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1.
紫外线B区对小牛胸腺DNA损伤的拉曼光谱研究   总被引:2,自引:0,他引:2  
用拉曼光谱检测了远紫外区UVB(280m~320nm)对小牛胸腺DNA的损伤,并对这个区段紫外线对DNA的不同照射时间时的损伤特征进行了比较分析。实验中所用的紫外线强度与太阳光强度相当。结果表明,辐照3h以内时,UVB对DNA的构型有较明显的损伤,这可能是受到嘧啶碱基损伤的影响。相对而言,UVB对脱氧核糖和碱基的损伤要严厉得多。就碱基对的受损伤程度来说,嘧啶碱受损最严重,部分证明了环丁烷嘧啶二聚体和6-4光产物的形成。经过3h UVB照射,AT碱基对和和胞嘧啶环的堆叠程度有所瓦解,一些碱基对受到修饰。而一些拉曼特征峰强度的反复波动,则说明了长时间的紫外照射可以导致部分DNA光复活的产生。进一步分析发现,UVB以一种较快的方式对DNA产生损伤。  相似文献   

2.
抗癌药物ADM与DNA相互作用的紫外共振拉曼光谱的研究   总被引:11,自引:0,他引:11  
用紫外共振拉曼光谱研究了ADM与小牛胸腺DNA相互作用,分析表明:ADM插入DNA的GC-CG位置,ADM与DNA之间的主要相互作用是蒽环π电子与碱基G和C的π电子形成的π-π电子相互作用,并通过碱基G,C的NH2的氮的孤对P电子与ADM的π-P电子相互作用以及ADM和DNA碱基G,C和PO2之间形成的氢键使相互作用加强;ADM插入DNA使其构象产生一定变化,但未破坏DNA碱基对间的氢键。  相似文献   

3.
增强UV—B辐射对蚕豆叶片微粒体膜一些性质的影响   总被引:11,自引:0,他引:11  
温室条件下,用0,8.65kJm^-2d^-1及11.2kJm^-2d^-1不同剂量的UV-B辐射处理蚕豆幼苗。Ca^2+-ATPase及Mg^2+-ATPase的活性在辐射处理期间下降。在处理21d,T1和T2微粒体膜的MDA含量明显高于对照,同时IUFA急剧下降,且呈明显的剂量效应。  相似文献   

4.
He—Ne激光诱变白细胞DNA的拉曼光谱研究   总被引:5,自引:0,他引:5       下载免费PDF全文
报道了He—Ne激光对白细胞DNA诱变的拉曼光谱研究。He—Ne激光辐射前,白细胞DNA主链振动区域出现二条强的A,C构型特征线812cm-1和872cm-1,以及弱的B型语线1092cm-1。辐射后,A型特征线812cm-1消失,代之是与B型结构有关的二条强的语线800cm-1和1090cm-1。试验结果表明,He—Ne激光可诱变DNA构型(AM-B型)。在碱基振动区域,辐射前其拉曼谱出现强而宽的C=0伸长振动谱线1680cm-1,这是与酮基结构有关的谱线,辐射后该谱线强度大大减弱。实验结果提示,He一Ne激光有可能使碱基发生互变异构。  相似文献   

5.
综述了UV-B辐射增强对植物光合作用的影响,植物对光破坏的响应与适应性方面的国内外研究进展,许多研究表明UV-B辐射增强对植物具有破坏作用能引起植物光抑制,光氧化和光损伤,植物依靠自身修复系统而对其破坏又具有一定的适应性。  相似文献   

6.
研究大田栽培和自然光条件下,模拟UV-B辐射(UV-B,280-315nm)增强对麦田生态系统K营养和累积的影响,UV-B辐射显著影响春小麦不同生育期各部位K含量和群体K累积,并显著降低群体K总累积,在5.31kJ.m^-2UV-B辐射下,春小麦群体K总累积的降低最显著,UV-B辐射降低春小麦群体K输出,标志着麦田生态系统K产投比降低,K循环功能下降,麦田土壤速效K含量增加是春小麦群体K输出降低的结果,并将导致土壤库中K储量的增加。  相似文献   

