稀土-落叶松单宁配合物的合成及抗真菌活性研究

以稀土(Re~(3+))和落叶松单宁(LT)为原料,采用液相合成法合成了5种廉价的稀土-落叶松单宁(Re~(3+)-LT)配合物,并通过红外光谱、X射线光电子能谱、紫外光谱以及配位数测定确定了配合物的结构.采用牛津杯法、琼脂稀释法测定配合物对黑曲霉、红曲霉、白腐菌、毛霉4种真菌的抑制作用.在抑菌方面,5种配合物对上述4种真菌均具有较强的抑制作用,其抑菌活性大小顺序为Ce~(3+)-LTGd~(3+)-LTLa~(3+)-LTNd~(3+)-LTYb~(3+)-LT,其中Ce~(3+)-LT对4种真菌的最小抑菌浓度分别为:1.6、1.6、0.8和1.6 g·L~(-1);Yb~(3+)-LT对4种真菌的最小抑菌浓度分别为:3.2、1.6、3.2和3.2 g·L~(-1).在杀菌方面,Yb~(3+)-LT的杀菌活性最强,其对4种真菌的最小杀菌浓度分别为:6.4、3.2、3.2和6.4 g·L~(-1).此外,尽管Nd~(3+)-LT和Gd~(3+)-LT具有较强的抑菌活性,但对黑曲霉和毛霉的杀菌作用较弱.     

硫脲壳聚糖Zn(Ⅱ)配合物的制备、表征及生物活性

利用FT-IR、UV、TG-DTA和XRD手段,对合成的硫脲壳聚糖及硫脲壳聚糖-Zn(Ⅱ)配合物进行了表征,研究了壳聚糖、硫脲壳聚糖及硫脲壳聚糖-Zn(Ⅱ)配合物对细菌大肠杆菌、金黄色葡萄球菌和真菌黑曲霉的抑菌性能.结果表明:合成的硫脲壳聚糖-Zn(Ⅱ)配合物对大肠杆菌、金黄色葡萄球菌的抑菌性能比单一的壳聚糖、硫脲壳聚糖显著提高,对真菌黑曲霉亦具有较强的抑制作用.     

吡唑啉酮铜配合物P-FAH-Cu-phen对金黄色葡萄球菌的转录组影响分析

【背景】金黄色葡萄球菌是目前食品和临床引起感染的重要病原菌,迫切需要开发新型抗菌药物。【目的】分析吡唑啉酮铜配合物P-FAH-Cu-phen对金黄色葡萄球菌的转录组影响和主要代谢信号通路。【方法】采用液体稀释法测定P-FAH-Cu-phen作用金黄色葡萄球菌的最低抑菌浓度(minimum inhibitory concentration, MIC)和最低杀菌浓度(minimum bactericidal concentration, MBC)。将终浓度2 μg/mL的配合物分别作用于对数生长期的金黄色葡萄球菌30 min和2 h,进行转录组测序及分析。【结果】 P-FAH-Cu-phen作用金黄色葡萄球菌的MIC和MBC分别为2 μg/mL和4 μg/mL。与空白对照相比,配合物处理细菌30 min后,其差异基因共有356个,其中上调表达180个、下调表达176个;配合物处理细菌2 h后,其差异基因共有23个,其中上调表达3个、下调表达20个。差异基因功能主要富集于膜的组成部分、细胞质、质膜、ATP结合、发病机制、金属离子结合、组氨酸生物合成过程、DNA结合、水解酶活性、跨膜转运蛋白活性、硝酸盐同化、硝酸盐代谢过程、硝酸还原酶复合物、硝酸还原酶活性等。差异基因涉及的信号通路主要有双组分系统、群体感应、氮代谢、三羧酸循环、氨基酸代谢等。【结论】影响细菌质膜组成、毒素生成、生物膜形成、细胞壁合成、能量代谢等可能是吡唑啉酮铜配合物P-FAH-Cu-phen对金黄色葡萄球菌的主要抑菌作用。研究为揭示吡唑啉酮铜配合物抑制金黄色葡萄球菌分子机制提供了理论依据。     

