鲣鱼骨硫酸软骨素提取工艺研究

[目的]以鲣鱼骨为原料,对鱼骨硫酸软骨素提取方法进行研究。[方法]以硫酸软骨素提取率为评价指标,通过单因素和正交试验优化鲣鱼骨硫酸软骨素的提取条件。[结果]在酶添加量2.5%(木瓜蛋白酶:胰蛋白酶为1∶2)、料液比1∶20、提取温度80℃、p H 6.5下浸提24 h、超声处理30 min,鱼骨硫酸软骨素的提取率达2.86%,纯度为90.0%。理化分析显示,鲣鱼骨硫酸软骨素颜色洁白,水分含量9.2%,氨基己糖含量30.1%,氮含量3.05%,葡萄糖醛酸含量26.9%。通过红外光谱分析,确定样品为硫酸软骨素C。[结论]利用优化工艺提取鲣鱼骨中的硫酸软骨素具有可行性,在鲣鱼加工副产物的高值化利用中具有一定的应用前景。     

牦牛胸小骨中硫酸软骨素的提取研究

以牦牛胸小骨为原料,采用稀碱-酶解法提取硫酸软骨素,对碱解条件和酶解过程进行筛选.碱提取的最佳条件为:原料与1.5%的NaOH液质量比1∶1.2,38℃搅拌提取10 h;酶水解最佳条件为:胰酶体积分数8%,pH8.5~9.0,48~51℃水解5~6 h.在最佳提取条件下,得到牦牛胸小骨硫酸软骨素产品为白色粉末,纯度92.5%,收率为2.67%.     

一氧化氮合酶与糖尿病小鼠视网膜细胞凋亡

取正常小鼠、糖尿病2周(DM1组)及20周(DM2组)小鼠的视网膜样本,TUNEL法检测细胞凋亡及存在的部位;免疫印迹法检测一氧化氮合酶( iNOS、nNOS)的表达;竞争性ELISA法测定硝基酪氨酸含量,检测视网膜损伤程度,探讨一氧化氮合酶与早期糖尿病小鼠(2、20周)视网膜细胞凋亡的关系.结果表明:对照组未发现凋亡...     

绿藻中提取的硫酸鼠李糖对酶的抑制作用研究

该文研究了从太平洋沿岸、浙江沿海地区的天然绿藻中提取硫酸化多糖的高效方法。通过对比盐酸处理法、酶处理法、高温加热酶处理法提取硫酸鼠李糖的得率,高温加热酶处理法最为高效。其次该种硫酸化多糖对各种生物酶的活性抑制实验表明,硫酸鼠李糖对透明质酸酶和弹性蛋白酶的活性抑制能力较强,对胶原蛋白酶活性无抑制作用,对络氨酸酶活性有一定抑制作用。证明绿藻中提取的硫酸鼠李糖对于人体的保湿性能、抗黑色素生成性能以及维持肌肤弹性方面均有作用,为其今后在护肤品行业和健康保健食品方面的发展提供理论基础。     

运动对大鼠心肌细胞与一氧化氮合酶的影响

【目的】研究运动对大鼠心肌细胞及一氧化氮合酶的影响,探讨运动引起心肌细胞凋亡的可能机制。【方法】通过游泳训练建立大鼠有氧训练组和力竭过度训练组模型,以常规饲养大鼠为对照,检测各组大鼠心脏质量与心系数(心脏质量/体质量)的变化,采用Western blot检测心肌细胞中p53蛋白的表达,DNA ladder法检测心肌组织细胞的凋亡,并测定各组大鼠心肌与血清中的NO含量及结构型NOS(cNOS)、诱导型NOS(iNOS)活性。【结果】力竭过度训练组大鼠心脏质量和心系数增加,心肌细胞中p53蛋白的表达显著增加,与过度训练时大鼠心肌细胞凋亡基因的调控有关。DNA ladder检测结果显示,有氧训练组大鼠心肌与血清中的cNOS活性升高,有少量的NO生成,对大鼠心血管系统产生了良性影响,使大鼠心血管系统功能增强;而力竭过度训练组出现了明显的凋亡条带,长期的过度负荷使大鼠心肌与血清中的iNOS活性升高,产生的较多NO对细胞具有毒性作用。【结论】不适宜的运动负荷会促使大鼠心肌细胞凋亡,NO可能参与了心肌的损害过程。     

