CpG island hypermethylation is maintained in human colorectal cancer cells after RNAi-mediated depletion of DNMT1

The role of the primary mammalian DNA methyltransferase, DNMT1, in maintaining CpG island methylation in human colon cancer cells has recently been questioned. This controversy has arisen from discrepancies between genetic knockout and RNA interference-mediated knockdown studies. Here, we re-examined the RNA interference-based approach and found that hypermethylation of single-copy genes is maintained in cells transiently and stably depleted of DNMT1.     

双(2-羟基苯甲醛)缩硫脲及其Cu(Ⅱ),Ni(Ⅱ)配合物的合成与抑制超氧自由基的研究

采用两步法合成了双(2-羟基苯甲醛)缩硫脲配体及其与Cu(Ⅱ),Ni(Ⅱ)离子所形成的配合物,摩尔电导及恒重实验等研究了化合物的组成和配位环境;对所合成的化合物进行了抑制超氧自由基实验和消灭钉螺的初步试验。     

4-羟基水杨醛丙氨酸合锌(Ⅱ)的合成表征及其抗癌活性的初步研究

本文报道了4-羟基水杨醛丙氨酸合锌(Ⅱ)的合成和表征,它的化学组成已由元素分析,摩尔电导,红外光谱,氢核磁共振谱等测定所证实。体外抗癌活性试验表明,该配合物对宫颈癌、艾氏腹水癌和喉癌细胞均有一定的抑制作用。     

苹果和白梨的属间杂交研究

用杂交种胚离体培养的方法可获得大量的苹果和白梨的属间杂交幼苗。对其进行根尖染色体检查和叶、茎的过氧化物酶同工酶带分析。证实杂交种胚苗是二倍体（２ｎ＝３４），并具有其双亲的基本酶带。     

An integrated view of the chemistry and mineralogy of martian soils

The mineralogical and elemental compositions of the martian soil are indicators of chemical and physical weathering processes. Using data from the Mars Exploration Rovers, we show that bright dust deposits on opposite sides of the planet are part of a global unit and not dominated by the composition of local rocks. Dark soil deposits at both sites have similar basaltic mineralogies, and could reflect either a global component or the general similarity in the compositions of the rocks from which they were derived. Increased levels of bromine are consistent with mobilization of soluble salts by thin films of liquid water, but the presence of olivine in analysed soil samples indicates that the extent of aqueous alteration of soils has been limited. Nickel abundances are enhanced at the immediate surface and indicate that the upper few millimetres of soil could contain up to one per cent meteoritic material.     

Water alteration of rocks and soils on Mars at the Spirit rover site in Gusev crater

Gusev crater was selected as the landing site for the Spirit rover because of the possibility that it once held a lake. Thus one of the rover's tasks was to search for evidence of lake sediments. However, the plains at the landing site were found to be covered by a regolith composed of olivine-rich basaltic rock and windblown 'global' dust. The analyses of three rock interiors exposed by the rock abrasion tool showed that they are similar to one another, consistent with having originated from a common lava flow. Here we report the investigation of soils, rock coatings and rock interiors by the Spirit rover from sol (martian day) 1 to sol 156, from its landing site to the base of the Columbia hills. The physical and chemical characteristics of the materials analysed provide evidence for limited but unequivocal interaction between water and the volcanic rocks of the Gusev plains. This evidence includes the softness of rock interiors that contain anomalously high concentrations of sulphur, chlorine and bromine relative to terrestrial basalts and martian meteorites; sulphur, chlorine and ferric iron enrichments in multilayer coatings on the light-toned rock Mazatzal; high bromine concentration in filled vugs and veins within the plains basalts; positive correlations between magnesium, sulphur and other salt components in trench soils; and decoupling of sulphur, chlorine and bromine concentrations in trench soils compared to Gusev surface soils, indicating chemical mobility and separation.     

Dissociation of obesity,hypercholesterolemia and diabetes from atherosclerosis in ob/ob mice

Summary Genetically obese, diabetic and hypercholesterolemic C57BL/6J-ob/ob mice were placed on Purina Laboratory Chow containing 2% cholesterol for up to 4 months. They developed higher plasma cholesterol levels and accumulated an increased quantity of cholesterol in the liver but failed to develop atherosclerotic lesions in the aorta as would be expected in an obese, diabetic and hypercholesterolemic human adult.Acknowledgments. We wish to thank Mr. Willis M. Overton for his excellent technical assistance.     

苯酚丙酮缩合反应的小型中试研究

讨论了传统固定床反应器用于苯酚丙酮缩合反应生产双酚Ａ的不足之处，开发了一种被称做“多段悬浮床具分离作用塔式反应器”的新型装置，提出了应用新装置进行苯酚丙体现 合反应的新工艺流程。中试数据表明新装置及工艺较传统的固定床方法有明显技术优势。