Background:Robinia pseudoacacia is a widely planted pioneer tree species in reforestations on barren mountains in northern China.Because of its nitrogen-fixing ability,it can play a positive role in soil and forest re...Background:Robinia pseudoacacia is a widely planted pioneer tree species in reforestations on barren mountains in northern China.Because of its nitrogen-fixing ability,it can play a positive role in soil and forest restoration.After clearcutting of planted stands,R.pseudoacacia stands become coppice plantations.The impacts of shifting from seedling to coppice stands on soil bacterial community and soil properties have not been wel described.This study aims to quantify how soil properties and bacterial community composition vary between planted seedling versus coppice stands.Methods:Nine 20 m×20 m plots were randomly selected in seedling and coppice stands.The bulk soil and rhizosphere soil were sampled in summer 2017.Bulk soil was sampled at 10 cm from the soil surface using a soil auger.Rhizosphere soil samples were col ected using a brush.The soil samples were transported to the laboratory for chemical analysis,and bacterial community composition and diversity was obtained through DNA extraction,16 S r RNA gene amplification and high-throughput sequencing.Results:The results showed that,compared to seedling plantations,soil quality decreased significantly in coppice stands,but without affecting soil exchangeable Mg^(2+) and K^(+).Total carbon(C)and nitrogen(N)were lower in the rhizosphere than in bulk soil,whereas nutrient availability showed an opposite trend.The conversion from seedling to coppice plantations was also related to significant differences in soil bacterial community structure and to the reduction of soil bacterialα-diversity.Principal component analysis(PCA)showed that bacterial community composition was similar in both bulk and rhizosphere soils in second-generation coppice plantations.Special y,the conversion from seedling to coppice stands increased the relative abundance of Proteobacteria and Rhizobium,but reduced that of Actinobacteria,which may result in a decline of soil nutrient availability.Mantel tests revealed that C,N,soil organic matter(SOM),nitrate nitrogen(NO^(-)+(3)-N)and available phosphorus positively correlated with bacterial community composition,while a variation partition analysis(VPA)showed that NO^(-)+(3)-N explained a relatively greater proportion of bacterial distribution(15.12%),compared with C and SOM.Surprisingly,N showed no relationship with bacterial community composition,which may be related to nitrogen transportation.Conclusions:The conversion from seedling to coppice stands reduced soil quality and led to spatial-temporal homogenization of the soil bacterial community structure in both the rhizosphere and bulk soils.Such imbalance in microbial structure can accelerate the decline of R.pseudoacacia.This may affect the role of R.pseudoacacia coppice stands in soil and forest restoration of barren lands in mountain areas.展开更多
Atherosclerosis is a chronic multifactorial cardiovascular disease.Western diets have been reported to affect atherosclerosis through regulating adipose function.In high cholesterol diet-fed ApoE^(−/−)mice,adipocyte H...Atherosclerosis is a chronic multifactorial cardiovascular disease.Western diets have been reported to affect atherosclerosis through regulating adipose function.In high cholesterol diet-fed ApoE^(−/−)mice,adipocyte HIF-1αdeficiency or direct inhibition of HIF-1αby the selective pharmacological HIF-1αinhibitor PX-478 alleviates high cholesterol diet-induced atherosclerosis by reducing adipose ceramide generation,which lowers cholesterol levels and reduces inflammatory responses,resulting in improved dyslipidemia and atherogenesis.Smpd3,the gene encoding neutral sphingomyelinase,is identified as a new target gene directly regulated by HIF-1αthat is involved in ceramide generation.Injection of lentivirus-SMPD3 in epididymal adipose tissue reverses the decrease in ceramides in adipocytes and eliminates the improvements on atherosclerosis in the adipocyte HIF-1α-deficient mice.Therefore,HIF-1αinhibition may constitute a novel approach to slow atherosclerotic progression.展开更多
In this work,the medium internal phase O/W Pickering emulsions stabilized with bamboo shoots nanocellulose(BSNC)was successfully fabricated.The nanocellulose extracted from bamboo shoots with an average width of 56.37...In this work,the medium internal phase O/W Pickering emulsions stabilized with bamboo shoots nanocellulose(BSNC)was successfully fabricated.The nanocellulose extracted from bamboo shoots with an average width of 56.37 nm and height of 7.44 nm showed great potential as an emulsifier in the Pickering emulsions.The effects of BSNC content,oil-water ratio and emulsification process on the structure,stability and rheology of the resultant Pickering emulsions was explored.The obtained emulsion with the BSNC content of 0.5 wt%at the oil to water volume ratio of 5:5 had a lower particle size of around 25μm.With the increasing BSNC content,the emulsions presented increased droplet size,and even demulsification occurred.Interestingly,the physicochemical properties of the emulsions could be significantly improved through twice shearing,which effectively reduced droplet size.The surface coverage was above 100%for the Pickering emulsions stabilized with the BSNC content of 0.5%-1.1%.With the increasing BSNC content,the apparent viscosity was increased first and then decreased,and all emulsions showed elastic behaviors.This work would provide theoretical guidance for preparing medium or high internal phase Pickering emulsions stabilized with nanocellulose.展开更多
