Direct Evidence Research Articles

Irreversible Inhibition of DNMT3A by an N-Mustard Analog of S-Adenosyl-L-Methionine.

DNA methylation, an important epigenetic modification, is catalyzed by DNA methyltransferases and is essential in the regulation of gene expression. Here, the utility of an N-mustard analog designed to mimic the native methyl donor, S-adenosyl-L-methionine (SAM), was explored with the DNA methyltransferase 3A catalytic domain (DNMT3AC). In lieu of the expected analog transfer to DNA, methyltransferase activity was instead inhibited in a concentration dependent manner. Further investigation into the mechanism of analog inhibition did not reveal a typical competitive mechanism. Instead, mass spectrometry analysis provided direct evidence of two cysteine residues in the SAM binding site covalently modified by the SAM analog and confirmed its' function as an irreversible inhibitor of DNMT3AC.

Intensification of submesoscale frontogenesis and forward energy cascade driven by upper-ocean convergent flows

Upper-ocean fronts are an important component of the global climate system, regulating both the oceanic energy cycle and material transports. In the common paradigm, upper-ocean fronts are generated by frontogenesis at the mesoscale (20–300 km), driven predominantly by confluent horizontal flows initiated by a background straining field. However, the mechanisms by which this frontogenesis extends down to and influences the submesoscale (0.2–20 km), which dominates vertical transports in the ocean, are still understudied. Here, we provide direct observational evidence that submesoscale frontogenesis, defined as the rate at which submesoscale buoyancy gradients intensify, is closely linked to convergent flows. Analysis of year-long measurements by a mooring array in the North Atlantic indicates that both the upper-ocean frontogenetic rate and the horizontal convergence exhibit strong seasonality and scale dependence, with larger magnitudes in winter and at smaller horizontal scales (down to at least 2 km). The frontogenetic rate is found to correlate more strongly with horizontal convergence as the scale decreases, suggesting that convergent flows are the main driver of submesoscale frontogenesis. Crucially, a rapid forward cascade of kinetic energy and enhanced vertical velocities preferentially occur during periods of submesoscale frontogenesis. Our findings highlight a mechanism underpinning the key role of submesoscale fronts in the oceanic kinetic energy cascade and as a focus of vertical transports, and call for a parameterization of such effects in climate-scale ocean models.

Recombinant leptins affect lipid metabolism in hepatocytes of Cynoglossus semilaevis

Leptin is a peptide hormone primarily produced by adipose tissue, which plays a crucial role in regulating energy balance by controlling appetite and energy expenditure. To better understand the intricate physiological functions of leptin in hepatocytes in tongue sole (Cynoglossus semilaevis), this study presents an integrated transcriptomic and metabolomic analysis of tongue sole hepatocytes following stimulation with lepA and lepB. Comparative analysis identified 2971 and 2900 upregulated differentially expressed genes (DEGs) and 1895 and 1821 downregulated DEGs in response to lepA and lepB stimulation, respectively. Notably, 5706 genes were commonly regulated by both stimulations, suggesting overlapping functional roles of these two leptin proteins. GO and KEGG enrichment analysis indicated significant enrichment in immune response (JAK-STAT signaling pathway, NF-κB signaling pathway, etc.) and lipid metabolism pathways, such as fatty acid synthesis, with similar findings for lepB. Metabolomic analysis demonstrated clear separation between treatment and control groups, with 34 medium- to long-chain fatty acids and numerous differentially expressed metabolites (DEMs) identified. KEGG analysis of the metabolome paralleled the transcriptomic findings, with shared pathways in lipid metabolism and immune function. Finally, joint analysis highlighted co-enrichment in linoleic acid metabolism and leishmaniasis pathways. Detailed mechanistic insights revealed the activation of JAK-STAT and NF-κB signaling pathways, modulation of arachidonic acid metabolism, and the influence on the MAPK signaling pathway. Additionally, lepA uniquely co-enriched in the fatty acid synthesis pathway, with specific gene regulation affecting the synthesis of various fatty acids. The study concluded that lepA and lepB exerted significant regulatory effects on lipid metabolism and immune responses in tongue sole hepatocytes through complex molecular networks. To our current knowledge, this represents the first direct evidence of leptin's role in immune function within teleost fish and offers valuable insights into the molecular mechanisms of lipid metabolism underlying the actions of lepA and lepB.

