The social and economic circumstances of mixed ethnicity children in the UK: findings from the Millennium Cohort Study

The number of people with a ‘mixed’ ethnicity heritage is growing in contemporary Britain. Research in this area has largely focused on implications for cultural and racialized identities, and little is known about associated economic and social factors. Data from the Millennium Cohort Study, a representative panel survey of children born in 2000–2001, are used to examine the circumstances of mixed ethnicity children in comparison with their non-mixed and white counterparts. Findings suggest a cultural location between ‘white’ and minority identities, and socio-economic advantage in comparison with non-mixed counterparts. For example, households of non-mixed white children had poorer economic profiles than households of both mixed white and mixed Indian children. This effect is associated with the presence of a white parent, and the factors underlying it are examined. Although the statistical approach used bypasses a consideration of the dynamics of identity, it provides important evidence on stratification and inequality, and the factors driving this.     

Membrane Damage Induced by Supercritical Carbon Dioxide in Rhodotorula mucilaginosa

To clarify the mechanism of microbial inactivation by supercritical carbon dioxide (SCCO₂), membrane damage of Rhodotorula mucilaginosa was investigated within specific pressure (10 Mpa), temperature (37 °C), and treatment time (10–70 min) ranges, including cell morphological structure, membrane permeability and fluidity. SEM and TEM observations showed morphological changes in the cell envelope and intracellular organization after SCCO₂ treatment. Increase of membrane permeability was measured as increased uptake of the trypan blue dye with microscopy, and leakage of intracellular substances such as UV-absorbing materials and ions by determining the change of protein and electrical conductivity. The SCCO₂ mediated reduction in CFU ml⁻¹ was 0.5–1 log higher at 37 °C and 10 MPa for 60 min in Rose Bengal Medium containing 4 % sodium than a similar treatment in Rose Bengal Medium. Membrane fluidity analyzed by fluorescence polarization method using 1,6-diphenyl-1,3,5-hexatriene showed that the florescence polarization and florescence anisotropy of the SCCO₂-treated cells were increased slightly and gently compared with the untreated cells. The correlation between membrane damage and death of cells under SCCO₂ was clear, and the membrane damage was a key factor induced the inactivation of cells.     

涡虫生殖生物学研究进展

涡虫由于具有极强的再生能力而成为发育生物学及再生生物学研究的模式生物。此外,其在有性生殖方面所表现出来的独特性也备受人们关注。目前,涡虫生殖生物学研究领域主要围绕两个热点问题开展工作：1.无性生殖向有性生殖转化的诱因及机制的探讨;2.生殖相关基因的克隆、表达及功能分析。有关生殖转化机制方面的研究主要集中在涡虫的性化相关事件以及性化物质的本质探索;截至目前已克隆并对其表达和功能进行探讨的涡虫生殖相关基因主要有DjPTK1、vasa-like 基因、DeY1、Dryg、nanos相关基因以及Drpiwi-1等。此外,本文也对有关涡虫生殖生物学方面存在的问题及未来该领域的发展趋势进行了总结和展望。     

细菌对消毒剂抗性机理研究进展

消毒剂通过抑制膜的主动运输、抑制微生物的代谢、扰乱微生物的DNA复制、使微生物细胞裂解而导致胞内成分渗漏以及使胞内物质凝结等方面发挥灭菌作用.消毒剂在杀灭细菌和控制细菌污染方面具有重要作用,但细菌对消毒剂也会产生抗性.细菌对消毒剂的抗性机制主要通过形成生物被膜,阻挡或外排机制减少消毒剂分子进入细胞,使消毒剂分子失活,以及其他表型性耐药等4个途径来实现,其中通过形成生物被膜阻止消毒剂分子进入细菌细胞或在进入细胞前使消毒剂失去效用,在细菌对消毒剂的抗性机制中具有重要作用.以实际污染的主要菌株为对象,研究它们对常用消毒剂的抗性机制,对控制细菌污染具有极大的应用价值和现实意义.     

