卵黄脂磷蛋白通过网格蛋白介导的内吞作用进入培养的人成纤维细胞

为了探究从斑马鱼(Danio rerio)胚胎裂解液中纯化的卵黄脂磷蛋白(lipovitellin, Lv)进入培养的人成纤维细胞的分子途径,该研究用Sephadex G-200色谱柱结合QAE-Sephadex A50阴离子交换色谱柱从斑马鱼0 h胚胎裂解液中分离纯化出Lv。FITC标记的Lv(FITC-Lv)预先分别与Hepes、牛组蛋白、鱼精蛋白、卵磷脂、0 h胚胎胰蛋白酶水解物或者斑马鱼胚胎裂解液孵育,再加入至opti-MEM培养基中培养人成纤维细胞,培养一定时间后,用荧光倒置显微镜观察,发现Hepes和组蛋白可以促进Lv进入细胞。制霉菌素是陷窝介导的内吞作用(caveolae-mediated endocytosis)的抑制剂,氯丙嗪和蔗糖是网格蛋白介导的内吞作用(clathrin-mediated endocytosis)的抑制剂,阿米洛利是巨胞饮作用(macropinocytosis)的抑制剂。为了证实Lv进入细胞的分子途径,在FITC标记Lv与人成纤维细胞的培养体系中,分别加入上述抑制剂。结果发现氯丙嗪和蔗糖可以抑制Lv进入细胞。该研究获得如下结论:纯化的斑马鱼Lv单独...     

氯毒素用于神经胶质瘤治疗的研究进展

氯毒素是一种从以色列沙漠蝎的毒液中分离出来的多肽,它具有稳定和紧凑的三级结构,可以抑制胶质瘤细胞的增殖、转移和侵袭,并且可作为靶向剂结合显影剂和药物等用于胶质瘤细胞的治疗.本文就对氯毒素在脑胶质瘤治疗中的研究和应用进展方面作一综述.     

16S rDNA实时荧光定量PCR检测大蒜提取物对小鼠肠道菌群的调节作用

目的 探究蒜氨酸、大蒜辣素、大蒜粉对小鼠肠道菌群的调节作用。方法 将SPF级C57BL/6J小鼠分为空白对照组、蒜氨酸组、大蒜辣素组和大蒜粉组,每组10只。空白对照组小鼠灌服蒸馏水30 d,蒜氨酸组、大蒜辣素组、大蒜粉组小鼠灌服不同浓度的受试物溶液30 d,采用16S rDNA实时荧光定量PCR检测实验前后小鼠粪便样本中乳杆菌、双歧杆菌、肠杆菌、肠球菌、产气荚膜梭菌水平变化。结果 给药30 d后,与空白对照组相比、实验前后自身对比,蒜氨酸组、大蒜辣素组、大蒜粉组小鼠的肠杆菌、肠球菌水平无明显变化;乳杆菌、双歧杆菌水平显著增加;产气荚膜梭菌水平显著降低。结论 蒜氨酸、大蒜辣素、大蒜粉对肠道菌群具有有益的调节作用,是一种良好的天然有益于肠道菌群的食品。     

不同叶面免疫诱抗剂对烟草生长和抗性的影响

为明确施用不同叶面免疫诱抗药剂对烟草抗性和生长的影响,在重庆市奉节县基地开展田间小区试验,探究在烟草生长期施用不同叶面免疫诱抗药剂对烟草生长和抗性的影响.结果表明：在烟草生长中期,喷施生物诱抗药剂智能聪(ZNC)和化学诱抗剂氯吲哚酰肼(CHI),会显著降低烟草病毒病、烟草野火病和烟草赤星病的发病率,而且ZNC和CHI对生长有一定的促进作用,同时CHI还可显著提高烟叶的质量与产值.当喷施济农有机肥时,能显著促进株高和叶面积对烟株有明显的促生长作用,并且显著提高了烟叶的产量与收益.     

不同剪叶次数对“K326”烟株生长及抗性的影响

为了探究重庆市烟区不同烟苗剪叶次数对移栽前烟苗的影响,以及移栽后对烟株生长和抗性的影响,本研究以烤烟品种“K326”为材料,开展了不同剪叶次数对烟叶后期生长和抗性的影响分析.室内及田间试验结果表明,剪叶处理能够激活烟苗的植物超氧化物歧化酶(SOD)和过氧化物酶(POD)活性,使抗性相关基因ERF, GST, Oxidea和Pr1上调表达,并且在苗期能够促进根长、干物质的积累和减少烟草赤星病、烟草野火病的发生,当剪叶次数为2次时,效果最为显著,因此在生产上剪叶2次,其经济效益最佳.     

