Qinghai Meteorological Bureau

The Elikendagou syenogranite, located within the Tataleng granitic batholith in Northwest China, hosts numerous greisen belts and significant tin mineralizations. However, there have been few investigations into these features, resulting in a limited understanding of the petrogenesis and tin-mineralization potential of the syenogranite. This study investigates the geochronology and petrogenesis of the Elikendagou syenogranite, along with ages and compositions of cassiterite from the greisen belts. Two samples of the syenogranite yielded weighted mean 206 Pb/ 238 U zircon ages of 436.0 ± 5.5 and 429.3 ± 2.5 Ma, respectively, while the cassiterite yielded a lower intercept U–Pb age of 432.6 ± 2.7 Ma, all suggesting a comparable early Silurian era. Geochemically, the syenogranite is predominantly peraluminous, with high alkali contents, strongly negative Eu anomalies, high Rb/Sr and Rb/Ba ratios, and negative correlations between Rb and Th, suggesting a fractionated S-type granite. The observed low oxygen fugacities and Ce 4+ /Ce 3+ ratios for zircon indicate that the fractionated syenogranite, which exhibits no magnetism in the field, was formed under relatively reducing conditions, demonstrating significant potential for tin mineralization. Additionally, positive correlations among specific trace elements in cassiterite suggest oxidized conditions. Overall, the redox reaction from bivalent Sn to tetravalent Sn was necessary to form greisen-type tin mineralization in this study, which may be genetically linked to the emplacement of the Elikendagou syenogranite during the early Silurian syn-collisional setting associated with the closure of the South Qilian Ocean.

Alfalfa (Medicago sativa L.) is one of the most important forage crop in northern China, suffers from low-temperature (LT) stress, which significantly impairs its yield. While selenium (Se) supplementation has been reported to enhance abiotic stress tolerance in plants, the underlying molecular mechanisms in alfalfa remain poorly understood. This study aims to explore how Se mediates LT tolerance in alfalfa through transcriptomic analysis. Selenium significantly increased total Se in both shoots and roots, enhanced root-to-shoot translocation, and under low temperature (LT) shifted Se speciation toward organic forms at the higher dose. Meanwhile, 0.4 mg kg−1 Se was sufficient to restore Pn, Gs, Ci, and Tr, reduce MDA, and elevate SOD, POD, APX, GR, GSH, and ASA, indicating improved photosynthetic performance and antioxidant status. Co-expression network analysis identified modules tightly associated with these traits: in the photosynthetic module, MS.gene064837 and MS.gene051360 were positively correlated with Gs, whereas MS.gene061853 and MS.gene037454 were positively correlated with Ci and Tr but negatively with Gs, suggesting coordination between carbon assimilation and stomatal control. In the antioxidant module, MS.gene036174 correlated positively with GSH and MDA and negatively with GSSG, while MS.gene064490 showed negative correlations with Pro, SS, GSSG, SOD, and POD. qRT-PCR of six targets corroborated the RNA-seq trends. Collectively, these results indicate that moderate soil Se (0.4 mg·kg−1) supplementation enhances LT tolerance in alfalfa by concurrently optimizing photosynthetic regulation and antioxidant defense, with MS.gene064837, MS.gene051360, MS.gene036174, and MS.gene064490 emerging as candidate regulators whose specific functions require further validation. This study reveals that selenium enhances LT tolerance in alfalfa by promoting Se conversion into its organic form, optimizing redox homeostasis, and activating key genes associated with photosynthesis and antioxidant defense. These findings provide valuable insights into Se-mediated cold tolerance mechanisms, offering a foundation for Se-based strategies in improving the resilience of forage crops to cold stress.

The imbalance of T helper 17 (Th17)/regulatory T (Treg) is pivotal in the development of chronic obstructive pulmonary disease (COPD). This study focused on evaluating the regulatory effects of short-chain fatty acids (SCFAs) on Th17/Treg balance in COPD.A COPD mouse model was induced by exposure to cigarette smoke (CS) and intranasal lipopolysaccharide (LPS) instillation. Mice were administered sodium acetate (NaA), sodium propionate (NaP), or sodium butyrate (NaB) via oral gavage. Lung function, histopathological changes, cytokine levels, and the distribution of Th17 and Treg cells were then evaluated. Epithelial cell injury induced by cigarette smoke extract (CSE) was assessed using the Cell Counting Kit-8 (CCK-8) assay, wound healing assay, and flow cytometry for apoptosis and T cell subset analysis.SCFAs treatment attenuated pathological damage in lung tissue, including reduced inflammatory cell infiltration and pulmonary fibrosis. SCFAs suppressed apoptosis and increased peak inspiratory flow (PIF) and peak expiratory flow (PEF). SCFAs effectively rebalanced the Th17/Treg axis by suppressing Th17 differentiation while promoting Treg cell expansion, which was accompanied by reduced levels of inflammatory signaling factors (IL-17, IL-6, IL-2, and TNF-α). Moreover, SCFAs enhanced CSE-induced MLE-12 cell viability and migration, and suppressed apoptosis. SCFAs blocked the differentiation of naïve CD4⁺ T cells into Th17 cells while facilitating their differentiation into Treg cells.SCFAs alleviate the pathological features of COPD by restoring the Th17/Treg balance and enhancing epithelial resilience, suggesting their promise as a therapeutic strategy for CS-related COPD.