Pseudomonas weihenstephanensis through the iron metabolism pathway promotes in situ spoilage capacity of prepared beef steaks during cold storage.

In this study, we evaluated the histomorphology, reactive oxygen species (ROS), protein degradation, and iron metabolism characteristics and differential expression analysis of genes for siderophores synthesis and protease secretion in prepared beef steaks inoculated alone or co-inoculated with P. weihenstephanensis, B. thermotrichothrix and M. caseolyticus at 4 °C for 12 days. The results showed that the P. weihenstephanensis was the key bacteria that degraded protein in the process of prepared beef steaks spoilage, which led to protein oxidation by promoting ferritin degradation to release free iron and inducing ROS accumulation. The highest expression of FpvA and AprE was detected in the P. weihenstephanensis group by comparing qRT-PCR of the different inoculation groups. Both qRT-PCR and Western blot revealed that ferritin heavy polypeptide and ferritin light chain polypeptide gene and protein expressions were significantly higher in the P. weihenstephanensis inoculation group compared to the other inoculation groups. Results suggested that FpvA and AprE might play roles in meat spoilage and were potential positional, physiological and functional candidate genes for improving the quality traits of prepared beef steaks. This work may provide insights on controlling food quality and safety by intervening in spoilage pathways targeting iron carrier biosynthesis or protease secretion genes.

Efficient Fresh Lamp Light-Harvesting Films with the Self-Activating Continuous and Recyclable Bactericidal Ability for Ultrapersistent Freshness of Perishable Muscle Food.

A large quantity of perishable muscle food is being wasted due to harmful bacteria infestation during the sales and circulation each year and facing challenges. In this study, a self-activated bactericidal active film (PLA/g-C3N4@PCN-224) responsive to fresh lamp light was prepared, which showed excellent hydrophobicity, water vapor resistance, and thermal stability. Due to the synergistic effect between light-induced reactive oxygen species and the high specific surface area of g-C3N4@PCN-224, this film still maintains 99.99% bactericidal efficacy against Escherichia coli and Staphylococcus aureus after 10 days of continuous bactericidal activity test. The results of cell and hemolysis experiments indicated that the film was safe and nontoxic and can effectively preserve fresh pork for 7 days. Moreover, the film also exhibited a recyclable and efficient killing activity. A strategy for achieving ultrapersistent freshness of perishable muscle food was provided.

Coexisting with Ice Crystals: Cryogenic Preservation of Muscle Food─Mechanisms, Challenges, and Cutting-Edge Strategies.

Cryopreservation, one of the most effective preservation methods, is essential for maintaining the safety and quality of food. However, there is no denying the fact that the quality of muscle food deteriorates as a result of the unavoidable production of ice. Advancements in cryoregulatory materials and techniques have effectively mitigated the adverse impacts of ice, thereby enhancing the standard of freezing preservation. The first part of this overview explains how ice forms, including the theoretical foundations of nucleation, growth, and recrystallization as well as the key influencing factors that affect each process. Subsequently, the impact of ice formation on the eating quality and nutritional value of muscle food is delineated. A systematic explanation of cutting-edge strategies based on nucleation intervention, growth control, and recrystallization inhibition is offered. These methods include antifreeze proteins, ice-nucleating proteins, antifreeze peptides, natural deep eutectic solvents, polysaccharides, amino acids, and their derivatives. Furthermore, advanced physical techniques such as electrostatic fields, magnetic fields, acoustic fields, liquid nitrogen, and supercooling preservation techniques are expounded upon, which effectively hinder the formation of ice crystals during cryopreservation. The paper outlines the difficulties and potential directions in ice inhibition for effective cryopreservation.

Next-generation meat preservation: integrating nano-natural substances to tackle hurdles and opportunities.

