In order to improve the accuracy of biophysical parameters retrieved from remotely sensing data, a new algorithm was presented by using spatial contextual to estimate canopy variables from high-resolution remote sensi...In order to improve the accuracy of biophysical parameters retrieved from remotely sensing data, a new algorithm was presented by using spatial contextual to estimate canopy variables from high-resolution remote sensing images. The developed algorithm was used for inversion of leaf area index (LAI) from Enhanced Thematic Mapper Plus (ETM+) data by combining with optimization method to minimize cost functions. The results show that the distribution of LAI is spatially consistent with the false composition imagery from ETM+ and the accuracy of LAI is significantly improved over the results retrieved by the conventional pixelwise retrieval methods, demonstrating that this method can be reliably used to integrate spatial contextual information for inverting LAI from high-resolution remote sensing images.展开更多
Background Dendritic cells(DCs)are the most important antigen-presenting cells due to their professional and extremely efficient antigen-presenting function.The dynamics of cytoskeleton plays crucial regulated roles o...Background Dendritic cells(DCs)are the most important antigen-presenting cells due to their professional and extremely efficient antigen-presenting function.The dynamics of cytoskeleton plays crucial regulated roles on DCs’immune functions and biophysical properties.Several evidences show that tumor-derived suppressive cytokines deteriorate DCs’immune functions through remodeling their F-actin cytoskeleton.But the underlying mechanism is still elusive.Tropomodulin1(Tmod1),a cytoskeleton-binding protein,regulates and stabilizes actin filaments lengths and cytoskeleton architecture,which involves in the regulations of the morphology,formation of neural dendrites and biophysical properties of cells.Our previous studies found that mature DCs(mDCs)had a higher expression of Tmod1 than immature DCs(imDCs). Therefore,it’s hypothesized that Tmod1 maybe involve in the modification of DCs’functions.Objective The aim of the study is to investigate the effects of Tmodl on the immune functions and biophysical properties of DCs and the underlying mechanisms in order to further understand the biological behaviors of DCs.Methods Bone marrow-derived cells were harvested from wild type(C57BL/6 J)mice and Tmod1 knockout mice(Tmod1 overexpressing transgenic(TOT)/Tmod1-/-)and differentiated to immature dendritic cells(imDCs)by rmGM-CSF and rmIL-4.imDCs were then matured by lipopolysaccharides(LPS)treatment.The expressions of the surface markers in DCs,including CD80,CD86,CD40,MHC-Ⅱand CCR7,were detected by flow cytometry,Western blot and qRT-PCR.The inflammation cytokines such as IL-6,IFN-γ,IFN-βand IL-10 were also detected by flow cytometry.The immune functions and the biophysical properties of DCs were compared between the wild type and Tmod1 knockout mice.The F-actin content and dendritic pseudopodia of these two kinds of DCs were detected by flow cytometry and laser scanning confocal microscope respectively.Finally,we detected the MyD88 dependent and independent signaling pathway to discover the molecular mechanisms.Results We found that Tmod1-deficient mDCs showed deficient antigen-presenting ability and they failed to express enough MHC-Ⅱ,co-stimulated molecules(CD80/86,CD40)and CCR7 on their cell surface.The secretions of the inflammatory cytokines IL-6 and IFN-γwere decreased while the anti-inflammatory cytokines IFN-βand IL-10 were increased in the supernatant of Tmod1-deficient mDCs.As compared to DCs of wild type mice,the migration ability of DCs from Tmod1 knockout mice were dramatically damaged including their free migration and CCL19 mediated chemotaxis migration.However,we found that Tmod1 knockout had no effects on the imDCs’endocytosis ability.Furthermore,Tmod1 knockout DCs showed higher osmotic fragility,lower Young’s modulus,less F-actin content and shorter dendritic pseudopodia.Under LPS stimulation,the phosphorylation level of p65 and p38 were significantly downregulated in Tmod1 knockout mice while the expression of p-IRF3 was upregulated.Conclusions These results indicated that Tmodl knockout leads to deficient antigen-presenting ability and impaired migration of DCs as well as their biophysical properties.The underlying mechanisms are due to the inhibitions of the TLR4-mediated NF-κB and p38 MAPK singling pathway and the activation of the IRF3 signaling pathway,as well as the disturbed reorganization of the F-actin cytoskeleton.Our results provide a new insight on the functions of Tmod1 which can affect the DCs’immune functions and biophysical properties through regulating the TLR4-mediated singling pathways and cytoskeleton remodeling.展开更多
