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Fungi play an important regulating role in terrestrial ecosystem functioning. However, their biogeographic distribution patterns along combined gradients of plant communities and environmental variables across regional spatial scales remain poorly understood. This knowledge gap is particularly pronounced in arid and semi-arid grassland ecosystems, which occupy one third of the terrestrial surface of China. Here, a regional-scale field investigation was conducted to collect soil samples from 290 plots at 52 sites along a 4000 km transect in temperate grasslands of northern China to assess the distribution patterns of fungal communities. The high-throughput Illumina sequencing revealed that soil fungal communities were dominated by Ascomycota, Basidiomycota and Zygomycota across the temperate grasslands. Fungal richness increased with plant species richness and mean annual precipitation (MAP). Bray-Cutis dissimilarities in soil fungal community composition between sites were significantly correlated with plant community composition, geographical distance, and abiotic factors including MAP, mean annual temperature, soil pH, and soil organic carbon. Variation partitioning analysis revealed that variation in fungal community composition was mainly explained by plant community composition, followed by geographical distance and abiotic factors. Structural equation models further highlighted the significant role of plant species richness in determining soil fungal richness. Taken together, these results suggest that the regional-scale distribution pattern of soil fungal communities is predominantly mediated by plant community composition, and also by abiotic factors and geographical distance in arid and semi-arid temperate grasslands. [ABSTRACT FROM AUTHOR]

Abstract: Rhizoma Curcumae is a common Chinese dietary spice used in South Asia and China for thousands of years. As the main extract, Rhizoma Curcumae oil has attracted a great interest due to its newly raised therapeutic activities including its pharmacological effects upon central nervous system such as neuroprotection, cognitive enhancement, and anti-seizure efficacy; however the molecular mechanisms and the target identification remain to be established. Here we characterize an inhibitory effect of curcumol, a major bioactive component of Rhizoma Curcumae oil, on the excitability of hippocampal neurons in culture, the basal locomotor activity of freely moving animals, and the chemically induced seizure activity in vivo. Electrophysiological recording showed that acute application of curcumol significantly facilitated the γ-aminobutyric acid (GABA)-activated current in cultured mouse hippocampal neurons and in human embryonic kidney cells expressing α1- or α5-containing A type GABA (GABAA) receptors in a concentration-dependent manner. Measurement of tonic and miniature inhibitory postsynaptic GABAergic currents in hippocampal slices indicated that curcumol enhanced both forms of inhibition. In both pentylenetetrazole and kainate seizure models, curcumol suppressed epileptic activity in mice by prolonging the latency to clonic and tonic seizures and reducing the mortality as well as the susceptibility to seizure, presumably by facilitating the activation of GABAA receptors. Taken together, our results identified curcumol as a novel anti-seizure agent which inhibited neuronal excitability through enhancing GABAergic inhibition. [Copyright &y& Elsevier]