The increasing global meat demand raises concerns regarding the spoilage of meat caused by microbial invasion and oxidative decomposition. Natural substances, as a gift from nature to humanity, possess broad-spectrum bioactivity and have been utilized for meat preservation. However, their limited stability, solubility, and availability hinder their further development. To address this predicament, advanced organic nanocarriers provide an effective shelter for the formation of nano-natural substances (NNS). This review comprehensively presents various natural substances derived from plants, animals, and microorganisms, along with the challenges they face. Subsequently, the potential of organic nanocarriers is explored, highlighting their distinct features and applicability, in addressing these challenges. The review methodically examines the application of NNS in meat preservation, with a focus on their pathways of action and preservation mechanisms. Furthermore, the outlook and future trends for NNS applications in meat preservation are concluded. The theory and practice summary of NNS is expected to serve as a catalyst for advancements that enhance meat security, promote human health, and contribute to sustainable development.

Diversified organic nanocarriers conquer the limitations of natural substancesNNS based on organic nanocarriers are a reliable and health-promoting optionNNS can manifest their effectiveness through diverse pathways and mechanismsThe utilization of NNS in meat preservation represents a transformative strategy.

Recent advances in meat freshness "magnifier": fluorescence sensing.

To address the serious waste of meat resources and food safety problems caused by the decrease in meat freshness due to the action of microorganisms and enzymes, a low-cost, time-saving and high-efficiency freshness monitoring method is urgently needed. Fluorescence sensing could act as a "magnifier" for meat freshness monitoring due to its ability to sense characteristic signal produced by meat spoilage. Here, the magnification mechanism of meat freshness via sensing the water activity, adenosine triphosphate, hydrogen ion, total volatile basic nitrogen, hydrogen sulfide, bioamines was comprehensively analyzed. The existing "magnifier" forms including paper chips, films, labels, arrays, probes, and hydrogels as well as the application in livestock, poultry and aquatic meat freshness monitoring were reviewed. Future research directions involving innovation of principles, visualization and quantification capabilities for various meats freshness were provided. By critically evaluating the potential and limitations, efficient and reliable meat freshness monitoring strategies wish to be developed for the post-epidemic era.

A Mendelian randomization study for drug repurposing reveals bezafibrate and fenofibric acid as potential osteoporosis treatments.

Background: Lipid pathways have been implicated in the pathogenesis of osteoporosis (OP). Lipid-lowering drugs may be used to prevent and treat OP. However, the causal interpretation of results from traditional observational designs is controversial by confounding. We aimed to investigate the causal association between genetically proxied lipid-lowering drugs and OP risk. Methods: We conducted two-step Mendelian randomization (MR) analyses to investigate the causal association of genetically proxied lipid-lowering drugs on the risk of OP. The first step MR was used to estimate the associations of drug target genes expression with low-density lipoprotein cholesterol (LDL-C) levels. The significant SNPs in the first step MR were used as instrumental variables in the second step MR to estimate the associations of LDL-C levels with forearm bone mineral density (FA-BMD), femoral neck BMD (FN-BMD), lumbar spine BMD (LS-BMD) and fracture. The significant lipid-lowering drugs after MR analyses were further evaluated for their effects on bone mineralization using a dexamethasone-induced OP zebrafish model. Results: The first step MR analysis found that the higher expression of four genes (HMGCR, NPC1L1, PCSK9 and PPARG) was significantly associated with a lower LDL-C level. The genetically decreased LDL-C level mediated by the PPARG was significantly associated with increased FN-BMD (BETA = -1.38, p = 0.001) and LS-BMD (BETA = -2.07, p = 3.35 × 10-5) and was marginally significantly associated with FA-BMD (BETA = -2.36, p = 0.008) and reduced fracture risk (OR = 3.47, p = 0.008). Bezafibrate (BZF) and Fenofibric acid (FBA) act as PPARG agonists. Therefore genetically proxied BZF and FBA had significant protective effects on OP. The dexamethasone-induced OP zebrafish treated with BZF and FBA showed increased bone mineralization area and integrated optical density (IOD) with alizarin red staining. Conclusion: The present study provided evidence that BZF and FBA can increase BMD, suggesting their potential effects in preventing and treating OP. These findings potentially pave the way for future studies that may allow personalized selection of lipid-lowering drugs for those at risk of OP.

