首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
紫花芒果后熟过程中主要类胡萝卜素含量的变化   总被引:4,自引:0,他引:4  
紫花芒果后熟过程中主要类胡萝卜素含量的变化周玉蝉,唐友林,谭兴杰(中国科学院华南植物研究所广州510650)关键词:总类胡萝卜素;α-胡萝卜素;β-胡萝卜素;叶黄素;芒果芒果以富含维生素A原——卜胡萝卜素而著称,而果实中类胡萝卜素含量的变化与芒果后熟...  相似文献   

2.
采用GA3诱导菠萝多酚氧化酶活性升高的机理   总被引:1,自引:0,他引:1  
在多酚氧化酶(PPO)提取过程中,直接加入GA3溶液,不能使PPO活性增加。采后GA3诱导菠萝PPO活性升高的同时,显著提高了酸性酸酯酶的活性,这是果实组织的Pi浓度明显升高的主要原因。随着果实的后熟,磷脂磷D活性不断下降,GA3处理显著延缓了该酶的下降速度。虽然采用ABA处理使果实PPO活性有小幅度增加,但ABA处理能使GA3对PPO活性的诱导明显加强。  相似文献   

3.
采后GA_3诱导菠萝多酚氧化酶活性升高的机理   总被引:2,自引:0,他引:2  
在多酚氧化酶(PPO)提取过程中,直接加入GA3溶液,不能使PPO活性增加。采后GA3诱导菠萝(Ananascomosus(L.)Mer.)PPO活性升高的同时,显著提高了酸性磷酸酯酶的活性,这是果实组织的Pi浓度明显升高的主要原因。随着果实的后熟,磷脂酶D活性不断下降,GA3处理显著延缓了该酶的下降速度。虽然采后ABA处理使果实PPO活性有小幅度增加,但ABA处理能使GA3对PPO活性的诱导明显加强。  相似文献   

4.
应用红外光谱技术定量测定了水化膜中蚯蚓新钙结合蛋白(NCBP)的二级结构及在不同比例Ca2+、Tb3+离子的作用下其二级结构的变化。结果表明,NCBP中α-helix含量较低而β-sheet的含量较高,且随不同比例金属离子的加入,1629cm-1处β-sheet峰的变化较明显。同时发现,NCBP具有钙结合蛋白家族特征的SDS-PAGE现象,但不具有激活PDE靶酶的活性,初步认为,NCBP含有与Ca2+浓度相关的特殊的结构和功能。另外,高浓度下Tb3+的结合引发NCBP的分子间聚合,提示对稀土元素的使用要慎重  相似文献   

5.
本文用荧光标记的受体底物〔Gnβ1-2Mα1-6(Gnβ1-2Mα1-3)Mβ1-4Gnβ1-4(Fucα1-6)Gn-PA〕,结合高效液相层析(HPLC)建立了细胞表面β1-4半乳糖基转移酶的活性检测方法。用这种方法研究HL60细胞,发现不同的培养时间,其细胞表面的酶变化明显,在24小时酶活性最高,此时细胞处在分裂间期。用佛波酯(PMA),视黄酸(RA)等细胞诱导分化剂处理HL60细胞株时,发现其表面活性发生了明显的变化,PMA诱导的细胞其表面酶活性在24小时变化最大,升高到对照的1.3倍;而RA处理的细胞其表面酶活性在72小时变化最大,升高到对照的1.72倍。  相似文献   

6.
条斑紫菜中R-藻红蛋白的生化特性   总被引:5,自引:0,他引:5  
条斑紫菜的R-藻红蛋白(R-PE),在CM-52柱上用含8mol/L脲的0.02mol/L乙酸铵缓冲液(pH=5.05)洗脱,观察到3条色带,经吸收光谱测定表明,它们分别是α、β、γ亚基。用SDS-PAGE测定的α、β和γ亚基分子量分别是17.0kd,18.0kd和31.7kd。R-PE中亚基的摩尔比是6α:6β:1γ。条斑紫菜的R-PE最稳定的聚集态分子量是229kd。各亚基的发色团含量:α亚基含2个藻红胆素(PEB),β亚基含1个PEB和0.5个藻尿胆素(PUB),γ亚基含2个PEB和3个PUB。结合R-PE和各亚基的氨基酸组成分析,条斑紫菜的R-PE亚基组成是(αβ)6γ。  相似文献   

