~(12)C~(6+)重离子辐照大葱的细胞学和RAPD分析

用309、0和180Gy12C6+重离子辐照处理大葱干种子,研究其对大葱根尖的细胞学效应,并采用随机扩增多态性DNA(RAPD)技术初步分析了其变异类型。不同剂量12C6+的重离子照射能有效诱导大葱根尖细胞微核和染色体畸变。随着辐照剂量的增加,幼苗根尖细胞微核形成几率明显增大,微核率、多微核率和染色体总畸变率呈线性上升。但除去微核以外的染色体畸变率则呈U型变化。RAPD结果表明,大葱不同处理之间的DNA存在明显差异,所用35种引物中有28种出现了特异性条带,既有新增条带,又有缺失条带,还有迁移率的差异。30、90和180Gy剂量辐照引起的RAPD变异率分别为29.91%、41.05%和22.14%。结果发现高微核率和染色体变异过大会导致高致死效应,使得染色体总畸变率高的处理组在当代生长苗的DNA变异率变小。

加速~(12)C~(6+)离子照射诱发人肝癌细胞SMMC-7721的DNA双链断裂

重离子为高传能线密度(LET)辐射;;在引起肿瘤细胞失活上有更大的相对生物学效应。DNA的双链断裂在细胞辐射损伤中是极其重要的;;其最终导致细胞的失活。本实验研究检测细胞DNA的双链断裂(DSB);;以探讨细胞失活的机理。用脉冲场凝胶电泳方法结合溴乙锭染色的荧光扫描技术;;定量测定C诱导人肝癌126+细胞SMMC?7721DNA的DSB剂量效应关系。结果发现;;DNA片段释放百分比随吸收剂量的增加而增加。

~(12)C~(6+)注入小麦种子胚乳引起M_1代的变化

通过控制单核能大小 ,将 1 2 C离子注入小麦种子胚乳 ,结果引起 M1 代植株的较大变化。这些变化包括 :生物学性状的变异 ;根尖细胞染色体畸变率和微核率的显著提高 ;POD酶活性显著提高和 CAT酶活性、MDA含量和蛋白质含量的较大程度的下降等。本文也讨论了诱变胚乳对胚作用的可能机理

C-N化合物合成研究

用能量 50 - 1 1 0 ke V的 N离子在低于 80°C温度下注入 CVD法合成的金刚石薄膜后 ,分别用 X射线光电子谱、红外谱和拉曼谱检测注入后的薄膜中是否形成了 C- N化合物 .结果表明注入后的薄膜中存在有 3种化学键态的 C- N化合物 ,且低能离子注入更有利于 C- N化合物的形成 .由于在注入区内形成了大量的 C- N单键 ,这有利于β- C3N4 的合成 .对 C- N化合物薄膜的场发射特性也做了研究

Kinetic energies of C-n(+) (n <= 58) fragment ions produced by nanosecond laser impact on C-60

Laser-induced fragmentation of C-60 has been studied using a time-of-flight mass spectrometric technique. The average kinetic energies of fragment ions C-n(+) (n <= 58) have been extracted from the measured full width at half maximum (FWHM) of ion beam profiles. The primary formation mechanism of small fragment ion C-n(+) (n < 30) is assumed to be a two-step fragmentation process: C60 sequential decay to unstable C-30(+) ion and the binary fission of C-30(+). Considering a second photo absorption process in the later part of laser pulse duration, good agreement is achieved between experiment and theoretical description of photoion formation. (C) 2009 Elsevier B. V. All rights reserved.

High negative ion production yield in 30 keV F2+ + adenine (C5H5N5) collisions

In collisions between slow F2+ ions (30 keV) and molecular targets, adenine, scattered particle production yields have been measured directly by simultaneous detection of neutrals, positive and negative ions. The relative cross-section for a negative ion formation channel was measured to be 1%. Despite a slight decrease compared to a larger target, the fullerene C-60, the measured negative ion formation cross section is still at least one order of magnitude larger than the yield in ion-atom interactions.

Pre-irradiation with low-dose C-12(6+) beam significantly enhances the efficacy of AdCMV-p53 gene therapy in human non-small lung cancer

The combination of ionizing radiation and gene therapy has been investigated. However, there are very few reports about the combination of heavy-ion irradiation and gene therapy. To determine if the pre-exposure to low-dose heavy ion beam enhances the suppression of AdCMV-p53 on non-small lung cancer (NSLC), the cells pre-irradiated or non-irradiated were infected with 20, 40 MOI of AdCMV-p53. Survival fraction and the relative biology effect (RBE) were determined by clonogenic assay. The results showed that the proportions of p53 positive cells in C-12(6+) beam induced AdCMV-p53 infected cells were more than 90%, which were significantly more than those in gamma-ray induced AdCMV-p53 infected cells. The pre-exposure to low-dose 12C6+ beam significantly prevented the G(0)/G(1) arrest and activated G(2)/M checkpoints. The pre-exposure to C-12(6+) beam significantly improved cell to apoptosis. RBEs for the C-12(6+)+ AdCMV-p53 infection groups were 30%-60%,20% -130% and 30%-70% more than those for the C-12(6+)_irradiated only, AdCMV-p53 infected only, and gamma-irradiation induced AdCMVp53 infected groups, respectively. The data suggested that the pre-exposure to low-dose C-12(6+) beam significantly promotes exogenous p53 expression in NSLC, and the suppression of AdCMV-p53 gene therapy on NSLC.

