TET酶的生物学功能及相关机制的研究进展

DNA甲基化（DNA methylation）及去甲基化属于常见的表观遗传修饰,可介导多种生理和病理过程。DNA甲基化及去甲基化修饰参与基因的表达调控,且二者的动态平衡可以维持遗传表达稳定性。DNA甲基转移酶（DNA methyltransferase,DNMT）主要包括DNMT1、DNMT3A、DNMT3B、DNMT3L,DNA去甲基化酶（DNA demethylase）主要指10-11易位蛋白（ten-eleven-translocation protein,TET）家族,包括TET1、TET2、TET3,是调节DNA甲基化和去甲基化的重要酶类。TET酶是目前发现的调节DNA去甲基化（DNA demethylation）过程中最重要的酶。综述了TET酶在DNA去甲基化修饰中的作用机制,探讨了DNA去甲基化酶在生长发育和疾病中的关键作用,以期为今后表观遗传学的相关研究提供新思路。     

The apple FERONIA receptor-like kinase MdMRLK2 negatively regulates Valsa canker resistance by suppressing defence responses and hypersensitive reaction

Valsa canker, caused by the fungus Valsa mali, is one of the most destructive diseases of apple trees in China and other East Asian countries. The plant receptor-like kinase FERONIA is involved in plant cell growth, development, and immunity. However, little is known about the function of FERONIA in apple defence against V. mali. In this study, we found that MdMRLK2 was highly induced by V. mali in twigs of V. mali-susceptible Malus mellana but not in those of the resistant species Malus yunnaensis. 35S:MdMRLK2 apple plants showed compromised resistance relative to wild-type (WT) plants. Further analyses indicated that 35S:MdMRLK2 apple plants had enhanced abscisic acid (ABA) levels and reduced salicylic acid (SA) levels relative to the WT on V. mali infection. MdMRLK2 overexpression also suppressed polyphenol accumulation and inhibited the activities of phenylalanine ammonia-lyase (PAL), β-1,3-glucanase (GLU), and chitinase (CHT) during V. mali infection. Moreover, MdMRLK2 interacted with MdHIR1, a hypersensitive-induced response protein, and suppressed the MdHIR1-mediated hypersensitive reaction (HR), probably by impairing MdHIR1 self-interaction. Collectively, these findings demonstrate that overexpression of MdMRLK2 compromises Valsa canker resistance, probably by (a) altering ABA and SA levels, (b) suppressing polyphenol accumulation, (c) inhibiting PAL, GLU, and CHT activities, and (d) blocking MdHIR1-mediated HR by disrupting MdHIR1 self-interaction.     

羊肚菌多糖提取分离及生物活性研究进展*

羊肚菌(Morchella spp.)是一种珍稀食药用真菌,从羊肚菌中提取的多糖在抗癌、抗氧化、降血糖、降血脂及免疫调节等方面具有良好的生物活性,在食品、药品和保健品开发方面具有广阔的应用前景。羊肚菌多糖的有效提取是对其进行结构解析和生物活性研究的基础,不同的提取方式对羊肚菌多糖的结构和生物活性具有一定影响。羊肚菌多糖的结构特性如分子量、单糖组成、一级结构等,对其生物活性具有很大影响,因此研究羊肚菌多糖的结构对揭示其生物活性及作用机制具有重要意义。针对羊肚菌多糖进行综述,总结羊肚菌多糖提取分离、结构解析及生物活性的研究进展,分析羊肚菌多糖生物活性的作用机制,并对今后研究方向提出展望,以期为羊肚菌多糖的研究与开发提供理论基础。     

Enantioselective vinylation of aldehydes with the vinyl Grignard reagent catalyzed by magnesium complex of chiral BINOLs

Enantioselective vinylation of aldehydes via direct catalytic asymmetric Grignard reaction of aldehdyes and the vinyl Grinard reagent is a long‐standing challenge. This work demonstrated that the magnesium (S)‐3,3′‐dimethyl BINOLate enantioselectively catalyze the direct vinylation of aldehydes with the deactivated vinylmagnesium bromide by bis(2‐[N,N′‐dimethylamino]ethyl) ether (BDMAEE) in the addition of n‐butylmagnesium chloride. The highest ee of 63% was achieved up to date.     