Diabetes reduces right atrial beta-adrenergic signaling but not agonist stimulation of heart rate in swine

This study assessed the effects of streptozotocin diabetes in swine on the heart rate response to beta-adrenergic stimulation the adenylyl cyclase signal transduction pathway. Diabetic animals (n = 9) were hyperglycemic compared to the control group (n = 10) (12.6 +/- 1.0 vs. 3.53 +/- 0.29 mM). There were no significant differences between the diabetic and nondiabetic groups in the heart rate response to isoproterenol, however, there was a significant reduction (14%) in beta-adrenergic receptor density in the right atrium in the diabetic (61 +/- 3 fmol/mg protein) versus the nondiabetic group (71 +/- 3) (P < 0.05). The content of guanosine triphosphate binding regulatory proteins (Gs and Gi) in the right atrium was not affected by diabetes, nor was adenylyl cyclase activity under unstimulated conditions or with receptor-dependent stimulation with isoproterenol. On the other hand, adenylyl cyclase activity was 34% lower when directly stimulated with forskolin, and it was reduced by 23% when stimulated through Gs with Gpp(NH)p. In conclusion, beta-adrenergic stimulation of heart rate with isoproteronol and the receptor-dependent signal transduction pathway remained intact in the right atrium of diabetic swine despite reduced beta-adrenergic receptor density, G-protein content, and direct stimulation of adenylyl cyclase activity.     

Structural and functional characterization of the Zn(II) site in dimethylargininase-1 (DDAH-1) from bovine brain. Zn(II) release activates DDAH-1

L-N(omega),N(omega)-dimethylarginine dimethylaminohydrolase-1 (DDAH-1) is a Zn(II)-containing enzyme that, through hydrolysis of side-chain methylated l-arginines, regulates the activity of nitric-oxide synthase. Herein we report the structural and functional properties of the Zn(II)-binding site in DDAH-1 from bovine brain. Activity measurements of the native and metal-free enzyme have revealed that the endogenously bound Zn(II) inhibits the enzyme. Native DDAH-1 could be fully or partially activated using various concentrations of phosphate, imidazole, histidine, and histamine, a process that is paralleled by the release of Zn(II). The slow activation of the enzyme by the bulky complexing agents EDTA and 1,10-phenantroline suggests that the Zn(II)-binding site is partially buried in the protein structure. The apparent Zn(II)-dissociation constant of 4.2 nm, determined by 19F NMR using the chelator 5F-BAPTA (1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid), lies in the range of intracellular free Zn(II) concentrations. These results suggest a regulatory role for the Zn(II)-binding site. The coordination environment of the Zn(II) in DDAH-1 has been examined by Zn K-edge x-ray absorption spectroscopy. The extended x-ray absorption fine structure observed is consistent with Zn(II) being coordinated by 2 S and 2 N (or O) atoms. The biological implications of these findings are discussed.     

Identification of chromosome inheritance modifiers in Drosophila melanogaster

Faithful chromosome inheritance is a fundamental biological activity and errors contribute to birth defects and cancer progression. We have performed a P-element screen in Drosophila melanogaster with the aim of identifying novel candidate genes involved in inheritance. We used a "sensitized" minichromosome substrate (J21A) to screen approximately 3,000 new P-element lines for dominant effects on chromosome inheritance and recovered 78 Sensitized chromosome inheritance modifiers (Scim). Of these, 69 decreased minichromosome inheritance while 9 increased minichromosome inheritance. Fourteen mutations are lethal or semilethal when homozygous and all exhibit dramatic mitotic defects. Inverse PCR combined with genomic analyses identified P insertions within or close to genes with previously described inheritance functions, including wings apart-like (wapl), centrosomin (cnn), and pavarotti (pav). Further, lethal insertions in replication factor complex 4 (rfc4) and GTPase-activating protein 1 (Gap1) exhibit specific mitotic chromosome defects, discovering previously unknown roles for these proteins in chromosome inheritance. The majority of the lines represent mutations in previously uncharacterized loci, many of which have human homologs, and we anticipate that this collection will provide a rich source of mutations in new genes required for chromosome inheritance in metazoans.