7.
Gao BB  Han QD 《生理科学进展》1997,28(3):271-273
去甲肾上腺素(NA)可引起棕色脂肪组织(BAT)的产热作用,也是BAT募集反应主要的调节物质。BAT中存在的肾上腺素受体(AR)至少包括α1,α2,β1和β2四型。BAT的产热作用主要由β3-AR介导;其细胞增殖和细胞分化分别由β1-AR和β3-AR介导。与BAT募集有关的几种转录因子的表达也受NA的调控,例如c-fos和非成熟细胞C/EBPα基因的表达受β-和α1-AR的调节;C/EBPβ和成熟  相似文献   

8.
用荧光标记的受体底物(Gnβ1-2Mα1-6(Gnβ1-2Mα1-3)Mβ1-4Gnβ1-4(Fucα1-6)Gn-PA),结合高效液相层析(HPLC)建立了细胞β-1,4-半乳糖基转移酶的活性检测方法.研究了HL60细胞在体外低血清培养后不同的时间其酶活性的变化,发现12至24h酶活性达到一个高峰,为50.14pmol/min(106cel),此时细胞处在分裂间期,其它各测定时间变化不大.用PMA,RA等细胞诱导分化剂处理HL60细胞株时,发现其活性发生了较明显的变化,PMA诱导的细胞其酶活性在24h变化最大,升高到对照的1.32倍;而RA处理的细胞其酶活性在72h变化最大,升高到对照的2.15倍.  相似文献   

9.
应用蛋白dotblot技术检测了低氧内皮细胞条件培养液(HECCM)和常氧内皮细胞条件培养液(NECCM)内PDGF相对含量,并利用[3H]-TdR掺入法和流式细胞术观察了HECCM和NECCM及加入特异PDGF抗体对肺动脉平滑肌细胞(PASMC)生长的影响。结果表明,HECCM中的PDGF含量明显高于NECCM;HECCM能明显增强PASMC内DNA合成,促进PASMC从Go/G1期进入S期;当预先加入PDGF-B链抗体时,则会明显地抑制HECCM对PASMC的DNA合成,阻止PASMC从Go/G1期进入S期。结果提示,低氧时PASMC增殖与肺动脉内皮细胞分泌释放PDGF增加有关  相似文献   

10.
地衣芽孢杆菌1Baciuus Licheniformis)BL-306产生的胞外β-甘露聚糖酶经硫酸铵分级盐析,DEAE-纤维素柱层析。Sephadex-G100柱凝胶过滤和DEAE-纤维素柱再层析分离纯化,得到SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)均一样品。用SDS-PAGE测得纯化后β-甘露聚糖酶分子量为26000道尔顿。用凝胶等电聚焦电泳(PAGEIEF)测得等电点PI为5.0。该酶  相似文献   

11.
The goal of this article was to establish reference ranges of the concentration of trace elements in human serum and to compare these results with those reported by other authors. We describe the sample preparation and measurement conditions that allow the rapid, precise, and accurate determination of Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human serum samples (n=110) by inductively coupled plasma-mass spectrometry (ICP-MS). Accuracy and precision were determined by analyzing three reconstituted reference serum samples by comparison with other methods and by the standard addition procedure. The advantages of the ICP-MS method include short time of analysis of the elements mentioned, low detection limit, high precision, and high accuracy. Disadventages include a high risk of contamination due to the presence of some of the elements of interest in the environment, the relatively delicate sample handling, and the high cost of the equipment.  相似文献   

