Climate-induced shifts in the composition and structure of alpine vegetation cover,both expansion and reduction,are altering alpine ecosystem functions.However,accurately quantifying variations over large-scale region...Climate-induced shifts in the composition and structure of alpine vegetation cover,both expansion and reduction,are altering alpine ecosystem functions.However,accurately quantifying variations over large-scale regions requires a detailed characterization of the fine-scale mosaic vegetation covers.In this study,we employed a regression-based unmixing model using synthetic data to develop a multi-temporal machine learning model aimed to esti-mate the fractions of alpine plant functional types(PFTs)from 1984 to 2024 in the Yarlung Zangbo River Basin(YZRB),China.The estimated cover fractions for tree cover,shrub cover and herbac-eous cover had mean absolute errors of 10.36%,14.06%and 13.38%,respectively.The variations in the fractions of each alpine PFT revealed a slight increase in tree cover and shrub cover,along-side a contraction in herbaceous cover.Specifically,tree cover and shrub cover expanded by+1.54%and+1.83%per decade,respec-tively,while herbaceous cover declined at a rate of 1.98%per decade.These variations were predominantly observed at higher elevations(4000-6000 m),on shaded aspects,and on lower slopes.The variations in these fractions are also positively correlated with air temperature and soil moisture in most regions.This study pro-vides new insights into vegetation cover shifts in this ecologically sensitive region.展开更多
Bacterial pore-forming toxins(PFTs) are essential virulence factors of many human pathogens. Knowledge of their structure within the membrane is critical for an understanding of their function in pathogenesis and for ...Bacterial pore-forming toxins(PFTs) are essential virulence factors of many human pathogens. Knowledge of their structure within the membrane is critical for an understanding of their function in pathogenesis and for the development of useful therapy. Atomic force microscopy(AFM) has often been employed to structurally interrogate many membrane proteins, including PFTs, owing to its ability to produce sub-nanometer resolution images of samples under aqueous solution. However, an absolute prerequisite for AFM studies is that the samples are single-layered and closely-packed, which is frequently challenging with PFTs. Here, using the prototypical member of the cholesterol-dependent cytolysin family of PFTs, perfringolysin O(PFO), as a test sample, we have developed a simple, highly robust method that routinely produces clean, closely-packed samples across the entire specimen surface. In this approach, we first use a small Teflon well to prepare the supported lipid bilayer, remove the sample from the well, and then directly apply the proteins to the bilayer. For reasons that are not clear,bilayer preparation in the Teflon well is essential. We anticipate that this simple method will prove widely useful for the preparation of similar samples, and thereby enable AFM imaging of the greatest range of bacterial PFTs to the highest possible resolution.展开更多
基金supported by the National Natural Science Foundation of China(U22A20567)CAS-ANSO Sustainable Development Research Project(CAS-ANSO-SDRP-2024-04 and CAS-ANSO-SDRP-2024-08)+2 种基金the Sino-Africa Joint Research Center,CAS,China(SAJC202403)the International Science and Technology Cooperation Project of Hubei Province,China(2024EHA035)the Youth Project of Natural Science Foundation of Hubei Province,China(2025AFB393).
文摘Climate-induced shifts in the composition and structure of alpine vegetation cover,both expansion and reduction,are altering alpine ecosystem functions.However,accurately quantifying variations over large-scale regions requires a detailed characterization of the fine-scale mosaic vegetation covers.In this study,we employed a regression-based unmixing model using synthetic data to develop a multi-temporal machine learning model aimed to esti-mate the fractions of alpine plant functional types(PFTs)from 1984 to 2024 in the Yarlung Zangbo River Basin(YZRB),China.The estimated cover fractions for tree cover,shrub cover and herbac-eous cover had mean absolute errors of 10.36%,14.06%and 13.38%,respectively.The variations in the fractions of each alpine PFT revealed a slight increase in tree cover and shrub cover,along-side a contraction in herbaceous cover.Specifically,tree cover and shrub cover expanded by+1.54%and+1.83%per decade,respec-tively,while herbaceous cover declined at a rate of 1.98%per decade.These variations were predominantly observed at higher elevations(4000-6000 m),on shaded aspects,and on lower slopes.The variations in these fractions are also positively correlated with air temperature and soil moisture in most regions.This study pro-vides new insights into vegetation cover shifts in this ecologically sensitive region.
基金the National Natural Science Foundation of China(Nos.991129000,11374207,31370750,21273148 and 11074168)
文摘Bacterial pore-forming toxins(PFTs) are essential virulence factors of many human pathogens. Knowledge of their structure within the membrane is critical for an understanding of their function in pathogenesis and for the development of useful therapy. Atomic force microscopy(AFM) has often been employed to structurally interrogate many membrane proteins, including PFTs, owing to its ability to produce sub-nanometer resolution images of samples under aqueous solution. However, an absolute prerequisite for AFM studies is that the samples are single-layered and closely-packed, which is frequently challenging with PFTs. Here, using the prototypical member of the cholesterol-dependent cytolysin family of PFTs, perfringolysin O(PFO), as a test sample, we have developed a simple, highly robust method that routinely produces clean, closely-packed samples across the entire specimen surface. In this approach, we first use a small Teflon well to prepare the supported lipid bilayer, remove the sample from the well, and then directly apply the proteins to the bilayer. For reasons that are not clear,bilayer preparation in the Teflon well is essential. We anticipate that this simple method will prove widely useful for the preparation of similar samples, and thereby enable AFM imaging of the greatest range of bacterial PFTs to the highest possible resolution.
