The Changbai Mountains and the Appalachian Mountains have similar spatial contexts.The elevation,latitude,and moisture gradients of both mountain ranges offer regional insight for investigating the vegetation dynamics...The Changbai Mountains and the Appalachian Mountains have similar spatial contexts.The elevation,latitude,and moisture gradients of both mountain ranges offer regional insight for investigating the vegetation dynamics in eastern Eurasia and eastern North America.We determined and compared the spatial patterns and temporal trends in the normalized difference vegetation index(NDVI)in the Changbai Mountains and the Appalachian Mountains using time series data from the Global Inventory Modeling and Mapping Studies 3^(rd) generation dataset from 1982 to 2013.The spatial pattern of NDVI in the Changbai Mountains exhibited fragmentation,whereas NDVI in the Appalachian Mountains decreased from south to north.The vegetation dynamics in the Changbai Mountains had an insignificant trend at the regional scale,whereas the dynamics in the Appalachian Mountains had a significant increasing trend.NDVI increased in 55% of the area of the Changbai Mountains and in 95% of the area of the Appalachian Mountains.The peak NDVI occurred one month later in the Changbai Mountains than in the Appalachian Mountains.The results revealed a significant increase in NDVI in autumn in both mountain ranges.The climatic trend in the Changbai Mountains included warming and decreased precipitation,and whereas that in the Appalachian Mountains included significant warming and increased precipitation.Positive and negative correlations existed between NDVI and temperature and precipitation,respectively,in both mountain ranges.Particularly,the spring temperature and NDVI exhibited a significant positive correlation in both mountain ranges.The results of this study suggest that human actives caused the differences in the spatial patterns of NDVI and that various characteristics of climate change and intensity of human actives dominated the differences in the NDVI trends between the Changbai Mountains and the Appalachian Mountains.Additionally,the vegetation dynamics of both mountain ranges were not identical to those in previous broader-scale studies.展开更多
Increasing evidence suggests that Cyclin A-Cdk2 activity is required in the apoptosis process induced by various stimuli.To determine a specific substrate of Cyclin A-Cdk2 for apoptosis,in this study,we carried out an...Increasing evidence suggests that Cyclin A-Cdk2 activity is required in the apoptosis process induced by various stimuli.To determine a specific substrate of Cyclin A-Cdk2 for apoptosis,in this study,we carried out an in vitro kinase assay using immunoprecipitated complex Cyclin A-Cdk2 as an enzyme source,and recombinant protein GST-Bad as a substrate.Our study showed that Bad was clearly phosphorylated by Cyclin A-Cdk2 in vitro.To examine whether protein Bad can also be phosphorylated by Cyclin A-Cdk2 kinase in vivo,we transiently overexpressed protein Bad with Cyclin A or Cdk2-dn,a dominant negative version of Cdk2,in Hela cells and determined the phosphorylation status of protein Bad.The test showed that protein Bad was clearly phosphorylated in Cyclin A overexpressed cells,but not in Cdk2-dn or mock transfectent.Moreover,etoposide also caused the phosphorylation of endogenetic Bad.In conclusion,here we provide first time evidence that protein Bad can be a substrate of Cyclin A-Cdk2 apoptosis for in vitro and in vivo.展开更多
Betulinic acid and its derivatives have been extensively studied in the past for their anti-tumor effects, but relatively little is known about its precursor betulin. In this study we showed that betulin, an abundant ...Betulinic acid and its derivatives have been extensively studied in the past for their anti-tumor effects, but relatively little is known about its precursor betulin. In this study we showed that betulin, an abundant natural product, significantly inhibits the cell growth of human hepatoma HepG2 cells in a dose-dependent manner. In the presence of 10 μg/mL betulin, HepG2 cells undergo an apoptosis, as evidenced by apoptotic morphology such as cell shrinkage, membrane blebbing, nuclear condensation and fragmentation, apoptotic body formation, and caspase activation. Kinetics analysis shows that the depolarization of the mitochondrial membrane potential and the release of the mito- chondrial apoptotic protein cytochrome c occurred as early as 2 h post treatment of HepG2 cells with 10 μg/mL betulin. Proteolytic activation of caspase-9, but not caspase-8, was observed in this apoptosis process. Moreover, the inactivation of caspase-9 by its specific siRNA dramatically reduced betulin-induced caspase-3 activation and apoptosis. Taken together, our observations indicate that the activation of caspase-9 is critical for betulin-induced apoptosis of human hepatoma HepG2 cells.展开更多
