Streptomyces umbrella toxin particles block hyphal growth of competing species.

Streptomyces are a genus of ubiquitous soil bacteria from which the majority of clinically utilized antibiotics derive1. The production of these antibacterial molecules reflects the relentless competition Streptomyces engage in with other bacteria, including other Streptomyces species1,2. Here we show that in addition to small-molecule antibiotics, Streptomyces produce and secrete antibacterial protein complexes that feature a large, degenerate repeat-containing polymorphic toxin protein. A cryo-electron microscopy structure of these particles reveals an extended stalk topped by a ringed crown comprising the toxin repeats scaffolding five lectin-tipped spokes, which led us to name them umbrella particles. Streptomyces coelicolor encodes three umbrella particles with distinct toxin and lectin composition. Notably, supernatant containing these toxins specifically and potently inhibits the growth of select Streptomyces species from among a diverse collection of bacteria screened. For one target, Streptomyces griseus, inhibition relies on a single toxin and that intoxication manifests as rapid cessation of vegetative hyphal growth. Our data show that Streptomyces umbrella particles mediate competition among vegetative mycelia of related species, a function distinct from small-molecule antibiotics, which are produced at the onset of reproductive growth and act broadly3,4. Sequence analyses suggest that this role of umbrella particles extends beyond Streptomyces, as we identified umbrella loci in nearly 1,000 species across Actinobacteria.

Epitranscriptional m6A modification of rRNA negatively impacts translation and host colonization in Staphylococcus aureus.

Macrolides, lincosamides, and streptogramin B (MLS) are structurally distinct molecules that are among the safest antibiotics for prophylactic use and for the treatment of bacterial infections. The family of erythromycin resistance methyltransferases (Erm) invariantly install either one or two methyl groups onto the N6,6-adenosine of 2058 nucleotide (m6A2058) of the bacterial 23S rRNA, leading to bacterial cross-resistance to all MLS antibiotics. Despite extensive structural studies on the mechanism of Erm-mediated MLS resistance, how the m6A epitranscriptomic mark affects ribosome function and bacterial physiology is not well understood. Here, we show that Staphylococcus aureus cells harboring m6A2058 ribosomes are outcompeted by cells carrying unmodified ribosomes during infections and are severely impaired in colonization in the absence of an unmodified counterpart. The competitive advantage of m6A2058 ribosomes is manifested only upon antibiotic challenge. Using ribosome profiling (Ribo-Seq) and a dual-fluorescence reporter to measure ribosome occupancy and translational fidelity, we found that specific genes involved in host interactions, metabolism, and information processing are disproportionally deregulated in mRNA translation. This dysregulation is linked to a substantial reduction in translational capacity and fidelity in m6A2058 ribosomes. These findings point to a general "inefficient translation" mechanism of trade-offs associated with multidrug-resistant ribosomes.

Genome-wide enhancer identification by massively parallel reporter assay in Arabidopsis.

Enhancers are critical cis-regulatory elements controlling gene expression during cell development and differentiation. However, genome-wide enhancer characterization has been challenging due to the lack of a well-defined relationship between enhancers and genes. Function-based methods are the gold standard for determining the biological function of cis-regulatory elements; however, these methods have not been widely applied to plants. Here, we applied a massively parallel reporter assay on Arabidopsis to measure enhancer activities across the genome. We identified 4327 enhancers with various combinations of epigenetic modifications distinctively different from animal enhancers. Furthermore, we showed that enhancers differ from promoters in their preference for transcription factors. Although some enhancers are not conserved and overlap with transposable elements forming clusters, enhancers are generally conserved across thousand Arabidopsis accessions, suggesting they are selected under evolution pressure and could play critical roles in the regulation of important genes. Moreover, comparison analysis reveals that enhancers identified by different strategies do not overlap, suggesting these methods are complementary in nature. In sum, we systematically investigated the features of enhancers identified by functional assay in A. thaliana, which lays the foundation for further investigation into enhancers' functional mechanisms in plants.

Serum levels of vitamin B12 combined with folate and plasma total homocysteine predict ischemic stroke disease: a retrospective case-control study.

