[Construction of synthetic microbial community and its application in polyhydroxyalkanoate biosynthesis].

Synthetic microbial communities are artificial systems composed of multiple microorganisms with well-defined genetic backgrounds. They are characterized by low complexity, high controllability, and strong stability, thus suitable for industrial production, disease management, and environmental remediation. This review summarizes the design principles and construction methods of synthetic microbial communities, and highlights their application in polyhydroxyalkanoate (PHA) biosynthesis. Constructing a synthetic microbial community represents a core research direction of synthetic ecology and an emerging frontier of synthetic biology. It requires strategies to design and control microbial interactions, spatial organization, robustness maintenance, and biocontainment to obtain an efficient, stable, and controllable synthetic microbial community. In recent years, synthetic microbial communities have been widely used to synthesize high-value chemicals such as drugs, biofuels, and biomaterials. As an ideal substitute for oil-based plastics, PHA has received much attention. Enhancing the capacity and broadening the range of carbon source utilization for PHA producers have become the research priority in the application of synthetic microbial communities for PHA biosynthesis, with the aim to reduce PHA production cost.

Human Exposure to Ambient Atmospheric Microplastics in a Megacity: Spatiotemporal Variation and Associated Microorganism-Related Health Risk.

Microplastics are found in various human tissues and are considered harmful, raising concerns about human exposure to microplastics in the environment. Existing research has analyzed indoor and occupational scenarios, but long-term monitoring of ambient atmospheric microplastics (AMPs), especially in highly polluted urban regions, needs to be further investigated. This study estimated human environmental exposure to AMPs by considering inhalation, dust ingestion, and dermal exposure in three urban functional zones within a megacity. The annual exposure quantity was 7.37 × 104 items for children and 1.06 × 105 items for adults, comparable with the human microplastic consumption from food and water. Significant spatiotemporal differences were observed in the characteristics of AMPs that humans were exposed to, with wind speed and rainfall frequency mainly driving these changes. The annual human AMP exposure quantity in urban green land spaces, which were recognized as relatively low polluted zones, was comparable with that in public service zones and residential zones. Notably, significant positive correlations between the AMP characteristics and the pathogenicity of the airborne bacterial community were discovered. AMP size and immune-mediated disease risks brought by atmospheric microbes showed the most significant relationship, where Sphingomonas might act as the potential key mediator.

Potential environmental risks of field bio/non-degradable microplastic from mulching residues in farmland: Evidence from metagenomic analysis of plastisphere.

The plastisphere may act as reservoir of antibiotic resistome, accelerating global antimicrobial resistance dissemination. However, the environmental risks in the plastisphere of field microplastics (MPs) in farmland remain largely unknown. Here, antibiotic resistance genes (ARGs) and virulence factors (VFs) on polyethylene microplastics (PE-MPs) and polybutylene adipate terephthalate and polylactic acid microplastics (PBAT/PLA-MPs) from residues were investigated using metagenomic analysis. The results suggested that the profiles of ARG and VF in the plastisphere of PBAT/PLA-MPs had greater number of detected genes with statistically higher values of diversity and abundance than soil and PE-MP. Procrustes analysis indicated a good fitting correlation between ARG/VF profiles and bacterial community composition. Actinobacteria was the major host for tetracycline and glycopeptide resistance genes in the soil and PE-MP plastisphere, whereas the primary host for multidrug resistance genes changed to Proteobacteria in PBAT/PLA-MP plastisphere. Besides, three human pathogens, Sphingomonas paucimobilis, Lactobacillus plantarum and Pseudomonas aeruginosa were identified in the plastisphere. The PE-MP plastisphere exhibited a higher transfer potential of ARGs than PBAT/PLA-MP plastisphere. This work enhances our knowledge of potential environmental risks posed by microplastic in farmland and provides valuable insights for risk assessment and management of agricultural mulching applications.

Periodontal ligament cells-derived exosomes promote osteoclast differentiation via modulating macrophage polarization.

Several studies have demonstrated that exosomes (Exos) are involved in the regulation of macrophage polarization and osteoclast differentiation. However, the characteristics as well as roles of exosomes from human periodontal ligament cells (hPDLCs-Exos) in M1/M2 macrophage polarization and osteoclast differentiation remain unclear. Here, periodontal ligament cells were successfully extracted by method of improved Type-I collagen enzyme digestion. hPDLCs-Exos were extracted by ultracentrifugation. hPDLCs-Exos were identified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western blotting (WB). Osteoclast differentiation was evaluated by real-time quantitative polymerase chain reaction (RT-qPCR), WB and tartrate-resistant acid phosphatase (TRAP) staining. M1/M2 macrophage polarization were evaluated by RT-qPCR and WB. The results showed hPDLCs-Exos promoted osteoclast differentiation and M2 macrophage polarization, but inhibited M1 macrophage polarization. Moreover, M1 macrophages inhibited osteoclast differentiation, whereas M2 macrophages promoted osteoclast differentiation. It has shown that hPDLCs-Exos promoted osteoclast differentiation by inhibiting M1 and promoting M2 macrophage polarization.