青天葵体外抑菌活性研究

目的:研究青天葵水提取液、醇提取液和水醇提取液对金黄色葡萄球菌、大肠杆菌、白色念珠菌、伤寒沙门菌、绿脓杆菌、黑曲霉菌6种菌株的抑菌效果。方法:制备青天葵3种提取液,采用试管两倍稀释法测定3种提取液对金黄色葡萄球菌等6种菌株的最低抑菌浓度(MIC)。结果:青天葵水提取液对伤寒沙门菌的抑菌作用较强(MIC为12.5%),对金黄色葡萄球菌、大肠杆菌、绿脓杆菌和黑曲霉菌的抑菌作用较弱(MIC为50%);醇提取液对伤寒沙门菌和绿脓杆菌都有很强的抑菌作用(MIC为6.25%),对金黄色葡萄球菌也有较强的抑菌活性(MIC为12.5%),对大肠杆菌的抑菌作用较弱(MIC为50%);水醇提取液的抑菌活性与醇提取液相当。结论:青天葵对金黄色葡萄球菌等6种菌株表现出不同程度的抑制活性。     

茶多酚对金黄色葡萄球菌和铜绿假单胞菌的抑菌机理

以革兰氏阳性的金黄色葡萄球菌和革兰氏阴性的铜绿假单胞菌为试验菌,通过测定茶多酚与两种菌作用前后细菌培养液的电导率和可溶性总糖的变化,以及菌体在磷代谢和蛋白质表达方面的变化,初步阐明了茶多酚对这两种菌的抑菌机理。研究结果表明,茶多酚对金黄色葡萄球菌和铜绿假单胞菌均有抑菌活性,但对金黄色葡萄球菌的抑菌活性更强。经茶多酚处理后,细菌培养液的电导率和总糖浓度均增大,表明了茶多酚可破坏细胞膜的结构、导致细胞通透性增加,进而使细胞内容物外泄。另一方面,经茶多酚处理后的两种菌对磷的消耗量降低,以致严重影响了核酸、磷脂等细胞重要成分的合成以及能量代谢;通过SDS-PAGE分析,证实茶多酚可以阻碍细菌蛋白质的正常表达,以致影响其细胞的结构组成以及酶的催化活性,最终导致细菌正常生理功能的丧失。     

黄连内生真菌的分离鉴定及抑菌活性研究CSCD

为研究四川省峨眉地区黄连内生真菌多样性及菌株抑菌活性和机制,发掘黄连内生真菌资源,本研究从川黄连植株分离鉴定14株黄连内生真菌,分属于2纲,5目,7科,11属。根状茎、茎、叶和须根中的内生真菌定殖率分别是27.8%、56.7%、52.5%和39.6%。14株黄连内生真菌对金黄色葡萄球菌均有抑菌效果,Cop S01、Cop L01、Cop FR01的抑菌圈直径超过35 mm,纸片扩散法测得3株内生真菌发酵液对金黄色葡萄球菌均有效,Cop L01抑菌圈直径大于20 mm,抑菌效果最好,其发酵产物最低抑菌浓度(MIC)为10 mg/mL,最低杀菌浓度(MBC)为11 mg/mL。初步探究Cop L01抑菌机制发现该菌株发酵产物破坏金黄色葡萄球菌细胞膜,引起胞内核酸及蛋白外泄,造成金黄色葡萄球菌死亡。本研究表明川黄连内生真菌具有丰富的多样性,部分菌株及其发酵产物对金黄色葡萄球菌均表现出较好的抑菌效果,预示着黄连内生真菌Cop L01具有产生新型抗菌活性物质的潜力,为后续深入开发这一资源宝库提供了新的菌种和思路。     

藜蒿提取物抑菌作用的初步研究

采用榨汁、水提、醇提等 3种不同的方法 ,提取藜蒿中的抗菌有效成分。测定了各种提取物对 14种食品腐败菌的最低抑菌浓度 ( MIC) ,结果表明 :1.藜蒿汁的 MIC:痢疾杆菌为 2 5% ,大肠杆菌为 2 5% ,巨大芽孢杆菌为 50 % ,面包酵母为 5% ;2 .藜蒿水提物的 MIC:痢疾杆菌为 2 .5% ,大肠杆菌为 5% ,巨大芽孢杆菌为 5% ,面包酵母为 10 % ;3.黎蒿醇提物的 MIC:痢疾杆菌、巨大芽孢杆菌、大肠杆菌均为 5% ,蜡状芽孢杆菌、金黄色葡萄球菌、面包酵母、黄曲霉均为 10 % ,产朊酵母、裂殖酵母、异常汉逊酵母、白地霉、桔青霉、镰刀霉均为 2 0 %     

桂皮酸-8-羟基喹啉稀土配合物的合成、抑菌活性及其对DNA的作用

以稀土离子为模板,用桂皮酸、8-羟基喹啉为原料,在乙醇溶液中首次合成了两种稀土三元配合物,采用元素分析、摩尔电导、红外光谱、紫外光谱和荧光光谱进行表征,并研究了配合物对常见细菌大肠杆菌和金黄色葡萄球菌的抑菌活性以及与DNA的相互作用.结果表明:配合物的抑菌活性较配体和稀土离子均有提高,能使细胞正常的DNA复制生理功能受到影响.     

