydroxybenzohydrazide) using a wide range of analytical methods, including elemental analysis, UV–Vis, FT‐IR, and 1HNMR spectrometry, molar conductivity and magnetic susceptibility measurements, and thermal analysis. According to the findings, chelation can occur through O, N, and O donor atoms of monoanionic chelator for generating mono‐nuclear chelates with tetrahedral geometry for Cu (II) and octahedral geometry for Zn (II). The anticarcinogenic ability of TBH chelator and its coordinated compounds against human liver cancer (HepG‐2) was investigated. The Cu(TBH) complex was found to have selective and promising anticancer activity against a liver cancer cell line, with lower IC50 (liver carcinoma cell line) and higher IC50 (normal human cell line) values than other produced compounds and standard drugs. Utilizing DFT computations, the molecular structures of the TBH and its complexes were verified, offering a detailed understanding of their quantum chemical characteristics. A quantitative structure–activity relationship (QSAR) model, which illustrates the association between DFT‐computed descriptors and biological activities pIC50, was also created using multiple linear regression (MLR) on the synthesized compounds as anticancer medicines. Additionally, there are no issues with the produced compounds' oral bioavailability according to (ROF) Lipinski's rule of five. Furthermore, docking studies of the synthesized TBH chelator and its chelates with CDK2 kinase have been performed to validate the biological findings. According to our findings, the novel Cu(TBH) nanodrug exhibits considerable cytotoxic activity, prompting further study into its pharmacological profile and exploring its potential in drug development.

Structural variation of types IV-A1- and IV-A3-mediated CRISPR interference

CRISPR-Cas mediated DNA-interference typically relies on sequence-specific binding and nucleolytic degradation of foreign genetic material. Type IV-A CRISPR-Cas systems diverge from this general mechanism, using a nuclease-independent interference pathway to suppress gene expression for gene regulation and plasmid competition. To understand how the type IV-A system associated effector complex achieves this interference, we determine cryo-EM structures of two evolutionarily distinct type IV-A complexes (types IV-A1 and IV-A3) bound to cognate DNA-targets in the presence and absence of the type IV-A signature DinG effector helicase. The structures reveal how the effector complexes recognize the protospacer adjacent motif and target-strand DNA to form an R-loop structure. Additionally, we reveal differences between types IV-A1 and IV-A3 in DNA interactions and structural motifs that allow for in trans recruitment of DinG. Our study provides a detailed view of type IV-A mediated DNA-interference and presents a structural foundation for engineering type IV-A-based genome editing tools.

SERRATE drives phase separation behaviours to regulate m6A modification and miRNA biogenesis.

The methyltransferase complex (MTC) deposits N6-adenosine (m6A) onto RNA, whereas the microprocessor produces microRNA. Whether and how these two distinct complexes cross-regulate each other has been poorly studied. Here we report that the MTC subunit B tends to form insoluble condensates with poor activity, with its level monitored by the 20S proteasome. Conversely, the microprocessor component SERRATE (SE) forms liquid-like condensates, which in turn promote the solubility and stability of the MTC subunit B, leading to increased MTC activity. Consistently, the hypomorphic lines expressing SE variants, defective in MTC interaction or liquid-like phase behaviour, exhibit reduced m6A levels. Reciprocally, MTC can recruit the microprocessor to the MIRNA loci, prompting co-transcriptional cleavage of primary miRNA substrates. Additionally, primary miRNA substrates carrying m6A modifications at their single-stranded basal regions are enriched by m6A readers, which retain the microprocessor in the nucleoplasm for continuing processing. This reveals an unappreciated mechanism of phase separation in RNA modification and processing through MTC and microprocessor coordination.

A transcriptomic hourglass in brown algae.

