Effect of pulsing electromagnetic fields on DNA synthesis in mammalian cells in culture

Summary DNA synthesis in Chinese hamster V79 cells was significantly enhanced when they were exposed to weak, pulsing electromagnetic fields generated by specific combinations of the pulse width (25s), frequency (10, 100 Hz) and magnetic intensity (2×10^–5 8×10^–5T). Conversely the DNA synthesis of cells in the fields at 4×10^–4 T was repressed to 80% of that in controls not exposed to the fields.This work was supported by Kaken Pharmaceutical Co., Ltd, Tokyo, Japan, and in part by a Grant-in-Aid from the Ministry of Education, Science and Culture of Japan and from the Foundation for Life Science Promotion Tokyo, Japan to I.K.     

Biochemical aspects of radiation biology

Summary In order to analyze the mechanisms of biological radiation effects, the events after radiation energy absorption in irradiated organisms have to be studied by physico-chemical and biochemical methods. The radiation effects in vitro on biomolecules, especially DNA, are described, as well as their alterations in irradiated cells. Whereas in vitro, in aqueous solution, predominantly OH radicals are effective and lead to damage in single moieties of the DNA, in vivo the direct absorption of radiation energy leads to locally multiply-damaged sites, which produce DNA double-strand breaks and locally denatured regions. DNA damage will be repaired in irradiated cells. Error free repair leads to the original nucleotide sequence in the genome by excision or by recombination. Error prone repair (mutagenic repair), leads to mutation. However, the biochemistry of these processes, regulated by a number of genes, is poorly understood. In addition, more complex reactions, such as gene amplification and transposition of mobile gene elements, are responsible for mutation or malignant transformation.     

麻疯树适生区域土壤DNA提取及多重PCR验证

比较了4种土壤总DNA提取方法应用于四川西昌去南元谋和海南海口三地麻疯树适生区土壤样品的DNA提取效果,发现改进后的方法1和方法4提取效果显著好于方法2和方法3.不仅如此,采用多重PCR扩增方法证明方法1和方法4扩增的真菌DNA产量所占比例增加,说明所得DNA更具有代表性.然而仅有方法4能成功提取海南及云南两地麻疯树适生地区的土壤总DNA,但提取的DNA纯度和产量过低,说明还需进一步进行优化.     

超顺磁性Fe3O4@SiO2空心亚微球的制备及其在质粒DNA分离纯化中的应用

采用溶剂热法合成超顺磁性空心亚微球,然后通过正硅酸乙酯水解-聚合反应,在亚微球表面包覆SiO₂,形成核壳结构Fe₃O₄@SiO₂空心亚微球。以该Fe₃O₄@SiO₂亚微球为分离介质,实现了大肠杆菌（E. coli）质粒DNA的高效、快速分离。     

污水处理系统中噬菌体的浓缩分离和宏合格基因组DNA的提取

以城市污水活性污泥为材料,经分级粗滤、超滤、等密度梯度离心等方法获得高纯度噬菌体悬液,常规SDS方法提取噬菌体DNA.荧光显微镜观察和计数表明浓缩液中噬菌体的纯度和丰度都显著提高;利用透射电镜对浓缩液进行观察,噬菌体的形态呈杆状、线状等多样;基因组提取结果显示,得到的DNA样品纯度高,大小介于20~25kb之间,电泳条带清晰,整个泳道没有弥散现象;利用细菌通用引物对提取的噬菌体DNA进行16SrDNA扩增阴性,说明所得到的噬菌体纯度较高,没有细菌污染.通过实验获得一种高效快捷的从污水处理系统中纯化浓缩噬菌体并进一步获得噬菌体宏基因组DNA的方法,同时为研究环境噬菌体生态分布、多样性组成奠定基础.     

Redescription of the Cephalaspidea gastropod Atys jeffreysi (Weinkauff, 1866) (Haminoeidae), with a discussion on the phylogenetic affinities of the Mediterranean species of the genus

Atys jeffreysi is a heterobranch Cephalaspidea gastropod belonging to the family Haminoeidae occurring in the Mediterranean Sea, Madeira and Canary archipelagos. Nearly nothing is known about the internal anatomical features of this species. In this paper we redescribe the species A. jeffreysi based on fine anatomical work and scanning electron microscopy. DNA barcodes are provided for the first time for A. jeffreysi and A. macandrewii, the only two species of the genus native in the Mediterranean Sea. The genetic distance (COI uncorrected p-distance) between them is estimate at 21.6%. A Bayesian molecular phylogeny based on the gene marker cytochrome c oxidase subunit I (COI) including all sequences available of the genera Aliculastrum, Liloa and Atys species did not support a sister relationship between the two Mediterranean species and suggests that they are more closely related to distinct Indo-West Pacific lineages. The complex systematics of the genus Atys is briefly discussed.     

DNA分子电荷输运的大极化机制探讨

近年来研究发现,与生命体密切相关的DNA损伤与修复过程伴随着DNA链内电荷的转移.在DNA中,极化子是重要的元激发,是DNA中电荷传递可能的载流子.为了更好的理解DNA的电荷输运的极化子机制,给出了能够准确估计电声耦合常数α数值的理论方法.利用确定的电声耦合常数α,计算了极化子宽度和极化子束缚能.计算结果显示,DNA中的电荷输运是通过大极化子的相干运动来实现的.     

Protection against malaria by immunization with plasmid DNA encoding cholera toxin B subunit andPlasmodium falciparum epitopes

Cholera toxin B subunit is a good carrier protein and an effective adjuvant which can boost both cellular and humoral immunity. DNA fragments encoding B cell, Th cell and CTL epitopes of P. falciparum CS, MSA-1, MSA-2 and RESA antigens were cloned down-stream of cholera toxin B subunit gene in the same reading frame. Another modification using IL2 as adjuvant was also made. High titer of anti-malaria epitopes antibodies and strong cellular immunogenicity were elicited after Balb/c mice were immunized three times with 100 μg recombinant plasmid DNA dissolved in 100 μL PBS. 200 vaccinees were challenged with mouse Plasmodium yoelli to investigate if cross protection existed. The protective efficacy was about 50%. And it is found that the protective efficacy is correlated with CTL activity which was considered to be the primary effects of anti-sporozoite protective immunity. Better results might be expected when the DNA vaccine candidates were applied to primates.     

微波加热快速测定中药提取物的干重及出膏率

利用微波法测定了几种中药提取物的干重及出膏率，同时与烘箱法进行了比较。由实验结果可知，该法与传统法相比，具有省时、省工、省电等优点。     

扫描隧道显微镜应用于生物超微结构探测的机制

在利用扫描隧道显微镜研究质位pUC18DNA分子线圈型超螺旋拓扑结构的基础上，进一步探讨了扫描隧道显微镜应用于生物超微结构探测的可能机制，并指出扫描隧道显微镜技术是探测生物超微结构，尤其是DNA拓扑结构的较好手段。