Cell reprograming technologies have broad applications in cell therapy,disease modeling and drug screening.Direct reprogramming is the process of converting from one cell type into a very distantly related cell type.I...Cell reprograming technologies have broad applications in cell therapy,disease modeling and drug screening.Direct reprogramming is the process of converting from one cell type into a very distantly related cell type.In this direct conversion process,cells do not proceed through a pluripotent stage,which can be time-consuming and challenging due to spontaneous differentiation.This method also offers the advantage of circumventing the teratoma potential that is associated with using iPSCs.Previous works have demonstrated that with the use of genetic manipulation,fibroblasts can be directly converted into other cell types,including neurons,cardiomyocytes,blood cell progenitors,and hepatocytes.It is well known that the microenvironment can directs cell fate,and in turn cells interact with or remodel their niches.Accumulative evidence suggests that biophysical factors such as the microtopography and mechanical property of cell adhesive substrates regulate a variety of cellular functions such as migration,proliferation and differentiation,which in turn can modulate wound healing,tissue remodeling and tumor growth,but there are limited number of studies on the roles of biophysical cues in cell reprogramming[1].Passive topographical cues offer a simple and effective method to improve reprogramming efficiency without the need for biochemical manipulations.Our previous study has demonstrated that somatic cells cultured on the parallel microgrooves,which can replace the effects of small-molecule epigenetic modifiers and significantly improve the iPSCs reprogramming efficiency.The mechanism relies on the mechanomodulation of the cells’epigenetic state,specifically,an increase of histone H3 acetylation and H3K4 methylation[2].Additionally,in cardiomyocytes reprogramming study,culturing the fibroblasts on microgrooved substrate enhances the expression of cardiomyocyte genes by day 2 and improves the yield of partially reprogrammed cells at day 10.By combining microgrooved substrate with an optimized culture protocol,the conversion from fibroblasts to cardiomyocytes is increased through genetic changes and structural organization of sarcomeres[3].Besides biomaterial topography,recent studies have demonstrated the effects of matrix stiffness on cell reprogramming.For example,a decrease of substrate stiffness can improve the iPSCs reprogramming efficiency,while an intermediate stiffness can significantly enhance the efficiency of neuronal reprogramming [4].Further analysis suggests that intracellular biomechanical changes play an important role in reprogramming process.Cells interact with the biophysical factors in the microenvironment through an'inside-out'and'outside-in'feedback loop,which is mediated by focal adhesions and cytoskeleton [5].Therefore,we investigated the role of the intracellular mechanical structure in cell reprogramming.We showed,for the first time,that the mechanical property of cells was modulated during the early phase of reprogramming as determined by atomic force microscopy(AFM)and high-throughput quantitative deformability cytometry(q-DC).We observed that cell stiffness increased by day 1 during reprogramming process,which was followed by a pronounced decrease within a few days.Examination of actin cytoskeleton showed that actin assembled into a network with a cage-like structure around the nucleus by day 1,but this structure along with the majority of the cytoskeleton gradually disappeared,coinciding with the changes in intracellular mechanical property.Furthermore,inhibition of actin contractility by using small molecules significantly altered the reprogramming efficiency.These findings provide new insights into the mechanisms of how biophysical cues modulate cell fate.In any given physiological microenvironment,cells may experience various of biophysical inputs,which,as we show,may affect cell phenotype changes.展开更多
基金Project(2007CB714407) supported by the Major State Basic Research and Development Program of ChinaProject(2004DFA06300) supported by Key International Collaboration Project in Science and TechnologyProjects(40571107, 40701102) supported by the National Natural Science Foundation of China
文摘In order to improve the accuracy of biophysical parameters retrieved from remotely sensing data, a new algorithm was presented by using spatial contextual to estimate canopy variables from high-resolution remote sensing images. The developed algorithm was used for inversion of leaf area index (LAI) from Enhanced Thematic Mapper Plus (ETM+) data by combining with optimization method to minimize cost functions. The results show that the distribution of LAI is spatially consistent with the false composition imagery from ETM+ and the accuracy of LAI is significantly improved over the results retrieved by the conventional pixelwise retrieval methods, demonstrating that this method can be reliably used to integrate spatial contextual information for inverting LAI from high-resolution remote sensing images.