丹参酚酸B盐联合黄芪多糖预处理对大鼠脑缺血再灌注细胞凋亡及GFAP表达的影响

目的观察丹参酚酸B盐联合黄芪多糖预处理对SD大鼠脑缺血再灌注损伤细胞凋亡及脑组织中胶质纤维酸性蛋白(GFAP)表达的影响,探讨该预处理方式对脑缺血再灌注损伤后梗死灶及缺血半暗带重塑的影响。方法以线栓法建立缺血再灌注模型——大脑中动脉梗塞模型(MCAO)。将138只雄性SD大鼠随机分为6组(各23只):正常组、假手术组、模型(缺血再灌注)组、丹参酚酸B盐组、黄芪多糖预处理组及丹参酚酸B盐联合黄芪多糖预处理组。观察丹参酚酸B盐联合黄芪多糖预处理对大鼠脑缺血再灌注神经功能、脑梗死面积和病理形态学的影响。采用TUNEL法检测缺血半暗带和灶中心区凋亡细胞,采用免疫组化法检测缺血半暗带和灶中心区GFAP表达的变化。结果模型组与假手术组相比,缺血半暗带凋亡细胞及GFAP阳性细胞数目增多;丹参酚酸B盐联合黄芪多糖预处理可不同程度地降低实验性脑缺血大鼠的神经功能评分(Longa评分)、减小梗死灶面积并使脑组织病理形态改变减轻(P<0.05);丹参酚酸B盐联合黄芪多糖预处理组大鼠脑组织缺血半暗带凋亡细胞和GFAP表达减少,而梗死灶中心凋亡细胞和GFAP表达却增多。结论丹参酚酸B盐联合黄芪多糖预处理可能通过调节脑缺血再灌注损伤细胞凋亡和GFAP表达而促进脑重塑。     

Spectral consequences of photoreceptor sampling in the rhesus retina

Optical transforms were used to compute the power spectra of rhesus cones treated as arrays of image sampling points. Spectra were obtained for the central fovea, parafovea, periphery, and far periphery. All were consistent with a novel spatial sampling principle that introduces minimal noise for spatial frequencies below the Nyquist limits implied by local receptor densities, while frequencies above the nominal Nyquist limits are not converted into conspicuous moiré patterns, but instead are scattered into broadband noise. This sampling scheme allows the visual system to escape aliasing distortion despite a large mismatch between retinal image bandwidth and the Nyquist limits implied by extrafoveal cone densities.     

Illumination induces dye incorporation in photoreceptor cells

Illumination of fly photoreceptors in the presence of the fluorescent dye Lucifer yellow initiates incorporation of the dye, which stains each cell down to its synaptic terminal. Unilluminated cells do not become stained. Experiments on animals in vivo show that selected cells can be stained without loss of viability. "Induced endocytosis" provides a plausible mechanism underlying this phenomenon.     

Asymmetry in the structure of the ABC transporter-binding protein complex BtuCD-BtuF

BtuCD is an adenosine triphosphate-binding cassette (ABC) transporter that translocates vitamin B12 from the periplasmic binding protein BtuF into the cytoplasm of Escherichia coli. The 2.6 angstrom crystal structure of a complex BtuCD-F reveals substantial conformational changes as compared with the previously reported structures of BtuCD and BtuF. The lobes of BtuF are spread apart, and B12 is displaced from the binding pocket. The transmembrane BtuC subunits reveal two distinct conformations, and the translocation pathway is closed to both sides of the membrane. Electron paramagnetic resonance spectra of spin-labeled cysteine mutants reconstituted in proteoliposomes are consistent with the conformation of BtuCD-F that was observed in the crystal structure. A comparison with BtuCD and the homologous HI1470/71 protein suggests that the structure of BtuCD-F may reflect a posttranslocation intermediate.     

A 49-kilodalton phosphoprotein in the Drosophila photoreceptor is an arrestin homolog

The gene encoding the 49-kilodalton protein that undergoes light-induced phosphorylation in the Drosophila photoreceptor has been isolated and characterized. The encoded protein has 401 amino acid residues and a molecular mass of 44,972 daltons, and it shares approximately 42 percent amino acid sequence identity with arrestin (S-antigen), which has been proposed to quench the light-induced cascade of guanosine 3',5'-monophosphate hydrolysis in vertebrate photoreceptors. Unlike the 49-kilodalton protein, however, arrestin, which appears to bind to phosphorylated rhodopsin, has not itself been reported to undergo phosphorylation. In vitro, Ca2+ was the only agent found that would stimulate the phosphorylation of the 49-kilodalton protein. The phosphorylation of this arrestin-like protein in vivo may therefore be triggered by a Ca2+ signal that is likely to be regulated by light-activated phosphoinositide-specific phospholipase C.     

