离子束生物效应及应用中值得研究的几个问题

重离子束生物效应及重离子束在生命科学中的应用研究,在国内外物理学与生命科学领域中得到了广泛的开展,但对出现的一些现象还没有深刻地揭露其本质,作出机理性解释。为了深入研究,本文提出一些值得研究的问题供参考,如:重离子径迹结构及能量沉积分布模型,DNA辐射敏感位点,质量沉积-分子改造,直接作用与间接作用,放射性核束的应用等。     

低能重离子在作物种胚内射程分布的研究技术

我国科学工作者率先将低能重离子束成功地应用于作物诱变育种,并建立了能量,质量和电荷三因子作用机制体系,但至今有关理论射程很短的低能重离子注入生物体后如何通过信息传递而诱发生物学效应的机理尚不完全清楚,低能重离子在作物种胚内的实际射程分布迄今仍是一个颇有争议的热点问题,而该项研究就直接触及低能离子束与生物组织细胞的原初作用机制,应用低能放射性束或具有可探测放射性的核反应产物,通过超薄切片和逐层分析测定,即可定量计算不同能量的低能离子束在作物种胚内的射程分布,本文还探讨了激光共聚焦扫描显微镜,原子力显微镜,X-射线能谱分析技术,单粒子微束技术和图像处理等技术途径在该项研究中的应用。     

三种辐射源对耐辐射微球菌作用机理的比较研究

三种辐射源对耐辐射微球菌作用机理的比较研究宋道军余增亮（中国科学院等离子体物理研究所离子束生物工程研究中心合肥２３００３１八十年代中期创立于我国的低能重离子生物学，研究已证实注入离子对植物和微生物均有良好的诱变效应［１－４］。离子注入生物体集能量沉积...     

低能离子束生物技术的应用

自从我国科学家发现离子注入生物学效应后,低能离子束生物技术的研究就在我国率先兴起。随后,越来越多的科学家基于低能离子与生物体之间存在的能量沉积、动量传递、质量沉积及电荷中和与交换的相互作用,对生物体内的遗传物质进行加工、修饰、重组,开辟了农作物和微生物等遗传改良及转基因的新方法。本文简要介绍了低能离子束生物技术产生的背景、低能离子束与生物体之间相互作用的机理和特点以及目前低能离子束在诱变育种和转基因等生物技术领域的研究进展,并展望了离子束技术在藻类基因工程方面的发展潜力。     

低能铁离子束对原卟啉IX二钠盐的辐照效应研究

110ke V Fe^ 离子注入原卟啉IX二钠盐薄膜亲品后的一些谱学分析结果表明,低能铁离子束辐照可以导致生物分子的损伤和化学改性,并且初步证实注入铁离子在样品分子中慢化沉积后形成含铁的金属络合物,即注入铁离子的质量沉积。     

离子束对生物体的作用原理及应用

离子束是指一束具有一定能量的质量数小于或等于4的带电离子束,离子束注入技术是生物物理技术,具有生理损伤小、突变谱广和突变频率高等特点。离子束与生物体的相互作用是我国具有独立知识产权的生物物理技术,我国科学家在上世纪80年代已经发现了离子束注入的生物效应,并将这一原理应用于植物诱变育种。本文主要概述了低能离子束注入对生物体的作用原理,以及该技术在植物育种、微生物品种改良和遗传改良上的应用,最后还小结了离子束注入技术在研究领域存在的问题并对其未来发展方向提出展望。     

重离子诱变微生物育种的研究进展

近年来,重离子束作为一种新的辐射诱变源在微生物育种领域已多有应用.与传统的辐照源相比,重离子束具有更高的传能线密度,可以产生更强的辐射损伤生物效应,因此诱变效率高.本文综述了近年来重离子诱变在微生物育种中取得的进展、诱变后突变体菌株的筛选策略、重离子束引起微生物遗传物质改变的直接和间接机制以及突变后的修复机理,并对其在...     

磁场的生物学效应及其机理的研究

本就不同参数的磁场的生物学效应研究进行了综述,总结了磁场对生命体整体、组织、器官、细胞直至生物大分子层面上的研究成果,并结合实验结果对磁场生物学效应的可能物理机制进行了初步探讨,并对磁场生物学效应的研究前景进行了展望。     

磁场的生物学效应及其机理的研究

本文就不同参数的磁场的生物学效应研究进行了综述,总结了磁场对生命体整体、组织、器官、细胞直至生物大分子层面上的研究成果,并结合实验结果对磁场生物学效应的可能物理机制进行了初步探讨,并对磁场生物学效应的研究前景进行了展望。     

