水蛭素基因在酵母细胞中的分泌表达

报道了合成的水蛭素基因表达载体的构建 ,表达载体在酵母细胞中的表达 ,以及重组水蛭素的胞外分泌情况     

转座子沉默与DNA甲基化

转座子(transposable elements,TEs)在生物体基因组可以通过转座或逆转座移动,它拷贝数的大规模增加是基因组不稳定的重要因素,因此,维持TEs沉默是宿主进化的方向。DNA甲基化被认为是沉默TEs的可遗传表观遗传修饰方式,同时也在维持基因组稳定、基因印迹、调节基因表达中发挥作用。本研究综述了TEs对生物基因组进化和基因表达的影响,重点总结了以DNA甲基化为主的转座子沉默机制的最新研究进展,归纳了环境因素通过DNA去甲基化调控转座子跳跃的机理。图4参82     

Dynamics of replication-independent histone turnover in budding yeast

Chromatin plays roles in processes governed by different time scales. To assay the dynamic behavior of chromatin in living cells, we used genomic tiling arrays to measure histone H3 turnover in G1-arrested Saccharomyces cerevisiae at single-nucleosome resolution over 4% of the genome, and at lower (approximately 265 base pair) resolution over the entire genome. We find that nucleosomes at promoters are replaced more rapidly than at coding regions and that replacement rates over coding regions correlate with polymerase density. In addition, rapid histone turnover is found at known chromatin boundary elements. These results suggest that rapid histone turnover serves to functionally separate chromatin domains and prevent spread of histone states.     

酿酒酵母ADH2基因沉默表达载体的构建

利用重叠延伸PCR获得酿酒酵母基因沉默组件SADH2,经酶切与酿酒酵母穿梭质粒pYES2.0连接,构建酿酒酵母ADH2基因沉默表达载体。经酶切及测序鉴定成功构建了ADH2基因沉默表达载体pSADH2。     

用植物提取物筛选与酵母甾醇乙酰化循环相关的物质

为了确定酿酒酵母中乙酰/脱乙酰循环是否参与细胞对某些甾体化合物或其类似物的毒性解除过程,将野生型(BY4742)、脱乙酰酶SAY1单突变体(say1Δ)、乙酰基转移酶ATF2 单突变体(atf2Δ)和SAY、ATF2 双突变体(atf2Δsay1Δ)酵母菌分别培养在含21种不同植物提取物的培养基中,比较其生长状况.结果显示,在含80 mg/mL黄芪提取物的培养基中,细胞生长必须依赖一个完整的乙酰化/脱乙酰循环的作用;而在含20 mg/mL生姜提取物的培养基中,其生长则必须依赖ATF2(乙酰化作用)的缺失.可以推测甾醇乙酰化/脱乙酰循环途径很可能间接参与了某些甾族化合物或其类似物的解毒过程.     

The structure of sister minichromosome DNA before anaphase in Saccharomyces cerevisiae

The role of DNA topology in holding sister chromatids together before anaphase was investigated by analyzing the structure of a small circular minichromosome in cell cycle (cdc) mutants of the yeast Saccharomyces cerevisiae. In the majority of cells arrested after S phase but before anaphase, sister minichromosome molecules are not topologically interlocked with each other. The analysis of the ploidy of minichromosomes in cells that are released from arrest demonstrates that the sister molecules are properly segregated when the cell cycle block is removed. Therefore, sister minichromosome molecules need not remain topologically interlocked until anaphase in order to be properly segregated, and topological interlocking of sister DNA molecules apparently is not the primary force holding sister chromatids together.     

Molecular biology. Unwinding RNA silencing

Eukaryotic cells have developed an elegant system called RNA silencing for getting rid of foreign RNAs whether they be of viral, retrotransposon, or transgene origin. In his Perspective, Baulcombe examines new findings (Wu-Scharf et al.) showing that in a green alga the gene responsible for RNA silencing encodes an RNA helicase (related to proteins in worms and other organisms) that is required for regulation of gene expression at the RNA level.     

DNA分子标记技术在酿酒酵母菌株遗传多样性分析中的应用

本文介绍了RAPD、mtDNA-RFLP、微卫星DNA（microsatellite）、Interdelta指纹图谱以及线粒体DNA COX1基因指纹图谱等5种DNA分子标记技术的方法和原理及其优缺点,同时探讨了DNA分子标记技术在国内外酿酒酵母菌株区分中的应用状况与前景。     

Selective silencing of foreign DNA with low GC content by the H-NS protein in Salmonella

Horizontal gene transfer plays a major role in microbial evolution. However, newly acquired sequences can decrease fitness unless integrated into preexisting regulatory networks. We found that the histone-like nucleoid structuring protein (H-NS) selectively silences horizontally acquired genes by targeting sequences with GC content lower than the resident genome. Mutations in hns are lethal in Salmonella unless accompanied by compensatory mutations in other regulatory loci. Thus, H-NS provides a previously unrecognized mechanism of bacterial defense against foreign DNA, enabling the acquisition of DNA from exogenous sources while avoiding detrimental consequences from unregulated expression of newly acquired genes. Characteristic GC/AT ratios of bacterial genomes may facilitate discrimination between a cell's own DNA and foreign DNA.     

酿酒酵母多糖对葡萄酒果香酯类物质水解呈香的表观基质效应

【目的】研究酿酒酵母多糖对葡萄酒果香酯类物质水解呈香的表观基质效应,探究酿酒酵母多糖在稳定产品果香、延长货架期方面的应用潜力。【方法】以酿酒酵母为材料,利用热水浸提法、碱法提取得到酵母多糖,并通过紫外分光光度计、气相色谱以及高效液相色谱解析酿酒酵母多糖的基本组分。配置含有果香酯类物质常规浓度的模拟葡萄酒溶液,并作酵母多糖处理,多糖浓度在0—2.0 g·L^-1范围作梯度设置。酵母多糖对果香酯类物质挥发性的影响采用静态顶空方法分析,随后不同处理模拟酒在4℃下贮藏6个月,定期取样监测果香酯类物质的含量变化。最后通过感官分析评价6个月后不同处理模拟酒的香气特征。【结果】通过仪器分析得到酿酒酵母多糖总多糖含量占比为(72.61±3.29)%,蛋白质含量占比为(11.20±0.02)%,其主要单糖组成为甘露糖和葡萄糖,二者的摩尔比1.790∶1;该多糖的高分子量组分为18、163和21 819 kD,低分子量组分为576 Da。静态顶空分析方法表明,多糖处理可以降低模拟酒中乙酸酯的挥发性,以0.8 g·L^-1的多糖处理效果最好;而多糖处理可以提高模拟酒中...