MiR-125 family improves the radiosensitivity of head and neck squamous cell carcinoma.

BACKGROUND: MiRNAs can affect the radiosensitization of head and neck squamous cell carcinoma (HNSCC). We aimed to analyze the function of miR-125 family members in HNSCC using The Cancer Genome Atlas (TCGA) and determine their effect on radiation in laryngeal squamous cell cancer (LSCC). METHODS: First, we systematically analyzed the role of the miR-125 family in HNSCC using the TCGA database and found that miR-125a-5p is associated with radiotherapy. We then performed comprehensive enrichment analysis of miR-125a-5p and predicted target genes. Then, we performed transfection, cell proliferation assays, reverse transcription polymerase chain reaction, apoptosis assays, micronucleus tests, and western blotting on hep-2 cells selected with puromycin. RESULTS: MiR-125 family members exhibited significantly different expression in HNSCC. They were significantly associated with tumor-node-metastasis staging, clinical stages, and histological grades. Radiation therapy had a statistically effect on miR-125 family members, except miR-125a-3p. Moreover, miR-125a-5p was related to overall survival in LSCC. Thus, we predicted 110 target genes and seven hub genes of miR-125a-5p. The proliferation rate of cells transfected with lentivirus vector expressing miR-125a-5p was significantly reduced compared to the other groups. The radiation effect was enhanced in cells transfected with miR-125a-5p. The ratio of apoptotic cells transfected and exposed to X-rays (10 Gy) was distinctly higher than that of the Ad-control group. Western blotting analysis revealed that miR-125a-5p upregulated the apoptotic regulators P53 and rH2AX. Thus, miR-125a-5p may increase radiosensitivity in LSCC via upregulation of pro-apoptotic genes. CONCLUSIONS: MiR-125 family members could be prognostic biomarkers of HNSCC and improve HNSCC sensitivity to radiotherapy by activating P53. Upregulating miR-125a-5p via lentivirus vectors may be a novel strategy to strengthen the effect of radiotherapy on LSCC.

Dissection of Cellular Communication between Human Primary Osteoblasts and Bone Marrow Mesenchymal Stem Cells in Osteoarthritis at Single-Cell Resolution.

Background and Objectives: Osteoblasts are derived from bone marrow mesenchymal stem cells (BMMSCs) and play important role in bone remodeling. While our previous studies have investigated the cell subtypes and heterogeneity in osteoblasts and BMMSCs separately, cell-to-cell communications between osteoblasts and BMMSCs in vivo in humans have not been characterized. The aim of this study was to investigate the cellular communication between human primary osteoblasts and bone marrow mesenchymal stem cells. Methods and Results: To investigate the cell-to-cell communications between osteoblasts and BMMSCs and identify new cell subtypes, we performed a systematic integration analysis with our single-cell RNA sequencing (scRNA-seq) transcriptomes data from BMMSCs and osteoblasts. We successfully identified a novel preosteoblasts subtype which highly expressed ATF3, CCL2, CXCL2 and IRF1. Biological functional annotations of the transcriptomes suggested that the novel preosteoblasts subtype may inhibit osteoblasts differentiation, maintain cells to a less differentiated status and recruit osteoclasts. Ligand-receptor interaction analysis showed strong interaction between mature osteoblasts and BMMSCs. Meanwhile, we found FZD1 was highly expressed in BMMSCs of osteogenic differentiation direction. WIF1 and SFRP4, which were highly expressed in mature osteoblasts were reported to inhibit osteogenic differentiation. We speculated that WIF1 and sFRP4 expressed in mature osteoblasts inhibited the binding of FZD1 to Wnt ligand in BMMSCs, thereby further inhibiting osteogenic differentiation of BMMSCs. Conclusions: Our study provided a more systematic and comprehensive understanding of the heterogeneity of osteogenic cells. At the single cell level, this study provided insights into the cell-to-cell communications between BMMSCs and osteoblasts and mature osteoblasts may mediate negative feedback regulation of osteogenesis process.

Transcriptomic analysis reveals shared gene signatures and molecular mechanisms between obesity and periodontitis.

