Oxidative damages to DNA by indoor PM10s: Their relationships with trace element compositions

Plasmid DNA assay and ICP-MS analysis were conducted in order to investigate the bioreactivity of inhalable particles (PM10) and the relationship between bioreactivity and trace element compositions of PM10 in Beijing air. A total of four PM10 samples were carefully selected to represent the indoor and corresponding outdoor environments: one from urban smoker's home, two from non-smoker's homes, and the other from the outdoor. In general, the oxidative damage by indoor PM10 was slightly higher than that of outdoor. Among the four sets of samples, the PM10 from the smoker's home had a lowest TD50 (toxic dose of PM10 causing 50% DNA to be damaged), being 100 μg·mL-1, suggesting the highest bioreactivity. The heavy metals are believed to be the main reason for oxidative damage to plasmid DNA. The ICP-MS analysis combined with the DNA assay showed that the water-soluble zinc levels had better relationship with TD50 values than other elements, implying that water-soluble zinc might play an important role in the damage of DNA. It is concluded that the PM10 in smoker's home had the highest level of water-soluble zinc as well as the lowest TD50 (highest bioreactivity). Iron is considered to be one of the most bioreactive elements, but it will cause little damage to plasmid DNA, probably because iron is mainly in water-insoluble state in Beijing PM10.     

微生物之间竞争模型的全局分析

本文讨论具有再生养分流的具有质粒与不具有质粒微生物之间竞争的数学模型．假定再生养分流不具有时滞时，我们对的模型的平衡位置进行了全局分析．     

基于DNA计算的最大权团问题设计

介绍了最大团和最大权团的概念和国内外学者运用DNA计算解决最大团的研究成果;结合前人运用质粒、二进制、粘贴模型等方式进行DNA计算操作的原理,设计了新的用于解决最大权团问题的算法步骤,大大提高了算法效率,实现了最大团和最大权团的同步求解,对市场分析、方案选择等领域有一定的意义。     

自然杀伤（NK）细胞在免疫缺陷小鼠体内的研究进展

为了研究自然杀伤细胞对正常人及人类恶性淋巴造血细胞的排斥作用，将严重的联合免疫缺陷突变小鼠或ｂｅｉｇｅ小鼠分别与Ｃ５７ＢＬ／６Ｊ小鼠杂交。Ｃ５７ＢＬ／６Ｊ－ｓｃｉｄ小鼠显示成熟的Ｔ、Ｂ细胞严重丢失并伴随ＮＫ１．１细胞的百分比增加。虽然２月龄内的小鼠血清免疫球蛋白含量甚微，但７．５月龄的小鼠均可检出免疫球蛋白。Ｃ５７ＢＬ／６Ｊ－ｓｃｉｄ／ｓｃｉｄ小鼠与Ｃ５７ＢＬ／６Ｊ＋／＋对照组小鼠比较，溶血性补体     

A novel salicylaldehyde dehydrogenase-NahV involved in catabolism of naphthalene from Pseudomonas putida ND6

A novel salicylaldehyde dehydrogenase involved in catabolism of naphthalene from Pseudomonas putida ND6, NahV, has been identified. NahV exhibited lower identity in amino acid sequence with the classic salicylaldehyde dehydrogenase, NahF, from P. putida ND6. This is the first report of an isofunctional enzyme of bacterial salicylaldehyde dehydrogenase. Comparison of Km and Vmax values of NahV and NahF demonstrated that NahF has a more efficient catalytic reaction than NahV, while NahV has much higher affinity for salicylaldehyde and NAD . Both enzymes exhibited broad substrate speci- ficities and catalyzed the oxidation of salicylaldehyde, 5-chlorosalicylaldehyde, formaldehyde, m-nitrobenzaldehyde, o-nitrobenzaldehyde, o-methoxybenxaldehyde, glutaraldehyde, caprylic aldehyde, and glyoxal. However, the relative rates at which the substituted analogs are transformed differ considerably. NahV activity could be enhanced by Fe2 , Cu2 and Zn2 ; whereas NahF activity could only be stimulated by Fe2 . NahF is more stable than NahV at elevated temperatures. Dot-blot hybridization analyses showed that nahF-like genes occurred in all naphthalene-degradation bacteria isolated in this study, whereas nahV-like genes were present in only some naphthalene-degrading bacteria.     

Identification and analysis of the gas vesicle gene cluster on an unstable plasmid ofHalobacterium halobium

In our efforts to elucidate the mechanism of high-frequency mutation ofHalobacterium halobium to a gas vesicle deficient state, we discovered insertions, deletions, inversions, and complex DNA rearrangements associated with a large endogenous plasmid, pNRC100. The rearrangements are mostly IS element-mediated, and when they occur in a region of pNCRC100 containing a cluster of thirteen genes, gas vesicle mutants result. We have characterized the structure and expression of this gas vesicle protein (gvp) gene cluster and demonstrated its requirement for gas vesicle synthesis and cell flotation by genetic transformation.     

甲酸钠的抗氧化作用

以溶血试验、红细胞还原型谷胱甘肽测定、受照南粒ＰＵＣ１８ＤＮＡ单链断裂的测定、受照小鼠肝和肾匀浆脂质过氧化物的测定作为指标，检测了甲酸钠的抗氧化作用。结果表明：甲酸钠能显著地降低受＾６０Ｃｏγ射线照射的红细胞的溶血水平；显著抑制ＶｉｔＣ／Ｆｅ＾＋＋诱导的红细胞悬液还原型谷胱甘肽的耗竭；显著抑制受质粒ＰＵＣ１８ＤＮＡ单链断裂程度；显著地抑制受照小鼠肝、肾匀浆丙二醛水平的升高，结果提示：内具有抗氧化作     

Ti质粒转化胡萝卜细胞的初步研究

本文报道了通过三亲酱将Ｐ＾ＢＩ１０１等Ｔｉ质粒从大肠杆菌（Ｅ．ｃｏｌｉＣ６００）中转移到发根农杆菌（Ａｇｒｏｂａｃｔｅｒｉｕｍ ｒｈｉｚｏｇｅｎｅｓ）中，并获得转移子，将上述转移子与胡萝卜悬浮细胞混合共培养后得到转化细胞。转化细胞在没加生长激素和细胞分裂素的情况下能知主生长，并获得愈伤组织。     

大熊猫肠道菌抗生素抗性菌转座酶的基因克隆和表达

对大熊猫肠道大肠杆菌抗生素抗性质粒pAm08CD7339全序列的生物信息学分析结果表明,该质粒中存在一个编码转座酶的DNA片段,两条DNA链均可编码转座酶,其编码区长度分别为717 bp和600 bp,编码238个和199个氨基酸残基（分别命名为Transposase238和Transposase199）.以pAm08CD7339质粒DNA为模板,利用PCR方法对2个转座酶基因进行扩增,构建相应表达质粒,转化不同大肠杆菌菌株进行表达,结果表明：Transposase199可以在E.coli BL2