Induction of apoptosis and autophagy by dichloromethane extract from Patrinia scabiosaefolia Fisch on acute myeloid leukemia cells.

Patrinia scabiosaefolia Fisch (PS), a perennial herb belonging to the genus Pinus in the family Pinnacle Sauce, has been previously known for its analgesic, anti-inflammatory, antibacterial, and antitumor properties. However, the specific mechanism behind its antileukemic effect remains unknown. This study focused on the cytotoxicity and potential modes of action of the dichloromethane extract from PS (DEPS) in acute myeloid leukemia (AML) cells. Our results demonstrated that DEPS reduced cell viability, arrested the cell cycle in the G2/M phase, disrupted the mitochondrial membrane potential, increased reactive oxygen species (ROS) production, and upregulated the expression of Bax/Bcl-2 and Cleaved caspase-3. However, the impact of DEPS on cell viability and the expression of apoptosis-associated proteins was reversed upon pretreatment with the caspase-3 inhibitor (Z-DEVD-FMK) in HL-60 cells, which demonstrated that DEPS could induce apoptosis through the mitochondria-associated apoptotic pathway. Interestingly, DEPS also influenced autophagy by upregulating the expression of LC3II/I, P62, and Beclin-1 proteins, and the autophagy inhibition chloroquine(CQ) could attenuate the apoptotic effects of DEPS in HL-60 cells. Furthermore, SMART 2.0 analysis predicted that the main components present in DEPS were likely terpenoids. In conclusion, DEPS possibly exerts antileukemic effects by downregulating the PI3K/AKT and ERK pathways, thereby promoting intracellular ROS production, activating the mitochondrial apoptotic pathway, and affecting autophagy, providing valuable insights for the potential future application of PS in the treatment of AML.

Localized electron-accepted yellow-emission carbon dots encapsulated in UiO-66 for efficient visible-light driven photocatalytic activity.

Metal organic frameworks (MOFs) possess a large surface area, inherent porosity and high crystallinity. Nevertheless, they lack electron acceptors, which limit the exploitation of their photocatalytic properties. Carbon dots (CDs) known for excellent optical properties can serve as localized electron acceptors. As a novel hybrid nanomaterial, the structure of CDs@MOFs effectively facilitates charge separation and carrier transfer, bring about a marked improvement of photocatalytic activity. In this study, yellow-emission carbon dots (YCDs) were encapsulated within zirconium-based metal organic framework (UiO-66) via a dynamic adsorption method. Compared with blue carbon dots (BCDs), the YCDs@UiO-66 exhibited superior degradation performance. It demonstrates that incorporation of YCDs broadens the UV absorption range of UiO-66, thereby enhancing light utilization. The degradation efficiency of YCDs@UiO-66 was 92.6%, whereas UiO-66 alone achieved only 63.1%. Notably, the results of the radical quenching experiment and electron paramagnetic resonance (EPR) revealed that h+ and •O2- played a prominent role in the photodegradation of tetracycline hydrochloride (TCH). This study highlights that the introducing YCDs in MOFs-mediated photocatalytic reactions is a viable strategy to improve catalytic efficiency.

Plastic substrate and residual time of microplastics in the urban river shape the composition and structure of bacterial communities in plastisphere.

The widespread secondary microplastics (MPs) in urban freshwater, originating from plastic wastes, have created a new habitat called plastisphere for microorganisms. The factors influencing the structure and ecological risks of the microbial community within the plastisphere are not yet fully understood. We conducted an in-site incubation experiment in an urban river, using MPs from garbage bags (GB), shopping bags (SB), and plastic bottles (PB). Bacterial communities in water and plastisphere incubated for 2 and 4 weeks were analyzed by 16S high-throughput sequencing. The results showed the bacterial composition of the plastisphere, especially the PB, exhibited enrichment of plastic-degrading and photoautotrophic taxa. Diversity declined in GB and PB but increased in SB plastisphere. Abundance analysis revealed distinct bacterial species that were enriched or depleted in each type of plastisphere. As the succession progressed, the differences in community structure was more pronounced, and the decline in the complexity of bacterial community within each plastisphere suggested increasing specialization. All the plastisphere exhibited elevated pathogenicity at the second or forth week, compared to bacterial communities related to natural particles. These findings highlighted the continually evolving plastisphere in urban rivers was influenced by the plastic substrates, and attention should be paid to fragile plastic wastes due to the rapidly increasing pathogenicity of the bacterial community attached to them.

