DNA甲基化的影响因素及对基因表达的调控

DNA甲基化是一种由DNA甲基转移酶介导的主要表观遗传修饰方式,是调节基因组功能的重要途径。本文重点综述了影响DNA甲基化的主要因素以及DNA甲基化与基因表达调控的关系。     

甲醛、组蛋白（脱）甲基化与学习记忆

组蛋白的甲基化与脱甲基是调控DNA特定基因“开”与“关”的主要分子机制之一,与哺乳动物表观遗传密切相关。研究表明,组蛋白的可逆共价修饰,也是记忆与遗忘的分子调控机制。甲醛作为甲基化供体,参与了组蛋白修饰的关键环节。因此,甲醛代谢失调,可能影响组蛋白甲基化与脱甲基,也影响DNA甲基化与脱甲基,这可能是老年认知损伤的因素之一。     

DNA甲基化异常与肿瘤发生的研究

DNA甲基化是真核生物DNA的正常内源性修饰方式 ,它由DNA甲基化转移酶催化发生。但DNA甲基化异常在肿瘤发生中却起着极为重要的作用 ,它主要表现为抑癌基因高甲基化所致的基因失活和原癌基因低甲基化所致的基因激活 ,引起与细胞增殖、分化相关基因表达异常 ,造成细胞恶变形成肿瘤。文章总结了DNA甲基化异常对肿瘤相关基因表达的影响 ,在肿瘤发生中的可能机制及针对高甲基化的治疗方案     

实验小鼠烧伤后对皮肤解毒酶表达水平的影响

本文旨在通过检测烧伤诱导的大鼠体内烟酰胺降解的改变,探索皮肤本身可能在胰岛素抵抗中起到的重要作用。此实验通过检测与解毒相关的酶的m RNA的表达(包括烟酰胺N-甲基转移酶、醛氧化酶、儿茶酚-O-甲基转移酶、单胺氧化酶A、超氧化物歧化酶2、谷胱甘肽过氧化物酶1、过氧化氢酶和过氧化还原酶1)。进而研究假烧伤大鼠与烧伤大鼠体内的烟酰胺和N1-甲基烟酰胺的清除能力是否有所差异。结果表明,在烧伤大鼠的皮肤中酶均未表达,但假烧伤大鼠均有表达。假烧伤大鼠的烟酰胺的代谢能力大于烧伤大鼠的代谢能力且全层烧伤的大鼠皮肤中检测不到异型生药物代谢酶的表达。烧伤能降低机体对过多烟酰胺的清除能力。     

5-羟甲基胞嘧啶生物学功能研究进展

最近的研究发现,DNA胞嘧啶5号位上能发生羟甲基化修饰形成5-羟甲基胞嘧啶,这种修饰对于基因的表达和调控有着重要的影响,本文对这方面的研究进展作一介绍.     

DNA 甲基化及其生物学功能

DNA甲基化是表观遗传修饰的重要组成成分,是一种重要的基因表达调控机制。本文在介绍DNA甲基化的形成及其修饰方式的基础上论述了DNA甲基化的生物学功能。     

DNA甲基化及其植物生物学意义研究进展

DNA的甲基化修饰在基因表达、植物细胞分化和植物的系统发育中起着重要的调节作用,从DNA甲基化机理、调节机制及其在植物生长发育中的意义3个方面阐述了DNA甲基化的研究进展．     

DNA甲基化异常与肿瘤间关系的研究进展

DNA的甲基化及甲基化异常在人体发育和肿瘤的发生中起着至关重要的作用。文中主要综述了几十年来人们对 DNA甲基化异常与基因转录及肿瘤发生之间关系的研究进展 ,尤其是最近的研究突破。     

植物DNA甲基化研究进展

植物DNA甲基化是导致转基因沉默的直接和主要因素。甲基化的出现严重制约了植物基因工程的商业化生产。本将对植物DNA甲基化的机制、作用等问题作一综述。     

表观遗传学中的DNA可逆化学修饰

DNA是遗传信息的载体,也是生物个体以及物种的整个生命周期的蓝图。DNA在这整个生命周期中保持高度稳定。DNA的可逆化学修饰在哺乳动物的细胞分化、个体发育等过程中起到重要作用。本文主要关注针对DNA中胞嘧啶的甲基化与去甲基化动态变化及功能的相关前沿研究进展。     

