质粒超螺旋比例对其细胞转染效率及表达的影响

检测质粒开环、闭环比例不同时对其细胞转染效率及表达的影响。构建携带人肝细胞生长因子基因的质粒(pcDNA3-HGF)及携带LacZ报告基因的质粒(pcDNA3-LacZ),用核酸纯化试剂盒提取开环、闭环比例不同的质粒,然后用LipofectAMINE介导它们分别转染NIH3T3细胞,采用X-Gal染色和ELISA法分别观察转染效率和表达活性。结果表明,用超螺旋比例分别为85.45%和48.44%的质粒pcDNA3-LacZ转染生长旺盛的NIH3T3细胞,48h检测转染效率分别为23.4%±3.8%和9.3%±2.5%,前者约是后者的2.5倍。用超螺旋比例分别为93.28%和40.53%的质粒pcDNA3-HGF转染1×106NIH3T3细胞,ELISA法检测48h细胞培养上清中HGF的表达量分别为46.5±6.3ng和25.6±4.2ng,前者是后者的1.8倍。初步认为质粒开环、闭环比例不同对其细胞转染效率及表达有一定影响,超螺旋比例高时其转染效率及表达量较高。     

Heparin and its derivatives bind to HIV-1 recombinant envelope glycoproteins, rather than to recombinant HIV-1 receptor, CD4

We have employed a direct radiolabel binding assay to investigate the interaction between3H-heparin and recombinant envelope glycoproteins, rgp120s, derived from several different isolates of HIV-1. Comparable dose-dependent binding is exhibited by rgp120s from isolates IIIB, GB8, MN and SF-2. Under identical experimental conditions the binding of3H- heparin to a recombinant soluble form of the cellular receptor for gp120, CD4, is negligible. The binding of3H-heparin to rgp120 is competed for by excess unlabeled heparin and certain other, but not all, glycosaminoglycan and chemically modified heparins. Of a range of such polysaccharides tested, ability to compete with3H-heparin for binding was strictly correlated with inhibition of HIV-1 replication in vitro. Those possessing potent anti-HIV-1 activity were effective competitors, whereas those having no or little anti-HIV-1 activity were poor competitors. Scatchard analysis indicates that the K d of the interaction between heparin and rgp120 is 10 nM. Binding studies conducted in increasing salt concentrations confirm that the interaction is ionic in nature. Synthetic 33-35 amino acid peptides based on the sequence of the V3 loop of gp120 also bind to heparin with high affinity. V3 loop peptides that are cyclized due to terminal cysteine residues show more selective binding than their uncyclized counterparts. Overall, these data demonstrate further that heparin exerts its anti-HIV-1 activity by binding to the envelope glycoprotein of HIV-1, rather than its cellular receptor, CD4. This study confirms that the V3 loop of gp120 is the site at which heparin exerts its anti- HIV-1 activity. Moreover, it reveals that high affinity binding to heparin is shared by all four rgp120s examined, despite amino acid substitutions within the V3 loop.      

红松人工林优势木竞争指数影响因子

在温带湿润气候区东段不同立地条件下的红松人工林内设置面积为600 m~2(20 m×30 m)的70块矩形固定样地。在每个样地内,选取5颗最高且长势较好的优势木作为研究的对象木,用Voronoi图确定优势木相应的竞争木,测定每一块样地内优势木与竞争木之间的距离。采用Hegyi单木竞争指数模型,分析优势木在不同样地水平上的种内竞争强度,探讨林分生长因子、地形因子、土壤养分因子对优势木竞争指数的影响,并对这3类因子与优势木竞争指数进行相应的拟合和相关性分析。结果表明：红松人工林优势木竞争强度随着优势木胸径的增大而变小,并且两者之间的关系服从幂函数;红松优势木的竞争指数与其树高、胸径、冠幅呈极显著的相关关系(P<0.01);坡向、坡位、海拔对竞争指数影响极显著(P<0.01);红松人工林优势木竞争指数的大小与土壤氮磷钾含量均呈极显著的相关关系(P<0.01);pH值对优势木竞争指数的影响不显著。当红松人工林优势木平均胸径达到45cm,优势木平均树高和冠幅大于周围竞争木时,其对周围资源的利用程度增大,林木会发生自然稀疏现象,其所受的竞争压力减小。红松喜光性强,对水分的要求高,...     