Background: Both obesity (OB) and periodontitis (PD) are chronic non-communicable diseases, and numerous epidemiological studies have demonstrated the association between these two diseases. However, the molecular mechanisms that could explain the association between OB and PD are largely unclear. This study aims to investigate the common gene signatures and biological pathways in OB and PD through bioinformatics analysis of publicly available transcriptome datasets. Methods: The RNA expression profile datasets of OB (GSE104815) and PD (GSE106090) were used as training data, and GSE152991 and GSE16134 as validation data. After screening for differentially expressed genes (DEGs) shared by OB and PD, gene enrichment analysis, protein-protein interaction (PPI) network construction, GeneMANIA analysis, immune infiltration analysis and gene set enrichment analysis (GSEA) were performed. In addition, receiver operating characteristic (ROC) curves were used to assess the predictive accuracy of the hub gene. Finally, we constructed the hub gene-associated TF-miRNA-mRNA regulatory network. Results: We identified a total of 147 DEGs shared by OB and PD (38 down-regulated and 109 up-regulated). Functional analysis showed that these genes were mainly enriched in immune-related pathways such as B cell receptor signalling, leukocyte migration and cellular defence responses. 14 hub genes (FGR, MNDA, NCF2, FYB1, EVI2B, LY86, IGSF6, CTSS, CXCR4, LCK, FCN1, CXCL2, P2RY13, MMP7) showed high sensitivity and specificity in the ROC curve analysis. The results of immune infiltration analysis showed that immune cells such as macrophages, activated CD4 T cells and immune B cells were present at high infiltration levels in both OB and PD samples.The results of GeneMANIA analysis and GSEA analysis suggested that five key genes (FGR, LCK, FYB1, LY86 and P2RY13) may be strongly associated with macrophages. Finally, we constructed a TF-miRNA-mRNA regulatory network consisting of 233 transcription factors (TFs), 8 miRNAs and 14 mRNAs based on the validated information obtained from the database. Conclusions: Five key genes (FGR, LCK, FYB1, LY86, P2RY13) may be important biomarkers of OB and PD. These genes may play an important role in the pathogenesis of OB and PD by affecting macrophage activity and participating in immune regulation and inflammatory responses.

Metal-free electro-Fenton degradation of perfluorooctanoic acid with efficient ordered mesoporous carbon catalyst.

Heterogeneous electro-Fenton with in situ generated H2O2 and •OH is a cost-effective method for the degradation of refractory organic pollutants, in which the catalyst is an important factor affecting its degradation performance. Metal-free catalysts can avoid the potential risk of metal dissolution. However, it remains great challenge to develop efficient metal-free catalyst for electro-Fenton. Herein, ordered mesoporous carbon (OMC) was designed as a bifunctional catalyst for efficient H2O2 and •OH generation in electro-Fenton. The electro-Fenton system showed fast perfluorooctanoic acid (PFOA) degradation with kinetics constant of 1.26 h-1 and high total organic carbon (TOC) removal efficiency of 84.0 % after 3 h reaction. The •OH was the main species responsible for PFOA degradation. Its generation was promoted by the abundant oxygen functional groups such as C-O-C and the nano-confinement effect of mesoporous channels on OMCs. This study indicated that OMC is an efficient catalyst for metal-free electro-Fenton system.

Regulon active landscape reveals cell development and functional state changes of human primary osteoblasts in vivo.

