Complementary roles for histone deacetylases 1, 2, and 3 in differentiation of pluripotent stem cells

Abstract In eukaryotic cells, covalent modifications to core histones contribute to the establishment and maintenance of cellular phenotype via regulation of gene expression. Histone acetyltransferases (HATs) cooperate with histone deacetylases (HDACs) to establish and maintain specific patterns of histone acetylation. HDAC inhibitors can cause pluripotent stem cells to cease proliferating and enter terminal differentiation pathways in culture. To better define the roles of individual HDACs in stem cell differentiation, we have constructed "dominant-negative" stem cell lines expressing mutant, Flag-tagged HDACs with reduced enzymatic activity. Replacement of a single residue (His→Ala) in the catalytic center reduced the activity of HDACs 1 and 2 by 80%, and abolished HDAC3 activity; the mutant HDACs were expressed at similar levels and in the same multiprotein complexes as wild-type HDACs. Hexamethylene bisacetamide-induced MEL cell differentiation was potentiated by the individual mutant HDACs, but only to 2%, versus 60% for an HDAC inhibitor, sodium butyrate, suggesting that inhibition of multiple HDACs is required for full potentiation. Cultured E14.5 cortical stem cells differentiate to neurons, astrocytes, and oligodendrocytes upon withdrawal of basic fibroblast growth factor. Transduction of stem cells with mutant HDACs 1, 2, or 3 shifted cell fate choice toward oligodendrocytes. Mutant HDAC2 also increased differentiation to astrocytes, while mutant HDAC1 reduced differentiation to neurons by 50%. These results indicate that HDAC activity inhibits differentiation to oligodendrocytes, and that HDAC2 activity specifically inhibits differentiation to astrocytes, while HDAC1 activity is required for differentiation to neurons.     

一个水稻显性高秆突变体的遗传分析和基因定位

从水稻(Oryza sativa L.)的两个半矮秆籼稻品种6442S-7和蜀恢881杂交F2代群体中发现一个高秆突变体D111,其株高和秆长分别比亲本蜀恢881增加63.0%和87.0%。用205个微卫星标记分析D111及其原始亲本6442S-7和蜀恢881之间的基因组DNA多态性,结果未发现D111具有2个原始亲本都没有的新带型,证明D111的确是6442S-7和蜀恢881的杂交后代发生基因突变产生的。将D111分别与蜀恢881、蜀恢527、明恢63、9311、IR68、G46B等6个半矮秆品种和高秆对照品种南京6号杂交,分析F1和F2代株高的遗传行为,结果表明D111的高秆性状由一对显性基因控制,且该基因与南京6号的高秆基因紧密连锁或等位。以蜀恢527/D111 F2群体为定位群体,运用微卫星标记将D111显性高秆突变基因定位于水稻第一染色体长臂,与RM212、RM302和RM472的遗传距离分别是27.7 cM、25.5 cM和6.0 cM,该基因暂命名为LC(t)。认为D111是首例从半矮秆品种自然突变产生的水稻显性高秆突变体,LC(t)为首次定位的水稻显性高秆突变基因。此外,将上述基因定位结果与Causse等(1994)和Temnykh等(2000; 2001)发表的水稻分子连锁图谱进行比较,发现LC(t)基因恰巧位于与水稻“绿色革命基因”sd1相同或十分相近的染色体区域,因此,还就LC(t)基因与sd1基因之间的可能关系进行了讨论。     

一组优势菌对焦化废水中吲哚、吡啶的降解条件的实验研究

从普通变形杆菌BH、芽孢杆菌DC4 5、巨大芽孢杆菌F3、枯草芽孢杆菌DC4 2等 4种脱色菌中 ,经驯化、筛选出普通变形杆菌BH、芽孢杆菌DC4 5两株降解苯酚、吲哚、吡啶、喹啉的优势菌。其中普通变形杆菌BH降解吡啶的适宜条件是 :温度 30～ 4 5℃ ,pH 7～ 8,投加适量Pb2 + ;芽孢杆菌DC4 5降解吲哚的适宜条件是 :温度 2 0～ 5 0℃ ,pH 6～ 8,投加适量Zn2 + ,Fe2 + 。     