Complex multicellularity has emerged independently across a few eukaryotic lineages and is often associated with the rise of elaborate, tightly coordinated developmental processes1,2. How multicellularity and development are interconnected in evolution is a major question in biology. The hourglass model of embryonic evolution depicts how developmental processes are conserved during evolution, and predicts morphological and molecular divergence in early and late embryogenesis, bridged by a conserved mid-embryonic (phylotypic) period linked to the formation of the basic body plan3,4. Initially found in animal embryos5-8, molecular hourglass patterns have recently been proposed for land plants and fungi9,10. However, whether the hourglass pattern is an intrinsic feature of all complex multicellular eukaryotes remains unknown. Here we tested the presence of a molecular hourglass in the brown algae, a eukaryotic lineage that has evolved multicellularity independently from animals, fungi and plants1,11,12. By exploring transcriptome evolution patterns of brown algae with distinct morphological complexities, we uncovered an hourglass pattern during embryogenesis in morphologically complex species. Filamentous algae without canonical embryogenesis display transcriptome conservation in multicellular stages of the life cycle, whereas unicellular stages are more rapidly evolving. Our findings suggest that transcriptome conservation in brown algae is associated with cell differentiation stages, but is not necessarily linked to embryogenesis. Together with previous work in animals, plants and fungi, we provide further evidence for the generality of a developmental hourglass pattern across complex multicellular eukaryotes.

Distinct Regions within SAP25 Recruit O-Linked Glycosylation, DNA Demethylation, and Ubiquitin Ligase and Hydrolase Activities to the Sin3/HDAC Complex.

Sin3 is an evolutionarily conserved repressor protein complex mainly associated with histone deacetylase (HDAC) activity. Many proteins are part of Sin3/HDAC complexes, and the function of most of these members remains poorly understood. SAP25, a previously identified Sin3A associated protein of 25 kDa, has been proposed to participate in regulating gene expression programs involved in the immune response but the exact mechanism of this regulation is unclear. SAP25 is not expressed in HEK293 cells, which hence serve as a natural knockout system to decipher the molecular functions uniquely carried out by this Sin3/HDAC subunit. Using molecular, proteomic, protein engineering, and interaction network approaches, we show that SAP25 interacts with distinct enzymatic and regulatory protein complexes in addition to Sin3/HDAC. Additional proteins uniquely recovered from the Halo-SAP25 pull-downs included the SCF E3 ubiquitin ligase complex SKP1/FBXO3/CUL1 and the ubiquitin carboxyl-terminal hydrolase 11 (USP11). Furthermore, mutational analysis demonstrates that distinct regions of SAP25 participate in its interaction with USP11, OGT/TETs, and SCF(FBXO3). These results suggest that SAP25 may function as an adaptor protein to coordinate the assembly of different enzymatic complexes to control Sin3/HDAC-mediated gene expression. The data were deposited with the MASSIVE repository with the identifiers MSV000093576 and MSV000093553.

Global nuclear reorganization during heterochromatin replication in the giant-genome plant Nigella damascena L.

Among flowering plants, genome size varies remarkably, by >2200-fold, and this variation depends on the loss and gain of noncoding DNA sequences that form distinct heterochromatin complexes during interphase. In plants with giant genomes, most chromatin remains condensed during interphase, forming a dense network of heterochromatin threads called interphase chromonemata. Using super-resolution light and electron microscopy, we studied the ultrastructure of chromonemata during and after replication in root meristem nuclei of Nigella damascena L. During S-phase, heterochromatin undergoes transient decondensation locally at DNA replication sites. Due to the abundance of heterochromatin, the replication leads to a robust disassembly of the chromonema meshwork and a general reorganization of the nuclear morphology visible even by conventional light microscopy. After replication, heterochromatin recondenses, restoring the chromonema structure. Thus, we show that heterochromatin replication in interphase nuclei of giant-genome plants induces a global nuclear reorganization.

A novel copper(II) complex with a salicylidene carbohydrazide ligand that promotes oxidative stress and apoptosis in triple negative breast cancer cells.