BACKGROUND: While transcription factor (TF) regulation is known to play an important role in osteoblast development, differentiation, and bone metabolism, the molecular features of TFs in human osteoblasts at the single-cell resolution level have not yet been characterized. Here, we identified modules (regulons) of co-regulated genes by applying single-cell regulatory network inference and clustering to the single-cell RNA sequencing profiles of human osteoblasts. We also performed cell-specific network (CSN) analysis, reconstructed regulon activity-based osteoblast development trajectories, and validated the functions of important regulons both in vivo and in vitro. RESULTS: We identified four cell clusters: preosteoblast-S1, preosteoblast-S2, intermediate osteoblasts, and mature osteoblasts. CSN analysis results and regulon activity-based osteoblast development trajectories revealed cell development and functional state changes of osteoblasts. CREM and FOSL2 regulons were mainly active in preosteoblast-S1, FOXC2 regulons were mainly active in intermediate osteoblast, and RUNX2 and CREB3L1 regulons were most active in mature osteoblasts. CONCLUSIONS: This is the first study to describe the unique features of human osteoblasts in vivo based on cellular regulon active landscapes. Functional state changes of CREM, FOSL2, FOXC2, RUNX2, and CREB3L1 regulons regarding immunity, cell proliferation, and differentiation identified the important cell stages or subtypes that may be predominantly affected by bone metabolism disorders. These findings may lead to a deeper understanding of the mechanisms underlying bone metabolism and associated diseases.

Effects of soluble Antarctic krill protein-curcumin complex combined with photodynamic inactivation on the storage quality of shrimp.

A new protein complex (SAKP-Cur) was successfully prepared by combining soluble Antarctic krill protein with curcumin through hydrophobic action. The potency of photodynamic inactivation (PDI) mediated by the complex on preserving the storage quality of shrimp at 4 °C was investigated by microbiological, chemical, physical and histological methods. Results showed that the SAKP-Cur significantly improved the stability of curcumin, and greatly inactivated the native bacteria in shrimp driven by PDI. Meanwhile, the complex-mediated PDI effectively reduced the endogenous enzyme activity, the production of total volatile basic nitrogen (TVB-N) and malondialdehyde (MDA) in shrimp. Moreover, it obviously maintained the integrity and elasticity of the muscle fibers, thereby reducing the loss of water in myofibrils. Notably, the SAKP-Cur enhanced the PDI potency to preserve the freshness of shrimp during 4 °C storage or freeze-thaw cycles treatment. Therefore, the SAKP-Cur coupled with PDI is an effective fresh-keeping technology for aquatic products.

Basic electrolyzed water coupled with ultrasonic treatment improves the functional properties and digestibility of Antarctic krill proteins.

This study firstly constructed a new method of basic electrolyzed water coupled with ultrasonic (USBEW) to creatively modify the Antarctic krill proteins (AKPs), and its effects on amino acid composition, structural and functional properties, as well as in vitro digestibility of AKPs were evaluated. Results showed that BEW inhibited the production of 1O2 and •OH radicals from ultrasonic treatment. In comparison with the deionized water coupled with ultrasonic (USDW) treatment, the USBEW treatment effectively reduced the oxidation of active groups (carbonyl and free sulfhydryl) in the side chain of amino acids of the AKPs, and it also obviously decreased the particle size (18.6 nm), improved the solubility (13.2 %), increased the molecules flexibility and the surface hydrophobicity of AKPs. All these advantageous changes contributed to the improved foam stability, foam capacity and emulsifying properties of AKPs. More importantly, the in vitro digestibility (84.6 %) of AKPs treated by USBEW was significantly higher than that any control samples. Our results prove that the USBEW treatment is a valid and promising method to exploit novel marine protein products with a high nutritional quality.

Imputation of Human Primary Osteoblast Single Cell RNA-Seq Data Identified Three Novel Osteoblastic Subtypes.

BACKGROUND: Recently, single-cell RNA sequencing (scRNA-seq) technology was increasingly used to study transcriptomics at a single-cell resolution, scRNA-seq analysis was complicated by the "dropout", where the data only captures a small fraction of the transcriptome. This phenomenon can lead to the fact that the actual expressed transcript may not be detected. We previously performed osteoblast subtypes classification and dissection on freshly isolated human osteoblasts. MATERIALS AND METHODS: Here, we used the scImpute method to impute the missing values of dropout genes from a scRNA-seq dataset generated on freshly isolated human osteoblasts. RESULTS: Based on the imputed gene expression patterns, we discovered three new osteoblast subtypes. Specifically, these newfound osteoblast subtypes are osteoblast progenitors, and two undetermined osteoblasts. Osteoblast progenitors showed significantly high expression of proliferation related genes (FOS, JUN, JUNB and JUND). Analysis of each subtype showed that in addition to bone formation, these undetermined osteoblasts may involve osteoclast and adipocyte differentiation and have the potential function of regulate immune activation. CONCLUSIONS: Our findings provided a new perspective for studying the osteoblast heterogeneity and potential biological functions of these freshly isolated human osteoblasts at the single-cell level, which provides further insight into osteoblasts subtypes under various (pathological) physiological conditions.