DNA methylation polymorphism in flue-cured tobacco and candidate markers for tobacco mosaic virus resistance

DNA methylation plays an important role in the epigenetic regulation of gene expression during plant growth, development, and polyploidization. However, there is still no distinct evidence in tobacco regarding the distribution of the methylation pattern and whether it contributes to qualitative characteristics. We studied the levels and patterns of methylation polymorphism at CCGG sites in 48 accessions of allotetraploid flue-cured tobacco, Nicotiana tabacum, using a methylation-sensitive amplified polymorphism (MSAP) technique. The results showed that methylation existed at a high level among tobacco accessions, among which 49.3% sites were methylated and 69.9% allelic sites were polymorphic. A cluster analysis revealed distinct patterns of geography-specific groups. In addition, three polymorphic sites significantly related to tobacco mosaic virus (TMV) resistance were explored. This suggests that tobacco breeders should pay more attention to epigenetic traits.     

一种基于氨基葡萄糖的新型手性β-氨基醇的合成

手性氨基醇作为催化剂广泛应用于多种不对称合成反应中.以氨基葡萄糖为原料设计合成一种新型手性β-氨基醇.氨基葡萄糖盐酸盐首先与氯甲酸甲酯缩合,再先后经过甲基化、苄叉保护、碱性水解反应,得4,6-O-苄叉基-2-脱氧-2-氨基-α-D-吡喃葡萄糖甲苷.4步反应总收率35%,对目标化合物及反应中间体的结构均进行1H NMR表征.     

Epigenetic Vestiges of Early Developmental Adversity: Childhood Stress Exposure and DNA Methylation in Adolescence

Fifteen‐year‐old adolescents (N = 109) in a longitudinal study of child development were recruited to examine differences in DNA methylation in relation to parent reports of adversity during the adolescents’ infancy and preschool periods. Microarray technology applied to 28,000 cytosine–guanine dinucleotide sites within DNA derived from buccal epithelial cells showed differential methylation among adolescents whose parents reported high levels of stress during their children’s early lives. Maternal stressors in infancy and paternal stressors in the preschool years were most strongly predictive of differential methylation, and the patterning of such epigenetic marks varied by children’s gender. To the authors’ knowledge, this is the first report of prospective associations between adversities in early childhood and the epigenetic conformation of adolescents’ genomic DNA.     

碘化三甲基对乙酰苯基铵的合成

在乙酸乙酯溶剂中,以碘甲烷和对二甲氨基苯乙酮反应合成了碘化三甲基对乙酰苯基铵,通过红外光谱和核磁共振氢谱表征了其分子结构.结果表明,在碘甲烷过量50%条件下,反应时间4h,生成的产物可自行从溶液中沉淀出来,产率达85%以上。     

动脉粥样硬化性心脑血管疾病患者血浆脂蛋白(a)水平与纤溶活性的关系

目的 :为了研究动脉粥样硬化性心脑血管疾病患者血浆脂蛋白 (a)水平与纤溶活性的关系 ,探讨脂蛋白 (a)促血栓形成和致动脉粥样硬化的机理。方法 :分别测定 4 2例心肌梗塞患者、4 2例心绞痛患者、4 4例脑梗塞患者及 38名健康对照者的脂蛋白 (a)浓度、组织型纤溶酶原激活剂 (tPA[lj1])及其抑制物 (PAI)活性 ,并分析其相关性。结果 :各组动脉粥样硬化性心脑血管疾病患者血浆脂蛋白 (a)浓度和PAI活性明显升高 ,tPA活性明显降低 ;各组脂蛋白 (a)与PAI活性均呈显著正相关。结论 :血浆高脂蛋白 (a)浓度是动脉粥样硬化性心脑血管疾病的主要危险因素之一 ,脂蛋白 (a)水平的升高与纤溶活性低下有关     

Global changes of 5-hydroxymethylcytosine and 5-methylcytosine from normal to tumor tissues are associated with carcinogenesis and prognosis in colorectal cancer