PURPOSE: This study aimed to identify and quantify the association and investigate whether serum vitamin B12 alone or vitamin B12 combined with folate and plasma total homocysteine (tHcy) levels could be used to predict the risk of acute ischemic stroke. MATERIALS AND METHODS: This retrospective case-control study was conducted in the Department of Neurology, First Affiliated Hospital of Chongqing Medical University. It included 259 inpatients experiencing their first-ever acute ischemic stroke and 259 age-matched, sex-matched healthy controls. Patients were categorized into groups based on the etiology of their stroke: large-artery atherosclerosis (LAAS, n = 126), cardio embolism (CEI, n = 35), small vessel disease (SVD, n = 89), stroke of other determined etiology (ODE, n = 5), and stroke of undetermined etiology (UDE, n = 4). The associations of serum vitamin B12, folate, and plasma tHcy levels with the risk of ischemic stroke were evaluated using multivariable logistic regression analysis. Receiver operator characteristic (ROC) curves were used to assess the diagnostic power of vitamin B12, folate, and tHcy levels for ischemic stroke. RESULTS: Serum vitamin B12 and folate levels were significantly lower in ischemic stroke patients compared to controls, while plasma tHcy levels were significantly higher. The first quartile of serum vitamin B12 levels was significantly associated with an increased risk of LAAS (aOR = 2.289, 95% CI = 1.098-4.770), SVD (aOR = 4.471, 95% CI = 1.110-4.945) and overall ischemic stroke (aOR = 3.216, 95% CI = 1.733-5.966). Similarly, the first quartile of serum folate levels was associated with an increased risk of LAAS (aOR = 3.480, 95% CI = 1.954-6.449), CEI (aOR = 2.809, 95% CI = 1.073-4.991), SVD (aOR = 5.376, 95% CI = 1.708-6.924), and overall ischemic stroke (aOR = 3.381, 95% CI = 1.535-7.449). The fourth quartile of tHcy levels was also significantly associated with an increased risk of LAAS (aOR = 2.946, 95% CI = 1.008-5.148), CEI (aOR = 2.212, 95% CI = 1.247-5.946), SVD (aOR = 2.957, 95% CI = 1.324-6.054), and overall ischemic stroke (aOR = 2.233, 95% CI = 1.586-4.592). For predicting different types of ischemic stroke, vitamin B12 alone demonstrated the best diagnostic value for SVD, evidenced by a sensitivity of 71.0% and negative predictive value of 90.3%, along with the highest positive likelihood ratio (+ LR) for SVD. Vitamin B12 + tHcy + folate are valuable in predicting different types of ischemic stroke, with the most significant effect observed in SVD, followed by LAAS, and the weakest predictive effect in CEI. Additionally, vitamin B12 alone in combination with other indicators, such as folate alone, tHcy alone, and folate + tHcy could reduce negative likelihood ratio (-LR) and improve + LR. CONCLUSIONS: Vitamin B12 was an independent risk factor for acute ischemic stroke. The risk calculation model constructed with vitamin B12 + tHcy + folate had the greatest diagnostic value for SVD.

Natural variation in the HAN1 gene confers chilling tolerance in rice and allowed adaptation to a temperate climate.

Rice (Oryza sativa L.) is a chilling-sensitive staple crop that originated in subtropical regions of Asia. Introduction of the chilling tolerance trait enables the expansion of rice cultivation to temperate regions. Here we report the cloning and characterization of HAN1, a quantitative trait locus (QTL) that confers chilling tolerance on temperate japonica rice. HAN1 encodes an oxidase that catalyzes the conversion of biologically active jasmonoyl-L-isoleucine (JA-Ile) to the inactive form 12-hydroxy-JA-Ile (12OH-JA-Ile) and fine-tunes the JA-mediated chilling response. Natural variants in HAN1 diverged between indica and japonica rice during domestication. A specific allele from temperate japonica rice, which gained a putative MYB cis-element in the promoter of HAN1 during the divergence of the two japonica ecotypes, enhances the chilling tolerance of temperate japonica rice and allows it to adapt to a temperate climate. The results of this study extend our understanding of the northward expansion of rice cultivation and provide a target gene for the improvement of chilling tolerance in rice.