海拔高度对2型糖尿病患者循环内皮祖细胞及低氧诱导因子的影响*

目的: 探讨不同海拔地区2型糖尿病患者循环内皮祖细胞数量及相关检测指标的变化情况,为2型糖尿病血管并发症的研究和治疗提供依据。方法: 选取386 m低海拔地区(咸阳市)和1 520 m高海拔地区(兰州市)各一家医院内被诊断的2型糖尿病患者(25人/29人)和健康体检者(20人/20人)。用全自动生化分析仪检测两组人群的血脂、血糖和糖化血红蛋白指标,用酶联免疫吸附试验(ELISA)检测低氧诱导因子-1α(HIF-1α)的浓度,用流式细胞仪测定外周血循环内皮祖细胞(EPCs)的数量。结果: 无论在低海拔还是高海拔地区,糖尿病组较健康组循环EPCs数量降低(P＜0.01),体质指数(BMI)、腰臀比(WHR)、甘油三酯(TG)、空腹血糖(FBG)及糖化血红蛋白含量(HbAlc)增高(P＜0.05);与低海拔组相比,无论高海拔的糖尿病患者还是健康者,HIF-1α的表达水平均明显增加(P＜0.05),而循环EPCs数量明显降低(P＜0.05),且有循环EPCs数量健康者高于2型糖尿病无血管并发症者高于2型糖尿病伴血管并发症者的表现(P＜0.05)。结论: 海拔高度增加,2型糖尿病(T2DM)患者体内HIF-1α表达水平增加,循环EPCs数量降低,且与其血管病变程度密切相关。因此有望通过对高海拔地区T2DM患者进行EPCs的移植来实现对糖尿病血管并发症的预防和改善。     

微塑料对湖泊生态系统初级生产者的影响

塑料的广泛应用导致大量微塑料进入环境,尤其是水环境,从而产生环境风险。浮游植物等自养生物是湖泊系统的主要初级生产者,是湖泊食物链的关键组成部分,为食物链的上游提供能量和物质基础。同时,浮游植物也是对微塑料响应最敏感的类群。了解湖泊浮游植物等初级生产者对微塑料的响应是探究微塑料对湖泊生态系统功能影响的重要基础。总结了全球湖泊生态系统微塑料的丰度、类型、尺寸、来源等分布特征,系统分析了微塑料暴露对浮游植物等初级生产者细胞结构、基因表达和生长,以及对浮游植物叶绿素a含量、光合活性的影响,并总结了其中的影响机制。总体而言,微塑料会降低初级生产者的叶绿素a含量,剂量越高、尺寸越小,这种抑制作用越强烈;同时,微塑料也会作用于初级生产者,造成细胞膜损伤、DNA损伤,调控其相关功能基因表达,抑制其生长和光合活性等。然而,湖泊生态系统微塑料的实际检出浓度远低于室内暴露实验中的添加剂量,微塑料结构和组分也更为复杂,野外观测结果与室内培养实验之间还不能建立直接的对应关系。因此,未来的相关研究应集中在如何有效联系野外观测结果与室内培养实验结果,进一步聚焦建立可靠的、可应用推广的微塑料浓度与初级生产者之间的剂量-效应关系模型,探究微塑料对湖泊初级生产者的作用机制,为刻画微塑料对湖泊生态系统初级生产者及其功能的作用机制提供科学支撑。     

Double intratibial injection of human tonsil-derived mesenchymal stromal cells recovers postmenopausal osteoporotic bone mass

Background and aims

Osteoporosis, which is a disease characterized by weakening of the bone, affects a large portion of the senior population. The current therapeutic options for osteoporosis have side effects, and there is no effective treatment for severe osteoporosis. Thus, we urgently need new treatment strategies, such as topical therapies and/or safe and effective stem cell therapies.