脱油油樟叶提取物的体外抑菌活性研究

探讨了油樟叶提取挥发油后的残渣的乙醇浸膏和乙醇浸膏的石油醚萃取相、乙酸乙酯萃取相、正丁醇萃取相和水萃取相对大肠杆菌、金黄色葡萄球菌、沙门氏菌等三种常见致病菌的最低抑菌浓度(MIC)、最低杀菌浓度(MBC)以及抑菌曲线.结果显示,各提取物对大肠杆菌的抑菌活性为正丁醇萃取相(MIC、MBC:7.813、15.625 mg/...     

两种中药剂型的体外抑菌作用观察

目的比较黄连等20种中药水煎剂与免煎颗粒剂对56株临床分离的金黄色葡萄球菌的体外抑菌效果。方法采用M-H琼脂稀释法检测20种中药水煎剂与免煎颗粒剂对MSSA(甲氧西林敏感金黄色葡萄球菌)、MRSA(耐甲氧西林金黄色葡萄球菌)的体外抑菌作用,测定MIC50(药物抑制50%细菌时的最小浓度)、MIC90(药物抑制90%细菌时的最小浓度),MIC(最小抑菌浓度),并作比较。结果 20种中药的水煎剂和免煎颗粒对56株受试菌显示了不同程度的抑菌作用,以五倍子抑菌效果最好,水煎剂抑菌效果比相应的免煎颗粒好。结论两种中药剂型在抗感染中,均具有临床实际应用价值,而水煎剂抑菌效果稍强于相应的免煎颗粒剂型。     

Development of silver-containing austenite antibacterial stainless steels for biomedical applications Part I: microstructure characteristics,mechanical properties and antibacterial mechanisms

The as-quenched (AQ) microstructure of the Ag-containing alloys was found to be essentially a mixture of austenite (γ) and Ag phases. The Ag phase precipitates had a face-centered-cubic structure and lattice parameter a = 4.09 Å. When the alloy contained Ag ≥0.2 wt%, the mechanical properties were slightly enhanced because of the precipitate strengthening by the Ag phase precipitates. Moreover, the Ag-containing alloys exhibited ductile fracture after tensile testing. The results of an antibacterial test revealed that the Ag phase precipitates play a key role in the antibacterial mechanism of Ag-containing alloys: Ag⁺ ions released from the Ag phase precipitates can kill bacteria. It is suggested that as AISI 316L alloy has an Ag content ≥0.2 wt%, it will have excellent antibacterial properties against both Staphylococcus aureus and Escherichia coli, with an antibacterial rate of nearly 100%.     

Influence of exogenous application of glycinebetaine on antioxidative system and growth of salt-stressed soybean seedlings (Glycine max L.)

Glycinebetaine is one of the most competitive compounds which play an important role in salt stress in plants. In this study, the enhanced salt tolerance in soybean (Glycine max L.) by exogenous application of glycinebetaine was evaluated. To improve salt tolerance at the seedling stage, GB was applied in four different concentrations (0, 5, 25 and 50 mM) as a pre-sowing seed treatment. Salinity stress in the form of a final concentration of 150 mM sodium chloride (NaCl) over a 15 day period drastically affected the plants as indicated by increased proline, MDA and Na⁺ content of soybean plants. In contrast, supplementation with 50 mM GB improved growth of soybean plants under NaCl as evidenced by a decrease in proline, MDA and Na⁺ content of soybean plants. Further analysis showed that treatments with GB, resulted in increasing of CAT and SOD activity of soybean seedlings in salt stress. We propose that the role of GB in increasing tolerance to salinity stress in soybean may result from either its antioxidant capacity by direct scavenging of H₂O₂ or its role in activating CAT activity which is mandatory in scavenging H₂O₂.     

Na(+) interaction with the pore of Shaker B K(+) channels: zero and low K(+) conditions.