Genomic and in vitro pharmacodynamic analysis of rifampicin resistance in multidrug-resistant canine Staphylococcus pseudintermedius isolates.

BACKGROUND: Antimicrobial resistance is a growing concern in canine Staphylococcus pseudintermedius dermatitis. Treatment with rifampicin (RFP) is considered only in meticillin-resistant and multidrug-resistant S. pseudintermedius (MDR-MRSP). HYPOTHESIS/OBJECTIVES: To determine an optimal RFP dosing for MDR-MRSP treatment without induction of RFP resistance and identify causal mutations for antimicrobial resistance. METHODS AND MATERIALS: Time-kill assays were performed in a control isolate and three MDR-MRSP isolates at six clinically relevant concentrations [32 to 1,024 × MIC (the minimum inhibitory concentration)]. Whole-genome resequencing and bioinformatic analysis were performed in the resistant strains developed in this assay. RESULTS: The genomic analysis identified nine antimicrobial resistance genes (ARGs) in MDR-MRSP isolates, which are responsible for resistance to seven classes of antibiotics. RFP activity against all four isolates was consistent with a time-dependent and bacteriostatic response. RFP resistance was observed in six of the 28 time-kill assays, including concentrations 64 × MIC in MDR-MRSP1 isolates at 24 h, 32 × MIC in MDR-MRSP2 at 48 h, 32 × MIC in MDR-MRSP3 at 48 h and 256 × MIC in MDR-MRSP3 at 24 h. Genome-wide mutation analyses in these RFP-resistant strains discovered the causal mutations in the coding region of the rpoB gene. CONCLUSIONS AND CLINICAL RELEVANCE: A study has shown that 6 mg/kg per os results in plasma concentrations of 600-1,000 × MIC of S. pseudintermedius. Based on our data, this dose should achieve the minimum MIC (×512) to prevent RFP resistance development; therefore, we recommend a minimum daily dose of 6 mg/kg for MDR-MRSP pyoderma treatment when limited antibiotic options are available.

Genetic architecture of subspecies divergence in trace mineral accumulation and elemental correlations in the rice grain.

KEY MESSAGE: Genome differentiation has shaped the divergence in element concentration between rice subspecies and contributed to the correlation among trace minerals in the rice grain. The balance between trace minerals in rice, a staple food for more than half of the world's population, is crucial for human health. However, the genetic basis underlying the correlation between trace minerals has not been fully elucidated. To address this issue, we first quantified the concentrations of 11 trace minerals in the grains of a diversity panel of 575 rice cultivars. We found that eight elements were accumulated at significantly different levels between the indica and japonica subspecies, and we also observed significant correlation patterns among a number of elements. Further, using a genome-wide association study, we identified a total of 96 significant association loci (SALs). The differentiation of the major-effect SALs along with the different number of high-concentration alleles present in the two subspecies shaped the different element performance in indica and japonica varieties. Only a few SALs located in clusters and the majority of SALs showed subspecies/subgroup differentiation, indicating that the correlations between elements in the diversity panel were mainly caused by genome differentiation instead of shared genetic basis. The genetic architecture unveiled in this study will facilitate improvement in breeding for trace mineral content.

E-Jet 3D-Printed Scaffolds as Sustained Multi-Drug Delivery Vehicles in Breast Cancer Therapy.

PURPOSE: Combination chemotherapy is gradually receiving more attention because of its potential synergistic effect and reduced drug doses in clinical application. However, how to precisely control drug release dose and time using vehicles remains a challenge. This work developed an efficient drug delivery system to combat breast cancer, which can enhance drug effects despite reducing its concentration. METHODS: Controlled-release poly-lactic-co-glycolic acid (PLGA) scaffolds were fabricated by E-jet 3D printing to deliver doxorubicin (DOX) and cisplatin (CDDP) simultaneously. RESULTS: This drug delivery system allowed the use of a reduced drug dosage resulting in a better effect on the human breast cancer cell apoptosis and inhibiting tumor growth, compared with the effect of each drug and the two drugs administrated without PLGA scaffolds. Our study suggested that DOX-CDDP-PLGA scaffolds could efficiently destroy MDA-MB-231 cells and restrain tumor growth. CONCLUSIONS: The 3D printed PLGA scaffolds with their time-programmed drug release might be useful as a new multi-drug delivery vehicle in cancer therapy, which has a potential advantage in a long term tumor cure and prevention of tumor recurrence.

