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1.
观察了亚硒酸钠(Na2SeO3)在体外作用于大鼠晶状体上皮细胞(RLEcells)而造成的DNA单链断裂(singlestrandbreaks,SSB),并对其DNA损伤、修复动力学做了初步研究.发现SSB严重程度与亚硒酸钠的浓度呈线性相关,其SSB重接修复约在30~60min内完成.还作了有关非程序DNA合成(UDS)的检测,发现与SSB相比,UDS发生迟且持续时间更长,提示Na2SeO3可能在体外对大鼠晶状体上皮细胞除造成SSB以外,还可能造成其它种类的DNA损伤.  相似文献   

2.
构建了pCHBSSIG质料,其特点是CMV立即早期启动子调控乙型肝炎(乙肝)表面抗原S+前S1融合基因在前,SV40早期启动子调控GS扩增基因在后,此质粒转化到CHO-dhfr^-细胞中,经克隆加MSX及MTX筛选、扩增,建立了7个高效表达乙肝表达抗原S及前S1融合蛋白细胞系GdSS1,并检测了其中GdSS1-18细胞系的生物学特性,结果表明:未发现微生物污染,无致瘤性、遗传稳定,电镜下可观察到2  相似文献   

3.
植物自交不亲和分子机理研究的一些进展   总被引:10,自引:0,他引:10  
综述了植物孢子体自交不亲和(SSI)与配子体不亲和(GSI)分子机理研究的一些进展。SLG和SRK基因编码的SLG和SRK蛋白在SSI中起着关键作用,而S基因编码的S蛋白(RNase)在GSI中起着重要作用。禾本科植物的GSI是受双位点S和Z基因控制的,文中也作了简要介绍。  相似文献   

4.
本研究采用了免疫细胞化学方法,首次系统观察了22例9—27周引产人胎儿下丘脑视上区的视上核和视交叉上核内的生长抑素免疫反应神经元(Somatostatinimmunoreactiveneuron,简称SOM-IR神经元)的发生、发育的形态学特征。从16周开始,在视上核(SupraopticalnucleusSON)和交叉上核(SuprachiasmatienucleusSON)内可观察到SOM-IR神经元,在SON、SOM-IR神经元数随着胎龄增加而增多,到22周时数量最多,以后随着胎龄增加SOM-IR神经元数出现逐渐减少现象;SCN内的SOM-IR神经元在18周和22周时出现两次高峰,研究结果提示,SON和SCN内的SOM-IR神经元在胚胎发育过程中出现消长现象,表明了SOM-IR神经元在SON和SCN内各有其独特的发育过程。  相似文献   

5.
马铃薯GBSS基因5′侧翼区调控作用的研究   总被引:2,自引:0,他引:2  
将0.4、0.8、1.6、2.9kbGBSS基因的5′侧翼区与GUS基因融合,构建了双元表达载体。0.8kbGBSSGUS通过基因枪介导在块茎切片中获得了瞬间表达。以上建构物通过农杆菌介导转入了马铃薯(SolanumtuberosumL.cv.Desiree)。XGluc染色及PCR结果证实已获得转基因植株。利用离体块茎诱导系统,GUS表达用荧光进行定量检测,结果显示,2.9、1.6、0.4kbGBSSGUS的表达均以块茎明显高于茎段,达2~10倍。0.8、1.6、2.9kbGBSSGUS表达高于0.4kbGBSSGUS。蔗糖浓度的升高可诱导GBSSGUS的表达,而光照抑制了GBSSGUS的表达。  相似文献   

6.
亚硒酸钠诱发的晶状体上皮细胞DNA损伤及修复   总被引:3,自引:0,他引:3  
观察了亚硒酸钠(Na2SeO3)在体外作用于大鼠晶状体上皮细胞(RLE cells)而造成的DNA单链断裂(SSB),并对其DNA损伤、修复动力学做了初步研究。发现SSB严重程度与亚硒酸钠的浓度呈线性相关,其SSB重接修复约在30 ̄60min内完成,还作了有关非程序DNA合居(UDS)的检测,发现与SSB相比,UDS发生迟且持续时间更长,提示Na2SeO3可能在体外对大鼠晶状体上皮细胞除造成SSB  相似文献   

7.
生态网络分析是研究生态网络的理论和方法,ASSEN(theAnalysisandsimulationSystemfoEconetworks)是生态网络分析和模拟的软件系统,本文在简述生态网络分析基本方法的基础上,介绍了ASSEN的结构和功能,并利用ASSEN对一个简单水流生态网络进行了分析和模拟。  相似文献   