基金financially supported by the Special Fund for Forestry Scientific Research in the Public Interest No.201504406the National Natural Science Foundation of China(Nos.31570705,31500362,31700553)+4 种基金the Shandong Provincial Natural Science Foundation,China(No.ZR2016CP01)the Project of Shandong Province Higher Educational Science and Technology Program(No.J16LF09)China Scholarship Council(No.201809135006)The contribution of S.de-Miguel was supported by the Spanish Ministry of Economy and Competitivity(MINECO)(Grant No.RTI2018–099315-A-I00)by a Serra-Húnter Fellowship provided by the Generalitat of Catalonia。
文摘Background:Robinia pseudoacacia is a widely planted pioneer tree species in reforestations on barren mountains in northern China.Because of its nitrogen-fixing ability,it can play a positive role in soil and forest restoration.After clearcutting of planted stands,R.pseudoacacia stands become coppice plantations.The impacts of shifting from seedling to coppice stands on soil bacterial community and soil properties have not been wel described.This study aims to quantify how soil properties and bacterial community composition vary between planted seedling versus coppice stands.Methods:Nine 20 m×20 m plots were randomly selected in seedling and coppice stands.The bulk soil and rhizosphere soil were sampled in summer 2017.Bulk soil was sampled at 10 cm from the soil surface using a soil auger.Rhizosphere soil samples were col ected using a brush.The soil samples were transported to the laboratory for chemical analysis,and bacterial community composition and diversity was obtained through DNA extraction,16 S r RNA gene amplification and high-throughput sequencing.Results:The results showed that,compared to seedling plantations,soil quality decreased significantly in coppice stands,but without affecting soil exchangeable Mg^(2+) and K^(+).Total carbon(C)and nitrogen(N)were lower in the rhizosphere than in bulk soil,whereas nutrient availability showed an opposite trend.The conversion from seedling to coppice plantations was also related to significant differences in soil bacterial community structure and to the reduction of soil bacterialα-diversity.Principal component analysis(PCA)showed that bacterial community composition was similar in both bulk and rhizosphere soils in second-generation coppice plantations.Special y,the conversion from seedling to coppice stands increased the relative abundance of Proteobacteria and Rhizobium,but reduced that of Actinobacteria,which may result in a decline of soil nutrient availability.Mantel tests revealed that C,N,soil organic matter(SOM),nitrate nitrogen(NO^(-)+(3)-N)and available phosphorus positively correlated with bacterial community composition,while a variation partition analysis(VPA)showed that NO^(-)+(3)-N explained a relatively greater proportion of bacterial distribution(15.12%),compared with C and SOM.Surprisingly,N showed no relationship with bacterial community composition,which may be related to nitrogen transportation.Conclusions:The conversion from seedling to coppice stands reduced soil quality and led to spatial-temporal homogenization of the soil bacterial community structure in both the rhizosphere and bulk soils.Such imbalance in microbial structure can accelerate the decline of R.pseudoacacia.This may affect the role of R.pseudoacacia coppice stands in soil and forest restoration of barren lands in mountain areas.
基金This work was supported by the National Key Research and Development Program of China(2018YFA0800700 and 2018YFC1003900)the National Natural Science Foundation of China(Nos.91857115,31925021,82022028 and 81921001).
文摘Atherosclerosis is a chronic multifactorial cardiovascular disease.Western diets have been reported to affect atherosclerosis through regulating adipose function.In high cholesterol diet-fed ApoE^(−/−)mice,adipocyte HIF-1αdeficiency or direct inhibition of HIF-1αby the selective pharmacological HIF-1αinhibitor PX-478 alleviates high cholesterol diet-induced atherosclerosis by reducing adipose ceramide generation,which lowers cholesterol levels and reduces inflammatory responses,resulting in improved dyslipidemia and atherogenesis.Smpd3,the gene encoding neutral sphingomyelinase,is identified as a new target gene directly regulated by HIF-1αthat is involved in ceramide generation.Injection of lentivirus-SMPD3 in epididymal adipose tissue reverses the decrease in ceramides in adipocytes and eliminates the improvements on atherosclerosis in the adipocyte HIF-1α-deficient mice.Therefore,HIF-1αinhibition may constitute a novel approach to slow atherosclerotic progression.
基金This work was supported by the National Nature Science Foundation of China(32072177).
文摘In this work,the medium internal phase O/W Pickering emulsions stabilized with bamboo shoots nanocellulose(BSNC)was successfully fabricated.The nanocellulose extracted from bamboo shoots with an average width of 56.37 nm and height of 7.44 nm showed great potential as an emulsifier in the Pickering emulsions.The effects of BSNC content,oil-water ratio and emulsification process on the structure,stability and rheology of the resultant Pickering emulsions was explored.The obtained emulsion with the BSNC content of 0.5 wt%at the oil to water volume ratio of 5:5 had a lower particle size of around 25μm.With the increasing BSNC content,the emulsions presented increased droplet size,and even demulsification occurred.Interestingly,the physicochemical properties of the emulsions could be significantly improved through twice shearing,which effectively reduced droplet size.The surface coverage was above 100%for the Pickering emulsions stabilized with the BSNC content of 0.5%-1.1%.With the increasing BSNC content,the apparent viscosity was increased first and then decreased,and all emulsions showed elastic behaviors.This work would provide theoretical guidance for preparing medium or high internal phase Pickering emulsions stabilized with nanocellulose.
