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- Liu, Xiaoxuan, et al.
(författare)
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Identifying patterns and hotspots of global land cover transitions using the ESA CCI Land Cover dataset
- 2018
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Ingår i: Remote Sensing Letters. - : Taylor & Francis Group. - 2150-704X .- 2150-7058. ; 9:10, s. 972-981
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Tidskriftsartikel (refereegranskat)abstract
- Land use/land cover change is a continuing research focus, not only because of its ecological and environmental effects but also because of the difficulties with accurate change detection and analysis uncertainty. The principal difficulty is the lack of a long time series of annual global land cover maps at a fine resolution. A new global long-term time series of annual datasets called the European Space Agency (ESA) Climate Change Initiative Land Cover (CCI-LC) has been published, making it possible to detect the global land cover changes. Using this ESA CCI-LC product from 1992-2015, we quantified the annual transitions of land cover change globally with the trajectory analysis method, analyzed the changes patterns and identified the land cover change hotspots. The total land cover change area for the world was 5.99 million km(2), amounting to only 3.36% of the total continental area. Most changes happened in forest and cropland, accounting 32% of all the land cover changes. Most land cover changes happened in tropical ecoregions. Grassland changes were mainly distributed in the temperate ecoregions, while cropland expansion occurred mainly in the tropical or subtropical ecoregions. The hotspots identified in this paper could provide target areas for further research.
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| 2. |
- Du, Zhixue, et al.
(författare)
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In Situ Monitoring of p53 Protein and MDM2 Protein Interaction in Single Living Cells Using Single-Molecule Fluorescence Spectroscopy
- 2018
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 90:10, s. 6144-6151
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Tidskriftsartikel (refereegranskat)abstract
- Protein-protein interactions play a central role in signal transduction, transcription regulations, enzymatic activity, and protein synthesis. The p53 protein is a key transcription factor, and its activity is precisely regulated by the p53-MDM2 interaction. Although the p53-MDM2 interaction has been studied, it is still not clear how p53 structures and external factors influence the p53-MDM2 interaction in living cells. Here, we developed a direct method for monitoring the p53-MDM2 interaction in single living cells using single-molecule fluorescence cross-correlation spectroscopy with a microfluidic chip. First, we labeled p53 and MDM2 proteins with enhanced green fluorescent protein (EGFP) and mCherry, respectively, using lentivirus infection. We then designed various mutants covering the three main domains of p53 (tetramerization, transactivation, and DNA binding domains) and systematically studied effects of p53 protein primary, secondary, and quaternary structures on p53 MDM2 binding affinity in single living cells. We found that p53 dimers and tetramers can bind to MDM2, that the binding affinity of p53 tetramers is higher than that of p53 dimers, and that the affinity is closely correlated to the helicity of the p53 transactivation domain. The hot-spot mutation R175H in the DNA-binding domain reduced the binding of p53 to MDM2. Finally, we studied effects of inhibitors on p53-MDM2 interactions and dissociation dynamics of pS3-MDM2 complexes in single living cells. We found that inhibitors Nutlin 3 alpha and MI773 efficiently inhibited the pS3-MDM2 interaction, but RITA did not work in living cells. This study provides a direct way for quantifying the relationship between protein structure and protein protein interactions and evaluation of inhibitors in living cells.
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