SO2对谷子幼苗根系镉胁迫的缓解作用

以谷子幼苗为材料,采用SO_2衍生物(SO_3~(2-)∶HSO_3~-,3∶1,mmol·L~(-1)/mmol·L~(-1))预处理方式,研究外源SO_2对镉(Cd)致根系毒性的影响。研究发现:250、500μmol·L~(-1)Cd胁迫下,谷子幼苗根生长受到明显抑制,根组织中活性氧(ROS)大量产生,膜脂过氧化增加;与Cd单独处理组相比,用500μmol·L~(-1)SO_2衍生物预处理后,Cd对根系生长的抑制作用减弱,根组织中ROS水平降低,膜脂氧化损伤减轻,谷胱甘肽(GSH)含量提高,过氧化物酶(POD)、谷胱甘肽过氧化物酶(GPX)和谷胱甘肽硫转移酶(GST)等酶活性明显增加。结果表明:一定浓度的SO_2衍生物能够通过上调抗氧化酶系统POD和GPX的活性来有效缓解Cd胁迫造成的谷子根系氧化损伤,并很可能通过维持较高的GSH水平和提高GST活性来增强谷子根系的Cd解毒能力。     

Microspectrophotometry of photoreceptor organelles from eyes of the prawn Palaemonetes

Microspectrophotometric measurements of individual dark-adapted rhabdoms of the prawn Palaemonetes vulgaris reveal the presence of two light-sensitive pigments. A pigment with maximum absorbancy at 555 nanometers is converted by light to a long-lived intermediate with wavelength of maximum absorbancy at 496 nanometers. A second pigment with wavelength of maximum absorbancy at 496 nanometers bleaches in the light, seemingly without forming detectable products at wavelengths longer than 375 nanometers. Both pigments occur in each layer of microvilli.     

Multicompartment micelles from ABC miktoarm stars in water

By combining three mutually immiscible polymeric components in a mixed-arm star block terpolymer architecture, we have observed the formation of a previously unknown class of multicompartment micelles in dilute aqueous solution. Connection of water-soluble poly(ethylene oxide) and two hydrophobic but immiscible components (a polymeric hydrocarbon and a perfluorinated polyether) at a common junction leads to molecular frustration when dispersed in aqueous solution. The incompatible hydrophobic blocks form cores that are protected from the water by the poly(ethylene oxide) blocks, but both are forced to make contact with the poly(ethylene oxide) by virtue of the chain architecture. The structures that emerge depend on the relative lengths of the blocks and can be tuned from discrete multicompartment micelles to extended wormlike structures with segmented cores.     

Cyclic nucleotide phosphodiesterase: high activity in a mammalian photoreceptor

Purified outer segments of bovine rods exhibit phosphodiesterase activity against adenosine and guanosine cyclic 3',5'-monophosphates (cyclic AMP and cyclic GMP). The enzyme hydrolyzed cyclic GMP more rapidly than cyclic AMP at low substrate concentrations. The presence of high phosphodiesterase activity in this highly specialized organelle suggests that this enzyme may function in control of cyclic nucleotide concentration during visual excitation or adaptation.     

Membrane changes in a single photoreceptor cause associative learning in Hermissenda

Single type B photoreceptors in intact, restrained Hermissenda were impaled with a microelectrode and exposed to either paired or unpaired presentations of light and depolarizing current to simulate natural stimulus effects during conditioning with light and rotation. Paired, but not unpaired, stimulus presentations produced cumulative depolarization and increased input resistance in type B cells. These membrane changes are similar to those observed after pairings of light and rotation are administered to either intact animals or isolated nervous systems or when light is paired with electrical stimulation of the vestibular system in isolated nervous systems. One and two days after treatment, pairing- and light-specific suppression of phototactic behavior was observed in recovered animals. These findings indicate that the membrane changes of type B cells produced by pairing light with current injections cause acquisition of the learned behavior.