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1.
Gábelová A Valovicová Z Lábaj J Bacová G Binková B Farmer PB 《Mutation research》2007,620(1-2):135-144
The free radical generating activity of airborne particulate matter (PM10) has been proposed as a primary mechanism in biological activity of ambient air pollution. In an effort to determine the impact of the complex mixtures of extractable organic matter (EOM) from airborne particles on oxidative damage to DNA, the level of 8-oxo-2′-deoxyguanosine (8-oxodG), the most prevalent and stable oxidative lesion, was measured in the human metabolically competent cell line Hep G2. Cultured cells were exposed to equivalent EOM concentrations (5–150 μg/ml) and oxidative DNA damage was analyzed using a modified single cell gel electrophoresis (SCGE), which involves the incubation of whole cell DNA with repair specific DNA endonuclease, which cleaves oxidized DNA at the sites of 8-oxodG. EOMs were extracted from PM10 collected daily (24 h intervals) in three European cities: Prague (Czech Republic, two monitoring sites, Libuš and Smíchov), Košice (Slovak Republic) and Sofia (Bulgaria) during 3-month sampling periods in the winter and summer seasons. No substantial time- and dose-dependent increase of oxidative DNA lesions was detected in EOM-treated cells with the exception of the EOM collected at the monitoring site Košice, summer sampling. In this case, 2 h cell exposure to EOM resulted in a slight but significant increase of oxidative DNA damage at three from total of six concentrations. The mean 8-oxodG values at these concentrations ranged from 15.3 to 26.1 per 106 nucleotides with a value 3.5 per 106 nucleotides in untreated cells. B[a]P, the positive control, induced a variable but insignificant increase of oxidative DNA damage in Hep G2 cell (approximately 1.6-fold increase over control value).
Based on these data we believe that EOM samples extracted from airborne particle PM10 play probably only a marginal role in oxidative stress generation and oxidative lesion formation to DNA. However, adsorbed organic compounds can undergo various interactions (additive or synergistic) with other PM components or physical factors (UV-A radiation) and in this way they might enhance/multiply the adverse health effects of air pollution. 相似文献
2.
Marc Nishimoto William T. Roubal John E. Stein Usha Varanasi 《Chemico-biological interactions》1991,80(3)
Juvenile English sole were exposed intramuscularly to nitrofurantoin (NF) and the levels of 8-hydroxy-2′deoxyguanosine (8-OH-dG) in liver, kidney and blood were determined using reversed-phase HPLC with electrochemical detection. Identification and quantitation of the 8-OH-dG in the samples was accomplished by comparison with standard 8-OH-dG, which was characterized by UV spectroscopy and fast-atom bombardment mass spectrometry. The levels of hepatic 8-OH-dG increased (r2 = 0.59, P = 0.015) with the dose of NF (0.10 – 10 mg NF/kg fish). In kidney and blood, however, the levels of 8-OH-dG were significantly higher than controls only at the highest dose tested. The level of binding in liver ranged from 0.37 to 0.76 fmol 8-OH-dG/μg DNA. The levels of hepatic 8-OH-dG reached a maximum (approx. 1 fmol 8-OH-dG/μg DNA) between 1 and 3 days after exposure, followed by a decrease to control levels (approx. 0.25 fmol 8-OH-dG/μg DNA) at 5 days post-exposure. These data demonstrate the first direct evidence for the formation of oxidized DNA bases resulting from the metabolism of a nitroaromatic compound by fish. 相似文献
3.