羟自由基、γ射线和重离子束致死效应的比较

以集落法测存活率、用双链断裂模型分析实验数据,比较研究了羟自由基、γ射线和125．5keV/μm碳离子束对B16细胞和V79细胞的致死效应。结果表明：三种处理对细胞都有明显的致死作用,剂量越大,效果越明显;重离子束的致效效应比γ射线强,而且对抗常规辐射的黑色素瘤也有效,证明了重离子治癌的优势;羟自由基与DNA的作用没有一次击中的成分,碳离子束则以一次击中为主,γ射线介于两者之间,两种细胞对羧自由基的敏感性与对电脑辐射的敏感不同,揭示电离辐射的间接作用不是简单的自由基行为。     

Alternative reproductive tactics in atlantic salmon: factors affecting mature parr success

In Atlantic salmon, as in most salmonids, males can mature early in the life cycle, as small freshwater fish, termed parr, and/or undergo a sea migration before maturing as full-size adults. The alternative life histories are contingent on environmental and social circumstances, such as growth rate, territory quality or any other factor that affects the individual''s state. In order to model the choice of life history in this group of commercially valuable species, it is necessary to understand not only the relative contribution of the different male types to subsequent generations, but also to know the factors that affect reproductive success in each type. In this paper we present the results of a study designed to investigate the factors that affect the reproductive success of mature parr. We used highly polymorphic minisatellite DNA markers to analyse paternity in a series of mating experiments where the number and body size of parr were manipulated. The fraction of eggs fertilized by mature parr ranged from 26 to 40 per cent, with individual parr fertilizing up to 26 per cent of the eggs. A strong positive correlation was found between parr size and reproductive success. The relative success of parr decreased with increasing parr number. Data from this and other studies on variation in the timing and degree of parr reproductive success are discussed in relation to the evolution of male mating strategies and life history in salmonids.     

The Biology of the Acaropathogenic Fungus Hirsutella kirchneri

The acaropathogenic fungus Hirsutella kirchneri (Rostrup) Minter , Brady and Hall grew best and produced most mycelia on a medium containing yeast extract , dextrose and agar; conidial production , however , was maximal or potato dextrose agar (PDA) . The best growth on both media was at 25 C and conidial germination was high within a wide range of temperatures (10 - 35 C) . Colony growth , mycelial mass production and conidial yield were best under alternating dark and light regimes . Maximal germination occurred under dark conditions . When grown in continuous light the fungus produced synnemata (compacted conidiophores) which remained viable for 22 weeks . Of six species of phytophagous mites assayed , three spider mites and a rust mite became infected by the fungus , as did , to a limited degree , a parasitic mite . Another four mites , including two pests , a scavenger and a predator , were unaffected . The fungus grew on and sporulated from heat - killed cadavers of a dead mealybug (Homoptera) . Conidial germination and penetration into live mites , under saturation condi tions , were affected little by temperatures . Intra - host growth was temperature dependent , with mite death beginning on the second or third day post - infection . Maximal sporulation from infected mites took place at 25 C . Mortality was quickest at 25 C when mites were held under saturation conditions , but some death also occurred at lower relative humidities . These data are discussed with a view to using H. kirchneri in the biological control of plant mites .     

Modular Structure of Biochips Based on Microstructured Deposition of Functional Nanoparticles

This paper presents the microstructured deposition of nanoparticles, which are chemically modified to be conjugated to biomolecules or dyes. In our approach, we separated the technical steps “surface chemistry” and “microstructuring” into two fully independent processes. This was realized by firstly synthesizing specific nanoparticles with tailor‐made surfaces. Thus, the surface chemistry was customized to the demands of most different kinds of specific proteins. Then, microstructured monolayer arrays of these nanoparticles were generated by photolithography, microcontact printing or spotting with a microarrayer. The overall system resulted in a nanoparticle‐based microarray for the selective binding of protein ligands providing both wide flexibility and high specificity.     

A study of the transport and deposition of oilseed rape (Brassica napus L.) pollen in east Fife, Scotland

It has been suggested that there is a link between the relatively recent expansion in the farming of oilseed rape (Brassica napus L.) and an increase in the incidence of respiratory illness in eastern Scotland. However, there is limited evidence of the extent to which one possible cause of this increased illness, the pollen of oilseed rape, is disseminated from fields of this crop. The present study used sedimentation traps and a portable volumetric air sampler to study the transport of pollen from rape fields in Fife, and the results confirmed the widely held view that most of the pollen travels only a short distance from its source. In this case relatively low quantities ofBrassica pollen were detected more than 200 m from fields of rape. This may have implications for the formulation of advice for those who appear to suffer from an allergic reaction to rape crops.     