Inhibition of germination of dormant barley (Hordeum vulgare L.) grains by blue light as related to oxygen and hormonal regulation

Germination of primary dormant barley grains is promoted by darkness and temperatures below 20 °C, but is strongly inhibited by blue light. Exposure under blue light at 10 °C for periods longer than five days, results in a progressive inability to germinate in the dark, considered as secondary dormancy. We demonstrate that the inhibitory effect of blue light is reinforced in hypoxia. The inhibitory effect of blue light is associated with an increase in embryo abscisic acid (ABA) content (by 3.5‐ to 3.8‐fold) and embryo sensitivity to both ABA and hypoxia. Analysis of expression of ABA metabolism genes shows that increase in ABA mainly results in a strong increase in HvNCED1 and HvNCED2 expression, and a slight decrease in HvABA8′OH‐1. Among the gibberellins (GA) metabolism genes examined, blue light decreases the expression of HvGA3ox2, involved in GA synthesis, increases that of GA2ox3 and GA2ox5, involved in GA catabolism, and reduces the GA signalling evaluated by the HvExpA11 expression. Expression of secondary dormancy is associated with maintenance of high embryo ABA content and a low HvExpA11 expression. The partial reversion of the inhibitory effect of blue light by green light also suggests that cryptochrome might be involved in this hormonal regulation.     

RevSex duplication-induced and sex-related differences in the SOX9 regulatory region chromatin landscape in human fibroblasts

It was recently shown that duplications of the RevSex element, located 0.5 Mb upstream of SOX9, cause XX-disorder of sex development (DSD), and that deletions cause XY-DSD. To explore how a 148 kb RevSex duplication could have turned on gonadal SOX9 expression in the absence of SRY in an XX-male, we examined the chromatin landscape in primary skin fibroblast cultures from the index, his RevSex duplication-carrier father and six controls. The ENCODE project supports the notion that chromatin state maps show overlap between different cell types, i.e., that our study of fibroblasts could be of biological relevance. We examined the SOX9 regulatory region by high-resolution ChIP-on-chip experiments (a kind of “chromatin-CGH”) and DNA methylation investigations. The RevSex duplication was associated with chromatin changes predicting better accessibility of the SRY-responsive TESCO enhancer region 14–15 kb upstream of SOX9. Four kb downstream of the TESCO evolutionary conserved region, a peak of the enhancer/promoter-associated H3K4me3 mark was found together with a major dip of the repressive H3K9me3 chromatin mark. Similar differences were also found when three control males were compared with three control females. A marked male/female difference was a more open chromatin signature in males starting ~400 kb upstream of SOX9 and increasing toward the SOX9 promoter. In the RevSex duplication-carrier father, two positions of DNA hypomethylation were also found, one corresponding to the H3K4me3 peak mentioned above. Our results suggest that the RevSex duplication could operate by inducing long-range epigenetic changes. Furthermore, the differences in chromatin state maps between males and females suggest that the Y chromosome or X chromosome dosage may affect chromatin conformation, i.e., that sex-dependent gene regulation may take place by chromatin modification.     

Complex temporal decay: a complete analysis

Relaxation dynamics is universal in science and engineering; its study serves to parameterize a system's response and to help identify a microscopic model of the processes involved. When measured data for a phenomenon cannot be fitted using one exponential, the choice of an alternative function to describe the decay becomes nontrivial. Here, we contrast two different, but fundamentally related approaches to fitting nontrivial decay curves; exponential decomposition and the gamma probability density function. Copyright © 2013 John Wiley & Sons, Ltd.     

Extrapontine myelinolysis presenting as acute parkinsonism

Background

Extrapontine myelinolysis presenting with extra pyramidal features suggestive of parkinsonism may be a challenging clinical syndrome. Clinicians should maintain their vigilance while correcting electrolyte imbalances, especially with associated co-morbidity.

Case presentation

A 41-year-old woman presented with acute parkinsonism like features while on a holiday. This followed slow correction of hyponatraemia after repeated vomiting. MRI changes were suggestive of Extrapontine myelinolysis(EPM). This case is at variance with four previous cases reported in the medical literature in that the patient made a full clinical recovery and the MR changes resolved with symptomatic support alone.

Conclusion

Extrapontine myelinolysis could make a complete recovery with symptomatic support alone. During hyponatraemia correction, rapid osmotic shifts of fluid that cause hypernatremia, causes myelinolysis rather than absolute serum sodium level. Even gradual correction of hyponatraemia can produce myelinolysis, especially with pre-existing malnourishment, alcoholism, drug misuse, Addison's disease and immuno-suppression. Pallidial sparing is typical of EPM in MRI scans.