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To investigate the effects of various types of farmland shelterbelts on soil quality and soil bacterial community diversity, this study focused on soil samples from four different shelterbelt types in the Alaer reclamation area, including Populus euphratica Oliv.- Populus tomentosa Carrière (PP), Elaeagnus angustifolia L.- Populus euphratica Oliv. (EP), Populus alba var. pyramidalis Bunge (P), and Salix babylonica L. (S). We analyzed their physical, chemical, biological properties as well as the differences in bacterial community structure, and explored the influencing factors on soil microbial community characteristics through microbial correlation network analysis. The results showed that: (1) There were significant differences in soil properties among the four types of farmland shelterbelts (p < 0.05), with P soils exhibiting the highest levels of organic matter, total nitrogen, and total phosphorus contents. (2) The Alpha diversity indices of soil bacteria showed significant differences among the four types of farmland shelterbelts (p < 0.05), with the P soils displayed the highest Chao1 and Shannon indices. (3) There were differences in the composition and abundance of dominant soil bacterial communities among different farmland shelterbelts, notably, the abundances of Verrucomicrobia, Acidobacteria, and Planctomycetes were significantly higher in P soils compared to the other three types. (4) The complexity of the correlation network between microbial species and environmental factors was highest in EP soils, soil microbial biomass nitrogen and available phosphorus were the main influencing factors. These findings indicated that different types of farmland shelterbelts had significant impacts on soil properties and soil bacterial communities. Soil bacterial communities were regulated by soil properties, their changes reflected a combined effect of soil characteristics and tree species.

Studies in rodents revealed that selective accumulation of Na+ channel subtypes at the axon initial segment (AIS) determines action potential (AP) initiation and back propagation in cortical pyramidal cells (PCs); however, in human cortex, the molecular identity of Na+ channels distributed at PC axons, including the AIS and the nodes of Ranvier, remains unclear. We performed immunostaining experiments in human cortical tissues removed surgically to cure brain diseases. We found strong immunosignals of Na+ channels and two channel subtypes, NaV1.2 and NaV1.6, at the AIS of human cortical PCs. Although both channel subtypes were expressed along the entire AIS, the peak immunosignals of NaV1.2 and NaV1.6 were found at proximal and distal AIS regions, respectively. Surprisingly, in addition to the presence of NaV1.6 at the nodes of Ranvier, NaV1.2 was also found in a subpopulation of nodes in the adult human cortex, different from the absence of NaV1.2 in myelinated axons in rodents. NaV1.1 immunosignals were not detected at either the AIS or the nodes of Ranvier of PCs; however, they were expressed at interneuron axons with different distribution patterns. Further experiments revealed that parvalbumin-positive GABAergic axon cartridges selectively innervated distal AIS regions with relatively high immunosignals of NaV1.6 but not the proximal NaV1.2-enriched compartments, suggesting an important role of axo-axonic cells in regulating AP initiation in human PCs.Together, our results show that both NaV1.2 and NaV1.6 (but not NaV1.1) channel subtypes are expressed at the AIS and the nodes of Ranvier in adult human cortical PCs, suggesting that these channel subtypes control neuronal excitability and signal conduction in PC axons. [ABSTRACT FROM AUTHOR]