Global climate changes result in the expansion of lower elevation plants to higher elevations.The rapid upward expansion of herbaceous plants into the alpine tundra on Changbai Mountain resulted in changes in differen...Global climate changes result in the expansion of lower elevation plants to higher elevations.The rapid upward expansion of herbaceous plants into the alpine tundra on Changbai Mountain resulted in changes in different levels of ecosystem organization.However,the responses and feedback of litter properties and soil mesofauna to herbaceous plants expansion have not been studied yet.To understand the mechanisms underlying those changes,we conducted a field experiment in the range of 2250-2300 m in the alpine tundra of the Changbai Mountain and collected a total of 288 samples from four degrees of herbaceous plants expansion to study the litter physiochemical properties,soil mesofauna,and soil nutrient contents,and their relationships in that tundra ecosystem suffered from various degrees of herbaceous invasion.We found that herbaceous plant expansion is responsible for a major shift in the dominant species of soil mesofauna from mites to collembolan and has significant impacts on the community structure(R2=0.54,p=0.001)and diversity of soil mesofauna(Shannon-Weiner index,p=0.01).The increasing herbaceous plant expansion resulted in a significant increase in litter biomass from 91 g·m^(-2) in the original tundra vegetation(OIT)to 118 g·m^(-2) in the moderately invaded tundra(MIT),and an increase in litter thickness from 2.37 cm(OIT)to 3.05 cm(MIT).And,the litter total nitrogen content significantly increased,but the values of the litter carbon content,the lignin content,the C/N ratio,and the lignin/N ratio decreased with increased herbaceous coverage(both p<0.05).The litter physical properties pathway(biomass and thickness)directly explained 31% of the total variance in soil mesofauna diversity and 59% of the total variance in soil mesofauna community composition.Furthermore,both the soil available nutrients(incl.AN and AP)and plant biomass(incl.the total plant biomass and herbs/shrubs biomass)significantly increased with increasing coverage of herbaceous plant(both p<0.05),and litter chemical properties pathway directly explained 50% of the soil nutrient content variance and indirectly explained 20% of soil nutrient by affecting soil mesofauna.We found that both soil available nutrients and soil mesofauna were positively correlated with the herbaceous expansion from OIT to MIT,indicating a positive feedback of herbaceous expansion,and the abundance of soil mesofauna decreased in the severely invaded tundra vegetation,suggesting a negative feedback.While,both litter N content and soil available nitrogen were consistently increased in the severely invaded tundra vegetation,indicating a positive feedback of herbaceous expansion.Therefore,this study provides new insights into the process of herbaceous plant expansion into tundra,and provides possible evidence for further expansion according to responses and feedback of in litter properties and soil mesofauna to herbaceous plants expansion.Furthermore,these positive or/and negative feedback systems in the Changbai alpine tundra ecosystem in relation to herbaceous expansion have important implications for the tundra protection,and thus,need to be deeply studied.展开更多