We report the synthesis, characterization, anti-cancer activity and mechanism of action of a novel water-soluble Cu(II) complex with salicylidene carbohydrazide as the ligand and o-phenanthroline as the co-ligand. The synthesized complex (1) was characterized by FT-IR, EPR, and electronic spectroscopy, as well as single crystal X-ray diffraction. This compound was found to be paramagnetic from EPR spectra and X-ray crystallography revealed that the molecule crystallized in an orthorhombic crystal system. The crystal lattice was asymmetric containing two distinct binuclear copper complexes containing the Schiff base as the major ligand, o-phenanthroline as a co-ligand, two nitrate anions, and two water molecules. The Cu(II) in the first site coordinated with the enolised ligand comprising enolate O-, phenolate O-, and the imine N and N,N from o-phen. The major part of this complex exists as Cu(II) coordinated with two H2O molecules at the second site with nitrate acting as the counter anion. However, a smaller portion of the complex exists where Cu(II) is coordinated with NO3- and H2O, and the remaining water molecule acts as lattice water. It was tested for DNA binding and cleavage properties which revealed that it binds in an intercalative mode to CT-DNA with Kb value of 1.25 × 104 M-1. Furthermore, cleavage studies reveal that the complex has potential for efficient DNA cleavage under both oxidative and hydrolytic conditions. It was able to enhance the rate of cleavage by 2.8 × 108 times. The complex shows good cytotoxicity to breast cancer monolayer (2D) as well as spheroid (3D) systems. The IC50 values for MDA-MB-231 and MCF-7 monolayer culture was calculated as 1.86 ± 0.17 μM and 2.22 ± 0.08 μM, respectively, and in (3D) spheroids of MDA-MB-231 cells, the IC50 value was calculated to be 1.51 ± 0.29 μM. It was observed that the complex outperformed cisplatin in both breast cancer cell lines. The cells treated with complex 1 underwent severe DNA damage, increased oxidative stress and cell cycle arrest which finally led to programmed cell death or apoptosis in triple negative breast cancer cells through an intrinsic pathway.

Rare Presentation of Anaplastic Carcinoma as a Mural Nodule in Mucinous Cystadenoma with Concurrent Benign Brenner Tumor

Abstract Introduction/Objective Mural nodules in ovarian mucinous tumors, particularly which are anaplastic carcinomas, represent an exceedingly rare and complex diagnostic category. The literature documents only a few such tumors, predominantly sarcoma-like, with favorable prognoses. In contrast, malignant mural nodules, including anaplastic carcinoma and sarcomatous or carcinosarcomatous types, are notably rare, with fewer than ten cases reported. The co-occurrence of an anaplastic carcinoma mural nodule with a benign Brenner tumor presents distinct diagnostic and treatment complexities stemming from mixed tumor pathology and associated genetic mutations like KRAS and p53, critical in the development of these unusual nodules. This report deepens our insight into rare ovarian tumors. Methods/Case Report A 60-year-old woman with persistent lower abdominal pain underwent surgery for a suspected benign ovarian cyst based on initial imaging. The removed ovary contained a 10.5 x 10 x 8 cm unilocular cyst lined with benign, mucin-containing columnar epithelium. However, a 2 cm anaplastic carcinoma mural nodule was identified within the cyst, exhibiting cellular pleomorphism, nuclear atypia, and high mitotic activity. Immunohistochemical staining confirmed the carcinoma with diffuse cytokeratin and EMA positivity. The fallopian tube was free of tumor involvement, and no capsular or lymphovascular invasion was seen. The cancer was staged as PT1a, pNx, pMx. Results (if a Case Study enter NA) NA Conclusion Anaplastic carcinoma, when present as a mural nodule within a benign-looking mucinous cystadenoma, demands an aggressive treatment strategy due to its poor prognosis and aggressive nature. Such cases require a deviation from standard benign treatment protocols to include extensive surgery, possibly, depending on disease progression, chemotherapy or radiation.