Singh R Kaur B Kalina I Popov TA Georgieva T Garte S Binkova B Sram RJ Taioli E Farmer PB 《Mutation research》2007,620(1-2):71-82
Epidemiological studies conducted in metropolitan areas have demonstrated that exposure to environmental air pollution is associated with increases in mortality. Carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) are the major source of genotoxic activities of organic mixtures associated with respirable particulate matter, which is a constituent of environmental air pollution. In this study,we wanted to evaluate the relationship between exposure to these genotoxic compounds present in the air and endogenous oxidative DNA damage in three different human populations exposed to varying levels of environmental air pollution. As measures of oxidative DNA damage we have determined 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) by liquid chromatography–tandem mass spectrometry (LC–MS/MS) and cyclic pyrimidopurinone N-1,N2 malondialdehyde-2′-deoxyguanosine (M1dG) by the immunoslot blot assay from lymphocyte DNA of participating individuals. The level of endogenous oxidative DNA damage was significantly increased in individuals exposed to environmental air pollution compared to unexposed individuals from Kosice (8-oxodG adducts) and Sofia (M1dG adducts). However, there was no significant difference in the level of endogenous oxidative DNA and exposure to environmental air pollution in individuals from Prague (8-oxodG and M1dG adducts) and Kosice (M1dG adducts). The average level of M1dG adducts was significantly lower in unexposed and exposed individuals from Kosice compared to those from Prague and Sofia. The average level of 8-oxodG adducts was significantly higher in unexposed and exposed individuals from Kosice compared to those from Prague. A significant increasing trend according to the interaction of c-PAHs exposure and smoking status was observed in levels of 8-oxodG adducts in individuals from Kosice. However, no other relationship was observed for M1dG and 8-oxodG adduct levels with regard to the smoking status and c-PAH exposure status of the individuals. The conclusion that can be made from this study is that environmental air pollution may alter the endogenous oxidative DNA damage levels in humans but the effect appears to be related to the country where the individuals reside. Genetic polymorphisms of the genes involved in metabolism and detoxification and also differences in the DNA repair capacity and antioxidant status of the individuals could be possible explanations for the variation observed in the level of endogenous oxidative DNA damage for the different populations. 相似文献
4.
空气中的细颗粒物(PM2.5)是我国城市空气污染的主要污染物之一,严重威胁着城市居民的健康,限制城市发展的可持续性。PM2.5去除的自然途径有两种,分别是干沉降和湿沉降,其中干沉降占据主导作用,且干沉降的过程和效率与城市森林紧密关联。目前针对城市森林对干沉降作用的研究主要是在小尺度中从不同树种、不同群落结构、不同景观类型等角度来估算并比较其滞尘量,较少关注其占空气污染总量的比率,从而可能影响对城市森林滞尘服务能力的判断。因此,利用城市森林效益(Urban Forest Effect, UFORE)模型中的大气污染干沉降模块的核心算法,以2015年为例,估算了我国主要城市辖区的城市森林一年内对大气中的PM2.5削减量以及其占空气中PM2.5污染总量的比重。结果显示:(1)2015年全国主要城市单位绿地面积日均滞尘量较高地区主要集中在华北地区、华东地区、以及东北地区。其中北京30.47mg/m2,苏州24.63mg/m2,沈阳28.55mg/m2 相似文献
5.
随着我国城市的快速发展,城市的区域性大气污染问题日益突出,尤其是大城市和超大城市的污染问题更加严重。那么城市规模的扩大是否必然导致空气污染的加剧?控制城市人口规模是否是防治空气污染的有效手段?这些问题成为空气污染防治中政府、公众和学者广泛关注的焦点。采用2013年冬季全国114个重点城市两种典型大气污染物-NO_2(传统)和PM_(2.5)(新型)-浓度的实时监测数据,首先分析了这两种大气污染物的空间分布特征,进而定量分析城市人口规模和大气污染物浓度的关系。结果显示:(1)仅有21%的城市NO_2浓度达到WHO的城市年均浓度标准(40μg/m~3),全部城市的PM_(2.5)浓度高于WHO年均浓度标准(10μg/m~3);(2)大气污染物的空间分布具有显著的集聚特征和区域性特征,表现为:NO_2呈较为分散的空间分布,而PM_(2.5)的空间分布呈现"北高南低、内陆高沿海低"的特征。NO_2浓度高的区域主要分布在天津、河北东南部和山东中部地区,PM_(2.5)浓度高的区域主要分布于河北西南部和山东西部;(3)常住人口规模同冬季NO_2和PM_(2.5)浓度呈倒"U"型关系;在1000到1200万的城市冬季平均NO_2和PM_(2.5)浓度最高(NO_2:69.28μg/m~3,PM_(2.5):119.58μg/m~3)。(4)总人口低于1200万的城市,冬季NO_2浓度和PM_(2.5)浓度随着城市规模增加而显著升高(NO_2:r=0.44,P0.01;PM_(2.5):r=0.43,P0.01);总人口高于1200万的城市,NO_2浓度同城市规模呈显著负相关关系(r=0.91,P0.05),PM_(2.5)浓度随城市规模增加逐渐降低。(5)常住人口密度在1000人/km~2以下的重点城市,NO_2和PM_(2.5)浓度同城市人口密度呈显著正相关关系(NO_2:r=0.23,P0.05;PM_(2.5):r=0.36,P0.01)。常住人口密度在1000人/km~2以上的城市人口密度同NO_2和PM_(2.5)浓度呈显著负相关关系(NO_2:r=-0.61,P0.05;PM_(2.5):r=0.63,P0.01)。以上研究结果可以为划定不同大气污染物的重点防治区域和制定联合防治行动计划提供理论依据,并为重点城市大气污染治理和城市人口规模控制理论完善提供参考。 相似文献
6.