The miR-134 attenuates the expression of transcription factor FOXM1 during pluripotent NT2/D1 embryonal carcinoma cell differentiation.

Transcription factor FOXM1 plays a critical role in maintenance of stem cell pluripotency through stimulating the transcription of pluripotency-related genes in mouse pluripotent stem cells. In this study, we have found that the repression of FOXM1 expression is mediated by FOXM1 3'UTR during retinoic acid-induced differentiation of human pluripotent NT2/D1 embryonal carcinoma cells. FOXM1 3'UTR contains a microRNA response element (MRE) for miR-134, which has been shown to attenuate the expression of pluripotency-related genes post-transcriptionally during mouse embryonic stem cell differentiation. We have determined that miR-134 is induced during RA-induced differentiation of NT2/D1 cells and the overexpression of miR-134 represses the expression of FOXM1 protein but not FOXM1 mRNA. Furthermore, the expression of OCT4 is diminished by FOXM1 knockdown and the OCT4 promoter is regulated directly by FOXM1, suggesting that FOXM1 is required for maintaining the expression of OCT4 in NT2/D1 cells. Together, our results suggest that FOXM1 is essential for human pluripotent stem cells and miR-134 attenuates its expression during differentiation.

Ultrasensitive detection of single nucleotide polymorphism in human mitochondrial DNA utilizing ion-mediated cascade surface-enhanced Raman spectroscopy amplification.

Although surface-enhanced Raman spectroscopy (SERS) has been featured by high sensitivity, additional signal enhancement is still necessary for trace amount of biomolecules detection. In this paper, a SERS amplified approach, featuring "ions-mediated cascade amplification (IMCA)", was proposed by utilizing the dissolved silver ions (Ag(+)) from silver nanoparticles (AgNPs). We found that using Ag(+) as linkage agent can effectively control the gaps between neighboring 4-aminobenzenethiol (4-ABT) encoded gold nanoparticles (AuNPs@4-ABT) to form "hot spots" and thus produce SERS signal output, in which the SERS intensity was proportional to the concentration of Ag(+). Inspired by this finding, the IMCA was utilized for ultrasensitive detection of single nucleotide polymorphism in human mitochondrial DNA (16189T → C). Combining with the DNA ligase reaction, each target DNA binding event could successfully cause one AgNP introduction. By detecting the dissolved Ag(+) from AgNPs using IMCA, low to 3.0 × 10(-5) fm/µL targeted DNA can be detected, which corresponds to extractions from 200 nL cell suspension containing carcinoma pancreatic ß-cell lines from diabetes patients. This IMCA approach is expected to be a universal strategy for ultrasensitive detection of analytes and supply valuable information for biomedical research and clinical early diagnosis.

Foxa1 contributes to the repression of Nanog expression by recruiting Grg3 during the differentiation of pluripotent P19 embryonal carcinoma cells.

Transcription factor Foxa1 plays a critical role during neural differentiation and is induced immediately after retinoic acid (RA)-initiated differentiation of pluripotent P19 embryonal carcinoma cells, correlated with the downregulated expression of pluripotency-related genes such as Nanog. To study whether Foxa1 participates in the repression of pluripotency factors, we expressed Foxa1 ectopically in P19 cells and identified that Nanog was repressed directly by Foxa1. We confirmed that Foxa1 was able to interact with Grg3, which is a transcriptional corepressor that expresses in P19 cells as well as during RA-induced P19 cell differentiation. Knockdown of Foxa1 or Grg3 delayed the downregulation of Nanog expression during RA-induced P19 cell differentiation. Furthermore, we found that Foxa1 recruited Grg3 to the Nanog promoter -2kb upstream region and switched the promoter to an inactive chromatin status represented by typical modifications in histone H3. Together, our results suggested a critical involvement of Foxa1 in the negative regulation of Nanog expression during the differentiation of pluripotent stem cells.