8.
鄱阳湖湿地环境及其MOS—1MESSR遥感影像分析   总被引:2,自引:0,他引:2  
陈水森  付尔林 《生态科学》1998,17(2):118-120
利用MOS-1MESSR卫星遥感影像,对鄱阳湖湿地环境进行了解译特征分析,通过实地调查,揭示了MESSR影像色调与湿地非温地带性植被之间的关系,为鄱阳湖及其它地区湿地调查提供了范例  相似文献   

9.
人肌肌酸激酶在SDS溶液中失活与构象变化的比较研究   总被引:3,自引:0,他引:3  
应用紫外差吸收光谱、荧光发射光谱、CD先谱等监测手段,研究了SDS溶液滴定人肌肌酸激酶时的构象与活力变化的关系。结果表明酶的活力丧失先于以紫外差吸收先谱、荧先发射谱和巯基暴露数目所监测到的构象变化。SDS滴定时引起的酶的荧光发射光谱的变化在低滴定度阶段随着SDS滴定量的增加,荧光强度下降,发射峰位红移,当SDS浓度达到2.1mmol/L时,荧光强度增大,继续增加SDS滴定量,荧光强度又降低,发射峰位红移直至终态。紫外差吸收光谱随着SDS溶液的加入,281nm.287nm和292nm的负差吸收峰增大。CD光谱结果表明在本实验所用的SDS浓度范围内,SDS对人肌肌酸激酶的二级结构几乎没有影响。上述结果支持了酶的活性部位构象柔性的观点。  相似文献   

10.
应用差别p H 值沉淀蛋白质的原理,建立了水稻条纹病毒病特异蛋白( S P) 的两种提纯方法。这两种方法都可以从病叶中提纯到大量的 S P,其粗提纯量分别为0 .8 和2 .0 mg/g 病叶。通过 S D S P A G E 分离后得到了精提纯的蛋白,其分子量为20 .1 k Da 。将粗提纯和精提纯的 S P 分别免疫兔子,制备出效价为51 200 和6 400 的抗血清。将效价为6 400 的高度特异性的抗血清用于研究 R S V S P 与 R S V C P 及同属的水稻草状矮化病毒( R G S V) S P、 C P 之间的血清学关系,结果表明, R S V S P 的抗血清与 R G S V C P、 R S V C P 之间无反应,但可与 R G S V S P 微弱反应;而 R G S V S P、 C P 及 R S V C P 的抗血清与 R S V S P 之间都无血清学反应。结果证实了 R S V 和 R G S V 之间存在着进化上的亲缘关系  相似文献   

11.
Experiments were conducted on rats during the early postnatal period; a study was made of the membrane potential (MP) establishment of the fibers of the skeletal muscles of the neck, the anterior and the posterior limbs. At birth the most mature were the muscles of the neck, and the least -- the muscles of the posterior limb. Establishment of the stationary MP level in the muscles of the neck occurred during the first week after birth, in the muscles of the anterior limbs -- by the 10th-12th day, and of the posterior limbs -- by the 15th-20th day. The order of maturation of various groups of the skeletal muscles was associated with the peculiarities of the neuro-trophic influences at various age periods. Muscles of the neck were characterized at all the developmental stages by a rhythmic low-frequency electromyographic activity. In the muscles of the limbs the rhythmic electromyographic activity was transformed into the discharge high-frequency activity by the period of termination of increase of the MP of the muscles.  相似文献   

12.
The time course of changes in the hand muscle activity and the grip force before the hit of an object falling from different heights into a cup held between the thumb and the forefinger was analyzed in three variants of the experiment: (1) the subject saw the object falling; (2) the subject did not see the object falling but initiated the fall; and (3) the subject had no information on either the falling or its start. In the third variant, the muscle activity and the grip force changed in response to the object hitting the cup. In the second variant, the muscle activity and the grip force began to change 200–280 ms before the hit, this time being independent of height from which the object fell. In the first variant, the anticipatory changes began 150 ms after the object started falling and did not depend on the height of the falling within the rage 30–50 cm. If the object fell from a height of 70–105 cm, the changes in the muscle activity and the grip force began a fixed time before the object hit the cup, which did not depend on the height from which the object fell. Thus, when the object fall from small heights, the timing of the increase in the grip force was mainly determined by the moment when the object began moving; at large heights, the increase in the grip force was related to the presumed moment of the hit.  相似文献   

