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1.
高胆固醇血症病人的红细胞膜ATP酶活性变化   总被引:3,自引:0,他引:3  
研究表明高胆固醇血症病人的红细胞膜Na+-K+-ATP酶和Ca2+-Mg2+-ATP酶活性均降低,并且血浆总胆固醇和低密度脂蛋白-胆固醇浓度与这两种酶活性呈高度负相关,而血浆高密度脂蛋白-胆固醇浓度与Na+-K+-ATP酶活性呈正相关。这些变化的研究,对于进一步探讨动脉粥样硬化的发生机制及其防治可能具有重要意义。  相似文献   

2.
为了探讨重金属Cd2+和Cu2+胁迫对泥蚶消化酶活性的影响,运用酶学分析的方法,按《渔业水质标准》(GB 11607)规定的Cd2+、Cu2+最高限量值的1、2、5、10倍设置重金属离子Cd2+、Cu2+浓度及其组合,研究了在重金属Cd2+、Cu2+胁迫下,30d内泥蚶3种消化酶活性的变化规律。结果表明:与空白对照组相比,在重金属Cd2+、Cu2+或其组合的胁迫下,较低浓度组泥蚶的淀粉酶活性实验前期增强(即被诱导),实验后期减弱(即被抑制),较高浓度组泥蚶的淀粉酶活性从实验一开始就减弱,并保持在较低水平,毒性比较,同一重金属高浓度 > 低浓度,不同重金属及其组合Cu2+ > (Cd2++Cu2+)组合 > Cd2+;泥蚶脂肪酶的活性实验前期增强,实验后期转为微减弱或减弱,毒性比较,同一重金属高浓度 > 低浓度,不同重金属及其组合(Cd2++Cu2+)组合 > Cu2+ > Cd2+;泥蚶胃蛋白酶的活性实验前期增强,且活性呈现升高-降低-再升高-再降低的变化,实验后期分别表现微增强、微减弱和减弱,毒性比较,同一重金属高浓度 > 低浓度,不同重金属及其组合(Cd2++Cu2+)组合 > Cu2+ > Cd2+。可见:环境中的Cd2+和Cu2+对泥蚶的消化酶活性起着明显的影响作用。  相似文献   

3.
Ca2+泵(Ca2+-ATPase)是调节细胞内Ca2+浓度的重要蛋白质之一. Ca2+泵在转运Ca2+的过程中经历一系列构象变化. 其中,E1状态为外向的Ca2+高亲和状态,E2状态则为内向的Ca2+低亲和状态. 目前,骨骼肌内质网Ca2+泵转运Ca2+过程中的几个中间状态,包括E1-2Ca2+,E1-ATP,E1-P-ADP,E2-Pi和E2状态的三维晶体结构已经解析. 介绍这几种状态的晶体结构,并分析Ca2+泵在执行功能过程中结构与功能的关系.  相似文献   