Genomic underpinnings of Cytoplasmic Incompatibility: CIF gene-neighborhood diversification through extensive lateral transfers and recombination in Wolbachia.

Cytoplasmic incompatibility (CI), a non-Mendelian genetic phenomenon, involves manipulation of host reproduction by Wolbachia, a maternally transmitted alphaproteobacterium. The underlying mechanism is centered around the CIF system governed by two genes, cifA and cifB, where cifB induces embryonic lethality, and cifA counteracts it. Recent investigations have unveiled intriguing facets of this system, including diverse cifB variants, prophage association in specific strains, copy-number variation, and rapid component divergence, hinting at a complex evolutionary history. We utilized comparative genomics to systematically classify CIF systems, analyze their locus structure and domain architectures, and reconstruct their diversification and evolutionary trajectories. Our new classification identifies ten distinct CIF types, featuring not just versions present in Wolbachia, but also other intracellular bacteria, and eukaryotic hosts. Significantly, our analysis of CIF loci reveals remarkable variability in gene composition and organization, encompassing an array of diverse endonucleases, variable toxin domains, deubiquitinating peptidases (DUBs), prophages, and transposons. We present compelling evidence that the components within the loci have been diversifying their sequences and domain architectures through extensive, independent lateral transfers and inter-locus recombination involving gene conversion. The association with diverse transposons and prophages, coupled with selective pressures from host immunity, likely underpins the emergence of CIF loci as recombination hotspots. Our investigation also posits the origin of CifB-REase domains from mobile elements akin to CR-effectors and Tribolium Medea1 factor, which is linked to another non-Mendelian genetic phenomenon. This comprehensive genomic analysis offers novel insights into the molecular evolution and genomic foundations of Wolbachia-mediated host reproductive control.

Machine learning-based classification reveals distinct clusters of non-coding genomic allelic variations associated with Erm-mediated antibiotic resistance.

The erythromycin resistance RNA methyltransferase (erm) confers cross-resistance to all therapeutically important macrolides, lincosamides, and streptogramins (MLS phenotype). The expression of erm is often induced by the macrolide-mediated ribosome stalling in the upstream co-transcribed leader sequence, thereby triggering a conformational switch of the intergenic RNA hairpins to allow the translational initiation of erm. We investigated the evolutionary emergence of the upstream erm regulatory elements and the impact of allelic variation on erm expression and the MLS phenotype. Through systematic profiling of the upstream regulatory sequences across all known erm operons, we observed that specific erm subfamilies, such as ermB and ermC, have independently evolved distinct configurations of small upstream ORFs and palindromic repeats. A population-wide genomic analysis of the upstream ermB regions revealed substantial non-random allelic variation at numerous positions. Utilizing machine learning-based classification coupled with RNA structure modeling, we found that many alleles cooperatively influence the stability of alternative RNA hairpin structures formed by the palindromic repeats, which, in turn, affects the inducibility of ermB expression and MLS phenotypes. Subsequent experimental validation of 11 randomly selected variants demonstrated an impressive 91% accuracy in predicting MLS phenotypes. Furthermore, we uncovered a mixed distribution of MLS-sensitive and MLS-resistant ermB loci within the evolutionary tree, indicating repeated and independent evolution of MLS resistance. Taken together, this study not only elucidates the evolutionary processes driving the emergence and development of MLS resistance but also highlights the potential of using non-coding genomic allele data to predict antibiotic resistance phenotypes. IMPORTANCE: Antibiotic resistance (AR) poses a global health threat as the efficacy of available antibiotics has rapidly eroded due to the widespread transmission of AR genes. Using Erm-dependent MLS resistance as a model, this study highlights the significance of non-coding genomic allelic variations. Through a comprehensive analysis of upstream regulatory elements within the erm family, we elucidated the evolutionary emergence and development of AR mechanisms. Leveraging population-wide machine learning (ML)-based genomic analysis, we transformed substantial non-random allelic variations into discernible clusters of elements, enabling precise prediction of MLS phenotypes from non-coding regions. These findings offer deeper insight into AR evolution and demonstrate the potential of harnessing non-coding genomic allele data for accurately predicting AR phenotypes.

