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Understanding how members of the human gut microbiota prioritize nutrient resources is one component of a larger effort to decipher the mechanisms defining microbial community robustness and resiliency in health and disease. This knowledge is foundational for development of microbiota-directed therapeutics. To model how bacteria prioritize glycans in the gut, germfree mice were colonized with 13 human gut bacterial strains, including seven saccharolytic Bacteroidaceae species. Animals were fed a Western diet supplemented with pea fiber. After community assembly, an inducible CRISPR-based system was used to selectively and temporarily reduce the absolute abundance of Bacteroides thetaiotaomicron or B. cellulosilyticus by 10- to 60-fold. Each knockdown resulted in specific, reproducible increases in the abundances of other Bacteroidaceae and dynamic alterations in their expression of genes involved in glycan utilization. Emergence of these alternate consumers was associated with preservation of community saccharolytic activity. Using an inducible system for CRISPR base editing in vitro, we disrupted translation of transporters critical for utilizing dietary polysaccharides in Phocaeicola vulgatus, a B. cellulosilyticus knockdown-responsive taxon. In vitro and in vivo tests of the resulting P. vulgatus mutants allowed us to further characterize mechanisms associated with its increased fitness after knockdown. In principle, the approach described can be applied to study utilization of a range of nutrients and to preclinical efforts designed to develop therapeutic strategies for precision manipulation of microbial communities.

[ Objective ] The front piedmont belt of the northern slope of the Tianshan Mountains in Xinjiang is a crucial component of the mountain-oasis-desert ecosystem of the Tianshan northern slope. Investiga- ting the dynamic physiological adaptations of plants to drought stress and assessing methods for drought resistance , as well as selecting suitable tree species for vegetation restoration holds significant importance for the ecological restoration in this region. [ Methods ] 12 plant species planted in the piedmont belt of the northern slope of the Tianshan Mountains in Xinjiang were selected as the subjects. The study observed the spatiotemporal distribution of soil moisture following irrigation and analyzed the impact of drought stress and rewatering treatment on plant photosynthetic and physiological indicators. The drought resist- ance of these 12 species was evaluated using principal component analysis. [ Results ] ( 1 ) Following drought stress , soil moisture depletion occurred most rapidly in the 0-20 cm layer , followed by the 20- 40 cm layer , and was slowest in the 40-60 cm layer. Different plants employed different strategies to adapt their growth to drought stress. ( 2 ) Following drought stress , net photosynthetic rate ( P n ), stoma- tal conductance ( G s ), transpiration rate ( T r ), intercellular CO 2 concentration ( C i ), potential activity of PSⅡ ( F v / F o ), maximum photochemical efficiency of PSⅡ ( F v / F m ), electron transport rate ( ETR ), and chlorophyll content were decreased , while the activity of superoxide dismutase ( SOD ), proline content , malondialdehyde ( MDA ) content , and non-photochemical quenching coefficient ( q N ) were increased. Af- ter rehydration , there was a certain degree of recovery in each parameter , but none of them reached the in- itial levels. ( 3 ) The results of principal component analysis highlighted that factors like P n , chlorophyll content , ETR , and MDA content were major contributors. Species such as Haloxylon ammodendron , Tamarix chinensis , Rosa acicularis , and Caragana korshinskii demonstrated significant drought resili- ence. Hippophae rhamnoides , H . rhamnoides ‘ Xinji 5 ’, H . rhamnoides ‘ Xinji 1 ’, and Prunus sibirica showed moderate levels of drought resistance , while H . rhamnoides ‘ Xinji 4 ’, H . rhamnoides ‘ Xinji 3 ’, Xanthoceras sorbifolium , and H . rhamnoides ‘ Xinji 2 ’ exhibited relatively lower drought tolerance. [ Conclusion ] P n , chlorophyll content , ETR , and MDA content were crucial indicators for evaluating the adaptability of various plant species to drought stress. In the context of ecological restoration efforts in the piedmont belt of the Tianshan Mountains􀆴 northern slope in Xinjiang , prioritizing the cultivation of H . ammodendron , T . chinensis , R . acicularis , and C . korshinskii were recommended.