Intestinal barrier damage contributes to a higher prevalence of frailty in aging people living with HIV: a retrospective case control study in a Chinese cohort.

It has been previously demonstrated that intestinal barrier damage is one of the underlying mechanisms leading to frailty in non-HIV-infected aging populations. However, there is a paucity of direct evidence which demonstrates the association between intestinal barrier damage and frailty in people living with HIV (PLWH). The present study is a retrospective case control study. Participants older than 50 years old were stratified into a frail/pre-frail group (case group) and non-frail group (control group) according to the Fried frailty phenotype. We collected and curated data concerning socio-demographic variables, psychological states and social functioning, and clinical information associated with the identification of biomarkers of intestinal barrier damage, microbial translocation, and levels of inflammatory cytokines of participants. The case group had significantly higher levels of Reg-3α (p=0.042) and I-FABP (p=0.045) compared to the control group. We further observed, after adjusting for confounding factors by logistic regression analysis, that I-FABP levels remained significantly higher in the case group compared to the control group (p=0.033). Also, Fried Phenotype scores positively correlated with I-FABP levels (rs=0.21, p=0.01), LPS levels (rs=0.20, p=0.02), and sCD14 levels (rs=0.18, p=0.04). Moreover, the study confirmed both the positive correlation between inflammatory cytokines (IL-6 and IP-10) with frailty in aging PLWH, and between inflammatory cytokines (IL-6, IL-8 and IP-10) with biomarkers of intestinal barrier dysfunction in older PLWH. The present study indicates that the inflammation induced by intestinal barrier damage/dysfunction is likely to contribute to frailty in aging PLWH.

Peripheral cranio-spinal nerve communication for trapezius muscle control using axonal profiling through immunostaining

Accessory nerve (CNXI) has been known to be the primary conduit for motor control of the trapezius, while the supplementary cervical nerves (C3 and C4) are responsible for processing sensory information from muscle. However, the lack of substantial direct evidence has led to these conclusions being regarded as mere speculation. This study used immunostaining (using antibodies against neurofilament 200 for all axons, choline acetyltransferase for cholinergic axons, tyrosine hydroxylase for sympathetic axons, and alpha 3 sodium potassium ATPase for proprioceptive afferent axons) of human samples to verify the functional contributions of nerves. Study highlights the pivotal role of C3 and C4 in regulating precise movements of trapezius, contributing to motor control, proprioceptive feedback, and sympathetic modulation. CNXI is composed primarily of somatic efferent fibers, with significant numbers of sympathetic or sensory fibers. Furthermore, C3-4 have both cholinergic and non-cholinergic axons, suggesting their involvement in proprioceptive feedback and somatic efferent functions. Although less common, mechanosensors such as nociceptive sensor and sympathetic fibers are also supplied by these cervical nerves. The study demonstrated that these nerves contain motor fibers and significant proprioceptive and sympathetic axons, challenging the long-held notion that CNXI are motor and upper spinal nerves are sensory.

Morphological phenotype of right ventricular outflow tract is associated with cardiovascular outcomes and premature death