4.
苏柳172和垂柳对Cu2+的吸收特性及有机酸影响   总被引:1,自引:0,他引:1       下载免费PDF全文
采用溶液培养的方法,研究了苏柳172和垂柳对Cu2+吸收的动力学特性及低分子量有机酸(乙酸和苹果酸)对Cu2+吸收的影响。结果表明:苏柳172和垂柳根系对Cu2+的吸收量随溶液Cu2+浓度的升高及吸收时间的延长而增加。苏柳172和垂柳对Cu2+吸收的浓度动力学曲线呈线性,非饱和曲线,可以用米氏方程很好地拟合。米氏方程拟合的结果说明,垂柳根系的Cu2+吸收能力要稍强于苏柳172。Cu2+浓度为20 μmol/L时,随着乙酸和苹果酸浓度的增加,对苏柳172和垂柳根系吸收Cu2+的促进作用呈先上升后下降的趋势,其中,乙酸在10:1(乙酸∶ Cu2+)、苹果酸在5:1(苹果酸∶ Cu2+)时促进作用最强。Cu2+在根尖区的含量远远大于成熟区,说明根尖区是吸收Cu2+最活跃的区域。在Cu2+浓度为20 μmol/L的吸收液中加入乙酸或苹果酸(有机酸∶ Cu2+= 10:1)时,苏柳172根尖区的Cu2+含量分别增加了16.5%和33.7%,根成熟区的Cu2+含量增加了23.7%和43.0%,但根尖区和成熟区的Cu2+含量比值分别是1.40 和1.39,略小于不加有机酸时的1.49。乙酸与Cu2+的比例为10:1时,当Cu2+浓度小于20 μmol/L时乙酸促进垂柳根系对Cu2+的吸收,当Cu2+浓度大于20 μmol/L时,乙酸抑制垂柳根系对Cu2+的吸收,抑制作用随Cu2+浓度的升高而加强,说明低浓度的乙酸可以促进垂柳根对Cu2+的吸收,而高浓度的乙酸能够抑制垂柳根吸收Cu2+。同时,乙酸抑制了Cu2+在垂柳地上部的积累,抑制作用随着Cu2+浓度的增加而加强,说明乙酸能够抑制Cu2+由根向地上部的运输。  相似文献   

5.
用单细胞阳离子测定系统研究了SeO2-3对巨噬细胞内游离Ca2+和Mg2+的影响.实验结果表明:SeO2-3高于10-4mol/L时,有显著的细胞毒性.SeO2-3对细胞的毒性作用使细胞内游离Ca2+和Mg2+的浓度升高但Ca2+浓度的升高速率比Mg2+快.还有,高于10-4mol/L的SeO2-3对红细胞膜上的Ca2+-ATP酶活性有明显抑制作用.  相似文献   

6.
亲和层析纯化肌质网Ca2+-ATP酶   总被引:1,自引:1,他引:0  
建立了一种亲和层析纯化肌质网Ca2+-ATP酶的方法.用非离子型去污剂C12E8 溶解肌质网,再通过反应红-120琼脂糖亲和层析柱使肌质网Ca2+-ATP酶纯度从粗品中的65%提高到99%,并具有较高ATP水解活性.经SDS-聚丙烯酰胺凝胶电泳检测,为电泳纯.  相似文献   

7.
以细胞壁崩溃酶-Driselflse短时间处理水霉(Saprozegma ferax)菌丝,pH5.0时可使原生质从菌丝亚顶端喷出,pH6.0~8.0时则不导致该现象发生;适当浓度EGTA的存在,可提高pH5.0时酶解引起的原生质喷出频率、使pH6.0~8.0时生长菌丝的顶端原生质也喷出、并且喷出多发生在菌丝最顶端;外加CaCl2.不抑制菌丝顶端原生质的喷出,排除了Ca2+抑制酶活性的可能。随后的跟踪观察显示,长时间以缺Ca2+培养介质培养菌丝,同样能够导致菌丝顶端原生质喷出。上述研究结果表明,培养介质中Ca2+和H+对菌丝完整性的维持起调节作用,细胞壁上的Ca2+可能参与了水霉菌丝细胞壁物理特性的修饰。  相似文献   

8.
用生化测定法首次证实豚鼠精子质膜Ca2+-ATPase活性在精子获能和顶体反应过程中显著下降.Ca2+-ATPase抑制剂利尿酸(ethacrynic acid)抑制质膜Ca2+-ATPase活性,但钙调素(50μg/mL)的拮抗剂三氟拉嗪(TFP,200~500μmol/L)对该酶活性没有影响,说明钙调素不直接参与精子依赖于ATP的Ca2+的主动泵出.但钙调素与精子的Ca2+内流有关,钙调素拮抗剂TFP显著促进精子顶体反应和精子对Ca2+的摄入.Ca2+-ATPase抑制剂栎皮酮(quercetin)、原钒酸钠(sodiumorthovandate)、利尿磺胺(furosemide)和利尿酸均显著促进豚鼠精子的顶体反应,但却抑制精子对Ca2+的摄入,这无法用它们对质膜Ca2+-ATPase活性的抑制作用解释.推测这可能是由于Ca2+-ATPase抑制剂在抑制质膜Ca2+-ATPase活性的同时也抑制了顶体外膜或线粒体外膜上的该酶的活性,导致Ca2+在细胞质内的积累,进而通过负反馈机制抑制Ca2+进一步内流所致.另外,Ca2+-ATPase抑制剂对糖酵解的抑制作用也可能是Ca2+在细胞质中积累和抑制精子Ca2+摄入的原因.  相似文献   