Objective·To analyze the expression changes of adhesion G protein-coupled receptor F1 (ADGRF1) in the occurrence and development of pancreatic ductal adenocarcinoma (PDAC), and explore the impact of ADGRF1 on the proliferation of PDAC cells and the potential molecular mechanisms that promote PDAC progression.Methods·The expression of ADGRF1 at mRNA level was analyzed based on the Gene Expression Omnibus (GEO) database and The Cancer Genome Atlas (TCGA) database, respectively. The expression of ADGRF1 in normal pancreatic ductal epithelial cells (hTERT-HPNE) and various PDAC tumor cells was detected by using real-time fluorescence quantitative PCR (qPCR) and Western blotting. Immunohistochemical staining (IHC) was used to detect the differential expression of ADGRF1 in cancer tissues and adjacent tissues of PDAC patients. After knocking down ADGRF1 with small interfering RNA (siRNA) transfection, the changes in the proliferation ability of PDAC AsPC-1 and SW1990 cells were detected through CCK8 assay and plate cloning experiment. Stable overexpression of ADGRF1 was constructed in PDAC Patu8988 cell line, and the proliferation changes induced by overexpression of ADGRF1 were evaluated through CCK8 assay. RNA sequencing (RNA-seq), gene set enrichment analysis (GSEA), and immune infiltration analysis were utilized to predict signaling pathways associated with ADGRF1-mediated promotion of PDAC cancer progression.Results·Analysis of the TCGA database and GEO database revealed higher expression of ADGRF1 mRNA in PDAC tissues compared to normal pancreatic tissues (all P=0.000). qPCR and Western blotting results demonstrated up-regulation of ADGRF1 mRNA and protein levels in various PDAC cells compared to hTERT-HPNE cells (all P

Liquid sodium leaks and sodium fire accidents are common occurrences during the operation of sodium-cooled fast reactors and pose key and challenging issues in their development. Of the different forms of sodium fire, spray sodium fire has the most severe consequences and is the primary threat to plant safety. The atomization characteristics of liquid sodium are a crucial factor affecting the spray sodium fire. Studying these characteristics through experimental research could provide essential data for simulating and evaluating the safety of spray sodium fires. In this paper, an experimental visualization device that takes into consideration the material characteristics of liquid sodium was designed and constructed. In the experiments, the liquid sodium with varying masses (20-150 g) and temperatures (200-400℃) was injected from nozzles of different shapes (round, oval, sharp crack, rough crack) at different heights (55-85 cm) using high-pressure nitrogen (0.1-0.5 MPa), generating sodium liquid sprays. The experimental phenomenon was noted and recorded. Finally, the sodium spray was collected within a cooling tank filled with liquid paraffin, which caused liquid droplets to solidify into solid sodium particles. The size distributions of the liquid sodium droplets in the spray field were inferred by measuring those of solid sodium particles. The study analyzed the effects of injection pressure, initial sodium mass and temperature, leakage height, and leakage boundary shape on the liquid sodium spray characteristics. It is found that the process of liquid sodium spray can be divided into three stages:the column flow stage, the transition stage and the atomization stage. As the stages develop, the liquid sodium spray angle will progressively rise, reaching its peak during the atomization stage. The raising of leakage height and injection pressure causes increased flow rate of liquid sodium resulting in intensified air disturbance for more atomized sodium flow, leading to a decrease in mass intermediate diameter of the sodium spray. The atomization characteristics of liquid sodium are greatly influenced by the leakage boundary, and the mass intermediate diameter of the spray decreases approximately linearly with the increase of the shape factor of the leakage boundary. Increasing the initial temperature of liquid sodium may lead to a reduction in its surface tension and viscosity, potentially promoting sodium flow atomization. However, such changes are likely to be negligible, thereby limiting the impact of the initial temperature on the atomization characteristics within experimental conditions. The rise in sodium mass would result in an elevation of the liquid level within the crucible, thereby reducing the impact of high-pressure gas on the leakage end in the proximity of the nozzle. Consequently, the intermediate mass diameter of the spray will increase with the initial sodium mass. This research can provide fundamental experimental data for the simulation and safety assessment of spray fires of liquid sodium and can provide technical references for sodium fire prevention and control measures.