Morphology of right ventricular outflow tract (RVOT) is potentially related to cardiovascular outcomes. However, this relationship still remains to be verified with direct evidence. We retrospectively reviewed cases from the autopsy specimen library in the Center of Forensic Medicine in Sun Yat-sen University from 2017 to 2023. Six RVOT morphological characteristics were measured and their association with cardiovascular diseases (CVDs), sudden cardiac death (SCD) and age at death was evaluated. Relationship between myocardial fibrosis in RVOT and CVDs was investigated. RVOT characteristics were recruited by machine learning algorithms for diagnosing CVDs. A total of 2370 cases were finally recruited. Perimeter of sub-valve plane (pSBV) in RVOT was positively associated with risk of CVDs and SCD (OR: 1.21, 95%CI: 1.07–1.37, p = 0.003; OR: 1.33, 95%CI: 1.16–1.52, p < 0.001). Compared with thickness of septum (tS) < 3.0 mm, tS ≥ 3.0 mm was associated with premature death in disease-dominant death (β=-0.16, 95%CI: -0.20 to -0.11, p < 0.001) and SCD (β=-0.15, 95%CI: -0.21 to -0.10, p < 0.001). Degree of myocardial fibrosis in the posterior septum was increased in coronary atherosclerosis (6.86%±2.48% vs. 4.91%±2.14%, p = 0.011) and cardiomyopathies (8.11%±3.24% vs. 4.88%±3.11%, p = 0.005). A logistic regression model, recruiting age, left and right ventricular wall thickness, pSBV, circumference of pulmonary annulus and aortic annulus, was elected as an optimal diagnostic model of CVDs, yielding AUC of 0.734 (95%CI: 0.705–0.763), 0.781 (0.740–0.821) and 0.763 (0.725-0.800) in training, validation and test sets. Increased pSBV significantly correlates with higher risk of CVDs and SCD. And tS ≥ 3.0 mm is an independent risk factor of premature death regardless of diseases.

Integrated miRNA Signatures: Advancing Breast Cancer Diagnosis and Prognosis.

Breast cancer ranks first in incidence and second in deaths worldwide, presenting alarmingly rising mortality rates. Imaging methodologies and/or invasive biopsies are routinely used for screening and detection, although not always with high sensitivity/specificity. MicroRNAs (miRNAs) could serve as diagnostic and prognostic biomarkers for breast cancer. We have designed a computational approach combining transcriptome profiling, survival analyses, and diagnostic power calculations from 1165 patients with breast invasive carcinoma from The Cancer Genome Atlas (TCGA-BRCA). Our strategy yielded two separate miRNA signatures consisting of four up-regulated and five down-regulated miRNAs in breast tumors, with cumulative diagnostic strength of AUC 0.93 and 0.92, respectively. We provide direct evidence regarding the breast cancer-specific expression of both signatures through a multicancer comparison of >7000 biopsies representing 19 solid cancer types, challenging their diagnostic potency beyond any of the current diagnostic methods. Our signatures are functionally implicated in cancer-related processes with statistically significant effects on overall survival and lymph-node invasion in breast cancer patients, which underlie their strong prognostic implication. Collectively, we propose two novel miRNA signatures with significantly elevated diagnostic and prognostic power as a functionally resolved tool for binary and accurate detection of breast cancer and other tumors of the female reproductive system.

The learnability of natural concepts

According to a recent proposal, natural concepts are represented in an optimally designed similarity space, adhering to principles a skilled engineer would use for creatures with our perceptual and cognitive capacities. One key principle is that natural concepts should be easily learnable. While evidence exists for parts of this optimal design proposal, there has been no direct evidence linking naturalness to learning until now. This article presents results from a computational study on perceptual color space, demonstrating that naturalness indeed facilitates learning.

Stem cell-derived exosomes for ischemic stroke: a conventional and network meta-analysis based on animal models.

