Cytosine bases of the nuclear genome in higher plants are often extensively methylated.Cytosine methylation has been implicated in the silencing of both transposable elements （TEs） and endogenous genes,and loss of m...Cytosine bases of the nuclear genome in higher plants are often extensively methylated.Cytosine methylation has been implicated in the silencing of both transposable elements （TEs） and endogenous genes,and loss of methylation may have severe functional consequences.The recent methylation profiling of the entire Arabidopsis genome has provided novel insights into the extent and pattern of cytosine methylation and its relationships with gene activity.In addition,the fresh studies also revealed the more dynamic nature of this epigenetic modification across plant development than previously believed.Cytosine methylation of gene promoter regions usually inhibits transcription,but methylation in coding regions （gene-body methylation） does not generally affect gene expression.Active demethylation （though probably act synergistically with passive loss of methylation） of promoters by the 5-methyl cytosine DNA glycosylase or DEMETER （DME） is required for the uni-parental expression of imprinting genes in endosperm,which is essential for seed viability.The opinion that cytosine methylation is indispensible for normal plant development has been reinforced by using single or combinations of diverse loss-of-function mutants for DNA methyltransferases,DNA glycosylases,components involved in siRNA biogenesis and chromatin remodeling factors.Patterns of cytosine methylation in plants are usually faithfully maintained across organismal generations by the concerted action of epigenetic inheritance and progressive correction of strayed patterns.However,some variant methylation patterns may escape from being corrected and hence produce novel epialleles in the affected somatic cells.This,coupled with the unique property of plants to produce germline cells late during development,may enable the newly acquired epialleles to be inherited to future generations,which if visible to selection may contribute to adaptation and evolution.展开更多
Graphene has recently emerged as an important and exciting material.Inspired by its outstanding properties,many researchers have extensively studied graphene-related materials both experimentally and theoretically.Por...Graphene has recently emerged as an important and exciting material.Inspired by its outstanding properties,many researchers have extensively studied graphene-related materials both experimentally and theoretically.Porous graphene is a collection of graphene-related materials with nanopores in the plane.Porous graphene exhibits properties distinct from those of graphene,and it has widespread potential applications in various fields such as gas separation,hydrogen storage,DNA sequencing,and supercapacitors.In this review,we summarize recent progress in studies of the properties,preparation,and potential applications of porous graphene,and show that porous graphene is a promising material with great potential for future development.展开更多
The importance of NAC(named as NAM,ATAF1,2,and CUC2)proteins in plant development,transcription regulation and regulatory pathways involving proteinprotein interactions has been increasingly recognized.We report here ...The importance of NAC(named as NAM,ATAF1,2,and CUC2)proteins in plant development,transcription regulation and regulatory pathways involving proteinprotein interactions has been increasingly recognized.We report here the high resolution crystal structure of SNAC1(stress-responsive NAC)NAC domain at 2.5Å.Although the structure of the SNAC1 NAC domain shares a structural similarity with the reported structure of the ANAC NAC1 domain,some key features,especially relating to two loop regions which potentially take the responsibility for DNA-binding,distinguish the SNAC1 NAC domain from other reported NAC structures.Moreover,the dimerization of the SNAC1 NAC domain is demonstrated by both soluble and crystalline conditions,suggesting this dimeric state should be conserved in this type of NAC family.Additionally,we discuss the possible NAC-DNA binding model according to the structure and reported biological evidences.展开更多
基金supported by the National Natural Science Foundation of China (No. 30870198 and 30870178)the Programme of Introducing Talents of Discipline to Universities of China (No. B07017)
文摘Cytosine bases of the nuclear genome in higher plants are often extensively methylated.Cytosine methylation has been implicated in the silencing of both transposable elements （TEs） and endogenous genes,and loss of methylation may have severe functional consequences.The recent methylation profiling of the entire Arabidopsis genome has provided novel insights into the extent and pattern of cytosine methylation and its relationships with gene activity.In addition,the fresh studies also revealed the more dynamic nature of this epigenetic modification across plant development than previously believed.Cytosine methylation of gene promoter regions usually inhibits transcription,but methylation in coding regions （gene-body methylation） does not generally affect gene expression.Active demethylation （though probably act synergistically with passive loss of methylation） of promoters by the 5-methyl cytosine DNA glycosylase or DEMETER （DME） is required for the uni-parental expression of imprinting genes in endosperm,which is essential for seed viability.The opinion that cytosine methylation is indispensible for normal plant development has been reinforced by using single or combinations of diverse loss-of-function mutants for DNA methyltransferases,DNA glycosylases,components involved in siRNA biogenesis and chromatin remodeling factors.Patterns of cytosine methylation in plants are usually faithfully maintained across organismal generations by the concerted action of epigenetic inheritance and progressive correction of strayed patterns.However,some variant methylation patterns may escape from being corrected and hence produce novel epialleles in the affected somatic cells.This,coupled with the unique property of plants to produce germline cells late during development,may enable the newly acquired epialleles to be inherited to future generations,which if visible to selection may contribute to adaptation and evolution.
基金supported by the"100Projects"of Creative Research for the Undergraduates of Nankai University(BX9-179)the National Natural Science Foundation of China(21073096)
文摘Graphene has recently emerged as an important and exciting material.Inspired by its outstanding properties,many researchers have extensively studied graphene-related materials both experimentally and theoretically.Porous graphene is a collection of graphene-related materials with nanopores in the plane.Porous graphene exhibits properties distinct from those of graphene,and it has widespread potential applications in various fields such as gas separation,hydrogen storage,DNA sequencing,and supercapacitors.In this review,we summarize recent progress in studies of the properties,preparation,and potential applications of porous graphene,and show that porous graphene is a promising material with great potential for future development.
基金the National Natural Science Foundation of China(Grant Nos.30730022 and 30870486)the National Basic Research Program(973 Program)(Grant No.2007CB914304)the National Major Projects(grant Nos.2009ZX09311-001 and 2009ZX10004-304).
文摘The importance of NAC(named as NAM,ATAF1,2,and CUC2)proteins in plant development,transcription regulation and regulatory pathways involving proteinprotein interactions has been increasingly recognized.We report here the high resolution crystal structure of SNAC1(stress-responsive NAC)NAC domain at 2.5Å.Although the structure of the SNAC1 NAC domain shares a structural similarity with the reported structure of the ANAC NAC1 domain,some key features,especially relating to two loop regions which potentially take the responsibility for DNA-binding,distinguish the SNAC1 NAC domain from other reported NAC structures.Moreover,the dimerization of the SNAC1 NAC domain is demonstrated by both soluble and crystalline conditions,suggesting this dimeric state should be conserved in this type of NAC family.Additionally,we discuss the possible NAC-DNA binding model according to the structure and reported biological evidences.