The synthesis and structures of four new copper(II) adamantoid clusters

Four new copper(II) compounds with an inorganic, adamantane-like core have been prepared and structurally characterized: [(2-aminopyridine)4(μ2-Br)6Cu4(μ4-O)].(2-aminopyridinium) bromide monohydrate (1), the open cage structure (2-aminopyridinium) [(2-aminopyridine)4(μ2-Cl)5(Cl)2Cu4(μ4-O)] (2), bis(2-amino-5-methylpyridinium) [(2-amino-5-methylpyridine)2(μ2-Cl)6(Cl)2Cu4(μ4-O)] (3) and the co-crystal [(2-amino-5-fluoropyridine)4(μ-Cl)6Cu4(μ4-O)]2 [(2-amino-5-fluoropyridine)4Cu2Cl4] (4). All four include additional components in the lattice ranging from a non-coordinated ancillary ligand (1) to a co-crystallization with a distinct coordination complex (4). The compounds crystallize as: 1, triclinic, P-1; 2, monoclinic, P21/c; 3, monoclinic, P21/c; 4, triclinic, P-1. Analysis of the geometric parameters within the adamantoid cores of the compounds indicates significant structural resilience as parameters are little changed by the presence of additional components in the lattice. Breaking of the central core by coordination of an additional chloride ion in 2 significantly affects the geometry about those two Cu(II) ions but has little effect on other parts of the core.

Mixtures of Intrinsically Disordered Neuronal Protein Tau and Anionic Liposomes Reveal Distinct Anionic Liposome-Tau Complexes Coexisting with Tau Liquid-Liquid Phase-Separated Coacervates.

Tau, an intrinsically disordered neuronal protein and polyampholyte with an overall positive charge, is a microtubule (MT) associated protein that binds to anionic domains of MTs and suppresses their dynamic instability. Aberrant tau-MT interactions are implicated in Alzheimer's and other neurodegenerative diseases. Here, we studied the interactions between full-length human protein tau and other negatively charged binding substrates, as revealed by differential interference contrast (DIC) and fluorescence microscopy. As a binding substrate, we chose anionic liposomes (ALs) containing either 1,2-dioleoyl-sn-glycero-3-phosphatidylserine (DOPS, -1e) or 1,2-dioleoyl-sn-glycero-3-phosphatidylglycerol (DOPG, -1e) mixed with zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) to mimic anionic plasma membranes of axons where tau resides. At low salt concentrations (0 to 10 mM KCl or NaCl) with minimal charge screening, reaction mixtures of tau and ALs resulted in the formation of distinct states of AL-tau complexes coexisting with liquid-liquid phase-separated tau self-coacervates arising from the polyampholytic nature of tau containing cationic and anionic domains. AL-tau complexes (i.e. tau-lipoplexes) exhibited distinct types of morphologies. This included large ∼20-30 μm tau-decorated giant vesicles with additional smaller liposomes with bound tau attached to the giant vesicles and tau-mediated finite-size assemblies of small liposomes. As the salt concentration was increased to near and above 150 mM for 1:1 electrolytes, AL-tau complexes remained stable, while tau self-coacervate droplets were found to dissolve, indicative of the breaking of (anionic/cationic) electrostatic bonds between tau chains due to increased charge screening. The findings are consistent with the hypothesis that distinct cationic domains of tau may interact with anionic lipid domains of the lumen-facing monolayer of the axon's plasma membrane, suggesting the possibility of transient yet robust interactions near relevant ionic strengths found in neurons.

Characterization of Streptococcus agalactiae 1a isolated from farmed Nile tilapia (Oreochromis niloticus) in North America, Central America, and Southeast Asia

Streptococcosis caused by Streptococcus agalactiae 1a in Nile tilapia (Oreochromis niloticus) is a severe disease challenge for the global supply of tilapia. Currently, the extensive use of antibiotics is the primary curative tool used to minimize the impact of the disease. Vaccination is a prophylactic measure that has been shown to reduce antibiotic use in the aquaculture sector substantially. However, no commercially licensed vaccine against Streptococcus agalactiae 1a is currently available.This study aimed to investigate, through molecular and immunological methods, if Streptococcus agalactiae 1a isolates collected from North America (NAM), Central America (CAM), and Southeast Asia (SEA) were similarly suitable for the development of a potentially effective vaccine to serve the global tilapia farming industry. Our comparative data showed that the Streptococcus agalactiae 1a isolates from NAM, CAM and SEA had similar biochemical profiles, and genetic multi-locus sequence typing (MLST) analysis showed that the NAM and CAM isolates belonged to sequence type 7 (ST-7) and clonal complex 1, while isolates from SEA grouped into three sequence types (ST-1650, ST-500, and ST-7) and two distinct clonal complexes (CC1 and CC12). Isolates from NAM, CAM, and SEA displayed similar antigenic profiles determined by western blotting with polyclonal rabbit antisera, which was supported by in vivo cross-protection studies, showing that fish immunized with vaccines based on SEA and CAM isolates with different genetic MLST profiles were highly protected against cross-challenge using the same bacterial strains for challenge. Overall, the data obtained from our investigations provide strong indications that Streptococcus agalactiae 1a distributed in NAM, CAM, and SEA are serologically uniform pathogens, and vaccines based on isolates of Streptococcus agalactiae 1a from these regions may be suited for vaccination of tilapia worldwide.