We aimed to evaluate the efficacy of stem cell-derived exosomes for treating ischemic stroke and to screen for the optimal administration strategy. We searched PubMed, Web of Science, Embase, Cochrane Library, and Scopus databases for relevant studies published from their inception to 31 December 2023. Conventional and network meta-analyses of the routes of administration, types, and immune compatibility of stem cell-derived exosomes were performed using the cerebral infarct volume (%) and modified neurological severity score (mNSS) as outcome indicators. A total of 38 randomized controlled animal experiments were included. Conventional meta-analysis showed that compared with the negative control group: intravenous administration significantly reduced the cerebral infarct volume (%) and mNSS; intranasal administration significantly reduced the cerebral infarct volume (%); and intracerebral administration significantly reduced the mNSS. Adipose-derived mesenchymal stem cell-derived exosomes (ADSC-Exos), bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos), dental pulp stem cell-derived exosomes (DPSC-Exos) and neural stem cell-derived exosomes (NSC-Exos) significantly reduced the cerebral infarct volume (%) and mNSS; Endothelial progenitor cell-derived exosomes (EPC-Exos), embryonic stem cell-derived exosomes (ESC-Exos), induced pluripotent stem cell-derived exosomes (iPSC-Exos) and neural progenitor cell-derived exosomes (NPC-Exos) significantly reduced the cerebral infarct volume (%); Umbilical cord mesenchymal stem cell-derived exosomes (UCMSC-Exos) significantly reduced the mNSS; and there was no significant difference between urogenital stem cell-derived exosomes (USC-Exos) and negative controls. Engineered modified exosomes had better efficacy than unmodified exosomes. Both allogeneic and xenogeneic stem cell-derived exosomes significantly reduced the cerebral infarct volume (%) and the mNSS. The network meta-analysis showed that intravenous administration was the best route of administration for reducing the cerebral infarct volume (%) and mNSS. Among the 10 types of stem cell-derived exosomes that were administered intravenously, BMSC-Exos were the best type for reducing the cerebral infarct volume (%) and the mNSS. Allogeneic exosomes had the best efficacy in reducing the cerebral infarct volume (%), whereas xenogeneic stem cell-derived exosomes had the best efficacy in reducing the mNSS. This meta-analysis, by integrating the available evidence, revealed that intravenous administration is the best route of administration, that BMSC-Exos are the best exosome type, that allogeneic exosomes have the best efficacy in reducing the cerebral infarct volume (%), and that xenogeneic exosomes have the best efficacy in reducing mNSS, which can provide options for preclinical studies. In the future, more high-quality randomized controlled animal experiments, especially direct comparative evidence, are needed to determine the optimal administration strategy for stem cell-derived exosomes for ischemic stroke. https://www.crd.york.ac.uk/PROSPERO/display_record.php?ID=CRD42024497333, PROSPERO, CRD42024497333.

First insights into the prevalence, genetic characteristics, and pathogenicity of Bacillus cereus from generations worldwide.

Bacillus cereus, a global threat, is one of the major causes of toxin-induced foodborne diseases. However, a comprehensive assessment of the prevalence and characteristics of B. cereus worldwide is still lacking. Here, we applied whole-genome sequence analysis to 191 B. cereus collected in Africa, America, Asia, Europe, and Oceania from the 1900s to 2022, finding that CC142 dominated the global B. cereus clonal complex. The results provided direct evidence that B. cereus could spread through the food chain and intercontinentally. B. cereus from different generations worldwide showed coherence in the antibiotic-resistant gene and virulence and biofilm gene profiles, although with high genomic heterogeneity. The BCI-BCII-vanZF-fosB profiles and virulence and biofilm genes were detected at high rates, and we emphasized that B. cereus would pose a serious challenge to global public health and clinical treatment.IMPORTANCEThis study first emphasized the prevalence, genetic characteristics, and pathogenicity of Bacillus cereus worldwide from the 1900s to 2022 using whole-genome sequence analysis. The CC142 dominated the global Bacillus cereus clonal complex. Moreover, we revealed a close evolutionary relationship between the isolates from different sources. B. cereus isolates from different generations worldwide showed coherence in potential pathogenicity, although with high genomic heterogeneity. The BCI-BCII-vanZF-fosB profiles and virulence and biofilm genes were detected at high rates, and we emphasized that B. cereus would pose a serious challenge to global public health and clinical treatment.

Unraveling key environmental drivers of spatial variation in plant functional traits: Insights from Dacrydium pectinatum de Laub. in natural communities on Hainan Island, China