13.
Ab initio molecular orbital calculations were made for the various types of structures of the pore of the ion channel and the results were applied to the permeability model by Hille, an extension of the Eyring rate theory. In Hille's model, ion passage through the channel is regarded as a kinetic process. Accordingly, it is thought that the interaction energy between cation and ligand, the easier the passage is, due to the lower activation energy. The calculated interaction energy was in the order Li+ greater than Na+ greater than K+ for all models. The optimum size of the pore determined from the interaction energy depends on the structure of the filter. The size for the pentagon was largest, followed by the hexagon and tetragon. On the other hand, the size depends hardly at all on the kind of ligand molecules. In the case of the tetragon, the sizes for the Na and K channels were nearly the same as those estimated from the model building and inhibitor-blocking experiment. The interaction energy between the ionized carboxyl group and the cation was extremely large, clearly reflecting the experimental fact that the carboxyl group in the pore has an important role in making the passage of the cation through the channel easier by dehydrating the water molecules. By analysis of the interaction energy, it was revealed that the contribution of the electrostatic energy was predominant, although the contributions of the other effects might not be negligible. Among these effects, the value of the charge transfer energy is largest, and this is noteworthy in connection with the selective transmission of cations through the overlap of orbitals. It is concluded that the quantum-chemical indices such as interaction energy and the electronic charge calculated by the sophisticated ab initio method help to shed light on the nature of the pore of the ion channel.  相似文献   

14.
In the first part of the paper, the results of the investigation of the rhodopsin arrestin interaction are presented. The results were mainly obtained with the technique of the selective labelling of the rhodopsin and arrestin SH-groups and the rhodopsin limited proteolysis. These results are discussed in the frame of the latest data on the three-dimensional structure of arrestin. In the second part of the paper, results of the antigenic properties of arrestin (S-antigen) and its role in the pathogenesis of the retina diseases are summarized. The data on the role of the autoimmune processes in the pathogenesis of diabetic retinopathy are presented. We have also described the results of the use of the elaborated technique of the immune diagnostics in the prognosis of the diabetic retinopathy and retinopathy of the premature babies.  相似文献   

15.
纵坑切梢小蠹蛀梢期空间分布   总被引:11,自引:0,他引:11  
在昆明地区,纵坑切梢小蠹(Tomicus piniperda)成虫蛀梢多集中在蛀干木附近。种群密度以蛀干木为中心向周围是指数递减,散布半径约30m。在蛀虹梢过程中,该种群逐渐向新区扩张。在树冠内,纵坑切梢小蠹主要分布在4—10轮枝上。第7轮技虫口百分率最高。6—7轮枝受害率最大。树冠上层受害较其下属于重。从树冠水平层次考察,树冠外层虫量相对集中,约为树冠中、内层虫量之和。树冠内层虫量最少。纵坑切梢小蠹在树冠内的种群分布系由梢径、种群密度、蛀梢行为、降落方式、光照等因素综合影响的结果。  相似文献   

16.
This paper reports a quantitative study of the effect of ring substituents in the 1-position of the aromatic ring on the rate of monophenol hydroxylation and o-diphenol oxidation catalyzed by tyrosinase. A possible correlation between the electron density of the carbon atom supporting the oxygen from the monophenolic hydroxyl group and the V Mmax values for each monophenol was found. In the case of o-diphenols the same effect was observed but the size of the side-chain became very important. NMR studies on the monophenols justified the sequence of the V Mmax values obtained. As regards the o-diphenols, on the other hand, only a fair correlation between NMR and V Dmax values was observed due to the effect of the molecular size of the ring substituent. From these data, it can be concluded that the redox step (k33) is not the rate-determining step of the reaction mechanism. Thus, the monophenols are converted into diphenols, but the order of specificities towards monophenols is different to that of o-diphenols. The rate-limiting step of the monophenolase activity could be the nucleophilic attack (k51) of the oxygen atom of the hydroxyl group on the copper atoms of the active site of the enzyme. This step could also be similar to or have a lower rate of attack than the electrophilic attack (k52) of the oxygen atom of the active site of oxytyrosinase on the C-3 of the monophenolic ring. However, the rate-limiting step in the diphenolase activity of tyrosinase could be related to both the nucleophilic power of the oxygen atom belonging to the hydroxyl group at the carbon atom in the 3-position (k32) and to the size of the substituent side-chain. On the basis of the results obtained, kinetic and structural models describing the monophenolase and diphenolase reaction mechanisms for tyrosinase are proposed.  相似文献   