Platinum-Cobalt Nanowires for Efficient Alcohol Oxidation Electrocatalysis.

The compositions and surface facets of platinum (Pt)-based electrocatalysts are of great significance for the development of direct alcohol fuel cells (DAFCs). We reported an approach for preparing ultrathin PtnCo100-n nanowire (NW) catalysts with high activity. The PtnCo100-n NW alloy catalysts synthesized by single-phase surfactant-free synthesis have adjustable compositions and (111) plane and strain lattices. X-ray diffraction (XRD) results indicate that the alloy composition can adjust the lattice shrinkage or expansion of PtnCo100-n NWs. X-ray photoelectron spectroscopy (XPS) results show that the electron structure of Pt is changed by the alloying effect caused by electron modulation in the d band, and the chemical adsorption strength of Pt is decreased, thus the catalytic activity of Pt is increased. The experimental results show that the activity of PtnCo100-n for the oxidation of methanol and ethanol is related to the exposed crystal surface, strain lattice and composition of catalysts. The PtnCo100-n NWs exhibit stronger electrocatalytic performance for both methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR). The dominant (111) plane Pt53Co47 exhibits the highest electrocatalytic activity in MOR, which is supported by the results of XPS. This discovery provides a new pathway to design high activity, stability nanocatalysts to enhance direct alcohol fuel cells.

Periodontal ligament fibroblasts-derived exosomes induced by PGE2 inhibit human periodontal ligament stem cells osteogenic differentiation via activating miR-34c-5p/SATB2/ERK.

Several studies have confirmed that exosomes containing microRNAs (miRNAs) from the aseptic inflammatory microenvironment play an important role in bone remodeling. But the mechanism that induces changes in the osteogenic ability of periodontal ligament stem cells (PDLSCs) is still unclear. In the present study, the osteogenic function of periodontal ligament fibroblasts-derived exosomes induced by PGE2 on PDLSCs was detected by real-time PCR, alizarin red assay and alkaline phosphatase staining. High-throughput miRNAs sequencing was used to reveal that miR-34c-5p in exosomes-PGE2 was upregulated compared it in exosomes-normal. Real-time PCR and western blotting assay verified that overexpression of miR-34c-5p inhibited osteogenic differentiation, and reduced phosphorylation of ERK1/2. In addition, dual-luciferase reporter assay revealed that miR-34c-5p targeted special AT-rich sequence-binding protein 2 (SATB2). It was shown that exosomal miR-34c-5p inhibited osteogenic differentiation of PDLSCs via SATB2/ERK pathway.

Spectrins and human diseases.

Spectrin, as one of the major components of a plasma membrane-associated cytoskeleton, is a cytoskeletal protein composed of the modular structure of α and ß subunits. The spectrin-based skeleton is essential for preserving the integrity and mechanical characteristics of the cell membrane. Moreover, spectrin regulates a variety of cell processes including cell apoptosis, cell adhesion, cell spreading, and cell cycle. Dysfunction of spectrins is implicated in various human diseases including hemolytic anemia, neurodegenerative diseases, ataxia, heart diseases, and cancers. Here, we briefly discuss spectrins function as well as the clinical manifestations and currently known molecular mechanisms of human diseases related to spectrins, highlighting that strategies for targeting regulation of spectrins function may provide new avenues for therapeutic intervention for these diseases.

Advances in polysaccharide nanocrystals as pharmaceutical excipients.

Polysaccharide nanocrystals (PNs) are attractive pharmaceutical excipients due to their abundant surface hydroxyl groups, high surface charges, prominent mechanical properties, excellent fluidity, and good swelling properties. In this review, we summarize three kinds of PNs, including cellulose nanocrystals (CNCs), starch nanocrystals (SNCs), and chitin nanocrystals (ChNCs). We introduce the applications of PNs as stabilizers, adsorbents, film-forming materials, gel materials, disintegrants, and ointment matrices. We focus on the advantages of PNs to improve mechanical properties, thermal stability, therapeutic effect, biocompatibility, and release of active pharmaceutical ingredients. We discuss regulatory issues of PNs. We finally propose the challenges and future perspectives of PNs as pharmaceutical excipients.