Accurate predictions of species distribution and coexistence in response to environmental changes depend on a thorough understanding of how functional traits relate to environmental conditions. However, there is still limited evidence regarding the sources of functional trait variation and the environmental mechanisms that regulate these traits in tropical forests. This study focuses on Dacrydium pectinatum de Laub., a crucial and endangered species native to the tropical mountain forests of Hainan Island, China. We gathered functional trait data from 68 permanent plots of D. pectinatum situated in three regions: Bawangling (163 tree species), Diaoluoshan (127 tree species), and Jianfengling (175 tree species). Nine functional traits were measured at the species level, and their variation patterns and sources were analyzed using linear mixed-effects models and variance decomposition methods. Our findings reveal that environmental pressures cause variations in trait relationships across different site conditions at the species level. Typically, inter-specific trait variation exceeds intra-specific variation, particularly for leaf area (LA) and specific leaf area (SLA). This indicates that trait variability is influenced by how species adapt to and balance specific environmental conditions. Site conditions significantly impact trait variation, especially for SLA, leaf dry matter content (LDMC), and wood density (WD). Additionally, intraspecific variation is notable for certain traits, reflecting individual responses to environmental heterogeneity. At the community level, eight out of nine traits exhibit significant changes in community-weighted mean (CWM) across various site conditions and environmental gradients. For instance, LA's CWM increases with soil fertility, whereas SLA, leaf nitrogen content (LNC), and leaf phosphorus content (LPC) show differences between site conditions. LDMC and WD decrease significantly in high-fertility environments, suggesting a transition from resource conservation to resource acquisition strategies within communities as soil fertility rises. Geographic variables play a crucial role in trait distributions across different community levels, with elevation and soil factors also contributing significantly to trait variation. Overall, our study provides direct evidence of how environmental filtering influences plant functional trait distributions and community assembly. Future research should explore the mechanisms driving these trait-environment relationships and their responses across various ecological contexts.

Does working memory training in children need to be adaptive? A randomized controlled trial.

Most cognitive training programs are adaptive, despite limited direct evidence that this maximizes children's outcomes. This randomized controlled trial evaluated working memory training with difficulty of activities presented using adaptive, self-select, or stepwise compared with an active control. At baseline, immediately, and 6-months post-intervention, 201 Australian primary school children (101 males, 7-11 years) completed working memory tests (near and intermediate transfer) and the Raven's Standard Progressive Matrices, and caregivers completed the attention-deficit/hyperactivity disorder-Rating Scale-5 (far transfer). The intervention comprised ten 20-min sessions delivered in class. For each training condition, compared with the active control, there was no evidence of transfer immediately or 6-months post-intervention (negligible to small effects). This trial provides no evidence that adaptive working memory training maximizes children's outcomes.

Dissected antiporter modules establish minimal proton-conduction elements of the respiratory complex I

The respiratory Complex I is a highly intricate redox-driven proton pump that powers oxidative phosphorylation across all domains of life. Yet, despite major efforts in recent decades, its long-range energy transduction principles remain highly debated. We create here minimal proton-conducting membrane modules by engineering and dissecting the key elements of the bacterial Complex I. By combining biophysical, biochemical, and computational experiments, we show that the isolated antiporter-like modules of Complex I comprise all functional elements required for conducting protons across proteoliposome membranes. We find that the rate of proton conduction is controlled by conformational changes of buried ion-pairs that modulate the reaction barriers by electric field effects. The proton conduction is also modulated by bulky residues along the proton channels that are key for establishing a tightly coupled proton pumping machinery in Complex I. Our findings provide direct experimental evidence that the individual antiporter modules are responsible for the proton transport activity of Complex I. On a general level, our findings highlight electrostatic and conformational coupling mechanisms in the modular energy-transduction machinery of Complex I with distinct similarities to other enzymes.

Disruption of mgrB gene by ISkpn14 sourced from a blaKPC−2 carrying plasmid mediating polymyxin resistance against carbapenem-resistant Klebsiella pneumoniae during treatment: study on the underlying mechanisms