Aberrant DNA methylation has raised widespread attention in tumorigenesis. In this study, we aimed to investigate the changes of global DNA methylation and hydroxymethylation from normal to tumor tissues in colorectal cancer (CRC) and their association with the prognosis. The levels of genomic 5-hydroxymethylcytosine (5hmC) and 5-methylcytosine (5mC) in cancerous tissues were significantly lower than those in corresponding adjacent normal tissues. The genomic levels of 5mC were significantly positively correlated with 5hmC in normal and cancerous tissues (all P<0.05). The ratio of 5mC in cancerous tissues to matched normal tissues (C/N-5mC) was also significantly positively correlated with the ratio of 5hmC in cancerous tissues to matched normal tissues (C/N-5hmC) (P=0.01). The 5mC levels and C/N-5mC ratios decreased with age (all P<0.05). Higher 5mC and 5hmC levels were found in rectal than in colon tissues (all P<0.05). High levels of 5mC in cancerous tissues and high C/N-5hmC ratios were each associated with lymph node metastasis (all P<0.05). Survival analysis indicated that the C/N-5mC ratio (P=0.04) is an independent protective factor for overall survival. The data showed that patients with a combination of high C/N-5hmC and low C/N-5mC ratios tended to have a worse prognosis (P<0.01). Our findings showed that the C/N-5mC ratio may be an independent prognostic factor for CRC outcome. Patients with both a high C/N-5hmC ratio and a low C/N-5mC ratio exhibited the worst survival, suggesting that 5mC and 5hmC can be used as critical markers in tumorigenesis and prognosis estimation.     

Comparison of the effects of acute and chronic psychological stress on metabolic features in rats

This study was aimed to compare the effects of acute and chronic psychological stress on metabolic factors. Forty-two male Wistar rats were divided into control and stressed groups. Stress was applied by a communication box acutely (1 d) and chronically (15 and 30 d). Blood sampling was carried out by retro-orbital-puncture method. The plasma levels of glucose, cholesterol, triglyceride, insulin, and corticosterone were measured. In addition, feed and water intake, latency to eat and drink, adrenal and body weights were determined. Acute and chronic psychological stress did not significantly change basal plasma corticosterone levels. However, immediately (1 min) after acute exposure to stress, plasma corticosterone level increased compared to that before stress exposure. Acute stress increased plasma insulin levels significantly. Fifteen days of stress exposure resulted in plasma glucose increase. Chronic stress significantly increased feed intake, latency to eat, and adrenal weight compared to acute stress. The body weights of both control and stressed groups increased markedly during the experiment. Homeostasis model assessment of insulin resistance (HOMA-IR) index did not change significantly in the stressed group. In conclusion, application of acute and chronic psychological stress leads to different metabolic and/or behavioral changes but the metabolic changes resulting from acute exposure to stress seem to be more pronounced.     

天麻钩藤饮对高血压病肝阳上亢证患者超氧化物歧化酶的影响

目的：观察天麻钩藤饮对高血压病（肝阳上亢型）患者血浆超氧化物歧化酶（SOD）的影响。方法：采用随机对照方法，观察天麻钩藤饮组（30例）和对照组（30例）治疗前后血压水平及血浆超氧化物歧化酶的变化。结果：两组治疗后血压明显降低，超氧化物歧化酶明显增高（P〈0．01，P〈0．05），组间比较无显著差异（P〉0．05）。结论：天麻钩藤饮能显著升高高血压病患者血浆超氧化物歧化酶的水平。     

原发性痛经患者外周血细胞因子和PGF2α相关性研究

目的：通过原发性痛经病人外周血细胞因子和PGF2α改变,探讨其发病机制。方法：临床随机病例对照研究。选取原发性痛经患者64例,平均年龄22．3±7．1岁,正常对照组健康女性60例,平均年龄21．5±5．4岁,用酶联免疫吸附实验（EUSA）法测定经期外周血PGF2α浓度和白细胞介素-4（IL-4）,IL-10,和INF-γ水平。结果：二组经前和经中PGF2α水平均显著增高（正常对照组经前45．46±11．48pg／ml,痛经组经前51．31±15．88pg／ml）,但原发性痛经组病人经期PGF2α（182．66±68．67pg／ml）显著高于正常对照组（117．59±38．55pg／ml）（P〈0．01）;痛经组IL10经中显著低于正常对照组（8．53±1．33与13．14±1．41pg／ml）（P〈0．01）;病经组IFN-γ IL10经中显著增高（16．49±4．63与9．12±1．55pg／ml）（P〈0．01）。结论：原发性痛经发病机制与免疫功能、PGF。分泌量有关。