7.
采用循环伏安法和紫外光谱法研究了羧甲基壳聚糖-Cr(III)配合物与鲱鱼精DNA之间的作用方式。结果发现:(1)羧甲基壳聚糖-Cr(III)的存在导致Fe(CN)3-6/4-探针分子氧化还原峰电流下降,式量电位正移,显示羧甲基壳聚糖-Cr(III)和Fe(CN)3-6/4-与DNA之间存在竞争性作用,说明羧甲基壳聚糖-Cr(III)通过插入方式与DNA相互作用的;(2)中性红的加入导致羧甲基壳聚糖-Cr(III)/DNA体系的特征吸收峰发生增色效应、峰位红移并伴有等吸收点出现,这进一步表明羧甲基壳聚糖-Cr(III)是以插入方式与鲱鱼精DNA发生了相互作用,导致DNA分子的构象变化,并且CMC-Cr与DNA的结合比n(CMC-Cr):n(DNA)为3∶1。  相似文献   

8.
UV—B辐射对小麦叶片H2O2代谢的影响   总被引:11,自引:1,他引:11       下载免费PDF全文
研究了温室种植的小麦在0(CK)、8.82kJ/m^2(T1)和12.6kJ/m^2(T2)三种剂量的紫外线B(UV-B)辐射下H2O2含量的变化及其机理。UV-B辐射下H2O2、还原型抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量增加,抗坏血酸过氧化物酶(APx)和谷胱甘肽不原酶(GR)活性升高,脂肪酸不饱和度指数(IUFA)降低。SDS-PAGE谱图没有质上的差异,但凝胶着色深浅有变化。分析  相似文献   

9.
. 《西北植物学报》2000,20(3):387-391
研究了大田栽培和自然光条件下 ,模拟 UV- B辐射 ( UV- B,2 80~ 31 5nm)增强对麦田生态系统能量累积和流动的影响。在 5.31 k J· m- 2 UV- B辐射下 ,春小麦群体不同生育期叶、茎、根、穗、粒生物量和总生物量显著降低 ,各部位热值没有显著变化 ,各部位能量累积和总能量累积显著降低。能量累积与生物量呈极显著正相关 ,而与热值没有显著的相关性 ,可能生物量比热值对能量累积的贡献更大。 UV- B辐射显著降低春小麦群体能量输出 ,可能导致麦田生态系统能量流动功能下降。  相似文献   

10.
增强UV—B辐射对高山植物麻花艽净光合速率的影响   总被引:30,自引:0,他引:30       下载免费PDF全文
在高寒矮嵩草(Kobresia humilis)草甸地区以太阳短波辐射为背景,建立了人工增强UV-B辐射的实验装置,每天增补15.8kJ.m^-2的辐射剂量,模拟平流层臭氧破坏约5%时近地表面太阳UV-B辐射的增强。观测表明:UV-B辐射的增强对麻花艽(Gentiana stramianea)植物的光合作用无明显的抑制或伤害作用。相反,在早晨补充UV-B辐射的短时间内,叶片的Pn随Gs的增大而有所提高。随着UV-B辐射时间的延长,在11:30-12:30,Pn和Gs有所降低。UV-B辐射时间进一步延长后(约14:00以后),处理和对照组叶片Pn和Gs的差异趋向不明显,增强太阳UV-B辐射后,麻花艽叶片的光合色素并无明显变化,UV-B吸收物质的含量无明显变化,麻花艽叶片厚度的直接测量表明,增强UV-B辐射能明显提高叶片的厚度。叶片厚度的增加可补偿增强UV-B辐射辐后引起的光合色素的光降解,改善单位叶面积为基础的光合速率,是高原植物对强UV-B辐射的一种适应方式。  相似文献   