BackgroundCarbapenem-resistant Klebsiella pneumoniae (CRKP) infections poses global challenges, with limited options available for targeted therapy. Polymyxin was been regarded as one of the most important last-resort antimicrobial agents. Many factors could accelerate the resistance evolution of polymyxin. Insertion sequence (IS) inserted into mgrB is the main polymyxin resistance mechanism in K. pneumoniae. In this study, two CRKPs (KP31157 and KP31311) were isolated from the urine of a patient, shifting from susceptible to resistant as the mgrB inserted by ISkpn14. We intended to explore the origin of the IS and underlying mechanisms resulting in polymyxin resistance.MethodsThe within-host evolution relationship and molecular features of both CRKPs were determined by pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS). pKP31311_KPC-2 plasmid genome structures contained in the above two CRKPs were aligned with the homologic plasmids, retrieved from the NCBI genome database via comparative genomic analysis. The plasmids encoding ISkpn14 elements flanked by direct repeat (DR) or not were analyzed. The mRNA expression, plasmid curing and in vitro antibiotics inducing experiment were employed to understand the potential mechanism of polymyxin resistance.ResultsBoth strains, sharing homology, exhibited polymyxin resistance due to the insertion of ISkpn14 into the mgrB gene, influenced by minocycline exposure. Minocycline and tigecycline could accelerate polymyxin resistance (P < 0.05), validated by an in vitro induction experiment. The ISkpn14 without DR flanked expressed about 4 times higher than that with DR. The frequency of the mgrB insertion induced by polymyxin was significantly reduced (0 strain detected) after the blaKPC−2-carrying plasmid was eliminated.ConclusionsThis study provides direct experimental evidence that the ISkpn14 element causing mgrB inactivation and polymyxin resistance in K. pneumoniae originates from blaKPC−2-carrying plasmids. Minocycline exposure will accelerate the evolution of polymyxin resistance. Understanding the dynamics of IS transposition and its association with antibiotic exposure is crucial for developing effective strategies to reduce the emergence of polymyxin resistance in CRKP.

Do elephants really never forget? What we know about elephant memory and a call for further investigation.

Despite popular culture's promotion of the elephant's ability to "never forget," there is remarkably limited empirical research on the memory capacities of any living elephant species (Asian, Elephas maximus; African savanna, Loxodonta africana; African forest, Loxodonta cyclotis). A growing body of literature on elephant cognition and behavioral ecology has provided insight into the elephant's ability to behave flexibly in changing physical and social environments, but little direct evidence of how memory might relate to this flexibility exists. In this paper, we review and discuss the potential relationships between what we know about elephant cognition and behavior and the elephants' memory for the world around them as they navigate their physical, social, and spatial environments. We also discuss future directions for investigating elephant memory and implications for such research on elephant conservation and human-elephant conflict mitigation.

Significant improvement in the removal performance of decimeter-sized zero-valent iron plates for mixed heavy metal ions in wastewater by enhancing surface sharpness

This study aims to lower the work function (Wa) of a decimeter-sized zero-valent iron plate (DZVIP) by introducing surface sharpness (TDZVIP) during stirring. Sharpness was achieved by cutting isosceles triangles with heights of 1 cm and varying apex angles (α) of 10˚, 20˚, 30˚, 40˚, and 50˚. A mixed simulated wastewater containing Cu(II), Te(IV), Se(IV), As(III), Bi(III), and Pb(II) at concentrations exceeding emission standards was prepared. Results indicate that the removal process exhibits mixed kinetic behavior, and sharpness significantly enhances the removal capacity (Re), mean removal rate (Vm), recycling performance, and final discharge quality. The Vm values for Cu(II), Te(IV), Se(IV), As(III), Bi(III), and Pb(II) over TDZVIP with optimized α are 2.34, 1.97, 1.51, 1.59, 4.09, and 1.53 times higher, respectively, than those over PDZVIP (without sharpness). UPS measurements provide direct evidence of Wa reduction, while XRD offers indirect confirmation. This is the first time the Wa of the amorphous shell has been identified and verified as a critical potential barrier for core electrons transferring from the DZVIP surface to wastewater. Additionally, it has been successfully reduced by incorporating surface sharpness and stirring, leading to enhanced removal efficiency, improved recycling performance, and higher final discharge quality.

Coherent optical spin Hall transport for polaritonics at room temperature.