Recent observations indicate that the resistance of apoptosis is an important process of tumor metastasis and metastases are the cause of 90% of human cancer death. Etoposide, a semisynthetic derivative of the podophy...Recent observations indicate that the resistance of apoptosis is an important process of tumor metastasis and metastases are the cause of 90% of human cancer death. Etoposide, a semisynthetic derivative of the podophyllotoxins, is a clinically used anti-cancer reagent, but the effects of it on metastatic gastric carcinoma cells are totally unknown. In this study, etoposide induced apoptotic cell death in human gastric adenocarcinoma cell line SGC-7901, derived from metastatic lymph nodes, as evidenced by the analysis of DNA fragmentation, apoptotic body formation, caspase activation, and apoptosis specific changes in cell morphology is demonstrated. The depolarization of mitochondrial membrane and the release of cytochrome c were most early events in etoposide treated SGC-7901 cells, and were followed by caspase-3 activation and PARP cleavage. Caspase-8 activation was not detected under the same condition. Thus, it was proposed that etoposide induces caspase-associated apoptotic cell death in human metastatic gastric carcinoma, which is initiated by mitochondrial cytochrome c release.展开更多
Parkinson＇s disease（PD） is a common neurodegenerative disorder whose primary pathology features are the degeneration of dopaminergic neurons in the substantia nigra pars compacta（SNc） and the presence of eosinoph...Parkinson＇s disease（PD） is a common neurodegenerative disorder whose primary pathology features are the degeneration of dopaminergic neurons in the substantia nigra pars compacta（SNc） and the presence of eosinophilic inclusions called Lewy body in the cytoplasm of the remained neurons. Growing evidence suggests that dysfunction of the ubiquitin-proteasome system（UPS） is involved in the etiopathogenesis of PD. In order to investigate the pathogenetic mechanism of ubiquitin-proteasome dysfunction in PD, 2D-differential gel electrophoresis（2D-DIGE） and MALDI-TOF Pro MS were used to determine the proteins, which were differentially expressed, in PC12 cells that had undergone a synthetic proteasomal inhibitor PSI（10 μmol/L） treatment for 24 h. Forty-six protein spots were differentially expressed in response to PSI administration, of which 34 were increased and 12 decreased. Six of these were identified as molecular charperones： endoplasmin precursor（GRP94）, heat shock protein 105（HSP105）, HSC-70-psl, glucose ruglated protein 75（GRP75）, glucose ruglated protein 58（GRP58） and heat shock 27000 protein l（HSP27）. The results suggest that the molecular chaperones play an important role in the PD model induced by proteasomal inhibitor.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 41601438 and 41571078)the Fundamental Research Funds for the Central Universities (Grant No.2412016KJ026)the Foundation of the Education Department of Jilin Province in the 13~(th) Five-Year project (Grant No. JJKH20170916KJ)
文摘The Changbai Mountains and the Appalachian Mountains have similar spatial contexts.The elevation,latitude,and moisture gradients of both mountain ranges offer regional insight for investigating the vegetation dynamics in eastern Eurasia and eastern North America.We determined and compared the spatial patterns and temporal trends in the normalized difference vegetation index(NDVI)in the Changbai Mountains and the Appalachian Mountains using time series data from the Global Inventory Modeling and Mapping Studies 3^(rd) generation dataset from 1982 to 2013.The spatial pattern of NDVI in the Changbai Mountains exhibited fragmentation,whereas NDVI in the Appalachian Mountains decreased from south to north.The vegetation dynamics in the Changbai Mountains had an insignificant trend at the regional scale,whereas the dynamics in the Appalachian Mountains had a significant increasing trend.NDVI increased in 55% of the area of the Changbai Mountains and in 95% of the area of the Appalachian Mountains.The peak NDVI occurred one month later in the Changbai Mountains than in the Appalachian Mountains.The results revealed a significant increase in NDVI in autumn in both mountain ranges.The climatic trend in the Changbai Mountains included warming and decreased precipitation,and whereas that in the Appalachian Mountains included significant warming and increased precipitation.Positive and negative correlations existed between NDVI and temperature and precipitation,respectively,in both mountain ranges.Particularly,the spring temperature and NDVI exhibited a significant positive correlation in both mountain ranges.The results of this study suggest that human actives caused the differences in the spatial patterns of NDVI and that various characteristics of climate change and intensity of human actives dominated the differences in the NDVI trends between the Changbai Mountains and the Appalachian Mountains.Additionally,the vegetation dynamics of both mountain ranges were not identical to those in previous broader-scale studies.