The Shaker B K(+) conductance (G(K)) collapses (in a reversible manner) if the membrane is depolarized and then repolarized in, 0 K(+), Na(+)-containing solutions (Gómez-Lagunas, F. 1997. J. Physiol. 499:3-15; Gómez-Lagunas, F. 1999. Biophys. J. 77:2988-2998). In this work, the role of Na(+) ions in the collapse of G(K) in 0-K(+) solutions, and in the behavior of the channels in low K(+) was studied. The main findings are as follows. First, in 0-K(+) solutions, the presence of Na(+) ions is an important factor that speeds the collapse of G(K). Second, external Na(+) fosters the drop of G(K) by binding to a site with a K(d) = 3.3 mM. External K(+) competes, in a mutually exclusive manner, with Na(o)(+) for binding to this site, with an estimated K(d) = 80 microM. Third, NMG and choline are relatively inert regarding the stability of G(K); fourth, with [K(o)(+)] = 0, the energy required to relieve Na(i)(+) block of Shaker (French, R.J., and J.B. Wells. 1977. J. Gen. Physiol. 70:707-724; Starkus, J.G., L. Kuschel, M. Rayner, and S. Heinemann. 2000. J. Gen. Physiol. 110:539-550) decreases with the molar fraction of Na(i)(+) (X(Na,i)), in an extent not accounted for by the change in Delta(mu)(Na). Finally, when X(Na,i) = 1, G(K) collapses by the binding of Na(i)(+) to two sites, with apparent K(d)s of 2 and 14.3 mM.     

Loss of caveolin-1 impairs retinal function due to disturbance of subretinal microenvironment

Caveolin-1 (Cav-1), an integral component of caveolar membrane domains, is expressed in several retinal cell types, including photoreceptors, retinal vascular endothelial cells, Müller glia, and retinal pigment epithelium (RPE) cells. Recent evidence links Cav-1 to ocular diseases, including autoimmune uveitis, diabetic retinopathy, and primary open angle glaucoma, but its role in normal vision is largely undetermined. In this report, we show that ablation of Cav-1 results in reduced inner and outer retinal function as measured, in vivo, by electroretinography and manganese-enhanced MRI. Somewhat surprisingly, dark current and light sensitivity were normal in individual rods (recorded with suction electrode methods) from Cav-1 knock-out (KO) mice. Although photoreceptor function was largely normal, in vitro, the apparent K(+) affinity of the RPE-expressed α1-Na(+)/K(+)-ATPase was decreased in Cav-1 KO mice. Cav-1 KO retinas also displayed unusually tight adhesion with the RPE, which could be resolved by brief treatment with hyperosmotic medium, suggesting alterations in outer retinal fluid homeostasis. Collectively, these findings demonstrate that reduced retinal function resulting from Cav-1 ablation is not photoreceptor-intrinsic but rather involves impaired subretinal and/or RPE ion/fluid homeostasis.     

Spatial,Cellular, and Intracellular Localization of Na+/K+-ATPase in the Sterically Disposed Renal Tubules of Japanese Eel

The kidney plays a crucial role in the regulation of water and ion balances in both freshwater and seawater fishes. However, the complicated structures of the kidney hamper comprehensive understanding of renal functions. In this study, to investigate the structure of sterically disposed renal tubules, we examined spatial, cellular, and intracellular localization of Na⁺/K⁺-ATPase in the kidney of the Japanese eel. The renal tubule was composed of the first (PT-I) and second (PT-II) segments of the proximal tubule and the distal tubule (DT), followed by the collecting ducts (CDs). Light microscopic immunocytochemistry detected Na⁺/K⁺-ATPase along the renal tubules and CD; however, the subcellular distribution of the Na⁺/K⁺-ATPase immunoreaction varied among different segments. Electron microscopic immunocytochemistry further revealed that Na⁺/K⁺-ATPase was distributed on the basal infoldings of PT-I, PT-II, and DT cells. Three-dimensional analyses showed that the renal tubules meandered in a random pattern through lymphoid tissues, and then merged into the CD, which was aligned linearly. Among the different segments, the DT and CD cells showed more-intense Na⁺/K⁺-ATPase immunoreaction in freshwater eel than in seawater-acclimated eel, confirming that the DT and CD segments are important in freshwater adaptation, or hyperosmoregulation. (J Histochem Cytochem 58:707–719, 2010)     

Interaction of the BKCa channel gating ring with dendrotoxins

Two classes of small homologous basic proteins, mamba snake dendrotoxins (DTX) and bovine pancreatic trypsin inhibitor (BPTI), block the large conductance Ca²⁺-activated K⁺ channel (BK_Ca, KCa1.1) by production of discrete subconductance events when added to the intracellular side of the membrane. This toxin-channel interaction is unlikely to be pharmacologically relevant to the action of mamba venom, but as a fortuitous ligand-protein interaction, it has certain biophysical implications for the mechanism of BK_Ca channel gating. In this work we examined the subconductance behavior of 9 natural dendrotoxin homologs and 6 charge neutralization mutants of δ-dendrotoxin in the context of current structural information on the intracellular gating ring domain of the BK_Ca channel. Calculation of an electrostatic surface map of the BK_Ca gating ring based on the Poisson-Boltzmann equation reveals a predominantly electronegative surface due to an abundance of solvent-accessible side chains of negatively charged amino acids. Available structure-activity information suggests that cationic DTX/BPTI molecules bind by electrostatic attraction to site(s) on the gating ring located in or near the cytoplasmic side portals where the inactivation ball peptide of the β2 subunit enters to block the channel. Such an interaction may decrease the apparent unitary conductance by altering the dynamic balance of open versus closed states of BK_Ca channel activation gating.     