12.
Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons.  相似文献   

13.
A new polynitro cage compound 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptcyclo [5.5.1.1(3,11).1(5,9)] pentadecane (NNNAHP) was designed in the present work. Its molecular structure was optimized at the B3LYP/6-31 G(d,p) level of density functional theory (DFT) and crystal structure was predicted using the Compass and Dreiding force fields and refined by DFT GGA-RPBE method. The obtained crystal structure of NNNAHP belongs to the P-1 space group and the lattice parameters are a = 9.99 ?, b = 10.78 ?, c = 9.99 ?, α = 90.01°, β = 120.01°, γ = 90.00°, and Z = 2, respectively. Based on the optimized crystal structure, the band gap, density of state, thermodynamic properties, infrared spectrum, strain energy, detonation characteristics, and thermal stability were predicted. Calculation results show that NNNAHP has detonation properties close to those of CL-20 and is a high energy density compound with moderate stability.  相似文献   

14.
This report attempts to formulate reference ranges of elemental concentrations for 15 trace elements in selected human tissues and body fluids. A set of samples consisting of whole blood, blood serum, urine, milk, liver, and hair were chosen and considered for 15 elements of biological significance: As, Cd, Co, Cr, Cu, F, Fe, I, Hg, Mn, Mo, Ni, Pb, Se, and Zn. The results represent wholly or partially data received from 40 countries of the global regions of Africa, Asia, Europe, North, South, and Central America, Australia, and New Zealand. This survey, even if qualitative, has been useful in demonstrating certain trends of trace-element scenarios around the world. It is of course recognized that both diet and environment exert a strong influence on the distribution pattern of several elements, such as As, Cd, Mn, Pb, Se, and Zn. A limited comparison of the available information on soil status of different countries reflected some interesting associations for elements, such as Mn and Zn. Importantly, this study revealed that only a few countries were in a position to identify a reasonable amount of data on samples requested for this project. Regretably, for a number of countries, any dependable data for even such essential elements as Cu, Fe, and Zn were not available. In view of the nutritional importance of many elements, the time is ripe for concerted efforts by intergovernmental agencies to initiate investigations or commission task forces/projects to generate reliable reference data for selected global regions, which sadly lack data of any kind at present.  相似文献   

15.
16.
The variation with age of the 18 trace element mass fractions and some histological characteristics of intact prostate glands of 50 subjects aged 0–30 years was investigated by instrumental neutron activation analysis, inductively coupled plasma atomic emission spectrometry, and a quantitative morphometric analysis. Mean values ± standard error of the mean (M ± SΕΜ) for the mass fractions (in milligrams per kilogram wet tissue) of these trace elements in pre-puberty were: Al 28.5 ± 9.0, B 0.40 ± 0.11, Ba 1.48 ± 0.44, Br 10.5 ± 1.5, Ca 241 ± 30, Cl 3,203 ± 278, Cu 3.51 ± 0.89, Fe 33.7 ± 4.1, K 2,364 ± 145, Li 0.020 ± 0.004, Mg 153 ± 23, Mn 0.46 ± 0.06, Na 2,286 ± 130, P 1,391 ± 100, S 1,698 ± 132, Si 62 ± 11, Sr 0.38 ± 0.08, and Zn 27.6 ± 2.3. During puberty and postpuberty, when there is a significant increase in circulating androgens, the mean values were: Al 7.2 ± 1.4, B 0.21 ± 0.05, Ba 0.25 ± 0.06, Br 5.8 ± 1.0, Ca 433 ± 81, Cl 2,314 ± 201, Cu 1.77 ± 0.13, Fe 20.9 ± 1.6, K 2,585 ± 118, Li 0.0088 ± 0.0014, Mg 232 ± 27, Mn 0.34 ± 0.04, Na 1,875 ± 107, P 1,403 ± 98, S 1,673 ± 73, Si 22.2 ± 3.1, Sr 0.22 ± 0.03, and Zn 93.3 ± 8.9. Mean values (M ± SΕΜ) of percent volumes (%) of the stroma, epithelium and lumen in the prostate before puberty were 73.4 ± 2.6, 20.4 ± 1.7, and 4.45 ± 0.94, respectively, versus 46.5 ± 2.5, 38.5 ± 1.9, and 14.9 ± 1.2 during puberty and postpuberty. This work’s results confirm that the Zn mass fraction in prostate tissue is an androgen-dependent parameter. For the first time it has been demonstrated that the glandular lumen is a main pool of Ca, Mg, and Zn accumulation and that the stroma is a main pool of Al, B, Ba, Br, Cl, Cu, Fe, Mn, Na, and Si accumulation in the normal human prostate, for the age range 0–30 years. It was concluded that the Ca, Mg, and Zn binds tightly within the prostatic fluid, because the volume of glandular lumen reflects the volume of prostatic fluid.  相似文献   