近40年来,中国快速经济发展引发较为严重的大气污染,PM2.5是一种重要的空气污染物,掌握其时空分布规律是对其进行防治的重要前提。基于遥感反演出的PM2.5浓度数据集,研究了中国2000-2015年PM2.5浓度的时空分布特征,并基于界定的1376个城镇城区及对应乡村的边界分析了每年PM2.5浓度值的城乡差异,用线性趋势分析法计算城镇PM2.5浓度的年际变化速率及显著性。结果表明,研究期内,PM2.5浓度高于35 μg/m3的面积比例由18.58%增加至32.03%,低于15 μg/m3的面积从43.92%减少到25.12%。PM2.5污染最严重的地区分布在塔里木盆地、河北南部、河南北部和山东西部。从2000年到2015年,中国绝大多数城镇PM2.5浓度显著增加,尤其是在东北平原、太行山以东的河北省西南部、燕山以南的北京天津及河北唐山、鲁中南山地丘陵及周围平原地区、华北平原江苏省北部。PM2.5城乡差异在河北省、山西省两条东北-西南向S形条带区域、浙江省-福建省条带及天山北部绿洲区域较大。研究对PM2.5高浓度区域、PM2.5浓度增长较快区域以及城区PM2.5浓度对乡村影响较大区域进行图示,为中国进一步控制雾霾污染提供一定科学依据。 相似文献
7.
北京市PM2.5化学组分特征 总被引:1,自引:0,他引:1
对2012年8月至2013年7月期间北京市定陵、车公庄、房山和榆垡4个站点的15种PM_(2.5)化学组分进行分析,探讨各组分的时空分布特征以及有机碳(OC)、元素碳(EC)的污染特征。结果表明,4个站点PM_(2.5)组分中OC、SO_4~(2-)、NO_3~-和NH_4~+的含量较高,年均浓度分别为(22.62±21.86)、(19.39±21.06)、(18.89±19.82)、(13.20±12.80)μg/m3。各组分浓度在时间分布上多为冬季最高,夏季最低;在空间分布上多为南部高,北部低;另外NH+4浓度水平明显高于早年间的监测结果。受燃煤的影响,冬季OC和EC平均浓度分别为夏季浓度的3倍和2.5倍。春、夏、秋、冬季4个站点平均OC/EC比值分别为4.9、7.0、8.1和8.4,表明北京市全年均存在较严重的SOC污染。采用OC/EC比值法估算得出全年定陵、车公庄、房山和榆垡站二次有机碳(SOC)占OC的比例分别为57.7%、60.0%、45.6%和57.6%。定陵、车公庄、房山和榆垡站年均[NO_3~-]/[SO_4~(2-)]比值分别为1.01、1.25、1.08和1.12,表明目前北京市排放源表现出固定源和移动源并重的特征。 相似文献
8.
