ABSTRACT
The riparian zone supports important ecological functions and acts as an ecotone connecting terrestrial and aquatic areas. Soil microbes under the revegetation of woody species are crucial to the biogeochemical cycle of nutrients. Here, soil samples were collected to examine the soil microbes during different emergence phases in 2019 (May:T1, July:T2, and September:T3) in the riparian zone of the Three Gorges Reservoir, China. The variations in the bacterial community were evaluated using high-throughput sequencing. The results showed that:during the emergence phases, soil properties such as pH value (pH), ammonium nitrogen (NH4+-N), and nitrate-nitrogen (NO3--N) and soil enzymes changed significantly(P<0.05), and soil bacterial α diversity also changed with time. Except for the Chao1 index, the richness of rhizosphere soil bacteria showed T1>T2>T3, whereas the α diversity of non-rhizosphere soil bacteria showed T3>T1>T2. The redundancy analysis (RDA) test implied that soil urease, NH4+-N, pH, and NO3--N were the key factors structuring the microbial community. Proteobacteria and Acidobacteria were the two dominant components among the 60 phyla that were detected in the soil. Based on phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt2) prediction, metabolism was the basic function of soil bacterial communities of Taxodium distichum; in the secondary functional layer, the metabolic pathways related to carbon, nitrogen, and phosphorus mainly included amino acid metabolism, carbohydrate metabolism, lipid compound metabolism, and energy metabolism, and the relative abundance of each metabolic function had a certain time difference in different periods. These findings could help us better understand how soil microbes change after restoring vegetation in the Three Gorges Reservoir area.
Subject(s)
Soil , Taxodium , Soil/chemistry , Soil Microbiology , Phylogeny , Bacteria/genetics , NitrogenABSTRACT
Background: Naoluo Xintong decoction (NLXTD) is a traditional Chinese medicine (TCM) formula which has been used to improve neuronal functional recovery after cerebral ischemic stroke. However, the molecular mechanism underlying NLXTD's amelioration of ischemic stroke remains unclear. The present study was designed to explore the effect and mechanism of NLXTD on brain angiogenesis in a rat model with cerebral ischemia-reperfusion (I/R) injury targeting the hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) pathway. Materials and Methods: Cerebral I/R model was established by the classical middle cerebral artery occlusion (MCAO) method. Sprague-Dawley (SD) male rats (n = 80) were randomly divided into the sham-operation group, the model group, the HIF-1α inhibitor 2-methoxyestradiol (2ME2) group, the 2ME2 with NLXTD group, and the NLXTD group. Neurological deficit test, TTC staining, H&E staining, TUNEL staining, immunohistochemistry (IH), immunofluorescence (IF), western blot, and quantitative RT-PCR were performed to evaluate the effect of NLXTD after MCAO. Results: Administration of NLXTD significantly decreased neuron deficiency scores, reduced brain infarct volume, and lowered damaged and apoptotic cells after brain I/R injury in rats. Meanwhile, NLXTD had a protective effect on angiogenesis by increasing the MVD and the expressions of BrdU and CD34, which enhanced the number of endothelial cells in the ischemic penumbra brain. NLXTD treatment significantly raised the protein and mRNA levels of HIF-1α, VEGF, VEGFR2, and Notch1 compared with the model treatment. In contrast, a specific HIF-1α inhibitor, 2ME2, inhibited the improvement of neurological function and angiogenesis in NLXTD-induced rats with cerebral I/R injury, suggesting that NLXTD played a positive role in ischemic brain injury by activating the HIF-1α/VEGF signaling pathway. Conclusions: NLXTD exerts neuroprotection targeting angiogenesis by upregulating the HIF-1α/VEGF signaling pathway on cerebral I/R injury rats.