Inhibition of Tumor Microenvironment Cytokine Signaling Sensitizes Ovarian Cancer Cells to Antiestrogen Therapy.

Antiestrogen therapy (AET) is an alternative to cytotoxic chemotherapy for recurrent ovarian cancer, yet the often short duration of response suggests mechanisms of resistance. We previously demonstrated that tumor microenvironment interleukin-6/leukemia inhibitory factor (IL6/LIF) cytokines induce tumor cell JAK-STAT signaling to promote cancer growth. Crosstalk between estrogen signaling and cytokine signaling has been reported. Therefore, we sought to characterize the impact of IL6/LIF signaling on estrogen signaling in epithelial ovarian cancer and investigate the efficacy of combination therapy. We first assessed patient tumors for cytokine expression and compared it with response to AET to determine clinical relevance. In vitro, we determined the effect of IL6/LIF on estrogen receptor expression and signaling. Cell viability assays were used to determine the efficacy and potential synergy of cytokine blockade and AET. We then extended studies to animal models, incorporating patient-derived stromal cells. Our results demonstrated shorter progression-free interval on AET in patients with stromal IL6/LIF expression. In vitro, IL6/LIF increased tumor cell estrogen receptor expression and signaling, and combination cytokine blockade and AET resulted in synergistic inhibition of tumor cell growth. The anticancer effect was verified in a mouse model. In conclusion, due to crosstalk between IL6/LIF cytokine signaling and estrogen signaling, dual blockade is a potential new treatment approach for ovarian cancer.

Survival benefit of surgery in patients with clinical T4 esophageal cancer who achieved complete or partial response after neoadjuvant chemoradiotherapy or radiotherapy.

Objective: This study aimed to determine the long-term survival of patients with cT4 esophageal cancer (EC) and whether neoadjuvant chemoradiotherapy/radiotherapy plus surgery (nCRT/RT + S) is superior to definitive CRT(dCRT)/RT in terms of survival in cT4 EC downstaged after nCRT/RT. Summary background data: Treatment options for cT4 EC include dCRT/RT and nCRT/RT + S, but it is not clear whether the latter provides survival benefit in patients downstaged after nCRT/RT. Methods: From 2002 to 2017, 726 patients with cT4 esophageal squamous cell carcinoma (ESCC) were retrospectively analyzed. Patients achieving clinical complete response (cCR) or partial response (PR) after 4-week RT (median dose, 40.7 Gy) and considered fit for surgery were offered esophagectomy. Of the 726 patients, 308 (42.4%) achieved cCR/PR, while 74 patients received subsequent surgery (nCRT/RT + S group), 234 patients received dCRT/RT. Results: Median follow-up was 58 months. The 3-year overall survival (OS) and progression-free survival (PFS) rates for all patients were 33.3% and 35.6%, respectively. The corresponding OS and PFS rates were 54.8% and 48.5% in the nCRT/RT + S group versus 30.0% and 22.1% in the dCRT/RT group (both p < 0.0001). After adjusting the confounding variables with inverse probability of treatment weighting, the adjusted 3-year OS rates were 50.4% in the nCRT/RT + S group versus 50.8% in the dCRT/RT group (p = 0.15). However, the adjusted 3-year PFS rates were significantly different between the two groups (49.0% and versus 38.3%, p = 0.004). Postoperative complications occurred in 18 (24.3%) patients. Conclusion: The long-term survival of cT4 ESCC was improved after the use of three-dimensional CRT. In cT4, EC responded to nCRT/RT, surgery improves PFS but not OS.