Yingmei Zhang Yejing Wang Runliu Yu Sheng Zhang Zhenbin Wu 《Frontiers of Biology in China》2008,3(1):50-54
The effects of heavy metals Cd2+, Pb2+ and Zn2+ at 0.05, 0.5 and 5.0 mg/L level and their interactions at 0.5 mg/L level on DNA damage in hepatopancreas of loach Misgurnus anguillicaudatus for 1–35 days exposure were examined by single cell gel electrophoresis (SCGE). For each test group, 20 loaches with similar
body size (5.17–7.99 g; 11.79–13.21 cm) were selected and kept in aquaria with dechlorinated water at (22±1)°C and fed a commercial
diet every 48 h. According to the percentage of damaged DNA with tail and its TL/D (tail length to diameter of nucleus) value,
the relationship between DNA damage degree and heavy metal dose and exposure time was determined. Results showed that the
percentage of damaged DNA and the TL/D value were increased with the prolonged exposure time. The highest percentage (84.85%)
of damaged DNA was shown in 5.0 mg/L Zn2+ group after 28 days exposure and the biggest TL/D value (2.50) in all treated groups after 35 days exposure. During the first
treated week, the damnification of DNA was mainly recognized as the first level, after that time, the third damaged level
was mostly observed and the percentage of damaged DNA was beyond 80%. The joint toxic effects among Cd2+, Pb2+ or Zn2+ revealed much complexity, but it generally displayed that the presence of Cd2+ could enhance the genotoxicity of Pb2+ or Zn2+. In conclusion, the results suggested that there was a significant time-and dose-depended relationship between the heavy
metal and DNA damage in hepatopancreas of loach, and SCGE could represent a useful means to evaluate the genotoxicity of environmental
contamination on aquatic organisms.
__________
Translated from Acta Hydrobiologica Sinica, 2006, 30(4): 399–403 [译自: 水生生物学报] 相似文献
9.
Ultraviolet radiation is one of the most deleterious forms of radiation to terrestrial organisms and is involved in formation of mutagenic pyrimidine dimers and oxidized nucleotides. The biflavonoid fraction (BFF), extracted from needles of Araucaria angustifolia was capable of protecting calf thymus DNA from damage induced by UV radiation. This occurred through prevention of cyclobutane thymine dimer and 8-oxo-7,8-dihydro-2′-deoxyguanosine formation, this being quantified by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) in a multiple reaction monitoring mode (MRM) and by HPLC-coulometric detection, respectively. 相似文献
10.
Alena Gbelov Zuzana Valovi
ov Gabriela Ba
ov Juraj Lbaj Blanka Binkov Jan Topinka Oksana Sevastyanova Radim J. rm Ivan Kalina Viera Habalov Todor A. Popov Teodor Panev Peter B. Farmer 《Mutation research》2007,620(1-2):103
Sensitivity and correlations among three endpoints were evaluated to assess the genotoxic potential of organic complex mixtures in vitro. This study was focused on DNA adduct formation, DNA single strand break induction and tumour suppressor p53 protein up-regulation produced by extractable organic matter (EOM) absorbed on respirable particulate matter PM10 (particulate matter < 10 μm) collected in three European cities (Prague, Sofia, Košice) during winter and summer period. To compare the sensitivity of particular endpoints for in vitro measurement of complex mixture genotoxicity, the metabolically competent human hepatoma cell line Hep G2 was treated with equivalent EOM concentration of 50 μg/ml. Cell exposure to EOMs resulted in significant DNA adduct formation and DNA strand break induction, however, a lack of protein p53 up-regulation over the steady-state level was found. While the maximum of DNA strand breaks was determined after 2 h cell exposure to EOMs, 24 h treatment interval was optimal for DNA adduct determination.No substantial location- and season-related differences in EOM genotoxicity were detected using DNA strand break assessment. In agreement with these results no significant variation in DNA adduct levels were found in relation to the locality and season except for the monitoring site in Prague. The Prague EOM sample collected during summer period produced nearly three-fold lower DNA adduct level in comparison to the winter EOM sample.Comparable results were obtained when the ambient air genotoxicity, based on the concentration of carcinogenic PAHs in cubic meter of air (ng c-PAHs/m3), was elicited using either DNA adduct or strand break determination. In general, at least six-fold higher genotoxicity of the winter air in comparison to the summer air was estimated by each particular endpoint. Moreover, the genotoxic potential of winter air revealed by DNA adduct assessment and DNA strand break measurement increased in the same order: Košice Prague < Sofia.Based on these data we suppose that two endpoints DNA breakage and DNA adduction are sensitive in vitro biomarkers for estimation of genotoxic activity of organic complex mixture associated with airborne particles. On the other hand, the measurement of protein p53 up-regulation manifested some limitations; therefore it cannot be used as a reliable endpoint for in vitro genotoxicity assessment. 相似文献
11.