基金Supported by the National Natural Science Foundation of China(Nos.30370294and30640064).
文摘Increasing evidence suggests that Cyclin A-Cdk2 activity is required in the apoptosis process induced by various stimuli.To determine a specific substrate of Cyclin A-Cdk2 for apoptosis,in this study,we carried out an in vitro kinase assay using immunoprecipitated complex Cyclin A-Cdk2 as an enzyme source,and recombinant protein GST-Bad as a substrate.Our study showed that Bad was clearly phosphorylated by Cyclin A-Cdk2 in vitro.To examine whether protein Bad can also be phosphorylated by Cyclin A-Cdk2 kinase in vivo,we transiently overexpressed protein Bad with Cyclin A or Cdk2-dn,a dominant negative version of Cdk2,in Hela cells and determined the phosphorylation status of protein Bad.The test showed that protein Bad was clearly phosphorylated in Cyclin A overexpressed cells,but not in Cdk2-dn or mock transfectent.Moreover,etoposide also caused the phosphorylation of endogenetic Bad.In conclusion,here we provide first time evidence that protein Bad can be a substrate of Cyclin A-Cdk2 apoptosis for in vitro and in vivo.
基金Supported by the National Natural Science Foundation of China(No.30770447 and 90813003)
文摘Betulinic acid and its derivatives have been extensively studied in the past for their anti-tumor effects, but relatively little is known about its precursor betulin. In this study we showed that betulin, an abundant natural product, significantly inhibits the cell growth of human hepatoma HepG2 cells in a dose-dependent manner. In the presence of 10 μg/mL betulin, HepG2 cells undergo an apoptosis, as evidenced by apoptotic morphology such as cell shrinkage, membrane blebbing, nuclear condensation and fragmentation, apoptotic body formation, and caspase activation. Kinetics analysis shows that the depolarization of the mitochondrial membrane potential and the release of the mito- chondrial apoptotic protein cytochrome c occurred as early as 2 h post treatment of HepG2 cells with 10 μg/mL betulin. Proteolytic activation of caspase-9, but not caspase-8, was observed in this apoptosis process. Moreover, the inactivation of caspase-9 by its specific siRNA dramatically reduced betulin-induced caspase-3 activation and apoptosis. Taken together, our observations indicate that the activation of caspase-9 is critical for betulin-induced apoptosis of human hepatoma HepG2 cells.
基金funded by the Natural Science Foundation of China(Grants No.41571078 and 41171072)。
文摘Global climate changes result in the expansion of lower elevation plants to higher elevations.The rapid upward expansion of herbaceous plants into the alpine tundra on Changbai Mountain resulted in changes in different levels of ecosystem organization.However,the responses and feedback of litter properties and soil mesofauna to herbaceous plants expansion have not been studied yet.To understand the mechanisms underlying those changes,we conducted a field experiment in the range of 2250-2300 m in the alpine tundra of the Changbai Mountain and collected a total of 288 samples from four degrees of herbaceous plants expansion to study the litter physiochemical properties,soil mesofauna,and soil nutrient contents,and their relationships in that tundra ecosystem suffered from various degrees of herbaceous invasion.We found that herbaceous plant expansion is responsible for a major shift in the dominant species of soil mesofauna from mites to collembolan and has significant impacts on the community structure(R2=0.54,p=0.001)and diversity of soil mesofauna(Shannon-Weiner index,p=0.01).The increasing herbaceous plant expansion resulted in a significant increase in litter biomass from 91 g·m^(-2) in the original tundra vegetation(OIT)to 118 g·m^(-2) in the moderately invaded tundra(MIT),and an increase in litter thickness from 2.37 cm(OIT)to 3.05 cm(MIT).And,the litter total nitrogen content significantly increased,but the values of the litter carbon content,the lignin content,the C/N ratio,and the lignin/N ratio decreased with