17.
The effect of age and gender on major, minor, and trace element contents in the intact rib bone of 80 relatively healthy 15–55-year-old women and men was investigated. Contents or upper limit of contents of 16 chemical elements in the rib bone were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Mean values (M?±?SΕΜ) for the mass fraction of Ba, Ca, Cu, Fe, K, Li, Mg, Na, P, S, Sr, and Zn (milligram per kilogram of dry bone) were as follows: 2.54?±?0.16, 171,400?±?4,050, 1.35?±?0.22, 140?±?11, 1,874?±?71, 0.049?±?0.011, 2,139?±?38, 5,378?±?88, 75,140?±?1,660, 1,881?±?51, 291?±?20, and 92.8?±?1.5, respectively. The upper limits of contents of Al, B, Mn, and V were <7.20, <0.65, <0.36, and <0.03, respectively. Statistically significant tendency for the Ca, Mg, and P content to decrease with age was found in the human rib bone, regardless of gender. The mass fraction of Fe in the male rib bone increases with age. It was shown that higher Ca, Mg, Na, P, and Sr mass fractions as well as lower Fe content were typical of female ribs as compared to those in male ribs.  相似文献   

18.
The unitary conductances and permeability sequences of the rat connexin40 (rCx40) gap junction channels to seven monovalent cations and anions were studied in rCx40-transfected neuroblastoma 2A (N2A) cell pairs using the dual whole cell recording technique. Chloride salt cation substitutions (115 mM principal salt) resulted in the following junctional maximal single channel current-voltage relationship slope conductances (γj in pS): CsCl (153), RbCl (148), KCl (142), NaCl (115), LiCl (86), TMACl (71), TEACl (63). Reversible block of the rCx40 channel was observed with TBA. Potassium anion salt γj are: Kglutamate (160), Kacetate (160), Kaspartate (158), KNO3 (157), KF (148), KCl (142), and KBr (132). Ion selectivity was verified by measuring reversal potentials for current in rCx40 gap junction channels with asymmetric salt solutions in the two electrodes and using the Goldman-Hodgkin-Katz equation to calculate relative permeabilities. The permeabilities relative to Li+ are: Cs+ (1.38), Rb+ (1.32), K+ (1.31), Na+ (1.16), TMA+ (0.53), TEA+ (0.45), TBA+ (0.03), Cl (0.19), glutamate (0.04), and NO3− (0.14), assuming that the monovalent anions permeate the channel by forming ion pairs with permeant monovalent cations within the pore thereby causing proportionate decreases in the channel conductance. This hypothesis can account for why the predicted increasing conductances with increasing ion mobilities in an essentially aqueous channel were not observed for anions in the rCx40 channel. The rCx40 effective channel radius is estimated to be 6.6 Å from a theoretical fit of the relationship of relative permeability and cation radius.  相似文献   

19.
Nine blood group systems of goats were identified using 12 caprine reagents produced by absorption of alloimmune antisera. The caprine C blood group system, possibly homologous to the ovine C blood group system, was characterized by two reagents and shown to be controlled by three alleles,C 12,C 25, andC . A more complex blood group system of goats, designated G, was identified using three reagents and shown to be controlled by six codominant alleles (G 10.19.20,G 10.19,G 10.20,G 10,G 19,G 20) and a recessive allele (G ). A further seven one-factor two-allelic systems were identified by seven reagents. The nine genetic systems provided exclusion probabilities of 0.479, 0.492, 0.548, and 0.572 in Australian Angora, Dairy, Cashmere, and Texan Angora goat breeds, respectively. This work was supported by a grant from the Australian Stud Book, Alison Road, Randwick, New South Wales 2031, Australia.  相似文献   

20.
《Ibis》1894,36(3):447-460
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号