Action of Molybdate Anion on d-Glucosone: Catalytic Conversion to Aldonates Involving C1-C2 Transposition.

Treatment of the osone (aldos-2-ulose), d-[1-13C]glucosone (1 1), with sodium molybdate at 90° for 30 h gave a mixture of d-[2-13C]gluconate (2 2) and d-[2-13C]mannonate (3 2) in an 85:15 ratio, indicating that the reaction proceeds with C1-C2 transposition similar to that observed previously with aldoses. Reactions with several singly and doubly 13C-labeled isotopomers of 1 confirmed this transposition. In contrast to the aldose reaction, the reaction with 1 is irreversible, presumably due to electrostatic repulsion between the negatively charged catalytically active bimolybdate species and the negatively charged aldonate product. The production of 2 and 3 is mediated by the formation of two structurally distinct bimolybdate complexes, one producing the gluco isomer and the other producing the manno isomer. Reaction byproducts were also observed, specifically d-[1-13C]arabinose (4 1) and [13C]formate (5), when 1 1 was used as the reactant. These byproducts appear to form from the breakdown of bimolybdate complexes via alternative pathways that compete with those responsible for aldonate formation.

CCNP Innovations in Neuropsychopharmacology Award: The psychopharmacology of psychedelics: where the brain meets spirituality.

For 3000 years, psychedelics have been used in religious contexts to enhance spiritual thinking, well-being, and a sense of community. In the last few years, a renaissance in the use of psychedelic drugs for mental disorders has occurred in Western society; consequently, a pressing scientific need to elucidate the intricate mechanisms underlying their actions has arisen. Psychedelics mainly bind to serotonin (5-HT) receptors, particularly 5-HT2A receptors, but may also bind to other receptors. Unlike conventional psychotropic drugs used in psychiatry, psychedelics introduce a distinctive complexity. They not only engage in receptor activation, but also exert influence over specific neural circuits, thereby facilitating transformative cognitive experiences and fostering what many have identified as a spiritual contemplation or mystical experience. This comprehensive review describes clinical studies that have examined the propensity of psychedelics to enhance spiritual, mystical, and transcendent cognitive states. This multifaceted nature, encompassing diverse components and paradigms, necessitates careful consideration during the investigation of psychedelic mechanisms of action to avoid oversimplification. The present review endeavours to elucidate the mechanisms underlying the actions of 2 principal psychedelic substances, psilocybin and lysergic acid diethylamide (LSD), with a focus on monoamine and glutamate receptor mechanisms; molecular aspects, such as neuroplasticity and epigenetics; as well as the impact of psychedelics on brain circuits, including the default mode network and the cortico-striato-thalamo-cortical network. Given their distinctive and intricate mechanisms of action, psychedelics necessitate a novel conceptual framework in psychiatry, offering insight into the treatment of mental health disorders and facilitating the integration of the realms of brain, mind, and spirituality.

Crystal structure and nucleic acid binding mode of CPV NSP9: implications for viroplasm in Reovirales.