increased herbaceous coverage(both p<0.05).The litter physical properties pathway(biomass and thickness)directly explained 31% of the total variance in soil mesofauna diversity and 59% of the total variance in soil mesofauna community composition.Furthermore,both the soil available nutrients(incl.AN and AP)and plant biomass(incl.the total plant biomass and herbs/shrubs biomass)significantly increased with increasing coverage of herbaceous plant(both p<0.05),and litter chemical properties pathway directly explained 50% of the soil nutrient content variance and indirectly explained 20% of soil nutrient by affecting soil mesofauna.We found that both soil available nutrients and soil mesofauna were positively correlated with the herbaceous expansion from OIT to MIT,indicating a positive feedback of herbaceous expansion,and the abundance of soil mesofauna decreased in the severely invaded tundra vegetation,suggesting a negative feedback.While,both litter N content and soil available nitrogen were consistently increased in the severely invaded tundra vegetation,indicating a positive feedback of herbaceous expansion.Therefore,this study provides new insights into the process of herbaceous plant expansion into tundra,and provides possible evidence for further expansion according to responses and feedback of in litter properties and soil mesofauna to herbaceous plants expansion.Furthermore,these positive or/and negative feedback systems in the Changbai alpine tundra ecosystem in relation to herbaceous expansion have important implications for the tundra protection,and thus,need to be deeply studied.
基金the National Natural Science Foundation of China(Nos.30640064 and 30770447).
文摘Recent observations indicate that the resistance of apoptosis is an important process of tumor metastasis and metastases are the cause of 90% of human cancer death. Etoposide, a semisynthetic derivative of the podophyllotoxins, is a clinically used anti-cancer reagent, but the effects of it on metastatic gastric carcinoma cells are totally unknown. In this study, etoposide induced apoptotic cell death in human gastric adenocarcinoma cell line SGC-7901, derived from metastatic lymph nodes, as evidenced by the analysis of DNA fragmentation, apoptotic body formation, caspase activation, and apoptosis specific changes in cell morphology is demonstrated. The depolarization of mitochondrial membrane and the release of cytochrome c were most early events in etoposide treated SGC-7901 cells, and were followed by caspase-3 activation and PARP cleavage. Caspase-8 activation was not detected under the same condition. Thus, it was proposed that etoposide induces caspase-associated apoptotic cell death in human metastatic gastric carcinoma, which is initiated by mitochondrial cytochrome c release.
文摘Parkinson＇s disease（PD） is a common neurodegenerative disorder whose primary pathology features are the degeneration of dopaminergic neurons in the substantia nigra pars compacta（SNc） and the presence of eosinophilic inclusions called Lewy body in the cytoplasm of the remained neurons. Growing evidence suggests that dysfunction of the ubiquitin-proteasome system（UPS） is involved in the etiopathogenesis of PD. In order to investigate the pathogenetic mechanism of ubiquitin-proteasome dysfunction in PD, 2D-differential gel electrophoresis（2D-DIGE） and MALDI-TOF Pro MS were used to determine the proteins, which were differentially expressed, in PC12 cells that had undergone a synthetic proteasomal inhibitor PSI（10 μmol/L） treatment for 24 h. Forty-six protein spots were differentially expressed in response to PSI administration, of which 34 were increased and 12 decreased. Six of these were identified as molecular charperones： endoplasmin precursor（GRP94）, heat shock protein 105（HSP105）, HSC-70-psl, glucose ruglated protein 75（GRP75）, glucose ruglated protein 58（GRP58） and heat shock 27000 protein l（HSP27）. The results suggest that the molecular chaperones play an important role in the PD model induced by proteasomal inhibitor.