Structural and functional properties of soluble Antarctic krill proteins covalently modified by rutin.

New polyphenol-protein conjugates were successfully prepared by covalently crosslinking soluble Antarctic krill proteins with rutin (SAKPs-rutin). The physico-chemical and functional properties of SAKPs-rutin conjugates were systematically evaluated by measuring the changes in interfacial tension, structural conformation, and emulsifying ability, etc. The results showed that SAKPs-rutin conjugates possessed higher surface hydrophobicity, surface charge, and thermal denaturation temperature, and lower ß-sheet conformation compared to native SAKPs. On this basis, the interfacial tension of SAKPs-rutin conjugates was reduced, which greatly contributed to the formation of denser and more ordered networks at the oil-water interface. Meanwhile, the emulsifier endowed the fabricated high internal phase emulsions (HIPEs) with excellent physical performance and oxidative stability, evidenced by low peroxide values (POV) and malondialdehyde (MDA) after the treatment of long-term storage (15d), heating (65 °C) and UV light treatment. These findings suggest that SAKPs-rutin conjugates are a novel and promising food resource for preparing food-grade emulsions.

Anti-tyrosinase, antioxidant and antibacterial activities of gallic acid-benzylidenehydrazine hybrids and their application in preservation of fresh-cut apples and shrimps.

A series of gallic acid-benzylidenehydrazine hybrids were synthesized and evaluated for their tyrosinase inhibitory activity. Thereinto, compounds 5d and 5f potently inhibited tyrosinase with IC50 of 15.3 and 3.3 µM, compared to kojic acid (44.4 µM). The inhibition mechanism suggested that 5d and 5f not only chelated with Cu2+, but also reduced Cu2+ to Cu1+ in the tyrosinase active site. Additionally, 5d and 5f exhibited strong DPPH scavenging and antibacterial activities against Vibrio parahaemolyticu and Staphylococcus aureus, which can be attributed to the function of gallic acid and hydrazone moiety. These compounds also exhibited capacity to preserve fresh-cut apples and shrimps. Finally, 5d and 5f exhibited low cytotoxic activity in a human cell line (HEK293). Therefore, these compounds possess anti-tyrosinase, antioxidant, and antibacterial activities, and can be used in the development of novel food preservatives.

Single-cell RNA sequencing deconvolutes the in vivo heterogeneity of human bone marrow-derived mesenchymal stem cells.

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are multipotent stromal cells that have a critical role in the maintenance of skeletal tissues such as bone, cartilage, and the fat in bone marrow. In addition to providing microenvironmental support for hematopoietic processes, BM-MSCs can differentiate into various mesodermal lineages including osteoblast/osteocyte, chondrocyte, and adipocyte that are crucial for bone metabolism. While BM-MSCs have high cell-to-cell heterogeneity in gene expression, the cell subtypes that contribute to this heterogeneity in vivo in humans have not been characterized. To investigate the transcriptional diversity of BM-MSCs, we applied single-cell RNA sequencing (scRNA-seq) on freshly isolated CD271+ BM-derived mononuclear cells (BM-MNCs) from two human subjects. We successfully identified LEPRhiCD45low BM-MSCs within the CD271+ BM-MNC population, and further codified the BM-MSCs into distinct subpopulations corresponding to the osteogenic, chondrogenic, and adipogenic differentiation trajectories, as well as terminal-stage quiescent cells. Biological functional annotations of the transcriptomes suggest that osteoblast precursors induce angiogenesis coupled with osteogenesis, and chondrocyte precursors have the potential to differentiate into myocytes. We also discovered transcripts for several clusters of differentiation (CD) markers that were either highly expressed (e.g., CD167b, CD91, CD130 and CD118) or absent (e.g., CD74, CD217, CD148 and CD68) in BM-MSCs, representing potential novel markers for human BM-MSC purification. This study is the first systematic in vivo dissection of human BM-MSCs cell subtypes at the single-cell resolution, revealing an insight into the extent of their cellular heterogeneity and roles in maintaining bone homeostasis.