Characterizing Vitamin B12 Deficiency in Neurology Outpatients: A Retrospective Observational Study.

OBJECTIVES: Clinical manifestations of vitamin B12 deficiency are varied and may result in missed or delayed diagnosis. This investigation explores the diverse clinical manifestations and demographic characteristics of vitamin B12 deficiency in neurology outpatients, aiming to enhance timely diagnosis and outcomes. METHODS: The severity of vitamin B12 deficiency was classified as absolute (≤150 pg/mL) or borderline deficiency (150-300 pg/mL). We conducted a retrospective analysis of 165 outpatients with vitamin B12 deficiency at the department of neurology between May 2020 and May 2021. RESULT: Absolute vitamin B12 deficiency was found in 23.0% of the patients. The most common age range was 50-60 years, the most common cause was vegetarianism, and the most common symptom was headache. Epileptiform symptoms were more likely to occur in younger patients (<20 years old) with vitamin B12 deficiency, whereas psychiatric symptoms were more likely to occur in older patients (>70 years old). Vegetarians, salivation, and nonmegaloblastic anemia were more obvious in patients with absolute vitamin B12 deficiency, whereas headaches often showed borderline B12 deficiency. CONCLUSIONS: The clinical characteristics of vitamin B12 deficiency are complex and nonspecific. The diagnosis should be based on multiple factors.

Developing and Validating a Nomogram Model for Predicting Ischemic Stroke Risk.

Background and purpose: Clinically, the ability to identify individuals at risk of ischemic stroke remains limited. This study aimed to develop a nomogram model for predicting the risk of acute ischemic stroke. Methods: In this study, we conducted a retrospective analysis on patients who visited the Department of Neurology, collecting important information including clinical records, demographic characteristics, and complete hematological tests. Participants were randomly divided into training and internal validation sets in a 7:3 ratio. Based on their diagnosis, patients were categorized as having or not having ischemic stroke (ischemic and non-ischemic stroke groups). Subsequently, in the training set, key predictive variables were identified through multivariate logistic regression and least absolute shrinkage and selection operator (LASSO) regression methods, and a nomogram model was constructed accordingly. The model was then evaluated on the internal validation set and an independent external validation set through area under the receiver operating characteristic curve (AUC-ROC) analysis, a Hosmer-Lemeshow goodness-of-fit test, and decision curve analysis (DCA) to verify its predictive efficacy and clinical applicability. Results: Eight predictors were identified: age, smoking status, hypertension, diabetes, atrial fibrillation, stroke history, white blood cell count, and vitamin B12 levels. Based on these factors, a nomogram with high predictive accuracy was constructed. The model demonstrated good predictive performance, with an AUC-ROC of 0.760 (95% confidence interval [CI]: 0.736-0.784). The AUC-ROC values for internal and external validation were 0.768 (95% CI: 0.732-0.804) and 0.732 (95% CI: 0.688-0.777), respectively, proving the model's capability to predict the risk of ischemic stroke effectively. Calibration and DCA confirmed its clinical value. Conclusions: We constructed a nomogram based on eight variables, effectively quantifying the risk of ischemic stroke.

Development of a Predictive Nomogram for Intra-Hospital Mortality in Acute Ischemic Stroke Patients Using LASSO Regression.

Background and Purpose: Ischemic stroke is a leading cause of mortality and disability globally, necessitating accurate prediction of intra-hospital mortality (IHM) for improved patient care. This study aimed to develop a practical nomogram for personalized IHM risk prediction in ischemic stroke patients. Methods: A retrospective study of 422 ischemic stroke patients (April 2020 - December 2021) from Chongqing Medical University's First Affiliated Hospital was conducted, with patients divided into training (n=295) and validation (n=127) groups. Data on demographics, comorbidities, stroke risk factors, and lab results were collected. Stroke severity was assessed using NIHSS, and stroke types were classified by TOAST criteria. Least absolute shrinkage and selection operator (LASSO) regression was employed for predictor selection and nomogram construction, with evaluation through ROC curves, calibration curves, and decision curve analysis. Results: LASSO regression and multivariate logistic regression identified four independent IHM predictors: age, admission NIHSS score, chronic obstructive pulmonary disease (COPD) diagnosis, and white blood cell count (WBC). A highly accurate nomogram based on these variables exhibited excellent predictive performance, with AUCs of 0.958 (training) and 0.962 (validation), sensitivities of 93.2% and 95.7%, and specificities of 93.1% and 90.9%, respectively. Calibration curves and decision curve analysis validated its clinical applicability. Conclusion: Age, admission NIHSS score, COPD history, and WBC were identified as independent IHM predictors in ischemic stroke patients. The developed nomogram demonstrated high predictive accuracy and practical utility for mortality risk estimation. External validation and prospective studies are warranted for further confirmation of its clinical efficacy.

