植物耐低磷的转录调控机制

植物缺磷已经成为世界性的难题,越来越多的研究表明,转录调控是植物耐低磷调控的的重要环节,因此,有关植物低磷诱导转录因子转录机制的研究已成为国内外研究的热点。综述了与植物磷胁迫相关的转录因子PHR1,PHO1,WRKY6等调控磷酸饥饿的方式及其在植物生长发育、根系形态变化和激素信号等方面的功能,并对其研究前景进行了展望。     

Stem cell self-renewal controlled by chromatin remodeling factors

The self-renewing ability of a stem cell is controlled by its specialized micro-environment or niche, whereas epigenetic regulation of gene expression by chromatin remodeling factors underlies cell fate determination. Here we report that the adenosine triphosphate-dependent chromatin remodeling factors ISWI and DOM control germline stem cell and somatic stem cell self-renewal in the Drosophila ovary, respectively. The iswi mutant germline stem cells are lost rapidly because of defects in responding to bone morphogenetic protein niche signals and in repressing differentiation, whereas the dom mutant somatic stem cells are lost because of defective self-renewal. This work demonstrates that different stem cell types can use different chromatin remodeling factors to control cell self-renewal.     

超级杂交稻杂种优势基因组水平的转录因子分析

本研究利用超级杂交稻组合两优培九及亲本(93-11、培矮64S)和已完成基因组测序的籼稻93-11和粳稻日本晴所配的籼粳杂交稻及亲本为材料,采用包含36926个单一基因的的寡聚核苷酸基因芯片进行亲本和杂交组合基因表达差异分析.结果表明在两优培九杂交组合中发现3488个差异表达基因,在Nipponbare/93-11组合中只发现有2416个差异表达基因.差异表达基因表现为多基因修饰模式,主要有加性效应,高或低亲本的显性效应,超显性和低显性.两优培九杂交组合中表现为加性效应有2317个主要差异基因,而Nipponbare/93-11组合中只有1055个主要差异基因表现为加性效应.两个杂交组合的差异表达基因的保守功能包括多个生物化学代谢途径的有关基因.比较亲本同源性基因调控区域发现大量的序列变化,这些变化在差异表达基因中更为丰富.上述发现证明了杂种优势产生的存在较复杂的分子机理.     

高迁移率族核小体结合蛋白及其应用潜能

高迁移率族核小体结合蛋白(High-mobility group nucleosome-binding proteins,HMGN)几乎存在于所有哺乳动物和多数脊椎动物的细胞核中,属于HMG蛋白家族。HMGN是现在唯一已知的特异性结合在核小体上的非组蛋白,能够改变染色质的结构、增强染色质模板的转录/复制,参与DNA复制/表达、细胞分化、器官发育及基因表达调控等细胞的生命活动。目前,HMGN包括HMGN1、HMGN2、HMGN3、HMGN4和HMGN5。研究显示,HMGN1据其所在位置的不同,有着截然不同的功能。在细胞核内,HMGN1作为一种特殊定位的生物蛋白,与核小体直接结合而调节基因的转录和影响染色质的结构;在细胞外环境,HMGN1通过toll样受体4(Toll-like receptor 4,TLR4)促进抗原提呈细胞(Antigen-presenting cells,APCs)的活化和补充,从而促进特定抗原免疫应答。警报素(Alarmins)是一种内源性介质,当机体受到危险信号刺激时,它能快速的释放到细胞外,招募并激活APCs增强特异性免疫和非特异性免疫反应。认识HMGN及其作用对其在多方面的应用有重要意义。     

Histone H4-K16 acetylation controls chromatin structure and protein interactions

Acetylation of histone H4 on lysine 16 (H4-K16Ac) is a prevalent and reversible posttranslational chromatin modification in eukaryotes. To characterize the structural and functional role of this mark, we used a native chemical ligation strategy to generate histone H4 that was homogeneously acetylated at K16. The incorporation of this modified histone into nucleosomal arrays inhibits the formation of compact 30-nanometer-like fibers and impedes the ability of chromatin to form cross-fiber interactions. H4-K16Ac also inhibits the ability of the adenosine triphosphate-utilizing chromatin assembly and remodeling enzyme ACF to mobilize a mononucleosome, indicating that this single histone modification modulates both higher order chromatin structure and functional interactions between a nonhistone protein and the chromatin fiber.