17.
A study was made of the accumulation of antibodies in the blood serum and the secretions of the respiratory tracts of persons immunized with the living influenza vaccine. The duration of inductive phase and the dynamics of the antibody accumulation in the secretions occurred irrespective of their initial level in the blood sera, this pointing to the autonomic character of the local immunity system. On the other hand the functional condition of the system of local immunity influenced the intensity of the antibody formation in the system of the general immunity. If before the immunization the antibody titre in the secretions were 1:4 and greater, the antibody accumulation in the blood sera took place less intensively. An analogous phenomenon was also observed when the antibodies were absent in the secretions before the immunization, but their formation took place as soon as the first week after it. The mechanism of this peculiar "competition for the antigen" of the systems of local and general immunity consisted in the neutralization of the influenza virus in the area of the porta of infection.  相似文献   

18.
Because of their great abundance and amenability to fully automated genotyping, single-nucleotide polymorphisms (SNPs) and simple insertion/deletion are emerging as a new generation of markers for positional cloning. Although the efficiency and cost associated with the markers are important in the mapping of human disease genes, the power to detect the linkage between the marker and the disease locus, as well as the accuracy of the estimation of the map location of the disease gene, dictate the selection of the markers. Both the power and the accuracy depend not only on the type of the markers but also on other factors, such as the age of the disease mutation, the magnitude of the genetic effect, the marker-allele distribution in the population, mutation rates of marker loci, the frequency of the disease allele, the recombination fraction, and the methods for mapping the human disease genes. In this article, we develop a mathematical framework and the analytical formulas for calculation of the power and the accuracy and investigate the impact that the aforementioned factors have on the power and the accuracy, by using two population-based gene-mapping methods-likelihood-based linkage-disequilibrium mapping and the transmission/disequilibrium test, for both biallelic SNPs and microsatellites. These studies provide not only guidance in selection of the markers and in the design of the sample scheme for positional cloning but also insight into the biological bases of the mapping of human disease genes.  相似文献   

19.
The following conclusions may be drawn from the results in this work. The respiratory cycles are formed by the neuronal machinery in the reticular formation under the posterior part of the vagal motor nucleus. The motor neurones or the neuronal networks composing the motor nucleus of the respiratory muscles tonically discharge the action potentials, when the neurones or the networks are released from the inhibitory influences of the interneurones connecting the neuronal machinery to the motor neurones. Furthermore, the interneurones probably generate the tonic discharges after removing the inhibitory influences of the other interneurones or the neuronal machinery on them. A reflex mouth closing is elicited by a mechanical stimulus applying on the upper lip. The motor neurones of the m. adductor mandibulae are activated via only one synapse in the reflex. The reflex action potentials recorded from the motor nerve reduce in amplitude at the resting phase of the nerve in the respiratory cycles. These results suggest that the respiratory motor neurones are by nature spontaneous generators of the tonic action potentials and, in the time of the normal breathing, the tonic activity is interrupted by an inhibitory influence of the neuronal machinery generating the respiratory cycles.  相似文献   

20.
银杏套细胞发育的解剖学研究   总被引:3,自引:2,他引:1  
银杏套细胞起源于近雄配子体表达的颈卵器母细胞周围细胞,中央细胞形成时,套细胞呈明显的一层,围绕颈卵器紧密排列,随着颈卵器的发育,套细胞体积逐渐地大,细胞质变浓厚,细胞质中脂滴增多,套细胞和中央细胞的接触壁开始出现局部加厚,在颈卵器发育的泡沫化阶段,套细胞和中央细胞的接触壁不均匀加厚较为显著,在较薄的区域可见胞间连丝,受精前,套细胞中液泡增多,脂滴迅速减少,造淀粉体增大,套细胞与卵细胞的接触壁的不均匀加厚非常明显,精核进入颈卵器以后,卵细胞与套细胞的接触壁和卵细胞的质膜之间形成一个薄厚不均的间隔层,受精卵分裂时,受精卵细胞与套细胞接触壁的凹陷处可见许多小泡和内质网,游离核期时,套细胞内出现大量小液泡,细胞内含物迅速消失,套细胞外形变长,胚胎长出颈卵器后,套细胞逐渐解体消失。  相似文献   

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