[Molecular mechanism of cardiac differentiation in P19 embryonal carcinoma cells regulated by Foxa2].

OBJECTIVE: To investigate the involvement of transcription factor Foxa2 in cardiac differentiation in P19 embryonal carcinoma cells and its molecular mechanism. METHODS: P19 cells were induced to differentiate into cardiomyocytes by adding dimethyl sulfoxide (DMSO) into the culture medium of their embryoid bodies (EBs). The mRNA levels of pluripotency markers of embryonic pluripotent stem cells, cardiac differentiation related genes, and Foxa2 in the cell samples at different time points of cardiac differentiation were detected by reverse transcription PCR (RT-PCR). Differentiated and mature cardiomyocytes were identified by immunofluorescence. Eukaryotic expression plasmid pCMV-rFoxa2 (rat Foxa2) was transfected into P19 cells, and clonal populations of P19 cells that stably expressed green fluorescence protein (GFP)-rFoxa2 were isolated to enhance the expression levels of Foxa2 in P19 cells. The mRNA and protein levels of pluripotency markers and cardiac differentiation related genes in the above cell samples were detected by RT-PCR and Western blot. The mRNA levels of cardiac differentiation related genes in EBs differentiation system were also examined. RESULTS: P19 cells differentiated into cardiomyocytes in the presence of DMSO, accompanied by stimulated expression of Foxa2. Transfection of pCMV-rFoxa2 plasmids into P19 cells upregulated rFoxa2 expression transiently and activated the transcription of its downstream cardiac inducer Cerberus1 (Cer1). The expression of pluripotency marker Nanog was suppressed and the expression of cardiac inducer Sonic Hedgehog (Shh) was elevated in GFP-rFoxa2 P19 cells. The expression of Cer1 and cardiac muscle marker actin, alpha cardiac muscle 1 (Actc1) was upregulated in EBs of GFP-rFoxa2 P19 cells. CONCLUSION: Foxa2 participates in cardiac differentiation in P19 embryonal carcinoma cells. Foxa2 may inhibit Nanog expression and stimulate the expression of Cer1 and Shh directly during cardiac differentiation in P19 cells in the presence of DMSO.

Ribonuclease T2 represents a distinct circularly permutated version of the BECR RNases.

Detection of homologous relationships among proteins and understanding their mechanisms of diversification are major topics in the fields of protein science, bioinformatics, and phylogenetics. Recent developments in sequence/profile-based and structural similarity-based methods have greatly facilitated the unification and classification of many protein families into superfamilies or folds, yet many proteins remain unclassified in current protein databases. As one of the three earliest identified RNases in biology, ribonuclease T2, also known as RNase I in Escherichia coli, RNase Rh in fungi, or S-RNase in plant, is thought to be an ancient RNase family due to its widespread distribution and distinct structure. In this study, we present evidence that RNase T2 represents a circularly permutated version of the BECR (Barnase-EndoU-Colicin E5/D-RelE) fold RNases. This subtle relationship cannot be detected by traditional methods such as sequence/profile-based comparisons, structure-similarity searches, and circular permutation detections. However, we were able to identify the structural similarity using rational reconstruction of a theoretical RNase T2 ancestor via a reverse circular permutation process, followed by structural modeling using AlphaFold2, and structural comparisons. This relationship is further supported by the fact that RNase T2 and other typical BECR RNases, namely Colicin D, RNase A, and BrnT, share similar catalytic site configurations, all involving an analogous set of conserved residues on the α0 helix and the ß4 strand of the BECR fold. This study revealed a hidden root of RNase T2 in bacterial toxin systems and demonstrated that reconstruction and modeling of ancestral topology is an effective strategy to identify remote relationship between proteins.