Cytoplasmic polyhedrosis viruses (CPVs), like other members of the order Reovirales, produce viroplasms, hubs of viral assembly that shield them from host immunity. Our study investigates the potential role of NSP9, a nucleic acid-binding non-structural protein encoded by CPVs, in viroplasm biogenesis. We determined the crystal structure of the NSP9 core (NSP9ΔC), which shows a dimeric organization topologically similar to the P9-1 homodimers of plant reoviruses. The disordered C-terminal region of NSP9 facilitates oligomerization but is dispensable for nucleic acid binding. NSP9 robustly binds to single- and double-stranded nucleic acids, regardless of RNA or DNA origin. Mutagenesis studies further confirmed that the dimeric form of NSP9 is critical for nucleic acid binding due to positively charged residues that form a tunnel during homodimerization. Gel migration assays reveal a unique nucleic acid binding pattern, with the sequential appearance of two distinct complexes dependent on protein concentration. The similar gel migration pattern shared by NSP9 and rotavirus NSP3, coupled with its structural resemblance to P9-1, hints at a potential role in translational regulation or viral genome packaging, which may be linked to viroplasm. This study advances our understanding of viroplasm biogenesis and Reovirales replication, providing insights into potential antiviral drug targets.

JR-AB2-011 induces fast metabolic changes independent of mTOR complex 2 inhibition in human leukemia cells.

The mechanistic target of rapamycin (mTOR) is a crucial regulator of cell metabolic activity. It forms part of several distinct protein complexes, particularly mTORC1 and mTORC2. The lack of specific inhibitors still hampers the attribution of mTOR functions to these complexes. JR-AB2-011 has been reported as a specific mTORC2 inhibitor preventing mTOR binding to RICTOR, a unique component of mTORC2. We aimed to describe the effects of JR-AB2-011 in leukemia/lymphoma cells, where the mTOR pathway is often aberrantly activated. The impact of JR-AB2-011 on leukemia/lymphoma cell metabolism was analyzed using the Seahorse platform. AKT phosphorylation at Ser473 was used as a marker of mTORC2 activity. mTOR binding to RICTOR was assessed by co-immunoprecipitation. RICTOR-null cells were derived from the Karpas-299 cell line using CRISPR/Cas9 gene editing. In leukemia/lymphoma cell lines, JR-AB2-011 induced a rapid drop in the cell respiration rate, which was variably compensated by an increased glycolytic rate. In contrast, an increase in the respiration rate due to JR-AB2-011 treatment was observed in primary leukemia cells. Unexpectedly, JR-AB2-011 did not affect AKT Ser473 phosphorylation. In addition, mTOR did not dissociate from RICTOR in cells treated with JR-AB2-011 under the experimental conditions used in this study. The effect of JR-AB2-011 on cell respiration was retained in RICTOR-null cells. JR-AB2-011 affects leukemia/lymphoma cell metabolism via a mechanism independent of mTORC2.

Modeling hyperbranched polymer formation via ATRP using dissipative particle dynamics

Hyperbranched polymers (HBPs) offer distinguishing, advantageous properties that arise from their distinctive complex topology. One of the effective approaches to the synthesis of hyperbranched structures involves the use of a branching initiator (inibramer) that is activated only after incorporation into a polymer chain. There remain, however, challenges in determining and characterizing the structures of the synthesized HBPs. Dissipative particle dynamics (DPD) was used to probe the effects of inibramer concentration, solvent concentration, and inibramer reactivity on the kinetics, molecular weight, and dispersity of HBPs. Additionally, DPD allows for direct observation of branched structures, which was not possible in previously reported Monte Carlo type simulations. It was found that higher inibramer concentrations led to faster monomer consumption while forming more dendritic structures with fewer defects. Additionally, high dispersities characteristic of HBP systems were found to originate from asymmetric propagation rates between inibramer-inibramer and inibramer-monomer reactions.

How does CHD4 slide nucleosomes?