Timothy England Emily Beatty Almas Rehman Jaffar Nourooz-Zadeh Paulo Pereira James O'Reilly 《Free radical research》2013,47(4):355-362
Oxidative damage to DNA in human tissues can be determined by measuring multiple products of oxidative damage to the purine and pyrimidine bases using gas chromatography-mass spectrometry (GC-MS). Oxidative damage to lipids (lipid peroxidation) can be quantitated by the mass spectrometry-based determination of F2-isoprostanes, specific end-products of the peroxidation of arachidonic acid residues in lipids. For both DNA base damage products and 8-epi prostaglandin F2α (PGF2α), there is a wide variation in levels between different healthy human subjects. We measured multiple products of oxidative damage to DNA bases in white cells, and 8-epi PGF2α in plasma, from blood samples obtained from healthy human subjects in the UK and in Portugal. No correlation of 8-epi PGF2α levels with levels of any modified DNA base (including 8-hydroxyguanine) was observed. We conclude that no single parameter can be measured as an index of “oxidative stress” or “oxidative damage” in vivo. 相似文献
12.
Alexandros Tselepis Paschalis-Thomas Doulias Evaggelia Lourida Georgios Glantzounis Evangelos Tsimoyiannis Dimitrios Galaris 《Free radical biology & medicine》2001,30(12)
Trimetazidine is a well-established anti-ischemic drug, which has been used for long time in the treatment of pathological conditions related with the generation of reactive oxygen species. However, although extensively studied, its molecular mode of action remains largely unknown. In the present study, the ability of trimetazidine to protect low-density lipoproteins (LDL) from oxidation and cultured cells from H2O2-induced DNA damage was investigated. Trimetazidine, tested at concentrations 0.02 to 2.20 mM, was shown to offer significant protection to LDL exposed to three different oxidizing systems, namely copper, Fe/ascorbate, and met-myoglobin/H2O2. The oxidizability of LDL was estimated by measuring, (i) the lag period, (ii) the maximal rate of conjugated diene formation, (iii) the total amount of conjugated dienes formed, (iv) the electrophoretic migration of LDL protein in agarose gels (REM), and (v) the inactivation of the enzyme PAF-acetylhydrolase present in LDL. In addition, the presence of trimetazidine decreased considerably the DNA damage in H2O2-exposed Jurkat cells in culture. H2O2 was continuously generated by the action of glucose oxidase at a rate of 11.8 ± 1.5 μM per min (60 ng enzyme per 100 μl), and DNA damage was assessed by the single cell gel electrophoresis assay (also called comet assay). The protection offered by trimetazidine in this system (about 30% at best) was transient, indicating modification of this agent during its action. These results indicate that trimetazidine can modulate the action of oxidizing agents in different systems. Although its mode of action is not clarified, the possibility that it acts as a lipid barrier permeable transition metal chelator is considered. 相似文献
13.
Reactive oxygen species have been implicated in aerobic organisms as causative agents in damage to DNA, proteins, and lipids. Catalase is a major enzyme in the defense against such oxidant damage. To determine whether increased catalase expression confers greater resistance to oxidant stress, a eukaryotic expression vector harboring a human catalase cDNA clone was constructed. Acatalasemic murine fibroblasts were then co-transfected with the catalase expression vector and pSV2-neo, and successfully transfected cells were identified by their ability to grow in the presence of geneticin. Clones that contained integrated copies of the catalase expression vector were identified by Polymerase Chain Reaction (PCR) analysis. Stably transfected geneticin-resistant cell lines that overexpressed catalase in potentially positive cell lines were confirmed by catalase enzyme assays. To examine the physiological relevance of catalase overexpression, cells were exposed to oxidant stresses (hydrogen peroxide and hyperoxia), and survival rates were determined. Results demonstrated a significant resistance to oxidative stress in cells overexpressing catalase when compared to controls. These transfected cell lines will provide important models for further evaluation of the role of catalase in protecting cells against the toxic effects of oxygen-derived free radicals and their derivatives. 相似文献
14.