Vitamin B12 supplementation improves cognitive function in middle aged and elderly patients with cognitive impairment.

Introduction: Objectives: to determine the effects of vitamin B12 supplementation on neuropsychological function and disease progression in middle aged and elderly patients with cognitive impairment. Methods: this was a prospective case-control study. From May 2020 to May 2021, 307 participants clinically diagnosed with cognitive impairment in the Department of Neurology of the First Affiliated Hospital of Chongqing Medical University were enrolled. A total of 115 patients were included in this study. Meanwhile, 115 participants with cognitive impairment were randomly assigned in equal proportions to two groups: vitamin B12 treatment group (n = 58, vitamin B12 500 mg/d intramuscularly for seven days, followed by cobamamide 0.25 mg/d and methylcobalamin 0.50 mg/d) and the control group (n = 57). Demographic characteristics and blood biochemical variables were obtained from all participants. Cognitive performance was measured using the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Cognitive performance was measured at baseline and after six months. Results: the vitamin B12 supplementation treatment patients who presented with cognitive impairment showed significant improvement, especially in attention, calculation (p < 0.01) and visual-constructional ability (p < 0.05), in their neuropsychological function compared to their matched group. Conclusion: vitamin B12 supplementation may improve frontal function in patients with cognitive decline. Vitamin B12 levels should be investigated in all patients with cognitive impairment.

Introducción: Objetivos: determinar los efectos de la suplementación con vitamina B12 en la función neuropsicológica y la progresión de la enfermedad en pacientes de mediana edad y adultos mayores con deterioro cognitivo. Métodos: se realizó un estudio prospectivo de casos y controles; se estudiaron 307 participantes, desde mayo de 2020 a mayo de 2021, diagnosticados clínicamente con deterioro cognitivo en el Departamento de Neurología, el Primer Hospital Anexado a la Universidad Médica de Chongqing. En el estudio se incluyeron un total de 115 pacientes con deterioro cognitivo que fueron asignados aleatoriamente en proporciones iguales a dos grupos: un grupo de tratamiento con vitamina B12 (n = 58, vitamina B12 500 mg/d intramuscular durante 7 días, seguido de cobamamida 0,25 mg/d y metilcobalamina 0,50 mg/d) y un grupo de control (n = 57). Se obtuvieron las características demográficas y las variables bioquímicas sanguíneas de todos los participantes. El rendimiento cognitivo se midió mediante el miniexamen del estado mental (MMSE) y la evaluación cognitiva de Montreal (Moca) al inicio del estudio y a los 6 meses. Resultados: los pacientes con deterioro cognitivo que recibieron tratamiento de suplementación con vitamina B12 mostraron una mejora significativa, especialmente en la atención, el cálculo (p < 0,01) y la capacidad visuoespacial (p < 0,05), en su función neuropsicológica en comparación con el grupo control. Conclusión: la suplementación con vitamina B12 puede mejorar la función frontal en pacientes con deterioro cognitivo. Los pacientes con deterioro cognitivo deben conocer sus propios niveles de vitamina B12.

Effects of vitamin B12 deficiency on risk and outcome of ischemic stroke.

Ischemic stroke is the most prevalent form of stroke and has a high incidence in older adults, characterized by high morbidity, mortality, disability, and recurrence rate. Vitamin B12 deficiency is prevalent in the elderly and has been reported to be associated with ischemic stroke. The mechanisms maybe include the disorder of methylation metabolism, accumulation of toxic metabolites, immune dysfunction, affecting gut microbial composition and gut-brain immune homeostasis, and toxic stress responses to the brain. Vitamin B12 deficiency may lead to cerebral artery atherosclerosis, change myelination, influence the metabolism and transmission between nerve tissue, and ultimately causes the occurrence and development of ischemic stroke. This paper reviews the correlation between vitamin B12 deficiency and ischemic stroke, looking forward to improving clinicians' understanding and providing new therapeutic directions for ischemic stroke.