Chromatin remodelling enzymes reposition nucleosomes throughout the genome to regulate the rate of transcription and other processes. These enzymes have been studied intensively since the 1990s, and yet the mechanism by which they operate has only very recently come into focus, following advances in cryoelectron microscopy and single-molecule biophysics. CHD4 is an essential and ubiquitous chromatin remodelling enzyme that until recently has received less attention than remodellers such as Snf2 and CHD1. Here we review what recent work in the field has taught us about how CHD4 reshapes the genome. Cryoelectron microscopy and single-molecule studies demonstrate that CHD4 shares a central remodelling mechanism with most other chromatin remodellers. At the same time, differences between CHD4 and other chromatin remodellers result from the actions of auxiliary domains that regulate remodeller activity by for example: (1) making differential interactions with nucleosomal epitopes such as the acidic patch and the N-terminal tail of histone H4, and (2) inducing the formation of distinct multi-protein remodelling complexes (e.g. NuRD vs ChAHP). Thus, although we have learned much about remodeller activity, there is still clearly much more waiting to be revealed.

‘How anxious I am’: the effect of different online modalities on Chinese language beginners’ classroom anxiety

ABSTRACT Foreign language classroom anxiety (FLCA) is ‘a distinct complex set of self-perceptions, beliefs, feelings and behaviours related to classroom language learning arising from the uniqueness of the language learning process’ (Horwitz, Horwitz and Cope 1986: 128) [Foreign language classroom anxiety. The Modern Language Journal 70, no. 2: 125–32] which potentially has a negative impact on achievement and engagement in language learning. The purpose of the investigation reported here was to examine how two online modalities – Zoom video conferencing and the virtual world, Second Life – affected FLCA among Chinese language beginners performing tasks using the different modes. Through statistical and thematical analyses of survey data along with open-ended questions from 55 participants, it was found that the relationship between FLCA levels experienced by learners on these modalities was influenced by various factors such as gender differences, task-related language skills, and self-perceived language proficiency. The study also suggests that FLCA is dependent on the learners’ immediate learning experience, particularly in relation to their level of engagement and task awareness. Despite the small sample size, the study sheds light on the advantages and limitations of each modality in terms of its effect on students’ FLCA and performance in task-based language teaching.

Reciprocal regulation of m 6 A modification and miRNA production machineries via phase separation-dependent and -independent mechanisms.

Methyltransferase complex (MTC) deposits N 6-adenosine (m 6 A) onto RNA, whereas microprocessor produces miRNA. Whether and how these two distinct complexes cross-regulate each other has been poorly studied. Here we report that the MTC subunit B (MTB) tends to form insoluble condensates with poor activity, with its level monitored by 20S proteasome. Conversely, the microprocessor component SERRATE (SE) forms liquid-like condensates, which in turn promotes solubility and stability of MTB, leading to increased MTC activity. Consistently, the hypomorphic lines expressing SE variants, defective in MTC interaction or liquid-like phase behavior, exhibit reduced m 6 A level. Reciprocally, MTC can recruit microprocessor to MIRNA loci, prompting co-transcriptional cleavage of primary miRNA (pri-miRNAs) substrates. Additionally, pri-miRNAs carrying m 6 A modifications at their single-stranded basal regions are enriched by m 6 A readers, which retain microprocessor in the nucleoplasm for continuing processing. This reveals an unappreciated mechanism of phase separation in RNA modification and processing through MTC and microprocessor coordination.

Oversampling multi-label data based on natural neighbor and label correlation

In multi-label learning, addressing the class imbalance issue is of paramount importance. Oversampling methods are preferred as they offer a more general solution independent of the model choice, i.e., they alleviate the imbalance of datasets by augmenting instances in the pre-processing step. Existing neighbor-based oversampling methods employ an empirical number of neighbors (k=5) to identify the local region for new instances creation. However, a single fixed k value cannot fit all labels, because every label usually has its own distinct distribution and complexity. Furthermore, the label assignment for synthetic instances usually depends on the statistics of individual labels within the corresponding neighborhood, ignoring the informative correlation among labels. To overcome these limitations, we propose an oversampling method called Multi-Label Oversampling with Natural neighbor and label Correlation (MLONC). Our approach offers three main advantages: (1) the adaptive number of neighbors for each label related to the data complexity is obtained via natural neighbor detection; (2) it encourages generating more instances proximate to the decision boundary of highly imbalanced labels, and diminishes the impact of outliers; (3) exploitation of label correlation in label assignment enhances the quality of the synthetic instances. Experimental results demonstrate the effectiveness of MLONC under various base classifiers.