Three group 10 complexes containing nido-carborane diphosphine, [NiCl(PPh3){7,8-(PPh2)2-7,8-C2B9H10}] (1), [PdCl(PPh3){7,8-(PPh2)2-7,8-C2B9H10}] · 1.25CH2Cl2 (2) and [PtCl(PPh3){7,8-(PPh2)2-7,8-C2B9H10}] · 2.5CH2Cl2 (3) have been synthesized by the reactions of [M(PPh3)2Cl2] (M = Ni, Pd, Pt) with closo carborane diphosphine 1,2-(PPh2)2-1,2-C2B10H10 in ethanol. For complex 3, it could also be obtained under solvothermal condition. All three complexes were characterized by elemental analysis, FT-IR, 1H and 13C NMR spectroscopy and X-ray structure determination. Single crystal structures show that their structures are similar to each other. In each complex, the nido [7,8-(PPh2)2-7,8-C2B9H10]−, which resulted from the degradation of the initial closo ligand 1,2-(PPh2)2-1,2-C2B10H10 during the reaction process, was coordinated bidentately through the P atoms to M(II) ion, and this resulted in a stable five-membered chelating ring between the bis-diphosphine ligand and the metal. The coordination mode of the metal can be described as a slightly distorted square-planar, in which the remaining two positions were occupied by one Cl− and one PPh3 group. 相似文献
15.
Mary N. Mohankumar S. Janani B. Karthikeya Prabhu P. R. Vivek Kumar R. K. Jeevanram 《Mutation Research - Genetic Toxicology and Environmental Mutagenesis》2002,520(1-2):179-187
DNA damage was assessed in smoker lymphocytes by subjecting them to the single cell gel electrophoresis (SCGE) assay. In addition to the appearance of comet tails, smoker cells exhibited enlarged nuclei when analysed by the comet assay. On comparing basal DNA damage among smokers and a non-smoking control group, smoker lymphocytes showed higher basal DNA damage (smokers, 36.25±8.45 μm; non-smokers, 21.6±2.06 μm). A significant difference in DNA migration lengths was observed between the two groups at 10 min after UV exposure (smokers, 65.5±20.34 μm; non-smokers, 79.2±11.59 μm), but no significant differences were seen at 30 min after UV exposure (smokers, 21.13±10.73 μm; non-smokers, (27.2±4.13 μm). The study thus implies that cigarette smoking perhaps interferes with the incision steps of the nucleotide excision repair (NER) process. There appeared be no correlation between the frequency of smoking and DNA damage or the capacity of the cells to repair UV-induced DNA damage that suggests inherited host factors may be responsible for the inter-individual differences in DNA repair capacities. The study also suggests monitoring NER following UV insult using the SCGE assay is a sensitive and simple method to assess DNA damage and integrity of DNA repair in human cells exposed to chemical mutagens. 相似文献
16.
Junjie Hu Wenbing Zhang Huimin Ma Yunmei Cai Guoying Sheng Jiamo Fu 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2010,878(28):2765-2769
8-Hydroxy-2′-deoxyguanosine (8-OHdG) and 5-methyl-2′-deoxycytidine (5-mdC) are utilized as useful biomarkers not only for early diagnosis but also for the detection and assessment of high-risk individuals. In the present study, a sensitive and specific method was developed for simultaneous determination of 8-OHdG and 5-mdC in DNA by high performance liquid chromatography/positive electrospray ionization tandem mass spectrometry. The limits of quantification for 8-OHdG and 5-mdC were 80 and 40 pg/ml, respectively. The calibration curves of 8-OHdG and 5-mdC were linear over the concentration range of 0.02–100 ng/ml and the correlation coefficients were higher than 0.9990. The intra-day and inter-day relative standard derivative values were in the range of 0.70–7.47% for 8-OHdG and 1.07–7.06% for 5-mdC, respectively. The recoveries were 93.4–108.5% for 8-OHdG and 87.4–104.9% for 5-mdC, respectively. This method was validated by determination of the background levels of 8-OHdG and 5-mdC in calf thymus DNA, and satisfactory results were obtained. 相似文献
17.