喀斯特山地煤矿废弃地几种优势植物的重金属耐性特征

对贵阳花溪区麦坪乡煤矿废弃地进行了野外调查, 对该地优势植物和土壤进行了采样, 测定样品As、Cd、Cu、Hg、Pb和Zn的含量, 发现当地优势植物雀稗(Paspalum thunbergii Kunth ex Steud.)地上部分Cu含量达到1058.12 mg•kg-1, 转移系数2.89, 富集系数16.07。研究了雀稗在铜离子胁迫实验中的根系活力变化和叶绿素浓度变化, 雀稗根系活力随实验进行而逐渐降低, 铜离子浓度为500 µg•mL-1的实验进行到第四周时TTC还原量达到最低值; 叶绿素浓度随着铜离子浓度的增加而缓慢降低, 进一步确认当地土著植物雀稗对铜离子有一定的耐受性。     

毛乌素沙地3种优势植物对模拟降水量变化的水分平衡研究(英文)

未来全球变化 ,尤其降水变化的进一步加剧 ,将对毛乌素沙地陆地生态系统分布格局和生产力带来巨大影响。为了预测未来变化 ,提出合理的对应策略 ,实验选择毛乌素沙地 3种优势灌木、半灌木为研究对象 ,人工控制 4种降水量水平来探讨水分平衡对全球降水量变化的响应。结果表明 ,沙地蓄水量和不同沙层深度含水量季节变化明显受到不同施水量和 3种植物种类的影响。 3种植物沙地蓄水量和不同深度沙层含水量随着施水量的增加逐渐增大 ,并且不同施水量和植物沙地含水量随深度增加逐渐增大。在同一施水量处理下的蓄水量和同一深度含水量均大体为杨柴 (HedysarummongolicumTurcz.) >沙柳 (SalixpsammophilaC .WangetCh .Y .Yang) >油蒿 (Artemisiaordosi caKrasch .) ;3种植物的蒸发量和蒸腾量季节变化明显受到施水量的影响。随着施水量的增加 ,即 15 7 5、315 0、472 5和 6 30 0mm ,蒸发总量依次为 12 3.6 6、2 5 8.6 8、376 .30、45 8.5 7mm ;蒸腾总量 ,油蒿分别为 5 0 .80、6 8.93、10 8.39、16 3.36mm ;沙柳分别为 47.37、6 8.17、93.6 5、135 .97mm ;杨柴分别为 46 .73、6 7.37,86 .0 7、10 9.6 4mm。蒸发量显著大于蒸腾量     

居群遗传结构研究中显性标记数据方法初探

为对比显性标记应用于居群遗传结构研究时不同统计参数的适用性,利用RAPD技术对中国5个居群的100个疣粒野生稻个体进行了遗传结构分析。在衡量居群遗传多样性水平时,多态位点比率（PPB）会低估遗传变异的量,其价值不如Shannon多样性指数和Nei基因多样性指数,而采用Nei指数时不必进行Lynch-Milligan矫正。对个体间遗传关系进行分析时,17种遗传相似性指数矩阵两两之间的Mantel检测都表现出极显著的相关性（r＞0.95,t＞t     

Lethal bithorax complex mutations of Drosophila melanogaster show no germ line maternal effects

Three Ultrabithorax (Ubx) alleles and three different deficiencies of the bithorax complex (BX-C) of Drosophila melanogaster have been tested for maternal effects in the germ line. The dominant female sterile technique was used. The Ubx alleles and a deletion of the abdominal region of the BX-C are homozygous viable in germ line clones and show no maternal effects. Two deletions which lack the proximal portion of the BX-C are lethal in the female germ line indicating either that these deficiencies lack genes apart from the BX-C that are necessary for fertility or that there are BX-C genes that are essential for normal maternal germ line function. The significance of the bias in the isolation of only zygotic mutations at the BX-C are discussed with respect to these results.