11.
The pH-dependent structure of calf thymus DNA is analyzed using Raman spectroscopy. The Raman spectra in the acidic region demonstrate that denaturation occurs in several steps. The binding of H+ to adenine and cytosine residues is accompanied by a decrease in the percentage of DNA in the B-conformation and a concurrent increase in a conformation most probably related to the C-form. The denaturation of DNA is observed at pH 3.3 and parallels the protonation of guanine bases. The Raman spectra of calf thymus DNA in the basic region (above pH 10) show that guanine residues are deprotonated at a lower pH value than are thymine residues. In addition, Raman spectra in the basic region detect conformational changes of the phosphate backbone different from those found in the acidic region.  相似文献   

12.
线粒体呼吸功能与精子活力、核DNA损伤的相关性分析   总被引:2,自引:0,他引:2  
为探讨线粒体呼吸功能与精子活力、核DNA损伤程度之间的相关性,按WHO标准收集34例不同活力的精液标本,采用蔗糖差速离心法或密度梯度离心法提取精子线粒体,通过铂氧电极-溶氧仪测定线粒体呼吸耗氧率并计算状态III呼吸、状态IV呼吸、呼吸控制率(RCR)、磷氧比(P/0)及氧化磷酸化效率(0PR);应用精子染色质扩散(sperm chromatin dispersion,SCD)实验检测精子DNA损伤情况。结果表明:不同活力精子线粒体状态Ⅲ呼吸耗氧量之间具有显著差异俨〈0.01);弱精子症组RcR和OPR与正常对照组比较,分别降低了17.03%(P〈0.05)和40.74%(P〈0。01);精子DNA损伤程度与精子活力、状态III呼吸及OPR均呈极显著负相关(r值分别是-0.812、-0.788和-0.696)。以上结果提示:精子线粒体呼吸耗氧和氧化磷酸化功能与精子活力之间存在着密切的联系;精子DNA(包括mtDNA)损伤可能影响精子的正常功能。  相似文献   

13.
14.
The ultraviolet resonance Raman (UV RR) spectra of functional ATP/membrane-bound Na+K+-ATPase complexes have been obtained. The substrate binding in the enzyme active site has been shown to be accompanied with significant changes in the electronic vibrational structure of the adenine ring. From the spectral analysis of ATP, 8-Br-ATP and 6-NHMe-adenine at various pH values the conclusion was made that N1 and the NH2, group and, probably, N7 of the substrate adenine part, interact with the protein surroundings via hydrogen bonds.  相似文献   

15.
Raman spectroscopy was used for the first time to detect the effect of independent UVA (ultraviolet-A: 320-400nm) and UVB (ultraviolet-B: 280-320 nm) irradiation on the calf thymus DNA in aqueous solution. After both UVA and UVB irradiation for 1h or 3h, the damage to the conformation of DNA was moderate, but the reduction of the B-form DNA component was obvious. Both UVA and UVB caused significant damage to the deoxyribose moiety and bases, among which the pyrimidine base pairs were more seriously affected. There appeared to be preferential damaging sites on DNA molecules caused by UVA and UVB irradiation. UVA irradiation caused more damage to the deoxyribose than UVB irradiation, while UVB irradiation caused more significant damage to the pyrimidine moiety than UVA irradiation. After UVB irradiation for 3h, unstacking of the AT base pairs and the cytosine ring took place, severe damage to the thymine moiety occurred, and some base pairs were modified. Moreover, with either UVA or UVB irradiation for 3h,the photoreactivation of DNA occurred. The damage to the DNA caused by UVB was immediate, while the damage caused by UVA was proportional to the irradiation duration. The experimental results partly indicate the formation of some cyclobutane pyrimidine dimers and (6-4) photoproducts.  相似文献   