Alberto Izzotti Cristina Cartiglia Maurizio Taningher Silvio De Flora Roumen Balansky 《Mutation Research - Genetic Toxicology and Environmental Mutagenesis》1999,446(2):751
Experimental data suggest a possible role of DNA damage in aging, mainly related to oxidative lesions. With the objective of evaluating DNA lesions as molecular biomarkers of aging, we measured 8-hydroxy-2′-deoxyguanosine (8-OH-dG) and DNA–protein crosslinks (DPXL) levels in different organs of mice aged 12 and 24 months. 8-OH-dG was detected by 32P postlabelling after removing unmodified dG by trifluoracetic acid, which prevented the artificial formation of 8-OH-dG during 32P labelling procedures. Appreciable 8-OH-dG amounts were detected in 12-month-old mice in liver (1.8±0.7 8-OH-dG/105 normal nucleotides), brain (1.6±0.5) and heart (2.3±0.5). In 24-month-old mice these values were higher in all examined organs (liver, 2.7±0.4; brain, 3.6±1.1; heart, 6.8±2.2 8-OH-dG/105 normal nucleotides). This accounted for a 1.5-fold increase in liver (not significant), 2.3-fold increase in brain (P<0.01), and 3.0-fold increase in heart (P<0.001). A similar trend was observed for DPXL levels, which were the 1.8±0.3%, 1.2±0.2%, and 2.2±0.3% of total DNA in liver, brain, and heart of 12-month-old mice and 1.9±0.4%, 2.0±0.4%, and 3.4±0.5% in 24-month-old mice, with ratios of 1.0, 1.7 (P<0.01), and 1.5 (P<0.001), respectively. Highly significant correlations between 8-OH-dG and DPXL levels were recorded in brain (r=0.619, P<0.001) and heart (r=0.800, P<0.0001), but not in liver (r=0.201, not significant). These data suggest that brain and heart are more severely affected by the monitored age-related DNA lesions than liver, which can be ascribed to certain characteristics of these postmitotic organs, including the low detoxifying capacities, the high oxygen consumption, and the impossibility to replace damaged cells by mitosis. The strong correlation between 8-OH-dG and DPXL supports a possible contribution of oxidative mechanisms to formation of DPXL in those organs, such as brain and heart, which play a primary role in the aging of the whole organism. 相似文献
18.
Tunicamycin, an inhibitor of the asparagine-linked protein N-glycosylation, blocks the initiation of DNA synthesis in Swiss 3T3 cells stimulated by prostaglandin F2α alone or with insulin. This effect is exerted only when tunicamycin is added from 0 to 8 h after stimulation and it decreases the rate of entry into S phase. Blocking of labeled sugar incorporation to proteins occurs regardless of the time of PGF2α stimulation. In contrast tunicamicin does not inhibit protein synthesis. These results suggest that N-glycoprotein synthesis early during the prereplicative phase is an important event controlling the mitogenic action of PGF2α 相似文献
19.
Jin-Huan Su Jian-He Xu Hui-Lei Yu Yu-Cai He Wen-Ya Lu Guo-Qiang Lin 《Journal of Molecular Catalysis .B, Enzymatic》2009,57(1-4):278-283
A novel β-glucosidase from Fusarium proliferatum ECU2042 (FPG) was successfully purified to homogeneity with a 506-fold increase in specific activity. The molecular mass of the native purified enzyme (FPG) was estimated to be approximately 78.7 kDa, with two homogeneous subunits of 39.1 kDa, and the pI of this enzyme was 4.4, as measured by two-dimensional electrophoresis. The optimal activities of FPG occurred at pH 5.0 and 50 °C, respectively. The enzyme was stable at pH 4.0–6.5 and temperatures below 60 °C, and the deactivation energy (Ed) for FPG was 88.6 kJ mo1−1. Moreover, it was interesting to find that although the purified enzyme exhibited a very low activity towards p-nitrophenyl β-d-glucoside (pNPG), and almost no activity towards cellobiose, a relatively high activity was observed on ginsenoside Rg3. The enzyme hydrolyzed the 3-C, β-(1 → 2)-glucoside of ginsenoside Rg3 to produce ginsenoside Rh2, but did not sequentially hydrolyze the β-d-glucosidic bond of Rh2. The Km and Vmax values of FPG for ginsenoside Rg3 were 2.37 mM and 0.568 μmol (h mg protein)−1, respectively. In addition, this enzyme also exhibited significant activities towards various alkyl glucosides, aryl glucosides and several natural glycosides. 相似文献
20.
The voltage-dependent calcium channel (VDCC) in skeletal muscle probably plays a key role in transducing membrane charge movement to the calcium release channel. We report here that the expression of VDCC α1 and α2 mRNAs is developmentally regulated in differentiating C2Cl2 myogenic cells. The α1 mRNA is not detectable in the myoblast form of C2Cl2 cells while its expression is induced 20-fold in differentiated myotubes. In contrast, the α2 mRNA is weakly expressed in myoblasts but is also induced upon myogenic differentiation. 相似文献