The Regulation and Function of Histone Methylation

Histones are wrapped around by genomic DNA to form nucleosomes which are the basic units of chromatin. In eukaryotes histones undergo various covalent modifications such as methylation, phosphorylation, acetylation, ubiquitination and ribosylation. Histone modifications play a fundamental role in the epigenetic regulation of gene expression in multicellular eukaryotes. Histone methylation is one of the most important modifications occurring on Lysine (K) and Arginine (R) residues of histones, dynamically regulated by histone methyltransferases and demethylases. Identifications of such histone modification enzymes and to study how they work are the most fundamental questions needs to be answered. Uncovering the regulation and functions of the various histone methylation enzymes will help us to better understand the epigenetic code. This review summarizes the regulation of histone methyltransferases activity, the recruitment of methyltransferases and the distribution patterns and function of histone methylations.     

CO2倍增对不同基因型大豆光合色素含量和荧光诱导动力学参数的影响

研究了CO_2倍增对大豆(Glycine max L.)Bragg(野生型)及其不同单基因突变品系Nts 382(超结瘤突变体)和Nod 49(不结瘤突变体)某些光合特性的影响。结果表明,CO_2倍增能提高Bragg、Nts 382和Nod 49的叶绿素(Chl)和类胡萝卜素(Car)的含量,但不同品系提高的幅度有所不同。荧光诱导动力学测定结果表明,CO_2倍增均能提高其PSⅡ活性、PSⅡ原初光能转化效率和光合作用潜在量子转化效率。CO_2倍增更有利于提高Nts 382的荧光光化学猝灭系数(qp)和PSⅡ总的光化学量子产量,以及较大幅度地降低荧光非光化学猝灭系数(qN),有助于把所捕获的光能用于进行光合作用。这可能与Nts 382是超结瘤突变体,比Bragg和Nod 49能更充分地利用空气中的氮素有关。     

Efficient mucosal vaccination mediated by the neonatal Fc receptor

Almost all infectious diseases are initiated at mucosal surfaces, yet intramuscular or subcutaneous vaccination usually provides only minimal protection at sites of infection owing to suboptimal activation of the mucosal immune system. The neonatal Fc receptor (FcRn) mediates the transport of IgG across polarized epithelial cells lining mucosal surfaces. We mimicked this process by fusing a model antigen, herpes simplex virus type-2 (HSV-2) glycoprotein gD, to an IgG Fc fragment. Intranasal immunization, together with the adjuvant CpG, completely protected wild-type, but not FcRn knockout, mice after intravaginal challenge with virulent HSV-2 186. This immunization strategy induced efficient mucosal and systemic antibody, B- and T-cell immune responses, with stable protection for at least 6 months after vaccination in most of the immunized animals. The FcRn-IgG transcellular transport pathway may provide a general delivery route for subunit vaccines against many mucosal pathogens.     

离子对高效液相色谱法分析黄瓜花叶病毒侵染烟草的总RNA水平变化

为研究植物病毒在RNA水平上对寄主植物的基因表达产生的影响,采用离子对高效液相色谱法,对黄瓜花叶病毒侵染烟草造成的总RNA的组成成分变化进行研究。离子对液相色谱法,是近几年才应用于对RNA进行分离、纯化和分析的一种试验技术,具有操作简单、重复性好、所需时间短等优点。选择适宜的离子对试剂,并对选定的离子对试剂正己胺/1,1,1,3,3,3-六氟-2-丙醇进行了优化,达到了较好的总RNA分离效果,并观察到健康植株和染病植株分离峰之间的差异,有差异的RNA种类还需进一步试验来验证。为研究植物病毒的致病机制提供一种新的试验方法和途径。     

TLR4 signaling-induced heme oxygenase upregulation in the acute lung injury: role in hemorrhagic shock and two-hit induced lung inflammation

Resuscitated hemorrhagic shock is believed to promote the development of acute lung injury (ALI) by priming the immune system for an exaggerated inflammatory response to a second trivial stimulus. This work explored effects of TLR4 on hemorrhage-induced ALI and “second-hit” responses, and further explore the mechanisms involved in “second-hit” responses. Expression of HO-1, IL-10, lung W/D and MPO markedly increased at nearly all time-points examined in HSR/LPS group as compared with sham/LPS group in WT mice. In HSR/LPS mice, the induced amount of IL-10 and the expressions of HO-1 of WT mice were significantly higher compared with TLR-4d/d. This study provides in vivo evidence that pulmonary infections after LPS instillation contribute to local tissue release of pro-inflammatory mediators after HSR systemic. Activation of TLR4 might induce HO-1 expression and HO-1 modulates proinflammatory responses that are triggered via TLR4 signaling.     

人胃粘膜G、D细胞与肠化生关系的研究

用免疫细胞化学和原位杂交技术探讨G、D细胞及胃泌素mRNA与肠化生的关系。标本来自胃镜活检的胃粘膜。结果显示,在与大肠化生区相邻的胃粘膜,G细胞突变消失,假幽门腺化生也缺乏G细胞,而淖肠化生仍保留少数G细胞;D细胞不仅见于小肠化生,而且也出现在假幽门腺化生以及某些大肠化生区。胃泌素mRNA仅限于G细胞分布区,未出现在大肠化生区和假幽门腺化生区,G细胞及胃泌素mRNA在大肠化生区的消失,可能由于局部杯状细胞分泌的硫酸粘蛋白改变了局部的微环境,从而影响了G细胞的分化与发育,至于假幽门腺化生区G细胞及胃泌素mRNA消失的原因还不清楚,应继续研究。     

植物谷氨酸受体的研究进展

离子型谷氨酸受体(iGLuR)是哺乳动物中一类由L-氨基酸(如谷氨酸、甘氨酸)等配体门控的阳离子通道, 具有调节兴奋性神经信号传递和引导神经元发育等分子功能。1998年研究者在拟南芥(Arabidopsis thaliana)中发现了20个与iGLuRs同源的序列(即AtGLRs), 它们的功能涉及植物光信号传递、根尖分生细胞活性、花粉管生长、胞质Ca²⁺流以及应答多种生物和非生物环境胁迫等。该文从谷氨酸受体(GLR)的结构特征、离子通道激活与配体的关系、表达模式及可能的生物学功能等方面, 综述了近十几年来关于植物GLR和氨基酸信号的研究成果, 旨在为相关领域的同行提供有益的参考。