Kinetic and pH studies on human phenylethanolamine N-methyltransferase

Phenylethanolamine N-methyltransferase (PNMT) catalyzes the conversion of norepinephrine (noradrenaline) to epinephrine (adrenaline) while, concomitantly, S-adenosyl-l-methionine (AdoMet) is converted to S-adenosyl-l-homocysteine. This reaction represents the terminal step in catecholamine biosynthesis and inhibitors of PNMT have been investigated, inter alia, as potential antihypertensive agents. At various times the kinetic mechanism of PNMT has been reported to operate by a random mechanism, an ordered mechanism in which norepinephrine binds first, and an ordered mechanism in which AdoMet binds first. Here we report the results of initial velocity studies on human PNMT in the absence and presence of product and dead end inhibitors. These, coupled with isothermal titration calorimetry and fluorescence binding experiments, clearly shown that hPNMT operates by an ordered sequential mechanism in which AdoMet binds first. Although the log V pH-profile was not well defined, plots of log V/K versus pH for AdoMet and phenylethanolamine, as well as the pK_i versus pH for the inhibitor, SK&F 29661, were all bell-shaped indicating that a protonated and an unprotonated group are required for catalysis.     

The potato tuber,maize endosperm and a chimeric maize-potato ADP-glucose pyrophosphorylase exhibit fundamental differences in Pi inhibition

ADP-glucose pyrophosphorylase (AGPase) is highly regulated by allosteric effectors acting both positively and negatively. Enzymes from various sources differ, however, in the mechanism of allosteric regulation. Here, we determined how the effector, inorganic phosphate (Pi), functions in the presence and absence of saturating amounts of the activator, 3-phosphoglyceric acid (3-PGA). This regulation was examined in the maize endosperm enzyme, the oxidized and reduced forms of the potato tuber enzyme as well as a small subunit chimeric AGPase (MP), which contains both maize endosperm and potato tuber sequences paired with a wild-type maize large subunit. These data, combined with our previous kinetic studies of these enzymes led to a model of Pi inhibition for the various enzymes. The Pi inhibition data suggest that while the maize enzyme contains a single effector site that binds both 3-PGA and Pi, the other enzymes exhibit more complex behavior and most likely have at least two separate interacting binding sites for Pi. The possible physiological implications of the differences in Pi inhibition distinguishing the maize endosperm and potato tuber AGPases are discussed.     

病毒穿越血脑屏障的两种方式与可能机制

血脑屏障是维持中枢神经系统内环境稳定的重要结构,限制血液中大多数病原体的入侵;但有些病毒可穿越血脑屏障入侵中枢神经系统,导致神经功能障碍及炎症性疾病。目前认为,病毒可通过细胞和细胞间隙两种方式穿越血脑屏障,前者为直接感染脑微血管内皮细胞和跨细胞途径,后者为破坏内皮细胞间紧密连接及"特洛伊木马"途径。本文就近年来病毒穿越血脑屏障的途径和机制进行综述。     

天蚕素A-马盖宁杂合肽对耐甲氧西林金黄色葡萄球菌抑菌机制的研究

【目的】研究天蚕素A-马盖宁杂合肽对耐甲氧西林金黄色葡萄球菌(MRSA)DNA作用的抑菌机制。【方法】利用激光扫描共聚焦显微镜(CLSM)、凝胶阻滞分析、紫外光谱分析、荧光光谱分析的方法。【结果】天蚕素A-马盖宁杂合肽对MRSA的最小抑菌浓度(MIC)为64 mg/L,杂合肽可以在细菌胞内形成累积,并能与体外基因组DNA发生结合作用。同时杂合肽可以引起DNA构象的改变,荧光光谱分析结果表明杂合肽能与溴化乙锭(EB)竞争性地嵌入基因组DNA中,作用方式类似于EB与DNA的结合方式,杂合肽与DNA的结合表现为混合式作用方式。【结论】天蚕素A-马盖宁进入细菌胞内,与MRSA基因组DNA结合,并以混合式作用方式与DNA发生了结合,通过胞内靶向机制发挥抑菌作用。