16.
拉曼光谱作为分子振动光谱,具有无损、无需试剂染色和快速方便的特点,在生物学领域的应用越来越广泛。拉曼镊子是光镊与拉曼光谱的结合,应用拉曼镊子技术收集单个红菇担孢子的拉曼光谱,分析单个担孢子的主要成分,不同的储存方法对担孢子成分的影响等。结果发现,单个担孢子的拉曼光谱反映了担孢子内含物的基本组成,红菇担孢子的孢内主要成分是脂类物质;不同种类的红菇担孢子的拉曼光谱基本相同,经过多年保存的孢子仍然保持其孢子内的主要成分不变。各随机选择10个担孢子的拉曼光谱进行主成分(PCA)判别分析,结果显示红菇属内不同种类的孢子无法区分。结果表明单孢子拉曼光谱可以应用于分析孢子内成分的变化,但应用于真菌分类的可能性有待进一步探索。  相似文献   

17.
The ability of DNA to bind polycation yielding polyplexes is widely used in nonviral gene delivery. The aim of the present study was to evaluate the DNA compaction with a new DNA vector using Raman spectroscopy. The polyplexes result from an association of a beta-cyclodextrin polymer (polybeta-CD), an amphiphilic cationic connector (DC-Chol or adamantane derivative Ada2), and DNA. The charge of the polymeric vector is effectively controlled by simple addition of cationic connector in the medium. We used surface enhanced Raman spectroscopy (SERS) to characterize this ternary complex, monitoring the accessibility of adenyl residues to silver colloids. The first experiments were performed using model systems based on polyA (polyadenosine monophosphate) well characterized by SERS. This model was then extended to plasmid DNA to study polybeta-CD/Ada2/DNA and polybeta-CD/DC-Chol/DNA polyplexes. The SERS spectra show a decrease of signal intensity when the vector/DNA charge ratio (Z+/-) increases. At the highest ratio (Z+/- = 10) the signal is 6-fold and 3-fold less intense than the DNA reference signal for Ada2 and DC-Chol polyplexes, respectively. Thus adenyl residues have a reduced accessibility as DNA is bound to the vector. Moreover, the SERS intensity variations are in agreement with gel electrophoresis and zeta potential experiments on the same systems. The overall study clearly demonstrates that the cationic charges neutralizing the negative charges of DNA result in the formation of stable polyplexes. In vitro transfection efficiency of those DNA vectors are also presented and compared to the classical DC-Chol lipoplexes (DC-Chol/DNA). The results show an increase of the transfection efficiency 2-fold higher with our vector based on polybeta-CD.  相似文献   

18.
为了研究激光照射后角膜蛋白质化学组成的改变,探讨激光角膜损伤的发生机制,将日本大耳白兔随机分为正常对照组和激光损伤组,选取角膜上皮层和基质层作为研究对象,通过傅里叶变换红外光谱技术(Fou-rier transform infrared spectroscopy,FT-IR)对角膜组织酰胺I带中蛋白质二级结构各吸收峰进行定量分析,观察激光照射后蛋白质分子结构的改变情况。结果显示,激光照射后出现蛋白质二级结构吸收峰的位移和积分百分比的改变。激光照射可使角膜上皮层和基质层蛋白质构象发生改变,从而导致蛋白质结构稳定性下降和蛋白质生物功能的破坏。  相似文献   

19.
Non-canonical forms of DNA are attracting increasing interest for applications in nanotechnology. It is frequently convenient to characterize DNA molecules using a label-free approach such as ultraviolet absorption spectroscopy. In this paper we present the results of our investigation into the use of this technique to probe the folding of quadruplex and triplex nanoswitches. We confirmed that four G-quartets were necessary for folding at sub-mM concentrations of potassium and found that the wrong choice of sequence for the linker between G-tracts could dramatically disrupt folding, presumably due to the presence of kinetic traps in the folding landscape. In the case of the triplex nanoswitch we examined, we found that the UV spectrum showed a small change in absorbance when a triplex was formed. We anticipate that our results will be of interest to researchers seeking to design DNA nanoswitches based on quadruplexes and triplexes.  相似文献   

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