花生壳乙醇提取物的脲酶抑制活性研究

以花生壳为研究对象,探索其防治胃炎、胃溃疡的可能性和作用机制。用乙醇进行提取,所得提取物总黄酮含量为29. 5%,其中木犀草素占总黄酮的84. 6%。脲酶活性研究表明,花生壳提取物具有较好抑制作用,IC50达到48. 1±2. 7μg/m L,表面等离子体共振(SPR)动力学亲和分析显示花生壳与脲酶具有较强的亲和力(KD为0. 11±0. 02μg/m L)。与木犀草素的折合活性相比,花生壳提取物具有更高的脲酶抑制活性,表明提取物中还存在其他具有脲酶抑制活性物质,并与木犀草素存在协同增效作用。主要活性成分木犀草素与脲酶活性点的Ni离子和周围的氨基酸残基存在强的配位键和氢键相互作用,占住脲酶活性点而导致脲酶失活。     

滇杨种群遗传多样性与遗传结构

滇杨(Populus yunnanensis)是我国西南地区的特有树种, 具有速生、易无性繁殖、适应性强等优良特性, 是典型的南方型杨属树种。研究滇杨遗传多样性及种群结构对其种质资源的收集、保存和利用具有重要的意义。本研究从我国滇杨主要分布区云南和四川共采集了6个种群, 包括云南的昭通(ZT)、会泽(HZ)、嵩明(SM)、洱源(EY)、拉市海(LS)以及四川的美姑(MG), 共64个个体, 利用34对SSR分子标记和3对cpDNA叶绿体标记开展遗传多样性与遗传结构研究。SSR引物共检测到154个等位基因, 平均等位基因数为4.529, 观测杂合度(Ho)与期望杂合度(He)分别为0.552和0.472, 遗传分化系数(Fst)平均值为0.238, 多态性信息含量指数(PIC)平均值为0.421, 基因流(Nm)为0.806。滇杨的遗传结构分析(DAPC)与遗传距离的主坐标分析(PCoA)、UPGMA聚类分析均将6个种群划分为3个亚类: 第І亚类包括昭通种群、会泽种群和嵩明种群的4个个体, 第ІІ亚类包括嵩明种群的6个个体以及洱源种群和拉市海种群, 第III亚类为美姑种群; 嵩明种群包含第І和第ІІ两个亚类的混合遗传成分。3个cpDNA联合序列中共检测到35个变异位点, 分为13个单倍型, 其中单倍型H5在种群中分布最为广泛, 其余的单倍型均为种群特有的单倍型。分子方差分析(AMOVA)表明种群内的遗传变异大于种群间变异。研究表明滇杨不同种群的遗传分化具有地域性, 可选择就地保护; 昭通种群遗传多样性最高, 且包含7种叶绿体单倍型, 单倍型类型最多, 应优先保护。     

A protocol for rapid generation of recombinant adenoviruses using the AdEasy system

Recombinant adenoviruses provide a versatile system for gene expression studies and therapeutic applications. We have developed an approach that simplifies the generation and production of such viruses called the AdEasy system. A recombinant adenoviral plasmid is generated with a minimum of enzymatic manipulations, employing homologous recombination in bacteria rather than in eukaryotic cells. After transfection of such plasmids into a mammalian packaging cell line, viral production is conveniently followed with the aid of GFP encoded by a gene incorporated into the viral backbone. This system has expedited the process of generating and testing recombinant adenoviruses for a variety of purposes. In this protocol, we describe the practical aspects of using the AdEasy system for generating recombinant adenoviruses. The full protocol usually takes 4-5 weeks to complete.     

Structure of the ubiquitin-binding zinc finger domain of human DNA Y-polymerase eta

The ubiquitin-binding zinc finger (UBZ) domain of human DNA Y-family polymerase (pol) eta is important in the recruitment of the polymerase to the stalled replication machinery in translesion synthesis. Here, we report the solution structure of the pol eta UBZ domain and its interaction with ubiquitin. We show that the UBZ domain adopts a classical C(2)H(2) zinc-finger structure characterized by a betabetaalpha fold. Nuclear magnetic resonance titration maps the binding interfaces between UBZ and ubiquitin to the alpha-helix of the UBZ domain and the canonical hydrophobic surface of ubiquitin defined by residues L8, I44 and V70. Although the UBZ domain binds ubiquitin through a single alpha-helix, in a manner similar to the inverted ubiquitin-interacting motif, its structure is distinct from previously characterized ubiquitin-binding domains. The pol eta UBZ domain represents a novel member of the C(2)H(2) zinc finger family that interacts with ubiquitin to regulate translesion synthesis.