Molybdenum L-shell X-ray production by 350-600 keV Xeq+ (q=25-30) ions

Molybdenum L-shell X-rays were produced by Xeq+ (q = 25-30) bombardment at low energies from 2.65 to 4.55 keV/amu (350-600 keV). We observed a kinetic energy threshold of Mo L-shell ionization down to 2.65-3.03 keV/amu (350-400 keV). The charge state effect of the incident ions was not observed which shows that the ions were neutralized, reaching an equilibrium charge state and losing their initial charge state memory before production of L-shell vacancies resulted in X-ray production. The experimental ionization cross sections were compared with those from Binary Encounter Approximation theory. Taking into account projectile deflection in the target nuclear Coulomb field, the ionization cross section of Mo L-shell near the kinetic energy threshold was well described. (C) 2010 Published by Elsevier B.V.

~(12)C~(6+)高能重离子辐照大葱损伤及其分子生物学效应；Cytological Damage and Molecular Biology Effect of ~(12)C~(6+) Heavy Ions on Allium fistulosum L.

利用30,90,180Gy3种剂量的12C6+重离子束辐照大葱种子,研究其在细胞水平和农艺性状的诱变效应并进行RAPD分析。通过与M1代的研究结果比较后表明:经过不同剂量12C6+重离子照射后能有效地诱导大葱细胞形成微核和染色体畸变,这种诱变效应,在M2代仍然有所表现。M1代大葱结果期的株高、白长、花序直径和种子产量随辐照剂量增加产生明显差别,其中30Gy辐照组增幅最大。大葱总水溶性蛋白质和维生素C的含量在30Gy组中积累最多,在90Gy组有明显下降。与M1代一致,M2代中大葱染色体微核率及RAPD分析所得的DNA多态性比率仍然与辐照剂量呈正相关,但比率整体下降;说明高能量重离子辐照造成的DNA变异在M2代被修复和淘汰。

CO_2干扰对红松和长白赤松幼苗土壤微生物量C的影响

以不同浓度CO2(700、500μm o l/m o l)处理的红松和长白赤松幼苗土壤为研究对象,在2003年的7~9月的中旬采样,对0~10 cm层土壤微生物生物量C受高浓度CO2影响进行了研究。结果表明,700μm o l/m o l CO2对红松幼苗土壤微生物生物量C起着极显著(p<0.01)抑制效应,其作用大于500μm o l/m o l CO2处理;受高浓度CO2处理的长白赤松幼苗土壤微生物生物量C表现出了与红松土壤微生物生物量C相似的变化规律。此外,500μm o l/m o l CO2条件对红松和长白赤松幼苗土壤微生物生物量C的影响存在着不稳定性。

巨大芽孢杆菌在维生素C二步发酵中的作用

巨大芽孢杆菌培养时期不同其上清液对促进氧化葡萄糖酸杆菌生长和产酸能力不同 ,在稳定期及衰亡初期显著促进氧化葡萄糖酸杆菌生长与产酸。pH、温度可改变上清液对氧化葡萄糖酸杆菌生长与产酸的影响。上清液中含活性物质具有蛋白质的部分性质 ,对酸、碱、热敏感

维生素C“二步发酵法”第二步发酵混合菌关系的研究

维生素Ｃ“二步发酵法”第二步发酵混合菌关系的研究马成新，杨凤玫，焦鹏，薛德林，王书锦（中国科学院沈阳应用生态研究所，１１００１５）维生素Ｃ作为一种重要的医药产品，不但用于治疗多种疾病，而且已被广泛用于食品、化妆品、饲料产品中，随着维生素Ｃ应用范围的增...

维生素C二步发酵混菌接种控制

本文研究维生素C二步发酵接种种液状态与发酵转化的关系，指明接种种液浓度为6．5×109个／ml，二菌数量之比为0.3，种液酸量为7mg／ml时．可获得较好的发酵转化效率。

维生素C二步发酵中L-山梨糖脱氢酶的性质及作用

从氧化葡萄糖酸杆菌细胞质中分离纯化出L 山梨糖脱氢酶 (SDH) ,其分子量为 46× 10 3 ,表观分子量为 190× 10 3 ;在测试范围内 ,最适pH是 7.4,温度为 5 5℃ ,最稳定的 pH是 7.0 ,温度为 30℃以下 ;FeCl3 促进酶活 ,CoCl2 抑制酶活 .该酶活力与发酵产物 2 酮基 L 古龙酸的合成呈正相关 ;伴生菌促进产酸菌生长和代谢 ,并使该酶比活力增加 ,从而提高发酵系统中该酶的总活力 .图 11表 5参 9