基金funded by the National Natural Science Foundation of China ( 31660258,31771014, 31860262,31570938,31260227)the Science and Technology Foundation of Guizhou Province ( 2019-2787,2018-1412, 2016-5676,2017-5718)+2 种基金the Science and Technology Innovative Talent Team of Guizhou Province ( 2015-4021)the 2011 Collaborative Innovation Program of Guizhou Province ( 2015-04 )the Cell and Gene Engineering Innovative Research Groups of Guizhou Province ( KY-2016-031)
文摘Background Dendritic cells(DCs)are the most important antigen-presenting cells due to their professional and extremely efficient antigen-presenting function.The dynamics of cytoskeleton plays crucial regulated roles on DCs’immune functions and biophysical properties.Several evidences show that tumor-derived suppressive cytokines deteriorate DCs’immune functions through remodeling their F-actin cytoskeleton.But the underlying mechanism is still elusive.Tropomodulin1(Tmod1),a cytoskeleton-binding protein,regulates and stabilizes actin filaments lengths and cytoskeleton architecture,which involves in the regulations of the morphology,formation of neural dendrites and biophysical properties of cells.Our previous studies found that mature DCs(mDCs)had a higher expression of Tmod1 than immature DCs(imDCs). Therefore,it’s hypothesized that Tmod1 maybe involve in the modification of DCs’functions.Objective The aim of the study is to investigate the effects of Tmodl on the immune functions and biophysical properties of DCs and the underlying mechanisms in order to further understand the biological behaviors of DCs.Methods Bone marrow-derived cells were harvested from wild type(C57BL/6 J)mice and Tmod1 knockout mice(Tmod1 overexpressing transgenic(TOT)/Tmod1-/-)and differentiated to immature dendritic cells(imDCs)by rmGM-CSF and rmIL-4.imDCs were then matured by lipopolysaccharides(LPS)treatment.The expressions of the surface markers in DCs,including CD80,CD86,CD40,MHC-Ⅱand CCR7,were detected by flow cytometry,Western blot and qRT-PCR.The inflammation cytokines such as IL-6,IFN-γ,IFN-βand IL-10 were also detected by flow cytometry.The immune functions and the biophysical properties of DCs were compared between the wild type and Tmod1 knockout mice.The F-actin content and dendritic pseudopodia of these two kinds of DCs were detected by flow cytometry and laser scanning confocal microscope respectively.Finally,we detected the MyD88 dependent and independent signaling pathway to discover the molecular mechanisms.Results We found that Tmod1-deficient mDCs showed deficient antigen-presenting ability and they failed to express enough MHC-Ⅱ,co-stimulated molecules(CD80/86,CD40)and CCR7 on their cell surface.The secretions of the inflammatory cytokines IL-6 and IFN-γwere decreased while the anti-inflammatory cytokines IFN-βand IL-10 were increased in the supernatant of Tmod1-deficient mDCs.As compared to DCs of wild type mice,the migration ability of DCs from Tmod1 knockout mice were dramatically damaged including their free migration and CCL19 mediated chemotaxis migration.However,we found that Tmod1 knockout had no effects on the imDCs’endocytosis ability.Furthermore,Tmod1 knockout DCs showed higher osmotic fragility,lower Young’s modulus,less F-actin content and shorter dendritic pseudopodia.Under LPS stimulation,the phosphorylation level of p65 and p38 were significantly downregulated in Tmod1 knockout mice while the expression of p-IRF3 was upregulated.Conclusions These results indicated that Tmodl knockout leads to deficient antigen-presenting ability and impaired migration of DCs as well as their biophysical properties.The underlying mechanisms are due to the inhibitions of the TLR4-mediated NF-κB and p38 MAPK singling pathway and the activation of the IRF3 signaling pathway,as well as the disturbed reorganization of the F-actin cytoskeleton.Our results provide a new insight on the functions of Tmod1 which can affect the DCs’immune functions and biophysical properties through regulating the TLR4-mediated singling pathways and cytoskeleton remodeling.