Spin or valley degrees of freedom hold promise for next-generation spintronics. Nonetheless, the macroscopic coherent spin current formations are still hindered by rapid dephasing due to electron scattering, specifically at room temperature. Exciton polaritons offer excellent platforms for spin-optronic devices via the optical spin Hall effect. However, this effect could neither be unequivocally observed at room temperature nor be exploited for practical spintronic devices due to the presence of strong thermal fluctuations or large linear spin splitting. Here we report the observation of room-temperature optical spin Hall effect of exciton polaritons, with the spin current flow over 60 μm in a formamidinium lead bromide perovskite microcavity. We provide direct evidence of long-range coherence in the flow of polaritons and the spin current carried by them. Leveraging the spin Hall transport of polaritons, we further demonstrate two polaritonic devices, namely, a NOT gate and a spin-polarized beamsplitter, advancing the frontier of room-temperature polaritonics in perovskite microcavities.

Direct Evidence of Breakdown of Spin Statistics in Ion-Atom Charge Exchange Collisions.

Recent experimental studies have questioned the validity of spin statistics assumptions, particularly in charge exchange processes occurring in atomic MeV collisions. Here, we study spin-resolved single electron capture processes in collisions between C^{3+} ions and helium within an energy range of 1.25-400 keV/u. Using high resolution reaction microscope and multielectronic theoretical approaches, we directly measure and calculate the true population information of the C^{2+}(1s^{2}2s2p ^{1,3}P) states at the time of electron capture, overcoming the previous experimental and theoretical difficulties. At the level of integral and scattering angle differential cross sections, our results demonstrate the breakdown of pure spin statistics arguments, especially at high impact energies where they are traditionally expected to be valid. These novel findings and conclusions raise intriguing questions both in the understanding of the electronic dynamics during such fast collisional processes and in exploring quantum manipulation of atomic and molecular reactivity.

Dysregulated balance of D- and L-amino acids modulating glutamatergic neurotransmission in severe spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by reduced expression of the survival motor neuron (SMN) protein. In addition to motor neuron survival, SMN deficiency affects the integrity and function of afferent synapses that provide glutamatergic excitatory drive essential for motor neuron firing and muscle contraction. However, it is unknown whether deficits in the metabolism of excitatory amino acids and their precursors contribute to neuronal dysfunction in SMA. To address this issue, we measured the levels of the main neuroactive D- and L-amino acids acting on glutamatergic receptors in the central nervous system of SMNΔ7 mice as well as the cerebrospinal fluid (CSF) of SMA patients of varying severity before and after treatment with the SMN-inducing drug Nusinersen. Our findings reveal that SMN deficiency disrupts glutamate and serine metabolism in the CSF of severe SMA patients, including decreased concentration of L-glutamate, which is partially corrected by Nusinersen therapy. Moreover, we identify dysregulated L-glutamine to L-glutamate conversion as a shared neurochemical signature of altered glutamatergic synapse metabolism that implicates astrocyte dysfunction in both severe SMA patients and mouse models. Lastly, consistent with a correlation of higher CSF levels of D-serine with better motor function in severe SMA patients, we show that daily supplementation with the NMDA receptor co-agonist D-serine improves neurological deficits in SMNΔ7 mice. Altogether, these findings provide direct evidence for dysregulation of D- and L-amino acid metabolism linked to glutamatergic neurotransmission in severe SMA and have potential implications for treating this neurological disorder.

Direct and Inverse Photoelectron Spectroscopy Evidence for a Revised Picture of Electronic States of Negative Polarons in n‐Doped C60

AbstractDetermining the electronic levels associated with polarons, the fundamental charge carriers in organic semiconductors, is key to understanding the charge transport properties of these materials. Recent findings challenge the traditional view of these electronic levels by highlighting the importance of intra‐molecular Coulomb interactions in polarons. Experimental evidence was previously presented for a revised model of the negative polaron in the case of the polymer semiconductor poly(NDI2OD‐T2); there, the addition of an excess electron was seen to lead to the emergence of a singly occupied state within the energy gap of the undoped material and an unoccupied state above the edge of the conduction states. Here, focus is on a small‐molecule semiconductor, C60, and spectral evidence is provided of a similar picture for the new states appearing upon polaron formation. Specifically, direct and inverse photoemission spectroscopy is used to investigate the density of states in C60 films n‐doped with two dimeric dopants. The Coulomb interaction energy (Hubbard U) of the C60 anion is experimentally determined to be ≈1.1 eV, a value that aligns closely with theoretical predictions.