甲型链球菌SN-34和SN-35体外抑菌作用的研究

目的观察甲型链球菌SN-34和SN-35的抑菌效果。方法在固体培养基上用复层琼脂法观测甲型链球菌SN-34和SN-35对化脓性链球菌32309-2和金黄色葡萄球菌26001的抑菌环大小;在液体培养基中,甲型链球菌SN-34和SN-35分别与化脓性链球菌32309-2和金黄色葡萄球菌26001共同培养,然后观察一定间隔（2h）细菌的数量变化,并绘制生长曲线。结果化脓性链球菌32309-2的生长明显受到抑制。结论仅甲型链球菌SN-34具有抑菌作用。     

氦—氖激光照射对孔雀鱼乳酸脱氢酶等的作用效应

本实验使用氦氖激光采用不同的处理时间照射孔雀鱼的仔鱼,分析其ＬＤＨ,ＩＤＨ及过氧化物酶的活性变化,实验表明：氦氖激光照射仔鱼可引起上述酶的活性出现不同程度的提高     

Development of a coupled-column liquid chromatographic–tandem mass spectrometric method for the direct determination of betamethasone in urine

Different hyphenated liquid chromatographic (LC) and mass spectrometric (MS) techniques were investigated in order to set-up a method for the fast, direct analysis of betamethasone in hydrolysed and non-hydrolysed urine using large-volume sample injection. After the optimisation of the LC parameters using a traditional UV detector and of the thermospray and mass spectrometric parameters by flow injection, urine samples (0.5 ml) were submitted to analysis by either LC combined with tandem mass spectrometry (MS–MS), coupled-column LC (LC–LC) combined with single quadrupole MS, and LC–LC–MS–MS. Both the three-step configurations (LC–MS–MS and LC–LC–MS) did not provide satisfactory results: loss of sensitivity was noted in the case of LC–MS–MS (likely due to reduced efficiency in the ionisation of betamethasone in the thermospray owing to the presence of large amounts of matrix interference), while in the case of LC–LC–MS a high chemical noise resulting in insufficient selectivity of detection was observed. On the contrary, LC–LC–MS–MS analysis proved to meet the demand of high speed of analysis (sample throughput, 4.5 h⁻¹), selectivity, and sensitivity (LOQ, 1 ng/ml; LOD, 0.2 ng/ml). Notwithstanding the complex analytical system adopted, the developed procedure was manageable and very robust, provided that at the beginning of each analytical session the performance of the system was controlled by checking the retention time of the analytes on the first analytical column with UV detection and by optimising vaporiser temperature of the thermospray by flow injection.     

Photochemistry of bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)strontium tetraglyme solutions for eventual liquid phase photochemical deposition

The mechanism of Sr(hfac)₂TG (hfac = 1,1,1,5,5,5,hexafluoro-2,4-pentanedionato and TG, tetraglyme = 2,5,8,11,14-pentaoxapentadecane) photodegradation was investigated in methanol and dichloromethane at 254 and 300 nm. In methanol, photodegradation led to SrF₂ through the attack of fluoride on the metal, occurring from the CF₃ group in the intraligand excited state π-π*. In dichloromethane, a mixture of SrCl₂ and SrF₂ was obtained in proportions dependent on the initial complex concentration and irradiation wavelength. SrF₂ was formed by photoexcited species of the complex with the same mechanism occurring in methanol. SrCl₂ was formed by a solvent-initiated reaction at 254 nm, involving substitution of ligand by chloride ion, coming from photochemical solvent decomposition, whereas at 300 nm it was formed by a solvent-assisted reaction, involving an electron transfer to solvent from excited ligand in triplet state.The photochemical kinetics were followed by UV spectrophotometry, the photodecomposition products were recognized by ESI-mass, XRD and XPS. The Sr(hfac)₂TG photodegradation was usefully exploited to obtain pure thin films or mixture of SrCl₂ and SrF₂ by the LPPD technique, operating in suitable experimental conditions. The films were characterized by SEM, XPS and XRD.     

Field measurements of the acidity of cloudwater deposited on polypropylene surfaces and Sitka spruce shoots

Summary Enhancement of the acidity of water on conifer needles, caused by evaporation even during the presence of cloud, is investigated. Field measurements of the acidity of droplets on polypropylene surfaces, shaped like needle bearing conifer shoots, and on Sitka spruce shoots, showed that surface droplet acidity varied significantly over a few hours, due to many causes. The acidity of the droplets commonly reached 800 eq/l (pH = 3.1) and occasionally 1000 eq/l (pH = 3.0). Increases in H⁺ ion concentration due to evaporation of pure water from the droplets occurred particularly around the end of cloud events. It was concluded that variation of H⁺ concentration of water on conifer needles due to evaporation during the presence of cloud is likely to be less important than that due to the other reasons. In particular the increase in H⁺ concentration from the reduction in droplet volume, due to evaporation, after the end of a cloud event is likely to be the most significant.