基金supported in part by a grant from the National Institute of Health ( HL121450)UCLA Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research Innovation Award
文摘Cell reprograming technologies have broad applications in cell therapy,disease modeling and drug screening.Direct reprogramming is the process of converting from one cell type into a very distantly related cell type.In this direct conversion process,cells do not proceed through a pluripotent stage,which can be time-consuming and challenging due to spontaneous differentiation.This method also offers the advantage of circumventing the teratoma potential that is associated with using iPSCs.Previous works have demonstrated that with the use of genetic manipulation,fibroblasts can be directly converted into other cell types,including neurons,cardiomyocytes,blood cell progenitors,and hepatocytes.It is well known that the microenvironment can directs cell fate,and in turn cells interact with or remodel their niches.Accumulative evidence suggests that biophysical factors such as the microtopography and mechanical property of cell adhesive substrates regulate a variety of cellular functions such as migration,proliferation and differentiation,which in turn can modulate wound healing,tissue remodeling and tumor growth,but there are limited number of studies on the roles of biophysical cues in cell reprogramming[1].Passive topographical cues offer a simple and effective method to improve reprogramming efficiency without the need for biochemical manipulations.Our previous study has demonstrated that somatic cells cultured on the parallel microgrooves,which can replace the effects of small-molecule epigenetic modifiers and significantly improve the iPSCs reprogramming efficiency.The mechanism relies on the mechanomodulation of the cells’epigenetic state,specifically,an increase of histone H3 acetylation and H3K4 methylation[2].Additionally,in cardiomyocytes reprogramming study,culturing the fibroblasts on microgrooved substrate enhances the expression of cardiomyocyte genes by day 2 and improves the yield of partially reprogrammed cells at day 10.By combining microgrooved substrate with an optimized culture protocol,the conversion from fibroblasts to cardiomyocytes is increased through genetic changes and structural organization of sarcomeres[3].Besides biomaterial topography,recent studies have demonstrated the effects of matrix stiffness on cell reprogramming.For example,a decrease of substrate stiffness can improve the iPSCs reprogramming efficiency,while an intermediate stiffness can significantly enhance the efficiency of neuronal reprogramming [4].Further analysis suggests that intracellular biomechanical changes play an important role in reprogramming process.Cells interact with the biophysical factors in the microenvironment through an'inside-out'and'outside-in'feedback loop,which is mediated by focal adhesions and cytoskeleton [5].Therefore,we investigated the role of the intracellular mechanical structure in cell reprogramming.We showed,for the first time,that the mechanical property of cells was modulated during the early phase of reprogramming as determined by atomic force microscopy(AFM)and high-throughput quantitative deformability cytometry(q-DC).We observed that cell stiffness increased by day 1 during reprogramming process,which was followed by a pronounced decrease within a few days.Examination of actin cytoskeleton showed that actin assembled into a network with a cage-like structure around the nucleus by day 1,but this structure along with the majority of the cytoskeleton gradually disappeared,coinciding with the changes in intracellular mechanical property.Furthermore,inhibition of actin contractility by using small molecules significantly altered the reprogramming efficiency.These findings provide new insights into the mechanisms of how biophysical cues modulate cell fate.In any given physiological microenvironment,cells may experience various of biophysical inputs,which,as we show,may affect cell phenotype changes.