Overexpression of SeNHX1 improves both salt tolerance and disease resistance in tobacco

Recently, we found NHX1, the gene encoding a Na⁺/H⁺ exchanger, participated in plant disease defense. Although NHX1 has been confirmed to be involved in plant salt tolerance, whether the NHX1 transgenic plants exhibit both salt tolerance and disease resistance has not been investigated. The T1 progenies of Nicotiana tabacum L. lines expressing SeNHX1 (from Salicornia europaea) were generated for the present study. Compared with PBI-type control plants, SeNHX1 transgenic tobaccos exhibited more biomass, longer root length, and higher K⁺/Na⁺ ratio at post germination or seedling stage under NaCl treatment, indicating enhanced salt tolerance. The vacuolar H⁺ efflux in SeNHX1 transgenic tobacco was increased after treatment of NaCl with different concentration. Meanwhile, the SeNHX1 transgenic tobaccos showed smaller wilted spot area, less H₂O₂ accumulation in leaves after infection of Phytophthora parasitica var. nicotianae. Further investigation demonstrated a larger NAD(P)(H) pool in SeNHX1 transgenic tobacco. These evidences revealed that overexpression of SeNHX1 intensified the compartmentation of Na⁺ into vacuole under salt stress and improved the ability of eliminating ROS after pathogen attack, which then enhanced salt tolerance and disease resistance simultaneously in tobacco. Our findings indicate NHX1 has potential value in creating crops with both improved salt tolerance and disease resistance.     

Na+/K+-ATPase resistance and cardenolide sequestration: basal adaptations to host plant toxins in the milkweed bugs (Hemiptera: Lygaeidae: Lygaeinae)

Despite sequestration of toxins being a common coevolutionary response to plant defence in phytophagous insects, the macroevolution of the traits involved is largely unaddressed. Using a phylogenetic approach comprising species from four continents, we analysed the ability to sequester toxic cardenolides in the hemipteran subfamily Lygaeinae, which is widely associated with cardenolide-producing Apocynaceae. In addition, we analysed cardenolide resistance of their Na⁺/K⁺-ATPases, the molecular target of cardenolides. Our data indicate that cardenolide sequestration and cardenolide-resistant Na⁺/K⁺-ATPase are basal adaptations in the Lygaeinae. In two species that shifted to non-apocynaceous hosts, the ability to sequester was secondarily reduced, yet Na⁺/K⁺-ATPase resistance was maintained. We suggest that both traits evolved together and represent major coevolutionary adaptations responsible for the evolutionary success of lygaeine bugs. Moreover, specialization on cardenolides was not an evolutionary dead end, but enabled this insect lineage to host shift to cardenolide-producing plants from distantly related families.     

Altered intracellular pH regulation in cells with high levels of P-glycoprotein expression

P-glycoprotein is an ATP-binding-cassette transporter that pumps many structurally unrelated drugs out of cells through an ATP-dependent mechanism. As a result, multidrug-resistant cells that overexpress P-glycoprotein have reduced intracellular steady-state levels of a variety of chemotherapeutic agents. In addition, increased cytosolic pH has been a frequent finding in multidrug-resistant cells that express P-glycoprotein, and it has been proposed that this consequence of P-glycoprotein expression may contribute to the lower intracellular levels of chemotherapeutic agents. In these studies, we measured intracellular pH and the rate of acid extrusion in response to an acid load in two cells with very different levels of P-glycoprotein expression: V79 parental cells and LZ-8 multidrug resistant cells. Compared to the wild-type V79 cells, LZ-8 cells have a lower intracellular pH and a slower recovery of intracellular pH after an acid load. The data also show that LZ-8 cells have reduced ability to extrude acid, probably due to a decrease in Na⁺/H⁺ exchanger activity. The alterations in intracellular pH and acid extrusion in LZ-8 cells are reversed by 24-h exposure to the multidrug-resistance modulator verapamil. The lower intracellular pH in LZ-8 indicates that intracellular alkalinization is not necessary for multidrug resistance. The reversal by verapamil of the decreased acid-extrusion suggests that P-glycoprotein can affect other membrane transport mechanism.