9.
The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on deoxyuridine 5′-triphosphatase (dUTPase) in the cytosol of rat liver was investigated. Addition of Ca2+ up to 5.0 μM to the enzyme reaction mixture caused a significant decrease of dUTPase activity, while Zn2+, Cd2+, Co2+, Al3+, Mn2+ and Ni2+ (10 μM) did not have an appreciable effect. The Ca2+-induced decrease of dUTPase activity was reversed by the presence of regucalcin; the effect was complete at 1.0 μM of the protein. Regucalcin had no effect on the basal activity of the enzyme. Meanwhile, the reversible effect of regucalcin on the Ca2+ (10 μM)-induced decrease of dUTPase activity was not altered by the coexistence of Cd2+ or Zn2+ (10 μM). The present data suggest that liver cytosolic dUTPase is uniquely regulated by Ca2+ of various metals, and that the Ca2+ effect is reversed by regucalcin.  相似文献   

10.
基因工程菌大肠杆菌JM109富集废水中镍离子的研究   总被引:6,自引:2,他引:4  
利用通过基因工程技术所构建的在细胞内同时表达出高特异性镍转运蛋白和金属硫蛋白的基因工程菌富集水体中的镍离子。菌体细胞对Ni2+的富集速率很快,富集过程满足Langmuir等温线模型。与原始宿主菌相比,经基因改造的基因工程菌不仅最大镍富集容量增加了5倍多,而且对pH值、离子强度的变化及其它共存重金属离子的影响都呈现出更强的适应性。相比而言,Na+、Ca2+、Cd2+、Pb2+的影响较小,但Mg2+、Hg2+和Cu2+所引起的负面效应较大。进一步的实验表明基因工程菌对Ni2+的富集行为不需要外加营养物质。  相似文献   

11.
Systematic significance of mature embryo of bamboos   总被引:1,自引:0,他引:1  
The mature embryo of seven species belonging to five genera of Indian bamboos is described. In all these the basic pattern of embryo organisation is same: the scutellar and coleoptilar bundles are not separated by an internode, the epiblast is absent, the lower portion of the scutellum and the coleorhiza are separated by a cleft and the margins of embryonic leaves overlap. The features unique to fleshy fruited bamboos are: presence of a massive scutellum, the juxtaposition of plumule and radicle and the occurrence of a bud in the axil of the coleoptile. The fleshy fruit bearing bamboos should be classified into one group, the tribeMelocanneae. Evidence is provided to recognise additional groups in the subfamilyBambusoideae.  相似文献   

12.
Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.  相似文献   

13.
The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.  相似文献   

14.
The Drosophila Pax6 homolog twin of eyeless (toy) is so far the first zygotically expressed gene involved in eye morphogenesis in Drosophila. The study of its expression during embryogenesis is therefore informative of the initial events of eye development in Drosophila. We have analyzed how the initial expression domain of toy at cellular blastoderm is regulated. We show that the three maternal patterning systems active in the cephalic region (the anterior, terminal and dorsal-ventral systems) cooperate with zygotically activated gap genes to shape the initial expression domain of toy. Whereas Bicoid, Dorsal and Torso signaling synergistically act as activators, Hunchback, Knirps and Decapentaplegic act as repressors.  相似文献   

15.
16.
Twenty three species in 11 genera were examined in the field to determine hosts. OnlyStriga asiatica andSeymeria cassioides have a narrow host range being restricted to grasses and pines, respectively. These are the only species which cause pronounced and sometimes serious host damage. The other species attach to a great diversity of hosts.  相似文献   

17.
Lactobacilli play a distinctive role in the microbial balance of the chicken gut. In experiments simulating the chicken crop, the antagonism of lactobacilli against Enterobacteriaceae and Salmonella typhimurium was demonstrated and was attributed to lactic acid production. Moreover, adhesion to the crop epithelium was a common characteristic of intestinal lactobacilli. As opposed to salmonellas, lactobacilli were sensitive to deconjugated bile salts at 2.5mm. This sensitivity could lower their chance of proliferation in the small bowel of the chicken tract.The authors are at the Laboratory of Microbial Ecology, Faculty of Agricultural Sciences, State University of Gent, Coupure L., 653, B-9000 Gent, Belgium.  相似文献   

18.
Intracellular cysteine aspartate-specific proteases (caspases) play both signaling and effector roles in realizing the program of cell death. Caspases function as proteolytic cascades unique for each cell type and signal triggering apoptosis. All parts of the proteolytic cascades are duplicated and controlled by feedback signals. Amplification cycles between pairs of caspases (the third and the sixth, the ninth and the third, the twelfth and the sixth, and others) help multiply the initial apoptotic signal. The presence of physiological inhibitors of apoptosis that directly interact with caspases creates a multilevel regulatory network of apoptosis in cell. The caspase proteolytic cascades are also regulated by sphingolipid secondary messengers, among them ceramide, sphingosine, and their phosphates. Moreover, an association of the caspase signaling with ubiquitin-dependent proteolysis is shown in cells. In particular, the use of extracellular activators and inhibitors of caspases allows irreversible activation of apoptosis in tumor cells or the prevention of apoptosis in cortical neurons under neurodegenerative diseases.  相似文献   

19.
李腾  唐启明  韦玉梅  赵建成  李敏 《广西植物》2021,41(8):1372-1390
通过对采自广西24个县(市)的1 147份青藓科植物标本的逐一鉴定及相关文献的查阅,确认有广西青藓科植物11属、44种,其中包括广西青藓科植物新记录属1属,即拟异叶藓属(Pseudokindbergia),新记录种7种,分别为匐枝青藓(Brachythecium procumbens)、阔叶尖喙藓(Oxyrrhynchium latifolium)、泛生尖喙藓(O. vagans)、拟异叶藓(Pseudokindbergia dumosa)、华东细喙藓(Rhynchostegiella sinensis)、长肋拟青藓(Sciurohypnum populeum)和弯叶拟青藓(S. reflexum)。该文提供了修订后的广西青藓科植物名录,并对其中的新记录属、种的主要形态学识别特征、生境和地理分布等进行了详细描述。  相似文献   

20.
The role of the C-terminal domain of rhodopsin in the activation of transducin was studied. The treatment of photoreceptor membranes with trypsin, thermolysin, and Asp-N-endoprotease led to the respective rhodopsin species devoid of 9, 12-, or 19-aa C-terminal fragments. It was shown that the removal of 9-aa fragment by trypsin does not affect the catalytic activity of the receptor, whereas the thermolysin-induced truncation of the rhodopsin C-terminus by 12 aa about 1.5-fold enhances its activity. The Asp-N-endoprotease-assisted removal of 19 aa (i.e., the shortening by seven more C-terminal aa) virtually unchanges catalytic activity of the resulting truncated rhodopsin compared to the preparation truncated with thermolysin. These results suggest that the part of the rhodopsin C-terminal fragment between the sites of its cleavage by trypsin and thermolysin (Val337–Ser338–Lys339) inhibits the signal transduction from rhodopsin to the next component of visual cascade.  相似文献   

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